Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~o705~7
APPA~ATUS ~OR VARIATION OF SPEED
The present invention relates to a mechanical
~ransmission device.
It more specifically relates to a friction trans-
mi~sion device for transferring a mechanical power between
coupling means and a coupling member having a rotary move-
ment without creating an axial torque on the coupling member
or on the coupling means.
PRIOR ART
l¢ Friction transmission devices are ~nown which have
an input shaft an~ an output shaft coupled to rotary members,
cooperating via rolling surfaces and comprising means for
modifying the r~lative position of the rolling surfaces in
such a way as to vary the transmission ratio.
Transmission devices or variable drives of this type
ha~Je ~een more particularly described in Canadian Patent No.
99~,857, issued October 26, 1976 to Vadetec S.A.
Such transmis~ion devices comprise:
a3 a frame;
b) a first member comprising two rolling surfaces
revolving about a first axis fixed relative to the frame,
located (preferably symmetrically) on either side of a plane
perpendicular to the first axis at a point S of said axis;
c) a second member comprising at least two rolling
surfaces revolving about a second axis coinciding at point
S with the first axis and forming with the latter an angle
a, located (preferably symmetrically) on either side of a
p7 ane perpendicular to the second axis at the point S of
said axis;
.~ . .
` ~7~527
d) supporting means mounted so as to move at a
speed relative to the frame, supporting the second member
in such a way that the latter can rotate on itself about
the second axis at speed ~ in such a way that the movement
of the second member about the point S is the combination of
a rotation movement at speed ~ about the second axis and a
conical movement of apex S at speed ~ of the second axis
a~out the first axis;.
e) first connecting means between, on the one
10 hand, the coupling means comprising a main drive shaft and
on the other hand the second member or the supporting means
(in the circumstances, these connecting means are more
particularly constit~ted ~y an extension having a prismatic
cross-section integral with a main drive shaft) in such a
way that the coupling means actuate the conical movement of
the second member (or conversely are actuated by the second
member);
f) second connecting means between a coupling
member comprising a main drive shaft and one of the following
20snembers: the second member or the first member (in the
circumstances these connecting means more particularly
comprise a homokinetic joint located between the second member
and a rnain drive shaft);
g) a mechanical system applying the rolling
surface of the secon~ mem~er against the rolling surface of
the first member at two points P~, P2 located on either side
of ~he first axis and the second axis (in the case of the
known transmission device described in ~forementione~ Canadian
Patent ~o. 998,857, this mechanical system comprises gyroscopic
means);
107~527
h) means for modifying the position of the contact
points between the rolling surfaces in such a way as to
vary the transmission ratio between the movement frequency
of the coupling means and the movement frequency of the
coupling member.
A transmission device of this type is particularly
well suited for the transmission of high power by creating
in a particularly simple manner (by means of the gyroscopic
means) the normal contact pressure between the first member
10 ana the second member, whilst avoiding (due to the subdividing
into two of the rolling surface~ on either side of the point
S) the application of axial forces on the one hand to the -
coupling member and to the coupling means constituted by
the main drive shafts and the other, the bearings supporting
the second member or the first member.
Moreover, due to the means for modifying the p~sition
of the contact points ~comprising varying the slope of angle
a of the second axis relative to the firs~ axis) it is possi~le
to vary the ratio of the input speeds and the output speeds.
However, no matter how elaborate this transmission
device, it has certain disadvantages, which can be relatively
troublesome in certain constructional variants.
These disadvantages are due to the fac~ that, in
the prior art, transmission devices it is necessary to
provide a degree of freedom in the radial direction parallel
to the meridian plane of the first and second axes, in such
~ way that the second member can, under the action of the
tor~ue created by the gyroscopic means, tilt and engage
against the first mem~er.
107V5Z7
~ he necessity of providing a tolerance in a radial
direction leads to the following disadvantages: firstly,
the second member can oscillate radially when it rolls on
the first member, whereby said radial oscillations of the
second member can damage the rolling surfaces and cause
lack of stability of the oil film in the contact area of the
rolling surfaces, whilst said oscillations also cause
fluctuations to the contact pressure which are prejudicial
to the satisfactory operation of the transmission device~
Secondly, there is no doubt that it is often
difficu~t, if not impossible, to obtain mechanical connec-
tions (more particularly by gears) between two members which
have an uncertain gap between them. This problem of mechani-
cal connections is in the case of the transmission devices
according to the present invention a serious problem which
have at least two effects: on the one hand, it is necessary
to provide in certain constructional forms, mechanical con-
nections between the second member (or a member associated
with the second member such as supporting means) and
20 auxiliary mechanisms which it is necessary to drive at speeds
which are synchronous with the speed ~ of the second axis
about the first axis.
On the other hand, it is necessary to provide in
the case o~ transmission devices according to the invention,
first and second connecting means between the coupling means,
the coupling members and the first mem~er, second member and
su~porting means, whereby it is also necessary to provide
in the case of certain constructional variants, other connect-
ing means between the frame and the second member in order
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- 1~70527
more particularly to stop the rotation of the second member
(in such a way that ~ = 0, /a~ = /~ /).
It is pointed out in this connection that ~ is the
rotation speed of the second member on itself, about the
second axis, measured in an absolute reference mark linked
to the frame, ~ is the rotation speed of the second member
measured in a rotary reference mark linked to the first axis
and to the second axis, whilst the algebraic relationship
O* O O
~ a
10 exists between ~ and ~ . Consequently, in the case where
~ z O, the second member is fixed against rotation about ~he
second axis and relative to the frame, but it translates in
nutation at the speed a relative to the first axis.
The necessity of maintaining a radial degree of
freedom thus complicates the construction of the mechanical
connections.
Thirdly, it is necessary to stress that mechanically
the gaps (and the resulting oscillations) are often a source
of los~es by mechanical friction or a source of wear. A
20 fundamental quality of a good transmission device is good
efficiency.
THE OBJECT OF THE PRESENT INVENTION
-
The object of the present invention is to provide
a transrnission device having the same advantages as the known
transmission devices, but which does not have the disadvantages
descri~ed herein~e~ore.
In other words, the present invention relates to
transmission devices of the type described hereinbefore which
are able to transmit hiqh power, whilst keeping the roll~ng
.'
~0705'~7
surfaces engaged with one another, without sliding and without axial forces
of reaction being created and which permit a simple and rapid variation of
the transmission ratio.
With reference to these transmission devices, the problem solved
by the invention, is to as far as possible eliminate the disadvantageous
consequences due to the more or less uncertain clearances between the rolling
surfaces.
THE TRANSMISSION ~EVICE ACCORDING
TO THE PRESENT INVENTION
According to the present invention, there is provided in a trans-
mission device having a frame, drive input means, and drive output means,
means interconnecting said input and output means comprising: a first element
on a first axis fixed in the frame and having rolling surfaces of revolution
about said first axis, one such rolling surface on each side of a first plane
perpendicular to said first axis at a point of axes intersection; a second
element on a second axis intersecting said firs~ axis at said point of axes
intersection ant having concentric journal and rolling surfaces of revolution
about said second axis, the rolling surfaces of said second element being
disposed one on each side of a second plane passing through said point of
axes intersection and perpendicular to said second axes intersection and
perpenticular to said second axis; support means rotatable on said first axis
and journalled with said journal surfaces to support said second element for
movement in a biconical path circumferentially of said first axis, the apex
of said biconical path being coincident with said point of axes intersection;
the respective rolling surfaces on said first and second elements being in
r~lling frictional engagement at two points of contact in a third plane con-
taining said first and second axes and located one on each side of said first
plane; the rolling surfaces of at least one of said elements being defined by
generatrices inclined oppositely with respect to the axis of revolution there-
of and symmetrically with respect to said point of axes intersection, thereby
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1~70527
to provide in the respective rolling surfaces of said first and secondelements a variable ratio of rolling surface radii at said points of contact
for variation in the spacing of said points of contact from said point of
axes intersection; and means for forcing said respective rolling surfaces on
said first and second elements into rolling friction engagement with each
other at said two points.
These supporting means can be constructed in different ways~
Hbreinafter,special embodiments will be described with reference to the
drawings. They can, for ex~mple, comprise at least two series of bearings,
the first permitting a rotation of the second member relative to the frame
and the second permitting a rotation of the second member relative to the
supporting means about the second axis, said two series of bearings being
inclined relative to one another.
Due to this arrangement of the supporting means and the fact that
the second element moves in a biconical path, it is obvious that one of the
main causes of the uncertain radial clearance between the rolling surfaces
is eliminated. Moreover, this simplifies the connections between the coupling
member or the coupling means and the second member or the supporting member,
because henceforth, the latter are oriented in fixed directions relative to
the frame.
Because the second element moves in a biconical path circumferential-
ly of the first axis, the slope angle a of the second axis relative to the
first axis is fixed. This means that, contrary to what happens in the prior
art transmission device, the second member cannot swing around the point of
axes intersection S relative to the first member. It also ~eans that the
orientations in the space of the second axis relative to the first axis have
no degree of freedom. It should also be noted, however, that this does not
exclude the case where the slope angle a is adjustable. That is to say that
when the second axis can assume several different inclinations relative to
the first axis and where for each of these inclinations (caused directly or
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1070527
indirectly by an appropriate mechanism, more particularly in order to modify
the transmission ratio, for example) the second member has no degree of
oscillating freedom relative to the first member.
As the ideas which have just been developed are relatively
complex, it is perhaps necessary to study them from a different angle
based on a mechanical analysis of the forces applied at the contact points
of the rolling surfaces.
In the first case, i.e. the case of a prior art transmission
device ~in the case where the slope angle a has a degree of freedom)
a mechanical torque is applied to the first or second member and generates
at the contact points of the rolling surfaces a force and therefore a
pressure which, in normal operation, prevents the sliding of the rolling
surfaces relative to one another.
In the second caseJ i.e. with the transmission device according
to the present invention~in the case where the slope angle of the second
axis relative to the first axis, is fixed, no matter whether it is adjust-
able or not) a torque applied to the second member produces no normal
force or pressure at the contact points because movement about point S
6f the second member relative to the first member is prevented. Therefore,
in this case, different mechanical systems are used for applying the
rolling surfaces of the second member against the rolling surfaces of the
rotary member.
COMPLEMENTARY PROBLEMS AND THEIR SOLUTIONS
In complementary manner, the preferred embodiments of the
components forming the transmission device are more specifically designed
in such a way that the transmission device has at least the same advantages
as the prior art transmission devices.
Thus, in embodiments of the transmission device, the following
complementary pro~lems have also ~een solved:
the problem of varying the transmission ratio without modifying
... ..
1070527
the slope angle a (point 1), whereby in order to simplify the mechanical
connections between the moving members and the coupling members or the
coupling means, it is desirable to avoid any variation in the slope angle
~i
the problem of creating the contact pressure at the contact
point between the ~olling surfaces ~point 2), whereby said problem is
preferably solved in combination with the problem of varying the trans-
mission ratio;
the problem of the mechanical connections (point 3);
the problem of balancing the forces of reaction on the
bearing supporting the second member (point 4);
the problem of balancing the forces of reaction on the frame
(point 5).
In order to simul~aneously solve these different problems
and the fundamental problem of the present invention, novel members have
been designed or the prior a~t members have been adapted, modified,
operated and combined with the supporting members in such a way that it
is simultaneously possible to achieve often contradictory objectives.
Thus: point 1)
To solve the complementary problem of a variation of the
transmission ratio without modifying the slope angle a, the rolling sur-
faces of one of the two members are generally conical and have a half-
angle at the apex which is substantially equal to the slope angle of the
second axis relative to the first axis, whilst the rolling surfaces of
the other member have a substantially annular configuration.
~he term "generally conical" signifies that the generating
curves of the rolling surfaces, viewed in a meridian p~ane passing through
the axis of revolution of the rolling surfaces do not greatly vary from
a straight line. This also means that the angles of the tangents of these
generating curves, relative to the axis of revolution do not vary very much
10705Z7
from an average value called the "half-angle or apex angle of the cone."
Thus, the terms "half-angle or apex angle of the cone" must
not be understood in the strict sense of the word and must not be limited
to the simple designation of "cones" or "truncated cones, " whose generating
lines are straight lines. These terms have been used for ease of reference,
making it necessary to redefine their geometry whenever the shape of the
rolling surfaces is mentioned.
In the same way the term "annular," used for qualifying the
shape of the other rolling surface, must not be understood as limited to
strictly cylindrical structures. In other words, the annular rolling
surfaces, namely the functional parts of the annular rolling surfaces which
come into contact with the conical rolling surfaces, are substantially
cylindrical (the average tangent at their generating line being substantially
parallel to their axis of revolution).
It is obvious that the combination of generally conical
rolling surfaces and annular rolling surfaces can lead to the same
result as strictly conical and cylindrical rolling surfaces (i.e. the
modification of the transmission ratio without modifying slope angle ~,
whilst providing the complementary advantages which will be
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. ...
107~527
described with reference to specia7 embodiments. The terms
~conical, n "conically shaped," "with a generally conical
configuration, n "annular" and "cylindrically shaped" must
not be understood in their strict sense and wherever they
are used, they must be interpreted so as to take account
of what has been said hereinbefore.
As a result of this arrangement and construction
of the rolling surfaces, there is no need to modify the slope
angle of the second axis relative to the first axis for varying
10 the transmission ratio. It is in fact sufficient to axially
move the substantially rolling surfaces and/or the conical
rolling surfaces relative to one another to modify the position
of the contact points Pl and P2 and therefore the transmission
ratio.
Reference is briefly made to the principle of this
transmission ratio variation mechanism: the kinematic
equation also called transmission equation is:
o o o o Rl
~ - + (a ~' ~) R =
or:
o O O* R
~ - -'~ Rl =
in which:
designates the speed of the second axis about the
first axis,
~ designates the rotation speed of the second member
a~out the second axis, measured in an absolute reference mar~
lin~ed with the frame;
~,*
B designates the rotation speed of the second member
a~out the second axis in a rotary reference mar~ linked to
the first axis and to the second axis;
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10705Z7
~ designates the rotation speed of the first m~mber
about the first axis when the latter is, in the case of certain
variants, mounted so that it rotates relative to the frame;
Rl designates the radius of the circle described
by one of the contact points on the considered rolling surface
of the second member;
R2 designates the radius of the circle described
by one of the contact points on the considered rolling
surface of the fi~st member.
This equation was def~ned by the Applicant in
the aforementioned Canadian Patent No. 998,857.
It is clear that a modification of the position
of contact points Pl and P2 causes a variation in the ratio
of Rl/R2 and therefore a variation in the ratio between any
O O O
two of the speeds a, ~ and ~. It will be shown hereinafter
how it is possible to remove the indefiniteness appearing
in the case where the first member is mounted in rotation
at the speed ~.
In this connection, it is pointed out that this
20 special conical shape of the rolling surfac~s is known per
se. Rolling surfaces having such a conical shape are speci-
fically described in U.S. Patents No. 2,319,319 ~GRAHAM),
~o. 2,535,409 (GRAHAM) and No. 2,405,957 ~JONES). However,
it is essential to point out that the transmission devices
described in these U.S. patents only have a single series
of rolling surfaces. In other words, they do not have the
essential characteristics of the transmission devices covered
by the present invention; namely, that the rolling surfaces
are subdivided into two and located on either side of a
point 5, whilst the slope angle a is strictly fixed.
10705Z7
Admittedly, in the case of the GRAHAM transmission
device of U.S. Patent No. 2,535,409, a conical planet wheel
is forced and locked against an annular ring by means of
wedges but on the one hand such means would appear to he
incompatible with a subdivision into two of the rolling
surfaces (it is virtually impossible to forced-support a
member at four points) and on the other would be unable to
prevent, even if arranged symmetrically relative to a point
S, the development of an axial reaction component ~it is
10 virtually impossible to strictly balance the forces of
reaction brought about by a member supporting by force at
four poin~s).
Moreover and correlatively, the means (wedges)
provided in the GRAHAM transmission device of U.S. Patent
No. 2,535,409 do not maintain constant the slope angle a.
In fact, they imply a certain elasticity of the planet wheel
and therefore a certain variation of the angle a, without
which it would not be possible to maintain the planet wheel
supported against the annular ring.
These essentially structural differences lead to a
large number of disadvantages which are not found in the
transmission device according to the present invention and
these are more particularly: the bearings which support the
rotating members must be designed so as to resist the axial
forces; the mechanical connections between the rotating
members and the frame must ~e designe~ so as to permit the
variations of the slope angle a and are a source of oscilla-
tions or losses which decrease the efficiency of the trans-
mission device.
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~,~
,. ~
107~5Z7
In our Canadian Patent No. 1,031,984, granted
May 30, 1978, the applicant also described conical and annular
rolling surfaces. This patent which was still not published
on the priority date of the present application, is referred
to here for information purposes.
In the case of this latter patent, the rolling
surfaces are subdivided into two, so that the problem of
balancing the axial reaction forces is solved. However,
the slope angle a has a certain degree of freedo~, i.e. the
second member is mounted with a slight clearance so that
it can swing and engage against the first member.
Thus, this transmission device, although it is an
improvement because it makes it possible to vary in simple
manner the transmission ratio, still has the disadvantages
associated with possible random variations in the slope
angle a.
According to a further complementary characteristic
hhich may contribute to solving the problem of varying
the transmission ratio, the annular rolling surfaces may be
mounted so as to be axially movable and the means for
modifying the position of the contact points between the
rolling surfaces comprise members for actuating the annular
rolling surfaces.
As a result of this special construction, it is
possible to vary the transmission ratio by axially displacing
the annular rolling surfaces along the generating line of
the cone parallel to the axis of revolution of the annular
rings.
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" "
.j . -~
,. ... ,: :,
1070527
A~cording to another feature relative to another
embodiment, the annular rolling surfaces are mounted in
axially movable manner and the means for modifying the
position of the contact poin~s between the rolling surfaces
comprise members for axially actuating the conical rolling
surfaces mounted in axially movable manner.
As a result of this special construction, the gap
between the second member and the first member is modified
symmetrically or asymmetrically in such a way that in the
10 first case the annular rolling surfaces actuated by the system
creating the contact pressure can move until they abut against
the conical rollin~ surfaces or in such a way that in the r
second case, the contact pressures at Pl and P2, on either
side of the point S are unbalanced and give rise to an axial
component which is able to displace the annular rolling
surfaces. It is clear that the general solutions and special
preferred embodiments described hereinbefore are perfectly
compatible with the means making it possible to keep fixed
the slope angle a, because they specifically aim at main-
20 taining slope ang~e a constant.
It is also certain that the solutions described
hereinbefore and which solve the problem of varying the
transmission ratio also contribute to solving the fundamental
problem of the present invention. Thus, it is easier to
prevent radial clearances between the second and ~irst
m~mbers, maintaining the slope angle a fixed because there
is no need to vary the angle _ in order to modify the trans-
mission ratio. In other words, it is easier to prevent
10705Z7
annular clearances between two members when their angular orientation
is defined once and for all. Thus, the solution adopted for solving
the problem of the variation of the transmission ratio is not independent
of the solutions of the fundamental problem of the present invention,
in fact they cooperate with one another.
However, it should be noted that this solution of the problem
of varying the transmission ratio applies no matter whether the angle a
is fixed or not. Reference has already been made to an earlier-dated
patent of the present applicant, namely No. 1,031,984, which specifically
describes ~ariants of effecting this solution in the case where the
slope angle a has a certain degree of freedom.
Moreover, as will be seen more particularly in point 3
~, hereinafter and during the detailed description of special embodiments,
this solution of the problem of the variation of the transmission ratio
by conical rolling surfaces can be utilized with a wide variety of systems
creating the contact pressure.
Therefore, the solution involving the conical rolling surface
tescribed hereinbefore has a broad scope and can be claimed in a more general
manner, i.e. other than in combination with special systems for creating
the contact pressure (gyroscopic system) described in the above-mentioned
Patent No. 1,031,984.
To solve the problem of creating the contact pressure: the
rolling surfaces of one of the members may be mounted in axially movable
manner and the system which applies the rolling surfaces against one
another may comprise means for axially actuating the rolling surfaces
mounted in axially movable manner.
This system construction which creates the contact pressure at
contact points Pl and P2 is not independent of the fundamental characteristic
of the present invention which consists of maintaining the angle a fixed.
Thus, with the angle a maintained fixed, it is no longer
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~'
...
10705Z7
possible to envisage the bringing into contact of the rolling surfaces
and the creation of the contact pressure according to the prior art by
the second member freely swinging about point S.
Thus, the mechanical system must be designed in such a way
that the second member is applied against the first member without a
free angular variation of angle a being necessary.
1~70527
This is the case in the system describea hereinbefore
which comprises axially displacing the rolling surfaces of
one of the members without changing angle _.
French Patent No. 1,227,486 (HEUR~EL) describes a
transmission device comprising a conical roller which can
displace axially by a small amplitude under the action of a
spring.
It should be noted however: on the one hand that
this transmission device is not of the type covered by the
10 present invention because it does not have two pairs of
rolling surfaces arranged symmetrically in such a way that
the axial forces of reaction are eliminated and on the other
said swing which axially actuates the rolling surfaces does
not create a contact pressure and in fact belongs either to
a disengaging mechanism or to a wear-compensation mechanism.
In other words, the spring according to the teaching
of the above French patent does not have the function of
developing a contact pressure between the roller and the
ring so as to ensure their driving without sliding. It must,
20 in fact, be remembered that in the case of the HEURTEL trans-
mission device, driving is produced by "simple adhesion" of
the smooth surfaces (line 4, left-hand column of page 3).
It should be noted here that the fact that the
contact pressure is created by a system which is independent
of the ~inematic operating conditions provides the advantage
of permanently maintaining an ade~uate contact pressure,
~, c~ ~
even in transient states when the speed-. ~, 2 and ~ can
vary. In the case where this system comprises gyroscopic
1~705Z7
means according to the teaching of aforementioned Canadian
Patent No. 998,857 it is sensitive to accidental variations
of the kinematic conditions. In this connection, the use of
an independent system constitutes an advantage compared with
that used in the prior art.
It should also be noted that the fact that angle
a is fixed facilitates the provision of the independent system
for creating the contact pressure. Therefore, as the second
member always has a fixed orientation, it is possible to
10 utilize it for pressing the rolling surfaces thereof. In
other words, the fact that the slope angle a is fixed cooperates
with the other structural dispositions Gf the transmission
device in order to facilitate the realizations of the systems
creating the contact pressure.
The system for creating the contact pressure can
be realized in various ways.
In the case of certain embodiments, the means for
axially actuating the said rolling surfaces mounted in axially
movable manner can have an inertial origin. In this case,
~0 the rolling surfaces mounted in axially movable manner are
preferably those of the second member and are ~ormed on two
annular rings, whose axis is the second axis, inserted between
the first member and the second member and integral in rotation
O*
at the speed ~ , of the second member.
For example, the means having an inertial origin
can comprise annu~ar rings having a mass and geometry, as
well as rolling surfaces of the first mem~er having a pro~ile
such that two axia7 forces are ~eve70ped and have the effect
_ ~9 _
~F f
1070527
of axially displacing the annular rings towards the rolling
surfaces of the first member and of creating the contact
pressure.
In the case of other embodiments, the means for
actuating the rolling surfaces mounted in axially movable
manner can comprise an elastic system. In this case
preferably:
the rolling surfaces of the second member are
mounted in axially movable manner;
the rolling surfaces of the first member are two
truncated cones juxtaposed by their base, whose apex half-
angle is slightly less than the slope angle a of the second
axis relative to the first axis;
the means for axially actuating the two rolling
surfaces of the second member against those of the first
member by creating the contact pressure comprise two elastic
systems, each supported on the one hand on the second member
and on the other on the rolling surfaces of the second axially
movable member.
~0 In the case of other embodiments, the means for
ac~uating the rolling surfaces mounted in axially movable
manner with a view to creating the contact pressure comprise
ra~ps and in this case preferably:
the two rolling surfaces of the second member
surround the first member;
the two rolling surfaces of the first member,
mounted in axially movable manner on the first member are two
trllncated cones juxtaposed by their base, whose apex half-
angle is equa~ to the slope ang~e a of the second axis
relative to the first axis;
- 20 -
10705Z7
the means for axially actutating the rolling surfaces
of the first member against the rolling surfaces of the
second member comprise a system of ramps integral with the
first member and cooperating with complementary ramps integral
with the rolling surfaces of the first member.
More specifically, in this case, the ramps are of
the helical type, in such a way that the rolling surfaces of
; the first member are automatically screwed onto the first
member during the operation of the transmission device.
These special constructions of the system which
creates the contact pressure by means of ramps integral with
the members (integral with the first or second members) have
the substantial advantage of preventing relative slipping
of the rolling surfaces under the action of the output
torque (or a driving or reactive torgue) of an excessive
nature. Thus, the contact pressure created ~y such a system
of ramps is directly proportional to the output torque, so
that the contact pressure is continually adapted to the
value of this torque, whatever it is.
It must~be stressed that the problem of varying
the transmission ratio cannot be solved independently at
that of creating the contact pressure, because in one case
it is a question of finding solutions permitting the modifi-
cation or the position of contact points Pl and P2 and in
the other it is a question of finding a solution which
permits the creat~on of the contact pressure at ~hese points.
However, the great advanta~e of the solutions defined herein-
before is that they are compatible with one another.
- 21 -
~07~527
Thus, for example, it is possible to combine the
inertial actuating means for the annular rolling surfaces
and creating the contact pressure with the members permitting
the axial actuation of the conical rolling surfaces with a
view to modifying the position of the contact points.
In the same way, it is possible to combine the
elastic systems actuating the ann~lar rolling surfaces,
with a view to creating the contact pressure, with the mem~ers
which axially actuate the conical rolling surfaces. For
10 example, in this case, these members can be of the hydraulic
type and comprise tight chambers able to receive a pres-
surized fluid.
Moreover, it is possible to combine the systems of
; ramps actuating the conical rolling surfaces, with a view
to creating the contact pressure, with the members which
axially actuate the annular rolling surfaces with a view to
mod~fy~ng the position of the contact points. For example,
~n th~ 8 case, the members can comprise connections by gear
trains. However, other permutations and combinations are
20 possible without passing beyond the scope of the present
invention.
An explanation is provided here of an apparent
duplication of the members comprising the transmission device.
~t wou~d in fact appear that the transmission dev~ce comprises
two members ~on the one hand the system crea~ing the contact
pressure and on the other the means for modifying the position
of the contact points between the rol~ing surfaces) haYing
at least in the case of certain embodiments a comparible
10705Z7
function, namely that of axially actuating the rolling surfaces
of one and/or the other of the members relative to one
another. However, in connection with these embodiments it
18 important to note that:
one of these members ~namely the system creating
the contact pressure) axially actuates the rolling surfaces
of the member in question without in practice displacing
them, in such a way as to create the indispensible contact
pressure, the action thereof being permanent;
the other, (namely the means for modifying the
position of the contact points) modifies the axial position
of the rolling surfaces in such a way as to modify the ~l/R2
ratio of the radii of the circles described by the contact
points on the rolling surfaces of the second meSmber relative
to the radii of the circles described by the contact points
or the rolling surfaces of the first member, said means
only being used when it is necessary to vary the transmission
ratio, so that their action is temporary.
Point 3).
The problem of the mechanical connections occurs
repeatedly relative to a transmission device according to
the invention.
On the one hand between the coupling means and the
second member or the supporting means, on the other between
the coupling member and the first member or the second member
and finally ~etwee~ the second memSber and the frame or between
the second member and the first member so as to lin~ the
c> o * r
speeds ~a, ~ or at least two of them.
- 23 -I
'
s~
10705Z7
Moreover, the problem of the mechanical connections
is occurring between the auxiliaries of the transmission
device or the motor operating the transmission device and
the second member (for the supporting means) in order to
synchronize the operation of the auxiliaries with those
of the transmission device~
~ he problem of the mechanical connections involve
different solutions depending on the advantages which it
is desired to obtain or depending on the disadvantages which
it is desired to avoid. Moreover, different solutions can
be envisaged according to the nature of the members which are
to be connected or, alternatively, the same solution can
~e used for connecting members of a different type.
a) In order to solve the problem of the mechanical
connections, a particularly simple solution can be achieved
when the second member is inclined by the constant angle and
! consists of using conical gears of apex S. This solution
can be used for different possible embodiments of the trans-
mission device.
According to a first embodiment, this mechanical
connection, involving conical gear trains of apex S forms the
second connection means between the coupling member and the
second movable member.
According to a second embodiment which can be used
when the first member is mounted so as to rotate relative
to the frame at the speed ~ about the first axis, this
mechanical connection by conical gear trains o~ apex S is
placed ~etween the second member an~ the frame in such a way
O O*
as to lin~ the speeds a and ~ .
_ 24 _
1070527
According to a third embodiment which can also
be used when the first member rotates relative to the frame
at speed ~ about the first axis, this mechanical connection
by conical gear trains of apex S is located between the
first and second members in such a way as to link in rotation
O O* O
the speeds ~, ~ , and ~ or at least two of them.
Preferably, the conical gear train comprises two
conical gears of apex S one integral in rotation with the
second member and the other lin~ed in rotation with one of
10 the following members: the frame, the coupling member, the
first member or the supporting means.
b) The problem of connections between the supporting
means and the coupling means (noteably constituted by a rotary
drive shaft) does not present a difficulty because the slope
angle a is fixed. It has already been seen that the supporting
m~ans can rotate about the first axis. It is therefore
perfectly simple to link them in rotation with the rotary
drive shaft specifically mounted in coaxial manner relative
to the first axis. This system can also be used for driving
20 the auxiliaries o~ the transmission device or the motor
actuating the transmission device.
c) In the same way, the problem of the connections
between the coupling member (specifically constituted by a
rotary drive sha~t) and the first member (when the latter
rotates about the first axis) does not present a difficulty.
It is possib~e to lin~ in rotation, the first mem~er with the
drive shaft, which is more particularly mounted in coaxial
manner re1ative ~ the ~irs~ axis.
- 25 -
. . .
10705Z7
Point 4).
In order to solve the problem of balancing the
forces of the reaction on the bearings supporting the second
member, the second member may comprise gyroscopic means for
developing a gyroscopic torque which wholly or partly
balances the forces applied to the second member by the system
creating the contact pressure.
The gyroscopic means which develop a ~yroscopic
torque have a direction and an intensity which is sufficient
to relieve the stress on the bearings inserted between the
supporting means and the second member (~hese bearings permit
the latter to ro~ate about its own axis, the second axis,
whilst maintaining the latter inclined by a fixed angle a).
As a result, it is possible to lighten the material construc-
tion of these bearings and decrese the mechanical losses
therein.
It is important to point out here what is meant
by the phrase "gy~oscopic means associated with the second
member, developing a gyroscopic torque," by referring to the
mechanical properties of gyroscopic movements. Inertial
phenomena are developed in a solid having a movement about
a fixed point, the classic example of a solid having this
movement is the gyroscope (this is one of the reasons why
the adjective "gyroscopic" has been used to define the
mechanical means used~ ~he second member according to the
invention is in ~act a solid having a movement about a fixed
point S. It has in fact a rotary movement a~out its axis
~ 70527
of revolution (the second axis). This axis has itself a
conical rotary movement of apex S about the general axis
of the transmission device (the first axis). The axis of
the 6econd member (the second axis) describes a cone of apex
S about the general axis of the transmission device (the
first axis). This cone is generally called "~utation cone."
All the elementary forces of inertia which are
developed in the mass of the second member can ~e reduced,
by applying the general laws of mechanics to a torque and
10 to a force applied at S.
a) The force applied at S:
In the case where the center of gravity of the ~econd
mem~er substantially coincides with the point S, the force
applied at S is substantially zero. In the opposite case,
the force applied at S is a rotary force located in the plane
perpendicular to the general axis of the transmission device
(the first axis).
Preferably, according to a secondary feature of
the present invention, the center of gravity of the second
20 member is adjacent to point S, in such a way as to eliminate
the force applied at S which loads the bearings.
b) The torque:
The torque, which the inventor calls the "gyroscopic
torque" or "tor~ue with a gyroscopic origin," by analogy
with the terminology applied in the study of gyroscopes
can be mathematically characterized by a vector, whose direc-
tion is perpendicular to the plane containing the first and
second axes. The torque has a tendency to swing the second
1~70S27
member about an axis perpendicular to the plane containing
- the first axis and the second axis (but since the slope
angle a is fixed, no movement is possible).
Preferably, and according to a subsidiary charac-
teristic of the invention which facilitates its realization,
the second member is a solid which revolves about the second
axis having a transverse plane of symmetry perpendicular
at S to the second axis. In the case of this special embodi-
ment of the second member, it is possible to calculate, by
1~ applying the conventional laws of the mechanics of solids,
the moment of this torque (the modulus of the vector), said
moment being given by the following formula:
C 1 = (Jl ~ J3)a2 sin a cos a - J3 (a - ~) sin a
In this formula:
Jl and J2 designate the moments of inertia of the
second member relative to the second axis and relative to an
axis passing through S perpendicular to said second axis;
a (also called ~a" in the present application)
designates the slope angle of the second axis relative to
20 the first axis;
~ designates the rotation speed of the second member
about the first axis;
~ designates the rotation speed of the second
member about the second axis in a reference frame which is
fixed relati~e to the frame, whilst ~ , which has been used
previously, designates the rotation speed of the second member
about the second axis in a reference frame lin~ed to the
rotary plane containing the ~irst and second axes, whereby
be~ween ~ and ~ the relationship ~ a) is obtained.
- 2~ -
-" 1070527
This formula gives the intensity of the moment of
the gyroscopic torque resulting from all the forces of
inertia and relative thereto the following comments are
made:
a) it has been described in two parts in such
a way as to show in the first part the contribution of
inertial effects which can be called "centrifugal." Thus,
when a = ~, (when ~ = O), the second part of the expression
disappears, only leaving the first part, which is independent
10 of the rotation speed value of the second member about its
revolution axis (the second axis).
It should be noted that in general in the trans-
mission devices according to the invention (~ = O, in other
words a = ~*).
b) The expression of the moment of the gyroscopic
torque is an algebraic sum, therefore this couple can,
depending on the value of each of the parameters, either
tend to apply the second member to the first, or, conversely
tend to oppose the second member being supported on the
20 first.
In other words, the different parameters such as
th~ shape and mass of the second member tJl, J3), the rotation
speed (a, ~) and the conical movement angle a ~or a) must,
for each variant, be proportioned so as to obtain a tor~ue
hav~ng a direction and an intensity sufficient for ba~ancing
the reactive torque produced by the mechanical system creating
the contact pressures at points Pl and P2 (linked with the
power to be transmitted by the transmission device).
- 29 -
10705Z7
The term "gyroscopic means" is understood to mean
all the structural parameters and all the kinematic parameters
of the second member which influence the intensity and
direction of the gyroscopic torque.
The calculation of the gyroscopic means (i.e. the
calculation of the structural and kinematic parameters of
the second member~ falls within the scope of the skilled
expert. More particularly in the case of certain variants,
he can use the formula given hereinbefore. The calculation
of the gyroscopic means falls within the scope of the skilled
expert provided that, in accordance with one of the main
features of the present invention, he has received the instruc-
tion to use the gyroscopic torque created by these means
in order to balance with a sufficient force in a total or
partial manner the reactive torque produced by the mechanical
system creating the contact pressures at points Pl and P2.
Point 5).
In ordsr ~o solve the problem of balancing the
reactive forces on the frame, the supporting means may
comprise inertial means for developing a torque with an
inertial origin which serves to wholly or partly balance
the forces produced by the system creating the contact
pressures on the first member and consequently on the frame.
The inertial means comprise an arrangement and a
distribution of the masses forming the ~upporting means.
Before describing in detail several embodiments
of the transmission devices forming the ob~ect or objects
of the present invention, it would appear necessary to
- 30 -
"1~
t ~ ~ ~
~1~7~5;~7
briefly point out that the different members composing the
transmission device can be realized or arranged in different
ways depending on the complementary problems or subsidiary
advantages which it is desired to additionally obtain.
Firstly, the relative positions of the first member
and the second member can vary. The first member can be
contained within the second member which is then a hollow
body. Firstly, the second member can be contained in the
first member which on this occasion is hollow. Correlatively,
1~ the revolving rolling surfaces can in turn be concave or
convex in a transverse plane.
Secondly, a large variety of rolling surface forms
are possible. In the special case where the rolling surfaces
are conical (making it unnecessary to vary the slope angle
a), these conical rolling surfaces can be mounted on the
first member or on the second member.
In the meridian planes ~i.e. in a radial plane
passing through the axes of revolution of the rolling surfaces)
the generating lines of the rolling surfaces can either be
20 convex rolling su~faces or concave rolling surfaces. The
choice of the radii or curvature of the rolling surfaces in
the transverse or meridian planes make it possi~e, all
things ~eing equal, to obtain different output speed
ranges for the same variation amplitude of the ratio Rl~R2,
different variation laws of the transmission power as a function
of the output speed and transmission devices with different
dimensions.
Thirdly, a large diversity of mechanisms creating
the contact pressure is canceivable.
1.:
107~527
Fourthly, the coupling members and coupling means
can be realized in different ways. They can comprise main
drive ~hafts (input shaft or output shaft or vice versa).
The main drive shafts (more generally the coupling members
and coupling means) can be linked in rotation respectively
either with the first or second members (as regards the
coupling member) or the second member or supporting means
(as regards the coupling means). It is not indispensible
for the coupling means and coupling member to be respectively
10 linked in rotation with the first and second members, so
that one (the coupling member) can be linked with the
rotary movement of speed ~ of the second member about its
own axis (the second axis) and the other (coupling means)
can be linked at the speed a of the second member about the
first axis.
Fifthly, the first member can either be fixed
or can rotate about the first axis.
In the case where the first member rotates about
the first axis at speed ~ the general kinematic transmission
20 equation: '
o o o o Rl
~ - + ~a ~ ~B) R2 =
which was defined by the Applicant in the earlier-dated
Canadian Patent ~o. 998,857 leads to indefiniteness. Several
possi~le speeds ~ correspond to a spePd ~, depending on
the values of ~. To remove this indefiniteness and in
accordance with the teaching of aforementioned Canadian
Patent No. 988,857 various solutions are possib~e.
One solution consists of connecting in rotation
the firs~ member to the coupling member (to a main drive
107~527
shaft) and stopping the rotation of the second member
O O* O
relative to the frame (~ = 0; ~ = ~) or stopping the
rotation of a main drive shaft connected to the second
member.
It has already been seen how it is possible to
produce the mechanical connections between the second
member and the frame or between the second member and a
main drive shaft to achieve this result ~e.g. by means of
be~el gears or apex S or a flexible transverse member).
Another solution consists of connecting at least
two of the speeds (a, ~ , ~) by means of mechanical connections.
O O* O
Thus, the speeds a, ~ , w are interconnected by
two equation systems. On the one hand, the general ~inematic
transmission equation:
o o o o Rl
~ a ~ = 0
and on the other hand the equation due to the mechanical
connection which can be of the type:
O O* O
F t~, ~, ~) = O
in the case of an epicyclic connection for example or of
the type: r
o o*
g (~, B ) = 0
or even of the type:
O O
h (a, ~) = 0
O O*
) = O
This system of equations makes it possi~e to
determine the output speed of the transmission device as a
function of the input speed for a predetermined ~alue of
ratio R~/R2. Thus, only a single output speed corresponds
to one input speed.
1~7VSZ7
The mechanical connections linking the speeds
O O* O
provide particular advantages. As has been seen,
the gyroscopic balancing torque varies as a function of the
speeds of the second member about the second axis and of the
second axis about the first axis. Therefore, the mechanical
connections make it possible to modify the evolution of the
gyroscopic torque as a function of the output speed. ~hus,
it is possible to correlatively obtain output torques which
are better adapted to the different cases of utilization
10 (constant torques, etc.).
The mechanical connections connecting the speeds
O O* O
, ~ , ~ in the same way as the mechanical connections linking
the first and second members, as well as the supporting means
to the coupling members and the coupling means (to the
main drive shaft: input or output shafts of the transmission
device) can be formed in different ways, e.g. by means of bevel
gear trains of apex S or by means of a flexible transverse
mem~er~ or by means of sliding articulations mounted at the
extension end integral with the second member.
It is pointed out that the expression "linked in
rotation" used in the present description and in the claims,
relates to identical angular velocities or in a constant
given ratio or in a variable given ratio, whilst the expres-
sion "integral in rotation" relates to identical speeds.
The various em~odiments of transmission devices
according to the invention will now be described in greater
detail relative to non-limitative examples and with reference
to the drawings which show:
- 34 -
. . ,
~7~5Z7
Fig. l is a longitudinal sectional view through
a plane passing through the first and second axes of a first
variant, the system creating the contact pressure and
actuating the rolling surfaces comprising an elastic system.
Fig. la is a cross-sectional view through the
plane a-a of the variant shown in Fig. l.
Fig. 2 is a longitudinal sectional view through a
plane passing through the first and second axes in a second
variant comprising the system creating the contact pressure,
10 having an inertial origin.
Fig. 3 is a force diagram illustrating the opera-
tion of the inertial system described with reference to Fig.
2.
Fig. 4 is a longitudinal sectional view through a
plane passing through the first and second axes of a third
~ariant having a system creating the contact pressure com-
prising a system of helical ramps, whereby in this variant
the annular rings on which are pro~ided the rolling surfaces
are posltioned externally by a gear system.
Fig. 4a'is a cross-sectional view through the
plane b-b of the variant shown in Fig. 4.
Fig. 5 is a longitudinal sectional view through a
plane passing through the first and second axes of a fourth
variant having a system creating the contact pressure com-
prising a system of he~ical ramps, whereby in this variant,
the annu~ar rings on which the rolling sur~aces are provided
are positioned externa~1y through the combination of a
hydraulic system and a gear train~
- 35 -
1070527
Fig. 5a is a partial perspective view of the
manipulating member of the variant of Fig. 5.
Fig. 6 is a longitudinal sectional view through
the plane passing through the first and second axes of a
variant of the type described with reference to Figs. 2
and 3, whereby in the case of this variant, the first
biconical mem~er is fixed.
~ ig. 7 is a longitudinal sectional view through the
plane passing through the first and second axes of a variant
10 of the type described with reference to Fig. 4 and 5,
whereby in the case of this varian~, the second member
carries the biconical rolling surface.
Fig. 7a is a detailed perspective view of the means
for modifying the position of the contact points Pl and
P2 in the case of the variants shown in Fig. 7.
Figs. 1 and la will now be described which respec-
t~vely show a longitudinal sectional view and a cross-sectional
view of a first variant of a transmission device according to
the invention.
This transmission device comprises a fixed frame
having at either end two substantially planar sides Al and
A2 ~oined by a casingA3, which has a generally cylindrical
shape.
A first member 2 and a second mem~er ~ are mounted
so as to rotate on said frame via bearings.
The first mem~er 2 rotates a~out a first axis 7
which is the longitudina~ axis of the transmission device,
being fixed relative to the frame A. The first member comprises
two halves 4 and 5, having two conical rolling surfaces 8 and
- 36 -
~f ~
1070S~7
9. These two halves are mounted on a shaft 11 (output
shaft) which is coaxial to the first axis 7 and are axially
movable relative to oné another in accordance with the longi-
tudinal direction of the first axis 7. Keys 22a and 22b
interlock in rotation the two halves 4 and 5 and the shaft
11 .
~ etween the inner wall of halves 4 and 5 and the
outer surface of shaftll are provided two annular chambers
14a and 14b, which communicate with the outside by pipes
10 17a, 17b and 15 provided to this end in the mass of shaft -
11. A cylindrical groove 18 on the surface of shaft 11
makes it possible to introduce a pressurized fluid into the
chambers 14a and 14b when shaft 11 rotates on itself about
the first axis 6. Gaskets 21a, 21b, 21c, 21d, 21e and 21f
ensure the sealin~ of the system of annular chambers and
the supply pipes 4 of said annular chambers. The introduction
of a pressurized fluid into the annular chambers has the
effect of simultaneously axially displacing the two halves
4 and 5 and the rolling surfaces 8 and 9 by moving them
~0 apart. The functson of said manipulating members of the
rolling surfaces 8 and 9 of first member 2 will be shown
hereinafter.
The frustum-shaped rolling surfaces 8 and 9 are
of revolution about the first axis 7 and are disposed symme-
trically on either side o~ a plane 10 which is perpendicular
to the first àxis 7 at a point S of said axis. The large
bases of each of the two truncated cones face one another.
Shaft 11 is supported by the frame at each of its
ends by a system of bearings comprising a first series of
roller bearings la and lb coaxial to the first axis 7. ~n
1~7~5Z7
order to facilitate the assembly of the first mem~er and
the shaft 11 supporting the same, the end of shaft 11 is
disassemblable ~y means of a system of rings 23a, 23b and the
bolt 24.
A support 13 is mounted so as to rotate about the
first axis 7 by means of a system of bearings 25a and 25b
inserted between the frame A (sides Al and A2) and the support
13. The ~earings la and lb mentioned herein~efore are them-
selves mounted within the support 13 in the transverse plane
of bearings 2~a and 25b at each of the ends of the trans-
mission device, in such a way that the first mem~er 2 can
rotate relative to support 13, which can itself rotate
relative to frame A.
The substantially cylindrical support 13 is inclined
relative to a lorgitudinal axis 7 of the transmission device.
It i6 intended to sup~ort the second member 3 via needle
ball bearings 26a, 26~, and 26c. This latter bearing serves
to axially position the second member 3 relative to the
support 13.
The second member 3 is a substantially cylindrical
solid of revolution and rotates relative to the support 13
about a second axis 12 passing through the pcint S of the
first axis 7 and inclined by a constant fixed angle _ (also
called a) relati~e to the latter. In the case of this
embodiment, the half-angle at the apex of the cone frustums
forming the rolling surfaces of the first mem~er is slight~y
smaller than the a~o~e-defined slope angle _. The significance
of this will be shown hereinafter with reference to the
description of the operation of the transmission device.
- 38 -
~07~527
The second member 3 co~prises two rolling surfaces
19 and 20 which are of revolution about the second axis 12
and are symmetrically disposed on either side of a plane 16
perpendicular to said second axis at point S. These rolling
surfaces are formed on two annular rings 27 and 28 which are
axially movable relative to one another, in accordance with the
longitudinal direction of the second axis 12 within the
cylindrical body 3a of the second member, but they are integral
in rotation with the second member 3.
A mechanical system comprising a plurality of
coil springs 29 axially actuates two rolling surfaces 19 and
20 of the second member in such a way as to apply the latter
with a sufficient force at two contact points Pl and P2
against the rolling surfaces 8 and 9 of the first member 2.
These springs are fitted along the inner wall of the second
member 3 and supported on the one hand on the flanges 30a
and 3Ob located at the two ends of the second member 3
and on the other on each of the annular rings. The exact
function of this spring system will be described hereinafter.
A bevel gear 31 of apex S is integral in rotation
with the second member 3 and cooperates with a bevel gear
32 of apex S integral with the casing A3 of the frame. A
main drive shaft 33 ~input shaft) is integral in rotation
with support 13, said shaft 33 being coaxial to axis 7.
The operation of this embodiment of a transmission
device according to the invention will now be descri~ed.
The biconical rolling surfaces are in rollin~
frictional contact at Pl and P2 with the rolling surfaces
19 and 20 of the second member. The speci~ic contact pressure
- 39 -
~.~.,'
107~527
is created by the spring system. These springs 29 and the
ha~f-angle at the apex of the frustom-shaped rolling surfaces
are calculated to create the normal pressure FN sufficient
to transmit the input torque, without any slipping of the
races relative to one another. Under the action of the input
torque applied to the input shaft 33, rolling surfaces l9 ~-
and 20 are rotated on the one hand at the speed ~ about
their own axis (the second axis) and on the other are given
a conical movement of apex S about the first axis 7 at
lO speed a.
The above-defined speeds ~ , and speed ~ of the
first member about axis 7 are interconnected by a kinematic
relationship dependent on the geometry of the rolling surfaces
and which is as follows:
~ " - a - ~* --
In this equation, Rl and ~ designate the radius Rl of the
circle described ~y one of the contact points on the rolling
surface in question of the second member and the radius R2
of the circle described by one of the contact points on the
20 considered rolling surface of the first member.
In the case of the present embodiment, the bevel
gears 31 and 32 of apex S, which are respectively integral
with the second member 3 and the frame, have the effect of
lin~ing in rotation the speeds ~ and ~ in such a way that
the ~atter are in a constant ratio. Conse~uent7y, ~or an
input speed a there is only a single output speed ~ at
which the output shaft ll of ~he transmission de~ce can ~e
driven.
- 4U -
107~5Z7
The metallic masses of the second member 3 are
distributed in such a way that the center of gravity of the
second member coincides with the point S of the first and
second axes and the main moments of inertia ~1 and J3 of
the second member have values related to the speeds a and
B and the slope angle a (also called a) in such a way that
a gyroscopic tor~ue is developed havinq a direction and intensity
sufficient for wholly or partly balancing the reactive torque
associated with the normal forces FN.
Thus, the bearings 26a, 26b and 26c which support
the second member, only receive relatively low or zero radial
forces during operation.
Furthermore, as a result of the symmetrical arrange-
ment of the rolling surfaces, bearings la, lb, 25a and 25b
supporting the main drive shafts receive no axial reaction.
The way in which the input speed ratio can ~e
varied by modifying the ratio Rl and R2 will now be described.
By injecting a pressurized fluid into the chambers
14a and 14b, it is possible to displace the rollinq surfaces
20 8 and 9, by respectively moving them away from plane 10.
In Fig. 1, the rolling surfaces 8 and 9 are shown in their
position of maximum spacing. The available transverse
spacing between the rolling surfaces 8 and 9 and the cylin-
drical body 3a of the seco~d member 3 decreases in propor-
tion to the mo~ing apart of the rol7ing surfaces. As the
slope angle of the second axis relative to the first axis
is significantly greater than the hal~-angl~ at the apex
of the frustum-shaped rolling surfaces 8 and 9 the available
~ 41 -
107~527
transverse space between the rolling surfaces 8 and 9 and
the cylindrical body 3a of the second member 3 increases in
the direction of the plane of symmetry 16. Therefore, the
axially movable annular rings 27 and 28 on which are provided
the rolling surfaces 19 and 20 cannot move back in the direc-
tion of plane 16 when the rolling surfaces 8 and 9 are moved
away from one another by injecting a pressurized 1uld(rolling
surfaces 8 and 9 move back relative to the action of the
elastic system 29a and 29b). Therefore, the ratio Rl/~
10 varies, because the radius R2 increases, so that correlatively,
bearing in mind that the kinematic equation mentioned here-
inbefore the speed ratios ~ and ~ vary.
Conversely, when the fluid pressure in the chambers
14a and 14b increases, the rolling surfaces 8 and 9 move
towards one another and towards plane 10. They are in fact
actuated by the spring system 29a and 29b via annular rings
27 and 28. They are actuated by the spring system whilst
the fluid pressure in the chambers does not balance the force
exerted by the elastic system. As a result of the reversible
20 displacement of tHe rolling surfaces 8 and 9, it is possible
to continuously vary in ~ne direction or the other the speed
ratio of the transmission device.
With reference to Fig. 2 a second e~bodiment of the
transmission device according to the invention will now be
described. Fig. 2 shows a longitudinal sectional view through
a plane passing through the first ana second axes of the
transmission device comprising a mechanical system creating
the inertial contact pressure.
- ~2 -
10'7~527
Most of the members described with reference to
Fig. 1 are shown in this drawing. They carry the same
reference numPrals and more particularly it is possible to
see frame A, first member 2, second member 3, first axis
7, Qecond axis 12, support 13, rolling surfaces 8 and 9 of
the first member and 19 and 20 of the second member, with the
constant fixed slope angle a of the second axis relative
to the first axis.
A detailed description will only be provided here
10 of those members whose structure differs from that described
hereinbefore. This applies more particularly to the geometry
of the rolling surfaces 8 and 9 having a generally conical
configuration.
In the case of this embodiment, the mechanical
system creating the contact pressure and actuating the
rolling surfaces has an inertial origin, i.e. the inertial
forces which develop in the mass of the annu~ar rings
27 and 28 actuates the latter and applies them against the
rolling surfaces 8 and 9. Fig. 3 shows the force diagram
20 illustrating the operation of the mechanical system actuating
o~e of the rolling surfaces. As the annular ring 28 is
rotated at speed a about the first axis 7, it is subjected
to centrifugal forces, whose resultant at Gp (center of
gravity of the annular ring }ocated on the second axis 12)
is a rotary force Fc ~this force depends on the geometry
and mass of the annular ring as well as its speed ~). This
~orce can be broken down into an axia~ component (directed
according to the second axis 12~ FCa and a radial component
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107~527`
FCr. This axial component FCa has the tendency to displace
the annular ring 28 in the direction of arrow F, i.e. to
move the ring 28 out of the plane of symmetry 16 of the second
member. Therefore, the annular ring is displaced until it
iB supported on the rolling surface 9 of the first member,
by exerting an adequate pressure to prevent the slipping
of the rolling surfaces 9 and 20, in such a way that the
rolling surfaces roll on one another without slipping.
It is ~nown that in order to transmit a given
input torque, it is necessary to exert a predetermined normal
force FN (this normal force FN is obtained by calculation or
experimentally from the torque value to be transmitted).
Tt is possible to calculate or draw the profile of the
rolling surface 9 of the first member and define the geometry
of the annular ring 28 in such a way that each contact point
between the rolling surfaces 9 and 20, the normal force
created ~y the centrifugal force Fc is equal to
the desired normal force FN. Thus, if T is used to designate
the tangent at contact point P2 relative to the rolling
surface 9 of the first member, said tangent T forms an angle
~a with the second axis 12 which is materialized by drawing
at P2 the parallel line and the perpendicular line to the first
axis 12.
The axial component FNa (in accordance with the
second axis 123 of the nor~al force FN is a function of the
a~ove-defined ang~e ~a:
Na N sin ~a
_44; _
1070~Z7
When balanced, this axial component FNa must be
equal to the axial component FCa created by the centrifugal
force:
ca FNa = Fn x sin ~a
Thus, by graphically or numerically solving this
equation, it is possible to determine the geometry, the mass
of the annular ring and the rotation speed ~, as well as the
profile of the rolling surface 9 permitting the creation of
the desired normal force ~N~
The operation of the manipulating member permitting
the axial position of the rolling surfaces 8 and 9 and the
variation of the speed is, in all points identical to that
applied with reference to ~ig. 1.
Figs. 4 and 4a will now be described which respec-
tively show a longitudinal sectional view through a plane
passing through a first and second axes and a cross-sectional
view of a third variant having a mechanical system for
i actuating the rolling surfaces creating the contact pressure
! comprising helical ramps. These drawings show most of the
20 members described'with reference to Fig. 1 and these carry
the same references. A detailed description will be provided
hereinafter only of those members having a different structure
from those described hereinbefore, more particularly the
mechanical actuating system for rolling surfaces ana the
manipulating mem~er.
In this em~odiment, the rolling surfaces 8 and 9
are truncated cones, whereof the half-angle at the apex is
egual to the slope an~le _ of the second axis relative to
- 45 -
107~527
the first axis. Therefore, the available spacing between
the cylindrical body 3a of the second member 3 and the rolling
~urfaces 8 and 9 is constant over the entire length of the
rolling surfaces.
The rings are mounted, in a manner to be described
hereinafter, in such a way that they can be axially displaced,
in accordance with the direction of the second axis in the
space defined hereinbefore and are in frictional contact
with the rolling surfaces 8 and 9.
The two halves 4 and 5 on which the rolling surfaces
8 and 9 are formed, are movable on shaft 11 by means of
helical ramps 40a and 40b having a reverse pitch. It is
obvious that on rotating the two halves 4 and ~ relative to
the output shaft 11 in an appropriate direction, there is
a tendency to move apart hal~es 4 and 5. This has the effect
of reducing the space between the rolling surfaces 8 and 9
and the second member 3. Consequently, on rotating the two
halves 4 and 5 in an appropriate direction, the rolling surf~ces
8 and 9 are applied against the rolling surfaces 19 and 20
with a sufficient~normal force to transmit the input torque.
A coil spring 40c inserted between the two halves
4 and 5 facilitates the realization of the mechanical system
which creates the normal force by pretensioning the rolling
surfaces in such a way that they are prevented from sliding
on one another on starting or in the case where the output
torque is zero.
The annular rings 27 and 28 are mounted so as to
s~ide axially within the cylindrical body 3a of the second
member having a cylindrical shape internally. They are
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107V527
traversed by threaded rods 41, such as 41a, 41~ a~d 41c
having opposite pitches, making it possible to axially
displace them (to move them closer or further away). These
threaded rods 41 are integral with gears 42, such as 42a,
42b and 42c, moved by a crown gear 43 whose axis is the
second axis 12. ~his crown gear 43 is itself integral with
a bevel gear 44 of apex S in gear with a further bevel gear
45 of apex S, which rotates about the first axis 7. Bevel
gear 45 is integral in rotation with a gear 46 which is in
10 gear with a gear 47, integral with a manipulating lever
wh~ch moves about an axis 48, fixed relative to frame A. As
a result of this combination of gears, it is possible to
control from the outside of the transmission device, the
axial position of the annular rings and thus vary the speed
ratio of the transmission device (as has already been described
with reference to Fig. 1).
A description will now be provided of Fig. 5 which
shows a longitudinal sectional view through a plane passing
through the first and second axes of a fourth embodiment.
20 In the case of this embodiment, the annular rings, on which
are provided the rolling surfaces, are positioned externally "~
by the combination of a hydraulic system and a gear train.
This drawing shows most of the members described
with reference to the previous drawings, particularly
Figs. 1 and 4 and they carry the same reference numerals.
The half-angle at the apex of the frustums con-
stituting the rolling surfaces ~ and ~ is substantia}ly equal
to the slope angle of the second axis relative to the first
axis.
_ 47 -
.'~ ,
10705Z7
In the case of this embodiment, the mechanical
system actuating the rolling surfaces and creating the normal
force FN is comparable to that described hereinbefore with
reference to Fig. 4. It comprises an annular ring S9 mounted
integral in rotation with shaft 40 by means of channels.
Annular ring S9 has on its sides ramps formed by teeth 59a
and 59~ which cooperate with ramps having a complementary
configuration, also formed by teeth 4a and 5a integral
respectively with halves 4 and 5 on which are provided the
10 frustum-shaped rolling surfaces 8 and 9. The inclination
of the faces of the teeth is such that the rotation of the
two halves 4 and 5 relative to the shaft 8 has the effect of
moving them apart and jamming the rolling ~urfaces 8 and 9
against rolling surfaces 19 and 20 of the second member 3.
In the case of this embodiment, the manipulating
member which axially positions the annular rings 27 and 28
is of a special type and is shown in perspective in Fig. Sa.
The annular rings are mounted so as to slide within
two cylindrical sleeves 53a and 53b, which rotate within
20 the second member 3. These two sleeves 53a and 53b are
integral with two conical crown gears of apex S and are syn-
chronized in rotation about the second axis 12 via a bevel
~ear S5 of apex S, whose rotation axis located in the plane
of symmetry 16 passes through S. This bevel gear 55 is mounted
in freely rotatable manner by means o~ a shaft which pivots
in the second member and is in gear with two beve? gears
SSa and 55~ o~ apex S, integral with the sleeves. The two
sleeves have two longitudinal openings 56a and 56b in which
- 48 -
107~27
slide two cylindrical rods 57a and 57b, integral with
annular rings 27 and 28. The extensions of the two cylin-
drical rods 57a and 57b slide in two other helical ramps 58a
and 58b provided in the wall of the second member 3.
The two annular chambers 14a and 14b are indepen-
dently supplied with a pressurized fluid by pipes 50a, 50b,
51a, 51~, 52a and 52b of the type described hereinbefore. -~
When the pressure in one of the chambers, e.g. the
right-hand chamber 14b is increased, the normal force FN is
10 increased on one side. Therefore, the sleeve 56b tends to
rotate more quickly than the second member 3. ~y rotating
relative to the second member 3, sleeve 56b, via the opening
system causes the axial displacement of the annular ring 28.
As sleeve 56b is synchronized in rotation with sleeve 56a,
the latter in turn rota~es relative to the second member
whilst axially displacing via the other opening system, the
annular ring 27. The profile of the helical openings 58a
and 58b of the second member 3 i8 calculated in such a way
that the axial movements of the annular rings 27 and 28
20 are in opposite directions. Whilst the pressure difference
is maintained between the two annular chambers 14a and 14b,
the sleeve~ bring about the axial displacement of the annular
rings.
A description will now be provided of Fig. ~ which
shows a longitudinal sectional view through a plane passing
through the first and second axes of an em~odiment comparable
to that describea with reference to Figs. 2 and 3.
Most of the members descri~ed with reference to
Figs. 2 and 3 reoccur and carry the same reference numerals.
- 49 -
~0705Z7
In the case of this embodiment, the first biconical
member 2 is fixed and integral with frame A via a hollow
shaft 11. The casing 60 of the transmission device rotates
about the first axis 7 and is integral with a main drive shaft
61. Casing 60 is integral in rotation with a bevel gear 62
of the apex S, of the same type as gear 32 described with
reference to Fig. 1. This bevel gear 62 cooperates with other
gears 31 of the transmission device, as described hereinbefore.
Support 30 is integral in rotation with a main
10 drive shaft 63 which traverses the hollow shaft 11.
In other words, this embodiment differs from that
described relative to Figs. 2 and 3 in that the first member
is fixed in rotation. One of the main drive shafts 63 is
connected in rotation at the speed ~ of the first member
about the first axis 7. ~he other main drive shaft 61 is
connected in rotation at the speed ~ of the second member
about the second axis 12 via a bevel gear train of apex S.
A description will now be given of Fig. 7 which
shows a longitudinal sectional view through a plane passing
20 through the first~and second axes of an embodiment comparable
to that described with reference to Figs. 4 and 5.
In this embodiment, the second member carries the
conical rolling s~rfaces.
The transmission de~vice has a frame A comprising
two flat si~es Al and A2 at each of ~he ends, ~oined by
screws to a substantially cylindrical casing A3.
~ he first member 72 comprising two halves 74 and
75 with a generally annular configuration is mounted on the
said casing. On these two halves are provided the rolling
-- so
- 1070SZ7
surfaces 78 and 79 which revolve about a first axis 77
(the longitudinal axis of the transmission device) and
~ymmetrically positioned relative to a plane 80 perpendi-
cular to the first axis 7 at a point S of said axis. The
two halves move axially within the casing in accordance with
the longitudinal direction of the first axis 77. These
; two halves are controlled in axial translation by a manipula-
ting member, whose arrangement will be better understood by
referring to the detailed view of Fig. 7a to be described
10 hereinafter.
Within the casing is mounted a second member 73
which also comprises two halves 73a and 73b on which are ;~
respectively provided the frustum-shaped rolling surfaces
89 and 90. These two rolling surfaces 8g and 90 revolve
about a second axis 82 which coincides with the first axis
77 at a point S. In addition, they are symmetrically
arranged on either side of a plane 8~ perpendicular to the
3econd axis at S.
The slope angle a of the second axis, relative
20 to the first axis is constant and substantially equal to
the half-angle at the apex of the frustum-shaped rolling
surfaces.
These two halves are mounted by means of a system
of helical ramps llOa and llOb on a ho~low shaft 81 coaxia~
to the secon~ axis 82 (this system of helical ramps has the
same functions as the system of helical ramps describea
with reference to Fig. 4).
This shaft 81 and the second member 73 are mounted
so as to rotate about the second axis 72 by means of bearings
9~a and 9~ carried at one of the ends by a support 83a which
i
i ,~ ,
~ ~.
1070527
is freely rotatable about the first axis 7 and at the other
end by a support 83b integral in rotation with a main drive
shaft 103.
Support 83a is itself supported by bearings 81a
mounted in the side Al of the frame. Support 83b is itself
supported by the bearings 81b mounted in the side A2 of the
frame.
Sha$t 81 and the second mem~er ?3 which rotate
at speed ~ about the second axis 82 are linked in rotation,
10 via a universal joint 7 00 with a main dri~e shaft 104 coaxial
to axis 77. This shaft 104 is supported by bearings 105.
The universal joint 100 is located within the hollow shaft f
81.
It can be seen that the members comprising this
embodiment of the transmission device according to the
invention have similarities with the members described with
reference to Figs. 1 to 6. Admittedly, their relative
~ositioning is not the same, but their structures and func-
tions are comparable and in fact to stress the similarity,
20 the same terminology as used hereinbefore is employed for
describing this new embodiment and in addit7on the reference
numerals used show the clear association between this embodi-
ment and those described hereinbefore, so that 70 has been
added to the reference numerals used in the embodiments of
Figs. 1 to 6 when passing from a mem~er, axis, bearing to
a member, axis, bearing of the present embodiment.
Therefore, no further detailed description will
be provided here of the operation of this em~odiment, because
it is comparable to that of the previously descri~ed embodi-
- 52 -
10705Z7
ments. However, it is briefly pointed out that the shaft
103 rota~es support 83b at speed a. As a result, due to
the fact that the rolling surfaces 78 and 89 on the one hand
and 79 and 90 on the other are respectively maintained
supported against one another at the two points Pl and
P2, the second member 73 rolls against the first member 72
O*
by rotating on itself at the speed ~ about the second axis.
Therefore, the main drive shaft 104, lin~ed in rotation with
the second member, is driven.
In the same way as in certain of the embodiments
already described, the normal force exerting the specific
frictional contact pressure at Pl and P2 is created by the ?
system of helical ramps. In order to facilitate the operation
of the helical ramps system on starting, a spring 106,
inserted ~etween the two frustum-shaped portions 73a and
73b actuates the rolling su~faces 89 and 90 relative to
the rolling ~urfaces of the first member in such a way
that the rolling surfaces are pretensioned.
In the same way as previously, the geometry and
2~ kinematics of the second member are adapted so as to produce
a gyroscopic torque which balances the reactive torque correla-
tive to the normal forces exerted at P1 and P2. This
arrangeme~t reduces the mechanical stresses, particular}y
on the bearings, which lightens them or reduces wear thereto.
The manipulating mem~er which axially moves the
ro~ling surfaces 78 and 79 of the first member wil} now be
described with reference to the detailed ~iew of Figs. 7a.
This perspective view shows the cylindrical casing of A3,
_ s3 -
10705Z7
the first axis 77, the two halves 74 and 7~ of the first
member having an annular configuration on ~ihich are formed
the rolling surfaces 78 and 79 which revolve about the first
axis 77. Cylindrical pins 74a and 75a are respectively
integral with the two halves 74 and 75. These two pins
slide in a longitudinal opening 115 of the casing and cooperate
with a system o~ helical ramps 116a and 116b of opposite
pitch, provided in a sleeve 117 and 118, made in two parts
in order to facilitate machining of the ramp. The sleeve
10 117 and ~18 is co~,xial to the casing and rotates about the
first axis 7. It is obvious that on rotating the sleeve
a~out the axis 77, rolling surfaces 78 and 79 are moved away
from one another to a greater or lesser extent in accordance
wi.h the directi of the first axis 77.
- 54 -
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