Note: Descriptions are shown in the official language in which they were submitted.
1078~95~
Background of the Invention
The present invention relates to swivel joints
of the parallel or constant velocity type for transmitting
torque between a drive shaft and a driven shaft. Such
joints include an outer joint membe~ connected with one
of the shafts and an inner joint member connected with the
other shaft. The outer ~oin-t member has a hollow cavity
and the inner jolnt member is arranged within the cavit~.
The interior wall surEace of the cavity has a first
plurality of ball receiving grooves and the exterior surface
of the inner joint member has a second plurality of ball
receiving grooves equal in number to the first plurality.
The plurality of grooves are arranged so that a ball for
; transmitting torque between the inner and outer joint members
is carried between one pair of corresponding grooves.- In
- this arrange~ent, the balls of each pair of grooves are
~; subjected to a force caused by clearances or play which are
a result of large manufacturin~ tolerances. This force
~, tends to dispIace the balls out of their homokinetic plane
in a direction ca~sing a decrease in the angle formed by a
plane containing the centers of the balls and the axis of
rotation of the inner joint member. This type of joint also
includes a cage having a plurality of circumferentially
'~ arranged window recesses, which is arranged between the inner
.
~25 and outer joint members, the balls being retalned in the
- window recesses.
~ ~ In such constant veloci y, or parallel transmission
-
~ ~ joints, which are used in steering linkages for motor
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vehicles, manufacturing tolerances usual-
ly result in clearances which affect the s~eering control
of the torque transmitting elements. As a result of such
clearances, forces act on -the torque transmitting elements
displacing them out of a homokine-tic plane detrimentally
affecting the torque transmission capacity of the joint and
its serviceable life. The adverse effects of such
cle~arances become more significant when the inner joint
member is deflected with respect to the outer joint member
(i.e. when the axis of rotation of the inner joint member
is angularly displaced relative to the axis of rotation
of the outer joint member). Such adverse effects progressively
increase even for a displacement angle of approximately 25-30.
This is particularly true in joints which are provided
with axially extending parallel ball receiving grooves, the
balls carried between the grooves acting as the torque
transmitting elements.
Further, one of the problems particularly found
in motor vehicles is that considerable steering forces are
required when operating the vehicle around corners, espe-
cially at very low speeds, or at very low tire pressures.
In view of the modern trend towards the use of front-wheel
drive vehicles, it has become customary to select a negative
roll-radius for front wheel adjustment in order to ensure
substantially straight forward movement of the vehicle even
in situatlons of asymmetrical braking. However, such
negative steering roll-radius also affects the general
steering behavior of the vehicle since the wheels of the
vehicle will not automatically return to a normal straight
condition after tight cornering.
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It is accordingly the principal object of the
present invention to provide a swivel joint for a steering
control lin~age of the type having.a cage for retaini.ng
ball~torque transmitting elements, which can compensate for
tilting movement of the cage as a result of play and
clearances caused by manufacturing tolerances.
A further object of the present invention is to
provide a s~ivel joint of the constant velocity or parallel
type which has means for providing a restoring force
effective during certain angular deflections of the joint,
which force is either constantly effective on the joint or
becomes effective when the angular displacement of the inner
joint me~ber with respect to the outer joint member reaches
a certain predetermined angle.
Yet another object of the present invention is
to provide a swivel joint having means to assist movement of
the wheels to an original straight position after angular
deflection of the joint caused by turning the wheels.
Other objects, features and advantages of the
2~ invention will become more apparent from the description of
the invention in connection with the drawings to be described
more fully hereinafter.
Summary of the Invention
:
~ The foregoing objects of the present invention are
25 generally accomplished by provid1ng in a swivel joint of the
.~ type described hereinabove, a stop face on the inside of the
- inner joint member and a cooperating bearing surface on the
cage engaging the stop face at a predetermined angle of dls-
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~137~ 9
placerlent of the a~is of the inner joint member with
respect to the axis of the outer joint member.
The advantage of a cooperating stop face and
bearing surface on the cage is that at a ~redetermined
angle of displacement, which is less -than the maximum
permissible angle of displacement of the joint, the stop
face will be engaged by -the bearin~ suxface of the cage.
Accordingly, duri.ng further deflection of the inner joint
member with respect to khe outer joint member, the cage
will be repositioned so that the centers of the ball torque
transmitting elements will lie in a plane which bisects
an angle of deflection between the inner and outer joint
members. This will ensure that the centers of the balls
return to an angle bisecting plane regardless of load
conditions.
- Additionally, as a result of this arra~gement the
- balls, which have been shifted to a position adjacent theedges of the grooves, will return to the bottom of the groove
track so as to reduce load per unit surface.
2~ Further, because the balls are returned to a
perfect parallel position, any of the balls which then have
their centers passing through a plane which contains the
axes of both the inner joint member and the outer joint member
.
will be effective to transmit torque. Consequently, load lS
more evenly distributed over the balls and the static load
capacity is increased.
In one embodiment of the invention, the stop face
of the inner joint member is for~ed so as to be concentric
- with the axis of both the inner and outer joint members when
~ 30 they are aligned with each other, and the bearing surface is
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~C~7~ 39
arranged at the front end of the cage facing the stop face.
The advantage of this arrangement is that, because
of tumbling movement of the cage during rotation of the joint,
the cage will engage the stop face along certain individual
, parts of its circumference even before the predetermined
angle of displacement at which engacJement between -the stop
face and bearing surface takes place, is reached. Accor-
dingly, the foregoing advantages will result even at angles
of displacement between the axes of the inne~ and outer
joint members which are below the maximum deflection of the
joint.
Another feature of the present invention is to
provide a spring means between the stop face and the bearing
surface of the cage so that the bearing surface engages the
spring before reaching the stop face.
The use of such a spring means provides the
additional advantage that a force, which is directed opposite
to the tilting moments of the cage, assists in urging the
cage to return into the angle bisecting plane. This force
creates a restoring force which facilitates steering control
of the joint. This force acting on the cage, is effective
at most times, and at any rate during those times when the
angle of displacement is approximately between 25 and 30.
'~ Another advantage of this arrangement is that
improved steering control permits larger manufacturing
tolerances resulting in larger clearances between elements.
Constant velocity joints which have larger manufac-turing
tolerances are thus less expensive to manufacture and also
generate less heat when in operation.
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78~9~
In addition, the use of the spring, which is
operative either during all angles or displacement or only
above a certain predetermined angle of displacement, creates
a force which tends to res-tore the joint to a straight or
non-deflec-ted position. This Eorce has the eEfect of
reducing the effort needed to s-traighten out -the turned
front wheels, and thus improves driving safety. Because
it is included within the joint, this means for producing
a restoring force has all the advantages of a sealed and
permanently lubricated unit.
The spring may be associated with the bearing
surface of the cage. Such an arrangement would merely
involve constructional or production considerations.
The spring can be one of a number of different
types, such as for example a plate springl a spiral spring,
a leaf spring or a pad or bloc~ of an elastically deformable
plastic material.
The elastic force which is requlred to be
exerted by the spring will vary depending upon the type
of joint in which it is being used. In joints where large
- amou~ts of deflection are anticipated, the point at whichthe bearing surface will engage the spring before encountering
the stop face will be at a larger angle of displacement than
in a joint where only small amounts of deflection are anti-
cipated. Accordingly, different types of springs will be
used in different types of joints.
When using a plate spring, which is securely
attached to the ~age, the outside diam~ter of the spring will
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~C~7819~
be equal to the convex surface of the cage. ~dditionally,
the stop race, which is engaged by the plate spring, is
formed by an annular surface on a separate annular component
which is carried on the inside surface of the cavity of the
outer joint member.
The use of a p]ate sprincJ mountecl on the cage is
advantageous in as much as the cage will only be displaced
by an amount equal to half the deflectiorl movement so that
relatively little space is re~uired.
Brlef Description of the Drawings
; Embodimen-ts of the present invention exemplifying
the principles and features of the invention are illustrated
by way of example in the accompanying drawings, in which:
Figure 1 is an axial sectional view showing a
swivel joint in accordance with the present invention,
having a stop face on the inside of the outer joint member,
and showing the position of the inner and outer jolnt
members with their axes parallel;
Figure 2 is a view similar to that Gf Figure 1
illustr~ting the inner and outer joint members with their
axes displaced at an angle with respect to each other;
Figure 3 is a view similar to that of Figure 1
illustrating an embodiment of the invention in which the
stop ace is located at an area of the opening of the
outer joint member;
Figure 4 lS a view sim1lar to that of Figure 1
;~ illustrating an embodiment of the invention having one
type of spring positioned between the stop face and the
' bearing surface;
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Figure 5 is a view similar to that of Figure 1
illustrating yet ano~her embodiment of ~he present
invention having another type of spring which is connected
to the cage;
Fisure 6 is a view similar to tha-t of Figure 1
illustrating yet a further embodiment of the present
invention having yet a further type of spring in the form
of a block oE resilient plastic ma-terial located between
the stop face and the bearing surface for engaging the
stop face;
Figure 7 is a view similar to that of Figure 1
illustrating still a further embodiment of the present
invention having a spring member in the form of a plate
positioned between the stop face and the bearing surface;
Figure 8 is a plan view showing one type of
plate spring used in the embodiment illustrated in Figure 7;
and
Figure 9 is a plan view illustrating another
type of plate spring for use in the embodiment illustrated
in Figure 7.
Description of the Invention
~eferring now in more detail to the accompanying
drawings, Figure 1 illustrates a swivel joint for
transmitting torque between a drive shaft and a driven
shaft at a constant velocity. In the embodiment shown
i herein, the joint includes an outer joint member 1 which can
be connected to the driven shaft. The joint member 1 has a
cavity 2 which has an opening for receiving an inner joint
member. A plurality of circumferentially spaced grooves 4
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78~99
extend along the inner wall surface of the cavity 2 in a
direction parallel to the a~is of rotation 3 of the joint
members. An inner joint member 5 which is connected to a
drive shaEt 15 is carried within the cavity 2 of the outer
joint member 1. A plurality of lon~itudinal ~rooves 7,
e~tending parallel to grooves 4, are provided on the ou-tside
wall surface of the inner joint member 5. In the embodiment
shown, the inner joint member 5 and -the drive shaft 15 form
an integral unit which are made in one piece. A cage 8 having
an outer conve~ surface and an inner concave surface is
arranged between the inner joint member 5 and the outer
joint member 1. A steering control member 19 is carried
as a separate component on the inner joint member 5.
Control member 19 has a convex surface 6 which guides the
inner concave surface of the cage 8. The center 9 of the
convex outer surface of the caye 8 and the center 10 of
the concave inner surface of the cage 8 are located on
opposite sides of a plane containing the center of torque
transmitting balls 11.
The cage 8 further includes circumferentially spaced
window recesses 12 which retain the torque transmitting balls
11. The torque transmitting balls 11 are also carried
between a pair of oppositely positioned grooves 4 and 7 of
the outer and lnner joint members respectively. The number
of grooves ~ on the outer joint member 1 is the same as the
number of grooves 7 on the inner joint member 5, so that
corresponding pairs of grooves 4 and 7 can support a single
torque transmitting ball 11 between them. While only one
ball is shown, a plurality of such torque transmitting balls
is preferably provided. The cavity 2 of the outer joi-nt
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7~ 3g
member 1 is sealed by a concertina boot 13.
An annular stop face 27 is provided on the
interior wall of the joint member 1 within the cavity 2.
The annular stop face 27 is arranged concentric with the
axis of rotation 3. An annular bearing surface 28 on a front
end of the cage 8 is arranged for engaging the stop face 27
to determine the maximum angular displacement (or maximum
degree of deflection) between the a~es of the inner and outer
joint members.
The position of maximum angular displacement
between the inner joint member 5 and the outer joint member
1 is illustrated in Figure 2, the angle of displacement being
the angle at which the axis of the inner joint member 5 is
displaced from the axis 3. It will be noted that the bearing
- 15 surface 28 on cage 8 is in a position engaging the annular
stop face 27 on the outer joint member 1. Cage 8 is thus
prevented from any further angular rotation about the inter-
section of the axes of the inner and outer joint members by
the engagement of the beariny surface 28 with the stop f~ce
27. Even in the event of further angular displacement between
the inner joint member 5 and the outer joint member 1, the
cage 8 will not be further angularly displaced. At the
point when the bearing surface 28 first engages the stop
face 27, the axis of the inner joint member 5 will form an
obtuse angle with the axis of the outer joint member 1.
Reference numeral 30 indicates the plane which bisects this
obtuse angle. At this point of initial engagement, the
- centers of the torque transmitting balls 11 will lie in a
plane 29 which forms an angle ~ith the axis of the inner
~78~g~
joint member 5, which is less than the angle formed
between the angle bisectin~ plane 30 and the axis of the
inner joint member 5. Upon further angular deflection of
the inner joint member 5 with respect to the outer joint
~ 5 member 1, the ca~e 8 will remain st~-tionary but the balls
: 11 shift causing their centers -to lie in a plane which
forms an angle with the axis of the inner join-t member that
increases to a point larger -than half the obtuse angle
between the a~es of the inner and outer joint members until
the centers of the balls 11 lie in a plane 31. Plane 31
forms an angle with the axis of the inner joint member 5
which is larger than the bisecting angle. It will be
noted in Figure 2 that -the planes in which the centers of the
balls 11 lie pass through the point of intersection between
the axes of the inner and outer joint members.
Because of a certain amount of play between the
parts of the joint caused by manufacturing tolerances, the
plane containing the centers of the balls 11 will have a
tendency to shift in ~ direc-tion of the plane 29 as the
angle of displacement between the inner and outer joints
increases. As the inner and outer joints are further deflected
with respect to each other, the plane ln which the centers
of the balls 11 lie will shift in the direction of the angle
! bisecting plane 30 and subsequently in the direction of
: 25 plane 31 because of the tumbling movement of the cage 8 during
rotational movement causing the bearing surface 28 to strike
against the annular stop face 27. As the joint members further
deflect, the balls 11 will be caused to shift toward the edges
of the grooves 4 and 7. In the position in which the balls lie
1~7~g
in the plane 31, they will be forced back from the edges
of ~he grooves into the base of the ball receiving grooves,
: thus resulting in a higher load bearing capacity of the
] olnt .
Figure 3 illustra-tes a joint ~hich is substantl.all~
the same as the joint illustra-ted iII Figure 1 except that the
stop face 27 is positioned at -the opening of the cavity of
the outer joint member 1. In this embodiment, the stop face
27 is in the form of a chamfered surface at the front edge
of the opening. The bearing surface 28 oE the cage 8 in this
embodiment, is positioned at the -thin edge of the cage, when
viewed in cross section, rather than at the thick edge as
illustrated in Figures 1 and 2. This positioning of the
bearing surface provides means for increased static strength and stability.
The structure of the joint illustrated in the
embodiment of Figure 4 is similar to that illustrated in
Figures 1 and 2, however, in this embodiment a spring 14 is
connected to a stud or heel projection 20 on the inside of
the outer joint member 1. The spring 14 is therefore
positioned between the stop face and the bearing surface on
the cage 8. The bearing surface in this embodiment is
formed by a conical surface 21. Therefore, during angular
displacement of the inner joint member relative to the outerjoint member, the conical surface 21 of the cage 8 will first
engage the outer surface of the spring 14. Upon further
displacement the spring 14 will yield to the force exerted on
it by the conic~l bearing surface 21 up to a point of maximum
ansular displacement where the spring will not yield any
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further. The conical surface 21 will be in supporting
enga~ement with a surface on the spring 14 during
angular displacement of the joint u?wards of angles of about
20-~3~. In its functional operation, the arrangement of
Fi~ure 3 is substantially identical with that of the pre-
viously described embodiments, in as much as the conical
bearing surface 21 will be fully engaged ~ith the stop face
without further yielding oE the spring 1~ up to a given
displacement angle.
The embodiment of the joint shown in Figure 5 is
similar to that illustrated in Figure 4 in that a sprlng is
used to provide a degree of yielding movement between the
stop face and bearing surface upon engagement with each other.
~: In this embodiment, a spring 16 is secured to the cage 8
by a suitable fastening means 17. The stop face is formed by
an annular surface 23 on the inside of the outer joint member
1. Upon angular displacement of the joint members, the
tapered surface of the spring 16 will engage the annular
stop face 23.
~igure 6 illustrates a further embodiment of the
present invention, which is similar to the embodiment illus-
trated in Figure 4. In this embodiment, the spring 14 of
Figure 4 is replaced by a deformable or resilient annular
block 24, preferably made of deformable plastic material.
The annular block 24 is carried on the stud 20 of the outer
joint member 1. During angular displacement, the conical
bearing surface 21 of the cage 8 will first engage the outside
circumferential surface of the block 24. Upon further
. angular displacement, the block 24 will compress until it
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reaches a fully compressed condition defining the
ma~imum displacement angle. In the embodiment shown in
Figures 4 and 5, the spring members exert a force on
the cage tending to urge the joint members into a non-
deflected condition. Similarly, preapplied s-tresses -to
the block 24 in the embodirnent of Figure 6 will produce
a force acting on cage 8 to also urge the joint member
in-to a non-deflected position.
In the embodiment illustrated in Figure 7, a
plate spring 22, having an outside diameter corresponding
to the convex surface of the cage 8, is secured to the
cage 8 such as by riveting. It will be appreciated that
other suitable means for securing the plate spring 22 to
the cage will be equally satisfactory. A separate annular
component 25 is carried on the inside of the outer joint
member 1. An annular surface 26 is machined into tne
annular component 25 to form the stop face. An annular
portion of the surface of the plate spring 22 thus forms the
~ bearing surface for engaging the stop face 26 upon deflectlon- 20 of the joint.
Figures 8 and 9 illustrate different embodiments
of the plate spring 22. In the embodiment of Figure 8, the
plate spring is provided with a plurality of circumferentially
spaced slits 18 radially extending inwards from the outer
circumferential edge. This arrangement has the advantage
that during deflection of the joint, only that part of the
plate spring 22 which actually engages the stop face will be
subjected to ben~ing stresses or elastic action.
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~637~
The plate spring illustrated in Figure 9 is not
provided with the radially e~tending slits but can equally
function as a bearing surface.
Figures 1-7 each illustrate an embodiment o~ a
swivel joint of the kind in which the cage is guided and
supported on a steering control member 19. I'he inven-tion,
however, is equally applicable -to joi.nts of different kinds,
such as for example to "DO" joints, or o-ther cage controlled
joints.
While the present invention has been described
and illustrated with respect to certain preferred embodiments
which produce satisfactory results, it will be appreciated
by those skilled in the art, after understanding the purposes
of the invention, that various changes and modifications may
be made without departing from the spirit and scope of the
invention, and it is therefore intended to cover all such
changes and modifications in the appended claims.
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