Note: Descriptions are shown in the official language in which they were submitted.
1083371
This invention relates to universal joint and shaft
assemblies and methods of making same. The invention has been
developed primarily for application to assemblies of this kind
for use in motor road or other automotive vehicles for trans-
mitting the drive from the prime mover to driving wheels either
at the rear or at the front of the vehicle.
It is desirable to avoid or minimise vibration due to an
out-of-balance mass in such assembly, a condition which exists
when the combined centre of mass of the universal joint and
the shaft member is offset radially from, i.e. is eccentric
with respect to, the axis about which the shaft member and the
member of the universal joint to which the shaft is secured
rotate.
Such eccentricity can be brought about by the following
causes. Firstly, the axis about which the assembly of shaft -
member and the member of the universal joint connected thereto
actually rotates is determined by the axis of rotation of the
other member of the universal joint, and eccentricity may be
produced by the dimensional tolerances in the universal joint
20 itself and the accuracy of fit of the universal joint members F-
with respect to each other, i.e. presence or absence of any
radial play or lost motion. Secondly, eccentricity may be -
produced by reason of lack of accuracy with which the shaft
member is connected to that part of the universal joint member
; to which it is connected and which usually is in the form of a
stub shaft or spigot (of which the geometrical axis should
ideally be coaxial with the actual axis of rotation of the
universal joint). Thirdly, eccentricity may be produced by the
actual centre of mass of the shaft member not lying on the
geometrical axis of the shaft member, i.e. being offset radially
therefrom.
In many cases the universal joint and shaft assembly is
required to transmit drive to the input element of a combined
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reduction and differential gear, the output elements of which
are connected respectively to drive shafts which in turn are
connected to the driving wheels of the vehicle, usually but not
invariably at the rear thereof.
In such cases the shaft member which forms part of said
assembly is normally termed the propeller shaft and rotates at
an appreciably higher speed than does either of the drive shafts,
typically three or four times as high, and consequently the
elimination or minimisation of eccentricity giving rise to
vibration is especially important.
Whilst continuous research and development has been directed -
~to the elimination of the first cause of eccentricity referred
to above, it is still necessary to accept that because of -
production tolerances a significant number of assemblies will
present some eccentricity arising from the first cause but -
within said production tolerances. Furthermore, although normal
methods of joining the shaft member to the universal joint
member to which it is required to be connected, and in particular
welding methods, have been carefully designed to avoid or
minimise the second cause of eccentricity, here again it has to
be accepted that in mass production some of the assemblies
produced will exhibit eccentricity through this second cause.
With regard to the third cause of eccentricity, minimisation
of this is often somewhat beyond the control of a manufacturer
of assemblies of the kind specified in that reliance has to be
placed upon the adherence to accurate tolerances by the suppliers
of tubular stock from which such shaft members are made.
Accuracy in this respect is closely related to price and for the
price which is acceptable, having regard to the product to be
produced and its intended use, for example in mass produced
motor vehicles, it is clearly necessary to tolerate some `
eccentricity from this third cause. '
The present invention is based upon the concept that
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vibration arising from all three causes of eccentricity is
capable of being reduced if the overall mass of the assembly, -~
and in particular the shaft member, can be reduced.
Conventional practice is to make the shaft member
and the universal joint member to which it is to be connected
of a ferrous metal such as steel or cast ironj and to join
these member to each other by welding. ;
The use of welding technique for this purpose does
represent a design constraint by reason of the fact that the
10 metals employed for two members must then necessarily be selec- -~
ted to have welding compatability. Further, the use of a fer-
rous metal for the manufacture of the universal joint member
(or indeed the universal joint as a whole) is consequent upon
the necessity in a large number of applications, such as
propeller shaft in universal joint assemblies for motor vehi-
cles, to comply with strength requirements which have to be ;
met.
The present invention is based on the concept of
reducin~ the overall mass of the assembly and involves the
20 provision of a mode of securement of the shaft member to the ~-
universal joint member which overcomes the compatability
constraint.
The present invention resides in a method of making
an assembly of a shaft member and a universal joint member
characterized in that it comprises the steps of~
A. providing a shaft member of tubular form and a
universal joint member with a part which interfits with the
shaft member,
B. forming at least one of said parts to define, in
`- 30 combination with the other of said parts, a cavity for recei-
` ving an adhesive substance, said cavity being of elongate form
and extending a plurality of times around the circumference of
the interface between the interfitting parts of the shaft and
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universal joint member, ana having first and second openings
communicating with it at opposite ends of the cavity,
C. fitting such shaft member and the universal
joint member together,
D. injecting the adhesive substance through the
first said opening into the cavity, thus expelling air from
the cavity until the cavity is full of the adhesive substance,
E. subjecting the assembly to treatment to cure the
adhesive substance and establish a bond between the shaft and
10 universal joint member. -
The invention also extends to an assembly of a shaft
member and a universal joint member, characterized in that the
members have axially interfitting parts with overlapping cir- :
cumferentially extending faces, said faces defining a ca~ity :
which is of elongate form extending a plurality of times
around said circumferentially extending faces and in which is
received an adhesive substance which secures said members:to~
gether, said cavity having an inlet opening and a vent opening
communicating with it at spaced positions, said adhesive sub-
stance having been injected through said inlet opening.
Embodiments of assemblies in accordance with the
invention and methods of making such embodiments will now be
described, by way of example, with reference to the accompany-
ing drawings wherein:-
Figure 1 is a view in vertical diametral section of
a portion of a shaft and universal joint assembly showing the
connection of the shaft member to one of the members of the
universal joint and forming a first embodiment of the inven-
tion;
Figures 2 and 3 are transverse cross-sectional views
in the planes B D and A C respectively shown in Figure l;
Figure 4 is a view similar to Figure 1 illustrating
a second embodiment and method of making same;
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8337~ .
Figure 5 iS a vieW illustrating the application of
material to a mandrel for making the shaft member of the
embodiment of Figure 4 and forming an internal cavity therein. .
Referring firstly to Figure 1, the assembly comprises
a universal joint yoke member 112 and a shaft member 111. For
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convenience only one end portion of the shaft member is shown.
A like universal joint member may be provided at the opposite
end or according to requirements this other end may have other
means for connecting it in the drive or transmission line. The
universal joint member forms part of a universal joint of the
Hookes type comprising yoke members (of which only member 112 is
shown) including respective laterally spaced axially projecting
yoke arms 114, connected by base parts 116, and coupled together
by a connecting member (not shown) having two pairs of radially
projecting spigots engaged in openings in the yoke arms through
the intermediary of bearings.
All of the members of the universal joint may be formed of
a ferrous metal by casting, forging or fabricating methods in
order to provide the necessary strength for applications such `
as propeller shaft and universal joint assemblies for motor
vehicles.
The shaft member 111 is formed of a light weight material,
for example aluminium alloy, such shaft member being of tubular `;
form.
The shaft member 111 and the member 112 are secured in
assembled relationship by the provision of respective axially
interfitting parts llla and 112a, the former comprising a non-
tapering, i.e. cylindrical, integral end portion of the shaft,
and the latter comprising a spigot part 112a integral with the -
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base part 116 and having a cylindrical external face.
Between respective portions the internal face of the part
llla and the external face of the part 112a is interposed an
adhesive substance 124.
This may be in the form of thermo-setting epoxy resin which
is caused to set, after assembly of the parts, by subjecting it
to a high temperature, typically 170C.
The shaft is assembled with its part llla over the spigot
112a.
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It will be noted that portions lllg, 112g and lllh, 112h
of the adjacent axially and circumferentially extending surface
of the parts llla, 112a are in direct contact with each other,
i.e. without the intervention of any adhesive substances, and
thereby provide accurate location of the parts llla, 112a in
coaxial relation.
As a safeguard against axial separation of the parts llla,
112a these are formed with mutually cooperative formations to
prevent such separation. Thus, the member 112 of the universal `
joint is formed with a groove 125 between the spigot 112a and
the base 116, such groove presenting an axially facing shoulder
; 125a directed away from the main length of the shaft member 111
and which is engaged by a lip 126 at the free end of the tubular
shaft member produced by acting mechanically onthe extremity of
the shaft member by a pair of radially inwardly movable tools ;
such as 126a to produce permanent inward deformation.
The deformation of the shaft may be effected after heat
treatment to effect setting of the adhesive substance, or during,
or before such heat treatment as may be convenient.
If the shaft member 111 is made of an aluminium alloy there
will be a temperature limit above which it should not be raised
in order to avoid impairment of the mechanical properties, e.g.
strength of the shaft, typically this temperature would be in
the region of 200C.
Heating, therefore, would then be in the range 170C to a
temperature representing a suitable margin below 200C, such
as 190C.
The heat treatment may be effected by a batch process, i.e.
~; placing a quantity of the universal joint and shaft assemblies
in a chamber in which the atmospheric temperature is in the
range appropriate to the adhesive and materials employed, or by
passing the assemblies in succession through the chamber in which
the atmosphere is raised to the appropriate temperature.
: 1083371
In the embodiment of Figure 1 the internal face of the
part llla, and the external face of the part 112a, is of plane-
faced form, but one or both of these parts could incorporate a
system of depressions or channels as by knurling if desired.
The external face of the spigot part 112a incorporates a
passageway system for the reception of the adhesive in liquid ;`
or other flowable form. Such passageway system may comprise a
series of axially spaced circumferentially extending grooves
112c to 112f. The grooves 112e, 112f and 112c, 112 are
connected at their lower sides by axially extending grooves such
as 127 in Figure 2, while grooves 112d and 112e are connected ;
at their upper sides by an axially extending groove such as 128a
in Figure 3. Grooves 128_, 128c aligned with groove 128a also
exist in the planes A and B to provide respectively for the
admission of adhesive to the groove system through an injection
passageway 129, and for venting to the interior of the tubular
shaft 111. Such injection can be effected by engaging an
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'~ injection nozzle 129c in the entrance of the passageway 129 and
operating a pump forming part of the injection means. r`
The end part llla of the shaft 111 is a close sliding fit
on the spigot part 112a and is coaxially located by direct
contact over portions of the adjacent internal and external faces '~
between the grooves.
Alternatively the groove system may comprise a single `~
helical groove extending along the outer face of the spigot part
112a communicating at one end with the passageway 129 and at the
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opposite end with a venting groove such as 128 in the plane A.
In the embodiment illustrated in Figure 4 and the method of
~` making it illustrated in Figure 5, parts corresponding to those
already described in preceding embodiment are designated by like
reference numbers with the prefix 2 instead of 1 and the
preceding description is to be deemed to apply, reference being
made now principally to the differences.
1083371 ;
The tubular shaft member 211 which is made of an epoxy
resin mixture reinforced with longitudinally extending fibres,
for example carbon fibres, incorporates in its end part 211a
a relatively wide shallow groove 230 of helical form for the
reception of the adhesive substance 224, the latter being
injected through an opening 229 in the opposite end of the groove
230 providing venting to the interior of khe shaft member 211.
As seen in Figure 5, the groove 230 is formed by winding a
strip 231 of a material helically around a part of mandrel 232
upon which the shaft member 211 is moulded.
A suitable material for the helical strip 231 is a tape
woven of "nylon", "terylene" or "dacron". These materials are
capable of withstanding temperatures involved in curing the resin ~ ;~
component of the shaft member. ~ possible alternative to form the
tape would be a metal foil.
The shaft member 211 may be formed by winding reinforcing
fibres, for example glass fibres or carbon fibres 233, helically
around the mandrel and over the strip 231, alternate layers
being preferably wound helically in opposite hands or directions.
This step of the method is continued until a thickness nearly
equal to the desired thickness of the shaft member is achieved
and then axially extending reinforcement materials such as
carbon fibres or glass fibres 234 are laid axially over the
helical winding 233 already referred to and the whole is
impregnated with the epoxy resin mixture, for example by applying
it in flowable form by means of a brush 236.
The shaft member thus formed, and still retained on the
mandrel 232, is then subjected to heating, e.g. by passing
through an oven heated to a temperature of the order of 180C
to effect curing. The mandrel 232 is then removed axially
leaving the strip 231 in place.
The strip 231 may be left in place until the shaft member
is actually required to be assembled with its end part 211a in
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axially interfitting relationship with the part 212a of the ~-
associated universal joint. The tape is then effective to
prevent contamination of the groove 230 by air borne dirt and/or
moisture or other contaminants.
Immediately preparatory to axially interfitting assembly of
said parts, the strip 231 is removed to expose a helical
passageway 231a and axial interfitment is effected with the end
of the shaft member abutting a flange portion 235 of the
universal joint member 212. An adhesive substance 224, as
previously mentioned, is then injected through the passageway 229a,
air being expelled through vent opening 229_ at the opposite end
of the passageway 231 and the resultant assembly subjected to
suitable treatment, e.g. heating, to set the adhesive and secure
the shaft member and universal joint member together.
Instead of a woven tape, any suitable strip material capable
of holding its shape under the conditions of moulding and after
~ winding onto the mandrel may be employed, provided it is
;~ sufficiently flexible to permit it to be removed after the shaft
member has been formed. Again, whilst the helical winding of the
20 strip material is especially convenient, removable material ;~
applied in a configuration to produce`a passageway system of some
configuration other than helical may be employed if desired.
Furthermore, alternatively or in addition the part 212a of
the universal joint member may incorporate a groove in its
exterior surface.
Although the foregoing description reference has been made
to the formation of the universal joint members from a ferrous
metal, e.g. cast iron or steel, it is to be understood that
where the torque to be transmitted admits the universal joint
member could itself be formed of a light weight (low density)
material. This could be an aluminium alloy. The universal joint
member may be formed as a casting, and the joint between the
shaft member and the universal joint member could be effected
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1083371
as shown in any one of the preceding embodiments. `~
Further, the invention is of application to an assembly of
a shaft with some other form of universal joint member, e.g.
one from a constant velocity universal joint having inner and
outer members and torque transmitting rotary elements such as
balls engaging in formations such as grooves in the inner and ;
outer members.`
A possible modification which may be made to the embodiment ~ ..is`
illustrated in Figures 1 to 3 relates to the arrangement by
which the system of adhesive receiving grooves is vented to
provide for egress of air from the grooves as adhesive is
introduced. In the embodiment depicted in Figures 1 to 3, it is ;~
possible that adhesive escaping into the interior of the shaft
i from groove 128c could become detached from the adhesive
remaining in the groove and be free to move around inside the
shaft, providing a potential source of noise in service. To ~-
overcome this, venting may be arranged to occur to atmosphere
; outside the shaft. This may be done by extending the passageway
129 to open into the groove 112c most remote from the end of the
shaft, whilst a vent groove communicates with groove 112f.
Alternatively, the same arrangement of passageway 129 could be
employed as in Figure 1, with groove 112c communicating with a
small aperture extending radially through the tubular end part
llla of the shaft 111.
It is to be understood that, when we refer to the shaft
member being made of a material having a substantially lower
density than ferrous metals of which such member is normally
made, we refer to the average density of the shaft member as a
whole. In the case of a shaft member formed of a compositive
material, a component or componenks of the shaft may, taken
individually, present a density of the order of, or even greater
than, the density of ferrous metals, and yet the shaft member
as a whole have an average density less than that of such
10833~
ferrous metals. ~;
In the embodiment shown in Figure 4, a sealing component ,
of suitable form may be provided, if neceSsary, between the end
of the shaft part 211a and the flange portion 235 of the .
universal joint member 212, to prevent leakage of adhesive at
this point.
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