Rolling bearings for strut-type suspensions

In a rolling bearing for strut-type suspensions, a rotary bearing race 33 has, at its radially inner part, a cylindrical portion 37 having an outwardly extending flange 38. The radial inner end part 41 of the stationary bearing race 34 of the bearing is disposed at such a position so as to be overlapping with the outwardly extending flange 38. At least one of the above-mentioned members confronts and overlaps the other and includes a member having self-lubricating characteristics.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates to a rolling bearing for a strut-type suspension. 
More specifically, the present invention concerns a shell-type ball 
bearing through which a piston rod of a shock absorber of a motor vehicle 
can be inserted. 
2. Prior Art: 
Strut-type suspensions for motor vehicles are well known. Typifying such 
suspensions is that shown in FIG. 3 of the drawing. Generally, prior art 
strut-type suspensions include a piston rod 10' associated with a shock 
absorber. The piston rod 10' is inserted through an opening in a rotary 
bearing race 3' of a ball bearing 2' and the inner face of an upper seat 
11' for a coil spring 13'. The seal 11' carries the lower axial end of the 
rotary race 3'. The rotary race 3' is fixed in position on the shoulder of 
the piston rod 10'. These two members are fixed tightly to the piston rod 
10'. 
Ordinarily, according to the prior art the coil spring 13' is disposed 
between the upper spring seat 11' and a lower seat (not shown) which 
receives or seats the opposite end of the spring 13'. The lower seat is 
fixedly attached to an outer cylinder of the shock absorber such that the 
coil spring 13' encircles the piston rod 10'. A stationary bearing race 4' 
of the ball bearing 2' is fixed in position to a lower plate 15' of a 
shock absorbing rubber buffer mount assembly 14'. The buffer mount 14' 
comprises an integrally formed upper plate 16', the lower plate 15' and a 
rubber buffer 17' interposed between the upper plate 16' and the lower 
plate 15'. The buffer 17' is integrally adhered to the two plates 15' and 
16' by vulcanizing. The upper plate 16' is attached by a bolt 19' to a 
mounting plate 18' of the motor vehicle. Usually a dust cover 20' is 
incorporated into the structure. 
When the wheels of a vehicle are turned in a different direction by the 
steering wheel of the vehicle, the piston rods 10' of the vehicle shock 
absorbers will also rotate, along with the outer cylinders of the piston 
rods 10'. Thus, both a radial load and a thrust load, applied to each 
shock absorber, can be supported by the ball bearing 2' associated 
therewith. 
As explained above, ordinary type bearing perform, both, as a thrust 
bearing and a radial bearing. However, it is increasingly required to use 
ball bearings of relatively larger size having larger bearing width in 
order to obtain a predetermined increased loading capacity. In order to 
achieve this the stroke length of the shock absorber must be shortened, 
due to the limited mounting height allowed for the bearing. This decreases 
the extent of shock absorbing capacity. 
Use of a shell-type needle roller bearing having a considerably small 
bearing width may solve the aforesaid problem to some extent. However, 
such prior art needle roller bearings result in worse steering 
performance. This is attributable to the larger torque required by the use 
of needle roller bearing. 
In British Patent Specification No. 1446000 there is disclosed a rolling 
bearing for suspension struts which can solve many of these problems 
mentioned above. However, the bearing in the British Patent still cannot 
avoid mutual metal-to-metal contact in the axial direction, between the 
stationary bearing race and the rotary bearing race, in the assembly, due 
to the vibration of the vehicle to which the struts are applied. Hence, 
there is encountered various wear breakage at the points to contact, 
together with damage to the rubber buffer mount caused by metal powders 
formed by the wear breakage. This creates various undesirable effects on 
the durability of the suspension struts. 
The present invention, as will subsequently be described, solves such 
drawbacks in the prior art strut-type suspension. 
OBJECTS OF THE INVENTION 
An object of the present invention is to provide a strut-type suspension 
which can lengthen the stroke of the shock absorber to which the 
suspension strut is to be applied by reducing the mounting height of the 
rolling bearing to be incorporated therewith. 
Another object of the invention is to provide a bearing for strut-type 
suspensions which requires less torque and imparts almost no harmful 
effect on the steering performance of the motor vehicle to which the 
suspension strut is applied. 
A still further object of the invention is to provide rolling bearings for 
strut bearings which withstand longer service life. 
SUMMARY OF THE INVENTION 
According to the present invention, a shell-type roller bearing having 
strut-type suspension comprises, (a) a rotary bearing race, the 
cylindrical portion of which is formed to have an outwardly extending 
annular flange, (b) a stationary bearing race, the radially and axially 
innermost end of which is bent radially inward, so as to be overlapped 
with the outwardly extending flange of the rotary race, and (c) wherein at 
least one of the confronting portions of the races is formed from a member 
having self-lubricating characteristics. 
This construction enables a reduction in the mounting height of the 
bearing. Thus, the stroke of the shock absorber can be much longer, while 
lowering the bearing torque considerably. Furthermore, this construction 
can prevent both damage to the bearing due to wear at the bearing races 
and lowering of its durability caused by undesirable effects to its 
mounting rubber. 
By so configuring the suspension, metal-to-metal contact between the 
stationary bearing race and the rotary bearing race can be prevented, even 
if the piston rod of the suspension means is axially moved by any heavy 
vibration of the vehicle. Thus, any harmful wear on the overlapped 
portions of the two mating bearing races can be prevented, thereby 
resulting in no harmful abrasion of the rubber buffer mount due to metal 
powders formed by wear of the races. This ensures longer service life of 
the strut-type suspension. 
For a more complete understanding of the present invention reference is 
made to the following detailed description and accompanying drawing. In 
the drawing like reference characters refer to like parts throughout the 
several views, in which:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawing, and in particular, FIG. 1, there is depicted 
a piston rod 10 incorporated into a shock absorber. According to the 
present invention a roller bearing 30 is disposed in an overlapping manner 
on the surface of an upper seat 11 which, also, defines a seat for a coil 
spring 13. 
The bearing 30 is constructed as a shell-type ball bearing, wherein a 
plurality of bearing balls 35 are accommodated, as rolling members, 
between a rotary bearing race 33 and a stationary bearing race 34, to 
provide an angular contact therebetween. Each rotary race 33 and 
stationary race 34 is fabricated by press forming a thin steel sheet. 
On the surface of the rotary bearing race 33 and at the innermost radially 
peripheral portion thereof a bushing 45, made of a synthetic resinous 
material, is concentrically affixed. Fixing of the bushing 45 to the 
radial inner peripheral portion of the rotary bearing race 33 is done by 
inserting a plurality of protrusions 46, formed at a suitable distance on 
the axial end of the bushing 45, into respective recesses formed along the 
radial inner peripheral portion of the rotary bearing race 33. The bushing 
45 comprises a cylindrical portion 37 fixed to the rotary bearing race 33 
and an integrally formed flange 38, which is formed on the axial top end 
of the cylindrical portion 37. The flange 38 extends radially outward from 
the top of the cylindrical portion. Accordingly, the rotary bearing race 
33 includes, in turn, at its radial inner side thereof, the cylindrical 
portion 37 and the flange 38. 
The stationary bearing race 34 comprises, at its radial outer margin, a 
straight cylindrical portion 41, which extends downward from the radial 
outer margin, and a radial inwardly extending flange 42 contiguously 
formed by bending the lower part of the cylindrical portion 41 inwardly. 
The stationary bearing race 34, also, comprises a cylindrical portion 43a 
which constitutes a radial innermost portion and an intermediate annular 
shoulder portion connecting the two cylindrical portions 41 and 43. 
The inner surface of the cylindrical portion 43a, formed on the radial 
innermost part of the stationary bearing race 34, is disposed closely 
around the outer surface of the cylindrical portion 37 of the rotary 
bearing race 33. 
The outwardly extending flange 38 of the rotary bearing race 33, formed at 
the axial end of the cylindrical portion 37, is disposed above the axial 
upper part of the radial innermost portion of the shoulder portion 43, 
namely, above the axial top end of the cylindrical portion 43a of the 
stationary bearing race 34, such that the two members can be disposed in 
overlapping relation. 
In addition, at the position axially under the radial outer part 39 of the 
rotary bearing race 33, the inwardly directed flange 42, formed at the 
lower end of the cylindrical portion 41 at the radial outer end of the 
stationary bearing race 34, is positioned so that these two members lie in 
an overlapping relationship. 
In an assembled state, where a pre-determined number of bearing balls 35 
are accommodated between the two mating bearing races 33 and 34, the axial 
clearance .delta..sub.1 between the outwardly extending flange 38 and an 
upper plate 16 is smaller than the clearance .delta..sub.2 that is formed 
between the inwardly extending flange 42, at the end of the cylindrical 
portion of the stationary bearing race 34, and the radially outer end 
portion 39 of the rotary bearing race 33. 
The rolling bearing of FIG. 1 is assembled, first, by inserting the piston 
rod 10 into an opening formed in the cylindrical portion 37 of the rotary 
bearing race 33. Next, the assembled member is, concentrically laid upon 
the spring seat 11, which is fixed in position on the shoulder of the 
piston rod 10 and, then, by fastening, through a washer 50, a nut 12 by 
tightening it along the screw threads formed on the piston rod 10. 
Since the rolling bearing of this embodiment is a shell-type one wherein, 
both, the rotary bearing race 33 and the stationary bearing race 34 are 
fabricated of a steel sheet of thin thickness, it can afford not only a 
reduced height for mounting, but, also, angular contact between the balls 
35, the rotary race 33 and the stationary race 34. This ensures support 
for both a thrust load and a radial load. Yet, the torque for a required 
load capacity can be maintained the same as that obtainable from the 
ordinary type of ball bearing. 
In the rolling bearing 30, both the rotary race 33 and the stationary race 
34 have respective cylindrical portions 37 and 41. The cylindrical portion 
37 has an radially outwardly extending flange 38 at its upper axial end. 
The cylindrical portion 41 has a radially inwardly extending flange 42 at 
its lower axial end which lies under the radially outer part 39 of the 
rotary bearing race 33 and the radially inwardly extending flange 42 of 
the stationary bearing race define the bearing 30 as a non-separable type 
bearing. The radial inner end face of the cylindrical portion 43a is 
positioned adjacent to the outer face of the cylindrical portion 37 of the 
rotary bearing race 33. In addition, the clearance .delta..sub.1 formed 
between the end flange 38 of the rotary bearing race 33 and the upper 
plate 16 and the clearance .delta..sub.2 defined between the inwardly 
directed flange 42 of the cylindrical portion 41 of the stationary bearing 
race 34 and the radial outer end portion 39 of the rotary bearing race 33, 
are set to satisfy the relationship .delta..sub.1 &lt;.delta..sub.2. 
By virtue of this construction, even when the body of the vehicle is raised 
upward by a jack or other means, away from the ground level, the outwardly 
extending flange 38 of the cylindrical portion 37 of the rotary bearing 
race 33 of the bearing 30 is kept in contact with the upper face of the 
upper plate 16. In this manner the flange 42, extending inwardly from the 
axial end of the cylindrical portion 41 of the stationary bearing race 34, 
will never be deformed under any undesirable load. Furthermore, any radial 
movement of the rotary bearing race 33, due to oscillation of the shock 
absorber, will urge the outer surface of the cylindrical portion 37 of the 
rotary bearing race 33 into contact with the cylindrical face at the 
radial inner end 43 of the stationary bearing race 34 so as to function as 
a stopper. Accordingly, the rotary bearing race 33 can never be radially 
moved out of position. 
Since the flange 38 formed on the bushing 45 is made of a synthetic 
resinous material and has self-lubricating property, any mutual contact 
between the flange 38 and the upper plate 16 is now different from 
metal-to-metal contact between two mating rigid bodies, such as in the 
prior art. Any contact rendered herein becomes a contact with reduced 
abrasion wear and is free from the formation of metal powders. 
By utilizing a synthetic resinous bushing 45, not only the step of caulking 
the peripheral end of the cylindrical portion of the rotary bearing race, 
but, also, any special heat treatment for preventing work hardening of the 
caulked portion can be eliminated. This contributes to a simplification of 
the manufacturing process for making this kind of rolling bearing. 
Referring, now, to FIG. 2 there is depicted an alternate embodiment of the 
present invention. According to this embodiment, the bushing 55 comprises 
a cylinder 57 fabricated of a synthetic resinous material and a flange 58 
made of an annular steel disc. The lower surface of the flange 58 is 
backed with either a member 58a having self-lubricating properties, such 
as a washer made of a synthetic resinous material, or it can be coated or 
plated with a suitable solid lubricating material, such that it can be 
confronted with the upper end face of the bushing 55. Preferably, by 
coating or plating the lower or undersurface there is a reduction in the 
number or parts to be made and, thus, assembly is simplified. 
In all other respects the construction is the same as in the first 
embodiment.