GB2041105A

GB2041105A - A sealed support bearing

Info

Publication number: GB2041105A
Application number: GB7902445A
Authority: GB
Original assignee: SERVICES GH PLANT Ltd AK
Current assignee: SERVICES GH PLANT Ltd AK
Priority date: 1979-01-23
Filing date: 1979-01-23
Publication date: 1980-09-03

Abstract

A sealed support bearing for a shaft of a power steering unit of a vehicle comprises a cylindrical housing 20 with a cylindrical bronze bearing 22 coaxially located in it. One side of the bearing is open to the operating oil from the steering unit itself, but passage of this oil right through the bearing is restricted or prevented by a coaxially arranged natural or synthetic rubber sealing ring 24 located on, that side of the bearing remote from the main body of the steering unit itself. A scraper ring 28 on the side of the sealing ring remote from the bearing prevents ingress of dirt and moisture to the bearing. In this way the operating oil of the steering unit is used to lubricate the bearing thereby to increase its life and in the end reduce leakage of the oil. <IMAGE>

Description

SPECIFICATION A sealed support bearing The present invention relates to a sealed support bearing for a power steering unit of a vehicle.

In presently known rack and pinion units, the oil is supplied under pressure to one side or the other of a unit in dependence upon the torque applied to the vehicle steering wheel to provide power assistance in turning the steered wheels in the desired direction. The rack is joined at opposite ends respectively to respective piston rods which are disposed for movement into and out of respective cylinders. At the outer ends of these cylinders remote from the rack there are disposed respective seals surrounding the corresponding pistons. In these known units in the past movement of the piston rods into and out of the respective cylinders causes wear of the seals resulting in loss of oil and possible eventual failure. Furthermore, the aount of play of the piston rods in their seals reduces the sensitivity and feel of the steering mechanism to the vehicle driver.

According to the present invention, there is provided a sealed support bearing for a power steering mechanism comprising a housing, a bearing member fitted into the housing and coaxial with it, a sealing member disposed adjacent the bearing member such that in operation pressure fluid from the steering mechanism is allowed access to the bearing member but is prevented from passing through the seal by the sealing member and a back up ring disposed coaxially on that side of the sealing member remote from the bearing.

A preferred embodiment of the invention may comprise any one or more of the following advantageous features: (a) The housing is internally and externally cylindrical and is formed with an internal shoulder which locates the bearing member.

(b) The bearing member is internally and externally cylindrical and is formed with an external flange which abuts the internal shoulder of (a).

(c) The bearing member is made of bronze.

(d) The sealing member is made of natural or synthetic rubber.

(e) The back-up ring is a phosphor-bronze ring.

(f) A scraper seal is disposed on that side of the back-up ring remote from the sealing member.

In order that the invention may be more clearly understood, one embodiment thereof will now be described, by way of example, with reference to the accompanying drawing in which: Figure 1 diagrammatically shows a power steering mechanism and Figure 2 is an exploded view of a sealed support bearing according to the invention and forming a part of the mechanism of Fig.

1.

Referring to the drawing, the mechanism basically comprises a rack 1, pinion 2 and right and left piston rods 3 and 4 disposed for lengthwise movement in corresponding right and left cylinders 5 and 6. The outer ends of these cylinders 5 and 6 are sealed by respective seals of sealed support bearings 10 and 11 which coaxially surround the corresponding piston rods 3 and 4. The cylinders 5 and 6 are connected via pressure fluid liners 7 and 8 to a central pressure fluid pump unit 9. In operation of the steering, pressure fluid is fed to, for example, the right cylinder under pressure via line 8 in proportion to the torque applied to the vehicle steering wheel by the vehicle driver when turning the wheel to the right.The movement of the rack 1 to the right due to the turning of the pinion 2 by the steering wheel is thereby assisted by this pressure fluid and the right hand piston rod 4 moves outwardly through the bearing 11 under the action both of the force of the pressure fluid and the force of the pinion on the rack.

Referring to Fig. 2, each bearing 1 0, 11 comprises a cylindrical housing 20 made of steel and defining a shoulder 21 on internal surface. A bronze bearing 22 for the corresponding piston rod is made a press fit in the housing 21. This bronze bearing is provided with an external flange 23 which, in position, abuts the shoulder 21. Adjacent the flange 23, and of the same internal and external diameter, is a sealing ring 24 of natural or synthetic rubber having a slightly peaked internal surface and an annular slot 25 cut into that face of the ring remote from the bearing 22. This annular slot receives an anti extrusion nylon ring 26. A phosphor bronze backup ring 27 having an internal diameter equal to that internal diameter of the bearing 22 and an external diameter equal to that of the housing 20 abuts the face of the nylon ring 26. The bearing is completed by a scraper ring 29 which prevents ingress of foreign matter from outside the bearing into the bearing.

With bearings, as above described, loss of oil from the cylinders is reduced or prevented for longer periods than hitherto, thus increasing the overall life of the steering unit. The main metal bearing surface in contact with the shaft is of a wear resistant material and is well lubricated from the oil which constitutes the operative pressure fluid. Furthermore, the reduction in play in the bearing provides for a better steering "feel" for the vehicle driver.

It will be appreciated that the above embodiment has been described by way of example only and that many variations are possible without departing from the scope of the invention.

Claims

1. Ataled support-bearing for a power steerin6iechanism corpprising a housing, a bearing;member fitted into the housing and coaxial with it, a sealing member disposed adjacent the bearing member such that in operation pressure fluid from the steering mechanism is allowed access to the bearing member but is prevented from passing through the seal by the sealing member and a back up ring disposed coaxially on that side of the sealing member remote from the bearding.

2. A sealed support bearing as claimed in Claim 1, in which the housing is internally and externally cylindrical and is formed with an internal shoulder which locates the bearing member.

3. A sealed support bearing as claimed in Claim 1 or 2, in which the bearing member is made of bronze.

4. A sealed support bearing as claimed in Claim 1, 2 or 3, in which the sealing member is made of natural or synthetic rubber.

5. A sealed support bearing as claimed in any preceding claim, in which the back-up ring is a phosphor-bronze ring.

6. A sealed support bearing as claimed in any preceding claim, in which a scraper seal is disposed on that side of the back-up ring remote from the sealing member.

7. A sealed support bearing for a power steering mechanism substantially as hereinbefore described with reference to the accompanying drawings.

8. A power steering unit for a vehicle comprising a sealed support bearing as claimed in any preceding claim.