GB2024122A

GB2024122A - Steering wheel assembly

Info

Publication number: GB2024122A
Application number: GB7913399A
Authority: GB
Original assignee: Towmotor Corp
Current assignee: Caterpillar Industrial Inc
Priority date: 1978-06-30
Filing date: 1979-04-18
Publication date: 1980-01-09
Also published as: CA1107836A; GB2024122B

Abstract

A steering wheel assembly (12) has a steering column (14) and a steering wheel (16) which is rotatably movable relative to the steering column (14). A supporting member (20) is connected to the column (14) and a rotatable member (50) connected to the steering wheel (16) is positioned about the column (14) to move with the steering wheel (16) relative to the supporting sleeve (20) in a rotary direction. A sensing device (66, Figure 4) is positioned between the rotatable member (50) and supporting member (20) to sense rotation of the steering wheel (16). The steering wheel (16) is connected to the rotatable member (50) in such away as to ensure that only rotational movement is transferred from the steering wheel (16) to the member (50). <IMAGE>

Description

SPECIFICATION Steering wheel assembly The invention relates to steering wheel assemblies and, more particularly, to an apparatus for detecting rotary motion of a rotatable steering wheel.

Power steering systems often have rotatable steering wheels which are rotated to steer the vehicle.

Since system reacts to the rotation of the steering wheel to provide fluid power for steering, it is important to know when the steering wheel rotates.

Sensing rotation of the steering wheel with precision is difficult because standard motion sensing devices must be precisely aligned. Alignment is difficult because members of the power steering system such as the steering wheel and steering column move relative to each other during normal use.

It is desirable to have an apparatus which accurately senses rotation of the steering wheel and is not affected by other relative motion between the steering wheel and steering column.

According to the present invention, a steering wheel assembly has a steering column; a steering wheel connected to the column and rotatably movable relative to the column; a supporting member positioned about the column and connected thereto; a rotatable member positioned about the column and rotatable relative to the supporting member with the steering wheel; and means positioned between the rotatable member and supporting member, for sensing rotation of the rotating member, the supporting member Preferably, the rotatable member moves with the steering wheel only in a rotary direction thus ensuring precise control.

Three similar examples of a steering wheel assembly according to the invention will now be described with reference to the accompanying drawings in which Figure lisa diagrammatic, partial longitudinal sectional view of a first example; Figure 2 is a diagrammatic transverse view taken along line ll-ll of Figure 1; Figure 3 is a diagrammatic transverse crosssection taken on line Ill-Ill in Figure 2; Figure 4 is a diagrammatic view similar to Figure 1 but illustrating a second example; and, Figure 5 is a diagrammatic view similar to Figures 1 and 4, but illustrating a third example.

Figure 1 shows a rotary motion sensing apparatus 10 provided for a steering wheel assembly 12. The steering wheel assembly 12 has a hollow steering column 14 and a steering wheel 16 positioned atop the column 14. The wheel 16 is connected for steering a vehicle in a conventional manner and rotates relative to the column 14 about the longitudinal axis 18 of the column 14.

The apparatus 10 includes a supporting sleeve 20 having a central hub portion 22 and a peripheral, cup-like portion 24 which has an axially extending lip 26 and a flange 28 extending outwardly from the lip 26. A shoulder or ridge 30 which extends inwardly from the lip 26 towards the hub 22 and the lip 26, flange 28 and shoulder 30 have an inverted "T" cross-sectional configuration as can be seen in Figure 1.

The supporting sleeve 20 is positioned about the circumference of the column 14 with the hub 22 partially extending along the length of the column 14. The portion of the hub 20 nearest the steering wheel 16 has a recess 32 which has an 'L' shaped configuration with the long leg of the "L" being parallel to the axis 18 and with the shorter leg extending radially outwardly towards the periphery 24.

The lower portion of the hub 22 forms a clamp 36 for connecting the hub 22 and sleeve 20 to the steering column 14. The clamp 36 consists of two flanges 38,40 each having an opening 42,44 through which a nut and bolt assembly fit 46. The flanges 38,40 are spaced apart so that as the bolt is tightened, the flanges 38, 40 are drawn together thereby securing the hub 22 to the column 14.

In the example shown in Figure 4, the upper portion of the hub 22' of the supporting sleeve 20' has a flat end 48 instead of the recess 32, the flat end 48 being spaced a preselected distance from the steering wheel 16'.

The apparatuses 10 of Figures 1 to 4 include a rotating member 50 positioned about the column 14 and rotatable relative to the supporting sleeve 20.

The rotating member 50 has a central hub portion 52 which, in the first example is seated in the sleeve indentation 32 and a peripheral cap-like portion 54 which has a downwardly extending lip 56. In the second example the hub of the rotating member 50 sits atop the hub 22' of the supporting sleeve 20' and closely surrounds the column 14.

The sleeve lip 26 and the rotating member lip 56 lie closely adjacent each other in the assembled position and define a chamber 58. An opto-interrupter 60 having an infra red light source 61 is mounted on a circuit board 62 and positioned within the chamber 58 with the circuit board 62 resting on the shoulder 30.

The rotating member 50 has a plurality of teeth 64 which are arranged for intermittently interrupting the beam of light emitted by the opto-interrupter. In the first and second examples the tooth-to tooth separation was 11 degrees and 15 minutes. The teeth 64 are opto-interrupter 60 comprise a sensing - means 66 for sensing rotation of the rotating member 50 relative to the supporting sleeve 20; a signal from the sensing means 66 being used to enable steering control to be carried out, such as by causing actuation of a solenoid operated valve to allow fluid to pass to a steering control valve, the degree of steering being achieved independently through the steering column shaft (not shown).

Connecting means 70 connects the rotating member 50 to the steering wheel 16 for transferring only rotary motion of the wheel 16 to the rotating member 50 to maintain proper alignment of the teeth 64 and opto-interrupter 60. The connecting means 70 includes a flange 72 which extends outwardly away from the hub 22 and upwardly away from cap-like portion 54 in a direction towards the steering wheel. The flange 72 has a threaded opening 74 and a set screw 76 screw-threadably positioned therein. The set screw 76 engages with an opening 78 in the base of the steering wheel 16 ad when the wheel 16 rotates, the set screw 76 is rotated with it. The screw 76 and opening 78 are sized so that only rotary wheel motion is transferred to the set screw 76 and on to the rotating member 50.This is accomplished by providing sufficient space between the screw 76 and walls of the opening in the axial direction in which it is desired to not transmit motion.

In the third example shown in Figure 5, the lip of the supporting sleeve 20 is modified so that it has an external sloping step configuration and an internal "L"-shaped configuration.

The steering wheel 16' has a downwardly extending protrusion 80 which is generally aligned with, but spaced a small distance from, the sloping step-shaped lip 26' thus forming a chamber 58'. The wheel 16' has a second protrusion 82 which abuts the top of the sleeve 20' or column 14'.

The rotating member 50' has a hub portion 52' and the plurality of teeth 64. The rotating member 50' is connected to the wheel 16' by set screw 76' which is preferably threadably mateable with the opening 78' in the wheel 16'. The relationship between the screw 78' and rotating member opening 74' is such that only rotary wheel motion is transferred to the rotating member 50'.

As an operator rotates the steering wheel during normal steering manoeuvre, the wheel rotates about the axis of the column in a place perpendicular to the axis. As the wheel rotates, motion is imparted to the set screw, and because of the space which exists between the set screw and opening into which it projects only motion in a plant perpendicular to the axis of the column is transferred to the rotatable member 50, 50'.

The close fit between the hub of the rotating member and the sleeve indentation recess or column maintains concentricity between rotating member and the cup-like portion 24 and resists motion of the rotating member 50 other than rotary motion. In this manner, the teeth 64 are always properly aligned for proper operation of the opto-interrupter 60.

Claims

1. A steering wheel assembly having a steering column; a steering wheel connected to the column and rotatably movable relative to the column; a supporting member positioned about the column and connected thereto; a rotatable member positioned about the column and rotatable relative to the supporting member with the steering wheel; means positioned between the rotatable member and supporting member, for sensing rotation of the rotating member relative to the supporting member; and means for connecting the rotatable member to the steering wheel so as to transfer only rotary motion to the rotatable member from the steering wheel.

1. A steering wheel assembly having a steering column; a steering wheel connected to the column and rotatably movable relative to the column; a supporting member positioned about the column and connected thereto; a rotatable member positioned about the column and rotatable relative to the supporting member with the steering wheel; and means positioned between the rotatable member and supporting member, for sensing rotation of the rotating member relative to the supporting member.

2. A steering wheel assembly according to claim 1, including means for connecting the rotatable member to the steering wheel so as to transfer only rotary motion to the rotatable member.

3. A steering wheel assembly according to claim 1, or claim 2, wherein the sensing means includes an opto-interrupter having an infra red light source connected to one of the supporting member and rotatable member and a light interrupter connected to the other of the rotatable member and supporting member respectively.

4. A steering wheel assembly according to any of claims 1 to 3, wherein the supporting member and steering wheel define a chamber and wherein the sensing means is positioned within the chamber.

5. A steering wheel assembly according to any of claims 1 to 3, wherein the supporting member and rotatable member define a chamber, the sensing means being positioned within the chamber.

6. A steering wheel assembly according to any of claims 1 to 5, wherein the supporting member has an annular recess adjacent the column and the rotatable member has a hub seated in the recess.

7. A steering wheel assembly according to claim 1, substantially as described with reference to the accompanying drawings.

New claims or amendments to claims filed on 30 Aug 1979 superseded claims 1 and

2.

New or amended claims: Claim 2 deleted, appendant claims 3 to 7 renumbered and appendancies corrected.