AU743318B2

AU743318B2 - A steering system for a vehicle

Info

Publication number: AU743318B2
Application number: AU45217/97A
Authority: AU
Inventors: Andrew James Smith
Original assignee: AJ&JP Smith Ltd
Current assignee: AJ&JP Smith Ltd
Priority date: 1996-11-13
Filing date: 1997-11-13
Publication date: 2002-01-24
Anticipated expiration: 2017-11-13
Also published as: NZ299747A; AU4521797A

Description

1

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name of Applicant/s: Actual Inventor/s: Address of Service: Invention Title: A J J P SMITH LTD Andrew James SMITH SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 "A STEERING SYSTEM FOR A VEHICLE" The following statement is a full description of this invention, including the best method of performing it known to us:- (File: 20312.00) A VEHICLE STEERING SYSTEM This invention relates to a steering system for a vehicle. More particularly, but not exclusively, the present invention relates to a system for steering the wheels of a vehicle such as a "cherry picker" from a cab suspended from a boom above the ground.

Conventional steering systems for vehicles in which the wheels are controlled remotely include a lever which is operated to the left or right to activate the steering system. A disadvantage with this system is that the lever resets back to a neutral position after activation, thereby not indicating to the operator the angular position of the wheels. Consequently, the vehicle may be manoeuvred in an undesired direction as the operator does not have any indication as to the angular position of the wheels.

i It is an object of the present invention to provide a steering system for a vehicle which overcomes at least some of the abovementioned problems, or at least to provide the public with a useful choice.

According to one aspect of the invention there is provided a steering system for a vehicle S"including: an actuator to steer the wheel(s) of a vehicle; S" an input device having a movable control element; eee°• a control means responsive to the input device to control the actuator; and wheel position sensing means which senses the angular position of the wheel(s) S and provides an indication as to the angular position of the wheel(s) to the control means, wherein the position of the movable control element indicates to a user the angular position of the wheel(s).

A piston of a hydraulic cylinder preferably drives the wheel(s) of a vehicle depending upon the fluid supplied to the chambers of the cylinder via an hydraulic valve. The control means preferably includes a lever, the position of which corresponds to the position of the wheel(s).

-2- According to a first embodiment the position sensing means includes a cable connected to an arm which rotates with a wheel of the vehicle and provides position information to the control means via a first cable. The lever preferably provides user inputted control signals to the control means via a second cable. The first and second cables are preferably connected to first and second ends of a mechanical linkage with the mechanical linkage being connected at an intermediate point to the control arm of the hydraulic valve.

According to a second embodiment the position sensing means is an electrical sensor and the control means includes an electronic input device. In this embodiment the control means includes an electromechanically controlled valve responsive to signals received from the input device and electronic sensor.

Further aspects of the invention, which should be considered in all its novel aspects, will become apparent from the following description, given by way of example of i possible embodiments thereof and in which reference is made to the accompanying :I drawings wherein: °eoeo Figure 1: shows a schematic diagram of a steering system for a vehicle according to a first embodiment.

°•ooo Figure 2: shows diagrammatically the effect when the control lever is moved to 25 the left.

Figure 3: shows the equilibrium position of the steering system once the wheels have been moved to a position corresponding to the position of the lever.

Figure 4: shows an electromechanical embodiment.

RReferring to figure 1, a mechanical embodiment implemented in a vehicle having two steering wheels is shown. Piston 2 divides cylinder 1 into first and second chambers -3and 6. Rods 3 and 4 are connected to piston 2 and move the distal ends of steering arms 11 and 12 as piston 2 is moved to and fro. Steering arms 11 and 12 are pivotally connected at points 3a and 4a to rods 3 and 4 and pivot about pivot points 1 la and 12a. Accordingly, movement of piston 2 causes steering arms 11 and 12 to rotate about pivot points 1 la and 12a to alter the orientation of wheels 7 and 8 with respect to the vehicle.

Pump 9 provides pressurised fluid to valve 10 via fluid line 13. Fluid from chamber or 6 leaves valve 10 via line 14 to a reservoir within pump 9. The fluid paths through valve 10 are defined according to the position of control arm 19. When control arm 19 is inclined upwardly (as seen in figure 1) pressurised fluid is supplied from line 13 to chamber 6 and from chamber 5 via line 14 to the reservoir in pump 9. When the 15 control arm is inclined downwardly the flows are reversed.

"Control armnn 19 is connected to mechanical linkage 18 via a pivotal connection at 18a.

Cable 22 is connected to one end of mechanical linkage 18 and cable 24 is connected S.:i to the other. Cable 22 is connected at the other end to the end 17 of a lever 15 which is pivotable about pivot point 16. Cable 24 is connected to a disc 23 connected to o•••o steering arm 11.

The operation of the steering system will now be described with reference to figures 1 .o.ooi Sto 3. Figure 1 shows the initial state where wheels 7 and 8 are steering straight and :go 25 lever 15 is in its mid position. Figure 2 shows the situation when a user moves lever S015 to the left. The point of connection 17 of cable 22 to lever 15 is thus moved to the right causing end 18b of mechanical linkage 18 to pivot about point 18c and thus raise pivot point 18a so that control arm 19 is moved upwardly. The movement of control arm 19 causes valve 10 to direct pressurised fluid from line 13 to chamber 6 and flow from chamber 5 via line 14 to the reservoir in pump 9. This causes piston 2 to move to the left as shown in figure 3. This causes rods 3 and 4 to rotate steering arms 11 and 12 about pivot points 11 a and 12a so that the wheels 7 and 8 steer to the left (as 1 shown in figure 3).

-4- The rotation of steering arm 11 rotates disc 23 which causes cable 24 to push point 18c down to the position shown in figure 3. Once wheels 7 and 8 have turned to the position required by lever 15, point 18c will have moved to a position so that control arm 19 has returned to its neutral position.

It will be appreciated that should lever 15 now be moved to the right, point 18b will be moved down so that control arm 19 is inclined downwardly to supply pressurized fluid from line 13 to chamber 5 and return fluid from chamber 6 via line 14 to the reservoir in pump 9. As the wheels move point 18c moves upwardly to return control arm 19 to its neutral position.

Referring now to figure 4 an electromechanical implementation is shown. In this implementation light integers are given the same numbers as in figures 1 to 3. In this 15 embodiment an electronic sensor 30 provides an electronic signal via line 31 to electronic control module 32. The electronic sensor may be a rheostat, optical, S. -electronic sensor etc. The input device in this case is ajoy stick which provides .i electrical control Signals via line 34 to control module 32. It will be appreciated that any suitable electronic input device 33 may be substituted.

oooo.i Electronic module 32 compares the signal from sensor 30 indicative of the position of wheel 8 with the position demand signal from joy stick 33 to produce an output signal to drive electromechanical hydraulic valve 36. When joy stick 33 is moved to the left electronic control module will send a signal via line 35 to electromechanical oo 25 hydraulic valve 36 to supply pressurised fluid to chamber 6 and remove fluid from Schamber 5 so as to rotate steering arms 11 and 12 counter clock-wise.

Electromechanical hydraulic valve 36 will continue to drive piston 2 to the left until sensor 30 indicates to electronic control module 32 that the desired position has been obtained. Operation is thus similar to that described in relation to the mechanical embodiment. The electronic control module 32 may be simple electronic circuitry or a microprocessor controller. It will be appreciated that input device 33 may supply steering information via control lines or remotely via a wireless link. This enables remote control by a user outside of the vehicle. The electronic control module may remote control by a user outside o the vehicle. The electrnic control module may also be responsive to safety signals to disable operation if safety devices detect a malfunction.

Although the invention has been described in relation to vehicles incorporating two steering wheels it will be appreciated that the invention is equally applicable to a vehicle using a single steering wheel. It will also be apparent that the steering system to the invention may be implemented in a number of different manners.

Wherein the foregoing description reference has been made to integers or components having known equivalents, and such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example, it will be appreciated that improvements and/or modifications may be made thereto without departing from the scope of the invention as defined in the appended claims.

ooo S.o

S

Claims

1. A steering system for a vehicle including: an actuator to steer the wheel(s) of a vehicle; an input device having a movable control element; a control means responsive to the input device to control the actuator; and wheel position sensing means which senses the angular position of the wheel(s) and provides an indication as to the angular position of the wheel(s) to the control means, wherein the position of the movable control element indicates to a user the angular position of the wheel(s).

2. A steering system as claimed in claim 1 wherein the actuator is an hydraulic cylinder having a piston defining two chambers on either side of the piston, said piston causing rotation of the wheel(s) of a vehicle in dependence upon fluid supplied to or 15 removed from said chambers.

3. A steering system as claimed in claim 1 or claim 2 wherein the control means includes an hydraulic pump and an hydraulic valve which selectively supplies/removes hydraulic fluid to/from the chambers of the hydraulic cylinder. oooo• S•

4. A steering system as claimed in any one of the preceding claims wherein the input device includes a user actuated lever, the position of which corresponds to a o desired position of the wheel(s). eooo• 25

5. A steering system as claimed in claim 4 wherein the position sensing means includes a first cable connected between the control means and an arm which rotates with a wheel of the vehicle to indicate wheel position to the control means.

6. A steering system as claimed in claim 4 or claim 5 wherein a second cable is connected between the lever and the control means to convey desired wheel orientation controls to the control means.

7. A steering system as claimed in claim 6 wherein the hydraulic valve supplies/removes fluid to/from the chambers of said cylinder in response to movement of said lever via said second cable until the position sensing means indicates via said first cable that the wheel(s) of the vehicle are at an orientation corresponding to the degree of movement of the lever.

8. A steering system as claimed in claim 7 wherein the first and second cables are commonly connected to the hydraulic valve in such a manner that the hydraulic valve supplies/removes fluid to/from respective chambers of the cylinder until the lever and sensing means are in corresponding positions.

9. A steering system as claimed in claim 8 including a mechanical linkage having distal ends connected to the ends of the first and second cables respectively and an 15 intermediate point connected to an actuating arm of the hydraulic valve.

10. A steering system as claimed in any one of claims 1 to 4 wherein the wheel position sensing means includes an electrical sensor which supplies a signal to the control means indicative of the position of the wheel(s).

"11. A steering system as claimed in any one of claims 1 to 4 or 9 wherein the input device is an electronic input device which outputs a signal indicative of the position of a .eeo.i first portion relative to a body portion of the input device.

12. A steering system as claimed in claim 11 wherein the first portion is ajoy stick.

13. A steering system as claimed in any one of claims 10 to 12 when dependent upon claim 2 wherein the control means includes an electromechanically controlled valve responsive to the signals received from the electronic input device and position sensing means to control the supply/removal of fluid to/from the chambers to maintain a desired relationship between the signal from said sensor and the signal from said input device. -8-

14. A steering system substantially as herein described with reference to figures 1 to 3 or 4 of the accompanying drawings. DATED THIS 26' DAY OF NOVEMBER, 2001 A J& JP SMITH LTD. Attorney: STUART M. SMITH Fellow Institute of Patent Attorneys of Australia of BALD WIN SHELSTON WATERS