GB1602907A - Accelerator pedal assembly - Google Patents

Description

(54) ACCELERATOR PEDAL ASSEMBLY (71) We, EATON LIMITED, a British Company of Eaton House, Staines Road, Hounslow, Middlesex TW4 5DX, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to an improved accelerator linkage for motor vehicles, particularly but not exclusively for use in electrically-propelled vehicles.

Conventional accelerator linkages employ a tension spring for returning the accelerator to a vehicle-stationary or engine-idling speed when the driver lifts his foot off the accelerator pedal. Such springs may fail and, as will be appreciated, the linkage may easily stick in a higher e.g. maximum speed setting.

This is potentially dangerous both to the vehicle occupant(s), bystanders and other drivers. The present invention broadly aims to overcome this potential danger in a simple and economical fashion.

An embodiment of the invention to be described in detail was designed primarily for use in electrically-propelled vehicles such as fork-lift trucks. Such trucks are used in confined spaces and loss of control through failure of a conventional accelerator linkage could have grave effects. The preferred design can be used not only in electricallypropelled vehicles, but also in vehicles propelled by internal combustion engines. For the latter vehicles their fuel metering systems may need appropriate modification to allow the present linkage to be connected thereto.

It is believed to be well within the capability of a competent engineer to devise suitable modifications.

According to the present invention, there is provided an accelerator pedal linkage for controlling the speed of a vehicle, comprising a speed-control member which is pushed against return spring bias by a displaceable pusher element responsive to depression of the pedal for increasing vehicle speed from zero, the pusher element having a pivotal connection with the speed control member, and the return spring bias being provided by a compressed compression spring which acts along a line of action extending through the said pivotal connection and presses thereupon for returning the accelerator pedal towards a zero speed setting by pushing the pusher element in a direction counter to its direction of displacement for increasing vehicle speed for returning the speed control member towards a zero speed setting thereof the spring being mounted in or on a safety spring retainer which retains the spring in an operative, return-biasing condition in the event of a spring failure.

Should the compression spring break into two or more parts, they will be held together by the safety spring retainer. In use, the parts of the broken spring may commence to intermesh, thereby shortening the effective length of the spring. Its shortening may become more pronounced as time passes. The spring will continue to exert a restoring action on the linkage, although it has broken, so that when the driver lifts his foot off the pedal, the linkage is prevented from remaining in or adopting a high speed setting. The broken spring may not, however, return the linkage to a vehicle-stationary or engine-idling setting.

Thus, the vehicle may exhibit a tendency to creep forward (or back if left in reverse gear) or its engine may run at a higher than normal idling speed, in either case showing something is wrong with the vehicle speed control. Substantially the same effects may result should the compression spring not break but instead relax or "soften". In either event, the driver will receive an inherently safe advance warning that something needing attention is amiss with his vehicle speed control.

The safety spring retainer preferably is a rod located inside the convolutions of the spring. It could, however, be a close-fitting sleeve encompassing the spring and serving to retain the parts thereof should the spring break.

The invention will now be described by way of example only with reference to the accompanying drawing, in which: Fig. 1 shows part of an accelerator pedal assembly of the prior art, and Fig. 2 shows part of an accelerator pedal assembly embodying the present invention.

The illustrated accelerator pedal assemblies of the prior art and the present invention, 10 and 11 respectively, are both primarily intended for use in electrically-propelled vehicles. The assemblies 10, 11 operate to rotate, controllably, an actuator shaft 12, 13 of an electronic speed control, not shown.

The speed control may include a potentiometer and switching means, which may be located behind mounting plates 14, 15 of the respective assemblies, i.e. beneath the plane of the accompanying drawing. Electric speed controls of various kinds are well known, and since they are not in themselves germane to this invention, details are omitted.

In the prior assembly, an accelerator pedal 20 pivoted at a lower end (not shown) rests on a friction reducing roller 21 journalled on one end of a lever 22 pivoted at its other end to the mounting plate 14. The lever 22 pivots on a pin 23 which projects from the plate 14 beyond lever 22 to serve as a first spring anchorage. Fast with the actuator shaft 12, to swing and rotate therewith, is a second lever 24. The lever 24, which constitutes a speed control member of the assembly, extends in opposite directions to either side of shaft 12. Its end 25 further from the accelerator pedal 20 is movable between two abutments 26, 28 projecting from an up standing flange 30 carried by plate 14.

The abutments 26, 28 define mechanical limit stops for a zero speed setting and a maximum speed setting of the assembly and the electric speed control. Movement of the second lever 24 in response to actuation of the pedal 20 is gained by displacement of a pusher element or strut 31 linking the levers 22, 24. Strut 31 has its opposite ends each pivotally connected to a respective one of the levers 22 and 24. The pivot connection to lever 22 is here shown about mid-way along the length of lever 22, whereas the pivot connec tion to lever 24 is located at the end 32 thereof nearer the pedal 20. The latter pivot con nection is served by a pin 33 which serves as a second spring anchorage. A tension spring 35 is stretched between the two spring anchorages, its end loops hooking over the pins 23, 33.

In use, the vehicle fitted with accelerator pedal assembly 10 is started and accelerated from rest by pressing down on pedal 20, which causes lever 22 to swing down counter- clockwise about pin 23. This movement is communicated to control lever 24 by a push exerted thereon by the interconnecting articulated strut 31. Control lever 24 also swings counterclockwise to rotate the actuator shaft 12. The geometry of the levers is such that as lever 24 swings counterclockwise, the distance between its end 32 and pin 23 increases, so that spring 35 is extended against its bias. When the downward pressure on pedal 20 is removed, spring 35 contracts, shortening the distance between pin 23 which is fixed and pin 33 which is movable.

The contracting spring 35 causes lever 24 to rotate clockwise with shaft 12 to a zero speed setting. At the same time, movement of lever 24 is communicated via strut 31 and lever 22 to pedal 20 to restore this to a zero speed position.

If the spring 35 should age and "soften", it may be unable to restore the assembly to the zero speed setting when a driver lifts his foor off pedal 20. Should the spring break, which is most likely to occur adjacent its ends, it will be unable to restore the assembly to the zero speed setting. The assembly may remain in a high speed setting adopted thereby immediately before the driver commenced lifting his foot off the pedal, which is clearly a hazardous situation.

Alternatively, the assembly may assume a high or maximum speed setting of its own accord owing to the weights of the component parts of the assembly causing them to swing about their respective pivot mountings.

Reference is now made to Fig. 2 which shows the preferred embodiment of the invention. With the exception of reference numerals 11, 13 and 15, reference numerals used in Fig. 1 are adopted in Fig. 2 for parts of the preferred embodiment which are equivalents to parts of the prior art assembly.

The following description is confined to those areas of the preferred embodiment which differ from the prior art.

The assembly 11 has its accelerator pedal pivoted on a floor-mounting 40 and, in the vehicle at rest, the pedal 20 inclines upwardly and rests on roller 21. The lever 22 is pivoted at 42, pivot 42 in this case not serving as a spring anchorage. Displaceable pusher element or strut 31 is pivoted adjacent the roller end of lever 22 rather than adjacent the mid point thereof.

Instead of a tension return spring, assembly 11 uses a compression spring 45.

Spring 45 is supported throughout its length by a safety spring retainer formed by a support rod 46 located inside the coil of the spring. At the upper end of the rod is an abutment in the form of an inverted cup 48 which receives the top end portion of spring 46. Here, the cup, or the rod 46, is pivotally secured to pivot 49 interconnecting strut 31 and end 32 of lever 24. The spring 45 therefore acts along a line of action extending through the pivot 49, its upper end being movable with lever 24 and strut 31. The lower end of spring 45- engages a thrust washer 50 resting on a reaction plate 51 secured to mounting plate 15. The support rod 46 passes through the washer 50 and an aperture 52 in reaction plate 51, rod 46 being long enough to project downwardly of plate 51 when the assembly 11 is in a zero speed setting. The spring is already in a state of compression in the zero speed setting.

The aperture 52 is larger than the rod 46 and preferably its peripheral edge is shaped so as to present a tapered or flared lead-in from the upper and lower surfaces of plate 51. Its peripheral edge may be of rounded configuration. The arrangement is such as to allow the rod 46 freedom to rock to and fro, i.e. so that its upper end can swing to left and right as seen in the drawing.

Washer 50 could be replaced, if desired, by a cup generally similar to cup 48, the substitute having an aperture therein to pass rod 46. Cup 48 could be replaced by a washer secured to rod 46, or rod 46 could have an enlarged end forming a shoulder for the spring to abut. Abutments of other forms will doubtless readily occur to the designer.

Spring 46 is internally supported in the illustrated embodiment. It could be externally supported, however. Thus, the spring could be located inside a safety spring retainer in the form of a sleeve having one end rockably resting on plate 51, the spring having its lower end thrusting on the plate.

The upper end of the spring may abut a piston slidable in the sleeve and having an arm projecting through an axially-directed slot in the sleeve. Such an arm is secured to the pivot 49.

When the vehicle is at rest, the parts of the assembly 11 are in the solid line positions.

The vehicle is travelling at maximum speed when pedal 20 is pressed down to its dotted line position, and at intermediate speeds for intermediate settings of pedal 20. At the maximum speed setting, lever 22 has swung into an extreme counterclockwise position until its centreline is at 56. By way of strut 31, lever 24 has been caused to swing similarly until its centreline is at 57. These swinging movements are accompanied by compression of spring 45 since there is a net dimminishing in distance between cup 48 and aperture 52. Rod 46 is meanwhile rocked slightlyits top end shifting to the left in the drawing and is caused to move downwardly through aperture 52.

Upon removal of the operator's foot from pedal 20, spring 45 expands and restores the parts of the assembly to the positions shown in solid line in Fig. 2.

If the spring should break in one or more places, its broken parts will be retained on the support rod (or support sleeve) between cup 48 and fixed abutment 51, with the broken ends touching. The spring is thus still able to exert a restoring action on the assembly.

With pedal 20 released, the broken spring is able to support the pedal 20, levers 22 and 24 and strut 31 in approximately the zero speed setting. In the course of time, the broken ends may tend to mesh with one another (i.e. to become "screwed" together).

The spring will therefore shorten to some extent and may not be capable of restoring the assembly fully to and holding it exactly in the zero speed setting. The vehicle may therefore exhibit a tendency to creep forward; this action alerting the operator to a faulty speed control sufficiently early to avoid disastrous consequences. A similar effect may be produced if the spring commences to fail by going soft rather than actually breaking.

It will be recognised that the assembly 11 could be used to advantage in vehicles fitted with internal combustion engines, as aforesaid, in order to obtain the same advantages. Lever 24 or shaft 13 would be appropriately coupled to the actuating component at the fuel metering system.

It will further be recognized that the mechanical advantage of the linkage system can be varied by varying the pivot point positions and hence by varying the resulting lever arms.

Rather than use a cup to serve as a spring abutment, i.e. as cup 48 described above, a simple L-shaped or right-angled plate may be preferred. Such a plate will have one limb secured to the pivotal connection 49 between lever 24 and strut 31. The spring 45 will have its upper end abutting the other, upstanding limb; this limb may be viewed as extending upwardly from the plane of Fig. 2.

Rod 46 is suitably secured to the plate e.g.

by welding or brazing.

WHAT WE CLAIM IS: 1. An accelerator pedal linkage for controlling the speed of a vehicle, comprising a speed control member which is pushed against return spring bias by a displaceable pusher element responsive to depression of the pedal for increasing vehicle speed from zero, the pusher element having a pivotal connection with the speed control member, and the return spring bias being provided by a compressed compression spring which acts along a line of action extending through the said pivotal connection and presses thereupon for returning the acceleration pedal towards a zero speed setting by pushing the pusher element in a direction counter to its direction of displacement for increasing vehicle speed and for returning the speed control member towards a zero speed setting thereof, the spring being mounted in or on a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (13)

**WARNING** start of CLMS field may overlap end of DESC **. through the pivot 49, its upper end being movable with lever 24 and strut 31. The lower end of spring 45- engages a thrust washer 50 resting on a reaction plate 51 secured to mounting plate 15. The support rod 46 passes through the washer 50 and an aperture 52 in reaction plate 51, rod 46 being long enough to project downwardly of plate 51 when the assembly 11 is in a zero speed setting. The spring is already in a state of compression in the zero speed setting. The aperture 52 is larger than the rod 46 and preferably its peripheral edge is shaped so as to present a tapered or flared lead-in from the upper and lower surfaces of plate 51. Its peripheral edge may be of rounded configuration. The arrangement is such as to allow the rod 46 freedom to rock to and fro, i.e. so that its upper end can swing to left and right as seen in the drawing. Washer 50 could be replaced, if desired, by a cup generally similar to cup 48, the substitute having an aperture therein to pass rod 46. Cup 48 could be replaced by a washer secured to rod 46, or rod 46 could have an enlarged end forming a shoulder for the spring to abut. Abutments of other forms will doubtless readily occur to the designer. Spring 46 is internally supported in the illustrated embodiment. It could be externally supported, however. Thus, the spring could be located inside a safety spring retainer in the form of a sleeve having one end rockably resting on plate 51, the spring having its lower end thrusting on the plate. The upper end of the spring may abut a piston slidable in the sleeve and having an arm projecting through an axially-directed slot in the sleeve. Such an arm is secured to the pivot 49. When the vehicle is at rest, the parts of the assembly 11 are in the solid line positions. The vehicle is travelling at maximum speed when pedal 20 is pressed down to its dotted line position, and at intermediate speeds for intermediate settings of pedal 20. At the maximum speed setting, lever 22 has swung into an extreme counterclockwise position until its centreline is at 56. By way of strut 31, lever 24 has been caused to swing similarly until its centreline is at 57. These swinging movements are accompanied by compression of spring 45 since there is a net dimminishing in distance between cup 48 and aperture 52. Rod 46 is meanwhile rocked slightlyits top end shifting to the left in the drawing and is caused to move downwardly through aperture 52. Upon removal of the operator's foot from pedal 20, spring 45 expands and restores the parts of the assembly to the positions shown in solid line in Fig. 2. If the spring should break in one or more places, its broken parts will be retained on the support rod (or support sleeve) between cup 48 and fixed abutment 51, with the broken ends touching. The spring is thus still able to exert a restoring action on the assembly. With pedal 20 released, the broken spring is able to support the pedal 20, levers 22 and 24 and strut 31 in approximately the zero speed setting. In the course of time, the broken ends may tend to mesh with one another (i.e. to become "screwed" together). The spring will therefore shorten to some extent and may not be capable of restoring the assembly fully to and holding it exactly in the zero speed setting. The vehicle may therefore exhibit a tendency to creep forward; this action alerting the operator to a faulty speed control sufficiently early to avoid disastrous consequences. A similar effect may be produced if the spring commences to fail by going soft rather than actually breaking. It will be recognised that the assembly 11 could be used to advantage in vehicles fitted with internal combustion engines, as aforesaid, in order to obtain the same advantages. Lever 24 or shaft 13 would be appropriately coupled to the actuating component at the fuel metering system. It will further be recognized that the mechanical advantage of the linkage system can be varied by varying the pivot point positions and hence by varying the resulting lever arms. Rather than use a cup to serve as a spring abutment, i.e. as cup 48 described above, a simple L-shaped or right-angled plate may be preferred. Such a plate will have one limb secured to the pivotal connection 49 between lever 24 and strut 31. The spring 45 will have its upper end abutting the other, upstanding limb; this limb may be viewed as extending upwardly from the plane of Fig. 2. Rod 46 is suitably secured to the plate e.g. by welding or brazing. WHAT WE CLAIM IS:

1. An accelerator pedal linkage for controlling the speed of a vehicle, comprising a speed control member which is pushed against return spring bias by a displaceable pusher element responsive to depression of the pedal for increasing vehicle speed from zero, the pusher element having a pivotal connection with the speed control member, and the return spring bias being provided by a compressed compression spring which acts along a line of action extending through the said pivotal connection and presses thereupon for returning the acceleration pedal towards a zero speed setting by pushing the pusher element in a direction counter to its direction of displacement for increasing vehicle speed and for returning the speed control member towards a zero speed setting thereof, the spring being mounted in or on a

safety spring retainer which retains the spring in an operative, return-biasing condition in the event of a spring failure.

2. A linkage according to claim 1, wherein the safety spring retainer is arranged to retain the spring, after it has failed by breaking into one or more parts, with its broken ends in contact with one another.

3. A linkage according to claim 2, wherein the safety spring retainer is pivotally secured to the pivotal connection at the end of the spring remote from a fixed abutment upon which the spring bears.

4. A linkage according to claim 3, wherein the safety spring retainer comprises a rod on which the spring is mounted, the rod extending through the length of the spring, and the rod passing freely through an aperture in the fixed abutment and being movable in response to movements of the speed control member and the pusher element.

5. A linkage according to claim 4, wherein the spring has its end remote from the fixed abutment in engagement with an abutment at the end of said rod, the abutment being pivotally secured to the pivotal connection.

6. A linkage according to claim 5, wherein the abutment at the end of said rod comprises a cup into which the said spring end extends.

7. A linkage according to claim 4, 5 or 6, wherein the speed control member is a lever fast with a rotary actuating shaft of a speed control device so as to rotate with the shaft, the pivotal connection being located at a point on the lever remote from the shaft, and the said rod being received by the said aperture with freedom to rock to and fro in response to swinging movements of the lever.

8. A linkage according to any preceding claim, wherein the accelerator pedal rests on a pivoted lever and the pusher element is pivotally connected at one end to this lever and at its other end to the speed control member.

9. A linkage according to claim 8, wherein the said pivoted lever has a freerunning roller on which the accelerator pedal rests.

10. A linkage according to any of claims 1 to 9, which has a mounting carrying the speed control member, the mounting having stopping surfaces engageable by the said member when in zero and maximum speed settings.

11. An accelerator pedal linkage substantially as hereinbefore described with reference to and as shown in Fig. 2 of the accompanying drawing.

12. A vehicle fitted with an accelerator pedal linkage as claimed in any of claims I to 11.

13. A vehicle according to claim 12, which is electrically propelled and which has the speed control member fast with the shaft of a speed-controlling potentiometer.