Electronic adjustable pedal assembly

An electronic adjustable control pedal assembly for a motor vehicle including a carrier, a guide rod adapted to be secured to the dash panel of the vehicle and mounting the carrier for fore and aft movement along the guide rod, a power drive operative to move the carrier along the guide rod, and a pedal structure including a pedal arm pivotally mounted on the carrier and a potentiometer mounted on the carrier and operative to generate an output electrical signal proportioned to the extent of pivotal movement of the pedal arm.

BACKGROUND OF THE INVENTION 
This invention relates to control pedal apparatuses and more particularly 
to adjustment means for selectively adjusting the position of one or more 
of the control pedals of a motor vehicle. 
In a conventional automotive vehicle pedals are provided for controlling 
brakes and engine throttle. If the vehicle has a manual transmission a 
clutch pedal is also provided. These pedals are foot operated by the 
driver. In order for the driver to maintain the most advantageous position 
for working these control pedals the vehicle front seat is usually 
slidably mounted on a seat track with means for securing the seat along 
the track in a plurality of adjustment positions. 
The adjustment provided by moving the seat along the seat track does not 
accommodate all vehicle operators due to differences in anatomical 
dimensions. Further, there is growing concern that the use of seat tracks, 
and especially long seat tracks, constitutes a safety hazard in that the 
seat may pull loose from the track during an accident with resultant 
injuries to the driver and/or passengers. Further, the use of seat tracks 
to adjust the seat position has the effect of positioning shorter 
operators extremely close to the steering wheel where they are susceptible 
in an accident to injury from the steering wheel or from an exploding air 
bag. It is therefore desirable to either eliminate the seat track entirely 
or shorten the seat track to an extent that it will be strong enough to 
retain the seat during an impact. Shortening or eliminating the seat track 
requires that means be provided to selectively move the various control 
pedals to accommodate various size drivers. 
Various proposals were made over a period of many years to provide 
selective adjustment of the pedal positions to accommodate various size 
drivers but none of these proposals met with any significant commercial 
acceptance since the proposed mechanisms were unduly complex and expensive 
and/or were extremely difficult to operate and/or accomplished the 
required pedal adjustment only at the expense of altering other critical 
dimensional relationships as between the driver and the various pedals. 
Recently a control pedal mechanism has been developed which is simple and 
inexpensive and easy to operate and that accomplishes the required pedal 
adjustment without altering further critical dimensional relationships as 
between the driver and the various pedals. This control pedal mechanism is 
disclosed in U.S. Pat. Nos. 4,875,385; 4,989,474 and 5,078,024 all 
assigned to the assignee of the present application. The present invention 
represents further improvements in adjustable control pedal design and 
specifically relates to an adjustable control pedal apparatus which is 
compatible with, and incorporates, a drive-by-wire arrangement in which 
the link between the pedal and the associated controlled device of the 
motor vehicle comprises an electronic signal rather than a mechanical 
linkage. 
SUMMARY OF THE INVENTION 
This invention is directed to the provision of a simple, inexpensive and 
effective apparatus for adjusting the control pedals of a motor vehicle. 
More specifically, this invention is directed to the provision of an 
adjustable control pedal apparatus that is especially suitable for use in 
conjunction with a drive-by-wire throttle control. 
The invention apparatus is adapted to be mounted on the body structure of 
the motor vehicle and includes a carrier, guide means mounting the carrier 
for fore and aft movement relative to the body structure, and drive means 
operative to move the carrier along the guide means. According to the 
invention, the pedal assembly further includes a pedal structure mounted 
on the carrier for movement relative to the carrier and means operative in 
response to movement of the pedal structure on the carrier to generate an 
electrical signal proportioned to the extent of movement of the pedal 
structure on the carrier. This arrangement provides a simple and effective 
means of generating an electronic control signal on an adjustable pedal 
assembly and ensures that the ergonomics of the control pedal will not 
vary irrespective of the position of adjustment of the pedal structure. 
According to a further feature of the invention, the pedal structure is 
pivotally mounted on the carrier and the electric signal is generated in 
response to pivotal movement of the pedal structure on the carrier. This 
specific arrangement retains the customary pivotal movement of the control 
pedal and also maintains the constant ergometric operation of the control 
pedal assembly. 
According to a further feature of the invention, the generator means 
includes a potentiometer mounted on the carrier whose setting is varied in 
response to pivotal movement of the pedal structure on the carrier. This 
specific arrangement provides a simple and effective means of generating 
the required electronic signal to provide drive-by-wire operation. 
According to a further feature of the invention, the pedal structure 
includes a pedal arm and a pedal mounted on a lower end of the pedal arm; 
the pedal assembly further includes a feedback apparatus; and the feedback 
apparatus includes a spring mounted on the carrier and arranged to exert a 
spring force against the pedal arm that varies in response to pivotal 
movement of the pedal arm, a first friction surface defined on the pedal 
arm, and a second friction surface defined on the spring and arranged for 
wiping coaction with the first friction surface in response to pivotal 
movement of the pedal arm. This specific arrangement provides a simple and 
effective means of providing the desired feel or feedback to the operator 
upon movement of the pedal and further provides the desired hysteresis 
effect. 
According to a further feature of the invention the first friction surface 
is defined by a cam surface on the pedal arm; the spring comprises a leaf 
spring fixedly secured at one end thereof to the carrier and defining a 
free end; and the second friction surface is defined on the free end of 
the leaf spring. With this arrangement, pivotal movement of the pedal arm 
generates wiping action between the cam surface and the free end of the 
spring and varies the extent of flexing of the spring about its fixed end. 
According to a further feature of the invention, the feedback apparatus 
means further includes a first resistance plate mounted on the upper 
region of the pedal arm and a second resistance plate mounted on the free 
end of the leaf spring and biased against the first resistance plate. This 
arrangement allows the resistance offered to the pivoting pedal to be 
varied either by varying the spring characteristics of the spring or by 
varying the resistance characteristics of the resistance plates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The invention control pedal assembly, broadly considered, is intended to 
allow efficient fore and aft movement of the pedal assembly to accommodate 
operators of varying anatomical dimension and is operative to generate an 
electronic or drive-by-wire signal in response to pivotal movement of the 
pedal assembly while retaining the same ergometric operation of the pedal 
irrespective of the position of adjustment of the pedal. 
The pedal assembly includes a support structure 10, a carrier assembly 12, 
a drive assembly 14, a pedal assembly 16, a resistance or feedback 
assembly 18, and a generator means 20. 
Support structure 10 may be formed as two or more parts which are suitably 
joined together or may, as shown, be formed as a single integral unitary 
member in a casting or forging operation. Structure 10 includes a bracket 
portion 10a, a transmission housing portion 10b, and a guide rod portion 
10c. 
Bracket portion 10a is adapted to be suitably secured to the dash panel 22 
of the associated motor vehicle utilizing suitable fastener means in known 
manner. 
Transmission housing portion 10b extends rearwardly from bracket portion 
10a and has a generally cubicle configuration defining a hollow 10c 
opening at the front face 10d of bracket 10a and further defining a 
central bore 10e in a rear wall 10f of the housing portion. 
Guide rod portion 10c extends rigidly rearwardly from the rear wall 10f of 
the transmission housing portion, is hollow so as to provide a tubular 
configuration defining a central circular bore 10g concentric with bore 
10e, is open at its rear end 10h, and includes an upper axial slot 10i 
extending from a location proximate the transmission housing wall 10f to a 
location proximate guide rod rear end 10h. 
Carrier assembly 12 includes a housing 24, a nut 26, and a key 28. 
Housing 24 may be formed as a casting, forging or stamping, and is designed 
to move slidably along the guide rod portion 10c of support structure 10. 
Housing 24 includes a rear wall 24a, side walls 24b and 24c, a bottom wall 
24d, a top wall 24e, and a front wall including an upper portion 24f, a 
lower portion 24g, and an angled intermediate connector portion 24h. A 
circular opening 24i is provided in rear wall 24a proximate top wall 24e 
and a circular opening 24j is provided in front wall upper portion 24f 
proximate top wall 24e in axial alignment with opening 24i. Housing 24 is 
mounted on the guide rod portion 10c of support structure 10 with guide 
rod portion 10c passing through apertures 24i and 24j and bushings 30 
positioned in apertures 24i and 24j in sliding engagement with the outer 
periphery of guide rod portion 10c so as to mount the housing for sliding 
movement along the guide rod. Angled front wall 24h is complementary to 
the angled lower surface 10j of the transmission housing portion 10b of 
support structure 10 so that the housing 24 may move into nesting relation 
with respect to the support structure with the housing in its extreme 
forward position. 
Nut 26 is circular, is mounted for sliding movement in circular bore 10g of 
support structure 10, and defines a central threaded bore 26a. 
Key 28 is seated at its lower end 28a in a notch 26b in the upper periphery 
of nut 26 and passes upwardly through slot 10i and through an opening 24k 
in top housing wall 24e for securement at its upper end 28b, by fasteners 
32, to a flange 241 upstanding from housing top wall 24e. Key 28 thus 
lockingly interconnects nut 26 and housing 24 so that movement of nut 26 
in bore 10g is imparted to housing 24 so as to move housing 24 axially 
along guide rod portion 10c. 
Drive assembly 14 includes a motor 34, a cable 36, a bracket 38, a worm 40, 
a worm gear 42, and a screw shaft 44. 
Motor 34 comprises a suitable electric motor, with position memory if 
required, and is suitably secured to dash panel 22 proximate the bracket 
portion 10a of the support structure. 
Cable 36 comprises a well-known bowden cable and is drivingly secured at 
one end 36a to the output shaft of motor 34. Bracket 38 is secured to an 
outer face of transmission housing 10b and mounts the other end 36b of 
cable 36. 
Worm 40 is suitably journalled in transmission housing 10b in overlying 
relation to cavity 10c and is drivingly connected to cable end 36b. 
Worm gear 42 is journalled in cavity 10c in meshing engagement with worm 40 
and includes a front trunion 42a journalled in a bearing 45 positioned in 
the open front end of cavity 10c and a rear trunion 42b journalled in a 
counterbore 10k in transmission rear wall 10f. 
Screw shaft 44 extends rearwardly from worm gear 42 centrally within 
support structure bore 10g and passes threadably through the threaded 
central bore 26a of nut 26. 
It will be seen that actuation of motor 34 has the effect of rotating screw 
shaft 44 to thereby move nut 26 and housing 24 fore and aft along guide 
rod 10c with the extent of forward and rearward movement defined and 
limited by engagement of key 28 with the front and rear ends of slot 10i. 
Pedal assembly 16 includes a pedal arm 46 and a pedal 48 secured to the 
lower end 46a of the pedal arm. Pedal arm 46 passes upwardly through a 
slot 24m in the lower housing wall 24d for pivotal mounting at its upper 
end 46b to housing side walls 24b and 24c via a pivot shaft 50. 
Resistance assembly 18 includes a pedal arm friction cam plate 52, a leaf 
spring 54, and a spring friction cam plate 56. Resistance assembly 18 is 
intended to provide feedback or "feel" to the operator to replace the 
feedback normally provided by the mechanical linkage interconnecting the 
pedal and the controlled device such as the fuel throttle. With a 
mechanical linkage, the pedal pressure required when advancing the 
accelerator pedal is greater than that required to maintain a fixed 
position. This difference is often referred to as due to the hysteresis 
effect. This effect is important in maintaining the accelerator pedal in 
position while driving at a relatively constant speed and it must also be 
considered in achieving a desired deceleration time. The pressure which 
must be applied in accelerating is easily borne but if the back pressure 
of an accelerator spring produced the same effect during the time it was 
required to retain or maintain speed it would soon become uncomfortable 
for the operator to maintain a relatively constant speed. The hysteresis 
effect provides relief. It lessens the load required to maintain a setting 
of the accelerator yet there is still force to cause reverse pedal action 
when the foot applied pressure is removed. Resistance assembly 18 provides 
the "feel" of a mechanical linkage including the desired hysteresis effect 
to relieve operator fatigue. 
Pedal arm friction cam plate 52 may be formed, for example, of a plastic 
material such as Delrin.RTM. and is secured to an upper cam edge 46c of 
the pedal arm via a dovetail connection 52a. 
Spring 54 comprises a laminated leaf spring and includes a curl 54a at its 
upper end wrapped around a pin 24m projecting inwardly from housing side 
wall 24b. A nub 24n projects inwardly from housing side wall 24b below pin 
24m and coacts with pin 24m to trap the end tip 54b of curl 54a to fixedly 
secure the upper end of the spring to housing side wall 24b. 
Spring friction cam plate 56 may be formed, for example, of a glass filled 
nylon material and includes a working portion 56a suitably secured to the 
lower end 54b of leaf spring 54 and a tail portion 56b passing upwardly 
between the leaves 54a, 54b of leaf spring 54. The parts are configured 
such that with the pedal 48 in its upper or rest position, as seen in FIG. 
1, friction plate working portion 56a is urged against friction plate 52 
by spring 54 so as to resist pivotal movement of the pedal assembly to an 
operative position with the resistance being constituted both by the 
increasing resistance force of the spring 54 and by the frictional 
resistance force between plates 52 and 56a generated by the wiping or 
camming action of plate 52 against plate 56a as the pedal arm pivots about 
the axis of pivot shaft 50. Upon release of pressure on the pedal, the 
frictional resistance force between plates 52 and 56a become subtractive 
rather than additive with respect to the force of spring 54, thereby 
creating the desired hysteresis effect. The materials of cam plates 52 and 
56a may be selectively varied to selectively vary the friction levels and 
hence the damping or hysteresis effect provided by the rubbing plates. 
Generator means 20 comprises a potentiometer 60 positioned within the 
hollow of housing 24 and suitably secured to housing side wall 24c. 
Potentiometer 60 includes a central shaft, constituted by the pivot shaft 
50, a housing 60a concentric with shaft 50, a plurality of resistance 
elements 60b mounted circumferentially around the inner periphery of 
housing 60a in side-by-side relation, a wiper arm 60c mounted on shaft 50 
and operative to electrically slidably engage the resistance elements 60b 
in response to pivotal movement of shaft 50, and an outlet 60d projecting 
rearwardly through opening 24p in housing rear wall 24a and electrically 
connected to wiper 60c and resistance elements 60b in a manner such that 
the electrical signal appearing at the outlet 60d varies in proportion to 
the extent of pivotal movement of the pivot shaft 50. It will be seen that 
pivotal movement of pedal 48 has the effect of rotating pivot shaft 50 and 
thereby varying the electrical signal appearing at the potentiometer 
outlet 60d so that the signal appearing at outlet 60d is at all times 
proportioned to and indicative of the pivotal position of the pedal. It 
will be understood that electric power is suitably supplied to 
potentiometer 60 and an electrical conduit 62 is suitably connected to 
potentiometer outlet 60d and extends to the vehicle function or accessory, 
such as the vehicle throttle, that is being electrically controlled by the 
pedal assembly. 
In operation, the position of the pedal 48 relative to the operator is 
selectively adjusted by selectively energizing motor 34 to selectively 
move nut 26 forwardly and rearwardly within guide rod bore 10g and 
thereby, via key 28, move the pedal assembly selectively forwardly and 
rearwardly along guide rod 10c with the limits of forward and rearward 
movement determined by engagement of the key with the respective forward 
and rearward ends of the slot 10i. In any position of adjustment of the 
pedal, actuation of the pedal or release of the pedal results, in the 
manner previously described, in the generation of an output signal at the 
outlet 60d proportioned to the extent of pivotal movement. Since the 
pivotal movement of the pedal arm is precisely the same in any position of 
adjustment of the pedal structure, the ergometrics of the assembly do not 
vary irrespective of the position of adjustment of the pedal assembly and 
irrespective of the anatomical stature of the operator. 
As the pedal is moved downwardly, a "feel" is imparted to the pedal, 
simulating the feel of a mechanical linkage between the pedal and the 
controlled vehicle system, by the combined effect of flexing of the leaf 
spring 54 and frictional sliding or wiping engagement between the friction 
plates 52 and 56a. Further, as the pedal is released or allowed to return, 
the frictional force becomes subtractive rather than additive with respect 
to the spring force, thereby creating the desired hysteresis effect. The 
amount of feel imparted to the pedal can thus be precisely adjusted by 
adjusting the spring rate or other parameters of leaf spring 54, and/or by 
adjusting the materials or other parameters of friction plates 52 and 56a, 
and/or by adjusting the rise of cam edge 46c, thereby rendering it 
relatively easy to fine tune the system to achieve any desired feel and 
any desired hysteresis effect. 
The invention will be seen to provide an electronic adjustable pedal 
assembly for a motor vehicle in which the assembly may be readily adjusted 
to accommodate operators of varying anatomical dimensions and in which the 
ergometrics of the system remain constant irrespective of the position of 
adjustment of the pedal structure. 
Whereas a preferred embodiment of the invention has been illustrated and 
described in detail, it will be apparent that various changes may be made 
in the disclosed embodiment without departing from the scope or spirit of 
the invention. For example, although the invention pedal assembly has been 
indicated for use in controlling the throttle of the associated vehicle, 
the invention pedal assembly may be used to electrically control a wide 
variety of vehicle functions or accessories. Further, although the 
resistance assembly 18 has been illustrated as providing the damping for 
an adjustable pedal assembly, it will be apparent that this resistance 
assembly can also be utilized to provide damping for a non-adjustable 
pedal assembly.