[19]
`United States Patent
`5,415,144
`[11] Patent Number:
`
`Hardin et al.
`[45] Date of Patent: May 16, 1995
`
`US005415144A
`
`[54] THROTTLE POSITION VALIDATION
`METHOD AND APPARATUS
`_
`Inventors: George T. Hardin; James A. Keller;
`Earl C. Pearson, all of Knoxville,
`Tenn.
`
`[75]
`
`[73] Assignee: Robertshaw Controls Company,
`Richmond, Va.
`[21] Appl. No.: 182,625
`.
`[22] Flled!
`Jan. 14, 1994
`
`E21
`Ijnts. C(lfi6 ................................................ Foigszg
`. .............................................
`.
`.
`[58] Field of Search ............... 123/399, 478, 493, 494,
`123/397, 361, 339; 180/197, 335; 338/153, 172,
`174, 200; 333/184; 73/1181, 513; 364/431.05
`References Cited
`
`[56]
`
`U'S' PATENT DOCUMENTS
`2,l92,714 3/1940 Norman et a1. ..................... 123/399
`3,837,321 9/1974 Sauer ................
`123/399
`123/399
`3,858,561
`1/1975 Aono
`123/399
`3,911,872 10/1975 Hughes .
`123/399
`3,926,153 12/1975 Reddy ..........
`.. 123/399
`4,133,320
`1/1979 Bianchi et al.
`.
`4,305,359 12/1981 Mann et al. ......
`123/333
`
`4,308,838
`1/1982 Nakano et a1.
`123/492
`
`4,355,293 10/1982 Driscoll ................
`333/184
`
`4,528,590 7/1985 Bisacquino et a1
`338/153
`8/1985 Steinbrenner ........
`4,532,908
`123/493
`
`4,603,675
`8/1986 Junginger et al.
`123/478
`
`.....
`4,653,453 3/1987 Kamai et a1.
`123/444
`
`.. 73/118.1
`4,703,649 11/1987 Eitokuet a1.
`......
`4,703,823 11/1987 Yogo et a1.
`180/197
`
`4,706,062 11/1987 M‘annle et a1.
`338/172
`.. 123/494
`4,722,313 2/1988 Kohler et al.
`
`4,883,037 11/1989 Mabee et a1.
`.
`123/399
`
`4,915,075 4/1990 Brown ..........
`123/399
`
`6/1990 Oda et al. .
`4,933,661
`338/174
`4,944,269 7/1990 Imoehl ................................ 123/399
`
`4,958,607 9/1990 Lundberg ............................ 123/399
`4,983,946
`1/ 1991 Kotaki et al.
`.. 338/200
`5,133,321
`7/1992 Hering et al.
`123/399
`5,307,776 5/1994 Unuvar et al.
`123/399
`5,327,865 7/1994 Reihemann .......
`.. 123/397
`5,339,782
`8/1994 Golzer et a1.
`....................... 123/399
`
`
`
`.....
`
`OTHER PUBLICATIONS
`H. Collona, “VDO ‘Electric Accerlerator’ Remote
`Control”, distributed at the Second Int’l Conference on
`Automotive Electronics, London, England held Oct.
`29—NOV. 2, 1979.
`Primary Examiner—Raymond A.Ne11i
`It
`,
`’
`- _w ,
`ff
`, F 11 &
`1:141:12? Agent 0’ an ms H° mam ‘5 er
`
`ABSTRACT
`[57]
`An engine control system is disclosed having a unit for
`providing signals indicative of the position of an engine
`throttle member. The unit comprises a housing assem-
`bly associated with an engine throttle member and con—
`taining a stator assembly and a rotor assembly. The
`rotor assembly moves relative to the stator assembly as
`the throttle member moves. The rotor and stator assem-
`blies are electrically coupled together for producing
`first and second continuously variable, ratiometrically
`identical signals whose values depend upon the throttle
`member position. The first signal is delivered from the
`housing assembly for use in controlling the engine oper-
`ation. Processing circuitry processes the second signal
`for producing a throttle position validation signal hav-
`ing a first value when the throttle member is in an en-
`gine idle range of positions and a second value when the
`throttle member moves beyond the idle range of posi-
`tions. If the first signal and the validation signal signify»
`incompatible throttle member positions the engine
`speed is limited to “idle.”
`
`12 Claims, 11 Drawing Sheets
`
`
`
`VW EX1013
`
`US. Patent No. 6,588,260
`
`VW EX1013
`U.S. Patent No. 6,588,260
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 1 of 11
`
`_ 5,415,144
`
`Fig.1
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 2 of 11
`
`5,415,144
`
`
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 3 of 11
`
`5,415,144
`
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`

`US. Patent 4
`
`May 16, 1995
`
`Sheet 4 of 11
`
`5,415,144
`
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`

`US. Patent
`
`May. 16, 1995
`
`Sheet 5 of 11
`
`5,415,144
`
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`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 6 of 11
`
`5,415,144
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`
`
`112
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 7 of 11
`
`5,415,144
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`
`
`
`
`
`
`
`
`
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 8 of 11
`
`.
`
`5,415,144
`
`
`Fig.7B
`
`210
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 9 of 11
`
`5,415,144
`
`262
`
`
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 10 of 11
`
`5,415,144
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`+VCC
`320
`
`..................................................
`
`
`
`E
`
`ml0m
`
`I
`
`Qou
`
`POSITION
`SIGNAL
`OUTPUT ‘
`329
`
`(SIG 1)
`Fig.12A
`
`
`
`I... IDLE
`RANGE
`
`MIN. THROTTLE
`POSITION
`
`THROTTLE
`RANGE
`
`‘
`
`FULL THROTTLE
`POSITION
`
`IDLE
`VALIDATION
`SIGNAL
`OUTPUT
`374
`
`(SIG 2)
`
`LOGIC HIGH
`
`'
`
`FIQJZB I"_RANGE
`
`IDLE
`
`THRO‘ITLE
`
`RANGE
`
`IDLE
`VALIDATION
`SIGNAL
`OUTPUT
`376
`
`(SIG 3)
`
`
`
`LOGIC HIGH
`
`
`
`
`
`LOGIC LOW
`
`

`

`US. Patent
`
`May 16, 1995
`
`Sheet 11 of 11
`
`5,415,144
`
`
`
`omN
`
`09.
`
`
`
`omN
`
`

`

`1
`
`5,415,144
`
`THROTTLE POSITION VALIDATION METHOD
`AND APPARATUS
`
`FIELD OF THE INVENTION
`
`The present invention concerns a throttle pedal posi-
`tion sensor for a motor vehicle and, more particularly, a
`throttle pedal position sensor that provides complemen-
`tary signals for validating throttle positioning.
`BACKGROUND ART
`
`In prior art motor vehicle designs, engine setting has
`been achieved by a mechanical linkage between a throt-
`tle control element, such as a foot pedal, and a butterfly
`valve which Opens and closes to adjust the amount of
`combustion air entering the engine intake manifold.
`With the increasing use of fuel injection, many vehicles
`employ electronic controls to adjust the amount of fuel
`reaching the engine combustion chambers. Proposals
`have been made to directly convert throttle pedal posi-
`tion to an electric signal which controls fuel injection.
`Such vehicles may not employ any direct mechanical
`linkage between the throttle pedal and the engine. In-
`stead, the fuel flowing to the engine is controlled by an
`electric signal whose value varies according to throttle
`pedal position. In case of a failure in the electronics
`resulting in false output signals,
`the vehicle engine
`speed could become uncontrollable by the operator.
`In order to assure safe operation of such vehicles,
`engine idle validation devices have been employed.
`When the engine throttle pedal is in its “engine idle”
`position (e.g. when an operator’s foot is off the pedal),
`an output signal is produced signifying that the pedal is
`not depressed. When the pedal is depressed beyond a
`predetermined “idle” position,
`the validation device
`signals that the pedal is away from the idle position.
`Engine operation in response to the pedal position is
`then enabled.
`Idle validation devices have sometimes taken the
`form of mechanical on-off type switches actuated by the
`throttle pedal separately from the throttle position sig-
`nal generator. The mechanical switches had to be in-
`stalled and calibrated so that they accurately signalled
`the pedal position. In use, these switches were subject to
`mechanical forces which shifted them relative to the
`pedal and to the pedal position signal generator. Besides
`requiring recalibration, shifting switch settings relative
`to the pedal position signal generators could disable the
`vehicle. Moreover, the mechanical switches exhibited
`fixed relatively wide hysteresis which was undesirable.
`An example of a prior art proposal of an idle validation
`device for use with an electronic fuel injection control,
`is disclosed in US. Pat. No. 5,133,321 to Hering et al.
`The Hering et al. patent provided an idle verification
`device which was fixed in a housing with a pedal posi-
`tion signal generator so that calibration settings could
`not drift relative to each other. The idle verification
`switch was provided by a deposited resistance material
`similar to the deposited material used to form the signal
`generator. The deposited material forming the idle veri-
`fication switch was interrupted so that when the pedal
`was in its idle position one section of the material was
`engaged by a conductive wiper arm to signal the pedal
`position at idle. The other section of the material was
`engaged to signal the pedal position away from idle.
`This approach required that the resistance material
`sections be spaced apart, creating a “dead band” in
`which the conductive wiper arm engaged neither sec-
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`2
`tion of the deposited material. No output of any sort
`was available from the verification switch in the dead
`band, which is undesirable. The dead band simulated
`hysteresis so that the pedal position could be varied
`somewhat without generating frequent
`incompatible
`verification signals.
`The present invention provides a new and improved
`throttle pedal position signalling unit. Wherein indepen-
`dently derived signals both indicate pedal position and
`validate the pedal position without requiring calibration
`or periodic adjustments for recalibration.
`DISCLOSURE OF THE INVENTION
`
`An engine control system is disclosed having a unit
`for providing signals indicative of the position of an
`engine throttle member. The unit comprises a housing
`assembly associated with an engine throttle member and
`defining a chamber for a rotor assembly and a rotor
`assembly. The stator assembly is fixed against move-
`ment with respect to the housing and the stator assem-
`bly is connected to the throttle member for movement
`relative to the stator assembly in relation to throttle
`movement. The rotor and stator assemblies are electri-
`
`cally coupled together for producing first and second
`continuously variable, ratiometrically identical signals
`whose values depend upon the throttle member posi-
`tion. The first signal is delivered from the housing as-
`sembly for use in controlling the engine operation. Pro-
`cessing circuitry processes the second signal for pro-
`ducing a throttle position validation signal having a first
`value when the throttle member is in an engine idle
`range of positions. The processing circuitry produces a
`validation signal having a second value when the throt-
`tle member moves beyond the idle range of positions. If
`the first signal and the validation signal signify incom-
`patible throttle member positions the engine speed is
`limited to “idle.”
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side elevation View of a vehicle throttle
`pedal assembly embodying the present invention at-
`tached thereto;
`FIG. 2 is a perspective view of the assembly of FIG.
`1 with parts removed;
`FIG. 3 is a cross sectional view of a pedal position
`signal generating unit forming part of the assembly of
`FIGS. 1 and 2;
`FIG. 4A is an elevation View of a housing forming
`part of the unit of FIG. 3;
`FIG. 4B is a view seen approximately from the plane
`indicated by the line 4B—4B of FIG. 4C;
`FIG. 4C is a view seen approximately from the plane
`indicated by the line 4C—4C of FIG. 4A;
`FIG. 4D is a view seen approximately from the plane
`indicated by the line 4D—4D of FIG. 4A;
`FIG. 5A is a top plan View of a rotor component of
`FIG. 3;
`FIG. 5B is a bottom view of the rotor component of
`FIG. 5A;
`FIG. 6A is a cross-sectional view of a stator member
`illustrated in FIG. 3 and shown on a smaller scale;
`FIG. 6B is a view seen approximately from the plane
`indicated by the line 6B—6B of FIG. 6A;
`FIG. 6C is a view. seen approximately from the plane
`indicated by the line 6C—6C of FIG. 6A;
`FIG. 7A is an elevational view of a film member
`having deposited resistance material tracks thereon;
`
`

`

`3
`FIG. 7B is a view similar to FIG. 7A wherein the
`deposited materials are removed and printed electrical
`circuit elements exposed;
`FIG. 8 is an exploded perspective view of the printed
`circuit film member of FIG. 7 and the stator member of 5
`FIG. 6;
`FIG. 9 is a schematic diagram of circuitry for gener-
`ating throttle pedal position signals and complementary
`position validation signals constructed according to the
`invention;
`FIG. 10 is a schematic diagram of a circuit for gener-
`ating complementary pedal position validation signals;
`FIG. 11 is a schematic diagram of a portion of an
`alternate circuit for generating complementary pedal
`position validation signals; and
`FIGS. 12A-12C are plots of signals produced by the
`circuitry of FIGS. 10 and 11.
`
`10
`
`15
`
`BEST MODE FOR PRACTICING THE
`INVENTION
`
`20
`
`25
`
`30
`
`35
`
`FIGS. 1 and 2 of the drawings illustrate a position
`signalling throttle pedal assembly 10 embodying the
`present invention which is constructed for use in con-
`trolling automotive vehicle engines. The assembly 10
`comprises a throttle pedal unit 12 actuated by a vehicle
`operator to control the engine, a pedal position signal
`generating unit 14 (FIG. 1) producing electric signals
`indicative of pedal position, a signal cable 16 for trans-
`mitting the signals to an engine controller (not illus-
`trated), and a linkage 18 for actuating the signal genera-
`tor 14 in response to pedal positioning.
`The assembly 10 is constructed to simulate the opera-
`tion of a throttle controlling pedal which is mechani-
`cally linked to the engine. Thus when the operator’s
`foot is off the pedal (as illustrated in FIG. 1) the engine
`“idles.” As the pedal is depressed, a continuously vari-
`able throttle position signal is produced by the unit 14
`and transmitted to the engine controller so that progres-
`sively more fuel and air are supplied to the engine.
`Because there is no mechanical linkage between the
`operator and the engine, it is important to insure against
`a malfunction of some sort creating spurious electrical
`signals which cause the engine to operate out of control.
`The new assembly 10 also produces throttle position
`validation signals which are also transmitted to the
`engine controller.
`FIGS. 1 and 2 illustrate the pedal unit 12 as compris-
`ing a pedal 20, a pedal supporting base plate 22 and a
`hinge assembly 23 connecting the pedal to the base
`plate. The base plate 22 is formed of heavy gage sheet
`metal and secured to the vehicle operator’s compart-
`ment floor by suitable connectors (not illustrated). The
`pedal 20'coacts with the hinge assembly and base plate
`to simulate a conventional pedal mechanically linked to
`a carburetor or fuel injection system. The pedal is sche-
`matically illustrated as constructed from heavy gage
`sheet metal and may have a rubber-like tread member
`(not shown) bonded to its upper side for traction and
`wear resistance. The lower, pedal base end is coupled to
`the base plate 22 by the hinge assembly 23 so that the
`upper pedal tip end moves toward and away from the
`base plate through an arc.
`The hinge assembly 23 secures the pedal to the base
`plate and locates the pedal in its “engine idle” position
`when the operator’s foot is either off the pedal or exert- 65
`ing less than a predetermined force. The hinge assembly
`23 comprises a hinge pin 24, pin receiving pillow blocks
`26, 28 formed on the pedal and base plate, respectively,
`
`45
`
`50
`
`55
`
`60
`
`5,415,144
`
`4
`and a pedal return spring 29 (FIG. 2). The pillow blocks
`comprise ear-like projections in which aligned bearings
`are fixed. The bearings receive the pin 24 to assure a
`stable, wear resistant, low friction interconnection be-
`tween the pedal and base plate.
`The return spring 29 reacts between the pedal and the
`base plate to strongly resist depression of the pedal by
`the operator and to return the pedal to its idle position
`when the operator’s foot is relaxed or removed from the
`pedal. The preferred spring 29 is a helical torsion spring
`surrounding the pin 24. Opposite spring ends react be-
`tween the pedal and base plate, respectively, to bias the
`pedal.
`The linkage 18 reacts between the pedal 20 and the
`base plate 22 to condition the signal generating unit 14
`for signalling the exact pedal position relative to the
`base plate. The linkage 18 comprises a lever assembly 30
`extending between the pedal and the base plate, a pivot
`unit 31 connecting the lever assembly to the pedal, a
`cam mechanism 32 for positioning the lever assembly
`relative to the pedal and a return spring 33 biasing the
`lever assembly 30 to its engine idle position.
`As can best be seen in FIG. 2 the pivot unit 31 com-
`prises a flange 34 and lug 36 extending from the pedal 20
`and containing bearings (not illustrated) and a pivot
`shaft 42 mounted in the bearings for rotation relative to
`the pedal. The flange 34 carries the signal generating
`unit 14 on its front face 48 and includes tapped mount-
`ing holes 44 and a circular locating recess 46 on the
`front face 48. The holes 44 and recess 46 assure accurate
`alignment of the signal generating unit 14 with the pedal
`20.
`
`The shaft 42 transmits motion from the linkage 18 to
`the signal generating unit 14. The shaft 42 is mounted
`for low friction rotation in the aligned flange and lug
`bearings and is fixed to the lever assembly 30. Thus the
`shaft 42 rotates relative to the flange 34 about an axis 49
`when the pedal moves relative to the base plate. The
`shaft 42 is preferably cylindrical with a tang 50 at one
`end projecting outwardly beyond the flange face 48 for
`engagement with the signal generating unit 14.
`The lever assembly 30 drives the shaft 42 for actuat—
`ing the signal generating unit 14. The lever assembly 30
`extends between the shaft 42 and the cam mechanism 32
`so that as the pedal 20 moves, the cam mechanism 32
`and lever assembly 30 control the degree of shaft rota-
`tion. The lever assembly 32 comprises a pair of lever
`members 52 fixed to the shaft 42 and projecting to the
`cam mechanism 32 at the base plate, a cross member 56
`fixed between the lever members and spaced from the
`shaft, and a return spring 60 (FIG. 2) for biasing the
`lever members towards their “engine idle” position.
`The lever members 52 are fixed to the shaft 42 (for
`example by keys and keyways) at axially spaced loca-
`tions adjacent the respective confronting sides of the
`flange 34 and lug 36. The lever members 52 extend
`parallel to each other toward the cam mechanism with
`the cross member 56 fixed between them for support.
`The return spring 60 (schematically shown) is a helical
`torsion spring encircling the shaft 42 with its opposite
`ends 62 resiliently engaging and reacting between the
`pedal 20 and the cross member 56. The spring 60 is
`coiled to strongly urge the lever members 52 clockwise
`about the shaft 42 axis 49 (as seen in FIGS. 1 and 2)
`toward the lever assembly “engine idle” position.
`The cam mechanism 32 governs the degree of shaft
`(42) rotation created by a given pedal movement. The
`mechanism 32 comprises a cam ramp 63 on the base
`
`

`

`5,415,144
`
`5
`plate 22 and a roller follower 64 carried by the lever
`assembly 30. The cam ramp 63 is illustrated as formed
`by an upturned base plate end 65 having an embossed
`cam track 66 extending along its length. The cam fol-
`lower 64 is formed by a cylindrical roller extending
`between the lever member ends remote from the shaft
`42 and a roller axle 67. The axle 67 is fixed between the
`lever member ends and carries the roller which is freely
`rotatable on the axle. The illustrated roller follower 64
`provides a wide cylindrical cam following surface
`which is matched by the wide flat embossed cam track
`surface on the base plate end 65. The illustrated cam
`track is formed by a straight, angled ramp on the base
`plate, but other ramp configurations can be employed to
`produce shaft rotations varying as desired functions of
`pedal displacement.
`When the pedal 20 is in its “engine idle” position, the
`roller follower 64 is at an initial position on the cam
`ramp 63 which is illustrated by FIGS. 1 and 2. As the
`vehicle operator depresses the pedal 20 both the pedal
`20 and the lever members 52 rotate. The pedal 20 ro-
`tates in opposition to the spring 29 (clockwise as viewed
`in FIG. 1) and the lever members 52 rotate in opposition
`to the spring 60 (counterclockwise as viewed in FIG. 1).
`The roller follower moves along the cam ramp in a
`direction “M” (see FIG. 1) and the levers 52 rotate the
`shaft 42 in the direction of the arrow “R.”
`When the pedal pressure is relieved, the return spring
`60 urges the lever members back toward their initial
`“engine idle” positions, while the spring 29 returns the
`pedal to its “engine idle” position. The shaft 42 then
`turns in the direction opposite to the direction of the
`arrow “R” (FIG. 1).
`The signal generating unit 14 of the present invention
`is carried by the pedal 20 for providing electric pedal
`position responsive signals to control the engine. The
`unit 14 (FIGS. 1 and 3) comprises a housing assembly
`70, a signal handling stator assembly 71 anchored in the
`housing, and a rotor assembly 72 movably supported in
`the housing and coacting with the stator assembly 71 for
`generating pedal position responsive signals. The rotor
`and stator assemblies are disposed in a sealed chamber
`defined by the housing assembly. The housing assembly
`70 is secured to the pedal 20 with the rotor assembly 72
`connected to and driven by the shaft 42 for rotation
`relative to the stator assembly 71. Position signals are
`generated as the rotor assembly moves relative to the
`stator assembly. In the preferred construction the hous-
`ing assembly is clamped to the pedal by screws 73 (FIG.
`1 ) extending through openings in the housing assembly
`which are aligned with the tapped mounting flange
`holes 44.
`
`Referring to FIGS. 3 and 4A—C, the housing assem-
`bly 70 comprises a cup-like housing member 74 receiv-
`ing the stator and rotor assemblies, a cover member 76
`for the housing member, a terminal connector arrange-
`ment 78 and an assembly spring member 80 associated
`with the cover member for maintaining the stator as-
`sembly in position.
`The housing member 74 is a relatively high strength,
`electric insulator molded from plastic or plastic—like
`material (for example Valox 420). The member 74 forms
`a cavity 82 defined by a base wall 84 and a surrounding
`side wall 86. The rotor and stator assemblies are re-
`ceived in the cavity 82 and are accurately positioned
`with respect to each.
`The base wall 84 supports the rotor assembly 72 in a
`rotor assembly supporting boss structure 92. The boss
`
`6
`structure defines a bore 90 aligned with the shaft axis 49
`for accurately positioning and securing the rotor assem-
`bly radially with respect to the shaft axis. Arcuately
`curved bearing lands 94 are formed in the base wall 84
`adjacent the boss structure 92 for engaging and locating
`the rotor assembly relative to the shaft axis. The lands
`94 project slightly from the wall 84 towards the rotor
`and define narrow, low friction bearing faces engaged
`with the rotor assembly.
`The stator assembly 71 is fixed against movement
`both axially and radially relative to the housing assem-
`bly. The side wall 86 defines a seat forming shoulder 96
`extending partially about the irregularly shaped cavity
`(82) perimeter at a given distance from the base wall
`bearing land faces. The stator assembly 71 firmly seats
`on the shoulder 96 to fix the axial location of the stator
`assembly in the housing assembly. The stator assembly
`perimeter shape conforms to the shape of the cavity
`perimeter and shoulder 96 so that the stator assembly is
`fixed against any radial or circumferential motion rela-
`tive to the housing member when seated on the shoul-
`der 96.
`
`The cover member 76 (FIG. 3) both closes the cavity
`82 and resiliently clamps the assembly spring member
`80 against the stator assembly. The cover member 76 is
`a flat plate-like member hermetically secured to the
`housing member 74 at the cavity end remote from the
`base wall 84 to close the housing assembly chamber. As
`shown by FIG. 3 the housing side wall 86 defines a
`cover member seating shoulder 98 disposed a fixed
`distance from the shoulder 96 near the cavity open end.
`The cover member 76 is bonded to the shoulder 98 (for
`example by ultrasonic welding) when the housing as-
`sembly is complete. The shoulder perimeter conforms
`to the cavity perimeter shape and to the perimetral
`cover member (76) shape to assure a complete and her—
`metic bond.
`The illustrated spring member 80 is formed by a pad
`of foam plastic or rubber-like material compressed be-
`tween the cover member and the stator assembly 71.
`The spring member periphery conforms generally to
`the cavity shape and thus overlies the stator assembly.
`The uncompressed pad thickness is appreciably greater
`than the distance between the cover member and the
`stator assembly so that the pad resiliently maintains
`contact with the stator assembly. In addition to its
`spring function the foam construction cushions the
`housing assembly against road shocks. Other forms of
`assembly spring can be employed.
`The terminal connector arrangement 78 detachably
`couples the signal cable 16 to pedal position signal cir-
`cuitry of the stator assembly. In a preferred embodi-
`ment of the invention the cable 16 plugs into the signal
`generating unit 14. The illustrated terminal connector
`arrangement 78 (FIGS. 3 and 4A—C) comprises a female
`socket formation 100 continuous with and projecting
`from an external face of the side wall 86, a series of
`terminal pins 102a—fhermetically fixed in and extending
`through the side wall 86 into the cavity 82 for electrical
`engagement with respective stator assembly circuit
`elements, and guide structure 104 along the internal face
`of the side wall 86 for assuring proper alignment be-
`tween the terminal pins and the stator assembly.
`The socket formation 100 extends about the terminal
`pins 102 and the mating male end of the cable 16 to
`shield their juncture. A guide slot 106 integral with the
`socket formation 100 interfits with a key formed on the
`cable plug (not illustrated) to assure the terminal pins
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`5,415,144
`
`7
`are properly aligned with the cable plug. Each terminal
`pin 102 is press fit into a respective conforming pre-
`formed side wall (86) hole. Terminal pin ends project
`through the wall 86 into the cavity 82 for making good
`electrical contact with stator assembly circuit elements
`when the housing assembly has‘been completed.
`is
`The rotor assembly 72 (See FIGS. 3 and 5)
`mounted for rotation about the axis 49 between the boss
`structure 92 and the stator assembly 71 and coacts with
`the stator assembly to create electrical signals indicative
`of throttle pedal position. The rotor assembly 72 com-
`prises a molded rotor body 110, position signal transmit-
`ting circuit elements 112, 114, coupled to the stator
`assembly, a shaft seal 116, and a return spring system
`118.
`
`The rotor body 110 carries the position signal trans-
`mitting circuit elements 112, 114 and rotates with the
`shaft to move the position signal transmitting elements
`relative to the stator assembly circuitry for producing
`the position signals. The rotor body comprises a disc-
`like rotor member 120, supporting trunnions 122, 124
`projecting from opposite faces of the member 120 along
`the axis 49, bearing flanges 126 depending from the
`rotor member outer periphery for engagement with the
`bearing lands 94, and rotor body travel limiting stop
`elements 128 (See FIG. 5A).
`The rotor member 120 is a relatively thin, planar
`member centered on the axis 49 and defining a pair of
`generally cylindrically curved outer peripheral sections
`130 each having a wing-like projection 132 extending
`tangentially away from one end. The position signal
`transmitting elements 112, 114 are molded into respec-
`tive projections 132. Each bearing flange 126 projects
`from a respective cylindrical rotor body periphery and
`defines a relatively narrow bearing face engagable with
`a bearing land 94. A generally circular channel is de-
`fined between the trunnion 124 and the bearing flanges
`126 into which a cylindrical housing member boss ele-
`ment 133 surrounding the bore 90 extends (See FIGS. 3
`and 4).
`The trunnions 122, 124 are aligned on the axis 49 and
`support the rotor assembly for rotation about the axis
`49. The trunnions are respectively received and sup-
`ported for rotation in the housing member wall bore 90
`and in a stator assembly bearing socket 134 (FIG. 3).
`The shaft seal 116 is a conventional resilient ring seal
`seated on a shoulder within the boss element 133 and
`having faces sealingly engaging the trunnion 122, the
`rotor member 120 and the shoulder so that the housing
`chamber is sealed against the ingress of moisture, dust,
`etc. along the trunnion 122. The end of the trunnion 122
`projecting from the bore 90 is shaped to provide two
`parallel blade-like tangs 140 which receive the shaft
`tang 50 between them. The shaft 42 positively drives
`the rotor in both directions of rotation because of the
`relationship between the tangs. Planar semicircular
`shoulders 142 remain radially outwardly of the tangs
`140.
`
`The stop elements 128 coact with a stop lug 144
`(FIG. 4B) formed on the boss element 133 to limit rotor
`body rotation. The elements 128 are defined by radially
`inwardly projecting faces on the bearing flange 126.
`The lug 144 is molded continuously with the boss ele-
`ment 133 and the base wall 84 and projects radially
`outwardly from the boss element. The faces are spaced
`‘ apart a sufficient distance about the axis 49 to assure that
`the pedal 20 freely moves the rotor body through the
`full range of pedal travel. The stop elements limit rotor
`
`8
`member motion if the rotor member should move be-
`yond its normal operating range.
`The position signal transmitting elements 112, 114 are
`electrically coupled to conductive circuit elements on
`the stator assembly 71 to produce electrical signals
`whose values vary as a function of the rotor body posi-
`tion relative to the stator assembly 71. The illustrated
`position signal transmitting elements are potentiometer
`wiper elements each respectively engaging and bridg-
`ing pairs of stator assembly circuit elements forming
`potentiometers (the stator assembly circuit elements are
`described in detail below). Referring to FIGS. 3 and 5,
`each wiper element is a thin, highly conductive beryl-
`lium copper sheet forming first and second resilient
`contact arms 150, 152 projecting from the rotor member
`for resilient engagement with the stator assembly and a
`bridge 154 extending between the arms. The bridge 154
`is molded into the rotor member 120 with the arms
`projecting from the rotor member. Each arm terminates
`in a plurality of projecting, curved wiper fingers 156.
`The wiper fingers 156 engage electrical resistance mate-
`rial deposited on the stator assembly for producing
`position related electrical signals. The preferred fingers
`156 have gold alloy tips.
`The return spring system 118 (FIG. 3) reacts between
`the housing assembly and the rotor body 110 to bias the
`rotor body against movement away from its position
`corresponding to the “engine idle” throttle pedal posi-
`tion. The spring system 118 thus acts as a return spring
`in concert with the return springs 29 and 33. The system
`118 additionally fulfills a failsafe role by assuring that
`the pedal position signal generating unit 14 produces
`engine idle signals should the shaft 42 and rotor assem-
`bly 72 ever be disconnected.
`The illustrated spring system 118 comprises a helical
`torsion spring 160 disposed about the trunnion 122 be-
`tween a shoulder forming part of the boss structure 92
`and a washer-like spring anchor 162 surrounding the
`trunnion end projecting from the bore 90. The spring
`anchor 162 defines a peripheral notch 164 alignable
`with a radially inwardly extending key element 166
`molded into the boss structure 92 (See FIG. 4A) for
`securing the spring anchor against rotation with respect
`to the housing assembly 70. A finger (not shown)
`formed at
`the spring end adjacent
`the anchor 162
`projects through a receiving hole in the anchor so that
`the spring (160) end is fixed with respect to the housing
`assembly. The opposite end of the spring 160 is defined
`by a finger projecting into a receiving hole 169 (FIG.
`5A) in the rotor member 120. The spring 160 is initially
`stressed by “winding” it about its axis so that when the
`rotor member is in the “engine idle” position the spring
`160 forcefully retains the rotor member in place. As the
`rotor member moves away from the engine idle position
`the spring stress increases, strongly resisting the move-
`ment.
`
`The stator assembly 71 (FIGS. 3 and 6-8) is precisely
`stationed within the housing chamber for coaction with
`the rotor assembly 72 and the terminal connector ar-
`rangement 78 to produce and supply the position signals
`to the engine controller via the cable 16. The stator
`assembly comprises a stator body 180, a position signal
`assembly 182 (FIGS. 3, 7 and 8) supported by the body
`and an output signal terminal construction 184 for deliv-
`ering signals from the assembly 182 to the cable 16.
`The stator body 180 is fixed with respect to the rotor
`body 110. The preferred body 180 is a flat plate-like
`molded pla