Patent Publication Number: US-8534157-B2

Title: Electronic throttle control pedal assembly with hysteresis

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of U.S. Provisional Patent Application Ser. No. 61/305,372 filed Feb. 17, 2010, which is hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an electronic throttle control pedal assembly and, more particularly, to a pedal assembly having a hysteresis generating device. 
     BACKGROUND OF THE INVENTION 
     It is known to use pedal assemblies having position sensors to produce a “fly-by-wire” type pedal assembly for vehicle control such as brake and throttle operation rather than relying on a physical connection between the pedal and the vehicle control. A significant drawback of these pedal assemblies is that the removal of the physical connection of the pedal to the vehicle control removes the resistance or “pedal feel” that a driver is typically accustomed to sense during vehicle operation. As such, it is desirable to stimulate the feel of a mechanical pedal assembly. 
     Previously known pedal assemblies typically incorporate a spring to resist depression of the force on the pedal arm during depression of the pedal pad by the driver. However, although the compression of the spring resists depression, the springs do not simulate the “pedal feel” of a conventional pedal assembly which can be disorienting to a driver as the driver does not feel connected to the vehicle controls. Accordingly it is desirable to provide a hysteresis generating device which progressively increases the resistance to depression as the driver depresses the pedal arm. 
     SUMMARY OF THE INVENTION 
     The present invention provides an electronic throttle control pedal assembly which overcomes the above-mentioned problems of the previously known electronic throttle control pedal assemblies. 
     In brief, the electronic throttle control pedal assembly includes a housing having a cavity formed therein which is mounted to the vehicle. A hub is rotatably attached to the housing within the cavity. The hub includes at least a portion having a circumferential outer wall having an engagement portion. The pedal assembly includes a pedal arm having a pedal pad positioned at one end, and an opposite end operatively attached to the hub such that depression of the pedal pad rotates the hub. 
     A hysteresis generating device is positioned within the cavity of the housing so as to progressively increase the resistance to the depression of the pedal arm. The hysteresis generating device includes a slide member which is slidably attached to an interior surface of the housing. The slide member includes an abutment end having a generally arcuate configuration and an opposite contact end. A wedge member is positioned adjacent the contact end of the slide member such that depression of the pedal arm forces the wedge member against the contact end to slide member towards the hub. The movement of the slide member forces the abutment end of the slide member into engagement with the engagement portion of the hub thereby generating resistance to depression of the pedal arm. 
     In one embodiment the pedal arm includes a generally L-shaped configuration having an elongated leg and an arm extending generally normal to the elongated leg. A pedal pad is positioned at one end of the elongated leg and the arm extends from an opposite end of the elongated leg. In this configuration, the hub is formed as a distal portion of the arm such that the entire pedal arm is pivotal about the rotational axis of the hub. A spring pocket is formed adjacent the hub in the arm. A biasing member has one end positioned within the pocket formed in the arm and an opposite end in engagement with the wedge member. 
     In an alternative embodiment, the pedal arm is hingedly connected to the housing by a living hinge, and includes an extension arm extending at least partially within the housing. The hub includes a first arm having a hook formed at the distal end thereof which engages with the extending arm of the pedal arm such that depression of the pedal arm rotates the hub. The hub further includes a second arm which extends from an opposite side of the hub from the first arm. The second arm includes a cylindrical pocket for receiving one end of the biasing member. 
     One advantage of the present invention is that the electronic throttle control pedal assembly is provided with a hysteresis generating device which progressively increases the resistance to the pedal depression. The progressive increase of resistance as the pedal is depressed provides the driver with a more realistic feel of a mechanical pedal assembly. Other features and advantages of the present invention will be readily understood as the same becomes better understood upon reading the subsequent description when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present invention will be had upon reference to the following detailed description when read in conjunction with the accompanying drawings, wherein like reference characters refer to like parts throughout the several views and in which: 
         FIG. 1  is a front side perspective view of the inventive pedal assembly; 
         FIG. 2  is a rear side perspective view of the pedal assembly; 
         FIG. 3A  is a partial cross-sectional view illustrating the pedal arm in an initial position; 
         FIG. 3B  is a partial cross-sectional view illustrating the pedal arm in a partially depressed position and the engagement of the hysteresis generating device; 
         FIG. 4  is a partial cross-sectional view illustrating the interaction of the hysteresis generating device; 
         FIG. 5  is a rear plane view of the inventive pedal assembly with the insert removed from the housing; 
         FIG. 6  is a partial cross-sectional view of the pedal assembly with the pedal arm removed; 
         FIG. 7  is an alternative embodiment of the pedal assembly; 
         FIG. 8  is a perspective view illustrating the interaction of the hysteresis generating device of the second embodiment; and 
         FIG. 9  is a partial cross-sectional view of the second embodiment of the pedal assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention has utility as an electronic throttle control pedal assembly for use with an automotive vehicle which overcomes the above-mentioned disadvantages. The inventive electronic pedal assembly includes a hysteresis generating device which simulates the feel of a conventional mechanical pedal assembly. The hysteresis generating device includes a slide member which is driven into an engagement portion of a hub by a spring biased wedge member upon the depression of the pedal. The engagement of the slide member with the hub allows for the progressive increase of resistance to depression thereby simulating the feel of a conventional mechanical pedal assembly. 
     Referring to  FIGS. 1-6 , a first embodiment of an electronic throttle control pedal assembly for generating hysteresis to simulate the feel of a conventional mechanical pedal assembly is generally illustrated at  10 . The pedal assembly includes a housing bracket  12  for securing the pedal assembly  10  to a portion of the automotive vehicle. In the illustrated example, the housing bracket  12  is attached to a portion of the firewall (not shown) of the vehicle. 
     The housing bracket  12  includes a front wall  14 , an opposite rear wall  16 , and a pair of opposing side walls  18  which traverse the front wall  14  and the rear wall  16 . The rear wall  16  of the housing bracket  12  is formed of a generally planar surface for attaching the housing bracket  12  to the firewall (not shown) of the vehicle. The rear wall  16  includes at least one aperture  20  for securing the housing bracket  12  to the vehicle using any known fastener or attaching means to secure one object to another illustratively including bolting, screwing, welding, or adhesive. 
     As best seen in  FIG. 2 , one of the side walls  18  includes a molded pocket  22  which contains elements of a position sensor  46 , which will be described in greater detail below. A plug  24  is affixed to a top edge of the pocket  22  for the attachment of a wiring harness (not shown). The wiring harness transmits the signal from the position sensor to the vehicle control such as a brake assembly or throttle control to control the vehicle operation. 
     The housing bracket  12  has a generally boxlike structure having a cavity or interior portion defined by the rear wall  14 , front wall  16 , and the side walls  18 . The front wall  14  includes an opening  26  through which a portion of a pedal arm  28  extends. 
     The pedal arm  28  has a generally L-shaped configuration defined by an elongated leg  30  and an arm  32  extending generally normal from the elongated leg  30 . A pedal pad  34  is secured to a distal, lower end of the elongated leg  30 . In this example the pedal pad  34  has a generally rectangular shape and is formed of an isometric material such as a rubber as the pedal pad  34  contacts the foot of a driver so as to control vehicle operations. The arm  32  extends from an opposite end of the elongated leg  30  from the pedal pad  34 . A portion of the arm  32  extends through the opening  26  formed in the front wall  14  and extends into the cavity or interior portion of the housing bracket  12 . 
     Referring to  FIGS. 3A and 3B , the internal configuration of the pedal assembly  10  will now be described. The housing bracket  12  includes an internal cavity  36 . The arm  32  of the pedal arm  28  has a hub  38  formed integrally therewith at a distal end. The hub  38  has a generally circumferential outer wall  40  and has a center portion  42  which is rotatably mounted to the housing bracket  12  in any known manner such as by the engagement of pins extending from or into the central portion  42  of the hub  38 . As such, the hub  38  rotates about the central portion  42  which defines a pivot axis for the pedal arm  28 . The internal surface of the front wall  14  includes an arcuate surface  44  which is complementary in shape to the circumferential outer wall  40  of the hub  38  to guide the rotation of the hub  38  and the pivoting of the pedal arm about the central portion  42 . 
     The rotation of the hub  38  about the central portion  42  is sensed by a position sensor  46 , such as a non-contacting position sensor. In such an example, the position sensor  46  utilizes coils which are mounted on the sensor pocket  22  covered by a cover in order to create eddy currents which are measured and then delivered to the vehicle control such as the brake assembly or the throttle control for controlling operation of the vehicle. The signals generated by the position sensor  46  are transferred to the vehicle controls via the wiring harness attached to the plug  24 . 
     In the alternative, the position sensor  46  is optionally attached to the interior portion of the pocket  22  which when attached to the housing bracket  12  positions the position sensor  46  adjacent the hub  38  such that the rotation of the hub  38  can be accurately sensed. Further, the position sensor  46  is connected to a circuit board (not shown) which engages with the plug  24  to transmit the position signals to the vehicle controls via the wiring harness. It is appreciated, of course, that various other types of positioning sensors may be utilized without deviation from the scope of the invention. 
     The hub  38  includes a friction engagement portion  48  formed in the outer circumferential wall  40 . The friction engagement portion  48  is formed by radially stepping a portion of the circumferential outer wall  40  inwardly to form a channel or trough. The friction engagement portion  48  extends radially along a portion of the circumferential outer wall  40  of the hub  38 . Specifically, the friction engagement portion  48  extends about one quarter of the entire circumferential portion of the hub  38 . As best seen in  FIG. 5 , the friction engagement portion  48  is formed of a generally inwardly extending V shape such that the friction engagement portion  48  is at its widest adjacent the circumferential outer wall  40  and tapers or narrows as the friction engagement portion  48  extends inwardly towards the central portion  42  of the hub  38 . 
     In order to simulate the feel of a conventional mechanical pedal operation, the inventive pedal assembly  10  includes a hysteresis generating device  50  which provides the vehicle driver with resistance to the pedal depression. As best seen in  FIG. 4 , the hysteresis generating device  50  includes an insert  52 , a slide member  54 , a wedge member  56 , and a biasing member  58 . The insert  52  is positioned within an aperture  60  formed in the generally planar mounting surface of the rear wall  16 , as best seen in  FIG. 5 . The insert includes an exterior surface  62  which extends flush with the mounting surface of the rear wall  16 , as best seen in  FIG. 2 . The insert  52  is optionally received within the aperture  60  in a snap fit engagement or, in the alternative, the insert  52  connects to the rear wall  16  of the housing bracket  12  through the use of a fastener. The removable insert  52  is generally advantageous as the disconnection of the insert  52  from the housing bracket  12  allows for access to the cavity  36  and the remaining portions of the hysteresis generating device  50  thereby providing a reduction in time required for assembly and maintenance. 
     With reference to  FIGS. 3A ,  3 B, and  4 , an interior portion of the insert  52  which faces the cavity  36  includes a sloped surface  66  at one end and a curved surface  68  disposed at an opposite end. The curved surface  68  is formed complementary to the circumferential outer wall  40  of the hub  38  similar to the arcuate wall  44  formed at the interior surface of the rear wall  14 . The curved surface  68  of the insert  52  has a radius of curvature which is slightly larger than the circumferential outer wall  40  of the hub  38  and acts as a guide for the hub  38  during rotation. 
     Positioned between the sloped end  66  and the curved surface  68  is a generally planar portion  70 . A guide  72  extends generally normal from the planar surface  70 . The slide member  54  is slidably attached to the generally planar portion  70  of the insert  52 . The slide member  54  includes a cavity  74  formed on the side facing the interior surface of the insert  52 . The cavity  74  receives the guide  72  extending from the generally planar portion  70  of the insert  52 . The engagement of the cavity  74  and the guide  72  restricts the sliding movement of the slide member  54  such that the slide member  54  is allowed to slide along a predetermined portion of the generally planar surface  70  in the direction between the sloped surface  66  and the curved surface  68 . 
     The slide member  54  includes an angled surface  76  at an end facing the sloped surface  66  of the insert  52 . An opposite end of the slide member  54  which faces the curved surface  68  of the insert  52  has a generally arcuate surface complementary to the engagement portion  48  of the hub  38 . As best seen in  FIGS. 5 and 6 , the abutment end having an arcuate surface  78  of the slide member  54  is formed as a projection having a complementary shape to the friction engagement portion  48  of the hub  38  and which includes a radius of curvature similar to the radius of curvature of the friction engagement portion  48 . The engagement of the arcuate surface  78  of the slide member  54  with the friction engagement portion  48  of the hub  38  will be described in greater detail below. 
     The sloped surface  66  of the insert  52  and the angled surface  76  of the slide member  74  form a generally V-shape. The wedge member  56  includes a wedged portion  80  formed by a pair of angled surfaces  82  extending from a central portion  84 . The wedged portion  80  engages with the V-formation formed by the sloped surface  66  of the insert  52  and the angled surface  76  of the slide member  54 . The central portion  84  of the wedge member  56  includes a generally circular cross section and a retaining member  86  formed on a side opposite the wedge portion  80 . The retaining member  86  includes a bulbous protrusion centrally disposed within the central portion  84 . A lip  90  extends around the periphery of the central portion  84 . 
     The biasing member  58  includes a wedge end  92  and a pedal end  96 . The wedge end  92  is retained within the central portion  84  of the wedge member  56  by the lip  90  and the retaining member  86 . The pedal end  96  of the biasing member  58  is received within a cylindrical pocket  98  formed in the arm  32  of the pedal arm  28 . The cylindrical pocket  98  is formed in the arm  32  adjacent the hub  38 . 
     The biasing member  58  is optionally a pair of springs. The pair of springs includes an outer spring and an inner spring which extends coaxially with the outer spring. The biasing member  58  is used in part to bias the pedal arm  28  towards the initial or non-depressed position, and to actuate the hysteresis generating device  50 . 
     In order to facilitate a better understanding of the first embodiment of the present invention, the operation of the pedal assembly  10  will now be described. During pedal operation a driver actuates the pedal assembly  10  by depressing the pedal pad  34 . The depression of the pedal pad causes the pedal arm  28  to pivot about the central portion  42  of the hub  38 . The hub  38  rotates guided by the arcuate wall  44  and the curved surface  68  of the insert  52 . The rotation of the hub  38  causes the pedal arm  28  to pivot which compresses the biasing member  58  through the displacement of the pedal end  96  towards the hysteresis generating device  50 , specifically, the wedge member  56 . The displacement of the pedal end  96  of the biasing member  58  forces the wedge end  92  in the direction of the rear wall  16 . The displacement causes the wedge portion  80  to abut the sloped surface  66  of the insert  52  and the angled side  76  of the slide member  54 . As the wedge portion  80  moves from the front wall  14  in the direction towards the rear wall  16 , the slide member  54  slides upon the planar portion  70  of the insert  52  due to the contact of the angled side  82  and the angled surface  76 . 
     As the slide member  54  slides from the sloped surface  66  towards the curved surface  68 , the arcuate portion  78  engages with the friction engagement portion  48 . The insertion of the arcuate surface  78  of the slide member  54  into the friction engagement portion  48  causes friction due to the contact of the arcuate surface  78  with the friction engagement portion  48 . The friction caused by the contact of the arcuate surface  78  and the friction engagement portion  48  thereby generates resistance or hysteresis to simulate the feel of a conventional mechanical pedal assembly. 
     As seen in  FIG. 3B , the depression of the pedal arm  28  in the direction of arrow A 1  from the initial position towards the depressed position displaces the wedge portion  80  in the direction of arrow A 2  which forces the wedge portion  80  into engagement with the slide member  54 , specifically the angled side  76 . The abutment of the wedge portion  80  causes the slide member  54  to slide so as to be linearly displaced in the direction of arrow A 3  which introduces more of the abutment end having the arcuate surface  78  into engagement with the friction engagement portion  48  in order to generate additional resistance to the depression of the pedal arm  28 . As clearly seen in  FIG. 3B , the directions of arrows A 2  and A 3  are nonparallel, and in particular generally normal. Accordingly, the force applied to the pedal pad  34  is transmitted to the slide member  54  via the wedge member  56  thereby increasing resistance in step with the amount of force applied to the pedal arm  28 . 
     The interaction of the guide  72  formed on the generally planar portion  70  of the insert  52  and the cavity  74  of the slide member  54  is provided as a limit to the amount of movement the slide member  54  can be slid in the direction of the curved surface  68  of the insert  52 . Further, a friction pad  100 , formed of high friction material, is optionally attached to either the interior surface of the arcuate surface  78  of the slide member  54  or into the channel or trough formed in the friction engagement portion  48  in order to increase the amount of friction produced by the engagement of the arcuate surface  78  into the friction engagement portion  48 . 
     With reference to  FIGS. 7-9 , an alternative embodiment of the inventive pedal assembly having the hysteresis generating device is generally illustrated at  210 . The second embodiment of the pedal assembly  210  is an organ style pedal assembly which mounts to the floor (not shown) of the vehicle. The pedal assembly  210  includes a pedal arm  212  and a mounting bracket  214 . 
     The pedal arm  212  includes a pedal pad  216  optionally formed of an isometric material so as to provide friction between the pedal pad  216  and a driver&#39;s foot. The pedal arm  212  connects to the mounting bracket  214  at a lower edge by a living hinge  218  which pivotally connects the pedal arm  212  to the housing bracket  214 . An extension  220  extends outwardly from the pedal arm on a side opposite the pedal pad  216 . The extension  220  extends through an opening  222  formed in the housing bracket  214  and abuts a guide portion  224 . The pedal arm  212  pivots about the living hinge  218  and is guided along a predetermined pedal path by the interaction of the extension  220  and the curved portion  224 . 
     A hub  232  is rotatably mounted to the housing bracket  214  such that the hub  232  rotates about a central portion  234  upon depression of the pedal pad  216 . The extension  220  engages with a hook  226  formed on a first arm  230  extending outwardly from the hub  232 . The hub  232  rotates about the central portion  234  in response to depression of the pedal arm  212 . A second arm  236  extends outwardly from the hub  232  on a side opposite from the first arm  230 . 
     Positioned within the housing bracket  214 , is a hysteresis generating device  242 . The hysteresis generating device  242  includes biasing member  244 , wedge member  246 , and slide member  248 . An interior surface  250  of the housing bracket  212  includes a sloped surface  252 , a curved surface  254 , and a generally planar surface  256  disposed between the sloped surface  252  and the curved surface  254 . The slide member  248  is slidably attached to the interior surface  250 , specifically the planar surface  256 . The slide member  248  includes an angled end  260  and an abutment or arcuate end  258  which corresponds in shape and curvature to a stepped in friction engagement portion  262  formed in the circumferential outer wall  264  of the hub  232 . The arcuate end  258 , the friction engagement portion  262 , or both optionally include a friction pad  268  formed of a high friction material to increase the friction and therefore the hysteresis generated by the engagement of the arcuate end  258  and the friction engagement portion  262 . 
     The hysteresis generating device  242  is substantially similar to the hysteresis generating device  50  of the first embodiment. The hysteresis generating device  242  generates hysteresis due to the engagement of the arcuate end  258  into the friction engagement portion  262  due to the sliding of sliding member  248  caused by downward movement of the wedge member  246  caused by rotation of the hub  232  about central portion  234  in response to depression of the pedal arm  212 . The difference between the hysteresis device  242  and hysteresis device  50  is the attachment of the biasing member  244  to the hub  232 . 
     Biasing member  244 , optionally a pair of springs including an outer spring and an inner spring extending coaxially with the outer spring, includes a wedge end  264 , which connects to the wedge member  246  in a manner similar to the wedge member  56 , and an arm end  266 . As best seen in  FIG. 9 , the second arm  236  includes a cylindrical pocket  238  which engages with the arm end  266  of the biasing member  244 . As such, the arm end  266  of the biasing member  244  of the hysteresis device  242  connects to the second arm  236  extending radially outwardly from the hub  232 , rather than connecting to the pocket  98  formed in the arm  32  of the pedal arm  28  as in the hysteresis generating device  50 . 
     The operation of the pedal assembly  210 , specifically the hysteresis generating device  242 , is similar to the operation of the hysteresis generating device  50  of a first embodiment in that depression of the pedal arm  212 , specifically the pedal pad  216 , operates to rotate the hub  232  about central portion  234 . The rotation of the hub  232  rotates the second arm  236  which acts to compress the biasing member  244 . The compression of the biasing member  244  forces the wedge member  246  to engage the slide member  248 . The slide member  248  slides and the arcuate end  258  engages with the friction engagement portion  262  formed in the hub  232  so as to generate resistance to the depression of the pedal pad  216  thereby simulating the feel of a conventional mechanical pedal assembly. 
     A sensor  270  is used to detect the operation of the pedal arm  212 . Specifically, the rotation of the hub  232  about the central portion  234  is sensed by the position sensor  270 , such as a non-contacting position sensor. It is appreciated, of course, that various other types of positioning sensors may be utilized without deviation from the scope of the invention. 
     It is appreciated, of course, that the inventive pedal assemblies  10  and  210  are not limited to electronic throttle control pedals. The inventive pedal assemblies  10  and  210  are optionally used for controlling any vehicle operation illustratively including brake control, clutch control or any other operation which requires the pedal to simulate the feel of a mechanically connected pedal. 
     The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.