Abstract:
An electronic accelerator pedal system with a foot pressure-adjusting function. The foot pressure is variably adjusted with respect to the pedal arm stroke during the depressing and releasing of the accelerator pedal to improve the accelerator manipulation sensation. A foot pressure-adjusting means is installed on the pedal arm that causes a foot pressure to be varied in accordance with the pivoting direction of the pedal arm.

Description:
FIELD OF THE INVENTION 
   Generally, the present invention relates to an electronic accelerator pedal system with a foot pressure-adjusting function. More particularly the electronic accelerator pedal incorporates a system that provides variable resistance with respect to the stroke of the pedal arm during depression and release of the accelerator pedal. 
   BACKGROUND OF THE INVENTION 
   Typically, an accelerator manipulation device is either a mechanical device or an electronic device. The mechanical accelerator pedal system includes a pedal that is pivotally mounted on the driver&#39;s side floorboard, a throttle mechanism installed in the intra-engine suction system, and a cable connecting the accelerator pedal to the throttle mechanism that transmits a manipulation force. An electronic accelerator pedal system includes an accelerator pedal pivotally mounted on the driver&#39;s side floorboard and a detection sensor installed on the accelerator pedal that detects the position of the accelerator pedal on a real time basis. 
   A conventional mechanical accelerator pedal system generates a foot pressure hysteresis effect, and thus, no special problem occurs in the foot pressure tuning of the accelerator pedal. The foot pressure hysteresis effect refers to a phenomenon where a driver&#39;s passive reaction force (about 2 kgf), caused from friction of the cable during the releasing of the pedal, is small compared to the driver&#39;s passive reaction force (about 3.5˜4.5 kgf) during the depressing of the pedal. In contrast, in a conventional electronic accelerator pedal system the driver&#39;s passive reaction force, during depression, steady state, and release of the pedal, is determined only by the inherent elasticity of a return spring. The quantitative degree of the reactive force of the return spring is determined on the basis of depression of the pedal for acceleration. However, a drawback of this system is that there is no resistance in the system which counteracts the spring&#39;s reactive force while a driver holds a steady accelerator position. As a result, the driver&#39;s ankle is subjected to fatigue after repetitive depressions of the pedal. Consequently, the manipulability of the accelerator is aggravated. 
   SUMMARY OF THE INVENTION 
   The present invention provides an electronic accelerator pedal system with a foot pressure-adjusting function. The pivoting of the pedal is electrically detected to determine the degree of acceleration requested by the driver. The reactive foot pressure felt by the driver is made variable during the depressing and releasing of the pedal. Therefore, the driver&#39;s fatigue during frequent manipulation of the pedal is reduced, thereby improving the manipulability of the accelerator. 
   In accordance with an embodiment of the present invention, the electronic accelerator pedal system with a foot pressure-adjusting function comprises a pedal arm pivotally installed within a car interior. Additionally, a detection sensor for detecting the degree of pedal arm movement and a foot pressure-adjusting means is installed on the pedal arm for varying the foot pressure in accordance with the pivoting direction of the pedal arm. Furthermore, a contact member for contacting the foot pressure-adjusting means during the pivoting of the pedal arm is included. 
   In an alternative embodiment the electronic pedal system comprises a pedal arm pivotally coupled with a structural body and a detector sensor for detecting an amount of movement of the pedal arm. An elastic member generates a return force against movement of the pedal arm. Also included is a pressure-adjusting system that comprises a first friction member coupled to the pedal arm and a second friction member coupled to the structural body. The second friction member is configured and dimensioned to contact the first friction member and the contact between the friction members opposes movement of the pedal arm. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is an exploded perspective view of an embodiment of the electronic accelerator pedal system of the present, invention with a foot pressure-adjusting function; 
       FIG. 2  is a perspective view showing the assembled state of the electronic accelerator pedal system of  FIG. 1 ; 
       FIG. 3  illustrates an enlarged view of the coupling portion between the pedal arm and the foot pressure-adjusting means of  FIG. 1 ; 
       FIG. 4  is a perspective view of a contact member that accommodates and contacts the foot pressure-adjusting means of  FIG. 1 ; 
       FIG. 5  illustrates the contact state between the foot pressure-adjusting means and the contact member during the depressing and releasing of the accelerator pedal; 
       FIG. 6  is a graphical illustration showing the variation of the foot pressure with respect to the accelerator pedal stroke; 
       FIG. 7  illustrates another embodiment of the foot pressure-adjusting means according to the present invention; 
       FIG. 8  illustrates still another embodiment of the foot pressure-adjusting means according to the present invention; and 
       FIG. 9  illustrates yet another embodiment of the foot pressure-adjusting means according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIGS. 1 and 2 , the electronic accelerator pedal system with a foot pressure-adjusting function according to the present invention includes a housing  10  secured to a lower panel within a car&#39;s interior. A pedal arm  12  is pivotally installed on the housing  10  and a detection sensor  14 , such as a potentiometer, is secured on one side of the housing  10 . The detection sensor  14  electrically detects the degree the pedal arm  12  is pivoted during use. A foot pressure-adjusting means is installed on the pedal arm  12  for varying the foot pressure in accordance with the pivoting direction of the pedal arm  12 . Also, a contact member  16  is formed on the leading end of the housing  10  for contacting the foot pressure-adjusting means during the pivoting of the pedal arm. 
   A pivot-supporting fastening pin  18  is coupled to the housing  10  and the pedal arm  12  provide pivot of the pedal arm  12  with respect to the housing  10 . A pair of torsion springs  20  are fitted to the fastening pin  18  to elastically pivot the pedal arm  12  in relation to the housing  10 . On one end of the pivot-supporting fastening pin  18 , there is a securing pin  22  for preventing the fastening pin  18  from becoming separated from the housing  10  and the pedal arm  12 . 
   As shown in  FIG. 3 , the foot pressure-adjusting means includes a friction plate  24  that is detachably coupled to the leading end of the pedal arm  12 . The friction plate  24  includes an elastic installation part  24   a  having a pair of inclinedly spread protuberance parts  24   b  that couple to the leading end of the pedal arm  12  to maintain an elastic supporting force. A contact part  24   c  integrally extends from the elastic installation part  24   a  to contact the contact member  16 . Also included is pair of securing support parts  24   d  that integrally extend from both ends of the contact part  24   c . The pair of securing support parts  24   d  couple to the leading end of the pedal arm  12  and generate a securing strength. 
   The leading end of the pedal arm  12  has a mounting slot  12   a  for elastically receiving the friction plate  24 . The mounting slot  12   a  receives the elastic installation part  24   a  of the friction plate  24 . The mounting slot  12   a  is formed by a pair of elastic protuberances  12   b  which are inclinedly spread out to be contacted to the elastic installation part  24   a  of the friction plate  24 . Furthermore, two auxiliary protuberance parts  12   d  are formed outside two auxiliary mounting slots  12   c  for receiving the securing and supporting parts  24   d  of the friction plate  24 . 
   As shown in  FIGS. 4 and 5 , the leading end of the pedal arm  12  is pivotally installed into the contact member  16  which projects upward on the housing  10 . The contact member  16  includes a space of an opening part  16   a  that opens in the front and receives the leading end of the pedal arm  12 . A contact face  16   b  is vertically formed for contacting the friction plate  24  that functions as the foot pressure-adjusting means. The friction plate  24 , which is coupled to the leading end of the pedal arm  12 , maintains contact with the contact face  16   b  of the contact member  16  during the pivoting of the pedal arm  12 . 
   In use, if the driver depresses the pedal arm  12  during acceleration, the pedal arm  12  pivots around the fastening pin  18  upon the housing  10 . Under this condition, the contact part  24   c  of the fiction plate  24  sustains contact with the contact face  16   b  of the contact member  16  and generates friction. 
   The degree of the driver&#39;s foot pressure that is transmitted to the pedal arm  12  varies depending on the direction of the friction force generated between the friction plate  24  and the contact member  16 . That is, the degree of foot pressure required is variable depending on whether the driver is depressing the accelerator or releasing the accelerator, as graphically illustrated in  FIG. 6 . When the driver depresses the accelerator pedal, the variation of the foot pressure with respect to the stroke of the pedal arm  12  is equivalent to the sum of the inherent restoring force of the torsion spring  20  and the friction force generated between the friction plate  24  and the contact member  16 . This is represented in graph A of  FIG. 6 . 
   If the driver releases the acceleration (this refers to the state where the driver releases the pedal arm to cause deceleration, or the driver maintains a constant velocity of the car), then the variation of the foot pressure is ascertained by the difference between the inherent elastic restoring force of the torsion springs  20  and the friction force (between the friction plate  24  and the contact member  16 ). This is represented in graph B of  FIG. 6 . That is, during a constant velocity, the direction of the friction force between the friction plate  24  and the contact member  16  is opposite to the direction of the elastic restoring force of the torsion spring  20 . Therefore, if the driver desirers to maintain a constant car velocity, a foot pressure greater than the difference between the elastic restoring force of the torsion spring  20  and the friction force (between the friction plate  24  and the contact member  16 ) must be transmitted to the pedal arm  12 . 
   Thus, during the depressing and releasing of the pedal arm, the reaction force which is received by the driver is different. Therefore, a foot pressure hysteresis can be formed, similar to the conventional mechanical cable-type accelerating system. Following adjustment to the elastic restoring force of the torsion spring  20  and the friction force between the friction plate  24  and the contact member  16 , the foot pressure of the acceleration system can be set as desired. 
   The mounting slots  12   a  and the elastic protuberance part  12   b  together with the engaged elastic protuberance part  24   b  of the friction plate  24  forms an elastic restoring force which maintains contact between the friction plate  24  and the contact force  16   b  even following wear of the components. Therefore the foot pressure hysteresis is maintained. If grease or another lubricant is applied between the contact part  24   c  of the friction plate  24  and the contact face  16   b  of the contact member  16 , noise generated by this contact can be prevented during the depressing and releasing of the pedal arm  12 . 
     FIG. 7  illustrates another embodiment of the foot pressure-adjusting means according to the present invention. The foot pressure-adjusting means includes a contact plate  28  with its rear face elastically supported to the leading end of the pedal arm  12  through a return spring  26 . In this embodiment, the contact plate  28  is substituted for the friction plate  24  of the earlier embodiment. Furthermore, a closed space is formed in the leading end of the pedal arm  12  for accommodating the return spring  26 . An engaging part  28   a  is provided on the rear face of the contact plate  28  for preventing the return spring  26  from departing from the closed space. 
     FIG. 8  illustrates still another embodiment of the foot pressure-adjusting means of the present invention. The foot pressure-adjusting means includes a hollow elastic plate  32  with its rear face secured to the leading end of the pedal arm  12  by means of a fastening pin  30 . The front face faces toward the contact face  16   b  of the contact member  16 . In this embodiment, the elastic plate  32  can be substituted for the friction plate  24  of the earlier embodiment. 
     FIG. 9  illustrates yet another embodiment of the foot pressure-adjusting means of the present invention. The foot pressure-adjusting means includes an elastic member  36  made of rubber, with its rear face secured to the leading end of the pedal arm  12  by means of a fastening pin  34 . In this embodiment the elastic member  36  can be substituted for the friction plate  24  of the earlier embodiment of the present invention. 
   In the later described embodiments, the contact plate  28 , the elastic plate  32  and the elastic member  36 , which can be substituted for the friction plate  24  of the first embodiment, cause variations in the degree of foot pressure with respect to the stroke of the pedal arm  12  in the same manner as that of the earlier embodiment. 
   Many modifications and variations of the described embodiments will be apparent to one skilled in the art. The embodiments described in this application are intended for descriptive purposes and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims, along with the full scope of equivalents to which such claims are entitled.