Abstract:
A pedal module includes a double coil spring, a pedal, and a damping part. The double coil spring includes an outside coil and an inside coil. The pedal turns in a forward direction when a depressing force is applied thereto and turns in a reverse direction when a restoring force of the double coil spring is applied thereto. The damping part has an inserting portion disposed between the outside coil and the inside coil. The inserting portion includes a middle portion and a first side end portion disposed relative to each other in a width direction that corresponds to a circumferential direction of the double coil spring. The middle portion crosses a radial axis of the double coil spring and protrudes beyond the first side end portion toward an axial end of the double coil spring.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority of Japanese Patent Application No. 2004-44460, filed on Feb. 20, 2004, the contents of which are incorporated herein by reference.  
       FIELD OF THE INVENTION  
       [0002]     The present invention relates to a pedal module and, in particular, to a pedal module suitable for an accelerator for a vehicle.  
       BACKGROUND OF THE INVENTION  
       [0003]     In a conventional pedal module used for an accelerator for a vehicle, a pedal is turned forward by the action of a depressing force and is reversed by the urging force of a spring. Among the modules like this is a publicly known module that reverses the pedal from a forward position by the use of a double coil spring, as disclosed in Japanese patent document JP-A No. 2003-39970.  
         [0004]     In recent years, it is thought that a damping part  100  as shown in  FIG. 16  is arranged in the pedal module using a double coil spring. To be specific, the damping part  100  is formed in the shape of a rectangular flat plate and is bent in the shape of a letter U and a middle portion in the direction of length is retained by an inside coil  111  of a double coil spring  110 . Both end portions in the direction of length in the damping part  100  are formed into inserting portions  101  inserted between the inside coil  111  and an outside coil  112  of the double coil spring  110 , respectively. These inserting portions  101  can prevent the establishment of resonance of the inside coil  111  and the outside coil  112  with external vibration. Further, these inserting portions  101  secure the gaps between the inside coil  111  and the outside coil  112  and prevent these coils  111  and  112  from being put into contact with each other. Hence, the double coil spring  100  can deliver desired spring characteristics.  
         [0005]     Here, as for the respective inserting portions  101  of the damping part  100  shown in  FIG. 16 , attention is paid to their side end portions  102  in such a direction of width thereof (or peripheral direction of spring) that crosses the radial axis  113  of the double coil spring  110 . As shown in  FIG. 17 , when the double coil spring  110  is compressed, first, the side end portions  102  of the respective inserting portions  101  abut against the outside coil  112  in a gap  114  between windings of the outside coil  112 . This is caused by the fact that the side end portions  102  of the respective inserting portions  101  are apt to enter the gap  114  between the windings of the outside coil  112  before the double coil spring  110  shown in  FIG. 16  is compressed. When the double coil spring  110  is further compressed from a state where the side end portions  102  abut against the outside coil  112  in the gap  114  between the windings, the side end portions  102  are sprung and disengaged from the outside coil  112 . Impact caused at this time produces abnormal noises and propagates to the pedal to impair feeling of depressing the pedal.  
       SUMMARY OF THE INVENTION  
       [0006]     An object of the invention is to provide a pedal module for preventing the occurrence of abnormal noises and the deterioration of feeling of depressing a pedal.  
         [0007]     In accordance with one aspect of the invention, in the inserting portion, a middle portion in such a direction of width that crosses an axis in the radial direction of the double coil spring is protruded toward one end of the double coil spring as compared with a side end portion in the direction of width. For this reason, the side end portion in the direction of width of the inserting portion is hard to enter a gap between windings of an outside coil and hence the side end portion in the direction of width is hard to abut against the outside coil in the gap between the windings of the outside coil when the double coil spring is compressed. Alternatively, even if the side end portion in the direction of width of the inserting portion enters the gap between the windings of the outside coil, when the double coil spring is compressed, a portion between the side end portion in the direction of width and such a middle portion in the direction of width that protrudes as compared with the side end portion in the inserting portion abuts against the outside coil, thereby being guided inside the outside coil. With this, the side end portion in the direction of width is hard to abut against the outside coil in the gap between the windings of the outside coil.  
         [0008]     In this manner, the side end portion in the direction of width of the inserting portion is prevented from abutting against the outside coil in the gap between the windings of the outside coil. Hence, it is possible to avoid a problem that the side end portion is detached from the outside coil after the side end portion abuts against the outside coil to cause impact. Therefore, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the pedal, which are caused when the damping part interferes with the outside coil.  
         [0009]     According to another aspect of the present invention, an angle formed by the slant surface portion, which connects a side end portion in the direction of width to such a middle portion in the direction of width that is protruded as compared with the side end portion in the inserting portion, and an axis in the direction of width of the inserting portion is made larger than an angle formed by a material center line of the outside coil and the axis in the direction of width of the inserting portion. For this reason, it is possible to prevent the side end portion in the direction of width from abutting against the outside coil when the double coil spring is compressed. Therefore, it is possible to improve an effect of preventing the occurrence of abnormal noises and the deterioration of feeling of depressing the pedal.  
         [0010]     In this regard, the slant surface portion that connects the side end portion in the direction of width in the inserting portion and the middle portion in the direction of width that is protruded as compared with the side end portion may be formed in the shape of a curved surface.  
         [0011]     According to yet another aspect of the present invention, in the inserting portion, the middle portion in the direction of width is protruded toward the outside coil as compared with the side end portion in the direction of width. For this reason, the side end portion in the direction of width is hard to enter a gap between the windings of the outside coil. With this, when the double coil spring is compressed, it is possible to sufficiently prevent the side end portion in the direction of width from abutting against the outside coil in the gap between the windings of the outside coil. Therefore, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the pedal.  
         [0012]     According to yet another aspect of the present invention, in the inserting portion, a middle portion in such a direction of width that crosses an axis in the radial direction of the double coil spring and in such a direction of width that is not parallel to the center axis of the double coil spring is protruded toward the outside coil as compared with a side end portion in the direction of width. For this reason, the side end portion is hard to enter the gap between the windings of the outside coil. With this, when the double coil spring is compressed, the side end portion in the direction of width is hard to abut against the outside coil in the gap between the windings of the outside coil. Hence, it is possible to avoid a problem that the side end portion is detached from the outside coil after the side end portion abuts against the outside coil to cause impact. Therefore, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the pedal, which are caused when the damping part interferes with the outside coil.  
         [0013]     According to yet another aspect of the present invention, a damping part is adopted which is constructed of two inserting portion facing each other across the inside coil and a retaining portion that connects the two inserting portions and is retained by the inside coil in a gap between windings of the inside coil. With this, it is possible to facilitate a work of arranging the two inserting portions and to improve an effect of preventing resonance with external vibration.  
         [0014]     In the accelerator for a vehicle, there are cases where a double coil spring is used in order to increase an urging force applied to its accelerator pedal.  
         [0015]     Another aspect of the present invention is used as an accelerator for a vehicle in which the pedal is an accelerator pedal. Hence, it is possible to increase an urging force applied to the accelerator pedal and to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the pedal which are caused by the damping part. Therefore, the invention is suitable for an accelerator for a vehicle.  
         [0016]     Other features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts from a study of the following detailed description, appended claims, and drawings, all of which form a part of this application. In the drawings: 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1A  is a partially hidden front view of a damping part in accordance with a first embodiment of the present invention is attached to a double coil spring;  
         [0018]      FIG. 1B  is a cross-sectional view taken through line I-I of  FIG. 1A ;  
         [0019]      FIG. 2  is a cross-sectional side view of an accelerator for a vehicle in accordance with the first embodiment of the present invention;  
         [0020]      FIG. 3  is a perspective view of the damping part of  FIG. 1 ;  
         [0021]      FIG. 4A  is a front view of the damping part of  FIG. 1  for illustrating its operation;  
         [0022]      FIG. 4B  is a cross-sectional view taken through line IV-IV in  FIG. 4A ;  
         [0023]      FIG. 5  is a perspective view of a damping part in accordance with a second embodiment of the present invention;  
         [0024]      FIG. 6  is a perspective view of a damping part in accordance with a third embodiment of the present invention;  
         [0025]      FIG. 7  is a perspective view of a damping part in accordance with a fourth embodiment of the present invention;  
         [0026]      FIG. 8  is a perspective view of a damping part in accordance with a fifth embodiment of the present invention;  
         [0027]      FIG. 9A  is a front view of the damping part of the fifth embodiment attached to a double coil spring;  
         [0028]      FIG. 9B  is a cross-sectional view taken through line IX-IX of  FIG. 9A ;  
         [0029]      FIG. 10  is a perspective view of a damping part in accordance with a sixth embodiment of the present invention;  
         [0030]      FIG. 11A  is a front view of the damping part of the sixth embodiment attached to a double coil spring;  
         [0031]      FIG. 11B  is a cross-sectional view taken through line XI-XI of  FIG. 11A ;  
         [0032]      FIG. 12  is a perspective view of a damping part in accordance with a seventh embodiment of the present invention;  
         [0033]      FIG. 13A  is a front view of the damping part of the seventh embodiment attached to a double coil spring;  
         [0034]      FIG. 13B  is a cross-sectional view taken through line XIII-XIII of  FIG. 13A ;  
         [0035]      FIG. 14  is a perspective view of a damping part in accordance with an eighth embodiment of the present invention;  
         [0036]      FIG. 15A  is a front view of the damping part of the eighth embodiment attached to a double coil spring;  
         [0037]      FIG. 15B  is a cross-sectional view taken through line XV-XV of  FIG. 15A ;  
         [0038]      FIG. 16A  is a front view of a conventional damping part attached to a double coil spring;  
         [0039]      FIG. 16B  is a cross-sectional view taken through line XVI-XVI of  FIG. 16A ;  
         [0040]      FIG. 17A  is a front view of the conventional damping part of  FIG. 16  in a compressed state; and  
         [0041]      FIG. 17B  is a cross-sectional view taken through line XVII-XVII of  FIG. 17A . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0042]     A plurality of preferred embodiments of the invention will now be described with reference to the drawings.  
         [0043]     An accelerator  1  for a vehicle as a pedal module in accordance with the first embodiment of the invention is shown in  FIG. 2 . The accelerator  1  for a vehicle as a pedal module in accordance with the first embodiment controls the driving state of the vehicle in response to a driver&#39;s operation of an accelerator pedal  2 . The accelerator  1  adopts an accelerator-by-wire system and the accelerator pedal  2  is not mechanically coupled to the throttle unit of the vehicle. Instead, the accelerator  1  detects a turn angle of the accelerator pedal  2  with a turn angle sensor (not shown) and outputs a signal to indicate its detection result to an electronic control unit (ECU) of a vehicle engine. With this, the ECU controls the throttle unit on the basis of the turn angle of the accelerator pedal  2  derived from the output signal of the turn angle sensor.  
         [0044]     A housing  10  supporting the accelerator pedal  2  is formed of resin in the shape of a box having an opening  11 . The bottom plate  12  of housing  10  is fixed to the vehicle by bolts or a similar fastening means. A first stopper  13  formed of elastic material such as rubber is fixed to an inner wall of the bottom plate  12 . A fixing hole  15  shaped like a stepped circular cylinder, the diameter of which becomes smaller as its depth becomes larger, is formed in an inner wall of a top plate  14  facing the bottom plate  12  in the housing  10 . A second stopper  16  is formed integrally with an edge portion forming the opening  11  in the top plate  14 . A turn angle sensor (not shown) for detecting the turn angle of the accelerator pedal  2  is fixed to a side plate  17  in the housing  10  and a connector part  18  for electrically connecting the turn angle sensor to the ECU is provided on the outer wall of the side plate  17 .  
         [0045]     The accelerator pedal  2  is formed of resin and is extended in the shape of a letter V. One end in the direction of length of the accelerator pedal  2  is received in the housing  10  and the other end in the direction of length is extended through the opening  11  to the outside of the housing  10 . The accelerator pedal  2  has a turning shaft  20  in a middle portion in the direction of length that is received in the housing  10 . The turning shaft  20  is supported by the side plate  17  of the housing  10  and is arranged in such a way as to be freely rotated around its axis. For purposes of this description, a reference symbol X in  FIG. 2  denotes a forward rotational side of the accelerator pedal  2  and Y denotes a reverse rotational side of the accelerator pedal  2 .  
         [0046]     The accelerator pedal  2  has a depressing portion  21  at an end portion on a side extending from the housing  10 . A driver depresses the depressing portion  21  to apply a depressing force to the depressing portion  21  for turning the accelerator pedal  2  forward.  
         [0047]     The accelerator pedal  2  has an abutting portion  22  at a position between the turning shaft  20  and the depressing portion  21  in the direction of length thereof. The abutting portion  22  can abut against the second stopper  16 .  
         [0048]     The accelerator pedal  2  has a plate-shaped retaining portion  23  at an end portion on a side received in the housing  10 . In the retaining portion  23 , one plate surface  24  faces the bottom plate  12  and the other plate surface  25  faces the top plate  14 . The plate surface  24  of the retaining portion  23  can abut against the first stopper  13 . The retaining portion  23  has an integral protruding portion  26  protruding from the plate surface  25  toward the top plate  14 . The protruding portion  26  is formed in the shape of a stepped circular column, the diameter of which becomes smaller as the position becomes closer to its protruding end side.  
         [0049]     A double coil spring  30  is interposed between the top plate  14  and the retaining portion  23 . The double coil spring  30  is constructed of a combination of two cylindrical compression springs having predetermined uniform diameters. In the double coil spring  30 , an outside coil  31  has a larger diameter than an inside coil  32  and is wound in a direction opposite to the inside coil  32  and is coaxially arranged outside the inside coil  32 . One end of the outside coil  31  is fixed to a large diameter portion  15   a  of the fixing hole  15  and the other end of the outside coil  31  is retained by a large diameter portion  26   a  of the protruding portion  26 . One end of the inside coil  32  is fixed to a small diameter portion  15   b  of the fixing hole  15  and the other end of the outside coil  32  is retained by a small diameter portion  26   b  of the protruding portion  26 . The outside coil  31  and the inside coil  32  produce a restoring force when they are axially compressed between the top plate  14  and the retaining portion  23 . Further, in this embodiment, the outside coil  31  and the inside coil  32  are curved away from the turning shaft  20  to produce a supplemental restoring force. Hence, the double coil spring  30  applies a resultant force of the restoring forces, which are respectively produced by the outside coil  31  and the inside coil  32 , as an urging force to the retaining portion  23 . At this time, the urging force is applied to the retaining portion  23  in such a way as to turn the accelerator pedal  2  in the reverse direction.  
         [0050]     In this manner, when the depressing force is applied to the depressing portion  21  of the accelerator pedal  2  to separate the retaining portion  23  and the abutting portion  22  from the first stopper  13  and the second stopper  16 , respectively, the accelerator pedal  2  is allowed to be turned in forward and reverse directions. At this time, the double coil spring  30  is compressed in the axial direction in response to the turn angle of the accelerator pedal  2 . In contrast to this, when the retaining portion  23  and the abutting portion  22  of the accelerator pedal  2  are turned in the reverse direction by the urging force of the double coil spring  30  to abut against the first stopper  13  and the second stopper  16 , respectively, the accelerator pedal  2  is prohibited from being turned further in the reverse direction. At this time, the double coil spring  30  is brought into a state where it is most elongated in the axial direction.  
         [0051]     A damping part  40  is attached to the double coil spring  30 . The damping part  40  will be described below in detail.  
         [0052]      FIG. 3  shows a state where the damping part  40  is detached from the double coil spring  30 . First, the damping part  40  in this state will be described. The damping part  40  is formed of elastic material such as rubber in the shape of a long flat plate. In each of both end portions in the direction of length of the damping part  40 , a middle portion  41  in the direction of width is protruded outside in the direction of length from the side end portions  42 ,  43  on both sides in the direction of width and is pointed in an angular shape. Further, in each of both of the end portions, slant surface portions  44 ,  45 , which respectively connect the middle portion  41  in the direction of width to side end portions  42 ,  43  in the direction of width and slant with respect to an axis  48  in the direction of width, are formed respectively in the shape of a flat surface, whereby the damping part  40  is formed in a hexagon when viewed from the direction of thickness. The thickness of the damping part  40  is nearly constant in the direction of length and in the direction of width.  
         [0053]      FIG. 1  shows a state where the damping part  40  is attached to the double coil spring  30 . Next, the damping part  40  in this state will be described. The damping part  40  is bent at two positions in the direction of length along the direction of width in such a way as to be formed into the shape of a letter U when viewed from the direction of width. In the damping part  40 , a middle portion in the direction of length which forms a bottom portion of a shape like a letter U forms a retaining portion  46  retained by a wiring  34  of the inside coil  32  in a gap  33  between the windings of the inside coil  32 . In the damping part  40 , both end portions in the direction of length, each of which forms a side portion of the shape like a letter U, form inserting portions  47  inserted between the outside coil  31  and the inside coil  32 , respectively. In this manner, the damping part  40  is formed in which the retaining portion  46  connects the respective inserting portions  47  facing each other across the inside coil  32 .  
         [0054]     In the damping part  40  attached to the double coil spring  30  in the above-described manner, the direction of width of the respective inserting portions  47  becomes a direction that crosses the radial axis  30   a  of the double coil spring  30  and is not parallel to the center axis  30   b  of the double coil spring  30 , in particular, in this embodiment, a direction along the material center line  35  of the inside coil  32 . In each of the inserting portions  47 , the middle portion  41  in the direction of width is formed in a shape protruding toward the same one end of the double coil spring  30  from the side end portions  42 ,  43  on both sides in the direction of width. Further, in each of the inserting portions  47 , an angle θ 1  formed by the slant surface portion  44  ( 45 ) and the axis  48  in the direction of width is larger than an angle θ 2  formed by the material centerline  36  of the outside coil  31  and the axis  48  in the direction of width. Here, in this embodiment, the angle θ 2  is nearly equal to the sum of pitch angles of the outside coil  31  and the inside coil  32  which are wound in reverse directions with respect to each other.  
         [0055]     In the state where the double coil spring  30  is elongated most as shown in  FIG. 1 , of the side end portions  42 ,  43  of the respective inserting portions  47 , the side end portion  42  closer to the wiring  37  of the outside coil  31  located on the protruding side of the middle portion  41  is apt to enter a gap  38  between the windings of the outside coil  31 .  
         [0056]     When the double coil spring  30  is compressed from a state shown in  FIG. 1 , as shown in  FIG. 4 , the middle portions  41  of the respective inserting portions  47  do not abut against the outside coil  31  but pass through between the outside coil  31  and the inside coil  32 . For this reason, in the respective inserting portions  47 , first, the slant surface portions  44  each connecting the side end portion  42  to the middle portion  41  abut against the wiring  37  of the outside coil  31 . When the double coil spring  30  is further compressed after the slant surface portions  44  abut against the wiring  37 , the slant surface portions  44  of the respective inserting portions  47  are guided inside the wiring  37  of the outside coil  37  by the wiring  37 . For this reason, the side end portions  42  of the respective inserting portions  47  are hard to abut against the outside coil  31  in the gap  38  between the windings. In particular, in this embodiment, the slant surface portion  44  of each of the inserting portions  47  increases the effect of preventing the side end portions  42  of the respective inserting portion  47  from abutting against the outside coil  31  because the angle θ 1  formed by the slant surface portion  44  and the axis  48  in the direction of width is larger than the angle θ 2  formed by the material center line  36  of the outside coil  31  and the axis  48  in the direction of width.  
         [0057]     According to the first embodiment described above, it is possible to prevent the side end portions  42  in the direction of width of the respective inserting portions  47  from abutting against the outside coil  31  in the gap  38  between the windings and further to prevent the side end portions  42  from detaching from the outside coil after abutting to cause impact. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal as in the case of the conventional accelerator pedal.  
         [0058]     Further, according to the first embodiment, because two inserting portions  47  are inserted between the outside coil  31  and the inside coil  32 , it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal and at the same time to improve an effect of preventing resonance with external vibration. In addition, since the damping part  40  having two inserting portions  47  like this is formed of a single part, the respective inserting portions  47  can be arranged with ease.  
         [0059]     A second embodiment of the present invention is a modification of the first embodiment and  FIG. 5  shows a state where a damping part  50  in accordance with the second embodiment is detached from the double coil spring  30 . Slant surface portions  51 ,  52 , each of which connects the middle portion  41  in the direction of width to the side end portions  42 ,  43  in the both side end portions in the direction of length of the damping part  50 , are formed respectively in the shape of a curved surface protruding toward the outer periphery. Also the damping part  50  like this can be bent in the shape of a letter U as is the case with the first embodiment and can be attached to the double coil spring  30  to produce the same operation as in the first embodiment. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0060]     The third embodiment of the invention is a modification of the first embodiment and  FIG. 6  shows a state where a damping part  54  in accordance with the third embodiment is detached from the double coil spring  30 . Each of middle portions  55  in the direction of width in both end portions in the direction of length of the damping part  54  is protruded outside in the direction of length from the side end portions  42 ,  43  in the direction of width and is not pointed in the angular shape but formed in a flat surface. The slant surface portions  44 ,  45 , each of which is formed in the shape of a flat surface and connects the middle portion  55  in the direction of width to the side end portions  42 ,  43  in the direction of width, are formed in both end portions in the direction of length of the damping part  54 . In this manner, the damping part  54  is formed in an octagon when viewed from the direction of its thickness. Also the damping part  50  like this can be bent in the shape of a letter U as is the case with the first embodiment and can be attached to the double coil spring  30  to produce the same operation as in the first embodiment. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0061]     The fourth embodiment of the invention is a modification of the third embodiment and  FIG. 7  shows a state where a damping part  56  in accordance with the fourth embodiment is detached from the double coil spring  30 . Each of slant surface portions  57 ,  58 , which respectively connect the middle portion  55  in the direction of width to the side end portions  42 ,  43  in the both side end portions in the direction of length of the damping part  50 , are formed respectively in the shape of a curved surface protruding toward the outer periphery. Also the damping part  56  like this can be bent in the shape of a letter U as is the case with the first embodiment and can be attached to the double coil spring  30  to produce the same operation as in the first embodiment. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0062]     The fifth embodiment of the invention is a modification of the first embodiment and  FIG. 8  shows a state where a damping part  60  in accordance with the fifth embodiment is detached from the double coil spring  30 . The damping part  60  when viewed from the direction of its thickness is formed in the shape of a rhombus in which width decreases continuously from the center of the damping part  60  to both ends in the direction of length.  
         [0063]     When the damping part  60  like this is bent in the shape of a letter U as is the case with the first embodiment and is attached to the double coil spring  30 , there is provided a state shown in  FIG. 9 . To be specific, in each of two inserting portions  61  constructed of both end portions in the direction of length of the damping part  60 , a middle portion  41  in the direction of width is formed at an extreme tip pointed in an angular shape and side end portions  42 ,  43  in the direction of width are formed at the boundary between itself and a retaining portion  62  formed of the middle portion of the damping part  60 . With this, in each of the inserting portions  61 , the middle portion  41  in the direction of width is protruded toward the same one end of the double coil spring  30  as compared with the side end portions  42 ,  43  on both sides in the direction of width and slant surface portions  44 ,  45 , each formed in a flat surface, connect the middle portion  41  to the side end portions  42 ,  43 .  
         [0064]     As described above, in the state shown in  FIG. 9  where the double coil spring  30  is most elongated, the side end portion  42  of each inserting portion  61  is hard to enter a gap  38  between the windings of the outside coil  31 . This prevents the side end portion  42  of each inserting portion  61  from abutting against the outside coil  31  in the gap  38  between the windings when the double coil spring  30  is compressed and to prevent the side end portion  42  from detaching from the outside coil  31  to cause impact. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0065]     The sixth embodiment of the invention is a modification of the second embodiment and  FIG. 10  shows a state where a damping part  64  in accordance with the sixth embodiment is detached from the double coil spring  30 . The damping part  64  when viewed from the direction of its thickness is formed in the shape of a spindle in which width decreases continuously from the center of the damping part  64  to the both ends in the direction of length.  
         [0066]     When the damping part  64  like this is bent in the shape of a letter U as is the case with the first embodiment and is attached to the double coil spring  30 , there is provided a state shown in  FIG. 11 . To be specific, in each of two inserting portions  65  constructed of both end portions in the direction of length of the damping part  60 , a middle portion  41  in the direction of width is formed at an extreme tip pointed in an angular shape and side end portions  42 ,  43  in the direction of width are formed at the boundary between itself and a retaining portion  66  formed of the middle portion of the damping part  64 . With this, in each of the inserting portions  65 , the middle portion  41  in the direction of width is protruded toward the same one end of the double coil spring  30  as compared with the side end portions  42 ,  43  on both sides in the direction of width and slant surface portions  51 ,  52  each formed in the shape of a curved surface connect the middle portion  41  to the side end portions  42 ,  43 .  
         [0067]     As described above, in the state shown in  FIG. 11  where the double coil spring  30  is most elongated, the side end portion  42  of each inserting portion  65  is hard to enter a gap  38  between the windings of the outside coil  31 . This prevents the side end portion  42  of each inserting portion  65  from abutting against the outside coil  31  in the gap  38  between the windings when the double coil spring  30  is compressed and to prevent the side end portion  42  from detaching from the outside coil  31  to cause impact. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0068]     The seventh embodiment of the invention is a modification of the first embodiment and  FIG. 12  shows a state where a damping part  70  in accordance with the seventh embodiment is detached from the double coil spring  30 . In each of both end portions in the direction of length of the damping part  70 , the middle portion  41  in the direction of width is protruded not only outside in the direction of length but also in the direction of thickness as compared with the side end portions  42 ,  43  on both sides in the direction of width.  
         [0069]     When the damping part  70  like this is bent in the shape of a letter U as is the case with the first embodiment and is attached to the double coil spring  30 , there is provided a state shown in  FIG. 13 . To be specific, in each of two inserting portions  74  constructed of both end portions of the damping part  70 , the middle portion  41  in the direction of width is protruded toward the same one end of the double coil spring  30  and to the outside coil  31  as compared with both side end portions  42 ,  43  in the direction of width. Since the middle portion  41  is protruded to the outside coil  31  in this manner, in the state shown in  FIG. 13  where the double coil spring  30  is most elongated, the side end portion  42  of each inserting portion  74  is hard to enter the gap  38  between the windings of the outside coil  31 . With this, together with the same operation as in the first embodiment, it is possible to sufficiently prevent the side end portion  42  of each inserting portion  74  from abutting against the outside coil  31  in the gap  38  between the windings when the double coil spring  30  is compressed. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal with reliability.  
         [0070]     Here, the distinctive construction of the seventh embodiment described above may be applied to the second to sixth embodiments described above.  
         [0071]     The eighth embodiment of the invention is a modification of the seventh embodiment and  FIG. 14  shows a state where a damping part  80  in accordance with the eighth embodiment is detached from the double coil spring  30 . In the whole damping part  80  including both end portions in the direction of length, the middle portion  41  in the direction of width is protruded in the direction of thickness as compared with the side end portions  42 ,  43  on both sides in the direction of width but is not protruded outside in the direction of length.  
         [0072]     When the damping part  80  like this is bent in the shape of a letter U as is the case with the first embodiment and is attached to the double coil spring  30 , there is provided a state shown in  FIG. 15 . To be specific, in each of two inserting portions  84  constructed of both end portions of the damping part  80 , the middle portion  41  in the direction of width is protruded toward the outside coil  31  as compared with the side end portions  42 ,  43  in the direction of width. For this reason, in the state shown in  FIG. 15  where the double coil spring  30  is most elongated, the side end portion  42  of each inserting portion  84  is hard to enter the gap  38  between the windings of the outside coil  31 . With this, when the double coil spring  30  is compressed, it is possible to prevent the side end portion  42  of each inserting portion  84  from abutting against the outside coil  31  in the gap  38  between the windings and to prevent the side end portion  42  from detaching from the outside coil  31  after abutting to cause impact. Hence, it is possible to prevent the occurrence of abnormal noises and the deterioration of feeling of depressing the accelerator pedal.  
         [0073]     While the plurality of preferred embodiments of the invention have been described above, it should not be understood that the invention is limited to the plurality of preferred embodiments.  
         [0074]     For example, in the plurality of preferred embodiments is used one damping part of the type in which two inserting portions are connected to each other by the retaining portion. In contrast to this, it is also recommended to use two or more damping parts of the type in which two inserting portions are connected to each other by a retaining portion. Alternatively, it is also recommended to use a suitable number of damping parts of the type in which one inserting portion is connected to one retaining portion. Further, alternatively, it is also recommended to use a suitable number of damping parts having only an inserting portion, that is, damping parts that are not retained by the inside coil.  
         [0075]     Further, in the embodiments described above, the middle portion located in the center in the direction of width is protruded as a middle portion in the direction of width of the inserting portion as compared with the side end portions on both sides in the direction of width, but it is also recommended that a middle portion shifted from the center in the direction of width of the inserting portion be protruded. Further, in any case, it is also possible to protrude a middle portion (center portion) in the direction of width with respect to only one side end portion in the direction of width.  
         [0076]     Still further, in the plurality of embodiments described above, the double coil spring of a combination of two compression coil springs is used, but a double coil spring of a combination of two tension coil springs may be used. In any case, the outside coil and the inside coil may be wound in the same direction or in the opposite directions. Further, a suitable number of other coil springs may be further arranged inside the inside coil or outside the outside coil.  
         [0077]     In addition, in the plurality of embodiments described above, examples have been described in which the invention is applied to the accelerator for a vehicle. However, the invention can be applied to a publicly known pedal module provided with a pedal that is turned in the forward direction by the operation of depressing force and is turned in the reverse direction by the operation of restoring force of the double coil spring.