pedal device for vehicle having a friction damper

Abstract: A friction damper includes: a hollow cylindrical member (22) with a bottom (25); a movable member (23) disposed in said hollow cylindrical member in such a manner as to be movable in an axial direction of said hollow cylindrical member but immovable about an axis of said hollow cylindrical member; a coil spring (27) disposed between said movable member and the bottom of said hollow cylindrical member, one end (24) of said coil spring abutting against the bottom of said hollow cylindrical member and another end (26) thereof abutting against said movable member; a rotating member (28) disposed in said hollow cylindrical member in such a manner as to oppose said movable member and to be relatively rotatable about the axis of said hollow cylindrical member; and a frictionally-resisting-force generating mechanism (29) for generating a frictionally resisting force to the relative rotation of said rotating member with respect to said hollow cylindrical member, and for causing said movable member to move away from said rotating member in the axial direction against the resiliency of said coil spring and to approach the bottom of said hollow cylindrical member so as to increase the spring force of said coil spring, thereby increasing the frictionally resisting force.

Description: BACKGROUND OF THE INVENTION Field of the Invention: The present invention relates to a friction damper, and more particularly to a friction damper suitable for imparting an appropriate brake to an accelerator pedal, a brake pedal, a clutch pedal, or the like of a vehicle and a pedal device having the friction damper. Description of the Related Art: Pedal devices, including an accelerator pedal, a brake pedal, a clutch pedal, and the like of a vehicle, are each comprised of a pedal disposed at an upper-limit position at which the pedal can be pressed down as well as an urging means consisting of a coil spring for urging the pedal in a direction in which the pedal returns to its upper-limit position when the pedal was pressed down. In the case of the pedal device including an accelerator pedal, for example, as the accelerator pedal is pressed down, a throttle is opened or closed in the case of a gasoline engine, and a fuel injector is actuated in the case of a diesel engine. Conventionally, to open or close the throttle or actuate the fuel injector, the accelerator pedal and the throttle or the accelerator pedal and the fuel injector are linked together by an accelerator wire cable, and the accelerator pedal is adapted to pull the accelerator wire cable as it is pressed down. Accordingly, when the accelerator pedal is pressed down, a reaction force (resisting force) of a value in which the resilient reaction force of the coil spring and the tensile reaction force of the accelerator wire cable are added together is applied to the accelerator pedal. Meanwhile, fine control of fuel injection for the automotive engine is required for the purposes of low fuel consumption of vehicles and reduction of carbon dioxide, and electronic control of fuel injection such as the regulation of the throttle valve opening based on the pressing down of the accelerator pedal has been put to practical use. In vehicles in which fuel injection of the engine is effected by electronic control, the accelerator wire cable arranged between the accelerator pedal and the throttle valve is normally omitted. With the vehicles without the accelerator wire cables, however, the reaction force with respect to the pedal pressing force differs in comparison with vehicles with the accelerator wire cables, and if a general driver who is accustomed to driving a vehicle with the accelerator wire cable drives the vehicle without the accelerator wire cable, there is a possibility of excessively pressing down on the accelerator, thereby consuming fuel more than before. To obtain a large reaction force with respect to the pedal pressing force, if the spring force of a return spring for returning the pedal arm to the initial position of rotation is simply made large, there is a possibility of causing early fatigue to the pedal pressing foot due to the large reaction force from the return spring during constant traveling. As a countermeasure for overcoming this problem, an arrangement has been proposed in which the pedal arm is linked to one end of a dummy cable passed through a fixed helical pipe, the other end of the dummy cable being terminated via a coil spring, to ensure that a reaction force exhibiting a hysteresis characteristic with respect to the pedal pressing force, which is similar to the conventional case in which the accelerator wire cable is provided, can be obtained by the dummy cable. However, since this countermeasure using the dummy cable requires a relatively large space for installing the dummy cable, this countermeasure can be adopted only in vehicles of large vehicle types, such as trucks and RVs, in which there is sufficient leeway in space. In addition, since various factors are involved, the adjustment of reaction force by using the dummy cable is relatively difficult, and there is a possibility of increasing the cost in order to set the reaction force to a desired value. Furthermore, although, in order to obtain the hysteresis characteristic, a metallic dummy cable is allowed to slide within the inner surface of a resin sheathing of the pipe so as to produce sliding resistance between the metallic dummy cable and the inner surface of the resin sheathing of the pipe, there is a possibility that a large change in the characteristic can occur due to the wear caused by this sliding over a long period of use. The above-described problem occurs not only in the accelerator pedals, but can also occur in cases where appropriate rotational resistance is produced by using the above-described dummy cable or the like in brake pedals or clutch pedals, for example. SUMMARY OF THE INVENTION The present invention has been devised in view of the above-described circumstances, and it is an object of the present invention to provide a pedal device which makes it possible to simply set the hysteresis characteristic concerning the reaction force acting on the pedal to a desired value without using the accelerator wire cable and the dummy cable, as well as a friction damper suitable for use in the pedal device. Another object of the present invention is to provide a pedal device which is capable of obtaining an appropriate reaction force with respect to the pedal pressing force, is capable of being installed compactly in comparison with the dummy cable, makes it possible to effect very simply the adjustment of reaction force having a hysteresis characteristic, and exhibits a small change in the characteristic, as well as a friction damper suitable for use in the pedal device. US-A-5 295 409 shows a pedal device as described in the pre-characterising part of claim 1. US-A-1619035 shows a damper in a shock absorber which damper has certain features of the pre-characterising part of claim 1 hereto, which is directed to a pedal device. To attain the above objects, in accordance with a first aspect of the present invention, there is provided a pedal device for a vehicle, comprising: a pedal arm which is rotatably supported by a supporting frame: a first spring means for rotatively urging said pedal arm to an initial position of its rotation; and a damper for imparting a resisting force to the rotation of said pedal arm, said damper including; a hollow cylindrical member with a bottom and a hollow cylindrical portion; a movable member disposed in said hollow cylindrical member; a second spring means disposed between said movable member and the bottom of said hollow cylindrical member, one end of said second spring means abutting against the bottom of said hollow cylindrical member and another end thereof abutting against said movable member; a rotating member disposed in said hollow cylindrical member in such a manner as to oppose said movable member and to be rotatable about the axis of said hollow cylindrical member; and a frictionally-resisting-force generating means generating a frictionally resisting force as the resisting force to the relative rotation of said rotating member with respect to said hollow cylindrical member, characterised in that; said frictionally-resisting-force generating means causes said movable member to move away from said rotating member in an axial direction against the resiliency of said second spring means and to approach the bottom of said hollow cylindrical member so as to increase the spring force of said second spring means, thereby increasing the frictionally resisting force, the rotation of said pedal arm is transmitted as the relative rotation of said hollow cylindrical member and said rotating member, said hollow cylindrical portion of said hollow cylindrical member has on an inner peripheral surface thereof a groove extending in an axial direction of the hollow cylindrical member, and said movable member has a main body and a projection on an outer peripheral surface of said main body, said projection engaging in said groove with said hollow cylindrical portion in such a manner that said movable member is movable in said axial direction but immovable about an axis of said hollow cylindrical member. In accordance with the pedal device according to the invention, when the rotating member is relatively rotated with respect to the hollow cylindrical member due to the rotation of the pedal arm based on the pressing down of the pedal, an increasing frictionally resisting force is generated by the frictionally-resisting-force generating means. On the other hand, when the pressing down of the pedal is canceled and the rotating member is relatively reversely rotated with respect to the hollow cylindrical member, the frictionally resisting force in the frictionally-resisting-force generating means becomes small. Consequently, by virtue of the frictionally resisting force having this hysteresis characteristic, a resisting force similarly having the hysteresis characteristic is imparted to the rotation of the pedal arm. This resistance force makes it possible, for instance, to prevent the accelerator pedal from being excessively pressed down, which can otherwise consume fuel more than before. Preferably, the frictionally-resisting-force generating means has a projection formed integrally on one surface of the rotating member, opposing the movable member, in such a manner as to project in the axial direction toward one surface of the movable member and a projection formed integrally on the one surface of the movable member, opposing the rotating member, in such a manner as to project in the axial direction toward the one surface of the rotating member, the projections being arranged to come into planar contact with each other. With this feature, since the frictionally-resisting-force generating means is formed by projections which are disposed between the movable member and the rotating member and are formed integrally to the movable member and the rotating member, respectively, the pedal device can be made very compact, and can be installed by making effective use of a small space. Moreover, since the projections are brought into planar contact with each other, the coefficients.of friction at the contact surfaces can be set appropriately, thereby making it possible to determine a resisting force have a hysteresis characteristic which can be imparted to the rotation of the pedal arm, and making it possible to effect the adjustment of the reaction force very simply. Preferably also the frictionally-resisting-force generating means has an inclined surface formed on the one surface of the rotating member opposing the movable member, and an inclined surface formed on the one surface of the movable member opposing the rotating member and arranged to come into planar contact with the inclined surface formed on the one surface of the rotating member. With this feature, by appropriately setting the coefficients of friction at the inclined surface formed on the one surface of the rotating member and at the inclined surface formed on the one surface of the moveable member opposing the rotating member, it is possible to determine in the frictionally-resisting-force generating means the resisting force with the hysteresis characteristic which can be substantially imparted to the rotation of the pedal arm, so that the adjustment of the reaction force can be effected very simply. Preferably also, the frictionally-resisting-force generating means has a fixed surface which comes into planar contact with another surface of the rotating member, With this feature, since it is possible to determine the resisting force with the hysteresis characteristic which can be substantially imparted to the rotation of the pedal arm by appropriately setting the coefficients of friction at the other surface of the rotating member and the fixed surface, the adjustment of the reaction force can be effected very simply. It should be noted that, in such pedal device the other surface of the rotating member and the fixed surface which are brought into planar contact with each other may be formed by inclined surfaces in the same way as the pedal device in accordance with the previous preferred feature. Preferably also, the fixed surface is formed on the hollow cylindrical member. As a results, the pedal device can be formed more compactly. It goes without saying that the fixed surface may be formed on the supporting frame or the pedal arm, instead of being formed on the hollow cylindrical member. Preferably, the bottom of the hollow cylindrical member can be adjustably positioned in the axial direction. As a result, the initial resilient force generated by the second spring means, i.e., the initial resisting force, can be adjusted and set arbitrarily, so that an optimum initial resisting force can be obtained. Preferably, the second spring means has at least two coil springs arranged concentrically, and the at least two coil springs have mutually different moduli of elasticity. As the second spring means, a spring means using such as rubber or a leaf spring may be used. Preferably, if the second spring means is formed by at least one coil spring, the pedal device can be made to excel in durability and simple in the structure. In addition, if the second spring means is formed by at least two coil springs having mutually different moduli of elasticity as in the case of the pedal device in accordance with the seventh aspect, one coil spring can be used for fine adjustment, and the design and adjustment of the resisting force can be effected simply. Hence, such an arrangement is very preferable from this standpoint. In preferred embodiments the pedal arm is an accelerator pedal arm. In the pedal device for a vehicle in accordance with the present invention, an arrangement may be provided such that the rotation of the pedal arm is transmitted to either the hollow cylindrical member or the rotating member. Preferably, however, the rotation of the pedal arm is arranged to be transmitted to the rotating member, in which case, the hollow cylindrical member is fixedly supported by the frame. In the case where the rotation of the pedal arm is arranged to be transmitted to the hollow cylindrical member, the rotating member is fixedly supported by the frame. It should be noted that the pedal arm in the device of the present invention is preferably the aforementioned accelerator pedal arm, but the pedal arm is also applicable to a brake pedal arm, a clutch pedal arm, or the like. In accordance with the pedal device of the present invention, it is possible to obtain an appropriate reaction force with respect to the pedal pressing force, the pedal device can be installed compactly in comparison with the dummy cable, and the adjustment of reaction force having a hysteresis characteristic can be made very simply. In addition, in accordance with the pedal device of the present invention, the hysteresis characteristic can be simply set to a desired value without using a cable. BRIEF DESCRIPTION OF THE DRAWINGS Hereafter, a detailed description will be given of a friction damper and a pedal device having the friction damper in accordance with the present invention by citing embodiments in which the present invention is applied to an accelerator pedal device for a vehicle, particularly an automobile, illustrated in the drawings, wherein: Fig. 1 is a front cross-sectional view of a preferred embodiment of a pedal device for an automobile in accordance with the present invention; Fig. 2 is a left side view of the embodiment shown in Fig. 1; Fig. 3 is a detailed cross-sectional view of a damper of the embodiment shown in Fig. 1; Fig. 4 is a right side view of the damper shown in Fig. 3; Fig. 5 is a left side view of a movable member of the damper shown in Fig. 3; Fig. 6 is a cross-sectional view taken along line VI - VI of Fig. 5, in which projections, recesses, and stepped portions of a frictionally-resisting-force generating means are omitted; Fig. 7(a) is a right side view of the movable member of the damper shown in Fig. 3; Fig. 7(b) is an explanatory diagram in which the projections, the recesses, and the stepped portions of the frictionally-resisting-force generating means which is formed integrally with the movable member are illustrated in developed form; Fig. 8(a) is a left side view of a rotating member of the damper shown in Fig. 3; Fig. 8(b) is an explanatory diagram in which the projections, the recesses, and the stepped portions of the frictionally-resisting-force generating means which is formed integrally with the rotating member are illustrated in developed form; Fig. 9 is a right side view of the rotating member of the damper shown in Fig. 3; Fig. 10 is a cross-sectional view taken along line X - X of Fig. 9, in which projections, recesses, and stepped portions of the frictionally-resisting-force generating means are omitted; Fig. 11 is a diagram explaining the operation of the damper of the example shown in Figs. 1 and 3; Fig. 12 is a cross-sectional view of another preferred example of the damper of the present invention; Fig. 13 is a cross-sectional view of still another preferred example of the damper of the present invention; DESCRIPTION OF THE PREFERRED EMBODIMENTS In Figs. 1 to 10, a pedal device 1 for an automobile in accordance with an embodiment of the present invention is comprised of a supporting frame 2; a pedal arm, in this embodiment, an accelerator pedal arm 3 which is supported by the supporting frame 2 in such a manner as to be rotatable about an axis A in directions R; a spring means 4 for rotatively urging the accelerator pedal arm 3 toward an initial position of its rotation; a damper 5 serving as a resisting means for imparting a resisting force to the rotation in the R directions of the accelerator pedal arm 3 of an accelerator pedal 10, and a stopper (not shown) for stopping the rotation of the accelerator pedal arm 3 at the initial position of its rotation. In the pedal device 1, an accelerator wire cable for linking the accelerator pedal arm 3 and a throttle or linking the accelerator pedal arm 3 and a fuel injector is not used, and an actuator is connected at the location on the throttle or the fuel injector where the accelerator wire cable is conventionally connected. The arrangement provided is such that the displacement in the rotation of the accelerator pedal arm 3 is detected by an angle detector 9, which consists of a light projector 6, a light receiver 7, a disk 8 with slits formed in its periphery and rotatable with a rotating shaft 14, which will be described later, and the like, and the actuator connected at the location on the throttle or the fuel injector is driven via an electronic controller on the basis of a detection signal from the detector 9, whereby the throttle and the fuel injector are operated on the basis of the displacement in the rotation of the accelerator pedal arm 3. The supporting frame 2 at its bottom plate portion 13 is fixed to a vehicle body 11 by means of rivets or bolts 12 or the like, and rotatably supports the rotating shaft 14 at its both side walls 15 and 16. In the accelerator pedal 10 having a pedal 20 and the accelerator pedal arm 3 with the pedal 20 secured to a distal end thereof, the accelerator pedal arm 3 is secured to the rotating shaft 14 by means of welding or the like, and is supported by the supporting frame 2 via the rotating shaft 14 in such a manner as to be rotatable in the R directions. The spring means 4 in this embodiment is formed by a torsion coil spring 19 in which one end portion 17 thereof is engaged with the side wall 15 of the supporting frame 2, another end portion 18 thereof is passed through a hole 30, which is formed in the side wall 16, and is engaged with the accelerator pedal arm 3, and an intermediate coil portion thereof is wound around the rotating shaft 14 between both side walls 15 and 16 with gaps therebetween, thereby constantly resiliently urging the accelerator pedal arm 3 counterclockwise in Fig. 2 in the R direction. The damper 5 is comprised of a hollow cylindrical member 22 with a bottom fixed to the side wall 15 of the supporting frame 2 by means of bolts 21 or the like; a movable member 23 formed in the shape of an annular plate and disposed in the hollow cylindrical member 22 in such a manner as to be movable with respect to the hollow cylindrical member 22 in the direction of its axis A but immovable in directions about the axis A, i.e., in the directions R; a coil spring 27 serving as a spring means disposed between the movable member 23 and a bottom portion 25 of the hollow cylindrical member 22 and having one end 24 abutting against the bottom portion 25 of the hollow cylindrical member 22 and another end 26 abutting against the movable member 23; a rotating member 28 disposed in the hollow cylindrical member 22 in such a manner as to oppose the movable member 23 serving as a movable spring receiver and to be rotatable about the axis A in the R directions with respect to the hollow cylindrical member 22; and a frictionally-resisting-force generating means 29 which generates a frictionally resisting force as the aforementioned resisting force in the rotation in the R directions of the rotating member 28, causes the movable member 23 to move away from the rotating member 28 in the axial direction against the resiliency of the coil spring 27 and approach the bottom portion 25 of the hollow cylindrical member 22 so as to increase the spring force of the coil spring 27, thereby increasing the frictionally resisting force. The hollow cylindrical member 22 with a bottom in this embodiment has a hollow cylindrical portion 31, a collar portion 32 formed integrally with one end face of the hollow cylindrical portion 31; and a cover portion 36 serving as a fixed spring receiver which is threadedly engaged with an internally threaded portion 34 formed on an inner peripheral surface 33 of the hollow cylindrical portion 31 and is secured to the other end portion 35 of the hollow cylindrical portion 31. In addition to the threaded portion 34, the hollow cylindrical portion 31 has on its inner peripheral surface 33 at least one, in this embodiment six, grooves 41 (only two are shown) formed in such a manner as to extend in the direction of the axis A. The grooves 41 are arranged at equal angular intervals in the R direction. The collar portion 32 having a substantially elliptical outer shape has a through hole 42 in its center and through holes 43 and 44 at opposite end portions in its long-axis direction. The hollow cylidrical member 22 is fixedly supported at the collar portion 32 by the side wall 15 by means of bolts 21 or the like which are passed through the through holes 43 and 44. The collar portion 36 serving as the bottom portion 25 of the hollow cylindrical member 22 has an annular groove 46 at its end face 45, a hexagonal recess 48 in the center of its other end face 47, and an externally threaded portion 50 on its peripheral surface 49. One end 24 of the coil spring 27 is seated in the groove 46 of the cover portion 36, and the externally threaded portion 50 of the cover portion 36 is threadedly engaged with the internally threaded portion 34 by means of a rotating jig inserted in the recess 48, so that the cover portion 36 is tightened and secured to the other end portion 35 of the hollow cylindrical portion 31. As shown in detail in Figs. 5, 6, and 7, the movable member 23 includes a main body 56 formed in the shape of an annular plate and having a through hole 55 in its center; at least one, in this embodiment six, projections 58 formed integrally with an outer peripheral surface 57 of the main body 56; and an annular groove 60 formed in a face 59 facing one end face 45 of the cover portion 36. The projections 58 are arranged at equal angular intervals in the R direction, and are disposed in the grooves 41 in such a manner as to be movable in the direction of the axis A. As a result, the movable member 23 is movable in the direction of the axis A but immovable in the directions R. The other end 26 of the coil spring 27 is seated in the groove 60 of the main body 56. The coil spring 27 is disposed in the hollow cylindrical portion 31 concentrically therewith in such a manner as to be resiliently compressed so as to cause the movable member 23 to move away from the cover portion 36 in the direction of the axis A. As shown in detail particularly in Figs. 8, 9, and 10, the rotating member 28 has a hollow cylindrical portion 65 and an annular plate portion 67 formed integrally at one end side of an outer peripheral surface 66 of the hollow cylindrical portion 65. One end side of the hollow cylindrical portion 65 is disposed in the through hole 42, and is supported by an inner peripheral surface 64 of the collar portion 32, which defines the through hole 42, in such a manner as to be rotatable in the directions R. The other end side of the hollow cylindrical portion 65 is passed through the through hole 55, and extends in such a manner as to contact an inner peripheral surface 68 of the main body 56, which defines the through hole 55, and so as to be relatively slidable with respect to the inner peripheral surface 68 of the main body 56 in the direction of the axis A and in the R directions. A pair of mutually opposing flat surfaces 70 and 71 are formed in a central circular hole 69 of the hollow cylindrical portion 65, and one end portion of the rotating shaft 14 is fitted in the central circular hole 69 defined by the flat surfaces 70 and 71, whereby the rotation in the R directions of the pedal arm 3 is transmitted to the rotating member 28 via the rotating shaft 14. The frictionally-resisting-force generating means 29 is comprised of at least one, in this embodiment three, projections 84 formed integrally on an outer peripheral side of an annular surface 82 of the annular plate portion 67 of the rotating member 28, which faces an annular surface 81 of the main body 56 of the movable member 23, the projections 84 projecting toward the surface 81 of the movable member 23 in the direction of the axis A and each having an inclined surface 83; at least one, in this embodiment three, projections 86 formed integrally on an outer peripheral side of the surface 81 of the main body 56 of the movable member 23, which faces the surface 82 of the annular plate portion 67 of the rotating member 28, the projections 86 projecting toward the surface 82 of the rotating member 28 in the direction of the axis A and each having an inclined surface 85 in planar contact with the inclined surface 83; and a fixed surface 88 formed on the collar portion 32 of the hollow cylindrical member 22 in such a manner as to come into planar contact with an annular surface 87 of the annular plate portion 67 of the rotating member 28. The three projections 84 are arranged on the surface 82 at equal angular intervals in the R direction and are formed integrally on the annular plate portion 67, while the projections 86 are similarly arranged on the surface 81 at equal angular intervals in the R direction and are formed integrally on the main body 56. The inclined surfaces 83 and 85 are formed complementarily in such a manner as to come into planar contact with each other, preferably in such a manner as to be inclined about 45* with respect to the axis A. On the surface 81, recesses 91, into which distal ends in the direction of the axis A of the respective projections 84 are fitted, as well as stepped portions 92 defining the recesses 91, are formed continuously from the respective projections 86. Meanwhile, on the surface 82 as well, recesses 93, into which distal ends in the direction of the axis A of the respective projections 86 are fitted, as well as stepped portions 94 defining the recesses 93, are formed continuously from the respective projections 84. The position of initial planar contact between the inclined surface 83 and the inclined surface 85 is defined by the stepped portion 92 and the stepped portion 94. The fixed surface 88, in this embodiment, is formed by an annular surface of an annular portion 95 which projects radially inwardly of the collar portion 32. In the above-described pedal device 1, if the accelerator pedal 10 is pressed down, which in turn causes the accelerator pedal arm 3 to be rotated clockwise in the R direction in Fig. 2 against the resiliency of the coil spring 16, fuel injection for the engine is increased by the unillustrated electronic controller which received a detection signal from the detector 9 for detecting the rotational angle of the accelerator pedal arm 3, thereby accelerating the automobile. On the other hand, if the pressing of the accelerator pedal 10 is canceled, which in turn causes the accelerator pedal arm 3 to be rotated counterclockwise in the R direction in Fig. 2 by the resiliency of the coil spring 16, fuel injection for the engine is decreased by the unillustrated electronic controller, thereby decelerating the automobile. With the pedal device 1, if the rotating member 28 is rotated in the R direction through the rotating shaft 14 by the rotation of the accelerator pedal arm 3 due to the pressing of the pedal, the projections 84 are also rotated in the R direction, and the movable member 23, which is integrally provided with the projections 86 with their inclined surfaces 85 brought into planar contact with the inclined surfaces 83, is moved toward the bottom portion 25 against the resiliency of the coil spring 27 in the direction of the axis A owing to the rotation in the R direction of the projections 84, as shown in Fig. 11. On the other hand, if the pressing of the pedal is canceled, the accelerator pedal arm 3 is returned to its original position by the resiliency of the coil spring 16, and the movable member 23 is similarly returned to its original position, as shown in Fig. 1. With the pedal device 1, when the pedal is pressed down, an appropriate gradually increasing resisting force (reaction force) is imparted to the rotation of the accelerator pedal arm 3 based on the pressing of the pedal owing to the frictional resistance between the inclined surfaces 83 and the inclined surfaces 85 and the frictional resistance between the surface 87 and the fixed surface 88, which are pressed against each other by the gradually increasing resiliency of the coil spring 27. Thus, it is possible to avoid the excessive pressing of the accelerator pedal, which would consume fuel more than is necessary, and to avoid the risk of the occurrence of an accident due to out-of-control running. On the other hand, when the pressing of the pedal is canceled, the frictional resistance between the inclined surfaces 83 and the inclined surfaces 85, as well as the frictional resistance between the surface 87 and the fixed surface 88, become very small, and the accelerator pedal arm 3 is rotated and returned to its initial position at an early period with a small resisting force by the resiliency of the coil spring 16. According to the pedal device 1, since the resisting force which can be imparted to the rotation of the accelerator pedal arm 3 can be substantially determined by the frictional resistance between the inclined surfaces 83 and the inclined surfaces 85 as well as the frictional resistance between the surface 87 and the fixed surface 88, the adjustment of reaction force can be effected very simply. Further, by appropriately setting the respective values, the pedal device 1 can be made very compact, and can be installed by making effective use of a small space. According to the pedal device 1, since the bottom portion 25 of the hollow cylindrical member 22 is formed by the cover portion 36 which is threadedly engaged with the hollow cylindrical portion 31 in such a manner as to be capable of being adjustably positioned with respect to the direction of the axis A, the initial resiliency generated by the coil spring 27, i.e., the initial resisting force, can be arbitrarily adjusted and set, thereby making it possible to obtain an optimum initial resisting force. According to the pedal device 1, since the coil spring 27 produces practically no returning force for returning the accelerator pedal arm 3 to the initial position, virtually no reaction force is produced in the accelerator pedal arm 3 during the constant-speed traveling. Therefore, there is a further advantage in that the foot which presses on the pedal does not experience early fatigue. According to the pedal device 1, since the coil spring 27 is interposed between the movable member 23 and the bottom portion 25 of the hollow cylindrical member 22, which do not rotate relative to each other, the coil spring 27 is not twisted even when the rotating member 28 rotates, and such trouble as the faulty operation and the like due to the twisting of the coil spring 27 does not occur. In the pedal device 1, the hollow cylindrical member 22 may be fixed to the accelerator pedal arm 3, and the rotating member 28 may be secured to the supporting frame 2. Although, in the above-described pedal device 1, the bottom portion 25 of the hollow cylindrical member 22 is formed by the cover portion 36 which is separate from the hollow cylindrical portion 31, but the hollow cylindrical portion 31 and the cover portion 36 may be formed integrally as shown in Fig. 12, or an arrangement may be provided such that, as shown in Fig. 13, a threaded portion 104 formed on an inner peripheral surface 103 of the cover portion 36 is threadedly engaged with a threaded portion 102 formed on an outer peripheral surface 101 of the hollow cylindrical portion 31, and the cover portion 36 is secured to the hollow cylindrical portion 31 in such a manner as to be capable of being adjustably positioned with respect to the direction of the axis A. Although, in the above-described pedal device 1, the spring means interposed between the movable member 23 and the bottom portion 25 of the hollow cylindrical member 22 is formed by the single coil spring 27, the spring means may formed by at least two coil springs 111 and 112 which are arranged concentrically, as shown in Fig. 13, wherein, of these at least two coils springs 111 and 112, the modulus of elasticity of one coil spring-111 is made relatively large, while the modulus of elasticity of the other coil spring 112 is made relatively small, thereby varying their moduli of elasticity. A multiplicity of coil springs 112 having small but variously different moduli of elasticity are prepared in advance, and an appropriate one may be selected from among them, as required, so as to be used for the adjustment of the reaction force. In this case, the through hole 55 of the main body 56 of the movable member 23 may be omitted, and the hollow cylindrical portion 65 of the rotating member 28 may be formed to be short in the direction of the axis A so as not to penetrate the main body 56.

Claims: A pedal device for a vehicle, comprising: a pedal arm (3) which is rotatably supported by a supporting frame (2): a first spring means (4) for rotatively urging said pedal arm (3) to an initial position of its rotation; and a damper (5) for imparting a resisting force to the rotation of said pedal arm (3), said damper (5) including; a hollow cylindrical member (22) with a bottom (25) and a hollow cylindrical portion (31); a movable member (23) disposed in said hollow cylindrical member (22); a second spring means (27, 111, 112) disposed between said movable member (23) and the bottom (25) of said hollow cylindrical member (22), one end of said second spring means (27, 111, 112) abutting against the bottom (25) of said hollow cylindrical member (22) and another end thereof abutting against said movable member (23); a rotating member (28) disposed in said hollow cylindrical member (22) in such a manner as to oppose said movable member (23) and to be rotatable about the axis of said hollow cylindrical member (22); and a frictionally-resisting-force generating means (29) for generating a frictionally resisting force as the resisting force to the relative rotation of said rotating member (28) with respect to said hollow cylindrical member (22), characterised in that ; said frictionally-resisting-force generating means causes said movable member (23) to move away from said rotating member (28) in an axial direction against the resiliency of said second spring means (27) and to approach the bottom (25) of said hollow cylindrical member (22) so as to increase the spring force of said second spring means (27), thereby increasing the frictionally resisting force, the rotation of said pedal arm (3) is transmitted as the relative rotation of said hollow cylindrical member (22) and said rotating member (28), said hollow cylindrical portion (31) of said hollow cylindrical member (22) has on an inner peripheral surface (33) thereof a groove (41) extending in an axial direction of the hollow cylindrical member (22), and said movable member (23) has a main body (56) and a projection (58) on an outer peripheral surface (57) of said main body (56), said projection (58) engaging in said groove (41) with said hollow cylindrical portion (31) in such a manner that said movable member (23) is movable in said axial direction but immovable about an axis of said hollow cylindrical member (22). The pedal device for a vehicle according to claim 1, wherein said frictionally-resisting-force generating means (29) has a projection (84) formed integrally on one surface (82) of said rotating member (28), opposing said movable member (23), in such a manner as to project in the axial direction toward one surface (81) of said movable member (23) and a projection (86) formed integrally on the one surface (81) of said movable member (23), opposing said rotating member (28), in such a manner as to project in the axial direction toward the one surface (82) of said rotating member (28), said projections (84, 86) being arranged to come into planar contact with each other. The pedal device for a vehicle according to claim 1 or 2, wherein said frictionally-resisting-force generating means (29) has an inclined surface (83) on the one surface (82) of said rotating member (28) opposing said movable member (23), and an inclined surface (85) on the one surface (81) of said movable member (23) opposing said rotating member (28) and arranged to come into planar contact with said inclined surface (83) on the one surface (82) of said rotating member (28). The pedal device for a vehicle according to any one of claims 1 to 3, wherein said frictionally-resisting-force generating means (29) has a fixed surface (88) which comes into planar contact with a surface of said rotating member (28). The pedal device for a vehicle according to claim 4, wherein said fixed surface (88) is formed on said hollow cylindrical member (22). The pedal device for a vehicle according to any one of claims 1 to 5, wherein the bottom (25) of said hollow cylindrical member (22) can be adjustably positioned in the axial direction. The pedal device for a vehicle according to any one of claims 1 to 6, wherein said second spring means (27, 111, 112) has at least two coil springs (111, 112) arranged concentrically, and said at least two coil springs (111, 112) have mutually different moduli of elasticity. The pedal device for a vehicle according to any one of claims 1 to 7, wherein said pedal arm (3) is an accelerator pedal arm (3).

Inventors: IGARASHI YOSHITERU, KOJIMA MASAMITSU, IGARASHI, YOSHITERU, KOJIMA, MASAMITSU
Applicants: OILES INDUSTRY CO LTD, OILES CORPORATION
Application year: 1999
Main classification: F16F7
IPC codes: B60K26, F16F7, G05G5, G05G1