Electric vehicle and electric assistance device for vehicle

Abstract

The invention relates to an electric vehicle and an electric assist device for a vehicle. An electrically powered wheelchair (1) is provided with: a vehicle body (2) having trundles (2c) and main wheels (2b); a bracket (18) fixed to the vehicle body (2); an arm (20) which is supported by the bracket (18) so as to be capable of swinging in the vertical direction; a drive wheel (14) provided at the tip (21a) of the arm (20); an actuator (16) that drives the drive wheel (14); and an elastic member (58) that is provided between the bracket (18) and the arm (20) and that urges the arm (20) downward.

Description

Technical Field

[0001] The invention relates to an electric vehicle and an electric auxiliary device for a vehicle. Background Art

[0002] Patent Document 1 discloses an electric assist device for a wheelchair. The electric assist device includes: a main body including a battery, an electric motor, and a drive wheel; and a mounting rod. The electric motor drives the drive wheel. The mounting rod is a component for mounting the main body on the body of the wheelchair.

[0003] The position of the main body mounted on the vehicle body via the mounting rod can be switched to either a standby position or a drive position.

[0004] In the standby position, the drive wheels are lifted from the road surface, and in the drive position, the drive wheels are in contact with the road surface.

[0005] When in the driving position, the electric assist device assists the movement of the wheelchair by driving the drive wheels.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-150077

[0007] The wheelchair equipped with the above-mentioned conventional electric assist device travels with the main body fixed in the driving position. Therefore, the impact and vibration from the road surface are directly transmitted to the main body via the driving wheel. There is a concern that such impact and vibration may cause failure of the electric motor mounted on the main body, peripheral equipment for driving the driving wheel, etc.

[0008] Therefore, a technique of mounting the main body so as to be movable up and down and absorbing the vibration from the drive wheel has been considered.

[0009] However, in this case, the driving wheels are pressed against the road surface only by the deadweight of the main body, and the ground contact surface pressure of the driving wheels cannot be ensured, which may reduce traction and hinder stable driving. Summary of the invention

[0010] (1) An electric vehicle according to an embodiment comprises: a vehicle body having wheels; a bracket fixed to the vehicle body; an arm supported by the bracket so as to be able to swing in an up-and-down direction; a drive wheel provided at a front end portion of the arm; an actuator for driving the drive wheel; and an elastic member provided between the bracket and the arm for applying force to the arm downward.

[0011] (7) In addition, the present embodiment viewed from another point of view is a vehicle-use electric assist device mounted on a vehicle. The vehicle-use electric assist device comprises: a bracket fixed to the vehicle; an arm provided on the bracket so as to be swingable in the up-down direction; a drive wheel provided at the front end of the arm; an actuator driving the drive wheel; and an elastic member provided between the bracket and the arm and biasing the arm downward.

[0012] According to the present invention, vibration from the driving wheel can be damped and the ground contact surface pressure of the driving wheel can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a perspective view of the electric wheelchair according to the embodiment.

[0014] Figure 2 This is a diagram showing the main parts of the electric wheelchair when viewed from the rear.

[0015] Figure 3 yes Figure 1 Enlarged view of the main parts.

[0016] Figure 4 It is an enlarged perspective view showing the bracket and arm of the drive unit.

[0017] Figure 5 It is a cross-sectional view of the bracket and the arm.

[0018] Fig. 6A This is a diagram showing the relationship between the drive wheel and the main wheel when the position of the arm body is the lower swing position.

[0019] Figure 6B This is a diagram showing the relationship between the drive wheels and the main wheels in a state where the vehicle body is placed on a road surface.

[0020] Fig. 7A This diagram shows the force acting on the arm when the driving wheel is braked during travel of an electric wheelchair in which the straight line passing through the swing center of the arm and the rotation center of the driving wheel is not parallel to the road surface.

[0021] Figure 7B 1 is a diagram showing the force acting on the arm when the driving wheel is braked during travel of the electric wheelchair according to the present embodiment.

[0022] Figure 8 It is a diagram showing a bracket of a drive unit according to another embodiment. DETAILED DESCRIPTION

[0023] First, the contents of the implementation modes are listed and described.

[0024] [Overview of Embodiments]

[0025] (1) An electric vehicle according to an embodiment comprises: a vehicle body having wheels; a bracket fixed to the vehicle body; an arm supported by the bracket so as to be able to swing in an up-and-down direction; a drive wheel provided at a front end portion of the arm; an actuator for driving the drive wheel; and an elastic member provided between the bracket and the arm for applying force to the arm downward.

[0026] According to the above structure, the elastic member that urges the arm that can swing in the vertical direction downward can press the driving wheel against the road surface when the wheel is grounded. As a result, the vibration from the driving wheel can be alleviated and the ground contact surface pressure of the driving wheel can be increased.

[0027] (2) Here, when the electric vehicle is traveling in the direction from the rotation center of the driving wheel toward the swing center of the arm, if the driving wheel is braked, a pulling force in the direction opposite to the traveling direction may be applied to the front end of the arm through the driving wheel. When such a pulling force is applied to the arm through the driving wheel, a force in the direction of rotating the arm upward may be generated in the arm. If such a force is generated, the driving wheel may vibrate in the up-and-down direction while reducing the ground contact surface pressure of the driving wheel.

[0028] On the other hand, in the present embodiment, when the wheel and the drive wheel are in contact with the road surface, the straight line passing through the swing center of the arm and the rotation center of the drive wheel is configured to be parallel to the road surface.

[0029] Thus, even if a pulling force is applied to the arm by the driving wheel, it is possible to suppress generation of a force in a direction to rotate the arm upward.

[0030] As a result, it is possible to suppress a reduction in the ground contact surface pressure of the drive wheel and suppress vertical vibration generated in the drive wheel.

[0031] (3) In addition, the above-mentioned electric vehicle may further include a low-friction member interposed between the above-mentioned bracket and the above-mentioned arm.

[0032] In this case, even with a simple structure in which the arm and the bracket are clamped by fastening members such as bolts and nuts, the friction between the arm and the bracket can be appropriately reduced, and the arm can be swingably provided on the bracket.

[0033] In addition, by clamping the arm and the bracket with the low friction member, a moderate friction force can be applied between the arm and the bracket, and even if a force is generated in the direction of rotating the arm upward, the force can be suppressed. In addition, vibration of the arm and the drive wheel caused by the friction force between the arm and the bracket can be suppressed.

[0034] (4) In the electric vehicle, the bracket preferably includes a support member including a support shaft that supports the arm so as to be swingable, and the low friction member includes a low friction washer that is provided on the outer peripheral side of the support shaft and interposed between the arm and the support member.

[0035] (5) In addition, in the above-mentioned electric vehicle, the above-mentioned arm may also have a protrusion protruding along the long side direction of the above-mentioned arm on the base end side of the above-mentioned arm, and the above-mentioned bracket may also have: an upper wall portion arranged above the above-mentioned protrusion and abutted by the above-mentioned protrusion through the swing of the above-mentioned arm, and a lower wall portion arranged below the above-mentioned protrusion and abutted by the above-mentioned protrusion through the swing of the above-mentioned arm.

[0036] In this case, the swing range of the protrusion can be limited by the upper wall and the lower wall. Thus, the swing range of the arm can be limited. As a result, the arm can be prevented from swinging beyond a desired range.

[0037] (6) In the above-mentioned electric vehicle, the above-mentioned vehicle body may include a wheelchair.

[0038] (7) In addition, the present embodiment viewed from another point of view is a vehicle-use electric assist device mounted on a vehicle. The vehicle-use electric assist device comprises: a bracket fixed to the vehicle; an arm provided on the bracket so as to be swingable in the up-down direction; a drive wheel provided at the front end of the arm; an actuator driving the drive wheel; and an elastic member provided between the bracket and the arm and biasing the arm downward.

[0039] According to the above structure, since there is an elastic member that applies force to the arm downward, the bracket can be fixed to the vehicle body in a manner that the drive wheel is pressed against the road surface when the vehicle wheel is grounded. As a result, the drive wheel is pressed against the road surface through the elastic member. As a result, the vibration from the drive wheel can be mitigated and the ground contact surface pressure of the drive wheel can be increased.

[0040] (8) In the above-mentioned vehicle electric assist device, the above-mentioned bracket preferably comprises: a main body portion on which the above-mentioned arm is set; and a fixing portion which fixes the above-mentioned main body portion at a specified height position of the above-mentioned vehicle, and the above-mentioned specified height position is a position where a straight line passing through the swing center of the above-mentioned arm and the rotation center of the above-mentioned drive wheel is parallel to the above-mentioned road surface when the wheel of the above-mentioned vehicle electric assist device installed and the above-mentioned drive wheel are in contact with the road surface.

[0041] In this case, it is possible to suppress a decrease in the ground contact surface pressure of the drive wheel and suppress vertical vibration generated in the drive wheel.

[0042] (9) In the above-mentioned vehicle electric assist device, the bracket may include: a main body on which the arm is mounted; and a fixing portion capable of adjusting a height position of the main body of the vehicle.

[0043] In this case, the height position of the main body can be adjusted in such a manner that when the wheel of the vehicle on which the vehicle electric assist device is installed and the drive wheel are in contact with the road surface, a straight line passing through the swing center of the arm and the rotation center of the drive wheel is parallel to the road surface.

[0044] As a result, it is possible to suppress a reduction in the ground contact surface pressure of the drive wheel and suppress vertical vibration generated in the drive wheel.

[0045] [Details of implementation method]

[0046] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings.

[0047] [About the overall structure]

[0048] Figure 1 : is a perspective view of an electric wheelchair according to an embodiment. Figure 2 This is a diagram showing the main parts of an electric wheelchair when viewed from the rear.

[0049] This electric wheelchair 1 has a function of driving the driving wheels of the electric wheelchair 1 when pressed from behind by an operator, and assisting (assisting) the operator.

[0050] The electric wheelchair 1 is an electric vehicle including a vehicle body 2 and a vehicle electric assist device 4 .

[0051] The vehicle body 2 is a general wheelchair, and includes a frame 2a mainly composed of a metal pipe, a pair of main wheels 2b, and a pair of casters 2c.

[0052] The frame 2a includes a pair of rear tubes 2a1, a pair of front tubes 2a2, a pair of upper tubes 2a3, and a pair of down tubes 2a4.

[0053] The pair of rear pipes 2a1 extend in the up-down direction. The pair of rear pipes 2a1 are arranged in parallel with a constant interval in the left-right direction.

[0054] The pair of down tubes 2a4 are connected to the lower ends of the pair of rear tubes 2a1.

[0055] The pair of upper tubes 2a3 are connected to the pair of rear tubes 2a1. In the pair of rear tubes 2a1, the portion where the pair of upper tubes 2a3 are connected is located above the lower end.

[0056] The pair of upper tubes 2a3 and the pair of lower tubes 2a4 extend in the front-rear direction. The pair of upper tubes 2a3 and the pair of lower tubes 2a4 are arranged substantially parallel to each other at a constant interval in the left-right direction.

[0057] The portion of the pair of lower tubes 2a4 that is further rearward than the rear tube 2a1 is a dump lever 2t. The dump lever 2t is a member that is stepped on by the operator's foot. When the operator steps on the dump lever 2t, the caster 2c is lifted upward with the main wheel 2b as a fulcrum.

[0058] The pair of front tubes 2a2 extend in the up-down direction. The pair of front tubes 2a2 connects the front ends of the pair of upper tubes 2a3 and the front ends of the pair of lower tubes 2a4. Therefore, the pair of front tubes 2a2 are shorter than the pair of rear tubes 2a1.

[0059] A pair of casters 2c are provided at the lower end of the front tube 2a2. A pair of main wheels 2b are provided at the lower end of the rear tube 2a1.

[0060] A pair of main wheels 2b is arranged behind a pair of casters 2c. The pair of main wheels 2b are rear wheels. In addition, a pair of casters 2c are front wheels.

[0061] The vehicle body 2 further includes a seat 2d on which a passenger sits, and a backrest 2e. The seat 2d is fixed to a pair of upper tubes 2a3. The backrest 2e is fixed to a pair of rear tubes 2a1.

[0062] The electric wheelchair 1 is constructed by attaching the vehicle electric assist device 4 to a vehicle body 2 that can be used as a wheelchair.

[0063] In the following description, the direction in which the front of the passenger faces when the passenger sits on the electric wheelchair 1 (the direction in which the backrest portion 2e faces the front) is referred to as the front, and the opposite direction is referred to as the rear. Therefore, the passenger sits facing the front of the electric wheelchair 1. In addition, the direction facing the left side as viewed from the passenger is referred to as the left, and the direction facing the right side as viewed from the passenger is referred to as the right.

[0064] The vehicle electric assist device 4 includes a pair of drive units 8 and a pair of operation units 10 .

[0065] like Figure 1 As shown in FIG. 1 , a pair of protrusions 2a5 are provided at the upper ends of the pair of rear pipes 2a1. The pair of protrusions 2a5 protrude further rearward than the backrest portion 2e.

[0066] The pair of operation parts 10 are provided on the pair of protruding parts 2a5. Therefore, the pair of operation parts 10 are arranged on the upper left and right sides of the backrest part 2e.

[0067] The pair of operation parts 10 each has a handle 12 .

[0068] The handle 12 is movable in the front-rear direction relative to the protruding portion 2a5.

[0069] The operation unit 10 further includes a potentiometer (not shown). The potentiometer detects the displacement amount of the handle 12 in the front-rear direction. The operation unit 10 provides an output indicating the displacement amount of the handle 12 to a control device (described later).

[0070] The pair of drive units 8 is fixed to the left and right of the frame 2a. The pair of drive units 8 is arranged on the vehicle inner side of the pair of main wheels 2b.

[0071] The pair of drive units 8 includes a drive wheel 14 and an actuator 16 , respectively.

[0072] The actuator 16 drives the drive wheel 14 . The actuator 16 is a hub motor and is provided inside the drive wheel 14 .

[0073] The driving unit 8 will be described in detail later.

[0074] The vehicle electric assist device 4 further includes a battery, a control box (not shown) that accommodates a control device for controlling various parts, and the like.

[0075] The battery stores electric power to be supplied to the pair of drive units 8 (actuator 16 ) and various parts.

[0076] The control device has a function of controlling the pair of actuators 16 based on the outputs provided from the pair of operating parts 10. As described above, the outputs from the pair of operating parts 10 indicate the displacement amounts of the pair of handles 12.

[0077] The control device controls the pair of actuators 16 based on the displacement amounts of the pair of handles 12 so as to maintain the relative positions of the handles 12 and the frame 2 a (the vehicle body 2 ).

[0078] The control device can cause the actuator 16 to drive the drive wheels 14 to accelerate the vehicle body 2 and maintain the speed. In addition, the control device can cause the actuator 16 to brake the drive wheels 14 by regenerative braking, short-circuit braking, etc. to decelerate the vehicle body 2.

[0079] For example, if the operator pushes the handle 12 forward, the handle 12 is displaced forward. The control device moves the vehicle body 2 forward based on the output of the pair of operation parts 10 so that the position of the handle 12 returns to the original position. On the contrary, if the operator pulls the handle 12 backward, the handle 12 is displaced backward. The control device moves the vehicle body 2 backward so that the position of the handle 12 returns to the original position.

[0080] In this way, the control device adjusts the amount of movement of the actuator 16 according to the operator's pushing and pulling of the handle 12. Thus, the control device controls the pair of actuators 16 so that the relative position of the handle 12 and the vehicle body 2 is maintained.

[0081] [About the structure of the drive unit]

[0082] Figure 3 yes Figure 1 A magnified view of the main parts. Figure 3 In the figure, for easy understanding, the main wheel 2 b on the right side and the drive wheel 14 and the actuator 16 on the left side are omitted.

[0083] The driving unit 8 further includes a bracket 18 and an arm 20 .

[0084] The bracket 18 is a plate-shaped member and is fixed to the down tube 2a4 and the rear tube 2a1.

[0085] The arm 20 is supported by the bracket 18 so as to be swingable in the up-down direction.

[0086] The arm 20 includes an arm body 21 and a protrusion 22 provided integrally with the arm body 21 .

[0087] A notch portion 21 a 1 is provided at the front end portion 21 a of the arm body 21 .

[0088] The axle 14 a extending from the driving wheel 14 is fixed to the cutout portion 21 a 1 . Thus, the driving wheel 14 and the actuator 16 are provided at the front end portion 21 a of the arm body 21 .

[0089] Thus, when the arm body 21 swings in the up-down direction, the drive wheel 14 and the actuator 16 move in the up-down direction.

[0090] The actuator 16 includes a rotor (not shown) which can rotate integrally with the drive wheel 14. In addition, the actuator 16 includes a stator (not shown) which is fixed to the arm 20. Thus, the actuator 16 drives the drive wheel 14 to rotate.

[0091] Figure 4 It is an enlarged perspective view showing the bracket 18 and the arm 20 of the driving unit 8 .

[0092] exist Figure 4 , the bracket 18 and the arm 20 of the left drive unit 8 are shown. The left and right drive units 8 have the same structure. Therefore, the left drive unit 8 will be described here.

[0093] The bracket 18 includes a main body 24 and a fixing portion 26. The main body 24 is provided with an arm 20.

[0094] The fixing portion 26 is provided on the upper side of the main body 24. The fixing portion 26 fixes the main body 24 at a predetermined height position of the vehicle body 2.

[0095] The fixing portion 26 includes a front fixing portion 28 and a rear fixing portion 30 .

[0096] The front fixing portion 28 has a rectangular plate-shaped portion 28a connected to the main body portion 24, and a semi-cylindrical member 28b. One end of the semi-cylindrical member 28b is inserted into a slit 28c provided in the plate-shaped portion 28a and fixed to the plate-shaped portion 28a. The other end of the semi-cylindrical member 28b is fixed to the plate-shaped portion 28a by a bolt 28d. The lower tube 2a4 passes between the plate-shaped portion 28a and the semi-cylindrical member 28b (see Figure 3 The lower tube 2a4 is sandwiched between the plate-shaped portion 28a and the semi-cylindrical member 28b. Thus, the front fixing portion 28 is fixed to the lower tube 2a4.

[0097] The rear fixing portion 30 includes a protruding portion 30 a protruding from the edge of the main body portion 24 toward the vehicle inner side, and a pillar portion 30 b extending upward from the front end of the protruding portion 30 a .

[0098] The upper surface of the protrusion 30a contacts the lower tube 2a4 (see Figure 3 ).

[0099] A notch 30b1 is provided at the front end of the column 30b. The threaded portion 3a protruding from the hub 3 of the main wheel 2b fixed to the rear pipe 2a1 is fixed to the notch 30b1 (see Figure 3 The column portion 30b is clamped between the hub 3 and the nut 3b screwed with the threaded portion 3a. Thus, the rear fixing portion 30 is fixed to the rear pipe 2a1.

[0100] The fixing portion 26 is fixed to the down tube 2a4 and the rear tube 2a1. Thus, the fixing portion 26 fixes the main body 24 to the frame 2a.

[0101] like Figure 4 As shown in FIG. 1 , the arm body 21 of the arm 20 provided in the body portion 24 swings around the central axis C1 . That is, the central axis C1 is the swing center of the arm body 21 .

[0102] Figure 5 It is a cross-sectional view of the bracket 18 and the arm 20 . Figure 5 A cross section along the vertical direction including the central axis C1 is shown.

[0103] like Figure 5 As shown, the bracket 18 further includes a support member 34. The support member 34 is a member that supports the arm 20 so as to be swingable.

[0104] The support member 34 includes a support shaft 36 , a spacer 38 , a washer 44 , and a nut 42 .

[0105] The support member 34 is fixed to a support hole 24a provided in the main body 24. The support hole 24a is a hole centered on the central axis C1.

[0106] The support shaft 36 includes a shaft portion 36a, a head portion 36b, and a threaded portion 36c. The head portion 36b is provided at one end of the shaft portion 36a. The threaded portion 36c is provided at the other end of the shaft portion 36a. The nut 42 is screwed into the threaded portion 36c.

[0107] The support member 34 is configured by arranging a spacer 38 and a washer 44 on the outer peripheral side of the support shaft 36 in addition to the arm 20 .

[0108] In addition, a pair of low friction washers 40 are assembled to the support member 34 . The pair of low friction washers 40 are arranged on both sides of the arm 20 .

[0109] On the outer peripheral side of the support shaft 36 , a washer 44 , a low friction washer 40 , an arm 20 , a low friction washer 40 , a spacer 38 , and a main body 24 are arranged in this order from the head portion 36 b toward the threaded portion 36 c .

[0110] The washer 44 is a member for preventing various components from falling off the support shaft 36 .

[0111] The spacer 38 is a cylindrical member. The shaft portion 36a is inserted into the inner peripheral side of the spacer 38. The spacer 38 is a member for ensuring a gap between the main body portion 24 and the arm 20.

[0112] A hole portion 21b1 is provided on the base end portion 21b side of the arm body 21. The shaft portion 36a is inserted into the hole portion 21b1. A sliding bearing 46 is interposed between the hole portion 21b1 and the shaft portion 36a.

[0113] The pair of low friction washers 40 are washers with low friction coefficients on the surface and the inner surface.

[0114] The low friction washer 40 is sandwiched between the arm 20 and the spacer 38 and between the arm 20 and the washer 44 .

[0115] Examples of the low-friction washer 40 include a general washer in which the surface and the back surface are coated with a low-friction material such as fluororesin that reduces the friction coefficient, and a washer formed of a low-friction material.

[0116] In addition, a spring washer or a wave washer can also be used as the low friction washer 40. The spring washer or the wave washer can appropriately reduce the friction coefficient by reducing the contact area with the member that contacts itself.

[0117] The washer 44 , the low friction washer 40 , the arm 20 , the low friction washer 40 , the spacer 38 , and the body portion 24 are fastened between the head portion 36 b and the nut 42 .

[0118] That is, the arm 20 , the main body 24 , and other members are clamped by the support shaft 36 and the nut 42 serving as fastening members.

[0119] Since the arm 20 is disposed between the pair of low-friction washers 40 , the frictional force between the arm 20 and the support member 34 can be appropriately reduced.

[0120] That is, even with a simple structure in which the arm 20 and the main body 24 are clamped by a fastening member as in this embodiment, the friction between the arm 20 and the support member 34 can be appropriately reduced, and the arm 20 can be swingably set on the support member 34 (bracket 18).

[0121] like Figure 4 as well as Figure 5 As shown, the protrusion 22 of the arm 20 is provided on the base end portion 21 b side of the arm body 21 .

[0122] The protrusion 22 has a radial portion 50 and a longitudinal portion 52 .

[0123] The radial portion 50 protrudes from the side surface 21c of the arm body 21. The radial portion 50 extends in a radial direction perpendicular to the central axis C1. In addition, the radial portion 50 extends from the base end portion 21b in a direction intersecting the longitudinal direction of the arm body 21.

[0124] The longitudinal portion 52 extends from the side surface 50a of the radial portion 50. The longitudinal portion 52 extends in a direction opposite to the direction in which the arm body 21 extends. The longitudinal portion 52 extends substantially parallel to the longitudinal direction of the arm body 21.

[0125] like Figure 4 As shown, the bracket 18 has a bent portion 54 protruding toward the vehicle inner side along the side edge of the main body 24. The bent portion 54 has a recessed portion 55. The recessed portion 55 is formed by cutting the edge of the bent portion 54. The recessed portion 55 has an upper wall portion 55a and a lower wall portion 55b. The upper wall portion 55a and the lower wall portion 55b are opposed to each other.

[0126] The longitudinal portion 52 is inserted into the recess 55. Therefore, the upper wall portion 55a is provided above the longitudinal portion 52. The lower wall portion 55b is provided below the longitudinal portion 52.

[0127] In addition, the longitudinal direction portion 52 (protrusion 22) is provided integrally with the arm main body 21. Therefore, the longitudinal direction portion 52 swings together with the swing of the arm main body 21.

[0128] When the arm body 21 swings downward at a predetermined angle, the longitudinal direction portion 52 swings upward and comes into contact with the upper wall portion 55a. In this case, further upward swinging of the longitudinal direction portion 52 is restricted.

[0129] When the arm body 21 swings upward at a predetermined angle, the longitudinal portion 52 swings downward and contacts the lower wall portion 55b. In this case, further downward swinging of the longitudinal portion 52 is restricted.

[0130] Thus, the swing range of the longitudinal portion 52 (protrusion 22) is limited by the upper wall portion 55a and the lower wall portion 55b. Thus, the swing range of the arm 20 (arm body 21) can be limited. As a result, the arm body 21 can be prevented from swinging beyond the required range.

[0131] That is, the swing range of the arm body 21 is limited to the range from the position of the arm body 21 where the longitudinal portion 52 abuts against the upper wall portion 55 a to the position of the arm body 21 where the longitudinal portion 52 abuts against the lower wall portion 55 b .

[0132] In the following description, the position of the arm body 21 where the longitudinal portion 52 and the upper wall portion 55a abut is referred to as a lower swing position, and the position of the arm body 21 where the longitudinal portion 52 and the lower wall portion 55b abut is referred to as an upper swing position.

[0133] like Figure 4 As shown, the drive unit 8 further includes an elastic member 58 .

[0134] The elastic member 58 is provided between the bracket 18 and the arm 20. The elastic member 58 urges the arm 20 (arm body 21) downward.

[0135] The elastic member 58 is, for example, a tension coil spring.

[0136] An L-shaped spring hook portion 24 b is provided at the rear end of the main body portion 24 .

[0137] In addition, a spring hook bolt 60 is provided in the radial portion 50 of the protrusion 22. The spring hook bolt 60 is inserted into the hole portion 50b (see Figure 5 ). The spring hook bolt 60 is screwed together with the nut 62 to fasten the radial portion 50 . Thus, the spring hook bolt 60 is fixed to the radial portion 50 .

[0138] One end of the elastic member 58 is pulled and hung on the spring hook portion 24 b , and the other end of the elastic member 58 is hung on the groove portion 60 a at the front end of the spring hook bolt 60 .

[0139] In a state where the longitudinal direction portion 52 is in contact with the upper wall portion 55 a , the elastic member 58 applies a tensile force between the spring hook portion 24 b and the spring hook bolt 60 .

[0140] Thus, in a state where no force is applied to swing the arm body 21 upward, the arm body 21 is positioned at the lower swing position.

[0141] When the arm body 21 is at the lower swing position, the elastic member 58 applies a tensile force between the spring hook portion 24 b and the spring hook bolt 60 .

[0142] Thus, when the position of the arm main body 21 is between the lower swing position and the upper swing position, the elastic member 58 urges the arm 20 (arm main body 21 ) downward.

[0143] Fig. 6A This is a diagram showing the relationship between the drive wheel 14 and the main wheel 2b when the position of the arm body 21 is the lower swing position.

[0144] like Fig. 6A As shown, when the main wheels 2b and the driving wheels 14 of the vehicle body 2 are not in contact with the road surface R, no force from the road surface R acts on the arm body 21. Therefore, the position of the arm body 21 is the lower swing position.

[0145] When the position of the arm body 21 is the lower swing position, the lowest portion of the drive wheel 14 is located below the lowest portion of the main wheel 2b.

[0146] Figure 6B 1 and 2 , which are diagrams showing the relationship between the drive wheels 14 and the main wheels 2 b in a state where the vehicle body 2 is placed on the road surface R. FIG.

[0147] In this case, the caster 2c, the main wheel 2b, and the driving wheel 14 are in contact with the road surface R. Therefore, the position of the arm body 21 is between the lower swing position and the upper swing position.

[0148] At this time, the elastic member 58 urges the arm body 21 that can swing in the vertical direction downward, so the driving wheel 14 is pressed against the road surface R by the tensile force of the elastic member 58. As a result, the vibration transmitted from the driving wheel 14 to the vehicle body 2 can be mitigated, and the ground contact surface pressure of the driving wheel 14 can be increased.

[0149] In this embodiment, when the caster 2c, the main wheel 2b and the driving wheel 14 are in contact with the road surface R, the straight line L is parallel to the road surface R. The straight line L passes through the central axis C1 which is the swing center of the arm body 21 and the rotation center C2 of the driving wheel 14.

[0150] In the present embodiment, "the straight line L is parallel to the road surface R" includes not only the case where the straight line L is parallel to the road surface R, but also the case where the straight line L is substantially parallel to the road surface R. "The straight line L is parallel to the road surface R" means that the acute angle θ formed by the straight line along the road surface R and the straight line L is greater than 0 degrees and less than 8 degrees.

[0151] In the present embodiment, the position of the arm body 21 where the straight line L is substantially parallel to the road surface R is included between the lower swing position and the upper swing position.

[0152] Here, a case where the driving wheels are braked while the electric wheelchair is moving forward when the straight line L is not parallel to the road surface R will be described.

[0153] Fig. 7A 1 is a diagram showing the force acting on the arm when the electric wheelchair, in which the straight line L is not parallel to the road surface R, applies brakes to the driving wheel 114 during travel.

[0154] exist Fig. 7A , a state in which the electric wheelchair travels in a direction (forward) from the rotation center C2 of the driving wheel 114 toward the central axis C1 of the arm 120 is shown.

[0155] In this case, since braking (regenerative braking or short-circuit braking) is applied to the driving wheel 114, a force F1 pulling in the direction opposite to the traveling direction is applied to the front end portion 120A of the arm 120 through the driving wheel 114. At this time, since the straight line L is not parallel to the road surface R, the arm 120 tends to generate a force F2 in a direction to rotate the arm 120 upward.

[0156] When the arm 120 generates such a force F2, the ground contact surface pressure of the driving wheel 114 tends to be reduced, and on this basis, the driving wheel 114 is vibrated in the up-and-down direction.

[0157] Figure 7B This is a diagram showing the force acting on the arm when the driving wheel is braked during travel of the electric wheelchair according to the present embodiment.

[0158] like Figure 7B As shown, when the straight line L is parallel to the road surface R, even if a pulling force acts on the arm 20 by the drive wheel 14, generation of a force in a direction to rotate the arm 20 upward can be suppressed.

[0159] As a result, it is possible to suppress a reduction in the ground contact surface pressure of the drive wheel 14 and suppress vertical vibration generated in the drive wheel.

[0160] In addition, in this embodiment, by interposing and clamping the low friction washer 40 between the arm 20 and the support member 34 (bracket 18), an appropriate friction force can be applied between the arm 20 and the support member 34, and even if a force is generated in a direction to rotate the arm 20 upward, the force can be suppressed. In addition, the friction force between the arm 20 and the support member 34 can suppress vibrations generated in the arm 20 and the drive wheel 14.

[0161] [Regarding other implementation methods]

[0162] Figure 8 It is a diagram showing a bracket 18 of a drive unit 8 according to another embodiment.

[0163] This embodiment is different from the above-described embodiment in that the notch portion 30b1 provided in the column portion 30b is provided longer in the height direction and that a plurality of slits 28c and bolt holes 28b1 are arranged in the height direction.

[0164] The fixing portion 26 of the present embodiment has the above-described structure, and thus can adjust the height position of the main body 24 in the vehicle main body 2 .

[0165] Thereby, the height position of the main body 24 can be adjusted so that the straight line L becomes parallel to the road surface.

[0166] As a result, it is possible to suppress a reduction in the ground contact surface pressure of the drive wheel 14 and suppress vertical vibrations generated in the drive wheel 14 .

[0167] 〔other〕

[0168] The embodiments disclosed this time are illustrative and non-restrictive in all aspects.

[0169] In the above embodiment, the case where the tension coil spring is used as the elastic member 58 is exemplified, but an annular rubber or the like may be used instead of the tension coil spring.

[0170] In addition, in the above embodiment, although the case where the position of the arm body 21 where the straight line L is substantially parallel to the road surface R is included between the lower swing position and the upper swing position is illustrated, the lower swing position and the upper swing position may be included within the range of the position of the arm body 21 where the straight line L is substantially parallel to the road surface R.

[0171] In this case, the swing range of the arm body 21 can be limited to a range in which the straight line L and the road surface R are substantially parallel.

[0172] In the above embodiment, the vehicle body 2 having the front and rear wheels (casters 2c and main wheels 2b) is exemplified, but the vehicle body 2 may be configured to have at least one of the front and rear wheels.

[0173] In the above embodiment, the vehicle main body 2 is a general wheelchair and the vehicle electric assist device 4 is mounted thereon. However, the vehicle main body 2 alone may be a cart, a truck, or the like other than a wheelchair.

[0174] The protection scope of the present invention is not limited to the above-mentioned embodiments, but includes all changes within the scope equivalent to the structure described in the technical solution.

[0175] Description of Reference Numerals

[0176] 2… Vehicle body

[0177] 4…Electric auxiliary device for vehicle

[0178] 14…Drive wheel

[0179] 16…Actuator

[0180] 18…Bracket

[0181] 20…arm

[0182] 21a…Front end

[0183] 21b…base end

[0184] 22…Protrusion

[0185] 24…Main body

[0186] 26…Fixed part

[0187] 34…Supporting parts

[0188] 36…Support shaft

[0189] 40...Low friction washer (low friction component)

[0190] 55a…upper wall

[0191] 55b…lower wall

[0192] 58…elastic component.

Claims

1. An electric vehicle comprising: a vehicle body having wheels; a bracket fixed to the vehicle body; an arm supported by the bracket so as to be able to swing in an up-and-down direction; a driving wheel disposed at the front end of the arm; an actuator that drives the drive wheel; and The elastic member is provided between the bracket and the arm and biases the arm downward.

2. The electric vehicle according to claim 1, wherein: When the wheel and the drive wheel are in contact with a road surface, a straight line passing through a swing center of the arm and a rotation center of the drive wheel is parallel to the road surface.

3. The electric vehicle according to claim 2, wherein: Also available: The low friction member is sandwiched between the bracket and the arm.

4. The electric vehicle according to claim 3, wherein: The bracket includes a support member including a support shaft that supports the arm so as to be swingable. The low friction member includes a low friction washer provided on the outer peripheral side of the support shaft and interposed between the arm and the support member.

5. The electric vehicle according to claim 1, wherein: The arm has a protrusion protruding along the long side of the arm on the base end side of the arm, The bracket includes an upper wall portion provided above the protrusion and abutting against the protrusion when the arm swings, and a lower wall portion provided below the protrusion and abutting against the protrusion when the arm swings.

6. The electric vehicle according to claim 1, wherein: The vehicle body includes a wheelchair.

7. A vehicle electric assist device, mounted on a vehicle, comprising: a bracket, which is fixed to the above-mentioned vehicle; An arm is mounted on the bracket in a manner that allows it to swing in an up-and-down direction; a driving wheel disposed at the front end of the arm; an actuator that drives the drive wheel; and The elastic member is provided between the bracket and the arm and biases the arm downward.

8. The electric assist device for a vehicle according to claim 7, wherein: The bracket has: a main body on which the arm is mounted; and a fixing portion that fixes the main body portion at a predetermined height position of the vehicle, The predetermined height position is a position where a straight line passing through the swing center of the arm and the rotation center of the drive wheel is parallel to the road surface when the wheel of the vehicle on which the vehicle electric assist device is mounted and the drive wheel are in contact with the road surface.

9. The electric assist device for a vehicle according to claim 7, wherein: The bracket has: a main body on which the arm is mounted; and A fixing portion capable of adjusting a height position of the main body portion of the vehicle.

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