Electric vehicle and electric vehicle assistance device

Abstract

An electric wheelchair 1 has a vehicle body 2 with a roller 2c and a main wheel 2b, a clamp 18 attached to the vehicle body 2, an arm 20 which is held by the clamp 18 so that the arm 20 can pivot in an upward / downward direction, a drive wheel 14 which is provided at a tip 21a of the arm 20, an actuator 16 which is configured to drive the drive wheel 14, and an elastic element 58 which is provided between the clamp 18 and the arm 20 and pre-tensions the arm 20 downwards.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electric vehicle and an electric assist device for vehicles. STATE OF THE ART

[0002] Patent Document 1 discloses an electric assist device for use in a wheelchair. This electric assist device includes a body including a battery, an electric motor, and a drive wheel, as well as a mounting rod. The electric motor drives the drive wheel. The mounting rod is a member used to install the body into a vehicle body of the wheelchair. The position of the body, which is installed into the vehicle body via the mounting rod, can be switched between a standby position and a traveling position. In the standby position, the drive wheel is raised off the road surface. In the traveling position, the drive wheel is in contact with the road surface. When the drive wheel is driven in the traveling position, the electric assist device assists the wheelchair in traveling. Prior art documentsPatent documents

[0003] Patent Document 1: Unexamined Japanese Patent Application, Publication No. 2016 - 150 077 (JP 2016 - 150 077 A) SUMMARY OF THE INVENTIONProblem to be solved by the invention

[0004] A wheelchair equipped with the conventional electric assist device described above travels with the body fixed in a fixed position. Therefore, shocks and vibrations from the road surface are transmitted directly to the body via the drive wheel. Such shocks and vibrations can lead to failures of the electric motor mounted on the body, as well as failures of peripheral devices driving the drive wheel, etc.

[0005] Therefore, it is conceivable to install the body so that it can move up and down to dampen the vibrations of the drive wheel. However, in this case, the drive wheel would only be pushed against the road surface by the weight of the body, and the contact pressure of the drive wheel cannot be adequately secured, which can reduce traction and hinder stable driving. Means to solve the problem (1) An electric vehicle according to an embodiment includes: a vehicle body having a wheel; a bracket fixed to the vehicle body; an arm supported by the bracket such that the arm is pivotable in an up-and-down direction; a drive wheel provided at a tip of the arm; an actuator configured to drive the drive wheel; and an elastic member provided between the bracket and the arm and biasing the arm downward. (7) From another aspect, the embodiment is an electric auxiliary device for vehicles to be mounted on a vehicle. The electric auxiliary device for vehicles includes: a bracket fixed to the vehicle; an arm provided on the bracket such that the arm is pivotable in the up / down direction; a drive gear provided at the tip of the arm; an actuator configured to drive the drive gear; and an elastic member provided between the bracket and the arm and biasing the arm downward. Effects of the invention

[0006] According to the present disclosure, it is possible to increase the contact pressure of the drive wheel while simultaneously damping vibrations from the drive wheel. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of an electric wheelchair according to an embodiment. Fig. 2 is a schematic diagram of a main part of the electric wheelchair viewed from the rear. Fig. 3 is an enlarged view of a main part of Fig. 1. Fig. 4 is an enlarged perspective view showing a bracket and an arm of a drive unit. Fig. Figure 5 is a sectional view of the clamp and arm. Fig. 6A is a schematic diagram showing a relationship between a drive gear and a main gear when an arm assembly is in a lower swing position. Fig. 6B is a schematic diagram showing a relationship between the drive wheel and the main wheel when a vehicle body is placed on a road surface. Fig. Figure 7A is a schematic diagram showing the forces applied to an arm when a drive wheel is braked during travel of an electric wheelchair in which a straight line passing through a pivot center of the arm and a rotation center of the drive wheel is not parallel to the road surface. Fig. 7B is a schematic diagram showing a force applied to the arm when the drive wheel is braked during travel of the electric wheelchair of the embodiment. Fig. 8 is a schematic diagram showing a bracket of a drive unit according to another embodiment. MODES FOR CARRYING OUT THE INVENTIONFirst, details of the embodiments are listed. [Overview of the Embodiments]

[0007] (1) An electric vehicle according to an embodiment includes: a vehicle body having a wheel; a bracket fixed to the vehicle body; an arm supported by the bracket so that the arm is pivotable in an up-and-down direction; a drive wheel provided at a tip of the arm; an actuator configured to drive the drive wheel; and an elastic member provided between the bracket and the arm and biasing the arm downward.

[0008] The above configuration features an elastic element that biases the up / down pivoting arm downward. Therefore, the drive wheel can be pushed against a road surface while the wheel is in contact with the road surface. This makes it possible to increase the downforce of the drive wheel while simultaneously dampening vibrations from the drive wheel.

[0009] (2) When the drive wheel is braked while the electric vehicle travels in a direction from a rotation center of the drive wheel to a swing center of the arm, a tensile force may be exerted by the drive wheel on the tip of the arm in a direction opposite to the traveling direction. When such a tensile force is exerted by the drive wheel on the arm, a force may be generated on the arm in a direction in which the arm rotates upward. When such a force is generated, the contact pressure of the drive wheel may decrease, and the drive wheel may swing in the up / down direction.

[0010] In contrast, in the present embodiment, a straight line passing through the pivot point of the arm and the pivot point of the drive wheel when the wheel and the drive wheel are in contact with a road surface is parallel to the road surface.

[0011] Therefore, the generation of force in the direction in which the arm rotates upward can be suppressed even though the pulling force is applied to the arm by the drive wheel.

[0012] This can reduce the contact pressure of the drive wheel and the vibrations of the drive wheel in the up / down direction can be reduced.

[0013] (3) The electric vehicle may further include a low-friction member disposed between the bracket and the arm.

[0014] In this case, although a simple configuration is used in which the arm and the clamp are held between fasteners such as a bolt and a nut, the frictional force between the arm and the clamp can be reduced accordingly, and the arm can be provided so as to be pivotable relative to the clamp.

[0015] In addition, by holding the arm and clamp with the low-friction element in between, an appropriate friction force can be exerted between the arm and the clamp. Even if a force is generated in the direction in which the arm rotates upward, the force can be reduced. Furthermore, it is possible to reduce vibrations generated on the arm and the drive gear by the friction force between the arm and the clamp.

[0016] (4) In the electric vehicle, it is preferable that the bracket has a support member having a support shaft that supports the arm so that the arm is pivotable, and that the low-friction member has a low-friction disk provided on an outer peripheral side of the support shaft and disposed between the arm and the support member.

[0017] (5) In the electric vehicle, the arm may have a projection at an end portion of the arm that projects in a direction longitudinal to the arm, and the bracket may have an upper wall portion provided above the projection and with which the projection comes into contact when the arm swings, and a lower wall portion provided below the projection and with which the projection comes into contact when the arm swings.

[0018] In this case, the pivoting range of the projection can be limited by the upper and lower sections of the wall. Thus, the pivoting range of the arm can be limited. This can prevent the arm from pivoting beyond a required range.

[0019] (6) In the electric vehicle, the vehicle body may be a wheelchair.

[0020] (7) From another perspective, the embodiment is an electric auxiliary device for vehicles to be mounted on a vehicle. The electric auxiliary device for vehicles includes: a bracket fixed to the vehicle; an arm provided on the bracket such that the arm is pivotable in the up / down direction; a drive gear provided at a tip of the arm; an actuator configured to drive the drive gear; and an elastic member provided between the bracket and the arm and biasing the arm downward.

[0021] The above configuration has the elastic element that biases the arm downward. Therefore, the clamp can be attached to the vehicle body, pushing the drive wheel against a road surface, with the vehicle wheel in contact with the road surface. Therefore, the drive wheel is pushed against the road surface by the elastic element. This makes it possible to increase the contact pressure of the drive wheel while simultaneously dampening vibrations of the drive wheel.

[0022] (8) In the electric auxiliary device for vehicles, the bracket includes: a structure provided with the arm; and a fixing portion that fixes the structure to the vehicle at a predetermined height position. It is preferable that the predetermined height is a position where a straight line passing through the center of swing of the arm and the center of rotation of the drive wheel is parallel to the road surface when a wheel of the vehicle to which the electric auxiliary device is mounted and the drive wheel are in contact with the road surface.

[0023] In this case, the contact pressure of the drive wheel can be reduced and the vibrations of the drive wheel in the up and down direction can be reduced.

[0024] (9) In the electrical auxiliary device for vehicles, the bracket may include: a structure provided with the arm; and a fixing portion configured to adjust a height position of the structure on the vehicle.

[0025] In this case, the height position of the body can be adjusted so that the straight line passing through the pivot point of the arm and the pivot point of the drive wheel when the wheel of the vehicle to which the electric auxiliary device for the vehicle is attached and the drive wheel are in contact with the road surface is parallel to the road surface.

[0026] This can reduce the contact pressure of the drive wheel and the vibrations of the drive wheel in the up and down directions can be reduced. [Details of embodiments]

[0027] Preferred embodiments are described below with reference to the drawings. [General Configuration]

[0028] Fig. 1 is a perspective view of an electric wheelchair according to an embodiment. Fig. Figure 2 is a schematic diagram showing a main part of the electric wheelchair from the rear.

[0029] An electric wheelchair 1 has the function of driving the drive wheels of the electric wheelchair 1 when it is pushed from behind by an operator in order to assist the operator.

[0030] The electric wheelchair 1 is an electric vehicle having a vehicle body 2 and an electric vehicle support device 4.

[0031] The vehicle body 2 is a general wheelchair and has a frame 2a consisting mainly of metal tubes, a pair of main wheels 2b and a pair of casters 2c.

[0032] The frame 2a has a pair of rear tubes 2a1, a pair of front tubes 2a2, a pair of upper tubes 2a3 and a pair of lower tubes 2a4.

[0033] The pair of rear tubes 2a1 extend in an up / down direction. The pair of rear tubes 2a1 are arranged parallel to each other with a predetermined distance in a right / left direction.

[0034] The pair of lower tubes 2a4 is connected to the lower ends of the pair of rear tubes 2a1.

[0035] The pair of upper tubes 2a3 are connected to the pair of rear tubes 2a1. The portions of the pair of rear tubes 2a1 where the pair of upper tubes 2a3 are connected are located above the lower ends.

[0036] The pair of upper tubes 2a3 and the pair of lower tubes 2a4 extend in a forward / backward direction. The pair of upper tubes 2a3 and the pair of lower tubes 2a4 are provided substantially parallel to each other with predetermined intervals in the right / left direction.

[0037] Sections of the pair of lower tubes 2a4 behind the rear tubes 2a1 are tilt rods 2t. The tilt rod 2t is a member depressed by the operator's foot. When the operator depresses the tilt rod 2t, the track rollers 2c are lifted upward with the main wheels 2b as pivot points.

[0038] The pair of front tubes 2a2 extend in the up / down direction. The pair of front tubes 2a2 connects the tips of the pair of upper tubes 2a3 and the tips of the pair of lower tubes 2a4. Therefore, the pair of front tubes 2a2 is shorter than the pair of rear tubes 2a1.

[0039] The pair of track rollers 2c are provided at the lower ends of the front tubes 2a2. The pair of main wheels 2b are provided at the lower ends of the rear tubes 2a1.

[0040] The pair of main wheels 2b is provided behind the pair of track rollers 2c. The pair of main wheels 2b are rear wheels. The pair of track rollers 2c are front wheels.

[0041] The vehicle body 2 also has a seat portion 2d on which an occupant sits, and a backrest portion 2e. The seat portion 2d is fixed to the pair of upper tubes 2a3. The backrest portion 2e is fixed to the pair of rear tubes 2a1.

[0042] The electric wheelchair 1 is manufactured by attaching the vehicle's electric assist device 4 to the vehicle body 2, which can be used as a wheelchair.

[0043] In the following description, a direction in which the passenger faces forward when riding the electric wheelchair 1 (the direction in which the backrest portion 2e faces forward) is defined as the forward direction, and the opposite direction is defined as the backward direction. Therefore, the passenger rides the electric wheelchair 1 while facing forward. A direction in which the passenger faces to the left is defined as the left direction, and a direction in which the passenger faces to the right is defined as the right direction.

[0044] The electric vehicle assist device 4 has a pair of drive units 8 and a pair of operation units 10.

[0045] As from Fig. As shown in Figure 1, a pair of projections 2a5 are provided at the upper ends of the pair of rear tubes 2a1. The pair of projections 2a5 project rearward with respect to the backrest portion 2e.

[0046] The pair of operating units 10 are provided on the pair of protrusions 2a5. Therefore, the pair of operating units 10 are provided above the right and left sides of the backrest portion 2e.

[0047] The pair of operating units 10 has handles 12.

[0048] The handle 12 is movable in the forward / backward direction relative to the projection 2a5.

[0049] The actuator unit 10 also has a potentiometer (not shown). The potentiometer detects the amount of displacement of the handle 12 in the forward / backward direction. The actuator unit 10 provides an output indicating the amount of displacement of the handle 12 to a control device (described later).

[0050] The pair of drive units 8 are mounted on the right and left sides of the frame 2a. The pair of drive units 8 are provided on the inboard side of the pair of main wheels 2b of the vehicle.

[0051] The pair of drive units 8 has drive wheels 14 and actuators 16.

[0052] The actuator 16 drives the drive wheel 14. The actuator 16 is a wheel hub motor and is provided within the drive wheel 14.

[0053] The drive unit 8 will be described in detail later.

[0054] The electric vehicle support device 4 further includes a battery and a control panel (not shown) in which, for example, the control device that controls each part is housed.

[0055] The battery stores electrical energy which is supplied to the pair of drive units 8 (actuators 16) and each part.

[0056] The control device functions to control the pair of actuators 16 based on the outputs provided by the pair of operating units 10. As described above, the outputs of the pair of operating units 10 indicate the displacement amounts of the pair of handles 12.

[0057] The control device controls the pair of actuators 16 based on the displacement amounts of the pair of handles 12 to maintain the relative positions of the handles 12 and the frame 2a (vehicle body 2).

[0058] The control device can cause the actuators 16 to drive the drive wheels 14 to accelerate the vehicle body 2 or to maintain speed. The control device can brake the drive wheels 14 by causing the actuators 16 to perform regenerative braking, short-circuit braking, etc., thereby decelerating the vehicle body 2.

[0059] For example, when the operator pushes the handles 12 forward, the handles 12 are displaced forward. The control device moves the vehicle body 2 forward based on the outputs of the pair of operating units 10 to return the handles 12 to their original positions. Conversely, when the operator pulls the handles 12, the handles 12 are displaced backward. The control device moves the vehicle body 2 backward to return the handles 12 to their original positions.

[0060] In this way, the control device adjusts the amounts of operation of the actuators 16 in response to the operator's pushing and pulling of the handles 12. Thus, the control device controls the pair of actuators 16 to maintain the relative positions of the handles 12 and the vehicle body 2. [Drive unit configuration]

[0061] Fig. 3 is an enlarged view of a main part of Fig. 1. For a better understanding, the right main wheel 2b, the left drive wheel 14 and the left actuator 16 are shown in Fig. 3 omitted.

[0062] The drive unit 8 also has a clamp 18 and an arm 20. The clamp 18 is a plate-shaped element. The clamp 18 is attached to the lower tube 2a4 and the rear tube 2a1.

[0063] The arm 20 is held by the clamp 18 so that it can be pivoted in the upward / downward direction.

[0064] The arm 20 has an arm structure 21 and a projection 22 provided integrally with the arm structure 21.

[0065] The tip 21a of the arm structure 21 has a cutout 21a1.

[0066] An axle 14a extending from the drive gear 14 is fixed to the cutout 21a1. Therefore, the drive gear 14 and the actuator 16 are provided at the tip 21a of the arm assembly 21.

[0067] When the arm assembly 21 swings in the up / down direction, the drive wheel 14 and the actuator 16 move in the up / down direction.

[0068] A rotor (not shown) of the actuator 16 can rotate together with the drive wheel 14. A stator (not shown) of the actuator 16 is attached to the side of the arm 20. Thus, the actuator 16 drives the drive wheel 14 to rotate it.

[0069] Fig. 4 is an enlarged perspective view showing the bracket 18 and the arm 20 of the drive unit 8. Fig. Figure 4 shows the bracket 18 and arm 20 of the left drive unit 8. The right and left drive units 8 have the same configuration. Therefore, only the left drive unit 8 will be described.

[0070] The clamp 18 has a structure 24 and a fastening section 26. The structure 24 is provided with the arm 20.

[0071] The attachment portion 26 is provided on the top of the body 24. The attachment portion 26 fixes the body 24 at a predetermined height position on the vehicle body 2.

[0072] The attachment portion 26 has a front attachment portion 28 and a rear attachment portion 30.

[0073] The front attachment portion 28 has a rectangular plate-shaped portion 28a connected to the body 24 and a semi-cylindrical member 28b. One end of the semi-cylindrical member 28b is inserted into a slot 28c provided in the plate-shaped portion 28a and is fixed to the plate-shaped portion 28a. The other end of the semi-cylindrical member 28b is fixed to the plate-shaped portion 28a with a screw 28d. The lower tube 2a4 passes between the plate-shaped portion 28a and the semi-cylindrical member 28b (see Fig. 3). The lower tube 2a4 is held between the plate-shaped portion 28a and the semi-cylindrical member 28b. Thus, the front attachment portion 28 is fixed to the lower tube 2a4.

[0074] The rear attachment portion 30 has a projection 30a projecting from an edge of the body 24 toward the inboard side of the vehicle, and a pillar 30b extending upward from the tip of the projection 30a.

[0075] The upper surface of the projection 30a is in contact with the lower tube 2a4 (see Fig. 3).

[0076] At the top of the column 30b, a cutout 30b1 is provided. A screw 3a, which protrudes from a hub 3 of the main wheel 2b, which is fixed to the rear tube 2a1, is fixed to the cutout 30b1 (see Fig. 3). The column 30b is held between the hub 3 and a nut 3b, which is screwed together with the bolt 3a. Thus, the rear mounting portion 30 is secured to the rear tube 2a1.

[0077] The fastening section 26 is attached to the lower tube 2a4 and the rear tube 2a1. Thus, the fastening section 26 fixes the body 24 to the frame 2a.

[0078] As from Fig. As can be seen from Figure 4, the arm assembly 21 of the arm 20 provided on the assembly 24 swings around a central axis C1. That is, the central axis C1 is a center of swing of the arm assembly 21.

[0079] Fig. Figure 5 is a sectional view of the bracket 18 and the arm 20. Fig. Figure 5 shows a cross section along the up / down direction with the central axis C1.

[0080] As from Fig. 5, the clamp 18 also has a support element 34. The support element 34 holds the arm 20 so that the arm 20 is pivotable.

[0081] The support element 34 has a support shaft 36, a spacer 38, a washer 44 and a nut 42.

[0082] The support member 34 is fixed to a support hole 24a provided in the structure 24. The support hole 24a is a hole provided around the central axis C1.

[0083] The support shaft 36 has 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 threadably engaged with the threaded portion 36c.

[0084] The support element 34 is manufactured by arranging the arm 20, the spacer 38 and the disc 44 on the outboard side of the support shaft 36.

[0085] A pair of low-friction discs 40 are mounted on the support member 34. The pair of low-friction discs 40 are arranged on both sides of the arm 20.

[0086] On the outer peripheral side of the support shaft 36, the disc 44, the low-friction disc 40, the arm 20, the low-friction disc 40, the spacer 38 and the structure 24 are provided in this order from the head portion 36b to the threaded portion 36c.

[0087] The disc 44 is an element that prevents each element from falling off the support shaft 36.

[0088] The spacer 38 is a tubular member. The shaft portion 36a is inserted into the inner peripheral side of the spacer 38. The spacer 38 is a member for maintaining a distance between the structure 24 and the arm 20.

[0089] A hole 21b1 is provided on one side of the arm assembly 21, which rests on a supporting end 21b. The shaft portion 36a is inserted into the hole 21b1. A sliding bearing 46 is interposed between the hole 21b1 and the shaft portion 36a.

[0090] The pair of low-friction discs 40 has a low coefficient of friction on the front and back.

[0091] The low-friction washers 40 are arranged between the arm 20 and the spacer 38 and between the arm 20 and the washer 44.

[0092] The low-friction disk 40 includes, for example, a normal disk whose front and back surfaces are coated with a low-friction material such as fluororesin that reduces the friction coefficient, or a disk made of a low-friction material.

[0093] A spring washer or a wave washer can also be used as the low-friction washer 40. Both the spring washer and the wave washer can reduce the coefficient of friction by reducing the contact area between the washer and the element in contact with it.

[0094] The washer 44, the low-friction washer 40, the arm 20, the low-friction washer 40, the spacer 38 and the structure 24 are tightened between the section 36b of the head and the nut 42. That is, the arm 20, the structure 24 and the other elements are held between the support shaft 36 and the nut 42, which are fastening elements.

[0095] Since the arm 20 is provided between the pair of low-friction discs 40, the friction force between the arm 20 and the support member 34 can be reduced accordingly.

[0096] That is, even if the simple configuration in which the arm 20 and the structure 24 are held between the fastening members as adopted in the present embodiment, the frictional force between the arm 20 and the support member 34 can be reduced accordingly, and the arm 20 can be provided so as to be pivotable relative to the support member 34 (clamp 18).

[0097] As can be seen from the Fig. 4 and Fig. 5, the projection 22 of the arm 20 is provided on the side of the base end 21b of the arm structure 21. The projection 22 has a radial portion 50 and an elongated portion 52.

[0098] The radial portion 50 protrudes from a side surface 21c of the arm assembly 21. The radial portion 50 extends along a radial direction perpendicular to the central axis C1. Furthermore, the radial portion 50 extends from the base end 21b in a direction intersecting the longitudinal direction of the arm assembly 21.

[0099] The elongated portion 52 extends from a side surface 50a of the radial portion 50. The elongated portion 52 extends in a direction opposite to the direction in which the arm assembly 21 extends. The elongated portion 52 extends substantially parallel to the longitudinal direction of the arm assembly 21.

[0100] As from Fig. As can be seen in Figure 4, the bracket 18 has a curved portion 54 that projects along the side edge of the body 24 toward the inboard side of the vehicle. The curved portion 54 has a recess 55. The recess 55 is provided by cutting out the edge of the curved portion 54. The recess 55 has an upper wall portion 55a and a lower wall portion 55b. The upper wall portion 55a and the lower wall portion 55b face each other.

[0101] The elongated portion 52 is inserted into the recess 55. Therefore, the upper wall portion 55a is provided above the elongated portion 52. The lower wall portion 55b is provided below the elongated portion 52.

[0102] The elongated portion 52 (protrusion 22) is provided integrally with the arm assembly 21. Therefore, the elongated portion 52 swings along with the swing of the arm assembly 21.

[0103] When the arm assembly 21 swings downward by a predetermined angle, the elongated portion 52 swings upward and comes into contact with the upper wall portion 55a. In this case, further upward swing of the elongated portion 52 is restricted.

[0104] When the arm assembly 21 swings upward by a predetermined angle, the elongated portion 52 swings downward and comes into contact with the lower wall portion 55b. In this case, further downward swing of the elongated portion 52 is restricted.

[0105] Therefore, the pivoting range of the elongated portion 52 (protrusion 22) is limited by the upper wall portion 55a and the lower wall portion 55b. Thus, the pivoting range of the arm 20 (arm assembly 21) can be limited. This can suppress pivoting of the arm assembly 21 beyond a required range.

[0106] That is, the pivoting range of the arm assembly 21 is limited to the range from the position of the arm assembly 21 where the elongated portion 52 comes into contact with the upper wall portion 55a to the position of the arm assembly 21 where the elongated portion 52 comes into contact with the lower wall portion 55b.

[0107] In the following description, the position of the arm assembly 21 at which the elongated portion 52 comes into contact with the upper wall portion 55a is referred to as the lower pivot position, and the position of the arm assembly 21 at which the elongated portion 52 comes into contact with the lower wall portion 55b is referred to as the upper pivot position.

[0108] As from Fig. 4, the drive unit 8 also has an elastic element 58.

[0109] The elastic element 58 is provided between the bracket 18 and the arm 20. The elastic element 58 biases the arm 20 (arm assembly 21) downward.

[0110] The elastic element 58 is, for example, a helical tension spring.

[0111] An L-shaped spring hook portion 24b is provided at the rear end of the structure 24.

[0112] A spring hook bolt 60 is provided on the radial portion 50 of the projection 22. The spring hook bolt 60 is inserted into a hole 50b of the radial portion 50 (see Fig. 5). The spring hook screw 60 tightens the radial section 50 by engaging with a nut 62. Thus, the spring hook bolt 60 can be secured to the radial section 50.

[0113] One end of the elastic member 58 is hooked to the spring hook portion 24b. The other end of the elastic member 58 is hooked into a groove 60a at the tip of the spring hook screw 60.

[0114] Since the elongated portion 52 is in contact with the upper wall portion 55a, the elastic member 58 exerts a tensile force between the spring hook portion 24b and the spring hook screw 60.

[0115] Therefore, if no force is applied to pivot the arm assembly 21 upwards, the arm assembly 21 is in the lower pivot position.

[0116] When the arm assembly 21 is in the lower pivot position, a tensile force is applied between the portion of the spring hook 24b and the spring hook screw 60 by the elastic element 58.

[0117] When the arm assembly 21 is between the lower pivot position and the upper pivot position, the elastic element 58 biases the arm 20 (arm assembly 21) downward.

[0118] Fig. Fig. 6A is a schematic diagram showing the relationship between the drive gear 14 and the main gear 2b when the arm assembly 21 is in the lower swing position.

[0119] As from Fig. 6A, when the main wheel 2b of the vehicle body 2 and the drive wheel 14 are not in contact with the road surface R, no force is exerted on the arm assembly 21 from the road surface R. Therefore, the arm assembly 21 is in the lower swing position.

[0120] When the arm assembly 21 is in the lower pivot position, the lowermost portion of the drive wheel 14 is located below the lowermost portion of the main wheel 2b.

[0121] Fig. 6B is a schematic diagram showing the relationship between the drive wheel 14 and the main wheel 2b when the vehicle body 2 is placed on the road surface R.

[0122] In this case, the track roller 2c, the main wheel 2b, and the drive wheel 14 are in contact with the road surface R. Therefore, the arm assembly 21 is located between the lower and upper swing positions.

[0123] At this time, the elastic member 58 biases the up / down pivotable arm assembly 21 downward. Therefore, the drive wheel 14 is pushed against the road surface R by the tensile force of the elastic member 58. This allows the contact pressure of the drive wheel 14 to be increased while simultaneously damping the vibrations transmitted from the drive wheel 14 to the vehicle body 2.

[0124] In the present embodiment, when the idler roller 2c, the main wheel 2b, and the drive wheel 14 are in contact with the road surface R, a straight line L is parallel to the road surface R. The straight line L is a straight line passing through the center axis C1, which is the fulcrum of the arm assembly 21, and a rotation center C2 of the drive wheel 14.

[0125] The present embodiment of the description “the straight line L is parallel to the road surface R” has two cases: one case is that the straight line L is parallel to the road surface R, and the other case is that the straight line L is substantially parallel to the road surface R. The description “the straight line L is parallel to the road surface R” means that an acute angle θ between the straight line L and a straight line along the road surface R is equal to or greater than 0 degrees and equal to or less than 8 degrees.

[0126] In the present embodiment, the position of the arm assembly 21 in which the straight line L is substantially parallel to the road surface R is located between the lower swing position and the upper swing position.

[0127] A case is described in which the drive wheel is braked when the electric wheelchair, in which the straight line L is not parallel to the road surface R, moves forward.

[0128] Fig. 7A is a schematic representation of the forces exerted on an arm when a drive wheel 114 is braked during travel of an electric wheelchair in which the straight line L is not parallel to the road surface R.

[0129] Fig. 7A shows a case where the electric wheelchair moves (moves forward) in a direction from the pivot point C2 of the drive wheel 114 to the center axis C1 of an arm 120.

[0130] In this case, the drive wheel 114 is braked (regenerative braking or short-circuit braking). Therefore, a tensile force F1 is applied to a tip 120A of the arm 120 in a direction opposite to the traveling direction by the drive wheel 114. Since the straight line L is not parallel to the road surface R, at this time, a force F2 may be generated on the arm 120 in a direction in which the arm 120 rotates upward.

[0131] When such a force F2 is generated on the arm 120, the contact pressure of the drive wheel 114 may decrease and the drive wheel 114 may swing in the up / down direction.

[0132] Fig. 7B is a schematic diagram showing a force applied to the arm when the drive wheel is braked during travel of the electric wheelchair of the present embodiment.

[0133] As from Fig. 7B, although the traction force is applied to the arm 20 by the drive wheel 14 when the straight line L is parallel to the road surface R, the generation of a force in a direction in which the arm 20 rotates upward can be suppressed.

[0134] Thereby, the pressure at the contact of the drive wheel 14 can be reduced and the vibrations of the drive wheel in the up / down direction can be reduced.

[0135] In the present embodiment, an appropriate frictional force can be applied between the arm 20 and the support member 34 by holding the arm 20 and the support member 34 (clamp 18) with the low-friction washers 40 interposed therebetween. Even if a force is generated in the direction in which the arm 20 rotates upward, the force can be reduced. Furthermore, it is possible to reduce vibrations generated at the arm 20 and the drive gear 14 by the frictional force between the arm 20 and the support member 34. [Other embodiments]

[0136] Fig. Fig. 8 is a schematic diagram showing a bracket 18 of a drive unit 8 according to another embodiment. The present embodiment differs from the above embodiment in that the cutout 30b1 provided in the column 30b is longer in the height direction, and a plurality of slots 28c and a plurality of screw holes 28b1 are arranged along the height direction.

[0137] With the above configuration of the fixing portion 26 of the present embodiment, the position of the body 24 on the vehicle body 2 can be adjusted in height.

[0138] Therefore, the position of the height of the body 24 can be adjusted so that the straight line L is parallel to the road surface.

[0139] Thereby, the pressure at the contact of the drive wheel 14 can be reduced and the vibrations of the drive wheel 14 in the up / down direction can be reduced. [Miscellaneous]

[0140] The embodiments disclosed herein are in all respects illustrative and not restrictive.

[0141] The above embodiments illustrate the case where the helical tension spring is used as the elastic member 58, but instead of the helical tension spring, a rubber ring, etc. may be used.

[0142] The above embodiments illustrate the case where the position of the arm assembly 21 in which the straight line L is substantially parallel to the road surface R is between the lower swing position and the upper swing position, and the lower swing position and the upper swing position may be within the range of the position of the arm assembly 21 in which the straight line L is substantially parallel to the road surface R.

[0143] In this case, the swing range of the arm structure 21 can be limited to the range in which the straight line L is substantially parallel to the road surface R.

[0144] In the above embodiments, the vehicle body 2 is illustrated with the front and rear wheels (caster wheels 2c and main wheels 2b), but the vehicle body 2 may have at least one of the front and rear wheels.

[0145] The above embodiments illustrate the case where the electric vehicle assist device 4 is mounted on the vehicle body 2 which is a general wheelchair, however, the vehicle body 2 may be a trolley, a cart, etc. other than a wheelchair.

[0146] The scope of the present invention is not limited to the above embodiments and includes all changes made within the scope of equivalents to the configurations set forth in the claims. Description of reference symbols 2 vehicle body, 4 electric vehicle support device, 14 drive wheel, 16 actuator, 18 bracket, 20 arms, 21a peak, 21b base end, 22 lead, 24 Structure, 26 fastening section, 34 support element, 36 support shaft, 40 low-friction disc (low-friction element), 55a upper wall section, 55b lower wall section, 58 elastic element QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2016 - 150 077

[0003] JP 2016 - 150 077 A

[0003]

Claims

[1] Electric vehicle with: a vehicle body with a wheel; a bracket attached to the vehicle body; an arm supported by the clamp such that the arm is pivotable in an up / down direction; a drive wheel provided at a tip of the arm; an actuator configured to drive the drive wheel; and an elastic element provided between the clamp and the arm, which biases the arm downward. [2] An electric vehicle according to claim 1, wherein a straight line passing through a pivoting center of the arm and a rotational center of the drive wheel when the wheel and the drive wheel are in contact with a road surface is parallel to the road surface. [3] An electric vehicle according to claim 2, further comprising a low-friction member between the bracket and the arm. [4] Electric vehicle according to claim 3, wherein the clamp has a support element with a support shaft that holds the arm so that the arm can pivot, and the low-friction member has a low-friction washer provided on an outer peripheral side of the support shaft and disposed between the arm and the support member. [5] Electric vehicle according to claim 1, wherein the arm has a projection on a base end side of the arm which projects along a direction in the longitudinal direction of the arm, and the bracket has an upper wall portion provided above the projection and with which the projection comes into contact when the arm swings, and a lower wall portion provided below the projection and with which the projection comes into contact when the arm swings. [6] An electric vehicle according to claim 1, wherein the vehicle body includes a wheelchair. [7] An electric vehicle assist device to be mounted on a vehicle, the electric vehicle assist device comprising: a clamp attached to the vehicle; an arm attached to the bracket so that the arm can pivot in an up and down direction; a drive wheel attached to the tip of the arm; an actuator configured to drive the drive wheel; and an elastic element provided between the clamp and the arm, biasing the arm downward. [8] An electric vehicle support device according to claim 7, wherein the bracket has: a structure provided with the arm; and a fastening section that fixes the body to the vehicle at a predetermined height position, and the predetermined height position is a position in which a straight line passing through a pivoting center of the arm and a rotational center of the driving wheel when a wheel of the vehicle to which the electric auxiliary device for the vehicle is mounted and the driving wheel are in contact with a road surface is parallel to the road surface. [9] The electric vehicle support device according to claim 7, wherein the bracket has: a structure provided with the arm; and a mounting section configured to adjust the height of the body on the vehicle.

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