Electric vehicle

Abstract

Electric vehicle (1) with: a vehicle body (2) with a wheel (2b); a clamp (18) which is attached to the vehicle body (2); an arm (20) which is held by the clamp (18) such 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) configured to drive the drive wheel (14); and an elastic element (58) which is provided between the clamp (18) and the arm (20) and prestresses the arm (20) downwards, wherein the arm (20) has a projection (22) at a base end side of the arm (20) that projects along a direction in the longitudinal direction of the arm (20), and the bracket (18) has an upper wall section (55a) which is provided above the projection (22) and with which the projection (22) comes into contact when the arm (20) swings, and a lower wall section (55b) which is provided below the projection (22) and with which the projection (22) comes into contact when the arm (20) swings.

Description

TECHNICAL AREA

[0001] The present invention relates to an electric vehicle. STATE OF THE ART

[0002] Publication JP 2016-150 077 A discloses an electric assistive device for use in a wheelchair. This electric assistive device comprises a unit with a battery, an electric motor, and a drive wheel, as well as a mounting bar. The electric motor drives the drive wheel. The mounting bar is used to install the unit into the wheelchair body. The position of the unit, which is installed in the vehicle body via the mounting bar, can be switched between a standby position and a driving position. In the standby position, the drive wheel is lifted off the ground. In the driving position, the drive wheel is in contact with the ground. When the drive wheel is powered in the driving position, the electric assistive device assists the wheelchair while driving.

[0003] Documents US 5222567 A and EP 0 927 551 A1 depict vehicles of the type. SUMMARY OF THE INVENTION Problem to be solved by the invention

[0004] The wheelchair, equipped with the aforementioned conventional electric assist device, is fixed in a stationary position with the chassis. Therefore, shocks and vibrations from the road surface are transmitted directly to the chassis via the drive wheel. Such shocks and vibrations can lead to failures of the electric motor mounted on the chassis, as well as failures of peripheral devices that drive the wheel, etc.

[0005] Therefore, it is conceivable to install the structure in such a way that it can move up and down to dampen the vibrations of the drive wheel. In this case, however, the drive wheel is only pushed against the road surface by the weight of the structure, and the contact pressure of the drive wheel cannot be adequately ensured, which can reduce traction and hinder stable driving.

[0006] The object of the invention is to provide an electric vehicle in which the contact pressure of a drive wheel is sufficiently high and vibrations of the drive wheel are dampened to enable stable driving.

[0007] The problem is solved by a vehicle according to claim 1. Advantageous embodiments are the subject of the dependent claims. Effects of the invention

[0008] According to the present disclosure, it is possible to increase the contact pressure of the drive wheel while simultaneously dampening vibrations from the drive wheel. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a perspective view of an electric wheelchair according to one embodiment. Fig. Figure 2 is a schematic representation of a main part of the electric wheelchair seen from the rear. Fig. Figure 3 is an enlarged view of a main part from Fig. 1. Fig. Figure 4 is an enlarged perspective view showing a clamp and arm of a drive unit. Fig. Figure 5 is a sectional view of the clamp and arm. Fig. Figure 6A is a schematic representation showing a relationship between a drive wheel and a main wheel when an arm assembly is in a lower pivot position. Fig. Figure 6B is a schematic representation 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 representation showing the forces applied to an arm when a drive wheel is braked during the movement of an electric wheelchair, where 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. Figure 7B is a schematic representation showing a force applied to the arm when the drive wheel is braked during the movement of the electric wheelchair of the embodiment. Fig. Figure 8 is a schematic representation showing a clamp of a drive unit according to another embodiment. OPERATING MODES FOR EXECUTING THE INVENTION

[0009] First, details of the embodiments are listed. [Overview of the embodiments]

[0010] (1) An electric vehicle according to one embodiment has: a vehicle body with one wheel; a clamp attached to the vehicle body; an arm held by the clamp in such a way that the arm can pivot upwards and downwards in one direction; a drive wheel provided at one end of the arm; an actuator configured to drive the drive wheel; and an elastic element provided between the clamp and the arm, which pre-tensions the arm downwards.

[0011] The configuration described above incorporates an elastic element that pre-tensions the upward / downward pivoting arm downwards. This allows the drive wheel to be pushed against a road surface, maintaining contact with the surface. This increases the contact pressure of the drive wheel while simultaneously dampening vibrations from the drive wheel.

[0012] (2) If the drive wheel is braked while the electric vehicle is moving in one direction from a pivot point of the drive wheel to a pivot point of the arm, the drive wheel may exert a pulling force on the tip of the arm in a direction opposite to the direction of travel. If such a pulling force is exerted on the arm by the drive wheel, a force may be generated on the arm in a direction that causes the arm to rotate upwards. If such a force is generated, the contact pressure of the drive wheel may decrease and the drive wheel may oscillate in the up / down direction.

[0013] 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 lies parallel to the road surface when the wheel and the drive wheel are in contact with a road surface.

[0014] Therefore, the generation of force in the direction in which the arm rotates upwards can be suppressed, even though the pulling force is exerted on the arm by the drive wheel.

[0015] This allows the contact pressure of the drive wheel to be reduced and the vibrations of the drive wheel in the upward / downward direction to be reduced.

[0016] (3) The electric vehicle may also have a low-friction element arranged between the clamp and the arm.

[0017] In this case, the frictional force between the arm and the clamp can be reduced accordingly, although a simple configuration is used in which the arm and the clamp are held between fasteners such as a screw and a nut, and the arm can be provided so that it is pivotable relative to the clamp.

[0018] Furthermore, a suitable frictional force can be exerted between the arm and the clamp by holding the arm and clamp with the low-friction element between them. Even if a force is generated in the direction in which the arm rotates upwards, the force can be reduced. In addition, it is possible to reduce vibrations generated at the arm and the drive wheel by the frictional force between the arm and the clamp.

[0019] (4) In the electric vehicle, it is preferable that the clamp has a support element with a support shaft which holds the arm so that the arm is pivotable, and that the low-friction element has a low-friction disc which is provided on an outer circumferential side of the support shaft and is arranged between the arm and the support element.

[0020] (5) In the electric vehicle, the arm may have a projection at an end section of the arm that extends in a direction in the longitudinal direction of the arm, and the clamp may have an upper wall section provided above the projection with which the projection comes into contact when the arm swings, and a lower wall section provided below the projection with which the projection comes into contact when the arm swings.

[0021] In this case, the swivel range of the projection can be limited by the upper and lower sections of the wall. This limits the arm's swivel range, preventing it from swiveling beyond a necessary range.

[0022] (6) In the electric vehicle, the vehicle body can be a wheelchair.

[0023] (7) From another perspective, the embodiment is an electrical auxiliary device for vehicles, which is to be attached to a vehicle. The electrical auxiliary device for vehicles has: a clamp attached to the vehicle; an arm provided on the clamp such that the arm is pivotable in an upward / downward direction; a drive wheel provided at one end 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 downwards.

[0024] The configuration described above features an elastic element that pre-tensions the arm downwards. This allows the clamp to be attached to the vehicle body, pushing the drive wheel against the road surface. The elastic element then pushes the drive wheel against the road surface, thereby increasing the contact pressure of the drive wheel and simultaneously dampening its vibrations.

[0025] (8) In the electrical auxiliary device for vehicles, the clamp has: a superstructure that is provided with the arm; and a fastening section that secures the superstructure to the vehicle at a predetermined height position. It is preferable that the predetermined height be a position in which a straight line passing through the center of the pivoting movement 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 electrical auxiliary device is attached and the drive wheel are in contact with the road surface.

[0026] In this case, the contact pressure of the drive wheel can be reduced and the vibrations of the drive wheel in the upward and downward direction can be reduced.

[0027] (9) In the electrical auxiliary device for vehicles, the clamp may have: a superstructure provided with the arm; and a mounting section configured to adjust the height position of the superstructure on the vehicle.

[0028] In this case, the height position of the structure 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 electrical auxiliary device for the vehicle is attached and the drive wheel are in contact with the road surface, is parallel to the road surface.

[0029] This allows the contact pressure of the drive wheel to be reduced and the vibrations of the drive wheel in the upward and downward direction to be reduced. [Details of embodiments]

[0030] Preferred embodiments are described below with reference to the drawings. [General Configuration] Fig. Figure 1 is a perspective view of an electric wheelchair according to one embodiment. Fig. Figure 2 is a schematic representation showing a main part of the electric wheelchair from the rear.

[0031] An electric wheelchair 1 has the function of powering the drive wheels of the electric wheelchair 1 when it is pushed from behind by an operator to assist the operator.

[0032] The electric wheelchair 1 is an electric vehicle with a vehicle body 2 and an electric vehicle support device 4.

[0033] The vehicle body 2 is a general wheelchair and has a frame 2a, which is mainly made of metal tubes, a pair of main wheels 2b and a pair of running casters 2c.

[0034] 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.

[0035] The pair of rear tubes 2a1 extends in an upward / downward direction. The pair of rear tubes 2a1 is parallel to each other with a predetermined distance in a right / left direction.

[0036] The pair of lower tubes 2a4 is connected to the lower ends of the pair of rear tubes 2a1.

[0037] The pair of upper tubes 2a3 is connected to the pair of rear tubes 2a1. The sections of the pair of rear tubes 2a1 where the pair of upper tubes 2a3 is connected are located above the lower ends.

[0038] 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 essentially parallel to each other with predetermined distances in the right / left direction.

[0039] Sections of the pair of lower tubes 2a4 behind the rear tubes 2a1 are tilting bars 2t. The tilting bar 2t is an element that is pressed down by the operator's foot. When the operator presses down the tilting bar 2t, the guide rollers 2c are raised with the main wheels 2b as pivot points.

[0040] The pair of front tubes 2a2 extends in an upward / downward 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.

[0041] The pair of track rollers 2c is provided at the lower ends of the front tubes 2a2. The pair of main wheels 2b is provided at the lower ends of the rear tubes 2a1.

[0042] The pair of main wheels 2b is positioned 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.

[0043] The vehicle body 2 also has a seat section 2d, on which an occupant sits, and a backrest section 2e. The seat section 2d is attached to the pair of upper tubes 2a3. The backrest section 2e is attached to the pair of rear tubes 2a1.

[0044] The electric wheelchair 1 is manufactured by attaching the vehicle's electric auxiliary device 4 to the vehicle body 2, which can be used as a wheelchair.

[0045] In the following description, a direction in which the occupant faces forward while riding the electric wheelchair 1 (direction in which the section of the backrest 2e faces forward) is defined as the forward direction, and the opposite direction is defined as the backward direction. Therefore, the occupant rides the electric wheelchair 1 while facing forward. A direction in which the occupant faces to the left is defined as the left direction, and a direction in which the occupant faces to the right is defined as the right direction.

[0046] The electric vehicle support device 4 has a pair of drive units 8 and a pair of operating units 10.

[0047] As from Fig. As can be seen in Figure 1, a pair of projections 2a5 is provided at the upper ends of the pair of rear tubes 2a1. The pair of projections 2a5 extends rearward with respect to the section of the backrest 2e.

[0048] The pair of actuating units 10 is provided on the pair of projections 2a5. Therefore, the pair of actuating units 10 is provided above the right and left sides of the backrest section 2e.

[0049] The pair of actuation units 10 has handles 12.

[0050] The handle 12 is movable in a forward / backward direction relative to the projection 2a5.

[0051] The actuating unit 10 also has a potentiometer (not shown). The potentiometer detects the degree of movement of the handle 12 in the forward / backward direction. The actuating unit 10 provides an output indicating the degree of movement of the handle 12 to a control device (described later).

[0052] The pair of drive units 8 is attached to the right and left sides of the frame 2a. The pair of drive units 8 is located on the inner side of the pair of main wheels 2b of the vehicle.

[0053] The pair of drive units 8 has drive wheels 14 and actuators 16.

[0054] The actuator 16 drives the drive wheel 14. The actuator 16 is a wheel hub motor and is located inside the drive wheel 14.

[0055] The drive unit 8 will be described in detail later.

[0056] The electric vehicle assistance device 4 further comprises a battery and a control panel (not shown) which, for example, houses the control device that controls each part.

[0057] The battery stores electrical energy, which is supplied to the pair of drive units 8 (actuators 16) and each part.

[0058] The control device has the function of controlling 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 values ​​of the pair of handles 12.

[0059] The control device controls the pair of actuators 16 based on the displacement amounts of the pair of handles 12 in order to maintain the relative positions of the handles 12 and the frame 2a (vehicle body 2).

[0060] The control device can cause the actuators 16 to drive the drive wheels 14 to accelerate the vehicle body 2 or to maintain its speed. The control device can brake the drive wheels 14 by causing the actuators 16 to perform regenerative braking, short-circuit braking, etc., thereby slowing down the vehicle body 2.

[0061] For example, if the operator pushes the handles 12 forward, the handles 12 are moved 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, if the operator pulls on the handles 12, the handles 12 are moved backward. The control device moves the vehicle body 2 backward to return the handles 12 to their original positions.

[0062] In this way, the control device adjusts the amounts of operation of the actuators 16 in response to the operator pushing and pulling 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. [Configuration of the drive unit]

[0063] Fig. Figure 3 is an enlarged view of a main part from Fig. 1. For better understanding, the right main wheel 2b, the left drive wheel 14 and the left actuator 16 are shown in Fig. 3 omitted.

[0064] 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.

[0065] The arm 20 is held by the clamp 18 in such a way that it can pivot in the upward / downward direction.

[0066] The arm 20 has an arm assembly 21 and a projection 22, which is provided as a single piece with the arm assembly 21.

[0067] The tip 21a of the arm assembly 21 has a cutout 21a1.

[0068] An axle 14a extending from the drive wheel 14 is attached to the cutout 21a1. Therefore, the drive wheel 14 and the actuator 16 are provided at the tip 21a of the arm assembly 21.

[0069] When the arm assembly 21 oscillates in the upward / downward direction, the drive wheel 14 and the actuator 16 move in the upward / downward direction.

[0070] 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.

[0071] Fig. Figure 4 is an enlarged perspective view showing the clamp 18 and arm 20 of the drive unit 8.

[0072] Fig. Figure 4 shows the clamp 18 and the 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 is described.

[0073] The clamp 18 has a structure 24 and a fastening section 26. The structure 24 is provided with the arm 20.

[0074] The fastening section 26 is provided on the top of the superstructure 24. The fastening section 26 fixes the superstructure 24 in a predetermined position at a specific height on the vehicle body 2.

[0075] The mounting section 26 has a front mounting section 28 and a rear mounting section 30.

[0076] The front mounting section 28 has a rectangular, plate-shaped section 28a, which is connected to the superstructure 24, and a semi-cylindrical element 28b. One end of the semi-cylindrical element 28b is inserted into a slot 28c provided in the plate-shaped section 28a and is fastened to the plate-shaped section 28a. The other end of the semi-cylindrical element 28b is fastened to the plate-shaped section 28a with a screw 28d. The lower tube 2a4 passes between the plate-shaped section 28a and the semi-cylindrical element 28b (see Fig. 3) The lower tube 2a4 is held between the plate-shaped section 28a and the semi-cylindrical element 28b. Thus, the front mounting section 28 is attached to the lower tube 2a4.

[0077] The rear mounting section 30 has a projection 30a extending from an edge of the body 24 to the inner side of the vehicle, and a column 30b extending upwards from the top of the projection 30a.

[0078] The upper surface of the projection 30a is in contact with the lower tube 2a4 (see Fig. 3).

[0079] A cutout 30b1 is provided at the top of column 30b. A screw 3a, protruding from a hub 3 of the main wheel 2b, which is attached to the rear tube 2a1, is fastened to the cutout 30b1 (see Fig. 3) The column 30b is held between the hub 3 and a nut 3b, which is screwed to the bolt 3a by interlocking. Thus, the rear mounting section 30 is attached to the rear tube 2a1.

[0080] The fastening section 26 is attached to the lower tube 2a4 and the rear tube 2a1. Thus, the fastening section 26 secures the assembly 24 to the frame 2a.

[0081] As from Fig. As can be seen in Figure 4, the arm assembly 21 of the arm 20, which is provided on the assembly 24, oscillates about a central axis C1. That is, the central axis C1 is a center of oscillation of the arm assembly 21.

[0082] Fig. Figure 5 is a sectional view of the clamp 18 and the arm 20. Fig. Figure 5 shows a cross-section along the upward / downward direction with the central axis C1.

[0083] As from Fig. As can be seen in Figure 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.

[0084] The support element 34 has a support shaft 36, a spacer 38, a washer 44 and a nut 42.

[0085] The support element 34 is attached to a support hole 24a, which is provided in the structure 24. The support hole 24a is a hole provided around the central axis C1.

[0086] The support shaft 36 has a shaft section 36a, a head section 36b, and a threaded section 36c. The head section 36b is provided at one end of the shaft section 36a. The threaded section 36c is provided at the other end of the shaft section 36a. The nut 42 engages with the threaded section 36c.

[0087] The support element 34 is manufactured by arranging the arm 20, the spacer 38 and the disc 44 on the outer side of the support shaft 36.

[0088] A pair of low-friction discs 40 is attached to the support element 34. The pair of low-friction discs 40 is arranged on both sides of the arm 20.

[0089] On the outer circumferential side of the support shaft 36, the washer 44, the low-friction washer 40, the arm 20, the low-friction washer 40, the spacer 38 and the assembly 24 are provided in this order from the head section 36b to the threaded section 36c.

[0090] The disc 44 is an element that prevents each element from falling off the support shaft 36.

[0091] The spacer 38 is a tubular element. Section 36a of the shaft is inserted into the inner circumferential side of the spacer 38. The spacer 38 is an element for maintaining a distance between the structure 24 and the arm 20.

[0092] A hole 21b1 is provided on one side of the arm assembly 21, which is based on a supported end 21b. The section 36a of the shaft is inserted into the hole 21b1. A sliding bearing 46 is intermediately supported between the hole 21b1 and the section 36a of the shaft.

[0093] The pair of low-friction discs 40 has a low coefficient of friction on both the front and back surfaces.

[0094] The low-friction discs 40 are arranged between the arm 20 and the spacer 38, as well as between the arm 20 and the washer 44.

[0095] The low-friction disc 40, for example, has a normal disc whose front and back sides are coated with a low-friction material such as fluoropolymer, which reduces the coefficient of friction, or a disc made of a low-friction material.

[0096] A spring washer or a wave washer can also be used as a 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.

[0097] The washer 44, the low-friction washer 40, the arm 20, the low-friction washer 40, the spacer 38 and the assembly 24 are tightened between 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 the fastening elements.

[0098] Since the arm 20 is positioned between the pair of low-friction discs 40, the frictional force between the arm 20 and the support element 34 can be reduced accordingly.

[0099] This means that even if the simple configuration in which the arm 20 and the structure 24 are held between the fastening elements is assumed as in the present embodiment, the frictional force between the arm 20 and the support element 34 can be reduced accordingly and the arm 20 can be provided in such a way that it is pivotable relative to the support element 34 (clamp 18).

[0100] As from the Fig. 4 and Fig. As can be seen in Figure 5, the projection 22 of the arm 20 is provided on the side of the base end 21b of the arm assembly 21.

[0101] The projection 22 has a radial section 50 and an elongated section 52.

[0102] The radial section 50 projects from a side surface 21c of the arm assembly 21. The radial section 50 extends along a radial direction perpendicular to the central axis C1. Furthermore, the radial section 50 extends from the base end 21b in a direction that intersects the longitudinal direction of the arm assembly 21.

[0103] The elongated section 52 extends from a side surface 50a of the radial section 50. The elongated section 52 extends in a direction opposite to the direction in which the arm assembly 21 extends. The elongated section 52 extends substantially parallel to the longitudinal direction of the arm assembly 21.

[0104] As from Fig. As can be seen in Figure 4, the clamp 18 has a curved section 54 that projects along the side edge of the superstructure 24 towards the inner side of the vehicle. The curved section 54 has a recess 55. The recess 55 is provided by cutting out the edge of the curved section 54. The recess 55 has an upper wall section 55a and a lower wall section 55b. The upper wall section 55a and the lower wall section 55b face each other.

[0105] The elongated section 52 is inserted into the recess 55. Therefore, the upper wall section 55a is provided above the elongated section 52. The lower wall section 55b is provided below the elongated section 52.

[0106] The elongated section 52 (projection 22) is integrally formed with the arm assembly 21. Therefore, the elongated section 52 oscillates together with the oscillation of the arm assembly 21.

[0107] When the arm assembly 21 swings downwards by a predetermined angle, the elongated section 52 swings upwards and comes into contact with the upper wall section 55a. In this case, further upward swinging of the elongated section 52 is restricted.

[0108] When the arm assembly 21 swings upwards by a predetermined angle, the elongated section 52 swings downwards and comes into contact with the lower wall section 55b. In this case, further downward swinging of the elongated section 52 is restricted.

[0109] Therefore, the pivot range of the elongated section 52 (projection 22) is limited by the upper wall section 55a and the lower wall section 55b. Thus, the pivot range of the arm 20 (arm assembly 21) can be limited. This prevents the pivoting of the arm assembly 21 beyond a required range.

[0110] This means that the swivel range of the arm assembly 21 is limited to the area from the position of the arm assembly 21 where the elongated section 52 comes into contact with the upper wall section 55a, to the position of the arm assembly 21 where the elongated section 52 comes into contact with the lower wall section 55b.

[0111] In the following description, the position of the arm assembly 21 where the elongated section 52 comes into contact with the upper wall section 55a is referred to as the lower pivot position, and the position of the arm assembly 21 where the elongated section 52 comes into contact with the lower wall section 55b is referred to as the upper pivot position.

[0112] As from Fig. As can be seen in Figure 4, the drive unit 8 also has an elastic element 58.

[0113] The elastic element 58 is positioned between the clamp 18 and the arm 20. The elastic element 58 pre-tensions the arm 20 (arm assembly 21) downwards.

[0114] The elastic element 58, for example, is a helical tension spring.

[0115] An L-shaped spring hook section 24b is provided at the rear end of the structure 24.

[0116] A spring hook screw 60 is provided on the radial section 50 of the projection 22. The spring hook bolt 60 is inserted into a hole 50b of the radial section 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 attached to the radial section 50.

[0117] One end of the elastic element 58 is hooked onto the spring hook section 24b. The other end of the elastic element 58 is hooked into a groove 60a at the tip of the spring hook screw 60.

[0118] Since the elongated section 52 is in contact with the upper wall section 55a, the elastic element 58 exerts a tensile force between the spring hook section 24b and the spring hook screw 60.

[0119] Therefore, if no force is applied to pivot the arm assembly 21 upwards, the arm assembly 21 is in the lower pivot position.

[0120] When the arm assembly 21 is in the lower pivot position, a tensile force is applied between the section of the spring hook 24b and the spring hook screw 60 by the elastic element 58.

[0121] When the arm assembly 21 is located between the lower pivot position and the upper pivot position, the elastic element 58 pre-tensions the arm 20 (arm assembly 21) downwards.

[0122] Fig. Figure 6A is a schematic representation showing the relationship between the drive wheel 14 and the main wheel 2b when the arm assembly 21 is in the lower pivot position.

[0123] As from Fig. As can be seen in Figure 6A, no force is exerted on the arm assembly 21 by the road surface R when the main wheel 2b of the vehicle body 2 and the drive wheel 14 are not in contact with the road surface R. Therefore, the arm assembly 21 is in the lower pivot position.

[0124] When the arm assembly 21 is in the lower pivot position, the lowest section of the drive wheel 14 is located below the lowest section of the main wheel 2b.

[0125] Fig. Figure 6B is a schematic representation 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.

[0126] 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 pivot positions.

[0127] At this point, the elastic element 58 pre-tensions the arm assembly 21, which pivots in the upward / downward direction, downwards. Therefore, the drive wheel 14 is pushed against the road surface R by the tensile force of the elastic element 58. This increases the contact pressure of the drive wheel 14 while simultaneously dampening the vibrations transmitted from the drive wheel 14 to the vehicle body 2.

[0128] In the present embodiment, a straight line L lies parallel to the road surface R when the roller 2c, the main wheel 2b and the drive wheel 14 are in contact with the road surface R. The straight line L is a straight line that passes through the central axis C1, which is the pivot point of the arm assembly 21 and a pivot center C2 of the drive wheel 14.

[0129] The present embodiment of the description "the straight line L lies parallel to the roadway R" has two cases: one case is that the straight line L lies parallel to the roadway R, and the other case is that the straight line L is substantially parallel to the roadway R. The description "the straight line L lies 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.

[0130] In the present embodiment, the position of the arm assembly 21, in which the straight line L is essentially parallel to the road surface R, lies between the lower pivot position and the upper pivot position.

[0131] 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.

[0132] Fig. Figure 7A is a schematic representation of the forces exerted on an arm when a drive wheel 114 is braked during the movement of an electric wheelchair in which the straight line L is not parallel to the road surface R.

[0133] Fig. Figure 7A shows a case in which the electric wheelchair moves in one direction from the pivot point C2 of the drive wheel 114 to the central axis C1 of an arm 120 (moves forward).

[0134] In this case, the drive wheel 114 is braked (regenerative braking or short-circuit braking). Therefore, a tractive force F1 is exerted on a tip 120A of the arm 120 in a direction opposite to the direction of travel by the drive wheel 114. Since the straight line L is not parallel to the road surface R, a force F2 can be generated on the arm 120 at this time in a direction in which the arm 120 rotates upwards.

[0135] When such a force F2 is generated on the arm 120, the contact pressure of the drive wheel 114 can decrease and the drive wheel 114 can oscillate in the upward / downward direction.

[0136] Fig. Figure 7B is a schematic representation showing a force exerted on the arm when the drive wheel is braked during the movement of the electric wheelchair of the present embodiment.

[0137] As from Fig. As can be seen in Figure 7B, the generation of a force in a direction in which the arm 20 rotates upwards can be suppressed, although the traction force is exerted on the arm 20 by the drive wheel 14, when the straight line L is parallel to the road surface R.

[0138] This can reduce the pressure when the drive wheel 14 is in contact with the drive wheel and reduce the vibrations of the drive wheel in the upward / downward direction.

[0139] In the present embodiment, a suitable frictional force can be applied between the arm 20 and the support element 34 by holding the arm 20 and the support element 34 (clamp 18) with the low-friction discs 40 arranged between them. Even if a force is generated in the direction in which the arm 20 rotates upwards, the force can be reduced. Furthermore, it is possible to reduce vibrations generated at the arm 20 and the drive wheel 14 by the frictional force between the arm 20 and the support element 34. [Other embodiments]

[0140] Fig.Figure 8 is a schematic representation showing a clamp 18 of a drive unit 8 according to another embodiment. The present embodiment differs from the embodiment above in that the cutout 30b1 provided in the column 30b is longer in the vertical direction and that a plurality of slots 28c and a plurality of screw holes 28b1 are arranged along the vertical direction.

[0141] With the above configuration of the fastening section 26 of the present embodiment, the position of the superstructure 24 on the vehicle body 2 can be adjusted in height.

[0142] Therefore, the position of the height of the structure 24 can be adjusted so that the straight line L is parallel to the road surface.

[0143] This can reduce the pressure when the drive wheel 14 is in contact with the drive wheel and reduce the vibrations of the drive wheel 14 in the upward / downward direction. [Miscellaneous]

[0144] The embodiments disclosed herein are in every respect illustrative and not limiting.

[0145] The above embodiments represent the case in which the helical tension spring is used as the elastic element 58, but instead of the helical tension spring a rubber ring etc. can also be used.

[0146] The above embodiments represent the case in which the position of the arm assembly 21, in which the straight line L is substantially parallel to the road surface R, lies between the lower pivot position and the upper pivot position, wherein the lower pivot position and the upper pivot position can be in the region of the position of the arm assembly 21 in which the straight line L is substantially parallel to the road surface R.

[0147] In this case, the swivel range of the arm assembly 21 can be limited to the area in which the straight line L is essentially parallel to the road surface R.

[0148] In the above embodiments, the vehicle body 2 is shown with the front and rear wheels (steering casters 2c and main wheels 2b), but the vehicle body 2 can have at least one of the front and rear wheels.

[0149] The above embodiments illustrate the case in which the electrical device for assisting the vehicle 4 is attached to the vehicle body 2, which is a general wheelchair, although the vehicle body 2 may be a transport cart, a trolley, etc., which is not a wheelchair.

[0150] The scope of the present invention is not limited to the above embodiments and includes all modifications made within the framework of equivalents to the configurations set out in the claims. Description of the reference symbols 2 Vehicle body, 4 electric vehicle support devices, 14 drive wheel, 16 Actuator, 18 bracket, 20 arms, 21a Spitze, 21b Basic end, 22 lead, 24 Construction, 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

Claims

Electric vehicle (1) comprising: a vehicle body (2) with a wheel (2b); a clamp (18) attached to the vehicle body (2); an arm (20) held by the clamp (18) such that the arm (20) is pivotable in an upward / downward direction; a drive wheel (14) provided at a tip (21a) of the arm (20); an actuator (16) configured to drive the drive wheel (14);and an elastic element (58) provided between the clamp (18) and the arm (20) and pre-tensioning the arm (20) downwards, the arm (20) having a projection (22) at a base end face of the arm (20) projecting along a direction in the longitudinal direction of the arm (20), and the clamp (18) having an upper wall section (55a) provided above the projection (22) with which the projection (22) comes into contact when the arm (20) oscillates, and a lower wall section (55b) provided below the projection (22) with which the projection (22) comes into contact when the arm (20) oscillates. Electric vehicle (1) according to claim 1, wherein a straight line passing through a pivot center of the arm (20) and a rotation center of the drive wheel (14) when the wheel (2b) and the drive wheel (14) are in contact with a road surface is parallel to the road surface. Electric vehicle (1) according to claim 2, which furthermore has a low-friction element (40) between the clamp (18) and the arm (20). Electric vehicle (1) according to claim 3, wherein the clamp (18) has a support element (34) with a support shaft (36) which holds the arm (20) so that the arm (20) is pivotable, and the low-friction element (40) has a low-friction washer which is provided on an outer circumferential side of the support shaft (36) and is arranged between the arm (20) and the support element (34). Electric vehicle (1) according to claim 1, wherein the vehicle body (2) comprises a wheelchair. Electric vehicle (1) according to claim 1, wherein the clamp (18) has: a superstructure (24) provided by the arm (20); and a fastening section (26) which secures the superstructure (24) to the vehicle body (2) at a predetermined height position, and the predetermined height position is a position in which a straight line passing through a pivot center of the arm (20) and a rotation center of the drive wheel (14) when a wheel of the vehicle body (2) and the drive wheel (14) are in contact with a road surface is parallel to the road surface. Electric vehicle (1) according to claim 1, wherein the clamp (18) has: a superstructure (24) provided by the arm (20); and a fastening section (26) configured to adjust the height of the superstructure to the vehicle body (2).

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