Vehicle electric power assist device for and electric-powered vehicle

Abstract

Provided is a vehicle electric power assist device (4) that is attached to a vehicle, the vehicle electric power assist device (4) comprising: a bracket (36) that is fixed to a vehicle body (2); an arm (38) pivotably provided on the bracket (36); a drive wheel (14) provided at a distal end portion (38a) of the arm (38); an actuator (16) that drives the drive wheel (14); and a brake mechanism (20) that applies a brake to the drive wheel (14) stopped.

Description

Electric assist device for vehicle and electric vehicle

[0001] The present invention relates to an electric assist device for a vehicle and an electric vehicle.

[0002] Patent Document 1 discloses an electric assist device for use with wheelchairs. This electric assist device comprises a main body including a battery, an electric motor, and drive wheels, and an attachment bar. The electric motor drives the drive wheels. The attachment bar is a member for mounting the main body to the body of the wheelchair. The position of the main body mounted to the body via the attachment bar can be switched between a standby position and a drive position. In the standby position, the drive wheels are spaced apart from the road surface. In the drive position, the drive wheels are in contact with the road surface. By driving the drive wheels when in the drive position, the electric assist device assists the wheelchair in traveling.

[0003] Japanese Patent Application Laid-Open No. 2016-150077

[0004] A wheelchair equipped with the above-mentioned conventional power-assisted device travels with the main body fixed in the drive position. In this case, it is considered to press the drive wheels against the road surface to ensure sufficient contact pressure. Pressing the drive wheels against the road surface can reduce the contact pressure of the main wheels of the wheelchair due to the reaction force from pressing the drive wheels against the road surface.

[0005] Some wheelchairs have parking brakes that limit the rotation of the main wheels when the wheelchair is stopped. However, as mentioned above, in wheelchairs equipped with an electrically power-assisted device, the contact pressure of the main wheels decreases, which can reduce the braking force of the parking brake applied to the main wheels. Therefore, measures to supplement the braking force of the parking brake are desired.

[0006] (1) An embodiment is an electric assist device for a vehicle that is mounted on a vehicle. The electric assist device for a vehicle includes a bracket fixed to the vehicle, an arm swingably mounted on the bracket, a drive wheel mounted at the tip of the arm, an actuator that drives the drive wheel, and a brake mechanism that applies a brake to the drive wheel when the drive wheel is stopped.

[0007] (5) From another perspective, the present embodiment is an electric vehicle including a vehicle body, a bracket fixed to the vehicle body, an arm supported by the bracket so as to be swingable up and down, a drive wheel provided at the tip of the arm, an actuator that drives the drive wheel, and a brake mechanism that applies a brake to the drive wheel when the drive wheel is stopped.

[0008] According to the present disclosure, the braking force of the parking brake can be supplemented.

[0009] Fig. 1 is a perspective view of an electric wheelchair according to an embodiment. Fig. 2 is an enlarged view of a parking brake. Fig. 3 is a view showing a drive unit. Fig. 4 is a view showing a bracket and an arm. Fig. 5 is a view showing the overall configuration of a brake mechanism. Fig. 6 is an enlarged perspective view of a switching unit. Fig. 7 is an enlarged view of a first link. Fig. 8 is a view of the arm to which a second holding member and a third link are fixed, as seen from outside the vehicle. Fig. 9 is a view showing the position of the third link.

[0010] First, the contents of the embodiments will be listed and explained. [Outline of the Embodiments] (1) The embodiment is an electric assist device for a vehicle that is attached to a vehicle. This electric assist device for a vehicle includes a bracket fixed to the vehicle, an arm swingably attached to the bracket, a drive wheel attached to the tip of the arm, an actuator that drives the drive wheel, and a brake mechanism that brakes the drive wheel when it is stopped.

[0011] According to the above configuration, the vehicle has a brake mechanism that applies the brakes to the drive wheels when the vehicle is stopped. Therefore, even if the ground contact pressure of the vehicle's wheels decreases and the braking force of the vehicle's parking brake decreases, the braking force of the parking brake can be supplemented by applying the brakes to the drive wheels.

[0012] (2) In the above-described electric assist device for a vehicle, the brake mechanism preferably includes a brake unit provided on the arm for applying a brake to the drive wheels, and a switching unit for switching the brake unit between an activated state and a released state. In this case, the brake unit provided on the arm can be operated via the switching unit to apply a brake to the drive wheels.

[0013] (3) Furthermore, when the vehicle includes wheels, parking brake members for applying the brakes to the wheels, and a moving mechanism for moving the parking brake members to either a parking brake applied position where the brakes are applied to the wheels or a parking brake released position where the brakes are released to the wheels in response to operation by the vehicle operator, the switching unit preferably includes a first holding member fixed to the vehicle, a first link rotatably attached to the first holding member, an engagement unit attached to the first link and engaging with the parking brake members to rotate the first link in response to movement of the parking brake members, and a second link connecting the first link and the brake unit, and moving longitudinally in response to rotation of the first link to switch the state of the brake unit. In this case, the switching unit includes the first link that rotates in response to movement of the parking brake members of the vehicle and the second link that switches the state of the brake unit in response to rotation of the first link, so that the state of the brake unit can be switched in conjunction with operation of the parking brake of the vehicle. This allows the brake unit to be switched into an activated state when the vehicle occupant activates the parking brake of the vehicle.

[0014] (4) In the above-described electric assist device for a vehicle, the brake unit may include a second holding member fixed to the arm, a third link having a connection portion to which the second link is connected and rotatably provided on the second holding member, and a friction member provided on the third link and braking the drive wheel. In this case, it is preferable that the third link be rotatable, in response to movement of the second link, between a first position where the friction member and the drive wheel are separated from each other to achieve the released state, and a second position where the friction member and the drive wheel are in contact with each other to achieve the activated state.

[0015] (5) From another perspective, the present embodiment is an electric vehicle. The electric vehicle includes a vehicle body, a bracket fixed to the vehicle body, an arm supported by the bracket so as to be swingable up and down, a drive wheel provided at the tip of the arm, an actuator that drives the drive wheel, and a brake mechanism that applies a brake to the drive wheel when the vehicle is stopped. With the above configuration, the braking force of a parking brake can be supplemented.

[0016] [Details of the embodiment] A preferred embodiment will now be described with reference to the drawings. [Overall configuration] Figure 1 is a perspective view of an electric wheelchair according to an embodiment. This electric wheelchair 1 has a function of driving the drive wheels of the electric wheelchair 1 when pushed from behind by an operator, thereby assisting the operator.

[0017] The electric wheelchair 1 is an electric vehicle equipped with a vehicle body 2 and a vehicle power assist device 4. The vehicle body 2 is a typical wheelchair, and includes a frame 2a mainly made of metal pipes, a pair of main wheels 2b, and a pair of casters 2c. 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 lower tubes 2a4.

[0018] The pair of rear tubes 2a1 extend in the up-down direction. The pair of rear tubes 2a1 are arranged parallel to each other with a fixed gap in the left-right direction. The pair of lower tubes 2a4 are connected to the lower ends of the pair of rear tubes 2a1. The pair of upper tubes 2a3 are connected to the pair of rear tubes 2a1. The portion of the pair of rear tubes 2a1 where the pair of upper tubes 2a3 are connected is higher than the lower ends. 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 with a fixed gap in the left-right direction. The portion of the pair of lower tubes 2a4 rearward of the rear tubes 2a1 is a tipping bar 2t. The tipping bar 2t is a member that is stepped on by the operator's foot. When the operator steps on the tipping bar 2t, the caster 2c is lifted upward with the main wheel 2b as a fulcrum.

[0019] The pair of front tubes 2a2 extend in the vertical direction and connect the ends of the pair of upper tubes 2a3 and the pair of lower tubes 2a4. Therefore, the pair of front tubes 2a2 are shorter than the pair of rear tubes 2a1.

[0020] The pair of casters 2c are provided at the lower end of the front tube 2a2. The pair of main wheels 2b are provided at the lower end of the rear tube 2a1. The pair of main wheels 2b are provided behind the pair of casters 2c. The pair of main wheels 2b are rear wheels. The pair of casters 2c are front wheels. The vehicle body 2 further has a seat 2d on which a passenger sits, and a backrest 2e. The seat 2d is fixed to the pair of upper tubes 2a3. The backrest 2e is fixed to the pair of rear tubes 2a1.

[0021] The vehicle body 2 further includes a pair of parking brakes 3 on the left and right sides. The pair of parking brakes 3 have the function of applying the brakes to the pair of main wheels 2b. The pair of parking brakes 3 apply the brakes to keep the vehicle body 2 stopped. The parking brakes 3 will be described in detail later. The electric wheelchair 1 is configured by attaching an electric vehicle assist device 4 to a vehicle body 2 that can be used as a wheelchair.

[0022] In the following description, the direction in which the rider faces when riding in the electric wheelchair 1 (the direction in which the backrest 2e faces forward) is referred to as the forward direction, and the opposite direction as the rearward direction. Therefore, the rider rides facing the front of the electric wheelchair 1. Also, the direction facing left from the rider's perspective is referred to as the leftward direction, and the direction facing right from the rider's perspective is referred to as the rightward direction.

[0023] The vehicle electric assist device 4 includes a pair of drive units 8 and a pair of operating devices 10. As shown in FIG. 1 , a pair of protrusions 2a5 are provided at the upper ends of the pair of rear tubes 2a1. The pair of protrusions 2a5 protrude further rearward than the backrest 2e. The pair of operating devices 10 are provided on the pair of protrusions 2a5. Thus, the pair of operating devices 10 are disposed above the left and right sides of the backrest 2e. Each of the pair of operating devices 10 has a grip 12. The grip 12 is movable in the front-rear direction relative to the protrusions 2a5. The operating device 10 further has a potentiometer (not shown). The potentiometer detects the amount of displacement of the grip 12 in the front-rear direction. The operating device 10 provides an output indicating the amount of displacement of the grip 12 to a control device (described later).

[0024] The pair of drive units 8 are fixed to the left and right sides of the frame 2a. The pair of drive units 8 are arranged on the vehicle inboard side of the pair of main wheels 2b. Each of the pair of drive units 8 includes a drive wheel 14 and an actuator 16. The actuator 16 drives the drive wheel 14. The actuator 16 is an in-wheel motor and is provided inside the drive wheel 14. The drive unit 8 will be described in detail later.

[0025] The vehicle electric assist device 4 further includes a control box 18 and a pair of brake mechanisms 20. The control box 18 is a housing for accommodating a battery, a control device for controlling each component, and the like. The battery stores power supplied to the pair of drive units 8 (actuators 16) and each component. The control device has a function of controlling the pair of actuators 16 based on outputs from the pair of operation units 10. As described above, the outputs from the pair of operation units 10 indicate the amount of displacement of the pair of grips 12. The control device controls the pair of actuators 16 based on the amount of displacement of the pair of grips 12 so as to maintain the relative position between the grips 12 and the frame 2a (vehicle body 2). The control device can cause the actuators 16 to drive the drive wheels 14, thereby accelerating or maintaining the speed of the vehicle body 2. The control device can also cause the actuators 16 to perform regenerative braking, short-circuit braking, or the like, thereby braking the drive wheels 14 and decelerating the vehicle body 2.

[0026] For example, when the operator pushes the grip 12 forward, the grip 12 is displaced forward. The control device moves the vehicle body 2 forward based on the output of the pair of operating units 10 so as to return the grip 12 to its original position. Conversely, when the operator pulls the grip 12 rearward, the grip 12 is displaced rearward. The control device moves the vehicle body 2 backward so as to return the grip 12 to its original position. In this way, the control device adjusts the amount of operation of the actuator 16 in response to the operator pushing or pulling the grip 12. In this way, the control device controls the pair of actuators 16 so as to maintain the relative position between the grip 12 and the vehicle body 2.

[0027] The pair of brake mechanisms 20 have the function of applying brakes to the pair of stopped drive wheels 14. The pair of brake mechanisms 20 will be described in detail later.

[0028] [Regarding the Parking Brake] Fig. 2 is an enlarged view of the parking brake 3. A pair of parking brakes 3 are provided in front of a pair of left and right main wheels 2b. Fig. 2 shows the parking brake 3 in front of the right main wheel 2b. The left and right parking brakes 3 have the same configuration. Therefore, only the right parking brake 3 will be described here.

[0029] As shown in FIG. 2 , the parking brake 3 includes a parking brake member 24 and a movement mechanism 26. The parking brake member 24 is a member that generates a braking force by the frictional force between it and the main wheels 2b when pressed against them. The movement mechanism 26 has the function of moving the parking brake member 24 to either a parking brake applied position or a parking brake released position. The parking brake applied position is a position of the parking brake member 24 where the brakes are applied to the main wheels 2b. When the parking brake member 24 is in the parking brake applied position, the parking brake member 24 is pressed against the main wheels 2b and generates a braking force. The parking brake released position is a position of the parking brake member 24 where the brakes on the main wheels 2b are released. When the parking brake member 24 is in the parking brake released position, the parking brake member 24 is separated from the main wheels 2b and does not generate a braking force.

[0030] The movement mechanism 26 includes a lever 28, a first meshing member 30, a second meshing member 32, and a link 34. The movement mechanism 26 is housed in the cover 3a (FIG. 1), but is shown in FIG. 2 with the cover 3a removed. The first meshing member 30 is attached to the stay 25 by a pin 27. The stay 25 is a member fixed to the lower tube 2a4. The cover 3a is also fixed to the stay 25. The first meshing member 30 is attached to the stay 25 so as to be rotatable about the pin 27. The lever 28 is fixed to the first meshing member 30. The lever 28 extends upward from the first meshing member 30. The lever 28 includes a grip portion 28a for operation by the occupant. The first meshing member 30 rotates in response to operation by the occupant. The first meshing member 30 also includes a tooth portion 30a that meshes with the second meshing member 32. The first meshing member 30 is a partial gear having a toothed portion 30a. The first meshing member 30 is a gear with the pin 27 as its center.

[0031] The second meshing member 32 has teeth 32a that mesh with the teeth 30a. In FIG. 2, the teeth 30a, 32a are covered by a plate-shaped cover. The second meshing member 32 is fixed to a link 34. The link 34 is attached to the stay 25 by a pin 33. The pin 33 is fixed to the stay 25 via the cover 3a (FIG. 1). The link 34 is attached to the stay 25 so as to be rotatable around the pin 33. Here, the second meshing member 32 is a partial gear that rotates around the pin 33. Therefore, when the first meshing member 30 rotates, the second meshing member 32 and the link 34 rotate around the pin 33.

[0032] The parking brake member 24 is provided at the tip 34a of the link 34. In FIG. 2, the parking brake member 24 is separated from the main wheel 2b. Therefore, the parking brake member 24 is located in the parking brake release position. When the lever 28 is tilted rearward (in the direction of the arrow on the drawing) from the state shown in FIG. 2, the first meshing member 30 rotates downward. Accordingly, the second meshing member 32 and the link 34 also rotate. The rotation of the link 34 moves the parking brake member 24 rearward (in the direction of the arrow on the drawing). As a result, the parking brake member 24 moves to the parking brake activation position and is pressed against the main wheel 2b. In this way, the parking brake 3 can receive operation from the occupant via the lever 28 and activate or release the brake in accordance with the received operation.

[0033] [Configuration of the Drive Unit] Fig. 3 is a diagram showing the drive unit 8. Fig. 3 shows the drive unit 8 provided on the right side of the frame 2a. The left and right drive units 8 have the same configuration. Therefore, only the right drive unit 8 will be described here.

[0034] In addition to the drive wheel 14 and the actuator 16, the drive unit 8 further includes a bracket 36 and an arm 38. The bracket 36 is a plate-shaped member. The bracket 36 is fixed to the lower tube 2a4.

[0035] FIG. 4 is a diagram illustrating the bracket 36 and the arm 38. Referring to FIGS. 3 and 4, the bracket 36 includes a main body 40, a front fixing portion 41, and a rear fixing portion 42. The main body 40 is provided with the arm 38. The front fixing portion 41 includes a rectangular plate-shaped portion 41a connected to the main body 40 and a semi-cylindrical member 41b. One end of the semi-cylindrical member 41b is inserted into a slit 41c formed in the plate-shaped portion 41a and fixed to the plate-shaped portion 41a. The other end of the semi-cylindrical member 41b is fixed to the plate-shaped portion 41a by a bolt 41d. The lower tube 2a4 passes between the plate-shaped portion 41a and the semi-cylindrical member 41b (see FIG. 3). The lower tube 2a4 is sandwiched between the plate-shaped portion 41a and the semi-cylindrical member 41b. This fixes the front fixing portion 41 to the lower tube 2a4.

[0036] The rear fixing portion 42 has a protruding portion 42a that protrudes from the edge of the main body portion 40 toward the inside of the vehicle, and a pillar portion 42b that extends upward from the tip of the protruding portion 42a. The upper surface of the protruding portion 42a abuts against the lower tube 2a4 (see FIG. 3). A notch 42b1 is provided at the tip of the pillar portion 42b. A threaded portion 5a protruding from the hub 5 of the main wheel 2b fixed to the rear tube 2a1 is fixed to the notch 42b1 (see FIG. 3). The pillar portion 42b is sandwiched between the hub 5 and a nut 5b that threads onto the threaded portion 5a. In this way, the rear fixing portion 42 is fixed to the rear tube 2a1. In this way, the front fixing portion 41 and the rear fixing portion 42 fix the main body portion 40 to the frame 2a.

[0037] The arm 38 is attached to the bracket 36 by a shaft 37. The shaft 37 is fixed to a main body 40 of the bracket 36. The shaft 37 passes through the arm 38 and supports the arm 38 so that it can swing up and down. Therefore, the arm 38 can swing around the shaft 37.

[0038] A notch 38a1 is provided in the arm tip 38a of the arm 38. An axle extending from the drive wheel 14 is fixed to the notch 38a1. As a result, the drive wheel 14 and the actuator 16 are provided at the arm tip 38a of the arm 38. Therefore, when the arm 38 swings up and down, the drive wheel 14 and the actuator 16 move up and down. In addition, members of the brake mechanism 20 are fixed to the arm 38. These members will be described later.

[0039] A rotor (not shown) of the actuator 16 can rotate integrally with the drive wheel 14. A stator (not shown) of the actuator 16 is fixed to the arm 38. This allows the actuator 16 to drive the drive wheel 14 to rotate.

[0040] The drive unit 8 also includes an elastic member (not shown). The elastic member is provided between the bracket 36 and the arm 38. The elastic member biases the arm 38 downward. This presses the drive wheel 14 against the road surface. As a result, the contact pressure of the drive wheel 14 can be increased.

[0041] [Regarding the Brake Mechanism] Fig. 5 is a diagram showing the overall configuration of the brake mechanism 20. A pair of brake mechanisms 20 are provided associated with a pair of left and right main wheels 2b. Fig. 5 is a view of the brake mechanism 20 provided on the right main wheel 2b as seen from the inside of the vehicle. The left and right brake mechanisms 20 have the same configuration. Therefore, only the right brake mechanism 20 will be described here.

[0042] 5 , the brake mechanism 20 includes a brake unit 46 and a switching unit 48. The brake unit 46 is provided on the arm 38 and has a function of applying a brake to the drive wheels 14 when the wheels are stopped. The switching unit 48 has a function of switching the brake unit 46 between an activated state and a released state. The activated state is a state in which the brake unit 46 applies a brake to the drive wheels 14. The released state is a state in which the brake unit 46 releases the brake from the drive wheels 14.

[0043] The switching unit 48 includes a first holding member 50, a first link 52, and a second link 54. The first holding member 50 is fixed to the vehicle body 2. The first link 52 is rotatably provided on the first holding member 50. The brake unit 46 includes a second holding member 60, a third link 62, and a friction member 64.

[0044] The second link 54 is a wire. The exterior of the second link 54 is covered by a tube 55. The second link 54 is movable along the longitudinal direction within the tube 55. The second link 54 connects the first link 52 of the switching unit 48 and the third link 62 of the brake unit 46.

[0045] [Regarding the Switching Portion] Figure 6 is an enlarged perspective view of the switching portion 48. As shown in Figure 6, the first holding member 50 is a plate-shaped member and is fixed to the stay 25. In other words, it is fixed to the parking brake 3 via the stay 25. The first holding member 50 has a main body portion 50a and a wire guide 50b. The main body portion 50a is a plate-shaped portion fixed to the stay 25. The wire guide 50b is bent from the upper edge of the main body portion 50a and protrudes inward and forward of the vehicle. The wire guide 50b guides the second link 54. It also holds the tube 55.

[0046] The first link 52 is provided on the first holding member 50. The first link 52 is attached to the first holding member 50 by a shaft 51. The shaft 51 is fixed to the main body 50a of the first holding member 50. The shaft 51 passes through the first link 52 and rotatably supports the first link 52. Therefore, the first link 52 is rotatable around the shaft 51.

[0047] The first link 52 has a first arm portion 52a, a second arm portion 52b, and a connecting portion 52c. The first arm portion 52a extends in the front-to-rear direction. One end 54a of the second link 54 is connected to the front end of the first arm portion 52a. The connecting portion 52c is connected to the rear end of the first arm portion 52a. The rear end of the first arm portion 52a and the upper end of the second arm portion 52b are connected to the connecting portion 52c. As a result, the connecting portion 52c connects the first arm portion 52a and the second arm portion 52b. The second arm portion 52b extends in the up-down direction. Therefore, the first link 52 has an L-shape formed by the first arm portion 52a and the second arm portion 52b. The shaft 51 also passes through the upper end of the second arm portion 52b.

[0048] Fig. 7 is an enlarged view of the first link 52. As shown in Fig. 7, the second arm portion 52b has a through-hole 52b1 through which the shaft 51 passes. An engagement portion 53 is provided at the lower end of the second arm portion 52b. The engagement portion 53 is a member that engages with the parking brake member 24 of the parking brake 3. The engagement portion 53 has a protrusion 53a and a grip portion 53b. The protrusion 53a protrudes from the lower end of the second arm portion 52b toward the outside of the vehicle. The grip portion 53b is provided at the tip of the protrusion 53a. The grip portion 53b has a recess 53b1. The parking brake member 24 fits into the recess 53b1. As a result, the parking brake member 24 is gripped by the grip portion 53b.

[0049] The gripping portion 53b grips the parking brake member 24, causing the engaging portion 53 to engage with the parking brake member 24. Therefore, when the parking brake member 24 moves, the engaging portion 53 also moves in response to the movement, causing the first link 52 to rotate. In other words, the engaging portion 53 rotates the first link 52 in response to the movement of the parking brake member 24.

[0050] 6 , the second link 54 is a wire as described above, and is a member that connects the first link 52 and the brake unit 46. The second link 54 moves longitudinally within the tube 55 in response to the rotation of the first link 52. Therefore, the second link 54 moves longitudinally in response to the movement of the parking brake member 24. In other words, the second link 54 moves longitudinally in response to the operation of the lever 28 by the occupant.

[0051] 3 and 4, the brake unit 46 includes the second holding member 60, the third link 62, and the friction member 64, as described above. The second holding member 60 is a plate-shaped member and is fixed to the arm 38. The third link 62 is rotatably provided on the second holding member 60.

[0052] FIG. 8 is a view of the arm 38 to which the second retaining member 60 and the third link 62 are fixed, as seen from outside the vehicle. As shown in FIG. 8 , the arm 38 is a plate-shaped member and includes an arm body 70 extending in the fore-and-aft direction, a front protrusion 72, and an upper protrusion 74. The tip of the arm body 70 is the arm tip portion 38a, which is provided with the above-mentioned notch portion 38a1. FIG. 8 also shows the shaft 37 that passes through the arm 38, as well as the bolt 37a and spacer 37b. The spacer 37b is interposed between the arm 38 (arm body 70) and the bracket 36 ( FIGS. 3 and 4 ) and serves to determine the distance between the arm 38 and the bracket 36. The bolt 37a is threadedly engaged with the shaft 37. The bolt 37a clamps the arm 38 and the bracket 36.

[0053] As shown in Figure 8, the second holding member 60 is fixed to the front protrusion 72 and the upper protrusion 74 of the arm 38. The second holding member 60 is fixed to the front protrusion 72 by a bolt 61a. The bolt 61a is threaded into a screw hole 72a provided in the front protrusion 72. The second holding member 60 is fixed to the upper protrusion 74 by a bolt 61b. The bolt 61b is threaded into a screw hole 74a provided in the upper protrusion 74. The second holding member 60 and the arm 38 may be formed integrally.

[0054] Furthermore, the third link 62 is provided on the second holding member 60. Therefore, the second holding member 60 and the third link 62 are fixed to the arm 38.

[0055] 3, 4, and 8, the second holding member 60 has a main body portion 60a, a wire guide 60b, and a lower arm 60c. The main body portion 60a is a plate-shaped portion on which the third link 62 is provided. The wire guide 60b protrudes upward from the front edge of the main body portion 60a. The tip of the wire guide 60b is provided with a bent portion 60b1 that is bent toward the inside of the vehicle. The bent portion 60b1 holds the second link 54 and the tube 55. The lower arm 60c extends downward from the front edge of the main body portion 60a. The tip of the lower arm 60c is fixed to the front protrusion 72 of the arm 38.

[0056] The third link 62 is attached to the second holding member 60 by a shaft 78. The shaft 78 passes through the main body 60a of the second holding member 60. A bolt 79 (see FIG. 8 ) is threadedly engaged with the tip of the shaft 78. The shaft 78 is fixed to the second holding member 60 by the bolt 79. The shaft 78 also passes through the third link 62 and supports the third link 62 so that it can rotate.

[0057] The third link 62 has a link body 62a and a connecting portion 62b. The link body 62a is shaped like a flat bar. The shaft 78 passes through the link body 62a. Therefore, the link body 62a is rotatably supported by the shaft 78. The second link 54 is connected to the connecting portion 62b. The connecting portion 62b is provided at one end of the link body 62a. The connecting portion 62b has a bent portion 62b1 bent toward the inside of the vehicle. The other end 54b of the second link 54 is connected to the bent portion 62b1. A spring 80 is provided between the bent portion 60b1 and the bent portion 62b1. The second link 54 is inserted into the inner peripheral side of the spring 80. The spring 80 biases the bent portion 60b1 and the bent portion 62b1 in a direction separating them.

[0058] The friction member 64 is provided at the other end of the link body 62a. The friction member 64 brakes the drive wheel 14 by the friction force generated by contact with the drive wheel 14. The friction member 64 is a flat bar-shaped member that protrudes from the link body 62a toward the inside of the vehicle. As shown in Figure 4, the friction member 64 has a protruding dimension that allows it to contact almost the entire width of the contact surface of the drive wheel 14.

[0059] Here, as described above, the other end 54b of the second link 54 is connected to the connection portion 62b. Therefore, when the second link 54 moves in the longitudinal direction, the third link 62 rotates around the shaft 78. In other words, the third link 62 rotates in response to the movement of the second link 54. The third link 62 is rotatable between a first position and a second position.

[0060] FIG. 9 is a diagram showing the position of the third link 62. (a) in FIG. 9 shows the third link 62 in the first position. (b) in FIG. 9 shows the third link 62 in the second position. As shown in (a) in FIG. 9, when the third link 62 is in the first position, the friction member 64 and the drive wheel 14 are separated. This causes the brake unit 46 to be in a released state. As shown in (b) in FIG. 9, when the third link 62 is in the second position, the friction member 64 and the outer circumferential surface of the drive wheel 14 come into contact. This causes the brake unit 46 to be in an activated state. When the third link 62 is in the second position, a frictional force is generated between the friction member 64 and the outer circumferential surface of the drive wheel 14. This frictional force brakes the drive wheel 14.

[0061] [Regarding Operation of the Brake Mechanism] As described above, the second link 54 of the switching unit 48 moves in the longitudinal direction in response to the movement of the parking brake member 24 of the vehicle body 2. Furthermore, the third link 62 of the brake unit 46 rotates between a first position and a second position in response to the movement of the second link 54. In other words, the brake unit 46 switches between an activated state and a released state in response to the movement of the second link 54. Therefore, the brake unit 46 switches between an activated state and a released state in response to the movement of the parking brake member 24.

[0062] When the parking brake member 24 is in the parking brake release position (see FIG. 2), the third link 62 is in the first position. Here, when the parking brake member 24 moves from the parking brake release position to the parking brake applied position, the third link 62 moves from the first position to the second position. Therefore, when the parking brake member 24 is in the parking brake release position, the brake unit 46 is in the released state. On the other hand, when the parking brake member 24 is in the parking brake applied position, the brake unit 46 is in the applied state.

[0063] In other words, when the occupant operates the lever 28 to move the position of the parking brake member 24 from the parking brake release position to the parking brake applied position, the brake unit 46 switches from the released state to the applied state. Conversely, when the occupant operates the lever 28 to move the position of the parking brake member 24 from the parking brake applied position to the parking brake released position, the brake unit 46 switches from the applied state to the released state.

[0064] The bent portion 60b1 and the bent portion 62b1 are biased in the direction of separating them by the spring 80. Therefore, the third link 62 is normally held in the first position, and the brake portion 46 is held in the released state.

[0065] According to the above configuration, the vehicle has a brake mechanism 20 that applies the brakes to the stopped drive wheels 14. Therefore, even if the drive wheels 14 are pressed against the road surface and the ground contact pressure of the main wheels 2b of the vehicle body 2 decreases, thereby reducing the braking force of the parking brake 3, the braking force of the parking brake 3 can be supplemented by applying the brakes to the drive wheels 14.

[0066] In addition, in this embodiment, the brake mechanism 20 is equipped with a brake unit 46 provided on the arm 38 and a switching unit 48 that switches the brake unit 46 between an activated state and a released state, so that the brake unit 46 provided on the arm 38 can be operated via the switching unit 48 to brake the drive wheel 14.

[0067] Furthermore, the switching unit 48 includes a first link 52 that rotates in response to movement of the parking brake member 24, and a second link 54 that switches the state of the brake unit 46 in response to the rotation of the first link 52, so that the state of the brake unit 46 can be switched in conjunction with the operation of the parking brake 3 of the vehicle body 2. As a result, when a passenger activates the parking brake 3 of the vehicle body 2, the brake unit 46 can also be switched to an activated state.

[0068] [Others] The embodiments disclosed herein are illustrative in all respects and are not limiting. For example, in the above embodiment, the brakes are applied to the drive wheels 14 by bringing the friction members 64 into contact with the outer peripheral surfaces of the drive wheels 14. However, the brakes may be applied by providing a rotating member that rotates integrally with the drive wheels 14 and bringing the friction members into contact with this rotating member. Alternatively, the brakes may be applied by providing a plurality of recesses along the circumferential direction on the side surfaces of the drive wheels 14 and inserting rod-shaped anti-rotation members into the recesses.

[0069] In addition, in the above embodiment, the vehicle body 2 is a typical wheelchair and the vehicle power assist device 4 is attached to the vehicle body 2, but the vehicle body 2 may be a dolly, wagon, etc., other than a wheelchair. The scope of the present invention is not limited to the above embodiment, and includes all modifications within the scope of equivalents to the configurations described in the claims.

[0070] REFERENCE SIGNS LIST 1 Electric wheelchair (electric vehicle) 2 Vehicle body 2b Main wheel (wheel) 4 Vehicle electric assist device 14 Drive wheel 16 Actuator 20 Brake mechanism 24 Parking brake member 26 Movement mechanism 36 Bracket 38 Arm 38a Arm tip 46 Brake section 48 Switching section 50 First holding member 52 First link 53 Engagement section 54 Second link 60 Second holding member 62 Third link 62b Connection section 64 Friction member

Claims

1. An electric assist device for a vehicle that is mounted on a vehicle, A bracket fixed to the vehicle; an arm pivotably attached to the bracket; A drive wheel provided at a tip end of the arm; An actuator that drives the drive wheels; a brake mechanism that applies a brake to the drive wheels when the drive wheels are stopped, The brake mechanism includes: a brake unit provided on the arm and configured to apply a brake to the drive wheel; A switching unit that switches the brake unit between an activated state and a released state, The vehicle is Wheels and a parking brake member for applying the brakes to the wheels, and a moving mechanism for moving the parking brake member to either a parking brake applied position where the wheels are braked or a parking brake released position where the wheels are released in response to an operation by an operator of the vehicle, The switching unit is A first retaining member fixed to the vehicle; a first link rotatably provided on the first holding member; an engagement portion provided on the first link and engaging with the parking brake member to rotate the first link in response to movement of the parking brake member; a second link that connects the first link and the brake unit and moves in a longitudinal direction in response to rotation of the first link to switch the state of the brake unit; An electric assist device for vehicles.

2. The brake unit includes: A second holding member fixed to the arm; a third link having a connection portion to which the second link is connected and rotatably provided on the second holding member; a friction member provided on the third link and configured to brake the drive wheel; The third link is rotatable between a first position where the friction member and the drive wheel are separated from each other to be in the released state and a second position where the friction member and the drive wheel are in contact with each other to be in the activated state in response to movement of the second link. The electric assist device for a vehicle according to claim 1.

3. A vehicle body, A bracket fixed to the vehicle body; an arm supported by the bracket so as to be swingable in the vertical direction; A drive wheel provided at a tip end of the arm; An actuator that drives the drive wheels; a brake mechanism that applies a brake to the drive wheels when the drive wheels are stopped, The brake mechanism includes: a brake unit provided on the arm and configured to apply a brake to the drive wheel; A switching unit that switches the brake unit between an activated state and a released state, The vehicle body includes: Wheels and a parking brake member for applying the brakes to the wheels, and a moving mechanism for moving the parking brake member to either a parking brake applied position where the wheels are braked or a parking brake released position where the wheels are released in response to an operation by an operator of the vehicle body, The switching unit is A first holding member fixed to the vehicle body; a first link rotatably provided on the first holding member; an engagement portion provided on the first link and engaging with the parking brake member to rotate the first link in response to movement of the parking brake member; a second link that connects the first link and the brake unit and moves in a longitudinal direction in response to rotation of the first link to switch the state of the brake unit; Electric vehicle.

4. The brake unit includes: A second holding member fixed to the arm; a third link having a connection portion to which the second link is connected and rotatably provided on the second holding member; a friction member provided on the third link and configured to brake the drive wheel; The third link is rotatable between a first position where the friction member and the drive wheel are separated from each other to be in the released state and a second position where the friction member and the drive wheel are in contact with each other to be in the activated state in response to movement of the second link. The electric vehicle according to claim 3.