Electric assist device for manual wheelchairs

Abstract

This technology enables the simple electrification of manual wheelchairs without requiring extensive modifications. [Solution] The electric assist device 1 is attached to the wheel 2 of a manual wheelchair. The electric assist device 1 mainly consists of a mounting bracket 11 with a tubular section 16 having a roughly C-shaped cross-section and a hollow passage 15 curved in an arc shape through which the handrim 5 can pass; a drive unit 12 supported above the mounting bracket 11; and a battery unit 13 supported below the mounting bracket 11. These three components are integrated. The battery unit 13 is located on the inner circumference side of the handrim 5. The entire device is attached by press-fitting the tubular section 16 with a roughly C-shaped cross-section into the handrim 5.

Description

Technical Field

[0004] , , , , , , ,

[0006] , , , , , ,

[0005] , , , , , , ,

[0001] This invention relates to an electric assist device for a manual wheelchair that realizes simple electrification by being attached to a general manual wheelchair.

Background Art

[0002] Attempts have been made to simply electrify general manual wheelchairs. For example, Patent Document 1 discloses an electric assist device that rotates a friction roller in contact with the wheels of a manual wheelchair by an electric motor to drive the manual wheelchair.

[0003] In the electric assist device of this Patent Document 1, the friction roller is supported by the frame of the manual wheelchair, and a battery and an operation joystick are attached to the frame of the manual wheelchair at a position different from this friction roller.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The electric assist device of Patent Document 1 has a configuration in which the friction roller, the battery, and the joystick are individually attached to the frame of the manual wheelchair, and relatively large-scale modification is required. That is, it is suitable for the case of permanently modifying a manual wheelchair into an electric wheelchair based on the manual wheelchair. However, it is not suitable for applications that temporarily electrify a manual wheelchair without large-scale modification.

Means for Solving the Problems

[0006] This invention is an electric assist device attached to the wheels of a manual wheelchair, A mounting bracket is attached to the handrim, having a hollow passage section curved in an arc shape through which the handrim can pass, and the handrim is slidably fitted into the hollow passage section. A drive unit having a first housing supported by the above-mentioned mounting bracket, a drive roller that contacts the outer surface of the wheel, and an electric motor that drives the drive roller, A battery unit having a second housing supported by the above-mentioned mounting bracket and containing a battery, It is composed of the following features.

[0007] In this configuration, the drive unit, battery unit, and mounting bracket that constitute the electric assist device are integrated, and the entire unit is supported by the manual wheelchair by attaching the mounting bracket to the handrim of the manual wheelchair. The drive roller of the drive unit rotates due to the electric motor, transmitting rotational torque to the wheel. The reaction force acting on the electric assist device at this time is supported by the user sitting in the wheelchair holding the electric assist device with their hands. During movement, the handrim, which rotates together with the wheel, passes through the hollow passage of the mounting bracket. [Effects of the Invention]

[0008] This invention makes it possible to easily electrify a manual wheelchair without requiring extensive modifications to the manual wheelchair. [Brief explanation of the drawing]

[0009] [Figure 1] A side view showing an electric assist device according to one embodiment, mounted on the wheel of a manual wheelchair. [Figure 2] The same as above view. [Figure 3] Also a front view. [Figure 4] A side view showing an enlarged view of the main part of Figure 1. [Figure 5] A front view showing an enlarged view of the main parts of Figure 3. [Figure 6] Cross-sectional view along line AA in Figure 4. [Figure 7]Diagram illustrating the electric motor and drive roller. [Figure 8] Diagram illustrating a gearbox. [Figure 9] Side view of the mounting bracket and battery unit, excluding the drive unit. [Figure 10] The same as above view. [Figure 11] Also a front view. [Figure 12] Cross-sectional view along line BB in Figure 10. [Figure 13] A perspective view showing the operating switches on the drive unit. [Figure 14] A flowchart illustrating the driving control system. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of this invention will be described in detail with reference to the drawings. Figures 1 to 3 show the electric assist device 1 of one embodiment mounted on the wheel 2 of a manual wheelchair. The entire manual wheelchair is not shown, and only one wheel 2 (for example, the right side), which is the so-called rear wheel, is shown in Figures 1 to 3. The manual wheelchair has a general configuration, with a seat section where the user sits between the pair of wheels 2, and a pair of small-diameter front wheels at the front of the frame that supports the seat section and the wheels 2.

[0011] The wheel 2 is rotatably supported around the axle 3, and a handrim 5 is provided on the outside of the wheel 2 for the user to rotate the wheel 2 by hand. The handrim 5 is constructed by connecting metal tubes or metal rods with a circular cross-section in a ring shape, and is positioned slightly outside the wheel 2 and parallel to the wheel 2, and has a diameter slightly smaller than the outer diameter of the wheel 2. It is fixed to the wheel 2 via a plurality of connecting pieces 6 provided at equal angular intervals.

[0012] An electric assist device 1 according to an embodiment is configured to be attached to a handrim 5 and drive an adjacent wheel 2, and is provided for each of the left and right wheels 2. The figure illustrates the electric assist device 1 for the right wheel 2, and the electric assist device for the left wheel has a symmetrical shape. Here, the electric assist devices 1 provided on the left and right in this way are not fixed in the circumferential direction when mounted on the handrim 5, and the user sitting on the seat part supports the electric assist device 1 with both hands in the circumferential direction. That is, when the electric assist device 1 drives the wheel 2, the user supports the reaction force acting on the electric assist device 1. In FIGS. 1 to 3, the electric assist device 1 is depicted at the uppermost part of the wheel 2 on the premise that the user is supporting it by hand.

[0013] In the following description of the electric assist device 1, following the concepts of front-rear, left-right, and up-down of a manual wheelchair, the X direction shown in FIGS. 1 and 2 will be referred to as the "front-rear" direction, the Y direction as the "left-right" direction or "width" direction, and the Z direction as the "up-down" direction. Also, it is assumed that the electric assist device 1 is located at the uppermost part of the wheel 2 as shown in FIG. 1.

[0014] As shown in FIGS. 4 and 5, an electric assist device 1 according to an embodiment includes a mounting bracket 11 for attaching the entire electric assist device 1 to the handrim 5, a drive unit 12 for driving the wheel 2, and a battery unit 13 serving as a power source, and these three are integrated. The drive unit 12 has a drive unit housing 31 made of a hard synthetic resin as a first housing. The drive unit housing 31 has a rectangular box shape with relatively similar front-rear and left-right dimensions and is located on the outer peripheral side of the handrim 5. The battery unit 13 has a battery unit housing 32 made of the same hard synthetic resin as a second housing. The battery unit housing 32 has an elongated box shape in the front-rear direction and is located on the inner peripheral side of the handrim 5.

[0015] As shown in Figures 9 to 12, the mounting bracket 11 is mainly composed of a tubular portion 16 with a circular cross-section that forms a hollow passage 15 curved in an arc shape through which the handrim 5 can pass. The tubular portion 16 is made of a hard synthetic resin with appropriate elasticity and extends forward and backward while curving in an arc shape with a curvature corresponding to the curvature of the handrim 5, as shown in Figure 9, and has a roughly C-shaped cross-section with an open side portion facing the wheel 2, as shown in Figure 11. Because the tubular portion 16 has a roughly C-shaped cross-section, it is possible to press-fit the tubular portion 16 into the handrim 5 by utilizing the elasticity of the resin material. In the pressed-fit state, the opening width of the side portion is smaller than the diameter of the handrim 5, so the mounting bracket 11 will not naturally fall off the handrim 5. The inner diameter of the tubular section 16, which has a roughly C-shaped cross-section, that is, the diameter of the hollow passage section 15, is set to be slightly larger than the diameter of the handrim 5, allowing the handrim 5 to pass through the hollow passage section 15 in the circumferential direction. In other words, the mounting bracket 11 is configured to move freely in the circumferential direction relative to the handrim 5.

[0016] As shown in Figures 9 and 10, a notch 17 is provided in the center of the tubular portion 16 in the longitudinal direction (front-to-back direction) over a relatively large length range to avoid interference with the drive unit housing 31. Within the range of this notch 17, the tubular portion 16 has a shape in which the upper part is cut off, leaving only the lower part (inner circumference) of the C-shaped cross-section. The range of this notch 17 roughly corresponds to the front-to-back dimension of the drive unit housing 31. By providing the notch 17 in this way, the part that is pressed into the handrim 5 is divided into two parts, making it easier to press it into the handrim 5 and reducing the sliding resistance that occurs between the drive unit 12 and the handrim 5 during driving. In addition, it becomes possible to lower the height position of the drive unit 12.

[0017] A pair of drive unit mounting portions 18 for supporting the drive unit 12 are provided adjacent to the front and rear ends of the notch 17 of the tubular portion 16. As shown in Figure 11, each drive unit mounting portion 18 is equipped with a circular shaft support hole 20, and each of the pair of front and rear cylindrical boss portions 33 (see Figure 5) formed on the drive unit housing 31 is configured to fit into the shaft support hole 20 of the pair of drive unit mounting portions 18. Specifically, each drive unit mounting portion 18 consists of a fixing piece 18a molded integrally with the tubular portion 16 and a cap 18b fixed to the fixing piece 18a by a screw 19 (see Figure 9). The boss portion 33 is fixed by adjusting the angle of the drive unit 12 relative to the mounting bracket 11 and then tightening the screw 19. In other words, the inner diameter of the shaft support hole 20 is slightly smaller than the outer diameter of the boss portion 33. The pair of boss portions 33 and the corresponding pair of shaft support holes 20 are configured around a single common center line along the tangential direction of the handrim 5. Therefore, when the screw 19 is loosened, the angle of the drive unit 12 can be adjusted with the above center line as the center of rotation.

[0018] As shown in Figure 6, the drive unit 12 has a configuration in which a pair of electric motors 35, a drive roller 36, and a reduction gear 37 between them are housed in a drive unit housing 31. As shown in Figures 7 and 8, the pair of electric motors 35 are arranged in a front-to-back arrangement, and one drive roller 36 rotates via a reduction gear 37 consisting of the pinion 37a of each electric motor 35 and a relatively large-diameter gear 37b on the drive roller 36 side. As shown in Figure 6, the drive roller 36 is in contact with the outer circumferential surface of the wheel 2, thereby transmitting rotational torque from the drive roller 36 to the wheel 2. As mentioned above, the drive unit 12 is supported with respect to the mounting bracket 11 so that its angle can be adjusted, and by adjusting the angle in accordance with the actual position of the outer circumferential surface of the wheel 2 relative to the handrim 5, it is possible to reliably ensure that the drive roller 36 is in contact with the outer circumferential surface of the wheel 2.

[0019] The drive roller 36 is made of hard synthetic resin or metal, and its outer surface is treated with an appropriate anti-slip finish. As shown in Figure 6, the drive roller 36 is rotatably supported at both ends of its rotating shaft by the drive unit housing 31 via bearing members.

[0020] In the drive unit 12, as shown in Figure 6, the electric motor 35, the drive roller 36, and the reduction gear 37 between them are arranged so that their respective axes of rotation are parallel to each other, and the electric motor 35 and the drive roller 36 are located on opposite sides of the reduction gear 37. Furthermore, each axis of rotation (for example, the centerline 36a of the axis of rotation of the drive roller 36 is shown in Figure 6) is inclined so that the outer side in the width direction of the manual wheelchair is relatively lower. For example, it is inclined at about 30 to 60° with respect to the horizontal plane. This inclination of the axis of rotation of the drive unit 12 makes it possible to relatively reduce both the upward and lateral protrusion of the drive unit 12 from the wheels 2 of the manual wheelchair. In other words, if the axis of rotation were horizontal, the lateral protrusion of the drive unit 12 would be large. Also, if the electric motor 35 and the drive roller 36 were not arranged in series but stacked vertically, the upward protrusion would be large.

[0021] The uppermost part of the drive unit housing 31 covering the drive roller 36 has a generally flat shape that follows a horizontal plane, as shown in Figure 6. Also, as shown in Figures 2 and 4, a part of the front end of the drive unit housing 31 protrudes forward of the drive roller 36, forming a grip portion 31a that is easy for the user to hold. As shown in Figure 13, an operation switch 38 is provided on the side of the grip portion 31a. In one embodiment, the operation switch 38 is of the push-button type and is positioned so that it can be pressed by the thumb of a hand placed on the grip portion 31a. Furthermore, as will be described later, the drive unit 12 is equipped with a gravity sensor (not shown) at an appropriate position for switching between forward and reverse movement.

[0022] As shown in Figures 9 to 12, the battery unit 13, which has a battery unit housing 32, is supported by being suspended from a mounting bracket 11, which mainly consists of an arc-shaped tubular portion 16. The battery unit housing 32 has a rectangular parallelepiped shape that is long in the front-to-back direction, with a front-to-back length dimension corresponding to the chord of the arc of the tubular portion 16. Inside it, as shown in Figures 6 and 12, a plurality of cylindrical batteries 39 are housed, arranged along the longitudinal direction of the battery unit housing 32. In the illustrated example, a total of 12 batteries 39 are housed in a 2 × 2 × 3 configuration. In a preferred embodiment, the batteries 39 are rechargeable secondary batteries. A circuit board 40, which is divided into several parts, is also housed inside the battery unit housing 32. As shown in Figure 12, the battery unit housing 32 is equipped with an openable and closable battery cover 41 at the bottom for replacing the batteries 39.

[0023] Furthermore, as shown in Figures 11 and 6, the battery unit housing 32 (battery cover 41) is equipped with two projections 42 that extend long in the front-to-back direction at its bottom. These two projections 42 allow the electric assist device 1, when removed from the manual wheelchair and placed on the floor, to remain upright without tipping over.

[0024] As shown in Figures 12 and 9, the mounting bracket 11 and the battery unit housing 32 are connected to each other via a pair of rail sections 44 so as to be slidable in the left-right direction (i.e., in the axial direction of the wheel 2). The rail section 44 consists of a convex rail section 44a molded as part of a synthetic resin molded product on the battery unit housing 32 side to have a substantially T-shaped cross-section, and a concave rail section 44b having a substantially T-shaped groove that slidably engages with the convex rail section 44a. As shown in Figure 12, the concave rail section 44b is molded integrally with the tubular section 16 of the mounting bracket 11 and is molded as a highly rigid part that is thicker than the wall thickness of the tubular section 16. As shown in Figure 9, the pair of rail sections 44 are located in front of and behind, respectively, the pair of drive unit mounting sections 18 that support the drive unit housing 31. The mounting bracket 11 and the battery unit housing 32 do not interfere with each other in areas other than the pair of rail sections 44.

[0025] As described above, the battery unit housing 32 is supported by the mounting bracket 11 via a pair of rail sections 44, allowing for adjustment of the position (left-right position) of the battery unit housing 32 relative to the mounting bracket 11 to match the distance between the handrim 5 and the wheel 2. This allows for adjustment of the clearance between the battery unit housing 32 and the wheel 2, for example. There are no special fixing means between the battery unit housing 32, whose position can be adjusted by the rail sections 44, and the mounting bracket 11; the position of the battery unit housing 32 is maintained by appropriate friction in the synthetic resin rail sections 44.

[0026] Figures 10 and 11 show the state when the rail section 44 is in the reference position. In this state, the tubular section 16 of the mounting bracket 11 (in other words, the handrim 5) is located in the center of the left-right dimension of the battery unit housing 32. That is, the amount of protrusion of the battery unit housing 32 from the handrim 5 in the left-right direction is approximately equal on both sides. Also, as shown in Figure 6, when the battery unit housing 32 is mounted on the manual wheelchair via the mounting bracket 11 together with the drive unit 12, the battery unit housing 32 does not protrude beyond the end of the drive unit housing 31 on the electric motor 35 side in the left-right direction. That is, the maximum amount of protrusion of the electric assist device 1 in the left-right direction is determined by the upper corner 31b (corresponding to the outer end) of the drive unit housing 31, and the amount of protrusion of the battery unit housing 32 in the left-right direction is smaller than this maximum amount of protrusion. In other words, when the electric assist device 1 is projected along the radial direction of the handrim 5 as shown in Figure 2, the amount of protrusion of the battery unit housing 32 is smaller than the maximum amount of protrusion of the outer end of the drive unit housing 31 in the left-right direction of the manual wheelchair. Such lateral protrusion is an important factor, for example, when passing through a relatively narrow corridor. Although not shown in the diagram, the battery unit 13 and the drive unit 12 are connected by a harness with detachable connectors at its ends, and power is supplied to the drive unit 12 through this harness.

[0027] As described above, the electric assist device 1 of this embodiment integrates the drive unit 12, mounting bracket 11, and battery unit 13 into a single unit. Installation of the entire device is completed simply by attaching the mounting bracket 11 to the handrim 5 of a manual wheelchair while the unit remains integrated. Conversely, removal is completed by pulling the tubular portion 16 of the mounting bracket 11 off the handrim 5. Therefore, a simple electrification of a manual wheelchair can be easily achieved. The integrated electric assist device 1 contains all the elements necessary for operation, eliminating the need to attach other parts to other parts of the manual wheelchair.

[0028] Furthermore, since the drive unit 12 is located on the outer circumference, or upper part, of the handrim 5, while the battery unit 13 is located on the inner circumference, the overall design can be made compact. In other words, the battery unit 13 can be placed in the empty space on the inner circumference of the handrim 5.

[0029] Furthermore, while the drive unit 12 rests on top of the mounting bracket 11, the battery unit 13 is suspended downward from the mounting bracket 11. Since the weight of the battery unit 13, including the battery 39, is relatively large, when the electric assist device 1 is attached to the handrim 5, the center of gravity of the electric assist device 1 is located on the inner circumference side of the handrim 5 (i.e., below the handrim 5 at the notch 17) due to the weight of the battery unit 13. As a result, the posture of the electric assist device 1 around the handrim 5 is stable, making it easy for the user to handle. In other words, the battery unit 13 also functions as a counterweight to stabilize the posture of the electric assist device 1 on the handrim 5.

[0030] Furthermore, as described above, the electric assist device 1, which consists of a drive unit 12, a mounting bracket 11, and a battery unit 13, allows for the attachment and detachment of the drive unit 12 and the battery unit 13 to the mounting bracket 11. Therefore, if the diameter (i.e., curvature) of the handrim 5 of a manual wheelchair varies, by preparing several mounting brackets 11 having tubular sections 16 with different curvatures, it is possible to accommodate various manual wheelchairs by simply changing the mounting bracket 11.

[0031] Next, the operation of a manual wheelchair equipped with the above-mentioned electric assist device 1 will be described. As mentioned above, the electric assist device 1 is attached to each of the left and right wheels 2 of the manual wheelchair, and is operated by a user seated in the seat with both hands placed on the left and right electric assist devices 1. For example, with the top of the wheel 2 as the reference position, if the user presses the operation switch 38 and tilts the electric assist device 1 forward, the drive roller 36 of the drive unit 12 drives the wheel 2 in the forward direction. If both the left and right electric assist devices 1 are operated similarly, the manual wheelchair will move forward. The fact that the electric assist device 1 has been tilted forward by the user is detected by a gravity sensor (for example, a 6-axis gravity sensor) built into the drive unit 12. Conversely, if the user presses the operation switch 38 and tilts the electric assist device 1 backward, the wheel 2 will be driven in the reverse direction. Therefore, if both the left and right electric assist devices 1 are tilted backward simultaneously, the manual wheelchair will move backward. Furthermore, by operating one of the left and right electric assist devices 1 in the forward direction and the other in the reverse direction, the manual wheelchair can be turned around.

[0032] In the above explanation, the top of wheel 2 was described as the reference position of the electric assist device 1, but it is also possible to set a reference position at an angle other than the top (an angle tilted at an appropriate angle forward or backward). Even if the reference position is set at an appropriate angle, it is possible to detect whether the electric assist device 1 has been tilted forward or backward from this reference position using the gravity sensor. Furthermore, the amount of displacement of the electric assist device 1 due to user operation (how much it has been tilted) can also be detected by the gravity sensor, and in one embodiment, the larger this displacement, the greater the torque with which wheel 2 is driven.

[0033] Figure 14 is a flowchart showing the processing flow of the driving control performed by the control circuit built into the electric assist device 1. In the first step 1, the state of the operation switch 38 is read, and in step 2, it is determined whether the operation switch 38 is ON (pressed). If the operation switch 38 is OFF, the process proceeds to step 9, where the target torque is set to 0.

[0034] If the operation switch 38 is ON, in step 3, data from the 6-axis gravity sensor is read and the tilt angle of the electric assist device 1 (tilt angle from the reference position) is calculated. Based on this tilt angle, the target torque is calculated in step 5. In step 6, the rate limiter limits the rate of change of the target torque to a certain upper limit. Then, based on the target torque obtained in this way, the ON duty cycle for PWM control of the electric motor 35 is calculated in step 7, and in step 8, a drive signal according to this ON duty cycle is output to the electric motor 35.

[0035] In this way, the user can obtain the corresponding driving force by moving the left and right electric assist devices 1 forward and backward, making it easy to achieve driving that aligns with the user's intentions.

[0036] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, the mounting bracket 11 is mainly composed of a tubular portion 16 with a substantially C-shaped cross-section, but the mounting bracket 11 is not limited to such a configuration and can have any structure as long as it has a hollow passage portion 15 that is curved in an arc shape through which the handrim 5 can pass. For example, the mounting bracket 11 may have a two-part structure that allows it to be detachably attached to the handrim 5. [Explanation of symbols]

[0037] 1…Electric assist device 2...wheels 5…Handrim 11…Mounting bracket 12…Drive unit 13…Battery Unit 15...Hollow passage section 16...Tubular part 17... Notch 18…Drive unit mounting section 31…Drive unit housing 31a... Grip section 32... Battery unit housing 33... Boss section 35…Electric motor 36… Drive roller 37...Reducer 39…Battery 40... Circuit board 42...Protrusion 44... Rail section

Claims

1. An electric assist device that is attached to the wheels of a manual wheelchair, A mounting bracket is attached to the handrim, having a hollow passage section curved in an arc shape through which the handrim can pass, and the handrim is slidably fitted into the hollow passage section. A drive unit having a first housing supported by the above-mentioned mounting bracket, a drive roller that contacts the outer surface of the wheel, and an electric motor that drives the drive roller, A battery unit having a second housing supported by the above-mentioned mounting bracket and containing a battery, An electric assist device for manual wheelchairs, equipped with the following features.

2. The first housing described above is supported on the outer circumference side of the handrim of the mounting bracket. The second housing described above is supported on the inner circumference side of the handrim of the mounting bracket. The electric assist device for a manual wheelchair according to claim 1.

3. The above mounting bracket is mainly composed of a curved tubular portion that forms the hollow passage section. The tubular portion described above has a roughly C-shaped cross-section with an open lateral portion so that it can be press-fitted onto the handrim. The electric assist device for a manual wheelchair according to claim 1.

4. The mounting bracket and the second housing are connected via rails that engage with each other in a slidable manner along the width direction of the manual wheelchair. The position of the second housing in the width direction relative to the mounting bracket can be adjusted by the rail portion. The electric assist device for a manual wheelchair according to claim 1.

5. The above drive unit is configured such that the electric motor, the drive roller, and the reduction gear between them are arranged so that their respective rotation axes are parallel, and the electric motor and the drive roller are positioned on opposite sides of the reduction gear. Furthermore, the above-mentioned axis of rotation is tilted so that the outer side in the width direction of the manual wheelchair is relatively lower. The electric assist device for a manual wheelchair according to claim 1.

6. The first housing described above is mounted to the mounting bracket so as to be angle-adjustable, with the center line along the tangential direction of the handrim as the center of rotation. The electric assist device for a manual wheelchair according to claim 1.

7. The tubular portion described above has a notch formed in the central part of its longitudinal direction, which overlaps with the drive unit, to avoid interference with the first housing described above. Drive unit mounting portions are formed adjacent to both ends of this notch, respectively, to support the pair of shaft portions of the first housing. The electric assist device for a manual wheelchair according to claim 3.

8. The above drive unit is equipped with an operating switch. The electric assist device for a manual wheelchair according to claim 1.

9. The above drive unit is equipped with a gravity sensor that detects whether the handrim has tilted forward or backward, based on its orientation at a reference position in the circumferential direction. The drive direction switches to forward when tilted forward and to reverse when tilted backward. The electric assist device for a manual wheelchair according to claim 1.

10. When the electric assist device is projected along the radial direction of the handrim, the amount of protrusion of the second housing is smaller than the maximum amount of protrusion of the outer end of the first housing in the left-right direction of the manual wheelchair. The electric assist device for a manual wheelchair according to claim 1.

11. The first housing and the second housing are configured to be detachably attached to the mounting bracket. The electric assist device for a manual wheelchair according to claim 1.

Images