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, and a drive unit 12 supported above the mounting bracket 11, and the two are integrated. The entire device is attached by press-fitting the tubular section 16 with a roughly C-shaped cross-section into the handrim 5. The mounting bracket 11 is not fixed to the handrim 5 in the circumferential direction, and the user supports the electric assist device 1 by hand when driving.

Description

Technical Field

[0001] The present 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 drives a manual wheelchair by rotating a friction roller that contacts the wheels of the manual wheelchair with an electric motor.

[0003] In the electric assist device of Patent Document 1, the friction roller is supported by the frame of the manual wheelchair, and an operation joystick is 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 is configured to individually attach the friction roller and the joystick 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 a 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] The present invention is an electric assist device attached to the wheels of a manual wheelchair, A mounting bracket that is detachably attached to the handrim, having a hollow passage section curved in an arc shape through which the handrim can pass, and the handrim being slidably fitted into the hollow passage section, A drive unit having a housing supported by the above-mentioned mounting bracket, including a drive roller that contacts the outer surface of the wheel and an electric motor that drives the drive roller, It is composed of the following features.

[0007] In this configuration, the drive unit and mounting bracket of 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 travel, 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 of 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, excluding the drive unit. [Figure 10] A perspective view showing the operating switches on the drive unit. [Figure 11] 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 6 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 in the state of being mounted on the handrim 5, and the user sitting on the seat part supports the electric assist device 1 in the circumferential direction with both hands. 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 6, the electric assist device 1 is depicted at the uppermost part of the wheel 2 on the assumption 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 to 6, 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 and a drive unit 12 for driving the wheel 2, and the two are integrated. The drive unit 12 has a drive unit housing 31 made of a hard synthetic resin as a 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, that is, above the mounting bracket 11.

[0015] As shown in FIGS. 9 and 10, the mounting bracket 11 is mainly composed of a tubular portion 16 having a circular cross-section that forms a hollow passage portion 15 curved in an arc shape through which the handrim 5 can pass. The tubular portion 16 is made of a rigid synthetic resin having appropriate elasticity, and as shown in FIGS. 9 and 10, it extends back and forth while curving in an arc shape with a curvature corresponding to the curvature of the handrim 5, and has a substantially C-shaped cross-section with the side surface portion facing the wheel 2 being open. By having the tubular portion 16 in a substantially C-shaped cross-section like this, it is possible to press-fit the tubular portion 16 onto the handrim 5 by utilizing the elasticity of the resin material. In the press-fitted state, the opening width of the side surface portion is smaller than the outer diameter of the handrim 5. Therefore, the mounting bracket 11 does not naturally fall off from the handrim 5. The inner diameter of the tubular portion 16 having a substantially C-shaped cross-section, that is, the diameter of the hollow passage portion 15, is set slightly larger than the outer diameter of the handrim 5, and the handrim 5 can pass through the hollow passage portion 15 in the circumferential direction. That is, the mounting bracket 11 is configured to be able to move freely in the circumferential direction with respect to the handrim 5.

[0016] As shown in FIG. 9, at the central portion in the longitudinal direction (front-rear direction) of the tubular portion 16, a notch portion 17 is provided over a relatively large length range so as to avoid interference with the drive unit housing 31. In the range of this notch portion 17, the tubular portion 16 has a shape in which the upper portion is cut off so that only the lower portion (inner peripheral side portion) in the C-shaped cross-section remains. The formation range of this notch portion 17 generally corresponds to the front-rear dimension of the drive unit housing 31. By providing the notch portion 17 like this, the portion press-fitted onto the handrim 5 is divided into two, so that the press-fitting onto the handrim 5 becomes easy and the sliding resistance generated between the handrim 5 during running is reduced. Also, 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 at positions adjacent to the front and rear ends of the notch 17 of the tubular portion 16. As shown in Figures 5 and 10, 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 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 4, 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 10, 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] Although not shown in the diagram, a battery unit containing a secondary battery that serves as the power source is positioned at an appropriate location, such as the seat back of the manual wheelchair. This battery unit 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 via this harness.

[0023] In the electric assist device 1 of the embodiment configured as described above, the drive unit 12 and the mounting bracket 11 are integrated, and the entire device can be installed simply by attaching the mounting bracket 11 to the handrim 5 of a manual wheelchair while the device remains integrated. Conversely, removal can be completed by pulling out the tubular portion 16 of the mounting bracket 11 from the handrim 5. Therefore, a simple electrification of a manual wheelchair can be easily achieved. In particular, since the electric assist device 1 is supported by the handrim 5 rather than the frame of the manual wheelchair, it can be widely installed on various manual wheelchairs regardless of the frame structure.

[0024] Furthermore, as described above, the electric assist device 1, which consists of a drive unit 12 and a mounting bracket 11, allows the drive unit 12 to be attached to and detached from 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.

[0025] 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.

[0026] 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.

[0027] Figure 11 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.

[0028] 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.

[0029] 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.

[0030] 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]

[0031] 1…Electric assist device 2...wheels 5…Handrim 11…Mounting bracket 12…Drive unit 15...Hollow passage section 16...Tubular part 17... Notch 18…Drive unit mounting section 31…Drive unit housing 31a... Grip section 33... Boss section 35…Electric motor 36… Drive roller 37…Reducer

Claims

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

2. 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.

3. 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.

4. The above housing is mounted to the above 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.

5. 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 housing. At both ends of this notch, drive unit mounting portions are formed, which support the pair of shaft portions of the housing. The electric assist device for a manual wheelchair according to claim 2.

6. The front end of the above-mentioned housing constitutes the grip portion that the user holds in their hand. The electric assist device for a manual wheelchair according to claim 1.

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

8. 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.

9. The above reference position, which serves as the switching point for forward / reverse movement, can be set arbitrarily. The electric assist device for a manual wheelchair according to claim 8.

10. The housing is configured to be detachably attached to the mounting bracket. The electric assist device for a manual wheelchair according to claim 1.

Images