Manually operated, motor-assited wheelchair

Abstract: A manually operated, motor-assisted wheelchair comprises a manual force detecting means to detect manual forces applicable to wheels and an assist power system to apply assist power commensurate with manual forces detected to the respective wheels. Indicating means are provided for indicating certain operating conditions and/or adjustment conditions.

Description: This invention relates to a manually operated, motor-assisted wheelchair comprising a manual force detecting means to detect manual forces applicable to wheels and an assist power system to apply assist power commensurate with manual forces detected to the respective wheels. A wheelchair according to the preamble of claim 1 is known from EP-A-0 687 454. The manually operated, motor-assisted wheelchair would be categorized between the manual wheelchair and the motor-operated wheelchair, and is adapted to detect manual forces (torques) applied to manual force input members such as hand rims, and to apply assist powers commensurate with the manual forces (torques) to the right and left wheels, thereby alleviating physical effort of the rider. By the way, a method for detecting the manual forces applied to the manual force input members is known. That is to say, the manual force input member which can be rotated relative to the wheel is mounted on the wheel through an elastic members such as springs so that the magnitude of the manual force in proportion to the relative rotation amount is found by detecting the relative rotation by mean of a potentiometer or the like. Here, the zero point adjustment for the manual force detecting means such as the potentiometer is made so that the output is zero in a neutral state when there is,no manual force input. However, the conventional manual force detecting means has a problem in its zero point adjustment: It requires complicated procedure and much time because every time of adjustment a testing instrument is connected to the detecting means, the attachment position of the detecting means is adjusted while detecting the output of the detecting means so that the output becomes zero in the neutral state. Accordingly, it is an objective of the present invention to provide an improved manually operated, motor-assisted wheelchair which improves the ease of operation including maintenance and restoration. According to the present invention, this objective is solved for a manually operated, motor-assisted wheelchair as indicated above in that indicating means are provided for indicating certain operating conditions and/or adjustment conditions. According to a preferred embodiment of the present invention, said adjustment conditions are the states of zero point adjustment of said manual force detecting means. Another problem with the conventional manually operated, motor-assisted wheelchair is that no means is provided for informing the rider of any location or kind of troubles when such troubles occur. As a result, the rider is inevitably inconvenienced. Therefore, it is advantageous when said indicating means comprises a further display section having a further LED, said further display section being disposed at the reverse side of a fixed plate of one of the wheels. Moreover, usually when the manual force is applied to the hand rim, the force works not only in the circumferential direction but also in the lateral direction, namely in the vehicle width direction. As a result, the hand rim wobbles in the lateral direction and causes a prying force on the supporting portion of the small diameter portion. This in turn increases frictional resistance, ease of operation is adversely affected and, moreover, the manual force (torque) applied in the circumferential direction onto the input member cannot be detected accurately. Therefore, in order to further enhance the ease of operation it is advantageous when wobble prevention members are provided in a plural number of circumferential positions on a hub side facing the vicinity of outer circumference of an input member of said manual force detecting means. Therefore, according to the present invention, the state of the zero point adjustment of the manual force detecting means may be confirmed by visually recognizing the display sections provided on the wheelchair itself. As a result, zero point adjustment of the manual force detecting means may be made simply within a short period of time. Further, it is possible that the display section provides the rider also with information other than the state of zero point adjustment. Therefore, the rider is provided with information on any trouble in the manually operated, motor-assisted wheelchair in terms of on which of right and left wheels the trouble has occurred, and the location and the kind of the trouble. With another embodiment, the rider learns that the potentiometer is zero point adjusted when the lamp lights up. As a result, the potentiometer is zero point adjusted within a short period of time. According to a further embodiment the sensitive lighting zone of the lamp is set to be narrower than the electrically insensitive zone for the input signals from the potentiometer. As a result, the zero point does present within the insensitive zone as long as the lamp is lit up, and the zero point adjustment may be made accurately. With this invention as described above, wobble prevention members are provided in a plural number of circumferential positions on the hub side facing the vicinity of the outer circumference of the input member, and the gap between the wobble prevention member and the input member is adjustable to zero or a minute value. Therefore, no prying force is applied to the supporting portion in the central portion of the input member, the lateral wobble of the input member is suppressed, and the ease of operating input member is improved. At the same time, accuracy in the manual force measurement is improved. Since the wobble prevention members are disposed in the outer circumferential portion of the input member, even if the input member is pressed against the wobble prevention member, the contact is surface to surface and therefore the surface pressure is restricted to a low value, and the frictional resistance is kept low. In particular, if the wobble members are made of a resin of a low coefficient of friction, the frictional resistance is further restricted to a lower value even if the wobble prevention members come into contact with the input member. Other preferred embodiments of the present invention are laid down In further dependent claims. In the following, the present invention is explained in greater detail with respect to several embodiments thereof in conjunction with the accompanying drawings, wherein: FIG. 1 is a side view of a manually operated, motor-assisted wheelchair related to the embodiment 1 of the invention; FIG. 2 is a plan view of the same wheelchair; FIG. 3 is a rear view of the same wheelchair; FIG. 4 is an axial view of the hub portion of a wheel of the wheelchair with its cover removed; FIG. 5 is an enlarged view of the section A-A in FIG. 4; FIG. 6 shows the section B-B in FIG. 4; FIG. 7 is a side view as seen from inside the right wheel of the wheelchair of the embodiment 1 of the invention; FIG. 8 is a side view as seen from inside the left wheel of the wheelchair of the embodiment 1 of the invention; FIG. 9 is a characteristic graph of a potentiometer output versus manual force; FIG. 10 is a graph of relationship between potentiometer input signal and target torque; FIG. 11 is an electrical connection diagram for the manually operated, motor-assisted wheelchair of the embodiment 2 of the invention; FIG. 12 is a view of an essential part of the right hand side wheel as seen from inside the wheelchair of the embodiment 2 of the invention; FIG. 13 is an enlarged cross section C-C in FIG. 12; FIG. 14 is similar to FIG. 5 to show another embodiment of the spring holding structure of the manual force detection means; FIG. 15 is a side view of a wobble prevention means according to another embodiment of the present invention; FIG. 16 is a cross-sectional view of a part of a manual force detecting means comprising the wobble prevention means of FIG. 15; and FIG 17 is a cross-sectional view of the wobble prevention means of FIG. 15. Embodiments of the invention will now be described in reference to appended drawings. FIG. 1 is a side view of a manually operated, motor-assisted wheelchair related to the embodiment 1 of the invention. FIG. 2 is a plan view of the same wheelchair. FIG. 3 is a rear view of the same wheelchair. FIG. 4 is an axial view of the hub portion of a wheel of the wheelchair with its cover removed. FIG. 5 is an enlarged view of the section A-A in FIG. 4. FIG. 6 shows the section B-B in FIG. 4. FIG. 7 is a side view as seen from inside the right wheel of the wheelchair related to the invention. FIG. 8 is a side view as seen from inside the left wheel of the wheelchair related to the invention. FIG. 9 is a characteristic graph of a potentiometer output versus manual force. FIG. 10 is a graph of relationship between potentiometer input signal and target torque. In the manually operated, motor-assisted wheelchair 1 of the invention, assist powers in proportion to the manual forces applied to the right and left wheels 2 are applied respectively to the right and left wheels 2. The wheelchair is constituted with an existing folding type of manual wheelchair body, and the wheels removably attached to the right and left sides of the wheelchair body. The front and rear of the pipe frame 3 of the vehicle body are supported with paired right and left casters 4 and wheels 2 for free rolling. A seat 5 made of cloth for a rider to sit on is disposed in the center of the frame 3. As shown in FIG. 3, the frame 3 has paired front and rear cross members 3a. The X-shaped cross members 3a are pivoted at their intersection by means of a shaft 6 so that the vehicle body may be folded about the shaft 6. Paired right and left back pipes 3b are erected in the rear part of the frame 3. The upper ends of the back pipes 3b are bent rearward and covered with grips 7 for a tending person. A willy bar 8 is attached to the inside of each of the wheels 2 so as to extend obliquely rear downward (to the right in FIG. 1) for preventing the wheelchair from falling. Paired right and left elbow pipes 3c extend from the middle height position of the back pipes 3b of the frame 3 horizontally forward of the vehicle body and then bend downward at generally right angles, with their ends provided with casters 4 for free rolling. Front ends of paired right and left seat pipes 3d disposed below the elbow pipes 3c extend obliquely down forward, with their extended ends (fore-ends) are provided with paired steps 9. As shown in FIG. 6, each of the wheels 2 is supported for free rotation through two bearings 12 on a wheel shaft 11 supported on a wheel attachment boss 10 welded to the frame 3. A hand rim 13 for the rider to turn by hand is disposed on the outer side of each of the wheels 2. The hand rim 13 is attached through three spokes 15 to a disk 14 rotatably supported on a hub 2a of the wheel 2 using bolts 16. Therefore, the hand rim 13 may rotate independently of the wheel 2. In this embodiment as shown in FIG. 6, a seal ring 17 made of an elastic material is interposed between the hub 2a of the wheel 2 and the disk 14. The disk 14 is covered with a cover 18 connected to the disk 14. The seal ring 17 has the function of a friction damper for suppressing circumferential vibration due to inertia of the disk 14 as well as the function of sealing. The hand rim 13 is elastically supported at its three circumferential points by means of the structure shown in FIGs. 4 and 5 so as to be rotatable in both directions relative to the wheel 2. That is to say, as shown in FIG. 4, rectangular holes 14a are made in three circumferential positions on the disk 14. A large diameter spring 19 and a Small diameter spring 20 are installed in a compressed state in a space defined with the rectangular hole 14a and a recess 2a-1 of a semicircular cross section formed in each of three positions on the end surface of the hub 2a of the wheel 2 as shown in FIG. 5. Both ends of the springs 19, 20 are received in spring seats 21, 22. The springs 19, 20 are held in place with a retainer 24 secured to the hub 2a of the wheel 2 by means of two bolts 23. In the neutral state in which no manual force is applied to the hand rim 13, the small diameter spring 20 is installed with a specified initial compression force between the spring seats 21, 22, and both ends of the large diameter spring 19 are slightly apart from the spring seats 21, 22 without exerting forces to the spring seats 21, 22. The spring constant of the large diameter spring 19 is set greater than that of the small diameter spring 20. As shown in FIGs. 4 and 6, a potentiometer 27 for detecting the magnitude and direction of the manual force applied to the hand rim 13 (disk 14) from the amount and direction of rotation of the wheel 2 (hub 2a) relative to the hand rim 13 is attached to the outside end surface of the hub 2a using bolts 25 inserted in elongate holes 27a so that the position of the potentiometer 27 is adjustable (See FIG. 4). One end of a lever 28 is connected to the end of the input shaft of the potentiometer 27. The other end of the lever 28 has an elongate hole which is in engagement with a pin 29 projecting from the disk 14. As shown in FIGs. 6 through 8, a stationary disk 30 is disposed inside, with respect to the vehicle width direction, each of the paired wheels 2 and secured to the wheel shaft 11. A controller 31 constituting a control means and an electric motor 32 as a driving source are mounted on the stationary disk 30. Inside each of the wheels 2 is formed a space defined with the stationary disk 30. The space is divided with a ring-shaped partition wall 33 into a chamber S1 and a chamber S2. The controller 31 is housed in the chamber S1. A rotation transformer 34 performs signal transmission between the controller 31 and the potentiometer 27. The assist power produced with each of the electric motors 32 is transmitted through power transmission means including a belt transmission mechanism G1 and gears G2, G3 to each of the wheels 2. The above-described manual force detection means constituted with the springs 19, 20; signal transmission means constituted with the rotation transformer 34, control means constituted with the controller 31; and power transmission means constituted with the electric motor 32, the belt transmission mechanism G1, and gears G2, G3 constitute an assist power unit. The assist power unit is disposed around the wheel shaft 11 of the hub 2a of each of the wheels 2 in radially and axially compact dimensions. Each of the wheels 2 including the assist power unit within the hub 2a may be attached to or removed from the vehicle body as mentioned before. The manually operated, motor-assisted wheelchair 1 of the invention has a main switch (not shown) included in the hub 2a of the right hand side wheel 2. The main switch is turned on and off with swinging movement of a lever 35 shown in FIG. 7. The lever 35 for free swinging is supported with the wheel shaft 11. The base portion of the lever 35 is partially formed with gear teeth 35a in engagement with a sector gear 36 for turning the main switch on and off. A light emitting diode (LED, not shown) is embedded in the fore-end of the lever 35 for displaying the on or off state of the main switch. A cable 37 led out of the LED is electrically connected to a battery 38 which will be described later. The manually operated, motor-assisted wheelchair 1 of the invention has a battery 38 removably disposed near the right hand side wheel 2 as shown in FIGs. 1 and 7. That is to say, as shown in FIG. 6, to the stationary disk 30 is attached a bracket 39 using a bolt 40. To the upper part of the bracket 39 is attached a battery holder 41 using a screw 42. The battery 38 is removably installed in the battery holder 41. With the above-described arrangement, when the main switch is turned on by the swinging movement of the lever 35 in the state of the battery 38 being installed in the battery holder 41, the battery 38 energizes to drive both the assist power units provided on the right and left wheels 2 through wiring harnesses 52, 43. As shown in FIG. 7, the wiring harnesses 43, 52 are electrically interconnected through couplers 44a, 44b. One end of the wiring harness 43 is electrically connected to the assist power unit on the right hand side wheel 2 while its other end is electrically connected to the assist power unit on the left hand side wheel 2 as shown in FIG. 8. As shown in FIG. 8, a coupler 45 is attached to the stationary disk 30 on the left hand side wheel 2. The wiring harness 43 may be easily connected electrically to the assist power unit on the left hand side wheel 2 by simply pushing a coupler 46 connected to the end of the wiring harness 43 into the coupler 45. In this embodiment, the zero point adjustment of the potentiometer 27 is made by loosening the bolts 25 shown in FIG. 4 and adjusting the position of the potentiometer 27. Here, an LED 47 (shown in FIGs. 4 and 6) that lights up when the potentiometer 27 is zero point adjusted is provided in the controller 31 secured to the stationary disk 30. As shown in FIG. 4, an adjustment window 33a, facing the LED 47, of a circular shape is formed in the partition wall 33 in the wheel 2 in a position corresponding to the LED 47. A circular transparent member 48 is fit in the adjustment window 33a. While the transparent member 48 is provided in this embodiment, the LED 47 may also be recognized by arranging that the entire partition wall 33 is transparent, or that the portion of the partition wall 33 facing the LED 47 is thin-walled to be semitransparent. As shown in FIGs. 4 and 6, the LED 47, the adjustment window 33a, and the transparent member 48 are disposed to be aligned in the direction parallel to the wheel shaft 11 with any one of four openings 2a-2 of large and small sizes formed in four circumferential positions on the end surface of the hub 2a and sector-shaped openings 14b formed in three circumferential positions in the disk 14 depending on the rotated position of the wheel 2. Therefore, when the cover 18 (See FIG. 6) is removed for the zero point adjustment of the potentiometer 27, the lighting state of the LED 47 (or the zero point adjustment state of the potentiometer 27) may be visually confirmed from outside each of the wheels 2 as shown in FIG. 4. Now the function of the manually operated, motor-assisted wheelchair of the present embodiment will be described. When the rider applies manual forces to the paired right and left hand rims 13 to turn them in the forward direction for example, the hand rim 13 does not move, and no relative rotation occurs between the hand rim 13 and the wheel 2 before the magnitude of the manual force F M overcomes the initial compression force produced with the three small diameter springs 20. Here, the output of the potentiometer 27 is zero as shown in FIG. 9. In FIG. 9, the symbol F M0 shows the manual force which is equal to the initial compression force produced with the three small diameter springs 20. After that, when the manual force F M increases beyond F M0 , first the small diameter spring 20 only is compressed, and the hand rim 13 rotates relative to the wheel 2 by an angle commensurate with the compressed amount of the small diameter spring 20. The relative rotation amount of the hand rim 13 is magnified with the lever 28, and transmitted to the potentiometer 27. The potentiometer 27 outputs a signal as shown with a straight line (a) in FIG. 9 corresponding to the manual force F M applied to the hand rim 13. The signal is sent through the rotation transformer 34 to the control section of each controller 31. Because of a small spring constant of the small diameter spring 20, the amount of compression of the spring 20 corresponding to the increase in the manual force F M , or the amount of rotation of the hand rim 13, is large, and therefore, the sensitivity of the potentiometer 27 is kept high. As a result, the rider may operate the wheelchair 1 in a finely controlled manner. When the value of the manual force F M applied to the hand rim 13 reaches F M1 shown in FIG. 9, the large diameter spring 19 begins to be compressed together with the small diameter spring 20, and the hand rim 13 rotates relative to the wheel 2 by an angle commensurate with the compression amount of both the springs 19, 20. Here, the potentiometer 27 outputs a signal corresponding to the manual force F M applied to the hand rim 13 as shown with a straight line (b) in FIG. 9. After that, when the manual force F M applied to the hand rim 13 increases beyond F M2 shown in FIG. 9, both the spring seats 21, 22 come into contact with each other. As a result, the manual force F M is transmitted directly to the wheel 2. At this time, the output of the potentiometer 27 is constant as shown with a straight line (c) in FIG. 9. In place of the arrangement in which both the spring seats come into contact with each other, an arrangement may be employed in which the disk 14 comes into contact with the hub 2a or the retainer 24. When the rider applies manual forces to the hand rim 13 in the reverse direction, the output of the potentiometer 27 becomes as shown with straight lines (a'), (b'), and (c') in FIG. 9 and the hatched zone of the manual force in FIG. 9 is the insensitive zone. While the insensitive zone is provided by providing a specified initial compression force by means of the spring 20 described above, since the spring constant of the spring 20 is small, an insensitive zone of a narrow band width is provided in a stabilized manner. Provision of such an insensitive zone makes it possible to securely detect the standstill state of the wheelchair while allowing mechanical and electrical inaccuracy. The manual force F M applied intermittently to the hand rim 13 is detected as described above with the potentiometer 27, and the detected signal is inputted through the rotation transformer 34 to the control section of the controller 31. The control section of the controller 31 calculates a target torque τ based on a specified assist ratio for an input signal V in coming from the potentiometer 27, and outputs a control signal commensurate with the target torque τ. The relationship between the input signal V in and the target torque τ is shown in FIG. 10 with the assist ratio as a parameter. In this embodiment, when the value of V in is in the range V i1 - V i2 , the target torque is zero. Thus, the insensitive zone is formed as shown in FIG. 10 with hatching. When both the electric motors 32 are driven, their rotations are transmitted to the right and left wheels 2 through the power transmission means including the belt transmission mechanism G1, gears G2, and G3. Then both the right and left wheels 2 are driven by a driving force which is the sum of the manual forces and the assist forces. As a result, the wheelchair 1 is driven forward, and the rider may operate the wheelchair easily with about a half of the total driving force. While the above description is made with respect to the forward movement of the wheelchair 1, the reverse movement is similar to the forward movement. To make the zero point adjustment with the potentiometer 27 of each of the wheels 2 in the embodiment described above, the bolts 25 shown in FIG. 4 are loosened and its position is adjusted. In that case, the LED 47 (See FIGs. 4 and 6) that lights up when the zero point adjustment is made is provided in the controller 31 attached to the stationary plate 30. When the cover 18 (See FIG. 6) is removed for the zero point adjustment with the potentiometer 27, the lighting state of the LED 47 (or the zero point adjustment state of the potentiometer 27) may be visually confirmed from outside each of the wheels 2 through the opening 2a-2 of the hub 2a and the opening 14b of the disk 14. Therefore, the person making the zero point adjustment may learn from the lighting of the LED 47 that the zero point adjustment has been made, and then the bolts 25 maybe tightened to finish the zero point adjustment. Thus, the zero point adjustment of the potentiometer 27 may be made within a short period of time through a simple procedure. In particular in this embodiment, the zero point of the potentiometer 27 is set with a certain width, and the lighting zone of the LED 47 is set to be narrower than the electrical insensitive zone of the input signal V in coming from the potentiometer 27. As a result, in the state of the LED 47 being lit up, the zero point of the potentiometer 27 is securely located within the electrical insensitive zone so that the zero point adjustment of the potentiometer 27 may be made within a short period of time through a simple procedure. While the LED 47 in this embodiment is provided on each of the right and left wheels 2, similar LEDs may be provided in any other locations than the wheels on the wheelchair. Now the second embodiment of the invention will be described in reference to FIGs. 11 through 14. FIG. 11 is an electrical connection diagram for the manually operated, motor-assisted wheelchair of the invention. FIG. 12 is a view of an essential part of the right hand side wheel as seen from inside the same wheelchair. FIG. 13 is an enlarged cross section C-C in FIG. 12. FIG. 14 is similar to FIG. 5 to show another embodiment of the spring holding structure of the manual force detection means. In these drawings, the elements which are identical to those shown in FIGs. 1 - 10 are provided with the same symbols. As shown in FIG. 11, in this embodiment again, the LED 47 which lights up upon completion of the zero point, adjustment of the potentiometer 27 is provided in the controller 31 incorporated in each of the right and left wheel hubs. Also the main switch 55 to be turned on and off with the lever 35 is provided on the inner side of the stationary disk 30 of the right hand side wheel. An LED 56 for displaying, by its lighting state, the remaining battery capacity and troubles in the entire wheelchair as well as the on/off state of the power (on/off state of the main switch 55) is provided in the right hand side controller 31. By the way in this embodiment, each of the controllers 31 is provided with a power circuit board 31a and a control circuit board 31b, both spaced from each other by a specified distance in the vehicle width direction (normal to the drawing surface of FIG. 11) and also displaced from each other in the circumferential direction. The power circuit board 31a is secured in surface to surface contact with the stationary disk 30 and carries such components as (not shown) relays, capacitors, and thyristors which produce heat. On the control circuit board 31b are attached components such as CPU and others which do not produce heat. In this way, the heat producing components and non-heat producing components are separately disposed on the power circuit board 31a and the control circuit board 31b, respectively, so that heat from the heat producing components may be efficiently dissipated in the air through the stationary disk 30 and that each of the wheel hubs is prevented from being heated. In this embodiment, the power circuit board 31a and the control circuit board 31b are respectively formed in sector shapes and mutually displaced in the circumferential direction. By the way, while the power circuit board 31a and the control circuit board 31b are shown in FIG. 11 as mutually displaced also in the radial direction for the convenience of illustration, actually they are not mutually displaced in the radial direction. The LED 47 is attached to the surface (outside surface with respect to the vehicle width direction) of the control circuit board 31b of the controller 31 so that its lighting state may be visually confirmed easily from outside. Each of the LEDs 47 has the function of informing, by its lighting, the rider of the completion of the zero point adjustment of the potentiometer 27 provided on each of the wheels, and also by its flashing (specifically by the number of ons and offs within a specified period of time) of any troubles in the potentiometer 27 and the controller 31, providing the rider with information on locations and types of the troubles. When such troubles occur, the rider is informed of the occurrence and the types of the troubles by the sound of a buzzer 57 in addition to the flashing of the LED 47. Since the LED 47 is provided on each of the right and left wheels, the rider may learn from the flashing of the LED 47 on which of the wheels the trouble has occurred, and also may accurately learn from the manner of flashing the type of the trouble so that an appropriate action against the trouble may be taken promptly. The LED 56 provided in the right hand side controller 31 attached, as shown in FIGs. 11 through 13, in a location which is on the reverse side of the control circuit board 31b and does not overlaps the power circuit board 31a when seen in the circumferential direction. A circular hole 30a is formed in a position opposite the LED 56 of the stationary disk 30. A grommet 58 is fit in the circular hole 30a. The LED 56 is positioned in one opening, facing the inside of the stationary disk 30, of the grommet 58. The other opening, facing the outside of the stationary disk 30, of the grommet 58 is open upward. A transparent lens 59 is fit in the grommet 58. Part of the lens 59 is formed with a 45 degree reflection surface 59a so that light L from the LED 56 is reflected as shown in FIG. 13 with the reflection surface 59a with its light path bent upward by a right angle to exit the lens 59 upward. Therefore, the rider may easily see from the rider's seated position the lighting state of the LED 56 and get from the lighting state information on the state of the switch being on or off, remaining capacity of the battery, or any trouble in the entire wheelchair. Therefore, if any trouble occurs while the wheelchair is in use, the rider may learn the trouble from the lighting of the LED 56. Then the cover of the troubled wheel may be opened to locate and learn the type of the trouble from the manner of lighting of the LED 47. In this embodiment, the structure for holding the springs 19, 20 of large and small diameters constituting the manual force detecting means is constituted as shown in FIG. 14. That is to say, the width W 1 of the groove in the retainer 24 and the width W 2 in the groove of the hub 2a are made greater than the width W 3 of the rectangular hole 14a of the disk 14 (W 1 > W 2 > W 3 ). In the neutral state without the manual force on the hand rim, as shown in FIG. 14, one end of the retainer 24 is in contact with one spring seat 21 and one end of the hub 2a is in contact with the other spring seat 22, a gap Δ W 1 is formed between the retainer 24 and the spring seat 22, and a gap Δ W 2 is formed between the hub 2a and the spring seat 21. Here, each of the retainers 24 is secured with two bolts 23 to the hub 2a having circumferentially elongate holes (not shown) for passing the bolts 23. The manual force detection means may be set to the neutral position shown in FIG. 14 by the following procedure. That is to say, in the state of the bolts 23 being loosened, the springs 19, 20 and the spring seats 21, 22 are installed in the rectangular hole 14a of the disk 14. In that state, the disk 14 is rotated in the arrow direction in FIG. 14 to bring one spring seat 22 into contact with one end surface of the groove of the hub 2a. Then the retainer 24 is rotated in the same direction to bring the groove of the retainer 24 into contact with the other spring seat 21. Finally the bolts 23 are tightened to fix the adjusted state as shown in FIG. 14. With the constitution described above, machining errors of the width W 1 of the groove in the retainer 24, the width W 2 of the groove in the hub 2a, and the width W 3 of the rectangular hole 14a in the disk 14 may be absorbed with the gaps Δ W 1 and Δ W 2 so that the manual force detection means may be easily and accurately adjusted to the neutral state at the time of assembly. For the other two locations shown in FIG. 4, the adjustment to the neutral state may be made in a similar manner. FIGs. 15 through 17 show another embodiment of the present invention. As shown in FIGs. 15 through 17 a slider 25' made of a plastic material with a generally U shape cross section is fit and held slidably at the end portion of each of the retainers 24. Each slider 25' is pressed with a light force toward the outside end surface of the disk 14 with an adjustment screw 26 which may be screwed in and out relative to the end portion of the retainer 24 so that the gap between both components is zero or a minute value. Therefore, the disk 14 and the hand rim 13 held with the disk 14 are held with the sliders 25' which are in light contact with the outside end surface of the disk 14 so that lateral play of those components is held minimum. Here, the slider 25' is made of a material of a small coefficient of friction such as polyacetal resign (Duracon), polyamide resin (nylon), and fluorine resin (Teflon). As shown in FIG.15 in detail, each slider 25' is formed with guide grooves 25a on the inside surfaces (with respect to the width of the slider 25'), running in the lateral direction (normal to the drawing surface) with a semicircular cross section. Projections 24a running in the lateral direction (normal to the drawing surface) with a semicircular cross section are formed on both end (with respect to the width of the projecting end of the retainer 24) surfaces of the retainer 24. The projections 24a engage with the grooves 25a so that the slider 25' slides along the projections 24a and that the slider 25' is prevented from coming off by the engagement between the projection 24a and the guide grooves 25a. As is clear from the above description, with the invention, an effect is provided that the manual force detection means may be zero point adjusted easily within a short period of time because the zero point adjusted state of the manual force detection means may be confirmed by visually recognizing the display section provided on the wheelchair itself. Further, an effect is provided that the rider is provided with information, when any trouble occurs in the manually operated, motor-assisted, wheelchair, on which of the right and left wheels the trouble has occurred, or the location and the type of the trouble, because the display section also displays other information than the information on the zero point adjusted state of the manual force detection means. In addition, an effect is provided that the potentiometer may be easily and quickly zero point adjusted because the zero point adjusted state of the potentiometer may be learned from the lighting of the lamp. Moreover, an effect is provided that the potentiometer may be accurately zero point adjusted because the lamp lighting zone is set narrower than the electric insensitive zone for the input signal coming from the potentiometer.

Claims: A manually operated, motor-assisted wheelchair (1) comprising a manual force detecting means (27) to detect manual forces applicable to wheels (2) and an assist power system to apply assist power commensurate with manual forces detected to the respective wheels (2), characterized in that indicating means are provided for indicating certain adjustment conditions, which are the states of zero point adjustment of said manual force detecting means (27). A manually operated, motor-assisted wheelchair according to claim 1, characterized in that said operating conditions are malfunctions of a mechanical driving system and/or of said assist power system. A manually operated, motor-assisted wheelchair according to at least one of the preceding claims, characterized in that said indicating means comprising a display section having a LED (47), said display section being disposed on a fixed plate (30) for each of said wheels (2). A manually operated, motor-assisted wheelchair according to claim 3, characterized in that said display section is disposed on a surface, opposing a wheel hub (2a), of the fixed plate (30) for each of the wheels (2) and being recognizable from a vehicle body side through windows (33a) formed in a hub end wall and in a hand rim disk (14). A manually operated, motor-assisted wheelchair according to claim 3 or 4, characterized in that the display section being visually recognizable through a transparent member (48). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims, characterized in that said manual force detecting means comprising a potentiometer (27) and that said LED (47) lights up when the zero point adjustment of the manual force detecting means is finished. A manually operated, motor-assisted wheelchair according to claim 6, characterized in that the sensitive lighting zone of said LED (47) being set to be narrower than an electrically insensitive zone for input signals from said potentiometer (27). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims, characterized in that said indicating means comprising a further display section having a further LED (56), said further display section being disposed at the reverse side of a fixed plate (30) of one of the wheels (2). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims, characterized in that each of said wheels (2) being provided with a controller (31) for controlling said assist power system and said indicating means. A manually operated, motor-assisted wheelchair according to claim 9, characterized in that each of said controllers (31) comprising a power circuit board (31a) and a control circuit board (31b) both spaced from each other. A manually operated, motor-assisted wheelchair according to claim 10, characterized in that said LED (47) of said display section being provided on the outside surfaces of said control circuit boards (31b) and that said further LED (56) of said further display section being provided on the reverse side of one of said control circuit boards (31b). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims 8 to 11, characterized in that said further display section being positioned such that it is monitorable by a user sitting in said wheelchair (1). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims, characterized in that wobble prevention members (25') are provided in a plural number of circumferential positions on a hub side facing the vicinity of outer circumference of an input member (24) of said manual force detecting means (27). A manually operated, motor-assisted wheelchair according to claim 13, characterized in that the gap between the wobble prevention member (25') and the input member (24) is adjustable to zero or a minute value. A manually operated, motor-assisted wheelchair according to claim 13 or 14, characterized in that the input member (24) being constituted by including a disk (14) supported for rotation on a hub (2a) of the wheel (2), and that the wobble prevention members (25') are provided in a plural number of circumferential positions facing the vicinity of outer circumference of the disk (14). A manually operated, motor-assisted wheelchair according to claim 14 or 15, characterized In that the gap between the wobble prevention member (25') and the input member (24) is adjusted with an adjustment screw (26) capable of being screwed into and unscrewed out of the hub side of the wheel (2). A manually operated, motor-assisted wheelchair according to at least one of the preceding claims 1 to 16, characterized in that said manual force detecting means (27) further comprising springs (19,20) and that the structure for holding said springs (19,20) comprising a retainer (24) having a groove with a first width (W 1 ), said retainer (24) faces a hand rim disk (14) from one side, that the wheel hub (2a) is provided with a groove having a second width (W 2 ) facing said hand rim disk (14) from the other side of said hand rim disk (14), that said hand rim disk (14) Is provided with a rectangular hole (14a) for receiving said springs (19,20), said rectangular hole (14a) having a third width (W 3 ), said three widths (W 1 ,W 2 ,W 3 ) are fulfilling the following inequations: W 1 > W 3 and W 2 > W 3 said retainer (24) being circumferentially adjustably secured to a wheel hub (2a).

Inventors: KANNO NOBUYUKI, TANAKA HIROSHI, KANNO, NOBUYUKI, TANAKA, HIROSHI
Applicants: YAMAHA MOTOR CO LTD, YAMAHA HATSUDOKI KABUSHIKI KAISHA
Application year: 1997
Main classification: A61G5
IPC codes: A61G5