JPH1057424A - Wheelchair with motor drive assist device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a response to the operation of a hand rim. SOLUTION: An almost cylindrical torsion bar 60 is provided concentrically to the outer periphery of the axle 30 of a wheelchair with a motor drive assist device, one end of the torsion bar 60 is fixed to the hand rim 6 and the other end is fixed to a wheel 4. A potentiometer 70 with a slip ring is provided on the outer periphery of the torsion bar 60 and a torsion angle of the torsion bar 60 is detected. By assisting and driving a motor 8 based on the detected torsion angle, the play of a torque detection means is eliminated and the response of motor drive assist to the operation of the hand rim 6 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wheelchair with an electric assist device.

[0002]

2. Description of the Related Art A wheel rotatably supported via an axle and a hand rim concentrically mounted on a side surface of the wheel are provided, and a manual torque applied to the hand rim is detected. A wheelchair with an electric assist device that drives a wheel by a motor to compensate for the problem is known, and Japanese Patent Application Laid-Open No. 6-304205 measures a torque applied to a hand rim by using a strain gauge as a distortion amount of a connecting portion connecting the wheel and the hand rim. Things are shown.

[0003]

By the way, in the above conventional example, when detecting the amount of distortion of the connecting portion between the axle and the hand rim, since the amount of displacement of the object to be detected is extremely small, a strain gauge is used as torque detecting means. I have.

However, when a strain gauge is used as the torque detecting means, its output is a very small voltage, so that it is desired to improve reliability such as noise resistance and temperature drift durability.
This increases the cost because an amplifier circuit is required, and also detects elements other than the rotational force as operating torque, resulting in an assist error.To avoid this, it is necessary to provide a large number of strain gauges. There were problems such as being up.

[0005]

Means for Solving the Problems To solve the above problems, the invention according to claim 1 comprises a wheel rotatably supported via an axle, and a hand rim mounted concentrically on a side surface thereof. In a wheelchair with an electric assist device that assists driving of wheels by a motor to supplement human power applied to a hand rim, a substantially cylindrical torsion bar is provided in the wheel of the wheel, and one end of the torsion bar is fixed to the hand rim side. The other end is fixed to the wheel side, and the motor is assisted based on the torsion angle detected by the torsion angle detecting means for detecting the torsion angle of the torsion bar.

The invention according to claim 2 is characterized in that an axle passes through the center of the hollow portion of the torsion bar.

The invention according to claim 3 is characterized in that one end of the torsion bar is directly fixed to a hand rim hub provided at the center of the hand rim.

The invention according to claim 4 is characterized in that both ends of the torsion bar are arranged between an axle and bearings provided between bosses of a hub into which the axle is inserted.

The invention according to claim 5 is characterized in that the torsion angle detecting means is a potentiometer with a slip ring provided on the outer periphery of a torsion bar.

According to a sixth aspect of the present invention, the potentiometer with a slip ring includes an operating portion based on an input of a hand rim, and a torque difference detecting portion, and the operating portion and the detecting portion face each other across a torsion bar. Is characterized in that:

The invention according to claim 7 is characterized in that the amount of displacement in the detecting section is amplified more than the amount of displacement in the operating section.

[0012]

According to the first aspect of the present invention, a substantially cylindrical torsion bar is provided in the wheel, one end of the torsion bar is fixed to the hand rim, and the other end is fixed to the wheel. In addition, the motor is assist-driven based on the torsion angle detected by the torsion angle detecting means for detecting the torsion angle of the torsion bar. For this reason, even if the torsion bar is large in diameter, the torsion bar is hollow and can be sufficiently twisted. Further, since the diameter is large, the amount of displacement of the detection target increases, and the reliability of measurement is improved. In addition, there is no need to consider operation torque other than rotation,
Since it is sufficient to provide only one twist angle detecting means, the cost can be reduced.

According to the second aspect of the present invention, since the axle passes through the center of the hollow portion of the torsion bar, the inside of the hollow portion of the torsion bar can be effectively used to save space.

According to the third aspect of the present invention, since one end of the torsion bar is directly fixed to the hand rim hub provided at the center of the hand rim, the torsion bar and the hand rim are integrated without play. The assist drive can be performed with good response to the human power applied to the hand rim.

According to the present invention, both ends of the torsion bar are disposed between the axle and each bearing provided between the bosses of the hub into which the axle is inserted. The torsion bar can be accurately twisted in the direction of wheel rotation without falling down.

According to the fifth aspect of the present invention, since the torsion angle detecting means is a potentiometer with a slip ring provided on the outer periphery of the torsion bar, the output voltage thereof can be increased, so that an amplifier circuit and the like can be obtained. Need not be provided, and costs can be reduced.

According to the sixth aspect of the invention, a potentiometer with a slip ring includes an operating portion based on an input of a hand rim and a torque difference detecting portion, and the operating portion and the detecting portion face each other across a torsion bar. Since it is located at the position, the space for mounting the potentiometer with the slip ring can be minimized.

According to the seventh aspect of the present invention, since the displacement in the detecting section is amplified more than the displacement in the action section, the detection accuracy can be further improved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to the drawings. 9 is a rear view of the wheelchair with the electric assist device shown partially cut away, FIG. 10 is a side view thereof, and FIG. 11 is a plan view partially omitted and cut away.

As is apparent from these figures, the wheelchair with the electric assist device according to the present embodiment has wheels 4 provided on both sides of the seat 2, and a concentric hand rim having a smaller diameter than the wheels 4 is provided outside the wheel 4. 6 are attached.

These wheels 4 are assist-driven by motors 8 provided on the left and right sides, respectively, and the assist is in accordance with the rotational torque of the human power applied to the hand rim 6 to rotate the wheels 4.

At both ends of the rear cross member 10, there are provided brackets 12 which stand up, respectively. Outside the brackets 12, brackets 14 which extend substantially parallel in the vertical direction are connected to the left and right ends of the cross member 10. ing.

A boss 18 formed at the base end of a seat frame 16 which is formed in a substantially quadrangular shape as viewed from the front is supported between the upper ends of the brackets 12 and 14.

A cushion 20 is attached to the seat frame 16 so that the backrest 2a of the seat 2 can be folded freely.

A main frame 22 (see FIG. 10) is attached to the lower end of the bracket 14 and extends forward and downward toward the front of the vehicle body. A caster 26 is mounted.

Outside the lower end of the bracket 14,
The wheel 4 and the hand rim 6 are coaxially mounted via an axle 30, a motor 8 is disposed inside the bracket 14, and mounted on the lower surface of the cross member 10 via a guide member 32 for attachment and detachment. I have.

The frame for supporting the seating portion 2b constituting the seat 2 together with the backrest portion 2a includes a pair of left and right side members 13 provided in the front-rear direction and cross members 10 and 11 provided in the front-rear direction in the transverse direction. And a cushion 34 is mounted thereon.

A battery case 3 is provided below the seat 2b.
5 has its flange portion supported on the upper surfaces of the cross members 10, 11 and the left and right side members 13, and is housed in a space surrounded by these frame members.

A battery 40 for driving the motor 8 and a control unit 42 are housed in the battery case 35. The control unit 42 includes the motor 8
Is driven auxiliary according to the rotational torque applied to the hand rim 6.

A hand brake 4 is provided on one side of the front of the seat 2b.
6 are provided (see FIG. 11) so that the wheels 4 can be braked.

Next, the structure near the axle 30 will be described with reference to FIGS. FIG. 1 is an enlarged cross-sectional view showing the wheel 4 on the left side of the wheelchair below the axle 30, FIG. 2 is an enlarged cross-sectional view showing the vicinity of the axle 30, and FIG. 3 is an overall perspective view of the torsion bar. .

As is clear from FIGS. 1 and 2, a hub 50 is provided at the center of the wheel 4 and a driving flange 52 constituting the hub 50 is connected to a rim 55 via a spoke 54, and is connected to the rim 55. Has a tire 56 attached.

A substantially cylindrical torsion bar 60 is inserted and supported inside the boss 52a of the drive flange 52 via a bearing 58.
The axle 30 is inserted through the collar member 62 inside.

A bearing 64 is interposed between the collar member 62 inside the bearing 58 and the inner peripheral surface of one end of the torsion bar 60, and the other end of the collar member 62 near the other end of the torsion bar 60 is driven. A bearing 66 is interposed between the flanges 52.

A motor gear 68 provided at the end of the drive shaft 67 of the motor 8 is located near the outer peripheral surface of the drive flange 52. The motor gear 68 is connected to the drive flange 52
Meshes with the internal teeth of the ring gear 69 which rotates integrally with the ring gear 69.

A potentiometer 70 with a slip ring, which will be described later, for detecting the torsion angle of the torsion bar 60 is inserted into the concave space of the hub 50 formed on the outer periphery of the boss 52a of the drive flange 52. It is housed in shape.

Potentiometer 70 with slip ring
Are fastened to the inner surface of the outer peripheral wall 53 of the drive flange 52 by bolts 57.

A mounting projection 86 protruding from one side of the potentiometer 70 with a slip ring penetrates a transparent hole 52c formed on the side of the drive flange 52 and protrudes outward, and is connected to the torsion bar 60 side. Have been.

A guide projection 88 projecting from the other end surface of the potentiometer 70 with a slip ring is fitted into a cylindrical portion 51 a formed inside the inner wall 51 of the hub 50.

As is apparent from FIG. 3, the torsion bar 6
A serration 60a is formed on the outer periphery of one end of the zero, a flange portion 60b is formed on the other end, and a lightening hole 60c is formed in the middle portion at equal intervals in the circumferential direction.

On the flange portion 60b, a nut portion 60e and a bifurcated stopper engaging portion 60g are formed at symmetrical positions with a pair at 90 ° intervals.

As shown in FIG. 2 again, the torsion bar 6
A hand rim hub 6a provided at the center of the hand rim 6 is attached with a screw 60d.

The nut portion 60e of the flange portion 60b has
The screw 60f attached to the attachment protrusion 86 is engaged.

The head of the screw 60f is located in a notch 6c formed in the hand rim hub 6a.

The serrations 60a are engaged with serrations 52b formed on the inner periphery of one end of the boss 52a.

For this reason, one end of the torsion bar 60 is integrally rotated by the serrations 60a and 52b, and the other end is formed by the flange 60b and the hand rim hub 6a.
The connection at d allows the torsion bar 60 to be twisted according to the torque difference of the hand rim 6.

The stopper pin 6b provided on the side wall of the driving flange 52 and protruding outward is provided with a flange portion 60b.
When the rotation angle of the hand rim 6 with respect to the wheel 4 exceeds the assist range (see FIG. 8 described later), the stopper functions as a stopper.

Next, the structure of the potentiometer 70 with a slip ring will be described with reference to FIGS. FIG.
FIG. 5 is a conceptual view of the vicinity of a fulcrum in the axle-direction section of the potentiometer 70 with a slip ring (only the upper half is shown). FIG. FIG. 6 is an overall sectional view of the slider section taken along line 6-6 in FIG.

Potentiometer 70 with slip ring
Surrounds the circumference of the cylindrical portion 52a of the drive flange 52 and the torsion bar 60 in a ring shape, and the hand rim hub 6a (see FIG. 2) via the mounting projection 86 and the screw 60f.
, The outer wall 70b connected to the outer wall 53 (same) via the bolt 57, and the fixed member connected to the inner wall 51 (same) via the guide projection 88 and the tubular portion 51a. It has a housing consisting of the wall 70c.

A slider 71 having a substantially ring shape and a slip ring 73 are arranged in the housing at an interval in the direction of the center axis of the potentiometer 70 having the slip ring.

The slider 71 is connected by a fulcrum shaft 76a projecting from the rotor 70a, and serves as a swing fulcrum 76 of the slider 71. As shown in FIG. 6, the projection 72a formed on the outer periphery near the fulcrum is connected to the inner periphery of the outer peripheral wall 70b by the return spring 74.

The symmetrical position in the diameter direction of the slider 71 forms an action point 78, at which an output pattern 82, which is a resistor brush, protrudes in the central axis direction (FIG. 5).

The slip ring 73 is supported by a substrate fixing portion 80 formed on the inner peripheral side of the outer peripheral wall 70b, is configured as a substrate in which a predetermined circuit is incorporated, and has a plate spring shape which slides on a sliding contact surface on the back surface. The output is output to the outside of the potentiometer 70 with a slip ring via the slip contact 77. A resistor 86 is formed at a position where the output pattern 82 slides.

Since the swing fulcrum 76 rotates on the concentric circle of the center axis of the potentiometer 70 with the slip ring,
The force point 72 also moves against the elasticity of the return spring 74, but the force point 72 is pulled back in the opposite direction by the elastic force of the return spring 74 corresponding to this displacement amount.

Therefore, the power point 72 acts as an action portion with respect to the torque input from the hand rim 6. When the power point 72 swings around the swing fulcrum 76 by an operating angle corresponding to the input, the force point 72 is located opposite to the torsion bar 60. The action point 78 of the slider 71 also swings about the swing fulcrum 76 to the opposite side by the same operating angle. At this time, the operation point 78 side is a detection unit.

The operating angle is determined by the output pattern 82 and the resistor 8.
4 can be detected. The slider 71
The play 74 and the hiss can be removed by the spring 74 provided at the force point 72 of FIG.

FIGS. 7 and 8 are graphs showing the results of performance tests of the potentiometer 70 with a slip ring. As is apparent from FIG. 7, an output linearly proportional to the rotation angle, that is, the amount of twist can be obtained. it can.

Further, since the distance between the pivoting fulcrum 76 and the point of action 78 is much larger than the distance between the pivoting fulcrum 76 and the force point 72, the amount of displacement at the detecting portions (82, 84) is amplified, and as a result, Large output is obtained. Further, the width ΔV of the hysteresis when the torsion angle increases and when the torsion angle decreases is extremely small.

FIG. 8 shows the relationship between the torque of the assist driving force and the output, which means that the lower limit value of the assist range can be set up to around ΔV. This torque is proportional to the rotation angle.

Next, the operation of the present embodiment will be described. First,
The human power input by the hand rim 6 is
is transmitted to the torsion bar 60 via a. The torsion bar 60 is twisted in the circumferential direction of the axle 30 by the transmitted human power.

The torsion angle of the torsion bar 60 is adjusted by a potentiometer 70 with a slip ring provided on its outer periphery.
, And the signal is taken into the control unit 42, so that the motor 8 assists the human power with the controlled output and performs the assist drive.

Further, in the present embodiment, the torsion angle of the torsion bar 60 provided on the outer periphery of the axle 30 as a means for detecting the torque applied to the hand rim 6 is further determined by the potentiometer 70 with a slip ring provided on the outer periphery thereof. Therefore, the torque detecting means has a structure in which play and hysteresis hardly occur.

Therefore, even in a wheelchair in which the hand rim 6 is rotated by the occupant's hand, the assist drive can be controlled with good response.

In addition, since the potentiometer 70 with the slip ring detects the force point 72 of the slider 71 at the point of action 78 which is located opposite to the torsion bar 60, the displacement at the point of action 78, that is, the detection angle, is Since the amplitude is greater than the displacement amount of the swing fulcrum 76, that is, the operating angle, the measurement accuracy can be improved.

Further, it is not necessary to consider operation torque other than rotation, and it is sufficient to provide only one potentiometer with a slip ring 70 as twist angle detecting means.
Cost can be reduced.

Further, since the axle 30 passes through the center of the hollow portion of the torsion bar 60, the inside of the hollow portion of the torsion bar 60 can be effectively used to save space.

Further, both ends of the torsion bar 60 in the axial direction are connected to the bearings (58, 58) of the axle 30 and the drive flange 52.
64, 65, 66), the torsion bar 6
0 does not fall down, and the torsion bar 60 can be accurately twisted in the rotation direction of the wheel 4.

Furthermore, since the torsion bar 60 has a hollow cylindrical shape despite its large diameter, it can be easily twisted. Further, since the lightening hole 60c is formed, it is easy to twist and the weight can be further reduced.

Further, since the torsion angle is detected by the potentiometer 70 with a slip ring, the output voltage can be increased, so that it is not necessary to provide an amplifier circuit and the like, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a left wheel.

FIG. 2 is an enlarged sectional view near the left axle.

FIG. 3 is an overall perspective view of a torsion bar.

FIG. 4 is a conceptual diagram of the configuration of a potentiometer

FIG. 5 is an axle vertical sectional view of a sensor portion of the potentiometer.

FIG. 6 is the same drawing of a slider.

FIG. 7 is an output voltage characteristic diagram of the potentiometer according to the embodiment.

FIG. 8 is a hysteresis characteristic diagram of the same.

FIG. 9 is a front view showing a wheelchair partially cut away.

FIG. 10 is a left side view of the same.

FIG. 11 is a plan view of the same.

[Explanation of symbols]

4: wheel, 6: hand rim, 6a: hand rim hub,
8: motor, 30: axle, 60: torsion bar, 7
0: Potentiometer with slip ring

Claims (7)

[Claims] 1. An electric assist system comprising: a wheel rotatably supported via an axle; and a hand rim concentrically mounted on a side surface of the wheel, wherein the wheel is assisted by a motor to supplement human power applied to the hand rim. In the wheelchair with the device, a substantially cylindrical torsion bar is provided in the wheel of the wheel, one end of the torsion bar is fixed to the hand rim side, the other end is fixed to the wheel side, and the torsion angle of the torsion bar is set. A wheelchair with an electric assist device, wherein a motor is assist-driven based on a torsion angle detected by a torsion angle detecting means for detection. 2. A wheelchair with an electric assist device according to claim 1, wherein an axle passes through the center of the torsion bar in the hollow portion. 3. The wheelchair with an electric assist device according to claim 1, wherein one end of the torsion bar is directly fixed to a hand rim hub provided at the center of the hand rim. 4. The electric assist according to claim 1, wherein both end portions of said torsion bar are disposed between an axle and bearings provided between boss portions of a hub into which said axle is inserted. Wheelchair with device. 5. A wheelchair with an electric assist device according to claim 1, wherein said torsion angle detecting means is a potentiometer with a slip ring provided on an outer periphery of a torsion bar. 6. The potentiometer with a slip ring according to claim 1, further comprising an operating portion for inputting a hand rim, and a detecting portion for detecting a torque difference, wherein the operating portion and the detecting portion are located opposite to each other with a torsion bar interposed therebetween. The wheelchair with an electric assist device according to claim 5. 7. The wheelchair with an electric assist device according to claim 6, wherein the amount of displacement at the detecting section is amplified more than the amount of displacement at the action section.