JP2000189464A - Electric wheelchair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce substantial electric power consumption without loss of electromagnetic brake performance, miniaturize a battery used for an electric wheelchair and extend the travel distance by using less current- carrying value for keeping the release state of electromagnetic brake than the rated value of electromagnetic brake. SOLUTION: An electromagnetic brake for an electric wheelchair uses a non magnetization action type. It is the state that, when working a brake, in other words, fixing an electric motor, it does not send the electric current, on the other hand, when releasing the brake, it send the electric current. A current control circuit is worked to send the rated value of DC current to the electromagnetic brake by the command of microcomputer. In operation of the electric wheelchair, the electric current, which is required for keeping the state of releasing the brake, is sent to the electromagnetic brake through the current control circuit. The figure shows the change of the electric current sent to the electromagnetic brake, and the electric current, which is the minimum for need to keep the release is sent as shown by a continuous line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electric wheelchair driven by an electric motor.

[0002]

2. Description of the Related Art Wheelchairs are widely used as a means of transportation when a person has a physical disability or is unable to walk due to old age. This wheelchair is roughly classified into a so-called manual type driven by a user or a caregiver's hand and an electric type driven by an electric motor. In particular, when manual propulsion cannot be obtained due to severe obstacles or old age, the electric type is used. In this electric type, an electric motor is connected to a pair of left and right drive wheels by an appropriate transmission means, while the user operates the wheelchair by inputting a traveling direction by a hand operation unit provided at hand. Let it.

FIG. 1 shows an example of an electric wheelchair. Electric motors are respectively connected to left and right rear wheels via a speed reducer, and a user can turn a hand operation unit and a joystick in a desired direction to signal the signal. Is sent to the control unit below the seat, the conditions for operating the left and right electric motors are determined, and electric energy from the storage battery below the seat is supplied to the electric motors to operate the wheelchair according to the conditions. The conventional electric wheelchair is used internationally as a standard type.

[0004]

The joystick of the hand operating unit is treated as information on the traveling direction and the vehicle speed, depending on the direction in which the joystick is tilted and the tilt angle. On the other hand, when stopping, the joystick is set to a neutral, that is, a vertical position. When the joystick has reached the neutral position, the control unit regards it as a stop signal and smoothly stops the wheelchair at a constant deceleration ratio. The joystick's neutral position is a mechanism that automatically returns to that position when you release your hand from the joystick.
In order to ensure the safety of the electric wheelchair, as a stopping means, according to the brake by the regeneration of the electric motor,
It is usual to add an electromagnetic brake. This electromagnetic brake is generally referred to as a non-excitation operation type, and the brake operates when power is not supplied, and realizes a safe and comfortable stop in combination with the brake operation by the electric motor.
However, when operating the electric wheelchair, the electromagnetic brake needs to release the brake, so that the rated current continues to flow, and the consumption of the storage battery is promoted.
In addition, when the electromagnetic brake is released or the rated current is supplied or cut off during operation, a mechanical shock occurs and the user feels discomfort. When comparing the current for releasing the brake with the current for holding after the release, the non-excitation operation type electromagnetic brake requires a significantly smaller current for holding, for example, 50% of the current for releasing. %. However, when a power supply of a rated voltage is applied, a current required for release, that is, a rated current always flows, thereby promoting consumption of a storage battery.

[0005]

Therefore, when controlling and maintaining the electric energy supplied to the electromagnetic brake, the current required for the control is reduced to reduce the power consumption of the electromagnetic brake and further increase or decrease the current. By controlling, mechanical shock at the time of brake operation can be reduced.
Specifically, it can be realized by connecting a power supply to the electromagnetic brake via a PWM inverter and supplying a current appropriate and necessary for the operation of the electromagnetic brake by PWM duty control.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an electric wheelchair provided with a non-excited operation type electromagnetic brake, in which an energization value for maintaining an electromagnetic brake release state is controlled by a current smaller than a rated value of the electromagnetic brake. In an electric wheelchair having an electromagnetic brake, current consumption can be reduced.

Also, when the electromagnetic brake is released or activated,
The current is limited and the current is gradually increased to the rated value when the current is released, and the current is gradually decreased when the current is activated, so that the electromagnetic brake is not suddenly activated.

The control of the current supplied to the electromagnetic brake may be performed by PWM duty control. Also,
When the joystick is in the neutral position, the electromagnetic brake is activated, and when the joystick is in any other position, the electromagnetic brake is maintained in the released state, so that the electric wheelchair can be easily operated.

[0009]

EXAMPLES (Example 1) Details of the present invention will be described based on examples. FIG. 1 shows an embodiment of the present invention. The left and right driving wheels 1 have an electric motor 2 with a built-in electromagnetic brake and principle mechanism
Are connected, and the electric motor 2 is electrically connected to the main control unit 3. The main controller 3 contains a battery 4 as a driving energy source. The joystick operating unit 5 for operating the electric wheelchair is installed at one of the left and right armrests 7 in front of the seat 6 and is electrically connected to the main control unit 3.

FIG. 2 shows the structure of the motor unit. The motor 2 has a shaft 9 having a gear 8 at one end, and is connected to a driving wheel shaft 10 via a two-stage gear reduction mechanism.
Further, an electromagnetic brake 11 is provided at the other end of the shaft 9, and the brake function of the electric wheelchair is exerted by mechanically fixing or releasing the electric motor shaft 9.

This electromagnetic brake is of the so-called non-excitation type. When the brake is operated, that is, when the motor shaft is fixed, no current flows to the electromagnetic brake, and when the brake is released, the electromagnetic brake is released. This is to supply current to the brake.

FIG. 3 shows an operation circuit of the electromagnetic brake.
When the brake is released, the current control circuit operates according to a command from the microcomputer, and a rated DC current flows through the electromagnetic brake. Thereafter, during operation of the electric wheelchair, a current necessary for maintaining the brake released state is supplied to the electromagnetic brake via the current control circuit.

FIG. 4 shows a change in current flowing through the electromagnetic brake. According to the present invention, a minimum current required for releasing and holding is supplied, and the one shown by a solid line in the drawing corresponds to the present invention. On the other hand, in the conventional example, this is indicated by the one-dot chain line in the figure, and the retention after the release continues to flow at the same rated current as the release. FIG. 5 shows a conventional electromagnetic brake circuit. The current to the electromagnetic brake is controlled by an ON-OFF command of a microcomputer.

(Embodiment 2) FIG. 6 shows a second embodiment of the present invention. When applying a current to the electromagnetic brake, if there is a sudden change in the current, a mechanical shock may be caused, and the change in the current is inclined as shown in the figure for smoother brake operation or release, It has been increased or decreased.

FIG. 7 shows a specific method of the current control.
An embodiment of the present invention is shown in the following, but it can be realized by controlling the duty of the current flowing through the electromagnetic brake by a PWM inverter based on a command from a microcomputer.

[0016]

According to the first, second, and third aspects of the present invention, by controlling the current required for releasing and holding the electromagnetic brake necessary for safety, the performance of the electromagnetic brake is not impaired. Since the substantial power consumption can be reduced, the size of the battery used in the electric wheelchair can be reduced, and the traveling distance can be increased.

According to the second aspect of the present invention, by gradually increasing or decreasing the current at the time of operation, mechanical shock at the time of operation of the electromagnetic brake can be reduced, and a comfortable ride can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electric wheelchair according to the present embodiment.

FIG. 2 is a structural view of the electric motor unit.

FIG. 3 is a block diagram of the electromagnetic brake current control circuit.

FIG. 4 is a diagram showing the operation of the electromagnetic brake and a change in current.

FIG. 5 is a block diagram of a conventional electromagnetic brake control circuit.

FIG. 6 is a diagram showing a brake operation and a current change according to the second embodiment.

FIG. 7 is a block diagram of an electromagnetic brake control circuit according to the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 left and right drive wheels 2 motor 3 main control unit 4 battery 5 joystick operation unit 6 seat 7 armrest 8 motor output shaft gear 9 motor non-output side shaft 10 drive wheel shaft 11 electromagnetic brake

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yukihiro Ashizaki 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An electric wheelchair provided with a non-excited operation type electromagnetic brake, wherein an energization value for maintaining an electromagnetic brake release state is performed with a current smaller than a rated value of the electromagnetic brake. wheelchair. 2. When the electromagnetic brake is released or operated, the applied current is limited. When the electromagnetic brake is released, the current is gradually increased to a rated value.
2. The electric wheelchair according to claim 1, wherein the electric wheelchair is reduced during operation. 3. The control of the current supplied to the electromagnetic brake is controlled by P
The electric wheelchair according to claim 1 or 2, wherein the electric wheelchair is controlled by WM duty control. 4. The electric wheelchair according to claim 1, wherein the electromagnetic brake is operated when the joystick is in the neutral position, and the electromagnetic brake is held in the released state when the joystick is in any other position.