JP3350938B2 - Control device for electric wheelchair - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for an electric wheelchair , and more particularly to a controller for a wheelchair when a protection circuit in the controller is activated.
The present invention relates to a control device for an electric wheelchair which has a certain time allowance to stop after an alarm is generated without immediately stopping power supply.

An electric wheelchair has a maximum speed of 6k on a flat road.
m, it is possible to climb a steep slope with a gradient of 14 ° or more, and by operating only the accelerator lever,
It can perform operations such as starting, speed adjustment, and stopping, and is intended for use by persons with physical disabilities in place of feet.

In such an electric wheelchair , when the protection circuit in the control device is activated, the power supply is not immediately stopped, but a certain amount of time is allowed to stop after the alarm is generated. , Requested.

[0004]

2. Description of the Related Art In general, in an electric wheelchair, it is necessary to lower the center of gravity in order to increase the stability of a vehicle on a steep hill. For this reason, in many cases, the heaviest battery is mounted under a seat. In addition, since the seat surface becomes high, the center of gravity becomes high when a person rides on the seat.

[0005] When a vehicle having such a high center of gravity stops at a location where the inclination is steep, if the vehicle is slightly moved backward, the moment at that time acts on the overturning side, and the vehicle stability decreases. Therefore, it is necessary to stop the vehicle so as not to return. For this reason, there are cases in which the user is warned not to stop or start on a steep slope.

On the other hand, in an electric wheelchair, a control device performs overload protection such as overcurrent protection and temperature rise protection for a motorized wheelchair so as to withstand use on a steep slope. When the vehicle runs continuously on a steep slope, the motor current is suppressed to a certain level by the overcurrent protection circuit, but the temperature rises sharply.

The temperature rise protection circuit generally protects the device by stopping the power supply to the motor when the temperature of the device is detected to be equal to or higher than a certain temperature. Stop the motor. In other words, the driver suddenly stops without the driver noticing, but in this case, the driver cannot afford to prepare for this.

[0008] As a countermeasure against such inconsistent requirements, several proposals have been proposed. One of them is to protect the device, when the temperature reaches a certain level, reduce the current and suppress the heat generation, and at the same time generate an alarm, and when the temperature reaches a second level above this level, turn on the power for the first time. This is a method of completely stopping.

FIG. 4 shows a control method of such a conventional electric wheelchair , in which a temperature rise protection is provided by a temperature sensing element attached to a heat sink of a current control element for a motor. ing. In the figure,
M is a motor, Q1 to Q4 are driving field effect transistors (FETs) for the motor M, and TR1 and TR2 are FETs.
The driving transistor for Q1, TR3 and TR4 are F
A driving transistor for ETQ2, Rs is a shunt resistor for detecting motor current, G1 and G2 are AND gates, I
NV is an inverter, ACCL is an accelerator voltage generator, O
SC is a triangular wave generator, S is a switch for switching between forward (F) and reverse (R), IC1 to IC4 are comparators, Th
Is a temperature sensing element such as a thermistor, Bz is a buzzer, and ABC is an automatic brake circuit.

[0010] accelerator voltage generator ACCL generates an accelerator voltage _{v a} is changed in conjunction with an accelerator device.
The triangular wave generator OSC generates a triangular wave voltage having a constant period. The comparator IC1 compares the accelerator voltage and the triangular wave voltage, and generates a PWM signal having a pulse width that changes according to the accelerator operation intensity.

The AND gate G1 has a changeover switch S
Is open when is in the forward state, and the PWM signal is
Supply to R1 and FET Q3. From this the battery voltage _{V B,} FET Q1, a current flows through the motor M and FET Q3, the motor M is driven in the forward direction.
On the other hand, when the changeover switch S is in the reverse state, the AND gate G2 is opened, and the PWM signal is transmitted to the transistor TR3.
To the FET Q4. As a result, the battery voltage V
_A current flows from _B through the FET Q2, the motor M, and the FET Q4, and the motor M is driven in the reverse direction. Motor M, depending on the PWM signal supplied conduction rate of the current supplied from the battery voltage V _B is by changing is performed a speed control for changing the rotational speed.

The comparator IC2 has a shunt resistor Rs
When the voltage drop exceeds the voltage v _S generated in the voltage divider composed of the resistors r _{1 to} r ₃ , a low-level output is generated to limit the output of the comparator IC1, thereby reducing the current of the motor M. Reduces to a constant value.

The temperature sensing element Th serves as a protection element for performing overload protection in an electric wheelchair .
Be attached to a heat sink for ETQ1～Q4, it generates a voltage _{v O} which increases according to the temperature rise in the detection resistor _{r O.} The comparator IC3 outputs the output voltage v
_{When O} exceeds a certain value v _1, constitutes a voltage divider resistor r
_2, by the low level of the connection point of r _3, at the same time reduces the current limit value of the comparator IC2 to flow reducer a motor M to turn the buzzer Bz. Comparator IC4 is the output voltage _{v O} of the detection resistor _{r O} is a constant value v
_{When 2} (v ₂ > v ₁ ) is exceeded, the accelerator voltage is set to low level to cut off the energization of the motor M, and at the same time, the automatic brake circuit ABC is operated to stop the electric wheelchair .

FIG. 5 shows the motor current I in the case of the system of FIG.
And changes in the temperature T. When the motor is close to the lock and the amount of heat generated by the control element (FET) increases, the temperature of the heat sink increases. Temperature T _{1 (v} voltage detecting the temperature of the heat sink corresponds to v _{1
When 1} ) is reached, the current limiting circuit operates, the current is reduced, and the buzzer sounds to notify the driver that the power supply to the motor is being suppressed. Furthermore, when continuously driven by turning on the accelerator, when the temperature detecting voltage became temperature T _{2 (v 2)} corresponding to v _2, completely blocks the motor current I. Electric this time, since the automatic brake device operates
Wheelchair stops.

Alternatively, there is a method in which an alarm is generated when the temperature of the apparatus reaches a certain level, and the energization is stopped only when the level exceeds this level for a certain time.

[0016]

In the former method, when the temperature reaches a certain level, a current is reduced and an alarm is issued, and when the temperature reaches a second level above this level, energization is completely stopped. An alarm is issued at the same time as the flow reduction. However, in practice, when the electric wheelchair is reduced in flow while traveling on a steep hill, it stops or is in a state close to this. It is unlikely that the vehicle will return backward because the running torque remains, but the driver often performs the operation of setting the accelerator to 0 and stopping at this point. there is a possibility. Also set the accelerator to 0
Even if you try to get off a steep slope, it is difficult to move to a safe (gradient) place to stop because you cannot run as freely as before because of the current reduction condition. There is a problem.

In the latter method, an alarm is generated when the temperature of the device reaches a certain level, and when the level of the higher temperature continues for a certain time, the power supply is stopped. Is counted and the motor is stopped. In this case, since the temperature at the time of stoppage is not constant, a timer must be set in accordance with the temperature rise characteristic in the motor locked state so that the device can be protected even under the worst load condition.

FIG. 6 shows the operation time (t) and the device temperature (T).
Indicates a temperature rise characteristic in a running state, and indicates a temperature rise characteristic in a motor locked state. Since the allowable temperature of the device is fixed,
When the timer operation time Δt is determined with respect to the temperature difference ΔT from when the alarm level is reached in the motor lock state to when the temperature reaches the allowable temperature of the device, in a normal driving state, the time within Δt after the alarm level is reached in the normal driving state. Therefore, there is considerable room for the allowable temperature of the device.

Although it depends on the overcurrent protection method of the device, even if it is overloaded, the temperature rise on a steep slope in a state where the motor can rotate and manage to run is usually close to the characteristic shown in FIG. However, there is a considerable difference from the characteristics in the motor locked state. In actual running, it is desirable that the timer operation time Δt be sufficiently long due to the characteristics described above, so that the electric wheelchair can escape with a sufficient margin. According to this concept, the timer operation time Δt can be determined from the characteristic, and the device allowable temperature ΔT can be determined from the characteristic.
Since the alarm level itself has a low value, there is a problem that an alarm starts immediately when the ambient temperature rises in summer even with a light load.

[0020]

SUMMARY OF THE INVENTION The object of the present invention is to solve such problems of the prior art, and the apparatus is stopped only in accordance with the allowable temperature of the apparatus, but at a lower temperature by a certain temperature. An alarm is issued, and at the time of the alarm, the motor does not flow down, but generates the same torque as before to enable evacuation operation and direction change,
It is intended to provide a margin for operating the emergency handbrake.

[0021]

Means for Solving the Problems According to claim 1 of the present invention,
Electric wheeled chair for performing speed control of the motor M by varying the conduction ratio of the motor current in accordance with the accelerator voltage v _a
In the control apparatus 1 of the child, the first protection means 3 for actuating to an alarm element 2 operates when the output voltage v _O protection elements for performing overload protection of the motor M exceeds a predetermined value v ₁
When, a second protection means 4 output voltage v _O stops the energization of the motor M in the sectional accelerator voltage v _a running time exceeds a predetermined value _{v 2 (v 2> v 1} ), the output voltage v
_A third protection means (not shown) which operates when _O exceeds a predetermined value v ₃ (v ₂ > v ₃ > v ₁ ) to reduce the current supply to the motor M; Is what you do. The predetermined values v ₁ , v ₂ , and v ₃ are determined by the alarm element 2
Evacuate to a safe place even after operation
The direction can be changed even after element 2 has been activated.
You.

According to a second aspect of the present invention, there is provided a control device for an electric wheelchair for controlling the speed of a motor by changing a conductivity of a motor current according to an accelerator voltage.
Fourth protection means that operates when the battery voltage falls below a fourth predetermined value and activates an alarm element, and operates when the battery voltage falls below a fifth predetermined value lower than the fourth predetermined value. And a fifth protection means for cutting off the accelerator voltage and stopping the current supply to the motor. And the fourth and fifth predetermined values are alarms.
Evacuation to a safe place even after the element has been activated, or
The direction can be changed even after the alarm element is activated
I have.

[0023]

[Action] In claim 1 electric wheelchair control device 1 described, the speed control of the motor M by varying the conduction ratio of the motor current in accordance with the accelerator voltage v _a.
In such a device, when the output voltage v _O of the protective element of the temperature-sensitive element or the like for performing overload protection of the motor M is overloaded exceeds a predetermined value v _1, the first protection means 3
Operates to generate an alarm at the alarm element 2, but does not reduce the current to the motor M. Then, the output voltage v _{O of the} protection element further increases and the next predetermined value v ₃ (v ₃ > v)
_{If 1} ) is exceeded, the third protection means operates to reduce the current supply to the motor M. Then, the output voltage v _{O of the} protection element further increases and the next predetermined value v ₂ (v ₂ > v ₃ )
Is exceeded, the second protection means 4 operates and the motor M
Is stopped.

Therefore, since the motor M does not flow down only when an alarm is issued, it is possible to allow the same torque as before to carry out a retreat operation or to give a margin for performing an operation such as a direction change. In addition, when the overload state continues, the power supply to the motor M is stopped, so that damage to the device can be prevented.

In the control device for an electric wheelchair according to the second aspect , when the battery voltage becomes lower than the fourth predetermined value, the fourth protection means operates to generate an alarm in the alarm element. No flow reduction to the motor is performed.
Then, when the battery voltage further decreases and becomes lower than the fifth predetermined value, the fifth protection means operates to stop energizing the motor.

[0026] Therefore, the motor is not depressurized only when an alarm is generated, so that it is possible to allow the same torque as before to perform the evacuation operation or to perform an operation such as a direction change. . Further, when the battery voltage continues to decrease, the current supply to the motor is stopped, so that unstable operation due to a decrease in control ability and early deterioration of the battery can be prevented.

[0027]

FIG. 1 shows a reference example on which the present invention is based. The same elements as those in FIG. 4 are indicated by the same reference numerals. ₃
In that the output side of the comparator IC3 is not connected to the voltage divider of the current limiting circuit.

[0028] As in the case of FIG. 4, the PWM signal generated by the comparator IC1 the output of the accelerator voltage _{v a} a triangular wave generator OSC accelerator voltage generator ACCL, FETQ1～Q constituting the full bridge circuit
4, a current flows through the motor M, and the forward or backward drive is performed. The voltage generated at the shunt resistor Rs is fed back via the comparator IC2 to the output side of the comparator IC1 that generates the PWM signal. As a result, the current of the motor M is limited.

[0029] When the voltage _{v O} generated in the detection resistor _{r O} connected to the temperature sensing element Th in accordance with the temperature increase of the FETQ1~Q4 heat sink exceeds a certain value _{v 1,} the comparator IC3 operates the buzzer Bz . Comparator IC
4 indicates that the output voltage of the detection resistor r _O is a constant value v ₂ (v ₂ > v
₁ ) When exceeding, the accelerator voltage is turned off and the motor M
At the same time, the automatic brake circuit ABC is operated.

FIG. 2 shows changes in the motor current I and the temperature T in the reference example shown in FIG. When the motor is in a state close to the lock, the amount of heat generated by the control element (FET) increases, and when the voltage at which the temperature of the heat sink is detected reaches a temperature T ₁ (v ₁ ) corresponding to a constant value v ₁ , a current limiting circuit is provided. The buzzer sounds regardless of the operation of the vehicle to notify the driver that the vehicle is in an overload condition. In this state, no current reduction or control of the accelerator voltage is performed. Further, when the accelerator is turned on and driving is continued, when the temperature detection voltage reaches a temperature T ₂ (v ₂ ) corresponding to the constant value v ₂ , the motor current I is completely shut off and the automatic brake device is operated. So the electric wheelchair stops.

[0031] Thus, in the case of the present embodiment, even if the alarm is issued becomes overloaded with steep slope, the motor so is not reduced flow or stop can generate a torque so far, therefore electric The wheelchair does not stop or turn back and can be evacuated or turned to a safe place. If the overload state continues thereafter, the power supply to the motor is cut off and the electric wheelchair is stopped, so that burnout of the device can be prevented.

[0032] In one embodiment of the invention, operating the temperature T ₁ of the alarm overload occurs in FIG. 2, at an intermediate temperature Tm of the temperature T ₂ to stop the electric wheelchair, the current limiting circuit of the motor Then, the flow is reduced (see FIG. 4). Also in this case, an alarm is issued before the motor enters the flow reduction state, so that evacuation or change of direction can be performed.

FIG. 3 shows another embodiment of the present invention, in which only essential parts are shown. IC5 and IC6 are comparators for detecting a decrease in the output voltage of another protection circuit.
It is connected to the output side of C3 and IC4.

[0034] The protective circuit output voltage, it is possible to use, for example the battery voltage V _B. 3, when the battery voltage V _B becomes equal to or less than the specified value, since the first comparator IC5 is operated, the buzzer Bz by the output
Is sounded and an alarm is issued as in the case of overload. When the battery voltage _{V B} further decreases, the comparator IC
6 operates, the accelerator voltage is turned off by the output to cut off the energization of the motor M, and at the same time, the automatic brake circuit ABC is operated.

[0035] When the battery voltage V _B is too low, not only leads to premature deterioration of the battery, the control ability of the electric wheelchair is reduced, by doing so, to alert the early further stops energizing This can prevent such an obstacle.

As another example of the output voltage of the protection circuit, a temperature rise of the motor itself detected by the temperature of the yoke of the motor can be used.

[0037]

As described above, according to the first aspect of the present invention, in the electric wheelchair , when the protection circuit in the control device is activated, the energization is not immediately stopped, and the power is supplied immediately after the alarm is generated. Since a certain amount of time is allowed, even if an overload condition occurs during a steep hill climb and an alarm is issued, the motor does not immediately enter the current reduction state. since the vehicle can travel at a speed, there have enough time to retreat to a safe place or or redirecting, can perform treatment such as performing a braking operation of the emergency, previously electric wheelchair to perform such treatment Can be prevented from stopping or returning. Then, when the overload state continues, the energization of the motor is stopped and the electric wheelchair is stopped, so that damage to the equipment can be prevented. In the present invention, in order to perform such control, it is also possible to connect an output of another protection circuit and control alarm and stop in parallel.

According to the second aspect of the present invention, in the electric wheelchair , when the battery voltage drops, the power supply is not stopped immediately, but has a certain time margin before the stop after the alarm is generated. Even if a low voltage condition causes an alarm to be issued, the motor does not immediately enter the current reduction state, and can run at the current torque and speed. Evacuated to
Alternatively, it is possible to perform a measure such as changing direction or performing an emergency brake operation, and it is possible to prevent the electric wheelchair from stopping or returning before performing such a measure. And when the low voltage condition continues,
Since the power supply to the motor is stopped to stop the electric wheelchair ,
Unstable operation and early deterioration of the battery due to a decrease in control ability can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a reference example on which the present invention is based.

FIG. 2 is a diagram showing changes in a motor current I and a temperature T in the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing a control method of a conventional electric wheelchair .

FIG. 5 is a diagram showing changes in motor current I and temperature T in the case of a conventional method.

FIG. 6 is a diagram showing a relationship between an operation time (t) and a device temperature (T).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 control device 2 alarm element 3 first protection means 4 second protection means M motor

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 5/00-5/26 H02P 7/00-7/34 B60L 3/00 B60L 3/06

Claims (2)

(57) [Claims] 1. Conduction of a motor current according to an accelerator voltage
Speed control of motor by changing rate
Electric wheelchairIn the control device, the output voltage of the protection element for performing overload protection of the motor is provided.
Activates when the pressure exceeds a first predetermined value and activates the alarm element
First protection means for causing the output voltage to be in an overload state higher than the first predetermined value.
Operate when a second predetermined value indicating that the
The electric current to the motor is stopped by cutting off the
Second protection means for causing the output voltage to be equal to the first predetermined value and the second predetermined value.
Operate when a third predetermined value between
Third protection means for reducing the current flow to theAnd The first to third predetermined values are determined when the alarm element is activated.
Can be evacuated to a safe place even from
It is set to be able to change direction even after moving,  Characterized byElectric wheelchairControl device. 2. Conduction of a motor current according to an accelerator voltage
Speed control of motor by changing rate
Electric wheelchairThe control device operates when the battery voltage falls below a fourth predetermined value.
A fourth protection means for activating an alarm element; and a fifth protection means, wherein the battery voltage is lower than the fourth predetermined value.
Operates when the voltage drops below a predetermined value and shuts off the accelerator voltage.
Fifth protection to stop power supply to the motor
MeansAnd The fourth and fifth predetermined values are determined when the alarm element is activated.
Can be evacuated to a safe place even from
It is set to be able to change direction even after moving, Electric wheelchair Control device.