JPH03212118A - Motor overload protection method and overload protection apparatus - Google Patents

Abstract

PURPOSE:To enable protecting a motor from overcurrent by cutting OFF the supply voltage to the motor independent of the operation of a manual switch while short-circuiting the winding terminal of the motor, when the voltage value of an overcurrent sensing resistor terminal exceeds a set point, and by stopping and holding the motor under regenerative braking. CONSTITUTION:When a motor M is placed in overload state, a motor current IO becomes an overcurrent to raise the voltage across an overcurrent sensing resistor R0. When the voltage across the overcurrent sensing resistor R0 reaches the set point VBE of switching means 14, both transistors TR1 and TR2 are turned On and an auxiliary relay is energized. Then, a movable contact 24a is switched to a fixed contact 24c and the voltage supply to the motor M is cut OFF independent of the operation of a manual switch. In this case, the winding terminal of the motor M is short-circuited and regenerative braking acts on the motor.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention detects an overload state of a motor and stops the motor, thereby limiting the movement range of a movable member and preventing overheating caused by overcurrent. , relates to a motor overload protection method and overload protection device for protecting the motor from damage.

[Conventional technology]

For example, in automobiles and the like, configurations in which movable members are moved by drive control of motors, such as bow trunks, power windows, and power mirrors, are widely known.

In such a configuration, the drive control of the motor is performed, for example, by operating a manual switch consisting of an automatic return type changeover switch, etc., and the movable member is moved in an arbitrary direction depending on the operating direction of the manual switch. .

In such a configuration, the movement range of the movable member is usually limited by various means, and by stopping the motor at the movement limit position, excessive movement of the movable member is prevented, and overload is prevented. It protects the motor from overcurrents that occur.

As a method of limiting the movement range of a movable member, for example,
A configuration is known in which a limit switch is used to detect the movement limit position of a movable member. limit switch R31,
R32 is connected as shown in FIG. 8(A), for example, and is configured to be turned off at the same time as the movable member reaches the movement limit position. In such a configuration, 1. When the manual switch 112 is operated, the limit switch I? S1. ! ? By turning off S2, the voltage supply to the motor arm is cut off, the motor, and in other words, the movable member, is stopped and excessive movement of the movable member is prevented (see Figure 8 (B)). .

In addition, as another means, for example, a stopper that can be latched to the frame of the movable member is provided on the fixed member, and the movement of the movable member is forcibly blocked by the stopper, thereby limiting the movement range of the movable member. The configuration is known. In such a configuration, for example, a thermal protector is built into the motor, and when the thermal protector detects overheating of the motor, it is configured to cut off voltage supply to the motor. According to such a configuration,
Even if you continue to operate the manual switch by mistake after the movable member reaches its travel limit position and is prevented from moving by the stopper, the thermal protector will detect overheating of the motor and the voltage supply to the motor will be interrupted. Since it is shut off, damage to the motor is prevented.

[Problems that the invention attempts to solve]

By the way, for example, in a configuration using a limit switch, when the manual switch 112 is not operated, the relay contacts 120 and 122 are closed as shown in FIG. 8(A).
, via limit switches R5I, R52, etc.
A loop is formed in the circuit, shorting the supply voltage to the motor. Therefore, regenerative braking acts on motor H,
The motor is held stopped by shorting the regenerative braking winding ends.

However, when the manual switch 112 is operated, for example, as shown in FIG. 8(B), the motor control relay RL]
When energized, the movable member reaches the movement limit position,
Limit switch R3I corresponding to the driving direction of motor H
is off, no loop is formed in the supply voltage to the motor. That is, the voltage supplied to the motor is not short-circuited and no regenerative braking is applied to the motor. Therefore, even if the supply voltage to the motor is cut off, the motor will not suddenly stop, and there is a risk that the movable member will overrun due to inertia during movement, and the movement range of the movable member cannot be accurately limited. I can't do it.

In particular, when an overrun of a movable member occurs in a motor control device or the like having a memory function, the amount of overrun is accumulated as an error, which may cause a large deviation in the set position of the movable member.

On the other hand, if the stopper is configured to forcibly prevent the movable member from moving, excessive movement of the movable member is reliably prevented. However, since the movement of the movable member is forcibly blocked while the motor is in the driving state, the motor enters the I-eclipse G state, and the flow of overcurrent into the motor is unavoidable.

In addition, even if you continue to operate the manual switch after the movable member has stopped, if the motor overheats due to overcurrent and the motor temperature exceeds the set temperature of the built-in thermal protector, the thermal protector will operate and the supply voltage will decrease. Be cut off. However, in order to restart the motor after the thermal protector is activated, it is necessary to wait until the temperature around the thermal protector cools down to below the set temperature. Therefore, the motor cannot be restarted easily.

In order to mechanically prevent the movement of the movable members, for example, the strength of the stopper, the mounting location of the stopper, and the frame of the movable member that is locked with the stopper is reinforced to sufficiently prevent deformation of each member. The structure shall be designed to prevent Such reinforcement of fixed members, movable members, etc.
This is not preferable because each member, that is, the entire device may become larger and heavier.

Furthermore, in the above-mentioned known methods, importance is placed on limiting the movement range of the movable member and stopping the motor at the movement limit position. Conversely, it is difficult to detect an overload state of the motor due to mechanical blockage (mechanical blockage) or the like within the movement range of the movable member, so that the motor cannot be sufficiently protected from overcurrent.

This invention reliably limits the movement range of the movable member, and also reliably detects the overload condition of the motor at either the movement limit position of the movable member or at any position within the movement range, thereby preventing the motor from overcurrent. The present invention aims to provide an overload protection method and an overload protection device for a motor to be protected.

[Means to solve the problem]

In order to achieve this object, according to the motor overload protection method of the present invention, the voltage value of the overcurrent detection resistor terminal connected in series with the motor is detected, and the voltage value of the detection resistor terminal and the switching means are The preset setting value is monitored and compared during manual switch operation. and,
When the voltage value at the overcurrent detection resistor terminal exceeds the set value,
It is determined that the motor is overloaded, and the switching means is activated to cut off the supply voltage to the motor, regardless of the operation of the manual switch. Short circuit, stop the motor, and hold.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a motor overload protection device 10 according to an embodiment of the present invention includes a manual switch 12,
Switching means 14, switching member 16, and motor control relay RL1. l? L2 and overcurrent detection resistor R
o. The motor overload protection bag ff1lO is configured to be able to control the drive of the motor A by operating the manual switch 12. A DC geared motor is usually used as the motor arm, and the motor is installed as a drive source for movable members (not shown) such as a seating posture control device and various mirrors.

As shown in FIG. 1, as a manual switch 12,
For example, a movable contact 12a and a two-position fixed contact 1
2b and 12c, and has a neutral position where the movable contact does not touch any of the fixed contacts.For example, the movable contact 12a of a manual switch can be used as a power source for a motor stand, etc. The battery 18 is connected to the battery 18.

Motor control relays RLI and 1iL2 are connected to fixed contacts 12b and 12c of the manual switch, respectively. Motor control relay RL1. As RL2, for example, an electromagnetic relay that opens and closes the contacts by passing current through a coil can be used, and the relay RLI
, RL2 are respectively connected to the supply voltage to the motor and are interposed between the motor stand and the battery 18, as will be described later.

The relay contacts 20 of the motor control relay RLI include, for example, a movable contact 20a and two fixed contacts 20b, 2.
0c, the movable contact 20a is connected to the supply voltage to the motor stand, and the fixed contacts 20b and 20c are connected to the power supply side. Also, motor control relay 1?
Similarly to the relay RLI, the L2 relay contact 22 includes a movable contact 22a connected to the voltage supplied to the motor base, and fixed contacts 22b and 22c connected to the power supply side. As shown by the solid line in FIG. 1, motor control relays RL1. When RL2 is de-energized, the movable contacts 20a and 22a are in contact with the fixed contacts 20b and 20b, respectively, and when the relay is energized, for example, as illustrated by the movable contact 20a indicated by the dashed line,
They are switched to fixed contacts 20c and 22c, respectively.

Further, an overcurrent detection resistor RO is connected in series with the motor stand and is configured to be able to detect overcurrent flowing into the motor. When motor current 1o flows through overcurrent detection resistor RO, a voltage calculated by IoXRo is generated at the resistor terminal, and as described later, the overload state of the motor is detected from this voltage value.

The overload protection device 10 of the present invention further includes a switch notching means 14 and a switch notching member 16. The switching means 14 is, for example, 2
From the combination of transistors TR1 and TR2, on,
A voltage value that is formed to perform off-switching and is compared with a voltage value at the terminal of the overcurrent detection resistor RO is set in advance. The setting value of the switching means 14 is, for example,
The voltage VBE is set as the base-emitter voltage VBE of the transistor TRI, and the voltage VBE and the voltage value at the terminal of the overcurrent detection resistor Ro are constantly compared.

For example, the setting value of the switching means 14 (the voltage VBE of the transistor TRI) is normally set to be larger than the voltage value at the terminal of the overcurrent detection resistor RO, which is applied during steady driving of the motor stand. Then, due to the overload state of the motor, the overcurrent motor current IO is transferred to the overcurrent detection resistor RO.
When the voltage value at the terminal of the detection resistor reaches the voltage VBE, it is determined that the motor is in an overload state, and the switching means 14, that is, the transistors TR1, 71-2 are both turned on.

Here, at the time of starting the motor stand, a large current flows through the overcurrent detection resistor RO, and the voltage value at the terminal of the detection resistor Ro instantaneously becomes larger than the set value (VBE) of the switching means 14. Therefore, for example, the voltage value at the terminal of the overcurrent detection resistor Ro and the setting value of the switching means 14 are compared with the voltage value at the terminal of the overcurrent detection resistor Ro using the time constant of the resistor R1 and the capacitor CI.
It is configured to delay the start of the engine for a predetermined period of time.

Further, as the switching member 16, for example, an auxiliary relay RL3 connected to turn on and off the switching means 14 is used, and the relay contact 2 of the auxiliary relay
4 is interposed between the battery 18 and the relay contacts 20.22 of the motor control relay.

Auxiliary relay 1? As L3, for example, motor control relay RLI, I? Similar to L2, an electromagnetic relay can be used.

For example, the movable contact 24a of the relay contact 24 is connected to the fixed contacts 20c and 22c of the motor control relay, the fixed contact 24b is connected to the battery 18, and the fixed contact 24G is connected to the fixed contacts 20b and 22b of the motor control relay. . The movable contact 24a of the auxiliary relay contacts the fixed contact 24b when deenergized, and as the switching means 14 is turned on, the auxiliary relay 1? When L3 is energized, it is switched to fixed contact 24c.

The operation of the overload protection device 10 as described above will be explained with reference to the circuit diagram of FIG. 1 as well as the time charts of FIGS. 2 and 3.

As shown by the solid line in Figure 1, the manual switch 12
When not operated, motor control relays RL1 and RL
2 are both deenergized, the movable contact 20a of motor control relay RLI becomes the fixed contact 20b, and the movable contact 20a of motor control relay RLI becomes the fixed contact 20b.
The movable contacts 22a are in contact with the fixed contacts 22b, respectively. Furthermore, when the manual switch 12 is not operated, the motor A is in the normal state, so the auxiliary relay RL3 is deenergized as shown in FIG. 2, and the movable contact 24a is in contact with the fixed contact 24b.

At this time, the voltage supplied to motor A is the same as motor control relay RL1. Short-circuited through relay contacts 20 and 22 of RL2, as shown in Figure 2, regenerative braking is applied to the motor,
The motor remains stopped.

From this state, for example, by operating the manual switch 12, as shown by the dashed line in FIG.
When the movable contact 12a is brought into contact with the fixed contact 12b, the second
As shown in the figure, the motor control relay RLI is energized, and the movable contact 20a of the relay RLI is switched from the fixed contact 20b to the fixed contact 20c, as shown by the dashed line in FIG. Then, relay contact 2 of auxiliary relay RL3
4. The supply voltage from the battery 18 is applied to the motor N via the relay contact 20 of the motor control relay RLI, and the motor is driven as shown in FIG.

Furthermore, as can be seen from Fig. 2, the overcurrent detection resistor R
The terminal voltage of O is the set value VBE of the switching means 14.
Since it is smaller, transistors TR1 and TR2 are both turned off and auxiliary relay RL3 remains deenergized.

After the movable member has been moved to an arbitrary position, when the operating force on the manual switch 12 is released, the movable contact 12a of the manual switch returns to the courtal position. Then, as shown in FIG. 2, the motor control relay RLI is deenergized, the corresponding movable contact 20a is switched from the fixed contact 20c to the fixed contact 20b, the supply voltage to the motor A is cut off, and the motor The supply voltage to the motor is again short-circuited via the relay contact 20.22, and regenerative braking is applied to the motor.

By the way, when the movable member reaches the limit position or is restrained by a mechanical lock or the like while the motor A is being driven due to the operation of the manual switch 12, and the motor becomes in an over-Qa state, the motor current 1o becomes overcurrent. As shown in FIG. 3, the voltage value at the terminal of the overcurrent detection resistor RO is increased.

Then, when the voltage value at the overcurrent detection resistor RO terminal reaches the set value VBE of the switching means 14, both transistors TR1 and TR2 are turned on, and the auxiliary relay RL3
Current flows to energize the auxiliary relay. Then, the movable contact 24a of the auxiliary relay RL3 is switched from the fixed contact 24b to the fixed contact 24c, and the voltage supply to the motor H is cut off regardless of the operation of the manual switch, and the motor is immediately stopped.

At this time, since the manual switch 12 remains operated, the motor control relay RLI is in an energized state, and the movable contact 20a of the relay RLI is replaced by the fixed contact 20c.
is in contact with. That is, the supply voltage to the motor 8 is short-circuited via the relay contacts 20, 22, 24, and regenerative braking acts on the motor. Therefore, the motor A short-circuits the regenerative braking winding terminals and is stopped.

Here, the transistors TR1 and TR2 are configured to remain on even if the voltage at the terminal of the overcurrent detection resistor Ro becomes zero, and each transistor is , is considered off. In other words, when the manual switch 12 is turned on - degree
As long as transistors TR1 and TR2 are operated,
is maintained in the on state, and the movable contact 24a of the auxiliary relay RL3 is brought into contact with the fixed contact 24C. Therefore,
Even if the motor is stopped in an overloaded state within the movement range of the movable member, regenerative braking is reliably applied to the motor, and the accuracy of stopping the motor is improved.

Then, when the operating force of the manual switch 12 is released, the movable contact 128 returns to the neutral position, the manual switch is turned off, the motor control relay RLI is deenergized, and the corresponding movable contact 20 is connected to the fixed contact 2.
Switched from 0c to fixed contact zob. Then, the voltage supplied to the motor control relay RL1. Via the relay contact 20.22 of RL2, it is again short-circuited and the motor is held at rest by regenerative braking. In other words, the manual switch 12 is used to hold the motor A stopped by regenerative braking.
It continues even after you turn it off.

At this time, the voltage supply to transistors TR1 and TR2 is also cut off, so as shown in FIG. 3, each transistor is turned off and auxiliary relay RL3 is deenergized. Then, the movable contact 24 of auxiliary relay RL3 is switched from fixed contact 24c to 24b, and auxiliary relay 1? The L3 relay contact returns to its initial state.

As described above, the overload protection voltage value of the motor of the present invention and the preset value VBE set in the switching means 14 are monitored and compared while the manual switch 12 is being operated. And overcurrent detection resistor R.

When the voltage value of the terminal reaches the set value VBE, it is determined that the motor is overloaded, and the switching means 14 is activated to cut off the voltage supplied to the motor regardless of the operation of the manual switch, and At the same time, the regenerative braking winding terminals are short-circuited to stop and maintain the motor.

In other words, if the movement limit position is reached or the movement of the movable member is blocked by a moving mechanical block or the like and the motor N becomes overloaded, the voltage supply to the motor will be interrupted at any position of the movable member. is cut off, short-circuiting the winding terminals of the braking force of regenerative braking, and stopping immediately. Therefore, for example, overrun of the movable member at the movement limit position is reliably prevented, and the movement range of the movable member can be accurately limited. Therefore, even in a motor control device or the like having a memory function, since no cumulative error occurs, the movable member can be reliably returned to the memory position.

Furthermore, upon detection of an overcurrent flowing to the motor as the movable member reaches the movement limit position, the motor is immediately stopped. In other words, unlike known configurations using a thermal protector, after the motor is locked, -El, the manual switch 12 can be turned off to return the motor N to its normal state, without waiting for the temperature of the thermal protector to drop. The motor can be restarted easily.

When the movement of the movable member is blocked at the travel limit position, the motor is immediately stopped, so the motor is not restrained for a long time, and there is a strong force around the stopper that prevents the movable member from moving at the travel limit position. No force acts. Therefore, there is no need to reinforce the fixed member around the stopper, the frame of the movable member, etc., and the fixed member and the movable member can be made smaller and lighter.

Further, according to the motor overload protection device 10 of the present invention, despite the simple configuration, the above motor overload protection method can be properly performed, and the motor can be accurately protected from overcurrent. At the same time, the stopping accuracy of the motor can be sufficiently improved.

In addition, in the embodiment, explanation is given assuming that the movable contact 12a of the manual switch is operated to the fixed contact 12b side, but conversely, when the movable contact 12a is operated to the fixed contact 12c side. The same operation as above is also performed in . However, in this case, by bringing the movable contact 12a of the manual switch into contact with the fixed contact 12c, motor control relay RL2 is energized and the corresponding relay contact 22 is switched, so that the motor rotation is reversed.

In the embodiment, the switching means 14 comprises two
transistor TI? 1. Although it is formed by combining TR2, it is not limited to this, and may be formed from one small power thyristor (SCR), for example. The supply voltage to N is cut off, and the supply voltage to the motor is short-circuited. However, the present invention is not limited thereto, and for example, as in the second embodiment of the present invention shown in FIG.
The switching member 16 may be used to cut off the voltage supplied to the motor or to short-circuit the voltage supplied to the motor.

Motor overload protection device 11 of the second embodiment shown in FIG.
0, for example, the parallel diodes D1. Motor control relays RLI and RL2, each equipped with D2, are connected to fixed contacts 12b and 12c of the manual switch, respectively. Also, for example, diode D3゜D
4, the switching means 14 and the switching member 16 are connected to the fixed contacts 12b, 12c of the manual switch.

The operation of the motor overload protection device 110 in the second embodiment of the invention as described above will be explained with reference to the circuit diagram of FIG. 4 as well as the time charts of FIGS. 5 and 6. do.

As shown in FIGS. 4 and 5, the manual switch 12
When the motor is not operated, the voltage supplied to the motor is short-circuited, and regenerative braking is applied to the motor to keep it in a stopped state.

In such a state, when the manual switch 12 is operated and, for example, the movable contact 12a is brought into contact with the fixed contact 12b, since the transistors TR1 and TR2 are off, the current from the battery 18 is transferred to the diode D4.
, the resistor R2, and the Zener diode 201 to flow into the transistor TR3. Then, as shown in FIG. 5, transistor TR3 is turned on, motor control relay RLI is energized, and the corresponding movable contact 20a is -
As shown by the dotted chain line, from the fixed contact 20b to the fixed contact 20
can be switched to c. Then, by switching the relay contact 20 in conjunction with the energization of the motor control relay RLI, current from the battery lδ passes through the relay contact 2o, the motor A, and the relay contact 22 to the overcurrent detection resistor Ro.
, and the motor is driven in any direction.

At this time, the voltage at the terminal of the overcurrent detection resistor Ro and the set value VBE of the switching means 14 are constantly compared.

Since the terminal voltage is smaller than the set value, the transistor T
Both R1 and TR2 are kept off.

Then, from this state, the manual switch 12
When turned off, the base current of the transistor TR3 is cut off, so the transistor TR3 is turned off. Then, as transistor TR3 is turned off, motor control relay RLI is deenergized, and the corresponding movable contact 20a is switched from fixed contact 20c to fixed contact 2°b. Then, the voltage supplied to the motor is cut off, the voltage supplied to the motor is short-circuited, and regenerative braking is applied to the motor, so that the motor is stopped by regenerative braking.

By the way, when the motor is in an overload state, the motor current 1o becomes an overcurrent, and the voltage value at the terminal of the overcurrent detection resistor Ro increases. Then, the voltage value at the terminal of the overcurrent detection resistor Ro increases, and as shown in FIG.
When the set value VBH of 4 is reached, the transistors TR1 and T
Both R2 are turned on. Here, transistor TR1
, TR2 are turned on, the current flowing through the manual switch 12 and the diode D4 flows more easily into the transistors TR1 and TR2 than the Zener diode ZDI, so the Zener diode ZDI, )
Langista TI? The node potential VE of the emitter No. 2 drops to a low level (approximately below IV).

At this time, if the Zener voltage of the Zener diode 201 is set higher than the connection point potential VE at low level, at the same time as the connection point potential VE decreases, the transistor TR
Current no longer flows to the base of transistor TR3.
is turned off. Then, since no current flows to motor control relay RLI, relay RLl is deenergized regardless of the operation of manual switch 12, and relay contact 2o
is switched and motor A is stopped. The movable contact 20a of the motor control relay RLI is connected to the fixed contact 20a.
c to the fixed contact 20b, the supply voltage to the motor N is short-circuited via the relay contact 20.22 and regenerative braking acts on the motor.

Then, by releasing the operating force of the manual switch 12 and turning it off, the transistor TRI is turned off.

TR2 is turned off, motor overload protection bag fit 1
10 is returned to its initial state.

As described above, even in the overload protection device 110 configured using the switching member 16 having the Zener diode ZDI and the transistor TR3, the above motor overload protection method can be appropriately performed despite the simple configuration. can.

Note that the overload protection devices 10 and 110 are embodied as overload protection devices that control and protect one motor, as shown in FIGS. 1 and 4, respectively, but they are not limited to this. First, it may be applied to a configuration that controls and protects a plurality of motors.

For example, FIG. 7 shows an overload protection device 210 that controls and protects two motors M2 by applying the overload protection device 11G. Overload protection device 210 with such a configuration
By the same operation as the overload protection device IIO shown in FIG. 4, motor A1. Controls the drive of M2 and protects it from overcurrent.

In such a configuration, for example, in response to the operation of the manual switch 12, the motor control relays RLla, R
Either L2a is energized and the corresponding relay contact 20
．． By switching 22, the drive of the motor M1 is controlled. Further, in response to the operation of the manual switch 13, one of the motor control relays R1, 1b, and l1L2b is energized, and the motor M2 is driven and controlled by switching the corresponding relay contact 21, 23.

In addition, in the overload protection device 210 shown in FIG.
When one or both of the old motor and M2 becomes overloaded, both motors are configured to stop at the same time. According to such a configuration, motor M from overcurrent
1. In addition to protecting M2, the safety of the seated person etc. is ensured within 1 minute.

In this way, a configuration in which a plurality of motors are controlled and protected simultaneously can be particularly effectively used in a power seat or the like in which a trunk slide device, a reclining device, etc. are operated simultaneously.

The motor overload protection method of the present invention is not limited to automobiles, but can be widely applied as a protection method for motors disposed as drive sources for movable members.

The above-mentioned embodiments are for illustrating the present invention, and are not intended to limit the scope of the present invention, and all modifications and modifications within the technical scope of the present invention are also included in the present invention. Needless to say.

〔Effect of the invention〕

As described above, according to the motor overload protection method according to the present invention, the voltage value of the overcurrent detection resistor terminal connected in series with the motor is detected, and the voltage value of the detection resistor terminal and the switching means are set in advance. During manual switch operation, the equipment is monitored and compared with the specified set value. When the voltage value of the overcurrent detection resistor terminal reaches the set value, it is determined that the motor is overloaded, and the switching means is activated to cut off the supply voltage to the motor, regardless of the operation of the manual switch. At the same time, the voltage supplied to the motor is cut off, and the terminals of the regenerative braking windings are short-circuited to stop and maintain the motor. That is, when the motor becomes overloaded, the voltage supply to the motor is cut off at any position of the movable member, short-circuiting the winding terminals of the regenerative braking, and the motor is immediately stopped. Therefore, overrun of the movable member at the movement limit position is reliably prevented, and the range of movement of the movable member can be appropriately limited.

Further, upon detection of an overcurrent to the motor as the movable member reaches the movement limit position, the motor is immediately stopped. In other words, unlike known configurations using thermal protectors, the manual switch can be turned off immediately after the motor is locked, without waiting for the temperature of the thermal protector to fall, and the motor can be returned to its normal state. Easy to restart.

Even if the movement of the movable member is blocked at the travel limit position, the motor is immediately stopped, so the motor is not restrained for a long time, and a strong force is applied around the stopper that prevents the movable member from moving at the travel limit position. does not work. Therefore,
There is no need to reinforce the frames of fixed members and movable members, and the fixed members and movable members, in other words, the entire device, can be made smaller.
Lighter weight can be achieved.

Further, by continuing to cut off the supply voltage to the motor and short-circuit the supply voltage to the motor until the manual switch is turned off, malfunction of the motor can be reliably prevented. Therefore, protection of the motor from overcurrent, improvement of stopping accuracy of the movable member, etc. can be achieved more reliably.

Further, according to the motor overload protection device of the present invention, despite the simple configuration, the above motor overload protection method can be properly performed, and the motor can be accurately protected from overcurrent. , the motor stopping accuracy can be improved within 1 minute.

[Brief explanation of drawings]

Fig. 1 is a schematic circuit diagram of the motor overload protection device according to the present invention, Fig. 2 and Fig. 3 are time charts of the motor overload protection method according to the invention, and Fig. 4 is the schematic circuit diagram of the motor overload protection device according to the present invention. A schematic circuit diagram of a motor overload protection device according to a second embodiment of the invention, FIGS. 5 and 6 are time charts of a motor overload protection method according to a second embodiment of the invention, Figure 7 is a circuit diagram of an application example of a motor overload protection device, and Figures 8 (A) and (B) are operational diagrams of a known motor overload protection device before and after motor protection. be. 10.110.210: Motor overload protection device, 1
2: Manual switch, 14 switch means, 1
6: Switching member, 20.22: Relay contact of motor control relay, 24: Relay contact of auxiliary relay, M
: Motor, Ro: Overcurrent detection resistor, RLl, RL2 :
Motor control relay, TR1, TI? 2: ) transistor (switching means), RL3: auxiliary relay (switching member), ZDI: Zener diode (switching member), TR3: ) transistor (switching member).

Claims (5)

[Claims] (1) Detects the voltage value of the overcurrent detection resistor terminal connected in series with the motor, and monitors the preset value set in the switching means and the voltage value of the detection resistor terminal while operating the manual switch;
When the voltage value at the detection resistor terminal reaches the set value, it is determined that the motor is overloaded and the switching means is activated.
Regardless of manual switch operation, the voltage supply to the motor is cut off, the motor winding terminals are short-circuited, and the motor is stopped under regenerative braking applied to the motor.
How to protect the motor from overload. (2) When it is determined that the motor is overloaded, the voltage supply to the motor is cut off and the winding terminals of the motor are short-circuited until the manual switch is turned off. Motor overload protection method described. (3) Motor drive control using a motor to move the movable member, a manual switch that can arbitrarily drive the motor and adjust the position of the movable member, and switching of the movable contacts as the manual switch is operated. a motor control relay that performs the switching operation, an overcurrent detection resistor connected in series with the motor, a switching means in which a voltage value is preset to be compared with the terminal voltage of the overcurrent detection resistor, and a switching operation performed by the operation of the switching means. a switching member that performs the overcurrent detection, and when the terminal voltage of the overcurrent detection resistor reaches a set value, the switching operation of the switching member in conjunction with the operation of the switching means causes the motor to be A motor overload protection device that cuts off the voltage supply and shorts the motor winding terminals. (4) A switching member is formed from an auxiliary relay with a movable contact interposed between the power source and the motor, and the voltage supply to the motor is cut off by switching the movable contact of the auxiliary relay as the switching means operates. 4. The motor overload protection device according to claim 3, wherein the motor winding terminals are short-circuited. (5) A switching member is formed by a Zener diode and a transistor connected in parallel to the switching means, and a corresponding motor control relay is deenergized by the switching action of the transistor upon activation of the switching means. 4. The motor overload protection device according to claim 3, wherein the voltage supply to the motor is cut off and winding terminals of the motor are short-circuited.