JPH04111900U - Overload detection circuit for DC motor for shutters - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent burnout accidents during overload operation of DC motors for small household shutters. [Configuration] The overload current of the DC motor 17 for a small shutter is detected by the overload detection resistor 1, and when the overload voltage reaches the applied voltage, the motor 17 is stopped.The applied voltage of the protection relay 2 is stabilized by the Zener diode 3. It has been transformed into

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This idea is a safe way to detect overload current in a DC motor used to drive small household shutters. It concerns all equipment.

0002

[Conventional technology]

FIG. 3 is a current control circuit configuration diagram of a conventional shutter driving DC motor. is a push button switch box for opening/closing commands located near the shutter (not shown) 11 is the opening switch of the pushbutton switch box 10, and 12 is the opening switch of the push button switch box 10. It is a stop switch, and 13 is a close switch. 14 is a push button switch Controls the current to stop the motor in forward and reverse rotation according to the opening/closing stop command from 10. 15 is a hold circuit with an inverter configuration to hold the open/close signal. A bidirectional latching relay that switches the motor current according to the forward/reverse command signal from 14. - switch, and 14 and 15 form a hold circuit.

0003 16 is a relay that protects the motor by cutting off the current circuit when overload current flows through the motor. 16a is the contact point of relay 16 for interrupting the current circuit, 15a is the contact point for both forward and reverse rotation. This is a contact on the forward rotation side of the direction latching relay 15, and 15b is a contact on the reverse rotation side. , 17 is a DC motor, and 18 is a rotating shaft of the motor 17 for opening and closing the shutter. connected to a reduction gearhead.

0004 Next, the operation will be explained. Open switch of push button switch box 10 When 11 is pushed, the open line becomes conductive and forward rotation from the hold circuit 15 (temporarily open (if the case is normal rotation) The command causes the normal rotation contact 15a side of the latching relay 15 to When the current contacts of the motor 17 are switched and the motor 17 rotates forward, a current is applied to the rotating shaft 18. The signal is transmitted to the connected reduction gearhead (not shown) and the shutter curtain is raised. When the latching relay 15 is opened and closed, the latching relay 15 is closed by a command signal. 15b switches to the reverse side and maintains that state, so the shutter curtain descends. and close.

[0005] In addition, in the case of stopping, both contacts of the latching relay 15 are repelled by the stop command signal. The motor 17 is short-circuited and is braked by the current Ia caused by the back electromotive force, causing it to stop. Stop. Please note that obstacles, human bodies, etc. may obstruct the shutter while it is opening or closing. If an overload current flows through the motor 17 for some reason, the current circuit is cut off by the relay 16. The voltage of the relay 16 is set to protect the motor 17.

[0006]

[Problem that the idea aims to solve]

The current control circuit of the conventional DC motor for opening and closing the shutter is configured as described above. Therefore, the drive motor is large and expensive, as is the case with large commercial shutters. By using an AC motor, you can protect the motor with a thermal relay and create a complex control circuit. Since it is not possible to take measures such as installing a relay, a small DC motor that is inexpensive and easy to control is used to However, this type of relay has a lot of variation in voltage, making it unreliable. There are problems such as poor performance, and burnout accidents may occur due to the locked state during overload. It was convenient. This idea was made to solve the problems mentioned above, and was designed to prevent overload operation. An object of the present invention is to obtain a device that prevents motor burnout accidents caused by.

[0007]

[Means to solve the problem]

The overload detection circuit of the DC motor for shutter according to this invention is An overload detection resistor connected in series to a DC motor for detecting overload current, and When the overload voltage generated in the load detection resistor reaches the sensing voltage, the voltage of the DC motor is Select and set the protection relay that cuts off and stops the flow and the voltage of the protection relay. It is equipped with a Zener diode.

[0008]

[Effect]

The overload detection circuit of the DC motor for the shutter in this invention has an overload detection resistor. The overload current of the DC motor is detected by the zener diode. Since the DC motor is stopped by the protection relay set to the pressure, the DC motor will not burn out. Loss accidents can be prevented.

[0009]

【Example】

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an overload detection circuit of a DC motor for a shutter, which is an embodiment of this invention. 2 is a protection relay that operates when the overload voltage across _{the resistor R 0 reaches} the sensing voltage, and 2a is the contact point of the protection relay 2, which is a stop switch. This closes the circuit. Other symbols are the same as in the conventional example.

0010 Next, the operation will be explained. The basic operation of opening/closing/stopping the shutter was explained using the conventional example. Since the operation is exactly the same, it will be omitted. If you hit an obstacle left behind while opening or closing the shutter, or if your child If an overload current exceeding the setting is applied to the motor 17 due to a power supply being inserted or for other reasons. If this state continues, the DC motor 17 will burn out. cause an accident. This can be prevented if the current protection relay 16 operates early, but as mentioned above, It lacks reliability due to variations.

Therefore, an overload detection resistor R ₀ is connected in series to the current circuit of the DC motor 17, and an overload detection circuit consisting of a protection relay 2 and a Zener diode 3 is connected in parallel to detect the current of the motor 17 during overload operation. Block out and protect completely.

In this case, for example, if the power supply voltage is set to 24 V DC and the limit of the overload current value of the DC motor 17 is set to 0.3 A, the voltage of the protection relay 2 used in the detection circuit is selected to 6 V, and the voltage of the Zener diode 3 is set to 6 V. Assuming that the Zener voltage Vz is 6V, the sensing voltage of the detection circuit is the sensing voltage of protection relay 2 + Zener voltage Vz, which is 12V.Therefore, by simple calculation, if the sensing resistor _R0 is set to 40Ω, the sensing circuit will be It operates to stop the motor 17 when the overload current value of 0.3A is reached.

[0013] However, protection relay 2 has a limited voltage tolerance within a narrow range due to variations. Since it is difficult to operate at the specified value, connect Zener diode 3 in series with protective relay 2. Then, the voltage of the protection relay 2 is forcibly drawn in by the Zener voltage Vz, Since the sensing voltage is selected and set as the detection circuit, the sensing voltage is made into a constant voltage and can be set reliably. Protective relay contact 2 operated at a constant overload current value and connected to the stop switch circuit a is activated, the stop line becomes a closed circuit, and the current to the motor 17 is cut off. The motor will stop.

Next, another embodiment of this invention will be described. FIG. 2 is a configuration diagram of the overload detection circuit safety device for the shutter DC motor of this invention, in which the contact 2a of the protective relay 2 is connected to the open circuit of the pushbutton switch, and each constant of the detection circuit is the same as that of the previous embodiment. In this case, the overload current setting value is set to 0.3A, but at a time before that state, for example, the current setting value is set to 0.3A. 2A, a detection resistor R ₀ , a protection relay 2, and a Zener diode 3 are selected.

[0015] Next, the operation will be explained. Now press the close switch 13 of the pushbutton switch. If a child accidentally inserts his or her hand while lowering the shutter, motor 17 The load current increases to 0.2A, the detection circuit is activated, and the contact of protection relay 2 is activated. 2a is closed, the shutter open circuit is activated, and the forward/reverse relay switch of the motor 17 is activated. a, the motor 17 reverses to normal rotation, and the shutter automatically reverses and rises. It acts as a safety device.

[0016] If cost permits, the above-mentioned stop circuit for the overload current detection motor 17 and other implementations may be provided. The detection circuit as a safety device for reversing the motor 17 shown in the example is used in a two-stage configuration. It is more effective if used.

[0017]

[Effect of the idea]

As described above, according to this invention, a protective relay that stops the motor when overloaded The operating voltage is stabilized with a Zener diode, resulting in a simple and inexpensive circuit configuration. This has the effect of preventing the motor from burning out and can also be used as a safety device for equipment.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an overload detection circuit for a DC motor for a shutter, which is an embodiment of the present invention.

FIG. 2 is a configuration diagram of an overload detection circuit safety device for a shutter DC motor, which is another embodiment of the present invention.

FIG. 3 is a configuration diagram of a current control circuit of a conventional shutter driving DC motor.

[Explanation of symbols]

1 Overload detection resistor 2 Protective relay 2a Protective relay contact 3 Zener diode 14 Hold circuit 15 Latching relay switch 15a Latching relay contact 15b Latching relay contact 17 DC motor

Claims (1)

[Scope of utility model registration request] Claim 1: A hold circuit that switches and latches the forward and reverse current of the DC motor for driving the shutter opening/closing, an overload detection resistor that is connected in series with the DC motor to detect overload current, and an overload detection resistor that detects overload current. A protection relay for cutting off and stopping the current of the DC motor when the overload voltage reaches the sensing voltage, and a Zener diode for selectively setting the sensing voltage of the protective relay. Load detection circuit.