JPS5951230B2 - How to start a DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for starting a DC motor used to open and close an electric valve or the like.

Conventionally, the method for opening and closing switching devices such as electric valves is to rotate an AC two-phase motor in the forward or reverse direction, thereby opening and closing the switching device, and when the switching device is fully open or fully closed, operate a limit switch to connect the motor to the motor. A method is used to stop the power supply.

However, since this method uses an AC motor as the driving source for the switchgear, three power sources are required for power supply, and therefore, when using the electric valve for field irrigation, it is necessary to connect the AC motor to the AC power source. The distance to the electric motor becomes long, which is uneconomical. In addition, in the event of a power outage, the electric valve will maintain its opening position before the power outage and will lose its opening/closing function.
Depending on the application, it is necessary to prepare an emergency power source, but an AC emergency power source is uneconomical due to the high equipment cost. As a result of various studies to solve these drawbacks of conventional methods, the inventor of the present invention discovered a very economical method of using a DC motor as a drive valve for a switching device such as an electric power source, and filed a patent application. Patent application 1977-121505, JP 54-5
5818). The method of the invention has the advantage that only two wires are needed to feed power to the motor, and in the event of a power outage, it is sufficient to prepare a simple battery. The method for opening and closing an electric valve, etc. according to the invention will be described below with reference to the drawings. FIG. 1 shows one embodiment of the opening/closing method of the invention, and in the figure, 1 is a DC motor connected to an opening/closing device 2 such as an electric valve, and has a permanent magnet field, and the wiring of this DC motor is shown in FIG. There are two circuits 7 in which diodes 3 and 4 and limit switches 5 and 6 are connected in parallel.
and 8 are inserted such that the directions of diodes 3 and 4 are opposite to each other with respect to the direction of current flow.

Current from a DC power source (not shown) flows from terminal 9 into circuit 7 and through limit switch 5, which is closed.
It flows through the DC motor 1 and the diode 4 of the circuit 8 (the limit switch 6 of the circuit 8 is turned off) to the terminal 10.

If the opening/closing device 2 such as an electric valve is in a fully closed state before the start of energization, the opening/closing device 2 will begin to open as the electric motor 1 rotates forward, and at the same time, the opening/closing device 2 will be interlocked with the opening/closing device 2 by an appropriate method such as a cam mechanism. The limit switch 6 is closed and the circuit 8 is shorted. After a further period of time, when the opening/closing device 2 becomes fully open, the limit switch 5, which is interlocked with the opening/closing device 2 by an appropriate method such as a cam, is turned off, and the current from the DC power source is cut off by the circuit 7, and the motor 1 is stopped. .

Next, when closing the switchgear 2 from the fully open state, switch the direction of the current from the DC power source and pass the DC current through the terminal 10.The current flows through the closed limit switch 6 of the circuit 8, the DC motor 1, Terminal 9 via diode 3 of 7
flows to At this time, the DC motor 1 rotates in the reverse direction, so the switching device 2 connected thereto begins to close, and at the same time, the limit switch 5 whose circuit 7 is disconnected is closed and short-circuited. After a further lapse of time, when the switchgear 2 becomes closed, the closed limit switch 6 is turned off, the current is cut off in the circuit 8, the motor 1 is stopped, and the system returns to its initial state. FIG. 2 shows another method of implementing the invention, in which two circuits 11 and 12 are arranged in series on one line of the wiring of a DC motor 13.

In this case, when a direct current is applied to terminal 14, the current flows through limit switch 15 of circuit 11, diode 16 of circuit 12 (limit switch 17 is turned off), and motor 13 to terminal 18. As the electric motor 13 rotates forward, the opening/closing device 19 starts to open from the closed state, and at the same time, the limit switch 17 closes and the circuit 12 is short-circuited.
After a period of time, when the opening/closing device 19 is fully opened, the limit switch 1
5 is turned off, the current is cut off in circuit 11, and motor 13 is stopped. When closing the switching device 19 from this state, the direction of the direct current is changed and applied to the terminal 18. The current flows through the motor 13, the closed limit switch 17 of the circuit 12,
It flows through the diode 20 of the circuit 11 to the terminal 14. At this time, the motor rotates in the reverse direction, and as the switchgear 19 is closed, the limit switch 15 is closed, creating a short circuit. When the switchgear is fully closed, the limit switch 17 is turned off, cutting off the current, the motor stops, and the system starts. return to the state of
According to the opening/closing method of the invention of the application, since a DC power source is used, the number of power supply and distribution lines can be saved, and the cost of equipment required for emergency power sources etc. can be greatly reduced.

The present inventor further continued his research and arrived at the present invention, and the present invention further consists of connecting a capacitor in parallel to each of the two circuits in which the diode and limit switch are connected in parallel in the wiring of the applied invention. This addition increases the motor torque at startup and eliminates sparks from the limit switch, increasing reliability and service life.

The present invention is connected to a switching device such as an electric valve, and has two circuits in which a diode, a limit switch, and a capacitor are connected in parallel in the wiring of a DC motor having a permanent magnet field. By switching the direction of the current from the DC power supply, the DC motor is rotated forward or backward, thereby opening and closing the switchgear. The limit switch 2 is turned on and the limit switch 2 is turned off.As the switching device opens and closes, the limit switch 2 turns on, and when the opening/closing is completed, the limit switch 1 turns off and the power supply to the motor is stopped. When the power supply to the motor is cut off, the capacitor connected in parallel to the limit switch is charged by the power supply voltage, and then when the voltage is reversed and applied, the charging voltage and the power supply voltage are added together and applied to the motor. This is a method for starting a DC motor in which the starting torque of the motor is increased. An embodiment of the invention is shown in FIGS. 3 and 4.

By adding a capacitor in parallel to each limit switch in this way, the following advantages are produced. For example, when a closing signal is applied from the power supply side, the DC motor rotates in the closing direction, and when the capacitor is closed, the limit switch is turned off, and when the capacitor is supplied with the next current and charging is completed, power supply to the DC motor ends and stops.

After that, when an open signal with the polarity reversed is applied from the power supply side, the voltage of the power supply and the voltage charged in the capacitor are added to the DC motor, and the DC motor starts with a voltage that is approximately twice the power supply voltage. The reliability of electric valves, etc., which sometimes require large torque, can be improved. Furthermore, this capacitor has the effect of eliminating the spark that is generated when the limit switch is turned off, which helps extend the life of the limit switch contact.

[Brief explanation of the drawing]

1 and 2 are drawings for explaining the method for which the present inventor previously applied for a patent (Japanese Patent Application No. 52-121505, Japanese Unexamined Patent Publication No. 54-55818), and FIGS. The figure shows two embodiments of the method according to the invention. 1, 13... DC motor, 2, 19... Opening/closing device such as electric valve, 3, 4, 16, 20... Diode, 5,
6, 15, 17... limit switch, 21, 22,
23, 24... Capacitor 7, 8, 11, 12.
··circuit.

Claims (1)

[Claims] 1 In the wiring of a DC motor that is connected to an electric valve opening/closing device and has a permanent magnet field, connect two circuits in which a diode, a limit switch, and a capacitor are connected in parallel, so that the diode is oriented in the direction of current flow. By switching the direction of the current from the DC power source, the DC motor is rotated forward or backward, thereby opening and closing the switchgear, and at the beginning of opening/closing, limit switch 1 is inserted. is on, the limit switch 2 is off, and as the switchgear opens and closes, the limit switch 2 turns on, and when the opening/closing is completed, the limit switch 1 turns off and the power supply to the motor is stopped. When the switch is turned off and the power supply to the motor stops, the capacitor connected in parallel to the limit switch is charged by the power supply voltage, and the next time the voltage is reversed and applied, the charging voltage and the power supply voltage are in phase with each other. A method for starting a DC motor in which starting torque is applied to the motor to increase the starting torque of the motor.