JP2635348B2 - Split-phase starting Single-phase induction motor starting device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting device for a split-phase starting single-phase induction motor.

2. Description of the Related Art In recent years, single-phase induction motors have been widely used as power sources for machines, and motors and starting devices are required to have lower cost and longer life.

Hereinafter, an example of the above-described conventional starting device for a split-phase starting single-phase induction motor will be described with reference to the drawings.

FIG. 2 is a circuit diagram showing a conventional split-phase starting single-phase induction motor and a starting device. In FIG. 2, 1 is a single-phase AC power supply, 2 is an overload protection device, 3 is a single-phase induction motor for phase-separated start, 4 is a rotor of the single-phase induction motor 3 for phase-separated start, 5
Is a main winding, 6 is a starting winding, 7 is a current type starting relay, 8 is a current coil winding of the current type starting relay 7, and 9 is a current contact of the current type starting relay 7.

The operation of the circuit diagram configured as described above will be described below.

First, when the single-phase AC power supply 1 shown in the circuit diagram is connected,
Current is overload protection device 2, main winding 5, current coil winding 8
Flows into the circuit. At this time, the current contact 9 of the current type starting relay 7 is changed from the open state to the closed state by the magnetic force of the current flowing through the current coil winding 8. Therefore, current flows through the overload protection device 2, the starting winding 6, and the current contact 9, and the rotor 4 is started by the magnetic field in the operation of the main winding 5 and the starting winding 6. After that, when the rotation increases, the current flowing through the main winding 5 decreases. Therefore, the current flowing through the current coil winding 8 of the current-type start relay 7 decreases, so that the magnetic force is weakened and the current contact 9 is opened, and the rotor 4 is rotated. The rotation is continued by the winding 5.

SUMMARY OF THE INVENTION However, in the above configuration, in order to generally generate a phase difference between the currents of the main winding 5 and the starting winding 6 at the time of starting, the value of the (self-reactance / resistance) of the winding is required. The cross-sectional area ratio and the turns ratio of both winding conductors must be selected so that the starting winding side is smaller than the main winding side. Generally, the starting winding 6 is reduced in cross-sectional area of the winding conductor in order to increase the resistance value for the above-described reason. However, when the cross-sectional area of the winding conductor is reduced, the current density due to the current at the time of starting increases, causing an excessive rise in temperature of the starting winding 6 and burning. For this reason, in order to increase the resistance without reducing the conductor cross-sectional area of the starting winding 6, the starting winding 6 is referred to as a backlash winding. A method of winding a wire to lengthen the entire length of the starting winding 6, which is magnetically ineffective, and a method of connecting a fixed resistor outside the starting winding 6 in series are widely known. However, backlash winding has the disadvantage of increasing the cost of the winding and increasing the number of man-hours for winding the winding in production.
The method using an external resistor is as follows.
Works, and the resistance is applied until the current contact 9 of the current type starting relay 7 is opened. Therefore, there is a disadvantage that the torque during the two-phase operation by the main winding 5 and the starting winding 6 is reduced. FIG. 3 shows another conventional example. Elements 1 to 6 in FIG. 3 are the same as the elements in FIG. Numeral 11 denotes a positive temperature coefficient thermistor, which has a small resistance at low temperatures and a sudden increase at high temperatures. The operation will be described with reference to FIG. When the single-phase AC power supply 1 is turned on, the current flows through the overload protection device 2 to the main winding 5 and the temperature of the positive temperature coefficient thermistor 11 is low. Then, the rotor 4 is started. Then the positive characteristic thermistor 11
Thermistor self-heats due to current flowing through it
11 rises, increasing its resistance. Accordingly, the current flowing through the starting winding 6 becomes very small, and the operation is substantially continuous with the main winding 5. The resistance of the positive temperature coefficient thermistor 11 when it is cold acts in the same manner as the backlash winding or the external resistance in the starting winding circuit shown in the example of FIG. However, in the starting device using the positive characteristic thermistor 11, the current flowing through the starting winding 6 after the power supply is turned on regardless of the speed of the rotor 4 of the single-phase induction motor and the acceleration state is the resistance value of the positive characteristic thermistor 11. Will decrease due to changes in Therefore, when the load at the time of starting is large, the starting winding 6 is cut without sufficiently increasing the rotation speed, so that the operation is not switched from the start to the operation. In addition, the rotational torque at the time of acceleration after the start, in which a current flows through the main winding 5 and the starting winding 6, is decreased because the resistance value of the positive temperature coefficient thermistor 11 is increased. The conventional example of FIG.
It had the above-mentioned disadvantages. Single-phase AC power supply 1
From the on state to off, and immediately afterwards to the on state again,
The positive temperature coefficient thermistor 11 has a drawback that the current cannot flow during operation and heat is generated, and the resistance is increased.

In view of the above problems, the present invention effectively limits the current flowing through the starting winding at the time of starting, while maximizing the starting torque, without reducing the acceleration torque until switching to operation,
It is an object of the present invention to provide a starting device for a split-phase starting single-phase induction motor.

Means for Solving the Problems In order to solve the above-mentioned problems, a starting device for a split-phase starting single-phase induction motor according to the present invention includes a negative-characteristic thermistor connected in series to a starting winding, and a current-type starting relay connected thereto. A current-type starting relay having an electrode coil winding of a current-type starting relay connected to a current contact and a main winding of a split-phase starting single-phase induction motor is provided.

Effect of the Invention With the configuration described above, the negative characteristic thermistor restricts the current of the starting winding at the time of starting by the above-described configuration, and does not require a balash winding or an external resistor, which is another resistance component, in order to prevent an excessive temperature rise. A current flows through the starting winding to generate a starting torque because the negative characteristic thermistor reduces the resistance value after starting. After starting, acceleration is performed in two phases. However, since the resistance of the negative characteristic thermistor is small, the overall resistance of the starting winding circuit side is also small and the maximum torque of two phases is large, so acceleration is easy and operation is easy. Switching becomes smoother.

Embodiment Hereinafter, a starting device for a split-phase starting single-phase induction motor according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a starting device for a phase-separated starting single-phase induction motor according to an embodiment of the present invention. 1 to 9 are the same as those used and described in FIG. Reference numeral 10 denotes a negative characteristic thermistor connected in series between the starting winding 6 and the current contact 9 of the current type starting relay 7.

The operation of the starting device for a split-phase starting single-phase induction motor configured as described above will be described.

When the single-phase AC power supply 1 is connected, a current flows through the circuit of the overload protection device 2, the main winding 5, and the current coil winding 8 of the current-type starting relay 7, and the current-type starting relay is operated in the same manner as in the conventional example. 7
The current contact 9 is opened to closed. Accordingly, a voltage is also applied to the negative characteristic thermistor 10, but the current does not flow because the resistance in the cold state is large. Thereafter, the resistance of the negative characteristic thermistor 10 decreases, and the current starts flowing in the circuit of the starting winding 6 to reduce the starting torque. generate. The rotor 4 increases the rotation speed. At this time, the negative characteristic thermistor 10 maintains the state where the resistance is small, and the rotation speed can be increased. When the rotation speed increases, the current flowing in the circuit on the main winding 5 side decreases.
The magnetic force of the current coil 8 of the current type starting relay 7 is weakened, the current contact 9 is opened, and the rotor 4 is connected to the main winding 5.
To continue rotation. In this state, since no current flows through the negative characteristic thermistor 10, heat is dissipated, the temperature is reduced, and the resistance value is increased again. Therefore, even if the power supply 1 is turned off from the on state and immediately turned on again, the above-described starting device functions normally.

As described above, according to the present embodiment, in a starting device for a split-phase starting single-phase induction motor, in a device having a current-type starting relay, a negative-characteristic thermistor is provided between a current contact of the current-type starting relay and a starting winding. By providing, the backlash winding of the starting winding of the split-phase starting single-phase induction motor is not required, and the transition to smooth operation without reducing the generated torque of the motor in the accelerated state after starting, Therefore, when the starting load (including the inertial load) is large, the startability can be improved, and the difficulty of restarting immediately after stopping the operation can be solved.

Effect of the Invention As described above, the present invention provides a starting device for a single-phase induction motor having a phase-separated starting in which a current-type starting relay and a negative-characteristic thermistor are connected in series between the current contact and the starting winding. The production cost and material (copper content) can be reduced without increasing the wire diameter of the starting winding of a single-phase induction motor, and starting, acceleration, and operation when the starting load is large are facilitated. In addition to the above, it is possible to solve the difficulty of restarting immediately after stopping the operation.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a single-phase induction motor and a starting device according to an embodiment of the present invention, and FIGS. 2 and 3 are circuit diagrams of a conventional split-phase starting single-phase induction motor and a starting device. 3 ... Single-phase starting single-phase induction motor, 5 ... Main winding, 6 ...
Starting winding, 7: Current type starting relay, 8: Current coil winding, 9: Current contact, 10: Negative thermistor

Claims (1)

(57) [Claims] A negative thermistor connected in series with a starting winding, a current contact connected in series with the negative winding, and a current coil winding of a current type starting relay connected in series with a main winding and intermittently connecting the contact. A starting device for a split-phase starting single-phase induction motor, comprising a current-type relay provided.