JPS6158400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an electromagnetic brake used in a hoisting machine such as an electric hoist.

[Conventional technology]

Figures 2 and 3 are, for example, from Japanese Patent Application Laid-Open No. 54-157959.
This is a conventional device disclosed in the above publication, and in FIG. 3, when the push button switch PB-U or PB-D is pressed, the hoisting control coil UC or the hoisting control coil
DC is excited, and the hoisting contactor U-1 or the hoisting contactor D-1 shown in FIG. 2 is turned on. On the other hand, the winding contact U-1C or the winding down contact D-1C of the control coil UC or DC is closed, the control coil BrsC for the quick-cut switch Brs is energized, and the quick-cut switch Brs is closed. be done. Therefore, the DC electromagnetic brake coil BRC is energized via the full-wave rectifier Re, and the brake (not shown) is energized.
At the same time as the motor M is opened, three-phase alternating current is applied to the motor M, and the winding or lowering operation is performed.

By the way, when stopping the operation, by opening the push button switch PB-C or PB-D,
When the control coil UC or DC is deenergized, the control coil BrsC is deenergized, and at the same time as the energization to the electric motor M is stopped, the quick cut switch Brs is opened,
The DC electromagnetic brake coil BRC is deenergized and the brake begins its control action in a known manner. In other words, since the DC brake coil has an inductance L, even if the motor current disappears, the brake coil current remains for a time determined by the time constant of L/R, which delays the braking of the electromagnetic brake and prevents the suspended load from falling freely. However, the quick cut switch Brs immediately energizes the DC electromagnetic brake coil BRC, so the brake is immediately applied and the suspended load is prevented from falling freely.

[Problem that the invention seeks to solve]

In the above configuration, the DC electromagnetic brake coil BRC is placed on the motor M side, and the quick-cut switch control coil BrsC, quick-cut switch Brs, and full-wave rectifier Re are placed in a control box (not shown). This increases the number of wiring between the motor M side and the control box side, which not only makes the wiring work troublesome, but also requires a control coil with a large capacity because the quick-cut switch Brs turns on and off a large current.
BrsC must be used, making the whole thing expensive. Furthermore, in reality, the quick-cut switches Brs would be connected in parallel to open and close large currents, as shown in Figure 4, which would require wiring work. An even more troublesome problem arose.

This invention was made to solve this problem, and it becomes possible to arrange the brake control circuit as an independent circuit on the motor side, eliminating the need for signals for the brake control circuit, and furthermore, making the control circuit itself inexpensive. The present invention provides an electromagnetic brake control device for a hoisting machine that can be configured as follows.

[Means for solving problems]

The electromagnetic brake control device for a hoisting machine according to the present invention includes a first full-wave rectifier whose AC side is connected to one phase of a three-phase hoisting motor; an electromagnetic brake coil, a reverse diode connected in parallel to the DC electromagnetic brake coil, a transistor connected in series to the DC electromagnetic brake coil to open and close the DC side circuit of the first full-wave rectifier, and the three-phase winding coil. A current transformer that transforms the current of other phases of the motor, an AC side connected to the output side of this current transformer, and a second full-wave rectifier that supplies DC current to the base of the transistor. .

[Effect]

In the electromagnetic brake control device for a hoisting machine according to the present invention, the phase current of the three-phase hoisting motor is transformed and supplied to the base of the transistor connected in series to the DC electromagnetic brake coil. The current is supplied in an amount equal to or less than the main current of the transistor, and the brake control circuit can be placed together on the motor side.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a hoisting motor, 2 is a diode bridge, and 3 is a DC electromagnetic brake coil, which is connected to the output terminals P and N of the diode bridge 2 via a quick-cut transistor 4. . Reference numeral 5 denotes a freewheeling circuit consisting of a limiting resistor 6 and a freewheeling diode 7, and 3 a current transformer which supplies a base current to the base of the early cut transistor 4 via a diode bridge 9, a capacitor 10, and a resistor 11. It is connected to the.

Next, the operation will be explained.

When voltages are applied to U, V, and W, the early cut transistor is in an off state, so the starting current of the motor flows to the U phase and W phase. The V-phase current is reduced by the current transformation ratio by the current transformer 8, rectified by the diode bridge 9, and supplied to the base of the quick-cut transistor 4.

Then, the collector-emitter of the transistor is turned on, the electromagnetic brake coil 3 and the hoisting motor 1 are both excited, the brake is released, and the motor rotates.

At this time, the starting current of the motor flows through the collector emitter current of transistor 4, and the rated current is 5 to 5.
Although it is six times as large, the base current is also larger by that proportion, and the transistor operates normally without running out of base current.

When the power to U, V, and W is turned off, the current in each becomes zero, the base current of the transistor also disappears, and the collector-emitter of the transistor is also turned off, and the brake coil current rapidly flows through the limiting resistor 6 and current diode 7. decreases to

Then, the electromagnetic brake will apply the brakes without any time delay, and the electric motor will stop immediately. That is, there is no free fall of the load.

〔Effect of the invention〕

As described above, the present invention connects a transistor in series to a DC electromagnetic brake connected to the DC side of a first full-wave rectifier, and converts the current of one phase of a three-phase hoisting motor into alternating current using a current transformer. Since the output was rectified by the second full-wave rectifier and energized to the base of the above transistor, the brake control circuit part was
It can be completely separated and independent from the control circuit for hoisting and lowering of the motor, eliminating the need for control signal lines between the hoisting and lowering control circuit and the brake control circuit, which not only simplifies wiring work but also , there is no need for a large capacity and expensive control coil for the quick-cut switch, and there is no need to connect the quick-cut switches in parallel as shown in Figure 3. This has the effect of significantly reducing not only the price but also the work cost for configuring the circuit.

Furthermore, the base current changes according to the current in the main circuit of the motor, and the base current of the transistor is automatically supplied with the base current necessary for the main current of the transistor, reducing power consumption. Not only does this reduce the base loss, it can support the maximum current of the transistor's specification limit, which has the effect of realizing an economical design.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram of a conventional device, and Fig. 3 is a winding diagram thereof.
FIG. 4 is a partial circuit diagram of the lowering control section. In the figure, 1 is a hoisting motor, 2 and 9 are diode bridges, 3 is an electromagnetic brake coil, 4 is a transistor, and 8 is a current transformer. Note that the same parts in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A first full-wave rectifier whose AC side is connected to one phase of the three-phase hoisting motor, a DC electromagnetic brake coil connected to the DC side of this first full-wave rectifier, and a DC electromagnetic brake coil connected in parallel to this DC electromagnetic brake coil. a transistor connected in series to the DC electromagnetic brake coil to open and close the DC side circuit of the first full-wave rectifier; and a current transformer to transform the current of the other phase of the three-phase hoist motor. an electromagnetic brake control device for a hoisting machine, comprising: a second full-wave rectifier having an alternating current side connected to the output side of the current transformer and passing a direct current to the base of the transistor;