JP2758783B2 - Operation circuit of electric cargo handling machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation circuit for an electric cargo handling machine driven by an electric motor.

[0002]

2. Description of the Related Art FIG. 7 is a circuit diagram showing an example of an operation circuit of an electric cargo handling machine, which is a conventional operation circuit of an electric hoist disclosed in Japanese Patent Application Laid-Open No. 58-188298.

[0003] The DC low-voltage power supply circuit 1 includes a step-down transformer 1A.
And a diode bridge rectifier circuit 1B connected to the secondary side of the step-down transformer 1A, and a capacitor 1C connected between output terminals of the diode bridge rectifier circuit 1B. The output of the DC low voltage power supply circuit 1 is a hoist operation normally open push button contact 2A of the pendant switch,
The hoisting control circuit 3 and the hoisting control circuit 4 are connected to the hoisting operation circuit 3 via a normally open push button contact 2B. The hoisting control circuit 3 and the hoisting control circuit 4 respectively control the hoisting operation and the hoisting operation of the electric motor (not shown) of the electric hoist. The output terminals of the normally open push button contact 2A and the normally open push button contact 2B are connected to a current limiting resistor 7 and a capacitor 8 via diodes 5 and 6, respectively. The discharge resistor 9 is connected to the capacitor 8 in parallel.

Next, the operation of the circuit shown in FIG. 7 will be described.
When the hoisting operation normally open push button contact 2A is turned on, the output of the DC low voltage power supply circuit 1 is input to the hoisting control circuit 3 via the hoisting operation normally open push button contact 2A, and the hoisting control circuit 3 (Not shown). Here, when the hoisting operation normally open push button contact 2A is turned off, the hoisting control circuit 3 stops the hoisting operation. On the other hand, lowering operation normally open push button contact 2B
Is turned on, the output of the DC low-voltage power supply circuit 1 is input to the lowering control circuit 4 via the lowering operation normally open push button contact 2B, and the lowering control circuit 4 performs the lowering operation of the motor. When the normally open push button contact 2B is turned off, the lowering control circuit 4
Stops the lowering operation.

[0005] By the way, the hoisting operation normally open push button contact 2A,
When an insulating film is formed on the surface of the contact of the normally open push button contact 2B, the DC low voltage power supply circuit 1 is turned on even if the normally open push button contact 2A and the normally open push button contact 2B are turned on.
May not be supplied to the hoist control circuit 3 and the hoist control circuit 4 and may become inoperable. The insulating film formed on the normally open push button contact 2A and the normally open push button contact 2B is removed as follows.

For example, a case where the hoisting operation normally open push button contact 2A is turned on will be described. The capacitor 1C connected to the output terminal of the diode bridge rectifier circuit 1B is always charged when the hoisting operation normally open push button contact 2A and the winding operation normally open push button contact 2B are off. When the hoisting operation normally-open push button contact 2A is turned on, the capacitor 1C is mainly connected via the diode 5 and the current limiting resistor 7.
And the capacitor 8 is charged. Therefore, a rush current having a larger value than the current flowing through the hoisting control circuit 3 flows to the hoisting operation normally open push button contact 2A, and the contact portion of the hoisting operation normally open push button contact 2A causes chattering. As a result, the insulating coating on the contact surface of the normally open push button contact 2A for the winding operation is broken, and the output of the DC low-voltage power supply circuit 1 is reliably supplied to the winding control circuit 3.

On the other hand, when the lowering operation normally-open push button contact 2B is turned on, the capacitor 8 is charged via the diode 6 and the current limiting resistor 7, and the inrush current is larger than that supplied to the lowering control circuit 4. Is the normally open push button contact 2B for lowering operation
Flows through. As a result, the insulating film on the contact surface of the normally open push button contact 2B in the lowering operation is broken. When the hoisting operation normally open push button contact 2A and the hoisting operation normally open push button contact 2B are turned off, the capacitor 8 is discharged via the discharge resistor 9.

[0008]

Since the operation circuit of the conventional electric cargo handling machine is constructed as described above, a step-down transformer, a capacitor, a resistor and the like are used to destroy the oxide film on the contact surface of the push button. Requires a complicated circuit including: If the oxide film of the push button contact is not completely destroyed, contact failure occurs and operation becomes impossible. Further, since the signal generated by the operation circuit can be identified only in the on / off two state, the control circuit cannot detect the occurrence of the abnormality, and there is a danger that the electric cargo handling machine will run away.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can reliably input an operation signal, and is generated due to an operation signal generated by operating a push button and a failure. An object of the present invention is to obtain a highly reliable operation circuit of an electric cargo handling machine capable of identifying an abnormal signal.

[0010]

According to a first aspect of the present invention, an operation circuit for an electric cargo handling machine is connected to an AC power supply and generates a rectified output that fluctuates at the AC power supply frequency or a frequency that is an integral multiple of the AC power supply frequency. Switch contact means for turning on / off the output of the rectifying means; first converting means for converting the output of the rectifying means into an optical signal which blinks intermittently; and an optical signal generated by the first converting means. And a second converting means for converting into an intermittent electric signal.

The operation circuit for an electric cargo handling machine according to a second aspect of the present invention is connected to an AC power supply and rectifies the AC current to generate a rectified output that fluctuates at the AC power supply frequency or a frequency that is an integral multiple of the AC power supply frequency. Means, and first conversion means for converting an output of the rectification means into an optical signal that blinks intermittently;
A second converter for converting an optical signal generated by the first converter into an electric signal; and a light inserted between the first converter and the second converter for selectively generating light generated by the first converter. Selective light blocking means for blocking.

[0012]

In the operation circuit according to the first aspect of the present invention, the electric signal is converted into an optical signal by the first and second conversion means, and further the optical signal is converted into an electric signal and inputted to the control circuit. The switch contact means is directly connected to an AC power supply without passing through a transformer. Therefore, there is no need for a special circuit for removing the insulating film formed on the contact, the circuit configuration is simplified,
Further, even if the contact resistance value of the switch contact is large, the input to the control circuit can be reliably turned on / off. Further, since the input to the control circuit of the electric cargo handling machine is an intermittent signal, it is possible to discriminate between a signal caused by operating the switch contact and an abnormal signal caused by a failure or the like.

In the operation circuit according to a second aspect of the present invention, the first and second conversion means convert an electric signal into an optical signal, further convert the optical signal into an electric signal, and input the converted signal to a control circuit. The ON / OFF of the instruction signal is performed by a selective light blocking unit. Therefore, a special circuit for removing the insulating film formed on the contacts is not required, the circuit configuration is simplified, and no malfunction occurs due to the contact resistance of the switch contacts. Since the input to the control circuit of the electric cargo handling machine is an intermittent signal, it is possible to distinguish between a normal signal and an abnormal signal.

[0014]

FIG. 1 is a circuit diagram of an operation circuit of an electric cargo handling machine according to a first embodiment of the present invention. The figure shows, for example, a hoisting operation circuit of an electric hoist as an operation circuit of the electric cargo handling machine. In this case, the operation circuit of the hoisting operation of the electric hoist is also configured in the same manner as in FIG. The control circuit 16 in FIG. 1 corresponds to the hoist control circuit 3 of the operation circuit in FIG. 7 described above.

In FIG. 1, a series circuit including a normally open push button contact 10, a resistor 11, and a diode bridge rectifier circuit 12 is connected in series between AC power supplies R and S,
The shunt resistor 13 is connected in parallel with the input side of the diode bridge rectifier circuit 12. The normally-open push-button contact 10 is, for example, a contact of a hoisting operation push-button instructing a hoisting operation. The diode bridge rectifier circuit 12 is a diode 1
This is a full-wave rectifier circuit composed of 2A, 12B, 12C, and 12D.

The photocoupler 14 connected to the output side of the diode bridge rectifier circuit 12 has a light emitting diode 14A.
And a phototransistor 14B. The light emitting diode 14A is connected between the output terminals of the diode bridge rectifier circuit 12, and the collector of the phototransistor 14B is connected to a positive voltage source (+ 5V) via the resistor 15;
The emitter is grounded. The collector of the phototransistor 14B is further connected to the control circuit 16, and inputs an operation signal to the control circuit 16. The control circuit 16 controls the hoisting operation of the electric motor of the electric hoist in response to the operation signal input from the phototransistor 14B.

Next, the operation of the operation circuit of FIG. 1 will be described. When the normally open push button contact 10 is turned on, the AC voltage supplied from the AC power supplies R and S is full-wave rectified by the diode bridge rectifier circuit 12 and supplied to the light emitting diode 14A. Therefore, when the R-phase side of the power supply is positive, the normally open push button contact 10, the diode 12A, the light emitting diode 1
A current flows to the S-phase side via 4A and the diode 12C. On the other hand, when the S phase is positive, the normally open push button contact 1
0, a current flows to the R-phase side via the diode 12B, the light emitting diode 14A, and the diode 12D.

Therefore, the diode bridge rectifier circuit 12
The voltage supplied to the light emitting diode 14A after full-wave rectification has a waveform that fluctuates at twice the power supply frequency, as shown in FIG. 2, and the light emitting diode 14A emits light intermittently. The phototransistor 14B that has received the intermittent light repeatedly turns on and off at a frequency twice the power supply frequency, and supplies the control circuit 16 with an intermittent signal that repeats a low level and a high level at a frequency twice the power supply.

That is, when the phototransistor 14B receives light from the light emitting diode 14A and conducts, the collector voltage of the phototransistor 14B becomes the ground voltage 0V, the light emission of the light emitting diode 14A stops, and the phototransistor 1
When 4B is turned off, the collector voltage of phototransistor 14B becomes the positive power supply voltage + 5V. Therefore, the control circuit 16 is supplied with an intermittent signal that repeats a low level and a high level at a frequency twice the power supply frequency.

The shunt resistor 13 is a normally open push button contact 10.
Has an effect of removing a noise signal generated in a state where is turned off. This will be described below. The wiring connecting the normally-open pushbutton contact 10 and the resistor 11 runs in parallel with the wiring for other pushbuttons or the R-phase power supply wiring. Therefore, the input terminal of the diode bridge rectifier circuit 12 even if the normally open push button contact 10 is not turned on due to stray capacitance existing between the wiring connecting the normally open push button contact 10 and the resistor 11 and other wiring. A voltage may be induced between the terminals of the shunt resistor 13 and between the terminals. However, the resistance value of the shunt resistor 13 is set smaller than the resistance value of the series circuit including the diode 12A, the light emitting diode 14A, and the diode 12C or the resistance value of the series circuit including the diode 12B, the light emitting diode 14A, and the diode 12D. . As a result, the induced voltage between the input terminals of the diode bridge rectifier circuit 12 is suppressed to a low level by the shunt current flowing through the shunt resistor 13, and the light emitting diode 14A hardly emits light. Therefore, a noise signal generated when the normally open push button contact 10 is turned off by the induced voltage is generated by the control circuit 16.
Input is prevented.

The control circuit 16 of FIG. 1 can also discriminate a normal instruction signal from an abnormal signal generated as a result of a failure. This will be described below.

Normally open push button contact 1 in normal operating state
If the push button 0 is not pressed, the light emitting diode 1
4A does not emit light, and the phototransistor 14B is off. Therefore, a positive voltage (+5 V) is input to the control circuit 16. When the normally open push button contact 10 is turned on by pressing the push button, as described above, the control circuit 1
6 is supplied with an intermittent signal having a frequency twice the power supply frequency.

However, when the phototransistor 14B is turned on and fails, for example, a low-level signal (ground voltage 0 V) is continuously input to the control circuit 16. Therefore, when a low level signal is input for a predetermined time or more, the control circuit 16 determines that an abnormality has occurred, stops the operation, and notifies the abnormality by an alarm lamp (not shown) or the like.

FIG. 3 is a circuit diagram of an operation circuit of the electric cargo handling machine according to the second invention of the present invention. This figure also shows only a hoisting operation circuit of the electric hoist, for example, as an operation circuit of the electric cargo handling machine.

In FIG. 3, a diode bridge rectifier circuit 12 is connected to power supplies R and S via a transformer 20. In addition, instead of the normally open push button contact 10, a selective light shutoff push button 2 is provided.
1 is provided. The light blocking extension 21A of the selective light blocking push button 21 has a through hole 21B, and allows light from the light emitting diode 22 to the phototransistor 23 to pass when the selective light blocking push button 21 is pressed. Other configurations are the same as those of the embodiment of FIG.

Next, the operation of the operation circuit shown in FIG. 3 will be described. The AC voltages of the power supplies R and S stepped down by the transformer 20 are supplied to the diode bridge rectifier circuit 12 via the resistor 11 and full-wave rectified. Accordingly, the output of the diode bridge rectifier circuit 12 has the waveform shown in FIG. As a result, the light emitting diode 22
Emits light intermittently at twice the frequency of the power supply.

When the selective light blocking push button 21 is not pressed, light generated by the light emitting diode 22 is blocked by the light blocking extension 21A of the selective light blocking push button 21 and reaches the phototransistor 23. do not do. Therefore,
The phototransistor 23 is off and the control circuit 16
, A positive voltage (+5 V) is continuously input. When the selective light blocking push button 21 is pressed here, the light blocking extension 21
A falls, and the intermittent blinking light generated by the light emitting diode 22 reaches the phototransistor 23 through the through hole 21B. As a result, the phototransistor 23 is turned on intermittently, and supplies the control circuit 16 with an intermittent signal that repeats a low level and a high level at a frequency twice the power supply frequency. This is the same as in the embodiment of FIG.

FIG. 4 is a circuit diagram of an operation circuit of an electric cargo handling machine according to a second embodiment of the first invention of the present invention. The operation circuit of FIG. 4 is configured similarly to the operation circuit of FIG. 1 except for the following points.

That is, the upper limit switch 24 is inserted between the power supply terminal S and the resistor 11 to limit the upper limit of the current. The normally open push button contact 10 is connected in series with the diode 12D of the diode bridge rectifier circuit 12. The rest is configured similarly to the operation circuit of FIG.

Next, the operation of the operation circuit of FIG. 4 will be described. Push button not pressed, normally open push button contact 10
Is off, the diode 12D is disconnected from the diode bridge rectifier circuit 12, and the diode bridge rectifier circuit 12 forms a half-wave rectifier circuit. Therefore, current flows through the diode 12A, the light emitting diode 14A, and the diode 12C only when the R phase is positive,
As shown in FIG. 5, the diode bridge rectifier circuit 12 generates a half-wave rectified output that fluctuates at the same frequency as the power supply.

As a result, the light emitting diode 14A emits light intermittently at the same frequency as the power supply frequency, and the phototransistor 14B sends to the control circuit 16 an intermittent signal that repeats a low level and a high level at the same frequency as the power supply frequency. Supply.

Here, when the normally open push button contact 10 is pressed, the diode 12D is connected to the diode bridge rectifier circuit 12, and the diode bridge rectifier circuit 12 constitutes a full-wave rectifier circuit. As a result, the same state as when the normally open push button contact 10 is pressed in the circuit of FIG. 1 is obtained, and the full-wave rectified output having the waveform shown in FIG. 2 is supplied to the light emitting diode 14A.

Accordingly, the light emitting diode 14A emits light intermittently at twice the frequency of the power supply, and the phototransistor 14B also supplies the control circuit 16 with an intermittent signal that repeats a low level and a high level at a frequency twice the power supply frequency. .

Thus, the normally open push button contact 10 is turned on and off.
The frequency of the input signal to the control circuit 16 changes depending on the off state. Therefore, the control circuit 16 detects the on / off state of the normally open push button contact 10 from the frequency of the input signal.

On the other hand, when the hook reaches the upper limit and the upper limit switch 24 is opened as a result of the hoisting operation, the S-phase power is completely cut off, and no current is supplied to the light emitting diode 14A. Therefore, the light emitting diode 14A does not emit light,
Phototransistor 14B is continuously turned off. Therefore, a positive voltage (+5 V) is continuously input to the control circuit 16. Thus, the control circuit 16 detects that the hook has reached the upper limit.

FIG. 6 is a circuit diagram of an operation circuit of an electric cargo handling machine according to a third embodiment of the first invention of the present invention. For example, in the case of an electric hoist, the operation circuit shown in FIG. 6 can distinguish the three members of the high-speed hoisting operation, the low-speed hoisting operation and the high-speed hoisting operation from each other only by this circuit. The configuration is the same as that of the operation circuit of FIG.

That is, one of the lowering operation two-stage push-buttons 25
The normally open push button contact 25A is connected in series with the diode 12D (instead of the normally open push button contact 10 in FIG. 4). Further, a second-stage normally-open push-button contact 25B of the lowering operation two-stage push-button 25 is inserted between the power R phase and the input terminal of the diode bridge rectifier circuit 12 (the positive terminal of the diode 12A). In addition, two-step push-in button 2 for hoisting operation
The second-stage normally-open contact 26 is connected in parallel with the second-stage normally-open push-button contact 25B. The rest is the same as the configuration of the operation circuit in FIG.

Next, the operation of the operation circuit shown in FIG. 6 will be described. When the lowering operation second-stage push-button 25 is pressed to the first stage, the first-stage normally-open push-button contact 25A is closed. In this state, the second-stage normally-open push-button contact 25B and the hoisting-operation second-stage push-button second-stage normally-open contact 26 are open, and only when the S-phase side is positive, the diode 12B, the light-emitting diode 14A,
A current flows through the diode 12D and the first-stage normally-open push-button contact 25A. As a result, the half-wave rectified current having the waveform shown in FIG. 5 is supplied to the light emitting diode 14A, and the light emitting diode 14A emits light intermittently at the same frequency as the power supply. Therefore, the phototransistor 14B supplies the control circuit 16 with an intermittent signal that repeats a low level and a high level at the same frequency as the power supply. In response to this, the control circuit 16 detects that an instruction for low speed operation under winding has been given.

Here, the lowering operation two-stage push button 25 is set to 2
When the switch is pushed to the first stage, the first-stage normally-open push-button contact 25B is closed together with the first-stage normally-open push-button contact 25A, and the diode bridge rectifier circuit 12 constitutes a full-wave rectifier circuit. As a result, the full-wave rectified current having the waveform shown in FIG. 2 is supplied to the light emitting diode 14A in the same manner as when the normally open push button contact 10 is pressed in FIG. Therefore, the control circuit 16 is supplied with an intermittent signal that repeats a low level and a high level at twice the frequency of the power supply. In response to this, the control circuit 16 detects that an instruction for high speed operation under winding is given.

On the other hand, in the case of the hoisting operation, a hoisting instruction signal is input to the control circuit 16 from an operation circuit having a configuration similar to that shown in FIG. 4, for example. Control circuit 1 of FIG.
Reference numeral 6 denotes a hoisting operation and a hoisting operation, and the operation circuit of FIG. 4 having a configuration excluding the control circuit 16 is connected to the control circuit 16 of FIG. 6 as an operation circuit for instructing the hoisting operation. The normally-open push-button contact 10 in FIG. 4 constitutes the first-stage normally-open push-button contact of the hoisting operation two-stage push-button. Note that the hoisting operation two-stage push-button is mechanically interlocked with the hoisting operation two-stage push-button 25 and cannot be pressed at the same time.

When the hoisting operation two-stage push-button is pushed to the second stage, the hoisting operation two-stage push-button is in the second stage normally open contact 2
6 closes. At this time, the first-stage normally-open push button contact 25A and the second-stage normally-open push button contact 25B are open, and the winding operation is performed only when the R-phase side of the power supply is positive. , Diode 12A, light emitting diode 14
A, a current flows to the S-phase side via the diode 12C.
Therefore, the half-wave rectified current having the waveform shown in FIG. 5 is supplied to the light emitting diode 14A, and the light emitting diode 14A emits light intermittently at the same frequency as the power supply. Therefore, the phototransistor 14B supplies a signal having the same frequency as that of the power supply to the control circuit 16. As described above, the control circuit 16 receives the hoisting operation instruction signal from the hoisting operation operating circuit having the configuration shown in FIG. Has been entered. In this state, when a signal having the same frequency as the power supply frequency is further input from the phototransistor 14B in FIG. 6, the control circuit 16 responds to this and detects that there is an instruction for high-speed winding operation.

[0042]

In the operating circuit according to the first aspect of the present invention, the first and second conversion means convert an electric signal into an optical signal, further convert the optical signal into an electric signal, and input the converted signal to a control circuit. I have. Therefore, the switch contact means and the rectifying means can be directly connected to the AC power supply without using a transformer. This eliminates the need for a special circuit to remove the insulation film generated at the contacts, simplifies the circuit configuration, and reliably turns on / off the input signal to the control circuit even if the contact resistance of the switch contacts is large. it can.

Since the input to the control circuit of the electric cargo handling machine is an intermittent signal, it is possible to distinguish between a normal signal and an abnormal signal.

In the operation circuit according to the second invention of the present invention, the electric signal is converted into an optical signal by the first and second conversion means, and further the optical signal is converted into an electric signal and inputted to the control circuit. The turning on and off of the signal is performed by a selective light blocking means.

Therefore, a transformer and a switch contact are not required, the circuit configuration is simplified, and no malfunction occurs due to the contact resistance of the switch contact. Since the input to the control circuit of the electric cargo handling machine is an intermittent signal, it is possible to distinguish between a normal signal and an abnormal signal.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an operation circuit of an electric cargo handling machine according to a first embodiment of the first invention of the present invention.

FIG. 2 is a diagram showing a full-wave rectified waveform of the operation circuit according to the present invention.

FIG. 3 is a circuit diagram of an operation circuit of the electric cargo handling machine according to a second invention of the present invention.

FIG. 4 is a circuit diagram of an operation circuit of the electric cargo handling machine according to a second embodiment of the first invention of the present invention.

FIG. 5 is a diagram showing a half-wave rectified waveform of the operation circuit according to the present invention.

FIG. 6 is a circuit diagram of an operation circuit of the electric cargo handling machine according to a third embodiment of the first invention of the present invention.

FIG. 7 is a circuit diagram of a conventional electric hoisting machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC low voltage power supply circuit 1A Step-down transformer 1B Diode bridge rectifier circuit 1C Capacitor 2A Hoisting operation normally open push button contact 2B Unwinding operation normally open push button contact 3 Hoisting control circuit 4 Unwinding control circuit 5 Diode 6 Diode 7 Current limiting resistor 8 Capacitor 9 Discharge resistor 10 Normally open push button contact 11 Resistor 12 Diode bridge rectifier circuit 12A Diode 12B Diode 12C Diode 12D Diode 13 Shunt resistor 14 Photocoupler 14A Light emitting diode 14B Phototransistor 15 Resistor 16 Control circuit 20 Transformer DESCRIPTION OF SYMBOLS 21 Selective light-blocking push button 21A Light-blocking extension 21B Through-hole 22 Light-emitting diode 23 Phototransistor 24 Upper limit switch 25 Lowering operation two-stage push-button 25A First-stage normally-open push-button contact 25B 2nd stage normally open push button contact 26 Hoisting operation 2nd stage push button 2nd stage normally open contact

Claims (2)

(57) [Claims] An operation circuit for inputting an operation signal of an electric cargo handling machine to a control circuit of the electric cargo handling machine, wherein the operation circuit is connected to an AC power supply and generates a rectified output that fluctuates at the AC power supply frequency or a frequency that is an integral multiple of the frequency. Rectifying means; switch contact means for turning on / off the output of the rectifying means; first converting means for converting the output of the rectifying means into an optical signal which blinks intermittently; and light generated by the first converting means. And a second converting means for converting the signal into an intermittent electric signal. 2. An operation circuit for inputting an operation signal of an electric cargo handling machine to a control circuit of the electric cargo handling machine, wherein the operation circuit is connected to an AC power supply, rectifies the AC current, and fluctuates at the AC power supply frequency or an integral multiple thereof. Rectifying means for generating a rectified output, a first converting means for converting an output of the rectifying means into an optical signal blinking intermittently, and a second converting means for converting the optical signal generated by the first converting means into an electric signal. An operation circuit for an electric cargo handling machine, comprising: a conversion unit; and a selective light blocking unit inserted between the first conversion unit and the second conversion unit to selectively block light generated by the first conversion unit.