JPS5880701A - Interlocking circuit - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a mobile mechanism, by using an interlocking circuit which works in response to the polarity of the command signal and then driving a DC motor with the output of the interlocking circuit to stop the working of the DC motor with an abnormal function like a malfunction of a control circuit, etc. CONSTITUTION:An interlocking circuit 10 is provided between a control circuit 1 and a DC motor driving circuit 3 which drives a mobile mechanism 7. In addition to the command signal VIN given from the circuit 1, the positive and negative interlocking signals PI and NI given from interlocking detection switches 8 and 9 respectively are applied to the circuit 10. The switching circuits 11 and 12 are controlled by the signals PI and NI respectively, and the signal VIN is applied to a positive voltage rectifier 13 and a negative voltage rectifier 14. Both positive and negative direction signals are extracted out of the signal VIN and added together by an adder 15. Then the driving command signal VOUT is delivered. Thus the working of a DC motor 5 is stopped assuredly with an abnormal function such as a malfunction, a trouble, etc. of the circuit 10. Thus the breakdown of the mobile mechanism 7 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interlock circuit in a system that controls a direct current circuit including a direct current motor by analog command signals from a control circuit such as a computer. Conventionally, as shown in FIG. 1, a digital signal from a control circuit 1 such as a computer is converted into an analog signal by a digital/analog converter 2 to obtain an analog command signal, and this signal is sent to a DC motor drive circuit 3. is applied to the power amplifier 4, where it is applied to the DC motor 5.
It is known to drive the moving mechanism 7 by calculating the difference between the output of the tacho generator 6 which measures the rotational speed of the motor and applying the difference to the DC motor 5.

In such a system, runaway of the DC motor 5 is detected by positive direction and negative direction interlock detection switches 8 and 9 provided at both ends of the moving mechanism 7, and based on this detection signal, the control circuit 1 and the system are Digital/analog converter 2
The servo command signal given to the motor is turned off.

In this case, the runaway phenomenon of the DC motor 5 is often caused by a malfunction of the control circuit 1 itself or a failure of the digital/analog converter 2, and the interlock (
(Emergency stop) function may not operate normally, and as a result, the moving mechanism 7 may be damaged.

An object of the present invention is to provide an interlock circuit that reliably works the interlock function and prevents damage to the moving mechanism.

To achieve this objective, the present invention complies with Directive 18
A positive half-wave rectifier takes out the positive signal of the command signal, a negative half-wave rectifier takes out the negative signal of the command signal, an adder adds the output signals of these rectifiers, and an interlock signal is input. When not, the output signal of the exchanger is obtained from the adder, and when a positive interlock signal is given, the output signal of the positive half-wave rectifier is cut off, and a negative interlock signal is given. In this case, a feature is that an interlock circuit including a switch circuit that cuts off the output signal of the negative half-wave rectifier is provided, and the DC motor is driven by the output of this interlock circuit.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an example of an interlock circuit TTR control system according to the present invention, in which an interlock circuit 10 is provided between the control circuit 1 and the DC motor drive circuit 5.

In addition to the command signal V□ from the control circuit 1, positive and negative interlock signals PI and NI from the interlock detection switches 8 and 9 are input to the interlock circuit 10, and the drive command signal vo ■It is designed to output.

FIG. 6 shows an example of a specific configuration of the interlock circuit 10, in which 11 is a switch circuit that responds to a positive direction interlock signal PI, 12 is a switch circuit that responds to a negative direction interlock signal NI, and 13 is a positive direction interlock signal NI. A positive voltage rectifier 14 outputs a negative voltage whose sign is inverted with respect to the voltage input, and outputs Ov in response to the negative voltage input. 15 is a negative voltage rectifier that outputs Ov; 15 is an adder that adds the outputs of rectifiers 13 and 14 to generate a sign-inverted output; 16
and 17 indicate an inverter. In addition, the rectifiers 13 and 14 include resistors R7, R2, Rs and a diode D, respectively.
, , D2 and amplifier A1, adder 15 is composed of resistors R1 to R7 and amplifier A2, and switch circuits 11 and 12 are composed of switches SW1 and SW2, respectively.

In such a configuration, the interlock detection switch 8
and 9 remain open and the interlock signals PI and NI are not input, the switches SW1 of the switch circuits 11 and 12 are closed by the action of the inverters 16 and 17, so the command signal VO is It is directly input to the rectifiers 16 and 14. therefore,
The rectified outputs of the positive voltage and negative voltage of the command signal VIN are input to the adder 15, and the adder 15 adds them. This addition output is input to the DC motor drive circuit 3.

Now, when the interlock detection switch 8 is closed and the positive direction interlock signal PI is input, the switch circuit 1
1 switch S, W 2 is closed, while switch S
Since W1 is opened and the signal input to the positive voltage rectifier 13 is cut off, only the negative voltage signal of the negative voltage rectifier 14 is output from the adder 15 as the drive command signal VQUT.

Conversely, when the interlock detection switch 9 is closed and the interlock signal NI is input, the signal input to the negative voltage rectifier 14 is cut off, so that only the positive voltage signal is input to the adder 1.
5 as the drive command signal VOUT.

Figure 4 shows the waveforms of each part in Figure 3 under the condition that no interlock signals in the positive and negative directions are input.
a) is the command signal VIN of the control circuit 1, (b) is the output VA of the positive voltage rectifier 13, (Q) is the output VB of the negative voltage rectifier 14, and (a) is the drive command signal from the adder 15.
It is OUT.

When the positive direction interlock signal PI is input, the signal of only the negative voltage part shown in FIG. 4(d) is output from the adder 15, and when the negative direction interlock signal Nl is input, the signal of FIG. The signal of only the positive voltage portion in (d) is output from the adder 15.

In this way, when the interlock detection switches 8 and 9 do not work, normal motor driving is possible, but due to runaway of the DC motor 5, the moving mechanism 7 closes the interlock detection switch 8 and the following situation occurs. In this case, the forward drive signal input to the DC motor drive circuit 3 is cut off, and the forward drive of the DC motor 5 is stopped. However, the negative direction drive command signal remains unchanged, and the moving mechanism 7 can be easily returned to the angular direction by the command signal from the control circuit 1. Further, if the moving mechanism 7 closes the interlock detection switch 9 due to runaway of the DC motor 5, the driving of the moving mechanism 7 in the negative direction is stopped, but the driving in the positive direction is stopped. Eating behavior is now possible.

In the circuit shown in FIG. 3, depending on the setting of the resistance constants of the resistors R7 to R7, the output voltage vo with respect to the input voltage "IN"
It is possible to amplify or attenuate ot. For example, if R, = R6, My and "IN R."

If R,=R3, then in the embodiment described above, the switch circuits 11 and 12 are connected to the rectifier 13.
Although the rectifiers 15 and 14 are provided on the input side, they may be provided on the output sides of the rectifiers 15 and 14.

As described above, according to the present invention, the DC motor can be reliably stopped in the event of an abnormal operation such as malfunction or failure of the control circuit, and the moving mechanism will not be damaged.

Further, at this time, the return drive of the DC motor can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional control system, FIG. 2 is a configuration diagram of an embodiment of a control system including an interlock circuit according to the present invention, and FIG. 3 is a specific configuration diagram of an interlock circuit according to the present invention. FIG. 4, a block diagram of the embodiment, is a diagram showing waveforms of various parts of the interlock circuit of FIG. 5. 10... Interlock circuit, 11.12... Switch circuit, 13... Positive voltage rectifier, 14... Negative voltage rectifier, 15... Adder. Representative Patent Attorney Yuki Hibetsu

Claims (1)

[Claims] A first rectifier for extracting a positive direction signal of the command signal, a second rectifier for extracting a negative direction signal of the command signal, and an output signal of the first and second rectifiers. When an adder to add and a positive interlock signal are given,
switch means for cutting off the output signal of the first rectifier and cutting off the output signal of the second rectifier when a negative direction interlock signal is applied; An interlock circuit characterized by controlling a DC servo circuit.