JPS60261388A - Overload detector - Google Patents

Abstract

PURPOSE:To interrupt the supply of an abnormal current to a rotary motor with a simple construction by interrupting a current when a control signal becomes out of the range of a reference signal. CONSTITUTION:A window comparator 10 judges whether a control signal to a servo motor falls within the output range set by variable resistors VR1-VR3 or not, and outputs a signal to a processor 15 when becomes out of the output range. A processor 15 energizes a coil 20 when the signal is input from the comparator 10 to open a normally-open contact 28 to stop supplying a control signal to a servo motor. Thus, the supply of an abnormal current to a rotary motor can be interrupted with a simple construction, and the set value of the comparator to the control signal can be arbitrarily altered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overload detection device, and more specifically, when an overload is applied to a rotating electric motor, particularly a motor, the present invention quickly and reliably detects an increasing abnormal current and shuts it off. The present invention relates to an overload detection device configured to avoid accidents such as burnout of the motor itself.

It is widely known that when a motor is overloaded, the drive current increases, causing abnormal heat generation, which may lead to burnout of the motor. Therefore, in order to avoid this kind of danger, a protection circuit is generally built into the motor, and when an abnormal current occurs, the supply of current to the motor is cut off under the action of the protection circuit. For example, incorporating a protection relay etc. can be said to be a good example.

However, in the case of a servo motor, where the speed and torque can be arbitrarily selected in relation to the object, whether or not there is an overload is determined by the selected speed, etc. However, there is a problem in that this type of servo control system is not suitable for a control configuration such as the conventional technology in which all loads exceeding a certain rating are determined to be overloads and the current supply is cut off.

The present invention has been made to solve the above-mentioned disadvantages, and compares the control signal of the rotating electric motor with a selectively determined reference signal, and if it is within the range of the reference signal, the control signal is directly transmitted. It is an object of the present invention to provide an overload detection device configured to continue supplying current to a rotating electric motor and to detect and cut off current when a control signal goes outside the range.

In order to achieve the above-mentioned object, the present invention comprises a comparator 1 having a configuration in which an output range can be freely set for a control signal of a rotating electric motor using a plurality of variable resistors, and a relay equipped with a relay connected to the output side of the comparator. and a relay that controls the supply of input signals to the rotary motor, and when the control signal input to the comparator is outside the range set by the variable resistor, the comparator energizes the output signal to the relay. The present invention is characterized in that the control signal is output to the circuit and the control signal to the rotary motor is cut off by a relay.

Next, preferred embodiments of the overload detection device according to the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, reference symbols VRI, VH2 and VH3
represent variable resistors connected in series, and the outputs voltage-divided by the variable resistors VRI, VH2 and VH3 are connected to one input side of the first oP amplifier 12 and the second oP amplifier constituting the window comparator 10, respectively. Connect to one input side of amplifier 14. The configuration is such that a branched control input signal is introduced into the other input side of the 10th P amplifier 12 and the 20th P amplifier 14 via a fixed resistor R1. The output side of the window comparator IO is connected to the processing device 16 and also to a coil 20 constituting a relay power circuit 18 on the output side of the processing device 16 .

In this case, the processing device 16 is composed of a photocoupler consisting of a light emitting diode 22 and a phototransistor 24.

In the figure, reference numeral 26 indicates a diode for blocking backflow, and reference numeral 28 indicates a normally closed contact that is opened under the bias of the coil 20.

The overload detection device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the output range of the window comparator 10 is set by adjusting the variable resistors VRI to VR3, respectively. That is, when a branched control signal of a servo motor (not shown) is manually input within the range of the set output, there is no output from the window comparator 10. On the other hand, when the control signal is outside the setting range of the variable resistors VRI to VR3, the window comparator 10 outputs its output to the processing device 16. Since the processing device 16 is composed of a photocoupler, it supplies its output to the relay energizing circuit 18 with its input side and output side completely electrically insulated. As a result, the coil 20 is energized and the normally closed contact 28 is opened, completely blocking the flow of the control signal related to overload to the servo motor (not shown).

In this case, if a plurality of the photocouplers are connected in parallel and the H level signals of the 10th P amplifier 12 and the 20th P amplifier 14 are introduced into each photocoupler separately, the servo input can be corrected. It is possible to easily infer whether an abnormality is occurring in either direction of rotation.

According to the present invention, it is possible to cut off the supply of abnormal current to the rotary electric motor with an extremely simple configuration as described above, and when the rotational speed and torque are changed such that the rotary electric motor constitutes a servo system, the control The set value of the comparator for the signal can be changed arbitrarily, which has the advantage of simplifying control. Furthermore, effects such as being able to detect an overload in the rotational direction by determining an output signal outside the set value range can be obtained.

The present invention has been described above by citing preferred embodiments, but the present invention is not limited to these embodiments, and various improvements and design changes can be made without departing from the gist of the present invention. Of course words.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an overload detection device according to the present invention. 10...Window comparator 12...10th P amplifier 14...20th P amplifier 16
... Processing device 18 ... Relay energizing circuit 20 ... Coil 22 ... Light emitting diode 24 ... Phototransistor 26 ... Backflow blocking diode 28 ... Normally closed contact

Claims (1)

[Claims] (1) A comparator configured to freely set an output range for a control signal of a rotating electric motor using a plurality of variable resistors;
A relay energizing circuit connected to the output side of the comparator is connected to a relay that controls the supply of the input signal to the rotating motor, and the control signal input to the comparator is outside the range set by the variable resistor. An overload detection device characterized in that the overload detection device is configured to derive an output signal from the time comparator to the relay energizing circuit and cut off a control signal to the rotating electric motor by the relay. (2. In the device according to claim 1, the comparator is an overload detection device consisting of a window comparator. (3) In the device according to claim 1 or 2, the comparator and the relay energization An overload detection device with a photocoupler interposed between the circuit and the circuit.