JP2001318013A - Driving torque detector for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acuurately and quickly conduct detection even when an excessive driving torque is applied to a motor. SOLUTION: This detector detects a driving torque of the motor 2 provided on a frame 9 supported by an output shaft 5, of which the rotational drive is transmitted to the output shaft 5. The gear frame 9 is supported onto the output shaft 5 in a suspended condition via a reduction gear 4 in its longitudinal- directional one end side, and is supported from a lower side by a load cell (reaction detecting part) 11 attached with respect to a floor part 10 therebetween in the longitudinal-directional other end side. The load cell 11 is such one as electric resistance of a strain gage provided in its inside is varied in response to a tension load to vary an electric current, when the load is applied, and the current variation is measured to find the tension load. The load is detected to detect the driving torque of the motor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive torque detecting device for an electric motor for rotating a bucket elevator or a conveyor.

[0002]

2. Description of the Related Art In a belt conveyor, for example, a rotational drive output from a motor such as a motor is transmitted to an output shaft of a pulley via a speed reducer to drive a belt wound around the pulley. In this type of belt conveyor, the output torque of the motor is proportional to the current flowing through the motor,
If the conveyor is overloaded due to a large amount of conveyance or the like and the driving torque of the motor is increased, a large amount of current will flow through the motor. For this reason, conventionally, an ammeter such as an overload relay (overcurrent detector) is provided in the motor to detect the motor current and detect an abnormality, thereby preventing the overcurrent from flowing through the motor.

[0003]

However, the conventional motor drive torque detecting device as described above has the following problems. Since the response speed is slow in the method of detecting the current flowing through the electric motor, there is a possibility that a failure occurs in the device before the abnormality detection signal is output. In addition, since the motor current value has low accuracy, there is a problem in reliability of abnormality detection.

[0004] The present invention has been made in view of the above points, and even if an excessive driving torque is applied to the electric motor,
It is an object of the present invention to provide a drive torque detecting device capable of detecting accurately and quickly.

[0005]

In order to achieve the above object, the present invention employs the following constitution. The drive torque detecting device for an electric motor according to claim 1, wherein the drive torque detecting device is provided on a frame supported on an output shaft, and rotational drive is transmitted to the output shaft. A reaction force detecting unit for detecting a reaction force applied to the frame is provided.

Accordingly, the motor driving torque detecting device of the present invention can detect the load applied to the frame due to the reaction force generated when the output shaft is driven to rotate. This reaction force
Almost simultaneously with the rotation driving of the motor and at the same magnitude as the rotation output, the driving torque applied to the motor is calculated by calculating the product of the load on the frame and the distance between the output shaft and the reaction force detector. It can be calculated quickly and accurately.

According to a second aspect of the present invention, in the driving torque detecting device for a motor according to the first aspect, the reaction force detecting unit is a load cell attached to the frame. It is assumed that.

Therefore, in the drive torque detecting device for an electric motor according to the present invention, when a load is applied to the load button via the frame, the electric resistance of the strain gauge changes according to the load, so that the flowing current changes. Then, by measuring the change in the current, the load applied to the frame can be measured.

According to a third aspect of the present invention, there is provided an electric motor driving torque detecting apparatus according to the first or second aspect, wherein the electric motor rotational driving is performed based on a detection result of the reaction force detecting section. And a control unit for controlling the

Therefore, in the motor driving torque detecting device of the present invention, for example, a threshold value is set in the control unit,
When the detection result of the reaction force detection unit exceeds the threshold value, safety can be improved by reducing the load on the motor or stopping the motor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a motor driving torque detecting apparatus according to the present invention will be described below with reference to FIGS. Here, for example, description will be made using an example in which a belt conveyor is driven by an electric motor.

FIG. 1 is a front view of the belt conveyor 1. The belt conveyor 1 reduces the rotational drive of the electric motor 2 by a speed reducer 4 connected by a coupling 3 and transmits it to an output shaft 5 connected to the speed reducer 4, thereby forming a pulley 6 having an output shaft 5. During one, it is rotated clockwise.
An endless belt 7 is wound around the pulley 6.
The configuration is such that the belt 7 moves by the rotation of the pulley 6.

As shown in FIG. 2, the output shaft 5 is connected to a pulley 6
Are rotatably supported by bearings 8, 8, and one end on the side of the reduction gear 4 protrudes from the bearing 8 and is connected to a reduction mechanism (for example, a reduction gear) of the reduction gear 4. The reduction gear 4 and the electric motor 2 are fixedly mounted on a gear frame (frame) 9 having a rectangular shape in a plan view by fixing means such as bolts.

As shown in FIG. 1, the gear frame 9 is supported on the output shaft 5 via a speed reducer 4 at one end in the longitudinal direction, and is provided on the floor at the other end in the longitudinal direction. The load cell 10 is supported from below by a load cell (reaction force detection unit) 11 attached to the load cell 10. When a tensile load is applied, the load cell 11 changes the electric current flowing due to a change in the electric resistance of a strain gauge provided therein according to the load, and measures the current fluctuation. The tensile load can be determined.

The output of the load cell 11 is input to a controller (control unit) 12 such as a computer. An upper limit value of the driving torque of the electric motor 2 is set as a threshold value in the controller 12, and the controller 12 controls the rotational driving of the electric motor 2 based on the output of the load cell 11.

The procedure for detecting the driving torque of the electric motor 2 in the belt conveyor having the above configuration will be described below. Here, it is assumed that 150% of the rated torque of the electric motor 2 is set in the controller 12 as a threshold value.

When the rotational drive of the electric motor 2 is transmitted to the output shaft 5 via the speed reducer 4, a drive torque clockwise in FIG. At the same time as the rotation of the output shaft 5, a counterclockwise reaction force is generated in the gear frame 9 about the output shaft 5. Due to this reaction force, a tensile load acts on the load cell 11, and an electric signal (output current) corresponding to the load is output to the controller 12. Here, the following equation is established among the load P corresponding to this signal, the distance L between the output shaft 5 and the load cell 11, and the driving torque T of the electric motor 2. T = P × L (1)

Since the distance L is constant, the load cell 12
, The drive torque of the electric motor 2 can be calculated using the equation (1). In other words, since the load applied to the load cell 11 and the current value output at this time have a fixed relationship, by monitoring this current value, the load acting on the load cell 11 and the driving torque of the electric motor 2 can be reduced. Can be monitored.

For example, when the rated load of the load cell 11 is R _R
(T) The output current at this time is set to 20 (mA), and the load when the load cell 11 is set on the gear frame 9 without driving the electric motor 2 (only the own weight of the electric motor 2, the speed reducer 4, and the gear frame 9) is reduced. R1 (t), assuming that the output current at this time is A1 (mA), the relationship between the load cell output and the load cell load is shown in FIG. 3 (the output current when the load cell 11 is unloaded is 4 mA). Here, assuming that the load cell load when the electric motor 2 is driven at the rated torque of 100% is R _M (t), the output current Ax (mA) of the load cell 11 when driven at x% of the rated torque is expressed by the following equation. It is.

(Equation 1) Also,

(Equation 2)

Therefore, when the load cell 11 outputs a current value A ₁₅₀ or more corresponding to a driving torque of 150% of the rated torque, and exceeds a threshold value set in the controller 12, the electric motor 2 is turned on by 150% of the rated torque. It can be detected that the motor is driven by the above output. Controller 12
Determines that the output current of the load cell 11 has exceeded the threshold, the output of the motor 2 is reduced or the motor 2 is stopped so that the output current becomes equal to or less than the threshold.

In the motor driving torque detecting device according to the present embodiment, the gear frame 9 is driven by the rotation of the output shaft 5.
Is detected by the load cell 11, the responsiveness is better than in the conventional case where the current of the electric motor 2 is detected, and the excessive driving torque in the electric motor 2 can be accurately detected.
And it can be detected quickly. Therefore, it is possible to prevent the occurrence of device failure due to excessive driving torque.

In this embodiment, the controller 1
2 monitors the output current of the load cell 11 and
Is controlled, the application of an excessive drive torque to the electric motor 2 can be reliably avoided, and the effect of contributing to labor saving can be achieved.

In the above embodiment, the output shaft 5
The load cell 11 detects the reaction force associated with the rotational driving of the load cell 11. However, the present invention is not limited to this. For example, the drive torque may be controlled using a strain gauge and an amplifier.

In the above-described embodiment, an example in which the driving torque of the electric motor used in the belt conveyor is detected is used. However, the present invention is not limited to this, and the present invention can be applied to a driving device of another rotary output system such as a bucket elevator. It is.

[0025]

As described above, in the motor driving torque detecting device according to the first aspect, the reaction force detecting section detects the reaction force applied to the frame as the output shaft rotates. . As a result, the drive torque detecting device of the electric motor has better responsiveness than the case of detecting the electric current of the electric motor, and can detect the excessive drive torque accurately and quickly. An effect is obtained that the occurrence of device failure can be prevented beforehand.

According to a second aspect of the present invention, the reaction torque detector is a load cell. Thus, the driving torque detecting device for an electric motor has an effect that the driving torque of the electric motor can be detected by the power fluctuation of the strain gauge corresponding to the reaction force applied to the load cell.

According to a third aspect of the present invention, the control unit controls the rotation of the motor based on the detection result of the reaction force detecting unit. This allows
The drive torque detecting device for an electric motor has an effect that it is possible to reliably prevent an excessive drive torque from being applied to the electric motor and to contribute to labor saving.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a front view of a belt conveyor having a load cell.

FIG. 2 is a plan view of the belt conveyor.

FIG. 3 is a relationship diagram showing a relationship between a load applied to a load cell and an output current.

[Explanation of symbols]

 2 motor 5 output shaft 9 gear frame (frame) 11 load cell (reaction force detection unit) 12 controller (control unit)

Claims (3)

[Claims] 1. An electric motor drive torque detecting device provided on a frame supported on an output shaft and transmitting rotational drive to the output shaft, wherein a reaction force applied to the frame as the output shaft rotates. A drive torque detecting device for an electric motor, comprising: a reaction force detecting unit for detecting a torque. 2. The drive torque detecting device for an electric motor according to claim 1, wherein the reaction force detector is a load cell attached to the frame. 3. The electric motor driving torque detecting device according to claim 1, further comprising: a control unit that controls a rotational driving of the electric motor based on a detection result of the reaction force detecting unit. Drive torque detecting device.