JPH04258586A - Drive sleeve wear rate measuring device - Google Patents

Abstract

PURPOSE:To provide a drive sleeve wear rate measuring device capable of external measurements without touching an actuator, requiring no special technical skill for an observer, and capable of short-time measurements. CONSTITUTION:Starting current flowing to a motor 8 for a motor-driven actuator is extracted by a current transformer 1, both-wave rectified by a rectifier 2, and pulses are counted by a counter 3, while the changes in current levels applied through a peak holder 4 are observed by a rate-of-change measuring device 5, and when the current begins to increase, the counting operation of the counter 3 is stopped, and the amount of wear on a drive sleeve can be found out from the counted values.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive sleeve wear measurement device for actuators for opening and closing valves and gates.

0002

[Prior Art] Conventionally, for example, in order to check the degree of wear on the drive sleeve of the actuator of an electric valve, the actuator was removed from the electric valve, the drive sleeve was removed, and the inspection was performed directly visually or the dimensions and shape were measured. Ta.

0003

[Problem to be Solved by the Invention] Conventionally, in order to determine the degree of wear of the drive sleeve, disassembly and inspection are performed as described above, which requires a great deal of time and effort, and also requires a specialized engineer. There was a problem. This invention was made in view of the above-mentioned problems, and can be measured from the outside without touching the actuator, does not require special skills on the part of the measurer, and can be measured in a short time. The purpose of the present invention is to provide a drive sleeve wear measurement device.

0004

[Means and Effects for Solving the Problems] The drive sleeve wear measurement device of the present invention includes a current extracting means for extracting the current that flows when the electric actuator is started, and a current extracting means that observes this extracted current so that the current level is determined from the time of starting. and a means for measuring the time until the wear starts to increase, so that the amount of wear can be determined based on the time.

[0005] FIG. 3 shows an example of observation of current when starting a motor for driving an actuator. In this waveform, A indicates when the electromagnetic switch is turned on, B indicates when the motor starts and accelerates, C indicates no-load operation, D indicates hammer blow, and E indicates steady-load operation. Here, the relationship between the degree of wear of the drive sleeve and the effective value level of the current waveform is as shown in FIG. 4. In FIG. 4, q is the characteristic when the drive sleeve is new, and r is the characteristic when it is worn. When the drive sleeve wears out, the load is applied to the motor only after the hammer blow time TS1 and the time ΔT due to play in the drive sleeve screw have elapsed. Hammer blow and
During this screw play, the load on the motor is very light, so the motor rotates at approximately synchronous speed. Therefore, the time difference between when the actuator is initially used and when a load is applied to the motor is proportional to the play in the screw, that is, the amount of wear. The present invention focuses on this point, and since the time TS1 until the initial load is applied is known, the current at the time of startup is extracted by the current extraction means, and this extracted current is measured to increase the current level from the time of startup. The amount of wear is determined based on the measured time. For example, if the current measurement time TS2 is equal to TS1, it can be determined that there is no wear, and if TS2-TS1 is large, it can be determined that the wear is progressing.

[0006]

[Examples] The present invention will be explained in more detail with reference to Examples below. FIG. 1 is a block diagram of a drive sleeve wear measurement device showing one embodiment of the present invention. This measuring device consists of a current transformer 1, a rectifier 2 that double-wave rectifies the output of the current transformer 1, a counter 3 that counts the pulse train output from the rectifier 2, and a peak value of the output wave of the rectifier 2. a peak holder 4 that holds the peak holder 4; and a rate of change measuring device 5 that measures the rate of change in amplitude from the output of the peak holder 4 and stops the counting operation of the counter 3 when the rate of change exceeds a predetermined value. It is configured.

When measuring the degree of wear of the drive sleeve using this measuring device, the current transformer 1 is connected to a three-phase AC power source 6.
It is clipped onto the power supply wiring 7 that supplies power to the actuator motor 8 from the connector. When the electromagnetic switch is turned on and a starting current flows to the motor 8 via the power supply wiring 7, this current is detected by the current transformer 1, further rectified by the rectifier 2 in both waves, and is converted into a half-wave pulse train a (Fig. 2) is input to the counter 3 and counted.

On the other hand, the pulse output from the rectifier 2 is
The peak holder 4 detects the peak of each pulse, holds the peak value until the peak of the next pulse is detected, and sends the peak output b in FIG. 2 to the change rate measuring device 5. input. The rate of change measuring device 5 has a peak output b
In response to the fact that the rate of change has exceeded a predetermined value, at the point when point c in FIG. let Note that the current also increases when the motor 8 is started, but at this point TM is sufficiently short compared to TS, so
An increase in current will be detected after a sufficient period of time has passed after startup. The counter 3 counts the pulse train from the rectifier 2 from when the electromagnetic switch is turned on until the counting operation is stopped by the output of the rate of change measuring device 5. If this count number is PC, the time TS is 50Hz
In the case of current, it is 1/50 x PC x 1/2 (seconds). In this way, from the count value PC of counter 3, T in FIG.
By calculating S and outputting it as an output PM, the degree of wear of the drive sleeve can be determined based on the magnitude of this output value PM.

If the pulse value PS corresponding to the time TS when the drive sleeve is new and not worn is preset in the counter 3 in advance, a value corresponding to the amount of wear can be obtained as the output PM. As shown in Figure 4,
If the time until the current increases when it is new is TS1, and the current time, that is, the time until the current increases during the current measurement, is TS2, then the output PM is f(TS2-TS1).

FIG. 5 shows a torque characteristic curve of the actuator motor. During hammer blow and drive sleeve play, the motor load is very light and the motor rotates at approximately synchronous speed, so the PM value can be considered to be directly proportional to the amount of wear. That is, PM = K(TS2-T
S1). Therefore, the output PM of the counter 3 is output as the amount of wear.

[0011] Note that the time TS1 when the actuator is new can be calculated theoretically by the actuator design contractor, so there is no need to specifically measure it when the actuator is manufactured. Therefore, for actuators that are used for a long period of time, the design time is TS1.
If this is known, the present invention can be applied. Further, in the above embodiment, an AC-powered induction motor was used as an example of the drive motor for the actuator, but even in the case of a DC motor, it is sufficient to measure the time until the current starts to rise when a load is applied. In this case, a separate clock pulse generator will be provided for measurement.

0012

[Effects of the Invention] According to this invention, the wear of the drive sleeve is measured by measuring the time from startup until the current starts to increase, so there is no need to disassemble the actuator. Therefore, time and labor required for wear inspection can be reduced.

■Without touching the actuator,
Can be measured externally. ■Since the amount of wear is obtained as the output of the measuring device, the measurer does not require any special skills. ■Measurements can be carried out at easily accessible locations along the wiring route to the motor. There are other effects. The above effect is particularly effective when there are hundreds to thousands of actuators in one plant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a drive sleeve wear measurement device showing an embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the drive sleeve abrasion measurement device of the same embodiment.

FIG. 3 is a waveform diagram showing current changes when starting a motor.

FIG. 4 is an explanatory diagram showing the relationship between the degree of wear of the drive sleeve and the motor current.

FIG. 5 is a diagram showing a torque characteristic curve of a motor.

[Explanation of symbols]

1 Current transformer 2 Rectifier 3 Counter 4 Peak holder 5 Rate of change measuring device 8 Actuator motor

Claims (1)

[Claims] 1. Current extraction means for extracting a current flowing when an electric actuator is started, and means for observing this extracted current and measuring the time from the time of start until the current level starts to increase, A drive sleeve wear measurement device characterized by being able to determine the amount of wear based on the amount of wear.