JP2013196607A - Flow rate controller and flow rate testing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize highly accurate flow rate control even when a flow rate change is large.SOLUTION: A flow rate controller includes: a servo valve 5 for discharging a working fluid supplied from fluid pressure supply sources 2 and 4 while controlling a flow rate; an entrance pressure detector 11 for detecting the entrance pressure of the servo valve 5; an exit pressure detector 12 for detecting the exit pressure of the servo valve 5; a displacement detector 13 for detecting the spool displacement of the servo valve 5; and a controller 102 for computing the discharge flow rate of the servo valve 5 on the basis of detection results of the entrance pressure detector 11, the exit pressure detector 12 and the displacement detector 13, and outputting an aperture command to the servo valve 5 so that the computed flow rate becomes a predetermined set flow rate.

Description

  The present invention relates to a flow rate control device and a flow rate test device using the same.

  It is known to perform flow control by controlling the opening of a flow control valve based on the measurement result of a flow meter (see, for example, Patent Document 1).

JP 2009-103109 A

  However, when the flow rate change is large, the measurement value of the flow meter has poor responsiveness, so there is a limit to the flow rate control based on the measurement result of the flow meter.

  The present invention has been made in view of the above problems, and an object thereof is to realize highly accurate flow rate control even when the flow rate change is large.

  The flow control device according to the present invention includes a fluid pressure supply source that supplies a working fluid, a servo valve that discharges the working fluid supplied from the fluid pressure supply source while performing flow control, and an inlet pressure of the servo valve. An inlet pressure detector for detecting, an outlet pressure detector for detecting an outlet pressure of the servo valve, a displacement detector for detecting a spool displacement of the servo valve, the inlet pressure detector, the outlet pressure detector, and A controller that calculates a discharge flow rate of the servo valve based on a detection result of the displacement detector and outputs an opening degree command to the servo valve so that the calculated flow rate becomes a predetermined set flow rate. It is characterized by.

  According to the present invention, since the discharge flow rate of the servo valve is calculated based on the detection results of the inlet pressure detector, the outlet pressure detector, and the displacement detector, it is calculated even when the flow rate change is large. The discharge flow rate has good responsiveness. Since the flow rate control by the servo valve is performed using the calculated flow rate as a feedback signal, highly accurate flow rate control can be realized.

1 is a system diagram of a flow rate test apparatus according to a first embodiment of the present invention, where a solid line indicates a hydraulic system and a dotted line indicates a signal flow. FIG. It is a figure which shows the change of the calculation flow volume and actual flow volume which were displayed on the monitor. FIG. 4 is a system diagram of a flow rate test apparatus according to a second embodiment of the present invention, where a solid line indicates a hydraulic system and a dotted line indicates a signal flow.

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

<First Embodiment>
With reference to FIG.1 and FIG.2, the flow test apparatus 100 which concerns on 1st Embodiment of this invention is demonstrated.

  The flow rate test apparatus 100 is an apparatus that instantaneously supplies a large flow rate of liquid to the specimen 1 and tests performances such as fatigue and durability of the specimen 1. The specimen 1 is a valve, piping, a joint for piping, a flexible hose, or the like, and is a component used in an environment where the flow rate change is large. The liquid is oil in the present embodiment, but may be water or the like.

  As shown in FIG. 1, the flow rate test apparatus 100 includes a tester main body 101 and a controller 102 that controls the operation of the tester main body 101. In FIG. 1, the hydraulic system is indicated by a solid line, and the signal flow is indicated by a dotted line.

  The testing machine main body 101 includes a tank 8 in which hydraulic oil (working fluid) is stored, a hydraulic pump 2 that sucks and supplies the hydraulic oil in the tank 8, a supply passage 3 that connects the hydraulic pump 2 and the specimen 1, The accumulator 4 is connected to the supply passage 3 and the hydraulic fluid discharged from the hydraulic pump 2 is pressured, and the hydraulic fluid pressured by the accumulator 4 is discharged to the specimen 1 while controlling the flow rate. And a return passage 6 for connecting the specimen 1 and the tank 8 to each other. The hydraulic pump 2 and the accumulator 4 correspond to the “fluid pressure supply source” in claim 1.

  The testing machine main body 101 includes an inlet pressure gauge 11 as an inlet pressure detector that is provided on the upstream side of the servo valve 5 in the supply passage 3 and detects the inlet pressure of the servo valve 5, and the servo valve 5 in the supply passage 3. An outlet pressure gauge 12 provided on the downstream side as an outlet pressure detector for detecting the outlet pressure of the servo valve, a flow meter 14 provided in the return passage 6 as a flow rate detector for detecting the discharge flow rate of the servo valve 5; Is provided. As the flow meter 14, a Coriolis flow meter having excellent accuracy and durability is used. The actual flow rate Qr detected by the flow meter 14 is output and displayed on the monitor 21 as shown in FIG.

  The servo valve 5 has a spool that is displaced by a command signal from the controller 102, and the spool opening degree is controlled so that the discharge flow rate becomes a predetermined set flow rate. The servo valve 5 is provided with a displacement meter 13 as a displacement detector for detecting the spool displacement.

  The specimen 1 is attached between the two attachment ports 7a and 7b in a replaceable manner via a quick coupler or the like. The test machine main body 101 is an apparatus that instantaneously supplies a large flow rate of hydraulic fluid to the specimen 1 through the servo valve 5 and tests the influence on the specimen 1 due to a rapid flow rate change. The flow rate change is, for example, a change that rises from 50 L / min to 1200 L / min in 0.1 seconds. Even if such a rapid change in flow rate is controlled by using the measurement result of the flow meter 14 as a feedback signal, the measured value by the flow meter 14 is poorly responsive and unstable (see FIG. 2). There were limits.

  As a countermeasure, in this embodiment, a calculated flow rate calculated based on the detection results of the inlet pressure gauge 11, the outlet pressure gauge 12, and the displacement gauge 13 is used as a feedback signal for flow rate control by the servo valve 5. Hereinafter, control of the servo valve 5 by the controller 102 will be described.

  The controller 102 includes a CPU that controls the operation of the servo valve 5, a ROM that stores control programs and setting values necessary for the processing operation of the CPU, an inlet pressure gauge 11, an outlet pressure gauge 12, a displacement gauge 13, And a RAM that temporarily stores information detected by various sensors such as the flow meter 14.

  The controller 102 changes to a pulse shape that rises from 50 L / min to 1200 L / min in 0.1 seconds as the set flow rate, holds for 1200 seconds at 1200 L / min, and then decreases from 1200 L to 50 L / min in 0.1 seconds. The flow rate waveform to be generated is predetermined so as to be generated continuously.

  As shown in FIG. 1, in the controller 102, the spool opening degree L calculated from the spool displacement detected by the displacement gauge 13, the servo valve supply pressure Ps detected by the inlet pressure gauge 11, and the inlet pressure gauge 11 and the outlet The discharge flow rate Qc of the servo valve 5 is calculated based on the actually measured differential pressure ΔP1 that is the pressure difference detected by the pressure gauge 12. Specifically, the discharge flow rate Qc is calculated based on the following equation (1).

  Data of the discharge flow rate Qc (calculated flow rate) calculated based on the above (1) is output to the monitor 21, and the monitor 21 displays the discharge flow rate Qc in real time as shown in FIG. The calculation cycle of the discharge flow rate Qc is several msec.

  The servo amplifier 22 outputs an opening degree command to the servo valve 5 so that the discharge flow rate Qc calculated based on the above (1) becomes a predetermined set flow rate. Thus, the flow rate control by the servo amplifier 22 is performed using the discharge flow rate Qc calculated based on the above (1) as a feedback signal. The calculation cycle of the flow rate control by the servo amplifier 22 is several msec.

  The discharge flow rate Qc is a theoretical flow rate calculated by the above equation (1) using the spool opening L, the servo valve supply pressure Ps, and the actually measured differential pressure ΔP1 as factors, and is calculated in real time. Therefore, even when the flow rate change is large, the calculated discharge flow rate Qc has good responsiveness, and a stable feedback signal can be obtained. Since the flow rate control by the servo amplifier 22 is performed using the stable feedback signal, the accuracy is high.

  According to the above 1st Embodiment, there exists an effect shown below.

  Since the discharge flow rate of the servo valve 5 is calculated using the spool opening L, the servo valve supply pressure Ps, and the actually measured differential pressure ΔP1 as factors, the calculated discharge flow rate is responsive even when the flow rate change is large. Will be good. Since the flow rate control by the servo valve is performed using the calculated discharge flow rate as a feedback signal, highly accurate flow rate control can be realized.

  In general, when measuring a flow rate with a flow meter, the flow of the fluid needs to be laminar, but in this embodiment, the flow rate is measured by calculation using the above three factors. Unaffected by turbulence. Therefore, highly accurate flow rate control can be realized even when the fluid flow is turbulent.

Second Embodiment
Next, with reference to FIG.2 and FIG.3, the flow test apparatus 200 which concerns on 2nd Embodiment of this invention is demonstrated. Hereinafter, only differences from the first embodiment will be described, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

  The flow rate test apparatus 200 is different from the first embodiment in that the opening degree command output from the servo amplifier 22 to the servo valve 5 is corrected based on the detection result of the flow meter 14. The correction will be described below.

  The discharge flow rate Qc calculated by the above equation (1) is a theoretical flow rate, not an actually measured flow rate. On the other hand, the actual flow rate Qr detected by the flow meter 14 is low in accuracy because the response is not good during the flow rate change, but is high in a constant flow rate range. In particular, the Coriolis type flow meter used for the flow meter 14 is characterized by good response and low mechanical wear, and is excellent in accuracy and durability even in an environment where the flow rate change is repeated.

  Therefore, in order to ensure the accuracy of the discharge flow rate Qc calculated by the equation (1), the actual flow rate Qr detected by the flow meter 14 in the constant flow rate region becomes the set flow rate (1200 L / min in this embodiment). Thus, the opening degree command output from the servo amplifier 22 to the servo valve 5 is corrected. Specifically, the deviation of the actual flow rate Qr with respect to the set flow rate is calculated, and an opening correction signal that eliminates the deviation is calculated and output to the servo amplifier 22. The servo amplifier 22 calculates the opening degree command of the servo valve 5 so that the discharge flow rate Qc becomes a predetermined set flow rate using the discharge flow rate Qc calculated based on the above (1) as a feedback signal. The corrected opening degree command is corrected by the opening degree correction signal, and the corrected opening degree command is output to the servo valve 5.

  The correction of the opening degree command is desirably performed when the actual flow rate Qr detected by the flow meter 14 is stabilized (between 4 and 5 seconds in FIG. 2).

  In addition, the correction of the opening command is not performed in real time, but the opening command is corrected by the opening correction signal calculated when the previous pulsed flow waveform was generated to generate the pulsed flow waveform. Good. By correcting in this way, the accuracy of the flow rate control is improved every time the pulsed flow rate waveform is generated.

  According to the above 2nd Embodiment, there exists an effect shown below.

  Since the opening degree command output from the servo amplifier 22 to the servo valve 5 is corrected based on the actual flow rate Qr detected by the flow meter 14, more accurate flow rate control can be realized.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  In the above embodiment, the case where the servo valve 5 is used in the flow rate test apparatus 100 has been described. However, the servo valve 5 can be used in a flow rate control device that performs flow rate control with a large flow rate change, and its application is not limited.

  Moreover, in the said embodiment, the case where the hydraulic pump 2 and the accumulator 4 were used as a fluid pressure supply source was illustrated. In the above embodiment, the accumulator 4 is used to realize a large flow rate change. However, depending on the magnitude of the flow rate change, the accumulator 4 is not necessary, and the fluid pressure supply source can be configured only by the hydraulic pump 2.

  The present invention can be used as a flow test device for testing performance such as fatigue and durability of a specimen.

100, 200 Flow test device 101 Test machine main body 102 Controller 1 Specimen 2 Hydraulic pump (fluid pressure supply source)
4 Accumulator (fluid pressure supply source)
5 Servo valve 11 Inlet pressure gauge (Inlet pressure detector)
12 Outlet pressure gauge (Outlet pressure detector)
13 Displacement meter (displacement detector)
14 Flowmeter (Flow detector)
21 Monitor 22 Servo amplifier

Claims (3)

A fluid pressure source for supplying the working fluid;
A servo valve that discharges the working fluid supplied from the fluid pressure supply source while controlling the flow rate;
An inlet pressure detector for detecting the inlet pressure of the servo valve;
An outlet pressure detector for detecting an outlet pressure of the servo valve;
A displacement detector for detecting a spool displacement of the servo valve;
Based on the detection results of the inlet pressure detector, the outlet pressure detector, and the displacement detector, a discharge flow rate of the servo valve is calculated, and the servo valve is set so that the calculated flow rate becomes a predetermined set flow rate. A controller that outputs an opening command to
A flow rate control device comprising: A flow rate test apparatus comprising the flow rate control apparatus according to claim 1, wherein a performance test of the specimen is performed by discharging a working fluid to the specimen while performing flow control with the servo valve.
A flow detector for detecting the discharge flow rate of the servo valve;
The flow rate test apparatus, wherein the controller corrects the opening degree command so that an actual flow rate detected by the flow rate detector becomes the set flow rate. The set flow rate is a flow waveform that changes in a pulse shape,
The flow rate test apparatus according to claim 2, wherein the correction is performed in a constant flow rate range of a flow rate waveform that changes in a pulse shape.

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