JPH0143247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test device for a gas flow meter, and more particularly, to a test device for testing the characteristics of a gas flow meter that outputs an electrical signal corresponding to an air flow rate. Settings are made by opening and closing the sonic nozzle (SV meter), the output signal of the gas flowmeter under test for each reference flow rate is compared with the reference value, and the result of the comparison is used to determine whether the gas flowmeter under test passes or fails. This is what I did.

FIG. 1 is a configuration diagram for explaining one embodiment of a test apparatus according to the present invention, in which 10 is a vacuum pump, 20 is an SV meter unit, 30 is a gas flow meter which is a test object, and 40 is a A filter, 50 is a piston cylinder, 60 is a control device and operation panel. When the test specimen 30 is set at the position shown in the figure and the vacuum pump 10 is driven, outside air flows through the filter 4.
0, flows toward the vacuum pump 10 through the gas flow meter 30 and the SV meter unit 20. The filter 40 is designed to keep the sonic nozzle clean at all times.
It removes minute dust from the incoming air.
The purpose is to increase the reliability of the reference flow rate value of the sonic nozzle. On the surface of the control device and operation panel 60, there are operation sections including a clamp button 61, an unclamp button 62, an inspection start button 63, an _inspection stop button ₆₄ , etc.
A pass/fail judgment display section is provided for
When the clamp button 61 is pressed, the piston cylinder 5
As the piston 0 moves downward, the pistons of the other piston cylinders 70 move to the right in the figure, and when the unclamp button 62 is pressed, the pistons of the piston cylinders 50 move upward and the pistons of the piston cylinders 70 move to the left. It is starting to return to . Now, with the piston rising upward, place the test object 30 in the position shown in the figure and press the clamp button 61 to release the piston cylinder 50.
The piston moves downward to fix the test object 30 in a predetermined position, and the piston cylinder 7
The piston 0 moves to the right and connects the electrical output terminal portion 31 of the test object 30 to the lead wire from the operation panel 60. Next, when the test start button 63 is pressed, the SV meter 24 in the SV meter unit 20
_{Nos. 1} to 24n are opened and closed according to a predetermined sequence built in advance, and in the illustrated example, Nos. ₁ to 24n
Four types of reference flow rates No. ₄ are selected in sequence, and the measured values of the test object 30 for each reference flow rate are displayed on the operation panel 60.
The comparison is made by the arithmetic unit within. That is,
The interior of the SV meter unit 20 is divided into a front chamber 22 and a rear chamber 23 by a partition wall 21, and SV meters 24 ₁ to 24n are provided in the partition wall 21 to selectively communicate the front chamber 22 and the rear chamber 23. and these SV
selectively opening and closing the piston cylinders 25 ₁ to 25n according to a sequence built into the control section of the operation panel 60 to open and close the meters 24 ₁ to 24n;
A reference flow rate for the test object 30 is created.

FIG. 2 is a diagram showing the characteristic curve of the test object 30, in which the horizontal axis shows the flow rate, the vertical axis shows the output power,
The curve is the standard characteristic curve, is the allowable upper limit curve, is the allowable lower limit curve, Q ₁ to _{Q 4} are the test flow rates, and each test flow rate corresponds to the display lamps No. ₁ to _{No. 4} on the operation panel 60, and each flow rate Reference values for Q ₁ to _{Q 4}
E ₁ to _{E 4} are stored in advance in the memory within the operation panel 60. Now, when you return to the original state and press the inspection start button 63, the SV meters 24 ₁ to 24n are opened and closed according to the sequence preset in the operation panel 60, and the reference flow rates Q ₁ to _{Q 4} are The output signals of the test object 30 for each flow rate Q ₁ to _{Q 4} are sequentially created and compared with a reference value (curve) stored in advance in the memory in the operation panel 60, and the results of each comparison are determined as the upper and lower limits. If it falls between the allowable curves (within the shaded range), it is No. ₁ to _{No. 4} .
It is displayed on the GC indicator light, and if it is outside the allowable range, it is NG.
Displayed on the indicator light. Note that the SV meter needs to maintain the pressure before and after it within a critical pressure, so it is necessary to keep the upstream pressure, temperature, humidity, etc. constant, but it is difficult to keep these constant. Therefore, in reality, a detector for detecting these pressure, temperature, humidity, etc. is provided in the SV meter unit, and these detection signals are guided to the control device and the calculation section in the operation panel 60, where they are input to a predetermined value. (However, these detectors are omitted in FIG. 1). In addition, although natural numbers are generally selected as the reference values Q ₁ to _{Q 4} , the rated flow rate of each SV meter is not necessarily based on natural numbers, and the reference flow rate may be determined by combining several SV meters. Because it is something that we make,
The actual reference flow rate determined by the selection of the SV meter does not necessarily match Q ₁ to _{Q 4} shown in the diagram, and some deviation will occur, so in that case,
Add corrections to the reference value based on the gas pressure, temperature, humidity, etc. at that time, convert it back to a reference value that corresponds to the actual flow rate value, and then compare this converted value with the detection signal from the test object. Make it.

As is clear from the above description, according to the present invention, a gas flowmeter can be tested quickly and accurately with a simple configuration and operation.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a gas flow meter testing device according to the present invention, and FIG. 2 is a diagram showing an example of a reference characteristic curve used in implementing the present invention. 10... Vacuum pump, 20... SV meter unit, 24 ₁ to 24n... SV meter, 30... Test object, 40... Filter, 50... Piston cylinder, 60... Control device and operation panel, 70
...piston cylinder.

Claims (1)

[Claims] 1. An SV meter unit divided into front and rear chambers by a partition wall in which a large number of sonic nozzles are arranged to be selectively openable and closable, and a cylindrical filter that filters and sucks air into the front chamber upstream of the SV meter unit. Attachment/detachment means for removably and testably attaching a gas flowmeter under test between the filter and the front chamber of the SV meter unit on the axis of the filter, and the filter, the gas flowmeter under test, and the SV meter unit. ,
and a tester main body consisting of a negative pressure source such as a vacuum pump in a fluid path, a control device that selects the sonic nozzle and operates the gas flowmeter to be tested, and Compare the reference value stored in advance for each test flow rate of the test gas flowmeter with the flow rate value of the gas flowmeter under test obtained by converting the flow rate value of the selected sonic nozzle into each test flow rate value. A test device for a gas flow meter, comprising a calculation display section for determining and displaying pass/fail.