JPH0129541Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a testing device for gas flowmeters, more specifically, a testing device for testing the characteristics of gas flowmeters that output electrical signals corresponding to air flow rates. The electrical output signal of the gas flowmeter under test is compared with a reference value, and the result of the comparison is used to determine whether the gas flowmeter under test passes or fails. The aim is to make the test easier and faster, and to improve test accuracy.

FIG. 1 is a configuration diagram for explaining an embodiment of the test apparatus according to the present invention, in which 10 is a vacuum pump, 20 is a reference test flow rate setting device, 30 is a gas flowmeter as a test object, 40 is a cylindrical filter, 50 is a piston cylinder, and 60 is a control and judgment display device. When the test specimen 30 is set at the position shown in the figure and the vacuum pump 10 is driven, the outside air flows through the filter 40, the gas flow meter 30, It flows towards the vacuum pump 10 through the reference flow rate setting device 20 .
On the panel surface of the control and judgment display device 60, there are operating sections including a clamp button 61, an unclamp button 62, an inspection start button 63, an inspection stop button 64, etc., and various flow rates (No. ₁ to No. ₄ in the illustrated example). When the clamp button 61 is pressed, the piston of the piston cylinder 50 moves downward and the pistons of the other piston cylinders 70 move to the right in the figure.
When the unclamp button 62 is pressed, the piston of the piston cylinder 50 moves upward and the piston of the piston cylinder 70 returns to the left. Now, with the piston rising upwards, place the test object 30 in the position shown and press the clamp button 61, the piston of the piston cylinder 50 will move downward, fixing the test object 30 in a predetermined position. At the same time, the piston of the piston cylinder 70 moves to the right and the control and judgment display device 6
Connect the connector 66 provided at the tip of the lead wire 65 from 0 to the electrical output terminal section 31 of the test object 30.
Connect to. The standard test flow rate setting device 20 consists of SV meters 24 ₁ to 24 _o , etc., and a test start button 6
When you press 3, the reference test flow rate setting device 20
The SV meters 24 ₁ to 24 _o are opened and closed in accordance with a predetermined sequence built in in advance, and in the illustrated example, four types of reference flow rates No. ₁ to _{No. 4} are sequentially selected, and the test object 30 for each reference flow rate is selected. The measured values of are compared by the arithmetic unit in the control and judgment display device 60. That is, the reference test flow rate setting device 2
0 is divided into two by a partition wall 21 into a front chamber 22 and a rear chamber 23.
SV meters 24 ₁ to 24 _o are provided, and these SV meters 24 ₁ to 24 _o are opened and closed according to a sequence built into the control section of the control and judgment display device 60. 25 ₁ to 25 _o selectively open and close, test object 3
A reference flow rate for 0 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 voltage,
The curves are standard characteristic curves, are the allowable upper limit curves, are the allowable lower limit curves, Q ₁ to _{Q 4} are test flow rates, and each test flow rate is indicated by the display lamp No. ₁ of the control and judgment display device 60.
~ No. ₄ corresponds to each flow rate Q ₁ ~ _{Q 4}
The reference values E ₁ to _{E 4} are stored in advance in the memory within the control and judgment display device 60. Now, when you return to the original state and press the test start button 63, the SV meters 24 ₁ to 24 _o are opened and closed according to the sequence preset in the control and judgment display device 60, and the reference flow rate Q ₁ - Q ₄ are created sequentially, and the output signal of the test object 30 for each flow rate Q ₁ - _{Q 4} is compared with a reference value (curve) stored in advance in the memory in the control and judgment display device 60, and each of the If the comparison result falls between the upper and lower tolerance curves (within the shaded range)
It is displayed on the GO indicator lights No. ₁ to _{No. 4} , and when it is outside the allowable range, it is displayed on the NG 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 standard test flow rate setting device, and these detection signals are guided to the calculation section in the control and judgment display device 60, where the , a predetermined correction is applied (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. Since 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, there will be some deviation. Add corrections to the 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 compare this converted value with the detection signal from the test object. .

In the above-described test apparatus, if turbulence or the like exists in the fluid flowing inside the gas flow meter 30 under test, this will cause a measurement error. The first straightening tube 80 and the second straightening tube 90 are provided to eliminate such turbulence, and the inner diameter of these straightening tubes 80 and 90 is the same as that of the gas flowmeter 3 under test.
0, and so that when the gas flowmeter under test 30 is placed on the rectifier cylinder 80, the gas flowmeter under test 30 is accurately aligned with the rectifier cylinders 80 and 90. , positioning means such as a pin is provided on the upper surface of the rectifying cylinder 80. In addition, a large number of pores are provided approximately evenly in the upper peripheral wall 90a of the rectifier cylinder 90, and the outside air introduced through the filter 40 is introduced into the cylinder body 90 with as little turbulence as possible. That's what I do.

As described above, according to the present invention, it is possible to quickly and easily set the gas flowmeter under test in the test equipment, and moreover, it is possible to accurately test the gas flowmeter without causing turbulence or the like in the gas flowmeter under test. I can do it.

[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...Reference test flow rate setting device, 24 ₁ to 24 _o ...SV meter, 30...
Gas flowmeter under test, 40...Filter, 50...
...Piston cylinder, 60...Control and judgment display device, 70...Piston cylinder, 80,9
0... Rectifier tube.

Claims (1)

[Scope of utility model registration request] A cylindrical filter for introducing outside air whose peripheral wall is constituted by a filter, a test gas flow meter installation part formed in a fluid path following the filter, and a test gas flow meter installation part formed in the fluid path following the installation part. a reference flow rate setting section provided therein; and a negative pressure source disposed downstream of the reference flow rate setting section; and a gas flowmeter under test is disposed in the gas flowmeter under test installation section; , in a test device for a gas flowmeter that tests the gas flowmeter under test by setting a test flow rate in the reference flow rate setting section, the gas flowmeter under test is disposed downstream of the gas flowmeter under test installation section; a first rectifier cylinder on which a gas flowmeter is mounted and which rectifies the gas that has passed through the gas flowmeter under test; a second rectifier cylinder that rectifies the gas introduced into the meter;
a control device for moving a rectifying tube coaxially with the filter within the cylindrical filter; Pores for introducing the gas into the rectifying cylinder are provided approximately evenly, and the second rectifying cylinder is moved by the control device so that the flow rate of the gas to be tested is adjusted between the second rectifying cylinder and the first rectifying cylinder. 1. A test device for a gas flow meter, characterized in that when the meter is fixed, an electrical output terminal of the gas flow meter under test is connected to a judgment display unit.