JP3041953B2 - Leak detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detector used for performing a sealing test, a sealing test, and the like.

[Prior Art] A helium (He) leak detector is one of the powerful means for performing a sealing test or a sealing test. This apparatus includes an exhaust system that connects the device under test to a roughing pump, and an analysis tube that is selectively connected via a test valve in the exhaust system. Then, after evacuating the test object to a predetermined vacuum degree, open the test valve and allow the gas containing He leaked from the test object to flow into the analysis tube, select only He among them, and measure the amount. As a result, the amount of leakage from the test object can be measured indirectly.

[Problems to be Solved by the Invention] However, the analysis tube cannot be operated unless it is vacuum. Therefore, when the degree of vacuum of the exhaust system does not reach a predetermined value, that is, when the leak amount of the device under test is large, the test valve cannot be opened, which causes a problem that the measurement becomes impossible.

Therefore, conventionally, in order to cope with such gross leakage, a throttle valve is interposed in a part of the flow path from the test valve to the analysis tube, and He flowing into the analysis tube at the throttle valve.
In some cases, measurement is possible by regulating the amount. However, in such a case, the opening of the throttle valve must be made very small in anticipation of the maximum leakage time (that is, equivalent to the atmospheric pressure), which causes a problem that production becomes extremely difficult. Occurs.

The present invention has been made in view of such a problem, and when used in combination with the above-mentioned He leak detector or the like, a leak capable of easily measuring a leak amount during gross leak. It aims to provide detectors.

Means for Solving the Problems The present invention is configured as follows, focusing on the fact that the pressure of the exhaust system can be uniquely associated with the exhaust flow rate using the exhaust speed as a parameter according to the characteristics of the pump. It was done.

That is, the present invention includes an exhaust system that connects a device under test to a roughing pump, and an analysis tube that is connected in the middle of the exhaust system, and a leak that measures a leak amount from the device under test using the analysis tube. A pressure detecting means provided in the exhaust system, a flow rate determining means for determining an exhaust flow rate based on the characteristics of the roughing pump from a pressure detected by the pressure detecting means, Display means for outputting the output exhaust flow rate.

[Operation] With such a configuration, the flow rate of exhaust gas when the display on the display means has settled down to a steady state to some extent can be regarded as the leak amount from the test object. Further, even while the display on the display means fluctuates, the amount of leakage from the test object can be predicted at an early stage through follow-up observation.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a conventional He leak detector integrated with a leak detector according to the present embodiment. The conventional He leak detector includes an exhaust system L for connecting the device under test 1 to the roughing pump 2, and an analysis system selectively connected to the exhaust system L in the middle of the exhaust system L (test port) via a test valve 3a. And a tube 3. After evacuating the device under test 1 to a predetermined degree of vacuum, the test valve 3a is opened and gas containing He leaked from the device under test 1 flows into the analysis tube 3, and only He is selected in the analysis tube 3. Then, by measuring the amount, the amount of leakage from the test object 1 can be indirectly measured. Reference numeral 4 denotes a vacuum gauge (Pirani vacuum gauge, quartz vacuum gauge, etc.) used for detecting the timing of evacuation / end of evacuation, and 9 denotes a roughing valve. Also, 5
Is a microcomputer which controls all operations and data processing of the He leak detector.
5b and an interface 5c (the signal system is omitted).

In such a configuration, in this embodiment, the vacuum gauge 4 is connected to the microcomputer 5 through an A / D converter 6.
To form the pressure detecting means 7 by connecting
A function of flow rate determining means for calculating the exhaust flow rate Q based on the characteristics of the roughing pump 2 from the pressure P detected by the microcomputer 5 itself is added. The display means 8 for outputting the determined exhaust flow rate Q is provided by the microcomputer.
Connected to the data 5.

The pressure detecting means 7 converts the data of the degree of vacuum detected by the vacuum gauge 4 into analog data into digital data by the A / D converter 6 and thereafter takes it into the processor 5a, where the degree of vacuum-pressure conversion is performed. I have to. The microcomputer 5 is
In order to exhibit the function as flow rate determination means,
The pressure (P) -pumping speed (S) characteristic characteristic of the roughing pump 2 as shown in the figure is measured, stored in a table in the memory 5b and stored in another area in the memory 5b. And a control program for the stored processor 5a. The control program retrieves the exhaust speed S corresponding to the pressure P detected by the pressure detecting means 7 from the table into the processor 5a, and calculates the pressure P × the exhaust speed S in the processor 5a, thereby obtaining the exhaust flow rate Q. And outputs the exhaust flow rate Q to the output port of the interface 5c. The display means 8 can display data on the exhaust flow rate Q output from the microcomputer 5 in a tabular form or a graph in real time.

With such a configuration, even when the device under test 1 generates gross leakage and the test valve 3a cannot be opened, the display means 8 displays the He flowing through the exhaust system L. Since the flow rate of the gas containing the gas is displayed, by observing the display and reading the exhaust gas flow Q when it has settled down to a certain steady state, it can be regarded as the leak amount from the test object 1. . Further, even while the display on the display means 8 is fluctuating, the amount of leak from the test object 1 can be predicted at an early stage through follow-up observation. For this reason,
Compared with the conventional He leak detector, this detector can quantitatively and more specifically grasp the situation at the time of gross leak occurrence, and can use the measured leak amount as objective information for information exchange etc. Can also be used effectively. And
Gross leak can be dealt with by the same process as the usual leak amount measurement. In addition, the vacuum gauge 4 is conventionally provided with the He leak detector, and is provided with a micro computer.
The data 5 can be easily added even if it is conventionally attached or not attached. For this reason, there is no need for labor and almost no increase in cost, and there is an excellent advantage that the conventional device can be modified and easily adopted.

It should be noted that such a configuration is releasable from a part other than the test object.
If there is a leak, confusion may occur and cause an error, but this is originally intended to easily measure the amount of gross leak, and such a purposeful use is intended. To the extent possible, such errors can be ignored. In addition, it is not always necessary to integrally configure the He leak detector. Further, a table in which the exhaust gas flow rate directly corresponds to the detected pressure may be used. Further, the configuration and the like of the pressure detecting means and the flow rate determining means are not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

[Effect of the Invention] Since the leak detector of the present invention has the above-described configuration, it is possible to easily measure the leak amount when the test object causes gross leak. The effect is obtained.

In addition, the gross leak can be dealt with in the same process as the normal leak amount measurement by a simple method of adding a pressure detecting means and the like to the exhaust system of the conventional apparatus.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, and FIG.
Block diagram showing a state in which the detector is integrated with the detector,
FIG. 2 is a graph showing pressure-evacuation speed data. DESCRIPTION OF SYMBOLS 1 ... Test object, 2 ... Roughing pump 3 ... Analysis tube, 3a ... Test valve 4 ... Vacuum gauge 5 ... Flow rate judgment means (microcomputer) 5a ... Processor, 5b ... Memory 5c Interface 6 A / D converter 7 Pressure detecting means 8 Display means 9 Roughing valve L Exhaust system P Pressure Q Exhaust Flow rate, S: Pumping speed

Claims (1)

(57) [Claims] 1. A leak detector comprising: an exhaust system for connecting a device under test to a roughing pump; and an analysis tube connected in the middle of the exhaust system, wherein a leak amount from the device under test is measured by the analysis tube. , A pressure detecting means provided in the middle of the exhaust system, a flow rate determining means for determining an exhaust flow rate based on the characteristics of the roughing pump from a pressure detected by the pressure detecting means, and a flow rate determining means for determining the exhaust flow rate. A display means for outputting a flow rate of the exhaust gas.