JPH04204341A - Leak detector - Google Patents

Abstract

PURPOSE:To conveniently measure the amount of leak during gross leak by indexing exhaust flow rate from pressure detected by a pressure detecting means provided on the way of an exhaust system in accordance with the property of a roughing vacuum pump. CONSTITUTION:A pressure detecting means 7 gives A/D conversion 6 to vacuum data detected by a vacuum gauge 4 which is fetched into a processor 5a and performs vacuum-pressure conversion. A microcomputer 5 has data for which pressure P-exhaust velocity S property specific for a roughing vacuum pump 2 is measured and stored in a memory 5b in a table form. A control program fetches the velocity S corresponding to the pressure P detected 7 out of this table, finds the pressure P X the velocity S = exhaust flow rate Q in the processor 5a and outputs it to an interface 5c. A display means 8 displays data related to the flow rate Q output from the microcomputer 5. If the display is observed even when a test valve 3a is in unopened condition and the flow rate Q is read when it is settled in almost stable condition, the flow rate Q can be defined as the amount of leak from a specimen 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a leak detector used in sealing inspections, sealing inspections, and the like.

[Prior Art] A helium (He) leak detector is one of the effective means for performing a sealing inspection or sealing inspection.

This apparatus includes an exhaust system that connects the test object to a roughing pump, and an analysis tube that is selectively connected to the exhaust system via a test valve. Then, after evacuating the test object to a predetermined degree of vacuum, the test valve is opened and the gas containing He leaked from the test object flows into the analysis tube.
By selecting only He among these and measuring its amount, it is possible to indirectly measure the amount of leakage from the test object.

[Problems to be Solved by the Invention] However, the analysis tube cannot be operated unless it is in a vacuum. Therefore, if the degree of vacuum in the exhaust system does not reach the specified value, that is, if the amount of leakage from the test object is large,
This results in the inconvenience that the test valve cannot be opened and measurement becomes impossible.

Therefore, in order to deal with such gross leaks, conventionally, a throttle valve is interposed in a part of the flow path from the test valve to the analysis tube, and this throttle valve prevents the He flowing into the analysis tube.
In some cases, measurement is possible by regulating the amount. However, in this type of valve, the opening of the throttle valve must be made very small assuming maximum leakage (that is, equivalent to atmospheric pressure), which causes problems such as making manufacturing extremely difficult.

The present invention has been made with attention to such problems, and an object of the present invention is to provide a leak detector that can easily measure the leak amount at the time of gross leak when used in combination with the above-mentioned He leak detector or the like. It is an object.

[Means for Solving the Problems] The present invention is configured as follows, focusing on the fact that the pressure in the exhaust system can be uniquely related to the exhaust flow rate using the pumping speed as a parameter, depending on the characteristics of the pump. It is.

That is, the leak detector of the present invention includes a pressure detection means provided in the middle of an exhaust system that connects the test object to the roughing pump, and a pressure detection means based on the characteristics of the roughing pump based on the pressure detected by the pressure detection means. It is characterized by comprising a flow rate determination means for determining the exhaust flow rate, and a display means for outputting the exhaust flow rate determined by the flow rate determination means.

[Operation] With such a configuration, the exhaust flow rate when the display on the display device has settled down to a certain steady state can be regarded as the amount of leakage from the test object. Further, even while the display on the display means is changing, it is possible to predict the amount of leakage from the test object at an early stage through progress observation.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a conventional He leak detector in which a leak detector according to this embodiment is integrated. The conventional He leak detector includes an exhaust system that connects the test object 1 to a roughing pump 2, and an analysis tube 3 that is selectively connected to the middle of this exhaust system (test port) via a test valve 3a. It is equipped with After the test object 1 is evacuated to a predetermined degree of vacuum, the test valve 3a is opened to allow the gas containing He leaked from the test object 1 to flow into the analysis tube 3, and only He is selected in the analysis tube 3. death,
By measuring the amount, the amount of leakage from the test object 1 can be indirectly measured. 4 is a vacuum gauge (Villany vacuum gauge, crystal vacuum gauge, etc.) used to detect the timing of exhaust/end of exhaust, and 9 is a roughing valve. A microcomputer 5 controls all operations and data processing of the He leak detector, and is composed of a bromo-fusa 5a, a memory 5b, and an interface 5C (the signal system is omitted).

In this embodiment, the vacuum gauge 4 is connected to the microcomputer 5 via the A/D converter 6.
The pressure detection means 7 is configured by connecting the
The microcomputer 5 itself has a function of a flow rate determination means for determining the exhaust flow rate Q based on the characteristics of the roughing pump 2 from the detected pressure P, and furthermore, the function of a flow rate determination means for determining the exhaust flow rate Q based on the characteristics of the roughing pump 2 is added to the microcomputer 5 itself. A display means 8 for outputting the flow rate Q is connected to the microcomputer 5.

The pressure detection means 7 converts the degree of vacuum data detected in analog form by the vacuum gauge 4 into digital data using the A/D converter 6, and then inputs the data into the processor 5a, where the degree of vacuum and pressure are converted.

In order to function as a flow rate determining means, the microcomputer 5 measures the pressure (P)-pumping speed (S) characteristic characteristic of the roughing pump 2 as shown in FIG. 2 in advance and stores it in the memory 5b. It has data stored in a table and a control program for the processor 5a stored in another area within the memory 5b. The control program determines the pumping speed S corresponding to the pressure P detected by the pressure detection means 7.
is extracted from the table into the processor 5a, the processor 5a calculates the pressure px and the exhaust speed S to obtain the exhaust flow rate Q, and performs a routine at regular intervals of outputting the exhaust flow rate Q to the output port of the interface 5C. You are supposed to stand up and do it. The display means 8 is capable of displaying data related to the exhaust flow rate Q outputted from the microcomputer 5 in real time in a tabular format or a graph.

With such a configuration, even when the test valve 3a cannot be opened because the test object 1 generates a gross leak, the display means 8 shows the He flowing through the exhaust system. Since the flow rate of the contained gas is displayed, by observing the display and reading the exhaust flow rate Q when it has stabilized to a certain degree, it can be regarded as the amount of leakage from the test object 1. Further, even while the display on the display means 8 is changing, it is possible to predict the amount of leakage from the test object 1 at an early stage through progress observation. Therefore, compared to conventional He leak detectors, this one can quantitatively and more specifically grasp the situation when a gross leak occurs, and can also be used to exchange information by using the measured leak amount as objective information. It becomes possible to use it effectively. Furthermore, the vacuum gauge 4 has conventionally been attached to the He leak detector, and the microcomputer 5 can also be attached to the conventional one, or even if it is not attached, it can be easily added. Therefore, it does not require much effort, hardly increases cost, and has the excellent advantage that it can be easily adopted by modifying conventional equipment.

Note that this configuration may cause confusion and errors if there is a leak from a part other than the test object, but the original purpose of this configuration is to easily measure the amount of gross leakage. This error can be ignored as long as it is used for such a purposeful purpose. Furthermore, it is not necessarily necessary to configure it integrally with the He leak detector. It is also possible to use a table in which the exhaust flow rate corresponds directly to the detected pressure.

Further, the configurations of the pressure detection means and the flow rate determination means are not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

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

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram showing a state in which it is integrated into a conventional He leak detector, and FIG. 2 is a graph showing pressure-exhaust speed data. 1... Test object 2... Roughing pump 3...
・Analysis tube 3a...Test valve 4...
Vacuum gauge 5...Flow rate determination means (microcomputer) 5a.
...Processor 5b...Memory 5C...Interface

Claims (1)

[Claims] a pressure detection means provided in the middle of an exhaust system connecting the test object to the roughing pump; a flow rate determination means for determining the exhaust flow rate based on the characteristics of the roughing pump from the pressure detected by the pressure detection means; A leak detector comprising display means for outputting the exhaust flow rate determined by the flow rate determination means.