JPS58179330A - Leak detecting device - Google Patents

Abstract

PURPOSE:To obtain a net gas leakage quantity easily and exactly, by automatically subtracting an ineffective gas leakage quantity from a measured gas leakage quantity, in a leakage detecting device for detecting whether a minute hole exists or not on a vessel wall, and its size, etc. by a gas leakage quantity. CONSTITUTION:For instance, when helium gas is blown from the outside of a vessel whose inside is kept in a vacuum, if a minute hole exists on the vessel wall, helium gas goes into the vessel through its minute hole. A measuring part 1 measures gas passing through the minute hole, namely, quantity of leakage gas. In this measuring part 1, an apparent gas leakage quantity which adds a gas leakage quantity (ineffective gas leakage quantity) existing from before starting a measuring test, in the vessel and the measuring part, to a gas leakage quantity (net gas leakage quantity) passing through the vessel wall as soon as the measuring test is started is measured. Subsequently, the ineffective gas leakage quantity is subtracted from the apparent gas leakage quantity by calculating parts 2, 3, so that the net gas leakage quantity can be obtained automatically. Subsequently, an exhaust characteristic is measured as to the gas leakage quantity, and the leakage quantity in each time is stored as Q=Qt by making the passing time corresponding to a leakage quantity Q. When an apparent gas leakage quantity in case when some measuring test ends is Q' at time t1, an ineffective gas leakage quantity after that time t1 is derived from the relational expression.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a leak detection device that detects the presence or absence of micropores in a container wall, their size, etc. based on the amount of gas leakage.

In a closed container wall where the presence of micropores is not allowed, a leak detector is generally used to detect the presence or absence and size of micropores. by the way,
In conventional leak detection devices, in order to prevent the indication value of the gas leak amount measurement meter from becoming 1 zero due to residual gas after the previous gas leak amount measurement test, the indication value of the gas leak amount measurement meter is set to ``zero'' every measurement test. The correction is performed manually. In other words, in conventional gas leakage measurement tests, the indicated value is corrected to "zero" to prevent the invalid gas leakage amount from being included in the measurement data, while at the same time the indicated value is corrected to "zero" so that the net gas leakage amount is not included. I have to. However, for each measurement test, the indicated value is
Manually correcting to zero is extremely troublesome and lacks accuracy.

In view of the above, an object of the present invention is to provide a leak detection device that can easily and accurately obtain a net gas leak amount by automatically subtracting an ineffective gas leak amount from a measured gas leak amount.

In order to achieve the above object, the present invention provides an apparatus for detecting the presence or absence of micropores in a container wall, their size, etc. based on the amount of gas leakage, which includes a first means for measuring the amount of gas leakage, and a first means for measuring the amount of gas leakage; a second means for storing or calculating the amount of invalid gas leak from the measurement data from the means; and a third means for subtracting the amount of gas and the amount of leakage to obtain the net amount of gas leakage.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 is a block circuit diagram of one embodiment of the present invention.

The measurement unit (1) measures the amount of gas leaking depending on the presence or absence and size of micropores in the container wall.

This measurement method will be briefly explained. For example, helium (He 2 ) gas is blown from the outside of a container whose interior is kept in vacuum. If there are micro holes in the container wall, helium gas will enter the container through the micro holes. Measuring part (1
) measures the amount of gas passing through the micropores, that is, the amount of leak gas.

FIG. 2 mainly shows the amount of gas leak measured in the measuring section (1) along the time axis. In Figure 2,
Q+, Q2 and Q3 are the first . Here are the gas leakage curves from the second and third gas leakage measurement tests. By the way, in the measuring section (1),
The apparent gas leak is the sum of the amount of gas leak that passed through the container wall at the same time as the measurement test started (net gas leak amount) and the amount of gas leak that existed in the container or measurement part before the start of the measurement test (ineffective gas leak amount). quantity is measured. In this embodiment, the following 1. Second calculation part (2)
According to (3), the ineffective gas leak amount is subtracted from the apparent gas leak amount to automatically obtain the net gas leak amount.

That is, when the gas remaining in the container or the measuring section is to be evacuated for a new measurement test, the gas is evacuated according to the exhaust characteristic curve shown in FIG.

Since this exhaust characteristic curve changes exponentially, there are two methods for calculating an arbitrary amount of ineffective gas leakage. First, the first method will be explained. That is,
In the first method, the exhaust characteristics as shown in Fig. 3 are measured for the amount of gas leakage, and the amount of leakage at each time is correlated with the elapsed time (1) and the amount of leakage (2).
= Q(t). Now, as shown in Fig. 4, the apparent gas leak amount at the end of a certain measurement test is Q' at time (tl).
The amount of ineffective gas leak after that time (t,) can be determined from the following relational expression.

This is the saturated leakage amount obtained by measuring the characteristics over a long period of time.

Next, the second method will be explained. In the second method,
As shown in FIG. 5, between the end of the test and the start of a new test, the elapsed time (tn) from the end of the test and the amount of leakage (Qn) at that time are memorized,
A regression analysis calculation is performed using the (tn) and (Qn) to estimate the amount of ineffective gas leak at any given time.

Ineffective gas leak amount CQ (t) at this arbitrary time
) can be obtained from the following relational expression.

Q(t)=Q'exp(-)+QBG τ Here, Q', τ, and QBG are the following regression analysis calculation formulas (Thus, if we now calculate the amount of ineffective gas leak using the first method, Fig. 4 The net gas leak amount (Qv) at time (t3) in the new measurement test is obtained by measuring the apparent gas leak amount (Q') in the measuring section (1), while ) at time (1) of the above relational expression (t
3) is substituted to calculate the ineffective gas leak amount (QI), and the apparent value is obtained by subtracting the ineffective gas leak amount (Q+) from the above gas leak amount (Q') in the second calculation section (3).

In this embodiment, after the measurement test is completed, the next measurement test can be started without waiting until the amount of ineffective gas leak becomes almost constant like QBG, so such a measurement test can be repeated. Very suitable in some cases.

FIG. 6 is a block circuit diagram of another embodiment of the invention. In this embodiment, the next measurement test is started when a long time has elapsed after the end of the previous measurement test and the amount of ineffective gas leak reaches a constant QBG. After a considerable period of time has elapsed after the end of the measurement test, the amount of gas leakage measured by the measuring section (1') of this embodiment is as follows: This is the amount of ineffective gas leakage (QI) of QBG.This amount of ineffective gas leakage (Q
I) is stored in three storage units in response to a control signal from the control unit (2').

Therefore, the amount of ineffective gas leakage in the next measurement test will be stored in the storage section (3') before the start of the measurement test. Next, when the measurement test starts, the measurement section (
A signal regarding the apparent gas leak amount is inputted from one of the two, and a signal regarding the invalid gas leak amount is inputted from the memory section (3') to the calculation section (4'). The calculation unit (4') subtracts the invalid gas leak amount from the apparent gas leak amount based on both input signals, and
A signal regarding the net gas leakage amount, which is the result of the subtraction, is sent from the output section.

In this way, in this embodiment, the net amount of gas leak can be detected. FIG. 7 shows the apparent gas leak amount (q<) (Q2') (Q3') for each measurement test on the time axis. Therefore, in this example, each ineffective gas leakage amount (Q]' is calculated before each measurement test starts.
Net gas leakage amount (QV+') (QV2') (QV3') corresponding to BG) (Q2'BG) (Q3'BG)
can be determined accurately.

As explained above, according to the present invention, since it has the above-mentioned configuration, the net gas leak amount can be automatically determined by subtracting the invalid gas leak amount from the measured apparent gas leak amount, Eliminates troublesome measurement operations,
Moreover, effects such as being able to perform accurate measurements are exhibited.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 is a graph showing the gas leak amount curve for each measurement test in the above embodiment on the time axis, and Fig. 3 is a graph of the amount of ineffective gas leak in the exhaust system. FIGS. 4 and 5 are graphs showing the attenuation characteristic curve on the time axis. FIGS. 4 and 5 are graphs of the gas leak amount on the time axis to explain the measurement operation according to the above embodiment. FIG. 6 is a graph showing another embodiment of the present invention. Block circuit diagram, No. 7
The figure is a graph plotting gas leak curves for each measurement test in the above-mentioned embodiment on a time axis. (1) (1')...Measurement section, (2)...First calculation section, (3)...Second calculation section, (2')...Control section, (3
')...Storage section, (4...Arithmetic section Patent applicant Shimadzu Corporation Fig. 5 t, t, t (, [@ g ellipse (t) Fig. 6 Fig. 7

Claims (1)

[Claims] A first means for measuring the amount of gas leak by using a device for detecting the presence or absence of micropores in the container wall and their size based on the amount of gas leak;
a second means for storing or calculating the amount of ineffective gas leak from the measurement data from the means;
and a third means for obtaining a net gas leak amount by subtracting one nok amount of ineffective gas from the second means from the apparent gas leak amount from the above means. .