JPH11153507A - Leak detector - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a leak detector capable of effectively improving a problem that the sensitivity is reduced when the distance between an actual leak portion and a sniffer probe is increased. SOLUTION: An orifice 1 provided in a sub exhaust system passage 13 is provided.
2, the suction amount of the sniffer probe 3 is adjusted, so that the distance sensitivity and the background level can be set freely. By adjusting the suction amount of the capillary 9, the detection sensitivity and the leak detector can be adjusted. The pressure of the test port 11 of the main body 4 can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detector suitably used for performing a leak test by a so-called sniffer method.

[0002]

2. Description of the Related Art Conventionally, as this kind of leak detector,
The one shown in FIG. 2 is known. That is, this leak detector is a sniffer probe 3 for sucking a probe gas 2 such as helium leaking from the device under test 1.
A leak detector main body 4 for detecting the presence of the probe gas 2, a gas guide system 5 for communicating the sniffer probe 3 with the leak detector main body 4, and a series connected to the gas guide system 5. An exhaust system 8 for evacuating the gas guide system 5 using two-stage vacuum pumps 6, 7 and the like, and cooperating with the vacuum pumps 6, 7 provided in the gas guide system 5. And a capillary 9 which operates to maintain the inside of the gas guide system in a high vacuum state.

However, this kind of leak detector body 4
Is provided with a gas analysis tube and the like.
If the pressure of the test port 11 connected to is not maintained at a high vacuum, normal gas detection performance cannot be exhibited. Therefore, the capillary 9 having an extremely narrow gas passage is connected to the sniffer probe 3,
The inside of the gas guide system path 5 can be maintained in a high vacuum state.

[0004]

However, if the capillary 9 having a large flow path resistance is incorporated in the sniffer probe 3, the flow rate of the gas to be sucked is reduced, so that it is difficult to improve the detection accuracy. That is, in such a device, when the distance between the tip of the sniffer probe 3 and the actual leak location in the detection target 1 increases, the absolute amount of the probe gas that can be sucked decreases drastically.
There is a problem that the sensitivity is greatly reduced. Further, a capillary having a mechanically large flow path resistance has a disadvantage that clogging or the like is easily caused.

[0005]

In order to solve the above problems, the present invention takes the following measures. That is, the leak detector according to the present invention is a sniffer probe for sucking probe gas leaking from the test object, a leak detector main body for detecting the presence of the probe gas, and the sniffer probe in the leak detector main body. A gas guide system for communication, a main exhaust system for evacuating the gas guide system using a plurality of vacuum pumps connected to the gas guide system and arranged in series, and a main exhaust system A capillary which is interposed in the gas guide path located closer to the sniffer probe than the path and maintains the leak detector main body side of the gas guide path in a high vacuum state in cooperation with the vacuum pump; and a capillary. The intermediate portion of the gas guide passage located closer to the sniffer probe is connected to the intermediate exhaust portion located between the vacuum pumps in the main exhaust passage. A secondary exhaust system path, and characterized by being provided with an orifice which is interposed in the secondary exhaust pathway.

[0006] With such a configuration, a part of the gas sucked from the sniffer probe is exhausted through the sub-exhaust passage, so that the sniffer probe has a much larger suction amount than the conventional one. Even if it is increased, it is possible to maintain the leak detector main body side in the gas guide system at a high vacuum. Therefore, even when the distance between the actual leak location and the sniffer probe is relatively large, the possibility that the leaked probe gas is sucked into the sniffer probe is increased, and a decrease in sensitivity can be prevented. That is, according to the configuration of the present invention, it is possible to freely set the distance sensitivity and the background level by adjusting the suction amount of the sniffer probe with the orifice provided in the sub-exhaust passage, thereby enabling the capillary to be set. By adjusting the suction amount, the detection sensitivity and the test port pressure of the leak detector can be set. In this case, since the downstream of the capillary is exhausted by the main exhaust system, the capillary does not need to have an extremely large flow path resistance, and clogging can be effectively prevented.

As the probe gas, an inert gas such as helium is used. Of course, the vacuum pumps arranged in series in a plurality of stages are not necessarily limited to those housed in a separate housing. A preferred example of such a vacuum pump is a two-stage diaphragm vacuum pump. The orifice provided in the sub-exhaust passage is not limited to a fixed orifice, and may be one in which the suction amount can be changed by a needle valve. Further, the orifice suction amount may be confirmed by a flow meter or the like.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. The leak detector of this embodiment is different from the conventional leak detector in that the position of the capillary 9 is changed and a sub-exhaust passage 13 having a new orifice 12 is newly provided. In the corresponding part,
The same reference numerals are given and the description is omitted.

That is, the leak detector has a sniffer probe 3 for sucking in a probe gas 2 such as helium leaking from the test object 1 and an analysis tube for detecting the presence of the probe gas 2. The leak detector main body 4, a gas guide system 5 for communicating the sniffer probe 3 with the leak detector main body 4, and a two-stage diaphragm vacuum pump 6, 7 connected to the gas guide system 5. A main exhaust system 8 for evacuating the gas guide system 5 and the vacuum pumps 6 and 7 provided in the gas guide system 5 at a position closer to the sniffer probe 3 than the main exhaust system 8. In cooperation with the gas guide system 5
A capillary 9 for maintaining the leak detector body 4 side in a high vacuum state, and an intermediate portion 5a of the gas guide system 5 located on the sniffer probe 3 side of the capillary 9 with the vacuum pump 6 in the main exhaust system 8, A sub-exhaust passage 13 connected to the intermediate exhaust portion 8a located between the sub-exhaust passages 7 and an orifice 12 provided in the sub-exhaust passage 13 are provided.
In addition, 14 is a filter and 15 is an on-off valve. The on-off valve 15 is for closing the gas guide system 5 until the leak detector main body 4 side with respect to the capillary 9 is brought into a constant high vacuum state by the exhaust action of the vacuum pumps 6 and 7.

With such a configuration, the distance sensitivity and the background level can be freely set by adjusting the amount of suction of the sniffer probe 3 by the orifice 12 provided in the auxiliary exhaust passage 13. Becomes possible,
By adjusting the suction amount of the capillary 9, the detection sensitivity and the pressure of the test port 11 of the leak detector main body 4 can be set. By the way, in the case of the present embodiment, the suction amount of the sniffer probe 3 is set to be about 10 times or more as compared with the conventional capillary type.
As a result, the decrease in sensitivity due to the distance between the actual leak portion of the test object 1 and the sniffer probe 3 was significantly improved. For example, when the distance between the conventional leak portion and the sniffer probe 3 is 3 mm, the sensitivity is 100%, and when the distance is 20 mm, the sensitivity is 10%.
% In the present embodiment, even if the distance is 20 mm, it is 100%.
% Could be obtained. In addition, it is possible to prevent the inside of the capillary 9 from having an extremely small diameter channel structure, and to effectively prevent clogging.

The vacuum pump is not limited to the diaphragm type, but may be, for example, a scroll type.

[0012]

According to the present invention having the above-described structure, the amount of sniffer probe suction can be increased without difficulty, and the sensitivity decreases as the distance between the actual leak point and the sniffer probe increases. It is possible to provide a leak detector that can effectively improve the problem of performing the leak detection. Further, according to the present invention, clogging of the capillaries can be eliminated and maintenance and inspection can be facilitated.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional example and corresponding to FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Test object 2 ... Probe gas 3 ... Sniffer probe 4 ... Leak detector main body 5 ... Gas guide system 6 ... Vacuum pump 7 ... Vacuum pump 8 ... Main exhaust system 9 ... Capillary 12 ... Orifice 13 ... Sub exhaust system

Claims (1)

[Claims] 1. A sniffer probe for sucking a probe gas leaking from an object to be inspected, a leak detector body for detecting the presence of the probe gas, and a gas for communicating the sniffer probe with the leak detector body. A guide system, a main exhaust system for evacuating the gas guide system using a plurality of stages of vacuum pumps connected to the gas guide system, and a sniffer probe than the main exhaust system. A capillary which is provided in the middle of the gas guide system located on the side and which maintains the leak detector main body side of the gas guide system in a high vacuum state in cooperation with the vacuum pump; and a sniffer probe side relative to the capillary. And a sub-exhaust system connecting an intermediate portion of the gas guide system located at a position between the vacuum pumps in the main exhaust system with the sub-exhaust system. Leak detector characterized by comprising comprises an orifice which is interposed.