Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
1998-10-15
2001-04-10
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
Reexamination Certificate
active
06212942
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims priority from Japanese patent application No. Hei 9-288943, filed Oct. 21, 1997, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a leakage inspection method and an apparatus for detecting internal leakage of a fluid flowing in a leakage flow path, in equipment having a partition therein and a normal flow path separated by this partition, when the leakage flow path which bypasses the normal flow path is caused. Particularly, the present invention is suitable for an inspection of internal leakage of a heat exchanger such as an evaporator for an air-conditioning apparatus.
2. Description of Related Art
Generally, in equipment having a flow path inside in which a fluid flows, leakage measurements are made by detecting leakage from the inside to the outside of the object (equipment) to be checked, by applying a constant pressure or a constant flow rate of an inspection fluid or a pressure wave to the object. Various kinds of detecting methods, such as a flow rate measuring method, a pressure drop measuring method, etc., are available.
However, in equipment, for instance a heat exchanger like an evaporator, inside of which a partition is formed to separate the equipment interior to define a normal flow path, if a hole exists on the partition, a leakage flow path via the hole would be formed, bypassing the normal flow path and joining the original flow path (normal flow path). In this case, a leakage signal is mixed with a signal of the normal flow path. A conventional method, therefore, is not able to separately detect the leakage signal alone.
SUMMARY OF THE INVENTION
The present invention is made in light of the foregoing problems, and it is an object of the present invention to provide a leakage inspection method and apparatus which detects internal leakage of a fluid flowing in a leakage flow path of an equipment having a partition therein to define a normal flow path, when the leakage flow path bypassing the normal flow path via a hole or the like.
The present inventor et al, taking note of a difference in the length and configuration of the normal flow path and the bypassed leakage flow path, could achieve the above-described object by measuring a transient physical quantity of an inspection fluid or a pressure wave at the outlet when the pressure wave or the inspection fluid is led in from the inlet, then separating the leakage from the normal flow to thereby detect a leakage quantity and a leakage position (position of the leakage flow path).
According to a leakage inspection method of the present invention, a leakage inspection method for detecting an internal leakage of a fluid flowing in a leakage flow path bypassing a normal flow path, having an inlet and an outlet, in an equipment having a partition therein and having the normal flow path separated by the partition, includes the steps of:
applying a pressure wave to the normal flow path from the inlet;
detecting first physical quantity of the pressure wave, which passes through the normal flow path, at the outlet;
detecting second physical quantity of the pressure wave, which passes through the leakage flow path when the internal leakage occurs, at the outlet; and
determining the internal leakage from a difference between the first physical quantity and the second physical quantity.
According to the present invention, it is possible to easily detect occurrence of the leakage flow path, that is, internal leakage, by detecting a difference in the physical quantities, caused by a difference in the length and configuration of both flow paths, of the pressure waves passing through the paths.
The physical quantity of the pressure waves may be determined by the transfer time during which the pressure wave passed through each of the flow paths. Accordingly, there occurs a difference in each transfer time according to the difference in the length of flow paths between both flow paths, thereby allowing easy detection of occurrence of internal leakage.
Specifically, it is possible to detect, by using a pressure transducer (pressure sensor or the like), a pressure variation resulting from a difference in the transfer time of the pressure wave between the normal flow path and the leakage flow path.
The detection of the transfer time may be conducted by measuring the pressure wave as a sound wave by means of a microphone, thereby detecting a difference in the transfer time of the sound wave. In this case, the microphone used as a quick-response detecting means capable of measuring a wide dynamic range can detect even a very little quantity of leakage.
According to a leakage inspection apparatus of the present invention, it includes;
pressure wave generating means for applying a pressure wave to the normal flow path from the inlet;
detecting means for detecting first transfer time of the pressure wave, which passes through the normal flow path, at the outlet, and for detecting second transfer time of the pressure wave, which passes through the leakage flow path when the internal leakage occurs, at the outlet; and
internal leakage determining means for determining the internal leakage from a difference between the first transfer time and the second transfer time.
Accordingly, it is possible to easily detect occurrence of the leakage flow path, that is, internal leakage, by detecting a difference in the physical quantities, caused by a difference in the length and configuration of both flow paths, of the pressure waves passing through the paths.
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Hara Hideaki
Iriyama Shoji
Denso Corporation
Harness Dickey & Pierce PLC
Politzer Jay L.
Williams Hezron
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