JP3683756B2 - Leak measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a leak measuring device for detecting a leak of a circuit or the like to be measured based on a movement amount of a piston in a cylinder.
[0002]
[Prior art]
As this kind of leak measuring instrument, the one shown in FIG. 2 is conventionally known. In this conventional leak measuring instrument, a piston holding portion 1 is formed in a cylinder C, and a piston P is slidably held by the piston holding portion 1.
By inserting the piston P into the piston holding portion 1 as described above, the inside of the cylinder C is divided into one pressure chamber 2 and the other pressure chamber 3.
The piston P has a detection hole 4 on its axis. The detection hole 4 is opened only on one pressure chamber 2 side. The pressure receiving area S1 on the one pressure chamber 2 side including the bottom of the detection hole 4 is made equal to the pressure receiving area S2 of the other pressure chamber 3. A sensor element 5 made of a coil is provided at the opening of the detection hole 4 as described above.
[0003]
Further, the detection rod 6 is fixed to the one pressure chamber 2 side, but the detection rod 6 is made smaller than the inner diameter of the detection hole 4 to keep both of them in a non-contact state. . Since the non-contact state is maintained in this way, the pressure in one pressure chamber 2 also acts on the bottom of the detection hole 4. Therefore, as described above, the pressure receiving areas S1 and S2 in both pressure chambers 2 and 3 are equal.
[0004]
The detection rod 6 is provided with a core 7, and the core 7 and the sensor element 5 constitute a differential transformer as a non-contact stroke sensor. The detection rod 6 is electrically connected to a detector 8 provided outside the cylinder C.
In such a differential transformer, the induced voltage changes in accordance with the relative position between the core 7 and the sensor element 5, and the movement of the piston P is detected by detecting the change in the induced voltage with the detector 8. Is detected.
[0005]
Therefore, for example, if one pressure chamber 2 is connected to the pressurizing side (not shown) and the other pressure chamber 3 is connected to the measuring object side, both pressure chambers 2, The pressures in 3 are equal, for the following reason. That is, when the pressure on the one pressure chamber 2 side is increased, the piston P cannot move unless there is a leak on the measurement target side. The fact that the piston P cannot move in this way means that the acting force of the piston P on the one pressure chamber 2 side is balanced with the reaction force on the other pressure chamber 3 side. Moreover, since the pressure receiving areas S1 and S2 of the piston P are equal as described above, when the forces acting on the piston P are balanced as described above, the pressures in both pressure chambers 2 and 3 are also equal.
[0006]
When a leak occurs on the measurement target side, the pressure in the other pressure chamber 3 becomes lower by the amount of the leak. For this reason, the piston P moves in the right direction of the drawing. At this time, an induced voltage corresponding to the amount of movement of the piston P is generated in the differential transformer. This induced voltage is detected by the detector 8, and the movement amount of the piston P, that is, the leakage amount on the measurement target side is measured.
[0007]
[Problems to be solved by the invention]
When the conventional leak measuring instrument as described above is used, first, the pressure on the measurement object side is first guided to the other pressure chamber 3, and then the pressure on one pressure chamber 2 side is increased. To go. However, although the initial pressure is applied also to this one pressure chamber 2, the pressure is made quite low.
In the above state, when the pressure on the measurement target side is high, the piston P moves to the stroke end on the one pressure chamber 2 side. Thereafter, the pressure in the one pressure chamber 2 is increased, but measurement is not possible unless the pressure in the pressure chamber 2 increases to the pressure in the other pressure chamber 3.
That is, this conventional measuring device has a problem that it takes some time until the pressure on the pressure chamber 2 side increases and the amount of leakage can be measured.
An object of the present invention is to provide a leak measuring instrument which can measure immediately after pressure is introduced into one pressure chamber.
[0008]
[Means for Solving the Problems]
The present invention is a piston provided in a cylinder, which divides the inside of the cylinder into one pressure chamber and the other pressure chamber, connects the one pressure chamber to the pressurizing side, and measures the other pressure chamber. While connected to a circuit, etc., the amount of movement of the piston when one of the pressure chambers is pressurized is configured to measure the amount of leakage of the circuit being measured, etc., while the pressure receiving areas of the pistons in both pressure chambers are equal. It is assumed that there is a leak measuring instrument.
The piston is characterized in that a check valve that allows only the flow from the other pressure chamber to the one pressure chamber is provided on the premise of the measuring instrument.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the embodiment shown in FIG. 1, the other pressure chamber 3 and the detection hole 4, that is, one pressure chamber 2 are communicated with the piston P through a check valve 9. The check valve 9 is configured to allow only the flow from the other pressure chamber 3 to the one pressure chamber 2.
All other configurations are the same as those in the prior art.
[0010]
Now, when the other pressure chamber 3 is connected to the measurement target side holding a certain pressure, the pressure fluid led to the pressure chamber 3 is also led to the one pressure chamber 2 by pushing the check valve 9 open. Therefore, both pressure chambers 2 and 3 are immediately at the same pressure. In other words, the other pressure chamber 3 is connected to the object to be measured, and at the same time, the measurement is possible.
[0011]
After the pressure chambers 2 and 3 become the same pressure as described above, they function in the same manner as in the prior art. That is, if a leak occurs on the measurement target side, the pressure in the other pressure chamber 3 decreases by the amount of the leak. Therefore, the pressure in one pressure chamber 2 overcomes and the piston P moves rightward, and the amount of leakage on the measurement target side can be measured based on the amount of movement.
Note that when the piston P moves in the right direction as described above, the pressure on the one pressure chamber 2 side becomes higher than the pressure in the other pressure chamber 3, so that the check valve 9 is kept closed. In other words, the fluid on the one pressure chamber 2 side does not leak to the other pressure chamber 3 side.
[0012]
In the above embodiment, the movement amount of the piston P is detected by the relative movement amount between the sensor element 5 and the core 7. However, as an invention, as long as the pressure receiving area of the piston P is equal, any mechanism for detecting the movement amount of the piston may be used. For example, the amount of movement of the piston may be taken out of the cylinder C and measured.
[0013]
【The invention's effect】
According to the leak measuring instrument of the present invention, even when the pressure on the measuring object side is high, the leak can be measured simultaneously with connecting it to the cylinder. Therefore, it is possible to solve the problem that it takes time until the measurement becomes possible as in the prior art.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view.
FIG. 2 is a cross-sectional view of a conventional leak measuring instrument.
[Explanation of symbols]
C Cylinder P Piston 1 Piston holding part 2 One pressure chamber 3 The other pressure chamber 4 Detection hole 5 Sensor element 9 as element Check valve

Claims (1)

A piston provided in the cylinder divides the inside of the cylinder into one pressure chamber and the other pressure chamber, connects this one pressure chamber to the pressurizing side, and connects the other pressure chamber to the circuit to be measured In addition, the leakage measuring device is configured to measure the amount of leakage of a circuit to be measured by the amount of movement of the piston when one of the pressure chambers is pressurized, while the pressure receiving areas of the pistons in the two pressure chambers are equal. The leak measuring instrument according to claim 1, wherein the piston is provided with a check valve that allows only the flow from the other pressure chamber to the one pressure chamber.

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