JP3626330B2 - Leak measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a leak measuring instrument, and more particularly to a leak measuring instrument that measures a leak amount of a hydraulic device such as a control valve.
[0002]
[Prior art]
Conventionally, as shown in FIG. 3, this type of leak measuring device includes a piston 3 slidably provided in the cylinder 1, and two pressure chambers A and B partitioned in the cylinder 1 by the piston 3. One pressure chamber A of the two oil chambers is connected to a pressurizer (not shown) via a port a, and the other pressure chamber B is connected to a hydraulic device or a hydraulic circuit which is a measurement target (not shown) via a port b. The detection rod 4 connected and fixed to the cylinder 1 is inserted into the detection hole 3a formed along the axis 1f of the cylinder 1 in a non-contact state, and provided at the core 4a provided on the detection rod 4 and at the end of the detection hole 3a. The non-contact stroke sensor 6 comprising the detection coil 5 measures the amount of leakage of the hydraulic device or hydraulic circuit that is the object of measurement by the amount of movement of the piston 3 when one pressure chamber A is pressurized. There is something.
[0003]
[Problems to be solved by the invention]
By the way, in the above-mentioned conventional example, in order to allow the piston to freely slide in the cylinder and to prevent fluid leakage from the sliding surface between the cylinder and the piston, the inner peripheral surface of the cylinder and the outer peripheral surface of the piston Therefore, it is necessary to process a long range in the cylinder so as to cover the stroke of the piston with high accuracy, and there is a problem that it is expensive and the cost cannot be reduced.
Also, if foreign matter enters the cylinder, scratches on the inner peripheral surface of the cylinder, leakage from the sliding surface between the cylinder and the piston, or piston operation becomes defective There was a problem that the inner circumference of the cylinder had to be reworked or replaced over the entire range.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the cost by reducing the machining range without changing the inner circumference of the cylinder over the entire range, and making it possible to replace parts by dividing the function.
[0004]
[Means for Solving the Problems]
In the first invention, a cylinder, a piston that is slidably inserted in the cylinder, two pressure chambers defined in the cylinder by the piston, and one of the pressure chambers are connected to the pressurizer. Port, a port provided in the cylinder to connect the other pressure chamber to the hydraulic device to be measured, a detection hole formed in the piston along the cylinder axis, and a non-contact state inserted into the detection hole. Measured with the amount of movement of the piston when one of the pressure chambers is pressurized, with a detection rod fixed to one end of the cylinder and a stroke sensor consisting of a core provided on the detection rod and a coil provided at the end of the detection hole In the leak measuring instrument that measures the leak amount of the target hydraulic equipment, a lap portion is formed near the center of the cylinder, and a piston is slidably inserted into the hole formed in the lap portion. .
[0005]
In the second invention, the wrap portion is provided separately from the cylinder, sealed to the large diameter portion molded in the cylinder with the seal member, locked through the collar and the lid, and detachably inserted.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same components as those in the conventional example will be described with the same names and symbols.
As shown in FIG. 1, in the leak measuring instrument according to this embodiment, a lap portion 1a is formed integrally with the cylinder 1 in the vicinity of the center in the cylinder 1, the inside of the cylinder 1 is partitioned, and the cylinder end is screwed. Two pressure chambers A and B are formed by the joined lid bodies 2a and 2b.
[0007]
The cylinder 1 is formed with a port a provided to connect one pressure chamber A to a pressurizer (not shown) and a port b provided to connect the other pressure chamber B to a hydraulic device (not shown). ing.
[0008]
A detection hole 1b is formed in the lap portion 1a coaxially with the central axis 1f of the cylinder 1, and a piston 3 is slidably fitted into the detection hole 1b.
[0009]
A detection hole 3a is formed in the piston 3 along the central axis 1f of the cylinder 1, and a detection coil 5 is attached to one end side of the detection hole 3a.
[0010]
A detection rod 4 is fixed to a lid body 2a that is screwed onto the end of the cylinder 1, and is inserted into a detection hole 3a formed in the piston 3 while maintaining a non-contact state.
[0011]
The detection coil 5 provided on one end side of the detection hole 3a and the core 4a provided on the detection rod 4 constitute a stroke sensor 6 for detecting the stroke of the piston 3.
[0012]
When a pressure difference (Pa-Pb) occurs between the pressure Pa in the pressure chamber A and the pressure Pb in the pressure chamber B, the piston 3 moves from the pressure chamber A side where the pressure is high to the pressure chamber B side (the right direction in the figure). The stroke of the piston 3 is detected by the stroke sensor 6 by moving.
[0013]
The length of the wrap portion 1 a in the direction of the center axis 1 f of the cylinder 1 is smaller than the total length of the cylinder 1 and larger than the diameter of the piston 1.
[0014]
In addition, the hole 1b provided in the lap portion 1a is processed with high accuracy so that the piston 3 can slide freely and does not leak from the gap between the inner periphery 1c of the hole 1b and the outer periphery 3b of the piston 3. Therefore, only a sliding surface that is much shorter than the entire length of the cylinder 1 needs to be processed with high accuracy.
[0015]
Next, the operation will be described.
Now, for example, if one of the pressure chambers A is pressurized by a pressurizer (not shown) and a hydraulic device (not shown) connected to the other pressure chamber B has no leakage, the pressure Pa and the pressure in the pressure chamber A The pressure Pb in the chamber B is the same pressure (Pa = Pb), and therefore, the piston 3 does not move and remains stopped, and the leakage of the hydraulic device by the stroke sensor 6 is not detected.
[0016]
When a leak occurs in the hydraulic device that is the measurement target, the pressure Pb in the pressure chamber B becomes lower than the pressure Pa in the pressure chamber A (Pa> Pb), and a pressure difference occurs between the piston 3 and the piston 3. The signal slides in the right direction in the figure over the hole 1b provided in the lap portion 1a, and the signal detected by the stroke sensor 6 according to the movement amount of the piston 3 is converted into a leak amount by a control unit (not shown). The leak of the hydraulic device that is the measurement target is measured.
[0017]
In this way, the leak measuring device measures the leak amount of the hydraulic device to be measured by the movement amount of the piston 3, and the lap portion 1 a integrated with the cylinder 1 is formed near the center in the cylinder 1. Since the piston 3 is slidably inserted into the hole 1b formed in the lap 1a, the piston 3 freely slides in the cylinder 1 as in the conventional example, and the cylinder 1 and the piston 3 In order to prevent fluid leakage from the sliding surface, a long range in the cylinder 1 is provided so that the clearance between the inner peripheral surface of the cylinder 1 and the outer peripheral surface of the piston 3 can be made with high accuracy and the full stroke of the piston 3 can be covered. There is no need for processing, the number of processing steps is reduced, the cost is reduced, and the cost can be reduced.
[0018]
Next, the second embodiment shown in FIG. 2 differs from the first embodiment only in the configuration in which the wrap portion is provided separately and is detachably inserted. This is the same as the embodiment, and here, only different configurations will be described, and details of other components will be omitted.
Therefore, in the leak measuring instrument according to the second embodiment, as shown in FIG. 2, a large-diameter portion 1d that reaches the vicinity of the center in the cylinder 1 is formed, and the large-diameter portion 1d is sealed with a seal member 7. Thus, a wrap portion 8 provided separately from the cylinder 1 is inserted.
[0019]
The wrap portion 8 is further locked to the step portion 1e at the other end of the large-diameter portion 1d with a collar 9 fitted into the large-diameter portion 1d and a lid 2b screwed into the cylinder 1, and is detachably mounted. ing.
[0020]
A hole 8a is formed in the wrap portion 8 along the central axis 1f of the cylinder 1, and the piston 3 is slidably fitted into the hole 8a.
[0021]
In this way, the wrap portion 8 is provided separately from the cylinder 1 and sealed to the large-diameter portion 1d molded in the cylinder 1 with the seal member 7 and is locked via the collar 9 and the lid body 2b. Since the same effect as the first embodiment is obtained, foreign matter is mixed in the cylinder 1 and the inner peripheral surface of the cylinder 1 is scratched. Even when leakage from the sliding surface between the cylinder 1 and the piston 3 occurs or the operation of the piston 3 becomes defective, the wrap portion 8 is detachably mounted. The inner circumference 8b of the cylinder 1 can be easily reworked by taking out from the inside, and in some cases, the lap portion 8 can be replaced with a new one, and maintenance can be facilitated.
[0022]
【The invention's effect】
According to the first invention, there is provided a leak measuring instrument for measuring a leak amount of a hydraulic device to be measured by a movement amount of a piston, wherein a lap portion integrated with the cylinder is formed near the center in the cylinder. Since the piston is slidably inserted into the hole formed in this lap part, the cylinder can be covered with high accuracy with a clearance between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston. There is no need to process the entire range, the number of processing steps is reduced, the cost is reduced, and the cost can be reduced.
[0023]
According to the second invention, the wrap portion is provided separately from the cylinder, sealed to the large-diameter portion molded in the cylinder with the sealing member, locked through the collar and the lid, and detachably inserted. As a result, the same effects as in the first embodiment can be obtained, foreign substances can be mixed into the cylinder, and the inner peripheral surface of the cylinder can be scratched. Even if leakage from the sliding surface occurs or the piston malfunctions, the lapping part can be removed from the cylinder and the cylinder inner circumference can be easily reworked. The part can be replaced with a new one, and there is an effect that the maintenance can be easily performed.
[Brief description of the drawings]
FIG. 1 is a front cross-sectional view of a leak measuring instrument showing an embodiment of the present invention.
FIG. 2 is a front sectional view of a leak measuring instrument showing another embodiment.
FIG. 3 is a front sectional view of a leak measuring instrument showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cylinder 1a Lapping part 1b Hole 1c Sliding surface 1d Large diameter part 1e Step part 1f Cylinder center axis 2a, 2b Cover body 3 Piston 3a Detection hole 3b Outer periphery 4 Detection rod 4a Detection core 5 Detection coil 6 Stroke sensor 7 Seal member 8 Lap 9 Color A, B Pressure chamber a, b Port Pa Pressure P in pressure chamber A Pb Pressure in pressure chamber B

Claims (2)

A cylinder, a piston that is slidably inserted in the cylinder, two pressure chambers defined in the cylinder by the piston, a port provided in the cylinder to connect one pressure chamber to the pressurizer, and the other A port provided in the cylinder to connect the pressure chamber to the hydraulic device to be measured, a detection hole formed in the piston along the cylinder axis, and a non-contact state inserted into the detection hole and fixed to one end of the cylinder And a stroke sensor comprising a core provided on the detection rod and a coil provided at the end of the detection hole, and the amount of movement of the piston when one pressure chamber is pressurized In the leak measuring device that measures the amount of leak, a lap part is formed near the center of the cylinder, and a piston is slidably inserted into a hole formed in the wrap part. Leak meter characterized. The wrap portion is provided separately from the cylinder, sealed to a large-diameter portion molded in the cylinder with a seal member, locked through a collar and a lid, and detachably fitted. The leak measuring instrument according to claim 1.

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