Gas compressor

Abstract

To prevent a reduction in the life of a bellows in a bellows type gas compressor.SOLUTION: A bellows type gas compressor comprises: a pressurized container 1 filled with a pressurized fluid; a bellows 2 partitioning a portion inside the pressurized container 1, to which gas to be compressed is supplied, and capable of extending and contracting; a pump 18 for increasing pressure inside the pressurized container 1; and a balance piston 6 partitioning the inside of the pressurized container 1 into a space 7b outside the bellows 2, and a space 7a in which the pressure is increased by the pump 18. The balance piston 6 transmits the pressure increased by the pump 18, to the pressurized fluid outside the bellows.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a bellows type gas compressor, and more particularly to a gas compressor in which a reduction in the life of the bellows is prevented. [Background technology]

[0002] Conventionally, reciprocating compressors (piston compressors) have been used to compress various gases such as gaseous fuels. Reciprocating compressors have issues with the durability of sliding components such as piston rings and rod packings, and there are also issues such as heat generation when operating at high pressures without lubrication. In order to solve such problems, for example, a compressor that does not use sliding members can be considered, and a bellows type compressor is known as a compressor that does not use sliding members.

[0003] Patent Document 1 describes a bellows compressor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Utility Model Application Publication No. 64-4882 Summary of the Invention [Problem to be solved by the invention]

[0005] An example of a conventional bellows compressor is shown in Figure 6. This bellows compressor is configured by placing a bellows 102 that partitions a portion of the interior of a pressurized container 101, which has a fixed volume. Bellows 102 is made of a folded flexible material into a cylindrical shape and is expandable and contractible, resulting in a variable volume. This bellows compressor is equipped with a pump 104 that increases the pressure inside pressurized container 101 and supplies pressurized fluid 103 into pressurized container 101.

[0006] When pressurized fluid 103 is released from pressurized container 101 through exhaust valve 111 and the pressure drops to a low level, bellows 102 is expanded, and gas 107 to be compressed (e.g., hydrogen) is drawn into bellows 102 from gas intake hole 106 via intake check valve 105.

[0007] When pressurized fluid 103 is supplied into pressurized container 101 through supply on-off valve 110 and becomes highly pressurized, bellows 102 is contracted and gas 107 in bellows 102 is compressed. The internal pressures of pressurized fluid 103 in pressurized container 101 and gas 107 in bellows 102 become equal. Compressed gas 107 is discharged from bellows 102 through gas discharge hole 109 via discharge check valve 108.

[0008] In this bellows compressor, the internal pressure inside the bellows 102 and the outside of the bellows 102 (inside the pressurized vessel 101) are equal, creating a pressure balance state, which reduces stress on the bellows 102 and ensures the durability of the bellows 102.

[0009] However, according to an FMEA analysis (Failure Mode and Effect Analysis), it was found that failure of the suction check valve 105 or the discharge check valve 108 shortens the life of the bellows 102. It was also found that failure of the supply on-off valve 110 or the discharge on-off valve 111 may result in a large amount of pressurized fluid 103 being consumed, which may damage the bellows 102.

[0010] If the suction check valve 105 fails, during the suction stroke of the gas 107, the maximum displacement of the bellows 102 is detected and the pressurized fluid 103 is supplied, causing a transition to the compression stroke, increasing the operating speed and frequency and shortening the life of the bellows 102. Also, during the discharge stroke of the gas 107, the suction check valve 105 is in an open state, causing gas to flow out to the gas suction side and causing repeated emptying, increasing the operating speed and frequency and shortening the life of the bellows 102.

[0011] If the discharge check valve 108 malfunctions, the discharge check valve 108 opens during the intake stroke of the gas 107, causing gas to flow out to the gas discharge side and repeating empty-flow operations, increasing the operating speed and frequency and shortening the life of the bellows 102. Also during the discharge stroke of the gas 107, the discharge check valve 108 opens during the intake stroke of the gas 107, causing gas to flow out to the gas discharge side and repeating empty-flow operations, increasing the operating speed and frequency and shortening the life of the bellows 102.

[0012] If the supply on-off valve 110 fails, during the supply stroke of the pressurized fluid 103, an excessive amount of pressurized fluid 103 may be supplied, causing the bellows 102 to become fixed in the minimum displacement direction, resulting in a stoppage of operation, a large amount of pressurized fluid 103 being consumed, and damage to the bellows 102. Also during the discharge stroke of the pressurized fluid 103, an excessive amount of pressurized fluid 103 may be supplied, causing the bellows 102 to become fixed in the minimum displacement direction, resulting in a stoppage of operation, a large amount of pressurized fluid 103 being consumed, and damage to the bellows 102.

[0013] If the discharge on-off valve 111 fails, unstable operation may occur during the supply process of the pressurized fluid 103, causing a large amount of pressurized fluid 103 to be consumed and damaging the bellows 102. Also, unstable operation may occur during the discharge process of the pressurized fluid 103, causing a large amount of pressurized fluid 103 to be consumed and damaging the bellows 102.

[0014] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a bellows type gas compressor in which the life of the bellows is prevented from being shortened.

[0015] Further objects of the present invention will become apparent from the following description. [Means for solving the problem]

[0016] The above problems are solved by the following inventions.

[0017] 1. a pressurized vessel filled with a pressurized fluid; a bellows that partitions a part of the pressurized container, into which the gas to be compressed is supplied, and which is expandable and contractible and whose volume changes; a pump that increases the pressure inside the pressurized container; a balance piston slidably disposed within the pressure vessel, dividing the interior of the pressure vessel into a space outside the bellows and a space pressurized by the pump; Equipped with The balance piston transmits the pressure generated by the pump to the pressurized fluid outside the bellows. A gas compressor characterized by: 2. The amount of change in the volume of the bellows per moving distance of the balance piston is smaller than the amount of change in the volume of the space pressurized by the pump, and the internal pressure inside the bellows and the space outside the bellows is higher than the internal pressure inside the space pressurized by the pump. 2. The gas compressor according to claim 1, 3. The balance piston is integrally formed with a reduced diameter portion on one end side and an expanded diameter portion on the other end side, and the reduced diameter portion is inserted into the space outside the bellows, and the end face of the expanded diameter portion and the pressurizing container form a space that is pressurized by the pump. 3. The gas compressor according to item 2 above. 4. a gas inlet into the bellows; a gas discharge hole from within the bellows; Equipped with As the pressurized fluid in the space pressurized by the pump is increased, the pressurized fluid outside the bellows is increased in pressure, the volume of the bellows that has drawn in gas from the gas suction hole is reduced, the balance piston is moved in accordance with the reduction in the volume of the bellows, and the gas in the bellows is discharged from the gas discharge hole. 4. The gas compressor according to any one of 1, 2 and 3 above. 5. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressure vessel. 4. The gas compressor according to any one of 1, 2 and 3 above. 6. a position adjustment discharge valve that is opened to discharge the pressurized fluid in the space outside the bellows to the outside; a position adjustment supply valve that is opened to supply the pressurized fluid into the space outside the bellows; and When the bellows is compressed beyond a predetermined range, the position adjustment discharge valve is opened by a cover plate at the end of the bellows, and the pressurized fluid that has flowed into the space outside the bellows is discharged to the outside via the position adjustment discharge valve. When the bellows is extended beyond a predetermined range, the position adjustment supply valve is opened by the cover plate at the end of the bellows, and the pressurized fluid is supplied into the space outside the bellows via this position adjustment supply valve, thereby compensating for any leaked pressurized fluid. 4. The gas compressor according to any one of 1, 2 and 3 above. 7. The movable range of the balance piston is limited between a pair of stop plates. 4. The gas compressor according to any one of 1, 2 and 3 above. 8. A hydraulic damper is formed between the stop plate and the balance piston. 8. The gas compressor according to claim 7, 9. a pressure sensor that detects the pressure of the discharge gas discharged from inside the bellows; a gas intake shutoff valve; a discharge shutoff valve for the gas; Control means and and The control means operates the intake cutoff valve and the discharge cutoff valve when the pressure of the discharge gas detected by the pressure sensor indicates an abnormality, thereby cutting off the intake gas and the discharge gas being sucked into the bellows. 4. The gas compressor according to any one of 1, 2 and 3 above. 10. a position sensor that detects the position of the balance piston; a supply on-off valve that opens and closes the supply of the pressurized fluid to the space pressurized by the pump; a discharge on-off valve that opens and closes the discharge of the pressurized fluid from the space pressurized by the pump; Control means and and When the position of the balance piston detected by the position sensor is out of a predetermined range, the control means operates the supply on-off valve and the discharge on-off valve to cut off the pressurized fluid supplied to the space pressurized by the pump and the pressurized fluid discharged from the space pressurized by the pump. 4. The gas compressor according to any one of 1, 2 and 3 above. 11. The supply on-off valve and the discharge on-off valve are one two-position switching valve. 11. The gas compressor according to claim 10, 12. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressurized container, a position sensor that detects the position of the balance piston; Control means and and The control means detects the position of the balance piston using the position sensor, and controls the flow rate of the variable displacement hydraulic pump based on the detection result, thereby controlling the movement range of the balance piston. 4. The gas compressor according to any one of 1, 2 and 3 above. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a bellows type gas compressor in which a reduction in the life of the bellows is prevented. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of a gas compressor according to a first embodiment of the present invention (when gas is sucked in); [Figure 1A] FIG. 3 is a cross-sectional view showing the configuration of a bellows of the gas compressor. [Figure 1B] FIG. 4 is a cross-sectional view showing the configuration of a hydraulic damper of the gas compressor. [Figure 1C] FIG. 10 is a cross-sectional view showing a state in which the hydraulic damper is in operation. [Figure 1D] FIG. 3 is a cross-sectional view showing the configuration of a position adjustment discharge valve and a position adjustment supply valve of the gas compressor. [Figure 2] FIG. 3 is a cross-sectional view showing the configuration of the gas compressor of the first embodiment (when discharging gas); [Figure 3] FIG. 10 is a cross-sectional view showing another example of the connection between the pressurized vessel and the pump of the gas compressor. [Figure 4] FIG. 4 is a cross-sectional view showing another example of the pump of the gas compressor. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of a gas compressor according to a second embodiment of the present invention. [Figure 5A] FIG. 10 is a cross-sectional view showing another example of the hydraulic damper of the gas compressor according to the second embodiment. [Figure 5B] FIG. 10 is a cross-sectional view showing another example of the hydraulic damper of the gas compressor according to the second embodiment in operation. [Figure 6] Cross-sectional view showing an example of a conventional bellows compressor DETAILED DESCRIPTION OF THE INVENTION

[0020] Preferred embodiments of the present invention will now be described.

[0021] [First embodiment] [Configuration of gas compressor] FIG. 1 is a cross-sectional view showing the configuration of a gas compressor according to a first embodiment of the present invention (when gas is sucked in).

[0022] 1, this gas compressor has a pressurized vessel 1 filled with a pressurized fluid, and a bellows 2 that defines a portion of the interior of the pressurized vessel 1. In this embodiment, the volume of the pressurized vessel 1 is constant. FIG. 1A is a cross-sectional view showing the configuration of the bellows of the gas compressor. The bellows 2 is made of a flexible material and formed into a cylindrical shape. As shown in FIG. 1A, the side surface is bent into a plurality of pleats, so that the bellows 2 can expand and contract in the axial direction, and the volume changes as the bellows expands and contracts.

[0023] The preferred material for the bellows 2 is a metal that is not susceptible to hydrogen embrittlement, such as stainless steel, etc. The thickness of the material for the bellows 2 can be, for example, about 0.2 mm.

[0024] The shape of the pressurized vessel 1 is preferably a cylinder with both open ends closed, but is not limited to this and may be a square tube.Furthermore, the bellows 2 is also not limited to a cylindrical shape and may be a square tube.

[0025] One open end of the bellows 2 is joined to the inner wall of the pressurized container 1, and the other open end is closed by a cover plate 3. A sealed space is formed by the inner wall of the pressurized container 1 at the part where the bellows 2 is joined, the bellows 2, and the cover plate 3. The gas to be compressed is supplied into the bellows 2, and the bellows 2 is filled with the gas to be compressed, and no pressurized fluid is present inside.

[0026] A gas inlet hole 4a communicating with the sealed space within the bellows 2 is formed in the wall of the pressure vessel 1 at the portion where the bellows 2 is joined. This gas inlet hole 4a is provided with an inlet check valve 5a that stops gas from flowing out from the gas inlet hole 4a. Furthermore, a gas outlet hole 4b communicating with the sealed space within the bellows 2 is formed in the wall of the pressure vessel 1 at the portion where the bellows 2 is joined. This gas outlet hole 4b is provided with a discharge check valve 5b that stops gas from flowing into the gas outlet hole 4b.

[0027] The pressurized container 1 is provided with a hydraulic oil supply hole 15b and a hydraulic oil discharge hole 15a. A hydraulic oil supply pipe 16b is connected to the hydraulic oil supply hole 15b, and a hydraulic oil discharge pipe 16a is connected to the hydraulic oil discharge hole 15a. The hydraulic oil supply pipe 16b is connected to a hydraulic unit 18, which is a pump, via a supply on-off valve 17b. The hydraulic oil discharge pipe 16a is connected to the hydraulic unit 18 via a discharge on-off valve 17a. The operation of the hydraulic unit 18, the supply on-off valve 17b, and the discharge on-off valve 17a is controlled by a control device 14, which serves as control means. The pressure inside the pressure vessel 1 is increased by a hydraulic unit 18 .

[0028] A balance piston 6 is provided inside the pressurized container 1. This balance piston 6 is slidably disposed inside the pressurized container 1, and divides the interior of the pressurized container 1 into a space 7b outside the bellows 2 and a space 7a pressurized by a hydraulic unit 18. The balance piston 6 transmits the pressure boosted by the hydraulic unit 18 to the pressurized fluid outside the bellows 2. The balance piston 6 moves in accordance with changes in the volume inside the bellows 2.

[0029] Unlike the pistons of conventional reciprocating compressors, balance piston 6 does not separate high-pressure gas from low-pressure gas, nor does it actively slide to compress gas. Balance piston 6 separates the pressurized fluid in space 7b outside bellows 2 from the pressurized fluid in space 7a pressurized by hydraulic unit 18, and the internal pressures of these spaces are equal. Balance piston 6 passively slides in response to changes in the difference in volume between inside bellows 2 and space 7a pressurized by hydraulic unit 18. Therefore, unlike the pistons of conventional reciprocating compressors, balance piston 6 does not pose problems such as durability or heat generation.

[0030] In this embodiment, the sum of the volume of the space 7b outside the bellows 2 and the external volume of the bellows 2 and the cover plate 3, and the volume of the space 7a pressurized by the hydraulic unit 18 is the volume of the pressurized container 1 minus the external volume of the balance piston 6, and is unchanged.

[0031] The space 7b outside the bellows 2 is filled with pressurized fluid. The space 7a, which is pressurized by the hydraulic unit 18, is also filled with pressurized fluid. The pressurized fluid may be, for example, hydraulic oil for a hydraulic device.

[0032] The movable range of the balance piston 6 can be limited between a pair of stop plates 8a, 8b. It is preferable to form hydraulic dampers 9a, 9b between the stop plates 8a, 8b and the balance piston 6. The hydraulic dampers 9a, 9b are intake hydraulic dampers that use pressurized fluid in the space 7a that is pressurized by the hydraulic unit 18, and discharge hydraulic dampers that use pressurized fluid in the space 7b outside the bellows 2.

[0033] FIG. 1B is a cross-sectional view showing the configuration of the hydraulic damper of the gas compressor. The hydraulic dampers 9a and 9b have the same configuration and are disposed in opposite directions, so only the discharge hydraulic damper 9b, which uses the pressurized fluid in the space 7b outside the bellows 2 as shown in FIG. 1B, will be described.

[0034] The balance piston 6 is provided with a protrusion 6c that fits into a fitting hole 8c formed in the center of the stopper plate 8b. As shown in Fig. 1B, when the balance piston 6 is moved in a direction away from the bellows 2, the protrusion 6c is separated from the fitting hole 8c. At this time, the pressure of the pressurized fluid in the space 7b outside the bellows 2 is the same pressure P1 at every point.

[0035] FIG. 1C is a cross-sectional view showing a state in which the hydraulic damper is in operation. 1C, when the balance piston 6 is moved in a direction approaching the bellows 2, the protrusion 6c fits into the fitting hole 8c. At this time, the space between the balance piston 6 and the stopper plate 8b is blocked by the pressurized container 1 and the protrusion 6c, forming a closed space, hydraulic damper 9b. The pressurized fluid in this closed space, hydraulic damper 9b, is pressed by the balance piston 6 to a pressure P2 higher than the pressure P1 of the pressurized fluid in the space 7b outside the bellows 2.

[0036] As shown by arrow P in FIG. 1C, the pressurized fluid in hydraulic damper 9b, which is a closed space, leaks into space 7b outside bellows 2 from the gap between the outer circumferential surface of protrusion 6c and the inner circumferential surface of fitting hole 8c. If the amount of pressurized fluid leaking at this time is large, the amount by which balance piston 6 is decelerated is small, and the buffering capacity for balance piston 6 is low. If the amount of pressurized fluid leaking is small, the amount by which balance piston 6 is decelerated is large, and the buffering capacity for balance piston 6 is high. The amount of pressurized fluid leakage can be adjusted by utilizing the viscosity effect (viscous flow) or the throttling effect (throttling flow) (the width of the gap between protrusion 6c and fitting hole 8c).

[0037] In this gas compressor, the movable range of the balance piston 6 is limited to a certain range, and therefore the operating range of the bellows 2 is also limited to a certain range, and the amount of displacement is also limited to a certain range, so that damage to the bellows 2 and a reduction in the lifespan of the bellows 2 can be prevented. In addition, in this gas compressor, the hydraulic dampers 9a and 9b reduce the hydraulic fluctuation load on the bellows 2, allowing the bellows 2 to operate smoothly, thereby preventing damage to the bellows 2 and preventing a reduction in the lifespan of the bellows 2.

[0038] A gas intake pipe 10a is connected to the gas intake hole 4a, and is connected to a low-pressure gas tank 12a via an intake shutoff valve 11a. A gas discharge pipe 10b is connected to the gas discharge hole 4b. The gas discharge pipe 10b is connected to a high-pressure gas tank 12b via a discharge cutoff valve 11b. The operation of the suction cutoff valve 11a and the discharge cutoff valve 11b is controlled by a control device 14. The gas is, for example, hydrogen, but is not limited to this and may be any of various other fuel gases.

[0039] The space 7a is pressurized by the hydraulic unit 18, and pressurized fluid is supplied from the hydraulic oil supply pipe 16b via the supply on-off valve 17b, which has been opened. In addition, the pressure in the space 7a, which is pressurized by the hydraulic unit 18, is reduced by the hydraulic unit 18, and the pressurized fluid is discharged and recovered from the hydraulic oil discharge pipe 16a via the discharge on-off valve 17a, which has been opened.

[0040] [Compression Operation] In this gas compressor, when the pressure in space 7a, which is pressurized by hydraulic unit 18, is reduced, the internal pressure in space 7b outside bellows 2 is also reduced. At this time, as shown in Figure 1, the volume of bellows 2, which has drawn gas through gas inlet hole 4a, is expanded. The internal pressures in space 7a, which is pressurized by hydraulic unit 18, space 7b outside bellows 2, and inside bellows 2 are all equal.

[0041] The pressurized vessel 1 may be provided with a position sensor 19 that detects the position of the balance piston 6. Various types of position sensor 19 may be used, such as an optical sensor, an acoustic sensor, or a contact sensor. The detection result by the position sensor 19 is sent to the control device 14.

[0042] The control device 14 detects, via the position sensor 19, that the balance piston 6 is at a position where the volume of the bellows 2 is maximum, and when this position is detected, closes the discharge on-off valve 17a to stop the discharge of pressurized fluid from the space 7a pressurized by the hydraulic unit 18. At this time, the control device 14 also opens the supply on-off valve 17b to start the supply of pressurized fluid to the space 7a pressurized by the hydraulic unit 18.

[0043] FIG. 2 is a cross-sectional view showing the configuration of the gas compressor of the first embodiment (when discharging gas).

[0044] The control device 14 detects, via the position sensor 19, that the balance piston 6 is at a position where the volume of the bellows 2 is minimum, and when this position is detected, closes the supply on-off valve 17b to stop the supply of pressurized fluid to the space 7a pressurized by the hydraulic unit 18. At this time, the control device 14 also opens the discharge on-off valve 17a to start discharging the pressurized fluid from the space 7a pressurized by the hydraulic unit 18. The control device 14 controls the movable distance (stroke) of the bellows 2 based on the position of the balance piston 6 detected by the position sensor 19.

[0045] In this gas compressor, when the pressure inside the space 7a is increased by the hydraulic unit 18, the pressurized fluid compressed according to the compression rate k of the pressurized fluid is supplied, the balance piston 6 moves slightly toward the bellows 2, and the pressurized fluid inside the space 7b outside the bellows 2 is also compressed and increased in pressure. In other words, the boosting force from the hydraulic boost unit 18 is transmitted by the balance piston 6 to the pressurized fluid outside the bellows 2. At this time, according to Boyle's law (PV=nRT ∵P is pressure, V is volume, n is the amount of substance of the gas, R is the gas constant, and T is absolute temperature), gas pressure and volume are inversely proportional, so the volume of the bellows 2 that has drawn in gas from the gas inlet port 4a is reduced, as shown in Figure 2. Then, the balance piston 6 is moved to a position where the volume of the space 7a that is pressurized by the hydraulic unit 18 increases by the amount of the decrease in the volume inside the bellows 2. The gas drawn into the bellows 2 is compressed, and its pressure becomes equal to the internal pressure of the space 7b outside the bellows 2, and it is discharged from the gas outlet port 4b.

[0046] When the pressure in space 7a, which is pressurized by hydraulic unit 18, is reduced, the pressure in space 7b outside bellows 2 is also reduced. At this time, as shown in FIG. 1, gas is drawn in through gas inlet hole 4a, expanding the volume of bellows 2. Then, balance piston 6 is moved to a position where the volume of space 7a, which is pressurized by hydraulic unit 18, is reduced by the amount of the increase in the volume inside bellows 2. Hydraulic unit 18 discharges and recovers the pressurized fluid equivalent to the increase in the volume of bellows 2. The gas drawn into bellows 2 has a pressure equal to the internal pressure of space 7b outside bellows 2.

[0047] In this way, by repeatedly increasing and decreasing the pressure in the space 7a, which is pressurized by the hydraulic unit 18, the intake of low-pressure gas due to the expansion of the volume of the bellows 2, and the compression of gas due to the contraction of the volume of the bellows 2 and the discharge of high-pressure gas are repeated, and the high-pressure discharge gas is filled into the high-pressure gas tank 12b.

[0048] The control device 14 may calculate the movement speed of the balance piston 6 based on the position detection of the balance piston 6 by the position sensor 19, and control the supply and discharge amounts of pressurized fluid to and from the space 7a pressurized by the hydraulic unit 18 according to this movement speed.

[0049] In this gas compressor, the provision of the balance piston 6 prevents the pulsation and impacts propagating through the pressurized fluid from being directly applied to the bellows 2, thereby preventing damage to the bellows 2 and shortening the lifespan of the bellows 2. Furthermore, in this gas compressor, the control device 14 controls the movable distance (stroke) of the bellows 2 based on the position detection of the balance piston 6 by the position sensor 19, thereby preventing damage to the bellows 2 and shortening of the lifespan of the bellows 2.

[0050] [Autonomous position control of bellows] In this gas compressor, the bellows 2 can be autonomously controlled to a position within a predetermined movable range. FIG. 1D is a cross-sectional view showing the configuration of a position adjusting discharge valve and a position adjusting supply valve of the gas compressor. In this gas compressor, in order to autonomously control the position of the bellows 2 within a predetermined movable range, as shown in FIG. 1D, a position adjustment discharge valve 20a is provided which, when opened, discharges the pressurized fluid in the space 7b outside the bellows 2 to the outside, and a position adjustment supply valve 20b is provided which, when opened, supplies the pressurized fluid into the space 7b outside the bellows 2.

[0051] The position adjustment discharge valve 20a is provided on one open end side (upper part in FIGS. 1 and 1D) of the bellows 2, in the space 7b outside the bellows 2. The position adjustment discharge valve 20a is configured to include a cylinder 21 and a piston rod 22 arranged inside the cylinder 21. The piston rod 22 is slidable in the axial direction while keeping its outer peripheral surface in close contact with the inner peripheral surface of the cylinder 21 . The cylinder 21 has an open tip end, and an inwardly opening concave tapered portion 21a is formed at an inward position of the tip end. The piston rod 22 has a tip end that projects beyond the tip end of the cylinder 21, and a convex tapered portion 22a that corresponds to the concave tapered portion 21a is formed on the shaft portion. When the piston rod 22 is moved toward the tip end, the convex tapered portion 22a is fitted into the concave tapered portion 21a of the cylinder 21, thereby closing the gap between the convex tapered portion 22a and the concave tapered portion 21a. A compression spring 23 that presses the piston rod 22 toward the tip end is disposed inside the cylinder 21. The pressing force of this compression spring 23 closes the gap between the convex tapered portion 22a and the concave tapered portion 21a. When the tip end of the piston rod 22 is pushed toward the base end against the pressing force of the compression spring 23, the convex tapered portion 22a and the concave tapered portion 21a are separated from each other, creating a gap between them. The tip of the piston rod 22 is pressed by the end portion of the cover plate 3 of the bellows 2 . The cylinder 21 has a horizontal hole 24 that connects the inside of the cylinder 21 to the outside of the pressurized container 1 . When the convex tapered portion 22a and the concave tapered portion 21a are separated and the space between them is opened, the space 7b outside the bellows 2 is connected to the outside of the pressurized container 1 through the space between the convex tapered portion 22a and the concave tapered portion 21a, the inside of the cylinder 21, and the horizontal hole 24. From this horizontal hole 24, the pressurized fluid in the space 7b outside the bellows 2 is discharged to the outside (into the atmosphere).

[0052] Position adjustment supply valve 20b has a configuration in which the direction of position adjustment discharge valve 20a is reversed (upside down in FIGS. 1 and 1D), and is provided in space 7b outside bellows 2, on the side of cover plate 3 of bellows 2 (at the bottom in FIGS. 1 and 1D). Position adjustment supply valve 20b is configured to include a cylinder 21 and a piston rod 22 arranged within this cylinder 21. The piston rod 22 is slidable in the axial direction while keeping its outer peripheral surface in close contact with the inner peripheral surface of the cylinder 21 . The cylinder 21 has an open tip end, and an inwardly opening concave tapered portion 21a is formed at an inward position of the tip end. The piston rod 22 has a tip end that projects beyond the tip end of the cylinder 21, and a convex tapered portion 22a that corresponds to the concave tapered portion 21a is formed on the shaft portion. When the piston rod 22 is moved toward the tip end, the convex tapered portion 22a is fitted into the concave tapered portion 21a of the cylinder 21, thereby closing the gap between the convex tapered portion 22a and the concave tapered portion 21a. A compression spring 23 that presses the piston rod 22 toward the tip end is disposed inside the cylinder 21. The pressing force of this compression spring 23 closes the gap between the convex tapered portion 22a and the concave tapered portion 21a. When the tip end of the piston rod 22 is pushed toward the base end against the pressing force of the compression spring 23, the convex tapered portion 22a and the concave tapered portion 21a are separated from each other, creating a gap between them. The tip of the piston rod 22 is pressed by the end portion of the cover plate 3 of the bellows 2 . The cylinder 21 has a horizontal hole 24 that connects the inside of the cylinder 21 to the outside of the pressurized container 1 . When the convex tapered portion 22a and the concave tapered portion 21a are separated and the space between them is opened, the space 7b outside the bellows 2 is connected to the outside of the pressurized container 1 through the space between the convex tapered portion 22a and the concave tapered portion 21a, the inside of the cylinder 21, and the horizontal hole 24. From this horizontal hole 24, pressurized fluid is supplied into the space 7b outside the bellows 2.

[0053] When pressurized fluid flows from space 7a, which is pressurized by hydraulic unit 18, into space 7b outside bellows 2, the movable range of bellows 2 shifts in the direction of compressing bellows 2, and therefore, when bellows 2 is most compressed, it may be compressed outside the specified range and may be destroyed. When the bellows 2 is compressed beyond a predetermined range, the position adjustment discharge valve 20a is opened by the cover plate 3 of the bellows 2, and the pressurized fluid that has flowed into the space 7b outside the bellows 2 is discharged to the outside via this position adjustment discharge valve 20a.

[0054] When pressurized fluid flows from the space 7b outside the bellows 2 into the space 7a pressurized by the hydraulic unit 18, the movable range of the bellows 2 shifts in the direction of extending the bellows 2, and therefore, when the bellows 2 is fully extended, it may extend beyond the specified range and be destroyed. When the bellows 2 is extended beyond a predetermined range, the position adjustment supply valve 20b is opened by the cover plate 3 of the bellows 2, and pressurized fluid is supplied through this position adjustment supply valve 20b into the space 7b outside the bellows 2 to make up for the pressurized fluid that has leaked. The pressurized fluid supplied through the position adjustment supply valve 20b has a pressure slightly higher than that of the gas drawn into the bellows 2.

[0055] In this way, the movable range of the bellows 2 is autonomously controlled between the position where the position adjustment discharge valve 20a is opened and the position where the adjustment supply valve 20b is opened, so that damage due to compression and expansion going outside the specified range is prevented.

[0056] The movable distance (stroke) of the bellows 2 is controlled by the control device 14 based on the position of the balance piston 6 detected by the position sensor 19, as described above.

[0057] [Another example of connection between a pressurized container and a pump] FIG. 3 is a cross-sectional view showing another example of the connection between the pressurizing vessel and the pump of the gas compressor. In this gas compressor, as shown in FIG. 3, a two-position switching valve 17 can be provided in place of the supply on-off valve 17b and the discharge on-off valve 17a. In this case, a hydraulic oil supply / discharge hole 15 is provided in the wall of the pressurized container 1 at the portion forming the space 7a pressurized by the hydraulic unit 18, and a hydraulic oil supply / discharge pipe 16 is connected to the hydraulic oil supply / discharge hole 15, which is then connected to a two-position switching valve 17. One end of a hydraulic oil supply pipe 16b and one end of a hydraulic oil discharge pipe 16a are connected to the two-position switching valve 17, and the other ends of the hydraulic oil supply pipe 16b and the hydraulic oil discharge pipe 16a are connected to a hydraulic unit . The operation of the two-position switching valve 17 is controlled by the control device 14 .

[0058] Pressurized fluid is supplied to the space 7a pressurized by the hydraulic unit 18 via the hydraulic oil supply pipe 16b, the two-position switching valve 17, and the hydraulic oil supply / discharge pipe 16. At this time, the hydraulic unit 18 not only increases the pressure in the space 7a pressurized by the hydraulic unit 18, but also supplies the pressurized fluid. Furthermore, the pressurized fluid is discharged and recovered from the space 7a pressurized by the hydraulic unit 18 via the hydraulic oil supply / discharge pipe 16, the two-position switching valve 17, and the hydraulic oil discharge pipe 16a by the hydraulic unit 18. At this time, the hydraulic unit 18 reduces the pressure in the space 7a pressurized by the hydraulic unit 18, and discharges and recovers the pressurized fluid.

[0059] In addition, when it is necessary to cut off both the supply and discharge of hydraulic oil, a three-position switching valve is provided instead of the supply on-off valve 17b and the discharge on-off valve 17a, and the third position, to which neither the hydraulic oil supply pipe 16b nor the hydraulic oil discharge pipe 16a is connected, is closed.

[0060] [Variable displacement hydraulic pump] FIG. 4 is a cross-sectional view showing another example of the pump of the gas compressor. The pump may be a variable displacement hydraulic pump 25, as shown in Figure 4. The variable displacement hydraulic pump 25 is connected to the hydraulic oil supply / discharge hole 15 of the pressurized container 1 by a hydraulic oil supply / discharge pipe 16.

[0061] The variable displacement hydraulic pump 25 is capable of controlling the flow rate, and is capable of controlling the supply flow rate and the discharge flow rate. The variable displacement hydraulic pump 25 is driven by an electric motor 26, and the supply flow rate and the discharge flow rate of the pressurized fluid are controlled by a flow rate control device 27. The operation of the electric motor 26 and the flow rate control device 27 is controlled by the control device 14.

[0062] The variable displacement hydraulic pump 25 is provided with an accumulator (hydraulic accumulator) 28, which is designed to absorb pulsations and shocks propagating through the pressurized fluid in the piping. By absorbing the pulsation and shocks propagating through the pressurized fluid in the piping, damage to the bellows 2 is prevented, and the life of the bellows 2 is prevented from being shortened.

[0063] By using a variable displacement hydraulic pump, expensive switching valves and hydraulic units (complicated piping and equipment arrangement) are no longer necessary.

[0064] The control device 14 detects the position of the balance piston 6 by the position sensor 19, and based on the detection result, controls the flow rate of the variable displacement hydraulic pump 25, thereby controlling the movement range of the balance piston 6.

[0065] [Pressure sensor] 1 and 2, a pressure sensor 13 is preferably provided in the gas discharge pipe 10b of this gas compressor to detect the pressure of the discharge gas discharged from inside the bellows 2. By providing the pressure sensor 13, the operation of the suction cutoff valve 11a and the discharge cutoff valve 11b can be controlled by a control device 14 based on the pressure detected by the pressure sensor 13.

[0066] In this case, when the discharge gas pressure detected by the pressure sensor 13 indicates an abnormality, the control device 14 can operate the intake shutoff valve 11a and the discharge shutoff valve 11b to shut off the intake gas and discharge gas being sucked into the bellows 2.

[0067] In this way, when the pressure of the discharge gas indicates an abnormality, the intake gas and the discharge gas are cut off, thereby preventing damage to the bellows 2 and shortening of the life of the bellows 2.

[0068] [Cutting off supply and discharge of pressurized fluid] When the position of the end (cover plate 3) of the bellows 2 detected by the position sensor 19 is outside a predetermined range, the control device 14 can operate the hydraulic unit 18, the supply on-off valve 17b and the discharge on-off valve 17a to cut off the pressurized fluid supplied to the space 7a pressurized by the hydraulic unit 18 and the pressurized fluid discharged from the space 7a pressurized by the hydraulic unit 18.

[0069] In this way, when the position of the end (cover plate 3) of the bellows 2 is outside a specified range, damage to the bellows 2 and a reduction in the lifespan of the bellows 2 can be prevented by blocking the pressurized fluid supplied to the space 7a pressurized by the hydraulic unit 18 and the pressurized fluid discharged from the space 7a pressurized by the hydraulic unit 18.

[0070] [Pressurized fluid sensor] In this gas compressor, if the bellows 2 is damaged and pressurized fluid leaks from the space 7b outside the bellows 2 into the bellows 2, there is a risk that the pressurized fluid will be mixed into the discharge gas. To avoid such a situation, a pressurized fluid sensor (not shown) can be provided in the gas discharge pipe 10b or the bellows 2. In this case, when the control device 14 detects the presence of pressurized fluid in the gas discharge pipe 10b or the bellows 2, it immediately shuts off the discharge gas with the discharge shutoff valve 11b and shuts off the supply and discharge of pressurized fluid with the supply on-off valve 17b and the discharge on-off valve 17a, thereby preventing the pressurized fluid from mixing into the discharge gas.

[0071] Second Embodiment FIG. 5 is a cross-sectional view showing the configuration of a gas compressor according to a second embodiment of the present invention. In this embodiment, as shown in FIG. 5, the change in the volume of the bellows 2 per moving distance L of the balance piston 6 (L*π*R2 2 ) is the change in the volume of the space 7a pressurized by the hydraulic unit 18 (L*π*R1 2 ), and the internal pressure inside the bellows 2 and the space 7b outside the bellows 2 is higher than the internal pressure inside the space 7a, which is pressurized by the hydraulic unit 18. The volume of the space 7b outside the bellows 2 does not change even if the balance piston 6 moves.

[0072] In this embodiment, the balance piston 6 is integrally formed with a reduced diameter portion 6a at one end and an expanded diameter portion 6b at the other end. The reduced diameter portion 6a of the balance piston 6 enters a space 7a outside the bellows 2, and the end face of the expanded diameter portion 6b and the pressurized container 1 form the space 7a that is pressurized by the hydraulic unit 18.

[0073] More specifically, the balance piston 6 defines a space 7b outside the bellows 2 by the reduced diameter portion 6a, the stopper plate 8b, and the inner wall of the pressurized container 1 where the bellows 2 is located. The space 7b outside the bellows 2 is filled with pressurized fluid. The balance piston 6 also forms a space 7a, which is pressurized by the hydraulic unit 18, between the end face of the expanded diameter portion 6b and the inner wall of the pressure vessel 1 where the bellows 2 is not present. In other words, the balance piston 6 divides the interior of the pressurized container 1 into a space 7b outside the bellows 2 and a space 7a pressurized by the hydraulic unit 18. The space 7a pressurized by the hydraulic unit 18 is filled with pressurized fluid.

[0074] The balance piston 6 transmits the boost pressure from the hydraulic boost unit 18 to the pressurized fluid outside the bellows 2. The balance piston 6 is also moved in accordance with changes in the volume inside the bellows 2. These are the same as in the first embodiment described above.

[0075] The balance piston 6 does not have to be cylindrical in shape as long as it has a shape that can form the space 7b outside the bellows 2 and the space 7a that is pressurized by the hydraulic unit 18, and the diameter of the part other than the part that slides against the pressurized container 1 may be expanded or contracted.

[0076] The space 29 between the expanded diameter portion 6b of the balance piston 6 and the stopper plate 8b forming the space 7b outside the bellows 2 is not sealed, but is communicated with the outside via a through hole. This space 29 can be communicated with a pressurized fluid tank (oil tank) to serve as a hydraulic damper. This space 29 is not the "inside of the pressurized container 1."

[0077] In this embodiment, the outer diameter R2 of the balance piston 6 in the space 7b outside the bellows 2 is smaller than the outer diameter R1 in the space 7a pressurized by the hydraulic unit 18, so the volume of the pressurized container 1, which is the sum of the volume of the space 7b outside the bellows 2 and the external volumes of the bellows 2 and the cover plate 3, and the volume of the space 7a pressurized by the hydraulic unit 18, is not constant.

[0078] In this gas compressor, when the pressure in the space 7a is increased by the hydraulic unit 18, the balance piston 6 is moved in a direction corresponding to the decrease in the volume of the bellows 2*(R1 / R2) 2When the pressure in the space 7a pressurized by the hydraulic unit 18 is reduced, the balance piston 6 is moved to a position where the volume of the space 7a pressurized by the hydraulic unit 18 is increased by the amount of increase in the volume of the bellows 2*(R1 / R2) 2 Therefore, the hydraulic unit 18 moves the hydraulic pressure sensor 16 to a position where the volume of the space 7a pressurized by the hydraulic unit 18 decreases.

[0079] The pressure ratio between the space 7b inside and outside the bellows 2 and the space 7a pressurized by the hydraulic unit 18 is the ratio of the change in the volume of the space 7a pressurized by the hydraulic unit 18 per moving distance L of the balance piston 6 to the change in the volume inside the bellows 2. When the balance piston 6 is cylindrical, the pressure ratio between the space 7b and the space 7a is (R1 / R2) 2 It's double.

[0080] The internal pressure of the tank required for compressed hydrogen used in fuel cells is about 720 bar. Since the maximum pressure that can be increased by the hydraulic unit 18 is about 350 bar, if we set it to 300 bar to allow for a safety margin, then to make the pressure inside the bellows 2 720 bar, we obtain 720 = 300 * (R1 / R2). 2 From this, (R1 / R2) 2 =720 / 300, (R1 / R2)=√(720 / 300). (R1 / R2) is approximately 1.55.

[0081] In this embodiment, the balance piston 6 constitutes a booster device based on Pascal's principle. A small change in volume per moving distance L of the balance piston 6 means that the internal pressure that contributes to the moving force of the balance piston 6, i.e., the effective area that receives the force in the moving direction of the balance piston 6, i.e., the projected area in the moving direction of the balance piston 6, is small, and the pressure per area is high. The sum of the pressures in the moving direction acting on the balance piston 6 in the space 7b outside the bellows 2 is equal to the sum of the pressures in the moving direction acting on the balance piston 6 in the space 7a that is pressurized by the hydraulic unit 18.

[0082] In the gas compressor of the first embodiment described above, the internal pressures inside the bellows 2, inside the space 7b outside the bellows 2, and inside the space 7a pressurized by the hydraulic unit 18 are equal, and it is possible to configure the compressor so that the discharge gas is compressed to, for example, about 350 bar. Furthermore, as described above, the gas compressor of the second embodiment can be configured to have high-pressure compression specifications that compress the discharge gas to approximately 720 bar, for example.

[0083] FIG. 5A is a cross-sectional view showing another example of the hydraulic damper for the gas compressor according to the second embodiment. When the space 29 between the expanded diameter portion 6b of the balance piston 6 and the stopper plate 8b forming the space 7b outside the bellows 2 is used as a hydraulic damper, the balance piston 6 may be provided with a protrusion 6c at the base end portion of the reduced diameter portion 6a, and a step 8d into which the protrusion 6c fits may be provided around the periphery of the stopper plate 8b, as shown in Fig. 5A. When the balance piston 6 is moved in a direction away from the bellows 2, the protrusion 6c is separated from the step 8d. At this time, the pressure of the pressurized fluid in the space 29 is equal at every point.

[0084] FIG. 5B is a cross-sectional view showing a state in which another example of the hydraulic damper of the gas compressor of the second embodiment is in operation. 5B, when the balance piston 6 is moved in a direction approaching the bellows 2, the protrusion 6c fits into the stepped portion 8d. At this time, the space between the protrusion 6c of the balance piston 6 and the stopper plate 8b is closed by the stepped portion 8d and the reduced diameter portion 6a, forming a hydraulic damper, which is an enclosed space. The pressurized fluid in the hydraulic damper, which is an enclosed space, is pressed by the balance piston 6, and the pressure therein becomes higher than the pressure of the pressurized fluid in the space 29.

[0085] The pressurized fluid in the hydraulic damper, which is an enclosed space, leaks into space 29 from the gap between the outer circumferential surface of protrusion 6c and the inner circumferential surface of step 8d. If the amount of pressurized fluid leaking at this time is large, the amount by which balance piston 6 is decelerated is small, and the buffering capacity for balance piston 6 is low. If the amount of pressurized fluid leaking is small, the amount by which balance piston 6 is decelerated is large, and the buffering capacity for balance piston 6 is high. The amount of pressurized fluid leakage can be adjusted by utilizing the viscosity effect (viscous flow) or the throttling effect (throttling flow) (the width of the gap between protrusion 6c and step 8d).

[0086] [Gas compressor applications] This gas compressor can be designed to prevent the temperature of the discharge gas (outlet temperature) from becoming too high by taking into consideration the pressure ratio Pd / Ps between the intake gas pressure (inlet pressure) Ps and the discharge gas pressure (outlet pressure) Pd. For example, to increase the pressure of 30 bar gas to 720 bar, multiple gas compressors with a pressure ratio of about 2 can be connected in series to compress the gas as a multi-stage compressor. For example, the first stage can boost the pressure from about 30 bar to about 70 bar, the second stage can boost the pressure from about 70 bar to about 150 bar, the third stage can boost the pressure from about 150 bar to about 300 bar, and the fourth stage can boost the pressure from about 300 bar to about 720 bar. The first to third stages can use the gas compressor of the first embodiment described above, and the fourth stage can use the gas compressor of the second embodiment.

[0087] For example, in fuel cells used in electric vehicles, compressed hydrogen at about 720 bar is supplied from a tank, and this compressed hydrogen must have an extremely high purity (for example, 99.99%). In reciprocating compressors, piston rings and rod packings wear and gasify, which can cause impurities that are difficult to remove to become mixed into the compressed hydrogen. On the other hand, bellows compressors do not have such concerns and are therefore suitable for use in filling hydrogen into tanks that supply compressed hydrogen to fuel cells.

[0088] Furthermore, marine diesel engines that use liquefied gases such as LNG as fuel may require compressed gas at around 300 bar. Compressed gas pressurized to around 300 bar is preferably free of impurities such as lubricating oil so that it can be re-liquefied without any problems. Therefore, a bellows compressor, which does not have the risk of impurities such as lubricating oil being mixed into the discharge gas, is also suitable for use in supplying compressed gas to marine diesel engines. [Explanation of symbols]

[0089] 1. Pressurized container 2 Bellows 3 Lid plate 4a Gas intake hole 5a Intake check valve 4b Gas outlet hole 5b Discharge check valve 6 Balance piston 6a Reduced diameter part 6b Expanded diameter section 6c Protrusion 7a Space outside the bellows 7b Space pressurized by pump 8a Stop plate 8b Stop plate 8c mating hole 8d Step part 9a Damper 9b Damper 10a Gas intake tube 10b Gas discharge pipe 11a Intake shutoff valve 11b Discharge shutoff valve 12a Low-pressure gas tank 12b High-pressure gas tank 13 Pressure Sensor 14 Control device 15 Hydraulic oil supply and drainage hole 15b Hydraulic oil supply hole 15a Hydraulic oil drain hole 16 Hydraulic oil supply and drain pipe 16a Hydraulic oil discharge pipe 16b Hydraulic oil supply pipe 17 2-position switching valve 17a Discharge on-off valve 17b Supply on-off valve 18 Hydraulic unit 19 Position Sensor 20a Position Adjustable Discharge Valve 20b Position adjustment supply valve 21 Cylinder 21a Concave taper part 22 Piston rod 22a Convex tapered part 23 Compression spring 24 Horizontal hole 25 Variable displacement hydraulic pump 26 Electric motor 27 Flow Control Device 28 Accumulator 29 Space between balance piston and stop plate

Claims

1. a pressurized vessel filled with a pressurized fluid; a bellows that partitions a part of the pressurized container, into which the gas to be compressed is supplied, and which is expandable and contractible and whose volume changes; a pump that increases the pressure inside the pressurized container; a balance piston slidably disposed within the pressure vessel, dividing the interior of the pressure vessel into a space outside the bellows and a space pressurized by the pump; Equipped with The balance piston transmits the pressure generated by the pump to the pressurized fluid outside the bellows. A gas compressor characterized by:

2. The amount of change in the volume of the bellows per moving distance of the balance piston is smaller than the amount of change in the volume of the space pressurized by the pump, and the internal pressure inside the bellows and the space outside the bellows is higher than the internal pressure inside the space pressurized by the pump.

2. The gas compressor according to claim 1.

3. The balance piston is integrally formed with a reduced diameter portion on one end side and an expanded diameter portion on the other end side, and the reduced diameter portion is inserted into the space outside the bellows, and the end face of the expanded diameter portion and the pressurizing container form a space that is pressurized by the pump.

3. The gas compressor according to claim 2.

4. a gas inlet into the bellows; a gas discharge hole from within the bellows; Equipped with As the pressurized fluid in the space pressurized by the pump is increased, the pressurized fluid outside the bellows is increased in pressure, the volume of the bellows that has drawn in gas from the gas suction hole is reduced, the balance piston is moved in accordance with the reduction in the volume of the bellows, and the gas in the bellows is discharged from the gas discharge hole.

4. The gas compressor according to claim 1, 2 or 3.

5. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressure vessel.

4. The gas compressor according to claim 1, 2 or 3.

6. a position adjustment discharge valve that is opened to discharge the pressurized fluid in the space outside the bellows to the outside; a position adjustment supply valve that is opened to supply the pressurized fluid into the space outside the bellows; and When the bellows is compressed beyond a predetermined range, the position adjustment discharge valve is opened by a cover plate at the end of the bellows, and the pressurized fluid that has flowed into the space outside the bellows is discharged to the outside via the position adjustment discharge valve. When the bellows is extended beyond a predetermined range, the position adjustment supply valve is opened by the cover plate at the end of the bellows, and the pressurized fluid is supplied into the space outside the bellows via this position adjustment supply valve, thereby compensating for any leaked pressurized fluid.

4. The gas compressor according to claim 1, 2 or 3.

7. The movable range of the balance piston is limited between a pair of stop plates.

4. The gas compressor according to claim 1, 2 or 3.

8. A hydraulic damper is formed between the stop plate and the balance piston.

8. The gas compressor according to claim 7.

9. a pressure sensor that detects the pressure of the discharge gas discharged from inside the bellows; an intake shutoff valve for the gas; a gas discharge shutoff valve; Control means and and When the pressure of the discharge gas detected by the pressure sensor indicates an abnormality, the control means operates the suction cutoff valve and the discharge cutoff valve to cut off the suction gas and the discharge gas being sucked into the bellows.

4. The gas compressor according to claim 1, 2 or 3.

10. a position sensor that detects the position of the balance piston; a supply on-off valve that opens and closes the supply of the pressurized fluid to the space pressurized by the pump; a discharge on-off valve that opens and closes the discharge of the pressurized fluid from the space pressurized by the pump; Control means and and When the position of the balance piston detected by the position sensor is out of a predetermined range, the control means operates the supply on-off valve and the discharge on-off valve to cut off the pressurized fluid supplied to the space pressurized by the pump and the pressurized fluid discharged from the space pressurized by the pump.

4. The gas compressor according to claim 1, 2 or 3.

11. The supply on-off valve and the discharge on-off valve are one two-position switching valve.

11. The gas compressor according to claim 10.

12. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressurized container, a position sensor that detects the position of the balance piston; Control means and and The control means detects the position of the balance piston using the position sensor, and controls the flow rate of the variable displacement hydraulic pump based on the detection result, thereby controlling the movement range of the balance piston.

4. The gas compressor according to claim 1, 2 or 3.

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