gas compressor

Abstract

To prevent a reduction in the lifespan of bellows in a bellows-type gas compressor. [Solution] The system comprises a pressurized container 1 filled with pressurized fluid, a bellows 2 that partitions a portion of the inside of the pressurized container 1 and is supplied with a gas to be compressed, a pump 18 that increases the pressure inside the pressurized container 1, and a balance piston 6 that divides the inside of the pressurized container 1 into a space 7b outside the bellows 2 and a space 7a that is pressurized by the pump 18. The balance piston 6 transmits the pressure increase from the pump 18 to the pressurized fluid outside the bellows.

Description

Technical Field

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

Background Art

[0002] Conventionally, a reciprocating compressor (piston-type compressor) has been used to compress various gases such as gaseous fuels. The reciprocating compressor has problems such as the durability of sliding members such as piston rings and rod packings, and there are further problems such as heat generation when operating without lubricating oil under high-pressure specifications. In order to solve such problems, for example, a compressor that does not use a sliding member can be considered. A bellows (bellows) type compressor is known as a compressor that excludes a sliding member.

[0003] Patent Document 1 describes a bellows-type compressor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An example of a conventional bellows-type compressor is shown in FIG. 6. This bellows-type compressor is configured by arranging a bellows 102 that partitions a part of the inside of a pressure vessel 101 in the pressure vessel 101 with a constant volume. The bellows 102 is formed in a cylindrical shape from a bent flexible material, is stretchable, and has a changing volume. This bellows-type compressor includes a pump 104 that raises the pressure inside the pressure vessel 101 and supplies a pressurized fluid 103 into the pressure vessel 101.

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

[0007] When pressurized fluid 103 is supplied into the pressurized container 101 via the supply valve 110 and the pressure increases, the bellows 102 shortens, and the gas 107 inside the bellows 102 is compressed. The pressurized fluid 103 in the pressurized container 101 and the gas 107 inside the bellows 102 become equal in internal pressure. The compressed gas 107 is discharged from the bellows 102 through the discharge check valve 108 and the gas discharge port 109.

[0008] In this bellows-type compressor, the internal pressure inside the bellows 102 and the internal pressure outside the bellows 102 (inside the pressurized container 101) are equal, creating a pressure balance state. This reduces the stress on the bellows 102 and ensures its durability.

[0009] However, FMEA analysis (Failure Mode and Effects Analysis) revealed that failure of the intake check valve 105 or the discharge check valve 108 would reduce the lifespan of the bellows 102. It was also found that failure of the supply valve 110 or the discharge valve 111 could lead to excessive consumption of pressurized fluid 103, potentially damaging the bellows 102.

[0010] If the intake check valve 105 malfunctions, during the gas intake stroke of gas 107, the maximum displacement of the bellows 102 is detected, pressurized fluid 103 is supplied, and the system transitions to the compression stroke, increasing the operating speed and frequency, and reducing the lifespan of the bellows 102. Also, during the gas discharge stroke of gas 107, the intake check valve 105 becomes open, causing gas to leak out to the gas intake side, resulting in repeated dry running, which increases the operating speed and frequency, and reduces the lifespan of the bellows 102.

[0011] If the discharge check valve 108 malfunctions, during the gas intake stroke of gas 107, the discharge check valve 108 will be in an open state, causing gas to leak out to the gas discharge side and resulting in repeated dry-firing. This increases the operating speed and frequency, and reduces the lifespan of the bellows 102. Similarly, during the gas discharge stroke of gas 107, the discharge check valve 108 will also be in an open state, causing gas to leak out to the gas discharge side and resulting in repeated dry-firing. This increases the operating speed and frequency, and reduces the lifespan of the bellows 102.

[0012] If the supply valve 110 malfunctions, 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 direction of minimum displacement, resulting in a shutdown, excessive consumption of pressurized fluid 103, and potential damage to the bellows 102. Similarly, 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 direction of minimum displacement, resulting in a shutdown, excessive consumption of pressurized fluid 103, and potential damage to the bellows 102.

[0013] If the discharge valve 111 malfunctions, unstable operation may occur during the supply stroke of the pressurized fluid 103, potentially leading to excessive consumption of the pressurized fluid 103 and damage to the bellows 102. Similarly, unstable operation may occur during the discharge stroke of the pressurized fluid 103, potentially leading to excessive consumption of the pressurized fluid 103 and damage to the bellows 102.

[0014] Therefore, the object of the present invention is to provide a bellows-type gas compressor in which the reduction of the bellows' lifespan is prevented.

[0015] Furthermore, other problems of the present invention will become clear from the following description. [Means for solving the problem]

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

[0017] 1. A pressurized container filled with pressurized fluid, Partition a part inside the pressure vessel, and a bellows that is stretchable and has a variable volume and into which a gas to be compressed is supplied, a pump for increasing the pressure inside the pressure vessel, a balance piston that is slidably disposed inside the pressure vessel and divides the inside of the pressure vessel into a space outside the bellows and a space pressurized by the pump and is provided with the balance piston transmits the pressure increase by the pump to the pressurized fluid outside the bellows A gas compressor characterized by the above. 2. The change amount of the volume inside the bellows per unit moving distance of the balance piston is smaller than the change amount of the volume of the space pressurized by the pump, and the internal pressures inside and outside the bellows are higher than the internal pressure inside the space pressurized by the pump. The gas compressor according to claim 1, characterized by the above. 3. The balance piston is integrally formed from a reduced-diameter portion on one end side and an enlarged-diameter portion on the other end side, the reduced-diameter portion enters the space outside the bellows, and the end face of the enlarged-diameter portion and the pressure vessel constitute the space pressurized by the pump. The gas compressor according to claim 2, characterized by the above. 4. a gas suction hole into the bellows, a gas discharge hole from the bellows and is provided with When the pressurized fluid in the space pressurized by the pump is pressurized, the pressurized fluid outside the bellows is pressurized, the volume of the bellows that has sucked gas from the gas suction hole is reduced, the balance piston is moved in response to the reduction of the volume of the bellows, and the gas inside the bellows is discharged from the gas discharge hole. The gas compressor according to claim 1, 2 or 3, characterized by the above. 5. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressure vessel. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. 6. A position-adjustable discharge valve, which, when opened, discharges the pressurized fluid in the space outside the bellows to the outside, A position adjustment supply valve, which, when opened, supplies the pressurized fluid into the space outside the bellows, It has, When the bellows is compressed beyond a predetermined range, the position adjustment discharge valve is opened by the 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 through this 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 to the space outside the bellows through this valve, thereby replenishing the amount of pressurized fluid that has leaked out. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. 7. The range of motion of the balance piston is limited to between a pair of restraining plates. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. 8. A hydraulic damper is formed between the aforementioned restraint plate and the balance piston. The gas compressor according to claim 7, characterized in that it is a gas compressor as described above. 9. A pressure sensor for detecting the pressure of the discharged gas discharged from inside the bellows, The aforementioned gas intake shutoff valve, The aforementioned gas discharge shutoff valve, Control means and It has, When the pressure of the discharged gas detected by the pressure sensor indicates an abnormality, the control means operates the intake shutoff valve and the discharge shutoff valve to shut off the intake gas and discharged gas being drawn into the bellows. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. 10. A position sensor for detecting the position of the balance piston, A supply valve for opening and closing the supply of the pressurized fluid to the space pressurized by the pump, A discharge valve for opening and closing the discharge of the pressurized fluid from the space pressurized by the pump, Control means and It has, When the position of the balance piston detected by the position sensor falls outside a predetermined range, the control means operates the supply valve and the discharge valve to shut off the pressurized fluid supplied to the space pressurized by the pump and the pressurized fluid discharged from the space pressurized by the pump. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. 11. The supply valve and the discharge valve are a single two-position switching valve. The gas compressor according to the above 10, characterized in that it is a gas compressor. 12. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressurized container, A position sensor for detecting the position of the balance piston, Control means and It has, 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 to control the range of movement of the balance piston. A gas compressor according to claim 1, 2, or 3, characterized in that it is the gas compressor described above. [Effects of the Invention]

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

[0019] [Figure 1] Cross-sectional view showing the configuration of a gas compressor according to the first embodiment of the present invention (during gas intake). [Figure 1A] Cross-sectional view showing the configuration of the bellows of the gas compressor. [Figure 1B]Cross-sectional view showing the configuration of the hydraulic damper of the gas compressor. [Figure 1C] Cross-sectional view showing the state in which the hydraulic damper is in operation. [Figure 1D] Cross-sectional view showing the configuration of the position adjustment discharge valve and position adjustment supply valve of the gas compressor. [Figure 2] Cross-sectional view showing the configuration of the gas compressor of the first embodiment (during gas discharge) [Figure 3] Cross-sectional view showing another example of the connection between the pressurized vessel and the pump of the aforementioned gas compressor. [Figure 4] Cross-sectional view showing another example of the gas compressor pump. [Figure 5] Cross-sectional view showing the configuration of a gas compressor according to a second embodiment of the present invention. [Figure 5A] Cross-sectional view showing another example of the hydraulic damper for the gas compressor of the second embodiment described above. [Figure 5B] A cross-sectional view showing another example of the hydraulic damper of the gas compressor of the second embodiment in operation. [Figure 6] Cross-sectional view showing an example of a conventional bellows-type compressor. [Modes for carrying out the invention]

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

[0021] [First Embodiment] [Gas compressor configuration] Figure 1 is a cross-sectional view showing the configuration of a gas compressor according to the first embodiment of the present invention (during gas intake).

[0022] As shown in Figure 1, this gas compressor has a pressurized container 1 filled with pressurized fluid, and a bellows 2 that partitions a portion of the inside of the pressurized container 1. In this embodiment, the volume of the pressurized container 1 is constant. Figure 1A is a cross-sectional view showing the configuration of the bellows of the gas compressor. The bellows 2 is formed in a cylindrical shape from a flexible material, and as shown in Figure 1A, its side surface is bent into multiple pleats, allowing it to expand and contract in the axial direction, and its volume changes as it expands and contracts.

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

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

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

[0026] A gas intake port 4a is formed in the wall of the pressurized container 1 at the portion where the bellows 2 is joined, communicating with the sealed space inside the bellows 2. This gas intake port 4a is equipped with an intake check valve 5a to stop the outflow of gas from the gas intake port 4a. In addition, a gas discharge port 4b is formed in the wall of the pressurized container 1 at the portion where the bellows 2 is joined, communicating with the sealed space inside the bellows 2. This gas discharge port 4b is equipped with a discharge check valve 5b to stop the inflow of gas into the gas discharge port 4b.

[0027] The pressurized container 1 is provided with a hydraulic fluid supply port 15b and a hydraulic fluid discharge port 15a. A hydraulic fluid supply pipe 16b is connected to the hydraulic fluid supply port 15b, and a hydraulic fluid discharge pipe 16a is connected to the hydraulic fluid discharge port 15a. The hydraulic fluid supply pipe 16b is connected to a hydraulic unit 18, which is a pump, via a supply valve 17b. The hydraulic fluid discharge pipe 16a is connected to the hydraulic unit 18 via a discharge valve 17a. The hydraulic unit 18, the supply valve 17b, and the discharge valve 17a are operated and controlled by a control device 14, which is a control means. The inside of the pressurized container 1 is pressurized by the hydraulic unit 18.

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

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

[0030] In this embodiment, the sum of the volume of the space 7b outside the bellows 2 and the outer volumes 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 outer volume of the balance piston 6, and remains 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 can be, for example, the hydraulic fluid of a hydraulic system.

[0032] The balance piston 6 can limit its range of motion to the space between a pair of restraining plates 8a and 8b. Preferably, hydraulic dampers 9a and 9b are formed between the restraining plates 8a and 8b and the balance piston 6. The hydraulic dampers 9a and 9b are an intake hydraulic damper using pressurized fluid in a space 7a pressurized by the hydraulic unit 18, and a discharge hydraulic damper using pressurized fluid in a space 7b outside the bellows 2.

[0033] Figure 1B is a cross-sectional view showing the configuration of the hydraulic damper of the gas compressor. Since the hydraulic dampers 9a and 9b have the same configuration and are arranged in opposite directions, we will describe the discharge hydraulic damper 9b, which uses pressurized fluid in the space 7b outside the bellows 2, as shown in Figure 1B.

[0034] The balance piston 6 is provided with a projection 6c that fits into a fitting hole 8c formed in the central part of the restraint plate 8b. As shown in Figure 1B, when the balance piston 6 is moved away from the bellows 2, the projection 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 all points.

[0035] Figure 1C is a cross-sectional view showing the state in which the hydraulic damper is in operation. As shown in Figure 1C, when the balance piston 6 is moved toward the bellows 2, the projection 6c engages with the fitting hole 8c. At this time, the space between the balance piston 6 and the retaining plate 8b is closed by the pressurized container 1 and the projection 6c, forming a closed space called a hydraulic damper 9b. The pressurized fluid in this closed space, the hydraulic damper 9b, is pressed by the balance piston 6, resulting in a pressure P2 that is higher than the pressure P1 of the pressurized fluid in the space 7b outside the bellows 2.

[0036] The pressurized fluid inside the closed space of the hydraulic damper 9b leaks into the space 7b outside the bellows 2 through the gap between the outer surface of the projection 6c and the inner surface of the fitting hole 8c, as shown by arrow P in Figure 1C. If the amount of pressurized fluid leakage is large, the amount of deceleration of the balance piston 6 is small, and the buffering capacity for the balance piston 6 is low. If the amount of pressurized fluid leakage is small, the amount of deceleration of the balance piston 6 is large, and the buffering capacity for the balance piston 6 is high. The amount of pressurized fluid leakage can be adjusted by utilizing the viscous effect (viscous flow) and the throttling effect (throttling flow) (the width of the gap between the projection 6c and the fitting hole 8c).

[0037] In this gas compressor, since the range of motion of the balance piston 6 is limited to a certain range, 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. This prevents damage to the bellows 2 and prevents a reduction in the lifespan of the bellows 2. Furthermore, in this gas compressor, the hydraulic dampers 9a and 9b reduce the hydraulic fluctuation load on the bellows 2, resulting in smoother operation of the bellows 2. This prevents damage to the bellows 2 and reduces its lifespan.

[0038] A gas intake pipe 10a is connected to the gas intake port 4a. The gas intake pipe 10a is connected to the low-pressure gas tank 12a via the intake shut-off valve 11a. A gas discharge pipe 10b is connected to the gas discharge port 4b. The gas discharge pipe 10b is connected to the high-pressure gas tank 12b via a discharge shut-off valve 11b. The suction shut-off valve 11a and the discharge shut-off valve 11b are operated under the control of a control device 14. The gas is, for example, hydrogen, but is not limited to this; it may be any other type of fuel gas.

[0039] The space 7a, which is pressurized by the hydraulic unit 18, is supplied with pressurized fluid from the hydraulic fluid supply pipe 16b via the supply valve 17b, which is opened by the hydraulic unit 18. Furthermore, the space 7a, which is pressurized by the hydraulic unit 18, is depressurized by the hydraulic unit 18, and the pressurized fluid is discharged and recovered from the hydraulic fluid discharge pipe 16a via the opened discharge valve 17a.

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

[0041] The pressurized container 1 can be equipped with a position sensor 19 for detecting the position of the balance piston 6. Various types of position sensors can be used as the position sensor 19, such as optical sensors, acoustic sensors, and contact sensors. The detection result from the position sensor 19 is sent to the control device 14.

[0042] The control device 14 uses the position sensor 19 to detect when the balance piston 6 is at the position where the volume of the bellows 2 is at its maximum. When this position is detected, the control device 14 closes the discharge valve 17a to stop the discharge of pressurized fluid from the space 7a, which is pressurized by the hydraulic unit 18. At the same time, the control device 14 opens the supply valve 17b to start supplying pressurized fluid to the space 7a, which is pressurized by the hydraulic unit 18.

[0043] Figure 2 is a cross-sectional view showing the configuration of the gas compressor of the first embodiment (during gas discharge).

[0044] The control device 14 uses the position sensor 19 to detect when the balance piston 6 is in the position that minimizes the volume of the bellows 2. When this position is detected, the control device 14 closes the supply valve 17b to stop the supply of pressurized fluid to the space 7a, which is pressurized by the hydraulic unit 18. At the same time, the control device 14 opens the discharge valve 17a to start discharging the pressurized fluid from the space 7a, which is pressurized by the hydraulic unit 18. 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.

[0045] In this gas compressor, when the space 7a, which is pressurized by the hydraulic unit 18, is pressurized, compressed pressurized fluid is supplied according to the compressibility ratio k of the pressurized fluid, the balance piston 6 moves slightly toward the bellows 2, and the pressurized fluid in the space 7b outside the bellows 2 is also compressed and pressurized. In other words, the pressure increase from the hydraulic boosting unit 18 is transmitted to the pressurized fluid outside the bellows 2 by the balance piston 6. At this time, according to Boyle's Law (PV=nRT, where P is pressure, V is volume, n is the amount of substance of the gas, R is the gas constant, and T is the absolute temperature), the pressure and volume of the gas are inversely proportional, so as shown in Figure 2, the volume of the bellows 2 that has drawn in gas from the gas intake port 4a is reduced. Then the balance piston 6 moves to a position where the volume of the space 7a that is pressurized by the hydraulic boosting 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 to a pressure equal to the internal pressure of the space 7b outside the bellows 2 and is discharged from the gas discharge port 4b.

[0046] When the pressure inside space 7a, which is pressurized by the hydraulic unit 18, decreases, the pressure inside space 7b outside the bellows 2 also decreases. At this time, as shown in Figure 1, gas is drawn in from the gas intake port 4a, and the volume of the bellows 2 increases. Then, the balance piston 6 moves to a position where the volume of space 7a, which is pressurized by the hydraulic unit 18, decreases by the amount of the increase in the volume inside the bellows 2. The hydraulic unit 18 discharges and recovers the pressurized fluid that is equivalent to the increase in the volume of the bellows 2. The gas drawn into the bellows 2 is at a pressure equal to the internal pressure of space 7b outside the 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 and discharge of high-pressure gas due to the contraction of the volume of the bellows 2 are repeated, and the high-pressure discharge gas is filled into the high-pressure gas tank 12b.

[0048] The control device 14 may also 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 amount of pressurized fluid supplied to and discharged from the space 7a, which is pressurized by the hydraulic unit 18, according to this movement speed.

[0049] In this gas compressor, the presence of a balance piston 6 prevents pulsations and shocks propagating through the pressurized fluid from directly affecting the bellows 2, thereby preventing damage to the bellows 2 and reducing its lifespan. 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 preventing a reduction in 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 range of movement. Figure 1D is a cross-sectional view showing the configuration of the position adjustment discharge valve and position adjustment 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, a position adjustment discharge valve 20a is provided, as shown in Figure 1D, 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 pressurized fluid into the space 7b outside the bellows 2.

[0051] The position-adjustable discharge valve 20a is located in the space 7b outside the bellows 2, on the side of one open end of the bellows 2 (the upper part in Figures 1 and 1D). The position-adjustable discharge valve 20a is composed of a cylinder 21 and a piston rod 22 disposed within the cylinder 21. The piston rod 22 is slidable in the axial direction while its outer surface remains in close contact with the inner surface of the cylinder barrel 21. The cylinder barrel 21 has an open tip, and an inwardly opening concave tapered portion 21a is formed at an inward position of the tip. The piston rod 22 has its tip protruding from the tip of the cylinder barrel 21, and a convex tapered portion 22a corresponding to the concave tapered portion 21a is formed on the shaft portion. When the piston rod 22 is moved toward the tip, the convex tapered portion 22a fits into the concave tapered portion 21a of the cylinder barrel 21, closing the space between the convex tapered portion 22a and the concave tapered portion 21a. A compression spring 23 is positioned inside the cylinder barrel 21, pressing the piston rod 22 toward its tip. The pressure exerted by this compression spring 23 closes the space between the convex tapered portion 22a and the concave tapered portion 21a. When the tip 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 separate, and the space between them is opened. The tip of the piston rod 22 is pressed against the end portion of the cover plate 3 of the bellows 2. The cylinder 21 has a lateral 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 separate and the space between them is opened, the space 7b outside the bellows 2 is connected to the outside of the pressurized container 1 via the space between the convex tapered portion 22a and the concave tapered portion 21a, the inside of the cylinder 21, and the lateral hole 24. The pressurized fluid in the space 7b outside the bellows 2 is discharged to the outside (into the atmosphere) through this horizontal hole 24.

[0052] The position adjustment supply valve 20b has a configuration that is the opposite direction of the position adjustment discharge valve 20a (up and down in Figures 1 and 1D), and is located in the space 7b outside the bellows 2, on the side of the cover plate 3 of the bellows 2 (the lower part in Figures 1 and 1D). The position adjustment supply valve 20b is composed of a cylinder 21 and a piston rod 22 arranged inside the cylinder 21. The piston rod 22 is slidable in the axial direction while its outer surface remains in close contact with the inner surface of the cylinder barrel 21. The cylinder barrel 21 has an open tip, and an inwardly opening concave tapered portion 21a is formed at an inward position of the tip. The piston rod 22 has its tip protruding from the tip of the cylinder barrel 21, and a convex tapered portion 22a corresponding to the concave tapered portion 21a is formed on the shaft portion. When the piston rod 22 is moved toward the tip, the convex tapered portion 22a fits into the concave tapered portion 21a of the cylinder barrel 21, closing the space between the convex tapered portion 22a and the concave tapered portion 21a. A compression spring 23 is positioned inside the cylinder barrel 21, pressing the piston rod 22 toward its tip. The pressure exerted by this compression spring 23 closes the space between the convex tapered portion 22a and the concave tapered portion 21a. When the tip 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 separate, and the space between them is opened. The tip of the piston rod 22 is pressed against the end portion of the cover plate 3 of the bellows 2. The cylinder 21 has a lateral 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 separate and the space between them is opened, the space 7b outside the bellows 2 is connected to the outside of the pressurized container 1 via the space between the convex tapered portion 22a and the concave tapered portion 21a, the inside of the cylinder 21, and the lateral hole 24. Pressurized fluid is supplied from this horizontal hole 24 into the space 7b outside the bellows 2.

[0053] When pressurized fluid flows from the space 7a, which is pressurized by the hydraulic unit 18, into the space 7b outside the bellows 2, the range of movement of the bellows 2 shifts in a direction that compresses the bellows 2. Therefore, when it is compressed to its maximum extent, it may be compressed outside the predetermined range and may break. When the bellows 2 is compressed beyond a predetermined range, the cover plate 3 of the bellows 2 opens the position adjustment discharge valve 20a, and the pressurized fluid that has flowed into the space 7b outside the bellows 2 is discharged to the outside through this position adjustment discharge valve 20a.

[0054] When pressurized fluid flows out from the space 7b outside the bellows 2 into the space 7a which is pressurized by the hydraulic unit 18, the range of movement of the bellows 2 shifts in a direction that extends the bellows 2. Therefore, when it is most extended, it may extend beyond the predetermined range and be damaged. When the bellows 2 is extended beyond a predetermined range, the cover plate 3 of the bellows 2 opens the position adjustment supply valve 20b, and pressurized fluid is supplied to the space 7b outside the bellows 2 via this position adjustment supply valve 20b, replenishing the leaked pressurized fluid. The pressurized fluid supplied via the position adjustment supply valve 20b is at a slightly higher pressure than the gas drawn into the bellows 2.

[0055] In this way, the movable range of the bellows 2 is autonomously controlled between the position in which the position adjustment discharge valve 20a is opened and the position in which the adjustment supply valve 20b is opened, thus preventing damage caused by compression and extension going outside a predetermined range.

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

[0057] [Other examples of connecting a pressurized vessel to a pump] Figure 3 is a cross-sectional view showing another example of the connection between the pressurized vessel and the pump of the gas compressor. In this gas compressor, as shown in Figure 3, a two-position switching valve 17 can be provided instead of the supply valve 17b and the discharge valve 17a. In this case, a hydraulic fluid supply and discharge hole 15 is provided in the wall of the pressurized container 1 in the portion that forms the space 7a pressurized by the hydraulic unit 18, and a hydraulic fluid supply and discharge pipe 16 is connected to it, and this hydraulic fluid supply and discharge pipe 16 is connected to a two-position switching valve 17. One end of the hydraulic fluid supply pipe 16b and the hydraulic fluid discharge pipe 16a are connected to the two-position switching valve 17, and the other ends of these hydraulic fluid supply pipe 16b and hydraulic fluid discharge pipe 16a are connected to the hydraulic unit 18. The two-position switching valve 17 is operated under the control of the control device 14.

[0058] Pressurized fluid is supplied to the space 7a, which is pressurized by the hydraulic unit 18, via the hydraulic fluid supply pipe 16b, the two-position switching valve 17, and the hydraulic fluid supply and discharge pipe 16. At this time, the hydraulic unit 18 pressurizes the space 7a that is pressurized by the hydraulic unit 18 and supplies pressurized fluid. Furthermore, pressurized fluid is discharged and recovered from the space 7a, which is pressurized by the hydraulic unit 18, via the hydraulic fluid supply and discharge pipe 16, the two-position switching valve 17, and the hydraulic fluid discharge pipe 16a. At this time, the hydraulic unit 18 also reduces the pressure inside the space 7a that is pressurized by the hydraulic unit 18, and discharges and recovers the pressurized fluid.

[0059] Furthermore, if it is necessary to shut off both the supply and discharge of hydraulic fluid, a three-position switching valve is provided instead of the supply valve 17b and the discharge valve 17a, and the third position, to which neither the hydraulic fluid supply pipe 16b nor the hydraulic fluid discharge pipe 16a is connected, is closed.

[0060] [Variable Displacement Hydraulic Pump] Figure 4 is a cross-sectional view showing another example of the gas compressor pump. The pump can be a variable displacement hydraulic pump 25, as shown in Figure 4. The variable displacement hydraulic pump 25 is connected to the hydraulic fluid supply and discharge port 15 of the pressurized container 1 by a hydraulic fluid supply and discharge pipe 16.

[0061] The variable displacement hydraulic pump 25 is capable of flow control, and its supply and discharge flow rates can be controlled. The variable displacement hydraulic pump 25 is driven by an electric motor 26, and the supply and discharge flow rates of the pressurized fluid are controlled by a flow control device 27. The electric motor 26 and the flow control device 27 are operated under the control of the control device 14.

[0062] The variable displacement hydraulic pump 25 is equipped with a hydraulic accumulator 28, which absorbs pulsations and shocks propagating through the pressurized fluid in the piping. By absorbing pulsations and shocks propagating through the pressurized fluid inside the piping, damage to the bellows 2 is prevented, thus preventing a reduction in the lifespan of the bellows 2.

[0063] By using a variable displacement hydraulic pump, expensive switching valves become unnecessary, and hydraulic units (complex piping, equipment deployment) are eliminated.

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

[0065] [Pressure Sensor] It is preferable to provide a pressure sensor 13 in the gas discharge pipe 10b of this gas compressor, as shown in Figures 1 and 2, to detect the pressure of the discharge gas discharged from inside the bellows 2. By providing the pressure sensor 13, the intake shut-off valve 11a and the discharge shut-off valve 11b can be operated by the 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 suction shut-off valve 11a and the discharge shut-off valve 11b to shut off the suction gas and discharge gas drawn into the bellows 2.

[0067] In this way, when the discharge gas pressure shows an abnormality, the intake gas and discharge gas can be shut off, thereby preventing damage to the bellows 2 and preventing a reduction in the lifespan of the bellows 2.

[0068] [Shutoff of supply and discharge of pressurized fluid] When the position of the end of the bellows 2 (cover plate 3) detected by the position sensor 19 goes outside a predetermined range, the control device 14 operates the hydraulic unit 18, the supply valve 17b, and the discharge valve 17a to shut 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 moves outside a predetermined range, 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 are blocked, thereby preventing damage to the bellows 2 and preventing a reduction in the lifespan of the bellows 2.

[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 this pressurized fluid will mix with the discharge gas. To avoid such a situation, a pressurized fluid sensor (not shown) can be installed in the gas discharge pipe 10b or in the bellows 2. In this case, when the control device 14 detects the presence of pressurized fluid in the gas discharge pipe 10b or in the bellows 2, it can immediately shut off the discharge gas with the discharge shut-off valve 11b and shut off the supply and discharge of pressurized fluid with the supply shut-off valve 17b and the discharge shut-off valve 17a, thereby preventing the pressurized fluid from mixing with the discharge gas.

[0071] [Second Embodiment] Figure 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 Figure 5, the change in volume within the bellows 2 per unit travel distance L of the balance piston 6 (L*π*R²) 2 ) is the change in volume of the space 7a that is pressurized by the hydraulic unit 18 (L*π*R1 2 The volume of the space 7b outside the bellows 2 is smaller than the volume of the space 7a outside the bellows 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. Note that the volume of the space 7b outside the bellows 2 does not change even when the balance piston 6 moves.

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

[0073] More specifically, the balance piston 6, with its reduced diameter portion 6a, its restraining plate 8b, and the inner wall of the pressurized container 1 in the portion where the bellows 2 is located, forms a space 7b outside the bellows 2. The space 7b outside the bellows 2 is filled with pressurized fluid. Furthermore, the balance piston 6 forms a space 7a that is pressurized by the hydraulic unit 18 through the end face of the enlarged diameter portion 6b and the inner wall of the pressurizing container 1 in the portion where the bellows 2 is absent. In other words, the balance piston 6 divides the inside of the pressurized container 1 into the space 7b outside the bellows 2 and the space 7a which is pressurized by the hydraulic unit 18. The space 7a which is pressurized by the hydraulic unit 18 is filled with pressurized fluid.

[0074] The balance piston 6 transmits the pressure increase from the hydraulic pressure boosting unit 18 to the pressurized fluid outside the bellows 2. The balance piston 6 also moves in response to changes in the volume inside the bellows 2. These are the same as in the first embodiment described above.

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

[0076] The space 29 between the enlarged diameter portion 6b of the balance piston 6 and the restraining plate 8b that forms the space 7b outside the bellows 2 is not a sealed space, but is open to the outside through a through hole. This space 29 can be connected to a pressurized fluid tank (oil tank) and used as a hydraulic damper. This space 29 is not "inside 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 that is pressurized by the hydraulic unit 18. Therefore, the volume of the pressurized container 1, which is the sum of the volume of the space 7b outside the bellows 2 and the outer volumes of the bellows 2 and the cover plate 3, and the volume of the space 7a that is pressurized by the hydraulic unit 18, is not constant.

[0078] In this gas compressor, when the pressure in the space 7a, which is pressurized by the hydraulic unit 18, increases, the balance piston 6 adjusts for the decrease in volume within the bellows 2*(R1 / R2) 2The piston is moved to a position where the volume of the space 7a, which is pressurized by the hydraulic unit 18, increases. Also, when the pressure inside the space 7a, which is pressurized by the hydraulic unit 18, decreases, the balance piston 6 moves to a position where the volume inside the bellows 2 increases by *(R1 / R2) 2 It is then moved to a position where the volume of the space 7a, which is pressurized by the hydraulic unit 18, is reduced.

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

[0080] The required tank pressure for compressed hydrogen used in fuel cells is approximately 720 bar. Since the maximum pressure achieved by the hydraulic unit 18 is approximately 350 bar, and considering a safety margin of 300 bar, to reach 720 bar inside bellows 2, the calculation is 720 = 300 * (R1 / R2). 2 (R1 / R2) 2 = 720 / 300, and (R1 / R2) = √(720 / 300). (R1 / R2) is approximately 1.55.

[0081] In this embodiment, the balance piston 6 constitutes a power assist device based on Pascal's principle. The small change in volume per unit travel distance L of the balance piston 6 means that the internal pressure contributing to the movement force of the balance piston 6, that is, the effective area subjected to the force in the direction of movement of the balance piston 6, that is, the projected area of ​​the balance piston 6 in the direction of movement, is small, and the pressure per unit area is high. The sum of the pressures in the direction of movement acting on the balance piston 6 in the space 7b outside the bellows 2 is equal to the sum of the pressures in the direction of movement acting on the balance piston 6 in the space 7a which is pressurized by the hydraulic unit 18.

[0082] In the gas compressor of the first embodiment described above, the internal pressure is the same in the space 7b inside the bellows 2, the space 7b outside the bellows 2, and the space 7a pressurized by the hydraulic unit 18. For example, it is possible to compress the discharge gas to about 350 bar. Furthermore, in the gas compressor of the second embodiment, as described above, it is possible to have a high-pressure compression specification that compresses the discharge gas to approximately 720 bar.

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

[0084] Figure 5B is a cross-sectional view showing another example of the hydraulic damper of the gas compressor of the second embodiment in operation. As shown in Figure 5B, when the balance piston 6 is moved toward the bellows 2, the projection 6c engages with the stepped portion 8d. At this time, the space between the projection 6c of the balance piston 6 and the restraining plate 8b is closed by the stepped portion 8d and the reduced diameter portion 6a, forming a sealed space called a hydraulic damper. The pressurized fluid in this sealed space called the hydraulic damper is pressed by the balance piston 6, and its pressure becomes higher than the pressure of the pressurized fluid in the space 29.

[0085] The pressurized fluid inside the sealed hydraulic damper leaks into the space 29 through the gap between the outer surface of the projection 6c and the inner surface of the stepped portion 8d. When the amount of pressurized fluid leakage is large, the amount of deceleration of the balance piston 6 is small, and the buffering capacity for the balance piston 6 is low. When the amount of pressurized fluid leakage is small, the amount of deceleration of the balance piston 6 is large, and the buffering capacity for the balance piston 6 is high. The amount of pressurized fluid leakage can be adjusted by utilizing the viscous effect (viscous flow) or the throttling effect (throttling flow) (the width of the gap between the projection 6c and the stepped portion 8d).

[0086] [Applications of gas compressors] This gas compressor can be designed to prevent the discharge gas temperature (outlet temperature) from becoming too high by considering 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 approximately 2 can be connected in series to create a multi-stage compressor. For example, the first stage can boost the voltage from approximately 30 bar to approximately 70 bar, the second stage from approximately 70 bar to approximately 150 bar, the third stage from approximately 150 bar to approximately 300 bar, and the fourth stage from approximately 300 bar to approximately 720 bar. The first to third stages can use the gas compressor of the first embodiment described above. 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 around 720 bar is supplied from a tank. This compressed hydrogen requires extremely high purity (for example, 99.99%). In reciprocating compressors, wear and gasification of piston rings and rod packing can lead to the introduction of difficult-to-remove impurities into the compressed hydrogen. On the other hand, bellows-type compressors do not pose such a risk, making them suitable for applications such as filling tanks that supply compressed hydrogen to fuel cells with hydrogen.

[0088] Furthermore, marine diesel engines that use liquefied gases such as LNG as fuel sometimes require compressed gas at around 300 bar. It is desirable that compressed gases pressurized to around 300 bar be free from impurities such as lubricating oil to avoid hindering reliquefaction. Therefore, bellows-type compressors, which are free from the risk of impurities such as lubricating oil contaminating the discharged gas, are also suitable for supplying compressed gas to marine diesel engines. [Explanation of Symbols]

[0089] 1. Pressurized container 2 Bellows 3 Lid plate 4a Gas intake port 5a Intake check valve 4b Gas discharge port 5b Discharge check valve 6 Balance pistons 6a Reduced diameter part 6b Enlarged diameter section 6c Protrusion 7a Space outside the bellows 7b Space pressurized by the pump 8a Stop plate 8b Stop plate 8c mating hole 8d Step part 9a Damper 9b Damper 10a Gas intake pipe 10b Gas discharge pipe 11a Intake shut-off valve 11b Discharge shut-off 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 fluid discharge hole 16 Hydraulic oil supply and drain pipe 16a Hydraulic fluid discharge pipe 16b Hydraulic fluid supply pipe 17. Two-position switching valve 17a Discharge valve 17b Supply 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 section 23 Compression spring 24 Horizontal hole 25 Variable Displacement Hydraulic Pumps 26 Electric motor 27 Flow control device 28 Accumulator 29 Space between the balance piston and the brake plate

Claims

1. A pressurized container filled with pressurized fluid, A portion of the above-mentioned pressurized container is partitioned, and the gas to be compressed is supplied to the inside, and a bellows that is expandable and expandable and whose volume changes, A pump for increasing the pressure inside the aforementioned pressurized container, A balance piston is slidably disposed within the pressurized container and divides the inside of the pressurized container into a space outside the bellows and a space pressurized by the pump. Equipped with, The balance piston transmits the pressure increase from the pump to the pressurized fluid outside the bellows. A gas compressor characterized by the following features.

2. The balance piston is configured such that the change in volume within the bellows per unit distance traveled is smaller than the change in volume of the space pressurized by the pump, and the internal pressure in the space inside and outside the bellows is higher than that in the space pressurized by the pump. The gas compressor according to claim 1.

3. The balance piston is integrally formed from a reduced-diameter portion at one end and an enlarged-diameter portion at the other end, with the reduced-diameter portion entering the space outside the bellows, and the end face of the enlarged-diameter portion and the pressurizing container forming a space that is pressurized by the pump. The gas compressor according to claim 2, characterized in that way.

4. The gas intake port into the bellows, The gas discharge port from inside the bellows and Equipped with, As the pressurized fluid in the space pressurized by the pump is increased in pressure, the pressurized fluid outside the bellows is also increased in pressure, the volume of the bellows that has drawn in gas through the gas intake port is reduced, the balance piston moves in accordance with the reduction in the volume of the bellows, and the gas inside the bellows is discharged through the gas discharge port. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

5. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressurized container. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

6. A position-adjustable discharge valve, which, when opened, discharges the pressurized fluid in the space outside the bellows to the outside, A position adjustment supply valve, which, when opened, supplies the pressurized fluid into the space outside the bellows, It has, When the bellows is compressed beyond a predetermined range, the position adjustment discharge valve is opened by the 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 through this 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 to the space outside the bellows through this valve, thereby replenishing the amount of pressurized fluid that has leaked out. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

7. The range of motion of the balance piston is limited to between a pair of restraining plates. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

8. A hydraulic damper is formed between the aforementioned restraint plate and the balance piston. The gas compressor according to claim 7, characterized in that it is as described above.

9. A pressure sensor for detecting the pressure of the discharged gas discharged from inside the bellows, The aforementioned gas intake shutoff valve, The aforementioned gas discharge shutoff valve, Control means and It has, The control means operates the intake shutoff valve and the discharge shutoff valve to shut off the intake gas and discharge gas drawn into the bellows when the pressure of the discharge gas detected by the pressure sensor indicates an abnormality. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

10. A position sensor for detecting the position of the balance piston, A supply valve for opening and closing the supply of the pressurized fluid to the space pressurized by the pump, A discharge valve for opening and closing the discharge of the pressurized fluid from the space pressurized by the pump, Control means and It has, When the position of the balance piston detected by the position sensor falls outside a predetermined range, the control means operates the supply valve and the discharge valve to shut off the pressurized fluid supplied to the space pressurized by the pump and the pressurized fluid discharged from the space pressurized by the pump. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

11. The supply valve and the discharge valve are a single two-position switching valve. The gas compressor according to claim 10, characterized in that way.

12. The pump is a variable displacement hydraulic pump that increases and decreases the pressure inside the pressurized container, A position sensor for detecting the position of the balance piston, Control means and It has, 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 to control the range of movement of the balance piston. A gas compressor according to claim 1, 2, or 3, characterized in that it is as described above.

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