gas compressor

Abstract

To provide a gas compressor that can switch whether to compress gas in one stage or two stages.SOLUTION: A gas compressor 1A includes a first gas booster 2A and a second gas booster 2B. The first gas booster 2A includes: a first gas piston 33 facing a first compression chamber 3a; and a first hydraulic piston 44 separating a first driving chamber 4a and a second driving chamber 4b, and connected to the first gas piston 33. The second gas booster 2B includes: a second gas piston 37 facing a second compression chamber 3b to which gas is supplied from the first compression chamber 3a; and a second hydraulic piston 48 separating a third driving chamber 4c and a fourth driving chamber 4d, and connected to the second gas piston 37. The gas compressor 1A includes an opening / closing valve 82 provided in a communication passage 81 establishing communication between the first driving chamber 4a and the third driving chamber 4c, or establishing communication between the second driving chamber 4b and the fourth driving chamber 4d.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a hydraulically driven gas compressor and an operation method of the gas compressor.

Background Art

[0002] Conventionally, hydraulically driven gas compressors are known. For example, such gas compressors are used as large-scale gas compressors.

[0003] For example, Patent Document 1 discloses a gas compressor 100 that compresses gas in two stages as shown in Figure 7. Specifically, the gas compressor 100 includes a first structure 200 and a second structure 300. Each of the first structure 200 and the second structure 300 may also be referred to as a gas booster in some cases.

[0004] The first structure 200 includes a first gas piston 220 facing the first compression chamber 210, and a first hydraulic piston 250 that partitions the first drive chamber 230 and the second drive chamber 240. The first hydraulic piston 250 is connected to the first gas piston 220 by a rod 260 that traverses the first drive chamber 230.

[0005] Similarly, the second structure 300 includes a second gas piston 320 facing the second compression chamber 310, and a second hydraulic piston 350 that partitions the third drive chamber 330 and the fourth drive chamber 340. The second hydraulic piston 350 is connected to the second gas piston 320 by a rod 360 that traverses the third drive chamber 330.

[0006] The first compression chamber 210 and the second compression chamber 310 communicate with each other via a gas communication passage 400. Therefore, gas is supplied from the first compression chamber 210 to the second compression chamber 310. Further, the first drive chamber 230 and the third drive chamber 330 communicate with each other via a hydraulic communication passage 500.

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Special Publication No. 2021-522446 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the gas compressor 100 shown in Figure 7 can only compress the gas in two stages.

[0009] Therefore, the present disclosure aims to provide a gas compressor that can switch between compressing gas in one stage or in two stages, and a method for operating the gas compressor. [Means for solving the problem]

[0010] This disclosure provides a gas compressor comprising, from one side, a first gas booster including a first gas piston facing a first compression chamber and a first hydraulic piston that partitions a first drive chamber and a second drive chamber and is connected to the first gas piston by a rod that crosses the first drive chamber; a second gas booster including a second gas piston facing a second compression chamber from which gas is supplied from the first compression chamber and a second hydraulic piston that partitions a third drive chamber and a fourth drive chamber and is connected to the second gas piston by a rod that crosses the third drive chamber; and an on / off valve provided in a communication passage that connects the first drive chamber and the third drive chamber or the second drive chamber and the fourth drive chamber.

[0011] This disclosure also provides, in another aspect, a method for operating a gas compressor including a first gas booster and a second gas booster, which switches between an operating mode in which the gas is compressed in two stages using both the first gas booster and the second gas booster, and an operating mode in which the gas is compressed in one stage using only the second gas booster without using the first gas booster. [Effects of the Invention]

[0012] This disclosure provides a gas compressor that can switch between compressing gas in one stage or in two stages, and a method for operating the gas compressor. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of the gas compressor according to the first embodiment. [Figure 2] This figure shows the state of the gas compressor before it was shut down. [Figure 3] This figure shows the gas compressor with the intermediate chamber filled with hydraulic fluid. [Figure 4] This is a schematic diagram of a gas compressor as a modified example of the first embodiment. [Figure 5] This is a schematic diagram of the gas compressor according to the second embodiment. [Figure 6] This is a schematic diagram of a gas compressor as a modified example of the second embodiment. [Figure 7] This is a schematic diagram of a conventional gas compressor. [Modes for carrying out the invention]

[0014] <First Embodiment> Figure 1 shows a gas compressor 1A according to the first embodiment. The gas compressor 1A includes a first gas booster 2A and a second gas booster 2B, and compresses the gas in two or one stage. The gas to be compressed is not particularly limited, but hydrogen is an example.

[0015] Furthermore, the gas compressor 1A includes a hydraulic pump 61 that supplies hydraulic fluid to either the first gas booster 2A or the second gas booster 2B, an electric motor 62 that drives the hydraulic pump 61, and a control device 9 that controls the hydraulic pump 61 via the electric motor 62.

[0016] The first gas booster 2A includes a gas cylinder 3A, a hydraulic cylinder 4A and a rod 55, and the second gas booster 2B includes a gas cylinder 3B, a hydraulic cylinder 4B and a rod 56. The major difference between the first gas booster 2A and the second gas booster 2B lies in the size of the gas cylinders 3A and 3B. Specifically, the diameter of a second gas piston 37 described later is smaller than the diameter of a first gas piston 33 described later. For example, the area of the first gas piston 33 is not less than 2 times and not more than 10 times the area of the second gas piston 37. Note that the volumes inside gas cylinder tubes 31 and 35 described later may differ due to other elements besides the diameters of the first gas piston 33 and the second gas piston 37.

[0017] The gas cylinder 3A and the hydraulic cylinder 4A of the first gas booster 2A are arranged coaxially, and the gas cylinder 3B and the hydraulic cylinder 4B of the second gas booster 2B are arranged coaxially. In the present embodiment, the axial direction of the gas cylinders 3A, 3B and the hydraulic cylinders 4A, 4B is the vertical direction. The axial direction of the gas cylinders 3A, 3B and the hydraulic cylinders 4A, 4B may be parallel to the vertical direction, or may be slightly inclined relative to the vertical direction, for example, within 20 degrees. Further, in the present embodiment, the hydraulic cylinder 4A is disposed below the gas cylinder 3A, and the hydraulic cylinder 4B is disposed below the gas cylinder 3B. That is, a first drive chamber 4a and a second drive chamber 4b, which will be described later, of the first gas booster 2A are located below a first compression chamber 3a described later, and a third drive chamber 4c and a fourth drive chamber 4d, which will be described later, of the second gas booster 2B are located below a second compression chamber 3b described later.

[0018] Regarding the first gas booster 2A, the gas cylinder 3A includes a gas cylinder tube 31, a gas cover 32 and a first gas piston 33. The gas cylinder tube 31 has a cylindrical shape extending in the vertical direction, and the gas cover 32 closes the upper opening of the gas cylinder tube 31 on the side opposite to the hydraulic cylinder 4A. The first gas piston 33 is disposed inside the gas cylinder tube 31 and forms the first compression chamber 3a between itself and the gas cover 32. That is, the first gas piston 33 faces the first compression chamber 3a.

[0019] The gas cylinder 3A also includes a cylindrical jacket 34 that accommodates the gas cylinder tube 31 and extends from the gas cover 32 to a hydraulic cover 42 described later. An annular cooling chamber is formed between the gas cylinder tube 31 and the jacket 34, and a cooling liquid is supplied to the cooling chamber and discharged from the cooling chamber. However, the jacket 34 may be omitted.

[0020] The gas cover 32 is, for example, disk-shaped. In the present embodiment, the gas cover 32 has a suction port 2a and a discharge port 2b on an end face facing radially outward. However, one or both of the suction port 2a and the discharge port 2b may be located on the upper surface of the gas cover 32.

[0021] The gas cover 32 is formed with a gas flow path 21 leading from the suction port 2a to the first compression chamber 3a, and a gas flow path 23 leading from the first compression chamber 3a to the discharge port 2b. Check valves 22 and 24 are provided in the gas flow paths 21 and 23, respectively.

[0022] However, the check valve 22 may be provided in a gas supply path 11 described later, and the check valve 24 may be provided in a gas communication path 12 described later. In this case, the suction port 2a and the discharge port 2b may be provided at the upper portion of the gas cylinder tube 31, and the gas flow paths 21 and 23 may be omitted. When the suction port 2a and the discharge port 2b are provided in the gas cylinder tube 31, the pipe constituting the gas supply path 11 may pass through the jacket 34 to be connected to the suction port 2a, and the pipe constituting the gas communication path 12 may pass through the jacket 34 to be connected to the discharge port 2b.

[0023] The hydraulic cylinder 4A includes a hydraulic cylinder tube 41, a pair of hydraulic covers 42 and 43, and a first hydraulic piston 44. The hydraulic cylinder tube 41 has a cylindrical shape extending in the vertical direction, the hydraulic cover 42 closes the upper opening of the hydraulic cylinder tube 41, and the hydraulic cover 43 closes the lower opening of the hydraulic cylinder tube 41.

[0024] The first hydraulic piston 44 is positioned inside the hydraulic cylinder tube 41 and forms a first drive chamber 4a between itself and the hydraulic cover 42, and a second drive chamber 4b between itself and the hydraulic cover 43. In other words, the first hydraulic piston 44 separates the first drive chamber 4a and the second drive chamber 4b. In this embodiment, the first hydraulic piston 44 is made of a single component, but it may be made of multiple components. For example, the first hydraulic piston 44 may be made of two plates and a rod between them. In this case, hydraulic fluid may be supplied between the two plates.

[0025] In this embodiment, the lower opening of the gas cylinder tube 31 is closed by the hydraulic cover 42. The rod 55 traverses the first drive chamber 4a and passes through the hydraulic cover 42 to connect the first gas piston 33 and the first hydraulic piston 44. However, similar to the gas compressor 100 shown in Figure 7, the lower opening of the gas cylinder tube 31 may be closed by an intermediate cover, and an intermediate tube may be provided between the intermediate cover and the hydraulic cover 42, surrounding the space around the rod 55.

[0026] The hydraulic covers 42 and 43 are, for example, disc-shaped. In this embodiment, the hydraulic cover 42 has a supply and discharge port 5a on an end face facing radially outward, and the hydraulic cover 43 has a supply and discharge port 5b on an end face facing radially outward. However, the positions of the supply and discharge ports 5a and 5b are not limited to these. For example, the supply and discharge port 5a may be provided at the top of the hydraulic cylinder tube 41 and the hydraulic passage 51 described later may be omitted, or the supply and discharge port 5b may be provided at the bottom of the hydraulic cylinder tube 41 and the hydraulic passage 52 described later may be omitted.

[0027] The hydraulic cover 42 has a hydraulic passage 51 that connects the supply and discharge port 5a to the first drive chamber 4a, and the hydraulic cover 43 has a hydraulic passage 52 that connects the supply and discharge port 5b to the second drive chamber 4b.

[0028] With respect to the second gas booster 2B, the gas cylinder 3B includes a gas cylinder tube 35, a gas cover 36, and a second gas piston 37. The gas cylinder tube 35 is cylindrical and extends vertically, and the gas cover 36 closes the upper opening of the gas cylinder tube 35 on the side opposite to the hydraulic cylinder 4B. The second gas piston 37 is positioned inside the gas cylinder tube 35 and forms a second compression chamber 3b between itself and the gas cover 36. In other words, the second gas piston 37 faces the second compression chamber 3b.

[0029] The gas cylinder 3B also includes a cylindrical jacket 38 that houses the gas cylinder tube 35 and extends from the gas cover 36 to the hydraulic cover 46, which will be described later. An annular cooling chamber is formed between the gas cylinder tube 35 and the jacket 38, and coolant is supplied to and discharged from the cooling chamber. However, the jacket 38 may be omitted.

[0030] The gas cover 36 is, for example, disc-shaped. In this embodiment, the gas cover 36 has an intake port 2c and a discharge port 2d on an end face facing radially outward. However, one or both of the intake port 2c and the discharge port 2d may be on the upper surface of the gas cover 36.

[0031] The gas cover 36 has a gas passage 25 leading from the intake port 2c to the second compression chamber 3b, and a gas passage 27 leading from the second compression chamber 3b to the discharge port 2d. Check valves 26 and 28 are provided in the gas passages 25 and 27, respectively.

[0032] However, the check valve 26 may be provided in the gas communication passage 12 described later, and the check valve 28 may be provided in the gas discharge passage 13 described later. In this case, the intake port 2c and the discharge port 2d may be provided at the top of the gas cylinder tube 35, and the gas passages 25 and 27 may be omitted. When the intake port 2c and the discharge port 2d are provided in the gas cylinder tube 35, the piping constituting the gas communication passage 12 may pass through the jacket 38 and connect to the intake port 2c, and the piping constituting the gas discharge passage 13 may pass through the jacket 38 and connect to the discharge port 2d.

[0033] The hydraulic cylinder 4B includes a hydraulic cylinder tube 45, a pair of hydraulic covers 46, 47, and a second hydraulic piston 48. The hydraulic cylinder tube 45 is cylindrical and extends vertically, the hydraulic cover 46 closes the upper opening of the hydraulic cylinder tube 45, and the hydraulic cover 47 closes the lower opening of the hydraulic cylinder tube 45.

[0034] The second hydraulic piston 48 is positioned inside the hydraulic cylinder tube 45 and forms a third drive chamber 4c between itself and the hydraulic cover 46, and a fourth drive chamber 4d between itself and the hydraulic cover 47. In other words, the second hydraulic piston 48 separates the third drive chamber 4c and the fourth drive chamber 4d. In this embodiment, the second hydraulic piston 48 is made of a single component, but it may be made of multiple components. For example, the second hydraulic piston 48 may be made of two plates and a rod between them. In this case, hydraulic fluid may be supplied between the two plates.

[0035] In this embodiment, the lower opening of the gas cylinder tube 35 is closed by the hydraulic cover 46. The rod 56 traverses the third drive chamber 4c and passes through the hydraulic cover 46 to connect the second gas piston 37 and the second hydraulic piston 48. However, similar to the gas compressor 100 shown in Figure 7, the lower opening of the gas cylinder tube 35 may be closed by an intermediate cover, and an intermediate tube may be provided between the intermediate cover and the hydraulic cover 46, surrounding the space around the rod 56.

[0036] The hydraulic covers 46 and 47 are, for example, disc-shaped. In this embodiment, the hydraulic cover 46 has a supply and discharge port 5c on an end face facing radially outward, and the hydraulic cover 47 has a supply and discharge port 5d on an end face facing radially outward. However, the positions of the supply and discharge ports 5c and 5d are not limited to these. For example, the supply and discharge port 5c may be provided at the top of the hydraulic cylinder tube 45 and the hydraulic passage 53 described later may be omitted, or the supply and discharge port 5d may be provided at the bottom of the hydraulic cylinder tube 45 and the hydraulic passage 54 described later may be omitted.

[0037] The hydraulic cover 46 has a hydraulic passage 53 that connects the supply and discharge port 5c to the third drive chamber 4c, and the hydraulic cover 47 has a hydraulic passage 54 that connects the supply and discharge port 5d to the fourth drive chamber 4d.

[0038] A gas supply passage 11 is connected to the intake port 2a of the first gas booster 2A, and a gas discharge passage 13 is connected to the discharge port 2d of the second gas booster 2B. Furthermore, the discharge port 2b of the first gas booster 2A and the intake port 2c of the second gas booster 2B are connected to each other by a gas communication passage 12. As a result, gas is supplied from the first compression chamber 3a to the second compression chamber 3b. A cooler may be provided in the gas communication passage 12.

[0039] The supply and discharge port 5b of the first gas booster 2A and the supply and discharge port 5d of the second gas booster 2B are connected to each other by a hydraulic communication passage 81. In other words, the hydraulic communication passage 81 connects the second drive chamber 4b of the first gas booster 2A and the fourth drive chamber 4d of the second gas booster 2B. Therefore, the second drive chamber 4b, the hydraulic passage 52, the hydraulic communication passage 81, the hydraulic passage 54, and the fourth drive chamber 4d constitute an intermediate chamber. A first on-off valve 82 is provided in the hydraulic communication passage 81. Note that, as described above, when the supply and discharge port 5b is provided in the hydraulic cylinder tube 41 and the hydraulic passage 52 is omitted, and the supply and discharge port 5d is provided in the hydraulic cylinder tube 45 and the hydraulic passage 54 is omitted, the second drive chamber 4b, the hydraulic communication passage 81, and the fourth drive chamber 4d constitute an intermediate chamber.

[0040] The diameter of the first hydraulic piston 44 of the first gas booster 2A and the diameter of the second hydraulic piston 48 of the second gas booster 2B are equal. Therefore, the strokes of the first hydraulic piston 44 and the first gas piston 33 are equal to the strokes of the second hydraulic piston 48 and the second gas piston 37. However, the diameters of the first hydraulic piston 44 and the second hydraulic piston 48 may be different, and the strokes of the first hydraulic piston 44 and the first gas piston 33 may be different to the strokes of the second hydraulic piston 48 and the second gas piston 37.

[0041] The hydraulic pump 61 described above discharges hydraulic fluid to either the first common passage 63 or the second common passage 64. In this embodiment, the hydraulic pump 61 is a bidirectional pump whose hydraulic fluid discharge direction can be switched depending on the direction of rotation, and the first common passage 63 and the second common passage 64 are directly connected to the hydraulic pump 61. For example, a bidirectional pump is an axial piston pump. However, the hydraulic pump 61 may also be an axial piston pump that rotates in one direction, and whose hydraulic fluid discharge direction is switched depending on the tilting direction from the center of the swash plate or oblique axis. In this case, the control device 9 controls the hydraulic pump 61 via a regulator that changes the tilting angle of the hydraulic pump 61. Also, although the hydraulic pump 61 is a variable displacement pump in the illustrated example, the hydraulic pump 61 may also be a fixed displacement pump.

[0042] The first common passage 63 is connected to the tank by a tank passage 65, and a check valve 66 is provided in the tank passage 65. Similarly, the second common passage 64 is connected to the tank by a tank passage 67, and a check valve 68 is provided in the tank passage 67.

[0043] The first common passage 63 is connected to the supply and discharge port 5b of the first gas booster 2A by the first supply and discharge passage 71, and the second common passage 64 is connected to the supply and discharge port 5c of the second gas booster 2B by the second supply and discharge passage 75. In other words, the first supply and discharge passage 71 is interposed between the first common passage 63 and the second drive chamber 4b, and the second supply and discharge passage 75 is interposed between the second common passage 64 and the third drive chamber 4c. The first supply and discharge passage 71 is provided with a second on-off valve 72, and the second supply and discharge passage 75 is provided with a third on-off valve 76.

[0044] From the hydraulic communication passage 81, a first branch passage 83 branches off on the fourth drive chamber 4d side of the first on-off valve 82, and the first branch passage 83 is connected to the first common passage 63. A fourth on-off valve 84 is provided in the first branch passage 83. Also from the hydraulic communication passage 81, a second branch passage 85 branches off on the second drive chamber 4b side of the first on-off valve 82, and the second branch passage 85 is connected to the second common passage 64. A fifth on-off valve 86 is provided in the second branch passage 85.

[0045] Furthermore, the portion of the first supply / discharge passage 71 between the second on-off valve 72 and the first gas booster 2A is connected to the tank by a tank passage 73, and the tank passage 73 is equipped with a sixth on-off valve 74. Similarly, the portion of the second supply / discharge passage 75 between the third on-off valve 76 and the second gas booster 2B is connected to the tank by a tank passage 77, and the tank passage 77 is equipped with a seventh on-off valve 78.

[0046] As described above, the control device 9 not only controls the hydraulic pump 61 via the electric motor 62, but also controls the first on-off valve 82, the second on-off valve 72, the third on-off valve 76, the fourth on-off valve 84, the fifth on-off valve 86, the sixth on-off valve 74, and the seventh on-off valve 78. In the illustrated example, the first on-off valve 82, the fourth on-off valve 84, the fifth on-off valve 86, the sixth on-off valve 74, and the seventh on-off valve 78 are normally closed, and the second on-off valve 72 and the third on-off valve 76 are normally open. However, it is possible to appropriately determine whether each of the first on-off valve 82, the second on-off valve 72, the third on-off valve 76, the fourth on-off valve 84, the fifth on-off valve 86, the sixth on-off valve 74, and the seventh on-off valve 78 is normally closed or normally open.

[0047] With respect to the control device 9, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, dedicated processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions, or hardware programmed to perform the enumerated functions. The hardware may be hardware disclosed herein, or other known hardware programmed or configured to perform the enumerated functions. If the hardware is a processor, which is considered a type of circuit, then the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor. The control device 9 may consist of a single device or multiple devices.

[0048] Next, the operation method of the gas compressor 1A will be explained. In this operation method, the system switches between an operation mode in which the gas is compressed in two stages using both the first gas booster 2A and the second gas booster 2B, and an operation mode in which the gas is compressed in one stage using only the second gas booster 2B without using the first gas booster 2A. For example, the gas is compressed in two stages when the pressure of the gas supplied through the gas supply passage 11 is low, and the gas is compressed in one stage when the pressure of the gas supplied through the gas supply passage 11 is high.

[0049] When gas compressor 1A is idle, as shown in Figure 2, the first hydraulic piston 44 of the first gas booster 2A is in contact with the hydraulic cover 43 by its own weight, and the second hydraulic piston 48 of the second gas booster 2B is in contact with the hydraulic cover 47 by its own weight. For example, the sixth on-off valve 74 and the seventh on-off valve 78 are opened before gas compressor 1A is idle, and closed otherwise.

[0050] Before compressing the gas using both the first gas booster 2A and the second gas booster 2B, the control device 9 opens the third on-off valve 76 and the fourth on-off valve 84, as shown in Figure 3, and closes the first on-off valve 82, the second on-off valve 72, and the fifth on-off valve 86, while driving the hydraulic pump 61 to rotate in the direction of discharging hydraulic fluid to the first common passage 63. This supplies hydraulic fluid to the fourth drive chamber 4d, causing the second hydraulic piston 48 to rise. In other words, the second hydraulic piston 48 moves toward the second gas piston 37. Therefore, the intermediate chamber, which consists of the second drive chamber 4b, the hydraulic passage 52, the hydraulic communication passage 81, the hydraulic passage 54, and the fourth drive chamber 4d, can be filled with hydraulic fluid.

[0051] After the second hydraulic piston 48 has risen to its upper limit, the control device 9 opens the second on-off valve 72 and the fifth on-off valve 86, and with the first on-off valve 82, the third on-off valve 76, and the fourth on-off valve 84 closed, drives the hydraulic pump 61 to rotate in the direction of discharging hydraulic fluid into the second common passage 64, thereby supplying hydraulic fluid to the second drive chamber 4b and slightly raising the second hydraulic piston 48. This allows the intermediate chamber to be filled with more hydraulic fluid than the volume of the second drive chamber 4b or the fourth drive chamber 4d. As a result, it is possible to prevent the first gas piston 33 or the second gas piston 37 from coming into contact with the hydraulic cover 42 or 46 when it descends.

[0052] However, in order to fill the intermediate chamber with hydraulic fluid, the opposite procedure can be followed: first, the second on-off valve 72 and the fifth on-off valve 86 are opened, and with the first on-off valve 82, the third on-off valve 76, and the fourth on-off valve 84 closed, the hydraulic pump 61 is driven to rotate in the direction of discharging hydraulic fluid into the second common passage 64, thereby raising the first hydraulic piston 44 to its upper limit, in other words, moving it toward the first gas piston 33. After that, the third on-off valve 76 and the fourth on-off valve 84 are opened, and with the first on-off valve 82, the second on-off valve 72, and the fifth on-off valve 86 closed, the hydraulic pump 61 is driven to rotate in the direction of discharging hydraulic fluid into the first common passage 63, thereby slightly raising the second hydraulic piston 48.

[0053] After the intermediate chamber is filled with hydraulic fluid, the control device 9, when compressing the gas using both the first gas booster 2A and the second gas booster 2B, opens the first on-off valve 82, the second on-off valve 72, and the third on-off valve 76, while closing the fourth on-off valve 84 and the fifth on-off valve 86. In this state, the control device 9 rotates the hydraulic pump 61 alternately in the direction of discharging hydraulic fluid to the first common passage 63 and in the direction of discharging hydraulic fluid to the second common passage 64.

[0054] Since the intermediate chamber is filled with hydraulic fluid, the first hydraulic piston 44 and the second hydraulic piston 48 move alternately. First, when hydraulic fluid is supplied from the hydraulic pump 61 to the first drive chamber 4a through the first common passage 63 and the first supply / discharge passage 71, the first hydraulic piston 44 and the first gas piston 33 descend, while the second hydraulic piston 48 and the second gas piston 37 rise. As the first gas piston 33 descends, gas is supplied from the gas supply passage 11 to the first compression chamber 3a through the gas passage 21.

[0055] Next, when hydraulic fluid is supplied from the hydraulic pump 61 to the third drive chamber 4c through the second common passage 64 and the second supply / discharge passage 75, the second hydraulic piston 48 and the second gas piston 37 descend, while the first hydraulic piston 44 and the first gas piston 33 rise. As the first gas piston 33 rises and the second gas piston 37 descends, gas is supplied from the first compression chamber 3a to the second compression chamber 3b through the gas passage 23, the gas communication passage 12, and the gas passage 25. At this time, the gas is compressed due to the area difference between the first compression chamber 3a and the second compression chamber 3b.

[0056] Again, when hydraulic fluid is supplied from the hydraulic pump 61 to the first drive chamber 4a through the first common passage 63 and the first supply / discharge passage 71, the first hydraulic piston 44 and the first gas piston 33 descend, while the second hydraulic piston 48 and the second gas piston 37 rise. As the second gas piston 37 rises, the gas in the second compression chamber 3b is compressed to at least the pressure downstream of the check valve 28, and the compressed gas is discharged through the gas passage 27 and the gas discharge passage 13.

[0057] On the other hand, when the control device 9 compresses the gas using the second gas booster 2B without using the first gas booster 2A, it opens the third on-off valve 76 and the fourth on-off valve 84, and closes the first on-off valve 82, the second on-off valve 72, and the fifth on-off valve 86. In this state, the control device 9 rotates the hydraulic pump 61 alternately in the direction of discharging hydraulic fluid to the first common passage 63 and in the direction of discharging hydraulic fluid to the second common passage 64. At this time, the gas supplied through the gas supply passage 11 passes through the gas passages 21 and 23 of the first gas booster 2A, is supplied to the second compression chamber 3b through the gas communication passage 12 and the gas passage 25 of the second gas booster 2B, and is compressed in the second compression chamber 3b.

[0058] As described above, in the gas compressor 1A of this embodiment, a first on-off valve 82 is provided in the hydraulic communication passage 81. By closing the first on-off valve 82, one of the first hydraulic piston 44 and the second hydraulic piston 48 can be stopped while the other moves. Therefore, it is possible to switch between compressing the gas in one stage or in two stages.

[0059] More specifically, as described above, by opening the first on-off valve 82, the second on-off valve 72, and the third on-off valve 76, and closing the fourth on-off valve 84 and the fifth on-off valve 86, the gas can be compressed in two stages using both the first gas booster 2A and the second gas booster 2B. Alternatively, by opening the third on-off valve 76 and the fourth on-off valve 84, and closing the first on-off valve 82, the second on-off valve 72, and the fifth on-off valve 86, the gas can be compressed in one stage using the second gas booster 2B without using the first gas booster 2A.

[0060] <Variation> As shown in the modified gas compressor 1B in Figure 4, the supply and discharge ports 5a of the first gas booster 2A and the supply and discharge ports 5c of the second gas booster 2B may be connected to each other by a hydraulic communication passage 81, and the hydraulic communication passage 81 may also connect the first drive chamber 4a of the first gas booster 2A and the third drive chamber 4c of the second gas booster 2B. In this case, the first supply and discharge passage 71 is connected to the supply and discharge port 5b of the first gas booster 2A, and the second supply and discharge passage 75 is connected to the supply and discharge port 5d of the second gas booster 2B.

[0061] In the gas compressor 1B shown in Figure 4, the first supply and discharge passage 71 is interposed between the second drive chamber 4b and the first common passage 63, and the second supply and discharge passage 75 is interposed between the fourth drive chamber 4d and the second common passage 64. In addition, the first branch passage 83 branches off from the hydraulic communication passage 81 on the third drive chamber 4c side of the first on-off valve 82, and the second branch passage 85 branches off from the hydraulic communication passage 81 on the first drive chamber 4a side of the first on-off valve 82.

[0062] In the gas compressor 1B shown in Figure 4, the control device 9, similar to the first embodiment, opens the first on-off valve 82, the second on-off valve 72, and the third on-off valve 76, and closes the fourth on-off valve 84 and the fifth on-off valve 86, when compressing the gas in two stages using both the first gas booster 2A and the second gas booster 2B. On the other hand, when compressing the gas in one stage using only the second gas booster 2B without using the first gas booster 2A, the control device 9 opens the third on-off valve 76 and the fourth on-off valve 84, and closes the first on-off valve 82, the second on-off valve 72, and the fifth on-off valve 86. Note that in Figure 4, the operation of filling the intermediate chamber with hydraulic fluid, as described in the first embodiment, is not necessary.

[0063] Furthermore, in Figure 1 or Figure 4, a bypass path may be adopted that branches off from the gas supply path 11 to bypass the first gas booster 2A and connects to the gas communication path 12, and a bypass valve may be provided in the bypass path. In this case, when compressing the gas in one stage using the second gas booster 2B without using the first gas booster 2A, the bypass valve may be opened to supply gas to the second compression chamber 3b without passing through the first gas booster 2A. In other words, it is not always necessary to supply gas from the first compression chamber 3a to the second compression chamber 3b.

[0064] <Second Embodiment> Figure 5 shows a gas compressor 1C according to the second embodiment. In this embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and redundant explanations are omitted.

[0065] In this embodiment, the hydraulic pump 61 rotates in only one direction. Therefore, the hydraulic pump 61 is connected to the first common passage 63 and the second common passage 64 via the pump passage 91 and the switching valve 93. The hydraulic pump 61 may be a variable displacement pump or a fixed displacement pump.

[0066] The hydraulic pump 61 supplies hydraulic fluid to either the first common passage 63 or the second common passage 64 via the pump passage 91 and the switching valve 93. The switching valve 93 is connected to the tank by the tank passage 92. In this embodiment, the switching valve 93 is a three-position valve that can be switched between a neutral position, a first operating position and a second operating position.

[0067] In the neutral position, the switching valve 93 blocks all of the pump passage 91, tank passage 92, first common passage 63, and second common passage 64. In the first operating position on the right side of Figure 5, the switching valve 93 connects the pump passage 91 to the first common passage 63 and the second common passage 64 to the tank passage 92. In the second operating position on the left side of Figure 5, the switching valve 93 connects the pump passage 91 to the second common passage 64 and the first common passage 63 to the tank passage 92. The opening degree of the switching valve 93 in the first and second operating positions may be constant or variable.

[0068] The other configurations of the gas compressor 1C are the same as in the first embodiment. Specifically, the supply and discharge ports 5b of the first gas booster 2A and the supply and discharge ports 5d of the second gas booster 2B are connected to each other by a hydraulic communication passage 81, and a first on-off valve 82 is provided in the hydraulic communication passage 81. The gas compressor 1C also includes a second on-off valve 72, a third on-off valve 76, a fourth on-off valve 84, and a fifth on-off valve 86. Therefore, the same effects as in the first embodiment can be obtained in this embodiment as well.

[0069] <Variation> As shown in the modified gas compressor 1D in Figure 6, the supply and discharge ports 5a of the first gas booster 2A and the supply and discharge ports 5c of the second gas booster 2B may be connected to each other by a hydraulic communication passage 81.

[0070] <Other Embodiments> This disclosure is not limited to the embodiments described above, and various modifications are possible without departing from the gist of this disclosure.

[0071] For example, the axial direction of the gas cylinders 3A, 3B and hydraulic cylinders 4A, 4B may be horizontal rather than vertical. However, if the axial direction of the gas cylinders 3A, 3B and hydraulic cylinders 4A, 4B is vertical, as in the above embodiment, the installation area of ​​the gas compressors 1A, 1B, 1C, 1D can be reduced compared to when the axial direction of the gas cylinders 3A, 3B and hydraulic cylinders 4A, 4B is horizontal. Furthermore, since the space above the gas cylinders 3A, 3B can be used as a maintenance space, the gap between the first gas booster 2A, which includes the gas cylinders 3A and hydraulic cylinders 4A, and the surrounding structure, and the gap between the second gas booster 2B, which includes the gas cylinders 3B and hydraulic cylinders 4B, and the surrounding structure can be reduced. In addition, since the gas cylinders 3A, 3B are located above the hydraulic cylinders 4A, 4B, the first gas piston 33 and the second gas piston 37 can be lifted from above, improving maintainability.

[0072] Furthermore, it is also possible to compress the gas in a single stage by using the first gas booster 2A without using the second gas booster 2B. When compressing the gas using the first gas booster 2A without using the second gas booster 2B, the control device 9 opens the second on-off valve 72 and the fifth on-off valve 86, and drives the hydraulic pump 61 with the first on-off valve 82, the third on-off valve 76 and the fourth on-off valve 84 closed.

[0073] Alternatively, a low-pressure supply line may be branched from the gas connection passage 12, and two first gas boosters 2A may be provided to connect two first compression chambers 3a in parallel to one second compression chamber 3b via the gas connection passage 12. In this case, when a large flow rate of gas at low pressure is required, the two first gas boosters 2A may be used to compress the gas in one stage, and when a small flow rate of gas at high pressure is required, one of the first gas boosters 2A and the second gas booster 2B may be used to compress the gas in two stages.

[0074] <Summary> In a first aspect, the present disclosure provides a gas compressor comprising: a first gas booster including a first gas piston facing a first compression chamber and a first hydraulic piston that partitions a first drive chamber and a second drive chamber and is connected to the first gas piston by a rod that crosses the first drive chamber; a second gas booster including a second gas piston facing a second compression chamber from which gas is supplied from the first compression chamber and a second hydraulic piston that partitions a third drive chamber and a fourth drive chamber and is connected to the second gas piston by a rod that crosses the third drive chamber; and an on-off valve provided in a communication passage that connects the first drive chamber and the third drive chamber or the second drive chamber and the fourth drive chamber.

[0075] With the above configuration, since an on-off valve is provided in the communication passage, closing the on-off valve allows one of the first and second hydraulic pistons to stop while the other moves. Therefore, it is possible to switch between compressing the gas in one stage or in two stages.

[0076] In a second embodiment, in the first embodiment, the on-off valve is a first on-off valve, the communication passage connects the second drive chamber and the fourth drive chamber, and the gas compressor further comprises a hydraulic pump that discharges hydraulic fluid to either the first common passage or the second common passage, a second on-off valve provided in a first supply / discharge passage interposed between the first drive chamber and the first common passage, a third on-off valve provided in a second supply / discharge passage interposed between the third drive chamber and the second common passage, a fourth on-off valve provided in a first branch passage that branches off from the communication passage and connects to the first common passage on the fourth drive chamber side of the first on-off valve, and a fifth on-off valve provided in a second branch passage that branches off from the communication passage and connects to the second common passage on the second drive chamber side of the first on-off valve. With this configuration, by opening the first, second, and third on-off valves and closing the fourth and fifth on-off valves, the gas can be compressed in two stages using both the first and second gas boosters. Furthermore, by opening the third and fourth on-off valves and closing the first, second, and fifth on-off valves, the gas can be compressed in one stage using the second gas booster without using the first gas booster. Similarly, by opening the second and fifth on-off valves and closing the first, third, and fourth on-off valves, the gas can be compressed in one stage using the first gas booster without using the second gas booster.

[0077] In a third embodiment, in the second embodiment, for example, the gas compressor further comprises a control device for controlling the first on-off valve, the second on-off valve, the third on-off valve, the fourth on-off valve and the fifth on-off valve, wherein when compressing gas using both the first gas booster and the second gas booster, the control device may open the first on-off valve, the second on-off valve and the third on-off valve and close the fourth on-off valve and the fifth on-off valve, and when compressing gas using the second gas booster without using the first gas booster, it may open the third on-off valve and the fourth on-off valve and close the first on-off valve, the second on-off valve and the fifth on-off valve.

[0078] In a fourth embodiment, in the third embodiment, the control device controls the hydraulic pump, The control device may, before compressing the gas using both the first and second gas boosters, open the third and fourth on-off valves, and with the first, second, and fifth on-off valves closed, drive the hydraulic pump to supply hydraulic fluid to the fourth drive chamber, thereby moving the second hydraulic piston toward the second gas piston. With this configuration, the intermediate chamber, which consists of the second drive chamber, the communication passage, and the fourth drive chamber, can be filled with hydraulic fluid before using both the first and second gas boosters.

[0079] In a fifth embodiment, in the third embodiment, the control device controls the hydraulic pump, and before compressing the gas using both the first and second gas boosters, the control device opens the second and fifth on-off valves and, with the first, third, and fourth on-off valves closed, drives the hydraulic pump to supply hydraulic fluid to the second drive chamber, thereby moving the first hydraulic piston toward the first gas piston. With this configuration, hydraulic fluid can be filled into the intermediate chamber, which consists of the second drive chamber, the communication passage, and the fourth drive chamber, before using both the first and second gas boosters.

[0080] In a sixth embodiment, in the first embodiment, the on-off valve is a first on-off valve, the communication passage connects the first drive chamber and the third drive chamber, and the gas compressor further comprises a hydraulic pump that discharges hydraulic fluid to either the first common passage or the second common passage, a second on-off valve provided in a first supply / discharge passage interposed between the second drive chamber and the first common passage, a third on-off valve provided in a second supply / discharge passage interposed between the fourth drive chamber and the second common passage, a fourth on-off valve provided in a first branch passage that branches off from the communication passage and connects to the first common passage on the third drive chamber side of the first on-off valve, and a fifth on-off valve provided in a second branch passage that branches off from the communication passage and connects to the second common passage on the first drive chamber side of the first on-off valve. With this configuration, by opening the first, second, and third on-off valves and closing the fourth and fifth on-off valves, the gas can be compressed in two stages using both the first and second gas boosters. Furthermore, by opening the third and fourth on-off valves and closing the first, second, and fifth on-off valves, the gas can be compressed in one stage using the second gas booster without using the first gas booster. Similarly, by opening the second and fifth on-off valves and closing the first, third, and fourth on-off valves, the gas can be compressed in one stage using the first gas booster without using the second gas booster.

[0081] In a seventh aspect, in the sixth aspect, for example, the gas compressor further comprises a control device for controlling the first on-off valve, the second on-off valve, the third on-off valve, the fourth on-off valve and the fifth on-off valve, wherein when compressing gas using both the first gas booster and the second gas booster, the control device may open the first on-off valve, the second on-off valve and the third on-off valve and close the fourth on-off valve and the fifth on-off valve, and when compressing gas using the second gas booster without using the first gas booster, it may open the third on-off valve and the fourth on-off valve and close the first on-off valve, the second on-off valve and the fifth on-off valve.

[0082] In an eighth aspect, the present disclosure provides a method for operating a gas compressor including a first gas booster and a second gas booster, the method for operating a gas compressor that switches between an operating mode in which the gas is compressed in two stages using both the first gas booster and the second gas booster, and an operating mode in which the gas is compressed in one stage using only the second gas booster without using the first gas booster. [Explanation of Symbols]

[0083] 1A, 1B, 1C, 1D Gas Compressors 12 Gas connection passage 2A No. 1 Gas Booster 2B Second Gas Booster 33. First gas piston 37. Second gas piston 3a First Compression Chamber 3b 2nd compression chamber 44. First hydraulic piston 48. Second hydraulic piston 4a First drive chamber 4b Second drive chamber 4c Third drive chamber 4d Fourth drive chamber 55, 56 rods 61 Hydraulic pump 63 1st common road 64 2nd common road 71 1st supply / discharge path 72 Second shut-off valve 75 2nd supply / discharge path 76 Third shut-off valve 81 Hydraulic passageway 82 First shut-off valve 83 First Junction 84. Fourth shut-off valve 85 Second Junction 86. Fifth shut-off valve 9 Control device

Claims

1. A first gas booster includes a first gas piston facing a first compression chamber, and a first hydraulic piston that separates a first drive chamber and a second drive chamber and is connected to the first gas piston by a rod that crosses the first drive chamber. A second gas booster includes a second gas piston facing a second compression chamber from which gas is supplied from the first compression chamber, and a second hydraulic piston that separates a third drive chamber and a fourth drive chamber and is connected to the second gas piston by a rod that crosses the third drive chamber, A first on / off valve is provided in a communication passage that connects the first drive chamber and the third drive chamber, or the second drive chamber and the fourth drive chamber, Equipped with, The aforementioned connecting passage connects the second drive chamber and the fourth drive chamber. A hydraulic pump that discharges hydraulic fluid to either the first common passage or the second common passage, A second on-off valve is provided in the first supply / discharge passage interposed between the first drive chamber and the first common passage, A third on / off valve is provided in the second supply / discharge passage interposed between the third drive chamber and the second common passage, A fourth on-off valve is provided in a first branch passage that branches off from the communication passage on the fourth drive chamber side of the first on-off valve and connects to the first common passage, A fifth on-off valve is provided in a second branch passage that branches off from the communication passage on the second drive chamber side of the first on-off valve and connects to the second common passage, A gas compressor that is further equipped with [the following features].

2. The system further includes a control device for controlling the first, second, third, fourth, and fifth on-off valves, The gas compressor according to claim 1, wherein the control device opens the first, second, and third on-off valves and closes the fourth and fifth on-off valves when compressing gas using both the first and second gas boosters, and opens the third and fourth on-off valves and closes the first, second, and fifth on-off valves when compressing gas using only the second gas booster without using the first gas booster.

3. The control device controls the hydraulic pump, The gas compressor according to claim 2, wherein the control device opens the third and fourth on-off valves and, with the first, second, and fifth on-off valves closed, drives the hydraulic pump to supply hydraulic fluid to the fourth drive chamber, thereby moving the second hydraulic piston toward the second gas piston.

4. The control device controls the hydraulic pump, The gas compressor according to claim 2, wherein the control device opens the second on-off valve and the fifth on-off valve and, with the first on-off valve, the third on-off valve and the fourth on-off valve closed, drives the hydraulic pump to supply hydraulic fluid to the second drive chamber, thereby moving the first hydraulic piston toward the first gas piston.

5. A first gas booster including a first gas piston facing a first compression chamber, and a first hydraulic piston that separates a first drive chamber and a second drive chamber and is connected to the first gas piston by a rod that crosses the first drive chamber, A second gas booster includes a second gas piston facing a second compression chamber from which gas is supplied from the first compression chamber, and a second hydraulic piston that separates a third drive chamber and a fourth drive chamber and is connected to the second gas piston by a rod that crosses the third drive chamber, A first on / off valve is provided in a communication passage that connects the first drive chamber and the third drive chamber, or the second drive chamber and the fourth drive chamber, Equipped with, The aforementioned connecting passage connects the first drive chamber and the third drive chamber. A hydraulic pump that discharges hydraulic fluid to either the first common passage or the second common passage, A second on-off valve is provided in the first supply / discharge passage interposed between the second drive chamber and the first common passage, A third on / off valve is provided in the second supply / discharge passage interposed between the fourth drive chamber and the second common passage, A fourth on-off valve is provided in a first branch passage that branches off from the communication passage on the third drive chamber side of the first on-off valve and connects to the first common passage, A fifth on-off valve is provided in a second branch passage that branches off from the communication passage on the first drive chamber side of the first on-off valve and connects to the second common passage, A gas compressor that is further equipped with [the following features].

6. The system further includes a control device for controlling the first, second, third, fourth, and fifth on-off valves, The gas compressor according to claim 5, wherein the control device opens the first, second, and third on-off valves and closes the fourth and fifth on-off valves when compressing gas using both the first and second gas boosters, and opens the third and fourth on-off valves and closes the first, second, and fifth on-off valves when compressing gas using only the second gas booster without using the first gas booster.

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