gas compressor

Abstract

To provide a gas compressor that can reduce pressure loss.SOLUTION: A gas compressor 1A includes a gas booster 2A including a first compression chamber 3a, a second compression chamber 3b, a first driving chamber 2a, and a second driving chamber 2b. In the gas booster 2A, when hydraulic oil is supplied to the first driving chamber 2a, gas is supplied to the first compression chamber 3a, the gas is compressed in the second compression chamber 3b, and the hydraulic oil flows out of the second driving chamber 2b, and when the hydraulic oil is supplied to the second driving chamber 2b, the gas is compressed in the first compression chamber 3a, the gas is supplied to the second compression chamber 3b, and the hydraulic oil flows out of the first driving chamber 2a. The gas compressor 1A includes: a bidirectional pump 71 for supplying the hydraulic oil to one of the first driving chamber 2a and the second driving chamber 2b, and sucking the hydraulic oil from the other; an electric motor 72 for driving the bidirectional pump 71; and a control device 8 for controlling the electric motor 72.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a hydraulically driven gas compressor.

Background Art

[0002] Hydraulically driven gas compressors have been conventionally known. For example, such gas compressors are used as large-sized gas compressors.

[0003] For example, Patent Document 1 discloses a gas compressor including a gas booster 100 as shown in FIG. 6. Specifically, the gas booster 100 includes a first structure 200 and a second structure 300.

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

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

[0006] The first working chamber 230 of the first structure 200 and the third working chamber 330 of the second structure 300 communicate with each other through a communication passage 400. Therefore, the fourth working chamber 340 of the second structure 300 functions as a first driving chamber 110, and the second working chamber 240 of the first structure 200 functions as a second driving chamber 120.

[0007] More specifically, when hydraulic fluid is supplied to the first drive chamber 110, the gas in the second compression chamber 310 of the second structure 300 is compressed by the rise of the second gas piston 320, and in the first structure 200, the hydraulic fluid flows out of the second drive chamber 120 and gas is supplied to the first compression chamber 210 as the first hydraulic piston 250 and first gas piston 220 descend. Conversely, when hydraulic fluid is supplied to the second drive chamber 120, the gas in the first compression chamber 210 of the first structure 200 is compressed by the rise of the first gas piston 220, and in the second structure 300, the hydraulic fluid flows out of the first drive chamber 110 and gas is supplied to the second compression chamber 310 as the second hydraulic piston 350 and second gas piston 320 descend. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2021-522446 [Overview of the project] [Problems that the invention aims to solve]

[0009] To supply hydraulic fluid to either the first drive chamber 110 or the second drive chamber 120, one could consider switching the discharge direction of the hydraulic fluid from the pump using a directional control valve. However, in this configuration, pressure loss occurs when the hydraulic fluid passes through the directional control valve.

[0010] Therefore, the object of this disclosure is to provide a gas compressor that can reduce pressure loss. [Means for solving the problem]

[0011] This disclosure provides a gas compressor comprising, in first aspect, a gas booster including a first compression chamber, a second compression chamber, a first drive chamber, and a second drive chamber, wherein when hydraulic fluid is supplied to the first drive chamber, gas is supplied to the first compression chamber, the gas is compressed in the second compression chamber, and hydraulic fluid flows out of the second drive chamber, and when hydraulic fluid is supplied to the second drive chamber, gas is compressed in the first compression chamber, gas is supplied to the second compression chamber, and hydraulic fluid flows out of the first drive chamber; a bidirectional pump that supplies hydraulic fluid to one of the first drive chamber and the second drive chamber and draws hydraulic fluid from the other; an electric motor that drives the bidirectional pump; and a control device that controls the rotational speed of the electric motor.

[0012] This disclosure, in a second aspect, provides a gas booster comprising a first structure, a second structure, and a communication passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that partitions a first working chamber and a second working chamber and crosses the first working chamber; the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that partitions a third working chamber and a fourth working chamber and crosses the third working chamber; and the communication passage connects the second working chamber and the fourth working chamber; a bidirectional pump that supplies hydraulic fluid to one of the first and third working chambers and draws hydraulic fluid from the other; an electric motor that drives the bidirectional pump; and a control device that controls the rotational speed of the electric motor.

[0013] This disclosure, in a third aspect, provides a gas booster comprising a first structure, a second structure, and a communication passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that partitions a first working chamber and a second working chamber and crosses the first working chamber; the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that partitions a third working chamber and a fourth working chamber and crosses the third working chamber; and the communication passage connects the first working chamber and the third working chamber, comprising a gas booster, a bidirectional pump that supplies hydraulic fluid to one of the second and fourth working chambers and draws hydraulic fluid from the other, an electric motor that drives the bidirectional pump, and a control device that controls the rotational speed of the electric motor.

[0014] This disclosure provides a gas compressor comprising, from a fourth aspect, a gas booster including a first gas piston facing a first compression chamber, a second gas piston facing a second compression chamber, and a hydraulic piston that separates a first drive chamber from a second drive chamber and is connected to the first gas piston by a rod traversing the first drive chamber and to the second gas piston by a rod traversing the second drive chamber; a bidirectional pump that supplies hydraulic fluid to one of the first and second drive chambers and draws hydraulic fluid from the other; an electric motor that drives the bidirectional pump; and a control device that controls the rotational speed of the electric motor. [Effects of the Invention]

[0015] According to this disclosure, a gas compressor capable of reducing pressure loss is provided. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of the gas compressor according to the first embodiment. [Figure 2] This is a schematic diagram of a gas compressor as a modified example of the first embodiment. [Figure 3] This is a schematic diagram of a gas compressor representing another modified example of the first embodiment. [Figure 4] It is a schematic configuration diagram of a gas compressor according to a second embodiment. [Figure 5] It is a schematic configuration diagram of a gas compressor according to a modified example of the second embodiment. [Figure 6] It is a cross-sectional view of a gas booster of a conventional gas compressor.

Mode for Carrying Out the Invention

[0017] <First Embodiment> FIG. 1 shows a gas compressor 1A according to the first embodiment. The gas compressor 1A includes a twin-shaft type gas booster 2A including a first structure 21 and a second structure 22, and a bidirectional pump 71 that constitutes a hydraulic circuit together with a part of the gas booster 2A.

[0018] In the present embodiment, the gas compressor 1A compresses gas in two stages. The gas to be compressed is not particularly limited, and is, for example, hydrogen. The gas compressor 1A also includes an electric motor 72 that drives the bidirectional pump 71, and a control device 8 that controls the rotation speed of the electric motor 72.

[0019] The first structure 21 includes a gas cylinder 3A, a hydraulic cylinder 4A and a rod 65, and the second structure 22 includes a gas cylinder 3B, a hydraulic cylinder 4B and a rod 66. A major difference between the first structure 21 and the second structure 22 is the size of the gas cylinders 3A and 3B. Specifically, the diameter of a second gas piston 37, which will be described later, is smaller than the diameter of a first gas piston 33, which will be 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 volume in gas cylinder tubes 31 and 35, which will be described later, may be different depending on factors other than the diameters of the first gas piston 33 and the second gas piston 37.

[0020] In the first structure 21, the gas cylinder 3A and the hydraulic cylinder 4A are arranged coaxially, and in the second structure 22, the gas cylinder 3B and the hydraulic cylinder 4B are arranged coaxially. In the present embodiment, the axial directions of the gas cylinders 3A, 3B and the hydraulic cylinders 4A, 4B are the vertical direction. Further, in the present embodiment, the hydraulic cylinder 4A is arranged below the gas cylinder 3A, and the hydraulic cylinder 4B is arranged below the gas cylinder 3B. However, the axial directions of the gas cylinders 3A, 3B and the hydraulic cylinders 4A, 4B may be horizontal directions.

[0021] Regarding the first structure 21, 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 is located on one side of the gas cylinder tube 31 that is opposite to the hydraulic cylinder 4A, and closes the upper opening of the gas cylinder tube 31. The first gas piston 33 is arranged inside the gas cylinder tube 31 and forms a first compression chamber 3a between the first gas piston 33 and the gas cover 32. That is, the first gas piston 33 faces the first compression chamber 3a.

[0022] 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.

[0023] The gas cover 32 has, for example, a disk shape. In the present embodiment, the gas cover 32 is provided with a suction port 5a and a discharge port 5b on an end face facing radially outward. However, one or both of the suction port 5a and the discharge port 5b may be provided on the upper surface of the gas cover 32.

[0024] The gas cover 32 has a gas passage 51 leading from the intake port 5a to the first compression chamber 3a, and a gas passage 53 leading from the first compression chamber 3a to the discharge port 5b. Check valves 52 and 54 are provided in the gas passages 51 and 53, respectively.

[0025] However, the check valve 52 may be provided in the gas supply passage 11 described later, and the check valve 54 may be provided in the gas communication passage 12 described later. In this case, the intake port 5a and the discharge port 5b may be provided at the top of the gas cylinder tube 31, and the gas passages 51 and 53 may be omitted. When the intake port 5a and the discharge port 5b are provided in the gas cylinder tube 31, the piping constituting the gas supply passage 11 may pass through the jacket 34 and be connected to the intake port 5a, and the piping constituting the gas communication passage 12 may pass through the jacket 34 and be connected to the discharge port 5b.

[0026] The hydraulic cylinder 4A includes a hydraulic cylinder tube 41, a pair of hydraulic covers 42, 43, and a first hydraulic piston 44. The hydraulic cylinder tube 41 is cylindrical and extends vertically, and the hydraulic covers 42, 43 are located on both sides of the hydraulic cylinder tube 41. Hydraulic cover 42 closes the upper opening of the hydraulic cylinder tube 41, and hydraulic cover 43 closes the lower opening of the hydraulic cylinder tube 41.

[0027] The first hydraulic piston 44 is positioned inside the hydraulic cylinder tube 41 and forms a first working chamber 4a between itself and the hydraulic cover 42, and a second working chamber 4b between itself and the hydraulic cover 43. In other words, the first hydraulic piston 44 separates the first working chamber 4a and the second working chamber 4b. In this embodiment, the first hydraulic piston 44 is a single plate, but the first hydraulic piston 44 may be composed of two plates and a rod between them. In this case, hydraulic fluid may be supplied between the two plates.

[0028] In this embodiment, the lower opening of the gas cylinder tube 31 is closed by the hydraulic cover 42. The rod 65 traverses the first working 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 booster 100 shown in Figure 6, 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 65.

[0029] The hydraulic covers 42 and 43 are, for example, disc-shaped. In this embodiment, the hydraulic cover 42 has a supply and discharge port 6a on an end face facing radially outward, and the hydraulic cover 43 has a supply and discharge port 6b on an end face facing radially outward. However, the positions of the supply and discharge ports 6a and 6b are not limited to these. For example, the supply and discharge port 6a may be provided at the upper part of the hydraulic cylinder tube 41 and the hydraulic passage 61 described later may be omitted, or the supply and discharge port 6b may be provided at the lower part of the hydraulic cylinder tube 41 and the hydraulic passage 62 described later may be omitted.

[0030] The hydraulic cover 42 has a hydraulic passage 61 that connects the supply and discharge port 6a to the first working chamber 4a, and the hydraulic cover 43 has a hydraulic passage 62 that connects the supply and discharge port 6b to the second working chamber 4b.

[0031] With respect to the second structure 22, 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 is located on one side of the gas cylinder tube 35 opposite to the hydraulic cylinder 4B and closes the upper opening of the gas cylinder tube 35. 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.

[0032] 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.

[0033] The gas cover 36 is, for example, disc-shaped. In this embodiment, the gas cover 36 has an intake port 5c and a discharge port 5d on an end face facing radially outward. However, one or both of the intake port 5c and the discharge port 5d may be on the upper surface of the gas cover 36.

[0034] The gas cover 36 has a gas passage 55 leading from the intake port 5c to the second compression chamber 3b, and a gas passage 57 leading from the second compression chamber 3b to the discharge port 5d. Check valves 56 and 58 are provided in the gas passages 55 and 57, respectively.

[0035] However, the check valve 56 may be provided in the gas communication passage 12 described later, and the check valve 58 may be provided in the gas discharge passage 13 described later. In this case, the intake port 5c and the discharge port 5d may be provided at the top of the gas cylinder tube 35, and the gas passages 55 and 57 may be omitted. When the intake port 5c and the discharge port 5d 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 5c, and the piping constituting the gas discharge passage 13 may pass through the jacket 38 and connect to the discharge port 5d.

[0036] 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, and the hydraulic covers 46, 47 are located on both sides of the hydraulic cylinder tube 45. Hydraulic cover 46 closes the upper opening of the hydraulic cylinder tube 45, and hydraulic cover 47 closes the lower opening of the hydraulic cylinder tube 45.

[0037] The second hydraulic piston 48 is positioned inside the hydraulic cylinder tube 45 and forms a third working chamber 4c between itself and the hydraulic cover 46, and a fourth working chamber 4d between itself and the hydraulic cover 47. In other words, the second hydraulic piston 48 separates the third working chamber 4c and the fourth working chamber 4d. In this embodiment, the second hydraulic piston 48 is a single plate, but the second hydraulic piston 48 may be composed of two plates and a rod between them. In this case, hydraulic fluid may be supplied between the two plates.

[0038] In this embodiment, the lower opening of the gas cylinder tube 35 is closed by the hydraulic cover 46. The rod 66 traverses the third working 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 booster 100 shown in Figure 6, 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 66.

[0039] The hydraulic covers 46 and 47 are, for example, disc-shaped. In this embodiment, the hydraulic cover 46 has a supply and discharge port 6c on an end face facing radially outward, and the hydraulic cover 47 has a supply and discharge port 6d on an end face facing radially outward. However, the positions of the supply and discharge ports 6c and 6d are not limited to these. For example, the supply and discharge port 6c may be provided at the top of the hydraulic cylinder tube 45 and the hydraulic passage 63 described later may be omitted, or the supply and discharge port 6d may be provided at the bottom of the hydraulic cylinder tube 45 and the hydraulic passage 64 described later may be omitted.

[0040] The hydraulic cover 46 has a hydraulic passage 63 that connects the supply and discharge port 6c to the third working chamber 4c, and the hydraulic cover 47 has a hydraulic passage 64 that connects the supply and discharge port 6d to the fourth working chamber 4d.

[0041] A gas supply passage 11 is connected to the intake port 5a of the first structure 21, and a gas discharge passage 13 is connected to the discharge port 5d of the second structure 22. In addition, the discharge port 5b of the first structure 21 and the intake port 5c of the second structure 22 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.

[0042] The first gas piston 33 and the second gas piston 37 move alternately. When 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 51. 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 53, the gas connecting passage 12, and the gas passage 55. At this time, the gas is compressed due to the area difference between the first compression chamber 3a and the second compression chamber 3b. That is, when the pressure in the first compression chamber 3a is lower than the pressure in the second compression chamber 3b, the gas is compressed in the first compression chamber 3a, the gas passage 53, and the gas connecting passage 12, and when the pressure in the first compression chamber 3a becomes equal to or greater than the pressure in the second compression chamber 3b, the gas is compressed in the first compression chamber 3a, the gas passage 53, the gas connecting passage 12, the gas passage 55, and the second compression chamber 3b. 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 58, and the compressed gas is discharged through the gas passage 57 and the gas discharge passage 13.

[0043] The supply and discharge port 6b of the first structure 21 and the supply and discharge port 6d of the second structure 22 are connected to each other by a hydraulic communication passage 14. In other words, the hydraulic communication passage 14 connects the second working chamber 4b of the first structure 21 and the fourth working chamber 4d of the second structure 22. For this reason, in this embodiment, the first working chamber 4a of the first structure 21 functions as the first drive chamber 2a, and the third working chamber 4c of the second structure 22 functions as the second drive chamber 2b.

[0044] The diameter of the first hydraulic piston 44 of the first structure 21 and the diameter of the second hydraulic piston 48 of the second structure 22 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.

[0045] The bidirectional pump 71 described above is connected to the supply and discharge port 6a of the first structure 21 by a supply and discharge passage 73, and to the supply and discharge port 6c of the second structure 22 by a supply and discharge passage 74. The bidirectional pump 71 supplies hydraulic fluid to one of the first drive chamber 2a and the second drive chamber 2b, and draws hydraulic fluid from the other.

[0046] When hydraulic fluid is supplied from the bidirectional pump 71 to the first drive chamber 2a through the supply / discharge passage 73 and the hydraulic passage 61, the first hydraulic piston 44 descends together with the first gas piston 33, and hydraulic fluid is supplied from the second drive chamber 4b to the fourth drive chamber 4d through the hydraulic passage 62, the hydraulic connecting passage 14 and the hydraulic passage 64. When hydraulic fluid is supplied to the fourth drive chamber 4d, the second hydraulic piston 48 rises together with the second gas piston 37, and hydraulic fluid flows out from the second drive chamber 2b to the supply / discharge passage 74 through the hydraulic passage 63.

[0047] Conversely, when hydraulic fluid is supplied from the bidirectional pump 71 to the second drive chamber 2b through the supply / discharge passage 74 and the hydraulic passage 63, the second hydraulic piston 48 descends together with the second gas piston 37, and hydraulic fluid is supplied from the fourth drive chamber 4d to the second drive chamber 4b through the hydraulic passage 64, the hydraulic connecting passage 14, and the hydraulic passage 62. When hydraulic fluid is supplied to the second drive chamber 4b, the first hydraulic piston 44 rises together with the first gas piston 33, and hydraulic fluid flows out from the first drive chamber 2a to the supply / discharge passage 73 through the hydraulic passage 61.

[0048] For example, the bidirectional pump 71 is an axial piston pump. In this embodiment, the bidirectional pump 71 is a pump whose hydraulic fluid discharge direction can be switched depending on the direction of rotation. However, the bidirectional pump 71 may also be a pump that rotates in one direction, and whose hydraulic fluid discharge direction can be switched depending on the tilt direction from the center of the swash plate or slanted shaft. In this case, the control device 9 controls not only the electric motor 72 but also a regulator that changes the tilt angle of the bidirectional pump 71. Also, although the bidirectional pump 71 is a variable displacement pump in the illustrated example, the bidirectional pump 71 may also be a fixed displacement pump.

[0049] The supply and discharge passage 73 is connected to the tank by a tank passage 75, and a check valve 76 is provided in the tank passage 75. Similarly, the supply and discharge passage 74 is connected to the tank by a tank passage 77, and a check valve 78 is provided in the tank passage 77.

[0050] Furthermore, the supply and discharge passage 73 is connected to the tank by a relief passage 81, and a relief valve 82 is provided in the relief passage 81. Similarly, the supply and discharge passage 74 is connected to the tank by a relief passage 83, and a relief valve 84 is provided in the relief passage 83.

[0051] The control device 8 for controlling the rotational speed of the electric motor 72 includes, for example, a first device such as an inverter or servo amplifier interposed between the electric motor 72 and the power supply, and a second device that outputs commands to the first device.

[0052] With respect to the control device 8, 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 that is 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.

[0053] The control device 8 maintains the rotational speed N of the electric motor 72 at a target value Nt when supplying power to the electric motor 72. The target value Nt may be a fixed value or a variable value. Furthermore, the control device 8 maintains the rotational speed N of the electric motor 72 at the target value Nt even when power is being generated by the electric motor 72.

[0054] More specifically, when the second gas piston 37 moves upward, in other words, in a direction that reduces the second compression chamber 3b, if the product of the pressure in the first compression chamber 3a and the area of ​​the first gas piston 33 is greater than the product of the pressure in the second compression chamber 3b and the area of ​​the second gas piston 37, then the pressure in the first compression chamber 3a pushes down the first gas piston 33, and hydraulic fluid is pushed out from the second drive chamber 2b. Also, when the first gas piston 33 moves upward, in other words, in a direction that reduces the first compression chamber 3a, if the product of the pressure in the first compression chamber 3a and the area of ​​the first gas piston 33 is less than the product of the pressure in the second compression chamber 3b and the area of ​​the second gas piston 37, then the pressure in the second compression chamber 3b pushes down the second gas piston 37, and hydraulic fluid is pushed out from the first drive chamber 2a. When hydraulic fluid is pushed out from the second drive chamber 2b or the first drive chamber 2a, the bidirectional pump 71 is driven as a motor, and power is generated by the electric motor 72.

[0055] For example, the control device 8 may include a regenerative converter that converts alternating current to direct current, and the generated power may be stored in a battery or supplied to other equipment. Alternatively, the control device 8 may release the generated power as heat.

[0056] As described above, in the gas compressor 1A of this embodiment, a bidirectional pump 71 is used, so the direction to which the hydraulic fluid is supplied, the first drive chamber 2a or the second drive chamber 2b, can be switched by switching the discharge direction of the bidirectional pump 71. Therefore, pressure loss can be reduced compared to when a directional control valve is used. As a result, heat generation of the hydraulic fluid can be suppressed.

[0057] Furthermore, in this embodiment, the control device 8 maintains the rotational speed N of the electric motor 72 at the target value Nt both when supplying power to the electric motor 72 and when power is generated by the electric motor 72. Therefore, even when the hydraulic fluid is pushed out from the second drive chamber 2b or the first drive chamber 2a by the pressure in the first compression chamber 3a or the second compression chamber 3b, the gas booster 2A can be operated at the desired speed.

[0058] <Variation> As shown in the modified gas compressor 1B in Figure 2, the first working chamber 4a of the first structure 21 and the third working chamber 4c of the second structure 22 of the gas booster 2B may be in communication through a hydraulic communication passage 14, the fourth working chamber 4d of the second structure 22 may function as the first drive chamber 2a, and the second working chamber 4b of the first structure 21 may function as the second drive chamber 2b.

[0059] Furthermore, as shown in the modified gas compressor 1C in Figure 3, the gas cylinder 3A of the first structure 21 and the gas cylinder 3B of the second structure 22 of the gas booster 2C are connected in parallel by a gas supply passage 15 and a gas discharge passage 16, and the gas compressor 1C compresses the gas in a single stage. In this case, the diameter of the second gas piston 37 is equal to the diameter of the first gas piston 33.

[0060] In Figure 3, the second working chamber 4b of the first structure 21 and the fourth working chamber 4d of the second structure 22 are in communication through the hydraulic communication passage 14, similar to the first embodiment. However, similar to Figure 2, the first working chamber 4a of the first structure 21 and the third working chamber 4c of the second structure 22 may be in communication through the hydraulic communication passage 14.

[0061] <Second Embodiment> Figure 4 shows a gas compressor 1D according to the second embodiment. In this embodiment as well, the gas compressor 1D compresses the gas in two stages, but the gas compressor 1D includes a single-shaft type gas booster 2D. In this embodiment, the same reference numerals are used for components identical to those in the first embodiment, and redundant explanations are omitted.

[0062] Specifically, the gas booster 2D includes the gas cylinders 3A and 3B described in the first embodiment, a hydraulic cylinder 4C positioned between the gas cylinders 3A and 3B, and a pair of rods 95 and 96.

[0063] Gas cylinders 3A and 3B are arranged coaxially and facing opposite directions, and hydraulic cylinder 4C is also arranged coaxially with gas cylinders 3A and 3B. In this embodiment, the axial direction of gas cylinders 3A, 3B and hydraulic cylinder 4C is lateral, but the axial direction of gas cylinders 3A, 3B and hydraulic cylinder 4C may be vertical. For the sake of explanation, the gas cylinder 3A side will be referred to as the left, and the gas cylinder 3B side as the right.

[0064] The hydraulic cylinder 4C includes a hydraulic cylinder tube 91, a pair of hydraulic covers 92 and 93, and a hydraulic piston 94. The hydraulic cylinder tube 91 is a cylindrical shape extending laterally, and the hydraulic covers 92 and 93 are located on both sides of the hydraulic cylinder tube 91. Hydraulic cover 92 closes the opening on the left side of the hydraulic cylinder tube 91, and hydraulic cover 93 closes the opening on the right side of the hydraulic cylinder tube 91. The hydraulic piston 94 is positioned inside the hydraulic cylinder tube 91 and forms a first drive chamber 2a with hydraulic cover 92 and a second drive chamber 2b with hydraulic cover 93. In other words, the hydraulic piston 94 separates the first drive chamber 2a and the second drive chamber 2b.

[0065] In this embodiment, the opening of the gas cylinder tube 35 of gas cylinder 3A on the hydraulic cylinder 4C side is closed by the hydraulic cover 92, and the opening of the gas cylinder tube 35 of gas cylinder 3B on the hydraulic cylinder 4C side is closed by the hydraulic cover 92. Rod 95 crosses the first drive chamber 2a and passes through the hydraulic cover 92 to connect the first gas piston 33 and the hydraulic piston 94, and rod 96 crosses the second drive chamber 2b and passes through the hydraulic cover 93 to connect the second gas piston 37 and the hydraulic piston 94.

[0066] The hydraulic covers 92 and 93 are, for example, disc-shaped. In this embodiment, the hydraulic cover 92 has a supply and discharge port 6e on its radially outward-facing end face, and the hydraulic cover 93 has a supply and discharge port 6f on its radially outward-facing end face. However, the positions of the supply and discharge ports 6e and 6f are not limited to these. For example, the supply and discharge port 6e may be provided on the left side of the hydraulic cylinder tube 91 and the hydraulic passage 67 described later may be omitted, or the supply and discharge port 6f may be provided on the right side of the hydraulic cylinder tube 91 and the hydraulic passage 68 described later may be omitted.

[0067] The hydraulic cover 92 has a hydraulic passage 67 that connects the supply and discharge port 6e to the first drive chamber 2a, and the hydraulic cover 93 has a hydraulic passage 68 that connects the supply and discharge port 6f to the second drive chamber 2b.

[0068] Similar to the first embodiment, the supply and discharge port 6e is connected to the bidirectional pump 71 by the supply and discharge passage 73, and the supply and discharge port 6f is connected to the bidirectional pump 71 by the supply and discharge passage 74. The bidirectional pump 71 supplies hydraulic fluid to one of the first drive chamber 2a and the second drive chamber 2b, and draws hydraulic fluid from the other.

[0069] When hydraulic fluid is supplied from the bidirectional pump 71 to the first drive chamber 2a through the supply / discharge passage 73 and the hydraulic passage 67, the hydraulic piston 94 moves to the right, causing hydraulic fluid to flow from the second drive chamber 2b to the supply / discharge passage 74 through the hydraulic passage 68. The first gas piston 33 of gas cylinder 3A and the second gas piston 37 of gas cylinder 3B also move to the right along with the hydraulic piston 94. The movement of the first gas piston 33 to the right causes gas to be supplied from the gas supply passage 11 to the first compression chamber 3a through the gas passage 51. The movement of the second gas piston 37 to the right causes the gas in the second compression chamber 3b to be compressed to at least the pressure downstream of the check valve 58, and the compressed gas is discharged through the gas passage 57 and the gas discharge passage 13.

[0070] Conversely, when hydraulic fluid is supplied from the bidirectional pump 71 to the second drive chamber 2b through the supply and discharge passage 74, the hydraulic piston 94 moves to the left, and hydraulic fluid flows out from the first drive chamber 2a to the supply and discharge passage 73 through the hydraulic passage 67. The first gas piston 33 of gas cylinder 3A and the second gas piston 37 of gas cylinder 3B also move to the left along with the hydraulic piston 94. As a result, gas is supplied from the first compression chamber 3a to the second compression chamber 3b through the gas passage 53, the gas communication passage 12, and the gas passage 55. At this time, the gas is compressed due to the area difference between the first compression chamber 3a and the second compression chamber 3b. In other words, when the pressure in the first compression chamber 3a is lower than the pressure in the second compression chamber 3b, the gas is compressed in the first compression chamber 3a, the gas flow path 53, and the gas connecting passage 12. When the pressure in the first compression chamber 3a becomes equal to or greater than the pressure in the second compression chamber 3b, the gas is compressed in the first compression chamber 3a, the gas flow path 53, the gas connecting passage 12, the gas flow path 55, and the second compression chamber 3b.

[0071] In this embodiment as well, since a bidirectional pump 71 is used, the direction to which the hydraulic fluid is supplied, to the first drive chamber 2a or the second drive chamber 2b, can be switched by switching the discharge direction of the bidirectional pump 71. Therefore, pressure loss can be reduced compared to when a directional control valve is used. As a result, heat generation of the hydraulic fluid can be suppressed.

[0072] Furthermore, in this embodiment as in the first embodiment, the control device 8 maintains the rotational speed N of the electric motor 72 at the target value Nt both when supplying power to the electric motor 72 and when power is generated by the electric motor 72. Therefore, even when the hydraulic fluid is pushed out from the second drive chamber 2b or the first drive chamber 2a by the pressure in the first compression chamber 3a or the second compression chamber 3b, the gas booster 2D can be operated at the desired speed.

[0073] <Variation> As shown in the modified gas compressor 1E in Figure 5, the gas cylinders 3A and 3B of the gas booster 2E are connected in parallel by a gas supply passage 17 and a gas discharge passage 18, and the gas compressor 1E may compress the gas in a single stage. In this case, the diameter of the second gas piston 37 is equal to the diameter of the first gas piston 33.

[0074] <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.

[0075] <Summary> In a first aspect, the present disclosure provides a gas compressor comprising, in a first aspect, a gas booster including a first compression chamber, a second compression chamber, a first drive chamber, and a second drive chamber, wherein when hydraulic fluid is supplied to the first drive chamber, gas is supplied to the first compression chamber, the gas is compressed in the second compression chamber, and hydraulic fluid flows out of the second drive chamber, and when hydraulic fluid is supplied to the second drive chamber, gas is compressed in the first compression chamber, gas is supplied to the second compression chamber, and hydraulic fluid flows out of the first drive chamber; a bidirectional pump that supplies hydraulic fluid to one of the first drive chamber and the second drive chamber and draws hydraulic fluid from the other; an electric motor that drives the bidirectional pump; and a control device that controls the rotational speed of the electric motor.

[0076] With the above configuration, since a bidirectional pump is used, the direction to which the hydraulic fluid is supplied—either to the first drive chamber or the second drive chamber—can be switched by switching the discharge direction of the bidirectional pump. Therefore, pressure loss can be reduced compared to when a directional control valve is used.

[0077] In a second embodiment, in the first embodiment, for example, the gas booster includes a first structure including a first gas piston facing the first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that separates the first working chamber from the second working chamber and crosses the first working chamber; a second structure including a second gas piston facing the second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that separates the third working chamber from the fourth working chamber and crosses the third working chamber; and a communication passage connecting the second working chamber and the fourth working chamber, wherein the first working chamber functions as the first drive chamber and the third working chamber functions as the second drive chamber.

[0078] In a third embodiment, in the first embodiment, for example, the gas booster includes a first structure including a first gas piston facing the first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that separates the first working chamber from the second working chamber and crosses the first working chamber; a second structure including a second gas piston facing the second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that separates the third working chamber from the fourth working chamber and crosses the third working chamber; and a communication passage connecting the first working chamber and the third working chamber, wherein the fourth working chamber functions as the first drive chamber and the second working chamber functions as the second drive chamber.

[0079] In a fourth embodiment, in the first embodiment, for example, the gas booster may include a first gas piston facing the first compression chamber, a second gas piston facing the second compression chamber, and a hydraulic piston that separates the first drive chamber and the second drive chamber, and is connected to the first gas piston by a rod that crosses the first drive chamber, and is also connected to the second gas piston by a rod that crosses the second drive chamber.

[0080] In a fifth aspect, the present disclosure provides a gas booster comprising a first structure, a second structure, and a communication passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that partitions a first working chamber and a second working chamber and crosses the first working chamber; the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that partitions a third working chamber and a fourth working chamber and crosses the third working chamber; and the communication passage connects the second working chamber and the fourth working chamber, comprising a gas booster, a bidirectional pump that supplies hydraulic fluid to one of the first and third working chambers and draws hydraulic fluid from the other, an electric motor that drives the bidirectional pump, and a control device that controls the rotational speed of the electric motor.

[0081] In the fifth embodiment, as in the first embodiment, a bidirectional pump is used, so the direction to which the hydraulic fluid is supplied, whether to the first working chamber or the third working chamber, can be switched by switching the discharge direction of the bidirectional pump. Therefore, pressure loss can be reduced compared to when a directional control valve is used.

[0082] In a sixth aspect, the present disclosure provides a gas booster comprising a first structure, a second structure and a communication passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that partitions a first working chamber and a second working chamber and crosses the first working chamber; the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that partitions a third working chamber and a fourth working chamber and crosses the third working chamber; and the communication passage connects the first working chamber and the third working chamber, comprising a gas booster, a bidirectional pump that supplies hydraulic fluid to one of the second and fourth working chambers and draws hydraulic fluid from the other, an electric motor that drives the bidirectional pump, and a control device that controls the rotational speed of the electric motor.

[0083] In the fifth embodiment, as in the first embodiment, a bidirectional pump is used, so the direction to which the hydraulic fluid is supplied, either to the second working chamber or the fourth working chamber, can be switched by switching the discharge direction of the bidirectional pump. Therefore, the pressure loss can be reduced compared to when a directional control valve is used.

[0084] In a seventh aspect, the present disclosure provides a gas compressor comprising, in a fourth aspect, a gas booster including a first gas piston facing a first compression chamber, a second gas piston facing a second compression chamber, and a hydraulic piston that separates a first drive chamber from a second drive chamber and is connected to the first gas piston by a rod traversing the first drive chamber and connected to the second gas piston by a rod traversing the second drive chamber; a bidirectional pump that supplies hydraulic fluid to one of the first and second drive chambers and draws hydraulic fluid from the other; an electric motor that drives the bidirectional pump; and a control device that controls the rotational speed of the electric motor.

[0085] In the seventh embodiment, as in the first embodiment, a bidirectional pump is used, so the direction to which the hydraulic fluid is supplied, whether to the first or second drive chamber, can be switched by switching the discharge direction of the bidirectional pump. Therefore, pressure loss can be reduced compared to when a directional control valve is used.

[0086] In an eighth aspect, in any of the first to seventh aspects, the diameter of the second gas piston facing the second compression chamber is smaller than the diameter of the first gas piston facing the first compression chamber, and gas is supplied from the first compression chamber to the second compression chamber. With this configuration, the gas can be compressed in two stages.

[0087] In a ninth aspect, in the eighth aspect, the control device may maintain the rotational speed of the motor at a target value both when supplying power to the motor and when power is generated by the motor. With this configuration, the gas booster can be operated at a desired speed even when the hydraulic fluid is pushed out by the pressure in the first or second compression chamber.

[0088] In a tenth embodiment, in the ninth embodiment, for example, when power is generated by the electric motor, the product of the pressure in the first compression chamber and the area of ​​the first gas piston when the second gas piston moves in the direction of reducing the second compression chamber may be greater than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, or the product of the pressure in the first compression chamber and the area of ​​the first gas piston when the first gas piston moves in the direction of reducing the first compression chamber may be less than the product of the pressure in the second compression chamber and the area of ​​the second gas piston. [Explanation of symbols]

[0089] 1A, 1B, 1C, 1D, 1E Gas Compressors 2A, 2B, 2C, 2D, 2E Gas Boosters 21 First structure 22 Second structure 2a First drive chamber 2b Second drive chamber 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 1st working chamber 4b Second Working Chamber 4c Third working chamber 4d 4th working chamber 65, 66 rods 71 Bidirectional pump 72 Electric motor 8 Control device 94 Hydraulic Piston 95,96 rods

Claims

1. A gas booster comprising a first compression chamber, a second compression chamber, a first drive chamber, and a second drive chamber, wherein when hydraulic fluid is supplied to the first drive chamber, gas is supplied to the first compression chamber, the gas is compressed in the second compression chamber, and hydraulic fluid flows out of the second drive chamber, and when hydraulic fluid is supplied to the second drive chamber, gas is compressed in the first compression chamber, gas is supplied to the second compression chamber, and hydraulic fluid flows out of the first drive chamber, A bidirectional pump that supplies hydraulic fluid to one of the first drive chamber and the second drive chamber and draws hydraulic fluid from the other, The electric motor that drives the bidirectional pump, The system includes a control device for controlling the rotational speed of the electric motor, The gas booster includes a first gas piston facing the first compression chamber and a second gas piston facing the second compression chamber. When the second gas piston rises and moves in a direction that reduces the second compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is greater than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the first compression chamber pushes down the first gas piston, pushing out hydraulic fluid from the second drive chamber, and the hydraulic fluid pushed out from the second drive chamber drives the bidirectional pump as a motor, generating electricity with the electric motor. A gas compressor wherein, when the first gas piston rises and moves in a direction that reduces the first compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is less than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the second compression chamber pushes down the second gas piston, causing hydraulic fluid to be pushed out of the first drive chamber, and the hydraulic fluid pushed out of the first drive chamber drives the bidirectional pump as a motor, generating electricity with the electric motor.

2. The aforementioned gas booster is A first structure including a first hydraulic piston that separates a first working chamber and a second working chamber and is connected to the first gas piston by a rod that crosses the first working chamber, A second structure including a second hydraulic piston that separates the third and fourth working chambers and is connected to the second gas piston by a rod that crosses the third working chamber, It includes a communication passage connecting the second working chamber and the fourth working chamber, The gas compressor according to claim 1, wherein the first working chamber functions as the first drive chamber and the third working chamber functions as the second drive chamber.

3. The aforementioned gas booster is A first structure including a first hydraulic piston that separates a first working chamber and a second working chamber and is connected to the first gas piston by a rod that crosses the first working chamber, A second structure including a second hydraulic piston that separates the third and fourth working chambers and is connected to the second gas piston by a rod that crosses the third working chamber, It includes a connecting passage that connects the first working chamber and the third working chamber, The gas compressor according to claim 1, wherein the fourth working chamber functions as the first drive chamber and the second working chamber functions as the second drive chamber.

4. The gas compressor according to claim 1, wherein the gas booster includes a hydraulic piston that separates the first drive chamber and the second drive chamber, is connected to the first gas piston by a rod that crosses the first drive chamber, and is connected to the second gas piston by a rod that crosses the second drive chamber.

5. A gas booster comprising a first structure, a second structure, and a connecting passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that separates a first working chamber from a second working chamber and crosses the first working chamber, the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that separates a third working chamber from a fourth working chamber and crosses the third working chamber, and the connecting passage connects the second working chamber and the fourth working chamber, the gas booster and A bidirectional pump that supplies hydraulic fluid to one of the first and third working chambers and draws hydraulic fluid from the other, The electric motor that drives the bidirectional pump, The system includes a control device for controlling the rotational speed of the electric motor, When the second gas piston rises and moves in a direction that reduces the second compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is greater than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the first compression chamber pushes down the first gas piston, pushing out hydraulic fluid from the third working chamber, and the hydraulic fluid pushed out from the third working chamber drives the bidirectional pump as a motor, generating electricity with the electric motor. A gas compressor wherein, when the first gas piston rises and moves in a direction that reduces the first compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is less than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the second compression chamber pushes down the second gas piston, causing hydraulic fluid to be pushed out of the first working chamber, and the hydraulic fluid pushed out of the first working chamber drives the bidirectional pump as a motor, generating electricity with the electric motor.

6. A gas booster comprising a first structure, a second structure, and a connecting passage, wherein the first structure includes a first gas piston facing a first compression chamber and a first hydraulic piston connected to the first gas piston by a rod that separates a first working chamber from a second working chamber and crosses the first working chamber, the second structure includes a second gas piston facing a second compression chamber and a second hydraulic piston connected to the second gas piston by a rod that separates a third working chamber from a fourth working chamber and crosses the third working chamber, and the connecting passage connects the first working chamber and the third working chamber, the gas booster and A bidirectional pump that supplies hydraulic fluid to one of the second and fourth working chambers and draws hydraulic fluid from the other, The electric motor that drives the bidirectional pump, The system includes a control device for controlling the rotational speed of the electric motor, When the second gas piston rises and moves in a direction that reduces the second compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is greater than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the first compression chamber pushes down the first gas piston, pushing out hydraulic fluid from the second working chamber, and the hydraulic fluid pushed out from the second working chamber drives the bidirectional pump as a motor, generating electricity with the electric motor. A gas compressor wherein, when the first gas piston rises and moves in a direction that reduces the first compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is less than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the second compression chamber pushes down the second gas piston, causing hydraulic fluid to be pushed out of the fourth working chamber, and the hydraulic fluid pushed out of the fourth working chamber drives the bidirectional pump as a motor, generating electricity with the electric motor.

7. A gas booster including a first gas piston facing a first compression chamber, a second gas piston facing a second compression chamber, and a hydraulic piston that separates the first drive chamber and the second drive chamber, and is connected to the first gas piston by a rod that crosses the first drive chamber, and is also connected to the second gas piston by a rod that crosses the second drive chamber, A bidirectional pump that supplies hydraulic fluid to one of the first drive chamber and the second drive chamber and draws hydraulic fluid from the other, The electric motor that drives the bidirectional pump, The system includes a control device for controlling the rotational speed of the electric motor, When the second gas piston rises and moves in a direction that reduces the second compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is greater than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the first compression chamber pushes down the first gas piston, pushing out hydraulic fluid from the second drive chamber, and the hydraulic fluid pushed out from the second drive chamber drives the bidirectional pump as a motor, generating electricity with the electric motor. A gas compressor wherein, when the first gas piston rises and moves in a direction that reduces the first compression chamber, if the product of the pressure in the first compression chamber and the area of ​​the first gas piston is less than the product of the pressure in the second compression chamber and the area of ​​the second gas piston, the pressure in the second compression chamber pushes down the second gas piston, causing hydraulic fluid to be pushed out of the first drive chamber, and the hydraulic fluid pushed out of the first drive chamber drives the bidirectional pump as a motor, generating electricity with the electric motor.

8. The gas compressor according to any one of claims 1 to 7, wherein the diameter of the second gas piston is smaller than the diameter of the first gas piston, and gas is supplied from the first compression chamber to the second compression chamber.

9. The gas compressor according to claim 8, wherein the control device maintains the rotational speed of the electric motor at a target value both when supplying power to the electric motor and when power is generated by the electric motor.

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