A small-displacement flexible piston compressor

Abstract

The present invention discloses a small-displacement flexible piston compressor, comprising a compressor cavity, a swash plate disposed within the compressor cavity, a multi-stage compressor connected to the slanted end of the swash plate, and a main shaft connected to the flat end of the swash plate. In the multi-stage compressor, each stage includes a cylinder, an intake valve, an exhaust valve, a gas piston, a liquid piston, a piston rod, a ball joint connecting rod, a refill valve assembly, a relief valve assembly, a waste liquid one-way valve, and a liquid inlet control valve. The gas piston, liquid piston, and piston rod within the cylinder are sequentially connected from top to bottom, and the piston rod is connected to the swash plate via a ball joint connecting rod. The present invention overcomes the problems of complex structure, large volume and weight caused by the separate hydraulic and gas compression structures in conventional ionic liquid compressors. The hydraulic and gas compression devices are placed within a single cylinder, and the swash plate mechanism drives the device to reciprocate, significantly simplifying the structural complexity and control difficulty, while also facilitating multi-stage compression.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressors, and in particular relates to a small-displacement flexible piston compressor. Background Art

[0002] The rise of hydrogen energy marks a major transformation in the energy sector, leading a new trend in sustainable development with its unique advantages. Its environmental friendliness makes hydrogen a powerful tool for reducing greenhouse gas emissions and addressing climate change; its high energy density gives it unparalleled advantages in long-distance transportation and heavy-load applications; and the widespread availability of hydrogen provides diverse pathways for hydrogen production, enhancing the stability of energy supply. Against this backdrop, the role of high-pressure hydrogen compressors cannot be underestimated.

[0003] In hydrogen energy storage systems, high-pressure hydrogen compressors not only compress hydrogen to a high pressure for efficient energy storage, but also ensure its safe storage and long-term stability by precisely controlling pressure and temperature. This process not only improves the overall performance of the energy storage system but also lays the foundation for the large-scale application of hydrogen energy. At hydrogen refueling stations, the performance of high-pressure hydrogen compressors is directly related to their operational efficiency and user experience. By efficiently compressing hydrogen, they ensure that hydrogen fuel cell vehicles can be refueled in a short time, comparable to the refueling time of traditional fuel vehicles, greatly improving the practicality and market competitiveness of hydrogen-powered vehicles. Furthermore, the compressor's reliability and durability are key factors in ensuring the long-term stable operation of hydrogen refueling stations. Therefore, high-pressure hydrogen compressors are not only an important bridge connecting hydrogen energy production and consumption but also key equipment in driving the hydrogen energy industry towards maturity.

[0004] In the field of hydrogen compressors, there are two main types: diaphragm type and liquid-driven type. Diaphragm compressors rely on a flexible diaphragm to complete the gas compression process. Their advantages are that they do not produce oil pollution, have low maintenance costs, can provide a higher pressure ratio, and are suitable for operating environments with low flow and high pressure ratios. However, the cost of this type of compressor is relatively high, and the compression speed is not fast. On the other hand, liquid-driven compressors use liquid to drive the piston or plunger for compression. They are known for their efficient compression capacity, ability to handle large flows, low vibration, and stability, but they may require more detailed maintenance and the system design is more complex. When deciding which compressor to use, it is necessary to comprehensively consider the specific application scenario, cost budget, and actual maintenance management.

[0005] Liquid-sealed compressors, exemplified by ionic liquid compressors, utilize a specialized liquid medium—ionic liquid—to replace the metal pistons in traditional compressors for gas compression. Due to their incompressibility, lack of saturated vapor pressure, and extremely low gas solubility, these ionic liquids ensure sealing and lubrication in high-pressure environments while effectively reducing energy waste. Ionic liquid compressors utilize the physical properties of ionic liquids to create volume changes within the compressor cylinder, resulting in gas compression. This technology offers significant advantages over traditional piston compressors. It not only addresses the common sealing and lubrication challenges faced in high-pressure environments, but also offers excellent wide-range operating conditions, high compression efficiency, and is more suitable for the development of large-displacement compressor models. Ionic liquid compressors also offer excellent environmental benefits, reducing lubricant usage and potentially lowering emissions. Their stable performance and low maintenance requirements make ionic liquid compressors a promising technology for applications in hydrogen energy, chemical engineering, and other industries requiring high-pressure gas compression.

[0006] However, ionic liquid compressors face multiple challenges in small-displacement design. Due to the presence of separate hydraulic and pneumatic systems, they are more expensive and complex, and are at a disadvantage in terms of size and weight compared to other compressors. These factors combine to result in their energy efficiency and economic benefits in small-displacement applications being lower than expected. In addition, since small-displacement applications often have higher requirements for the compactness and lightness of equipment, the limitations of ionic liquid compressors in this regard become more apparent. At the same time, the cost and complexity of maintaining and replacing ionic liquids are also issues that cannot be ignored in the small-displacement market. These factors jointly affect the market acceptance and promotion potential of ionic liquid compressors in the small-displacement field. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems of complex structure, large volume and weight caused by the separation of hydraulic and gas compression structures in traditional ionic liquid compressors, and to provide a small-displacement flexible piston compressor with relatively simple structure and reliable sealing.

[0008] The purpose of the present invention is to solve the problem through the following technical solutions:

[0009] A small-displacement flexible piston compressor is characterized by comprising a compressor cavity, a swash plate arranged in the compressor cavity, a multi-stage compressor connected to the inclined surface end of the swash plate, and a main shaft connected to the flat surface end of the swash plate.

[0010] In the multi-stage compressor, each stage of the compressor includes a cylinder, an intake valve, an exhaust valve, a gas piston, a liquid piston, a piston rod, a ball joint connecting rod, a liquid replenishing valve assembly, a relief valve assembly, a waste liquid check valve, and a liquid inlet control valve. The gas piston, the liquid piston, and the piston rod are connected in sequence from top to bottom in the cylinder, and the piston rod is connected to the swash plate through a ball joint connecting rod;

[0011] The cylinder body and the upper surface of the gas piston form a compression chamber, in which there is a sealing liquid; the surface of the middle part of the cylinder body and the gas piston forms a balance chamber, which is connected to the inlet of the waste liquid one-way valve through a pipeline; the lower surface of the gas piston and the upper surface of the liquid piston form a hydraulic chamber, in which there is hydraulic oil; an overflow channel is provided at the lower part of the gas piston, which is connected to the hydraulic chamber and the interior of the compressor cavity respectively, and an overflow valve assembly is installed on the overflow channel; a fluid replenishment channel is provided on the liquid piston, which is connected to the interior of the hydraulic chamber and the compressor cavity respectively, and a fluid replenishment valve assembly is installed on the fluid replenishment channel.

[0012] Furthermore, in the multi-stage compressor, the air intake valve of the first-stage compressor is respectively connected to the external air intake and the outlet of its own liquid inlet control valve, the air intake valves of the remaining compressors are respectively connected to the exhaust valve of the previous-stage compressor and the outlet of their own liquid inlet control valve, the exhaust valve of the last-stage compressor is connected to the inlet of the gas-liquid separator, the liquid outlet of the gas-liquid separator is connected to the inlet of the sealing liquid storage tank, the outlet of the sealing liquid storage tank is respectively connected to the liquid inlet control valve inlets of the compressors at each stage, and the outlet of the waste liquid one-way valve is connected to the waste liquid storage tank.

[0013] Furthermore, the gas piston is provided with a gas piston upper sealing assembly and a gas piston lower sealing assembly, and the liquid piston is provided with a liquid piston sealing assembly.

[0014] Furthermore, the gas piston upper sealing assembly, the gas piston lower sealing assembly, and the liquid piston sealing assembly are each composed of one ring or multiple rings. The gas piston upper sealing assembly, the gas piston lower sealing assembly, and the liquid piston sealing assembly are made of metal, non-metal, a combination of metal and non-metal, or a composite.

[0015] Furthermore, the compressor cavity is provided with a hydraulic oil circulation inlet and outlet, a heat exchanger and a circulation pump are connected between the hydraulic oil circulation inlet and outlet, and an energy storage tank is connected to the circulation pump outlet.

[0016] Furthermore, a heat exchanger is provided inside the compressor cavity, a pressure regulating valve is connected to the side wall of the compressor cavity through an opening, and an inlet of the pressure regulating valve is connected to a high-pressure gas source.

[0017] Furthermore, the sealing liquid is an aqueous or oily liquid with low solubility in the compressed gas.

[0018] The present invention places the hydraulic and gas compression devices in a cylinder body, and drives the devices to reciprocate through a swash plate mechanism, which greatly simplifies the structural complexity and control difficulty and also makes it easy to achieve multi-stage compression. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a small-displacement flexible piston compressor according to Example 1;

[0020] Figure 2 This is a schematic diagram of a small-displacement flexible piston compressor according to Example 2;

[0021] Figure 3 This is a schematic projection diagram of the swash plate of a multi-stage small-displacement flexible piston compressor according to Example 3;

[0022] Description of the numbers in the figure:

[0023] 1- swash plate; 2- compressor cavity; 3- main shaft; 4- heat exchanger; 5- circulating pump; 6- energy storage tank; 7- sealing liquid storage tank; 8- gas-liquid separator; 9- waste liquid storage tank; 10- high-pressure gas source; 11- pressure regulating valve;

[0024] 101-cylinder body; 102-intake valve; 103-exhaust valve, 104-gas piston, 105-gas piston upper sealing assembly, 106-gas piston lower sealing assembly, 107-liquid piston, 108-liquid piston sealing assembly, 109-piston rod, 110-ball connecting rod, 111-liquid replenishing valve assembly, 112-overflow valve assembly, 113-waste liquid one-way valve, 114-liquid inlet control valve;

[0025] 130 - compression chamber; 131 - balance chamber; 132 - overflow channel; 133 - fluid replenishment channel; 134 - hydraulic chamber; 150 - sealing liquid; 151 - hydraulic oil;

[0026] 201 - second cylinder; 202 - second air inlet valve; 203 - second exhaust valve, 204 - second gas piston, 205 - second gas piston upper sealing assembly, 206 - second gas piston lower sealing assembly, 207 - second liquid piston, 208 - second liquid piston sealing assembly, 209 - second piston rod, 210 - second ball-end connecting rod, 211 - second liquid replenishing valve assembly, 212 - second overflow valve assembly, 213 - second waste liquid one-way valve, 214 - second liquid inlet control valve;

[0027] 230 - second compression chamber; 231 - second balance chamber; 232 - second overflow channel; 233 - second fluid replenishing channel; 234 - second hydraulic chamber; 250 - second sealing liquid; 251 - second hydraulic oil;

[0028] 1001-first stage compressor; 1002-second stage compressor; 1003-third stage compressor; 1004-fourth stage compressor; 1005-fifth stage compressor; DETAILED DESCRIPTION

[0029] The structural features and technical implementation process of the present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0030] 1) Example 1

[0031] Figure 1 This is a schematic diagram of a small-displacement flexible piston compressor, which consists of two-stage compression. The first stage 1001 of the compressor includes a cylinder 101, an intake valve 102, an exhaust valve 103, a gas piston 104, a gas piston upper sealing assembly 105, a gas piston lower sealing assembly 106, a liquid piston 107, a liquid piston sealing assembly 108, a piston rod 109, a ball joint connecting rod 110, a liquid replenishing valve assembly 111, a relief valve assembly 112, a waste liquid check valve 113, and a liquid inlet control valve 114. The upper surfaces of the cylinder 101 and the gas piston 104 form a compression chamber 130, and the compression chamber 130 contains a sealing liquid 150.

[0032] The second stage 1002 of the compressor includes a second cylinder 201, a second intake valve 202, a second exhaust valve 203, a second gas piston 204, a second gas piston upper sealing assembly 205, a second gas piston lower sealing assembly 206, a second liquid piston 207, a second liquid piston sealing assembly 208, a second piston rod 209, a second ball joint connecting rod 210, a second liquid replenishing valve assembly 211, a second relief valve assembly 212, a second waste liquid check valve 213, and a second liquid inlet control valve 214. A second compression chamber 230 is formed on the upper surfaces of the second cylinder 201 and the second gas piston 204. A second sealing liquid 250 is contained in the second compression chamber 230.

[0033] A balance chamber 131 is formed on the surface of the middle part of the cylinder body 101 and the gas piston 104 of the first stage 1001 of the compressor, and the balance chamber 131 is connected to the inlet of the waste liquid check valve 113 through a pipeline; a hydraulic chamber 134 is formed on the lower surface of the gas piston 104 and the upper surface of the liquid piston 107, and hydraulic oil 151 is contained in the hydraulic chamber 134; an overflow channel 132 is opened at the lower part of the gas piston 104, and the overflow channel 132 is respectively connected to the hydraulic chamber 134 and the interior of the compressor cavity 2, and an overflow valve assembly 112 is installed on the overflow channel 132; a liquid replenishing channel 133 is opened on the liquid piston 107, and the liquid replenishing channel 133 is respectively connected to the hydraulic chamber 134 and the interior of the compressor cavity 2, and a liquid replenishing valve assembly 111 is installed on the liquid replenishing channel 133;

[0034] A second balancing chamber 231 is formed on the surface of the middle part of the second cylinder 201 and the second gas piston 204 of the second stage 1002 of the compressor, and the second balancing chamber 231 is connected to the inlet of the second waste liquid one-way valve 213 through a pipeline; a second hydraulic chamber 234 is formed on the lower surface of the second gas piston 204 and the upper surface of the second liquid piston 207, and second hydraulic oil 251 is contained in the second hydraulic chamber 234; a second overflow channel 232 is opened at the lower part of the second gas piston 204, and the second overflow channel 232 is communicated with the second hydraulic chamber 234 and the interior of the compressor cavity 2 respectively, and a second overflow valve assembly 212 is installed on the second overflow channel 232; a second liquid replenishing channel 233 is opened on the second liquid piston 207, and the second liquid replenishing channel 233 is communicated with the second hydraulic chamber 234 and the interior of the compressor cavity 2 respectively, and a second liquid replenishing valve assembly 211 is installed on the second liquid replenishing channel 233;

[0035] The swash plate 1 is placed in the compressor cavity 2 and is connected to the main shaft 3. The swash plate 1 is connected to the lower part of the ball joint connecting rod 110 and the second ball joint connecting rod 210;

[0036] The air inlet valve 102 is connected to the external air inlet and the outlet of the liquid inlet control valve 114 respectively, the air inlet valve 202 is connected to the outlet of the exhaust valve 103 and the second liquid inlet control valve 214 respectively, the second exhaust valve 203 is connected to the inlet of the gas-liquid separator 8, the liquid outlet of the gas-liquid separator 8 is connected to the inlet of the sealing liquid storage tank 7, and the outlet of the sealing liquid storage tank 7 is connected to the inlet of the liquid inlet control valve 114 and the inlet of the second liquid inlet control valve 214 respectively;

[0037] The outlets of the waste liquid one-way valve 113 and the second waste liquid one-way valve 213 are connected to the waste liquid storage tank 9;

[0038] The compressor cavity 2 is provided with a hydraulic oil circulation inlet and outlet, between which a heat exchanger 4 and a circulation pump 5 are connected, and the outlet of the circulation pump 5 is also connected to an energy storage tank 6;

[0039] The gas piston upper sealing assembly 105 and the second gas piston upper sealing assembly 205, the gas piston lower sealing assembly 106 and the second gas piston lower sealing assembly 206, and the liquid piston sealing assembly 108 and the second liquid piston sealing assembly 208 are composed of two support rings and a non-metallic polytetrafluoroethylene ring;

[0040] The second sealing liquid 203 is a room temperature ionic liquid;

[0041] When the main shaft 3 rotates, the swash plate 1 rotates, and the ball connecting rod 110 and the second ball connecting rod 210 connected to the swash plate 1 reciprocate up and down, thereby driving the liquid piston 107 to reciprocate up and down. Taking the first stage 1001 of the compressor as an example, when the liquid piston 107 moves to the top dead center, the volume of the hydraulic chamber 134 tends to decrease, and the hydraulic oil 151 is compressed. Since the compressibility of the hydraulic oil 151 is very low, it will push the gas piston 104 to move to the top dead center, so that the gas in the compression chamber 130 is compressed. After reaching a certain pressure, it is discharged from the exhaust valve 103 until the liquid piston 107 reaches the top dead center, completing the compression and exhaust process; when the liquid piston 107 moves to the bottom dead center, the volume of the hydraulic chamber 134 tends to increase, and the hydraulic oil 151 is expanded. Similarly, since the compressibility of the hydraulic oil 151 is very low, the pressure in the hydraulic chamber 134 decreases. Under the action of the gas pressure in the compression chamber 130, the gas piston 104 will move downward, and fresh gas will be sucked into the cylinder body 1 through the intake valve 102 until the liquid piston 107 reaches the bottom dead center, completing the expansion and intake process;

[0042] The pressure in the sealing liquid storage tank 7 is greater than the suction pressure, so the liquid inlet control valve 114 is opened to inject sealing liquid 150 into the compression chamber 130 through the intake valve 102. The sealing liquid 150 flows into the upper part of the gas piston 104, so that the compressed medium cannot leak through the sealing component 105 on the gas piston. At the same time, during the exhaust process, part of the sealing liquid 150 is discharged from the exhaust valve 103 along with the gas, and the discharged gas-liquid mixture is separated by the gas-liquid separator 8, and the separated sealing liquid flows into the sealing liquid storage tank 7.

[0043] When the liquid piston 107 approaches the top dead center and the amount of sealing liquid 150 in the compression chamber 130 is too much, the overflow valve assembly 112 is opened to discharge part of the hydraulic oil 151 in the hydraulic chamber 134 into the compressor chamber 2 through the overflow channel 132. When the liquid piston 107 approaches the bottom dead center and the amount of sealing liquid 150 in the compression chamber 130 is too little, the liquid replenishing one-way valve assembly 111 is opened through the liquid replenishing channel 133 to replenish the hydraulic oil 151 into the hydraulic chamber 134.

[0044] A small amount of leaked hydraulic oil 151 and sealing liquid 150 are collected in the balancing chamber 131 and eventually discharged into the waste liquid storage tank 9 through the waste liquid one-way valve 113 .

[0045] The working principle of the second stage compressor 1002 is the same.

[0046] Since the compression and overflow processes during operation will generate heat, causing the temperature of the hydraulic oil in the compressor cavity 2 to gradually increase, the hydraulic oil is extracted through the circulation pump 5 and sent to the heat exchanger 4 for cooling. The cooled hydraulic oil is then sent back to the compressor cavity 2.

[0047] In order to ensure the stability of overflow and replenishment volume, an accumulator 6 filled with nitrogen and with stable pressure is connected to the circulation pump 5, so that the pressure fluctuation can be kept small when the hydraulic oil flows into or out of the compressor cavity 2.

[0048] 2) Example 2

[0049] Figure 2 Schematic diagram of embodiment 2. Compared with embodiment 1, the heat exchanger 4 is placed inside the compressor cavity 2, which further simplifies the structure and improves the heat exchange efficiency.

[0050] Since the accumulator 6 in Example 1 is difficult to maintain stable pressure when the flow rate fluctuates greatly, a gas of a certain pressure is generated by a high-pressure gas source 10, which is adjusted to a suitable pressure by a pressure-regulating valve 11 and then connected to the orifice of the compressor cavity 2. This ensures that a constant pressure in the cavity can be maintained even after changes in temperature, flow rate, and hydraulic oil volume.

[0051] In addition, in Example 2, the number of compressor stages is increased to 5, including a first-stage compressor 1001 , a second-stage compressor 1002 , a third-stage compressor 1003 , a fourth-stage compressor 1004 , and a fifth-stage compressor 1005 . Figure 3 This is a schematic diagram of each stage projected onto the swash plate 1. The exhaust of the first stage compressor 1001 is connected in sequence to the intake of the fifth stage compressor 1005. The intake valve of the first stage compressor 1001 is connected to the outside world, and the exhaust valve of the fifth stage compressor 1005 is connected to the gas-liquid separator 8.

[0052] The preferred specific embodiments of the present invention described above in conjunction with the accompanying drawings are only used to illustrate the implementation methods of the present invention, and are not intended to limit the aforementioned invention objectives and the content and scope of the appended claims. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technology and rights protection of the present invention.

Claims

1. A small displacement flexible piston compressor, characterized in that: It comprises a compressor cavity (2), a swash plate (1) disposed in the compressor cavity (2), a multi-stage compressor connected to the inclined surface end of the swash plate (1), and a main shaft (3) connected to the flat surface end of the swash plate (1); In the multi-stage compressor, each stage of the compressor includes a cylinder body, an intake valve, an exhaust valve, a gas piston, a liquid piston, a piston rod, a ball head connecting rod, a liquid replenishing valve assembly, a relief valve assembly, a waste liquid one-way valve, and a liquid inlet control valve. The gas piston, the liquid piston, and the piston rod in the cylinder body are connected in sequence from top to bottom, and the piston rod is connected to the swash plate through the ball head connecting rod. After the main shaft (3) rotates, the swash plate (1) rotates, and the ball head connecting rod (110) and the second ball head connecting rod (210) connected to the swash plate (1) reciprocate up and down, thereby driving the liquid piston (107) to reciprocate up and down. In the multi-stage compressor, the air inlet valve of the first-stage compressor is connected to the external air intake and the outlet of its own liquid inlet control valve respectively, the air inlet valves of the remaining compressors are connected to the exhaust valve of the previous-stage compressor and the outlet of its own liquid inlet control valve respectively, the exhaust valve of the last-stage compressor is connected to the inlet of the gas-liquid separator (8), the liquid outlet of the gas-liquid separator (8) is connected to the inlet of the sealing liquid storage tank (7), the outlet of the sealing liquid storage tank (7) is connected to the inlet of the liquid inlet control valve of each stage compressor respectively, and the outlet of the waste liquid one-way valve is connected to the waste liquid storage tank (9); The cylinder body and the upper surface of the gas piston form a compression chamber, in which a sealing liquid is contained; the surface of the middle part of the cylinder body and the gas piston forms a balance chamber, which is connected to the inlet of the waste liquid one-way valve through a pipeline; the lower surface of the gas piston and the upper surface of the liquid piston form a hydraulic chamber, in which hydraulic oil is contained; an overflow channel is provided at the lower part of the gas piston, which is communicated with the hydraulic chamber and the interior of the compressor chamber (2) respectively, and an overflow valve assembly is installed on the overflow channel; a fluid replenishment channel is provided on the liquid piston, which is communicated with the interior of the hydraulic chamber and the compressor chamber (2) respectively, and a fluid replenishment valve assembly is installed on the fluid replenishment channel.

2. A small displacement flexible piston compressor according to claim 1, characterized in that: The gas piston is provided with a gas piston upper sealing assembly and a gas piston lower sealing assembly, and the liquid piston is provided with a liquid piston sealing assembly.

3. The small displacement flexible piston compressor according to claim 2, characterized in that: The gas piston upper sealing assembly, the gas piston lower sealing assembly and the liquid piston sealing assembly are all composed of one ring or multiple rings.

4. The small displacement flexible piston compressor according to claim 2, characterized in that: The gas piston upper sealing component, the gas piston lower sealing component and the liquid piston sealing component are made of metal, non-metal, a combination of metal and non-metal or a composite.

5. The small-displacement flexible piston compressor according to any one of claims 1-2, characterized in that: The compressor cavity (2) is provided with a hydraulic oil circulation inlet and outlet, a heat exchanger (4) and a circulation pump (5) are connected between the hydraulic oil circulation inlet and outlet, and an outlet of the circulation pump (5) is connected to an energy storage tank (6).

6. The small-displacement flexible piston compressor according to any one of claims 1-2, characterized in that: A heat exchanger (4) is provided inside the compressor cavity (2), a pressure regulating valve (11) is connected to the side wall of the compressor cavity (2) through an opening, and an inlet of the pressure regulating valve (11) is connected to a high-pressure gas source (10).

7. The small-displacement flexible piston compressor according to any one of claims 1-2, characterized in that: The sealing liquid is an aqueous or oily liquid with low solubility in the compressed gas.

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