Mechanical limiting device for hydraulically-driven piston of ionic liquid compressor

Abstract

The invention provides a mechanical limiting device for a hydraulically-driven piston of an ionic liquid compressor, which comprises a cylinder body, a piston, a hydraulic cylinder and a hydraulic driving device, the piston is slidably mounted in the cylinder body, the cylinder body and the hydraulic cylinder are assembled in a butt joint manner, and the hydraulic driving device is used for supplying hydraulic oil to the hydraulic cylinder. Piston stroke limiters are installed on the inner walls of the hydraulic cylinder and the air cylinder body, a cushion valve element is arranged at the lower end of the piston, and the cushion valve element penetrates through a center hole of the piston stroke limiter in a sliding mode and extends into the hydraulic cylinder. Compared with an existing hydrogen compressor, the buffer valve element and the limiting structure are arranged, the pressure can be automatically changed when a hydraulic system works, the piston movement condition is adjusted, extra power consumption is reduced, and the situation that the service life of the compressor is affected due to the fact that the free piston is too low in position or collides with a hydraulic cylinder is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of compressors, and in particular relates to a mechanical limiting device for a liquid-driven piston of an ionic liquid compressor. Background Art

[0002] Hydrogen is known as the clean energy with the greatest development potential in this century because of its abundant sources, huge energy released when it is completely burned, and only water produced after combustion. Ionic liquid compressor is a new type of liquid piston compressor, which uses ionic liquid as liquid piston instead of traditional crank connecting rod piston, thus solving the problems of piston sealing, lubrication and excessive volume in previous compressors. It is a very promising compressor and has become the first choice for hydrogen refueling stations because of its advantages. In the future, it can also be used in some petrochemical industries with high purity gas and toxic gas.

[0003] At present, ionic liquid compressors use liquid-driven free pistons, which reduce the number and volume of moving parts, but also cause the problem of unstable piston movement. Normally, when the free piston moves to the top dead center or near the bottom dead center, the relief valve opens to release pressure, slowing down the piston and preventing the piston from colliding and causing mechanical damage. However, in actual operation, the air pressure often does not reach the set pressure, and the oil pressure cannot reach the overflow pressure, so the overflow valve cannot be opened, causing the piston to hit the cylinder. This not only affects the life of the compressor, but also causes a large amount of ionic liquid to be lost in the cylinder, consuming additional power. At the same time, if the piston position is too high, the actual air pressure will exceed the exhaust pressure. The speed of the free piston will be abnormal during exhaust, causing the liquid piston liquid level to fluctuate violently, causing too much ionic liquid to be discharged from the cavity, reducing the volumetric efficiency of the compressor.

[0004] In response to this phenomenon, researchers are gradually seeking solutions. For example, when we consulted the literature, we saw the patent document "A Multi-cylinder Pump Direct-driven Ionic Liquid Compressor" of Lanzhou Lanshi Petroleum Equipment Engineering Co., Ltd., which has an upper buffer boss at the upper end of the piston and a lower buffer boss at the lower end. The upper and lower ends of the cylinder body are respectively provided with an inner groove of the upper annular boss and a buffer groove at the lower end corresponding to the upper and lower buffer bosses. When the gas enters, after the lower buffer boss enters the buffer groove, the oil in the buffer groove flows out through the oil channel, and the oil in the driving chamber needs to flow into the oil channel through the adjustable lower buffer throttle valve, and the compression cylinder is buffered by the throttling effect. When compressing the gas, after the upper buffer boss enters the inner groove of the annular boss, the gas outside the annular boss continues to be discharged from the gas channel, and the inner groove of the annular boss is filled with ionic liquid. This part of the ionic liquid flows into the compression chamber through the adjustable upper buffer throttle valve, and the compression cylinder is buffered by the throttling effect. Summary of the invention

[0005] Based on the above technical status, the present invention has made improvements on the basis of the existing technology and designed a mechanical limit device for the liquid-driven piston of an ionic liquid compressor, retaining the original structural design of the hydrogen compression space above the piston to avoid pressure fluctuations during hydrogen compression, and designing a buffer valve core structure under the piston to achieve a self-pressure buffering effect when the piston rises to the highest point and falls to the lowest point.

[0006] The technical solution adopted by the present invention is as follows: a mechanical limit device for the liquid-driven piston of an ionic liquid compressor, comprising a cylinder body, a piston, a hydraulic cylinder and a hydraulic drive device, wherein the piston is slidably installed in the cylinder body, the cylinder body and the hydraulic cylinder are docked and assembled, and the hydraulic drive device is used to supply hydraulic oil to the hydraulic cylinder.

[0007] A piston stroke limiter is installed on the inner walls of the hydraulic cylinder and the cylinder body, and a buffer valve core is arranged at the lower end of the piston, and the buffer valve core can slide through the central hole of the piston stroke limiter and extend into the interior of the hydraulic cylinder; a hydraulic cavity is formed between the upper end surface of the piston stroke limiter, the outer peripheral surface of the buffer valve core and the lower end surface of the piston, and the internal space of the hydraulic cylinder below the buffer valve core is connected with the hydraulic cavity via a hydraulic oil channel opened in the buffer valve core, and a throttle valve is arranged in the hydraulic oil channel; a lateral channel connected with the hydraulic oil channel is also opened on the buffer valve core, and a one-way valve is arranged on the lateral channel, and the one-way valve allows the hydraulic oil to flow from the side of the buffer valve core through the one-way valve into the hydraulic oil channel.

[0008] A secondary step hole is provided in the hydraulic cylinder, the inner diameter of the first step hole of the secondary step hole is smaller than the inner diameter of the cylinder body, thereby forming a first step surface between the contact surface of the cylinder body and the hydraulic cylinder, and the second step hole of the secondary step hole is located below the first step hole and has an inner diameter smaller than the inner diameter of the first step hole, thereby forming a second step surface between the first step hole and the second step hole; the shape of the piston stroke limiter is adapted to the secondary step hole and the two step surfaces.

[0009] Furthermore, the piston stroke limiter is an annular cylinder structure with a variable diameter outer wall, and its inner diameter is adapted to the inner diameter of the second-level step hole, and a necking portion is formed near the upper position of the inner diameter. The outer diameter of the piston stroke limiter includes a large diameter portion and a small diameter portion, and the large diameter portion and the small diameter portion are connected by a transition step. The large diameter portion is adapted to the inner diameter of the cylinder body, and the two are relatively fixedly installed; the small diameter portion is adapted to the inner diameter of the first-level step hole, and the small diameter portion of the piston stroke limiter is fixedly installed in the first-level step hole, and the lower end face of the small diameter portion abuts against the second-level step surface; the inner diameter of the necking portion is adapted to the outer diameter of the buffer valve core, so that the buffer valve core can slide along the necking portion and block the hydraulic oil from entering the hydraulic chamber from the hydraulic cylinder along the outer wall of the buffer valve core.

[0010] The buffer valve core is provided with a through hole which runs through both sides of the buffer valve core in a transverse direction, and the upper end of the hydraulic oil passage is connected with the through hole. The through hole is provided at a position corresponding to the hydraulic cavity so as to connect the hydraulic oil passage with the hydraulic cavity. When the piston reciprocates between the highest point and the lowest point, the through hole is always connected with the hydraulic cavity, and the lateral channel where the one-way valve is installed is always located below the constricted portion of the piston stroke limiter.

[0011] Preferably, the buffer valve core is integrally formed at the bottom of the piston; or, the buffer valve core is coaxially fixedly installed at the bottom of the piston with the piston.

[0012] Furthermore, the connection point between the lateral channel where the one-way valve is installed and the hydraulic oil channel is located above the throttle valve.

[0013] Preferably, it also includes an air circuit system, which includes an intake pipe, an exhaust pipe, an intake valve and an exhaust valve, the intake valve and the exhaust valve are installed on a valve seat, the valve seat is placed on the hydrogen compression end of the cylinder body, a pressure plate is fixed above the valve seat, the intake pipe passes through the pressure plate to communicate with the intake valve, and the exhaust pipe passes through the pressure plate to communicate with the exhaust valve.

[0014] Preferably, one or more through channels may be provided and distributed circumferentially; and one or more lateral channels may be provided and distributed circumferentially.

[0015] The beneficial technical effects of the present invention are:

[0016] Compared with the existing hydrogen compressor, the buffer valve core and the limit structure are provided, so that the pressure of the hydraulic system can change automatically when it is working, adjust the movement of the piston, reduce the generation of extra power consumption, and avoid the free piston position being too low or colliding with the hydraulic cylinder to affect the life of the compressor; compared with the reference technology consulted in the background technology, the present invention only relies on the buffer valve core and the limit structure at the bottom of the piston to achieve self-pressure buffering when the piston position is too high or too low, and the hydrogen compression space on the upper end surface of the piston is not affected. The structure is relatively simple and easy to assemble. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a system structure diagram of the mechanical limit device of the liquid-driven piston of the ionic liquid compressor of the present invention;

[0018] Figure 2 It is an enlarged cross-sectional view of a buffer valve core of a mechanical limit device of a liquid-driven piston of an ionic liquid compressor of the present invention;

[0019] Figure 3 This is a schematic diagram of the operation of the buffer valve core when the piston rises to the highest point;

[0020] Figure 4This is a schematic diagram of the operation of the buffer valve core when the piston drops to the lowest point;

[0021] In the figure: 1. hydraulic cylinder, 2. throttle valve, 3. one-way valve, 4. piston stroke limiter, 5. hydraulic chamber, 6. cylinder body, 7. piston, 8. ionic liquid, 9. intake pipe, 10. exhaust pipe, 11. pressure plate, 12. valve seat, 13. exhaust valve, 14. intake valve, 15. through hole, 16. hydraulic oil channel, 17. buffer valve core, 18. hydraulic oil. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0023] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present invention.

[0024] Figure 1 This is a system structure diagram of the mechanical limit device of the liquid-driven piston of the ionic liquid compressor of the present invention, including an air circuit system and a compression component; the air circuit system includes an intake pipe 9, an exhaust pipe 10, an intake valve 14 and an exhaust valve 13, the intake valve 14 and the exhaust valve 13 are installed on a valve seat 12, the valve seat 12 is placed on the hydrogen compression end of the cylinder body 6, a pressure plate 11 is fixedly arranged above the valve seat 12, the intake pipe 9 passes through the pressure plate 11 to communicate with the intake valve 14, and the exhaust pipe 10 passes through the pressure plate 11 to communicate with the exhaust valve 13; the compression component includes a cylinder body 6 and a piston 7 installed inside the cylinder body 6, the upper end surface of the piston 7 has an appropriate amount of ionic liquid 8, and the air circuit system is a conventional hydrogen compressor intake and exhaust structure, which is only briefly described here. The improvement of the present invention lies in the structural redesign of the mechanical limit device and the hydraulic drive device, see Figure 1A hydraulic cylinder 1 is connected below the cylinder body 6, and a piston 7 is accommodated in the cylinder body 6 and driven to reciprocate. A two-level step hole is provided in the hydraulic cylinder 1, and the inner diameter of the first-level step hole of the two-level step hole is smaller than the inner diameter of the cylinder body 6, thereby forming a first-level step surface between the contact surface of the cylinder body 6 and the hydraulic cylinder 1, and the second-level step hole of the two-level step hole is located below the first-level step hole and has an inner diameter smaller than the inner diameter of the first-level step hole, thereby forming a second-level step surface between the first-level step hole and the second-level step hole. A piston stroke limiter 4 is installed between the cylinder body 6 and the hydraulic cylinder 1. The piston stroke limiter 4 is an annular tube structure with a variable diameter of the outer peripheral wall, and its inner diameter is the same as or similar to the inner diameter of the second-level step hole. A constricted portion is formed near the upper position of the inner diameter. The outer diameter of the piston stroke limiter 4 includes a large diameter portion and a small diameter portion, and the large diameter portion and the small diameter portion are connected by a transition step. The large diameter portion is adapted to the inner diameter of the cylinder body 6, and the two are interference fit or threaded. The large diameter portion of the piston stroke limiter 4 is installed inside the cylinder body 6, and the small diameter portion is adapted to the inner diameter of the first-level step hole. The small diameter portion of the piston stroke limiter 4 is fixedly installed in the first-level step hole, and the lower end surface of the small diameter portion abuts against the second-level step surface.

[0025] The lower end of the piston 7 is integrally or separately fixedly connected to a buffer valve core 17, and the outer diameter of the buffer valve core 17 is adapted to the inner diameter of the constricted portion of the piston stroke limiter 4, so that the buffer valve core 17 passes through the constricted portion and extends into the hydraulic cylinder 1; a hydraulic chamber 5 is formed between the piston stroke limiter 4 and the piston 7.

[0026] See also Figure 2 , is an enlarged cross-sectional view of the buffer valve core of the mechanical limit device of the hydraulic piston of the ionic liquid compressor of the present invention. The buffer valve core 17 is provided with a hydraulic oil passage 16 extending in the axial direction and a through hole 15 extending in the transverse direction through both sides of the buffer valve core. The pipe through hole 15 is provided at a position corresponding to the hydraulic chamber 5. The lower end of the hydraulic oil passage 16 is connected to the inside of the hydraulic cylinder 1 through the throttle valve 2, and the upper end of the hydraulic oil passage 16 is connected to the through hole 15, thereby connecting the internal space of the hydraulic cylinder 1 and the hydraulic chamber 5. The buffer valve core 17 is also provided with a lateral channel connected to the hydraulic oil passage 16, and a one-way valve 3 is provided on the lateral channel. The one-way valve 3 allows the hydraulic oil to flow from the side of the buffer valve core through the one-way valve 3 to the hydraulic oil passage 16.

[0027] The opening position of the through hole 15 can be kept in contact with the hydraulic chamber 5 when the piston 7 reciprocates between the highest point and the lowest point; the opening position of the lateral channel of the one-way valve 3 can be kept in contact with the hydraulic chamber 5 when the piston 7 reciprocates between the highest point and the lowest point. The shrinkage portion blocks the hydraulic oil 18 from flowing from the hydraulic cylinder 1 along the annular gap between the buffer valve core 17 and the piston stroke limiter 4 to the hydraulic chamber 5.

[0028] Figure 1 and Figure 2 The structural design of the mechanical limit device and the hydraulic drive device of the present invention is shown in detail below. Figure 3 and Figure 4 The working principle of the mechanical limit device of the liquid-driven piston of the ionic liquid compressor of the present invention is explained as follows:

[0029] When working, it is divided into an intake process and a compression process. The gas enters the cylinder through the intake pipe 9 and the intake valve 14. The hydraulic pump in the hydraulic drive device moves, driving the hydraulic oil 18 to enter the hydraulic cylinder 1 to generate power, pushing the piston 7 up to compress the gas; when the pressure in the cylinder reaches the exhaust pressure, the exhaust valve 13 opens, and the gas is discharged through the exhaust pipe 10. During the compression process, when the piston 7 rises to the designed height, the liquid piston position reaches the top of the cylinder, the pressure on the top of the piston 7 increases sharply, and the throttle valve 2 at the bottom of the buffer valve core 17 reduces the flow rate due to the pressure difference. The hydraulic oil flows through the one-way valve 3 on the lower surface of the buffer valve core 17 through the hydraulic oil channel into the hydraulic chamber 5 and gathers at the bottom of the hydraulic chamber 5, causing the liquid pressure in the hydraulic cylinder 1 to drop sharply, preventing the piston position from continuing to rise.

[0030] During the intake process, when the position of the piston 7 drops, the through hole 15 on the upper part of the buffer valve core 17 gradually drops below the hydraulic oil level in the hydraulic chamber 5, and the hydraulic oil flows along the through hole 15 into the hydraulic oil channel 16 and re-enters the hydraulic cylinder 1 through the throttle valve 2, so that the pressure in the hydraulic cylinder 1 increases, thereby timely preventing the piston position from continuing to drop.

[0031] By means of the mechanical limit device of the hydraulically driven piston of the ionic liquid compressor of the present invention, the power provided by the hydraulic oil in the hydraulic cylinder to the piston can be adjusted spontaneously, so as to avoid collision with other parts of the compressor due to the free piston moving too high or too low, thereby affecting the life of the compressor, and at the same time prevent the loss of ionic liquid in the cylinder, thereby improving economic benefits.

[0032] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A mechanical limit device for a hydraulically driven piston of an ionic liquid compressor, comprising a cylinder body, a piston, a hydraulic cylinder and a hydraulic drive device, wherein the piston is slidably mounted in the cylinder body, the cylinder body and the hydraulic cylinder are butt-jointed and assembled, and the hydraulic drive device is used to supply hydraulic oil to the hydraulic cylinder; characterized in that: A piston stroke limiter is installed on the inner walls of the hydraulic cylinder and the cylinder body, and a buffer valve core is arranged at the lower end of the piston, and the buffer valve core can slide through the central hole of the piston stroke limiter and extend into the interior of the hydraulic cylinder; a hydraulic cavity is formed between the upper end surface of the piston stroke limiter, the outer peripheral surface of the buffer valve core and the lower end surface of the piston, and the internal space of the hydraulic cylinder below the buffer valve core is connected with the hydraulic cavity via a hydraulic oil channel opened in the buffer valve core, and a throttle valve is arranged in the hydraulic oil channel; a lateral channel connected with the hydraulic oil channel is also opened on the buffer valve core, and a one-way valve is arranged on the lateral channel, and the one-way valve allows the hydraulic oil to flow from the side of the buffer valve core through the one-way valve into the hydraulic oil channel.

2. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 1 is further characterized in that: A two-stage step hole is provided in the hydraulic cylinder, the inner diameter of the first stage step hole of the two-stage step hole is smaller than the inner diameter of the cylinder body, so that a first stage step surface is formed between the contact surface of the cylinder body and the hydraulic cylinder, and the second stage step hole of the two-stage step hole is located below the first stage step hole and has an inner diameter smaller than the inner diameter of the first stage step hole, so that a second stage step surface is formed between the first stage step hole and the second stage step hole; The shape of the piston stroke limiter is compatible with the secondary step hole and the two-step step surfaces.

3. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 2 is further characterized in that: The piston stroke limiter is a ring-shaped cylinder structure with a variable diameter of the outer peripheral wall, and its inner diameter is adapted to the inner diameter of the second-stage step hole, and a constriction portion is formed near the upper position of the inner diameter. The outer diameter of the piston stroke limiter includes a large diameter portion and a small diameter portion, and the large diameter portion and the small diameter portion are connected by a transition step. The large diameter portion is adapted to the inner diameter of the cylinder body, and the two are relatively fixedly installed; the small diameter portion is adapted to the inner diameter of the first-stage step hole, and the small diameter portion of the piston stroke limiter is fixedly installed in the first-stage step hole, and the lower end surface of the small diameter portion abuts against the second-stage step surface; The inner diameter of the constricted portion is matched with the outer diameter of the buffer valve core, so that the buffer valve core can slide along the constricted portion and prevent hydraulic oil from entering the hydraulic cavity from the hydraulic cylinder along the outer peripheral wall of the buffer valve core.

4. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 3 is further characterized in that: The buffer valve core is provided with a through hole which transversely passes through both sides of the buffer valve core, the upper end of the hydraulic oil channel is connected with the through hole, and the through hole is provided at a position corresponding to the hydraulic cavity to connect the hydraulic oil channel with the hydraulic cavity.

5. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 4 is further characterized in that: When the piston reciprocates between the highest point and the lowest point, the through hole is always connected to the hydraulic chamber, and the lateral channel where the one-way valve is installed is always located below the necking portion of the piston stroke limiter.

6. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 1 is further characterized in that: The buffer valve core is integrally formed at the bottom of the piston; or, the buffer valve core is coaxially fixedly installed at the bottom of the piston with the piston.

7. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 1 is further characterized in that: The connection point between the lateral channel where the one-way valve is installed and the hydraulic oil channel is located above the throttle valve.

8. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 1 is further characterized in that: It also includes an air circuit system, which includes an intake pipe, an exhaust pipe, an intake valve and an exhaust valve. The intake valve and the exhaust valve are installed on a valve seat. The valve seat is placed at the hydrogen compression end of the cylinder body. A pressure plate is fixed above the valve seat. The intake pipe passes through the pressure plate to communicate with the intake valve, and the exhaust pipe passes through the pressure plate to communicate with the exhaust valve.

9. The mechanical limit device for the liquid-driven piston of the ionic liquid compressor according to claim 4, further characterized in that: The through-channel may be provided with one or more circumferentially distributed channels; the lateral channel may be provided with one or more circumferentially distributed channels.

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