A motion control system for the bottom dead center of a free piston in an ionic liquid compressor

Abstract

The embodiment of the present application provides a kind of ion liquid compressor free piston bottom dead center motion control system.The system includes compressor intake valve, compressor exhaust valve, compressor cylinder upper end cover, compressor cylinder, ion liquid piston, free piston, compressor oil cylinder, overflow oil circuit overflow valve, radial plunger pump plunger, radial plunger pump cylinder, oil supplement pump, check valve, oil supplement circuit electromagnetic overflow valve, oil supplement circuit electromagnetic throttle valve, controller, piston acceleration sensor, piston displacement sensor, piston speed sensor, isolation cavity leakage hole, compressor low-pressure isolation cavity.The scheme of the present application is conducive to keeping the free piston with higher volumetric efficiency while avoiding cylinder collision, improving the working efficiency of ion liquid compressor, reducing the failure rate of ion liquid compressor.

Description

Technical Field

[0001] This invention relates to the field of ionic liquid compressor technology, and more particularly to a motion control system for the bottom dead center of the free piston of an ionic liquid compressor. Background Technology

[0002] The ionic liquid compressor is a new type of compressor for hydrogen refueling stations. It uses a hydraulically driven free piston and an ionic liquid filled between hydrogen and the free piston to replace the crank-connecting rod mechanism in the traditional reciprocating compressor, which greatly reduces the number of moving parts and the size of the whole machine. It plays a very important role in the hydrogen energy industry chain.

[0003] However, controlling the motion of the free piston presents a new challenge. When the free piston reaches bottom dead center, without proper deceleration and control, it will impact, causing significant damage to the compressor over long-term operation. Excessive deceleration of the free piston at bottom dead center reduces the compressor's volumetric efficiency. Simultaneously, the free piston's motion significantly affects the deformation of the liquid surface in the cylinder. If the piston impacts or accelerates excessively, the liquid surface will oscillate violently, causing excessive ionic liquid to be discharged from the cylinder. This requires additional work to replenish the liquid, reducing the overall efficiency of the compressor. Furthermore, when the free piston approaches bottom dead center, the oil replenishment system in the ionic liquid compressor replenishes the hydraulic system, a process that affects the free piston's motion at bottom dead center.

[0004] Therefore, how to control the motion of the free piston has become an urgent technical problem to be solved. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a motion control system for the bottom dead center of the free piston of an ionic liquid compressor, so as to at least partially solve the above-mentioned problems.

[0006] According to a first aspect of the present invention, a motion control system for the bottom dead center of a free piston of an ionic liquid compressor is provided, comprising a compressor cylinder 4, a compressor cylinder upper end cover 3 on the top of the compressor cylinder 4; a compressor inlet valve 1 and a compressor exhaust valve 2 are provided on the compressor cylinder upper end cover 3; an ionic liquid piston 5 is provided in the inner cavity of the compressor cylinder 4, and a free piston 6 is provided at the bottom of the ionic liquid piston 5; a compressor low-pressure isolation chamber 20 is provided at the bottom of the compressor cylinder 4; and a compressor oil cylinder 7 is provided at the bottom of the compressor low-pressure isolation chamber 20, with the inner cavity of the compressor oil cylinder 7 connected to the compressor... The inner cavity of cylinder 4 is connected; the inner cavity of radial piston pump cylinder 10 is equipped with radial piston pump plunger 9; the overflow valve 8, radial piston pump cylinder 10, oil replenishment electromagnetic overflow valve 13, oil replenishment electromagnetic throttle valve 14 and the bottom gap of compressor cylinder 7 are interconnected; the one-way valve 12 is connected to oil replenishment pump 11, oil replenishment electromagnetic overflow valve 13, oil replenishment electromagnetic throttle valve 14; the controller 15 is connected to oil replenishment electromagnetic overflow valve 13, oil replenishment electromagnetic throttle valve 14, piston acceleration sensor 16, piston displacement sensor 17 and piston speed sensor 18 respectively.

[0007] In one implementation, the piston acceleration sensor 16, the piston displacement sensor 17, and the piston speed sensor 18 are disposed within the low-pressure isolation chamber 20 of the compressor.

[0008] In another implementation, the compressor low-pressure isolation chamber 20 is connected to the atmosphere through the isolation chamber leakage hole 19 to ensure that the pressure inside the compressor low-pressure isolation chamber 20 is always equal to atmospheric pressure.

[0009] In another implementation, the actual displacement and speed of the free piston 6 are measured by a piston displacement sensor 17 and a piston speed sensor 18 installed in the low-pressure isolation chamber 20 of the compressor. The actual displacement and speed of the free piston 6 are analyzed and judged against the design values ​​in the controller 15. When the actual bottom dead center of the free piston 6 is less than the design value, the controller 15 sends a feedback signal to the solenoid relief valve 13 of the oil supply circuit, reduces the relief pressure of the solenoid relief valve 13 of the oil supply circuit, and delays the deceleration process of the free piston 6. When the free piston 6 reaches the bottom dead center position of the design value but the speed is not zero, the controller 15 sends a feedback signal to the solenoid relief valve 13 of the oil supply circuit, increases the relief pressure of the solenoid relief valve 13 of the oil supply circuit, and causes the free piston 6 to decelerate earlier.

[0010] In another implementation, the acceleration of the free piston 6 during deceleration is measured by a piston acceleration sensor 16 installed in the low-pressure isolation chamber 20 of the compressor. The acceleration is compared with the design value. When the actual acceleration is greater than the design value, the controller 15 transmits a feedback signal to the oil replenishment circuit solenoid throttle valve 14 to reduce the opening of the oil replenishment circuit solenoid throttle valve 14, so as to stabilize the speed of the free piston 6 and reduce the liquid surface fluctuation of the ionic liquid piston 5.

[0011] In another implementation, the piston acceleration sensor 16, piston displacement sensor 17, and piston speed sensor 18 are sensors that operate at normal temperature and pressure.

[0012] In another implementation, a circular gap is provided at the bottom of the part of the free piston 6 that extends into the compressor cylinder 4. The diameter of the circular gap is smaller than the diameter of the compressor cylinder 4. The piston acceleration sensor 16, the piston displacement sensor 17 and the piston speed sensor 18 are distributed within the range of the circular gap.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The invention achieves control of the bottom dead center position of the free piston by adjusting the overflow pressure, thereby avoiding mechanical damage caused by cylinder collision at the bottom dead center, which is beneficial to increasing the working life of the ionic liquid compressor; it also avoids the compressor volumetric efficiency being too low due to the actual bottom dead center distance being too large, thus improving the volumetric efficiency of the ionic liquid compressor.

[0015] (2) The invention adjusts the overflow flow rate to keep the liquid level of the liquid piston stable during the overflow process, preventing the liquid level from fluctuating violently and causing a large amount of ionic liquid to be discharged from the exhaust valve during exhaust, thus reducing the additional power consumption generated by replenishing ionic liquid.

[0016] (3) The invention achieves precise control of the bottom dead center of the free piston through electromagnetic overflow valve and electromagnetic throttle valve, without the need to adjust the motor, and is simple and easy to implement.

[0017] (4) By placing the sensor in the low-pressure isolation chamber, the invention avoids the requirements for the sensor to withstand high temperature and high pressure, and also avoids the problem of gas leakage. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0019] Figure 1This is a system structure diagram of the motion control system for the bottom dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram illustrating the working process of the motion control system for the bottom dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram illustrating the working process of the motion control system for the bottom dead center of the free piston of an ionic liquid compressor, according to another embodiment of the present invention.

[0022] List of reference numerals in the attached diagram:

[0023] 1: Compressor intake valve; 2: Compressor exhaust valve; 3: Compressor cylinder upper cover; 4: Compressor cylinder; 5: Ionic liquid piston; 6: Free piston; 7: Compressor cylinder; 8: Overflow valve for overflow circuit; 9: Radial piston pump piston; 10: Radial piston pump cylinder; 11: Make-up pump; 12: Check valve; 13: Solenoid overflow valve for make-up circuit; 14: Solenoid throttle valve for make-up circuit; 15: Controller; 16: Piston acceleration sensor; 17: Piston displacement sensor; 18: Piston speed sensor; 19: Isolation chamber leakage hole; 20: Compressor low-pressure isolation chamber. Detailed Implementation

[0024] To provide a clearer understanding of the technical features, objectives, and effects of the embodiments of the present invention, specific implementation methods of the embodiments of the present invention will now be described with reference to the accompanying drawings.

[0025] In this document, “exemplary” means “serving as an example, illustration or description”, and any illustrations or implementations described herein as “exemplary” should not be construed as a more preferred or advantageous technical solution.

[0026] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, some figures show only one or more components with the same structure or function, or only one or more are labeled.

[0027] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art should fall within the protection scope of the present invention.

[0028] The specific implementation of the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] See Figure 1 This is a system structure diagram of the motion control system for the bottom dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention, which mainly includes:

[0030] The compressor cylinder 4 has a compressor cylinder upper cover 3 on its top; the compressor cylinder upper cover 3 has a compressor inlet valve 1 and a compressor exhaust valve 2; the inner cavity of the compressor cylinder 4 has an ionic liquid piston 5, and a free piston 6 is located at the bottom of the ionic liquid piston 5; the bottom of the compressor cylinder 4 has a compressor low-pressure isolation chamber 20; a compressor oil cylinder 7 is located at the bottom of the compressor low-pressure isolation chamber 20, and the inner cavity of the compressor oil cylinder 7 is connected to the inner cavity of the compressor cylinder 4; the inner cavity of the radial plunger pump oil cylinder 10 is provided with... There is a radial piston pump plunger 9; the overflow valve 8, the radial piston pump cylinder 10, the replenishing oil circuit electromagnetic overflow valve 13, the replenishing oil circuit electromagnetic throttle valve 14 are interconnected with the bottom gap of the compressor cylinder 7; the one-way valve 12 is connected to the replenishing oil pump 11, the replenishing oil circuit electromagnetic overflow valve 13, and the replenishing oil circuit electromagnetic throttle valve 14; the controller 15 is connected to the replenishing oil circuit electromagnetic overflow valve 13, the replenishing oil circuit electromagnetic throttle valve 14, the piston acceleration sensor 16, the piston displacement sensor 17, and the piston speed sensor 18 respectively.

[0031] In one implementation, the piston acceleration sensor 16, the piston displacement sensor 17, and the piston speed sensor 18 are disposed within the low-pressure isolation chamber 20 of the compressor.

[0032] In another implementation, the compressor low-pressure isolation chamber 20 is connected to the atmosphere through the isolation chamber leakage hole 19 to ensure that the pressure inside the compressor low-pressure isolation chamber 20 is always equal to atmospheric pressure.

[0033] It should be understood that the compressor low-pressure isolation chamber 20 is connected to the atmosphere through the isolation chamber leakage hole 19, therefore, the pressure is much lower than that of the compressor cylinder 4 and the compressor oil cylinder 7.

[0034] In another implementation, the actual displacement and speed of the free piston 6 are measured by a piston displacement sensor 17 and a piston speed sensor 18 installed in the low-pressure isolation chamber 20 of the compressor. The actual displacement and speed of the free piston 6 are analyzed and judged against the design values ​​in the controller 15. When the actual bottom dead center of the free piston 6 is less than the design value, the controller 15 sends a feedback signal to the solenoid relief valve 13 of the oil supply circuit, reduces the relief pressure of the solenoid relief valve 13 of the oil supply circuit, and delays the deceleration process of the free piston 6. When the free piston 6 reaches the bottom dead center position of the design value but the speed is not zero, the controller 15 sends a feedback signal to the solenoid relief valve 13 of the oil supply circuit, increases the relief pressure of the solenoid relief valve 13 of the oil supply circuit, and causes the free piston 6 to decelerate earlier.

[0035] In another implementation, the acceleration of the free piston 6 during deceleration is measured by a piston acceleration sensor 16 installed in the low-pressure isolation chamber 20 of the compressor. The acceleration is compared with the design value. When the actual acceleration is greater than the design value, the controller 15 transmits a feedback signal to the oil replenishment circuit solenoid throttle valve 14 to reduce the opening of the oil replenishment circuit solenoid throttle valve 14, so as to stabilize the speed of the free piston 6 and reduce the liquid surface fluctuation of the ionic liquid piston 5.

[0036] For example, see Figure 2 Piston displacement sensor 17 and piston speed sensor 18 measure the actual displacement and actual speed of free piston 6. The collected signals are analyzed and processed in controller 15 to determine whether free piston 6 has reached the bottom dead center. The specific determination method is as follows:

[0037] When the speed of the free piston 6 is 0, if the displacement of the free piston 6 is less than the designed bottom dead center, it means that the deceleration is too early and the overflow pressure of the oil replenishment circuit is too high. In the next cycle, the overflow pressure needs to be reduced to delay the deceleration of the free piston 6.

[0038] If the displacement of the free piston 6 is equal to the designed bottom dead center position, but the speed of the free piston 6 is not 0, it means that the deceleration is too late and the overflow pressure of the oil supply circuit is too small. The overflow pressure needs to be increased in the next cycle to make the free piston 6 decelerate earlier.

[0039] The judgment result and deviation value are transmitted to the solenoid relief valve 13 of the oil replenishment circuit in the form of an electrical signal. The electromagnetic force of the solenoid relief valve 13 of the oil replenishment circuit is changed to adjust the overflow pressure. Through continuous correction, the control of the free piston 6 at the bottom dead center position is finally achieved.

[0040] Further, see Figure 3The piston acceleration sensor 16 monitors the speed change of the free piston 6 during deceleration. When the sudden speed change exceeds the design value, the controller 15 transmits a signal to the oil replenishment circuit solenoid throttle valve 14 to change the opening of the oil replenishment circuit solenoid throttle valve 14, thereby regulating the speed change of the free piston 6, ensuring the smooth movement of the free piston 6, and thus maintaining the stability of the liquid level of the ionic liquid piston 5. The movement control of the free piston 6 at the bottom dead center can be achieved by adjusting the two solenoid valves, the oil replenishment circuit solenoid overflow valve 13 and the oil replenishment circuit solenoid throttle valve 14.

[0041] In another implementation, the piston acceleration sensor 16, piston displacement sensor 17, and piston speed sensor 18 are sensors that operate at normal temperature and pressure.

[0042] It should be understood that the piston acceleration sensor 16, piston displacement sensor 17, and piston speed sensor 18 are located within the compressor's low-pressure isolation chamber 20. This chamber is connected to the atmosphere through a leakage port 19, and its internal pressure is much lower than that of the compressor cylinder 4 and compressor oil cylinder 7. Therefore, there is no need for the three sensors placed within to have pressure and temperature resistance requirements; sensors operating at normal temperature and pressure are sufficient. Furthermore, placing the sensors within the compressor's low-pressure isolation chamber 20 avoids drilling holes in the cylinder, eliminating the problem of cylinder leakage.

[0043] In another implementation, a circular gap is provided at the bottom of the part of the free piston 6 that extends into the compressor cylinder 4. The diameter of the circular gap is smaller than the diameter of the compressor cylinder 4. The piston acceleration sensor 16, the piston displacement sensor 17 and the piston speed sensor 18 are distributed within the range of the circular gap.

[0044] It should be understood that the piston displacement sensor 17, piston acceleration sensor 16, and piston speed sensor 18 are distributed within the range of the circular gap. When the free piston collides with the bottom of the cylinder, the three sensors will not be damaged, ensuring the safe operation of the three sensors.

[0045] This invention regulates the replenishment pressure during the replenishment process by monitoring the displacement and velocity of the free piston and altering the electromagnetic force of the electromagnetic overflow valve in the replenishment oil circuit, thus achieving feedback control of the piston's bottom dead center position. Simultaneously, it monitors the acceleration of the free piston and adjusts the replenishment flow rate by changing the opening of the electromagnetic throttle valve in the replenishment oil circuit, reducing sudden changes in the free piston velocity and minimizing fluctuations in the liquid level on the piston. This solution eliminates the need to adjust the replenishment pump and motor, is simple to implement, and helps maintain high volumetric efficiency of the free piston while preventing cylinder collision, thereby improving the operating efficiency of the ionic liquid compressor, reducing its failure rate, and extending its lifespan.

[0046] Specific embodiments of the invention have now been described. Other embodiments are within the scope of the appended claims. In some cases, the actions described in the claims can be performed in a different order and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing can be advantageous.

[0047] It should be noted that all directional indicators (such as up, down, left, right, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0048] In the description of this invention, the terms "first" and "second" are used only for convenience in describing different components or names, and should not be construed as indicating or implying a sequential relationship, relative importance, or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include at least one of that feature.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0050] It should be noted that although specific embodiments of the present invention have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of the present invention. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of the present invention.

[0051] The examples of the embodiments of the present invention are intended to concisely illustrate the technical features of the embodiments of the present invention, so that those skilled in the art can intuitively understand the technical features of the embodiments of the present invention, and are not intended to be an improper limitation of the embodiments of the present invention.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A motion control system for the bottom dead center of the free piston of an ionic liquid compressor, characterized in that, include: The compressor cylinder (4) has a compressor cylinder upper cover (3) on its top. The compressor cylinder upper cover (3) has a compressor inlet valve (1) and a compressor exhaust valve (2). The compressor cylinder (4) has an ionic liquid piston (5) in its inner cavity, and a free piston (6) is located at the bottom of the ionic liquid piston (5). The compressor cylinder (4) is provided with a compressor low-pressure isolation chamber (20) at the bottom; The compressor cylinder (7) is located at the bottom of the compressor low-pressure isolation chamber (20) and the inner cavity of the compressor cylinder (7) is connected to the inner cavity of the compressor cylinder (4); The inner cavity of the radial piston pump cylinder (10) is provided with a radial piston pump plunger (9); The overflow valve (8), radial piston pump cylinder (10), replenishment oil circuit electromagnetic overflow valve (13), replenishment oil circuit electromagnetic throttle valve (14) are interconnected with the bottom gap of the compressor cylinder (7); The check valve (12) is connected to the replenishing pump (11), the replenishing oil circuit solenoid relief valve (13), and the replenishing oil circuit solenoid throttle valve (14); The piston acceleration sensor (16), piston displacement sensor (17) and piston speed sensor (18) are installed in the low-pressure isolation chamber (20) of the compressor; The controller (15) is connected to the oil replenishment circuit electromagnetic overflow valve (13), the oil replenishment circuit electromagnetic throttle valve (14), the piston acceleration sensor (16), the piston displacement sensor (17), and the piston speed sensor (18), respectively. The actual displacement and actual speed of the free piston (6) are measured by the piston displacement sensor (17) and the piston speed sensor (18). The actual displacement and actual speed of the free piston (6) are analyzed and judged in the controller (15) against the design value. When the actual bottom dead center of the free piston (6) is less than the design value, the controller (15) sends a feedback signal to the oil supply circuit electromagnetic overflow valve (13) to reduce the overflow pressure of the oil supply circuit electromagnetic overflow valve (13) and postpone the deceleration process of the free piston (6). When the free piston (6) reaches the bottom dead center position of the design value but the speed is not zero, the controller (15) sends a feedback signal to the oil supply circuit electromagnetic overflow valve (13) to increase the overflow pressure of the oil supply circuit electromagnetic overflow valve (13) and make the free piston (6) decelerate in advance. The acceleration of the free piston (6) during deceleration is measured by a piston acceleration sensor (16) installed in the low-pressure isolation chamber (20) of the compressor. The acceleration is compared with the design value. When the actual acceleration is greater than the design value, the controller (15) transmits the feedback signal to the oil replenishment circuit electromagnetic throttle valve (14) to reduce the opening of the oil replenishment circuit electromagnetic throttle valve (14) so ​​as to stabilize the speed of the free piston (6) and reduce the liquid surface fluctuation of the ionic liquid piston (5).

2. The system according to claim 1, characterized in that, The compressor low-pressure isolation chamber (20) is connected to the atmosphere through the isolation chamber leakage hole (19) to ensure that the pressure inside the compressor low-pressure isolation chamber (20) is always equal to atmospheric pressure.

3. The system according to claim 1, characterized in that, The piston acceleration sensor (16), piston displacement sensor (17) and piston speed sensor (18) are sensors that operate at normal temperature and pressure.

4. The system according to claim 1, characterized in that, The bottom of the free piston (6) extending into the compressor cylinder (4) is provided with a circular gap. The diameter of the circular gap is smaller than the diameter of the compressor cylinder (4). The piston acceleration sensor (16), piston displacement sensor (17) and piston speed sensor (18) are distributed within the range of the circular gap.

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