A motion control system for a free piston top dead center of an ionic liquid compressor

Abstract

The embodiment of the present application provides a kind of ion liquid compressor free piston top 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, plunger pump oil cylinder, plunger pump plunger, oil supplement one-way valve, oil supplement pump, electromagnetic overflow valve, electromagnetic throttle valve, compressor low-pressure isolation chamber, piston displacement sensor, piston acceleration sensor, piston speed sensor, isolation chamber leakage hole, controller.The scheme of the present application adjusts oil spill pressure by monitoring the displacement and speed of free piston, realizes feedback control to the position of free piston top dead center;By monitoring the acceleration of free piston, adjust the overflow flow, reduce the speed mutation of free piston, smooth liquid level, avoid ion liquid compressor to hit cylinder at higher volumetric efficiency, prolong the service life of compressor, improve the working efficiency of compressor, and reduce additional power consumption.

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 top dead center of the free piston of an ionic liquid compressor. Background Technology

[0002] The ionic liquid compressor is a new type of piston compressor that uses two new technologies, free piston and liquid piston, to replace the traditional crank connecting rod piston. This solves the problems of piston sealing, lubrication and excessive size in previous compressors. Therefore, it is a very promising compressor for hydrogen refueling stations and can also be used in the petrochemical industry for some high-purity gases and toxic gases in the future.

[0003] Ionic liquid compressors use free pistons to reduce the number of moving parts and decrease size, but this also introduces the problem of inconsistent piston movement. Ideally, when the free piston reaches near top dead center, the relief valve opens to release pressure, slowing the piston and preventing it from colliding with the top dead center, causing mechanical damage, and preventing excessive discharge of ionic liquid above the free piston. However, in actual operation, oil pressure and gas pressure are interdependent. If the gas pressure does not reach the set pressure, the oil pressure will not reach the relief pressure, preventing the relief valve from opening, leading to piston collision and excessive discharge of ionic liquid. This not only affects the compressor's lifespan but also necessitates frequent replenishment of ionic liquid into the cylinder, resulting in additional power consumption. Furthermore, if the actual gas pressure exceeds the discharge pressure, the relief valve will open prematurely, reducing the piston stroke and lowering the compressor's volumetric efficiency. Additionally, when the relief valve opens, the speed of the free piston drops abruptly, causing violent fluctuations in the liquid level on the piston, resulting in excessive discharge of ionic liquid into the chamber. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a motion control system for the top dead center of the free piston of an ionic liquid compressor, so as to at least partially solve the above-mentioned problems.

[0005] According to a first aspect of the present invention, a motion control system for the top 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 on the compressor cylinder upper end cover 3, an ionic liquid piston 5 in the inner cavity of the compressor cylinder 4, a free piston 6 at the bottom of the ionic liquid piston 5, a compressor low-pressure isolation chamber 14 at the bottom of the compressor cylinder 4, a compressor oil cylinder 7 at the bottom of the compressor low-pressure isolation chamber 14 and the inner cavity of the compressor oil cylinder 7 communicating with the inner cavity of the compressor cylinder 4, a plunger pump plunger 9 in the inner cavity of a plunger pump oil cylinder 8, and the plunger pump oil cylinder 8, the oil replenishing check valve 10, the electromagnetic overflow valve 12 communicating with the bottom of the compressor oil cylinder 7, an oil replenishing pump 11 connected to the oil replenishing check valve 10, and an electromagnetic throttle valve 13 connected to the electromagnetic overflow valve 12.

[0006] In one implementation, the system includes a piston displacement sensor 15; a piston acceleration sensor 16; and a piston speed sensor 17; wherein the piston displacement sensor 15, the piston acceleration sensor 16, and the piston speed sensor 17 are disposed within the low-pressure isolation chamber 14 of the compressor.

[0007] In another implementation, the system includes an isolation chamber leakage hole 18 and a controller 19. The compressor low-pressure isolation chamber 14 is connected to the atmosphere through the isolation chamber leakage hole 18 to ensure that the pressure inside the compressor low-pressure isolation chamber 14 is always equal to atmospheric pressure. The controller 19 is connected to an electromagnetic overflow valve 12, an electromagnetic throttle valve 13, a piston displacement sensor 15, a piston acceleration sensor 16, and a piston speed sensor 17.

[0008] In another implementation, the piston displacement sensor 15, piston acceleration sensor 16, and piston speed sensor 17 are sensors that operate at normal temperature and pressure.

[0009] In another implementation, the actual dead center position and the velocity at which the free piston 6 reaches the actual dead center are measured by a piston displacement sensor 15 and a piston speed sensor 17 installed in the low-pressure isolation chamber 14. The actual dead center position and the velocity at which the free piston 6 reaches the actual dead center are compared with the design values. When the actual dead center position is less than the design value, the controller 19 transmits a feedback signal to the electromagnetic relief valve 12 to increase the relief pressure of the electromagnetic relief valve 12, thereby delaying the deceleration of the free piston 6. When the actual dead center position of the free piston 6 reaches the design value but the velocity is not zero, the controller 19 transmits a feedback signal to the electromagnetic relief valve 12 to decrease the relief pressure of the electromagnetic relief valve 12, thereby causing the free piston 6 to decelerate earlier.

[0010] In another implementation, the acceleration of the free piston 6 during the overflow process is measured by a piston acceleration sensor 16 installed in the low-pressure isolation chamber 14. The actual acceleration of the free piston 6 during the overflow process measured by the piston acceleration sensor 16 is compared with the design value. When the actual acceleration is greater than the design value, the controller 19 transmits a feedback signal to the electromagnetic throttle valve 13 to reduce the opening of the electromagnetic throttle valve 13, thereby stabilizing the speed of the free piston 6 and reducing the surface fluctuation of the ionic liquid piston 5.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0012] (1) The invention achieves control of the top dead center position of the free piston by adjusting the overflow pressure, thereby avoiding mechanical damage caused by the piston hitting the cylinder at the top 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 design value of the top dead center distance being too large, thus improving the volumetric efficiency of the ionic liquid compressor.

[0013] (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.

[0014] (3) The invention achieves precise control of the top dead center of the free piston through electromagnetic overflow valve and electromagnetic throttle valve, without changing the motor operating conditions, and is simple and easy to implement.

[0015] (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

[0016] 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.

[0017] Figure 1 This is a system structure diagram of the motion control system for the top dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram illustrating the working process of the motion control system for the top dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the working process of the motion control system of the free piston at the top dead center of the ionic liquid compressor according to another embodiment of the present invention.

[0020] List of reference numerals in the attached diagram:

[0021] 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 oil cylinder; 8: Plunger pump oil cylinder; 9: Plunger pump plunger; 10: Oil replenishment check valve; 11: Oil replenishment pump; 12: Electromagnetic relief valve; 13: Electromagnetic throttle valve; 14: Compressor low-pressure isolation chamber; 15: Piston displacement sensor; 16: Piston acceleration sensor; 17: Piston speed sensor; 18: Isolation chamber leakage hole; 19: Controller. Detailed Implementation

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] The specific implementation of the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0027] See Figure 1 This is a system structure diagram of the motion control system for the top dead center of the free piston of an ionic liquid compressor according to an embodiment of the present invention, which mainly includes:

[0028] 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. 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 14. The compressor oil cylinder 7 is located at the bottom of the compressor low-pressure isolation chamber 14 and its inner cavity is connected to the inner cavity of the compressor cylinder 4. The inner cavity of the plunger pump oil cylinder 8 has a plunger pump plunger 9. The plunger pump oil cylinder 8, the oil replenishing check valve 10, the electromagnetic overflow valve 12 and the bottom of the compressor oil cylinder 7 are interconnected. The oil replenishing pump 11 is connected to the oil replenishing check valve 10 and the electromagnetic throttle valve 13 is connected to the electromagnetic overflow valve 12.

[0029] In one implementation, the system includes a piston displacement sensor 15; a piston acceleration sensor 16; and a piston speed sensor 17; wherein the piston displacement sensor 15, the piston acceleration sensor 16, and the piston speed sensor 17 are disposed within the low-pressure isolation chamber 14 of the compressor.

[0030] In another implementation, the system includes an isolation chamber leakage hole 18 and a controller 19. The compressor low-pressure isolation chamber 14 is connected to the atmosphere through the isolation chamber leakage hole 18 to ensure that the pressure inside the compressor low-pressure isolation chamber 14 is always equal to atmospheric pressure. The controller 19 is connected to an electromagnetic overflow valve 12, an electromagnetic throttle valve 13, a piston displacement sensor 15, a piston acceleration sensor 16, and a piston speed sensor 17.

[0031] It should be understood that the compressor's low-pressure isolation chamber 14 is connected to atmospheric pressure through the isolation chamber leakage port 18. Therefore, the pressure inside the low-pressure isolation chamber is always equal to atmospheric pressure, and is far lower than the pressure in the compressor cylinder 4 and compressor oil cylinder 7. The piston displacement sensor 15, piston acceleration sensor 16, and piston speed sensor 17 are located inside the compressor's low-pressure isolation chamber 14 and do not need to withstand high temperature and high pressure. Furthermore, placing the sensors inside the low-pressure isolation chamber prevents gas leakage.

[0032] Furthermore, when the free piston 6 moves to the bottom dead center, even if the part of the piston that extends into the compressor cylinder 7 collides with the cylinder, the part of the free piston 6 in the compressor cylinder 4 will not collide with the low-pressure isolation chamber 14 at the bottom of the compressor cylinder 4. Therefore, the piston displacement sensor 15, piston acceleration sensor 16 and piston speed sensor 17 in the low-pressure isolation chamber 14 will not be damaged, ensuring the safe operation of the piston displacement sensor 15, piston acceleration sensor 16 and piston speed sensor 17.

[0033] In another implementation, the piston displacement sensor 15, piston acceleration sensor 16, and piston speed sensor 17 are sensors that operate at normal temperature and pressure.

[0034] In another implementation, the actual dead center position and the velocity at which the free piston 6 reaches the actual dead center are measured by a piston displacement sensor 15 and a piston speed sensor 17 installed in the low-pressure isolation chamber 14. The actual dead center position and the velocity at which the free piston 6 reaches the actual dead center are compared with the design values. When the actual dead center position is less than the design value, the controller 19 transmits a feedback signal to the electromagnetic relief valve 12 to increase the relief pressure of the electromagnetic relief valve 12, thereby delaying the deceleration of the free piston 6. When the actual dead center position of the free piston 6 reaches the design value but the velocity is not zero, the controller 19 transmits a feedback signal to the electromagnetic relief valve 12 to decrease the relief pressure of the electromagnetic relief valve 12, thereby causing the free piston 6 to decelerate earlier.

[0035] For example, see Figure 2 The piston displacement sensor 15 collects the real-time position of the free piston 6 and compares it with the designed top dead center position to determine whether the free piston 6 has reached the designed top dead center. The piston speed sensor 17 collects the real-time speed of the free piston 6 and compares it with the zero speed to determine whether the free piston 6 has reached the actual dead center. When the speed of the free piston 6 is 0, but the actual dead center position is less than the designed top dead center value, it indicates that the free piston 6 has decelerated excessively and needs to increase the overflow pressure to delay the overflow. When the actual dead center position of the free piston 6 is equal to the design value, but the speed is not equal to 0, it indicates that the free piston 6 has decelerated insufficiently and needs to reduce the overflow pressure to overflow earlier. The piston displacement sensor 15 and the piston speed sensor 17 transmit the collected displacement and speed signals to the controller 19. The controller 19 compares and analyzes the signals and transmits the feedback signals to the electromagnetic relief valve 12 in the form of electrical signals. By changing the electromagnetic force, the controller adjusts the overflow pressure of the electromagnetic relief valve 12, changes the overflow time of the electromagnetic relief valve 12 in the next cycle, and thus adjusts the movement of the free piston 6 to control the actual dead center position of the free piston 6.

[0036] In another implementation, the acceleration of the free piston 6 during the overflow process is measured by a piston acceleration sensor 16 installed in the low-pressure isolation chamber 14. The actual acceleration of the free piston 6 during the overflow process measured by the piston acceleration sensor 16 is compared with the design value. When the actual acceleration is greater than the design value, the controller 19 transmits a feedback signal to the electromagnetic throttle valve 13 to reduce the opening of the electromagnetic throttle valve 13, thereby stabilizing the speed of the free piston 6 and reducing the surface fluctuation of the ionic liquid piston 5.

[0037] For example, see Figure 3The piston acceleration sensor 16 collects the real-time acceleration of the free piston 6 and compares it with the design acceleration. When the acceleration of the free piston 6 is greater than the design value during the overflow process, it indicates that the speed fluctuation of the free piston 6 is too large, which will cause the liquid surface of the liquid piston 5 to fluctuate violently. Therefore, the controller 19 transmits an electrical signal to the electromagnetic throttle valve 13 to change the electromagnetic force to reduce the opening of the electromagnetic throttle valve 13, thereby reducing the overflow flow and making the speed change of the free piston 6 more stable, thus stabilizing the liquid surface of the liquid piston 5.

[0038] This invention uses a controller to output electrical signals to an electromagnetic overflow valve and an electromagnetic throttle valve. By changing the electromagnetic force, the overflow pressure and overflow flow rate are adjusted. This invention can avoid mechanical damage caused by the free piston hitting the cylinder at the top dead center or the actual dead center position deviating significantly from the design value, resulting in reduced volumetric efficiency. It can also reduce the violent oscillation of the liquid surface caused by sudden changes in the speed of the free piston during the overflow process. It is simple to implement, reduces the complexity of the system, and improves the service life of the system.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 top dead center of the free piston of an ionic liquid compressor, characterized in that, include: The compressor cylinder (4) is provided with a compressor cylinder upper end cover (3) on the top of the compressor cylinder (4); The compressor cylinder upper end cover (3) is provided with 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) has a compressor low-pressure isolation chamber (14) at its bottom; The compressor cylinder (7) is located at the bottom of the compressor low-pressure isolation chamber (14) 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 plunger pump cylinder (8) is equipped with a plunger pump plunger (9); The piston pump cylinder (8), the oil replenishment check valve (10), the electromagnetic relief valve (12) are interconnected with the bottom of the compressor cylinder (7); The replenishing pump (11) is connected to the replenishing check valve (10), and the electromagnetic throttle valve (13) is connected to the electromagnetic relief valve (12); Piston displacement sensor (15), piston acceleration sensor (16) and piston speed sensor (17) are installed in the low-pressure isolation chamber (14) of the compressor to measure the actual dead center position of the free piston (6), the speed when it reaches the actual dead center and the acceleration during the overflow process in real time. The controller (19) is connected to the electromagnetic overflow valve (12), the electromagnetic throttle valve (13), the piston displacement sensor (15), the piston acceleration sensor (16), and the piston speed sensor (17). The controller (19) compares the actual stop position and the speed at which the actual stop position is reached with the design value. When the actual stop position is less than the design value, the overflow pressure of the electromagnetic overflow valve (12) is increased to delay the deceleration of the free piston (6). When the actual stop position reaches the preset top stop position but the speed is not zero, the overflow pressure of the electromagnetic overflow valve (12) is decreased to decelerate the free piston (6) earlier. The actual acceleration of the free piston (6) during the overflow process measured by the piston acceleration sensor (16) is compared with the design value. When the actual acceleration is greater than the design value, the opening of the electromagnetic throttle valve (13) is reduced to stabilize the speed of the free piston (6) and reduce the surface fluctuation of the ionic liquid piston (5).

2. The system according to claim 1, characterized in that, include: The compressor low-pressure isolation chamber (14) is connected to the atmosphere through the isolation chamber leakage hole (18) to ensure that the pressure inside the compressor low-pressure isolation chamber (14) is always equal to atmospheric pressure.

3. The system according to claim 1, characterized in that, The piston displacement sensor (15), piston acceleration sensor (16) and piston speed sensor (17) are sensors that operate at normal temperature and pressure.

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