Dual-piston gas compressor

Abstract

The utility model relates to a double-piston gas compressor which comprises a cylinder body, a cylinder cover and an exhaust chamber which are sequentially arranged from bottom to top, a compression chamber is arranged in the cylinder body, a piston is arranged in the compression chamber, the cylinder cover is provided with an exhaust cavity located at the top of the compression chamber, and the piston comprises a main piston matched with the compression chamber to work. The upper end of the main piston is provided with an auxiliary piston which protrudes upwards and can stretch into the exhaust cavity when the piston moves to the upper dead center, and the auxiliary piston is of a smooth curved surface structure. The double-piston gas compressor is novel in structure and reasonable in design, and the auxiliary piston is optimized and designed into a smooth curved surface structure, so that on one hand, the motion resistance of the piston is reduced, and the efficiency of the compressor is improved; and on the other hand, temperature concentration and stress concentration at the top of the piston under high-temperature and high-pressure conditions are relieved, and the failure risk of the auxiliary piston is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of gas compressor especially a double piston gas compressor. BACKGROUND

[0002] The compressor is the important component equipment of refrigeration, heat pump system, and the performance of the compressor directly influences the efficiency and power consumption of the system. The piston compressor is the typical reciprocating volume compressor, and due to its structural characteristics, the piston compressor has irreplaceable role in specific application scene, especially in its high pressure, heavy load gas compression scene.

[0003] In the exhaust structure of the piston compressor, there is a gap between the exhaust valve and the top surface of the cylinder, and the exhaust cavity formed by the exhaust valve and the bottom surface of the cylinder cover is a component part of the gas compression chamber. The exhaust cavity volume of the conventional piston compressor does not change, which reduces the compression ratio of the compressor. Since the exhaust cavity volume is small, the compression ratio loss of the low pressure and medium pressure compressor is small, but for the high pressure and heavy load compressor, the exhaust cavity that cannot be compressed will cause great efficiency loss.

[0004] A common method to reduce the compression loss caused by the exhaust cavity is to set a flat top protruding part structure on the top of the piston, and when the piston runs to the top dead center, the top protruding part of the piston enters the exhaust cavity, thereby reducing the compression efficiency loss. However, since the medium exhibits high density and low viscosity and other properties that are completely different from conventional fluids after exceeding its critical temperature and pressure, supercritical carbon dioxide and other supercritical media have been used in advanced refrigeration and heat pump systems. At this time, the compressor must be able to withstand extremely high working temperature and pressure to ensure stable operation. Under the conditions of high temperature, high pressure and heavy load, the piston surface of the compressor is subjected to harsh operating conditions, and the aerodynamic resistance, temperature distribution and stress distribution of the piston under high pressure and high temperature gas will directly affect the energy consumption and service life of the compressor. SUMMARY

[0005] Therefore, the utility model aims at providing a double piston gas compressor, reducing the piston movement resistance, improving the compressor efficiency and prolonging the piston service life.

[0006] The utility model adopts the following scheme to realize: a double piston gas compressor, comprising a cylinder body, a cylinder cover and an exhaust chamber arranged in sequence from bottom to top, a compression chamber is arranged in the cylinder body, a piston is arranged in the compression chamber, an exhaust cavity is arranged on the cylinder cover and located at the top of the compression chamber, the piston comprises a main piston cooperating with the compression chamber, an auxiliary piston protruding upward is arranged on the upper end of the main piston and can extend into the exhaust cavity when the piston runs to the top dead center, and the auxiliary piston is a smooth curved surface structure.

[0007] Further, the upper end of the auxiliary piston is provided with a curved top bulging upward, and the lower part of the auxiliary piston is provided with a necking part on the periphery, and the curved top and the necking part are connected by an arc-shaped drum part.

[0008] Further, the vertical section profile of the auxiliary piston is a curve, including a top surface windward section of the top part, a side surface necking section on both sides, and a side surface transition section on both sides, which are sequentially connected from top to bottom.

[0009] Further, the upper end of the vertical section profile of the main piston is provided with a top surface gentle section on both sides of the vertical section profile of the auxiliary piston, and the inner end point of the top surface gentle section is connected with the lower end point of the side surface transition section, and the outer end point of the top surface gentle section is connected with the upper edge line of the side surface of the main piston.

[0010] Further, the compression chamber is detachably provided with a cylinder sleeve, the main piston of the piston is in sliding fit with the cylinder sleeve, the periphery of the main piston is provided with an annular groove, and a sealing ring is arranged in the annular groove.

[0011] Further, the outer periphery of the upper end of the cylinder sleeve is provided with a flange part, and the periphery of the upper end of the compression chamber is provided with an annular mounting groove matched with the flange part.

[0012] Further, the flange part is connected in the annular mounting groove through screws.

[0013] Further, a connecting rod is arranged below the piston, and the upper end of the connecting rod is hingedly connected with the main piston of the piston through a piston pin.

[0014] Further, the exhaust chamber is provided with an exhaust passage in communication with an exhaust cavity, and the exhaust cavity is provided with an exhaust valve at the upper opening.

[0015] Further, the cylinder head is provided with an intake passage in communication with the compression chamber, and the compression chamber is provided with an intake valve at the top part of the port of the intake passage.

[0016] Compared with the prior art, the double-piston gas compressor has the following beneficial effects: the double-piston gas compressor has a novel structure and reasonable design, the auxiliary piston is designed as a smooth curved surface structure, which reduces the movement resistance of the piston, improves the efficiency of the compressor, and reduces the temperature concentration and stress concentration of the top of the piston under high-temperature and high-pressure conditions, and reduces the failure risk of the auxiliary piston.

[0017] In order to make the purpose, technical scheme and advantages of the utility model more clear, specific examples and related drawings will be used to make a further detailed description of the utility model. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a partial structure schematic view of the gas compressor of the utility model.

[0019] Figure 2 is a variation of the compression chamber when the piston of the embodiment of the present application operates to the top dead center;

[0020] Figure 3 is a direction and airflow distribution diagram of the internal exhaust of the compressor after the exhaust valve of the embodiment of the present application is opened;

[0021] Figure 4 is a three-dimensional view of the attached piston located at the center of the embodiment of the present application;

[0022] Figure 5 is a contour curve diagram of the attached piston located at the center of the embodiment of the present application;

[0023] Figure 6 is a contour curve diagram of the attached piston deviated from the center of the embodiment of the present application;

[0024] Figure 7 is a contour curve diagram of the attached piston with a non-circular cross section of the embodiment of the present application; DETAILED DESCRIPTION

[0025] It should be noted that the following detailed description is merely exemplary in nature and is intended to provide further description of the application. 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 application belongs.

[0026] It is to be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments consistent with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof, but do not preclude the presence or addition of one or more other features, steps, operations, devices, components and / or combinations thereof.

[0027] As Figures 1-7As shown, a dual-piston gas compressor includes a cylinder body 25, a cylinder head 26, and an exhaust chamber 27 arranged sequentially from bottom to top. The cylinder body 25 is the main structure of the cylinder. The compressor housing, motor, crankshaft, and other components are not shown in the figure; these components are not modified and utilize existing technology, and will not be described in detail here. A compression chamber 31 is provided inside the cylinder body, and a piston 10 is located within the compression chamber 31. An exhaust cavity 34 is located at the top of the compression chamber 31 on the cylinder head 26. The piston 10 includes a main piston 21 that works in conjunction with the compression chamber. An auxiliary piston 11, which protrudes upwards from the upper end of the main piston and extends into the exhaust cavity when the piston reaches top dead center, has a smooth curved surface structure. The centerline of the auxiliary piston may be aligned with or deviate from the centerline of the main piston. When the piston reaches top dead center, the auxiliary piston extends into the exhaust cavity formed by the bottom surface of the cylinder head and the exhaust valve, thereby improving the compressor's compression efficiency. The attached piston 11 is a complete smooth curved surface. On the one hand, the smooth windward surface structure reduces the piston movement resistance and improves the compressor efficiency; on the other hand, the smooth curved surface reduces the temperature concentration and stress concentration at the top of the piston under high temperature and high pressure conditions, thus reducing the failure risk of the attached piston 11.

[0028] The cross-sectional shape (i.e., the cross-section) of the piston in the direction orthogonal to its centerline can be circular (e.g.) Figure 4 (as shown) or other closed figures, such as ellipses or parallelograms (e.g. Figure 7 (As shown). The crank-connecting rod-piston mechanism and intake-exhaust mechanism of a piston compressor are often asymmetrical structures. When facing the stringent requirements of structural stress and exhaust airflow, the curved surface of the attached piston 11 can be designed as a closed surface with a non-circular cross-section. The aerodynamic force generated by the curved surface of the attached piston 11 during movement can improve the dynamic characteristics of the piston and reduce compressor vibration. The curved surface of the attached piston 11 can also improve the flow state of the exhaust airflow.

[0029] In this embodiment, the upper end of the auxiliary piston 11 is provided with an upwardly raised curved top, and the lower periphery of the auxiliary piston has a constricted neck. The curved top and the constricted neck are connected by an arc-shaped drum. The auxiliary piston composed of continuous curved surfaces helps to reduce the aerodynamic drag of piston movement, and can also alleviate the stress field and temperature field concentration at the piston top, thereby improving piston life.

[0030] In this embodiment, the vertical cross-sectional profile of the attached piston 11 is a curve, including a top windward section 14, side necking sections 15, and side transition sections 16. The top windward section 14, side necking sections 15, and side transition sections 16 are connected sequentially from top to bottom; that is, the upper end point of the side transition section 16 is connected to the lower end point of the side necking section 15, and the lower ends of the top windward section 14 are connected to the upper ends of the side necking sections 15. The curves of the attached piston 11 are interconnected to form a complete curved profile.

[0031] The cross-sectional area of the top surface windward section 14 in the direction orthogonal to the top surface center line 13 decreases to a value close to zero in the direction of the top surface center line; the cross-sectional area of the side surface necking section 15 in the direction orthogonal to the top surface center line 13 decreases slowly in the direction of the top surface center line, forming a curved surface with a small cross-sectional area and a smooth transition in the direction of the top surface center line; the cross-sectional area of the side surface transition section 16 in the direction orthogonal to the top surface center line decreases from the cross-sectional area at the upper end of the top surface gentle section to the cross-sectional area at the lower end of the side surface necking section.

[0032] The top surface windward section 14 is located at the uppermost part of the auxiliary piston 11, and the curved surface formed by the top surface windward section 14 directly faces the gas during the compression process. As the compression process proceeds, the pressure, temperature, and density of the gas increase, and the gas resistance faced by the curved surface of the top surface windward section 14 increases sharply. In order to reduce the resistance of the piston in operation, the cross-sectional area of the auxiliary piston 11 corresponding to the part of the top surface windward section 14 (i.e., the top of the curved surface) decreases to a value close to zero in the direction of the cross-sectional height, so as to prevent the accumulation of high-pressure and high-temperature gas above the top surface windward section 14 and reduce the aerodynamic resistance when the piston moves. Since the accumulation of high-pressure and high-temperature gas above the top surface windward section 14 is prevented, the maximum temperature of the auxiliary piston 11 is also reduced. The side surface necking section 15 is a smooth transition curve, and the curved surface formed at this position enables the auxiliary piston 11 to extend into the exhaust cavity, so that the gas in the exhaust cavity participates in the compression, thereby reducing the loss of compression ratio. The lower edge of the curved surface of the top surface windward section 14 is smoothly connected to the upper edge of the curved surface of the side surface necking section 15, so that the high-pressure gas flow smoothly passes through, reducing the gas resistance when the piston moves. The top surface gentle section 17 is connected to the upper edge of the side surface of the main piston 21, so that the auxiliary piston 11 becomes the upper end surface of the main piston 21. The top surface gentle section 17 is a curved surface coinciding with or gently rising from the top surface horizontal plane 12, and the top surface gentle section 17 is the main compression surface of the main piston 21. The side surface transition section 16 is a transition surface between the side surface necking section 15 and the top surface gentle section 17. The upper edge of the curved surface of the side surface transition section 16 is connected to the lower edge of the curved surface of the side surface necking section 15, and the lower edge of the curved surface of the side surface transition section 16 is connected to the inner edge of the curved surface of the top surface gentle section. The side surface transition section 16 prevents the accumulation of high-temperature and high-pressure gas between the side surface necking section 15 and the top surface gentle section 17, further reduces the resistance of the piston in operation, and reduces the concentration of the temperature field and the stress field.

[0033] In the present embodiment, the top surface windward section 14 is in the shape of a semi-elliptical arc, the side surface necking section 15 is in the shape of an S, and the side surface transition section 16 is in the shape of a circular arc.

[0034] In the embodiment, the vertical section profile of the main piston 21 has a top flat section 17 on both sides of the vertical section profile of the auxiliary piston, the inner end point of the top flat section 17 is connected with the lower end point of the side transition section, and the outer end point of the top flat section 17 is connected with the upper edge of the side of the main piston 21.

[0035] In the embodiment, the top flat section 17 can be coincident with the top horizontal plane 12 (the plane surrounded by the upper edge of the side of the main piston 21 is defined as the top horizontal plane 12), or can be a flat curve higher than the top horizontal plane 12.

[0036] In the embodiment, the compression chamber 31 is detachably sleeved with a cylinder sleeve 24, the main piston 21 of the piston 10 is in sliding fit with the cylinder sleeve 24, the peripheral portion of the main piston is provided with an annular groove, and a sealing ring is arranged in the annular groove.

[0037] In the embodiment, the outer peripheral side of the upper end of the cylinder sleeve 24 is provided with a flange portion, the peripheral side of the upper end of the compression chamber is provided with an annular mounting groove matched with the flange portion, and the flange portion is connected in the annular mounting groove through screws.

[0038] In the embodiment, the piston is provided below with a connecting rod 23, the upper end of the connecting rod 23 is hingedly connected with the main piston 21 of the piston 10 through a piston pin 22.

[0039] In the embodiment, the exhaust chamber 24 is provided with an exhaust passage 33 communicated with an exhaust cavity 34, and the exhaust cavity 34 is provided with an exhaust valve 26 at the upper opening.

[0040] In the embodiment, the cylinder head 26 is provided with an intake passage 32 communicated with the compression chamber 31, and the compression chamber is provided with an intake valve 28 at the port of the intake passage 32.

[0041] The cylinder block 25, the cylinder sleeve 24, the main piston 21 and the cylinder head 26 jointly form a cylinder, the main piston 21 reciprocates on the straight line segment between the top dead center and the bottom dead center under the driving of the connecting rod 23, and uninterruptedly completes the intake-compression-exhaust process to realize the compression of working gas. When the main piston 21 is at the top dead center, the volume of the compression chamber 31 is the smallest, and when the main piston 21 is at the bottom dead center, the volume of the compression chamber 31 is the largest.

[0042] The intake-compression-exhaust process of the cylinder is as follows: firstly, after the exhaust valve 29 is closed when the main piston 21 is at the top dead center position, the intake valve 28 is opened, then the volume of the compression chamber 31 gradually increases during the movement of the main piston 21 from the top dead center to the bottom dead center, working gas enters the compression chamber 31 from the intake passage 32, and the intake process is completed when the main piston 21 moves to the bottom dead center position and the intake valve is closed. Secondly, the main piston 21 moves from the bottom dead center to the top dead center, the volume of the compression chamber 31 decreases, the compression process is completed, and the working gas in the compression chamber 31 is compressed, such asFigure 2 As shown. After reaching a certain pressure, the exhaust valve 29 opens, and the compressed working gas is discharged from various parts of the compression chamber into the exhaust duct 33, as shown. Figure 3 As shown. Then, the exhaust valve 29 closes, completing the exhaust process.

[0043] like Figure 1 As shown, the exhaust cavity 34 is located on the cylinder head 26. In traditional compressors, since the auxiliary piston 11 is flat, the internal volume of the exhaust cavity 34 does not change during compression and exhaust, which reduces the compression ratio of the cylinder to some extent. For high-pressure, heavy-duty compressors, the compression ratio loss caused by the exhaust cavity 34 will significantly affect the compressor performance. Therefore, it is necessary to change the internal volume of the exhaust cavity 34 during compression. The conventional method to change the internal volume of the exhaust cavity 34 is to provide a protrusion with a flat top surface on the auxiliary piston 11. During compression, the protrusion enters the exhaust cavity 34, thereby reducing the influence of the exhaust cavity 34 on the compression ratio. However, the geometric discontinuities of the traditional flat protrusion are prone to cause airflow accumulation, resulting in high resistance, temperature concentration, and stress concentration. These problems will greatly affect the efficiency and lifespan of the compressor when compressing high-temperature, high-pressure gases. Therefore, this invention proposes a method that does not provide a protrusion but instead replaces the auxiliary piston 11 with a continuous curved surface. The auxiliary piston 11 is extended into the exhaust cavity 34 by the curved surface formed by the top necking section 15. Meanwhile, the top cross-sectional area of ​​the top air-facing section 14 is a near-zero minimum, thus preventing the accumulation of high-pressure, high-temperature airflow above the top air-facing section 14 during the high-speed upward movement of the main piston 21. This reduces piston movement resistance, minimizes stress and temperature concentration, and ultimately improves compressor efficiency and lifespan. Furthermore, by optimizing the curved surface design, the aerodynamic force generated by the auxiliary piston 11 during the movement of the main piston 21 can be used to stabilize the movement of the main piston 21, thereby reducing vibration during compressor operation.

[0044] Unless otherwise stated, if any of the technical solutions disclosed in this utility model discloses a numerical range, then the disclosed numerical range is a preferred numerical range. Any person skilled in the art should understand that the preferred numerical range is merely one among many feasible numerical values ​​that has a more obvious or representative technical effect. Because there are many numerical values, it is impossible to list them all. Therefore, this utility model discloses only some numerical values ​​to illustrate the technical solutions of this utility model. Furthermore, the numerical values ​​listed above should not constitute a limitation on the scope of protection of this utility model.

[0045] If the utility model discloses or involves mutually fixed connecting parts or structural members, then, except for another declaration, fixed connection can be understood as: detachably fixed connection (for example, using bolt or screw connection), and also can be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by integral structure (for example, integrally formed by using casting process) (except for obviously unable to adopt integral forming process).

[0046] In addition, the terms used to represent the positional relationship or shape in any of the technical solutions of the utility model disclosed above include the states or shapes similar, analogous or close to them, except for another declaration.

[0047] Any component provided by the utility model can be assembled from a plurality of separate components, or can be a separate component manufactured by integral forming process.

[0048] The above is only a preferred embodiment of the utility model, and is not intended to limit the utility model in other forms, and any skilled person in the art can modify or change the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiments without departing from the technical solution of the utility model, according to the technical essence of the utility model, still belongs to the protection scope of the technical solution of the utility model.

Claims

1. A dual piston gas compressor characterized by: The application relates to a cylinder-piston engine, which comprises a cylinder body, a cylinder cover and an exhaust chamber arranged in sequence from bottom to top, wherein a compression chamber is arranged in the cylinder body, a piston is arranged in the compression chamber, an exhaust cavity is arranged on the top of the compression chamber, the piston comprises a main piston matched with the compression chamber, an auxiliary piston protruding upward is arranged on the top of the main piston and can extend into the exhaust cavity when the piston runs to the top dead center, and the auxiliary piston is a smooth curved surface structure.

2. The dual piston gas compressor of claim 1, wherein: The top of the auxiliary piston is provided with a curved top protruding upward, the lower part of the auxiliary piston is provided with a necking part, and the curved top and the necking part are connected through an arc-shaped drum part.

3. Double piston gas compressor according to claim 1 or 2, characterized in that: The vertical section profile of the auxiliary piston is a curve, which comprises a top surface windward section of the top, two side surface necking sections and two side surface transition sections, and the top surface windward section, the side surface necking sections and the side surface transition sections are connected in sequence from top to bottom.

4. The dual piston gas compressor of claim 3, wherein: The vertical section profile of the main piston is provided with a top surface gentle section on the top of the vertical section profile of the auxiliary piston, an inner end point of the top surface gentle section is connected with a lower end point of the side surface transition section, and an outer end point of the top surface gentle section is connected with an upper edge line of the side surface of the main piston.

5. The dual piston gas compressor of claim 1, wherein: A cylinder sleeve is detachably arranged in the compression chamber, the main piston of the piston is slidably matched with the cylinder sleeve, an annular groove is arranged on the peripheral part of the main piston, and a sealing ring is arranged in the annular groove.

6. The dual piston gas compressor of claim 5, wherein: A flange part is arranged on the outer periphery of the upper end of the cylinder sleeve, and an annular mounting groove matched with the flange part is arranged on the peripheral side of the upper end of the compression chamber.

7. The dual piston gas compressor of claim 6, wherein: The flange part is connected in the annular mounting groove through screws.

8. The dual piston gas compressor of claim 1, wherein: A connecting rod is arranged below the piston, and the upper end of the connecting rod is hingedly connected with the main piston of the piston through a piston pin.

9. The dual piston gas compressor of claim 1, wherein: The exhaust chamber is provided with an exhaust passage communicated with the exhaust cavity, and an exhaust valve is arranged on the opening of the exhaust cavity.

10. The dual piston gas compressor of claim 1, wherein: The cylinder cover is provided with an intake passage communicated with the compression chamber, and an intake valve is arranged on the top of the compression chamber at the port of the intake passage.

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