Structure for inhibiting offset of piston of linear compressor, compressor and refrigerating machine

Abstract

The invention relates to a structure for restraining offset of a piston of a linear compressor, the compressor and a refrigerating machine, the structure is arranged in the linear compressor, the linear compressor comprises a machine shell, an air cylinder, a suspension assembly and two linear motors, the air cylinder and the suspension assembly are installed in the machine shell, and the two linear motors are oppositely arranged; the linear motors are in driving connection with pistons, and the pistons of the two linear motors are slidably installed at the two ends of the air cylinder correspondingly and define a compression cavity. The end, away from the piston, of the linear motor and the machine shell form a back pressure cavity, and the linear motor is fixed into the machine shell through a hanging assembly. A one-way countercurrent airflow channel is arranged in the machine shell, an air inlet of the one-way countercurrent airflow channel is communicated with the backpressure cavity, and an air outlet of the one-way countercurrent airflow channel is communicated with the compression cavity and used for adjusting the pressure of the compression cavity and the backpressure cavity. Compared with the prior art, the piston has the advantages that the structure is simple, machining is convenient, piston offset can be effectively restrained, and the refrigerating performance of the refrigerator is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of cryogenic refrigeration machines, and in particular to a structure, compressor, and refrigeration machine for suppressing piston bias in a linear compressor. Background Technology

[0002] In 1862, KRIK successfully applied the reverse Stirling cycle to the field of refrigeration, thus laying the technological foundation for Stirling refrigerators. Leveraging its unique refrigeration advantages, Stirling refrigerators have been widely used in key technology fields such as infrared remote sensing and high-temperature superconductivity, and occupy an indispensable position in many important sectors including commerce, military, and aerospace. Currently, Stirling refrigerators widely used in the industry generally integrate core technologies such as opposed compressors, linear motor drives, leaf spring supports, and gap seals. The integrated application of these technologies effectively improves the operational stability and refrigeration efficiency of the refrigerators, promoting their large-scale application in various fields.

[0003] In the actual operation of Stirling refrigerators, the piston of the linear compressor is prone to offset, which has become one of the key issues affecting the performance of the refrigerator. Specifically, during the compressor assembly stage, the compressor piston has clearly defined upper and lower dead centers, namely the compression limit and the expansion limit, and both values ​​are equal. Under the support of leaf spring technology, when the refrigerator is not working, the piston is in the initial equilibrium position, at which point the offset is zero. When the compressor is driven by pure sinusoidal AC current, the piston will perform sinusoidal reciprocating motion, and its dynamic equilibrium position will deviate from the initial equilibrium position. This phenomenon is defined in the industry as compressor offset, and the amount of deviation between the piston's dynamic equilibrium position and the initial equilibrium position is called the offset amount.

[0004] The presence of piston offset in compressors can have a serious negative impact on the performance and lifespan of Stirling refrigerators. On the one hand, piston offset reduces the actual maximum stroke, directly decreasing the refrigerator's cooling performance. In extreme cases, it can even cause a single-sided piston impact, damaging core components and leading to equipment shutdown. On the other hand, since Stirling refrigerators currently commonly use leaf spring support technology, piston offset can cause a significant difference in the stroke on both sides of the leaf spring, with one side having an excessively large stroke and the other an excessively small stroke. Prolonged exposure to this asymmetrical stress state will significantly accelerate leaf spring fatigue, severely shortening their lifespan and increasing maintenance costs and the risk of failure.

[0005] To address the bias problem during the reciprocating motion of compressor pistons, various technical solutions have been proposed in the industry. Among them, the following four types are more widely used: (1) strengthening the axial stiffness of the leaf springs; (2) adjusting the pressure of the compressor back pressure chamber; (3) applying a reverse DC voltage in the piston bias direction; and (4) constructing a bypass branch outside the compressor. However, the above-mentioned existing solutions all have obvious limitations and are difficult to achieve efficient and low-cost bias suppression in practical engineering applications.

[0006] Specifically, the axial stiffness of a leaf spring has a physical upper limit and cannot be increased indefinitely. Simultaneously, as the axial stiffness of the leaf spring increases, the piston's running resistance also increases, leading to a significant increase in the driving force required by the compressor. This is detrimental to the energy-saving operation and long-term stable function of the refrigeration unit. In practical engineering applications, applying a reverse DC voltage is a commonly used bias suppression method. This solution controls the refrigeration unit's operation through an electronic control system, incorporating a DC voltage component in the piston's movement direction to pull the piston back to its initial equilibrium position. However, the additional DC voltage component directly increases the refrigeration unit's power consumption, reducing the equipment's energy efficiency.

[0007] Although the invention disclosed in CN114790976A is a piston offset control device and its adjustment method for a reciprocating DC linear compressor, the purpose is to adjust the piston shaft offset problem caused by back pressure imbalance during the operation of the reciprocating DC linear compressor. This piston offset control device consists of a branch tee, an electromagnetic control valve, a metering control valve, a branch bypass pipe, and a casing sealing cover. The overall structure is connected in parallel to the compressor's suction pipe. During compressor operation, by inputting a square wave signal of the same frequency to the electromagnetic control valve, it is controlled to open and close in coordination with the piston movement, thereby adjusting the back pressure to balance the pressure difference between the cylinder and the back pressure chamber, thus reducing piston offset.

[0008] However, while constructing a piston bias control device consisting of a branch tee, electromagnetic control valve, metering control valve, and branch bypass pipe outside the compressor can achieve bias control to a certain extent, this solution significantly increases the structural complexity of the equipment. This not only increases the manufacturing cost of the equipment but also greatly increases the difficulty of operation, making it unfavorable for the installation, commissioning, and subsequent maintenance of the equipment.

[0009] Therefore, there is a need for a structure that is easy to process, manufacture, and install, has low economic cost, and can significantly limit compressor bias by suppressing piston bias in linear compressors. Summary of the Invention

[0010] The purpose of this invention is to overcome the defects of the prior art and provide a structure, compressor, and refrigeration machine that is easy to process, manufacture, and install, has low economic cost, and can greatly limit compressor bias by suppressing piston bias in linear compressors.

[0011] The objective of this invention can be achieved through the following technical solutions: This solution provides a structure for suppressing piston bias in a linear compressor, which is installed inside the linear compressor. The linear compressor includes a housing, a cylinder installed inside the housing, a suspension assembly, and two linear motors arranged opposite each other. The linear motors are driven by pistons, and the pistons of the two linear motors are slidably installed at both ends of the cylinder, forming a compression chamber. The end of the linear motor away from the piston forms a back pressure chamber with the housing, and the linear motor is fixed inside the housing by the suspension assembly. The housing is provided with a unidirectional counter-current airflow channel. The inlet of the unidirectional counter-current airflow channel is connected to the back pressure chamber, and the outlet is connected to the compression chamber, which is used to adjust the pressure of the compression chamber and the back pressure chamber.

[0012] Furthermore, the unidirectional countercurrent airflow channel includes a capillary tube, which is disposed inside the piston and arranged along the axial direction of the piston.

[0013] Furthermore, capillary channels are provided inside the pistons on both sides of the compression chamber.

[0014] Furthermore, the one-way countercurrent airflow channel also includes a one-way valve, which is installed at the end of the capillary tube near the back pressure chamber, and the air inlet of the one-way valve faces the back pressure chamber.

[0015] Furthermore, the one-way counter-current airflow channel operates when the piston resets. When the pressure in the back pressure chamber is higher than the pressure in the compression chamber, the one-way valve in the back pressure chamber opens, and the gas flows to the compression chamber through the capillary tube to counteract the leakage during the compression process.

[0016] Furthermore, the unidirectional countercurrent airflow channel also includes a small orifice valve, which is installed at the end of the capillary tube near the back pressure chamber.

[0017] Furthermore, the unidirectional counter-current airflow channel operates when the piston resets, adjusting the compensation flow rate of the orifice valve according to the piston's offset until the compensation flow rate equals the slit leakage, and the piston returns to its original balanced position.

[0018] Furthermore, a compressor assembly is provided inside the housing, and the compressor assembly is provided with a compression chamber exhaust port. One end of the compression chamber exhaust port is connected to the compression chamber, and the other end is connected to the outside of the housing.

[0019] This solution also provides a linear compressor, including at least the aforementioned structure for suppressing piston bias in a linear compressor.

[0020] This solution also provides a refrigeration unit, including at least one of the linear compressors described above.

[0021] Compared with the prior art, the present invention has the following advantages: This solution adds a capillary tube between the compression chamber and the back pressure chamber, and installs a one-way valve at the end of the tube on the back pressure chamber side. When the pressure in the back pressure chamber is higher than that in the compression chamber, the one-way valve opens, allowing gas to flow through the capillary tube to the compression chamber. This partially offsets the leakage of gas from the compression chamber to the back pressure chamber through the slit, thereby adjusting the piston to its original equilibrium position. This solves the offset problem of the linear compressor during actual operation, offsetting the offset during piston operation. Compared to the complex structure and difficult operation of existing piston offset adjustment devices, this solution's compressor offset suppression structure is simple overall, requiring no additional equipment. It only requires pre-processing the capillary tube and installing the one-way valve, making it easy to process and install, simple to operate, easier to implement than other methods, and lower in manufacturing cost. It ensures the cooling effect of the refrigerant and effectively extends the service life of the suspension components. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an existing linear opposed compressor structure; Figure 2 A schematic diagram of an opposed compressor having a structure for suppressing piston bias in a linear compressor, provided by the present invention; Figure 3 A schematic diagram of a single compressor with a structure for suppressing piston bias in a linear compressor, provided by the present invention; In the diagram: 1. Compressor assembly; 2. Linear motor assembly; 3. Suspension assembly; 4. Housing; 5. One-way counter-current airflow channel; 6. One-way valve; 7. Compression chamber exhaust port; 11. Back pressure chamber; 12. Compression chamber; 13. Piston. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed during use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0028] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] Example 1 like Figure 2 As shown, this embodiment provides a structure for suppressing piston bias in a linear compressor. The structure is located inside the linear compressor, which includes a housing 4, a cylinder installed within the housing 4, a suspension assembly 3, and two opposing linear motors. The linear motors are connected to pistons 13, which are slidably mounted at both ends of the cylinder, forming a compression chamber 12. The end of the linear motor furthest from the piston 13 forms a back pressure chamber 11 with the housing 4, and the linear motor is fixed inside the housing 4 by the suspension assembly 3. A one-way counter-current airflow channel 5 is provided inside the housing 4. The inlet of the one-way counter-current airflow channel 5 connects to the back pressure chamber 11, and the outlet connects to the compression chamber 12, used to adjust the pressure of the compression chamber 12 and the back pressure chamber 11.

[0030] In this embodiment, the unidirectional countercurrent airflow channel 5 includes a capillary tube and a one-way valve 6. The capillary tube is disposed inside the piston 13 and is arranged along the axial direction of the piston 13. Capillary tubes are provided inside the pistons 13 on both sides of the compression chamber 12. The one-way valve 6 is installed at the end of the capillary tube near the back pressure chamber 11, and the air inlet of the one-way valve 6 faces the back pressure chamber 11.

[0031] Specifically, the one-way counter-current airflow channel 5 operates when the piston 13 is reset. When the pressure in the back pressure chamber 11 is higher than the pressure in the compression chamber 12, the one-way valve 6 in the back pressure chamber 11 opens, and the gas flows to the compression chamber 12 through the capillary tube to offset the leakage during the compression process.

[0032] In this embodiment, a compressor assembly 1 is housed inside the casing 4. The compressor assembly 1 has a compression chamber exhaust port 7, one end of which connects to the compression chamber 12, and the other end connects to the outside of the casing 4. Corresponding linear motor assemblies 2 are provided on the outer sides of both linear motors to drive the piston reciprocating motion. The suspension assembly 3 can be a leaf spring. Figure 1 As shown, these structures belong to the prior art and will not be described in detail. The present invention adds a one-way counterflow airflow channel inside the linear compressor to compensate for the gas leaked during the compression process in the compression chamber, so that the piston returns to its original position. This structure is easy to process, manufacture and install, has low economic cost, and can limit the compressor bias to a large extent, thereby improving the compressor energy efficiency.

[0033] This embodiment also provides a linear opposed compressor, including at least one of the above-described structures for suppressing piston offset in a linear compressor. It can accurately correct the dynamic balance position of the piston, avoid potential offset hazards, improve operational stability, and has strong structural adaptability and is easy to assemble.

[0034] This embodiment also provides a refrigeration unit, including at least one of the linear opposed compressors described above. It can effectively suppress piston offset, ensure the actual piston stroke, and thus guarantee stable refrigeration performance output. Furthermore, its overall structure is compact and adaptable to various application scenarios.

[0035] Example 2 This embodiment is basically the same as Embodiment 1, except that the one-way counter-current airflow channel 5 in this embodiment includes a capillary tube and a small orifice valve, with the small orifice valve installed at the end of the capillary tube near the back pressure chamber 11. The one-way counter-current airflow channel 5 operates when the piston 13 resets. Based on the piston's offset, the compensation flow rate of the small orifice valve is adjusted until the compensation flow rate equals the slit leakage, at which point the piston resets to its original equilibrium position. This structure functions the same as the one-way valve in Embodiment 1, aiming to compensate for the air pressure in the back pressure chamber and compression chamber, ensuring piston reset. It has a simple structure, is easy to manufacture and install, and is simple to operate, making it easier to implement than other methods.

[0036] Example 3 This embodiment is basically the same as Embodiment 1, except that, as Figure 3 As shown, this embodiment provides a single compressor with a unidirectional counter-current airflow channel 5 set on the piston driven by a linear motor. The leakage of the compression chamber 12 can be compensated by the back pressure chamber 11, thereby ensuring that the piston returns to its original position. The structure is simplified and the energy consumption is lower, while maintaining good operational stability and refrigeration efficiency adaptability. It is easy to assemble with various miniaturized and lightweight refrigeration equipment.

[0037] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A structure for suppressing piston bias in a linear compressor, disposed inside the linear compressor, characterized in that, The linear compressor includes a housing (4) and a cylinder, a suspension assembly (3) installed in the housing (4) and two linear motors arranged opposite to each other; the linear motors are connected to pistons (13), and the pistons (13) of the two linear motors are slidably installed at both ends of the cylinder and form a compression chamber (12); the end of the linear motor away from the piston (13) forms a back pressure chamber (11) with the housing (4), and the linear motor is fixed inside the housing (4) by the suspension assembly (3); the housing (4) is provided with a one-way counterflow airflow channel (5), the air inlet of the one-way counterflow airflow channel (5) is connected to the back pressure chamber (11), and the air outlet is connected to the compression chamber (12), which is used to adjust the pressure of the compression chamber (12) and the back pressure chamber (11).

2. The structure for suppressing piston bias in a linear compressor according to claim 1, characterized in that, The unidirectional countercurrent airflow channel (5) includes a capillary tube, which is disposed inside the piston (13) and arranged along the axial direction of the piston (13).

3. The structure for suppressing piston bias in a linear compressor according to claim 2, characterized in that, Both sides of the compression chamber (12) have capillary channels inside the pistons (13).

4. The structure for suppressing piston bias in a linear compressor according to claim 2, characterized in that, The one-way countercurrent airflow channel (5) also includes a one-way valve (6), which is installed at the end of the capillary tube near the back pressure chamber (11), and the air inlet of the one-way valve (6) faces the back pressure chamber (11).

5. The structure for suppressing piston bias in a linear compressor according to claim 4, characterized in that, The one-way counterflow airflow channel (5) operates when the piston (13) is reset. When the pressure in the back pressure chamber (11) is higher than the pressure in the compression chamber (12), the one-way valve (6) in the back pressure chamber (11) opens, and the gas flows to the compression chamber (12) through the capillary tube to offset the leakage during the compression process.

6. The structure for suppressing piston bias in a linear compressor according to claim 2, characterized in that, The unidirectional countercurrent airflow channel (5) also includes a small orifice valve, which is installed at the end of the capillary tube near the back pressure chamber (11).

7. The structure for suppressing piston bias in a linear compressor according to claim 6, characterized in that, The unidirectional countercurrent airflow channel (5) operates when the piston (13) is reset. According to the piston's offset, the compensation flow of the small orifice valve is adjusted until the compensation flow equals the slit leakage. The piston returns to its original balanced position.

8. The structure for suppressing piston bias in a linear compressor according to claim 1, characterized in that, The housing (4) is provided with a compressor assembly (1), and the compressor assembly (1) is provided with a compression chamber exhaust port (7). One end of the compression chamber exhaust port (7) is connected to the compression chamber (12), and the other end is connected to the outside of the housing (4).

9. A linear compressor, characterized in that, It includes at least the structure for suppressing piston bias in a linear compressor as described in any one of claims 1-8.

10. A refrigeration machine, characterized in that, It includes at least one linear compressor as described in claim 9.

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