Axial force balancing structure, screw compressor and refrigeration equipment

Abstract

The utility model discloses an axial force balance structure, screw compressor and refrigeration equipment, the axial force balance structure comprises: a screw compressor, which is provided with a working rotor for compressing gas, the gas generates a first axial force relative to the working rotor when the gas is compressed in the screw compressor; the screw oil pump is provided with a screw rotor used for pushing oil liquid to flow, a valve piece is installed at an oil outlet of the screw oil pump, the oil liquid generates second axial force relative to the screw rotor when flowing in the screw oil pump, and the second axial force is controlled by adjusting the opening degree of the valve piece; wherein the working rotor is coaxially connected with the screw rotor, and the directions of the first axial force and the second axial force are opposite. The hydraulic pressure of the screw oil pump is used for counteracting at least one part of rotor axial force generated when the compressor works, the load and the number of the bearings are reduced, and the running reliability of the screw compressor is improved.

Description

Technical Field

[0001] This utility model relates to the field of compressor technology, and in particular to an axial force balancing structure, a screw compressor, and refrigeration equipment. Background Technology

[0002] With economic growth and social development, the demand for resources such as oil and coal continues to increase, and the refrigeration industry is gradually shifting towards these areas. However, due to the harshness of the mining environment, many large refrigeration equipment are unable to adapt to complex operating conditions, while screw compressors, with their high reliability, low maintenance costs, and strong environmental adaptability, have become the ideal choice for harsh operating conditions.

[0003] In applications with high cooling demands, compressor performance is often affected by evaporation temperature, condensation temperature, and rotational speed. Generally, the lower the evaporation temperature, the higher the condensation temperature, and the higher the rotational speed, the stronger the compressor's cooling capacity. However, as the pressure ratio and rotational speed increase, the axial force on the compressor rotor also increases significantly. Axial force refers to the gas thrust along the compressor rotor axis. If this force is too large, it may place additional loads on the bearings and sealing system, and even lead to equipment damage.

[0004] like Figure 1 , 2 As shown, in the screw compressor 1, the balance of axial forces typically relies on a balancing piston structure. The balancing piston 4 counteracts the thrust on the rotor by generating a reverse axial force, thereby reducing the load on the bearings. However, the existing design of the balancing piston 4 still has certain limitations. For example, the angular contact bearing 5 requires preload, which is usually transmitted to the bearing through the balancing piston 4 by the tightening force of the screws 6 on the outside of the compressor body. At the same time, the oil pressure on the balancing piston 4 sleeve is also applied to the bearing, resulting in excessive load on the bearing and affecting its service life. In addition, excessive preload not only increases the compressor's energy consumption but also limits the compressor's design specifications, making bearing selection more difficult.

[0005] Under high pressure ratio conditions, the bearing load-bearing capacity requirements are higher, while under low pressure ratio and low speed conditions, excessive preload may cause abnormal compressor startup and further increase energy consumption. Since user operating conditions may change frequently, existing balanced piston structures cannot maintain optimal performance under all conditions, thus affecting system stability and long-term equipment reliability.

[0006] To address the aforementioned issues, a novel axial force balancing structure is urgently needed to optimize the bearing stress of screw compressors and improve the reliability of refrigeration equipment operation. Utility Model Content

[0007] To address the shortcomings of existing balanced piston structures in terms of adaptability, this invention proposes an axial force balancing structure, a screw compressor, and refrigeration equipment. It utilizes the hydraulic pressure of the screw oil pump to counteract at least a portion of the rotor axial force generated during compressor operation, thereby reducing bearing load and number, and improving the reliability of the screw compressor operation.

[0008] The technical solution adopted in this utility model is to design an axial force balancing structure, including:

[0009] A screw compressor having a working rotor for compressing gas, wherein the gas generates a first axial force relative to the working rotor when compressed inside the screw compressor;

[0010] A screw oil pump has a screw rotor for driving the flow of oil. A valve is installed at the oil outlet of the screw oil pump. When the oil flows inside the screw oil pump, it generates a second axial force relative to the screw rotor. The magnitude of the second axial force is controlled by adjusting the opening of the valve.

[0011] The working rotor is coaxially connected to the screw rotor, and the first axial force and the second axial force are in opposite directions.

[0012] Furthermore, the magnitudes of the first axial force and the second axial force are the same.

[0013] Furthermore, the working rotor and the screw rotor are connected by a connecting shaft, allowing the working rotor and the screw rotor to rotate asynchronously relative to the connecting shaft.

[0014] Furthermore, the screw oil pump is provided with a mounting hole for the connecting shaft to pass through, and a sealing structure is provided between the mounting hole and the connecting shaft.

[0015] Furthermore, the axial force balancing structure also includes a force measuring element for detecting the magnitude of the first axial force, and the opening degree of the valve is controlled by the detection value of the force measuring element.

[0016] Furthermore, the force measuring element is located at the end of the rotor tooth groove on the exhaust side of the screw compressor.

[0017] Furthermore, the first end of the working rotor is close to the exhaust side of the screw compressor, and the second end is close to the intake side of the screw compressor. The screw rotor is coaxially connected to either the first or second end of the working rotor.

[0018] In some embodiments, the valve is a throttle valve.

[0019] This invention also proposes a screw compressor that employs the aforementioned axial force balancing structure.

[0020] This utility model also proposes a refrigeration device, including the aforementioned screw compressor.

[0021] Compared with the prior art, this utility model adds a screw oil pump to the exhaust / intake side of the screw compressor. The working rotor is coaxially connected to the screw rotor. A valve is installed at the oil outlet of the screw oil pump. The axial hydraulic pressure of the screw rotor is controlled by the pressure difference between the inlet and outlet. This adaptively offsets part of the axial force generated by the working rotor, thereby reducing the bearing load and number, improving the reliability of the screw compressor operation, and reducing the energy consumption of the refrigeration equipment. Attached Figure Description

[0022] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0023] Figure 1 This is a schematic diagram of a twin-screw compressor in the prior art;

[0024] Figure 2 This is a partially enlarged schematic diagram of a twin-screw compressor in the prior art;

[0025] Figure 3 This is a schematic diagram of the axial force balance structure of this utility model;

[0026] Figure 4 This is a schematic diagram of the axial force of the screw oil pump located on the exhaust side of the screw compressor;

[0027] Figure 5 This is a schematic diagram of the axial force of the screw oil pump located on the suction side of the screw compressor;

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Screw compressor; 2. Male rotor; 3. Female rotor; 4. Balance piston; 5. Angular contact bearing; 6. Screw;

[0030] 100. Screw oil pump; 200. Valve; 300. Connecting shaft; 400. Working rotor; 500. Oil inlet; 600. Oil outlet. Detailed Implementation

[0031] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0032] like Figure 1 As shown, the axial force balancing structure proposed in this utility model has a screw compressor and a screw oil pump 200. The hydraulic pressure of the screw oil pump 200 is used to offset at least a portion of the rotor axial force generated when the screw compressor is working, thereby reducing the bearing load and number, and improving the reliability of the screw compressor 1 operation.

[0033] Specifically, taking a twin-screw compressor and a single-screw oil pump as examples, the screw compressor 1 typically includes a male rotor 2 and a female rotor 3. The male rotor 2 and the female rotor 3 mesh to form a compression chamber. When the gas is compressed inside the screw compressor 1, a pressure difference is generated, which in turn generates a first axial force relative to the rotor. The magnitude of this force depends on the thrust of the high-pressure gas on the rotor end face on the exhaust side. The male rotor 2, as the driving rotor, is directly connected to the drive shaft and bears the main gas thrust. The female rotor 3 is driven to rotate by the male rotor 2 and is subjected to less force. Its toothed structure allows part of the axial force to be offset by the male rotor 2. Since the axial force inside the screw compressor is mainly concentrated in the male rotor 2, the working rotor 400 preferably consists of the male rotor 2.

[0034] The screw oil pump 100 has a screw rotor for driving the flow of oil, including but not limited to lubricating oil or refrigeration oil. A valve 200 is installed at the oil outlet of the screw oil pump 100. The oil enters the screw oil pump 100 from the oil inlet 500 and flows out of the screw oil pump 100 through the oil outlet 600. Adjusting the opening of the valve 200 can control the flow rate at the oil outlet 600, so that a certain pressure difference is generated in the oil inside the screw oil pump 100, forming a pressure buildup phenomenon, thereby generating hydraulic pressure relative to the axial direction of the screw rotor.

[0035] Based on this, such as Figures 4 to 5 As shown, the working rotor 400 is coaxially connected to the screw rotor. The first axial force and the second axial force are in opposite directions. The hydraulic pressure of the screw oil pump 100 is used to counteract at least a portion of the rotor axial force generated during compressor operation, reducing the bearing load and number, and improving the reliability of the screw compressor 1. Preferably, the first axial force and the second axial force are the same magnitude, ensuring consistent bearing stress under any operating condition or speed, thus extending bearing life.

[0036] In a preferred embodiment of this invention, the valve 200 is a throttle valve, such as an electronic expansion valve, which controls the hydraulic pressure. When the throttling is small, the axial hydraulic pressure generated inside the screw oil pump 100 is small, corresponding to the low differential pressure condition of the refrigeration equipment or the screw compressor operating at low speed. When the throttling is large, the axial hydraulic pressure generated inside the screw oil pump 100 is large, corresponding to the high differential pressure condition of the refrigeration equipment or the screw compressor operating at high speed.

[0037] This design counteracts the axial force generated when the working rotor 400 of the screw compressor 1 rotates at different speeds / operating conditions by adjusting the throttling magnitude of throttling elements such as the electronic expansion valve. This keeps the axial force on the bearing within a certain range, improving bearing life while ensuring reliable operation of the screw compressor.

[0038] like Figure 4 , 5As shown, in some embodiments of this utility model, the screw compressor 1 and the screw oil pump 100 are each equipped with an independently operating motor. The working rotor 400 and the screw rotor are rotatably connected via a connecting shaft 300. One end of the connecting shaft 300 is movably connected to the working rotor 400, and the other end is movably connected to the screw rotor. The connecting shaft 300 transmits the axial force between the working rotor 400 and the screw rotor, and the working rotor 400 and the screw rotor can rotate asynchronously relative to the connecting shaft 300. The connecting shaft 300 can be connected to the working rotor 400 and the screw rotor via a coupling. This design can maintain the independent operation of the screw compressor 1 and the screw oil pump 100, and can also utilize the hydraulic pressure of the screw oil pump to counteract at least a portion of the rotor axial force generated during compressor operation.

[0039] It should be understood that the screw rotor, connecting shaft 300, and working rotor 400 of the screw oil pump 100 are preferably arranged on the same horizontal plane to ensure that the force is in the same direction and that the force on the structure is uniform.

[0040] In some embodiments of this utility model, the screw oil pump 100 is provided with a mounting hole for the connecting shaft 300 to pass through. A sealing structure is provided between the mounting hole and the connecting shaft 300. The sealing structure includes, but is not limited to, a comb-tooth seal structure. A comb-tooth seal is a non-contact dynamic sealing device that increases fluid resistance through multi-stage meandering flow channels. Its core feature is that alternating annular teeth and annular grooves form a comb-like meshing structure, creating a controllable leakage path between mechanical rotating parts. The purpose of this design is to prevent a large amount of oil from leaking out of the screw oil pump 100, which would prevent the formation of hydraulic pressure.

[0041] In some embodiments of this utility model, the axial force balancing structure further includes: a force-measuring element for detecting the magnitude of the first axial force; the opening degree of the valve 200 is controlled by the detection value of the force-measuring element; and the feedback of the pressure value is linked to the opening degree of the valve 200. The advantage of this design lies in significantly improving the dynamic response accuracy and operational reliability of the axial force balancing structure through the synergistic effect of real-time monitoring and closed-loop control.

[0042] In practical applications, force-measuring elements (such as pressure sensors) can be placed at the bearing end of the working rotor of the screw compressor, enabling them to capture instantaneous changes in axial force with a millisecond-level response speed and achieve efficient transmission of detection signals. Based on the detected values, the opening of valves (such as electronic expansion valves) is dynamically adjusted to achieve precise matching of the axial forces between the screw oil pump 100 and the screw compressor 1. This active control mechanism eliminates the over-balance or under-balance problems caused by the fixed preload design in traditional solutions, thereby avoiding the risks of bearing overload and seal failure.

[0043] Preferably, the force-measuring element is located at the end of the exhaust-side rotor tooth groove of the screw compressor 1. The end of the exhaust-side rotor tooth groove refers to the last spiral tooth groove near the compressor exhaust port, where the gas pressure is highest (close to the exhaust pressure) and is the main source of axial thrust. By arranging the force-measuring element at this location, the axial thrust of the high-pressure gas on the working rotor 400 can be monitored, and the valve opening of the screw oil pump 100 can be adjusted accordingly, which is beneficial for the precise control of the axial force of the working rotor 400.

[0044] It should be noted that the first end of the working rotor 400 is close to the exhaust side of the screw compressor 1, and the second end is close to the intake side of the screw compressor 1. The screw rotor is coaxially connected to either the first or second end of the working rotor 400. Figure 4 , 5 As shown, in practical applications, the screw oil pump 100 can be installed on the exhaust side or the suction side of the screw compressor, as long as the directions of the first axial force and the second axial force are opposite, making the installation more flexible.

[0045] like Figures 3 to 5 As shown, this utility model also proposes a screw compressor, which adopts the above-mentioned axial force balancing structure and uses the hydraulic pressure of the screw oil pump 200 to offset at least a portion of the rotor axial force generated when the screw compressor is working, thereby reducing the bearing load and number and improving the reliability of the screw compressor 1.

[0046] This utility model also proposes a refrigeration device, including: the aforementioned screw compressor, by adding a screw oil pump on the exhaust / intake side of the screw compressor, the working rotor being coaxially connected to the screw rotor, and a valve being installed at the oil outlet of the screw oil pump, the axial hydraulic pressure of the screw rotor being controlled by the pressure difference between the inlet and outlet, thereby adaptively offsetting part of the axial force generated by the working rotor, reducing the bearing load and number, improving the reliability of the screw compressor operation, and reducing the energy consumption of the refrigeration device.

[0047] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments according to this utility model. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings can be implemented in any order unless a specific express order is specified, and as long as the output of the preceding process is not used in the subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0048] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0049] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An axial force balancing structure, characterized by, include: A screw compressor having a working rotor for compressing gas, wherein the gas generates a first axial force relative to the working rotor when compressed inside the screw compressor; A screw oil pump has a screw rotor for driving the flow of oil. A valve is installed at the oil outlet of the screw oil pump. When the oil flows inside the screw oil pump, it generates a second axial force relative to the screw rotor. The magnitude of the second axial force is controlled by adjusting the opening of the valve. The working rotor is coaxially connected to the screw rotor, and the first axial force and the second axial force are in opposite directions.

2. The axial force balancing structure according to claim 1, characterized by, The magnitudes of the first axial force and the second axial force are the same.

3. The axial force balancing structure of claim 1, wherein, The working rotor and the screw rotor are connected by a connecting shaft, and the working rotor and the screw rotor can rotate asynchronously relative to the connecting shaft.

4. The axial force balancing structure according to claim 3, characterized by, The screw oil pump is provided with a mounting hole for the connecting shaft to pass through, and a sealing structure is provided between the mounting hole and the connecting shaft.

5. The axial force balancing structure according to claim 1, characterized by, Also includes: A force-measuring element is used to detect the magnitude of the first axial force, and the opening degree of the valve is controlled by the detection value of the force-measuring element.

6. The axial force balancing structure of claim 5, wherein, The force measuring element is located at the end of the rotor tooth groove on the exhaust side of the screw compressor.

7. The axial force balancing structure of claim 1, wherein, The first end of the working rotor is close to the exhaust side of the screw compressor, and the second end is close to the intake side of the screw compressor. The screw rotor is coaxially connected to either the first or second end of the working rotor.

8. The axial force balancing structure according to any one of claims 1 to 7, characterized in that, The valve is a throttle valve.

9. Screw compressor, characterized in that The screw compressor adopts the axial force balance structure as described in any one of claims 1 to 8.

10. A refrigeration appliance characterised in that, include: The screw compressor according to claim 9.

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