Gear transmission device, two-stage screw compressor and air conditioner

Abstract

The invention relates to a gear transmission device, a two-stage screw compressor and an air conditioner. The gear transmission device comprises a low-pressure stage rotor, a high-pressure stage rotor, a coupler and an adjusting gear assembly, and the adjusting gear assembly is located on the same side of the low-pressure stage rotor, the high-pressure stage rotor and the coupler. The adjusting gear assembly comprises a first adjusting gear and a second adjusting gear in coaxial transmission with the first adjusting gear, and the first adjusting gear is in meshing transmission with the periphery of the low-pressure-stage rotor. Under the refrigeration working condition, the low-pressure stage rotor and the high-pressure stage rotor are in coaxial transmission through the coupler, and the second adjusting gear is configured to idle; and under the heating working condition, the coupling is disengaged from the low-pressure-stage rotor, the coupling and the high-pressure-stage rotor are kept in meshing transmission, and the second adjusting gear is configured to be in meshing transmission with the periphery of the coupling.

Description

Technical Field

[0001] This application relates to the field of compressors, and particularly to a gear transmission device, a two-stage screw compressor, and an air conditioner. Background Art

[0002] The two-stage compression intermediate gas injection technology has been widely used in screw refrigeration compressors. From the refrigeration principle, it can be known that during two-stage compression, when the intermediate pressure is the square root of (evaporation pressure * condensation pressure), the system energy efficiency is the highest. However, for a single-stage two-stage screw compressor, the low-pressure stage rotor and the high-pressure stage rotor are connected by a coupling to transmit torque. As long as the sizes of the two-stage rotors are determined, the corresponding rotor displacement at each rotational speed is also determined. From the perspective of the cycle, the intermediate cavity pressure is determined. Therefore, a single-stage two-stage screw compressor usually only has an intermediate pressure that is the square root of (evaporation pressure * condensation pressure) under the nominal working conditions.

[0003] When the working conditions change, although each stage can adjust the theoretical internal volume ratio of each stage rotor through the internal volume ratio adjustment slide valve to match different working conditions and achieve efficient operation. However, at this time, the intermediate pressure will deviate from the theoretical value with the highest system energy efficiency. Summary of the Invention

[0004] This application provides a gear transmission device, a two-stage screw compressor, and an air conditioner to solve the technical problem that when the working conditions change, the intermediate pressure of a single-stage two-stage screw compressor will deviate from the theoretical value with the highest system energy efficiency in the above-mentioned prior art.

[0005] The present invention provides a gear transmission device, which includes: a low-pressure stage rotor, a high-pressure stage rotor, a coupling, and an adjustment gear assembly. The coupling is coaxially connected between the low-pressure stage rotor and the high-pressure stage rotor; the adjustment gear assembly is located on the same side of the low-pressure stage rotor, the high-pressure stage rotor, and the coupling. The adjustment gear assembly includes a first adjustment gear and a second adjustment gear that is coaxially driven with the first adjustment gear. The first adjustment gear is meshed and driven with the outer periphery of the low-pressure stage rotor; under refrigeration working conditions, the low-pressure stage rotor and the high-pressure stage rotor are coaxially driven through the coupling, and the second adjustment gear is configured to rotate idly; under heating working conditions, the coupling is disengaged from meshing with the low-pressure stage rotor, the coupling remains meshed and driven with the high-pressure stage rotor, and the second adjustment gear is configured to be meshed and driven with the outer periphery of the coupling.

[0006] Wherein, the coupling includes a first end shaft and a second end shaft. Under refrigeration working conditions, the first end shaft extends into the first inner cavity of the low-pressure stage rotor and is meshed and drivenly connected with the first inner cavity of the low-pressure stage rotor, and the second end shaft extends into the second inner cavity of the high-pressure stage rotor and is meshed and drivenly connected with the second inner cavity of the high-pressure stage rotor.

[0007] Among them, the second inner cavity of the high-pressure stage rotor includes a second meshing section and a second cavity section communicating with the second meshing section. The second meshing section is used for meshing and driving with the second end shaft of the coupling. The second cavity section is provided with a piston mechanism, and the piston mechanism is used to push the coupling to move towards the direction where the low-pressure stage rotor is located.

[0008] Among them, the first inner cavity of the low-pressure stage rotor includes a first meshing section and a first cavity section communicating with the first meshing section. The first meshing section is used for meshing and driving with the first end shaft of the coupling. The first cavity section is provided with a thrust piece, and the thrust piece is used to limit the maximum displacement of the coupling towards the low-pressure stage rotor.

[0009] Among them, the shaft end of the low-pressure stage rotor has a first toothed shaft section, and the coupling has a third toothed shaft section on the outer periphery; the first adjusting gear and the second adjusting gear in the adjusting gear assembly are coaxial and arranged at intervals, and the first adjusting gear meshes and drives with the first toothed shaft section; Under the heating condition, the coupling moves to the position of the second adjusting gear and meshes and drives with the second adjusting gear, and the first meshing section of the first inner cavity in the low-pressure stage rotor disengages from the first end shaft in the coupling.

[0010] Among them, the number of teeth of the second adjusting gear is less than that of the first adjusting gear.

[0011] Among them, the number of teeth of the first toothed shaft section is greater than that of the third toothed shaft section.

[0012] Among them, the meshing structures adopted at each meshing and driving position are all spline-like structures.

[0013] The present invention further provides a two-stage screw compressor, including the above-mentioned gear transmission device.

[0014] The present invention also provides an air conditioner, including the above-mentioned two-stage screw compressor.

[0015] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art: The gear transmission device, two-stage screw compressor and air conditioner provided by the embodiments of the present application can obtain a structure that can adjust the discharge volume of the high-pressure stage in a single-stage two-stage screw compressor by changing the meshing transmission relationship among the high-pressure stage rotor, low-pressure stage rotor and coupling, and is used to match the theoretical intermediate pressure of the system. Through such a structural setting, synchronous rotation among the low-pressure stage rotor, coupling and high-pressure stage rotor can be achieved under refrigeration conditions, and under heating conditions, the rotation speed of the high-pressure stage rotor can be adjusted independently. During the process, the coupling rotates synchronously with the high-pressure stage rotor, and the coupling does not drive the low-pressure stage rotor to rotate synchronously, so as to adjust the compression ratio distribution of each stage of the compressor, so as to achieve the theoretical optimum for the compression ratio distribution under different working conditions, thereby improving the system energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings here are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention and, together with the specification, are used to explain the principles of the present invention.

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0018] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements, unless otherwise stated, and the drawings in the drawings do not constitute a proportional limitation.

[0019] Figure 1 Schematic structural diagram of the meshing state of the gear transmission device under refrigeration conditions provided by the embodiments of the present application; Figure 2 Schematic structural diagram of the instantaneous (just starting to mesh) state of the rotational speed change provided by the embodiments of the present application; Figure 3 Schematic structural diagram of the meshing state of the gear transmission device under heating conditions provided by the embodiments of the present application; Figure 4 Schematic structural diagram corresponding to each meshing structure 7 in the gear transmission device provided by the embodiments of the present application.

[0020] Description of the reference numerals in the drawings: 1. Low-pressure stage rotor; 11. First inner cavity; 111. First meshing section; 112. First cavity section; 12. First toothed shaft section; 2. High-pressure stage rotor; 21. Second inner cavity; 211. Second meshing section; 212. Second cavity section; 22. Second toothed shaft section; 3. Coupling; 31. First end shaft; 32. Second end shaft; 33. Third toothed shaft section; 4. Adjusting gear assembly; 41. First adjusting gear; 42. Second adjusting gear; 5. Piston mechanism; 6. Thrust piece; 7. Meshing structure 7. Detailed implementation mode

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0022] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0023] For ease of description, spatial relative relationship terms may be used in the text to describe the relative positional relationship or movement of one element or feature shown in the figure relative to another element or feature. These relative relationship terms are, for example, "inner", "outer", "inner side", "outer side", "below", "beneath", "above", "upper", "front", "rear", etc. Such spatial relative relationship terms are intended to include different orientations of the device in use or operation other than the orientations depicted in the figure. For example, if the device in the figure undergoes a position flip or attitude change or movement state change, then these directional indications will also change accordingly. For example, an element described as "below other elements or features" or "beneath other elements or features" will then be oriented as "above other elements or features" or "upper than other elements or features". Therefore, the exemplary term "below" can include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other directions) and the spatial relative relationship descriptions used in the text have been interpreted accordingly.

[0024] The bipolar screw compressor is a common refrigeration compressor. Regarding its structure, the bipolar screw compressor generally includes main components, working chambers, synchronous gears, and an intermediate gas injection device. Regarding the main components, the main components include a low-pressure stage screw rotor, a high-pressure stage screw rotor, a housing, synchronous gears, a shaft seal, bearings, a suction end seat, a discharge end seat, an intermediate gas injection device, and a slide valve, etc.; Regarding the working chambers, inside the housing, two independent working chambers are formed by the screw rotors and the inner wall of the housing, namely the low-pressure stage working chamber and the high-pressure stage working chamber. The low-pressure stage working chamber is used to inhale low-temperature and low-pressure refrigerant gas and perform preliminary compression, while the high-pressure stage working chamber further compresses the refrigerant gas from the low-pressure stage to make it reach a higher pressure and temperature. Regarding the synchronous gears, the synchronous gears are used to ensure the synchronous operation between the low-pressure stage rotor and the high-pressure stage rotor, make them precisely cooperate according to a certain transmission ratio, and ensure the normal operation of the compressor. Regarding the intermediate gas injection device, the intermediate gas injection device is located between the low-pressure stage and the high-pressure stage and is used to supplement refrigerant gas to the intermediate chamber during the compression process to improve the performance and efficiency of the compressor.

[0025] Based on the above structure of the bipolar screw compressor, both the gas compression function and the energy regulation function are realized. Regarding compression, the working principle of the two-stage screw compressor is based on the basic working principle of the screw compressor, that is, through the rotation of a pair of meshing screw rotors in the housing, the refrigerant gas is continuously compressed in the tooth space volume; in two-stage compression, the refrigerant gas is first preliminarily compressed in the low-pressure stage rotor, then enters the intermediate chamber, and after intermediate gas injection, it enters the high-pressure stage rotor for further compression, and finally reaches the required discharge pressure. Regarding energy regulation, energy regulation is achieved through a slide valve; the slide valve can change the effective working length of the rotor, thereby regulating the refrigerant flow rate and compression ratio to adapt to different refrigeration load requirements; for example, when the refrigeration load is low, the slide valve shortens the effective working length of the rotor, reduces the refrigerant flow rate and compression work, and lowers the energy consumption of the compressor.

[0026] Regarding the working process, (suction process) the low-temperature and low-pressure refrigerant gas enters the low-pressure stage working chamber from the suction port. As the low-pressure stage screw rotor rotates, the volume between the teeth gradually increases, forming a negative pressure and sucking in the refrigerant gas; when the volume between the teeth reaches the maximum, the suction process ends. (Low-pressure stage compression process) After the suction ends, as the rotor continues to rotate, the volume between the teeth gradually decreases, and the refrigerant gas is compressed, with the pressure and temperature gradually increasing. During the low-pressure stage compression process, the refrigerant gas is compressed to the intermediate pressure. (Intermediate gas injection process) When the refrigerant gas compressed in the low-pressure stage enters the intermediate chamber, the intermediate gas injection device replenishes a certain amount of medium-pressure refrigerant gas into the intermediate chamber. This part of the gas injection can increase the refrigerating capacity and energy efficiency ratio of the compressor, and at the same time reduce the exhaust temperature of the compressor. (High-pressure stage compression process) The refrigerant gas after intermediate gas injection enters the high-pressure stage working chamber. Under the action of the high-pressure stage screw rotor, the refrigerant gas is compressed again, and the pressure and temperature further increase until the condensation pressure is reached. (Exhaust process) The high-temperature and high-pressure refrigerant gas compressed in the high-pressure stage is discharged from the exhaust port and enters the condenser, where it is cooled and condensed into a liquid, completing a refrigeration cycle.

[0027] Based on this, the bipolar screw compressor can achieve efficient operation under different working conditions through bipolar compression and intermediate gas injection technologies, and is widely used in various refrigeration and air-conditioning systems.

[0028] Under the nominal working conditions, the design of the single-stage bipolar screw compressor is based on theoretical calculations. At this time, the intermediate pressure is the square root of (evaporation pressure * condensation pressure), which is the ideal state obtained according to the thermodynamic principle of the refrigeration cycle. In this state, the compression ratio of each stage of the compressor, the refrigerant flow rate and other parameters are matched with each other, making the energy efficiency of the entire system reach the highest. This is an optimized design based on specific conditions (such as specific refrigerating capacity, evaporation temperature, condensation temperature, etc.).

[0029] When the working conditions change, such as the ambient temperature changes, the refrigeration load changes, etc., the evaporation pressure and the condensation pressure will change accordingly. Although each stage can adjust the theoretical internal volume ratio of each rotor through the internal volume ratio regulating slide valve to try to adapt to the new working conditions and achieve efficient operation. However, this adjustment method has certain limitations. The internal volume ratio adjustment mainly adjusts the compression ratio by changing the working volume of the rotor, but it cannot exactly match all the parameter changes brought about by the change of the working conditions. For example, the refrigerant flow rate, physical properties parameters, etc. will also change with the change of the working conditions, and these factors will also affect the intermediate pressure. Therefore, even after the internal volume ratio adjustment, the intermediate pressure may still deviate from the theoretical value when the system energy efficiency is the highest.

[0030] Therefore, a single-stage two-stage screw compressor can achieve an ideal intermediate pressure and the highest energy efficiency under nominal conditions. However, when the operating conditions change, due to the complexity of system parameters and the limitations of the internal volume ratio adjustment method, the intermediate pressure is prone to deviate from the theoretical optimum value.

[0031] To alleviate the above technical problems, referring to Figures 1-4 , the embodiment of the present application provides a single-stage two-stage screw compressor, which can achieve independent adjustment of the rotational speed of the high-pressure stage rotor 2, thereby adjusting the pressure ratio distribution of each stage of the compressor, so as to achieve the theoretical optimum for the pressure ratio distribution under different operating conditions, thereby improving the system energy efficiency. That is, it can achieve efficient operation of the high-pressure stage rotor 2 at two rotational speeds corresponding to two operating conditions.

[0032] The embodiment of the present application provides a gear transmission device, which can obtain a structure for adjusting the exhaust volume of the high-pressure stage in a single-stage two-stage screw compressor by changing the meshing transmission relationship among the high-pressure stage rotor, the low-pressure stage rotor 1 and the coupling 3, and is used to match the theoretical intermediate pressure of the system.

[0033] The embodiment of the present application provides a gear transmission device, including: a low-pressure stage rotor 1, a high-pressure stage rotor 2, a coupling 3 and an adjustment gear assembly 4. The coupling 3 is coaxially connected between the low-pressure stage rotor 1 and the high-pressure stage rotor 2; the adjustment gear assembly 4 is located on the same side of the low-pressure stage rotor 1, the high-pressure stage rotor 2 and the coupling 3. The adjustment gear assembly 4 includes a first adjustment gear 41 and a second adjustment gear 42 coaxially driven with the first adjustment gear 41. The first adjustment gear 41 is meshed and driven with the outer periphery of the low-pressure stage rotor 1; under refrigeration conditions, the low-pressure stage rotor 1 and the high-pressure stage rotor 2 are coaxially driven through the coupling 3, and the second adjustment gear 42 is configured to rotate idly; under heating conditions, the coupling 3 is disengaged from the low-pressure stage rotor 1, the coupling 3 remains meshed and driven with the high-pressure stage rotor 2, and the second adjustment gear 42 is configured to be meshed and driven with the outer periphery of the coupling 3.

[0034] Applying the transmission scheme as above, under the refrigeration condition, the power starts from the low-pressure stage rotor 1. The low-pressure stage rotor 1 starts to rotate driven by an external power source such as a motor. At this time, coaxial transmission is achieved between the low-pressure stage rotor 1 and the high-pressure stage rotor 2 through the coupling 3. This means that the rotation of the low-pressure stage rotor 1 will be directly transmitted to the high-pressure stage rotor 2 through the coupling 3, causing the high-pressure stage rotor 2 and the low-pressure stage rotor 1 to rotate synchronously at the same speed (because of coaxial transmission); although the first adjusting gear 41 in the adjusting gear assembly 4 meshes and drives with the outer circumference of the low-pressure stage rotor 1, the second adjusting gear 42 is configured to rotate idly. That is to say, the first adjusting gear 41 will rotate with the rotation of the low-pressure stage rotor 1, but due to the idle rotation of the second adjusting gear 42, it will not have an additional impact on the power transmission of the entire transmission process, and it only exists structurally and does not participate in the actual power transmission to change the speed of the high-pressure stage rotor 2; since the high-pressure stage rotor 2 and the low-pressure stage rotor 1 rotate synchronously, at this time, the high-pressure stage displacement is mainly determined by the speed of the low-pressure stage rotor 1 and the design parameters of the compressor itself, maintaining a relatively stable state under this condition to meet the system requirements under the refrigeration condition.

[0035] Applying the transmission scheme as above, when entering the heating condition, the first thing that happens is that the coupling 3 disengages from the low-pressure stage rotor 1, which cuts off the direct transmission path between the low-pressure stage rotor 1 and the high-pressure stage rotor 2 that originally passed through the coupling 3; at this time, the adjusting gear assembly 4 starts to play a role. The first adjusting gear 41 continues to mesh and drive with the outer circumference of the low-pressure stage rotor 1, and the rotation of the low-pressure stage rotor 1 drives the first adjusting gear 41 to rotate. Since the first adjusting gear 41 and the second adjusting gear 42 are in coaxial transmission, the second adjusting gear 42 will rotate together with the first adjusting gear 41. And the second adjusting gear 42 is configured to mesh and drive with the outer circumference of the coupling 3, so the rotation of the second adjusting gear 42 will be transmitted to the high-pressure stage rotor 2 through the coupling 3; due to the intervention of the adjusting gear assembly 4, the speed of the high-pressure stage rotor 2 is no longer the same as that of the low-pressure stage rotor 1, but is changed by the transmission ratio of the adjusting gear assembly 4. Specifically, the transmission ratio of the adjusting gear assembly 4 determines the speed change of the high-pressure stage rotor 2 relative to the low-pressure stage rotor 1. By reasonably designing parameters such as the number of teeth of the first adjusting gear 41 and the second adjusting gear 42, the speed of the high-pressure stage rotor 2 can be accurately controlled; since the displacement of the screw compressor is proportional to the speed, when the speed of the high-pressure stage rotor 2 changes, the high-pressure stage displacement will also change accordingly. By adjusting the high-pressure stage displacement, the intermediate pressure can be made to match the theoretical intermediate pressure of the system under the heating condition.

[0036] In summary, the synchronous rotation between the low-pressure stage rotor 1, the coupling 3 and the high-pressure stage rotor 2 can be achieved under the refrigeration condition, and the speed of the high-pressure stage rotor 2 can be adjusted separately under the heating condition. In the process, the coupling 3 rotates synchronously with the high-pressure stage rotor 2, and the coupling 3 will not drive the low-pressure stage rotor 1 to rotate synchronously, thereby adjusting the pressure ratio distribution of each stage of the compressor, so as to achieve the theoretical optimal pressure ratio distribution under different working conditions, thereby improving the system energy efficiency.

[0037] From the overall structure, the gear transmission device is applied to the two-stage screw compressor, which can enhance the adaptability of the two-stage screw compressor to the working conditions. By changing the meshing transmission relationship between the high-pressure stage rotor 2, the low-pressure stage rotor 1 and the coupling 3, the gear transmission device can flexibly adjust the transmission mode under two different working conditions: cooling and heating. Under cooling conditions, a simple and direct coaxial transmission of the coupling 3 is adopted to ensure the high efficiency and stability of the cooling process; under heating conditions, the transmission ratio is changed by adjusting the gear assembly 4, so that the compressor can adapt to the different requirements of the heating conditions for the high-pressure stage exhaust volume, thereby enhancing the adaptability of the compressor to different working conditions.

[0038] From the overall structure, the gear transmission device is applied to the two-stage screw compressor to achieve the matching of the intermediate pressure. Under different working conditions, the theoretical intermediate pressure of the system is different. By adjusting the high-pressure stage exhaust volume, the intermediate pressure can be made closer to the theoretical intermediate pressure of the system. In the heating condition, the speed of the high-pressure stage rotor 2 is changed by adjusting the gear assembly 4, and then the high-pressure stage exhaust volume is adjusted, so that the intermediate pressure can better match the theoretical value under the heating condition, thereby improving the energy efficiency and performance of the entire system.

[0039] From the overall structure, the gear transmission device is applied to the two-stage screw compressor, and the effect of adjusting the speed of the high-pressure stage rotor 2 can be achieved by using a simple structure, that is, the adjusting gear assembly 4 is located on the same side of the low-pressure stage rotor 1, the high-pressure stage rotor 2 and the coupling 3. This layout makes the structure of the entire device relatively compact and easy to install and maintain. Moreover, through a simple switching of the meshing relationship (engagement and disengagement of the coupling 3 and the low-pressure stage rotor 1) and the participation of the adjusting gear assembly 4, the adjustment of the high-pressure stage exhaust volume can be achieved, avoiding complex mechanical structures and control systems, and improving the reliability and economy of the device.

[0040] Considering the transmission scheme of the coupling 3 and the low-pressure stage rotor 1 and the high-pressure stage rotor 2 under refrigeration conditions, in the gear transmission device provided in the embodiment of the present application, the coupling 3 includes a first end shaft 31 and a second end shaft 32. Under refrigeration conditions, the first end shaft 31 extends into the first inner cavity 11 of the low-pressure stage rotor 1, and is meshed and driven with the first inner cavity 11 of the low-pressure stage rotor 1. The second end shaft 32 extends into the second inner cavity 21 of the high-pressure stage rotor 2, and is meshed and driven with the second inner cavity 21 of the high-pressure stage rotor 2.

[0041] In this way, by adopting the synchronous transmission scheme in which the two end shafts of the coupling 3 respectively extend into the high-pressure stage rotor 2 and the low-pressure stage rotor 1, the low-pressure stage rotor 1 and the high-pressure stage rotor 2 can be directly connected through the coupling 3, and the structure is relatively compact; moreover, the meshing transmission method can achieve efficient power transmission and reduce power loss. Because during meshing transmission, the contact between components is close, and there is almost no slippage phenomenon during the power transmission process, which can ensure that the power of the low-pressure stage rotor 1 is transmitted to the high-pressure stage rotor 2 to the greatest extent, thereby improving the overall working efficiency of the compressor.

[0042] Furthermore, the stable meshing transmission connection enables the rotational speed relationship between the low-pressure stage rotor 1 and the high-pressure stage rotor 2 to always remain relatively fixed under the refrigeration condition; this fixed rotational speed relationship helps to maintain the pressure balance inside the compressor and the stability of gas flow; for example, in a refrigeration system, the stable rotational speed relationship can ensure the stable compression process of the refrigerant in the compressor, and there will be no problems such as unstable refrigeration capacity caused by rotational speed fluctuations, thereby improving the stability and reliability of the operation of the entire refrigeration system; it is convenient to optimize the design and control of the compressor according to different working conditions; for example, under the refrigeration condition, parameters such as the exhaust volume and power consumption of the compressor can be accurately calculated according to this transmission scheme, so as to better match the operation requirements of the refrigeration system.

[0043] Considering the specific meshing transmission scheme between the coupling 3 and the high-pressure stage rotor 2, in the gear transmission device provided by the embodiment of the present application, the second inner cavity 21 of the high-pressure stage rotor 2 includes a second meshing section 211 and a second cavity section 212 communicating with the second meshing section 211. The second meshing section 211 is used for meshing transmission with the second end shaft 32 of the coupling 3, and the second cavity section 212 is provided with a piston mechanism 5, and the piston mechanism 5 is used to push the coupling 3 to move towards the direction where the low-pressure stage rotor 1 is located.

[0044] In this way, the transmission adjustment during working condition switching can be achieved; in the refrigeration working condition, the coupling 3 meshes and drives with the low-pressure stage rotor 1 and the high-pressure stage rotor 2 normally. When it is necessary to switch to the heating working condition, the piston mechanism 5 comes into play. The piston mechanism 5 pushes the coupling 3 to move towards the direction where the low-pressure stage rotor 1 is located, which causes the coupling 3 to gradually disengage from the low-pressure stage rotor 1. Since one end of the coupling 3 is in the second inner cavity 21 of the high-pressure stage rotor 2, by the push of the piston mechanism 5, the axial position of the coupling 3 is changed, and thus the relative position relationship with the low-pressure stage rotor 1 is changed, realizing the change of the meshing state between the two. This design enables the compressor to flexibly adjust the transmission relationship under different working conditions and meet the requirements of different working conditions for the torque transmission path. When switching back from the heating working condition to the refrigeration working condition, the piston mechanism 5 can act in the reverse direction (or rely on other reset mechanisms) to reset the coupling 3 and re-engage it with the low-pressure stage rotor 1, restoring the transmission state under the refrigeration working condition, ensuring the operability and stability of the working condition switching.

[0045] It should be noted that the existence of the piston mechanism 5 provides a means for precisely controlling the meshing and disengagement between the coupling 3 and the low-pressure stage rotor 1. By controlling the movement of the piston mechanism 5, the moving distance and speed of the coupling 3 can be precisely controlled, thus accurately realizing the switching of the transmission relationship. Compared with some methods that rely on external forces or simple mechanical structures to achieve meshing and disengagement, this has higher precision and reliability. For example, in some application scenarios with high requirements for working condition switching, it can quickly and accurately adjust the transmission relationship, avoiding the decline in compressor performance or failures caused by inaccurate switching.

[0046] Furthermore, due to the structural design of the second meshing section 211 and the second cavity section 212, the installation and acting positions of the piston mechanism 5 are more reasonable; the second meshing section 211 ensures the stable connection between the coupling 3 and the high-pressure stage rotor 2 during normal transmission, while the second cavity section 212 provides an installation space and an acting space for the piston mechanism 5. The two cooperate with each other, making the structure of the entire transmission system more compact and reasonable.

[0047] For the gear transmission device capable of improving the working condition adaptability of the compressor according to the embodiment of the present application, in the heating working condition, after the coupling 3 disengages from the low-pressure stage rotor 1, different torque transmission paths can be realized through other transmission components (such as the adjusting gear assembly 4 mentioned above) to adjust the high-pressure stage exhaust volume and make the intermediate pressure match the theoretical value under the heating working condition; while in the refrigeration working condition, the coupling 3 meshes normally with the low-pressure stage rotor 1 and the high-pressure stage rotor 2, ensuring efficient operation under the refrigeration working condition. Through this flexible adjustment of the transmission relationship, the compressor can maintain good performance under different working conditions, improving its application range and practicability.

[0048] In addition, the design of the piston mechanism 5 can also buffer the impact force during the transmission process to a certain extent; when the working conditions are switched, the movement of the piston mechanism 5 can absorb part of the impact force generated due to the change of the transmission relationship, reduce the damage to the internal components of the compressor, extend the service life of the compressor, and also help to reduce the vibration and noise during operation.

[0049] Considering the specific meshing transmission scheme of the coupling 3 and the low-pressure stage rotor 1, in the gear transmission device provided by the embodiment of the present application, the first inner cavity 11 of the low-pressure stage rotor 1 includes a first meshing section 111 and a first cavity section 112 communicating with the first meshing section 111. The first meshing section 111 is used for meshing transmission with the first end shaft 31 of the coupling 3, and the first cavity section 112 is provided with a thrust member 6, and the thrust member 6 is used to limit the maximum displacement of the coupling 3 towards the low-pressure stage rotor 1.

[0050] In this way, the transmission stability can be ensured, the integrity of the components can be protected, and the working condition switching and system control can be facilitated.

[0051] Regarding ensuring the transmission stability, first, the meshing depth can be accurately controlled. Under the refrigeration working condition, the first end shaft 31 of the coupling 3 meshes with the first meshing section 111 of the low-pressure stage rotor 1 to realize the power transmission from the low-pressure stage rotor 1 to the high-pressure stage rotor 2. The existence of the thrust member 6 can accurately control the maximum displacement of the first end shaft 31 of the coupling 3 inserted into the first inner cavity 11, ensuring that the first end shaft 31 and the first meshing section 111 are in the best meshing depth; if the meshing depth is too shallow, it may cause slipping during the transmission process, resulting in a reduction in the power transmission efficiency, and even may cause the separation between the coupling 3 and the low-pressure stage rotor 1, affecting the normal operation of the compressor. The thrust member 6 limits the maximum displacement and avoids this situation, ensuring stable power transmission. Second, stable torque transmission can be maintained. The stable meshing depth helps to maintain stable torque transmission. During the operation of the compressor, stable torque transmission is crucial for ensuring the performance of the compressor. By limiting the displacement of the coupling 3 with the thrust member 6, the contact area and contact force between the first end shaft 31 and the first meshing section 111 are kept relatively stable, so as to ensure that the torque can be reliably transmitted from the low-pressure stage rotor 1 to the coupling 3 and then to the high-pressure stage rotor 2, improving the stability and reliability of the entire transmission system.

[0052] Regarding the protection of component integrity, first of all, it can prevent over-insertion from damaging components. During the operating condition switching or the operation of the compressor, the coupling 3 may move excessively towards the low-pressure stage rotor 1. Without the restriction of the thrust member 6, the first end shaft 31 of the coupling 3 may be over-inserted into the first inner cavity 11, thereby damaging the wall surface of the first inner cavity 11, the first end shaft 31 itself, and the related meshing teeth; the thrust member 6 can timely prevent the excessive displacement of the coupling 3, avoid component damage caused by over-insertion, extend the service life of key components such as the low-pressure stage rotor 1 and the coupling 3, and reduce the maintenance cost and failure rate of the compressor. Secondly, it can reduce impact and wear. When the coupling 3 approaches the maximum displacement during movement, the thrust member 6 can play a buffering role and reduce the impact between the coupling 3 and the low-pressure stage rotor 1. This buffering effect helps to reduce the wear between components, especially in the case of frequent operating condition switching, and can significantly reduce the possibility of component performance degradation and failures caused by impact and wear.

[0053] Regarding the operating condition switching and system control, first of all, it can ensure the accuracy of operating condition switching. When switching between the refrigeration operating condition and the heating operating condition, the coupling 3 needs to engage or disengage with the low-pressure stage rotor 1. The presence of the thrust member 6 provides a clear position reference for this operation, enabling the coupling 3 to accurately move to the appropriate position during the operating condition switching process and ensuring the accuracy of the engagement and disengagement operations; for example, when switching back from the heating operating condition to the refrigeration operating condition, the coupling 3 needs to re-engage with the low-pressure stage rotor 1, and the thrust member 6 can help the coupling 3 quickly and accurately reach the correct engagement position, improving the efficiency and reliability of the operating condition switching. Secondly, it is beneficial to the overall control of the system. For the control of the entire compressor system, the presence of the thrust member 6 makes the displacement of the coupling 3 predictable and controllable. The control system can better adjust the actions of components such as the piston mechanism 5 according to the position information defined by the thrust member 6, achieve precise control of the position and state of the coupling 3, and thus optimize the operating performance of the compressor under different operating conditions.

[0054] Considering the specific transmission scheme among the low-pressure stage rotor 1, the high-pressure stage rotor 2, the coupling 3, and the adjusting gear assembly 4, in the gear transmission device provided by the embodiment of the present application, the shaft end of the low-pressure stage rotor 1 has a first toothed shaft section 12, the shaft end of the high-pressure stage rotor 2 has a second toothed shaft section 22, and the coupling 3 has a third toothed shaft section 33 on its outer periphery; in the adjusting gear assembly 4, the first adjusting gear 41 and the second adjusting gear 42 are coaxial and spaced apart, and the first adjusting gear 41 meshes with the first toothed shaft section 12 for transmission; in the heating operating condition, the coupling 3 moves to the position of the second adjusting gear 42 and meshes with the second adjusting gear 42 for transmission, and the first meshing section 111 of the first inner cavity 11 in the low-pressure stage rotor 1 disengages from the first end shaft 31 in the coupling 3.

[0055] In this way, efficient transmission with different working conditions can be achieved. First, regarding the construction of an independent transmission path for the heating working condition, in the heating working condition, the coupling 3 moves to mesh and drive with the second adjusting gear 42, and at the same time, the low-pressure stage rotor 1 disengages from the coupling 3. At this time, the power transmission path of the low-pressure stage rotor 1 changes: the low-pressure stage rotor 1 meshes with the first adjusting gear 41 through the first toothed shaft section 12 at the end of the shaft. Since the first adjusting gear 41 and the second adjusting gear 42 are coaxial, the second adjusting gear 42 then meshes with the third toothed shaft section 33 on the outer periphery of the coupling 3, and finally transmits the power to the second toothed shaft section 22 of the high-pressure stage rotor 2; this change in the transmission path enables the high-pressure stage rotor 2 not to maintain a direct coaxial speed relationship with the low-pressure stage rotor 1, but rather the speed of the high-pressure stage rotor 2 can be flexibly adjusted by adjusting the tooth number ratio of the adjusting gear assembly 4; for example, if the first adjusting gear 41 has more teeth and the second adjusting gear 42 has fewer teeth, when the speed of the low-pressure stage rotor 1 is constant, the speed of the high-pressure stage rotor 2 will decrease, thereby reducing the high-pressure stage exhaust volume to match the theoretical intermediate pressure under the heating working condition and achieving the optimization of the system energy efficiency. Second, regarding the efficient direct transmission for the refrigeration working condition, in the refrigeration working condition, the coupling 3 directly meshes and drives with the low-pressure stage rotor 1 and the high-pressure stage rotor 2. At this time, the power of the low-pressure stage rotor 1 is directly and efficiently transmitted to the high-pressure stage rotor 2 through the coupling 3, and the two rotate coaxially with the same speed. This direct transmission method reduces the intermediate transmission links and the transmission loss, meets the demand for stable refrigeration capacity under the refrigeration working condition, and ensures the efficient operation of the compressor under the refrigeration working condition. Through the differential design of the transmission paths under two different working conditions, the compressor can maintain good performance under different working conditions, improving the overall adaptability to working conditions.

[0056] Meanwhile, it can also achieve the function of precisely adjusting the high-pressure stage exhaust volume. First of all, based on the flexible adjustment of the gear transmission ratio, the introduction of the adjustment gear assembly 4 provides the possibility for the precise adjustment of the high-pressure stage exhaust volume; under the heating condition, through the meshing transmission of the first adjustment gear 41 and the first toothed shaft section 12, and the second adjustment gear 42 and the third toothed shaft section 33, using the principle of the gear transmission ratio, the rotation speed of the high-pressure stage rotor 2 can be adjusted according to the actual working condition requirements; because the exhaust volume of the screw compressor is proportional to the rotation speed, changing the rotation speed of the high-pressure stage rotor 2 can achieve the adjustment of the high-pressure stage exhaust volume. For example, when the system detects that the intermediate pressure is higher than the theoretical value under the heating condition, the adjustment gear assembly 4 can be adjusted (such as replacing the adjustment gears with different numbers of teeth), increasing the rotation speed of the high-pressure stage rotor 2 and the high-pressure stage exhaust volume, thereby reducing the intermediate pressure and making it close to the theoretical optimal value; conversely, when the intermediate pressure is lower than the theoretical value, the rotation speed of the high-pressure stage rotor 2 is reduced, the high-pressure stage exhaust volume is reduced, and the intermediate pressure is increased, ultimately achieving the precise matching of the intermediate pressure and the system theoretical intermediate pressure and improving the system energy efficiency. Secondly, it can achieve the adaptive adjustment of dual working conditions. Since the adjustment gear assembly 4 can achieve the flexible adjustment of the high-pressure stage exhaust volume, the gear transmission device can effectively adapt to the two working conditions of refrigeration and heating. Under the refrigeration condition, there is no need for the adjustment gear assembly 4 to participate in the adjustment, and the direct transmission ensures efficient refrigeration; under the heating condition, the adjustment gear assembly 4 plays a role, and adjusts the high-pressure stage exhaust volume according to the characteristics and requirements of the heating condition, ensuring that the compressor can operate efficiently under both working conditions, meeting the usage requirements under different working conditions, and expanding the application range of the compressor.

[0057] Furthermore, it can also enhance the stability and reliability of the system structure. First, there are clear positioning and mating of the transmission components. The low-pressure stage rotor 1, high-pressure stage rotor 2, coupling 3, and adjustment gear assembly 4 are connected and driven through specific toothed shaft segments and meshing relationships, and the positioning and mating of each component are clear. For example, the meshing of the first adjustment gear 41 with the first toothed shaft segment 12, the second adjustment gear 42 with the third toothed shaft segment 33, and the connection and disengagement of the coupling 3 with each component under different working conditions are all precisely designed and specified. This clear structural relationship ensures that during the transmission process, power can be stably transmitted between components, reducing vibrations, noises, and wear caused by improper component mating. At the same time, during the working condition switching process, the movement of the coupling 3 and the change in the meshing state also have clear paths and position references, reducing the risk of failures during the working condition switching process and enhancing the stability of the system structure. Second, through a reasonably designed transmission scheme, the high efficiency of power transmission can be ensured under different working conditions. The direct drive under the refrigeration working condition reduces the energy loss in the intermediate links; under the heating working condition, although the adjustment gear assembly 4 is added, through precise gear meshing design, the energy loss can be controlled at a low level. In addition, the stable meshing relationship between components also helps to reduce additional energy losses caused by factors such as slipping and impact, improving the energy utilization efficiency of the entire system and ensuring the reliability of the compressor during long-term operation.

[0058] Considering the transmission ratio scheme of the overall device, in the gear transmission device provided by the embodiment of the present application, the number of teeth of the second adjustment gear 42 is less than the number of teeth of the first adjustment gear 41, and the number of teeth of the first toothed shaft segment 12 is less than the number of teeth of the third toothed shaft segment 33.

[0059] In this way, it is possible to achieve speed reduction and efficiency increase of the high-pressure stage rotor 2 under the heating condition. First of all, based on the speed reduction principle of the gear transmission ratio, in the gear transmission, the transmission ratio i is equal to the ratio of the number of teeth z2 of the driven gear to the number of teeth z1 of the driving gear (i = z2 / z1). When i>1, it is a speed reduction transmission. Under the heating condition, the low-pressure stage rotor 1 drives the first adjusting gear 41 to rotate through the first toothed shaft section 12. Since the second adjusting gear 42 is coaxial with the first adjusting gear 41, the second adjusting gear 42 then drives the third toothed shaft section 33 of the coupling 3. It is known that the number of teeth of the second adjusting gear 42 is less than that of the first adjusting gear 41, and the number of teeth of the first toothed shaft section 12 is less than that of the third toothed shaft section 33, which makes the entire transmission path form a multi-stage speed reduction effect. For example, assuming that the number of teeth z1 of the first adjusting gear 41 is 20, the number of teeth z2 of the second adjusting gear 42 is 15, the number of teeth z1 of the first toothed shaft section 12 is 30, and the number of teeth z3 of the third toothed shaft section 33 is 45, then the total transmission ratio i from the first toothed shaft section 12 to the third toothed shaft section 33 is (z1 / z1) * (z3 / z2), that is, the rotational speed of the high-pressure stage rotor 2 is only half of that of the low-pressure stage rotor 1. Secondly, it is possible to adapt to the energy efficiency optimization under the heating condition. The displacement of the screw compressor is proportional to the rotational speed. The speed reduction of the high-pressure stage rotor 2 means a reduction in the high-pressure stage displacement. Under the heating condition, the intermediate pressure required by the system is different from that under the refrigeration condition. By reducing the high-pressure stage displacement, the intermediate pressure can be made closer to the theoretical value with the highest energy efficiency of the system under the heating condition. Reducing the rotational speed of the high-pressure stage rotor 2 can also reduce its operating power consumption and avoid problems such as unreasonable compression ratio and too high exhaust temperature caused by too high rotational speed, thereby improving the energy efficiency and stability of the entire heating system.

[0060] Meanwhile, it can also optimize the power distribution and torque transmission under dual working conditions. First, it can achieve direct and efficient transmission in the refrigeration working condition. In the refrigeration working condition, the coupling 3 directly connects the low-pressure stage rotor 1 and the high-pressure stage rotor 2, and at this time, the adjusting gear assembly 4 does not participate in the power transmission. Since the first toothed shaft section 12 and the third toothed shaft section 33 do not directly participate in the transmission under this working condition, the difference in their tooth numbers (the tooth number of the first toothed shaft section 12 is less than that of the third toothed shaft section 33) will not affect the refrigeration working condition. The power of the low-pressure stage rotor 1 can be directly and efficiently transmitted to the high-pressure stage rotor 2, keeping the two running at the same speed, meeting the demand for stable output of refrigerating capacity under the refrigeration working condition, and realizing efficient operation under the refrigeration working condition. Second, it can achieve torque amplification and stable transmission in the heating working condition. In the heating working condition, the multi-stage gear transmission not only realizes speed reduction but also is accompanied by torque amplification (according to the law of conservation of energy, power P = T * w, and the torque T will increase during speed reduction, where w is the angular velocity). The relatively large tooth number of the first toothed shaft section 12 enables it to bear the relatively large torque output by the low-pressure stage rotor 1, while the relatively large tooth number of the third toothed shaft section 33, when cooperating with the second adjusting gear 42, stably transmits the amplified torque to the high-pressure stage rotor 2. This optimized design of torque transmission ensures that in the heating working condition, even if the speed of the high-pressure stage rotor 2 decreases, sufficient torque can be obtained to maintain the stable progress of the compression process, avoiding problems such as a decrease in compression efficiency or unstable operation caused by insufficient torque.

[0061] Furthermore, it can also enhance the system's adaptability to working conditions and structural compactness. First, it can accurately match the dual working condition requirements. By setting the tooth number of the second adjusting gear 42 to be less than that of the first adjusting gear 41 and the tooth number of the first toothed shaft section 12 to be less than that of the third toothed shaft section 33, a unique transmission ratio scheme is formed. This scheme can accurately match the operation requirements of the refrigeration and heating working conditions. It maintains efficient direct transmission in the refrigeration working condition and realizes targeted speed reduction and pressure adjustment in the heating working condition, enabling the compressor to maintain good performance in different working conditions, greatly enhancing the system's adaptability to different working conditions, and broadening the application scenarios of the compressor. Second, a compact structural design is obtained. This transmission ratio scheme is based on the gear transmission principle. By reasonably designing the tooth numbers of each gear and toothed shaft section, while realizing the complex working condition adjustment function, there is no need to add too many complex transmission components or large-speed change mechanisms. Compared with other complex speed change methods (such as planetary gear speed change, etc.), this design makes the entire gear transmission device more compact, occupies less space, is convenient for installation and integration into the single-stage two-stage screw compressor system, and also reduces the manufacturing and maintenance costs.

[0062] Considering the meshing structure 7 of meshing transmission, in the gear transmission device provided by the embodiment of the present application, the meshing structure 7 at each meshing transmission position adopts a spline-like structure.

[0063] In this way, a spline-like structure is adopted at each meshing transmission position, which has significant logical effects in many aspects. From the perspective of transmission stability, the spline structure can evenly transmit torque through the cooperation of multiple key teeth and key grooves. Compared with ordinary flat key connections, it can effectively avoid component wear and looseness caused by uneven stress, ensuring stable and reliable power transmission between the low-pressure stage rotor 1, high-pressure stage rotor 2, coupling 3, and regulating gear assembly 4 during the operation of the compressor, and reducing vibration and noise. In terms of transmission efficiency, the meshing clearance on the tooth side of the spline is small, which can minimize energy loss during power transmission, making the transmission between components more efficient and contributing to improving the energy efficiency of the entire compressor system. From the perspective of assembly and maintenance, the spline structure has good centering and guiding properties, facilitating the installation and disassembly of components, reducing the assembly difficulty and time cost; at the same time, it has high structural strength and good wear resistance, which can extend the service life of components and reduce the maintenance frequency and repair cost caused by the damage of the meshing structure 7. In addition, during the working condition switching, the spline structure can ensure that the coupling 3 quickly and accurately meshes and disengages with each component, cooperate with other transmission components to achieve efficient switching of different transmission paths under refrigeration and heating working conditions, enhance the adaptability and response ability of the compressor to different working conditions, and thus ensure the stable and efficient operation of the entire gear transmission device under various working conditions.

[0064] When the gear transmission device according to the embodiment of the present application is applied, after the exhaust volume of the two-stage screw rotor is determined, the intermediate pressure constant value can be determined through iterative calculation. Since the rotor exhaust volume corresponds one-to-one with the rotational speed, and the rotational speeds of the high-pressure and low-pressure stage rotors 1 directly connected by the coupling 3 are equal, it is impossible to adjust the rotational speed of each stage separately. However, the low-pressure stage rotor 1 and the high-pressure stage rotor 2 adopt a new transmission connection scheme with the new coupling 3. Structures capable of transmitting torque such as threads or gears are provided on the shafts at both ends of the coupling 3, and the two shafts are inserted into the internal cavities (with corresponding transmission structures) of the two-stage rotors to achieve torque transmission between the two-stage rotors. Inside the rotor, in addition to the torque transmission structure, there will be cavities with a larger inner diameter (i.e., the first cavity section 112 and the second cavity section 212), and there is no transmission structure in the cavities. A piston mechanism 5 is provided in the cavity of the high-pressure stage rotor 2 to push the coupling 3 towards the low-pressure stage rotor 1; a thrust block is provided in the cavity of the low-pressure stage rotor 1 to limit the position of the coupling 3; a toothed shaft section a with the number of teeth Z1 is provided at the end of the shaft of the low-pressure stage rotor 1, and there is also an adjusting gear rotating shaft beside the coupling 3. This shaft is fixed separately, and there are also two toothed shaft sections on its shaft. The toothed shaft section b (with the number of teeth Z2) near the low-pressure stage rotor 1 end meshes with the toothed shaft section on the shaft of the low-pressure stage rotor 1, and the toothed shaft section c (with the number of teeth Z3) near the high-pressure stage rotor 2 end does not mesh with other shaft sections in the initial state and is in an idle state. Similarly, the new coupling 3 also has a toothed shaft section d in the middle section, with the number of teeth Z4. Among them, Z3 < Z2, and Z1 is slightly smaller than Z4, that is, under the heating condition, the rotational speed of the high-pressure stage rotor 2 decreases and the high-pressure stage displacement decreases because the condensation temperature under the heating condition is higher, the corresponding optimal intermediate pressure is higher, the gas density in the intermediate cavity is greater, and the volume under the same mass is smaller, so the high-pressure stage displacement needs to decrease.

[0065] In the initial state, the system operating condition is the refrigeration condition required by the user. The low-pressure stage rotor 1 is matched with the coupling 3 through the internal cavity transmission structure. The coupling 3 meshes with the internal transmission structure of the high-pressure stage rotor 2 cavity, driving the high-pressure stage rotor 2 to rotate. At this time, the shaft section b of the adjusting gear rotating shaft meshes with the shaft section a of the low-pressure stage rotor 1, driving the shaft section c to rotate idly. When the system operating condition needs to be converted to the heating condition required by the user, the high-pressure oil (high-pressure stage exhaust pressure) enters the right side of the cavity piston of the high-pressure stage rotor 2 through the oil supply hole of the high-pressure stage rotor 2. The oil hole of the low-pressure stage rotor 1 is connected to the low-pressure stage suction to increase the pressure difference between the two sections, pushing the coupling 3 to move towards the low-pressure stage. When the coupling 3 moves to the internal limit of the shaft, the shaft section c and the shaft section d of the coupling 3 are completely meshed, and the inside of the low-pressure stage rotor 1 cavity is disengaged from the coupling 3. At this time, the transmission between the low-pressure stage rotor 1 and the high-pressure stage rotor 2 is realized by the adjusting gear shaft. When switching from the heating condition to the refrigeration condition, the right side of the cavity piston of the high-pressure stage rotor 2 is connected to the low-pressure stage suction end. The oil hole of the low-pressure stage rotor 1 sucks in the high-pressure oil, and the gas pressure difference pushes the coupling 3 to move towards the high-pressure stage, returning to the initial state. It should be noted that when the shaft section d of the coupling 3 just starts to mesh with the shaft section c of the gear adjusting shaft, the internal meshing tooth section of the low-pressure stage rotor 1 needs to be disengaged, otherwise the rotor will be stuck.

[0066] Next, analyze the rotational speed of the high-pressure stage rotor 2 under the two operating conditions. In the initial state, the low-pressure stage and the high-pressure stage are connected by the coupling 3, so V_low = V_high. In the heating condition, according to the gear transmission ratio V1*Z1 = V2*Z2, it can be gradually deduced that V_high = V_low*Z1 / Z2*Z3 / Z4. Under the same module, the more teeth, the larger the diameter. It can be seen from the figure that Z3 < Z2 and Z1 is slightly larger than Z4. That is, in the heating condition, the rotational speed of the high-pressure stage rotor 2 decreases and the high-pressure stage displacement decreases. This is because the condensation temperature in the heating condition is higher, the corresponding optimal intermediate pressure is higher, the gas density in the intermediate cavity is greater, and the volume under the same mass is smaller. Therefore, the high-pressure stage displacement needs to decrease.

[0067] Additionally, the meshing structure 7 is a structure similar to a spline, and the spline types include but are not limited to rectangles, involutes, triangles, etc.

[0068] The embodiment of the present application further provides a two-stage screw compressor, including the above-mentioned gear transmission device.

[0069] Specifically, the two-stage screw compressor includes a housing, a core compression component, a power transmission system, and auxiliary components. Among them, the housing serves as the external framework of the entire compressor. The housing provides protection and support for the internal components, playing the roles of dust-proof, waterproof, fixing, and supporting the internal components, ensuring the stability of the compressor during operation. A closed space is formed inside it, providing a place for the compression process of the refrigerant gas and effectively reducing the transmission of operating noise. The core compression component includes a low-pressure stage screw rotor and a high-pressure stage screw rotor. The low-pressure stage screw rotor and the high-pressure stage screw rotor are respectively installed on the corresponding rotor shafts, and the two cooperate with each other inside the housing. The rotor has a special spiral tooth profile. As the rotor rotates, the volume between the teeth continuously changes, realizing the suction, compression, and discharge of the refrigerant gas. The power transmission system is a key part of the two-stage screw compressor, including the low-pressure stage rotor 1 shaft, the high-pressure stage rotor 2 shaft, the coupling 3, and the adjusting gear assembly 4. The end of the low-pressure stage rotor 1 shaft is provided with a first toothed shaft section 12. The first inner cavity 11 inside it is divided into a first meshing section 111 and a first cavity section 112. The first meshing section 111 is used for meshing and driving with the first end shaft 31 of the coupling 3, and the first cavity section 112 is provided with a thrust piece 6. The second toothed shaft section 22 at the end of the high-pressure stage rotor 2 shaft, its second inner cavity 21 includes a second meshing section 211 and a second cavity section 212. The second meshing section 211 is used for meshing with the second end shaft 32 of the coupling 3, and a piston mechanism 5 is equipped in the second cavity section 212. The coupling 3 has a first end shaft 31 and a second end shaft 32, which are respectively connected to the low-pressure stage rotor 1 and the high-pressure stage rotor 2. The adjusting gear assembly 4 is composed of a first adjusting gear 41 and a second adjusting gear 42. The two are coaxial and arranged at intervals. The first adjusting gear 41 meshes and drives with the first toothed shaft section 12 of the low-pressure stage rotor 1. The auxiliary components include a suction end seat, an exhaust end seat, an intermediate gas injection device, and a slide valve, etc. The suction end seat is used to guide the low-temperature and low-pressure refrigerant gas into the low-pressure stage screw rotor. The exhaust end seat discharges the high-temperature and high-pressure refrigerant gas compressed by the high-pressure stage screw rotor. The intermediate gas injection device can supplement the refrigerant gas into the intermediate cavity during the compression process, helping to improve the performance and efficiency of the compressor. The slide valve can adjust the internal volume ratio of each stage of the rotor to adapt to different working conditions and ensure the efficient operation of the compressor under various working conditions.

[0070] Applying the aforementioned gear transmission device to a two-stage screw compressor can enhance the adaptability to operating conditions. In traditional two-stage screw compressors, it is difficult to balance efficient operation under different operating conditions. After applying this gear transmission device, in the refrigeration operating condition, the coupling 3 directly connects the low-pressure stage rotor 1 and the high-pressure stage rotor 2 to achieve coaxial transmission, ensuring the efficient and stable refrigeration process; in the heating operating condition, by adjusting the gear assembly 4 to change the transmission path, the rotational speed of the high-pressure stage rotor 2 changes, thereby adjusting the high-pressure stage exhaust volume to meet the requirements of the heating operating condition. This flexible switching of the transmission method enables the two-stage screw compressor to maintain good performance in various operating conditions such as refrigeration and heating, significantly enhancing its adaptability to different operating conditions.

[0071] Applying the aforementioned gear transmission device to a two-stage screw compressor can improve the system energy efficiency. During the two-stage compression process, the intermediate pressure has an important impact on the system energy efficiency. When the intermediate pressure reaches the square root of (evaporation pressure * condensation pressure), the system energy efficiency is the highest. This gear transmission device can change the high-pressure stage exhaust volume by adjusting the rotational speed of the high-pressure stage rotor 2 according to the change of operating conditions, so that the intermediate pressure is closer to the theoretical optimal value. Whether in the refrigeration or heating operating condition, it can effectively improve the system energy efficiency, reduce energy consumption, save a large amount of operating costs compared with traditional compressors, and also conforms to the development trend of energy conservation and environmental protection.

[0072] Applying the aforementioned gear transmission device to a two-stage screw compressor can improve the operating stability and reliability. The gear transmission device adopts a spline-type meshing structure 7, which can evenly transmit torque, reduce wear and looseness between components, reduce vibration and noise during operation, and improve the stability of transmission. In addition, the design of thrust parts 6 and piston mechanisms 5 in the device accurately controls the displacement of the coupling 3, ensuring that the transmission relationship can be accurately adjusted during the operating condition switching process, avoiding transmission failures, thereby greatly improving the overall operating stability and reliability of the two-stage screw compressor, reducing the number of maintenance times and maintenance costs, and extending the service life of the compressor.

[0073] Applying the aforementioned gear transmission device to a two-stage screw compressor can achieve structural optimization and compactness. The design of this gear transmission device is ingenious. While realizing the function of complex operating condition adjustment, it maintains the compactness of the overall structure. Compared with the traditional transmission structure, this device does not require adding too many complex components, and the layout of each component is reasonable, occupying less space; this not only facilitates the miniaturized design and production of the compressor, but also reduces the manufacturing difficulty and cost, improves the market competitiveness of the product, and provides strong support for the further development and application of the two-stage screw compressor.

[0074] The embodiment of the present application further provides an air conditioner, which includes the above-mentioned two-stage screw compressor and can achieve all the effects of the foregoing two-stage screw compressor, and details are not described herein again.

[0075] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "include", "comprise", "contain", and "have" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the particular order described or illustrated, unless the order of performance is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0076] Although the terms first, second, third, etc. may be used in this document to describe multiple elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or section from another. Unless the context clearly indicates otherwise, terms such as "first" and "second" and other numerical terms used herein do not imply an order or sequence. Thus, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the teachings of the example embodiments.

[0077] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A gear transmission device, characterized in that: The gear transmission device comprises: Low pressure stage rotor; High pressure stage rotor; A coupling, the coupling being coaxially connected between the low-pressure stage rotor and the high-pressure stage rotor; an adjusting gear assembly, located on the same side of the low-pressure stage rotor, the high-pressure stage rotor and the coupling, the adjusting gear assembly comprising a first adjusting gear and a second adjusting gear coaxially driven with the first adjusting gear, the first adjusting gear meshing with the outer periphery of the low-pressure stage rotor for transmission; Under refrigeration conditions, the low-pressure stage rotor and the high-pressure stage rotor are coaxially driven through the coupling, and the second adjusting gear is configured to idle; Under heating conditions, the coupling is disengaged from the low-pressure stage rotor, the coupling is kept in meshing transmission with the high-pressure stage rotor, and the second adjusting gear is configured to be in meshing transmission with the outer periphery of the coupling.

2. The gear transmission device according to claim 1, characterized in that: The coupling includes a first end shaft and a second end shaft. Under the refrigeration condition, the first end shaft extends into the first inner cavity of the low-pressure stage rotor and is meshed and driven with the first inner cavity of the low-pressure stage rotor. The second end shaft extends into the second inner cavity of the high-pressure stage rotor and is meshed and driven with the second inner cavity of the high-pressure stage rotor.

3. The gear transmission device according to claim 2, characterized in that: The second inner cavity of the high-pressure stage rotor includes a second meshing section and a second cavity section connected to the second meshing section, the second meshing section is used for meshing transmission with the second end shaft of the coupling, and the second cavity section has a piston mechanism, and the piston mechanism is used to push the coupling to move toward the direction of the low-pressure stage rotor.

4. The gear transmission device according to claim 2, characterized in that: The first inner cavity of the low-pressure stage rotor includes a first meshing section and a first cavity section connected to the first meshing section, the first meshing section is used for meshing transmission with the first end shaft of the coupling, the first cavity section has a thrust member, and the thrust member is used to limit the maximum displacement of the coupling toward the low-pressure stage rotor.

5. The gear transmission device according to claim 4, characterized in that: The shaft end of the low-pressure stage rotor has a first toothed shaft section; the coupling has a third toothed shaft section on the periphery; the first adjusting gear and the second adjusting gear in the adjusting gear assembly are coaxial and spaced apart, and the first adjusting gear is meshed with the first toothed shaft section for transmission; Under the heating condition, the coupling moves to the second adjusting gear position and meshes with the second adjusting gear, and the first meshing section of the first inner cavity in the low-pressure stage rotor disengages from the first end shaft in the coupling.

6. The gear transmission device according to claim 1, characterized in that: The number of teeth of the second adjusting gear is smaller than the number of teeth of the first adjusting gear.

7. The gear transmission device according to claim 5, characterized in that: The number of teeth of the first toothed shaft segment is smaller than the number of teeth of the third toothed shaft segment.

8. The gear transmission device according to claim 1, characterized in that: The meshing structures used in each meshing transmission position all adopt a spline structure.

9. A two-stage screw compressor, characterized in that: It comprises the gear transmission device as claimed in any one of claims 1 to 8.

10. An air conditioner, characterized in that: Comprising the two-stage screw compressor as claimed in claim 9.

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