Two-stage compressor and air conditioning system

Abstract

The utility model provides a two-stage compressor and an air conditioning system. The two-stage compressor comprises a motor, a first impeller and a second impeller, and the motor is used for driving the first impeller and the second impeller to rotate; the motor comprises a casing, a stator component, a first bearing seat, a second bearing seat, a motor shaft and a rotor component, the stator component is fixed on the casing; the first bearing seat is fixed at one end of the shell; the second bearing seat is fixed at the other end of the shell; one end of the motor shaft is rotatably arranged on the first bearing seat through a first bearing; the other end of the motor shaft is rotatably arranged on a second bearing seat through a second bearing; wherein one end of the motor shaft is connected with the first impeller, and the other end of the motor shaft is connected with the second impeller; the rotor part is fixed on the motor shaft; wherein the casing is provided with an annular groove, and the annular groove is used for accommodating refrigerant liquid, so that the stator component and / or the rotor component are / is cooled through the refrigerant liquid.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a dual-stage compressor and an air conditioning system, and belongs to the technical field of air conditioning. BACKGROUND

[0002] Heat pump systems are widely used in waste heat recovery in production and life, and are of great significance for energy saving and emission reduction. Generally, a heat pump system uses a compressor to increase the temperature and pressure of refrigerant gas generated by heat exchange with waste heat. The high-temperature and high-pressure refrigerant exchanges heat with water on the use side to generate high-temperature water, thereby meeting the demand for high-temperature water in production and life. Compared with ordinary electric heating, the heat pump system can save up to 80% of electricity. In order to further improve the energy saving effect, the compressor is driven by a variable frequency high-speed permanent magnet motor. In order to avoid refrigerant leakage, the compressor generally adopts a closed structure.

[0003] The compressor of the prior art generally includes a high-speed permanent magnet motor and an impeller, the high-speed permanent magnet motor is centrally arranged, and compressor impellers are arranged on both sides of the high-speed permanent magnet motor. The motor rotor component is supported by bearings on both sides, and the bearings not only support the weight of the rotor component, but also bear the axial force generated by the compressor impeller. In the high-speed permanent magnet motor, oil bearings, magnetic suspension bearings and gas suspension bearings are generally used. In high evaporation and high condensation conditions, the prior art cannot effectively reduce the temperature in the motor inner cavity, resulting in failure of the compressor. CONTENT OF THE UTILITY MODEL

[0004] The present disclosure provides a dual-stage compressor and an air conditioning system.

[0005] According to one aspect of the present disclosure, a dual-stage compressor is provided, which includes a motor, a first impeller and a second impeller, wherein the motor is used to drive the first impeller and the second impeller to rotate, and the motor includes:

[0006] a casing;

[0007] a stator component fixed to the casing;

[0008] a first bearing seat fixed to one end of the casing;

[0009] a second bearing seat fixed to the other end of the casing;

[0010] a motor shaft, one end of the motor shaft is rotatably arranged in the first bearing seat through a first bearing, the other end of the motor shaft is rotatably arranged in the second bearing seat through a second bearing, wherein one end of the motor shaft is connected to the first impeller, and the other end of the motor shaft is connected to the second impeller; and

[0011] a rotor component fixed to the motor shaft;

[0012] The housing is provided with an annular groove for accommodating refrigerant liquid to cool the stator component and / or the rotor component by the refrigerant liquid.

[0013] According to one embodiment of the present disclosure, the annular groove is located at a middle position in the axial direction of the housing.

[0014] According to one embodiment of the present disclosure, a through hole is formed in a side wall of the annular groove, and the refrigerant liquid can flow to the outside of the annular groove through the through hole.

[0015] According to one embodiment of the present disclosure, a first accommodation space is formed between one side wall part of the annular groove and the first bearing seat, and a second accommodation space is formed between the other side wall part of the annular groove and the second bearing seat, and the refrigerant liquid can be stored in the first and second accommodation spaces.

[0016] According to one embodiment of the present disclosure, the two ends of the stator component can respectively extend into the first and second accommodation spaces and contact the refrigerant liquid in the first and second accommodation spaces.

[0017] According to one embodiment of the present disclosure, the first bearing seat and / or the second bearing seat is cooled by cold source water.

[0018] According to one embodiment of the present disclosure, the first bearing seat is formed with an annular accommodation cavity, which is respectively communicated with a cold source water inlet and a cold source water outlet, the cold source water inlet is used to provide cold source water into the annular accommodation cavity, and the cold source water outlet is used to discharge the cold source water in the annular accommodation cavity to the outside of the motor; and / or, the second bearing seat is formed with an annular accommodation cavity, which is respectively communicated with a cold source water inlet and a cold source water outlet, the cold source water inlet is used to provide cold source water into the annular accommodation cavity, and the cold source water outlet is used to discharge the cold source water in the annular accommodation cavity to the outside of the motor.

[0019] According to one embodiment of the present disclosure, a groove is formed on the first bearing seat and opens towards the inside of the motor, the groove is covered by a baffle, and the annular accommodation cavity is formed.

[0020] According to one embodiment of the present disclosure, a groove is formed on the second bearing seat and opens towards the inside of the motor, the groove is covered by a baffle, and the annular accommodation cavity is formed.

[0021] According to another aspect of the present disclosure, an air conditioning system is provided, which comprises the above-mentioned two-stage compressor. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the principles of the disclosure.

[0023] Figure 1 is a structural schematic diagram of an air conditioning system according to one embodiment of the disclosure.

[0024] Figure 2 is a structural schematic diagram of an air conditioning system according to another embodiment of the disclosure.

[0025] Figure 3 is a structural schematic diagram of a two-stage compressor according to one embodiment of the disclosure.

[0026] The reference numerals in the drawings are specifically as follows:

[0027] 100 two-stage compressor

[0028] 110 motor

[0029] 111 casing

[0030] 112 first bearing seat

[0031] 113 second bearing seat

[0032] 114 motor shaft

[0033] 115 rotor component

[0034] 116 stator component

[0035] 117 baffle

[0036] 120 first impeller

[0037] 130 second impeller

[0038] 140 first volute

[0039] 150 second volute

[0040] 200 first condenser

[0041] 300 evaporator

[0042] 400 liquid storage tank

[0043] 500 first pump

[0044] 600 second condenser

[0045] 610 first on-off valve

[0046] 620 second pump

[0047] 630 second on-off valve

[0048] 700 supply tank

[0049] 710 third on-off valve

[0050] 720 third pump

[0051] 740 fourth on-off valve. DETAILED DESCRIPTION

[0052] The present disclosure will be described in further detail below with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are illustrative of specific aspects of the present disclosure and are not intended to limit the scope of the present disclosure. In addition, it is to be understood that the specific embodiments described herein are only examples and that the present disclosure is not limited to these specific embodiments.

[0053] It should be noted that the embodiments and features of the embodiments in the present disclosure can be combined with each other without conflict. The technical solutions of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0054] Unless otherwise specified, the exemplary embodiments / examples shown will be understood as providing exemplary features of various details that can implement the technical concepts of the present disclosure in practice. Therefore, unless otherwise specified, the features of various embodiments / examples can be additionally combined, separated, interchanged and / or rearranged without departing from the technical concepts of the present disclosure.

[0055] In the drawings, cross-hatching and / or shading are generally used to make the boundaries and regions of adjacent components clear. Thus, unless otherwise specified, the presence or absence of cross-hatching or shading does not convey or imply any preference or requirement for a specific material, material property, size, scale, commonality of the illustrated components, and / or any other characteristic, attribute, property, etc. of the components. In addition, in the drawings, the size and relative sizes of components can be exaggerated for clarity and / or descriptive purposes. When exemplary embodiments can be implemented differently, a specific process sequence can be performed in a different order than described. For example, two consecutively described processes can be performed substantially simultaneously or in an order opposite to that described. In addition, the same reference numbers represent the same components.

[0056] When a component is referred to as being "on", "connected to", or "coupled to" another component, it can be directly on, connected, or coupled to the other component, or intervening components can be present. When a component is referred to as being "directly on", "directly connected to", or "directly coupled to" another component, there are no intervening components present. By contrast, when a component is referred to as being "indirectly on", "indirectly connected to", or "indirectly coupled to" another component, there are one or more intervening components present. In this context, the term "coupled" can refer to physical, electrical, and / or the like, connections, with or without intervening components.

[0057] For descriptive purposes, the disclosure can use spatial or relative terms, such as "below", "lower", "lowermost", "above", "upper" and "uppermost", "vertical", "horizontal", and the like, to describe the relationship between one component and another component as the figure(s) can appear. The spatial and / or relative terms can also be used to describe the orientation of the device during use, operation, and / or manufacture in addition to the orientation depicted in the figures. For example, if the device in the figure is turned over, a component described as "below" or "under" another component would then be oriented "above" the other component. Thus, the exemplary term "below" can encompass both an orientation of above and below. Moreover, the device can be oriented in another way (e.g., rotated 90 degrees or at another orientation), and the spatially relative descriptions used herein are interpreted accordingly.

[0058] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "including", "includes", "having", "has", "united", "unites", "containing", "contains" and variants are used in either the detailed description and / or the claims, such terms are intended to be inclusive in a manner similar to the term "comprising" as an open transition term without precluding any additional or other elements. It is also noted that, as used herein, the terms "substantially", "approximately" and other similar terms are used as synonyms for "about", so that the term "substantially", "approximately", and other like terms have the same meaning as "about".

[0059] Figure 1 is a structural schematic of an air conditioning system according to one embodiment of the disclosure.

[0060] As Figure 1 shown, the air conditioning system of the disclosure can include a two-stage compressor 100, a first condenser 200, an evaporator 300, a liquid accumulator 400, a first pump 500, and a second condenser 600, etc.

[0061] The two-stage compressor 100 comprises a first-stage compressor and a second-stage compressor; wherein the first-stage compressor is configured to receive the refrigerant gas discharged from the evaporator 300 and to compress the refrigerant gas in a first stage. The refrigerant gas compressed in the first stage enters the second-stage compressor and is further compressed by the second-stage compressor to obtain high-temperature and high-pressure refrigerant gas.

[0062] The first condenser 200 is connected to the second-stage compressor and is configured to condense at least part of the high-temperature and high-pressure refrigerant gas discharged from the second-stage compressor into refrigerant liquid. In a preferred embodiment, the first condenser 200 is also configured to receive service water, and the temperature of the service water is increased after the service water flows through the first condenser 200.

[0063] In other words, the service water and the refrigerant can exchange heat in the first condenser 200, so that the heat released when the high-temperature and high-pressure refrigerant gas is converted into refrigerant liquid can be used to heat the service water, and the temperature of the service water can be increased from about 70° to above 75°, so that the heat in the service water can be recycled to save energy.

[0064] The evaporator 300 is connected to the first condenser 200 via an expansion valve, and the evaporator 300 is also connected to the first-stage compressor. The evaporator 300 is configured to convert the refrigerant liquid into refrigerant gas, and the refrigerant gas discharged from the evaporator 300 is delivered to the first-stage compressor.

[0065] Specifically, after the high-temperature refrigerant liquid flows out of the first condenser 200, part of the refrigerant liquid is converted into refrigerant gas by the expansion effect of the expansion valve, and at this time, the high-temperature refrigerant liquid will become a mixture of low-temperature refrigerant liquid and refrigerant gas.

[0066] The mixture of low-temperature refrigerant liquid and refrigerant gas enters the evaporator 300 and is evaporated by the evaporator 300 to provide cold energy outside the evaporator 300.

[0067] In a preferred embodiment, the evaporator 300 is also configured to receive heat source water, and the temperature of the heat source water is decreased after the heat source water flows through the evaporator 300. In other words, the evaporator 300 of the present disclosure can recycle the heat in the heat source water while providing cold energy. For example, the temperature of the heat source water entering the evaporator 300 is about 50°C, and the temperature of the heat source water flowing out of the evaporator 300 can be reduced to below 45°C, so that the heat in the heat source water (low-temperature hot water) can be utilized.

[0068] The liquid storage tank 400 of the present disclosure is used to store refrigerant liquid; the refrigerant liquid can be used for cooling the motor of the two-stage compressor. In other words, in the air conditioning system of the present disclosure, the motor can be cooled by the independent circuit due to the provision of the liquid storage tank 400, thereby improving the cooling effect of the motor.

[0069] Specifically, compared with the prior art scheme of providing refrigerant liquid to the motor from the condenser or the economizer, the temperature of the motor of the present disclosure can be further reduced.

[0070] For example, the motor temperature in the prior art is generally about 110°C, and the motor temperature of the present disclosure is below 80°C, thereby improving the service life of the motor.

[0071] The first pump 500 is connected to the liquid storage tank 400 and the motor of the two-stage compressor 100, and is used to provide the refrigerant liquid in the liquid storage tank 400 to the motor of the two-stage compressor 100; specifically, the first pump 500 of the present disclosure can provide the refrigerant liquid into the inner cavity of the motor of the two-stage compressor 100, at which time the refrigerant liquid can cool the stator components and rotor components of the motor and the like.

[0072] The second condenser 600 of the present disclosure is connected to the motor of the two-stage compressor 100 and the liquid storage tank 400, and is used to receive the refrigerant liquid and / or refrigerant gas discharged from the motor of the two-stage compressor 100, and condense the refrigerant gas discharged from the motor into refrigerant liquid, and provide the refrigerant liquid to the liquid storage tank 400.

[0073] That is, after the refrigerant liquid is provided into the inner cavity of the motor, it can cool the stator components and rotor components of the motor. At this time, at least part of the refrigerant liquid will be converted into refrigerant gas. In addition, there can also be a case where part of the refrigerant liquid is not converted into refrigerant gas, and the mixture of refrigerant gas and refrigerant liquid will be discharged from the inner cavity of the motor to the second condenser 600.

[0074] The second condenser 600 is also used to receive cold condensed water with a lower temperature, so as to quickly cool and liquefy the mixture of refrigerant liquid and refrigerant gas, thereby forming an independent path for cooling the motor.

[0075] In the present disclosure, the liquid storage tank 400 and the second condenser are located at the bottom of the evaporator 300, and the liquid storage tank 400 is provided with a liquid level gauge, which can be used to detect whether the height of the refrigerant liquid in the liquid storage tank 400 meets the requirements. If the refrigerant liquid in the liquid storage tank 400 is less, part of the refrigerant liquid can be taken out from the evaporator 300 and supplemented to the liquid storage tank 400.

[0076] Specifically, the evaporator 300 is connected to the inlet side of the first pump 500 through a first pipeline, wherein the first pipeline is provided with a first switch valve 610. In a preferred embodiment, the first switch valve 610 can be a ball valve. When the first switch valve 610 is opened and the cold source water flows through the second condenser, the refrigerant liquid in the evaporator 300 will flow to the storage tank 400 to a set liquid level under the action of gravity and / or pressure difference between the evaporator and the second condenser, at which time the first switch valve 610 is closed.

[0077] Considering that the motor is connected at both ends with an impeller in which high-temperature and high-pressure refrigerant gas flows, part of these refrigerant gases will pass through the sealing structure of the motor and flow into the inner cavity of the motor. Therefore, after the dual-stage compressor works for a long time, the refrigerant liquid in the storage tank 400 will increase, at which time these liquids need to be discharged.

[0078] Specifically, when the liquid level meter detects that there is more refrigerant liquid in the storage tank 400, the refrigerant liquid in the storage tank 400 can be discharged to the evaporator 300. At this time, the storage tank 400 is also connected to the evaporator 300 through a second pipeline, wherein the second pipeline is provided with a second pump 620 and a second switch valve 630. Therefore, when the second pump 620 is in a working state and the second switch valve 630 is in an open state, the second pump 620 can extract the refrigerant liquid from the storage tank 400 and deliver the refrigerant liquid to the evaporator 300 after pressurizing the refrigerant liquid.

[0079] Figure 2 is a structural schematic diagram of an air conditioning system according to another embodiment of the present disclosure.

[0080] As Figure 2 shown, the air conditioning system of the present disclosure further comprises a supply tank 700 for storing refrigerant liquid, the supply tank 700 being connected to the storage tank 400 through a third pipeline, wherein the third pipeline is provided with a third switch valve 710 and a third pump 720; wherein the supply tank 700 is used to provide refrigerant liquid to the bearing of the motor of the dual-stage compressor 100.

[0081] At this time, the bearing of the motor is an air floating bearing, and accordingly, the refrigerant liquid provided to the bearing supports the motor shaft on one hand and cools the bearing on the other hand.

[0082] The refrigerant liquid supplied to the bearing of the motor of the two-stage compressor 100 flows through the bearing of the motor, enters the motor cavity, and is discharged to the second condenser 600; that is, the motor of the two-stage compressor 100 of the present disclosure has only one outlet for refrigerant liquid / refrigerant gas, at this time, the refrigerant liquid and / or refrigerant gas flowing through the bearing can enter the motor cavity, flow out to the outside of the motor through the hole opened on the motor casing, and further flow to the second condenser 600.

[0083] In other words, the refrigerant liquid in the liquid storage tank 400 of the present disclosure can be pumped to the supply tank 700 through the third pump 720; the supply tank 700 can be connected to the bearing of the motor through the fourth pipeline, and the fourth pipeline can be provided with a fourth switch valve 740, which can be a ball valve, so that when the third pump 720 is in working state and the third switch valve 710 and the fourth switch valve 740 are in open state, the supply tank 700 can supply refrigerant liquid to the bearing of the motor.

[0084] In addition, the supply tank 700 can be provided with an electric heater and a temperature sensor, at this time, when the third pump 720 is in non-working state and the third switch valve 710 is in closed state, the refrigerant liquid in the supply tank 700 can be heated by the electric heater, and at least part of the refrigerant liquid is converted into refrigerant gas, at this time, the pressure in the supply tank 700 will increase, and the refrigerant liquid will be delivered to the bearing of the motor through the pressure.

[0085] At this time, when the refrigerant liquid in the supply tank 700 is less, the third pump 720 can be controlled to be in working state and the third switch valve 710 can be controlled to be open, so that the refrigerant liquid can be supplemented into the supply tank 700.

[0086] Figure 3 is a structural schematic diagram of a two-stage compressor according to an embodiment of the present disclosure.

[0087] As Figure 3As shown, the two-stage compressor 100 of this disclosure includes a motor 110 and a first impeller 120 and a second impeller 130 driven by the motor 110. The motor 110 includes a housing 111, which has a cylindrical structure, with a first bearing seat 112 and a second bearing seat 113 fixed at both ends. One end of the motor shaft 114 of the motor 110 is rotatably mounted on the first bearing seat 112 via the first bearing, and similarly, the other end of the motor shaft 114 is rotatably mounted on the second bearing seat 113 via the second bearing. The first and second bearings can be any type of oilless bearing. In a specific embodiment, the first and second bearings can be air bearings, and one of the first and second bearings can be radial-axial, while the other of the first and second bearings can be a composite bearing of a radial bearing and a thrust bearing.

[0088] Specifically, the housing 111 of this disclosure and the first bearing seat 112 and the second bearing seat 113 provided at both ends of the housing 111 can form the inner cavity of the motor. At this time, the stator component and rotor component of the motor are all provided in the inner cavity of the motor.

[0089] In this disclosure, a rotor component 115 is mounted on the motor shaft 114, and a stator component 116 is fixed on the housing 111. Specifically, an annular groove is provided on the inner wall of the housing 111, and along the axial direction of the motor 110, the annular groove is located approximately at the middle of the rotor component 115. The stator component 116 can be fixed to the housing 111 and at least partially covers the annular groove. More preferably, a through hole is provided on the side wall of the annular groove, thereby allowing refrigerant liquid to flow through the through hole to the outside of the annular groove and further to the rotor component 115.

[0090] Furthermore, a first receiving space is formed between one sidewall portion forming the annular groove and the first bearing housing 112, and a second receiving space is formed between the other sidewall portion forming the annular groove and the second bearing housing. In other words, a first receiving space and a second receiving space are formed on both sides of the annular groove, respectively. Refrigerant liquid can be stored in both the first and second receiving spaces, and both ends of the stator component 116 can extend into the first and second receiving spaces, respectively, and contact the refrigerant liquid within them.

[0091] The housing 111 of this disclosure has a refrigerant inlet that can communicate with an annular groove, thereby enabling the supply of liquid refrigerant to the annular groove. Although Figure 3 Although not shown, those skilled in the art should know that the housing 111 has a refrigerant outlet that can be connected to the second condenser 600.

[0092] In a preferred embodiment, the refrigerant outlet is in communication with the second containing space, so that the liquid in the first containing space will flow into the second containing space and be discharged through the refrigerant outlet. Specifically, a plurality of flow channels can be formed on the stator component 116, through which the refrigerant liquid will flow from the first containing space to the second containing space and then be discharged from the motor. Accordingly, the flow process of the refrigerant liquid can cool the core and the enameled wire of the stator component, thereby reducing the temperature of the stator component of the motor.

[0093] The first bearing seat 112 and the second bearing seat 113 of the present disclosure can be cooled by the cold source water. Specifically, the first bearing seat 112 and the second bearing seat 113 are each formed with an annular containing cavity in communication with a cold source water inlet and a cold source water outlet, the cold source water inlet being configured to supply the cold source water into the annular containing cavity, and the cold source water outlet being configured to discharge the cold source water in the annular containing cavity to the outside of the motor.

[0094] In a specific embodiment, the annular containing cavities of the first bearing seat 112 and the second bearing seat 113 are formed in the same way. For example, the first bearing seat 112 is formed with a groove opening towards the inside of the motor, the groove being covered by the baffle 117 and thereby forming the annular containing cavity. At this time, the baffle 117 can be formed as at least part of the side wall of the first containing space or the second containing space.

[0095] The first volute 140 is fixed to the first bearing seat 112 and is configured to contain the first impeller; similarly, the second volute 150 is fixed to the second bearing seat 113 and is configured to contain the second impeller.

[0096] Based on the above structure, the motor of the air conditioning system of the present disclosure is independently cooled, so that the temperature in the motor cavity is independent of the residual heat and the temperature on the use side, ensuring that the motor operates at a lower temperature, avoiding demagnetization of the permanent magnet of the rotor component and the magnetic bearing, and high-temperature aging of the winding insulation material. Moreover, the air conditioning system can also improve the circulation efficiency of the heat pump system by more than 6%.

[0097] In the prior art, the motor is generally provided with refrigerant liquid through a condenser or an economizer, at this time, the temperature in the motor cavity corresponds to the saturation pressure in the cavity, which is equal to the saturation pressure in the evaporator plus the pressure loss of the pipeline from the motor cavity to the evaporator. Under high evaporation and high condensation conditions, the suction gas density and the compression ratio increase, the power consumption and heat generation of the motor increase sharply, the temperature in the motor cavity exceeds 80℃, and the temperature of the motor winding can reach 120~140℃, which is much higher than the 100~110℃ under normal conditions, causing the risk of aging of the insulation material and demagnetization of the permanent magnet of the rotor component and the magnetic bearing of the permanent magnet motor. To solve this technical problem, the existing solution is to replace the permanent magnet material, but this will increase the cost and weaken the competitiveness of the product.

[0098] On the other hand, as the temperature of the water used on the side rises, the curvature of the two-phase line of the working medium changes, and under the same pressure rise (although the pressure ratio decreases), a large amount of refrigerant liquid is gasified by the expansion valve, and only a part of the low-temperature liquid is used for cooling of the motor. If the cooling effect of the motor is to be ensured, a large amount of liquid needs to be led out from the condenser. The compressor needs to re-compress the gas that has no heat exchange capacity, consuming a large amount of compression power and seriously reducing the energy efficiency of the system. Using an economizer and leading out the motor cooling liquid from the economizer not only improves the circulation efficiency of the system, but also reduces the amount of cooling liquid, but this cannot solve the cooling problem of the motor when the temperature of the waste heat source rises.

[0099] Therefore, under high evaporation and high condensation conditions, how to reduce the temperature in the motor cavity while improving the circulation efficiency of the heat pump system is a bottleneck problem in the application of high-temperature heat pumps.

[0100] Compared with the prior art, that is, compared with the scheme of providing refrigerant liquid to the motor through the condenser or the economizer, the air conditioning system of the present disclosure can solve the cooling problem of the motor under high evaporation and high condensation conditions, control the temperature of the motor winding and the permanent magnet below 80°C (H-level insulation safety range), provide a reliable thermal management solution for the compressor, and at the same time improve the circulation efficiency of the high-temperature heat pump system.

[0101] In other words, the refrigerant liquid provided to the motor can be supercooled working liquid, so that the superheated gas in the motor cavity can be condensed by the supercooled working liquid, and the generated saturated liquid is cooled in the second condenser using an external cold source to produce supercooled working liquid, which is further improved in supercooling degree after being pressurized by the first pump.

[0102] In the present disclosure, the second condenser can be a liquid-liquid heat exchanger, and the external cold source exchanges heat with the saturated liquid working medium discharged from the motor, thereby reducing the temperature of the working liquid. The saturation temperature of the second condenser determines the temperature of the motor cavity, and the lower the temperature of the external cold source, the lower the temperature of the motor cavity. The temperature of the external cold source must be lower than the temperature of the waste heat source water. Thus, the air conditioning system of the present disclosure realizes the decoupling of the temperature of the motor cavity and the evaporation and condensation temperatures of the heat pump system.

[0103] The liquid storage tank of the present disclosure is used to store liquid working medium (i.e. refrigerant liquid) and provide liquid for the inlets of the first pump, the second pump and the third pump. In an optional embodiment, the liquid storage tank can be a liquid pocket at the bottom of the second condenser.

[0104] The first pump is used to increase the pressure of the liquid working medium, overcome the pressure loss of the cooling cycle, deliver the low-temperature working medium to the motor cavity, and further increase the supercooling degree of the working medium. In a preferred embodiment, the first pump can be a variable frequency pump, which can control the speed according to the temperature of the motor cavity, and when the temperature in the motor cavity is higher than the set value, the speed is increased, and vice versa. When the first pump is a fixed frequency pump, the cold source water pump that provides cold source water to the second condenser is a variable frequency pump, which also controls the speed according to the temperature of the motor cavity.

[0105] Based on the above structure, unlike the prior art which can only condense the motor temperature to about 110°C, which is not suitable for high evaporation and high condensation conditions, the air conditioning system of the present disclosure can use supercooled liquid to condense the superheated gas in the motor cavity to achieve motor cooling, thereby controlling the motor temperature at 80°C, and the temperature of the motor cavity is independent of the working condition of the heat pump (i.e. the first condenser and the evaporator).

[0106] In other words, the prior art uses high-temperature and high-pressure working medium liquid to produce gas and liquid after expansion valve pressure reduction, and its temperature is the saturation temperature in the motor cavity, i.e. using saturated liquid to cool the superheated gas in the motor cavity; but in the air conditioning system of the present disclosure, the temperature in the motor cavity can be effectively reduced through an independent cooling circuit.

[0107] The method of using high-temperature and high-pressure working medium liquid to reduce pressure and temperature through an expansion valve in the prior art needs to extract a large amount of refrigerant from the condenser for motor cooling, and this part of working medium is sucked into the compressor and compressed after heat exchange and gasification in the motor cavity, increasing the compressor power consumption. The air conditioning system of the present disclosure avoids the increase of compressor power consumption caused by compressed cooling gas working medium, at least improves the heat cycle efficiency by 6 percentage points, and with the increase of heat pump temperature rise, the heat cycle efficiency is improved more obviously, thus the present disclosure has higher heat cycle efficiency.

[0108] Moreover, the present scheme can cool the bearing, thereby providing a technical path for applying magnetic suspension and gas suspension bearings to high-temperature heat pump systems.

[0109] As shown in the scheme of Figure 1 , a magnetic suspension bearing is used. The following table compares the cycle efficiency COP of the present scheme and the prior art, ignoring bearing loss and pipeline loss, compressor suction superheat and condenser supercooling are both assumed to be 0, and water pump loss is not included in the COP calculation process.

[0110]

[0111] The cooling circulation loop working fluid pumps (i.e., the first pump, the second pump, and the third pump) of this disclosure require a small amount of power, which can be ignored. The calculations of existing solutions have not undergone iteration; they only consider the increased compressor flow and compression power consumption due to the increased working fluid cooling for the motor. Calculations show that, under a temperature rise of 40°C, regardless of the refrigerant used, this solution improves the COP of the heat pump system by more than 6%, and under a temperature rise of 60°C, this disclosure improves the COP by more than 14%.

[0112] like Figure 2 The scheme shown employs a static pressure air bearing in the two-stage compressor, and the inlet of the third pump is a subcooled liquid, which effectively avoids damage to the static pressure air bearing caused by supplying gas to it.

[0113] like Figure 3 When the motor is operating, the working fluid (i.e., liquid refrigerant) is pressurized by the first pump and enters the annular groove from the bottom of the housing 111. The working fluid rises uniformly within the annular groove until it fills the entire groove. As the working fluid flows through the stator core area, it absorbs the heat generated by electromagnetic induction (including eddy current losses and hysteresis losses) by contacting the core surface. When the working fluid rises to the top of the core, it forms a jet with a certain velocity through the through-holes on the sidewall of the annular groove, directly impacting the enameled wire windings at the upper ends of the motor. The jet covers the winding surface, rapidly carrying away the heat from the copper wires through forced convection. The enameled wires at the bottom of the motor are completely immersed in the liquid working fluid in the first and second containment spaces, achieving efficient heat conduction to remove the copper-loss heat through direct contact between the working fluid and the windings.

[0114] When cooling the motor rotor components, the saturated cryogenic working fluid (gas and / or liquid) diffuses uniformly under the geometric constraints of the housing, forming a continuous gas film layer surrounding the outer edge of the rotor components. The initial temperature of the working fluid is lower than the surface temperature of the rotor components, creating initial heat transfer potential energy. The cryogenic working fluid gas contacts the surface of the high-speed rotating rotor components, absorbing electromagnetic and mechanical heat through forced convection. Electromagnetic heat is conducted to the outer surface through the rotor component sheath (non-magnetic material) due to eddy current losses in the permanent magnets, while mechanical heat is generated by viscous shear heat generated by friction between the rotor component surface and the working fluid gas. After absorbing heat, the cryogenic working fluid's temperature rises and its density decreases, migrating towards the top of the cavity under the action of buoyancy, and simultaneously accelerating away from the rotor component surface with the assistance of centrifugal force from the rotor component's rotation. At the same time, in the first and second accommodating spaces at the bottom of the housing, the supercooled (or saturated) liquid working fluid, after heat exchange with the windings, transforms into saturated (cryogenic) gas and is continuously replenished, forming a dynamic convection circulation from bottom to top around the rotor components. The spray nozzle at the top of the housing uniformly sprays the supercooled liquid working fluid downwards. The falling supercooled liquid working fluid mixes with the rising high-temperature gas in the upper part of the casing, resulting in sensible heat exchange. The high-temperature gas releases heat to the liquid working fluid, causing its temperature to drop to saturation. The low-temperature liquid working fluid absorbs heat and partially vaporizes. This process maintains the phase equilibrium of the working fluid in the system.

[0115] The mixed saturated working medium after cooling of the stator component and the rotor component is collected in the first containing space and the second containing space at the bottom of the casing, and enters the external condenser through the liquid discharge port. At this time, the liquid discharge port can communicate with the first containing space and / or the second containing space.

[0116] Through condensation heat exchange cooling, the condensed working medium is re-injected into the "supercooled working medium inlet" after being pressurized by a pump, forming a closed cycle.

[0117] Referring again to Figure 3 , the heat insulation air cavity is used to cut off the direct heat conduction of the first volute (volute) and the second volute (volute) and the bearing seat, and blocks most of the above radiation heat and conduction heat outside the air cavity. When the residual heat is conducted through the bearing seat metal, it is continuously absorbed by the internal water cooling channel, and finally taken out of the system by the cold source water.

[0118] In the annular space between the volute (in contact with the high-temperature working medium), the bearing seat and the casing (motor end surface), a sealed heat insulation air cavity is arranged. The air cavity is filled with inert gas (or working medium), which uses the low thermal conductivity of gas (only 1 / 100~1 / 1000 of metal material) to block the heat conduction path of the high-temperature working medium through the volute (i.e. high-temperature working medium→volute metal wall→bearing seat→casing), that is, to block the transfer of high-temperature working medium to the inside of the machine cavity. A spiral or serpentine cooling channel is processed inside the bearing seat (a key component connecting the volute and the rotor component), and the cold source water is injected from the "cold source water inlet" and flows along the channel closely adhering to the inner wall of the bearing seat. The channel wall directly contacts the bearing seat metal, and the cold source water continuously absorbs the heat of the high-temperature working medium transferred to the bearing seat through forced convection (conduction path: high-temperature working medium→volute→bearing seat→cooling water). At the same time, the channel is arranged near the bearing mounting position, and the cold source water synchronously absorbs the heat generated by the gas friction when the bearing and the rotor component rotate at high speed (friction heat→bearing seat→cooling water).

[0119] In the description of the present specification, the description of the terms "one embodiment / way", "some embodiments / ways", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments / ways or examples in a suitable manner. In addition, the skilled in the art can combine and combine the different embodiments / ways or examples described in the present specification and the features of the different embodiments / ways or examples without contradiction.

[0120] Furthermore, the terms "first", "second", etc. are used herein for descriptive purposes only and should not be construed as indicating or implying relative importance or an ordered ranking such that the technical features so designated should possess. Thus, features having a "first", "second", etc. designation can implicitly or explicitly include at least one of the features. In the description of the application, the meaning of "a plurality" is at least two, for example two, three or the like, unless expressly specified otherwise.

[0121] Those skilled in the art will understand that the above-described embodiments are merely intended to clarify the present disclosure and are not intended to limit the scope of the present disclosure. Other changes or modifications can be made by those skilled in the art based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A two-stage compressor comprising a motor, a first impeller and a second impeller, wherein, The motor is used to drive the first and second impellers to rotate, characterized in that the motor comprises: a casing; a stator component fixed to the casing; a first bearing seat fixed to one end of the casing; a second bearing seat fixed to the other end of the casing; a motor shaft, one end of which is rotatably arranged in the first bearing seat through a first bearing, and the other end of which is rotatably arranged in the second bearing seat through a second bearing, wherein the one end of the motor shaft is connected to the first impeller, and the other end of the motor shaft is connected to the second impeller; and a rotor component fixed to the motor shaft; wherein the casing is provided with an annular groove for accommodating refrigerant liquid to cool the stator component and / or the rotor component through the refrigerant liquid.

2. The two-stage compressor of claim 1, wherein, The annular groove is located at the middle position in the axial direction of the casing.

3. The two-stage compressor of claim 1, wherein, A through hole is formed in the side wall of the annular groove, and the refrigerant liquid can flow to the outside of the annular groove through the through hole.

4. The two-stage compressor of claim 1, wherein, A first accommodating space is formed between one side wall part forming the annular groove and the first bearing seat, and a second accommodating space is formed between the other side wall part forming the annular groove and the second bearing seat, and the refrigerant liquid can be stored in the first and second accommodating spaces.

5. The two-stage compressor of claim 4, wherein, The two ends of the stator component can respectively extend into the first and second accommodating spaces and contact the refrigerant liquid in the first and second accommodating spaces.

6. The two-stage compressor of claim 1, wherein, The first bearing seat and / or the second bearing seat is cooled by cold source water.

7. The two-stage compressor of claim 6, wherein, The first bearing seat is formed with an annular accommodating cavity, which is respectively communicated with a cold source water inlet and a cold source water outlet, the cold source water inlet is used to provide cold source water into the annular accommodating cavity, and the cold source water outlet is used to discharge the cold source water in the annular accommodating cavity to the outside of the motor; and / or, the second bearing seat is formed with an annular accommodating cavity, which is respectively communicated with a cold source water inlet and a cold source water outlet, the cold source water inlet is used to provide cold source water into the annular accommodating cavity, and the cold source water outlet is used to discharge the cold source water in the annular accommodating cavity to the outside of the motor.

8. The two-stage compressor of claim 7, wherein, A groove is formed on the first bearing seat and opens towards the inside of the motor, the groove is covered by a baffle, and the annular accommodating cavity is formed.

9. The two-stage compressor of claim 7, wherein, A groove is formed on the second bearing seat and opens towards the inside of the motor, the groove is covered by a baffle, and the annular accommodating cavity is formed.

10. An air conditioning system characterized by, The double-stage compressor comprises the double-stage compressor according to any one of claims 1-9.

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