Heat pump unit

Abstract

The utility model relates to a heat pump unit which comprises a compressor, a heat exchanger set, a first circulation branch, a second circulation branch and a pressure detection device, the heat exchanger set comprises an evaporator and a condenser, and the evaporator and the condenser are connected with the compressor through a circulation main path; the first circulation branch is connected between the evaporator and the condenser, and an electronic expansion valve is arranged on the first circulation branch; the second circulation branch is connected with the first circulation branch in parallel and is connected between the evaporator and the condenser, and the second circulation branch is provided with a regulating valve and a throttling element; the pressure detection device can detect the pressure difference between the output end of the condenser and the input end of the evaporator, the detected pressure difference is compared with the pressure difference upper limit or the pressure range, real-time adjustment is conducted according to load changes and working condition changes, the performance matching performance of liquid supply adjustment is high, the adjustment precision is high, and stable and efficient operation of the unit is achieved.

Description

Technical Field

[0001] The utility model belongs to the technical field of electrical equipment, and in particular relates to a heat pump unit. Background Art

[0002] The heat pump unit is a circulation system composed of compressor-heat exchanger-throttle-heat absorber-compressor and other devices. The refrigerant circulates in the system under the action of the compressor.

[0003] The heat pump unit has a wide operating range, a large range of variable operating condition adjustment, a large pressure ratio, a large liquid supply volume and other characteristics, which put forward higher requirements for liquid supply regulation. The current mainstream liquid supply regulation scheme is mainly through a large-capacity electronic expansion valve or a combination of multiple electronic expansion valves. A large-capacity electronic expansion valve or a combination of multiple electronic expansion valves has the advantage of high regulation accuracy, but the price of a large-capacity electronic expansion valve or a plurality of electronic expansion valves is high. In particular, the structure of a combination of multiple electronic expansion valves will lead to complex liquid supply pipelines and a corresponding increase in costs. In addition, a throttling orifice plate can also be used in conjunction with an electronic expansion valve. The disadvantage is that the throttling orifice plate cannot be adjusted according to changes in load and operating conditions, and has poor performance matching and poor regulation accuracy. Utility Model Content

[0004] The utility model aims to provide a heat pump unit to solve the problems of high cost of liquid supply regulation, complex pipelines, poor regulation accuracy, etc. of the existing heat pump unit in the prior art.

[0005] In order to achieve the above-mentioned utility model purpose, the utility model adopts the following technical solutions:

[0006] In one aspect, the utility model provides a heat pump unit, comprising:

[0007] compressor;

[0008] A heat exchanger group, comprising an evaporator and a condenser, wherein the evaporator and the condenser are connected to the compressor through a main circulation path;

[0009] a first circulation branch connected between the evaporator and the condenser, wherein an electronic expansion valve is provided on the first circulation branch;

[0010] at least one second circulation branch, which is connected in parallel with the first circulation branch and connected between the evaporator and the condenser, and a regulating valve and a throttling element are provided on the second circulation branch;

[0011] A pressure detection device is configured to detect a pressure difference between the condenser output end and the evaporator input end.

[0012] In some embodiments of the present application, a first switch valve is further provided on the first circulation branch, the first switch valve is located upstream of the electronic expansion valve, and the input end of the second circulation branch is connected upstream of the first switch valve.

[0013] In some embodiments of the present application, a second switch valve is further provided downstream of the electronic expansion valve, and the second switch valve is provided on the main circulation line or the second switch valve is provided on the first circulation branch line.

[0014] In some embodiments of the present application, a drying filter is further provided on the main circulation circuit, and the drying filter is located downstream of the condenser.

[0015] In some embodiments of the present application, the pressure detection device is arranged on the second circulation branch, and includes a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged upstream of the regulating valve, and the second pressure sensor is arranged downstream of the throttling device.

[0016] In some embodiments of the present application, the pressure detection device is arranged on the first circulation branch, and includes a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged upstream of the first switching valve, and the second pressure sensor is arranged downstream of the electronic expansion valve.

[0017] In some embodiments of the present application, the pressure detection device is arranged on the main circulation circuit, and includes a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged downstream of the drying filter, and the second pressure sensor is arranged upstream of the second switch valve.

[0018] In some embodiments of the present application, the throttling element is a throttling orifice plate.

[0019] In some embodiments of the present application, the compressor is a screw heat pump compressor.

[0020] In some embodiments of the present application, the first switch valve and / or the second switch valve is a ball valve.

[0021] On the other hand, the present application also proposes a heat pump unit, which comprises:

[0022] compressor;

[0023] a heat exchanger group, comprising an evaporator and a condenser connected to the compressor via a main circulation path;

[0024] a first circulation branch connected between the evaporator and the condenser, wherein an electronic expansion valve is provided on the first circulation branch;

[0025] at least one second circulation branch connected in parallel with the first circulation branch and between the evaporator and the condenser, wherein a throttling regulating device is provided on the second circulation branch;

[0026] a pressure detection device configured to detect a pressure difference between an output end of the condenser and an input end of the evaporator;

[0027] Wherein, the throttling regulating device is configured to adjust the pressure difference between the condenser output end and the evaporator input end to within a target range.

[0028] Compared with the prior art, the advantages and positive effects of the utility model are:

[0029] The heat pump unit proposed in the present application includes at least one circulation branch, on which a regulating valve and a throttling element are arranged, which cooperate with the electronic expansion valve on the first circulation branch to realize liquid supply regulation. The pressure detection device can detect the pressure difference between the output end of the condenser and the input end of the evaporator, and compare the detected pressure difference with the upper limit of the pressure difference or the pressure range, and adjust the opening of the regulating valve accordingly to realize intelligent regulation. The liquid supply pipeline of the entire heat pump unit is simple and low in cost. Under the real-time detection of the pressure detection device, real-time regulation is carried out according to load changes and operating conditions. The performance matching of the liquid supply regulation is high and the regulation accuracy is high, so as to realize stable and efficient operation of the unit.

[0030] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 is one of the structural schematic diagrams of a heat pump unit according to an embodiment;

[0033] Figure 2 This is one of the schematic diagrams of the installation position of the pressure sensor;

[0034] Figure 3 This is the second schematic diagram of the installation position of the pressure sensor;

[0035] Figure 4 This is one of the schematic diagrams of refrigerant circulation when the regulating valve is closed;

[0036] Figure 5This is one of the schematic diagrams of refrigerant flow when the regulating valve is open;

[0037] Figure 6 This is the second schematic diagram of refrigerant flow when the regulating valve is closed;

[0038] Figure 7 This is a schematic diagram of the refrigerant flow when one of the regulating valves is open;

[0039] Figure 8 This is a schematic diagram of refrigerant flow when all regulating valves are open;

[0040] Fig. 9 A schematic diagram of a heat pump unit adjustment process according to an embodiment;

[0041] Reference numerals:

[0042] 10. compressor; 20. condenser; 30. filter drier;

[0043] 41. First switch valve; 42. Second switch valve;

[0044] 50. Evaporator; 60. Electronic expansion valve; 70. Regulating valve; 80. Throttling element;

[0045] 91. A first pressure sensor; 92. A second pressure sensor;

[0046] 100, main circulation route; 110, first circulation branch route; 120, second circulation branch route. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0050] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0051] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0052] The disclosure below provides many different embodiments or examples for realizing different structures of the utility model. In order to simplify the disclosure of the utility model, the components and settings of specific examples are described below. Of course, they are merely examples, and the purpose is not to limit the utility model. In addition, the utility model may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the utility model provides various specific examples of processes and materials, but those of ordinary skill in the art may be aware of the application of other processes and / or the use of other materials.

[0053] The heat pump unit is a device that can use external low-temperature heat energy to provide heating and heating, and is mainly composed of a compressor 10, an evaporator 50, a condenser 20 and a throttling device.

[0054] Here’s how it works:

[0055] The compressor 10 sucks low-temperature and low-pressure refrigerant, and compresses the refrigerant into high-temperature and high-pressure gas.

[0056] The condenser 20 is arranged at the output end of the compressor 10. The high-temperature and high-pressure gas output by the compressor 10 enters the condenser 20. The condenser 20 condenses the compressed refrigerant into a liquid phase, and the heat is released to the surrounding environment / or transferred to the coolant through the condensation process.

[0057] The throttling device is disposed between the condenser 20 and the evaporator 50. The refrigerant output from the condenser 20 is depressurized by the throttling device to form a low-temperature and low-pressure refrigerant liquid.

[0058] The low-temperature and low-pressure refrigerant liquid output from the throttling device enters the evaporator 50, absorbs heat from the outside or the refrigerant, and forms low-temperature and low-pressure steam. It is then newly input into the compressor 10, and is cyclically compressed by the compressor 10 to become a high-temperature and high-pressure gas, which circulates and is used for cooling or heating the external environment.

[0059] refer to Figure 1 The utility model provides a dual-throttling heat pump unit with adaptive adjustment, which can be adjusted in real time according to load changes and working conditions to achieve stable and efficient operation of the unit.

[0060] At the same time, the heat pump unit also has the advantages of high cost performance, high adjustment accuracy, dual throttling mechanisms complementing and replacing each other, and convenient maintenance.

[0061] Specifically, the heat pump unit involved in the present application includes a compressor 10, a heat exchanger group, a first circulation branch 110, at least one second circulation branch 120 and a pressure detection device.

[0062] The heat exchanger group includes an evaporator 50 and a condenser 20, and the evaporator 50 and the condenser 20 are connected to the compressor 10 through a circulation main circuit 100.

[0063] The first circulation branch 110 is connected to the circulation main circuit 100 and is located between the evaporator 50 and the condenser 20 . An electronic expansion valve 60 is provided on the first circulation branch 110 .

[0064] The electronic expansion valve 60 can automatically adjust the flow rate of the refrigerant according to the change of the indoor temperature, and has the advantages of rapid and sensitive action, accurate adjustment, stable and reliable performance, and a wide adjustment range.

[0065] Since the heat exchanger has a large cooling or heating capacity, a large liquid supply, a wide operating range, and a large pressure ratio, the throttling mechanism needs to have a greater adjustment accuracy and adjustment range, which may exceed the adjustment range of the electronic expansion valve 60.

[0066] In order to assist the electronic expansion valve 60 in regulating the liquid supply and the front-rear pressure difference, the present application is designed with at least one second circulation branch 120 .

[0067] The second circulation branch 120 is connected in parallel with the first circulation branch 110 , and is connected between the evaporator 50 and the condenser 20 .

[0068] The second circulation branch 120 is provided with a regulating valve 70 and a throttling element 80 . When the regulating range exceeds the regulating range of the electronic expansion valve 60 , the regulating valve 70 opens, and the throttling element 80 cooperates with the electronic expansion valve 60 to adjust the liquid supply.

[0069] The pressure detection device is used to detect the pressure difference before and after the liquid supply adjustment in real time. Specifically, it can be understood that the pressure detection device is used to detect the pressure difference between the output end of the condenser 20 and the input end of the evaporator 50.

[0070] In some embodiments of the present application, in order to facilitate the maintenance, inspection and replacement of the electronic expansion valve 60 , switch valves are respectively provided at the input end and the output end of the electronic expansion valve 60 .

[0071] When the electronic expansion valve 60 needs to be maintained, repaired or replaced, the switch valves on both sides of the electronic expansion valve 60 are closed to disconnect the electronic expansion valve 60 from the refrigerant circulation path for easy operation.

[0072] The switch valve specifically includes a first switch valve 41 and a second switch valve 42 . The first switch valve 41 is disposed on the first circulation branch 110 . The first switch valve 41 is located upstream of the electronic expansion valve 60 .

[0073] The second switch valve 42 is disposed upstream of the electronic expansion valve 60 . Specifically, the second switch valve 42 may be disposed on the main circulation path 100 ; or, the second switch valve 42 may be disposed on the main circulation path 100 .

[0074] An input end of the second circulation branch 120 is connected upstream of the first switch valve 41 .

[0075] The opening degree of the regulating valve 70 on the second circulation branch 120 is determined by the pressure difference fed back by the pressure detection device.

[0076] The pressure detection device is used to detect the fluid pressure before and after the electronic expansion valve 60 , and then determine the throttling effect of the electronic expansion valve 60 .

[0077] For example, the fluid pressure value upstream of the electronic expansion valve 60 is defined as P1, and the fluid pressure value downstream of the electronic expansion valve 60 is defined as P2. Then, the fluid pressure difference ΔP of the electronic expansion valve 60 is defined as P1-P2.

[0078] refer to Figure 3Specifically, in some embodiments of the present application, the pressure detection device is arranged on the first circulation branch 110, and includes a first pressure sensor 91 and a second pressure sensor 92. The first pressure sensor 91 is arranged upstream of the first switching valve 41, and the second pressure sensor 92 is arranged downstream of the electronic expansion valve 60.

[0079] In addition, reference Figure 1 In other embodiments, the pressure detection device may also be arranged on the second circulation branch 120 , with the first pressure sensor 91 arranged upstream of the regulating valve 70 , and the second pressure sensor 92 arranged downstream of the throttling member 80 .

[0080] In other embodiments, reference Figure 2 The pressure detection device is arranged on the main circulation path 100 , the first pressure sensor 91 is arranged downstream of the drying filter 30 , and the second pressure sensor 92 is arranged upstream of the second switch valve 42 .

[0081] The three types of setting positions of the first pressure sensor 91 and the second pressure sensor 92 described above have the same detected fluid pressure difference ΔP. The staff can set the specific positions of the first pressure sensor 91 and the second pressure sensor 92 according to the specific size of the installation space.

[0082] refer to Figure 6-Figure 8 In some embodiments of the present application, the number of the second circulation branches 120 is at least two groups.

[0083] The second circulation branches 120 are connected in parallel, and the input end of each second circulation branch 120 is connected to the upstream of the first switch valve 41 .

[0084] A drying filter 30 is also provided on the main circulation path 100 . The drying filter 30 is located downstream of the condenser 20 . The input end of each second circulation branch 120 is located between the drying filter 30 and the first switch valve 41 .

[0085] Each circulation branch is provided with a regulating valve 70 and a throttling element 80. When the regulating range exceeds the regulating range of the electronic expansion valve 60, the regulating valve 70 opens, and the throttling element 80 cooperates with the electronic expansion valve 60 to adjust the liquid supply.

[0086] For example, when the liquid supply adjustment range exceeds the adjustment range of the electronic expansion valve 60, that is, the pressure detection device detects that the pressure difference before and after is greater than the upper limit of the pressure value. At this time, it means that the adjustment range of the electronic expansion valve 60 is at the limit, but still cannot meet the adjustment requirements.

[0087] Under this working condition, the regulating valve 70 on one of the second circulation branches 120 can be opened, and the throttling element 80 on the corresponding second circulation branch 120 cooperates with the electronic expansion valve 60 to perform regulation.

[0088] If the regulating range of the throttling element 80 and the electronic expansion valve 60 on one circulation branch cannot meet the requirements, then the regulating valve 70 on the second circulation branch 120 is opened in sequence until the liquid supply regulation requirements are met.

[0089] The regulating valve 70 may be a valve member with automatic regulating capability, such as an electric ball valve or an electric butterfly valve, to regulate the refrigerant passing through the second circulation branch 120 .

[0090] In some embodiments of the present application, the throttling member 80 is a throttling orifice plate.

[0091] When the refrigerant flows on the second circulation branch 120, due to the local resistance of the orifice plate on the throttling orifice plate, the pressure of the fluid is reduced, energy is lost, and the purpose of throttling is achieved.

[0092] Compressor 10 is a screw heat pump compressor, which has a simple structure, few wearing parts, can operate at a low exhaust temperature under conditions of large pressure difference or pressure ratio, is insensitive to a large amount of lubricating oil in the refrigerant (often called a wet stroke), has good gas flow regulation, and is widely used in refrigeration devices such as air conditioners.

[0093] Of course, in addition to the screw compressor 10, other types of compressors 10 such as piston compressors 10 may also be used.

[0094] The first switch valve 41 and / or the second switch valve 42 is a ball valve, which is mainly used to cut off, distribute and change the flow direction of the medium in the circulation pipeline. It can be closed tightly by rotating 90 degrees and a very small torque.

[0095] The specific working mode of the heat pump unit is described in detail below:

[0096] During the operation of the air-conditioning system, the compressor 10 continuously discharges high-pressure refrigerant gas, which enters the condenser 20, and enters the drying filter 30 after condensation. Then, the liquid refrigerant enters the throttling mechanism, and the refrigerant passes through the first switch valve 41 and enters the electronic expansion valve 60. After throttling by the electronic expansion valve 60, it passes through the second switch valve 42 and enters the evaporator 50. After evaporation in the evaporator 50, it returns to the suction end of the compressor 10.

[0097] When the second circulation branch 120 participates in the refrigerant circulation, part of the refrigerant output from the drying filter 30 passes through the regulating valve 70 , is throttled by the throttling orifice plate, is transported to the evaporator 50 through the second switching valve 42 , and is finally transported back to the compressor 10 .

[0098] The first pressure sensor 91 and the second pressure sensor 92 can detect the pressures before and after the electronic expansion valve 60 in real time, and adjust the opening, closing and opening degree of the regulating valve 70 on the second circulation branch 120 according to the pressure difference.

[0099] Reference Fig. 9 , in the case of medium and large-sized heat pump units or when the liquid supply volume increases or decreases due to load changes, the controller of the heat pump unit judges according to the pressure difference △P detected in real time by the first pressure sensor 91 and the second pressure sensor 92:

[0100] Taking the number of the second circulation branch 120 as an example:

[0101] Combined with Figure 4 , when △P < Pa (Pa is the upper limit of the pressure value), the regulating valve 70 remains closed, and the system throttles through the electronic expansion valve 60.

[0102] Reference Figure 5 , when △P ≥ Pa (Pa is the upper limit of the pressure value), the regulating valve 70 opens a certain opening degree, and the refrigerant enters the throttle orifice plate to assist the electronic expansion valve 60 in throttling.

[0103] When the regulating valve 70 is opened:

[0104] If △P > Pb (Pb < Pa), the opening degree of the electric regulating valve 70 continues to increase so that the pressure difference △P continues to decrease until △P = Pb, and the opening degree of the electric regulating valve 70 remains stable.

[0105] If △P ≤ Pb, the controller controls the opening degree of the regulating valve 70 to continue to decrease, and the pressure difference △P continues to increase until △P = Pb, and then keeps the opening degree of the regulating valve 70 and runs continuously.

[0106] If △P < Pc (Pc < Pb), the regulating valve 70 closes, and the liquid refrigerant throttles only through the electronic expansion valve 60, and the pressure difference △P continues to increase to adapt to the working conditions of small load and small liquid supply volume.

[0107] Through the above adaptive adjustment method, the pressure difference △P is maintained between Pc and Pa, preferably fluctuating around Pb. On the one hand, it solves the problem of large liquid supply volume of medium and large-sized units, and on the other hand, it can be adjusted in real time according to the size of the liquid supply volume to achieve stable and efficient operation of the unit.

[0108] In addition, valve parts are arranged before and after the electronic expansion valve 60 and the throttle orifice plate in this solution, which provides convenience for the maintenance and replacement of the throttling elements.

[0109] The specific values ​​of Pa and Pb can be set to different Pa and Pb values ​​or set to range values ​​according to the type of refrigerant and the refrigeration system to adapt to different refrigeration systems and improve the versatility of the adaptive dual throttling mechanism.

[0110] In addition, you can set 3 or even more pressure values ​​(Pa, Pb, Pc...) to achieve more precise adjustment of the orifice throttling pipeline.

[0111] The present application also proposes a heat pump unit, which includes a compressor 10, a heat exchanger group, a first circulation branch 110, at least one second circulation branch 120 and a pressure detection device.

[0112] The heat exchanger group includes an evaporator 50 and a condenser 20 connected to the compressor 10 through a circulation main circuit 100 .

[0113] The first circulation branch 110 is connected between the evaporator 50 and the condenser 20 , and an electronic expansion valve 60 is disposed on the first circulation branch 110 .

[0114] The second circulation branch 120 is connected in parallel with the first circulation branch 110 and is connected between the evaporator 50 and the condenser 20 . A throttling regulating device is provided on the second circulation branch 120 .

[0115] The pressure detection device is configured to detect a pressure difference between an output end of the condenser 20 and an input end of the evaporator 50 .

[0116] The throttling regulating device is configured to adjust the pressure difference between the output end of the condenser 20 and the input end of the evaporator 50 to within a target range.

[0117] The specific setting of the throttling adjustment device and the pressure detection device can be achieved in the following ways:

[0118] Method 1:

[0119] The throttling regulating device specifically includes an electronic expansion valve 60 connected to the second circulation branch 120 and a third switch valve.

[0120] The pressure detection device is specifically a first pressure sensor 91 arranged at the output end of the condenser 20 and a second pressure sensor 92 arranged at the input end of the evaporator 50 .

[0121] When the pressure difference △P detected in real time by the first pressure sensor 91 and the second pressure sensor 92 is greater than the upper limit of the pressure value, the third switch valve opens, and the electronic expansion valve 60 on the second circulation branch 120 cooperates with the electronic expansion valve 60 on the first circulation branch 110 to adjust the liquid supply until △P is adjusted to below the upper limit of the pressure value.

[0122] When the pressure difference △P detected in real time by the first pressure sensor 91 and the second pressure sensor 92 is less than the upper limit of the pressure value, the third switching valve remains closed, and throttling is only performed by the electronic expansion valve 60 on the first circulation branch 110 to adapt to the working conditions of small load and small liquid supply volume.

[0123] Method 2:

[0124] A regulating valve 70 and a throttling element 80 are provided on the second circulation branch 120. When the adjustment range exceeds the adjustment range of the electronic expansion valve 60, the regulating valve 70 opens, and the liquid supply is adjusted in cooperation with the electronic expansion valve 60 through the throttling element 80.

[0125] The opening degree of the regulating valve 70 on the second circulation branch 120 is determined by the pressure difference fed back by the pressure detection device.

[0126] The pressure detection device is specifically a first pressure sensor 91 provided at the output end of the condenser 20 and a second pressure sensor 92 provided at the input end of the evaporator 50.

[0127] When the pressure difference △P detected in real time by the first pressure sensor 91 and the second pressure sensor 92 is greater than the upper limit of the pressure value, that is, when △P≥Pa, the regulating valve 70 opens a certain opening degree, and the refrigerant enters the throttle orifice to assist the electronic expansion valve 60 in throttling.

[0128] Reference Fig. 9 , for medium and large-sized heat pump units or in the case of an increase or decrease in the liquid supply volume caused by a load change, the controller of the heat pump unit judges according to the pressure difference △P detected in real time by the first pressure sensor 91 and the second pressure sensor 92:

[0129] When △P < Pa (Pa is the upper limit of the pressure value), the regulating valve 70 remains closed, and the system throttles through the electronic expansion valve 60.

[0130] When △P≥Pa (Pa is the upper limit of the pressure value), the regulating valve 70 opens a certain opening degree, and the refrigerant enters the throttle orifice to assist the electronic expansion valve 60 in throttling.

[0131] After the regulating valve 70 opens:

[0132] If △P > Pb (Pb < Pa), the opening degree of the electric regulating valve 70 continues to increase so that the pressure difference △P continues to decrease until △P = Pb, and the opening degree of the electric regulating valve 70 remains stable.

[0133] If △P≤Pb, the controller controls the opening degree of the regulating valve 70 to continue to decrease, the pressure difference △P continues to increase until △P = Pb, and then the opening degree of the regulating valve 70 is maintained and the operation continues.

[0134] When △P < Pc (Pc < Pb), the regulating valve 70 closes, and the liquid refrigerant is throttled only through the electronic expansion valve 60. The pressure difference △P continues to increase to adapt to the working conditions of small load and small liquid supply volume.

[0135] Through the above adaptive adjustment method, the pressure difference △P is maintained between Pc and Pa, preferably fluctuating around Pb. On the one hand, it solves the problem of large liquid supply volume in medium and large-sized units. On the other hand, it can be adjusted in real time according to the size of the liquid supply volume to achieve stable and efficient operation of the unit.

[0136] Method 3:

[0137] On the basis of Method 2, the throttling element 80 is an orifice plate.

[0138] When the refrigerant flows on the second circulation branch 120, due to the local resistance of the orifice plate on the orifice plate, the pressure of the fluid decreases and the energy is lost to achieve the throttling purpose.

[0139] The compressor 10 is a screw-type heat pump compressor 10, which has a simple structure and few vulnerable parts. It can operate at low exhaust temperature under the working conditions of large pressure difference or pressure ratio, and is widely used in refrigeration devices such as air conditioners.

[0140] The above three methods can be used alone for Method 1 or Method 2, or Method 2 can be combined with Method 3.

[0141] The heat pump unit proposed in this application compares the pressure difference detected by the pressure detection device with the upper limit or pressure range of the pressure difference, and correspondingly adjusts the opening of the regulating valve 70 to achieve intelligent adjustment. The liquid supply pipeline of the entire heat pump unit is simple and has low cost. Under the real-time detection of the pressure detection device, it is adjusted in real time according to the load change and working condition change. The performance matching of the liquid supply adjustment is high, and the adjustment accuracy is high, so as to achieve stable and efficient operation of the unit.

[0142] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0143] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A heat pump unit, characterized in that: include: compressor; A heat exchanger group, comprising an evaporator and a condenser, wherein the evaporator and the condenser are connected to the compressor through a main circulation path; a first circulation branch connected between the evaporator and the condenser, wherein an electronic expansion valve is provided on the first circulation branch; at least one second circulation branch, which is connected in parallel with the first circulation branch and connected between the evaporator and the condenser, and a regulating valve and a throttling element are provided on the second circulation branch; A pressure detection device is configured to detect a pressure difference between the condenser output end and the evaporator input end.

2. The heat pump unit according to claim 1, characterized in that: A first switch valve is also provided on the first circulation branch, and the first switch valve is located upstream of the electronic expansion valve. The input end of the second circulation branch is connected upstream of the first switch valve.

3. The heat pump unit according to claim 2, characterized in that: A second switch valve is further arranged downstream of the electronic expansion valve, and the second switch valve is arranged on the main circulation line or the second switch valve is arranged on the first circulation branch line.

4. The heat pump unit according to claim 3, characterized in that: The main circulation path is also provided with a drying filter, and the drying filter is located downstream of the condenser.

5. The heat pump unit according to claim 1, characterized in that: The pressure detection device is arranged on the second circulation branch, and includes a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged upstream of the regulating valve, and the second pressure sensor is arranged downstream of the throttling member.

6. The heat pump unit according to claim 3, characterized in that: The pressure detection device is arranged on the first circulation branch, and comprises a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged upstream of the first switch valve, and the second pressure sensor is arranged downstream of the electronic expansion valve.

7. The heat pump unit according to claim 4, characterized in that: The pressure detection device is arranged on the main circulation path, and includes a first pressure sensor and a second pressure sensor. The first pressure sensor is arranged downstream of the drying filter, and the second pressure sensor is arranged upstream of the second switch valve.

8. The heat pump unit according to claim 1, characterized in that: The throttling element is a throttling orifice plate.

9. The heat pump unit according to claim 3, characterized in that: The compressor is a screw heat pump compressor, and / or The first switch valve and / or the second switch valve is a ball valve.

10. A heat pump unit, characterized in that: include: compressor; a heat exchanger group, comprising an evaporator and a condenser connected to the compressor via a main circulation path; a first circulation branch connected between the evaporator and the condenser, wherein an electronic expansion valve is provided on the first circulation branch; at least one second circulation branch connected in parallel with the first circulation branch and between the evaporator and the condenser, wherein a throttling regulating device is provided on the second circulation branch; a pressure detection device configured to detect a pressure difference between an output end of the condenser and an input end of the evaporator; Wherein, the throttling regulating device is configured to adjust the pressure difference between the condenser output end and the evaporator input end to within a target range.

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