Heat pump unit and control method thereof

Abstract

The application provides a heat pump unit and a control method thereof. The heat pump unit comprises a first compression device and a second compression device, a first air supplement device and a second air supplement device. The first compression device comprises a first cylinder, an intermediate cavity and a second cylinder. Exhaust gas of the first cylinder enters the intermediate cavity, exhaust gas of the intermediate cavity enters the second cylinder, forming at least two-stage compression, and exhaust gas of the first compression device enters a suction port of the second compression device. The first air supplement device can supplement air to the first cylinder and / or the intermediate cavity, and the second air supplement device can supplement air to the intermediate cavity and / or the second cylinder. The first air supplement device and the second air supplement device can control air supplement to the first cylinder, the intermediate cavity and the second cylinder according to exhaust gas temperature of the first compression device. The application can solve the problems of low heating capacity at low temperature and high exhaust gas temperature of the heat pump unit in the prior art.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more specifically to a heat pump unit and its control method. Background Technology

[0002] With the increasing popularity of heat pump water heaters in the context of coal-to-electricity conversion, their application scenarios are becoming more and more widespread. The heating process of a heat pump water heater mainly involves absorbing heat from the outdoor air. Through the work of the compressor, heat is absorbed from the low-temperature heat source, i.e., the air, on the evaporator side. Then, through a water system heat exchanger, such as a plate heat exchanger or a shell-and-tube heat exchanger, the heat in the high-temperature refrigerant is transferred to the water system, circulating through the water circuit to provide heating to users. In northern regions, the lower the temperature, the greater the demand for heating. As the temperature decreases, evaporation also decreases. If the outlet water temperature remains constant, i.e., the condensing pressure remains constant, the compressor's compression ratio (condensing pressure / evaporating pressure) will increase. An excessively high compression ratio reduces the intake air volume, lowers the capacity, and increases the exhaust temperature, leading to reliability issues. However, at low temperatures, the demand for heat increases, and the heating capacity of the heat pump decreases as the temperature drops. This creates a supply-demand imbalance, limiting the application of heat pumps.

[0003] Because existing heat pump units suffer from technical problems such as low heating capacity at low temperatures, this invention studies and designs a heat pump unit and its control method. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low heating capacity at low temperatures in the heat pump units of the prior art, thereby providing a heat pump unit and its control method.

[0005] To address the above problems, the present invention provides a heat pump unit, comprising:

[0006] A first compression device and a second compression device, a first air supply device and a second air supply device, wherein the first compression device includes a first cylinder, an intermediate chamber and a second cylinder, the exhaust from the first cylinder enters the intermediate chamber and the exhaust from the intermediate chamber enters the second cylinder to form at least two-stage compression, and the exhaust from the first compression device enters the intake port of the second compression device.

[0007] The first air supply device can supply air to the first cylinder and / or the intermediate chamber, and the second air supply device can supply air to the intermediate chamber and / or the second cylinder. The first air supply device and the second air supply device can control the air supply to the first cylinder, the intermediate chamber and the second cylinder according to the exhaust temperature of the first compression device.

[0008] In some implementations...

[0009] The first air supply device can be connected to the air supply port of the first cylinder through the first air supply pipeline, and a first valve is provided on the first air supply pipeline. The second air supply device can be connected to the air supply port of the intermediate cavity through the second air supply pipeline, and a second valve is provided on the second air supply pipeline.

[0010] The outlet of the second cylinder is connected to the intake port of the second compression device through the first pipeline. A first temperature detection device is installed on the first pipeline. Both the first valve and the second valve are control valves. Both the first valve and the second valve are controlled to open and close according to the exhaust temperature detected by the first temperature detection device.

[0011] In some implementations...

[0012] The first air supply device can be connected to the air supply port of the first cylinder through a first air supply pipeline, and a first valve is provided on the first air supply pipeline. The first air supply device can also be connected to the air supply port of the intermediate cavity through a second air supply pipeline, and a second valve is provided on the second air supply pipeline.

[0013] The outlet of the second cylinder is connected to the intake port of the second compression device through the first pipeline. A first temperature detection device is installed on the first pipeline. Both the first valve and the second valve are control valves. Both the first valve and the second valve are controlled to open and close according to the exhaust temperature detected by the first temperature detection device.

[0014] In some implementations...

[0015] The second air supply device can be connected to the air supply port of the intermediate cavity through a third air supply pipeline, which is equipped with a third valve. The second air supply device is also connected to the air supply port of the second cylinder through a fourth air supply pipeline, which is equipped with a fourth valve.

[0016] The exhaust port of the second compression device exhausts gas through the second pipeline. The second pipeline is equipped with a second temperature detection device. The third valve and the fourth valve are both control valves. The third valve and the fourth valve are controlled to open and close according to the exhaust temperature detected by the second temperature detection device.

[0017] In some implementations...

[0018] The second air replenishment device is also connected to the air intake of the second compression device through a fifth air replenishment pipeline, and a fifth valve is provided on the fifth air replenishment pipeline. The second air replenishment device is also connected to the air replenishment port of the second compression device through a sixth air replenishment pipeline, and a sixth valve is provided on the sixth air replenishment pipeline. Both the fifth valve and the sixth valve are control valves, and both the fifth valve and the sixth valve are opened and closed according to the exhaust temperature detected by the second temperature detection device.

[0019] In some embodiments,

[0020] further comprising a first heat exchanger, a second heat exchanger, a first throttling device, a second throttling device, a third throttling device, a third pipeline, a fourth pipeline and a fifth pipeline, wherein the first gas supplementing device is communicated with one end of the first heat exchanger through the third pipeline, the first throttling device is arranged on the third pipeline, the second gas supplementing device is communicated with the first gas supplementing device through the fourth pipeline, the second throttling device is arranged on the fourth pipeline, the second gas supplementing device is communicated with one end of the second heat exchanger through the fifth pipeline, and the third throttling device is arranged on the fifth pipeline.

[0021] In some embodiments,

[0022] further comprising a four-way valve, a gas-liquid separator, a sixth pipeline, a seventh pipeline, an eighth pipeline and a ninth pipeline, wherein an air outlet of the second compression device is communicated with a first end of the four-way valve through a second pipeline, the first heat exchanger is communicated with a second end of the four-way valve through the sixth pipeline, the second heat exchanger is communicated with a third end of the four-way valve through the seventh pipeline, the gas-liquid separator is communicated with a fourth end of the four-way valve through the eighth pipeline, and the gas-liquid separator is further communicated with an air suction port of the first compression device through the ninth pipeline.

[0023] The present invention further provides a control method for the aforementioned heat pump unit, comprising:

[0024] a detecting step: detecting an exhaust temperature T1 of the first compression device by the first temperature detecting device;

[0025] a judging step: judging the relationship between T1 and a first preset temperature a;

[0026] a controlling step: when T1 ≥ a, opening the first valve and closing the second valve, and performing gas supplementation through the gas supplementation port of the first cylinder; when T1 < a-x, closing the first valve and the second valve, and stopping gas supplementation; when a-x ≤ T1 < a, the first valve and the second valve maintain their original states; wherein x is a constant.

[0027] In some embodiments,

[0028] in the judging step, the relationship between T1 and a second preset temperature b is further judged, wherein b > a;

[0029] In the control step, when T1≥b, the first valve and the second valve are opened, and air is simultaneously supplied through the air supply port of the first cylinder and the air supply port of the intermediate chamber; when T1<b-x, the first valve is opened and the second valve is closed; when b-x≤T1<b, the first valve and the second valve maintain the original state, wherein b-x≥a.

[0030] The present invention further provides a control method for the aforementioned heat pump unit, comprising:

[0031] a detection step of detecting an exhaust temperature T1 of the first compression device by the first temperature detection device;

[0032] a judgment step of judging a relationship between T1 and a first preset temperature a;

[0033] a control step of, when T1≥a, opening the first valve, closing the second valve, and supplying air through the air supply port of the first cylinder; when T1<a-x, closing the first valve and the second valve, and stopping air supply; when a-x≤T1<a, the first valve and the second valve maintaining the original state; wherein x is a constant.

[0034] In some embodiments,

[0035] the judgment step further comprises judging a relationship between T1 and a second preset temperature b, where b>a;

[0036] in the control step, when T1≥b, the first valve and the second valve are opened, and air is simultaneously supplied through the air supply port of the first cylinder and the air supply port of the intermediate chamber; when T1<b-x, the first valve is opened and the second valve is closed; when b-x≤T1<b, the first valve and the second valve maintain the original state, wherein b-x≥a.

[0037] In some embodiments,

[0038] the detection step further comprises detecting an exhaust temperature T2 of the second compression device by the second temperature detection device;

[0039] the judgment step comprises judging a relationship between T2 and a third preset temperature c;

[0040] in the control step, when T2≥c, the third valve is opened, and the fourth valve, the fifth valve and the sixth valve are closed, and air is supplied through the air supply port of the intermediate chamber; when T2<c-y, the third valve, the fourth valve, the fifth valve and the sixth valve are closed; when c-y≤T2<c, the third valve, the fourth valve, the fifth valve and the sixth valve all maintain the original state; wherein y is a constant.

[0041] In some embodiments,

[0042] In the judging step, the relationship between T2 and a fourth preset temperature d is judged, wherein d>c;

[0043] In the controlling step, when T2≥d, the third valve and the fourth valve are opened, the fifth valve and the sixth valve are closed, and gas is supplied through the gas supply port of the intermediate cavity and the gas supply port of the second cylinder; when T2<d-y, the third valve is opened, and the fourth valve, the fifth valve and the sixth valve are closed; when d-y≤T2<d, all of the third valve, the fourth valve, the fifth valve and the sixth valve maintain their original states, and at this time d-y≥c.

[0044] In some embodiments,

[0045] In the judging step, the relationship between T2 and a fifth preset temperature e is judged, wherein e>d;

[0046] In the controlling step, when T2≥e, the third valve, the fourth valve and the fifth valve are opened, the sixth valve is closed, and gas is supplied through the gas supply port of the intermediate cavity, the gas supply port of the second cylinder and the suction port of the second compression device; when it is detected that T2<e-y, the third valve and the fourth valve are opened, and the fifth valve and the sixth valve are closed; when e-y≤T2<e, all of the third valve, the fourth valve, the fifth valve and the sixth valve maintain their original states, and at this time e-y≥d.

[0047] In some embodiments,

[0048] In the judging step, the relationship between T2 and a sixth preset temperature f is judged, wherein f>e;

[0049] In the controlling step, when T2≥f, the third valve, the fourth valve, the fifth valve and the sixth valve are opened, and gas is supplied through the gas supply port of the intermediate cavity, the gas supply port of the second cylinder, the suction port of the second compression device and the gas supply port of the second compression device; when T2<f-y, the third valve, the fourth valve and the fifth valve are opened, and the sixth valve is closed; when f-y≤T2<f, all of the third valve, the fourth valve, the fifth valve and the sixth valve maintain their original states, and at this time f-y≥e.

[0050] The heat pump unit and the control method thereof provided by the present invention have the following beneficial effects:

[0051] 1. This invention employs two series-connected compression devices, with the first compression device having at least two cylinders, and first and second air supply devices capable of supplying air to the first, second, and / or intermediate chambers. This effectively increases the air supply volume, particularly improving the air supply volume of the compressor under low-temperature or ultra-low-temperature conditions, thereby enhancing heating capacity. Furthermore, the first and / or second air supply devices can control the air supply to the first cylinder, the intermediate chamber, and the second cylinder based on the exhaust temperature of the first compression device. This allows for selective air supply to one or more cylinder positions based on the exhaust temperature of the first compression device, forming a reasonable air supply control mechanism. This solution reduces the exhaust temperature of the first compression unit to a specified range, improving temperature control accuracy and preventing excessively high exhaust temperatures. This avoids exhaust protection shutdowns and wear-related issues. It also increases the gas supply to the compression unit, thereby enhancing heating / cooling capacity and increasing outlet water temperature. This effectively solves the problem of high compressor pressure ratios in ultra-low temperature environments, which cannot meet high outlet water temperatures. Furthermore, it effectively addresses the low heating capacity of existing heat pump units at low temperatures and solves the problem of excessively high exhaust temperatures, ensuring precise exhaust temperature control and preventing protective shutdowns.

[0052] 2. The present invention further enables the second air supply device to communicate with the air supply port of the intermediate cavity via a third air supply pipeline, wherein a third valve is provided on the third air supply pipeline. The second air supply device is also connected to the air supply port of the second cylinder via a fourth air supply pipeline, wherein a fourth valve is provided on the third air supply pipeline. The outlet of the second compression device exhausts gas through a second pipeline, wherein a second temperature detection device is provided on the second pipeline. Both the third and fourth valves are control valves, and their opening and closing are controlled according to the exhaust temperature detected by the second temperature detection device. This enables the second air supply device to... Based on the exhaust temperature of the second compression device, selective air replenishment is applied to the intermediate chamber and the second cylinder of the first compression device to form a reasonable air replenishment control scheme. This allows the exhaust temperature of the second compression device to be reduced to a specified temperature range, improving temperature control accuracy and ensuring that the exhaust temperature is not too high. This avoids the second compression device shutting down due to exhaust protection and prevents wear and tear. At the same time, it can further increase the amount of air replenished to the first compression device, thereby improving the heating / cooling capacity and the outlet water temperature. This effectively solves the problem that the compressor pressure ratio is too large to meet the high outlet water temperature in ultra-low temperature environments, and effectively improves the outlet water temperature.

[0053] 3. Furthermore, the present invention further connects the second air replenishment device to the intake port of the second compression device via a fifth air replenishment pipeline, wherein a fifth valve is provided on the fifth air replenishment pipeline. The second air replenishment device also connects to the air replenishment port of the second compression device via a sixth air replenishment pipeline, wherein a sixth valve is provided on the sixth air replenishment pipeline. Both the fifth and sixth valves are control valves, and their opening and closing are controlled according to the exhaust temperature detected by the second temperature detection device. This allows the second air replenishment device to selectively replenish air to the intake and air replenishment ports of the second compression device based on the exhaust temperature of the second compression device, forming a reasonable air replenishment control scheme. This further reduces the exhaust temperature of the second compression device to a specified temperature range, improving temperature control accuracy and ensuring that the exhaust temperature does not become too high. This further avoids shutdown due to exhaust protection of the second compression device and prevents wear and tear. Simultaneously, it increases the amount of air replenished to the second compression device, thereby improving heating / cooling capacity and increasing the outlet water temperature. This effectively solves the problem of the compressor's high pressure ratio failing to meet high outlet water temperatures under ultra-low temperature environments, effectively improving the outlet water temperature. Attached Figure Description

[0054] Figure 1 This is a system structure diagram of Embodiment 1 of the heat pump unit of the present invention;

[0055] Figure 2 This is a system structure diagram of embodiment 2 of the heat pump unit of the present invention.

[0056] The reference numerals in the attached figures are as follows:

[0057] 1. First compression device; 11. First cylinder; 12. Intermediate chamber; 13. Second cylinder; 2. Second compression device; 3. One-way valve; 4. First air supply device; 5. Second air supply device; 6. Second heat exchanger; 7. Four-way valve; 8. First heat exchanger; 9. Gas-liquid separator; 101. First air supply pipeline; 102. Second air supply pipeline; 103. Third air supply pipeline; 104. Fourth air supply pipeline; 105. Fifth air supply pipeline; 106. Sixth air supply pipeline; 201. First pipeline; 202, Second Pipeline; 203, Third Pipeline; 204, Fourth Pipeline; 205, Fifth Pipeline; 206, Sixth Pipeline; 207, Seventh Pipeline; 208, Eighth Pipeline; 209, Ninth Pipeline; V1, First Valve; V2, Second Valve; V3, Third Valve; V4, Fourth Valve; V5, Fifth Valve; V6, Sixth Valve; E1, First Throttling Device; E2, Second Throttling Device; E3, Third Throttling Device; F1, First Temperature Detection Device; F2, Second Temperature Detection Device. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0060] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0061] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0062] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0063] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0064] like Figure 1-2 As shown, the present invention provides a heat pump unit, which includes:

[0065] A first compression device 1 and a second compression device 2, a first air supply device 4 and a second air supply device 5, wherein the first compression device 1 includes a first cylinder 11, an intermediate chamber 12 and a second cylinder 13, wherein the exhaust from the first cylinder 11 enters the intermediate chamber 12 and the exhaust from the intermediate chamber 12 enters the second cylinder 13, forming at least two-stage compression, and the exhaust from the first compression device 1 enters the intake port of the second compression device 2.

[0066] The first air supply device 4 can supply air to the first cylinder 11 and / or the intermediate chamber 12, and the second air supply device 5 can supply air to the intermediate chamber 12 and / or the second cylinder 13. The first air supply device 4 and the second air supply device 5 can control the air supply to the first cylinder 11, the intermediate chamber 12 and the second cylinder 13 according to the exhaust temperature of the first compression device 1.

[0067] This invention employs two series-connected compression devices, with the first compression device having at least two cylinders, and first and second air supply devices capable of supplying air to the first, second, and / or intermediate chambers. This effectively increases the air supply volume, particularly improving the air supply volume of the compressor under low-temperature or ultra-low-temperature conditions, thereby enhancing heating capacity. Furthermore, the first and / or second air supply devices can control the air supply to the first cylinder, the intermediate chamber, and the second cylinder based on the exhaust temperature of the first compression device. This allows for selective air supply to one or more cylinder positions based on the exhaust temperature of the first compression device, resulting in rational air supply control. This solution reduces the exhaust temperature of the first compression unit to a specified range, improving temperature control accuracy and preventing excessively high exhaust temperatures. This avoids exhaust protection shutdowns and wear-related issues. It also increases the gas supply to the compression unit, thereby enhancing heating / cooling capacity and increasing outlet water temperature. This effectively solves the problem of high compressor pressure ratios in ultra-low temperature environments, which cannot meet high outlet water temperatures. Furthermore, it effectively addresses the low heating capacity of existing heat pump units at low temperatures and solves the problem of excessively high exhaust temperatures, ensuring precise exhaust temperature control and preventing protective shutdowns.

[0068] Example 1, such as Figure 1 In some implementation methods,

[0069] The first air supply device 4 can be connected to the air supply port of the first cylinder 11 through the first air supply pipeline 101, and the first air supply pipeline 101 is provided with a first valve V1. The second air supply device 5 can be connected to the air supply port of the intermediate cavity 12 through the second air supply pipeline 102, and the second air supply pipeline 102 is provided with a second valve V2.

[0070] The outlet of the second cylinder 13 is connected to the intake port of the second compression device 2 through the first pipeline 201. A first temperature detection device F1 is provided on the first pipeline 201. The first valve V1 and the second valve V2 are both control valves (preferably solenoid valves). The first valve V1 and the second valve V2 are both controlled to open and close according to the exhaust temperature detected by the first temperature detection device F1.

[0071] This is a preferred system structure of Embodiment 1 of the present invention. A first air supply device and a first air supply pipeline are connected to the air supply port of the first cylinder to supply air to the first cylinder of the first compression device. A second air supply device and a second air supply pipeline are connected to the air supply port of the intermediate cavity to supply air to the intermediate cavity of the first compression device. This allows for control of the opening and closing of the two air supply pipelines based on the exhaust temperature of the first compression device. This ensures that the exhaust temperature of the first compression device is not too high, meeting precise temperature control within a specified range, while also increasing or decreasing the air supply volume to meet demand. Simultaneously, it ensures that the heating / cooling capacity of the heat exchanger in the system is maximized (ensuring the exhaust temperature is within a specified range while simultaneously improving cooling / heating capacity), thus improving the energy efficiency of the heat pump system.

[0072] Example 2, as Figure 2 In some implementation methods,

[0073] The first air supply device 4 can be connected to the air supply port of the first cylinder 11 through the first air supply pipeline 101, and the first air supply pipeline 101 is provided with a first valve V1. The first air supply device 4 can also be connected to the air supply port of the intermediate cavity 12 through the second air supply pipeline 102, and the second air supply pipeline 102 is provided with a second valve V2.

[0074] The outlet of the second cylinder 13 is connected to the intake port of the second compression device 2 through the first pipeline 201. A first temperature detection device F1 is provided on the first pipeline 201. The first valve V1 and the second valve V2 are both control valves. The first valve V1 and the second valve V2 are both controlled to open and close according to the exhaust temperature detected by the first temperature detection device F1.

[0075] This is a preferred system structure of Embodiment 2 of the present invention. A first air supply device and a first air supply pipeline are connected to the air supply port of the first cylinder to supply air to the first cylinder of the first compression device. The first air supply device and the second air supply pipeline are connected to the air supply port of the intermediate cavity to supply air to the intermediate cavity of the first compression device. This allows for control of the opening and closing of the two air supply pipelines based on the exhaust temperature of the first compression device. This ensures that the exhaust temperature of the first compression device is not too high, meeting precise temperature control within a specified range, while also increasing or decreasing the air supply volume to meet demand. Simultaneously, it ensures that the heating / cooling capacity of the heat exchanger in the system reaches its maximum (ensuring the exhaust temperature is within a specified range while simultaneously improving cooling / heating capacity), thus improving the energy efficiency of the heat pump system.

[0076] In some implementations...

[0077] The second air supply device 5 can be connected to the air supply port of the intermediate cavity 12 through the third air supply pipeline 103, and the third air supply pipeline 103 is equipped with a third valve V3. The second air supply device 5 is also connected to the air supply port of the second cylinder 13 through the fourth air supply pipeline 104, and the third air supply pipeline 103 is equipped with a fourth valve V4.

[0078] The exhaust port of the second compression device 2 exhausts through the second pipeline 202. The second pipeline 202 is equipped with a second temperature detection device F2. The third valve V3 and the fourth valve V4 are both control valves. The third valve V3 and the fourth valve V4 are controlled to open and close according to the exhaust temperature detected by the second temperature detection device F2.

[0079] Embodiment 2 of the present invention further connects the second air supply device to the air supply port of the intermediate cavity via a third air supply pipeline, wherein a third valve is provided on the third air supply pipeline. The second air supply device also connects to the air supply port of the second cylinder via a fourth air supply pipeline, wherein a fourth valve is provided on the third air supply pipeline. The outlet of the second compression device exhausts gas through a second pipeline, wherein a second temperature detection device is provided on the second pipeline. Both the third and fourth valves are control valves, and both are opened and closed according to the exhaust temperature detected by the second temperature detection device; this enables the second air supply device to... The gas supply device selectively replenishes gas to the intermediate chamber and the second cylinder of the first compressor based on the exhaust temperature of the second compressor, forming a reasonable gas supply control scheme. This allows the exhaust temperature of the second compressor to be reduced to a specified temperature range, improving temperature control accuracy and ensuring that the exhaust temperature does not become too high. This avoids shutdown due to exhaust protection of the second compressor and prevents wear and tear. At the same time, it can further increase the amount of gas supplied to the first compressor, thereby improving the heating / cooling capacity and the outlet water temperature. This effectively solves the problem that the compressor pressure ratio is too high to meet the high outlet water temperature in ultra-low temperature environments, and effectively improves the outlet water temperature.

[0080] In some implementations...

[0081] The second air supply device 5 is also connected to the air intake of the second compression device 2 through the fifth air supply pipeline 105. The fifth air supply pipeline 105 is equipped with a fifth valve V5. The second air supply device 5 is also connected to the air supply port of the second compression device 2 through the sixth air supply pipeline 106. The sixth air supply pipeline 106 is equipped with a sixth valve V6. Both the fifth valve V5 and the sixth valve V6 are control valves. Both the fifth valve V5 and the sixth valve V6 are controlled to open and close according to the exhaust temperature detected by the second temperature detection device F2.

[0082] Embodiment 2 of the present invention further connects the second air replenishment device to the intake port of the second compression device via a fifth air replenishment pipeline, wherein a fifth valve is provided on the fifth air replenishment pipeline. The second air replenishment device is also connected to the air replenishment port of the second compression device via a sixth air replenishment pipeline, wherein a sixth valve is provided on the sixth air replenishment pipeline. Both the fifth and sixth valves are control valves, and both are opened and closed according to the exhaust temperature detected by the second temperature detection device. This allows the second air replenishment device to selectively replenish air to the intake and air replenishment ports of the second compression device based on the exhaust temperature of the second compression device, forming a reasonable air replenishment control scheme. This further reduces the exhaust temperature of the second compression device to a specified temperature range, improving temperature control accuracy and ensuring that the exhaust temperature is not too high. This further avoids shutdown due to exhaust protection of the second compression device and prevents wear and tear. Simultaneously, it increases the amount of air replenished to the second compression device, thereby improving heating / cooling capacity and increasing the outlet water temperature. This effectively solves the problem that the compressor pressure ratio is too high to meet the high outlet water temperature requirement under ultra-low temperature conditions, effectively improving the outlet water temperature.

[0083] In some implementations...

[0084] It also includes a first heat exchanger 8, a second heat exchanger 6, a first throttling device E1, a second throttling device E2, a third throttling device E3, a third pipeline 203, a fourth pipeline 204, and a fifth pipeline 205. The first gas supply device 4 is connected to one end of the first heat exchanger 8 through the third pipeline 203. The first throttling device E1 is installed on the third pipeline 203. The second gas supply device 5 is connected to the first gas supply device 4 through the fourth pipeline 204. The second throttling device E2 is installed on the fourth pipeline 204. The second gas supply device 5 is connected to one end of the second heat exchanger 6 through the fifth pipeline 205. The third throttling device E3 is installed on the fifth pipeline 205.

[0085] This is a further preferred structural form of the heat pump unit of the present invention, namely, a throttling device is set on the pipelines connecting the two gas supply devices to the first and second heat exchangers respectively, and on the pipeline between the two gas supply devices, which can realize the purpose of throttling flashing and gas supply to different compression units, and meet the requirements of gas supply pressure and flow rate.

[0086] In some implementations...

[0087] further includes a four-way valve 7, a gas-liquid separator 9, a sixth pipeline 206, a seventh pipeline 207, an eighth pipeline 208 and a ninth pipeline 209, wherein the gas outlet of the second compression device 2 communicates with the first end of the four-way valve 7 through the second pipeline 202, the first heat exchanger 8 communicates with the second end of the four-way valve 7 through the sixth pipeline 206, the second heat exchanger 6 communicates with the third end of the four-way valve 7 through the seventh pipeline 207, the gas-liquid separator 9 communicates with the fourth end of the four-way valve 7 through the eighth pipeline 208, and the gas-liquid separator 9 further communicates with the suction inlet of the first compression device 1 through the ninth pipeline 209.

[0088] This is a further preferred structural form of the heat pump unit of the present invention. Switching between a cooling mode and a heating mode can be achieved through the structure of the four-way valve, and the ninth pipeline can provide suction refrigerant for the suction inlet of the first compression device.

[0089] Embodiment 1: the present invention further provides a control method for the heat pump unit as described above, comprising:

[0090] a detection step: detecting the exhaust temperature T1 of the first compression device by the first temperature detection device F1;

[0091] a judgment step: judging the relationship between T1 and a first preset temperature a;

[0092] a control step: when T1 ≥ a, opening the first valve V1, closing the second valve V2, and performing gas supply through the gas supply port of the first cylinder 11; when T1 < a-x, closing the first valve V1 and the second valve V2, and stopping gas supply; when a-x ≤ T1 < a, keeping the original states of the first valve V1 and the second valve V2, wherein x is a constant.

[0093] This is the preferred control method of Embodiment 1 of the present invention: when it is detected that the F1 temperature T1≥a, the first valve V1 is opened and the second valve V2 is closed, and gas is supplied through the low-pressure cylinder (this indicates that the exhaust temperature is slightly high, the amount of refrigerant in the low-pressure stage is relatively small, so it is necessary to appropriately open the valve and perform slight gas supply to appropriately reduce the exhaust temperature and prevent the exhaust temperature from being too high); when it is detected that T1<a-x, the first valve V1 and the second valve V2 are closed, and no gas is supplied (this indicates that the exhaust temperature is very low and no gas supply is required); when the F1 temperature satisfies a>T1≥a-x, the first valve V1 and the second valve V2 maintain their original states (this indicates that the exhaust temperature is moderate, and maintaining the current state can keep the exhaust temperature within the required range), which can achieve first-stage control. The opening and closing of the two gas supply pipelines are controlled according to the exhaust temperature of the first compression device, so that on the premise of ensuring that the exhaust temperature of the first compression device is not too high and achieving accurate temperature control within the specified range, the gas supply amount can also be increased or decreased to make the gas supply amount meet the demand, while ensuring that the heating / cooling capacity of the heat exchanger in the system reaches the maximum (ensuring that the exhaust temperature is within the specified range and improving the cooling / heating capacity at the same time), and improving the energy efficiency of the heat pump system.

[0094] In some embodiments,

[0095] In the determining step, the relationship between T1 and a second preset temperature b is further determined, where b>a;

[0096] In the control step, when T1≥b, the first valve V1 and the second valve V2 are opened, and gas is supplied simultaneously through the gas supply port of the first cylinder 11 and the gas supply port of the intermediate chamber 12; when T1<b-x, the first valve V1 is opened and the second valve V2 is closed; when b-x≤T1<b, the first valve V1 and the second valve V2 maintain their original states, and at this time b-x≥a.

[0097] This is a further preferred control method of Embodiment 1 of the present invention: when it is detected that the F1 temperature T1≥b, the first valve V1 and the second valve V2 are opened, and air supply is performed through the low-pressure cylinder and the intermediate make-up air port (this indicates that the discharge temperature is relatively high, and the refrigerant amount in the low-pressure stage and the intermediate chamber is relatively small, so it is necessary to open the air supply to the first cylinder and the intermediate chamber at the same time to reduce the discharge temperature and prevent the discharge temperature from being too high); when it is detected that T1<b-x, the first valve V1 is opened and the second valve V2 is closed (this indicates that the discharge temperature is slightly high, and the refrigerant amount in the low-pressure stage is relatively small, so it is only necessary to open the air supply to the first cylinder for weak air supply to appropriately reduce the discharge temperature and prevent the discharge temperature from being too high); when it is detected that b>T1≥b-x, the first valve V1 and the second valve V2 maintain their original states, where b-x≥a (this indicates that the discharge temperature is moderate, and maintaining the current state can ensure that the discharge temperature is within the required range). This can realize the control of the discharge temperature of the second stage, and control the opening and closing of the two air supply pipelines according to the discharge temperature of the first compression device, so as to ensure that the discharge temperature of the first compression device is not too high, achieve accurate temperature control within the specified range, and at the same time increase or decrease the air supply amount to make the air supply amount meet the demand, and ensure that the heating / cooling capacity of the heat exchanger in the system reaches the maximum (ensuring the discharge temperature is within the specified range while improving the cooling / heating capacity), and improve the energy efficiency of the heat pump system.

[0098] In Embodiment 2, the present invention also provides a control method for the heat pump unit as described above, comprising:

[0099] a detection step of detecting the discharge temperature T1 of the first compression device 1 by the first temperature detection device F1;

[0100] a judgment step of judging the relationship between T1 and the first preset temperature a;

[0101] a control step: when T1≥a, opening the first valve V1, closing the second valve V2, and performing air supply through the air supply port of the first cylinder 11; when T1<a-x, closing the first valve V1 and the second valve V2, and performing no air supply; when a-x≤T1<a, the first valve V1 and the second valve V2 maintain their original states; wherein x is a constant.

[0102] This is a preferred control method according to embodiment 2 of the present invention: that is, when it is detected that the F1 temperature T1 ≥ a, the first valve V1 is opened and the second valve V2 is closed, and air supply is performed through the low pressure cylinder (this indicates that the exhaust temperature is slightly high, the amount of refrigerant in the low pressure stage is relatively small, so it is necessary to appropriately open the valve and perform slight air supply to appropriately reduce the exhaust temperature and prevent excessively high exhaust temperature); when it is detected that T1 < a-x, the first valve V1 and the second valve V2 are closed, and no air supply is performed (this indicates that the exhaust temperature is very low and no air supply is required); when it is detected that the F1 temperature a > T1 ≥ a-x, the first valve V1 and the second valve V2 maintain their original states (this indicates that the exhaust temperature is moderate, and maintaining the current state can ensure that the exhaust temperature is within the required range), which can realize first-stage control, control the opening and closing of the two air supply pipelines according to the exhaust temperature of the first compression device, so that while ensuring that the exhaust temperature of the first compression device is not excessively high and realizing accurate temperature control within a specified range, the air supply amount can also be increased or decreased so that the air supply amount meets the demand, and meanwhile, the heating / cooling capacity of the heat exchanger in the system is ensured to reach the maximum (ensuring that the exhaust temperature is within the specified range and improving the cooling / heating capacity at the same time), and improving the energy efficiency of the heat pump system.

[0103] In some embodiments,

[0104] In said judging step, the relationship between T1 and a second preset temperature b is also judged, where b > a;

[0105] In said controlling step, when T1 ≥ b, said first valve V1 and said second valve V2 are opened, and air supply is performed simultaneously through the air supply port of said first cylinder 11 and the air supply port of the intermediate cavity 12; when T1 < b-x, said first valve V1 is opened and said second valve V2 is closed; when b-x ≤ T1 < b, said first valve V1 and said second valve V2 maintain their original states, and at this time b-x ≥ a.

[0106] This is a further preferred control method in Example 2 of the present invention: when it is detected that the F1 temperature T1≥b, the first valve V1 and the second valve V2 are opened, and gas is supplied through the low-pressure cylinder and the intermediate make-up gas port (this indicates that the discharge temperature is relatively high, and the amount of refrigerant in the low-pressure stage and the intermediate chamber is relatively small, so it is necessary to simultaneously open the gas supply to the first cylinder and the intermediate chamber to reduce the discharge temperature and prevent the discharge temperature from being excessively high); when it is detected that T1<b-x, the first valve V1 is opened and the second valve V2 is closed (this indicates that the discharge temperature is slightly high, and the amount of refrigerant in the low-pressure stage is relatively small, it is only necessary to open the gas supply to the first cylinder for a slight gas supply to appropriately reduce the discharge temperature and prevent the discharge temperature from being excessively high); when it is detected that b>T1≥b-x, the first valve V1 and the second valve V2 maintain their original states, and b-x≥a at this time (this indicates that the discharge temperature is moderate, and maintaining the current state can ensure that the discharge temperature is within the required range), which can realize the control of the discharge temperature of the second stage, and control the opening and closing of the two gas supply pipelines according to the discharge temperature of the first compression device, so that while ensuring that the discharge temperature of the first compression device is not excessively high and achieving accurate temperature control within the specified range, the gas supply amount can also be increased or decreased to make the gas supply amount meet the demand, and at the same time ensure that the heating / cooling capacity of the heat exchanger in the system is maximized (ensuring that the discharge temperature is within the specified range while improving the cooling / heating capacity), thereby improving the energy efficiency of the heat pump system.

[0107] In some embodiments,

[0108] In the detecting step, the second temperature detecting device F2 is further used to detect the discharge temperature T2 of the second compression device 2;

[0109] In the determining step, the relationship between T2 and a third preset temperature c is determined;

[0110] In the controlling step, when T2≥c, the third valve V3 is opened, the fourth valve V4, the fifth valve V5 and the sixth valve V6 are closed, and gas is supplied through the gas supply port of the intermediate chamber 12; when T2<c-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 are all closed; when c-y≤T2<c, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 all maintain their original states; wherein y is a constant.

[0111] This is a preferred control method in Example 2 of the present invention: when it is detected that the F2 temperature T2≥c, open the third valve V3 and close the fourth valve V4, the fifth valve V5 and the sixth valve V6, and perform gas supplement through the intermediate gas supplement port (this indicates that the exhaust temperature of the second compression device is slightly high and the refrigerant amount therein is relatively small, so it is necessary to properly open the valve to perform a small amount of gas supplement, appropriately reduce the exhaust temperature, and prevent excessively high exhaust temperature); when it is detected that T2<c-y, close the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 (this indicates that the exhaust temperature of the second compression device is very low and gas supplement is not required); when it is detected that the F2 temperature c>T2≥c-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain their original states (this indicates that the exhaust temperature of the second compression device is moderate, and maintaining the current state can ensure that the exhaust temperature is within the required range). The method can realize control over the first stage of the second compression device, control the opening and closing of two gas supplement pipelines according to the exhaust temperature of the second compression device, so that while ensuring that the exhaust temperature of the second compression device does not become excessively high and satisfying accurate temperature control within the specified range, the gas supplement amount can also be increased or decreased to make the gas supplement amount meet the demand, and meanwhile ensure that the heating / cooling capacity of the heat exchanger in the system reaches the maximum (ensuring that the exhaust temperature is within the specified interval while improving the cooling / heating capacity), and improve the energy efficiency of the heat pump system.

[0112] In some embodiments,

[0113] In said judging step, the relationship between T2 and the fourth preset temperature d is judged, wherein d>c;

[0114] In said control step, when T2≥d, open said third valve V3 and said fourth valve V4, close said fifth valve V5 and said sixth valve V6, and perform gas supplement through the gas supplement port of said intermediate chamber 12 and the gas supplement port of said second cylinder 13; when T2<d-y, open said third valve V3 and close said fourth valve V4, said fifth valve V5 and said sixth valve V6; when d-y≤T2<d, said third valve V3, said fourth valve V4, said fifth valve V5 and said sixth valve V6 all maintain their original states, wherein d-y≥c.

[0115] This is a further preferred control method of embodiment 2 of the present invention: when it is detected that the F2 temperature T2≥d, the third valve V3 and the fourth valve V4 are opened, the fifth valve V5 and the sixth valve V6 are closed, and gas is supplied through the intermediate gas supply port and the high-pressure cylinder gas supply port (this indicates that the exhaust temperature of the second compression device is relatively high and the refrigerant amount of the second compression device is relatively small, so it is necessary to open the intermediate chamber of the first compression device and the gas supply port of the second cylinder for gas supply at the same time, which can effectively reduce the exhaust temperature of the second compression device and prevent the exhaust temperature from being too high); when it is detected that T2<d-y, the third valve V3 is opened, and the fourth valve V4, the fifth valve V5 and the sixth valve V6 are closed (this indicates that the exhaust temperature of the second compression device is slightly high and the refrigerant amount is relatively small, it is only necessary to open the intermediate chamber of the first compression device for gas supply and perform slight gas supplement, which can appropriately reduce the exhaust temperature of the second compression device and prevent the exhaust temperature from being too high); when it is detected that the F2 temperature d>T2≥d-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain their original states (this indicates that the exhaust temperature of the second compression device is moderate, and maintaining the current state can ensure that the exhaust temperature is within the required range). The present invention can realize control over the exhaust temperature of the second stage of the second compression device (the exhaust temperature of the second stage is higher than that of the first stage), and controls the opening and closing of the two gas supply pipelines of the first compression device according to the exhaust temperature of the second compression device, so that while ensuring that the exhaust temperature of the second compression device is not too high and realizing accurate temperature control within the specified range, the gas supply amount can also be increased or decreased to make the gas supply amount meet the demand, and at the same time ensure that the heating / cooling capacity of the heat exchanger in the system reaches the maximum (ensuring the exhaust temperature is within the specified range and improving the cooling / heating capacity), thereby improving the energy efficiency of the heat pump system.

[0116] In some embodiments,

[0117] In the determining step, the relationship between T2 and a fifth preset temperature e is determined, where e>d;

[0118] In the controlling step, when T2≥e, the third valve V3, the fourth valve V4 and the fifth valve V5 are opened, the sixth valve V6 is closed, and gas is supplied through the gas supply port of the intermediate chamber 12, the gas supply port of the second cylinder 13 and the suction port of the second compression device 2; when it is detected that T2<e-y, the third valve V3 and the fourth valve V4 are opened, and the fifth valve V5 and the sixth valve V6 are closed; when e-y≤T2<e, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 all maintain their original states, and at this time e-y≥d.

[0119] This is a further preferred control method in Example 2 of the present invention: when it is detected that the temperature T2 of F2 satisfies T2≥e, the third valve V3, the fourth valve V4 and the fifth valve V5 are opened, and the sixth valve V6 is closed, and gas is supplemented through the intermediate gas supply port and the high-pressure cylinder gas supply port of the first compression device, and the suction port of the second compression device (this indicates that the exhaust temperature of the second compression device is very high at this time, and it is necessary to simultaneously open the gas supply ports of the intermediate cavity and the second cylinder of the first compression device, and the suction port of the second compression device for simultaneous gas supplementation, so as to effectively reduce the exhaust temperature of the second compression device and prevent the exhaust temperature from being too high); when it is detected that T1<e-y, the third valve V3 and the fourth valve V4 are opened, and the fifth valve V5 and the sixth valve V6 are closed (this indicates that the exhaust temperature of the second compression device is relatively high at this time, it is only necessary to open the gas supply to the intermediate cavity and the second cylinder of the first compression device, which can appropriately reduce the exhaust temperature of the second compression device and prevent the exhaust temperature from being too high); when it is detected that the temperature T2 of F2 satisfies e>T2≥e-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain their original states (this indicates that the exhaust temperature of the second compression device is moderate at this time, and maintaining the current state can ensure that the exhaust temperature is within the required range), which can realize the control of the exhaust temperature of the third stage (the exhaust temperature of the third stage is higher than that of the second stage) of the second compression device. The opening and closing of the two gas supply pipelines of the first compression device and the suction pipeline of the second compression device are controlled according to the exhaust temperature of the second compression device, so that while ensuring that the exhaust temperature of the second compression device is not too high and achieving accurate temperature control within the specified range, the gas supply amount can also be increased or decreased to make the gas supply amount meet the demand, and at the same time ensure that the heating / cooling capacity of the heat exchanger in the system reaches the maximum (ensuring the exhaust temperature is within the specified range can also improve the cooling / heating capacity), thus improving the energy efficiency of the heat pump system.

[0120] In some embodiments,

[0121] In said judging step, the relationship between T2 and the sixth preset temperature f is judged, wherein f>e;

[0122] In said control step, when T2≥f, said third valve V3, said fourth valve V4, said fifth valve V5 and said sixth valve V6 are opened, and gas is supplemented through the gas supply port of said intermediate cavity 12, the gas supply port of said second cylinder 13, the suction port of said second compression device 2 and the gas supply port of said second compression device 2; when T2<f-y, said third valve V3, said fourth valve V4 and said fifth valve V5 are opened, and said sixth valve V6 is closed; when f-y≤T2<f, said third valve V3, said fourth valve V4, said fifth valve V5 and said sixth valve V6 all maintain their original states, and at this time f-y≥e.

[0123] This is a further preferred control method of embodiment 2 of the present invention: when it is detected that the F2 temperature T2≥f, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 are opened, and gas is simultaneously supplied through the intermediate gas supply port and the high-pressure cylinder gas supply port of the first compression device, and the suction port and the gas supply port of the second compression device (this indicates that the exhaust temperature of the second compression device is extremely high at this time, and it is necessary to simultaneously open the intermediate chamber and the second cylinder gas supply port of the first compression device, as well as the suction port and the gas supply port of the second compression device for simultaneous gas supply, so that the exhaust temperature of the second compression device can be effectively reduced, and excessive exhaust temperature thereof can be prevented); when it is detected that T1<f-y, the third valve V3, the fourth valve V4 and the fifth valve V5 are opened, and the sixth valve V6 is closed (this indicates that the exhaust temperature of the second compression device is relatively high at this time, it is only necessary to open the gas supply of the intermediate chamber and the second cylinder of the first compression device, and the suction port of the second compression device, so that the exhaust temperature of the second compression device can be appropriately reduced, and excessive exhaust temperature thereof can be prevented); when it is detected that f-y≤T2<f, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain the original state (this indicates that the exhaust temperature of the second compression device is moderate, and maintaining the current state can ensure that the exhaust temperature is within the required range), which can realize the control over the exhaust temperature of the fourth stage of the second compression device (the exhaust temperature of the fourth stage is higher than that of the third stage). According to the exhaust temperature of the second compression device, the opening and closing of the two gas supply pipelines of the first compression device, as well as the suction pipeline and the gas supply port of the second compression device are controlled, so that on the premise of ensuring that the exhaust temperature of the second compression device is not excessively high and satisfying the accurate temperature control within the specified range, the gas supply amount can also be increased or decreased so that the gas supply amount meets the demand. Meanwhile, it can ensure that the heating / cooling capacity of the heat exchanger in the system is maximized (the cooling / heating capacity can be improved while ensuring that the exhaust temperature is within the specified range), and the energy efficiency of the heat pump system is improved.

[0124] Therefore, the present invention can divide the temperature into a plurality of temperature ranges according to the exhaust temperatures of the first compression device and the second compression device, and realize different gas supply modes for exhaust temperatures in different ranges. Finally, the exhaust temperature can be controlled within the specified temperature range, and accurate control of the exhaust temperature is realized. Meanwhile, the gas supply amount can meet the demand for heating / cooling, and the heating / cooling capacity can be improved to the maximum extent. Through a reasonable gas supply control scheme, the present invention improves the heating / cooling capacity by 5% and increases the energy efficiency by 3%.

[0125] The present invention draws out different gas supply circuits through the first gas supply device (preferably a flash evaporator) and the second gas supply device (preferably a flash evaporator), and realizes different gas supply schemes by detecting the exhaust temperature and controlling the opening and closing of the electromagnetic valves on the circuits, which effectively reduces the exhaust temperature and can accurately control the exhaust temperature, improves the system reliability and enhances the overall performance of the whole machine.

[0126] Remark:

[0127] 1. The multiple parameters of the present invention satisfy f>e>d>c>b>a, where f~a can be between 105 and 70 degrees, or other reasonable values.

[0128] 2. x and y are positive numbers, both in ℃, and satisfy 10>x≥3 and 20>y≥3. There is no size relationship between x and y.

[0129] like Figure 2 The optimal implementation of this invention is as follows:

[0130] Taking the heating cycle as an example, the main circulation path is as follows:

[0131] The first cylinder 11 (low-pressure cylinder) of the first compression unit 1 (low-pressure stage compressor) receives low-temperature, low-pressure refrigerant vapor from the gas-liquid separator 9. After compression in the low-pressure cylinder, the vapor enters the second cylinder 13 (high-pressure cylinder). After secondary compression in the high-pressure cylinder, the vapor passes through the one-way valve 3 and connecting pipes to the suction port of the second compression unit 2 (high-pressure stage compressor). In the second compression unit 2, the vapor is compressed into high-temperature, high-pressure superheated vapor. The vapor then passes through the exhaust port to the four-way valve 7, and then to the second heat exchanger 6 (preferably a water-fluorine heat exchanger). In the water-fluorine heat exchanger, the vapor exchanges heat with low-temperature water and is cooled into high-pressure, medium-temperature liquid refrigerant. The liquid refrigerant then exits from the second heat exchanger 6 and passes through the connecting pipes to the third throttling device E3 (preferably an electronic expansion valve). After throttling and pressure reduction, the vapor enters the second gas replenishment device 5 (preferably a liquid receiver or flash evaporator). In the second gas supply device 5, the liquid refrigerant is subcooled by the flashed vapor refrigerant and reaches the second throttling device E2 (preferably an electronic expansion valve) through the connecting pipe. After being throttled and depressurized again, it enters the first gas supply device 4 (preferably a liquid receiver or flash evaporator). In the first gas supply device 4, the main liquid refrigerant is subcooled and reaches the first throttling device E1 (preferably an electronic expansion valve) through the connecting pipe. After being throttled and depressurized, it becomes a low-pressure vapor-liquid mixture and enters the first heat exchanger 8 (preferably a finned heat exchanger). After absorbing heat in the first heat exchanger 8, it evaporates into a low-pressure vapor refrigerant and enters the four-way valve 7. It then enters the gas-liquid separator 9 through the connecting pipe and then enters the first cylinder 11 (low-pressure cylinder) of the first compression device 1 (low-pressure stage compressor) from the suction port, completing one cycle.

[0132] The corresponding airflow path is as follows:

[0133] The refrigerant vapor from the first gas supply device 4 reaches the low-pressure cylinder gas supply port of the first cylinder 11 through the first valve V1 when the first valve V1 is opened; if the second valve V2 is opened, it enters the intermediate gas supply port of the first compression device 1 through the second valve V2.

[0134] The refrigerant vapor discharged from the second gas supply device 5 passes through the connecting pipeline. When the sixth valve V6 is opened, it passes through the sixth valve V6 and enters the gas supply port of the second compression device 2. When the fifth valve V5 is opened, it passes through the fifth valve V5, mixes with the exhaust gas from the first compression device 1, and then enters the suction port of the second compression device 2. When the third valve V3 is opened, it passes through the third valve V3 and enters the intermediate gas supply port of the first compression device 1. When the fourth valve V4 is opened, it passes through the fourth valve V4 and enters the high-pressure cylinder gas supply port of the first compression device 1. Through the on-off control of the solenoid valves, the refrigerant circulation amount is increased, the discharge temperature is reduced, the capacity and energy efficiency are improved, and the reliability of the whole machine is improved according to different gas supply requirements.

[0135] Logical relationship between solenoid valve on-off control and discharge temperature:

[0136] 1. When it is detected that the F1 temperature T1≥a, open the first valve V1 and close the second valve V2 to supply gas through the low-pressure cylinder; when it is detected that T1<a-x, close the first valve V1 and the second valve V2, and no gas is supplied; when it is detected that a>T1≥a-x for F1 temperature, the first valve V1 and the second valve V2 maintain their original states.

[0137] 2. When it is detected that the F1 temperature T1≥b, open the first valve V1 and the second valve V2 to supply gas through the low-pressure cylinder and the intermediate gas supply port; when it is detected that T1<b-x, open the first valve V1 and close the second valve V2; when it is detected that b>T1≥b-x for F1 temperature, the first valve V1 and the second valve V2 maintain their original states, and b-x≥a at this time.

[0138] 3. When it is detected that the F2 temperature T2≥c, open the third valve V3 and close the fourth valve V4, the fifth valve V5, and the sixth valve V6 to supply gas through the intermediate gas supply port; when it is detected that T2<c-y, close the third valve V3, the fourth valve V4, the fifth valve V5, and the sixth valve V6; when it is detected that c>T2≥c-y for F2 temperature, the third valve V3, the fourth valve V4, the fifth valve V5, and the sixth valve V6 maintain their original states.

[0139] 4. When it is detected that the F2 temperature T2≥d, open the third valve V3 and the fourth valve V4, close the fifth valve V5 and the sixth valve V6 to supply gas through the intermediate gas supply port and the high-pressure cylinder gas supply port; when it is detected that T2<d-y, open the third valve V3 and close the fourth valve V4, the fifth valve V5, and the sixth valve V6; when it is detected that d>T2≥d-y for F2 temperature, the third valve V3, the fourth valve V4, the fifth valve V5, and the sixth valve V6 maintain their original states, and d-y≥c at this time.

[0140] 5. When it is detected that the F2 temperature T2≥e, open the third valve V3, the fourth valve V4 and the fifth valve V5, close the sixth valve V6, and perform gas supplementation through the intermediate gas supply port of the first compression device 1, the high-pressure cylinder gas supply port of the first compression device 1, and the suction port of the second compression device 2; when it is detected that T1<e-y, open the third valve V3 and the fourth valve V4, and close the fifth valve V5 and the sixth valve V6; when it is detected that the F2 temperature e>T2≥e-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain the original state, and at this time, e-y≥d.

[0141] 6. When it is detected that the F2 temperature T2≥f, open the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6, and perform gas supplementation through the intermediate gas supply port of the first compression device 1, the high-pressure cylinder gas supply port of the first compression device 1, the suction port and the gas supply port of the second compression device 2; when it is detected that T1<f-y, open the third valve V3, the fourth valve V4 and the fifth valve V5, and close the sixth valve V6; when it is detected that the F2 temperature f>T2≥f-y, the third valve V3, the fourth valve V4, the fifth valve V5 and the sixth valve V6 maintain the original state, and at this time, f-y≥e.

[0142] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can also be made without departing from the technical principles of the present invention, and these improvements and modifications shall also be regarded as the protection scope of the present invention.

Claims

1. A heat pump unit, characterized in that: include: The first compression device (1) and the second compression device (2), the first air supply device (4) and the second air supply device (5), the first compression device (1) includes a first cylinder (11), an intermediate chamber (12) and a second cylinder (13), the exhaust of the first cylinder (11) enters the intermediate chamber (12), the exhaust of the intermediate chamber (12) enters the second cylinder (13) to form at least two-stage compression, and the exhaust of the first compression device (1) enters the intake port of the second compression device (2); The first air supply device (4) can supply air to the first cylinder (11) and / or the intermediate chamber (12), and the second air supply device (5) can supply air to the intermediate chamber (12) and / or the second cylinder (13). The first air supply device (4) and the second air supply device (5) can control the air supply to the first cylinder (11), the intermediate chamber (12) and the second cylinder (13) according to the exhaust temperature of the first compression device (1).

2. The heat pump unit according to claim 1, characterized in that: The first air supply device (4) can be connected to the air supply port of the first cylinder (11) through the first air supply pipeline (101), and a first valve (V1) is provided on the first air supply pipeline (101). The second air supply device (5) can be connected to the air supply port of the intermediate cavity (12) through the second air supply pipeline (102), and a second valve (V2) is provided on the second air supply pipeline (102). The outlet of the second cylinder (13) is connected to the intake port of the second compression device (2) through the first pipeline (201). The first pipeline (201) is equipped with a first temperature detection device (F1). The first valve (V1) and the second valve (V2) are both control valves. The first valve (V1) and the second valve (V2) are both controlled to open and close according to the exhaust temperature detected by the first temperature detection device (F1).

3. The heat pump unit according to claim 1, characterized in that: The first air supply device (4) can be connected to the air supply port of the first cylinder (11) through the first air supply pipeline (101). A first valve (V1) is provided on the first air supply pipeline (101). The first air supply device (4) can also be connected to the air supply port of the intermediate cavity (12) through the second air supply pipeline (102). A second valve (V2) is provided on the second air supply pipeline (102). The outlet of the second cylinder (13) is connected to the intake port of the second compression device (2) through the first pipeline (201). The first pipeline (201) is equipped with a first temperature detection device (F1). The first valve (V1) and the second valve (V2) are both control valves. The first valve (V1) and the second valve (V2) are both controlled to open and close according to the exhaust temperature detected by the first temperature detection device (F1).

4. The heat pump unit according to claim 3, characterized in that: The second air supply device (5) can be connected to the air supply port of the intermediate cavity (12) through the third air supply pipeline (103). A third valve (V3) is provided on the third air supply pipeline (103). The second air supply device (5) is also connected to the air supply port of the second cylinder (13) through the fourth air supply pipeline (104). A fourth valve (V4) is provided on the third air supply pipeline (103). The outlet of the second compression device (2) is vented through the second pipeline (202). The second pipeline (202) is equipped with a second temperature detection device (F2). The third valve (V3) and the fourth valve (V4) are both control valves. The third valve (V3) and the fourth valve (V4) are both controlled to open and close according to the exhaust temperature detected by the second temperature detection device (F2).

5. The heat pump unit according to claim 4, characterized in that: The second air supply device (5) is also connected to the air intake of the second compression device (2) through the fifth air supply pipeline (105). The fifth air supply pipeline (105) is equipped with a fifth valve (V5). The second air supply device (5) is also connected to the air supply port of the second compression device (2) through the sixth air supply pipeline (106). The sixth air supply pipeline (106) is equipped with a sixth valve (V6). The fifth valve (V5) and the sixth valve (V6) are both control valves. The fifth valve (V5) and the sixth valve (V6) are both controlled to open and close according to the exhaust temperature detected by the second temperature detection device (F2).

6. The heat pump unit according to claim 1, characterized in that: It also includes a first heat exchanger (8), a second heat exchanger (6), a first throttling device (E1), a second throttling device (E2), a third throttling device (E3), a third pipeline (203), a fourth pipeline (204), and a fifth pipeline (205). The first gas supply device (4) is connected to one end of the first heat exchanger (8) through the third pipeline (203). The first throttling device (E1) is installed on the third pipeline (203). The second gas supply device (5) is connected to the first gas supply device (4) through the fourth pipeline (204). The second throttling device (E2) is installed on the fourth pipeline (204). The second gas supply device (5) is connected to one end of the second heat exchanger (6) through the fifth pipeline (205). The third throttling device (E3) is installed on the fifth pipeline (205).

7. The heat pump unit according to claim 6, characterized in that: further comprises a four-way valve (7), a gas-liquid separator (9), a sixth pipeline (206), a seventh pipeline (207), an eighth pipeline (208) and a ninth pipeline (209), wherein an air outlet of the second compression device (2) is communicated with a first end of the four-way valve (7) through a second pipeline (202), the first heat exchanger (8) is communicated with a second end of the four-way valve (7) through the sixth pipeline (206), the second heat exchanger (6) is communicated with a third end of the four-way valve (7) through the seventh pipeline (207), the gas-liquid separator (9) is communicated with a fourth end of the four-way valve (7) through the eighth pipeline (208), and the gas-liquid separator (9) is further communicated with an air suction port of the first compression device (1) through the ninth pipeline (209).

8. A control method for a heat pump unit as described in claim 2, characterized in that: comprising: a detecting step: detecting an exhaust temperature T1 of the first compression device (1) by the first temperature detecting device (F1); a judging step: judging a relationship between T1 and a first preset temperature a; a controlling step: when T1≥a, opening the first valve (V1) and closing the second valve (V2) to perform air supplement through an air supplement port of the first cylinder (11); when T1<a-x, closing the first valve (V1) and the second valve (V2) to stop air supplement; when a-x≤T1<a, keeping the original states of the first valve (V1) and the second valve (V2); wherein x is a constant.

9. The control method according to claim 8, characterized in that: in the judging step, a relationship between T1 and a second preset temperature b is further judged, wherein b>a; in the controlling step, when T1≥b, opening the first valve (V1) and the second valve (V2) to perform air supplement simultaneously through the air supplement port of the first cylinder (11) and an air supplement port of the intermediate cavity (12); when T1<b-x, opening the first valve (V1) and closing the second valve (V2); when b-x≤T1<b, keeping the original states of the first valve (V1) and the second valve (V2), wherein b-x≥a.

10. A control method for a heat pump unit as described in claim 5, characterized in that: comprising: a detecting step: detecting an exhaust temperature T1 of the first compression device (1) by the first temperature detecting device (F1); a judging step: judging a relationship between T1 and a first preset temperature a; a controlling step: when T1≥a, opening the first valve (V1) and closing the second valve (V2) to perform air supplement through an air supplement port of the first cylinder (11); when T1<a-x, closing the first valve (V1) and the second valve (V2) to stop air supplement; when a-x≤T1<a, keeping the original states of the first valve (V1) and the second valve (V2); wherein x is a constant.

11. The control method according to claim 10, characterized in that: in the judging step, a relationship between T1 and a second preset temperature b is further judged, wherein b>a; In the control step, when T1≥b, the first valve (V1) and the second valve (V2) are opened, and air is supplied simultaneously through the air supply port of the first cylinder (11) and the air supply port of the intermediate chamber (12); when T1<b-x, the first valve (V1) is opened and the second valve (V2) is closed; when b-x≤T1<b, the first valve (V1) and the second valve (V2) maintain their original states, and b-x≥a at this time.

12. The control method according to claim 10, characterized in that: In the detecting step, the exhaust temperature T2 of the second compression device (2) is further detected by the second temperature detecting device (F2); In the determining step, the relationship between T2 and a third preset temperature c is determined; In the control step, when T2≥c, the third valve (V3) is opened, and the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) are closed, and air is supplied through the air supply port of the intermediate chamber (12); when T2<c-y, the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) are closed; when c-y≤T2<c, the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) all maintain their original states; wherein y is a constant.

13. The control method according to claim 12, characterized in that: In the determining step, the relationship between T2 and a fourth preset temperature d is determined, wherein d>c; In the control step, when T2≥d, the third valve (V3) and the fourth valve (V4) are opened, and the fifth valve (V5) and the sixth valve (V6) are closed, and air is supplied through the air supply port of the intermediate chamber (12) and the air supply port of the second cylinder (13); when T2<d-y, the third valve (V3) is opened, and the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) are closed; when d-y≤T2<d, the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) all maintain their original states, and d-y≥c at this time.

14. The control method according to claim 13, characterized in that: In the determining step, the relationship between T2 and a fifth preset temperature e is determined, wherein e>d; In the control step, when T2≥e, the third valve (V3), the fourth valve (V4) and the fifth valve (V5) are opened, and the sixth valve (V6) is closed, and air is supplied through the air supply port of the intermediate chamber (12), the air supply port of the second cylinder (13) and the air suction port of the second compression device (2); when T2<e-y is detected, the third valve (V3) and the fourth valve (V4) are opened, and the fifth valve (V5) and the sixth valve (V6) are closed; when e-y≤T2<e, the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) all maintain their original states, and e-y≥d at this time.

15. The control method according to claim 14, characterized in that: in the judging step, a relationship between T2 and a sixth preset temperature f is judged, wherein f>e; in the controlling step, when T2≥f, the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) are opened, and gas is supplemented through a gas supplement port of the intermediate cavity (12), a gas supplement port of the second cylinder (13), a suction port of the second compression device (2) and a gas supplement port of the second compression device (2); when T2<f-y, the third valve (V3), the fourth valve (V4) and the fifth valve (V5) are opened, and the sixth valve (V6) is closed; when f-y≤T2<f, all of the third valve (V3), the fourth valve (V4), the fifth valve (V5) and the sixth valve (V6) maintain original states, wherein f-y≥e.

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