Heat pump unit and control method thereof

Abstract

The invention relates to the technical field of heat pump units, in particular to a heat pump unit and a control method thereof, and aims to solve the problem that the use experience of a user is affected due to the fact that the fluctuation range of the outlet water temperature is large due to unstable operation of an existing heat pump unit. In order to achieve the purpose, the heat pump unit comprises a compressor, a first electromagnetic valve for controlling the compressor to load and a second electromagnetic valve for controlling the compressor to deload; the first electromagnetic valve is powered on to load the compressor, and the second electromagnetic valve is powered on to deload the compressor; the control method comprises the steps that the water inlet temperature T0 of the heat pump unit is obtained; the difference value T obtained by subtracting the preset water inlet temperature T1 from the water inlet temperature T0 of the heat pump unit is calculated; and according to the range where the difference value T is located, the compressor is controlled to be loaded, deloaded or alternately loaded and deloaded, so that the water outlet temperature of the heat pump unit is within the preset stable range. According to the invention, the outlet water temperature can be stabilized in a reasonable range, the large fluctuation change of the outlet water temperature is avoided, and the use experience of a user is improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat pump units, and specifically provides a heat pump unit and a control method thereof. Background Art

[0002] Air source heat pump chillers are based on the reverse Carnot cycle and can convert low-grade heat sources into usable high-value heat sources for heating life through the work of a compressor. They have attracted widespread attention from researchers due to their energy-saving and environmental protection advantages, such as their ability to reduce carbon dioxide emissions.

[0003] The stepless screw air source heat pump unit has a wide energy adjustment range, and has the advantages of smoother capacity changes and more stable systems compared to step-adjustment units, and has better user experience. However, during the energy adjustment process of the stepless compressor, because the slide valve adjustment is not fixed, there will be micro-fluctuations, and the adjustment degree is difficult to control. When the compressor is repeatedly adjusted to increase or decrease load, it will cause serious water temperature fluctuations, affecting the customer experience.

[0004] In summary, the unstable operation of existing heat pump units causes a large fluctuation range of the outlet water temperature, affecting the user experience.

[0005] Accordingly, the art needs a new heat pump unit and a control method thereof to solve the above problems. Summary of the invention

[0006] The present invention aims to solve the above technical problem, that is, to solve the problem that the unstable operation of the existing heat pump unit leads to a large fluctuation range of the outlet water temperature, thereby affecting the user experience.

[0007] In a first aspect, the present invention provides a control method for a heat pump unit, the heat pump unit comprising a compressor and a first solenoid valve for controlling the compressor to load and a second solenoid valve for reducing the load; the first solenoid valve is powered on to load the compressor, and the second solenoid valve is powered on to reduce the load of the compressor;

[0008] The control method comprises:

[0009] Obtaining the water inlet temperature T0 of the heat pump unit;

[0010] Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0011] According to the range of the difference ΔT, the compressor is controlled to load, unload, or alternately load and unload, so that the outlet water temperature of the heat pump unit is within a preset stable range.

[0012] In the preferred technical solution of the above control method, when the unit is in the refrigeration condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" specifically includes:

[0013] If △T≥T2, control the first solenoid valve to power on Y1 at a first preset time interval M1;

[0014] Where T2 is the preset temperature difference.

[0015] In the preferred technical solution of the above control method, when the unit is in the refrigeration condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0016] If (T2) / 2≤△T<T2, control the first solenoid valve to power on Y2 every second preset time interval M2;

[0017] Among them, M1<M2.

[0018] In the preferred technical solution of the above control method, when the unit is in the refrigeration condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0019] If △T≤(-T2), the second solenoid valve is controlled to power on Y3 at a third preset time interval M3; T2 is a preset temperature difference.

[0020] In the preferred technical solution of the above control method, when the unit is in the refrigeration condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0021] If (-T2)<△T≤(-T2) / 2, control the second solenoid valve to power on Y4 every fourth preset time interval M4;

[0022] Among them, M3<M4;

[0023] In the preferred technical solution of the above control method, when the unit is in the heating condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0024] If ΔT≥T2, the second solenoid valve is controlled to power on Y5 at every fifth preset time interval M5, and T2 is the preset temperature difference.

[0025] In the preferred technical solution of the above control method, when the unit is in the heating condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0026] If (T2) / 2≤△T<T2, control the second solenoid valve to power on Y6 every sixth preset time interval M6;

[0027] Among them, M5<M6.

[0028] In the preferred technical solution of the above control method, when the unit is in the heating condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0029] If △T≤(-T2), the first solenoid valve is controlled to power on Y7 at every seventh preset time interval M7, and T2 is the preset temperature difference.

[0030] In the preferred technical solution of the above control method, when the unit is in the heating condition, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0031] If (-T2)<△T≤(-T2) / 2, control the first solenoid valve M8 to power on Y8 every eighth preset time interval;

[0032] Among them, M7<M8.

[0033] In the preferred technical solution of the above control method, the step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes:

[0034] If |△T|<(T2) / 2, then obtain the load value change of the heat pump unit, wherein T2 is the preset temperature difference;

[0035] If the load value of the heat pump unit increases, the second solenoid valve is controlled to be powered on at Y9 every ninth preset time interval M9;

[0036] and / or,

[0037] If the load value of the heat pump unit decreases, the first solenoid valve is controlled to be powered on Y9 at intervals of a ninth preset time M9.

[0038] In the preferred technical solution of the above control method, the step of "obtaining the water inlet temperature T0 of the heat pump unit" further includes:

[0039] Obtaining the exhaust pressure and suction pressure of the compressor;

[0040] If the exhaust pressure of the compressor is less than or equal to the first preset pressure, and the suction pressure of the compressor is greater than or equal to the second preset pressure, then obtaining the water inlet temperature T0 of the heat pump unit;

[0041] The first preset pressure is greater than the second preset pressure.

[0042] In the preferred technical solution of the above control method, the control method further includes:

[0043] When the heat pump unit performs high-temperature cooling, if the exhaust pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so as to reduce the load of the compressor.

[0044] In the preferred technical solution of the above control method, the step of "if the exhaust pressure of the compressor is greater than the first preset pressure, controlling the second solenoid valve to operate so as to reduce the load of the compressor" specifically includes:

[0045] At every tenth preset time interval M10, the second solenoid valve is controlled to be powered on Y10.

[0047] In the preferred technical solution of the above control method, the step of “if the exhaust pressure of the compressor is greater than the first preset pressure, controlling the second solenoid valve to operate” further includes:

[0048] After the second solenoid valve is powered on for a first preset number of times, the second solenoid valve is controlled to stop being powered on.

[0049] In the preferred technical solution of the above control method, the control method further includes:

[0050] When the heat pump unit performs low-temperature heating,

[0051] If the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so as to load the compressor.

[0052] In the preferred technical solution of the above control method, the step of "if the suction pressure of the compressor is less than the second preset pressure, controlling the first solenoid valve to work so that the compressor is loaded" specifically includes:

[0053] The first solenoid valve is controlled to be powered on Y11 at every eleventh preset time interval M11.

[0054] In the preferred technical solution of the above control method, the step of “if the suction pressure of the compressor is less than the second preset pressure, controlling the first solenoid valve to operate” further includes:

[0055] After the first solenoid valve is powered on for a second preset number of times, the first solenoid valve is controlled to stop being powered on.

[0056] In the preferred technical solution of the above control method, the exhaust pressure and suction pressure of the compressor are obtained;

[0057] Calculating the pressure ratio of the compressor as the ratio of the exhaust pressure to the suction pressure;

[0058] The power-on time Y of the first solenoid valve or the second solenoid valve is determined by the following formula;

[0059] Where, Y is the power-on time, in seconds;

[0060] When the first solenoid valve is powered on, X is the pressure ratio of the compressor before the first solenoid valve is powered on;

[0061] When the second solenoid valve is powered on, X is the pressure ratio of the compressor before the second solenoid valve is powered on;

[0062] t is the unit time 1s;

[0063] a, b, c, j, and k are constants.

[0064] In a second aspect, the present invention further provides a heat pump unit, the heat pump unit comprising a controller, the controller being configured to execute the control method of the heat pump unit described in any one of the above-mentioned preferred technical solutions.

[0065] In the case of adopting the above technical solution, the heat pump unit of the present invention includes a compressor and a first solenoid valve for controlling the compressor to load and a second solenoid valve for reducing the load; the first solenoid valve is powered on to load the compressor, and the second solenoid valve is powered on to reduce the load of the compressor; the control method of the present invention includes: obtaining the inlet water temperature T0 of the heat pump unit; calculating the difference △T between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1; according to the range of the difference △T, controlling the compressor to load, reduce the load, or alternately add and reduce the load, so that the outlet water temperature of the heat pump unit is within a preset stable range. According to the comparison result of the difference between the inlet water temperature and the preset inlet water temperature and the preset temperature difference, the present invention controls the compressor to load, reduce the load, or alternately add and reduce the load accordingly, so that the outlet water temperature is stable within a reasonable range, avoiding large fluctuations in the outlet water temperature, and improving the user experience.

[0066] Furthermore, the present invention controls the second solenoid valve to operate to reduce the load on the compressor when the exhaust pressure of the compressor is greater than a first preset pressure when the heat pump unit is performing high-temperature cooling. This enables the heat pump unit to always operate in a stable state, thereby improving the stability of the unit.

[0067] Furthermore, the present invention controls the first solenoid valve to operate so as to load the compressor when the suction pressure of the compressor is less than a second preset pressure when the heat pump unit is performing low-temperature heating. This enables the heat pump unit to always operate in a stable state, thereby improving the stability of the unit.

[0068] Solution 1. A control method for a heat pump unit, characterized in that the heat pump unit comprises a compressor and a first solenoid valve for controlling the compressor to load and a second solenoid valve for reducing the load; the first solenoid valve is powered on to load the compressor, and the second solenoid valve is powered on to reduce the load of the compressor;

[0069] The control method comprises:

[0070] Obtaining the water inlet temperature T0 of the heat pump unit;

[0071] Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0072] According to the range of the difference ΔT, the compressor is controlled to load, unload, or alternately load and unload, so that the outlet water temperature of the heat pump unit is within a preset stable range.

[0073] Solution 2. The control method according to Solution 1 is characterized in that, when the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" specifically includes:

[0074] If △T≥T2, control the first solenoid valve to power on Y1 at a first preset time interval M1;

[0075] Where T2 is the preset temperature difference.

[0076] Solution 3. The control method according to Solution 2 is characterized in that, when the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0077] If (T2) / 2≤△T<T2, control the first solenoid valve to power on Y2 every second preset time interval M2;

[0078] Among them, M1<M2.

[0079] Solution 4. The control method according to Solution 1 is characterized in that, when the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0080] If △T≤(-T2), the second solenoid valve is controlled to power on Y3 at a third preset time interval M3; T2 is a preset temperature difference.

[0081] Solution 5. The control method according to Solution 4 is characterized in that, when the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0082] If (-T2)<△T≤(-T2) / 2, control the second solenoid valve to power on Y4 every fourth preset time interval M4;

[0083] Among them, M3<M4;

[0084] Solution 6. The control method according to Solution 1 is characterized in that, when the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0085] If ΔT≥T2, the second solenoid valve is controlled to power on Y5 at every fifth preset time interval M5, and T2 is the preset temperature difference.

[0086] Solution 7. The control method according to Solution 6 is characterized in that, when the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0087] If (T2) / 2≤△T<T2, control the second solenoid valve to power on Y6 every sixth preset time interval M6;

[0088] Among them, M5<M6.

[0089] Solution 8. The control method according to Solution 1 is characterized in that, when the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0090] If △T≤(-T2), the first solenoid valve is controlled to power on Y7 at every seventh preset time interval M7, and T2 is the preset temperature difference.

[0091] Solution 9. The control method according to Solution 8 is characterized in that, when the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0092] If (-T2)<△T≤(-T2) / 2, control the first solenoid valve M8 to power on Y8 every eighth preset time interval;

[0093] Among them, M7<M8.

[0094] Solution 10. The control method according to Solution 1 is characterized in that the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes:

[0095] If |△T|<(T2) / 2, then obtain the load value change of the heat pump unit, wherein T2 is the preset temperature difference;

[0096] If the load value of the heat pump unit increases, the second solenoid valve is controlled to be powered on at Y9 every ninth preset time interval M9;

[0097] and / or,

[0098] If the load value of the heat pump unit becomes smaller, the first solenoid valve is controlled to be powered on Y9 at intervals of the ninth preset time M9.

[0099] Solution 11. The control method according to Solution 1 is characterized in that the step of "obtaining the water inlet temperature T0 of the heat pump unit" further comprises:

[0100] Obtaining the exhaust pressure and suction pressure of the compressor;

[0101] If the exhaust pressure of the compressor is less than or equal to the first preset pressure, and the suction pressure of the compressor is greater than or equal to the second preset pressure, then obtaining the water inlet temperature T0 of the heat pump unit;

[0102] The first preset pressure is greater than the second preset pressure.

[0103] Solution 12. The control method according to Solution 11, characterized in that the control method further comprises:

[0104] When the heat pump unit performs high-temperature cooling, if the exhaust pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so as to reduce the load of the compressor.

[0105] Solution 13. The control method according to Solution 12 is characterized in that the step of "if the exhaust pressure of the compressor is greater than the first preset pressure, controlling the second solenoid valve to operate so as to reduce the load of the compressor" specifically includes:

[0106] At every tenth preset time interval M10, the second solenoid valve is controlled to be powered on Y10.

[0107] Solution 14. The control method according to Solution 13 is characterized in that the step of “if the exhaust pressure of the compressor is greater than the first preset pressure, controlling the second solenoid valve to operate” further includes:

[0108] After the second solenoid valve is powered on for a first preset number of times, the second solenoid valve is controlled to stop being powered on.

[0109] Solution 15. The control method according to Solution 11, characterized in that the control method further comprises:

[0110] When the heat pump unit performs low-temperature heating,

[0111] If the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so as to load the compressor.

[0112] Solution 16. The control method according to Solution 15 is characterized in that the step of "if the suction pressure of the compressor is less than the second preset pressure, controlling the first solenoid valve to work so that the compressor is loaded" specifically includes:

[0113] The first solenoid valve is controlled to be powered on Y11 at every eleventh preset time interval M11.

[0114] Solution 17. The control method according to Solution 16 is characterized in that the step of “if the suction pressure of the compressor is less than the second preset pressure, controlling the first solenoid valve to operate” further comprises:

[0115] After the first solenoid valve is powered on for a second preset number of times, the first solenoid valve is controlled to stop being powered on.

[0116] Solution 18. The control method according to any one of solutions 1 to 17, characterized in that:

[0117] Obtaining the exhaust pressure and suction pressure of the compressor;

[0118] Calculating the pressure ratio of the compressor as the ratio of the exhaust pressure to the suction pressure;

[0119] The power-on time Y of the first solenoid valve or the second solenoid valve is determined by the following formula;

[0120] Where, Y is the power-on time, in seconds;

[0121] When the first solenoid valve is powered on, X is the pressure ratio of the compressor before the first solenoid valve is powered on;

[0122] When the second solenoid valve is powered on, X is the pressure ratio of the compressor before the second solenoid valve is powered on;

[0123] t is the unit time 1s;

[0124] a, b, c, j, and k are constants.

[0125] Solution 19. A heat pump unit, characterized in that the heat pump unit includes a controller, and the controller is configured to execute the control method of the heat pump unit described in any one of Solutions 1 to 18 above. BRIEF DESCRIPTION OF THE DRAWINGS

[0126] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which:

[0127] Figure 1 It is a flow chart of the main steps of the control method of the heat pump unit of the present invention;

[0128] Figure 2is a flow chart of the steps of the heat pump unit of the present invention under refrigeration conditions;

[0129] Figure 3 is a flow chart of the steps of the heat pump unit of the present invention under heating conditions;

[0130] Figure 4 It is a comparison diagram of the heat pump unit of the present invention under heating condition and cooling condition;

[0131] Figure 5 1 is a schematic diagram of the principle of the compressor loading damping pipeline of the heat pump unit of the first preferred embodiment of the present invention;

[0132] Figure 6 Schematic diagram of the principle of the compressor loading damping pipeline of the heat pump unit of the second preferred embodiment of the present invention;

[0133] Reference numerals:

[0134] 1. First solenoid valve; 2. Second solenoid valve; 3. First oil pipeline; 4. Second oil pipeline; 5. Piston; 6. Sliding valve; 7. Screw; 8. Main pipeline. DETAILED DESCRIPTION

[0135] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0136] It should be noted that, in the description of the present invention, the terms "front", "rear", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are merely for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, it should be noted that, in the description of the present invention, the terms "first", "second", "third", "fourth", "fifth", "sixth", "seventh", "eighth", "ninth", "tenth", and "eleventh" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0137] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0138] First, refer to 5. The heat pump unit of the present invention includes a compressor and a first solenoid valve 1 for controlling the loading of the compressor and a second solenoid valve 2 for reducing the load; the first solenoid valve 1 is powered on to load the compressor, and the second solenoid valve 2 is powered on to reduce the load of the compressor; specifically, the slide valve 6 is connected to the piston 5, and the chamber where the piston 5 is located is connected to the first oil pipeline 3 and the second oil pipeline 4 respectively. The first solenoid valve 1 is arranged on the first oil pipeline 3, and the second solenoid valve 2 is arranged on the second oil pipeline 4. When the first solenoid valve 1 is powered on, the first oil pipeline 3 supplies oil, so that the piston 5 moves forward, so that the slide valve 6 of the compressor is pushed forward, and the amount of the compression chamber where the screw 7 is located is increased, so that the closed chamber formed by the compressor becomes larger, and then the operating capacity of the compressor becomes larger. When the second solenoid valve 2 is powered on, the second oil pipeline 4 leaks oil, so that the piston 5 moves backward, so that the slide valve 6 of the compressor moves backward, so that the closed chamber formed by the compressor becomes smaller, and then the operating capacity of the compressor becomes smaller.

[0139] It can be understood by those skilled in the art that the first oil pipeline 3 and the second oil pipeline 4 can be connected to the chamber where the piston 5 is located through the main pipeline 8, or can be connected as follows: Figure 6 As shown, the first oil pipeline 3 and the second oil pipeline 4 are both individually connected to the chamber where the piston 5 is located, and those skilled in the art can set them according to actual conditions.

[0140] by Figure 5 The direction shown is the reference direction. The first oil pipeline 3 can be the return oil in the heat pump unit system, and the second oil pipeline 4 is connected to the suction port of the compressor. Therefore, when the first solenoid valve 1 is powered on, the first oil pipeline 3 is connected to the chamber where the piston 5 is located. The first oil pipeline 3 is high-pressure oil, and the pressure is greater than the pressure on the front side of the piston 5, which pushes the piston 5 and the slide valve 6 to move forward, and the compressor is loaded; when the second solenoid valve 2 is powered on, the second oil pipeline 4 is connected to the chamber where the piston 5 is located. Since the second oil pipeline 4 is connected to the suction port of the compressor, the pressure on the front side of the piston 5 is greater than the pressure on the rear side, causing the second oil pipeline 4 to leak oil, the piston 5 and the slide valve 6 to move backward, and the compressor is unloaded.

[0141] In another preferred embodiment, the first oil pipeline 3 is connected to the oil supply device to provide high-pressure oil to achieve the purpose of pushing the piston 5 and the sliding valve 6 to move forward, and the second oil pipeline 4 is connected to the oil drain end (oil drain tank or oil drain box) so that the pressure of the second oil pipeline 4 is low when the second solenoid valve 2 is powered on, thereby achieving the purpose of draining oil to move the piston 5 and the sliding valve 6 backward.

[0142] The heat pump unit of the present invention further comprises a controller, which is configured to control all operations of the heat pump unit.

[0143] Those skilled in the art will appreciate that the present invention does not impose any limitations on the specific structure and model of the controller, and the controller may be either an original controller of the heat pump unit or a controller separately provided for executing the control method of the present invention. The technician may set the structure and model of the controller according to actual usage requirements.

[0144] See also Figure 1 The control method of the heat pump unit of the present invention mainly includes the following steps:

[0145] Step S1: Obtain the water inlet temperature T0 of the heat pump unit;

[0146] Step S2: Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0147] Step S3: According to the range of the difference △T, the compressor is controlled to load, reduce load or alternately load and reduce load, so that the outlet water temperature of the heat pump unit is within a preset stable range.

[0148] Further, in step S1, the water inlet temperature T0 at the shell and tube evaporator of the heat pump unit is obtained by a temperature sensor, that is, the temperature of water that has not undergone heat exchange treatment. After the water inlet temperature T0 is obtained, the information of the water inlet temperature T0 is transmitted to the controller of the heat pump unit. In step S2, the water inlet temperature T1 is preset to a value set by the user, and the calculation module in the controller calculates the difference △T of T0-T1, and then enters step S3. In step S3, if the difference of |△T| is within the preset range under the refrigeration condition, the first solenoid valve 1 and the second solenoid valve 2 are controlled to work alternately to maintain the current working state of the compressor. If △T is If △T is positive and is not within the preset range, the first solenoid valve 1 is controlled to work so that the compressor is loaded; if △T is negative and is not within the preset range, the second solenoid valve 2 is controlled to work so that the compressor is unloaded; if under the heating condition, the difference of |△T| is within the preset range, the first solenoid valve 1 and the second solenoid valve 2 are controlled to work alternately so that the compressor maintains the current working state; if △T is positive and is not within the preset range, the second solenoid valve 2 is controlled to work so that the compressor is unloaded; if △T is negative and is not within the preset range, the first solenoid valve 1 is controlled to work so that the compressor is loaded.

[0149] Through the above control method, the present invention can ensure that the outlet water temperature is stable within a reasonable range, avoid large fluctuations in the outlet water temperature, and improve the user experience.

[0150] In step S2, the user can also preset the water outlet temperature through the controller or software, and obtain the required water inlet temperature by subtracting the temperature change difference from the preset water outlet temperature. Technical personnel in this field can set it according to actual conditions.

[0151] See next Figure 2 and Figure 4 ,like Figure 2 As shown, the control method of the heat pump unit of the present invention comprises the following steps under refrigeration conditions:

[0152] Step S101: obtaining the water inlet temperature T0 of the heat pump unit;

[0153] Step S102: Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0154] Step S103: if △T≥T2, control the first solenoid valve to power on Y1 at a first preset time interval M1;

[0155] Step S104: if (T2) / 2≤△T<T2, control the first solenoid valve to power on Y2 at every second preset time interval M2;

[0156] Step S105: if △T≤(-T2), control the second solenoid valve to power on Y3 at every third preset time interval M3;

[0157] Step S106: If (-T2)<ΔT≤(-T2) / 2, control the second solenoid valve to power on Y4 at every fourth preset time interval M4.

[0158] For example, Figure 4 As shown in , T2 is the preset temperature difference, the preset temperature difference T2 is 4°C, the preset inlet water temperature T1 is 10°C, and under the refrigeration condition, if the inlet water temperature T0 is greater than or equal to 14°C, then △T=T0-T1≥T2, and then enter step S103, control the first solenoid valve 1 to power on Y1 every first preset time M1, so that the compressor enters the fast loading stage, wherein Y1 is the power-on time of the first solenoid valve 1; because under the refrigeration condition, the inlet water temperature is generally lower than the outlet water temperature, if the inlet water temperature is higher than the preset inlet water temperature and the difference is large, it is necessary to increase the refrigeration capacity of the heat pump unit in order to meet the user's desired outlet water temperature after water heat exchange. In step S103, the compressor quickly loads to increase the refrigeration capacity of the heat pump unit to ensure that the outlet water temperature of the heat unit is within the preset range.

[0159] Under the refrigeration condition, if 12℃≤water inlet temperature T0<14℃, then (T2) / 2≤△T<T2, and then enter step S104, control the first solenoid valve 1 to power on Y2 every second preset time M2, so that the compressor enters the slow loading stage, Y2 is the power-on time of the first solenoid valve 1, and at this time, under the refrigeration condition, the inlet water temperature is higher than the preset inlet water temperature, and the refrigeration capacity of the heat pump unit still needs to be improved, but because the difference between the inlet water temperature and the preset inlet water temperature is small, so in step S104, control the compressor to slowly load to improve the refrigeration capacity of the heat pump unit can ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0160] Wherein, M1<M2, so that step S103 is a fast loading stage of the compressor, and step S104 is a slow loading stage of the compressor.

[0161] Continue reading Figure 2 and Figure 4 Under refrigeration conditions, if the inlet water temperature T0≤6℃, then △T≤(-T2). At this time, enter step S105, control the second solenoid valve 2 to power on Y3 every third preset time M3, Y3 is the power-on time of the second solenoid valve 2, so that the compressor enters the rapid load reduction stage. Under refrigeration conditions, if the inlet water temperature is lower than the preset inlet water temperature, the heat pump unit reduces its refrigeration capacity to meet the user's required water outlet temperature after water heat exchange. Therefore, in step S105, if the inlet water temperature is lower than the preset inlet water temperature, and the difference between the two is large, the compressor enters the rapid load reduction stage to reduce the refrigeration capacity of the heat pump unit, avoid the outlet water temperature after heat exchange being too low, and ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0162] Under the refrigeration condition, if 6℃<water inlet temperature T0≤8℃, then (-T2)<△T≤(-T2) / 2. At this time, enter step S106, control the second solenoid valve 2 to power on Y4 every fourth preset time M4, Y4 is the power-on time of the second solenoid valve 2, so that the compressor enters the slow load reduction stage. Under the refrigeration condition, the inlet water temperature is lower than the preset inlet water temperature, and the refrigeration capacity of the heat pump unit still needs to be reduced, but the difference between the two is small, so in step S106, control the compressor to slowly reduce the load to reduce the refrigeration capacity of the heat pump unit, which can ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0163] Wherein, M3<M4, so that step S105 is a rapid load reduction for the compressor, and step S106 is a slow load reduction for the compressor.

[0164] It should be noted that the present invention does not impose any restriction on the specific values ​​of the first preset time M1, the second preset time M2, the third preset time M3, and the fourth preset time M4. The value range of the first preset time M1 is 3-4s, the value range of the second preset time M2 is 5-10s, the value range of the third preset time M3 is 3-4s, and the value range of the fourth preset time M4 is 5-10s. Of course, M1, M2, M3, and M4 can also be other values, M1 and M3 can be the same or different, and M2 and M4 can be the same or different; as long as M1<M2, M3<M4 are satisfied, technical personnel in this field can set it according to actual conditions.

[0165] See next Figure 3 and Figure 4 The control method of the heat pump unit of the present invention comprises the following steps under heating conditions:

[0166] Step S101: obtaining the water inlet temperature T0 of the heat pump unit;

[0167] Step S102: Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0168] Step S107: if △T≥T2, control the second solenoid valve to power on Y5 at every fifth preset time interval M5;

[0169] Step S108: if (T2) / 2≤△T<T2, control the second solenoid valve M6 to power on Y6 at every sixth preset time interval;

[0170] Step S109: if △T≤(-T2), control the first solenoid valve M7 to power on Y7 at every seventh preset time interval;

[0171] Step S110: If (-T2)<ΔT≤(-T2) / 2, control the first solenoid valve M8 to power on Y8 at every eighth preset time interval.

[0172] For example, Figure 4As shown in , T2 is the preset temperature difference, the preset temperature difference T2 is 4°C, the preset inlet water temperature T1 is 10°C, and under heating conditions, if the inlet water temperature T0>14°C, then △T≥T2, and enter step S107, then control the second solenoid valve 2 to power on Y5 every fifth preset time M5, Y5 is the power-on time of the second solenoid valve 2, under heating conditions, the inlet water temperature is generally lower than the preset inlet water temperature. If the inlet water temperature is greater than the preset inlet water temperature and the difference is large, it is easier for the heat pump unit to obtain the outlet water temperature desired or set by the user after heat exchange at the inlet water temperature, so the second solenoid valve 2 is powered on, causing the compressor to enter a rapid load reduction stage, quickly reducing the heating capacity of the heat pump unit, reducing the operating cost of the heat pump unit, and ensuring that the outlet water temperature is stable within a reasonable range to meet the user's water demand.

[0173] If 12℃≤water inlet temperature T0<14℃, then (T2) / 2≤△T<T2. At this time, enter step S108, control the second solenoid valve 2 to power on Y6 every sixth preset time M6, Y6 is the power-on time of the second solenoid valve 2, and under the heating condition, if the water inlet temperature is greater than the preset water inlet temperature, and the difference between the two is small, control the compressor to enter the slow load reduction stage, slowly reduce the heating capacity of the heat pump unit, reduce the operating cost of the heat pump unit, and ensure that the outlet water temperature is stable within a reasonable range to meet the user's water demand.

[0174] Among them, M5<M6, so that step S107 is a stage of rapid deloading of the compressor, and step S108 is a stage of slow deloading of the compressor.

[0175] Under the heating condition, if the inlet water temperature T0≤6℃, then △T≤(-T2), and enter step S109 to control the first solenoid valve 1 to power on Y7 every seventh preset time M7, where Y7 is the power-on time of the first solenoid valve 1. Under the heating condition, if the inlet water temperature is lower than the preset inlet water temperature, the heat pump unit needs to increase its heating capacity so that the water reaches the user's desired or preset outlet water temperature after heat exchange. If the inlet water temperature is lower than the preset inlet water temperature and the difference is large, enter step S109, the compressor fast loading stage, and increase the heating capacity of the heat pump unit to ensure that the outlet water temperature is within a reasonable range to meet the user's water demand.

[0176] Under the heating condition, if 6℃<water inlet temperature T0≤8℃, then (-T2)<△T≤(-T2) / 2, and enter step S110 to control the first solenoid valve 1 to power on Y8 every eighth preset time M8, where Y8 is the power-on time of the first solenoid valve 1. If the water inlet temperature is lower than the preset water inlet temperature, the heat pump unit needs to increase the heating capacity of the booster so that the water reaches the user's desired or preset water outlet temperature after heat exchange. If the water inlet temperature is lower than the preset water inlet temperature and the difference is small, enter step S110, the compressor slow loading stage, and increase the heating capacity of the heat pump unit to ensure that the water outlet temperature is within a reasonable range to meet the user's water demand.

[0177] Among them, M7<M8, so that step S109 is a fast loading stage of the compressor, and step S110 is a slow loading stage of the compressor.

[0178] It should be noted that the present invention does not impose any restriction on the specific values ​​of the fifth preset time M5, the sixth preset time M6, the seventh preset time M7, and the eighth preset time M8. The value range of the fifth preset time M5 is 3-4s, the value range of the sixth preset time M6 is 5-10s, the value range of the seventh preset time M7 is 3-4s, and the value range of the eighth preset time M8 is 5-10s. Of course, M5, M6, M7, and M8 can also be other values, M5 and M7 can be the same or different, and M6 and M8 can be the same or different; as long as M5<M6, M7<M8 are satisfied, technical personnel in this field can set it according to actual conditions.

[0179] Furthermore, the control method of the present invention further includes:

[0180] Step S111: if |△T|<(T2) / 2, then obtain the load value change of the heat pump unit;

[0181] Step S112: if the load value of the heat pump unit increases, the second solenoid valve M9 is controlled to power on Y9 at intervals of a ninth preset time;

[0182] Step S113: if the load value of the heat pump unit decreases, the first solenoid valve is controlled to be powered on Y9 at intervals of the ninth preset time M9.

[0183] See also Figure 4 For example, the preset temperature difference T2 is 4°C, and the preset inlet water temperature T1 is 10°C. Regardless of the heating condition or the cooling condition, if 8°C < inlet water temperature T0 < 12°C, then |△T| < (T2) / 2. At this time, the difference between the inlet water temperature and the preset inlet water temperature is within the preset difference range. Therefore, the current working state of the compressor can be maintained at this time. When maintaining the current working state of the compressor, the first solenoid valve 1 and the second solenoid valve 2 are both in the closed state.

[0184] The load value change is detected by the computer board of the heat pump unit. If the load value increases, step S111 is entered to control the second solenoid valve 2 to power on Y9 at the ninth preset time interval M9, where Y9 is the power-on time of the second solenoid valve 2. The second solenoid valve 2 controls the compressor to reduce the load to maintain the current working state of the compressor; if the load value decreases, step S113 is entered to control the first solenoid valve 1 to power on Y9 at the ninth preset time interval M9, where Y9 is the power-on time of the first solenoid valve 1. The first solenoid valve 1 controls the compressor to increase the load to maintain the current working state of the compressor.

[0185] It should be noted that the present invention does not impose any restrictions on the specific values ​​of the preset water inlet temperature T1 and the preset temperature difference T2. The preset water inlet temperature T1 can be set according to actual conditions, and the preset temperature difference can also be 2°C or 3°C. Of course, it can also be other values. Technical personnel in this field can set them according to actual conditions.

[0186] In addition, it should be noted that the present invention does not impose any limitation on the specific value of M9. The specific value range of M9 is 1.5s-2.5s. Of course, it can also be other values, and those skilled in the art can set it according to actual conditions.

[0187] Furthermore, the control method of the present invention further includes:

[0188] Step S201: Obtain the exhaust pressure and suction pressure of the compressor.

[0189] Step S202: If the exhaust pressure of the compressor is less than or equal to the first preset pressure, and the suction pressure of the compressor is greater than or equal to the second preset pressure, then enter step S101: obtain the inlet water temperature T0 of the heat pump unit; the first preset pressure is greater than the second preset pressure.

[0190] Step S203: When the heat pump unit performs high-temperature cooling, if the exhaust pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so as to reduce the load of the compressor;

[0191] Step S2031: Control the second solenoid valve 2 to power on Y10 at every tenth preset time interval M10;

[0192] Step S2032: After the second solenoid valve is powered on for a first preset number of times, controlling the second solenoid valve to stop being powered on;

[0193] Step S204: when the heat pump unit is performing low-temperature heating, if the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so as to load the compressor;

[0194] Step S2041: Controlling the first solenoid valve to power on Y11 at every eleventh preset time interval M11;

[0195] Step S2042: After the first solenoid valve 1 is powered on for a second preset number of times, the first solenoid valve is controlled to stop being powered on.

[0196] Specifically, the first preset pressure is the maximum limit value of the exhaust pressure. If the exhaust pressure is greater than the first preset pressure, the second solenoid valve 2 is controlled to work to reduce the load of the compressor and reduce the exhaust pressure of the compressor, so that the unit can operate more stably; the second preset pressure is the minimum limit value of the suction pressure. If the exhaust pressure is less than the second preset pressure, the first solenoid valve 1 is controlled to work to increase the suction pressure of the compressor, so that the unit can operate more stably.

[0197] Preferably, the range of the tenth preset time M10 and the eleventh preset time M11 is 1-2s, and the first preset number and the second preset number are both 5 times. Of course, the values ​​of M10 and M11 and the first preset number and the second preset number are both 5 times can also be other values, and technical personnel in this field can set them according to actual conditions.

[0198] Furthermore, the control method of the present invention further comprises the following steps:

[0199] Step S301: Obtain the exhaust pressure and suction pressure of the compressor;

[0200] Step S302: Calculate the pressure ratio of the compressor as the ratio of the exhaust pressure to the suction pressure;

[0201] Step S303: Determine the power-on time Y of the first solenoid valve or the second solenoid valve by the following formula;

[0202] Y=(aX j +bX k +c)t (1)

[0203] Where, Y is the power-on time, in seconds;

[0204] When the first solenoid valve is powered on, X is the pressure ratio of the compressor before the first solenoid valve is powered on;

[0205] When the second solenoid valve is powered on, X is the pressure ratio of the compressor before the second solenoid valve is powered on;

[0206] t is the unit time 1s;

[0207] a, b, c, j, and k are constants.

[0208] Regarding formula (1), those skilled in the art can obtain the values ​​of a, b, c, j, and k by taking multiple sets of data and substituting them into formula (1) according to the power-on time of the first solenoid valve 1 when the load value of the computer board of the heat pump unit is loaded with 1% under different pressure ratios (ratio of the exhaust pressure of the compressor to the suction pressure). Y1, Y2, Y7, Y8, Y11 and the power-on time Y9 of the first solenoid valve 1 are calculated using the above formula (1), and the power-on time Y of the first solenoid valve 1 at each preset time interval corresponds to the pressure ratio of the compressor before the first solenoid valve 1 is powered on.

[0209] According to the power-on time of the second solenoid valve 2 when the load value of the computer board of the heat pump unit is reduced by 1% under different pressure ratios (the ratio of the exhaust pressure of the compressor to the suction pressure), multiple sets of data are taken into formula (1) to obtain the values ​​of a, b, c, j, and k; Y3, Y4, Y5, Y6, Y10 and the power-on time Y9 of the second solenoid valve 2 are calculated using the above formula (1), and the power-on time Y of the second solenoid valve 2 at each preset time interval corresponds to the pressure ratio of the compressor before the second solenoid valve 2 is powered on.

[0210] By controlling the power-on time of the first solenoid valve 1 or the second solenoid valve 2 through the above formula, the stability of the operation of the heat pump unit can be ensured.

[0211] In the control method described above, unless otherwise specified, when the first solenoid valve 1 is in the power-on activation state, the second solenoid valve 2 is in the closed state; when the second solenoid valve 2 is in the power-on activation state, the first solenoid valve 1 is in the closed state.

[0212] In a second aspect, the present invention further claims protection for a heat pump unit, the heat pump unit comprising a controller, the controller being configured to be able to execute the control method of the heat pump unit described in any one of the above preferred embodiments.

[0213] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A control method for a heat pump unit, characterized in that: The heat pump unit comprises a compressor and a first solenoid valve for controlling the compressor to load and a second solenoid valve for reducing the load; When the first solenoid valve is powered on, the compressor is loaded, and when the second solenoid valve is powered on, the compressor is unloaded; The control method comprises: Obtaining the water inlet temperature T0 of the heat pump unit; Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1; According to the range of the difference ΔT, the compressor is controlled to load, unload, or alternately load and unload, so that the outlet water temperature of the heat pump unit is within a preset stable range.

2. The control method according to claim 1, characterized in that: When the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" specifically includes: If △T≥T2, control the first solenoid valve to power on Y1 at a first preset time interval M1; Where T2 is the preset temperature difference.

3. The control method according to claim 2, characterized in that: When the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If (T2) / 2≤△T<T2, control the first solenoid valve to power on Y2 every second preset time interval M2; Among them, M1<M2.

4. The control method according to claim 1, characterized in that: When the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If △T≤(-T2), the second solenoid valve is controlled to power on Y3 at a third preset time interval M3; T2 is a preset temperature difference.

5. The control method according to claim 4, characterized in that: When the unit is in a refrigeration condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If (-T2)<△T≤(-T2) / 2, control the second solenoid valve to power on Y4 at a fourth preset time interval M4; Among them, M3<M4.

6. The control method according to claim 1, characterized in that: When the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If ΔT≥T2, the second solenoid valve is controlled to power on Y5 at every fifth preset time interval M5, and T2 is the preset temperature difference.

7. The control method according to claim 6, characterized in that: When the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If (T2) / 2≤△T<T2, control the second solenoid valve to power on Y6 every sixth preset time interval M6; Among them, M5<M6.

8. The control method according to claim 1, characterized in that: When the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If △T≤(-T2), the first solenoid valve is controlled to power on Y7 at every seventh preset time interval M7, and T2 is the preset temperature difference.

9. The control method according to claim 8, characterized in that: When the unit is in a heating condition, the step of "controlling the compressor to load, unload, or alternately load and unload according to the range of the difference ΔT, so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If (-T2)<△T≤(-T2) / 2, control the first solenoid valve M8 to power on Y8 every eighth preset time interval; Among them, M7<M8.

10. The control method according to claim 1, characterized in that: The step of "controlling the compressor to load, unload or alternately load and unload according to the range of the difference ΔT so that the outlet water temperature of the heat pump unit is within a preset stable range" also includes: If |△T|<(T2) / 2, then obtain the load value change of the heat pump unit, wherein T2 is the preset temperature difference; If the load value of the heat pump unit increases, the second solenoid valve is controlled to be powered on at Y9 every ninth preset time interval M9; and / or, If the load value of the heat pump unit decreases, the first solenoid valve is controlled to be powered on Y9 at intervals of a ninth preset time M9.

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