Heat pump unit and control method thereof

Abstract

The present application relates to the technical field of heat pump unit, and particularly provides a heat pump unit and a control method thereof, aiming to solve the problem that the existing heat pump unit is unstable in operation, resulting in a large fluctuation range of outlet water temperature and affecting the user experience. To this end, the heat pump unit comprises a compressor, a first electromagnetic valve for controlling the loading of the compressor, and a second electromagnetic valve for controlling the unloading of the compressor; the first electromagnetic valve is powered on to load the compressor, and the second electromagnetic valve is powered on to unload the compressor; the control method comprises: obtaining the inlet water temperature T0 of the heat pump unit; calculating the difference AT 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 AT, 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 the preset stable range. The present application can stabilize the outlet water temperature within a reasonable range, avoid large fluctuation of the outlet water temperature, and improve the user experience.

Description

Technical Field

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

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

[0003] Variable-rate screw air source heat pump units offer advantages over stepped-rate units due to their wider energy regulation range, resulting in smoother capacity changes, greater system stability, and a better user experience. However, during energy regulation, the variable-rate compressor experiences slight fluctuations due to the non-fixed adjustment of the slide valve, and the degree of regulation is difficult to control. Repeatedly adding or removing loads from the compressor can lead to significant water temperature fluctuations, negatively impacting the customer experience.

[0004] In summary, the unstable operation of existing heat pump units results in large fluctuations in the outlet water temperature, which affects the user experience.

[0005] Accordingly, there is a need in the field for a new heat pump unit and its control method to solve the above problems. Summary of the Invention

[0006] The present invention aims to solve the above-mentioned technical problems, namely, to solve the problem that the unstable operation of existing heat pump units leads to large fluctuations in the outlet water temperature, which in turn affects the user experience.

[0007] In a first aspect, the present invention provides a control method for a heat pump unit, the heat pump unit including a compressor and a first solenoid valve for loading the compressor and a second solenoid valve for unloading the compressor; the first solenoid valve is energized to load the compressor, and the second solenoid valve is energized to unload the compressor;

[0008] The control method includes:

[0009] Obtain the inlet water 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] Based on the range of the difference △T, 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 embodiment of the above control method, when the unit is in cooling mode, 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 be energized Y1 at a first preset time interval M1;

[0014] T2 is the preset temperature difference.

[0015] In the preferred embodiment of the above control method, when the unit is in cooling mode, 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:

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

[0017] Where M1 < M2.

[0018] In the preferred embodiment of the above control method, when the unit is in cooling mode, 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:

[0019] If △T≤(-T2), control the second solenoid valve to be energized Y3 every third preset time interval M3; T2 is the preset temperature difference.

[0020] In the preferred embodiment of the above control method, when the unit is in cooling mode, 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:

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

[0022] Where M3 < M4;

[0023] In the preferred embodiment of the above control method, when the unit is in heating mode, 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:

[0024] If △T≥T2, control the second solenoid valve to be energized Y5 every fifth preset time interval M5, where T2 is the preset temperature difference.

[0025] In the preferred embodiment of the above control method, when the unit is in heating mode, 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:

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

[0027] Where M5 < M6.

[0028] In the preferred embodiment of the above control method, when the unit is in heating mode, 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:

[0029] If △T≤(-T2), the first solenoid valve is energized Y7 every seventh preset time interval M7, where T2 is the preset temperature difference.

[0030] In the preferred embodiment of the above control method, when the unit is in heating mode, 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:

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

[0032] Where M7 < M8.

[0033] In the preferred embodiment 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" further includes:

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

[0035] If the load value of the heat pump unit increases, the second solenoid valve is energized 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 energized Y9 at nine preset time intervals M9.

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

[0039] Obtain the compressor's discharge pressure and suction pressure;

[0040] If the discharge 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 the inlet water temperature T0 of the heat pump unit is obtained.

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

[0042] In a preferred embodiment of the above control method, the control method further includes:

[0043] When the heat pump unit is performing high-temperature cooling, if the discharge pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so that the compressor can be unloaded.

[0044] In the preferred embodiment of the above control method, the step of "if the discharge pressure of the compressor is greater than the first preset pressure, then controlling the second solenoid valve to operate so that the compressor can unload" specifically includes:

[0045] Every ten preset time intervals M10, the second solenoid valve is energized Y10.

[0046] In the preferred embodiment of the above control method, the step of "controlling the second solenoid valve to operate if the discharge pressure of the compressor is greater than the first preset pressure" further includes:

[0047] After the second solenoid valve is energized a first preset number of times, the second solenoid valve is controlled to stop being energized.

[0048] In a preferred embodiment of the above control method, the control method further includes:

[0049] When the heat pump unit is operating in low-temperature heating mode...

[0050] If the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so that the compressor is loaded.

[0051] In the preferred embodiment of the above control method, the step of "controlling the first solenoid valve to operate so that the compressor is loaded if the suction pressure of the compressor is less than the second preset pressure" specifically includes:

[0052] At every eleventh preset time interval M11, the first solenoid valve is energized Y11.

[0053] In the preferred embodiment of the above control method, the step of "controlling the first solenoid valve to operate if the suction pressure of the compressor is less than the second preset pressure" further includes:

[0054] After the first solenoid valve is energized a second preset number of times, the first solenoid valve is controlled to stop being energized.

[0055] In the preferred embodiment of the above control method, the compressor discharge pressure and suction pressure are obtained;

[0056] The pressure ratio of the compressor is calculated as the ratio of the discharge pressure to the intake pressure;

[0057] The energizing time Y of the first or second solenoid valve is determined by the following formula;

[0058] Where Y is the power-on time, in seconds;

[0059] When the first solenoid valve is energized, X is the pressure ratio of the compressor before the first solenoid valve is energized;

[0060] When the second solenoid valve is energized, X is the pressure ratio of the compressor before the second solenoid valve is energized;

[0061] t represents the unit of time, 1 second;

[0062] a, b, c, j, and k are constants.

[0063] In a second aspect, the present invention also provides a heat pump unit, the heat pump unit including a controller configured to perform the control method of the heat pump unit described in any of the preferred technical solutions above.

[0064] When adopting the above technical solution, the heat pump unit of the present invention includes a compressor and a first solenoid valve for loading and a second solenoid valve for unloading the compressor; energizing the first solenoid valve loads the compressor, and energizing the second solenoid valve unloads the compressor; the control method of the present invention includes: obtaining the inlet water temperature T0 of the heat pump unit; calculating the difference ΔT between the inlet water temperature T0 and the preset inlet water temperature T1; and 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. The present invention controls the compressor to load, unload, or alternately load and unload according to the comparison result between the difference between the inlet water temperature and the preset inlet water temperature and the preset temperature difference, so that the outlet water temperature is stabilized within a reasonable range, avoiding large fluctuations in the outlet water temperature and improving the user experience.

[0065] Furthermore, the present invention also controls the second solenoid valve to operate when the compressor's discharge pressure is greater than the first preset pressure during high-temperature cooling of the heat pump unit, so as to reduce the load on the compressor, thereby enabling the heat pump unit to always operate in a stable state and improving the stability of the unit.

[0066] Furthermore, the present invention also controls the first solenoid valve to operate when the compressor suction pressure is less than the second preset pressure during low-temperature heating of the heat pump unit, so as to load the compressor, thereby enabling the heat pump unit to always operate in a stable state and improving the stability of the unit.

[0067] Solution 1. A control method for a heat pump unit, characterized in that the heat pump unit includes a compressor and a first solenoid valve for loading and a second solenoid valve for unloading the compressor; the first solenoid valve is energized to load the compressor, and the second solenoid valve is energized to unload the compressor;

[0068] The control method includes:

[0069] Obtain the inlet water temperature T0 of the heat pump unit;

[0070] Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0071] Based on the range of the difference △T, 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.

[0072] Scheme 2. The control method according to Scheme 1, characterized in that, when the unit is in cooling mode, 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:

[0073] If △T≥T2, control the first solenoid valve to be energized Y1 at a first preset time interval M1;

[0074] T2 is the preset temperature difference.

[0075] Scheme 3. The control method according to Scheme 2, characterized in that, when the unit is in cooling mode, 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:

[0076] If (T2) / 2≤△T<T2, control the first solenoid valve to be energized Y2 every second preset time interval M2;

[0077] Where M1 < M2.

[0078] Scheme 4. The control method according to Scheme 1, characterized in that, when the unit is in cooling mode, 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:

[0079] If △T≤(-T2), control the second solenoid valve to be energized Y3 every third preset time interval M3; T2 is the preset temperature difference.

[0080] Scheme 5. The control method according to Scheme 4, characterized in that, when the unit is in cooling mode, 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:

[0081] If (-T2) < △T ≤ (-T2) / 2, control the second solenoid valve to be energized Y4 every fourth preset time interval M4;

[0082] Where M3 < M4;

[0083] Solution 6. The control method according to Solution 1, characterized in that, when the unit is in heating mode, 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:

[0084] If △T≥T2, control the second solenoid valve to be energized Y5 every fifth preset time interval M5, where T2 is the preset temperature difference.

[0085] Scheme 7. The control method according to Scheme 6, characterized in that, when the unit is in heating mode, 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:

[0086] If (T2) / 2≤△T<T2, control the second solenoid valve to be energized Y6 every sixth preset time interval M6;

[0087] Where M5 < M6.

[0088] Scheme 8. The control method according to Scheme 1, characterized in that, when the unit is in heating mode, 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:

[0089] If △T≤(-T2), the first solenoid valve is energized Y7 every seventh preset time interval M7, where T2 is the preset temperature difference.

[0090] Scheme 9. The control method according to Scheme 8, characterized in that, when the unit is in heating mode, 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:

[0091] If (-T2) < △T ≤ (-T2) / 2, control the first solenoid valve to be energized Y8 every eighth preset time interval M8;

[0092] Where M7 < M8.

[0093] Scheme 10. The control method according to Scheme 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" further includes:

[0094] If |△T|<(T2) / 2, then obtain the load value change of the heat pump unit, where T2 is the preset temperature difference;

[0095] If the load value of the heat pump unit increases, the second solenoid valve is energized Y9 every ninth preset time interval M9;

[0096] And / or,

[0097] If the load value of the heat pump unit decreases, the first solenoid valve is energized Y9 at nine preset time intervals M9.

[0098] Scheme 11. The control method according to claim 1, characterized in that the step of "obtaining the inlet water temperature T0 of the heat pump unit" further includes:

[0099] Obtain the compressor's discharge pressure and suction pressure;

[0100] If the discharge 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 the inlet water temperature T0 of the heat pump unit is obtained.

[0101] The first preset pressure is greater than the second preset pressure.

[0102] Solution 12. The control method according to Solution 11, characterized in that the control method further includes:

[0103] When the heat pump unit is performing high-temperature cooling, if the discharge pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so that the compressor can be unloaded.

[0104] Solution 13. The control method according to Solution 12, characterized in that the step of "if the discharge pressure of the compressor is greater than the first preset pressure, then controlling the second solenoid valve to operate so as to unload the compressor" specifically includes:

[0105] Every ten preset time intervals M10, the second solenoid valve is energized Y10.

[0106] Solution 14. The control method according to Solution 13, characterized in that the step of "controlling the second solenoid valve to operate if the discharge pressure of the compressor is greater than the first preset pressure" further includes:

[0107] After the second solenoid valve is energized a first preset number of times, the second solenoid valve is controlled to stop being energized.

[0108] Solution 15. The control method according to Solution 11, characterized in that the control method further includes:

[0109] When the heat pump unit is operating in low-temperature heating mode...

[0110] If the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so that the compressor is loaded.

[0111] Solution 16. The control method according to Solution 15, characterized in that the step of "if the suction pressure of the compressor is less than the second preset pressure, then controlling the first solenoid valve to operate so that the compressor is loaded" specifically includes:

[0112] At every eleventh preset time interval M11, the first solenoid valve is energized Y11.

[0113] Solution 17. The control method according to Solution 16, characterized in that the step of "controlling the first solenoid valve to operate if the suction pressure of the compressor is less than the second preset pressure" further includes:

[0114] After the first solenoid valve is energized a second preset number of times, the first solenoid valve is controlled to stop being energized.

[0115] Scheme 18. The control method according to any one of Schemes 1 to 17, characterized in that,

[0116] Obtain the compressor's discharge pressure and suction pressure;

[0117] The pressure ratio of the compressor is calculated as the ratio of the discharge pressure to the intake pressure;

[0118] The energizing time Y of the first or second solenoid valve is determined by the following formula;

[0119] Where Y is the power-on time, in seconds;

[0120] When the first solenoid valve is energized, X is the pressure ratio of the compressor before the first solenoid valve is energized;

[0121] When the second solenoid valve is energized, X is the pressure ratio of the compressor before the second solenoid valve is energized;

[0122] t represents the unit of time, 1 second;

[0123] a, b, c, j, and k are constants.

[0124] Scheme 19. A heat pump unit, characterized in that the heat pump unit includes a controller, the controller being configured to execute the control method of the heat pump unit described in any one of Schemes 1 to 18 above. Attached Figure Description

[0125] The preferred embodiments of the present invention are described below with reference to the accompanying drawings, in which:

[0126] Figure 1 This is a flowchart of the main steps of the control method for the heat pump unit of the present invention;

[0127] Figure 2 This is a flowchart of the steps of the heat pump unit of the present invention under cooling conditions;

[0128] Figure 3 This is a flowchart of the steps of the heat pump unit of the present invention under heating conditions;

[0129] Figure 4 This is a comparison diagram of the heat pump unit of the present invention under heating and cooling conditions;

[0130] Figure 5 This is a schematic diagram of the compressor loading vibration damping pipeline of the heat pump unit according to the first preferred embodiment of the present invention;

[0131] Figure 6 This is a schematic diagram of the compressor loading vibration damping pipeline of the heat pump unit according to the second preferred embodiment of the present invention;

[0132] Figure label:

[0133] 1. First solenoid valve; 2. Second solenoid valve; 3. First oil line; 4. Second oil line; 5. Piston; 6. Slide valve; 7. Screw; 8. Main line. Detailed Implementation

[0134] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the invention and are not intended to limit the scope of protection of the invention. Those skilled in the art can make adjustments as needed to adapt to specific applications.

[0135] It should be noted that in the description of this invention, terms such as "front" and "rear" indicating directional or positional relationships are based on the directional or positional relationships shown in the accompanying drawings. This is merely for ease of description and does not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, it should not be construed as a limitation of this invention. Furthermore, it should be noted that in the description of this invention, terms such as "first," "second," "third," "fourth," "fifth," "sixth," "seventh," "eighth," "ninth," "tenth," and "eleventh" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0136] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "connected" and "connected" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0137] Referring first to 5, the heat pump unit of the present invention includes a compressor and a first solenoid valve 1 for loading the compressor and a second solenoid valve 2 for unloading the compressor. When the first solenoid valve 1 is energized, the compressor is loaded; when the second solenoid valve 2 is energized, the compressor is unloaded. Specifically, a slide valve 6 is connected to a piston 5. The chamber where the piston 5 is located is connected to a first oil line 3 and a second oil line 4. The first solenoid valve 1 is located on the first oil line 3, and the second solenoid valve 2 is located on the second oil line 4. When the first solenoid valve 1 is energized, the first oil line 3 supplies oil, causing the piston 5 to move forward, thereby pushing the slide valve 6 of the compressor forward. The amount of sealing in the compression chamber where the screw 7 is located increases, making the closed chamber formed by the compressor larger, and thus increasing the operating capacity of the compressor. When the second solenoid valve 2 is energized, the second oil line 4 drains oil, causing the piston 5 to move backward, thereby moving the slide valve 6 of the compressor backward, making the closed chamber formed by the compressor smaller, and thus decreasing the operating capacity of the compressor.

[0138] Those skilled in the art will understand that the first oil line 3 and the second oil line 4 can be connected to the chamber where the piston 5 is located via the main pipeline 8, or they can be connected as follows: Figure 6 As shown, the first oil line 3 and the second oil line 4 are each individually connected to the chamber where the piston 5 is located. Those skilled in the art can set them up according to the actual situation.

[0139] by Figure 5 The directions shown are the reference directions. The first oil line 3 can be the return oil in the heat pump unit system, and the second oil line 4 is connected to the compressor's suction port. Therefore, when the first solenoid valve 1 is energized, the first oil line 3 is connected to the chamber where the piston 5 is located. The first oil line 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 forward, and the compressor is loaded. When the second solenoid valve 2 is energized, the second oil line 4 is connected to the chamber where the piston 5 is located. Since the second oil line 4 is connected to the compressor's suction port, the pressure on the front side of the piston 5 is greater than the pressure on the rear side, which causes the second oil line 4 to drain oil. The piston 5 and the slide valve 6 move backward, and the compressor is unloaded.

[0140] In another preferred embodiment, the first oil line 3 is connected to an oil supply device to provide high-pressure oil, thereby pushing the piston 5 and the slide valve 6 forward. The second oil line 4 is connected to an oil drain end (oil drain tank or oil drain container) so that the pressure in the second oil line 4 is low when the second solenoid valve 2 is energized, thereby draining oil to make the piston 5 and the slide valve 6 move backward.

[0141] The heat pump unit of the present invention also includes a controller, which is configured to control all operations of the heat pump unit.

[0142] Those skilled in the art will understand that the present invention does not impose any restrictions on the specific structure and model of the controller, and the controller can be either the original controller of the heat pump unit or a controller specially set up to execute the control method of the present invention. Technicians can set the structure and model of the controller according to actual usage requirements.

[0143] See Figure 1 The control method of the heat pump unit of the present invention mainly includes the following steps:

[0144] Step S1: Obtain the inlet water temperature T0 of the heat pump unit;

[0145] Step S2: Calculate the difference ΔT between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0146] Step S3: Based on the range of the difference △T, control the compressor to load, unload, or alternately load and unload to keep the outlet water temperature of the heat pump unit within the preset stable range.

[0147] Further, in step S1, the inlet water temperature T0 at the shell-and-tube evaporator of the heat pump unit is obtained through a temperature sensor; that is, the temperature of the water before heat exchange treatment. After obtaining the inlet water temperature T0, the information of the inlet water temperature T0 is transmitted to the controller of the heat pump unit. In step S2, the preset inlet water temperature T1 is the value set by the user. The calculation module in the controller calculates the difference ΔT between T0 and T1, and then proceeds to step S3. In step S3, if the difference |ΔT| is within a preset range under cooling conditions, the first solenoid valve 1 and the second solenoid valve 2 are controlled to work alternately to keep the compressor in its current working state. If ΔT is... If the difference in ΔT is positive and outside the preset range, the first solenoid valve 1 is controlled to operate, thereby loading the compressor. If ΔT is negative and outside the preset range, the second solenoid valve 2 is controlled to operate, thereby unloading the compressor. If, under heating conditions, the difference in ΔT is within the preset range, the first solenoid valve 1 and the second solenoid valve 2 are controlled to operate alternately, thereby maintaining the compressor's current operating state. If ΔT is positive and outside the preset range, the second solenoid valve 2 is controlled to operate, thereby unloading the compressor. If ΔT is negative and outside the preset range, the first solenoid valve 1 is controlled to operate, thereby loading the compressor.

[0148] 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.

[0149] In step S2, the user can also preset the outlet water temperature through the controller or software, and obtain the required inlet water temperature by subtracting the temperature change difference from the preset outlet water temperature. Those skilled in the art can set it according to the actual situation.

[0150] See next. Figure 2 and Figure 4 ,like Figure 2 As shown, the control method of the heat pump unit of the present invention includes the following steps under cooling conditions:

[0151] Step S101: Obtain the inlet water temperature T0 of the heat pump unit;

[0152] Step S102: Calculate the difference △T between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0153] Step S103: If △T≥T2, control the first solenoid valve to be energized Y1 at first preset time intervals M1;

[0154] Step S104: If (T2) / 2≤△T<T2, control the first solenoid valve to be energized Y2 every second preset time interval M2;

[0155] Step S105: If △T≤(-T2), control the second solenoid valve to be energized Y3 every third preset time interval M3;

[0156] Step S106: If (-T2) < △T ≤ (-T2) / 2, control the second solenoid valve to be energized Y4 every fourth preset time interval M4.

[0157] For example, such as Figure 4 As shown in the diagram, T2 is the preset temperature difference, which is 4℃, and the preset inlet water temperature T1 is 10℃. Under cooling conditions, if the inlet water temperature T0 is greater than or equal to 14℃, then △T=T0-T1≥T2. At this time, step S103 is entered, and the first solenoid valve 1 is energized Y1 at a first preset time interval M1, so that the compressor enters the rapid loading stage, where Y1 is the energizing time of the first solenoid valve 1. Because under cooling conditions, 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, the cooling capacity of the heat pump unit needs to be increased to meet the user's desired outlet water temperature after water heat exchange. In step S103, the compressor rapidly loads to increase the cooling capacity of the heat pump unit to ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0158] In cooling mode, if 12℃≤inlet water temperature T0<14℃, then (T2) / 2≤△T<T2. At this time, step S104 is entered, and the first solenoid valve 1 is energized at intervals of the second preset time M2 by Y2, so that the compressor enters the slow loading stage. Y2 is the energizing time of the first solenoid valve 1. At this time, in cooling mode, the inlet water temperature is higher than the preset inlet water temperature, and it is still necessary to increase the cooling capacity of the heat pump unit. However, since the difference between the inlet water temperature and the preset inlet water temperature is small, in step S104, controlling the compressor to slowly load and increase the cooling capacity of the heat pump unit can ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0159] Where M1 < M2, so that step S103 is the compressor rapid loading stage and step S104 is the compressor slow loading stage.

[0160] Continue reading Figure 2 and Figure 4In cooling mode, if the inlet water temperature T0 ≤ 6℃, then △T ≤ (-T2). At this time, step S105 is entered, and the second solenoid valve 2 is energized at a third preset time interval M3, where Y3 is the energization time of the second solenoid valve 2. This causes the compressor to enter the rapid unloading stage. In cooling mode, if the inlet water temperature is lower than the preset inlet water temperature, the heat pump unit can reduce its cooling capacity to meet the user's required outlet water temperature after 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 unloading stage to reduce the cooling 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.

[0161] In cooling mode, if 6℃ < inlet water temperature T0 ≤ 8℃, then (-T2) < △T ≤ (-T2) / 2. At this time, proceed to step S106, control the second solenoid valve 2 to be energized Y4 every four preset time intervals M4, where Y4 is the energization time of the second solenoid valve 2, so that the compressor enters the slow unloading stage. In cooling mode, the inlet water temperature is lower than the preset inlet water temperature, and it is still necessary to reduce the cooling capacity of the heat pump unit. However, the difference between the two is small. Therefore, in step S106, controlling the compressor to slowly unload and reduce the cooling capacity of the heat pump unit can ensure that the outlet water temperature of the heat pump unit is within the preset range.

[0162] Where M3 < M4, so that step S105 is the compressor rapidly unloading and step S106 is the compressor slowly unloading.

[0163] It should be noted that the present invention does not impose any restrictions 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 and M3 < M4, it is acceptable. Those skilled in the art can set these values ​​according to the actual situation.

[0164] See next. Figure 3 and Figure 4 The control method for the heat pump unit of the present invention includes the following steps under heating conditions:

[0165] Step S101: Obtain the inlet water temperature T0 of the heat pump unit;

[0166] Step S102: Calculate the difference △T between the inlet water temperature T0 of the heat pump unit and the preset inlet water temperature T1;

[0167] Step S107: If △T≥T2, control the second solenoid valve to be energized Y5 every fifth preset time interval M5;

[0168] Step S108: If (T2) / 2≤△T<T2, control the second solenoid valve to be energized Y6 every sixth preset time interval M6;

[0169] Step S109: If △T≤(-T2), control the first solenoid valve to be energized Y7 every seventh preset time interval M7;

[0170] Step S110: If (-T2) < △T ≤ (-T2) / 2, control the first solenoid valve to be energized Y8 every eighth preset time interval M8.

[0171] For example, such as Figure 4 As shown in the diagram, T2 is the preset temperature difference, which is 4℃, and the preset inlet water temperature T1 is 10℃. Under heating conditions, if the inlet water temperature T0 > 14℃, then △T ≥ T2, and the process proceeds to step S107. In this step, the second solenoid valve 2 is energized every five preset time intervals M5 and Y5 is the energization 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 higher than the preset inlet water temperature and the difference is large, the heat pump unit can more easily obtain the desired or set outlet water temperature by exchanging the inlet water temperature. Therefore, the second solenoid valve 2 is energized, causing the compressor to enter a rapid unloading phase, 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 remains stable within a reasonable range to meet the user's water demand.

[0172] If 12℃≤inlet water temperature T0<14℃, then (T2) / 2≤△T<T2. At this time, proceed to step S108, control the second solenoid valve 2 to be energized Y6 every six preset time intervals M6, where Y6 is the energization time of the second solenoid valve 2. In heating mode, if the inlet water temperature is greater than the preset inlet water temperature and the difference between the two is small, control the compressor to enter the slow unloading 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.

[0173] Where M5 < M6, so that step S107 is the compressor rapid unloading stage and step S108 is the compressor slow unloading stage.

[0174] In heating mode, if the inlet water temperature T0 ≤ 6℃, then △T ≤ (-T2), proceed to step S109, control the first solenoid valve 1 to be energized at seven preset time intervals M7 Y7, where Y7 is the energization time of the first solenoid valve 1. In heating mode, 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, proceed to step S109, the compressor rapid loading stage, to 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.

[0175] Under heating conditions, if 6℃ < inlet water temperature T0 ≤ 8℃, then (-T2) < △T ≤ (-T2) / 2, proceed to step S110, control the first solenoid valve 1 to be energized Y8 every eight preset time intervals M8, where Y8 is the energization time of the first solenoid valve 1. If the inlet water temperature is lower than the preset inlet water temperature, the heat pump unit needs to increase the heating capacity of the compressor 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 small, proceed to step S110, the compressor slow loading stage, to 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] Where M7 < M8, so that step S109 is the compressor rapid loading stage and step S110 is the compressor slow loading stage.

[0177] It should be noted that the present invention does not impose any restrictions 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 and M7 < M8, it is acceptable. Those skilled in the art can set these values ​​according to the actual situation.

[0178] Furthermore, the control method of the present invention also includes:

[0179] Step S111: If |△T|<(T2) / 2, then obtain the load change of the heat pump unit;

[0180] Step S112: If the load value of the heat pump unit increases, control the second solenoid valve to be energized Y9 every ninth preset time interval M9;

[0181] Step S113: If the load value of the heat pump unit decreases, control the first solenoid valve to be energized Y9 every ninth preset time interval M9.

[0182] See Figure 4 For example, the preset temperature difference T2 is 4℃ and the preset inlet water temperature T1 is 10℃. Regardless of whether it is in heating or cooling mode, if 8℃ < inlet water temperature T0 < 12℃, 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, it is sufficient to maintain the current working state of the compressor. When maintaining the current working state of the compressor, both the first solenoid valve 1 and the second solenoid valve 2 are in the closed state.

[0183] The computer board of the heat pump unit detects changes in load value. If the load value increases, the process proceeds to step S111, where the second solenoid valve 2 is energized at a preset time interval M9 (Y9 is the energization time of the second solenoid valve 2). The second solenoid valve 2 controls the compressor to unload, thereby maintaining the compressor's current operating state. If the load value decreases, the process proceeds to step S113, where the first solenoid valve 1 is energized at a preset time interval M9 (Y9 is the energization time of the first solenoid valve 1). The first solenoid valve 1 controls the compressor to load, thereby maintaining the compressor's current operating state.

[0184] It should be noted that the present invention does not impose any restrictions on the specific values ​​of the preset inlet water temperature T1 and the preset temperature difference T2. The preset inlet water temperature T1 can be set according to the actual situation, and the preset temperature difference can also be 2℃ or 3℃. Of course, it can also be other values. Those skilled in the art can set it according to the actual situation.

[0185] In addition, it should be noted that the present invention does not impose any restrictions on the specific value of M9. The specific value range of M9 is 1.5s-2.5s, and of course, it can be other values. Those skilled in the art can set it according to the actual situation.

[0186] Furthermore, the control method of the present invention also includes:

[0187] Step S201: Obtain the compressor discharge pressure and suction pressure.

[0188] Step S202: If the compressor's discharge pressure is less than or equal to the first preset pressure, and the compressor's suction pressure is greater than or equal to the second preset pressure, then proceed to step S101: Obtain the inlet water temperature T0 of the heat pump unit; the first preset pressure is greater than the second preset pressure.

[0189] Step S203: When the heat pump unit is performing high-temperature cooling, if the compressor's discharge pressure is greater than the first preset pressure, the second solenoid valve is controlled to operate so that the compressor can reduce its load.

[0190] Step S2031: Every tenth preset time interval M10, control the second solenoid valve 2 to be energized Y10;

[0191] Step S2032: After the second solenoid valve is energized for the first preset number of times, control the second solenoid valve to stop being energized;

[0192] Step S204: When the heat pump unit is operating in low-temperature heating mode, if the compressor suction pressure is less than the second preset pressure, the first solenoid valve is controlled to operate so that the compressor is loaded.

[0193] Step S2041: Every eleventh preset time interval M11, control the first solenoid valve to be energized Y11;

[0194] Step S2042: After the first solenoid valve 1 has been energized a second preset number of times, control the first solenoid valve to stop being energized.

[0195] Specifically, the first preset pressure is the maximum limit of the discharge pressure. If the discharge pressure is greater than the first preset pressure, the second solenoid valve 2 is controlled to work, so that the compressor is unloaded and the discharge pressure of the compressor is reduced, so that the unit can operate more stably. The second preset pressure is the minimum limit of the suction pressure. If the discharge pressure is less than the second preset pressure, the first solenoid valve 1 is controlled to work, so that the suction pressure of the compressor is increased, so that the unit can operate more stably.

[0196] Preferably, the range of the tenth preset time M10 and the eleventh preset time M11 is 1-2 seconds, and the first preset number and the second preset number are both 5 times. Of course, the values ​​of M10 and M11, as well as the first preset number and the second preset number of 5 times, can be other values, and those skilled in the art can set them according to the actual situation.

[0197] Furthermore, the control method of the present invention further includes the following steps:

[0198] Step S301: Obtain the compressor discharge pressure and suction pressure;

[0199] Step S302: Calculate the compressor's pressure ratio as the ratio of discharge pressure to suction pressure;

[0200] Step S303: Determine the energizing time Y of the first or second solenoid valve using the following formula;

[0201] Y=(aX j +bX k +c)t (1)

[0202] Where Y is the power-on time, in seconds;

[0203] When the first solenoid valve is energized, X is the pressure ratio of the compressor before the first solenoid valve is energized;

[0204] When the second solenoid valve is energized, X is the pressure ratio of the compressor before the second solenoid valve is energized;

[0205] t represents the unit of time, 1 second;

[0206] a, b, c, j, and k are constants.

[0207] 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) based on the energizing time of the first solenoid valve 1 when the load value of the unit computer board is increased by 1% under different pressure ratios (the ratio of the compressor's exhaust pressure to its suction pressure) of the heat pump unit. The calculation of Y1, Y2, Y7, Y8, Y11 and the energizing time Y9 of the first solenoid valve 1 are all calculated using the above formula (1), and the energizing time Y of the first solenoid valve 1 at each preset interval corresponds to the pressure ratio of the compressor before the first solenoid valve 1 is energized.

[0208] Based on the heat pump unit under different pressure ratios (the ratio of the compressor's exhaust pressure to its intake pressure), the power-on time of the second solenoid valve 2 when the load value of the unit's computer board is reduced by 1% is obtained by taking multiple sets of data and substituting them into formula (1). The power-on time Y9 of the second solenoid valve 2 is calculated using the above formula (1), and the power-on time Y of the second solenoid valve 2 at each preset interval corresponds to the compressor's pressure ratio before the second solenoid valve 2 is powered on.

[0209] By using the above formula to control the energizing time of the first solenoid valve 1 or the second solenoid valve 2, the stability of the heat pump unit's operation can be guaranteed.

[0210] In the control method described above, unless otherwise specified, when the first solenoid valve 1 is in the energized and activated state, the second solenoid valve 2 is in the closed state; when the second solenoid valve 2 is in the energized and activated state, the first solenoid valve 1 is in the closed state.

[0211] In a second aspect, the present invention also claims a heat pump unit including a controller configured to perform the control method of the heat pump unit described in any of the preferred embodiments above.

[0212] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles 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 such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A control method for a heat pump unit, characterized in that, The heat pump unit includes a compressor, a first solenoid valve for controlling the loading of the compressor, and a second solenoid valve for controlling the unloading of the compressor. The first solenoid valve is energized to load the compressor, and the second solenoid valve is energized to unload the compressor; The control method includes: Obtain the inlet water 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; Based on the range of the difference ΔT, the compressor is controlled to load, unload, or alternately load and unload to keep the outlet water temperature of the heat pump unit within a preset stable range. The steps include: When the unit is in cooling mode, if ΔT≥T2, the first solenoid valve is energized by Y1 at a first preset time interval M1; if (T2) / 2≤ΔT<T2, the first solenoid valve is energized by Y2 at a second preset time interval M2; where M1<M2, and T2 is the preset temperature difference. Obtain the compressor's discharge pressure and suction pressure; calculate the compressor's pressure ratio as the ratio of discharge pressure to suction pressure; determine the energizing time Y of the first or second solenoid valve using the following formula; Where Y is the power-on time in seconds; when the first solenoid valve is powered on, X is the pressure ratio of the compressor before the first solenoid valve is powered on; when the second solenoid valve is powered on, X is the pressure ratio of the compressor before the second solenoid valve is powered on; t is the unit time 1 second; a, b, c, j, and k are constants.

2. The control method according to claim 1, characterized in that, When the unit is in cooling mode, 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: If △T≤(-T2), control the second solenoid valve to be energized Y3 every third preset time interval M3; T2 is the preset temperature difference.

3. The control method according to claim 2, characterized in that, When the unit is in cooling mode, 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: If (-T2) < △T ≤ (-T2) / 2, control the second solenoid valve to be energized Y4 every fourth preset time interval M4; Where M3 < M4.

4. The control method according to claim 1, characterized in that, When the unit is in heating mode, 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: If △T≥T2, control the second solenoid valve to be energized Y5 every fifth preset time interval M5, where T2 is the preset temperature difference.

5. The control method according to claim 4, characterized in that, When the unit is in heating mode, 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: If (T2) / 2≤△T<T2, control the second solenoid valve to be energized Y6 every sixth preset time interval M6; Where M5 < M6.

6. The control method according to claim 1, characterized in that, When the unit is in heating mode, 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: If △T≤(-T2), control the first solenoid valve to be energized Y7 every seventh preset time interval M7, where T2 is the preset temperature difference.

7. The control method according to claim 6, characterized in that, When the unit is in heating mode, 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: If (-T2) < △T ≤ (-T2) / 2, control the first solenoid valve to be energized Y8 every eighth preset time interval M8; Where M7 < M8.

8. 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 △T, so that the outlet water temperature of the heat pump unit is within a preset stable range" further includes: If |△T| < (T2) / 2, then obtain the load value change of the heat pump unit, where T2 is the preset temperature difference; If the load value of the heat pump unit increases, the second solenoid valve is energized Y9 every ninth preset time interval M9; And / or, If the load value of the heat pump unit decreases, the first solenoid valve is energized Y9 at nine preset time intervals M9.

9. The control method according to claim 1, characterized in that, The step of "obtaining the inlet water temperature T0 of the heat pump unit" further includes: Obtain the compressor's discharge pressure and suction pressure; If the discharge 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 the inlet water temperature T0 of the heat pump unit is obtained. The first preset pressure is greater than the second preset pressure.

10. The control method according to claim 9, characterized in that, The control method further includes: When the heat pump unit is performing high-temperature cooling, if the discharge pressure of the compressor is greater than the first preset pressure, the second solenoid valve is controlled to operate so that the compressor can be unloaded.

11. The control method according to claim 10, characterized in that, The step of "if the discharge pressure of the compressor is greater than the first preset pressure, then controlling the second solenoid valve to operate, so as to unload the compressor" specifically includes: Every ten preset time intervals M10, the second solenoid valve is energized Y10.

12. The control method according to claim 11, characterized in that, The step of "controlling the second solenoid valve to operate if the discharge pressure of the compressor is greater than the first preset pressure" further includes: After the second solenoid valve is energized a first preset number of times, the second solenoid valve is controlled to stop being energized.

13. The control method according to claim 9, characterized in that, The control method further includes: When the heat pump unit is operating in low-temperature heating mode... If the suction pressure of the compressor is less than the second preset pressure, the first solenoid valve is controlled to operate so that the compressor is loaded.

14. The control method according to claim 13, characterized in that, The step of "if the suction pressure of the compressor is less than the second preset pressure, then controlling the first solenoid valve to operate so that the compressor is loaded" specifically includes: At every eleventh preset time interval M11, the first solenoid valve is energized Y11.

15. The control method according to claim 14, characterized in that, The step of "controlling the first solenoid valve to operate if the compressor's suction pressure is less than the second preset pressure" further includes: After the first solenoid valve is energized a second preset number of times, the first solenoid valve is controlled to stop being energized.

16. A heat pump unit, characterized in that, The heat pump unit includes a controller configured to perform the control method of the heat pump unit according to any one of claims 1 to 15.

Images