Variable frequency heat pump system and control method thereof

Abstract

The application discloses a variable frequency heat pump system and a control method thereof. The control method comprises the following steps: S101, when the variable frequency heat pump system is in a cooling mode and a control instruction of executing a heating mode is received, a four-way component is powered on, and then a compressor is controlled to start working; S102, a real-time running frequency of the compressor is acquired, and when the real-time running frequency of the compressor is greater than or equal to a preset operation frequency, a control device controls the four-way component to be powered off; S201, when the variable frequency heat pump system is in the heating mode and the control instruction of executing the cooling mode is received, the control device controls the four-way component to keep the working state unchanged, and controls the compressor to start working; S202, the real-time running frequency of the compressor is acquired, and when the real-time running frequency of the compressor is greater than or equal to the preset operation frequency, the control device controls the four-way component to be powered on. The control method can avoid the intermediate gas leakage problem of the four-way component in the mode switching process, and improves the smoothness during mode switching.

Description

Technical Field

[0001] This invention relates to the field of air conditioning heat pump system technology, and in particular to a variable frequency heat pump system and its control method. Background Technology

[0002] Variable frequency heat pump systems typically employ a four-way reversing valve to change the refrigerant flow direction, thereby switching between cooling and heating modes. The four-way reversing valve changes the conduction relationship between the input and output ports by energizing and de-energizing its coil, thus altering the refrigerant flow direction. Normally, the four-way reversing valve is energized when in cooling mode and de-energized when in heating mode.

[0003] Existing variable frequency heat pump systems have a problem of gas leakage during the switching between heating and cooling modes using their four-way reversing valves. This risk is even greater when the variable frequency heat pump system is operating within a load range where the high and low pressure compression ratio is small, which reduces the cooling or heating performance of the system.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a control method for a variable frequency heat pump system, which can avoid the problem of gas leakage in the middle of the four-way component during mode switching and improve the smoothness of mode switching.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A control method for a variable frequency heat pump system, the variable frequency heat pump system including a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device; the four-way assembly includes a piston body and a pilot valve, the pilot valve having a sliding cavity with a slider slidably disposed therein; the piston body having a piston chamber with a main slide valve slidably disposed therein; the D1 port of the piston body being connected to the output end of the compressor and the D2 port of the pilot valve, the S1 port of the piston body and the S2 port of the pilot valve being connected to the input end of the compressor; the E2 port and C2 port of the pilot valve being connected to the piston chamber; the E1 port and C1 port of the piston body being connected to the outdoor unit and the indoor unit, respectively; the control method includes the following steps:

[0008] S101. When the variable frequency heat pump system is in cooling mode, if a control command to switch to heating mode is received, the four-way component is energized and placed in the cooling position, and then the compressor is started to work.

[0009] S102. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to lose power and the four-way component is in the heating position.

[0010] S201. When the variable frequency heat pump system is in heating mode, if a control command to switch to cooling mode is received, the control device controls the four-way component to remain in working state and controls the compressor to start working.

[0011] S202. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to be energized, and the four-way component is in the cooling position.

[0012] In the control method of the variable frequency heat pump system, in step S201, the control device controls the four-way component to maintain the default start-up working state, which is that the four-way valve is de-energized.

[0013] In the control method of the variable frequency heat pump system, the preset operating frequency is 15Hz.

[0014] The control method for the variable frequency heat pump system further includes the following steps:

[0015] S301. When a shutdown command is received, obtain the operating mode executed when the variable frequency heat pump system shuts down;

[0016] S321. When the machine is stopped, the operating mode is cooling mode. When the start command is received, the control device controls the four-way component to be energized first, and then controls the compressor to start working.

[0017] The control method for the variable frequency heat pump system further includes the following steps:

[0018] S401. When a shutdown command is received, obtain the operating mode executed when the variable frequency heat pump system shuts down;

[0019] S402. When the operating mode executed during shutdown is cooling mode, the control device first controls the compressor to stop working. After the preset power failure time is reached, the control device controls the four-way component to lose power.

[0020] The present invention also provides a variable frequency heat pump system, wherein the variable frequency heat pump system is controlled by any of the control methods described above. The variable frequency heat pump system includes a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device. The four-way assembly includes a piston body and a pilot valve. The pilot valve has a sliding cavity, and a slider is slidably disposed within the sliding cavity. The piston body has a piston chamber, and a main slide valve is slidably disposed within the piston chamber. The D1 port of the piston body is connected to the compressor. The output end of the compressor is connected to the D2 port of the pilot valve, and the S1 port of the piston body and the S2 port of the pilot valve are respectively connected to the input end of the compressor; the E2 port and C2 port of the pilot valve are respectively used to connect to the piston chamber; the E1 port and C1 port of the piston body are respectively used to connect to the outdoor unit and the indoor unit, and the slider is used to adjust the conduction relationship of the E2 port, S2 port and C2 port; the main slide valve is used to adjust the conduction relationship of the E1 port, S1 port and C1 port; the outdoor unit is also connected to the indoor unit.

[0021] The variable frequency heat pump system also includes a throttling valve, through which the outdoor unit is connected to the indoor unit.

[0022] In the aforementioned variable frequency heat pump system, an electromagnetic coil is provided on one side of the pilot valve, and the slider is a metal slider. The electromagnetic coil is inductively connected to the slider. A spring is also provided inside the sliding cavity. One end of the spring is connected to one side of the slider, and the other end of the spring is connected to the inner wall of one side of the sliding cavity. The spring and the electromagnetic coil are located on the same side. A first conductive cavity and a second conductive cavity are provided at the bottom of the slider. The first conductive cavity is used to adjust the conduction relationship of the E2 port, the S2 port, and the C2 port, and the second conductive cavity is used to realize the conduction between the D2 port and the C2 port.

[0023] In the aforementioned variable frequency heat pump system, the main slide valve includes a first conductive block and a second conductive block. The first conductive block comprises two blocks, which are respectively disposed at both ends of the second conductive block. A first conductive groove is formed on the first conductive block, which is used to realize the conductive relationship between port D1 and port E1 or to realize the conductive relationship between port D1 and port C1. A second conductive groove is formed on the second conductive block, which is used to adjust the conductive relationship between port E1, port S1, and port C1.

[0024] Beneficial effects:

[0025] This invention provides a control method for a variable frequency heat pump system. When switching between cooling and heating modes, the method first controls the four-way valve assembly to maintain its operating mode consistent with the previous operating mode, and then controls the compressor to operate for a certain period of time before switching the operating mode of the four-way valve assembly. This avoids the problem of gas leakage in the four-way valve assembly during mode switching, improves the smoothness of mode switching, and enhances the stability and performance of the variable frequency heat pump system when it is in heating or cooling mode. Attached Figure Description

[0026] Figure 1 This is a system structure diagram of the variable frequency heat pump system provided by the present invention when it is in cooling mode;

[0027] Figure 2 This is a system structure diagram of the variable frequency heat pump system in heating mode provided by the present invention;

[0028] Figure 3 A first logic flowchart of the control method provided by the present invention;

[0029] Figure 4 A second logic flowchart of the control method provided by the present invention;

[0030] Figure 5 The third logic flowchart of the control method provided by the present invention.

[0031] Explanation of key component symbols: 1-capillary tube, 2-pilot valve, 21-slider, 22-electromagnetic coil, 23-spring, 3-piston body, 31-piston cavity, 32-first conducting block, 321-first conducting groove, 33-second conducting block, 331-second conducting groove. Detailed Implementation

[0032] This invention provides a variable frequency heat pump system and its control method. To make the purpose, technical solution and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0033] In the description of this invention, it should be understood that the terms "installation" and "connection" should be interpreted broadly, and those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Please see Figures 1 to 5This invention provides a control method for a variable frequency heat pump system. The variable frequency heat pump system includes a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device. The four-way assembly includes a piston body 3 and a pilot valve 2. The pilot valve 2 has a sliding cavity, and a slider 21 is slidably disposed within the sliding cavity. The piston body 3 has a piston chamber 31, and a main slide valve is slidably disposed within the piston chamber 31. The D1 port of the piston body 3 is connected to the output end of the compressor and the D2 port of the pilot valve 2, respectively. The S1 port of the piston body 3 and the S2 port of the pilot valve 2 are connected to the input end of the compressor, respectively. The E2 port and C2 port of the pilot valve 2 are respectively used to connect to the piston chamber 31. The E1 port and C1 port of the piston body 3 are respectively used to connect to the outdoor unit and the indoor unit. The control method includes the following steps:

[0035] S101. When the variable frequency heat pump system is in cooling mode, if a control command to switch to heating mode is received, the four-way component is energized and placed in the cooling position, and then the compressor is started to work.

[0036] S102. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to lose power and the four-way component is in the heating position.

[0037] S201. When the variable frequency heat pump system is in heating mode, if a control command to switch to cooling mode is received, the control device controls the four-way component to remain in working state and controls the compressor to start working.

[0038] S202. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to be energized, and the four-way component is in the cooling position.

[0039] The method for implementing a variable frequency heat pump system disclosed in this application, when switching between cooling and heating modes, first controls the four-way valve assembly to maintain its operating mode consistent with the operating mode before the switch. That is, if the variable frequency heat pump system was in heating mode before the switch, the four-way valve assembly remains in the heating position; if the variable frequency heat pump system was in cooling mode before the switch, the four-way valve remains in the cooling position. Then, the compressor is controlled to work for a certain period of time before the operating mode of the four-way valve assembly is switched. This avoids the problem of gas leakage in the four-way valve assembly during mode switching, improves the smoothness of mode switching, and improves the working stability and performance of the variable frequency heat pump system when executing heating or cooling modes.

[0040] Specifically, when the four-way assembly is in the cooling position, it is energized. The slider 21 inside the pilot valve 2 moves to one side of the slide cavity under the magnetic force generated by the electromagnetic coil 22. Figure 1 When the valve moves to the right, the D2 port of pilot valve 2 connects to the E2 port via the sliding cavity, and the S2 port of pilot valve 2 connects to the C2 port. The high-pressure gas discharged from the compressor enters the capillary tube 1 sequentially through the D1 and D2 ports, and then enters the other side of the piston chamber 31 through the E2 port. Figure 1 The middle is on the left; on the other hand, gas is discharged from one side of piston chamber 31. Figure 1 The middle position is on the right. Due to the pressure difference across the main slide valve, the main slide valve moves towards one side of the piston chamber 31. Figure 1 The piston moves to the right, making the S1 port of piston body 3 connected to the C1 port, and the D1 port of piston body 3 connected to the E1 port, thus forming a refrigeration cycle.

[0041] Specifically, when the four-way assembly is in the heating position, it is de-energized. The slider 21 inside the pilot valve 2 moves to the other side of the sliding cavity under the restoring force of the spring 23. Figure 2 When the valve shifts to the left, the D2 port of pilot valve 2 is connected to the C2 port, and the S2 port of pilot valve 2 is connected to the E2 port; the high-pressure gas discharged from the compressor enters the capillary tube 1 through the D1 port and the D2 port in sequence, and then enters one side of the piston chamber 31 through the C2 port. Figure 2 The middle is on the right side; on the other hand, gas is discharged from the other side of piston chamber 31. Figure 2 On the left side, due to the pressure difference across the main slide valve, the main slide valve moves to the other side of the piston chamber 31. Figure 1 The piston moves to the left, making the S1 and E1 ports of the piston body 3 connected, and the D1 and C1 ports of the piston body 3 connected, thus forming a heating cycle.

[0042] The basic conditions for the reversing of a four-way reversing valve are: ① The pressure difference between the two ends of the piston must be greater than the frictional resistance; ② The discharge flow rate of the compressor is much greater than the intermediate flow rate of the four-way reversing valve, which is related to the design parameters of the four-way reversing valve. In the prior art, when switching between cooling and heating modes, after the compressor starts, the pressure difference between the two ends of the four-way reversing valve gradually increases from 0. When the pressure difference between the two ends of the piston chamber 31 is greater than the frictional force of the main slide valve, the main slide valve moves in the heating or cooling direction. When it passes the intermediate position, due to the influence of the intermediate flow rate, the pressure difference increases. The pressure will drop rapidly. If the compressor's operating frequency is too low, the main slide valve may be in the middle position, causing gas leakage. In this application, the energization and de-energization state of the four-way component is adjusted only after ensuring that the compressor's operating frequency reaches the preset operating frequency. That is, the working mode of the four-way component is adjusted only after ensuring that a sufficient pressure difference is established, so as to avoid gas leakage problems in the four-way component. In this embodiment, the four-way component is energized by the control device outputting a strong electrical signal to it. When the control device stops outputting the strong electrical signal to the four-way component, the four-way component is de-energized.

[0043] Furthermore, in the prior art, when switching modes, the four-way valve is turned on according to the switched mode. That is, in the prior art, when switching from heating mode to cooling mode, if the variable frequency heat pump system starts working, the four-way reversing valve is in an energized state; while when switching from cooling mode to heating mode, if the variable frequency heat pump system starts working, the four-way reversing valve is in a de-energized state. In this application, when switching from cooling mode to heating mode, if the variable frequency heat pump system starts working, the four-way component is energized first, and then the compressor is controlled to start working. This ensures that the four-way component is in the cooling position before the compressor starts working, so that when the compressor operating frequency exceeds the preset operating frequency, that is, after establishing a sufficient pressure difference, the four-way component will perform the working mode switch.

[0044] Furthermore, in step S201, the control device controls the four-way assembly to maintain the default power-on working state, which is that the four-way valve is de-energized. In this embodiment, since the working mode of the variable frequency heat pump system before switching is the heating mode, when the heat pump variable frequency system starts working, the four-way assembly is kept in the heating position and the four-way assembly is in the de-energized state.

[0045] Furthermore, the preset operating frequency is 15Hz. The operating frequency can be preset by the designer according to the design parameters of the compressor and the four-way component, so that the switching conditions meet the actual working requirements.

[0046] Further, please refer to Figure 4 The control method further includes the following steps:

[0047] S301. When a shutdown command is received, obtain the operating mode executed when the variable frequency heat pump system shuts down;

[0048] S321. When the machine is stopped, the operating mode is cooling mode. When the start command is received, the control device controls the four-way component to be energized first, and then controls the compressor to start working.

[0049] Further, please refer to Figure 5 The control method further includes the following steps:

[0050] S401. When a shutdown command is received, obtain the operating mode executed when the variable frequency heat pump system shuts down;

[0051] S402. When the operating mode executed during shutdown is cooling mode, the control device first controls the compressor to stop working. After the preset power-off time is reached, the control device controls the four-way component to lose power, so that the four-way component remains in the shutdown state after the variable frequency compressor system stops. Due to the pressure difference, the four-way component remains in the cooling position during the period when the compressor starts working but the four-way component is not powered. In this embodiment, the power-off time is 1 minute, and the power-off time can be preset by the designer according to the design of the four-way component.

[0052] In existing technologies, during the shutdown of a variable frequency heat pump system, the four-way component returns to a de-energized state and resumes its heating position. When the system restarts, the compressor is controlled to operate for a certain period before the four-way component is energized. If the system operates in cooling mode during shutdown, the component remains in heating mode during the period between compressor startup and de-energization, resulting in energy waste. In this application, if the system operates in cooling mode during shutdown, the four-way component is controlled to de-energize after a certain delay following compressor power failure, or energized before compressor startup, ensuring the component remains in cooling mode. This solves the energy waste problem and reduces energy consumption during the startup phase of the variable frequency heat pump system.

[0053] Please see Figure 1 and Figure 2The present invention also provides a variable frequency heat pump system, wherein the variable frequency heat pump system is controlled by any of the control methods described above. The variable frequency heat pump system includes a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device. The four-way assembly includes a piston body 3 and a pilot valve 2. The pilot valve 2 has a sliding cavity, and a slider 21 is slidably disposed within the sliding cavity. The piston body 3 has a piston chamber 31, and a main slide valve is slidably disposed within the piston chamber 31. The D1 port of the piston body 3 is connected to the compressor... The output end of the compressor is connected to the D2 port of the pilot valve 2. The S1 port of the piston body 3 and the S2 port of the pilot valve 2 are respectively connected to the input end of the compressor. The E2 port and C2 port of the pilot valve 2 are respectively used to connect to the piston chamber 31. The E1 port and C1 port of the piston body 3 are respectively used to connect to the outdoor unit and the indoor unit. The slider 21 is used to adjust the conduction relationship of the E2 port, S2 port and C2 port. The main slide valve is used to adjust the conduction relationship of the E1 port, S1 port and C1 port. The outdoor unit is also connected to the indoor unit.

[0054] Further, please refer to Figure 1 and Figure 2 The variable frequency heat pump system also includes a throttling valve, through which the outdoor unit is connected to the indoor unit.

[0055] Further, please refer to Figure 1 and Figure 2 An electromagnetic coil 22 is provided on one side of the pilot valve 2, and the slider 21 is a metal slider 21. The electromagnetic coil 22 is inductively connected to the slider 21. A spring 23 is also provided in the slide cavity. One end of the spring 23 is connected to one side of the slider 21, and the other end of the spring 23 is connected to the inner wall of one side of the slide cavity. The spring 23 and the electromagnetic coil 22 are located on the same side. A first conductive cavity and a second conductive cavity are opened at the bottom of the slider 21. The first conductive cavity is used to adjust the conduction relationship of the E2 port, the S2 port and the C2 port, and the second conductive cavity is used to realize the conduction of the D2 port and the C2 port.

[0056] Further, please refer to Figure 1 and Figure 2The main slide valve includes a first conductive block 32 and a second conductive block 33. The first conductive block 32 includes two blocks, which are respectively disposed at both ends of the second conductive block 33. A first conductive groove 321 is formed on the first conductive block 32, which is used to realize the conductive relationship between port D1 and port E1 or to realize the conductive relationship between port D1 and port C1. A second conductive groove 331 is formed on the second conductive block 33, which is used to adjust the conductive relationship between port E1, port S1 and port C1. In this embodiment, the first conductive block 32 and the second conductive block 33 are integrally formed.

[0057] In the variable frequency heat pump system disclosed in this application, during actual operation, when the variable frequency heat pump system is in cooling mode, the four-way component is energized, and the slider 21 inside the pilot valve 2 moves to one side of the sliding cavity under the action of the magnetic force generated by the electromagnetic coil 22. Figure 1 The pilot valve 2 moves to the right, with port D2 connected to port E2 via the sliding cavity, and port S2 connected to port C2 via the first connecting cavity. The high-pressure gas discharged from the compressor enters capillary tube 1 sequentially through ports D1 and D2, and then enters the other side of piston chamber 31 through port E2. Figure 1 The middle is on the left; on the other hand, gas is discharged from one side of piston chamber 31. Figure 1 The middle position is on the right. Due to the pressure difference across the main slide valve, the main slide valve moves towards one side of the piston chamber 31. Figure 1 The piston body 3 is moved to the right, so that the S1 port of the piston body 3 is connected to the C1 port through the second conductive groove 331, and the D1 port of the piston body 3 is connected to the E1 port through the first conductive groove 321. The low-temperature refrigerant enters the indoor unit through the E1 port of the piston body 3. After heat exchange, the refrigerant enters the outdoor unit through the throttling valve, and then returns to the input end of the compressor through the C1 port, the second conductive groove 331 and the S1 port of the piston body 3 in sequence, thus realizing the refrigeration cycle.

[0058] Furthermore, when the variable frequency heat pump system operates in heating mode, the four-way assembly is de-energized, and the slider 21 inside the pilot valve 2 moves to the other side of the sliding cavity under the restoring force of the spring 23. Figure 2 The pilot valve 2 shifts to the left, with port D2 of the pilot valve 2 connected to port C2 via the second conducting chamber, and port S2 of the pilot valve 2 connected to port E2 via the first conducting chamber. The high-pressure gas discharged from the compressor enters capillary tube 1 sequentially through ports D1 and D2, and then enters one side of piston chamber 31 through port C2. Figure 2 The middle is on the right side; on the other hand, gas is discharged from the other side of piston chamber 31. Figure 2 On the left side, due to the pressure difference across the main slide valve, the main slide valve moves to the other side of the piston chamber 31. Figure 1 The piston body 3 is moved to the left, so that the S1 port of the piston body 3 is connected to the E1 port through the second guide groove 331, and the D1 port of the piston body 3 is connected to the C1 port through the first guide groove 321. The refrigerant enters the outdoor unit through the C1 port of the piston body 3, then enters the indoor unit through the throttle valve, and then returns to the input end of the compressor through the E1 port, the second guide groove 331 and the S1 port of the piston body 3 in sequence, thus realizing the heating cycle.

[0059] It is understood that those skilled in the art can make equivalent substitutions or changes to the technical solution and inventive concept of the present invention, and all such changes or substitutions should fall within the protection scope of the present invention.

Claims

1. A control method for a variable frequency heat pump system, characterized in that, The variable frequency heat pump system includes a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device. The four-way assembly includes a piston body and a pilot valve. The pilot valve has a sliding cavity with a slider slidably disposed within it. The piston body has a piston chamber with a main slide valve slidably disposed within it. The D1 port of the piston body is connected to the output end of the compressor and the D2 port of the pilot valve, respectively. The S1 port of the piston body and the S2 port of the pilot valve are connected to the input end of the compressor, respectively. The E2 and C2 ports of the pilot valve are connected to the piston chamber, respectively. The E1 and C1 ports of the piston body are connected to the outdoor unit and the indoor unit, respectively. The control method includes the following steps: S101. When the variable frequency heat pump system is in cooling mode, if a control command to switch to heating mode is received, the four-way component is energized and placed in the cooling position, and then the compressor is started to work. S102. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to lose power and the four-way component is in the heating position. S201. When the variable frequency heat pump system is in heating mode, if a control command to switch to cooling mode is received, the control device controls the four-way component to maintain the default start-up working state. The default start-up working state is that the four-way component is de-energized and the compressor is controlled to start working. S202. Obtain the real-time operating frequency of the compressor. When the real-time operating frequency of the compressor is greater than or equal to the preset operating frequency, the control device controls the four-way component to be energized, and the four-way component is in the cooling position. When a shutdown command is received, the operating mode executed by the variable frequency heat pump system at the time of shutdown is obtained. If the variable frequency heat pump system is in cooling mode at the time of shutdown, the four-way component is controlled to be de-energized after a preset power failure time after the compressor is de-energized, or when the system is restarted, the four-way component is first energized before the compressor starts working, so that the four-way component is always in the cooling position.

2. The control method for the variable frequency heat pump system according to claim 1, characterized in that, The preset operating frequency is 15Hz.

3. A variable frequency heat pump system, characterized in that, The variable frequency heat pump system employs the control method described in claim 1 or 2 to achieve operational control. The variable frequency heat pump system includes a control device, an outdoor unit, an indoor unit, and a compressor and a four-way assembly electrically connected to the control device. The four-way assembly includes a piston body and a pilot valve. The pilot valve has a sliding cavity, and a slider is slidably disposed within the sliding cavity. The piston body has a piston chamber, and a main slide valve is slidably disposed within the piston chamber. The D1 port of the piston body is connected to the output end of the compressor and the... The pilot valve's D2 port is connected, and the piston body's S1 port and the pilot valve's S2 port are respectively connected to the compressor's input end; the pilot valve's E2 port and C2 port are respectively used to connect to the piston chamber; the piston body's E1 port and C1 port are respectively used to connect to the outdoor unit and the indoor unit; the slider is used to adjust the conduction relationship of the E2 port, S2 port, and C2 port; the main slide valve is used to adjust the conduction relationship of the E1 port, S1 port, and C1 port; the outdoor unit is also connected to the indoor unit.

4. A variable frequency heat pump system according to claim 3, characterized in that, It also includes a throttle valve, through which the outdoor unit is connected to the indoor unit.

5. A variable frequency heat pump system according to claim 3, characterized in that, An electromagnetic coil is provided on one side of the pilot valve, and the slider is a metal slider. The electromagnetic coil is inductively connected to the slider. A spring is also provided inside the slide cavity. One end of the spring is connected to one side of the slider, and the other end of the spring is connected to the inner wall of one side of the slide cavity. The spring and the electromagnetic coil are located on the same side. A first conductive cavity and a second conductive cavity are opened at the bottom of the slider. The first conductive cavity is used to adjust the conduction relationship of the E2 port, the S2 port, and the C2 port, and the second conductive cavity is used to realize the conduction of the D2 port and the C2 port.

6. A variable frequency heat pump system according to claim 3, characterized in that, The main slide valve includes a first conducting block and a second conducting block. The first conducting block comprises two blocks, which are respectively disposed at both ends of the second conducting block. A first conducting groove is formed on the first conducting block, which is used to realize the conducting relationship between port D1 and port E1 or to realize the conducting relationship between port D1 and port C1. A second conducting groove is formed on the second conducting block, which is used to adjust the conducting relationship between port E1, port S1 and port C1.

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