Heat pump system and its control method

Abstract

The present invention provides a heat pump system and its control method, relating to the technical field of heat pump systems, including a compressor. The exhaust port of the compressor is connected to an oil separator through a pipeline. One end of the oil separator is connected to a shell-and-tube condenser. The outlet of the shell-and-tube condenser is connected to the main cavity of an economizer. The main cavity of the economizer is connected to a main expansion valve. The main expansion valve is connected to an evaporator. The evaporator is connected to the suction port of the compressor. In the backwashing process of the present application, the blocked oil liquid is discharged from the filter element, and the backwashing gas is filtered to avoid interference with subsequent use. After the backwashing is completed, reset is achieved through the first spring and the second spring for the next round of flushing. Through the present application, the blocked oil liquid can be flushed to avoid affecting the operation efficiency and safety of the entire unit due to excessive oil blockage.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump systems, and more particularly, to a heat pump system and its control method. Background Art

[0002] A heat pump system transfers heat through four core components (compressor, condenser, expansion valve, evaporator). During the operation of the compressor, an oil separator needs to be used in conjunction to separate the gas discharged by the compressor. For example, a new vertical oil separator structure for a compressor with the patent publication number CN217402909U includes: an oil separator housing, a top cover is fixedly connected to the top of the oil separator housing, an oil separator exhaust outlet is provided in the middle of the top cover, and the inner wall surface of the oil separator housing is coated with refrigeration oil; a starting exhaust flow channel is formed at the bottom of the outer wall of the oil separator housing, a terminal exhaust flow channel is formed at the top of the outer wall of the oil separator housing, the terminal exhaust flow channel is communicated with the inside of the oil separator housing, and the starting exhaust flow channel and the terminal exhaust flow channel are communicated through a middle exhaust flow channel; an exhaust guide plate is connected to the bottom of the oil separator exhaust outlet.

[0003] During the operation of the above oil separator, the oil and gas are separated through a filter element. However, after long-term operation, the outside of the filter element holes will be blocked by oil, resulting in the situation of filter element blockage during the operation of the oil separator. This not only causes the oil and gas to be unable to be separated, but also makes the internal gas unable to be discharged, further causing excessive pressure inside the oil separator and easily posing a safety hazard. Therefore, this application designs a heat pump system to ensure that the operation efficiency of the entire unit will not be affected due to blockage inside the oil separator during the operation of the heat pump system. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a heat pump system and its control method, which solves the problem that the pressure inside the oil separator of the heat pump system becomes too high due to blockage of the filter element during long-term use, thus causing a safety hazard.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A heat pump system includes a compressor, the exhaust port of the compressor is connected to an oil separator through a pipeline, one end of the oil separator is connected to a shell-and-tube condenser, the outlet of the shell-and-tube condenser is connected to the main cavity of an economizer, the main cavity of the economizer is connected to a main expansion valve, the main expansion valve is connected to an evaporator, and the evaporator is connected to the suction port of the compressor;

[0007] The lower end of the oil separator is connected to an oil tank, the oil tank is connected to the oil inlet of an oil cooler, the oil cooler is connected to the oil return port of the compressor, and an oil temperature sensor is installed on the pipeline;

[0008] The inlet of the secondary cavity of the economizer is connected to the economizer expansion valve, the outlet of the secondary cavity of the economizer is connected to the oil cooler expansion valve, the oil cooler expansion valve is connected to the inlet of the oil cooler, and the outlet of the oil cooler is connected to another suction port of the compressor;

[0009] A branch pipe is provided on the pipeline between the main expansion valve and the economizer and is connected with an electric bypass valve. The electric bypass valve is connected to the pipeline between the shell-and-tube condenser and the main cavity of the economizer through the branch pipe.

[0010] Preferably, the oil separator includes a housing, an upper cover is arranged on the upper side of the housing, an oil outlet valve is arranged on the lower side of the housing, a feed pipe is installed on one side of the housing, and the feed pipe is connected to the exhaust port of the compressor;

[0011] The oil outlet valve is connected to an oil tank through a pipeline. The upper cover is provided with an air outlet pipe, and the air outlet pipe is connected to the shell-and-tube condenser through a pipeline. A buffer assembly for preventing excessive pressure is arranged on one side of the housing, and a separation assembly for separation is installed between the upper cover and the housing.

[0012] Preferably, the separation assembly includes a fixed cover. A screw hole is formed on the surface of the housing, a bolt is arranged on the outer side of the upper cover, and the bolt passes through the fixed cover and is in threaded cooperation with the screw hole. A positioning frame is installed inside the fixed cover, a filter element is installed inside the positioning frame, and a plurality of through holes are formed on the surface of the fixed cover.

[0013] Preferably, a collection base is arranged at the bottom of the fixed cover. A socket is installed on one side of the upper cover, an oil suction pipe is installed inside the socket through a nut, the lower end of the oil suction pipe is located inside the collection base, a liquid suction pump is arranged at the upper end of the oil suction pipe, and the liquid suction pump is connected to the oil tank.

[0014] Preferably, the buffer assembly includes an expansion pipe. The expansion pipe is arranged on one side of the housing. A sealing ring is arranged at one end of the expansion pipe. A sealing piston is movably and hermetically arranged inside the sealing ring. A limiting ring is installed on the inner wall of the expansion pipe, and a compression spring is installed between the limiting ring and the sealing piston.

[0015] Preferably, an expansion frame is fixedly installed on the outer side of the housing, a buffer tank is fixedly installed inside the expansion frame, a one-way valve is installed at the lower end of the buffer tank, a connecting pipe is arranged at the upper end of the buffer tank, and the one-way valve is connected to the expansion pipe.

[0016] Preferably, a guide pipe is installed at the air outlet end of the one-way valve. An extrusion cover is installed on the pipe body of the guide pipe through a sealing sliding ring. An auxiliary spring is installed between the extrusion cover and the bottom of the buffer tank.

[0017] Preferably, a recoil pipe is installed at the center of the upper cover. The upper end of the recoil pipe is connected to a connecting pipe. An activity slot is provided inside the recoil pipe. An activity sleeve is installed inside the activity slot through a first spring. A nozzle is arranged inside the activity sleeve.

[0018] Preferably, a transfer shell is arranged at the bottom of the upper cover. A wind guide cover and an extension cover are respectively arranged at the bottom of the transfer shell. The wind guide cover is aligned with the air outlet pipe, and the extension cover is aligned with the recoil pipe. A wind guide rotary disc is rotatably installed inside the extension cover through a rotating shaft. A plurality of dispersion holes are provided on the outer side of the extension cover.

[0019] A matching slide rail is arranged on the inner wall of the transfer shell. A plugging slider is slidably installed inside the matching slide rail. A second spring is installed between the plugging slider and the transfer shell. Both the plugging slider and the end of the activity sleeve are inclined and are in limit cooperation.

[0020] A control method for a heat pump system includes the following steps:

[0021] S1: Before the unit starts, the economizer expansion valve is fully open, and the oil cooler expansion valve is fully closed.

[0022] S2: After the unit starts, when the oil temperature sensor detects that the oil temperature is lower than the set value during the start-up stage, the electric bypass valve is fully open, and the oil cooler expansion valve remains fully closed. All the refrigerant directly enters the main expansion valve through the electric bypass valve to participate in the main system refrigeration cycle, enabling the unit to achieve rapid heating.

[0023] S3: When the oil temperature sensor detects that the oil temperature is higher than the set value, gradually close the electric bypass valve until it is fully closed, and at the same time gradually open the oil cooler expansion valve. Control the oil temperature within the target range by adjusting the opening degree of the oil cooler expansion valve.

[0024] S4: After the system operates stably, on the premise that the oil temperature is controlled within the target range as the first control element, the system gradually reduces the opening degree of the economizer expansion valve and opens the oil cooler expansion valve to control the supercooling degree at the inlet of the main expansion valve within the target range, thereby improving the operating efficiency of the unit.

[0025] S5: After the system compressor is fully loaded and the hot water temperature of the shell-and-tube condenser is lower than the target value, on the premise that the oil temperature is controlled within the target range as the first control element, the system gradually reduces the opening degree of the economizer expansion valve and opens the oil cooler expansion valve to control the supercooling degree at the inlet of the main expansion valve within the target range, thereby increasing the heating capacity of the unit.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. Through this system, the oil pressure and temperature during the operation of the heat pump unit can be monitored in real time to ensure that during continuous operation, the operation efficiency of the unit will not be affected by excessive oil temperature. When the oil temperature is too high, the electric bypass valve is gradually closed until it is fully closed, and at the same time, the expansion valve of the oil cooler is gradually opened. By adjusting the opening of the expansion valve of the oil cooler, the oil temperature is controlled within the target range. After the system compressor is fully loaded, when the hot water temperature of the shell-and-tube condenser is lower than the target value, on the premise that the oil temperature is controlled within the target range as the first control factor, the system gradually reduces the opening of the economizer expansion valve and opens the expansion valve of the oil cooler to control the subcooling degree at the inlet of the main expansion valve within the target range, thereby improving the heating capacity of the unit.

[0028] 2. The gas discharged from the compressor is introduced through the feed pipe. The gas is sprayed on the fixed cover. By using the through holes opened on the surface of the fixed cover, the gas will enter the filter element, and the oil contained in the gas is filtered. After the gas passes through the filter element, the gas will be discharged along the outlet pipe, thus realizing the separation of the gas. During the separation process, as the amount of oil increases, the oil droplets will accumulate into oil liquid, and some oil liquid will penetrate into the filter element. The collection base is arranged at the bottom of the fixed cover to collect the penetrated oil liquid. To prevent excessive accumulation of oil liquid from interfering with the use of the filter element, the liquid extraction pump is started to make the inside of the extraction pipe have suction, and the bottom of the extraction pipe is arranged at the collection base, so that the oil liquid inside the collection base will be pumped outwards. After the extraction, the liquid extraction pump stops and the valve is closed to block the extraction pipe channel to avoid affecting the subsequent separation effect.

[0029] 3. When the filter element is blocked by oil, with the continuous intake of gas through the feed pipe, the pressure inside the housing increases. During the process of pressure increase, when the sealing piston is subjected to the current pressure, the compression spring will contract, and a gap will be generated between the sealing piston and the sealing ring, thus avoiding the problem of potential safety hazards caused by excessive pressure inside the housing, and further ensuring the safety of the heat pump system during operation;

[0030] The overpressure gas enters the expansion pipe and then passes through the one-way valve, and then enters the buffer tank, and is located between the extrusion cover and the buffer tank. The internal space of the buffer tank can change, so that the buffer tank can collect the current gas and the auxiliary spring contracts as the gas increases, and the internal space of the buffer tank increases, realizing backwashing and energy charging. When the gas pressure inside the buffer tank is greater than the pressure cooperated between the first spring and the second spring, the gas inside the buffer tank will be transferred to the separation component for backwashing operation, and the auxiliary spring can be used to reduce the internal space of the buffer tank to ensure the coherence of the current gas during discharge and realize a stable backwashing operation.

[0031] 4. When the charging gas is sent into the recoil pipe, its pressure is applied to the movable sleeve, causing the movable sleeve to move downward. During the movement, the movable sleeve and the plugging slider are inclined to cooperate with each other, thereby pushing open the plugging slider, so that the plugging slider blocks the air outlet pipe during the backwashing process to prevent the unfiltered gas from being discharged, and ensure that the current gas passes through the filter element in the reverse direction, realizing the backwashing of the blocked oil in the filter element and filtering its own oil content at the same time. The filtered oil will fall into the collection base for subsequent processing. Through the above structure, the present application can discharge the blocked oil from the filter element during the backwashing process and filter the backwashing gas to avoid interfering with subsequent use. After the backwashing is completed, the first spring and the second spring are used to reset for the next round of washing. Through the present application, the blocked oil can be washed to avoid affecting the operation efficiency and safety of the entire unit due to excessive oil blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of the heat pump system of the present invention;

[0033] Figure 2 is a three-dimensional structure diagram of the oil separator;

[0034] Figure 3 is a top view structure diagram of the oil separator;

[0035] Figure 4 is Figure 3 the sectional structure diagram at A-A in

[0036] Figure 5 is Figure 4 the enlarged structure diagram at a in

[0037] Figure 6 is Figure 4 the enlarged structure diagram at b in;

[0038] Figure 7 is Figure 4 the enlarged structure diagram at c in;

[0039] Figure 8 is Figure 3 the sectional structure diagram at B-B in;

[0040] Figure 9 is Figure 8 the enlarged structure diagram at d in;

[0041] Figure 10 is a front view structure diagram of the oil separator;

[0042] Figure 11 is Figure 10 the sectional structure diagram at C-C in.

[0043] In the figure: 1. Compressor; 2. Oil separator; 201. Housing; 2011. Screw hole; 202. Upper cover; 2021. Bolt; 2022. Air outlet pipe; 2023. Backflush pipe; 2024. Movable groove; 2025. First spring; 2026. Movable sleeve; 2027. Spray nozzle; 203. Feed pipe; 204. Buffer assembly; 2041. Expansion pipe; 2042. Sealing ring; 2043. Sealing piston; 2044. Limit ring; 2045. Compression spring; 2046. Expansion frame; 2047. Buffer tank; 2048. Check valve; 2049. Air guide pipe; 20410. Extrusion cover; 20411. Sealing sliding ring; 20412. Connecting pipe; 20413. Auxiliary spring; 205. Oil outlet valve; 206. Separation assembly; 2061. Fixed cover; 2062. Filter element; 2063. Through hole; 2064. Oil suction pipe; 2065. Collection base; 2066. Positioning frame; 2067. Socket; 2068. Liquid extraction pump; 207. Transfer housing; 2071. Plugging slider; 2072. Second spring; 2073. Air guide cover; 2074. Extension cover; 2075. Rotating shaft; 2076. Air guide turntable; 2077. Dispersion hole; 2078. Matching slide rail; 3. Shell and tube condenser; 4. Economizer; 5. Evaporator; 6. Oil tank; 7. Oil cooler; 8. Oil temperature sensor; 9. Main expansion valve; 901. Electric bypass valve; 902. Economizer expansion valve; 903. Oil cooler expansion valve. Specific embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0045] As Figures 1 to 11 shown, the heat pump system includes a compressor 1. The exhaust port of the compressor 1 is connected to an oil separator 2 through a pipeline. One end of the oil separator 2 is connected to a shell and tube condenser 3. The outlet of the shell and tube condenser 3 is connected to the main cavity of an economizer 4. The main cavity of the economizer 4 is connected to a main expansion valve 9. The main expansion valve 9 is connected to an evaporator 5. The evaporator 5 is connected to the suction port of the compressor 1;

[0046] The lower end of the oil separator 2 is connected to an oil tank 6. The oil tank 6 is connected to the oil inlet of an oil cooler 7. The oil cooler 7 is connected to the oil return port of the compressor 1 and an oil temperature sensor 8 is installed on the pipeline;

[0047] The inlet of the 4th cavity of the economizer is connected to the economizer expansion valve 902, and the outlet of the 4th cavity of the economizer is connected to the oil cooler expansion valve 903. The oil cooler expansion valve 903 is connected to the inlet of the 7th oil cooler, and the outlet of the 7th oil cooler is connected to the other suction port of the compressor 1;

[0048] There is a branch pipe on the pipeline between the main expansion valve 9 and the economizer 4 and an electric bypass valve 901 is connected. The electric bypass valve 901 is connected to the pipeline between the shell-and-tube condenser 3 and the main cavity of the economizer 4 through the branch pipe.

[0049] The exhaust of the compressor 1 is connected to the oil separator 2. The outlet of the oil separator 2 is connected to the shell-and-tube condenser 3. The downstream of the shell-and-tube condenser 3 is connected to the inlet of the main cavity of the economizer 4. The outlet of the main cavity of the economizer 4 is connected to the main expansion valve 9 through a pipeline. The main expansion valve 9 is connected to the evaporator 5, and the evaporator 5 is connected to the suction port of the compressor 1. The above components and pipelines form the main loop of the heat pump system.

[0050] An oil temperature sensor 8 is arranged on the pipeline of the oil cooler 7 and the oil return port of the compressor 1 to detect the oil temperature;

[0051] An oil pressure and temperature sensor is arranged at the inlet of the main expansion valve 9 to calculate the subcooling degree at the inlet of the main expansion valve 9;

[0052] The electric bypass valve 901 performs bypass adjustment, and its opening range is from 0% to 100%.

[0053] Through this system, the oil pressure and temperature during the operation of the heat pump unit can be monitored in real time to ensure that the operation efficiency of the unit will not be interfered by too high oil temperature during continuous operation. And when the oil temperature is too high, the electric bypass valve 901 is gradually closed to fully closed, and at the same time, the oil cooler expansion valve 903 is gradually opened. The oil temperature is controlled within the target range by adjusting the opening of the oil cooler expansion valve 903. And after the compressor 1 of the system is fully loaded and the hot water temperature of the shell-and-tube condenser 3 is lower than the target value, on the premise that the oil temperature is controlled within the target range as the first control element, the system gradually reduces the opening of the economizer expansion valve 902 and opens the oil cooler expansion valve 903 to control the subcooling degree at the inlet of the main expansion valve 9 within the target range, thereby improving the heating capacity of the unit.

[0054] In this embodiment, the oil separator 2 includes a housing 201. An upper cover 202 is arranged on the upper side of the housing 201. An oil outlet valve 205 is arranged on the lower side of the housing 201. A feed pipe 203 is installed on one side of the housing 201, and the feed pipe 203 is connected to the exhaust port of the compressor 1;

[0055] The oil outlet valve 205 is connected to the oil tank 6 through a pipeline. The upper cover 202 is provided with an air outlet pipe 2022, and the air outlet pipe 2022 is connected to the shell-and-tube condenser 3 through a pipeline. One side of the shell 201 is provided with a buffer assembly 204 for preventing excessive pressure. A separation assembly 206 for separation is installed between the upper cover 202 and the shell 201.

[0056] In this application, the separation assembly 206 includes a fixed cover 2061. A screw hole 2011 is formed on the surface of the shell 201, and a bolt 2021 is arranged on the outside of the upper cover 202. The bolt 2021 passes through the fixed cover 2061 and is in threaded cooperation with the screw hole 2011. A positioning frame 2066 is installed inside the fixed cover 2061, a filter element 2062 is installed inside the positioning frame 2066, and a number of through holes 2063 are formed on the surface of the fixed cover 2061.

[0057] The oil discharged after separation by the oil separator 2 can be controlled by the oil outlet valve 205. Generally, when the separated oil is stored to a certain content, it is discharged into the oil tank 6. By disassembling and assembling the bolt 2021, the separation assembly 206 can be quickly accessed, so as to facilitate the cleaning or replacement of the filter element 2062 used for a long time, thereby improving the operating efficiency of the entire heat pump unit.

[0058] It should be noted that a collection base 2065 is arranged at the bottom of the fixed cover 2061. A socket 2067 is installed on one side of the upper cover 202. An oil suction pipe 2064 is installed inside the socket 2067 through a nut. The lower end of the oil suction pipe 2064 is located inside the collection base 2065, and a liquid suction pump 2068 is arranged at the upper end of the oil suction pipe 2064. The liquid suction pump 2068 is connected to the oil tank 6.

[0059] The gas discharged from the compressor 1 is introduced through the feed pipe 203. The gas will spray on the fixed cover 2061. By using the through holes 2063 formed on the surface of the fixed cover 2061, the gas will enter the filter element 2062, and the oil contained in the gas will be filtered. After the gas passes through the filter element 2062, the gas will be discharged along the air outlet pipe 2022, thereby realizing the separation of the gas. During the separation process, as the amount of oil increases, the oil droplets will accumulate into oil liquid, resulting in some oil liquid seeping into the filter element 2062. The collection base 2065 arranged at the bottom of the fixed cover 2061 can collect the seeped oil liquid. In order to avoid excessive accumulation of oil liquid interfering with the use of the filter element 2062, by starting the liquid suction pump 2068, the inside of the oil suction pipe 2064 has suction, and by using the bottom of the oil suction pipe 2064 arranged at the collection base 2065, the oil liquid inside the collection base 2065 will be pumped outwards. After the pumping, the liquid suction pump 2068 stops and the valve is closed to block the passage of the oil suction pipe 2064 to avoid affecting the subsequent separation effect.

[0060] In this application, the buffer assembly 204 includes an extension tube 2041. The extension tube 2041 is arranged on one side of the housing 201. A sealing ring 2042 is arranged at one end of the extension tube 2041. A sealing piston 2043 is movably and sealingly arranged inside the sealing ring 2042. A limiting ring 2044 is installed on the inner wall of the extension tube 2041. A compression spring 2045 is installed between the limiting ring 2044 and the sealing piston 2043.

[0061] Specifically, an extension frame 2046 is fixedly installed on the outer side of the housing 201. A buffer tank 2047 is fixedly installed inside the extension frame 2046. A one-way valve 2048 is installed at the lower end of the buffer tank 2047. A connecting pipe 20412 is arranged at the upper end of the buffer tank 2047. The one-way valve 2048 is connected to the extension tube 2041.

[0062] Wherein, a gas guide pipe 2049 is installed at the air outlet end of the one-way valve 2048. An extrusion cover 20410 is installed on the pipe body of the gas guide pipe 2049 through a sealing sliding ring 20411. An auxiliary spring 20413 is installed between the extrusion cover 20410 and the bottom of the buffer tank 2047.

[0063] When the filter element 2062 is blocked by oil, with the continuous intake of air through the feed pipe 203, the pressure inside the housing 201 increases. During the process of pressure increase, when the sealing piston 2043 is subjected to the current pressure, the compression spring 2045 will contract, and a gap will be generated between the sealing piston 2043 and the sealing ring 2042, thus avoiding the problem of potential safety hazards caused by excessive pressure inside the housing 201, and further ensuring the safety of the heat pump system during operation;

[0064] And through the overpressure gas entering the extension tube 2041 and then passing through the one-way valve 2048, it enters the buffer tank 2047, and is located between the extrusion cover 20410 and the buffer tank 2047. Since the internal space of the buffer tank 2047 can change, the buffer tank 2047 can collect the current gas and the auxiliary spring 20413 will contract as the gas increases, and the internal space of the buffer tank 2047 increases, realizing backwashing and energy charging. When the gas pressure inside the buffer tank 2047 is greater than the pressure formed by the cooperation between the first spring 2025 and the second spring 2072, the gas inside the buffer tank 2047 will be transferred to the separation assembly 206 for backwashing operation, and the auxiliary spring 20413 can be used to reduce the internal space of the buffer tank 2047, so as to ensure the coherence of the current gas during discharge and realize a stable backwashing operation.

[0065] In the present application, a recoil pipe 2023 is installed at the center of the upper cover 202. The upper end of the recoil pipe 2023 is connected to a connecting pipe 20412. An activity slot 2024 is provided inside the recoil pipe 2023. An activity sleeve 2026 is installed inside the activity slot 2024 through a first spring 2025. A nozzle 2027 is arranged inside the activity sleeve 2026.

[0066] During specific setting, a transfer shell 207 is arranged at the bottom of the upper cover 202. A wind guide cover 2073 and an extension cover 2074 are respectively arranged at the bottom of the transfer shell 207. The wind guide cover 2073 is aligned with the air outlet pipe 2022, and the extension cover 2074 is aligned with the recoil pipe 2023. A wind guide rotary disk 2076 is rotatably installed inside the extension cover 2074 through a rotating shaft 2075. A number of dispersion holes 2077 are provided on the outer side of the extension cover 2074;

[0067] A matching slide rail 2078 is arranged on the inner wall of the transfer shell 207. A plugging slider 2071 is slidably installed inside the matching slide rail 2078. A second spring 2072 is installed between the plugging slider 2071 and the transfer shell 207. The ends of both the plugging slider 2071 and the activity sleeve 2026 are inclined and are in limit cooperation.

[0068] When the charging gas is sent into the recoil pipe 2023, its pressure will be applied to the activity sleeve 2026, causing the activity sleeve 2026 to move downward. During the movement, the inclined cooperation between the activity sleeve 2026 and the plugging slider 2071 is utilized to push open the plugging slider 2071, so that the plugging slider 2071 blocks the air outlet pipe 2022 during the backwashing process to prevent unfiltered gas from being discharged, and it is ensured that the current gas passes through the filter element 2062 in the reverse direction, realizing the reverse flushing of the blocked oil in the filter element 2062 and filtering the oil in it at the same time. The filtered oil will fall into the collection base 2065 for subsequent treatment. Through the above structure, the present application can discharge the blocked oil from the filter element 2062 during the backwashing process and filter the backwashing gas to avoid interfering with subsequent use. After the backwashing is completed, the reset is realized through the first spring 2025 and the second spring 2072 for the next round of flushing. Through the present application, the blocked oil can be flushed to avoid affecting the operation efficiency of the entire unit due to excessive oil blockage.

[0069] A control method for a heat pump system includes the following steps:

[0070] S1: Before the unit starts, the economizer expansion valve 902 is fully opened, and the oil cooler expansion valve 903 is fully closed;

[0071] S2: After the unit starts up, when the oil temperature sensor 8 detects that the oil temperature is lower than the set value during the startup stage, the electric bypass valve 901 is fully opened, and the expansion valve 903 of the oil cooler remains fully closed. All the refrigerant directly enters the main expansion valve 9 through the electric bypass valve 901 to participate in the refrigeration cycle of the main system, enabling the unit to achieve rapid heating;

[0072] S3: When the oil temperature sensor 8 detects that the oil temperature is higher than the set value, gradually close the electric bypass valve 901 until it is fully closed, and at the same time gradually open the expansion valve 903 of the oil cooler. Control the oil temperature within the target range by adjusting the opening degree of the expansion valve 903 of the oil cooler;

[0073] S4: After the system runs stably, on the premise that controlling the oil temperature within the target range is the first control factor, the system gradually reduces the opening degree of the economizer expansion valve 902 and opens the expansion valve 903 of the oil cooler to control the inlet subcooling degree of the main expansion valve 9 within the target range, thereby improving the operating efficiency of the unit;

[0074] S5: After the system compressor 1 is fully loaded and the hot water temperature of the shell-and-tube condenser 3 is lower than the target value, on the premise that controlling the oil temperature within the target range is the first control factor, the system gradually reduces the opening degree of the economizer expansion valve 902 and opens the expansion valve 903 of the oil cooler to control the inlet subcooling degree of the main expansion valve 9 within the target range, thereby increasing the heating capacity of the unit.

[0075] In S4, here "after the system runs stably" means that after the target hot water temperature has been reached, through the interlocking control of the economizer expansion valve 902 and the expansion valve 903 of the oil cooler, the total refrigeration capacity of the refrigerant evaporation in the economizer 4 and the oil cooler 7 is increased. Keep the refrigeration capacity of the refrigerant in the oil cooler 7 unchanged, thereby maintaining the oil temperature not exceeding the target temperature + / - 5°C, which is the allowable deviation for the compressor 1. The increased refrigerant evaporation refrigeration capacity occurs in the economizer 4, and its function is to condense the high-pressure saturated refrigerant in the main circuit, thereby establishing a certain target subcooling degree. Subcooling can make the refrigerant liquid temperature lower than the saturation temperature, reduce the generation of flash gas during throttling, retain more refrigerant in the liquid state, and can effectively evaporate and absorb heat after entering the evaporator 5, thereby increasing the refrigeration capacity / heating capacity and energy efficiency. The increase in heating capacity causes the hot water temperature to deviate from the target value, and the target hot water temperature is controlled by adjusting the load of the compressor 1.

[0076] The difference between S5 and S4 is that the compressor 1 is already fully loaded but the hot water temperature has not reached the target temperature. This means that the heating capacity of the system is lower than the demand. Through the linked control of the economizer expansion valve 902 and the oil cooler expansion valve 903, the total refrigeration capacity of the refrigerant evaporation in the economizer 4 and the oil cooler 7 is increased. The refrigeration capacity of the refrigerant in the oil cooler 7 is maintained unchanged, so as to maintain the oil temperature not exceeding the target temperature + / - 5°C, which is the allowable deviation for the compressor 1. The increased refrigerant evaporation refrigeration capacity occurs in the economizer 4, and its function is to condense the high-pressure saturated refrigerant in the main circuit, thereby establishing a certain target subcooling degree. Subcooling can make the refrigerant liquid temperature lower than the saturation temperature, reduce the generation of flash gas during throttling, retain more refrigerant in the liquid state, and can effectively evaporate and absorb heat after entering the evaporator 5, thereby improving the refrigeration capacity, heating capacity and energy efficiency of the unit. Based on the heat pump unit using the screw compressor 1, where the refrigerant used in the refrigerator is R134a, a reasonable design of the economizer 4 can effectively increase the heating capacity of the system by 5% - 10%.

[0077] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A heat pump system comprising a compressor (1), characterized in that: The exhaust port of the compressor (1) is connected to the oil separator (2) via a pipeline; one end of the oil separator (2) is connected to the shell and tube condenser (3); the outlet of the shell and tube condenser (3) is connected to the main cavity of the economizer (4); the main cavity of the economizer (4) is connected to the main expansion valve (9); the main expansion valve (9) is connected to the evaporator (5); and the evaporator (5) is connected to the air return port of the compressor (1); The lower end of the oil separator (2) is connected to an oil tank (6), the oil tank (6) is connected to the oil inlet of an oil cooler (7), the oil cooler (7) is connected to the oil return port of the compressor (1) and an oil temperature sensor (8) is installed on the pipeline; The inlet of the secondary cavity of the economizer (4) is connected to the economizer expansion valve (902), the outlet of the secondary cavity of the economizer (4) is connected to the oil cooler expansion valve (903), the oil cooler expansion valve (903) is connected to the air inlet of the oil cooler (7), and the air outlet of the oil cooler (7) is connected to another air return port of the compressor (1); A branch pipe is provided on the pipeline between the main expansion valve (9) and the economizer (4) and is connected to an electric bypass valve (901); the electric bypass valve (901) is connected to the pipeline between the shell and tube condenser (3) and the main cavity of the economizer (4) through the branch pipe; The oil separator (2) comprises a housing (201), an upper cover (202) is arranged on the upper side of the housing (201), a buffer component (204) for preventing excessive pressure is arranged on one side of the housing (201), and a separation component (206) for separation is installed between the upper cover (202) and the housing (201); The separation component (206) comprises a fixed cover (2061), a positioning frame (2066) is installed inside the fixed cover (2061), and a filter element (2062) is installed inside the positioning frame (2066); The buffer assembly (204) comprises an extension tube (2041), the extension tube (2041) being arranged on one side of the housing (201), a sealing ring (2042) being arranged at one end of the extension tube (2041), a sealing piston (2043) being arranged inside the sealing ring (2042) for movable sealing, an extension frame (2046) being fixedly mounted on the outside of the housing (201), a buffer tank (2047) being fixedly mounted inside the extension frame (2046), a one-way valve (2048) being mounted at the lower end of the buffer tank (2047), a connecting tube (20412) being arranged at the upper end of the buffer tank (2047), and the one-way valve (2048) being connected to the extension tube (2041); A through socket (2067) is installed on one side of the upper cover (202), and an oil extraction pipe (2064) is installed inside the through socket (2067) via a nut; A recoil pipe (2023) is installed at the center of the upper cover (202), the upper end of the recoil pipe (2023) is connected to the connecting pipe (20412), a transfer shell (207) is arranged at the bottom of the upper cover (202), and an air guide cover (2073) and an extension cover (2074) are respectively arranged at the bottom of the transfer shell (207), and the extension cover (2074) is aligned with the recoil pipe (2023).

2. The heat pump system according to claim 1, characterized in that: An oil outlet valve (205) is provided on the lower side of the shell (201), and a feed pipe (203) is installed on one side of the shell (201), wherein the feed pipe (203) is connected to the exhaust port of the compressor (1); The oil outlet valve (205) is connected to the oil tank (6) via a pipeline, and the upper cover (202) is provided with an air outlet pipe (2022), and the air outlet pipe (2022) is connected to the shell and tube condenser (3) via a pipeline.

3. The heat pump system according to claim 2, characterized in that: The shell (201) has a screw hole (2011) on its surface, the upper cover (202) has a bolt (2021) on its outer side, the bolt (2021) passes through the fixing cover (2061) and is threadedly engaged with the screw hole (2011), and the fixing cover (2061) has a plurality of through holes (2063) on its surface.

4. The heat pump system according to claim 3, characterized in that: A collecting base (2065) is provided at the bottom of the fixed cover (2061), and the lower end of the oil extraction pipe (2064) is located inside the collecting base (2065).

5. The heat pump system according to claim 4, characterized in that: A liquid extraction pump (2068) is provided at the upper end of the oil extraction pipe (2064), and the liquid extraction pump (2068) is connected to the oil tank (6).

6. The heat pump system according to claim 2, characterized in that: A limit ring (2044) is installed on the inner wall of the extension tube (2041), and a compression spring (2045) is installed between the limit ring (2044) and the sealing piston (2043).

7. The heat pump system according to claim 6, characterized in that: An air guide pipe (2049) is installed at the air outlet end of the one-way valve (2048); an extrusion cover (20410) is installed on the body of the air guide pipe (2049) via a sealing slip ring (20411); an auxiliary spring (20413) is installed between the extrusion cover (20410) and the bottom of the buffer tank (2047).

8. The heat pump system according to claim 6, characterized in that: A movable groove (2024) is provided inside the recoil pipe (2023), a movable sleeve (2026) is installed inside the movable groove (2024) via a first spring (2025), and a nozzle (2027) is provided inside the movable sleeve (2026).

9. The heat pump system according to claim 8, characterized in that: The air guide cover (2073) is aligned with the air outlet pipe (2022); an air guide turntable (2076) is rotatably mounted inside the extension cover (2074) via a rotating shaft (2075); and a plurality of dispersed holes (2077) are provided on the outside of the extension cover (2074); The inner wall of the transfer shell (207) is provided with a matching slide rail (2078), a blocking slider (2071) is slidably installed inside the matching slide rail (2078), a second spring (2072) is installed between the blocking slider (2071) and the transfer shell (207), and the ends of the blocking slider (2071) and the movable sleeve (2026) are both inclined and limited.

10. The control method of the heat pump system according to claim 1, characterized in that: The following steps are involved: S1: Before the unit is started, the economizer expansion valve (902) is fully opened and the oil cooler expansion valve (903) is fully closed; S2: After the unit is started, when the oil temperature sensor (8) detects that the oil temperature is lower than the set value during the startup phase, the electric bypass valve (901) is fully opened, the oil cooler expansion valve (903) remains fully closed, and all refrigerant directly enters the main expansion valve (9) through the electric bypass valve (901) to participate in the main system refrigeration cycle, so that the unit can achieve rapid heating; S3: When the oil temperature sensor (8) detects that the oil temperature is higher than the set value, the electric bypass valve (901) is gradually closed to fully closed, and the oil cooler expansion valve (903) is gradually opened, and the oil temperature is controlled to be within the target range by adjusting the opening of the oil cooler expansion valve (903); S4: After the system is running stably, under the premise that the oil temperature is controlled within the target range as the first control factor, the system gradually reduces the opening of the economizer expansion valve (902) and opens the oil cooler expansion valve (903) to control the inlet subcooling of the main expansion valve (9) to the target range, thereby improving the unit operation efficiency; S5: After the system compressor (1) is fully loaded, the hot water temperature of the shell and tube condenser (3) is lower than the target value. Under the premise that the oil temperature is controlled within the target range as the first control factor, the system gradually reduces the opening of the economizer expansion valve (902) and opens the oil cooler expansion valve (903) to control the inlet subcooling of the main expansion valve (9) to within the target range, thereby increasing the heating capacity of the unit.

Images