JP6771508B2 - Air conditioner - Google Patents

Description

The present invention relates to an air conditioner.

Patent Document 1 discloses a vehicle air conditioner including a heat pump cycle in which a refrigerant is evaporated by an outdoor heat exchanger and air blown out into a vehicle interior by an indoor heat exchanger is heated. In this vehicle air conditioner, the compressor is switched off when the actual high-pressure side refrigerant pressure exceeds the target high-pressure side refrigerant pressure.

Japanese Unexamined Patent Publication No. 2014-058205

However, in the vehicle air conditioner described in Patent Document 1, the temperature of the indoor heat exchanger has not dropped after the compressor is turned off when the actual high-pressure side refrigerant pressure exceeds the target high-pressure side refrigerant pressure. The compressor is also switched on when only the pressure of the refrigerant drops. Therefore, switching of the compressor on / off may be repeated frequently.

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the frequency of repeating on / off of a compressor in an air conditioner.

According to an aspect of the present invention, the air conditioner mounted on the vehicle uses a compressor that compresses the refrigerant and the heat of the refrigerant that compresses the air guided to the passenger compartment of the vehicle by the compressor. The indoor heat exchanger to be heated, the refrigerant pressure detector that detects the pressure of the refrigerant compressed by the compressor, and the refrigerant pressure detector to the target refrigerant pressure corresponding to the target blowing temperature of air into the passenger compartment. The control unit includes a control unit that controls the rotation speed of the compressor so that the pressure detected by the compressor approaches the pressure detected by the compressor, even if the pressure detected by the refrigerant pressure detector becomes higher than the target refrigerant pressure. When the pressure difference from the target refrigerant pressure is smaller than the set pressure, the compressor is operated at the minimum rotation speed.

In the above aspect, even if the pressure of the refrigerant compressed by the compressor becomes higher than the target refrigerant pressure, if the pressure difference from the target refrigerant pressure is smaller than the set pressure, the minimum rotation speed without stopping the compressor. Let's drive with. Therefore, the compressor cannot be switched off only while the compressor is operated at the minimum rotation speed. Further, the refrigerant pressure when the compressor is stopped is higher than the target refrigerant pressure by a set pressure. Therefore, it is suppressed that the compressor is switched on immediately after being switched off. Therefore, it is possible to reduce the frequency of repeating on / off of the compressor in the air conditioner.

FIG. 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention. FIG. 2 is a control block diagram of the air conditioner. FIG. 3 is a configuration diagram of an air conditioner according to a modified example of the embodiment of the present invention. FIG. 4 is a diagram illustrating the flow of the refrigerant of the air conditioner in the cooling mode. FIG. 5 is a diagram illustrating a flow of refrigerant in the air conditioner in the heat pump heating mode. FIG. 6 is a flowchart illustrating switching of the compressor operation mode with respect to the temperature of the heat medium. FIG. 7 is a transition diagram illustrating switching of the compressor operation mode with respect to the temperature of the heat medium.

Hereinafter, the air conditioner 100 according to the embodiment of the present invention will be described with reference to the drawings.

First, the configuration of the air conditioner 100 will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, the air conditioner 100 includes a refrigerating cycle 2 in which a refrigerant circulates, a hot water cycle 4 in which hot water as a heat medium circulates, and HVAC (Heating Ventilation and Air Conditioning) through which air used for air conditioning passes. ) A unit 5 and a controller 10 as a control unit for controlling the operation of the air conditioner 100 are provided.

The air conditioner 100 is a heat pump system capable of heating and cooling. The air conditioner 100 is mounted on a vehicle (not shown) to air-condition the interior of the vehicle interior (not shown). For example, HFO-1234yf is used as the refrigerant, and antifreeze is used as the hot water.

The refrigeration cycle 2 includes a compressor 21 as a compressor, a water cooling capacitor 22 as a refrigerant-heat medium heat exchanger, an outdoor heat exchanger 23, a liquid receiver 24, an internal heat exchanger 30, and an evaporator. Evaporator 25, a thermal expansion valve 26 as an expansion valve, a fixed throttle 27, a bypass path 20a through which a refrigerant bypassing the fixed throttle 27 flows, and a second flow as a flow path switching valve that opens and closes the bypass path 20a. It includes a path switching valve 29 and a refrigerant flow path 20 that connects them so that the refrigerant can circulate. The refrigerant flow path 20 is provided with a first flow path switching valve 28.

The compressor 21 sucks in a gaseous (gas phase) refrigerant and compresses it. As a result, the gaseous refrigerant becomes high temperature and high pressure.

The water-cooled condenser 22 functions as a condenser that condenses the refrigerant after passing through the compressor 21 during the heating operation. The water-cooled condenser 22 exchanges heat between the refrigerant whose high temperature and high pressure are increased by the compressor 21 and the hot water circulating in the hot water cycle 4, and heats the hot water by the heat of the refrigerant. The refrigerant condensed by the water-cooled condenser 22 flows to the fixed throttle 27.

The water-cooled condenser 22 uses the heat of the refrigerant compressed by the compressor 21 to heat the air used for air conditioning, which is guided into the vehicle interior through the hot water circulating in the hot water cycle 4. Here, the water cooling condenser 22 and the hot water cycle 4 correspond to an indoor heat exchanger that heats the air guided into the vehicle interior. Instead of this, as shown in FIG. 3, the refrigerant compressed by the compressor 21 may be directly guided to the heater core 42 without providing the hot water cycle 4. In this case, the heater core 42 corresponds to the indoor heat exchanger.

The outdoor heat exchanger 23 is arranged, for example, in the engine room of a vehicle (motor room in an electric vehicle), and exchanges heat between the refrigerant and the outside air. The outdoor heat exchanger 23 functions as a condenser during the cooling operation and as an evaporator during the heating operation. Outside air is introduced into the outdoor heat exchanger 23 by traveling the vehicle or rotating the outdoor fan 6.

The liquid receiver 24 is located downstream of the outdoor heat exchanger 23, introduces the refrigerant from the outdoor heat exchanger 23, and separates the liquid (liquid phase) refrigerant and the gaseous refrigerant into gas and liquid. The liquid receiver 24 has a liquid storage unit 24a for storing the liquid refrigerant, an outlet for guiding the liquid refrigerant to the evaporator 25, and an outlet for guiding the gaseous refrigerant to the compressor 21. Although omitted in FIG. 1 for conceptual purposes, the passage for guiding the gaseous refrigerant to the compressor 21 is configured so that the oil contained in the circuit can be returned.

The liquid receiver 24 guides the gaseous refrigerant flowing from the outdoor heat exchanger 23 to the compressor 21 during the heating operation. Only the separated gaseous refrigerant flows from the receiver 24 to the compressor 21. During the cooling operation, the liquid receiver 24 stores the liquid refrigerant flowing from the outdoor heat exchanger 23, and guides a part of the liquid refrigerant to the evaporator 25 via the internal heat exchanger 30 and the temperature expansion valve 26. Only the separated liquid refrigerant flows from the receiver 24 to the evaporator 25.

A differential pressure valve 31 is provided between the liquid receiver 24 and the temperature expansion valve 26. The differential pressure valve 31 is provided upstream of the internal heat exchanger 30. The differential pressure valve 31 opens when the pressure on the upstream side of the differential pressure valve 31 exceeds the set pressure. This set pressure is preset to a pressure at which the differential pressure valve 31 does not open during the heating operation and the differential pressure valve 31 opens only during the cooling operation. By providing the differential pressure valve 31, it is possible to prevent the refrigerant from flowing from the liquid receiver 24 to the evaporator 25 via the temperature expansion valve 26 during the heating operation. Therefore, it is possible to prevent the evaporator 25 from freezing and the lubricating oil flowing in the refrigerant flow path 20 from being stored in the evaporator 25. The differential pressure valve 31 may be provided between the internal heat exchanger 30 and the temperature expansion valve 26.

The evaporator 25 is arranged in the HVAC unit 5. When the operation mode of the refrigerating cycle 2 is the cooling mode, the evaporator 25 absorbs the heat of the air guided to the vehicle interior into the refrigerant to evaporate the refrigerant. The refrigerant evaporated in the evaporator 25 flows to the compressor 21 via the internal heat exchanger 30.

The temperature type expansion valve 26 is arranged between the internal heat exchanger 30 and the evaporator 25, and decompresses and expands the liquid refrigerant guided from the outdoor heat exchanger 23 via the receiver 24 and the internal heat exchanger 30. .. The temperature type expansion valve 26 automatically adjusts the opening degree according to the temperature of the refrigerant that has passed through the evaporator 25, that is, the degree of superheat of the gaseous refrigerant.

When the load on the evaporator 25 increases, the degree of superheat of the gaseous refrigerant increases. Then, the opening degree of the temperature type expansion valve 26 becomes large, and the amount of the refrigerant increases so as to adjust the degree of superheat. On the other hand, when the load of the evaporator 25 is reduced, the degree of superheat of the gaseous refrigerant is reduced. Then, the opening degree of the temperature type expansion valve 26 becomes small, and the amount of the refrigerant decreases so as to adjust the degree of superheat. In this way, the temperature type expansion valve 26 feeds back the temperature of the gaseous refrigerant that has passed through the evaporator 25, and adjusts the opening degree so that the gaseous refrigerant has an appropriate degree of superheat.

The internal heat exchanger 30 exchanges heat between the refrigerant upstream of the thermal expansion valve 26 and the refrigerant downstream of the evaporator 25 by utilizing the temperature difference.

The fixed throttle 27 is arranged between the water-cooled condenser 22 and the outdoor heat exchanger 23, and the refrigerant compressed by the compressor 21 and condensed by the water-cooled condenser 22 is decompressed and expanded. For the fixed diaphragm 27, for example, an orifice or a capillary tube is used. The diaphragm amount of the fixed diaphragm 27 is set in advance so as to correspond to a specific operating condition that is frequently used. In the present embodiment, the fixed throttle 27, the bypass path 20a, and the first flow path switching valve 28 correspond to the throttle mechanism.

Instead of the fixed diaphragm 27, for example, as in the modified example shown in FIG. 3, electromagnetic waves as an electric diaphragm mechanism that has at least a fully open diaphragm state and a predetermined diaphragm state and can adjust the opening degree stepwise or steplessly. The throttle valve 127 may be used as a variable throttle (throttle mechanism). In this case, it is not necessary to provide the bypass path 20a. The electromagnetic throttle valve 127 is adjusted so as not to throttle the flow of the refrigerant during the cooling operation, and is adjusted so as not to throttle the flow of the refrigerant during the heating operation.

The first flow path switching valve 28 switches the flow of the refrigerant by opening and closing. The first flow path switching valve 28 is a solenoid valve having a solenoid controlled by the controller 10.

During the cooling operation, the first flow path switching valve 28 is closed. As a result, the refrigerant condensed in the outdoor heat exchanger 23 flows into the liquid receiver 24, the pressure on the upstream side of the differential pressure valve 31 exceeds the set pressure, and the liquid refrigerant expands in the internal heat exchanger 30 and the temperature system. It passes through the valve 26 and the evaporator 25 and is guided to the compressor 21. On the other hand, during the heating operation, the first flow path switching valve 28 is opened. As a result, the refrigerant evaporated in the outdoor heat exchanger 23 flows into the liquid receiver 24, passes through the first flow path switching valve 28, and is guided to the compressor 21. Therefore, during the heating operation, the refrigerant flows by bypassing the internal heat exchanger 30, the temperature expansion valve 26, and the evaporator 25.

The second flow path switching valve 29 switches the flow of the refrigerant by opening and closing. The second flow path switching valve 29 is a solenoid valve having a solenoid controlled by the controller 10.

During the cooling operation, the second flow path switching valve 29 is opened. As a result, the refrigerant compressed by the compressor 21 passes through the water-cooled condenser 22, then bypasses the fixed throttle 27 and flows into the outdoor heat exchanger 23. On the other hand, during the heating operation, the second flow path switching valve 29 is closed. As a result, the refrigerant compressed by the compressor 21 passes through the water cooling condenser 22 and the fixed throttle 27 and flows into the outdoor heat exchanger 23.

The hot water cycle 4 includes a water pump 41 as a pump, a heater core 42, a hot water heater 43 as an auxiliary heater, a water cooling condenser 22, and a hot water flow path 40 connecting these so that hot water can circulate. To be equipped.

The water pump 41 circulates hot water in the hot water flow path 40.

The heater core 42 is arranged in the HVAC unit 5 and heats the air used for air conditioning by heat exchange between the air passing through the heater core 42 and the hot water during the heating operation.

The hot water heater 43 assists in heating the air guided to the passenger compartment. The hot water heater 43 has a heater (not shown) inside, and heats hot water using external power. As the heater, for example, a sheathed heater or a PTC (Positive Temperature Coefficient) heater is used.

Instead of the hot water heater 43, for example, an pneumatic heater (not shown) that directly heats the air guided to the passenger compartment or exhaust heat of the engine (not shown) as the internal combustion engine of the vehicle is used to guide the air to the passenger compartment. A hot water heat exchanger (not shown) that heats the air to be obtained may be used. Further, any one of the hot water heater 43, the pneumatic heater, and the hot water heat exchanger may be used alone, or any combination thereof may be used.

The HVAC unit 5 cools or heats the air used for air conditioning. The HVAC unit 5 includes a blower 52, an air mix door 53, and a case 51 that surrounds the blower 52 so that air used for air conditioning can pass through the HVAC unit 5. The evaporator 25 and the heater core 42 are arranged in the HVAC unit 5. The air blown from the blower 52 exchanges heat with the refrigerant flowing in the evaporator 25 and with the hot water flowing in the heater core 42.

The blower 52 is a blower that blows air into the HVAC unit 5.

The air mix door 53 adjusts the amount of air passing through the heater core 42 arranged in the HVAC unit 5. The air mix door 53 is installed on the blower 52 side of the heater core 42. The air mix door 53 opens the heater core 42 side during the heating operation and closes the heater core 42 side during the cooling operation. The amount of heat exchange between the air and the hot water in the heater core 42 is adjusted by the opening degree of the air mix door 53.

The air conditioner 100 includes a discharge pressure sensor 11 as a refrigerant pressure detector, an outdoor heat exchanger outlet temperature sensor 12 as a refrigerant temperature detector, an evaporator temperature sensor 13 as an evaporator temperature detector, and an outside air temperature detection. An outside temperature sensor 15 as a vessel and a water temperature sensor 16 as a heat medium temperature detector are installed.

The discharge pressure sensor 11 is installed in the refrigerant flow path 20 on the discharge side of the compressor 21 and detects the discharge pressure Pd [Pa] of the gaseous refrigerant compressed by the compressor 21.

The outdoor heat exchanger outlet temperature sensor 12 is provided at the outlet of the outdoor heat exchanger 23 and detects the temperature of the refrigerant in the refrigerant flow path 20. The outdoor heat exchanger outlet temperature sensor 12 detects the temperature of the refrigerant that has passed through the outdoor heat exchanger 23.

The evaporator temperature sensor 13 is installed on the downstream side of the air flow of the evaporator 25 in the HVAC unit 5 and detects the temperature of the air that has passed through the evaporator 25. The evaporator temperature sensor 13 may be installed directly on the evaporator 25.

The outside air temperature sensor 15 detects the temperature of the outside air before it is taken into the outdoor heat exchanger 23 and passes through.

The water temperature sensor 16 is installed in the hot water flow path 40 near the outlet of the hot water heater 43. The water temperature sensor 16 may be provided in the hot water heater 43. The water temperature sensor 16 detects the temperature Tw [° C.] of the hot water guided to the heater core 42.

The controller 10 is a microcomputer composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. It is also possible to configure the controller 10 with a plurality of microcomputers. The controller 10 causes the air conditioner 100 to exert various functions by reading the program stored in the ROM by the CPU.

The controller 10 is programmed to perform control of the air conditioner 100. As shown in FIG. 2, signals from the discharge pressure sensor 11, the outdoor heat exchanger outlet temperature sensor 12, the evaporator temperature sensor 13, the outside air temperature sensor 15, and the water temperature sensor 16 are input to the controller 10. Will be done. A signal from another sensor (not shown) may be input to the controller 10.

The controller 10 executes the control of the refrigeration cycle 2 based on the input signal. That is, as shown by the broken line in FIG. 1, the controller 10 sets the rotation speed (rotation speed) D [rpm] of the compressor 21, and opens and closes the first flow path switching valve 28 and the second flow path switching valve 29. Take control. Further, the controller 10 controls the hot water cycle 4 and the HVAC unit 5 by transmitting an output signal (not shown).

The controller 10 controls the rotation speed D of the compressor 21 as follows.

The controller 10 includes the vehicle interior temperature detected by the vehicle interior temperature sensor (not shown), the outside air temperature detected by the outside air temperature sensor 15, and the set temperature set by using the vehicle interior operation switch (not shown). And the amount of solar radiation detected by the solar radiation sensor (not shown) is input. From these input values, the controller 10 calculates the target blowout temperature To [° C.], which is the target temperature of the air guided into the vehicle interior.

The controller 10 calculates the target hot water temperature Two [° C.] as the target heat medium temperature, which is the target temperature of the hot water that needs to be supplied to the heater core 42 in order to set the air guided into the vehicle interior to the target outlet temperature To. The target hot water temperature Two is calculated by Two = To + α. α is a constant, for example, α = 2 [° C.].

The controller 10 calculates the target refrigerant temperature Tc [° C.], which is the target temperature of the refrigerant for setting the temperature Tw of the hot water supplied to the heater core 42 to the target hot water temperature Two. The target refrigerant temperature Tc is calculated by Tc = Tw + β. β is a constant, for example β = 1 [° C.].

The controller 10 calculates the target refrigerant pressure Pc [Pa], which is the target value of the discharge pressure Pd of the compressor 21 when the target refrigerant temperature Tc. Since there is a correlation between the saturation pressure of the refrigerant and the temperature, the target refrigerant pressure Pc can be calculated from the target refrigerant temperature Tc.

The controller 10 PI controls the rotation speed D of the compressor 21 so that the refrigerant pressure detected by the discharge pressure sensor 11 approaches the target refrigerant pressure Pc corresponding to the target blowing temperature To of air into the vehicle interior. In this way, since the controller 10 can calculate the target refrigerant pressure Pc once the target outlet temperature To is determined, the rotation speed D of the compressor 21 can be controlled based on the target outlet temperature To.

Next, each air conditioning operation mode of the air conditioner 100 will be described with reference to FIGS. 4 and 5.

<Cooling operation>
During the cooling operation, the refrigeration cycle 2 is switched to the cooling mode. In the cooling mode, the refrigerant in the refrigeration cycle 2 circulates as shown by the thick solid line in FIG.

The controller 10 keeps the first flow path switching valve 28 closed and the second flow path switching valve 29 open.

The refrigerant compressed by the compressor 21 to a high temperature and high pressure flows to the outdoor heat exchanger 23 through the water cooling condenser 22 and the second flow path switching valve 29. At this time, since the hot water in the hot water cycle 4 does not circulate, the water-cooled condenser 22 hardly exchanges heat. Further, the refrigerant bypasses the fixed throttle 27 and passes through the bypass path 20a. When an electromagnetic throttle valve 127 (see FIG. 2) is provided instead of the fixed throttle 27, the electromagnetic throttle valve 127 is adjusted so as not to throttle the flow of the refrigerant.

The refrigerant flowing to the outdoor heat exchanger 23 exchanges heat with the outside air introduced into the outdoor heat exchanger 23, is cooled, and then is gas-liquid separated by the receiver 24. As a result, the liquid refrigerant is stored in the receiver 24. A part of the liquid refrigerant flows from the receiver 24 to the temperature type expansion valve 26 connected to the downstream side of the receiver 24 via the internal heat exchanger 30.

After that, the liquid refrigerant is decompressed and expanded by the temperature expansion valve 26, flows to the evaporator 25, and evaporates by absorbing the heat of the air used for air conditioning when passing through the evaporator 25. The gaseous refrigerant evaporated in the evaporator 25 passes through the internal heat exchanger 30 and flows back to the compressor 21.

Here, the liquid refrigerant flowing from the receiver 24 to the internal heat exchanger 30 is a high-pressure fluid, and the degree of supercooling is substantially saturated at approximately 0 ° C. by gas-liquid separation in the receiver 24. It is in a liquid state. On the other hand, the gaseous refrigerant flowing from the evaporator 25 to the internal heat exchanger 30 expands under reduced pressure when passing through the temperature expansion valve 26 to become a low-temperature fluid. Therefore, the liquid refrigerant exchanges heat with the low-temperature gaseous refrigerant when flowing through the internal heat exchanger 30, and is excessively cooled by the gaseous refrigerant to have a degree of supercooling from the saturated liquid state. It will be in a cooled state. Further, the gaseous refrigerant is heated by the liquid refrigerant when flowing through the internal heat exchanger 30, so that the gaseous refrigerant is in a heated state having a degree of superheat.

The air cooled by the refrigerant in the evaporator 25 is flowed downstream of the HVAC unit 5 and used as cooling air.

<Heating operation>
During the heating operation, the refrigeration cycle 2 is switched to the heat pump heating mode. During the heating operation, a so-called endothermic heat pump operation is executed. In the heat pump heating mode, the refrigerant in the refrigeration cycle 2 and the hot water in the hot water cycle 4 circulate as shown by the thick solid line in FIG.

The controller 10 keeps the first flow path switching valve 28 open and the second flow path switching valve 29 closed.

The refrigerant compressed by the compressor 21 and having a high temperature flows to the water-cooled condenser 22. The refrigerant that has flowed to the water-cooled condenser 22 heats hot water inside the water-cooled condenser 22 and expands under reduced pressure through a fixed throttle 27 to become low in temperature and flows to the outdoor heat exchanger 23.

The refrigerant flowing to the outdoor heat exchanger 23 exchanges heat with the outside air introduced into the outdoor heat exchanger 23, and then flows to the receiver 24 for gas-liquid separation. Then, among the refrigerants gas-liquid separated by the liquid receiver 24, the gaseous refrigerant flows through the first flow path switching valve 28 to the compressor 21 again. As described above, in the heat pump heating mode, the liquid refrigerant is stored in the receiver 24, and the gaseous refrigerant is guided to the compressor 21.

On the other hand, the hot water heated by the refrigerant in the water cooling condenser 22 circulates and flows to the heater core 42 to heat the air around the heater core 42. The heated air is used as heating air by flowing to the downstream side of the HVAC unit 5.

If the refrigerant cannot sufficiently heat the hot water in the water-cooled condenser 22, the hot water may be heated in combination with the outside air endothermic heat pump operation or by operating the hot water heater 43 independently.

Next, switching of the operation mode of the compressor 21 during the heating operation will be described with reference to FIGS. 6 and 7. The controller 10 repeatedly executes the routine shown in FIG. 6 at regular time intervals, for example, every 10 milliseconds.

In step S11, the controller 10 detects the discharge pressure Pd of the compressor 21 based on the electric signal from the discharge pressure sensor 11.

In step S12, the controller 10 calculates the refrigerant pressure difference ΔP [Pa], which is the difference between the target refrigerant pressure Pc and the discharge pressure Pd.

In step S13, the controller 10 executes PI (Proportional Integral) control based on the refrigerant pressure difference ΔP, and calculates the rotation speed D of the compressor 21.

In step S14, the controller 10 detects the current operation mode of the compressor 21. The compressor 21 is operated in the first operation mode, the second operation mode, or the third operation mode.

The first operation mode is an operation mode in which the controller 10 PI controls the rotation speed D of the compressor 21 so that the discharge pressure Pd of the refrigerant detected by the discharge pressure sensor 11 approaches the target refrigerant pressure Pc. In the first operation mode, even if the calculated rotation speed D of the compressor 21 is lower than the minimum rotation speed (minimum rotation speed) Dmin [rpm], the controller 10 operates at the minimum rotation speed Dmin without stopping the compressor 21. To continue. The second operation mode is an operation mode in which the controller 10 fixes the compressor 21 at the minimum rotation speed Dmin and operates the compressor 21. The third operation mode is an operation mode in which the controller 10 stops the operation (rotation) of the compressor 21.

In step S15, the temperature Tw of the hot water is detected based on the electric signal from the water temperature sensor 16.

In step S16, the controller 10 determines in which operation mode the compressor 21 is operated based on the current operation mode of the compressor 21 and the temperature Tw of the hot water.

Specifically, the controller 10 determines in which operation mode the compressor 21 is operated based on the transition diagram of FIG. In FIG. 7, the horizontal axis is the temperature Tw of hot water, and the vertical axis is the operation mode of the compressor 21.

On the horizontal axis of FIG. 7, the first target hot water temperature Two1, the second target hot water temperature Two2, and the third target hot water temperature Two3 are set. In these, the hot water temperature difference ΔTw as the heat medium temperature difference obtained by subtracting the target hot water temperature Two corresponding to the target blowout temperature To from the hot water temperature Tw detected by the water temperature sensor 16 is the first set temperature Tw1 and the second setting, respectively. It is a temperature in the case of the temperature Tw2 and the third set temperature Tw3. Here, the first set temperature Tw1 is set to 4 [° C.], the second set temperature Tw2 is set to 2 [° C.], and the third set temperature Tw3 is set to 0 [° C.]. That is, the third target hot water temperature Two3 coincides with the target hot water temperature Two.

As shown in FIG. 7, when the heating operation is started by the air conditioner 100 and the air in the vehicle interior is not sufficiently warmed, the controller 10 sets the discharge pressure to the target refrigerant pressure Pc in the first operation mode. The rotation speed D of the compressor 21 is PI-controlled so that the discharge pressure Pd of the refrigerant detected by the sensor 11 approaches.

When the discharge pressure Pd exceeds the target refrigerant pressure Pc in the first operation mode, the rotation speed D of the compressor 21 is calculated to be a value lower than the minimum rotation speed Dmin. However, in the air conditioner 100, even if the hot water temperature Tw exceeds the target hot water temperature Two, if the hot water temperature difference ΔTw is lower than the first set temperature Tw1, the rotation of the compressor 21 is not stopped and the minimum rotation speed is reached. Continue operation at Dmin.

As described above, in the air conditioner 100, even if the discharge pressure Pd of the refrigerant compressed by the compressor 21 is higher than the target refrigerant pressure Pc, if the pressure difference from the target refrigerant pressure Pc is smaller than the set pressure, the compressor The 21 is operated at the minimum rotation speed Dmin without stopping. Therefore, the compressor 21 cannot be switched off only while the compressor 21 is operated at the minimum rotation speed Dmin. Further, the refrigerant pressure when the compressor 21 is stopped is higher than the target refrigerant pressure Pc by a set pressure. Therefore, it is suppressed that the compressor 21 is immediately switched on after being switched off. Therefore, the frequency of repeating on / off of the compressor 21 in the air conditioner 100 can be reduced.

Similarly, in the modified example shown in FIG. 3, in the controller 10, even if the discharge pressure Pd detected by the discharge pressure sensor 11 becomes higher than the target refrigerant pressure Pc, the refrigerant pressure difference ΔP from the target refrigerant pressure Pc is the set pressure. If it is smaller, the compressor 21 is operated at the minimum rotation speed Dmin. At this time, the set pressure is the pressure of the refrigerant when the temperature Tw of the hot water is the first target hot water temperature Two1. The same effect is obtained in this case as well.

In the first operation mode, the controller 10 has a first operation when the temperature Tw of the hot water rises and becomes higher than the first target hot water temperature Two1, that is, when the hot water temperature difference ΔTw becomes higher than the first set temperature Tw1. 3 The operation mode is switched to stop the rotation of the compressor 21.

In the third operation mode, the controller 10 has a second operation mode when the temperature Tw of the hot water becomes lower than the second target hot water temperature Tw2, that is, when the hot water temperature difference ΔTw becomes lower than the second set temperature Tw2. The compressor 21 is operated at the minimum rotation speed Dmin.

In the second operation mode, the controller 10 has a first operation mode when the temperature Tw of the hot water becomes lower than the third target hot water temperature Tw3, that is, when the hot water temperature difference ΔTw becomes lower than the third set temperature Tw3. The speed D of the compressor 21 is PI-controlled again by switching to.

Here, when the compressor 21 shifts from the stopped state to the normal PI control, the discharge pressure Pd is lower than the relationship with the temperature of the indoor heat exchanger, so that the difference from the target refrigerant pressure Pc is different. It is becoming larger, and it is necessary to increase the rotation speed D of the compressor 21. Then, when the discharge pressure Pd overshoots, it is necessary to suddenly reduce the rotation speed D of the compressor 21. Therefore, the rotation speed D of the compressor 21 may be hunted.

On the other hand, in the air conditioner 100, the state in which the compressor 21 is operated at the minimum rotation speed Dmin shifts to the normal PI control. Therefore, since the discharge pressure Pd is in the operating state, the rotation speed D of the compressor 21 is changed. There is no need to raise it suddenly. Therefore, it is possible to suppress hunting of the rotation speed D of the compressor 21.

Further, in the air conditioner 100, the refrigerant compressed by the compressor 21 heats the hot water by the water cooling condenser 22, and the heated hot water is circulated to the heater core 42 to heat the air. The responsiveness of the change in the temperature Tw of the hot water is poor as compared with the change in the discharge pressure Pd of the refrigerant. Therefore, if the compressor 21 is stopped and the compressor 21 is operated after waiting until the temperature Tw of the hot water becomes lower than the third target hot water temperature Two3, the temperature Tw of the hot water should be raised immediately. I can't.

On the other hand, in the air conditioner 100, since the state in which the compressor 21 is operated at the minimum rotation speed Dmin shifts to the normal PI control, the temperature Tw of the hot water can be raised quickly.

In the second operation mode, the controller 10 has a third operation mode when the temperature Tw of the hot water becomes higher than the first target hot water temperature Tw1, that is, when the hot water temperature difference ΔTw becomes higher than the first set temperature Tw1. To stop the rotation of the compressor 21.

If it is determined in step S16 that the compressor 21 is operated in the first operation mode, the process proceeds to step S17. If it is determined in step S16 that the compressor 21 is operated in the second operation mode, the process proceeds to step S20. If it is determined in step S16 that the compressor 21 is operated in the third operation mode, the process proceeds to step S22.

In step S17, the compressor 21 is turned on. If the compressor 21 is already on, the operation is continued as it is.

In step S18, it is determined whether or not the rotation speed D of the compressor 21 calculated in step S13 is larger than the minimum rotation speed Dmin. If it is determined in step S18 that the rotation speed D of the compressor 21 calculated in step S13 is larger than the minimum rotation speed Dmin, the process proceeds to step S19 and the compressor 21 is operated at the rotation speed D. .. On the other hand, if it is determined in step S18 that the rotation speed D of the compressor 21 calculated in step S13 is not greater than the minimum rotation speed Dmin, that is, is not less than the minimum rotation speed Dmin, the process proceeds to step S21. Then, the compressor 21 is rotated at the minimum rotation speed Dmin.

In step S20, the compressor 21 is turned on. If the compressor 21 is already on, the operation is continued as it is.

In step S21, the rotation speed D is fixed to the minimum rotation speed Dmin and the compressor 21 is rotated. As a result, the compressor 21 can be rotated at the minimum rotation speed Dmin when the third operation mode is switched to the second operation mode.

In step S22, the rotation of the compressor 21 is stopped. As a result, the rotation of the compressor 21 can be stopped when the first operation mode is switched to the third operation mode and when the second operation mode is switched to the third operation mode again.

According to the above embodiment, the following effects are obtained.

The air conditioner 100 includes a compressor 21 for compressing the refrigerant, a water cooling condenser 22 for heating the air guided to the passenger compartment of the vehicle using the heat of the compressor compressed by the compressor 21, a hot water cycle 4, and the compressor 21. The discharge pressure sensor 11 that detects the pressure of the compressed refrigerant and the discharge pressure Pd detected by the discharge pressure sensor 11 come close to the target refrigerant pressure Pc corresponding to the target blowout temperature To of air into the vehicle interior. The controller 10 includes a controller 10 that controls the rotation speed D, and even if the discharge pressure Pd detected by the discharge pressure sensor 11 is higher than the target refrigerant pressure Pc, the pressure difference from the target refrigerant pressure Pc is larger than the set pressure. When it is small, the compressor 21 is operated at the minimum rotation speed Dmin.

Further, the air conditioner 100 includes a water cooling condenser 22 that heats the hot water flowing through the heater core 42 by the heat of the refrigerant compressed by the compressor 21, and a water temperature sensor 16 that detects the temperature of the hot water guided to the heater core 42. Further, the controller 10 has a first setting in which the hot water temperature difference ΔTw obtained by subtracting the target hot water temperature Two corresponding to the target blowout temperature To from the temperature Tw detected by the water temperature sensor 16 is the temperature difference of the hot water when the set pressure is set. When the temperature is lower than Tw1, the compressor 21 is operated at the minimum rotation speed Dmin.

In these configurations, even if the discharge pressure Pd of the refrigerant compressed by the compressor 21 is higher than the target refrigerant pressure Pc, if the pressure difference from the target refrigerant pressure Pc is smaller than the set pressure, the compressor 21 is stopped. It is operated at the minimum rotation speed Dmin without. Therefore, the compressor 21 cannot be switched off only while the compressor 21 is operated at the minimum rotation speed Dmin. Further, the refrigerant pressure when the compressor 21 is stopped is higher than the target refrigerant pressure Pc by a set pressure. Therefore, it is suppressed that the compressor 21 is immediately switched on after being switched off. Therefore, the frequency of repeating on / off of the compressor 21 in the air conditioner 100 can be reduced.

Further, the controller 10 stops the rotation of the compressor 21 when the hot water temperature difference ΔTw becomes higher than the first set temperature Tw1.

According to this configuration, it is possible to reduce the frequency of repeating on / off of the compressor 21 in the air conditioner 100 and prevent the compressor 21 from being operated more than necessary.

Further, when the rotation of the compressor 21 is stopped and the hot water temperature difference ΔTw becomes lower than the second set temperature Tw2 set lower than the first set temperature Tw1, the controller 10 sets the compressor 21 to the minimum rotation speed. Operate at Dmin.

Further, the controller 10 targets when the hot water temperature difference ΔTw becomes lower than the third set temperature Tw3, which is set lower than the second set temperature Tw2, while the compressor 21 is operated at the minimum rotation speed Dmin. The rotation speed D of the compressor 21 is increased so that the discharge pressure Pd detected by the discharge pressure sensor 11 approaches the refrigerant pressure Pc.

According to these configurations, since the state in which the compressor 21 is operated at the minimum rotation speed Dmin shifts to the normal PI control, it is not necessary to suddenly increase the rotation speed D of the compressor 21. Therefore, it is possible to suppress hunting of the rotation speed D of the compressor 21. Further, in the air conditioner 100, since the state in which the compressor 21 is operated at the minimum rotation speed Dmin shifts to the normal PI control, the temperature Tw of the hot water can be raised quickly.

Although the embodiments of the present invention have been described above, the above embodiments are only a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configurations of the above embodiments. Absent.

100 Air conditioner 2 Refrigeration cycle 4 Hot water cycle 10 Controller (control unit)
11 Discharge pressure sensor (refrigerant pressure detector)
16 Water temperature sensor (heat medium temperature detector)
21 Compressor
22 Water-cooled condenser (refrigerant-heat medium heat exchanger)
23 Outdoor heat exchanger 24 Receiver 25 Evaporator (evaporator)
26 Temperature type expansion valve (expansion valve)
27 Fixed throttle 42 Heater core 127 Electromagnetic throttle valve (electric throttle mechanism)

Claims (5)

An air conditioner installed in a vehicle
A compressor that compresses the refrigerant and
An indoor heat exchanger that heats the air guided to the passenger compartment of the vehicle by using the heat of the refrigerant compressed by the compressor.
A refrigerant pressure detector that detects the pressure of the refrigerant compressed by the compressor, and
A control unit that controls the rotation speed of the compressor so that the pressure detected by the refrigerant pressure detector approaches the target refrigerant pressure corresponding to the target blowing temperature of air into the vehicle interior is provided.
The control unit operates the compressor at the minimum rotation speed when the pressure detected by the refrigerant pressure detector is higher than the target refrigerant pressure but the pressure difference from the target refrigerant pressure is smaller than the set pressure. Let,
An air conditioner characterized by that. The air conditioner according to claim 1.
A refrigerant-heat medium heat exchanger that heats the heat medium flowing through the indoor heat exchanger with the heat of the refrigerant compressed by the compressor.
Further provided with a heat medium temperature detector for detecting the temperature of the heat medium guided to the indoor heat exchanger.
In the control unit, the heat medium temperature difference obtained by subtracting the target heat medium temperature corresponding to the target blowing temperature from the temperature detected by the heat medium temperature detector is the temperature difference of the heat medium in the case of the set pressure. 1 When the temperature is lower than the set temperature, the compressor is operated at the minimum rotation speed.
An air conditioner characterized by that. The air conditioner according to claim 2.
The control unit stops the rotation of the compressor when the temperature difference of the heat medium becomes higher than the first set temperature.
An air conditioner characterized by that. The air conditioner according to claim 3.
The control unit rotates the compressor at a minimum when the heat medium temperature difference becomes lower than the second set temperature set lower than the first set temperature while the rotation of the compressor is stopped. Drive at speed,
An air conditioner characterized by that. The air conditioner according to claim 4.
The control unit operates the compressor at the minimum rotation speed, and when the heat medium temperature difference becomes lower than the third set temperature set lower than the second set temperature, the target The rotation speed of the compressor is increased so that the pressure detected by the refrigerant pressure detector approaches the refrigerant pressure.
An air conditioner characterized by that.

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