JP6553931B2 - Vehicle air conditioner - Google Patents

Description

  The present invention relates to a vehicle air conditioner.

  Patent Document 1 discloses an air conditioner for an electric vehicle that performs a defrosting operation to remove frost generated in an outdoor heat exchanger. In the air conditioner for an electric vehicle of Patent Document 1, the defrosting is performed when the outside air temperature above the set temperature is detected for the set time or more during the defrosting operation, or when the defrosting operation time reaches the time limit. End the operation.

JP 2000-94942 A

  However, the time required for the defrosting operation varies depending on the degree of frost generated in the outdoor heat exchanger. For this reason, there is a concern that the defrosting operation is performed more than necessary until the set time, even though the outside air temperature is high and the defrosting is completed early. In addition, although the defrosting operation is executed until the time limit is reached, there is a concern that the defrosting is insufficient and frost formation remains in the outdoor heat exchanger.

  The present invention was invented to solve such a problem, and by performing the defrosting operation according to the degree of frost formation, the defrosting operation is not performed more than necessary, and removal is performed. An object of the present invention is to provide a vehicle air conditioner in which frost is insufficient and frost formation does not remain in the outdoor heat exchanger.

  In the defrosting operation, after the frost formation on the outdoor heat exchanger is removed, the outlet side refrigerant temperature of the outdoor heat exchanger, the discharge temperature of the compressor, the discharge pressure, and the suction pressure rise. I found out.

In a vehicle air conditioner according to an aspect of the present invention, frost is generated in a compressor that compresses refrigerant, an outdoor heat exchanger that performs heat exchange between outside air and the refrigerant, and an outdoor heat exchanger. In this case, the defrosting operation execution unit guides the refrigerant compressed by the compressor to the outdoor heat exchanger and executes the defrosting operation, and estimates the degree of frost formation as the degree of frosting generated in the outdoor heat exchanger A frost degree estimation unit and a temperature difference calculation unit that calculates a temperature difference between the outlet side refrigerant temperature of the outdoor heat exchanger and the temperature of the outside air are provided. The defrosting operation execution unit starts the defrosting operation when the vehicle stops, and after a predetermined defrost termination determination start time has elapsed, the outlet side refrigerant temperature of the outdoor heat exchanger, the discharge temperature of the compressor, the discharge pressure The defrosting operation is ended when at least one of the suction pressure rises or when the pressure reaches a predetermined value. The defrosting operation execution unit sets the defrost termination determination start time based on the degree of frost formation estimated by the degree of frost formation unit. The frost formation degree estimation unit measures the elapsed time when the temperature difference calculated by the temperature difference calculation unit is equal to or greater than the frost formation temperature difference at which frost formation occurs in the outdoor heat exchanger. When the heating operation is continued, a predicted frost formation time for which frost formation is predicted to occur in the entire outdoor heat exchanger is set, and the frost formation level is estimated based on the ratio of the elapsed time to the predicted frost formation time. .

  In the present invention, the temperature at the outlet side of the outdoor heat exchanger after the predetermined defrost termination determination start time has elapsed since the start of the defrosting operation without setting the timing to stop the defrosting operation after a predetermined time has elapsed. Since at least one of the discharge temperature, discharge pressure and suction pressure of the compressor rises or reaches a predetermined value, the defrosting operation operation time according to the degree of frost formation Thus, it is possible to provide a vehicle air conditioner that does not perform defrosting operation more than necessary, and that defrosting is insufficient and frost does not remain on the outdoor heat exchanger.

It is a block diagram of the vehicle air conditioner which concerns on embodiment of this invention. It is a block diagram of the electric circuit regarding the air-conditioning control of the controller which concerns on embodiment of this invention. It is a figure which shows the flow of the refrigerant | coolant at the time of heating operation. It is a flow chart of accumulation frost degree degree calculation control at the time of heating operation which a controller concerning an embodiment of the present invention performs. It is a flowchart of the defrost operation control which the controller which concerns on embodiment of this invention performs. It is a frost formation prediction time characteristic table which the controller which concerns on embodiment of this invention refers. It is a figure showing the flow of the refrigerant at the time of defrosting operation. It is a graph which shows the time change of the exit side refrigerant temperature of the outdoor heat exchanger at the time of defrosting operation, and the discharge temperature of a compressor. It is a graph which shows the time change of the discharge pressure and suction pressure of a compressor at the time of defrosting operation.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of a vehicular air-conditioning system 100 according to an embodiment of the present invention.

  The vehicular air-conditioning system 100 includes a refrigeration cycle 1, a cooling water circulation cycle 3, a heating ventilation and air conditioning (HVAC) unit 7, and an engine cooling water circulation cycle 8.

  The refrigeration cycle 1 releases the heat of the refrigerant flow path 60 through which the refrigerant flows, the accumulator 10 provided on the refrigerant flow path 60 for gas-liquid separation of the refrigerant, the compressor 20 for compressing the refrigerant, and the high pressure refrigerant. A water refrigerant heat exchanger 30, an outdoor heat exchanger 40 for exchanging heat between the refrigerant and the outside air, and an evaporator 50 for allowing the refrigerant to absorb the heat of ambient air. For example, HFC-134a is used as the refrigerant.

  The accumulator 10 separates the refrigerant flowing through the refrigerant flow passage 60 into a gas phase refrigerant and a liquid phase refrigerant. From the accumulator 10, only the separated gas phase refrigerant flows to the compressor 20.

  The compressor 20 sucks in and compresses the refrigerant that has passed through the accumulator 10. The compressor 20 is a variable output compressor whose output changes according to the power consumption of the internal motor. The gas phase refrigerant is compressed by the compressor 20 to have a high temperature.

  The water-refrigerant heat exchanger 30 is a condenser that condenses the refrigerant that has passed through the compressor 20 using cooling water flowing inside. The water-refrigerant heat exchanger 30 performs heat exchange between the refrigerant and the cooling water, and secures a heat source for heating the air used for vehicle interior air conditioning.

  The outdoor heat exchanger 40 is a heat exchanger that performs heat exchange between the refrigerant and the outside air. Outside air is introduced into the outdoor heat exchanger 40 as the vehicle runs or the outdoor fan 41 rotates. The rotation speed of the outdoor fan 41 changes according to the frequency setting of the internal motor.

  The evaporator 50 is an evaporator that evaporates the refrigerant after passing through the outdoor heat exchanger 40. The evaporator 50 cools the air by causing the refrigerant to absorb the heat of the air used for the air conditioning in the passenger compartment. The refrigerant evaporated by the evaporator 50 flows to the accumulator 10.

  A first expansion valve 61 is disposed in the refrigerant flow path 60 between the water refrigerant heat exchanger 30 and the outdoor heat exchanger 40.

  The first expansion valve 61 decompresses and expands the refrigerant flowing from the water refrigerant heat exchanger 30 during the heating operation. For the first expansion valve 61, for example, a fixed throttle such as an orifice or a capillary tube is used. The refrigerant compressed at high temperature and high pressure by the compressor 20 upstream of the water refrigerant heat exchanger 30 passes through the small hole of the first expansion valve 61 and expands under reduced pressure to become misty low temperature refrigerant. As the first expansion valve 61, an opening adjustment valve capable of adjusting the opening of the valve may be used.

  The refrigerant flow passage 60 has a first bypass flow passage 60 a that connects the compressor 20 and the outdoor heat exchanger 40 by bypassing the water refrigerant heat exchanger 30 and the first expansion valve 61. A first on-off valve 62 which switches the flow of the refrigerant by opening and closing is installed in the first bypass flow passage 60a.

  The first on-off valve 62 is closed during heating operation and is opened during defrosting operation or cooling operation. At the time of heating operation, the first on-off valve 62 is closed, so the refrigerant compressed by the compressor 20 flows to the water refrigerant heat exchanger 30, and exchanges heat with the cooling water in the water refrigerant heat exchanger 30. Thereafter, the refrigerant passes through the first expansion valve 61, expands under reduced pressure, and flows to the outdoor heat exchanger 40. On the other hand, during the defrosting operation or the cooling operation, the first on-off valve 62 is opened, and the refrigerant compressed by the compressor 20 passes through the first on-off valve 62 and does not decompress and expand. It flows to the heat exchanger 40.

  A second opening / closing valve 63 and a second expansion valve 64 are arranged in series in the refrigerant flow path 60 between the outdoor heat exchanger 40 and the evaporator 50. In addition, the refrigerant flow passage 60 includes a second bypass flow passage 60 b that bypasses the second expansion valve 64 and the evaporator 50 and connects the outdoor heat exchanger 40 and the accumulator 10. A third on-off valve 65 that switches the flow by opening and closing is installed in the second bypass passage 60b.

  The second on-off valve 63 is a valve that switches the flow of the refrigerant to the evaporator 50. The 3rd on-off valve 65 is a valve which switches the flow of the refrigerant to the 2nd bypass channel 60b. During heating operation or defrosting operation, the second on-off valve 63 is closed and the third on-off valve 65 is opened. Therefore, the refrigerant flowing from the outdoor heat exchanger 40 passes through the second bypass flow path 60b and flows to the accumulator 10 as it is. On the other hand, during the cooling operation, the second on-off valve 63 is opened and the third on-off valve 65 is closed. Therefore, the refrigerant flowing from the outdoor heat exchanger 40 flows to the second expansion valve 64 and the evaporator 50.

  The second expansion valve 64 decompresses and expands the refrigerant flowing from the second on-off valve 63 during the cooling operation, and flows it to the evaporator 50. Like the first expansion valve 61, the second expansion valve 64 uses, for example, a fixed throttle such as an orifice or a capillary tube. The high-pressure refrigerant radiated by the outdoor heat exchanger 40 expands under reduced pressure by passing through a small hole in the second expansion valve 64 and becomes a low-temperature mist. Note that an opening adjusting valve capable of adjusting the opening of the valve may be used as the second expansion valve 64.

  The cooling water circulation cycle 3 includes a cooling water flow path 34 through which the cooling water flows. For example, antifreeze is used as the cooling water. A water refrigerant heat exchanger 30, a water pump 31, a heater core 32, and a hot water heater 33 are connected to the cooling water flow path 34.

  The water pump 31 feeds and circulates the cooling water in the cooling water flow path 34. The water pump 31 changes the number of rotations according to the frequency setting of the internal motor, and adjusts the amount of liquid coolant to be sent.

  The hot water heater 33 heats the passing cooling water. The cooling water is heated by the hot water heater 33 when the cooling water cannot sufficiently absorb heat from the refrigerant in the water / refrigerant heat exchanger 30.

  The heater core 32 uses the heat of the heated cooling water to warm the air blown into the passenger compartment.

  Air to be blown into the vehicle compartment is introduced into the HVAC unit 7. An evaporator 50 and a heater core 32 are disposed in the HVAC unit 7. When the air blown into the vehicle compartment is blown by a blower (not shown) and passes through the evaporator 50 and the heater core 32, heat exchange is performed between the refrigerant flowing in the evaporator 50 and the cooling water flowing in the heater core 32. The HVAC unit 7 includes an air mix door 70 on the upstream side of the heater core 32.

  The air mix door 70 adjusts the amount of air passing through the heater core 32 by controlling the opening degree. For example, during the heating operation, the air mix door 70 is opened so that the air is introduced to the heater core 32. By opening the air mix door 70, the air blown from the blower is guided to the heater core 32 and exchanges heat with the cooling water in the heater core 32.

  The engine coolant circulation cycle 8 includes an engine coolant passage 83 through which the engine coolant flows. An engine 80, an engine water pump 81, and a radiator 82 are connected to the engine coolant passage 83.

  The engine 80 burns the fuel to obtain the driving force of the vehicle. The engine 80 generates heat by burning fuel internally.

  The engine water pump 81 is a pump that circulates the engine coolant in the engine coolant channel 83. The circulating engine cooling water is heated when the engine 80 is cooled.

  The radiator 82 is disposed on the vehicle rear side of the outdoor heat exchanger 40, and dissipates the heat of the engine cooling water to the outside air.

  The vehicle air conditioner 100 includes an outdoor heat exchanger outlet temperature sensor 91, an outside air temperature sensor 92, a discharge temperature sensor 93, a discharge pressure sensor 94, a suction pressure sensor 95, and a hot water heater outlet temperature sensor 96; A blowing temperature sensor 97, an evaporator temperature sensor 98, and a solar radiation sensor 99 are installed.

  The outdoor heat exchanger outlet temperature sensor 91 is installed in the refrigerant flow passage 60 near the outlet of the outdoor heat exchanger 40, and detects the temperature of the refrigerant having passed through the outdoor heat exchanger 40 (outlet side refrigerant temperature To). The outdoor heat exchanger outlet temperature sensor 91 may be installed at the outlet of the outdoor heat exchanger 40.

  The outside air temperature sensor 92 detects the temperature of the outside air (outside air temperature Ta) before being taken into the outdoor heat exchanger 40.

  The discharge temperature sensor 93 and the discharge pressure sensor 94 are installed in the refrigerant flow path 60 on the discharge side of the compressor 20. The discharge temperature sensor 93 detects the temperature of the refrigerant compressed by the compressor 20 (discharge temperature Td). The discharge pressure sensor 94 detects the pressure of the refrigerant compressed by the compressor 20 (discharge pressure Pd).

  The suction pressure sensor 95 is installed in the refrigerant flow passage 60 on the suction side of the compressor 20. The suction pressure sensor 95 detects the pressure of the refrigerant sucked into the compressor (suction pressure Ps).

  The hot water heater outlet temperature sensor 96 is installed at the outlet of the hot water heater 33 and detects the temperature of the cooling water that has passed through the hot water heater 33.

  The blowout temperature sensor 97 is installed near the outlet of the HVAC unit 7 and detects the blowout temperature of the air blown into the vehicle interior.

  The evaporator temperature sensor 98 is installed on the downstream side of the air flow of the evaporator 50 of the HVAC unit 7 and detects the temperature of the air that has passed through the evaporator 50.

  The solar radiation sensor 99 is installed in the vehicle cabin and detects the solar radiation state in the vehicle cabin.

  FIG. 2 is a block diagram of an electric circuit related to the air conditioning control of the controller 90 of the vehicle air conditioner 100.

  The controller 90 is configured by a CPU, a ROM, a RAM, and the like, and causes the vehicle air conditioner 100 to perform various functions by reading a program stored in the ROM by the CPU.

  As shown in FIG. 2, signals from various sensors 92 to 99 are input to the controller 90. The controller 90 sets the outputs of the compressor 20, the water pump 31, the engine water pump 81, the hot water heater 33, and the outdoor fan 41 based on the input signal. Further, the controller 90 performs opening / closing control of the first opening / closing valve 62, the second opening / closing valve 63, and the third opening / closing valve 65 based on the input signal. Further, the controller 90 performs opening control of the air mix door 70.

  Here, air conditioning control executed by the vehicle air conditioner 100 will be described. In the vehicle air conditioner 100, the controller 90 determines the cooling request, the heating request, or the dehumidifying heating request of the vehicle interior based on the signal from the air conditioning operation switch of the vehicle interior (not shown), and executes the air conditioning control.

  For example, when the heating operation is performed according to the heating request of the vehicle interior, the controller 90 closes the first on-off valve 62 and the second on-off valve 63 and opens the third on-off valve 65 as shown in FIG. . FIG. 3 is a diagram illustrating the flow of the refrigerant during the heating operation. As shown by the thick solid line in FIG. 3, the refrigerant compressed by the compressor 20 during the heating operation is the water refrigerant heat exchanger 30, the first expansion valve 61, the outdoor heat exchanger 40, the third on-off valve 65, and the accumulator 10. In order and return to the compressor 20.

  During the heating operation, the refrigerant is compressed by the compressor 20 and then cooled by exchanging heat with the cooling water of the water / refrigerant heat exchanger 30. The cooling water of the water-refrigerant heat exchanger 30 secures a heating heat source by exchanging heat with the refrigerant. Thereafter, the refrigerant that has passed through the water-refrigerant heat exchanger 30 is decompressed and expanded by the first expansion valve 61, becomes a low-temperature refrigerant, and flows to the outdoor heat exchanger 40. The low temperature refrigerant absorbs heat from the outside air introduced into the outdoor heat exchanger 40 and evaporates. When heat exchange is normally performed between the outside air introduced to the outdoor heat exchanger 40 and the low temperature refrigerant, the outlet side refrigerant temperature To of the outdoor heat exchanger 40 becomes close to the outside air temperature Ta.

  At this time, the water vapor in the outside air around the outdoor heat exchanger 40 is condensed to a temperature equal to or lower than the dew point temperature by the low-temperature refrigerant, so that dew condenses and adheres to the outdoor heat exchanger 40. If the condensed water is cooled to below the freezing point by the low-temperature refrigerant, it may freeze and frost formation may occur in the outdoor heat exchanger 40. When frost formation occurs in the outdoor heat exchanger 40, heat exchange performed between the refrigerant flowing inside the outdoor heat exchanger 40 and the outside air is hindered by frost formation, so the heating efficiency of the vehicle air conditioner 100 decreases. There is a risk.

  Therefore, when frost formation occurs on the outdoor heat exchanger 40, the controller 90 of the vehicle air conditioner 100 executes the following defrosting operation control so as to remove frost formation on the outdoor heat exchanger 40. FIG. 4 is a flowchart of cumulative frost degree calculation control during heating operation executed by the controller 90. FIG. 5 is a flowchart of the defrosting operation control performed by the controller 90 when the vehicle is stopped. The controller 90 executes the cumulative degree of frost formation calculation control according to the flowchart of FIG. 4 during the heating operation, and executes the defrosting operation control according to the flowchart of FIG. 5 when the vehicle is stopped.

  First, the cumulative frost level calculation control executed by the controller 90 in order to calculate the cumulative frost level S and record it in the RAM will be described with reference to FIG.

  In step S101, the controller 90 calculates a temperature difference ΔT between the outside air temperature Ta and the outlet side refrigerant temperature To of the outdoor heat exchanger 40. The outside air temperature Ta is detected based on a signal from the outside air temperature sensor 92, and the outlet-side refrigerant temperature To of the outdoor heat exchanger 40 is detected based on a signal from the outdoor heat exchanger outlet temperature sensor 91. When frost formation has not occurred in the outdoor heat exchanger 40, heat exchange is normally performed between the refrigerant and the outside air, so that the temperature difference ΔT becomes small. On the other hand, when frost formation occurs in the outdoor heat exchanger 40, heat exchange can not be performed normally between the refrigerant and the outside air, and the refrigerant passes through the outlet of the outdoor heat exchanger 40 at low temperature. Therefore, the temperature difference ΔT becomes larger than the frosting temperature difference at which frost formation can occur in the outdoor heat exchanger 40. Thus, the controller 90 functions as a temperature difference calculation unit of the vehicle air conditioner 100. In addition, when the outlet side refrigerant temperature To of the outdoor heat exchanger 40 is higher than 0 ° C., condensed water generated on the surface of the outdoor heat exchanger 40 even if the temperature difference ΔT becomes larger than the frosting temperature difference. Does not freeze, so frost does not occur.

  In step S102, the controller 90 sets the frost formation prediction time tf based on the temperature difference ΔT and the passing wind speed Va. The passing wind speed Va is the speed of the outside air passing through the outdoor heat exchanger 40, and is calculated based on the rotational speed of the outdoor fan 41 and the vehicle speed. The frost formation predicted time tf is a time when the frost formation of the outdoor heat exchanger 40 affects the heat exchangeability, and specifically, when the heating operation is continued under a certain setting condition, It is the time when frost formation is expected to occur on the whole. By continuing the heating operation until the frost formation prediction time tf without changing the setting conditions, the cumulative degree of frost formation S becomes 1, and frost formation occurs in the entire outdoor heat exchanger 40, and the refrigerant and the outside air Heat exchange between the two.

  The predicted frost formation time tf is set with reference to, for example, a predicted frost formation time characteristic table shown in FIG. FIG. 6 shows the relationship between the passing wind speed Va that changes according to the temperature difference ΔT and the frost formation prediction time tf. In FIG. 6, the horizontal axis represents the passing wind speed Va, and the vertical axis represents the predicted frost formation time tf. As shown in FIG. 6, the predicted frost formation time tf becomes shorter as the passing wind speed Va increases, because the outside air containing water vapor is introduced around the outdoor heat exchanger 40 one after another. Further, the predicted frost formation time tf becomes shorter as the temperature difference ΔT becomes larger because the outside air is cooled near the outlet of the outdoor heat exchanger 40.

  Here, it is assumed that the temperature difference ΔT becomes the first temperature difference ΔT1 and the passing wind velocity Va becomes the first passing wind velocity V1 by performing the heating operation under a certain setting condition. At this time, the controller 90 specifies a point A based on the first temperature difference ΔT1 and the first passing wind velocity V1 with reference to the frost formation predicted time characteristic table shown in FIG. 6, and the frost formation prediction time tf is the first It is set that the predicted frost formation time tf1.

  Further, when the setting condition of the heating operation changes, the temperature difference ΔT becomes the second temperature difference ΔT2 larger than the first temperature difference ΔT1, and the passing wind velocity Va becomes the second passing wind velocity V2 faster than the first passing wind velocity V1. Do. At this time, the controller 90 specifies the point B based on the second temperature difference ΔT2 and the second passing wind velocity V2 with reference to the frost formation predicted time characteristic table shown in FIG. 6, and the frost formation prediction time tf is the first It is set that it is the second frost formation estimated time tf2 shorter than the frost formation estimated time tf1.

  As described above, after estimating the frost formation prediction time, the controller 90 returns to the flowchart of the cumulative frost formation degree calculation control of FIG. 4 and executes the process of step S103.

  In step S103, the controller 90 estimates the degree of frost formation F as the degree of frost formation generated in the outdoor heat exchanger 40. First, in order to estimate the frost formation degree F, the controller 90 calls the elapsed time tn recorded in the RAM. The elapsed time tn is a continuous time of the heating operation when the heating operation is executed under a setting condition in which the temperature difference ΔT between the outside air and the low-temperature refrigerant is equal to or greater than the frosting temperature difference. The elapsed time tn is counted up from 0 when the heating operation is started under the setting condition, and is recorded in the RAM. The elapsed time tn is counted up again from 0 when the heating operation is changed to a setting condition different from the setting condition.

  Next, the controller 90 estimates the frost formation degree F based on the ratio of the elapsed time tn to the predicted frost formation time tf. The frosting degree F is estimated by dividing the elapsed time tn by the frosting prediction time tf (F = tn / tf).

  For example, if the elapsed time tn is 1 minute and the first frost formation prediction time tf1 set in step S102 is 5 minutes, the controller 90 estimates that the frost formation degree F is 0.2. (F = 1/5 = 0.2). Further, when the heating operation condition is changed, the controller 90 updates the frost formation degree F. For example, when the elapsed time tn is 2 minutes and the second frost formation predicted time tf2 newly set in step S102 is 4 minutes, the controller 90 determines that the frost formation degree F is 0.5. Estimate (F = 2/4 = 0.5). Thus, the controller 90 functions as a frosting degree estimation unit of the vehicular air conditioner 100.

  In step S104, the controller 90 calculates the cumulative degree of frost formation S to determine the frost formation state of the outdoor heat exchanger 40. The cumulative frost level S is calculated by integrating the frost level F updated every time the controller 90 executes the cumulative frost level calculation control. The cumulative degree of frost formation S is calculated by adding the degree of frost formation F newly estimated in the present step S103 to the cumulative frost formation degree S up to the previous time recorded in the RAM (S = ΣF = S + F ).

  For example, when the cumulative degree of frost formation S up to the previous time is 0 and the degree of frost formation F newly estimated this time is 0.2, the controller 90 has a cumulative degree of frost formation S of 0.2. Calculate Further, when the heating operation condition is changed, the controller 90 newly calculates the accumulated frost degree S using the frosting degree F updated after the change of the heating operation condition. For example, when the cumulative degree of frost formation S up to the previous time is 0.2 and the degree of frost formation F newly estimated this time is 0.5, the controller 90 newly sets the cumulative frost degree S to 0. .7.

  In step S105, the controller 90 records the calculated cumulative degree of frost formation S in the RAM. Thereafter, the controller 90 ends the cumulative frost formation degree calculation control.

  Next, with reference to FIG. 5, the defrosting operation control at the time of the vehicle stop which the controller 90 performs using the cumulative frost formation degree S is demonstrated.

  In step S201, the controller 90 calls the cumulative degree of frost formation S recorded in the RAM. The cumulative frost formation degree S is a value representing the state of frost generated in the outdoor heat exchanger 40.

  In step S202, the controller 90 determines whether or not to start the defrosting operation by determining whether or not the cumulative frosting degree S called from the RAM is greater than zero. For example, when the cumulative frost level S is 0, the outdoor heat exchanger 40 is in a state where no frost is generated. On the other hand, when the cumulative frost level S is greater than 0, the outdoor heat exchanger 40 is in a state where frost is generated. In particular, when the cumulative degree of frost formation S increases to 1, the outdoor heat exchanger 40 is in a state where frost formation has occurred overall, and the refrigerant flowing through the outdoor heat exchanger 40 is between the outside air and the outside air. Heat exchange cannot be performed. The processing of the controller 90 ends the execution of the defrosting operation control when the cumulative degree of frost formation S is 0, and starts the defrosting operation when the cumulative frost formation degree S is greater than 0 (step S203). Go to

  In step S203, the controller 90 stops the outdoor fan 41. By stopping the outdoor fan 41 when the vehicle is stopped, the outside air around the outdoor heat exchanger 40 stays as it is, and new outside air is not introduced into the outdoor heat exchanger 40.

  In step S204, the controller 90 sets the defrost termination determination start time te. The defrost termination determination start time te is a time immediately before the end of the defrosting operation in which most of the frost formation of the outdoor heat exchanger 40 is removed by the defrosting operation being executed, and the controller 90 removes the defrosting operation. It is time to start the end of frost operation. The defrost termination determination start time te is set to be longer according to the magnitude of the cumulative degree of frost formation S.

  In step S205, the controller 90 starts the defrosting operation. Moreover, the controller 90 starts measurement of defrost operation time tm as continuation time of defrost operation simultaneously with start of defrost operation.

  When starting the defrosting operation, the controller 90 opens the first on-off valve 62 that was closed during the heating operation of FIG. 3 as shown in FIG. FIG. 7 is a diagram illustrating the flow of the refrigerant during the defrosting operation. As indicated by a thick solid line in FIG. 7, the refrigerant compressed by the compressor 20 during the defrosting operation passes through the first bypass flow passage 60 a when the first on-off valve 62 is opened.

  Here, with reference to FIG. 8 and FIG. 9, the temperature and pressure of the refrigerant whose value starts to change rapidly when the refrigerant passes through the first bypass flow passage 60a in the defrosting operation will be described.

  FIG. 8 is a graph showing temporal changes in the outlet-side refrigerant temperature To of the outdoor heat exchanger 40 and the discharge temperature Td of the compressor 20 during the defrosting operation. In FIG. 8, the horizontal axis represents the defrosting operation time tm, and the vertical axis represents the refrigerant temperature.

  Time t0 in FIG. 8 is a time when measurement of the defrosting operation time tm is started in the process of step S205 in FIG. At time t0, the controller 90 stops the outdoor fan 41 and switches the flow of the refrigerant by the processes in steps S203 and S205 in FIG. In the vicinity of time t0, the outlet side refrigerant temperature To and the discharge temperature Td are rapidly changed in value as shown in FIG. 8 because the flow path of the refrigerant is not stable since the flow path is switched with the start of the defrosting operation. It is changing. When the defrosting operation time tm is increased, the outlet side refrigerant temperature To and the discharge temperature Td are stably and gradually increased.

  FIG. 9 is a graph showing time changes of the discharge pressure Pd and the suction pressure Ps of the compressor 20 at the time of the defrosting operation. In FIG. 9, the horizontal axis represents the defrosting operation time tm, and the vertical axis represents the refrigerant pressure.

  Time t0 in FIG. 9 is a time when measurement of the defrosting operation time tm is started in the process of step S205 in FIG. The controller 90 stops the outdoor fan 41 and switches the refrigerant flow at time t0. In the vicinity of time t0, the discharge pressure Pd and the suction pressure Ps change rapidly as shown in FIG. 9 because the refrigerant flow is not stable. As the defrosting operation time tm increases, the discharge pressure Pd and the suction pressure Ps stably and gradually increase.

  In step S206 of FIG. 5, the controller 90 determines whether or not the defrosting operation time tm is equal to or longer than the defrosting end determination start time te. When the defrosting operation time tm is equal to or longer than the defrosting end determination start time te, the controller 90 advances the process to step S207 in order to determine the end of the defrosting operation. On the other hand, when the defrosting operation time tm is less than the defrosting end determination start time te, the controller 90 repeats the process of step S206 in order to continue the defrosting operation.

  In step S207, the controller 90 determines whether to end the defrosting operation. The controller 90 determines whether or not all frost formation generated in the outdoor heat exchanger 40 has been removed based on the temperature or pressure of the refrigerant after elapse of the defrost termination determination start time te. Specifically, the controller 90 determines whether at least one of the outlet-side refrigerant temperature To of the outdoor heat exchanger 40, the discharge temperature Td of the compressor 20, the discharge pressure Pd, and the suction pressure Ps is rising. Do. If any one of the above conditions is raised, the controller 90 advances the process to step S208 to end the defrosting operation. On the other hand, the controller 90 repeats the process of step S207 in order to continue the defrosting operation when none of the above conditions is raised.

  For example, at time te1 in FIGS. 8 and 9, the controller 90 determines that the defrosting operation time tm has become equal to or longer than time te1 in the process of step S206 in FIG. 5, and proceeds to the process of step S207. The end determination of is started. Time te1 is the time set as the defrosting end determination start time te based on the cumulative frost formation degree S in the process of step S204.

  The refrigerant compressed to a high temperature by the compressor 20 passes through the first bypass flow passage 60 a and flows to the outdoor heat exchanger 40 to melt the frost generated in the outdoor heat exchanger 40. As the defrosting operation is continued and the defrosting operation time tm approaches from time t0 to time te1, the frost formed in the outdoor heat exchanger 40 exchanges heat with the high temperature refrigerant compressed by the compressor 20. It is gradually melted down.

  When all the frost formation in the outdoor heat exchanger 40 is removed, the refrigerant compressed by the compressor 20 is not deprived of heat by the frost formation. Further, since the vehicle is stopped during the defrosting operation and the outdoor fan 41 is also stopped, the refrigerant compressed by the compressor 20 is not deprived of heat by the outside air newly introduced to the outdoor heat exchanger 40 . Therefore, after the defrosting operation is normally performed and all frost formation generated in the outdoor heat exchanger 40 is removed after the elapse of time te1, as shown in FIG. 8, the outlet side refrigerant temperature To and the discharge temperature Td Gradually rises. Further, after time te1 elapses, as shown in FIG. 9, the discharge pressure Pd and the suction pressure Ps lose the heat exchange object of the refrigerant, the enthalpy of the refrigerant increases, and the degree of superheat of the gas phase refrigerant before and after the compressor 20 As it gets higher, it will gradually rise.

  In the process of step S207 executed after the time te1 has elapsed, the controller 90 performs the outlet-side refrigerant temperature To of the outdoor heat exchanger, the discharge temperature Td of the compressor 20, the discharge temperature, and the suction pressure as shown in FIGS. It is determined that at least one of Ps is higher than the value at time te1. When the determination is established, the controller 90 advances the process to step S208 in order to end the defrosting operation.

  In the process of step S207 in FIG. 5, it is determined whether at least one of the outlet side refrigerant temperature To of the outdoor heat exchanger 40, the discharge temperature Td of the compressor 20, the discharge pressure Pd, and the suction pressure Ps has increased. It was judged. Instead of the determination, the controller 90 may determine whether at least one of the outlet-side refrigerant temperature To, the discharge temperature Td, the discharge pressure Pd, and the suction pressure Ps has risen to a predetermined value. The predetermined value in this case is a value determined in advance as the temperature or pressure of the refrigerant that reaches when the frost generated in the outdoor heat exchanger 40 is completely melted, for example.

  In step S208, the controller 90 ends the defrosting operation. The controller 90 returns the operating state of the outdoor fan 41 and the opening / closing state of the first opening / closing valve 62 to the state before the defrosting operation is started.

  Further, the controller 90 performs the defrosting operation, so that the frost generated in the entire outdoor heat exchanger 40 is removed. The controller 90 resets the cumulative frosting degree S to 0 by performing the defrosting operation and removing the frosting of the outdoor heat exchanger 40. The controller 90 also resets the defrosting operation time tm and the defrosting end determination start time te to 0 at the end of the defrosting operation. In addition, when the ignition is turned off after the vehicle stops, the controller 90 may leave the outdoor fan 41 stopped. Since the frost formation of the outdoor heat exchanger 40 is removed even when the outside air temperature Ta is a sufficiently high temperature, or when the cooling operation is continued for a predetermined time, the controller 90 causes the accumulated frost degree S to be It may be reset to zero.

  According to the vehicle air conditioner 100 according to the embodiment of the present invention described above, the following effects can be obtained.

  Vehicle air conditioner 100 includes a compressor 20 for compressing a refrigerant, an outdoor heat exchanger 40 for exchanging heat between the outside air and the refrigerant, and a compressor when frost is generated on the outdoor heat exchanger 40. And a controller 90 that functions as a defrosting operation executing unit that guides the refrigerant compressed by 20 to the outdoor heat exchanger 40 and executes the defrosting operation. The controller 90 as the defrosting operation execution unit starts the defrosting operation when the vehicle stops, and after the predetermined defrost termination determination start time te has elapsed, the outlet side refrigerant temperature To of the outdoor heat exchanger 40, the compressor The defrosting operation is terminated when at least one of the discharge temperature Td, the discharge pressure Pd, and the suction pressure Ps of 20 rises or reaches a predetermined value.

  According to the air conditioner 100 for a vehicle, the controller 90 as the defrosting operation execution unit sends the refrigerant compressed by the compressor 20 to the outdoor heat exchanger 40 when frost formation has occurred in the outdoor heat exchanger 40. Guide and perform defrosting operation. The controller 90 starts the defrosting operation when the vehicle stops, and after the predetermined defrost termination determination start time te has elapsed, the outlet side refrigerant temperature To of the outdoor heat exchanger 40, the discharge temperature Td of the compressor 20, the discharge Since the defrosting operation is ended when at least one of the pressure Pd and the suction pressure Ps rises or reaches a predetermined value, the defrosting operation is performed for a necessary time according to the degree of frost formation. be able to. Therefore, it is possible to provide the vehicle air conditioner 100 which does not perform the defrosting operation more than necessary, and the defrosting is insufficient and the outdoor heat exchanger 40 does not have the frost left.

  In the present embodiment, the outlet-side refrigerant temperature To of the outdoor heat exchanger 40, the discharge temperature Td of the compressor 20, and the discharge pressure after a predetermined defrost termination determination start time te has elapsed since the start of the defrosting operation. It was estimated that the frost formation on the outdoor heat exchanger 40 was completely removed when at least one of Pd and suction pressure Ps increased or reached a predetermined value, but it is limited to completely removed Alternatively, it may be estimated that frost formation has been removed at a surface area sufficient for the outdoor heat exchanger 40 to perform its function. That is, even if frost remains in a part of the outdoor heat exchanger 40, it may be estimated that most of the frost has been defrosted and the defrosting operation may be terminated.

  The vehicle air conditioner 100 further includes an outdoor fan 41 that introduces outside air into the outdoor heat exchanger 40. The outdoor fan 41 is stopped when the controller 90 is performing the defrosting operation.

  According to the vehicle air conditioner 100, when the defrosting operation is being performed, the vehicle is stopped and the outdoor fan 41 is stopped, so the refrigerant compressed by the compressor 20 is an outdoor heat exchanger It is possible to avoid losing heat from the newly introduced external air. Therefore, after a predetermined defrost termination determination start time te has elapsed since the start of the defrosting operation, the controller 90 determines whether all the frost formed on the outdoor heat exchanger 40 has been removed or not with the refrigerant. It can be determined while excluding the influence of heat exchange with the outside air. Further, since the refrigerant compressed by the compressor 20 exchanges heat only with frost formation of the outdoor heat exchanger 40 without exchanging heat with the outside air, the defrosting operation can be efficiently performed.

  In the vehicle air conditioner 100, the controller 90 further functions as a frost formation degree estimation unit that estimates the frost formation degree F as the degree of frost formation in the outdoor heat exchanger 40. The controller 90 sets the defrost termination determination start time te based on the estimated degree of frost formation F.

  According to the vehicle air conditioner 100, the degree of frost formation F is estimated as the degree of frost formation generated in the outdoor heat exchanger 40, and the defrost termination determination start time te is set based on the degree of frost formation F. The time for starting the defrosting operation end determination can be adjusted according to the degree of frost formation.

  In the vehicle air conditioner 100, the controller 90 further functions as a temperature difference calculating unit that calculates a temperature difference ΔT between the outlet side refrigerant temperature To of the outdoor heat exchanger 40 and the outside air temperature Ta of the outside air. The controller 90 measures the elapsed time tn in the state where the calculated temperature difference ΔT is equal to or more than the frosting temperature difference at which frosting occurs in the outdoor heat exchanger 40, and frosting of the outdoor heat exchanger 40 is thermal A predicted frost formation time tf that affects exchangeability is set, and the frost formation degree F is estimated based on the ratio of the elapsed time tn to the predicted frost formation time tf. In the vehicle air conditioner 100, the controller 90 sets the predicted frost formation time tf to be shorter as the calculated temperature difference ΔT is larger.

  According to the vehicle air conditioner 100, since the elapsed time tn is measured only when the temperature difference ΔT is equal to or greater than the frosting temperature difference at which frosting occurs in the outdoor heat exchanger 40, frosting is caused. It does not include the time when it does not occur. Then, the frost formation prediction time tf in which frost formation affects the heat exchange property is set, and the frost formation degree F is more accurately estimated based on the ratio of the elapsed time tn to the frost formation prediction time tf. Can accurately set the defrosting end determination start time te based on the frosting degree F with high reliability. Specifically, the frost formation prediction time tf is set to be short in consideration of the state in which frost formation is more likely to occur as the temperature difference ΔT is larger. Therefore, the controller 90 estimates the frost formation degree F to be high. be able to.

  In vehicle air conditioner 100, controller 90 estimates the degree of frost formation F based on the ratio of elapsed time tn to predicted frost formation time tf for each elapsed time tn, and the degree of frost formation estimated for each elapsed time tn Accumulate F to calculate an accumulated frost degree S which is an integrated value.

  According to the vehicle air conditioner 100, the frosting determination is performed based on the cumulative frosting degree S calculated by integrating the frosting degree F estimated for each elapsed time tn, so that frosting for each elapsed time tn The frost determination can be performed with all the progress states taken into consideration. For this reason, even if the frost formation prediction time tf changes each time according to the change of the traveling scene of the vehicle at each elapsed time tn, it is accurately determined how much the frost is advancing, and the defrost operation is performed without excess or deficiency. It can be done.

  In the vehicle air conditioner 100, the controller 90 resets the calculated cumulative frost level S when the defrosting operation is finished.

  According to the vehicle air conditioner 100, since the cumulative frost level S is reset when the defrosting operation is completed, the cumulative frost level S can be calculated again. For this reason, when frost formation is not generated in the outdoor heat exchanger 40, it is not erroneously determined that the cumulative frost formation degree S is greater than 0, and the defrosting operation can be executed with high accuracy.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, although the outlet-side refrigerant temperature To of the outdoor heat exchanger 40 is used to determine the defrosting operation end condition in step S207 of FIG. 5 in the above embodiment, the discharge temperature Td of the compressor 20, the discharge pressure Pd, and the suction pressure Only at least one of the above may be used for the determination. As described above, if only one of the discharge temperature Td of the compressor, the discharge pressure Pd, and the suction pressure Ps is used, it is necessary to provide the outdoor heat exchanger outlet temperature sensor 91 when the frosting degree estimation is not performed. Costs can be reduced.

  Further, during the defrosting operation, the heating operation may be appropriately performed using the hot water heater 33 as a heat source. When the heating operation is performed using the hot water heater 33, the controller 90 causes the temperature of the refrigerant compressed by the compressor 20 not to exceed the temperature of the cooling water heated by the hot water heater 33. Control the output. By doing in this way, heating operation can be performed so that the heating request | requirement of a vehicle interior may be satisfy | filled also during execution of defrost operation.

  Furthermore, when the vehicle starts traveling and the defrosting operation is stopped halfway, the controller 90 cancels the defrosting operation based on the ratio of the defrosting operation time tm to the defrost termination determination start time te. May be newly calculated (S = (1-tm / te) × S). For example, it is assumed that the cumulative degree of frost formation S at the start of the defrosting operation is 0.7, and the defrost termination determination start time te is 10 minutes. Assuming that the defrosting operation is stopped when the defrosting operation time tm reaches 5 minutes after the start of the defrosting operation, the controller 90 determines that the cumulative degree of frost formation S at the time of the defrosting operation is 0.35. Calculate (S = (1-5 / 10) × 0.7 = 0.35). By doing this, the controller 90 appropriately executes the defrosting operation without excess or deficiency for the time corresponding to the degree of frost formation at the time of the next stop of the vehicle, based on the cumulative degree of frost formation S recalculated. Can.

100 Vehicle air conditioner 1 Refrigerant cycle 3 Cooling water circulation cycle 7 HVAC unit 8 Engine cooling water circulation cycle 10 Accumulator 20 Compressor (compressor)
Reference Signs List 30 water refrigerant heat exchanger 40 outdoor heat exchanger 41 outdoor fan 50 evaporator 60 refrigerant flow path 60a first bypass flow path 61 first expansion valve 62 first opening / closing valve 70 air mix door 80 engine 90 controller (defrosting operation execution unit Frosting degree estimation unit, temperature difference calculation unit)
91 outdoor heat exchanger outlet temperature sensor 92 outside air temperature sensor 93 discharge temperature sensor 94 discharge pressure sensor 95 suction pressure sensor

Claims (4)

A vehicle air conditioner,
A compressor for compressing a refrigerant,
An outdoor heat exchanger that exchanges heat between the outside air and the refrigerant;
A defrosting operation executing unit for guiding the refrigerant compressed by the compressor to the outdoor heat exchanger and performing a defrosting operation when frost is generated in the outdoor heat exchanger;
A frosting degree estimation unit that estimates a frosting degree as the degree of frosting generated in the outdoor heat exchanger;
A temperature difference calculation unit that calculates a temperature difference between the outlet side refrigerant temperature of the outdoor heat exchanger and the temperature of the outside air;
Equipped with
The defrosting operation execution unit starts the defrosting operation when the vehicle stops, and after a predetermined defrost termination determination start time has elapsed, the outlet side refrigerant temperature of the outdoor heat exchanger, and the discharge of the compressor temperature, the exit defrosting operation when the discharge pressure, and at least one of the suction pressure when rising or has reached a predetermined value,
The defrosting operation execution unit sets the defrosting end determination start time based on the frosting degree estimated by the frosting degree estimation unit,
The frost degree estimation unit
Measuring an elapsed time of a state in which the temperature difference calculated by the temperature difference calculation unit is equal to or more than a frosting temperature difference at which frost formation occurs in the outdoor heat exchanger;
When the heating operation is continued under a predetermined setting condition, a frost formation predicted time in which frost formation is expected to occur in the entire outdoor heat exchanger is set,
The degree of frosting is estimated based on the ratio of the elapsed time to the predicted frosting time,
An air conditioner for a vehicle. A vehicle air conditioner according to claim 1, wherein
The frost degree estimation unit
The frosting degree is estimated based on a ratio of the elapsed time to the predicted frosting time for each elapsed time,
The integration degree is calculated by integrating the degree of frosting estimated for each elapsed time,
An air conditioner for a vehicle. A vehicle air conditioner according to claim 2, wherein
The frost formation degree estimation unit resets the calculated integrated value when the defrosting operation execution unit ends the defrosting operation.
An air conditioner for a vehicle. A vehicle air conditioner according to any one of claims 1 to 3, wherein
The frost formation degree estimation unit sets the frost formation prediction time to be shorter as the temperature difference calculated by the temperature difference calculation unit is larger.
An air conditioner for a vehicle.

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