JP2008290523A - Air-conditioning system for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the energy efficiency of heating operation while preventing a failure of a heat pump in an air-conditioning system for a vehicle. <P>SOLUTION: The air-conditioning system for the vehicle heats external air introduced from the outside of a cabin by a capacitor and introduces it into the cabin. The air-conditioning system recovers the heat of internal air discharged from the inside of the cabin by an evaporator and discharges it to the outside of the cabin. When a in-cabin temperature is lower than a predetermined temperature (S11), the operation of a compressor is stopped (S15). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle air conditioning system that can be mounted on an electric vehicle, a fuel cell vehicle, or the like that does not have a heat source such as an engine.

  As a vehicle air-conditioning system, a system that can perform a cooling operation and a heating operation by switching a refrigerant flow path using a heat pump including a compressor, a condenser, a liquid tank, an evaporator, and the like is known.

Patent Document 1 discloses a technique for recovering thermal energy of exhaust air by using air exhausted outside the passenger compartment for ventilation during heating for evaporation of the refrigerant in the evaporator.
JP 2002-98430 A

  However, in an extremely low temperature state where the outside air temperature is, for example, −20 ° C. or less, the density of the refrigerant decreases, so the pressure on the upstream side of the compressor becomes almost negative, making it difficult to ensure the refrigerant flow rate. This makes it difficult for the oil for lubricating the compressor circulating with the refrigerant to return to the compressor, so that the compressor may be insufficiently lubricated and damaged in the worst case. Moreover, when a part of the circulation path of the refrigerant becomes negative pressure, there is a possibility that a problem such as corrosion of the circulation path due to moisture or air entering the circulation path may occur.

  In addition, when the outside air temperature is extremely low, it may be possible to stop the operation of the heat pump and ensure the heating performance with a heater, etc., but heating with a heater alone will reduce the energy efficiency and the heating capacity may be insufficient. is there.

  An object of this invention is to improve the energy efficiency of heating operation, preventing the malfunction of a heat pump in the vehicle air conditioning system.

  According to the first aspect of the present invention, a compressor that compresses the first refrigerant, a capacitor that dissipates the heat of the first refrigerant, and an expansion means that expands the first refrigerant in the circulation path of the first refrigerant. And an evaporator for absorbing heat by the first refrigerant, in order, outside air introduced from outside the vehicle compartment is heated by a condenser and introduced into the vehicle compartment, and exhausted from the vehicle compartment. It is characterized by comprising an inside air discharging means for collecting heat from the inside air by an evaporator and discharging the outside air to the outside of the passenger compartment, and a compressor stopping means for stopping the operation of the compressor when the passenger compartment temperature is lower than a predetermined temperature.

  The invention according to claim 2 includes a first heater for heating the outside air introduced into the vehicle interior by the outside air introduction means, and heats the outside air by the first heater when the vehicle interior temperature is lower than a predetermined temperature. It is characterized by that.

  The invention according to claim 3 is characterized in that when the passenger compartment temperature is equal to or higher than a predetermined temperature, the compressor is operated to compensate for the lack of heating capacity by the first heater.

  The invention according to claim 4 controls the output of the compressor so that the dew point temperature calculating means for calculating the dew point temperature of the air in the passenger compartment and the evaporator temperature is near the dew point temperature and higher than the dew point temperature. And a compressor control means.

  The invention according to claim 5 is a dehumidifying and heating determining means for determining whether or not dehumidifying heating is required, and when it is determined that dehumidifying heating is required, a part of the air after heat is recovered by the inside air discharging means. It is characterized by comprising exhaust air recirculation means for returning the vehicle interior.

  According to a sixth aspect of the present invention, there is provided a pump that circulates the second refrigerant in a circulation path of the second refrigerant that absorbs heat radiated from the capacitor, and a second heater that heats the second refrigerant. And a heater core that dissipates the heat of the second refrigerant, and the outside air introduction means heats the outside air introduced from the outside of the vehicle interior by the heater core and introduces it into the vehicle interior, and the vehicle interior temperature is equal to or higher than a predetermined temperature. And a heater control means for controlling the output of the second heater so that the temperature of the second refrigerant is lower than the temperature of the first refrigerant.

  According to the first aspect of the present invention, whether or not to operate the heat pump is determined based on the temperature in the vehicle interior, so that the heat pump is operated if the vehicle interior temperature is higher than the predetermined temperature even when the outside air temperature is extremely low. The heating performance can be improved while preventing malfunction of the compressor. Moreover, heating efficiency can be improved by expanding the region where the heat pump operates.

  According to the second aspect of the present invention, since the outside air can be heated by the first heater when the passenger compartment temperature is lower than the predetermined temperature, heating is performed even when the operation of the heat pump is stopped. The heating capacity can be ensured even at extremely low temperatures.

  According to the third aspect of the present invention, when the heat pump is operated, the shortage of the heating capacity is compensated by the first heater, so that the heat pump having a high coefficient of performance can be preferentially used, and the efficiency is improved. Good heating can be done.

  According to the fourth aspect of the present invention, the dew point temperature in the passenger compartment is calculated, and the output of the compressor is controlled so that the evaporator temperature is higher than the dew point temperature in the vicinity of the dew point temperature. be able to. Therefore, since it is not necessary to perform a defrosting operation, heating is not interrupted and stable continuous operation can be performed.

  According to the fifth aspect of the present invention, it is determined whether or not dehumidifying heating is necessary, and when necessary, a part of the air after recovering heat by the inside air discharge means is returned to the vehicle interior. Relative humidity in the passenger compartment is reduced by the air dehumidified in the evaporator, and fogging of the window can be prevented.

  According to the sixth aspect of the invention, since the output of the second heater is controlled so that the temperature of the second refrigerant becomes lower than the temperature of the first refrigerant, the cooling water temperature rises too much and the refrigerant temperature Can be prevented from decreasing the heat exchange efficiency between the cooling water and the refrigerant. Therefore, the heat pump can be operated with priority over the electric heater, and the heating efficiency can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a system configuration diagram of a vehicle air conditioning system in the present embodiment. The vehicle air conditioning system includes a compressor 2, a condenser 3, a liquid tank 4, an expansion valve 5, and an evaporator 6 in this order in a circulation path 1 filled with R134a as a refrigerant to constitute a heat pump.

  The compressor 2 compresses the sucked relatively low-temperature and low-pressure refrigerant and discharges it as a high-temperature and high-pressure refrigerant.

  The condenser 3 exchanges heat between the refrigerant pumped from the compressor 2 and the fluid passing through the condenser 3 to heat the fluid passing through the condenser 3 and reduce the refrigerant temperature to condense.

  The liquid tank 4 gas-liquid separates the condensed refrigerant, and sends out only the liquid phase refrigerant to the expansion valve 5.

  The expansion valve 5 expands (depressurizes) the liquid-phase refrigerant sent from the liquid tank 4 and sends it to the evaporator 6 as a low-temperature and low-pressure refrigerant.

  The evaporator 6 exchanges heat between the refrigerant sent from the expansion valve 5 and the air passing through the evaporator 6 and absorbs heat from the air passing through the evaporator 6.

  FIG. 2 is a schematic configuration diagram showing the configuration of the air conditioning duct 20 of the vehicle air conditioning system in the present embodiment.

  A part of the air conditioning duct 20 is separated into two flow paths 22 and 23 which are parallel by a partition plate 21. One flow path 22 is provided with a blower fan 24, a condenser 3 and an electric heater 26. The air introduced from the outside of the passenger compartment by the blower fan 24 is heated by at least one of the condenser 3 and the electric heater 26 to provide a vehicle. Air blows into the room. Also, the other flow path 23 is provided with a blower fan 25 and an evaporator 6, and heat is recovered by the evaporator 6 from the air introduced from the passenger compartment for ventilation, and the cooled air is discharged outside the passenger compartment. To do.

  That is, cool air outside the passenger compartment is heated by at least one of the condenser 3 and the electric heater 26 and introduced into the passenger compartment to heat the passenger compartment, and is relatively discharged from the passenger compartment to the outside of the passenger compartment for ventilation. The evaporator 6 absorbs heat from high-temperature air.

  Next, control of the vehicle air conditioning system in the present embodiment will be described with reference to the flowchart of FIG. The following control is repeatedly performed every minute time.

  In step S11, it is determined whether the temperature in the passenger compartment is higher than a predetermined temperature. If the vehicle interior temperature is higher than the predetermined temperature, the process proceeds to step S12, the heat pump is operated, and if the vehicle interior temperature is equal to or lower than the predetermined temperature, the process proceeds to step S15, the heat pump is stopped, and heating is performed only with the electric heater. Here, in step S12, the heat pump is operated, but when the heating capacity is insufficient, the electric heater 26 is further operated to supplement the heating capacity. In step S15, the operation of the heat pump is stopped regardless of the required heating capacity. The predetermined temperature is a temperature at which the density of the refrigerant of the heat pump becomes too low and the upstream side of the compressor 2 may become negative pressure, and is set to −20 ° C., for example.

  In step S13, the dew point temperature in the passenger compartment is calculated. The dew point temperature in the passenger compartment is calculated based on the temperature in the passenger compartment and the relative humidity with reference to the wet air diagram shown in FIG. For example, the temperature in the passenger compartment is 20 ° C., the temperature is decreased from the state of point A where the relative humidity is 20%, and the temperature at point B where the relative humidity becomes 100% is −3 ° C. It becomes.

  In step S14, the output of the compressor 2 is controlled so that the temperature of the evaporator 6 is near the dew point temperature and higher than the dew point temperature. That is, the higher the output of the compressor 2, the lower the temperature of the evaporator 6. Therefore, the output of the compressor 2 is controlled so that the temperature of the evaporator 6 is slightly higher than the dew point temperature.

  As described above, in this embodiment, whether or not to operate the heat pump is determined based on the temperature in the vehicle interior, so that even when the outside air temperature is extremely low, the heat pump can be operated if the vehicle interior temperature is higher than a predetermined temperature. Heating performance can be improved while preventing problems with the compressor 2. In addition, since the heat pump can be operated depending on the passenger compartment temperature even at an extremely low temperature where the conventional heat pump has not been operated, the heating efficiency can be improved by expanding the region in which the heat pump operates.

  Further, since the dew point temperature in the passenger compartment is calculated and the output of the compressor 2 is controlled so that the temperature of the evaporator 6 is near the dew point temperature and higher than the dew point temperature, frosting of the evaporator 6 can be prevented. Thereby, since it is not necessary to perform a defrosting operation, heating is not interrupted and stable continuous operation can be performed.

(Second Embodiment)
In the present embodiment, the configuration of the vehicle air conditioning system is the same as that of the first embodiment, and the control content is different. Control of the vehicle air conditioning system in this embodiment will be described with reference to the flowchart of FIG. The following control is repeatedly performed every minute time.

  Steps S21, S22, and S25 are the same as steps S11, S12, and S15 of the first embodiment, respectively, and it is determined whether the vehicle interior temperature is higher than the predetermined temperature. If the vehicle interior temperature is higher than the predetermined temperature, the heat pump If the temperature is equal to or lower than the predetermined temperature, the operation of the heat pump is stopped and heating is performed only by the electric heater 26.

  In step S23, it is determined whether or not dehumidifying heating is necessary. When it is determined that dehumidifying heating is necessary, the process proceeds to step S24, and when it is determined that dehumidifying heating is not necessary, the process ends. Whether or not dehumidifying heating is necessary is determined by calculating the dew point temperature of the passenger compartment air and whether or not window fogging occurs on the windshield. That is, the dew point temperature of the vehicle interior air is calculated by referring to the wet air diagram of FIG. 4 based on the temperature in the vehicle interior and the relative humidity, and the temperature of the windshield that is substantially equal to the outside air temperature is the dew point temperature of the vehicle interior air. When it is below, it is determined that window fogging occurs.

  When it is determined that dehumidifying heating is necessary in this way, in step S24, the air after passing through the evaporator 6 is partially returned to the passenger compartment. As shown in FIG. 6, the air after passing through the evaporator 6 is a part of the dehumidified air after passing through the evaporator 6 flowing through the flow path 23 by opening the mix door 27 provided at the downstream end of the partition plate 21. Is mixed with the air flowing through the flow path 22 and returned to the passenger compartment.

  As described above, in the present embodiment, as in the first embodiment, whether or not to operate the heat pump is determined based on the temperature in the vehicle interior, so that the vehicle interior temperature can be higher than the predetermined temperature even when the outside air temperature is extremely low. Thus, the heat pump can be operated, and the heating performance can be improved while preventing the compressor 2 from malfunctioning. Moreover, heating efficiency can be improved by expanding the region where the heat pump operates.

  In addition, when dehumidifying heating is required, part of the air that has passed through the evaporator 6 is returned to the passenger compartment, so that the relative humidity in the passenger compartment is reduced by the air that has been dehumidified in the evaporator 6 and window fogging is prevented. Can do. Note that dehumidifying heating is required when the outside air temperature is about 15 ° C. and the load of the compressor 2 is low. Therefore, the output of the compressor 2, that is, the heating performance has room, and after the evaporator 6 dehumidifies Even if low-temperature air is introduced into the passenger compartment, heating performance can be reliably ensured while preventing window fogging.

(Third embodiment)
In the present embodiment, the configuration and control of the vehicle air conditioning system are different from those in the first embodiment. FIG. 7 is a system configuration diagram of the vehicle air conditioning system in the present embodiment.

  About a heat pump, it is the same structure as 1st Embodiment, and the capacitor | condenser 3 becomes a water cooling type cooled with cooling water. In other words, heat is exchanged between the refrigerant and the cooling water in the condenser 3, and the cooling water is heated by the refrigerant.

  A pump 31, a condenser 3, an electric heater 32, and a heater core 33 are sequentially connected to a cooling water circulation path 30 for cooling the refrigerant in the condenser 3.

  The pump 31 pressurizes and pumps the sucked cooling water to circulate the cooling water in the circulation path 30.

  The electric heater 32 is provided on the downstream side of the capacitor 3 and generates heat when energized to heat the cooling water.

  The heater core 33 heats the air passing through the heater core 33 by exchanging heat between the cooling water and the air passing through the heater core 33.

  The vehicle air conditioning system is configured as described above, and the electric heater 32 is turned on to further heat the cooling water heated by the condenser 3. As a result, the high-temperature cooling water flows through the heater core 33, whereby the air passing through the heater core 33 is heated, and hot air can be taken into the passenger compartment.

  FIG. 8 is a schematic configuration diagram showing the configuration of the air conditioning duct 20 of the vehicle air conditioning system in the present embodiment. The configuration of the air conditioning duct 20 is the same as that of the first embodiment, but the air conditioning duct 20 of the present embodiment is provided with a heater core 33 instead of the capacitor 3 of FIG. Thereby, the air introduced from the outside of the passenger compartment by the blower fan 24 is heated by the heater core 33 and blown into the passenger compartment. In addition, the electric heater 26 used in the first and second embodiments is not provided in this embodiment, and the electric heater 32 provided in the cooling water circulation path 30 is operated when the heater needs to be operated. Let

  Next, control of the vehicle air conditioning system in the present embodiment will be described with reference to the flowchart of FIG. The following control is repeatedly performed every minute time.

  Steps S31, S32, and S36 are the same as steps S11, S12, and S15 of the first embodiment, respectively, and it is determined whether the vehicle interior temperature is higher than the predetermined temperature. If the vehicle interior temperature is higher than the predetermined temperature, the heat pump If the temperature is equal to or lower than a predetermined temperature, the operation of the heat pump is stopped and heating is performed only by the electric heater 32.

  In step S33, it is determined whether or not a value obtained by subtracting the coolant temperature from the refrigerant temperature is smaller than a predetermined value. If smaller than a predetermined value, it will progress to step S35 and will stop the electric heater 32, and if it is more than a predetermined value, it will progress to step S34 and will operate the electric heater 32. The predetermined value is set to the lowest value of the temperature difference between the refrigerant and the cooling water necessary for maintaining the heat exchange efficiency between the refrigerant and the cooling water in the condenser 3.

  The case where the value obtained by subtracting the cooling water temperature from the refrigerant temperature is smaller than the predetermined value is a case where the temperature of the cooling water rises due to the operation of the electric heater 32 and the difference from the refrigerant temperature becomes small. When becomes smaller, the heat exchange efficiency between the cooling water and the refrigerant is lowered, so that the operation of the electric heater 32 is stopped to prevent the heat exchange efficiency from being lowered. That is, the operation of the electric heater 32 is controlled by the above control so that the coolant temperature is always higher than the coolant temperature by a predetermined value or more.

  As described above, in the present embodiment, as in the first embodiment, whether or not to operate the heat pump is determined based on the temperature in the vehicle interior, so that the vehicle interior temperature can be higher than the predetermined temperature even when the outside air temperature is extremely low. Thus, the heat pump can be operated, and the heating performance can be improved while preventing the compressor 2 from malfunctioning. Moreover, heating efficiency can be improved by expanding the region where the heat pump operates.

  In addition, when the value obtained by subtracting the cooling water temperature from the refrigerant temperature becomes less than the predetermined value, the electric heater 32 is stopped. Therefore, the cooling water temperature rises too much and the difference from the refrigerant temperature becomes small. It can prevent that the heat exchange efficiency with a refrigerant | coolant falls. Furthermore, the heat pump can be operated with priority over the electric heater 32, and the heating efficiency can be improved.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

  For example, although the electric heaters 26 and 32 are used as the heaters in the first to third embodiments, similar effects can be obtained even if a combustion heater or the like is used.

  Moreover, although the outside air is introduced into the flow path 22, a part of the air in the vehicle interior may be introduced. Thereby, heating efficiency can further be improved.

  Furthermore, in the third embodiment, the operation and stop of the electric heater 32 are switched so that the value obtained by subtracting the cooling water temperature from the refrigerant temperature is equal to or higher than a predetermined value, but instead of or in combination with this, The output of the compressor 2 may be controlled.

  Furthermore, it is also possible to perform the heating operation by appropriately combining the first to third embodiments.

It is a system configuration figure showing the composition of the vehicle air-conditioning system in a 1st embodiment. It is a block diagram which shows the structure of the air-conditioning duct in 1st Embodiment. It is a flowchart which shows control of the vehicle air conditioning system in 1st Embodiment. It is a wet air diagram. It is a flowchart which shows control of the vehicle air conditioning system in 2nd Embodiment. It is a block diagram which shows the structure of the air conditioning duct in 2nd Embodiment. It is a system block diagram which shows the structure of the vehicle air conditioning system in 3rd Embodiment. It is a block diagram which shows the structure of the air-conditioning duct in 3rd Embodiment. It is a flowchart which shows control of the vehicle air conditioning system in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Circulation path 2 Compressor 3 Capacitor 4 Liquid tank 5 Expansion valve 6 Evaporator 20 Air conditioning duct 21 Partition plate 22, 23 Flow path 24, 25 Blower fan 26 Electric heater 27 Mix door 30 Circulation path 31 Pump 32 Electric heater 33 Heater core

Claims (6)

In the circulation path (1) of the first refrigerant, the compressor (2) that compresses the first refrigerant, the capacitor (3) that dissipates heat of the first refrigerant, and the first refrigerant are expanded. An air conditioning system for a vehicle comprising in order an expansion means (5) for causing the first refrigerant to absorb heat and an evaporator (6) for absorbing heat;
Outside air introducing means (22, 24) for heating outside air introduced from outside the vehicle compartment by the condenser (3) and introducing it into the vehicle interior;
Inside air exhausting means (23, 25) for recovering heat from the inside of the passenger compartment by recovering heat by the evaporator (6) and exhausting it outside the passenger compartment;
An air conditioning system for a vehicle, comprising: a compressor stopping unit that stops the operation of the compressor (2) when the temperature in the passenger compartment is lower than a predetermined temperature. A first heater (26) for heating the outside air introduced into the passenger compartment by the outside air introduction means (22, 24);
2. The vehicle air conditioning system according to claim 1, wherein when the passenger compartment temperature is lower than a predetermined temperature, the outside air is heated by the first heater.   3. The method according to claim 1, wherein when the passenger compartment temperature is equal to or higher than a predetermined temperature, the compressor (2) is operated, and the first heater (26) compensates for the lack of heating capacity. Air conditioning system for vehicles. Dew point temperature calculating means for calculating the dew point temperature of the air in the passenger compartment;
Compressor control means for controlling the output of the compressor (2) so that the temperature of the evaporator (6) is near the dew point temperature and higher than the dew point temperature;
The vehicle air conditioning system according to any one of claims 1 to 3, further comprising: Dehumidifying and heating determining means for determining whether or not dehumidifying heating is required;
When it is determined that dehumidifying heating is necessary, exhaust air recirculation means (27) for returning a part of the air after recovering heat by the inside air discharge means (23, 25) to the vehicle interior;
The vehicle air conditioning system according to any one of claims 1 to 3, further comprising: A pump (31) that circulates the second refrigerant in a circulation path (30) of the second refrigerant that absorbs heat radiated from the condenser (3), and a second that heats the second refrigerant. Heater (32), and a heater core (33) for radiating the heat of the second refrigerant,
The outside air introducing means (22, 24) heats outside air introduced from outside the vehicle compartment by the heater core (33) and introduces it into the vehicle interior,
Heater control means for controlling the output of the second heater (32) so that the temperature of the second refrigerant is lower than the temperature of the first refrigerant when the vehicle interior temperature is equal to or higher than a predetermined temperature; The vehicular air conditioning system according to any one of claims 1 to 5.