JP3762007B2 - Air conditioner for vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle air conditioner, and more particularly to a vehicle air conditioner suitable for a vehicle having high engine efficiency and low engine exhaust heat to engine coolant.
[0002]
[Prior art]
Conventionally, as a heating device for a vehicle air conditioner, for example, as shown in FIG. 5, engine cooling water used for cooling the engine 101 is circulated by a pump 102, and the warm water as the engine cooling water and the vehicle interior air are used as a heater core. Heating is performed by performing heat exchange at 103. In FIG. 5, 104 is a radiator, 105 is a blower for blower, 106 is an air mix damper, 107 is a switching damper, and 108 is a duct.
[0003]
[Problems to be solved by the invention]
However, in recent years, the efficiency of the engine has been enhanced, and the amount of heat exhausted from the engine to the engine coolant is decreasing. When the engine exhaust heat quantity is small as described above, the hot water temperature may be lowered and the heating capacity may be insufficient particularly under the conditions of low outside air temperature and low engine speed. As a countermeasure, an electric heater using electric energy generated by an engine-driven alternator may be used, but the efficiency is low and it remains at about 60% at most.
[0004]
Therefore, the object of the present invention is to focus on the thermal energy that is discarded by the exhaust gas of the engine, form a heat pump cycle to pump heat from the exhaust gas, and dissipate the pumped thermal energy to the hot water for heating. It is to make it possible to solve the shortage of heating capacity even in an efficient engine.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the vehicular air-conditioning system of the present invention, the heat of the hot water circuit which hot water as the engine cooling water is circulated, the air that is blown into the hot water and the passenger compartment that is circulating in the circuit a heater core for exchanging a refrigerant circuit having a compressor for circulating refrigerant, in a vehicle air conditioner having an indoor evaporator that performs heat exchange with air blown into the refrigerant and the passenger compartment that is circulating in the refrigerant circuit The refrigerant circuit has an outdoor heat exchanger on the compressor outlet side, and absorbs heat from the engine exhaust gas by heat exchange between the first branch circuit leading to the indoor evaporator and the engine exhaust gas and the refrigerant. An exhaust gas evaporator, and a water-cooled condenser that radiates heat into the hot water circuit by heat exchange between the absorbed refrigerant and the hot water, and after passing through the outdoor heat exchanger, The first branch circuit branches to the third branch circuit communicating to the lesser inlet side, and the first and third branch circuits are merged on the compressor inlet side. A selection valve for selecting either the circuit or the third branch circuit is provided .
[0010]
In the third branch circuit, for example, a water-cooled condenser, an exhaust gas evaporator, and an outdoor heat exchanger are arranged in this order in the refrigerant flow direction, and the refrigerant is decompressed and expanded between the water-cooled condenser and the exhaust gas evaporator. A third throttle mechanism for reducing the pressure of the refrigerant is provided between the first throttle mechanism, the exhaust gas evaporator and the outdoor heat exchanger. In the first branch circuit, the outdoor heat exchanger and the indoor A second throttle mechanism is provided between the evaporator and the evaporator.
[0011]
In the vehicle air conditioner as described above, the compressor is a variable displacement compressor, based on a temperature sensor that detects the temperature of hot water, the temperature of the outlet air of the heater core, or the temperature between the fins of the heater core, and a signal from the temperature sensor. And a control device for controlling the discharge capacity of the compressor.
[0012]
The discharge capacity control of the variable displacement compressor is preferably performed based on an arithmetic expression having a feedback arithmetic term including at least proportional control by detecting the temperature of hot water, the outlet air temperature of the heater core, or the temperature between the fins of the heater core. .
[0013]
Further, the first throttle mechanism and at least one of the water-cooled condenser and the exhaust gas evaporator can be configured in an integrated structure. Furthermore, the exhaust gas evaporator may be provided with a gas-liquid separation mechanism for separating condensed water generated when the exhaust gas is cooled and / or a drain port for discharging the condensed water.
[0014]
In the vehicle air conditioner according to the present invention as described above, the heat of the engine exhaust gas is absorbed by the refrigerant in the refrigerant circuit by the exhaust gas evaporator that exchanges heat between the engine exhaust gas and the refrigerant, and the refrigerant absorbs heat. The water pumped from the engine exhaust gas or a part thereof is dissipated into the hot water circuit by the water-cooled condenser that exchanges heat between the water and the hot water (engine cooling water). That is, the refrigerant circuit forms a heat pump cycle.
[0015]
This heat pump cycle recovers thermal energy from the engine exhaust gas and raises the temperature of the hot water. Therefore, in the vehicle equipped with a high efficiency engine, the shortage of heating capacity is solved particularly when the hot water temperature is low and the heating capacity is insufficient under the conditions of low outside air temperature and low engine speed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a vehicle air conditioner according to a first reference example of the present invention, and shows an example when there is no cooling cycle. In the figure, reference numeral 1 denotes an engine, and 2 denotes a radiator. Hot water as engine cooling water used for cooling the engine 1 is circulated in the hot water circuit 4 by a pump 3. The circulated hot water exchanges heat with the air in the duct 9 by the heater core 5, and the air sucked by the blower 6 and heated by the heater core 5 is sent into the vehicle interior. 7 is an air mix damper provided on the upstream side of the heater core 5, 8 is a switching damper for switching the air blowing destination, and 9 is a duct.
[0017]
The configuration so far is substantially the same as the conventional structure shown in FIG. 5, but in this reference example, a refrigerant circuit 11 having a compressor 10 and circulating the refrigerant is provided.
[0018]
The refrigerant circuit 11 is provided with a water-cooled condenser 12 and an exhaust gas evaporator 13 in order in the refrigerant flow direction on the downstream side of the compressor 10, and between the water-cooled condenser 12 and the exhaust gas evaporator 13, the first A first expansion valve 14 is arranged as a throttle mechanism. The first expansion valve 14, at least one of the water-cooled condenser 12 and the exhaust gas evaporator 13 may be configured as an integral structure. In the present embodiment, the three are configured as an integrated device 15.
[0019]
The hot water circuit 4 is passed through the water-cooled condenser 12, and heat from the refrigerant is radiated to the hot water circuit 4 (warm water) by heat exchange between the refrigerant in the refrigerant circuit 11 and the hot water in the hot water circuit 4. It can be done. Further, an exhaust gas circuit 16 from the engine 1 is passed through the exhaust gas evaporator 13, and heat can be absorbed from the engine exhaust gas into the refrigerant circuit 11 (in the refrigerant) by heat exchange between the engine exhaust gas and the refrigerant. Yes. That is, a heat pump cycle is formed in which heat energy from the engine exhaust gas absorbed by the exhaust gas evaporator 13 is radiated to the warm water by the water-cooled condenser 12.
[0020]
The compressor 10 is a variable displacement compressor, and the discharge capacity of the compressor 10 is controlled by a controller 17 as a control device. The controller 17 is controlled based on a signal from the temperature sensor 18 that detects the temperature of the hot water. This temperature sensor may be a sensor that detects the outlet air temperature of the heater core 5 or the temperature between the fins of the heater core 5.
[0021]
The compressor 10 is driven by the engine 1 via a belt or the like, and can be turned on and off by a clutch (not shown). The water-cooled condenser 12 can be installed at any location in the hot water circuit 4, but in this embodiment, it is installed between the outlet of the heater core 5 and the inlet of the engine 1.
[0022]
Although not shown, the exhaust gas evaporator 13 is provided with a gas-liquid separation mechanism for separating condensed water generated when the engine exhaust gas is cooled and / or a drain port for discharging the condensed water. Is preferred. As a result, heat energy can be efficiently pumped from the engine exhaust gas more smoothly.
[0023]
In the first reference example apparatus configured as described above, an auxiliary heating system (heat pump) is added to the conventional hot water heating system shown in FIG.
[0024]
The high-pressure high-temperature gas refrigerant discharged from the compressor 10 and the hot water in the hot water circuit 4 are heat-exchanged by the water-cooled condenser 12, and the gas refrigerant is condensed and liquefied. At this time, the heat energy in the refrigerant is dissipated into the warm water, and the warm water is further heated. The liquid refrigerant from the water-cooled condenser 12 is decompressed and expanded by the first expansion valve 14 to become a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant after expansion and the engine exhaust gas are heat-exchanged by the exhaust gas evaporator 13, and the two-phase refrigerant is evaporated and vaporized. At this time, a part of the thermal energy of the high-temperature engine exhaust gas is absorbed by the refrigerant. The heat-absorbed refrigerant is compressed by the compressor 10 described above, and the heat energy pumped from the exhaust gas is released from the high-pressure high-temperature gas refrigerant discharged from the compressor 10 to the hot water via the water-cooled condenser 12. That is, a heat pump cycle is formed in which the heat energy pumped from the engine exhaust gas is released into the warm water.
[0025]
This heat pump cycle compensates for the lack of heating capacity due to high engine efficiency, and solves the shortage of heating capacity particularly when the hot water temperature is low at low outside air temperature and low engine speed conditions.
[0026]
The discharge capacity control of the variable displacement compressor 10 is performed, for example, as follows. The temperature sensor 18 detects the temperature of the inlet side hot water of the heater core 5 and performs PI (proportional + integral) control based on the detected hot water temperature. For this control, for example, the following arithmetic expression targeting a water temperature of 80 ° C. is used.
VOL = Kp · {(80−TW) + I _n }
However, I _n = I _n-1 + (Δt / Ki) · (80−TW)
Here, VOL: compressor discharge capacity TW: detected water temperature (° C.)
Ki, Kp: Coefficient Δt: Control period In other words, the above equation is a feedback calculation including a proportional calculation term proportional to the deviation between the detected water temperature TW and the water temperature target value.
[0027]
FIG. 2 shows a vehicle air conditioner according to a second reference example of the present invention. This reference example is provided with a cooling circuit as compared with the first reference example. The refrigerant circuit 21 in which the refrigerant is circulated is branched into a first branch circuit 23 and a second branch circuit 24 via a selection valve 22 on the outlet side of the compressor 10, and any of the branch circuits is selected by the selection valve 22. Can be selected. Both branch circuits 23 and 24 are joined at the inlet side of the compressor 10.
[0028]
The first branch circuit 23 is provided with an outdoor heat exchanger 25, a receiver 26, a second expansion valve 27 as a second throttling mechanism, and an indoor evaporator 28 in order in the refrigerant flow direction. In the second branch circuit 24, a water-cooled condenser 12, a first expansion valve 14, and an exhaust gas evaporator 13 are arranged. The water-cooled condenser 12 exchanges heat between the refrigerant and hot water in the hot water circuit 4, and the exhaust gas evaporator 13. Thus, heat exchange between the refrigerant and the engine exhaust gas is performed. The configuration of the second branch circuit 24 is substantially the same as that of the first embodiment. The heater core 5, the temperature sensor 18, and the controller 17 have substantially the same configuration as that of the first embodiment.
[0029]
In this reference example, the selection valve 22 is a three-way valve, and can be switched between cooling and auxiliary heating by switching the selection valve 22.
The switching determination conditions are, for example, as follows.
A / CSW ON → Operates in cooling mode A / CSW OFF, TW <85 ° C. → Operates in auxiliary heating mode A / CSW OFF, TW ≧ 85 ° C. → Not in operation
A / CSW: Air conditioner switch TW: Detected water temperature (° C)
[0030]
That is, in the cooling mode, the high-pressure and high-temperature gas refrigerant discharged from the compressor 10 and the outside air are heat-exchanged by the outdoor heat exchanger 25, and the gas refrigerant is condensed and liquefied. The liquid refrigerant is once stored in the receiver 26, and then depressurized and expanded by the second expansion valve 27. The expanded low-pressure two-phase refrigerant and the vehicle interior air or outside air are heat-exchanged by the indoor evaporator 28, and the two-phase The refrigerant is evaporated and gasified. Thereby, the air supplied into the vehicle compartment is cooled. The refrigerant from the indoor evaporator 28 is returned to the suction side of the compressor 10.
[0031]
On the other hand, in the auxiliary heating mode, the refrigerant discharged from the compressor 10 is returned from the water-cooled condenser 12, the first expansion valve 14, and the exhaust gas evaporator 13 to the inlet side of the compressor 10 by switching the selection valve 22. The operation of the auxiliary heating at this time conforms to the first reference example.
[0032]
FIG. 3 shows a vehicle air conditioner according to an embodiment of the present invention. In the present embodiment, heat energy can be recovered from outside air as compared with the second reference example, and the efficiency of auxiliary heating is further increased.
[0033]
A selection valve 31 composed of a four-way valve is provided on the outlet side of the compressor 10, and the refrigerant circuit 32 can be switched between the first branch circuit 23 and the third branch circuit 33 by switching the selection valve 31. It has become. The configuration of the first branch circuit 23 is substantially the same as that in the second reference example.
[0034]
The third branch circuit 33 is provided with a water-cooled condenser 12, a first expansion valve 14, and an exhaust gas evaporator 13 similar to the above in order in the refrigerant flow direction, and a downstream side thereof is a third throttling mechanism as a third throttling mechanism. Through the three expansion valve 34, the outdoor heat exchanger 25 enters from the side opposite to the first branch circuit 23, and returns from the outdoor heat exchanger 25 to the inlet side of the compressor 10.
[0035]
In the present embodiment, when the first branch circuit 23 is selected and set in the cooling mode, the operation is the same as that of the second reference example.
[0036]
When the third branch circuit 33 is selected and operated in the auxiliary heating mode, the operations of the water-cooled condenser 12, the first expansion valve 14, and the exhaust gas evaporator 13 are the same as those in the second reference example. Then, in the third expansion valve 34, the refrigerant is depressurized to a saturation pressure equal to or lower than the outside air temperature and flows into the outdoor heat exchanger 25. In this mode, the outdoor heat exchanger 25 functions not as a condenser but as an evaporator, and further heat energy is pumped up from the outside air. Therefore, the efficiency of auxiliary heating is further improved compared to the second reference example.
[0037]
In the reference examples 1 and 2 and the examples , the variable displacement compressor is used as the compressor of the heat pump cycle. However, when a fixed displacement (fixed displacement) compressor is used instead, the clutch is turned on and off. The heating capacity of the heat pump is controlled by the operation rate. For example, on / off of the clutch is controlled with reference to the temperature by the temperature sensor 18 as follows.
TW <80: Clutch ON
TW> 85: Clutch off
[0038]
As described above, the auxiliary heating system according to the present invention has been described with reference examples 1 and 2 and examples . Incidentally, compared with the conventional heating system as shown in FIG. In a vehicle air conditioner with an auxiliary heating function that can recover thermal energy, as shown in FIG. 4, the hot water temperature and the cabin temperature rise very quickly, and the heating capacity is insufficient. It will be resolved.
[0039]
【The invention's effect】
As described above, when the vehicle air conditioner of the present invention is used, the refrigerant circuit is used to form the heat pump cycle that can effectively use the heat energy of the engine exhaust gas for heating. However, insufficiency of the heating capacity can be solved even under conditions of low outside air temperature and low engine speed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a vehicle air conditioner according to a first reference example of the present invention.
FIG. 2 is a schematic configuration diagram of a vehicle air conditioner according to a second reference example of the present invention.
FIG. 3 is a schematic configuration diagram of a vehicle air conditioner according to an embodiment of the present invention.
FIG. 4 is a characteristic diagram showing the effect of the present invention.
FIG. 5 is a schematic configuration diagram of a conventional vehicle air conditioner.

Claims (7)

A hot water circuit in which hot water as engine cooling water is circulated, a heater core that performs heat exchange between the hot water circulated in the circuit and air blown into the passenger compartment, and a refrigerant circuit having a compressor that circulates the refrigerant; An air conditioner for a vehicle having an indoor evaporator for exchanging heat between the refrigerant circulated in the refrigerant circuit and the air blown into the vehicle interior , wherein the refrigerant circuit is connected to an outdoor heat exchanger on the compressor outlet side. A first branch circuit leading to the indoor evaporator, an exhaust gas evaporator that absorbs heat from the engine exhaust gas by heat exchange between the engine exhaust gas and the refrigerant, and heat exchange between the heat absorbed refrigerant and the hot water A water-cooled condenser for dissipating heat in the hot water circuit, and branching to a third branch circuit communicating with the compressor inlet side after passing through the outdoor heat exchanger, In addition, the first and third branch circuits are merged on the compressor inlet side, and a selection valve for selecting one of the first branch circuit and the third branch circuit is provided in the branch portion on the compressor outlet side A vehicle air conditioner characterized by the above. In the third branch circuit, the water-cooled condenser, the exhaust gas evaporator, and the outdoor heat exchanger are arranged in this order in the refrigerant flow direction, and the refrigerant is decompressed and expanded between the water-cooled condenser and the exhaust gas evaporator. A third throttle mechanism for reducing the pressure of the refrigerant is provided between the first throttle mechanism, the exhaust gas evaporator and the outdoor heat exchanger, and an outdoor heat exchanger is provided in the first branch circuit. The vehicle air conditioner according to claim 1 , wherein a second throttle mechanism is provided between the vehicle and the indoor evaporator . The compressor is a variable displacement compressor, and a temperature sensor that detects the temperature of the hot water, the outlet air temperature of the heater core, or the temperature between the fins of the heater core, and the discharge capacity of the compressor is controlled based on a signal from the temperature sensor The vehicle air conditioner of Claim 1 or 2 which has a control apparatus to perform . The compressor is a fixed capacity type compressor capable of selecting operation and non-operation, and is based on a temperature sensor for detecting the hot water temperature, the outlet air temperature of the heater core, or the temperature between fins of the heater core, and a signal from the temperature sensor. The vehicle air conditioner according to claim 1, further comprising: a control device that selects whether to operate or not . The signal that determines the discharge capacity of the variable displacement compressor includes the temperature sensor, the sensor temperature obtained by the heater core outlet air temperature sensor or the heater core inter-fin temperature detection sensor, the hot water temperature, and the heater core outlet air temperature. Or the vehicle air conditioner of Claim 3 performed based on the computing equation which has a feedback calculation term including the proportional control calculation term proportional to the deviation with the target value of the inter-fin temperature of a heater core . 6. The vehicle air conditioner according to claim 2, wherein the first throttle mechanism and at least one of the water-cooled condenser and the exhaust gas evaporator are configured in an integrated structure . The exhaust gas evaporator is provided with a gas-liquid separation mechanism for separating condensed water generated when the exhaust gas is cooled and / or a drain port for discharging the condensed water. Vehicle air conditioner.

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