JP2001246925A - Air conditioner for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a satisfactory heating performance not to give discomfort to an occupant by eliminating heating capability shortage in heating at a low outside air temperature without impairing demands toward size and weight reduction of an interior unit, and without impairing cooling performance. SOLUTION: This air conditioner for a vehicle is provide with a heater core taking at least engine cooling water as a heating source for hot water in an air duct to the vehicle compartment. The air conditioner is characterized in that a hot water heat exchanger for absorbing heat from water of heater core outlet is provided in an outlet hot water circuit side of the heater core, thereby constituting a heat pump cycle for radiating the amount of heat absorbed by the hot water heat exchanger for heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle air conditioner, and more particularly to a vehicle air conditioner which is suitable for a vehicle having a high engine efficiency and a small amount of engine exhaust heat to engine cooling water, and capable of eliminating a decrease in heating performance at a low outside air temperature. The present invention relates to a vehicle air conditioner.

[0002]

2. Description of the Related Art Conventionally, as a heating device of an air conditioner for a vehicle, as shown in FIG. Heating is performed by exchanging heat between room air and a heater core 103. In FIG.
Is a radiator, 105 is a blower for blowing, 106 is an air mix damper, 107 is a switching damper, and 108 is a ventilation duct to the vehicle interior.

However, in recent years, the efficiency of the engine has been improved, and the amount of heat exhausted from the engine to the engine cooling water has been reduced. When the amount of exhaust heat from the engine is small, the temperature of the hot water may be reduced and the heating capacity may be insufficient, particularly under conditions of low outside air temperature and low engine speed. As a countermeasure, an electric heater using electric energy generated by an alternator driven by an engine may be used. However, the efficiency is low and is at most about 60%.

As another countermeasure, Japanese Patent Laid-Open No. 10-1
Japanese Patent Application Publication No. 66847 discloses a device in which heat is pumped from exhaust gas of an engine by a heat pump cycle and the pumped heat energy is radiated to hot water for heating.

[0005] However, in this device, it is necessary to provide an exhaust heat exchanger for exhaust gas, and there is a problem that the cost is increased and the mounting method is difficult. Further, since heat is radiated to the return water from the heater core and returned to the engine and used as a heat source for the heater core, the heat pumped by the heat pump cycle cannot be used so effectively.

Japanese Patent Application Laid-Open No. 10-297270 discloses a system in which hot gas and high-pressure gas in a refrigeration circuit is radiated to the side of water supplied to a heater core.

However, in this system, since the hot gas and the high pressure gas are used, the amount of heat radiation obtained is small, and a sufficient effect cannot be exerted when heating is started at a low outside temperature. In addition, it is possible to increase the amount of heat radiation by increasing the rotation speed of the compressor, but in such a case, the rotation speed is significantly increased with respect to the rotation speed of the compressor at the time of cooling, and the apparatus is less realistic. It will be.

Further, Japanese Patent Application Laid-Open No. 11-198638 discloses that a heat absorbing heat exchanger (evaporator) is used to exchange heat between refrigerant and brine in order to solve the deterioration of heating performance during heating at low outside air temperature. A heat pump cycle that absorbs heat from a brine heater or engine cooling water and radiates heat to an indoor heat exchanger is disclosed.

However, this apparatus has a structure in which a heating indoor heat exchanger for circulating a refrigerant for radiating heat pumped by a heat pump cycle is added. The addition of this heating indoor heat exchanger causes an increase in cost,
It is difficult to reduce the size and weight of indoor units. Also, since the indoor heat exchanger becomes a condenser during cooling,
The heat dissipation impairs the cooling performance. In addition, an example in which a brine cooler, an auxiliary heat exchanger, and the like are additionally installed is also shown, but this increases costs and makes it difficult to reduce the size and weight.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating unit capable of heating at a low outside air temperature without obstructing the demand for reducing the size and weight of the indoor unit and without impairing the cooling performance. It is an object of the present invention to provide an air conditioner for a vehicle, which is capable of achieving sufficient heating performance (heating start-up performance, heating capability) that does not cause occupants to feel uncomfortable.

In particular, it is an object of the present invention to solve a shortage of heating capacity at the time of heating at a low outside air temperature and obtain a sufficient heating performance for a fuel-efficient vehicle with high engine efficiency in recent years.

[0012]

In order to solve the above-mentioned problems, an air conditioner for a vehicle according to the present invention has a heater core having at least engine cooling water as a heat source of hot water in a ventilation duct to a vehicle interior. In the air conditioner, a hot water heat exchanger that absorbs heat from the outlet water of the heater core is provided in the hot water circuit on the outlet side of the heater core, and a heat pump cycle that radiates heat absorbed by the hot water heat exchanger for heating is configured. What you do.

That is, the basic technical idea of the present invention is as follows.
A heat pump cycle is configured for a hot water circuit on the outlet side of a heater core using engine cooling water, and heat pumped by the heat pump cycle is used to eliminate insufficient heating capacity.

The heat pump cycle can be configured between a hot water circuit of a heater core and a refrigeration circuit for circulating a refrigerant. That is, inside the ventilation duct, the heater core and an indoor heat exchanger capable of circulating the refrigerant of the refrigeration circuit are provided, and the heat pump cycle is configured between the hot water heat exchanger and the indoor heat exchanger. Is what it is. Alternatively, the heat pump cycle is configured between the hot water heat exchanger and a heat exchanger provided in an inlet-side hot water circuit of the heater core, and transfers heat pumped from the outlet-side hot water circuit of the heater core to the inlet-side hot water of the heater core. It is also possible to adopt a structure that dissipates heat to the circuit.

When a heat pump cycle is configured between the hot water circuit of the heater core and the refrigeration circuit, for example, the refrigeration circuit supplies refrigerant to a compressor, an outdoor heat exchanger, a cooling expansion valve, the indoor heat exchanger, A cooling circuit that can be circulated in the order of the compressor, a first switching valve provided on the compressor discharge side of the refrigeration circuit, and a bypass circuit A from the first switching valve to an outlet side of the cooling expansion valve. And a second switching valve is provided at an outlet side of the indoor heat exchanger. One side of the second switching valve is connected to a suction side of the compressor, and the other side is used for heating. A structure in which the bypass circuit B is connected to the inlet side of the hot water heat exchanger via an expansion valve and the suction side of the compressor is connected from the outlet side of the hot water heat exchanger. In this structure, the heating expansion valve may be an expansion valve with a maximum operating pressure control function. This expansion valve with a maximum operating pressure control function (hereinafter sometimes referred to as an MOP function-equipped expansion valve) is a conventional expansion valve. Means an expansion valve having a function of not increasing the opening degree of the expansion valve. Further, a structure in which a suction pressure adjusting valve is provided on the suction side of the compressor of the bypass circuit B may be employed. Either the expansion valve with MOP function or the suction pressure adjusting valve may be provided.

Further, it is preferable that a water temperature sensor (for example, a control thermistor) is provided on the hot water inlet side of the hot water heat exchanger for controlling a heat pump cycle.

In the vehicle air conditioner according to the present invention, the heat of the engine cooling water used as the heat source of the heater core is pumped by the hot water heat exchanger provided in the outlet hot water circuit of the heater core. The pumped heat is effectively used as additional heating heat through the heat pump cycle, particularly when the heating capacity is insufficient. That is, a part of the amount of heat of the engine cooling water is first used for heating in the heater core as in the related art, and a part of the amount of heat of the engine cooling water after use in the heater core is further added to the hot water heat exchanger and the heat pump cycle. It is effectively used for heating through. Due to the latter addition of heat, when the heating capacity is insufficient or is likely to occur, especially when heating at low outside temperatures, the heating capacity shortage is promptly resolved, and the occupants do not feel uncomfortable. Heating performance is obtained.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 show an air conditioner for a vehicle according to an embodiment of the present invention. In particular, FIG. 1 shows an operation circuit when the heating capacity is insufficient with a thick line.

In FIG. 1, reference numeral 1 denotes a ventilation duct for sending temperature-controlled air into a vehicle compartment. In the ventilation duct 1, a blower 2, an indoor heat exchanger 3, and a heater core 4 are arranged in this order, and an air mix damper 5 is provided immediately upstream of the heater core 4.

The engine cooling water from the engine 6 flows into the heater core 4 via a pump 7 and an inlet side hot water circuit 8 as a heat source of hot water. The flowing hot water is used for heating by heat exchange with the air in the duct by the heater core 4. The engine cooling water used in the heater core 4 is
It is returned to the engine 6 via the outlet side hot water circuit 9.

The indoor heat exchanger 3 is connected to a refrigeration circuit 10 capable of circulating a refrigerant through the indoor heat exchanger 3. In the refrigeration circuit 10, a compressor 11, an outdoor heat exchanger 12, a receiver 13, and a cooling expansion valve 14 are arranged in this order, and the refrigerant from the cooling expansion valve 14 flows into the indoor heat exchanger 3. The refrigerant flowing out of the indoor heat exchanger 3 is circulated to the suction side of the compressor 11.

The configuration so far is substantially the same as a conventional general vehicle air conditioner. In the vehicle air conditioner according to the present invention, the outlet-side hot water circuit 9 of the heater core 4 is provided.
Is provided with a hot water heat exchanger 15 that absorbs heat from the heater core outlet water. Then, a heat pump cycle is configured in which the heat absorbed by the hot water heat exchanger 15 is released for heating.

In this embodiment, the heat pump cycle is configured between the hot water heat exchanger 15 and the refrigeration circuit 10. That is, a first switching valve 16 is provided on the discharge side of the compressor 11 of the refrigeration circuit 10, and a bypass circuit A17 is connected from the first switching valve 16 to an outlet side of the cooling expansion valve 14. A second switching valve 18 is provided on the outlet side of the indoor heat exchanger 3 of the refrigeration circuit 10, and one switching destination of the second switching valve 18 is connected to the suction side of the compressor 11. The other switching destination is connected to the refrigerant inlet side of the hot water heat exchanger 15 via the heating expansion valve 19. The refrigerant outlet side of the hot water heat exchanger 15 is connected to a bypass circuit B.
20 is connected to the suction side of the compressor 11. Further, in this embodiment, a control thermistor 21 is provided as a water temperature sensor on the hot water inlet side of the hot water heat exchanger 15 so that the temperature of the hot water entering the hot water heat exchanger 15 can be detected.

FIG. 1 shows a control state when the heating capacity of the vehicle air conditioner is insufficient. A thick line indicates a circuit used in the main control, a solid arrow indicates a flow of hot water, and a dotted arrow indicates a flow of a refrigerant. Is shown.

For example, when the heating capacity is insufficient, for example, when the heating is started at a low outside air temperature, as shown in FIG. 1, the refrigerant discharged from the compressor 11 passes through the first switching valve 16 and the bypass circuit A17 to generate indoor heat. The heat is introduced into the exchanger 3, condensed in the indoor heat exchanger 3, and radiated into the ventilation duct 1 by the condensation. After the refrigerant condensed in the indoor heat exchanger 3 passes through the second switching valve 18, it is expanded by the heating expansion valve 19,
It is introduced into the hot water heat exchanger 15. In the hot water heat exchanger 15, the refrigerant is evaporated by heat exchange with the outlet water of the heater core 4, and the refrigerant absorbs heat from the outlet water of the heater core 4 by the evaporation. The refrigerant that has absorbed the heat is returned to the suction side of the compressor 11 through the bypass circuit B20, is compressed again by the compressor 11, and is discharged. Therefore, this system pumps heat from the outlet water of the heater core 4 in the hot water heat exchanger 15 with the refrigerant circulated through the refrigeration circuit 10 in the above circuit configuration, and dissipates the pumped heat by the indoor heat exchanger 3. Construct a heat pump cycle.

By the above heat pump cycle, the heat radiation by circulating the hot water through the heater core 4 is added with the heat radiation by the condensation of the refrigerant in the indoor heat exchanger 3, so that the heating capacity is improved as compared with the case of heating only by the heater core 4. It is greatly increased. As a result, when the heating capacity is insufficient when the heating is started at a low outside air temperature, the insufficient heating capacity can be resolved, and a sufficiently high heating performance can be obtained.

In the heat pump cycle, the hot water heat exchanger 15 functions as an evaporator for absorbing heat, and does not absorb heat from low-temperature outside air, so that a sufficiently large heat absorption can be obtained. Further, the absorbed hot water is returned to the engine 6 again and is sufficiently heated, so that the original heating capacity of the heater core 4 does not decrease.

Further, when heat is absorbed by the evaporator from low-temperature outside air, a problem of frost formation occurs. However, since the heat is absorbed by the hot water heat exchanger 15 as a refrigerant evaporator as described above, the formation of frost is prevented. It is not at all.

The control thermistor 21 as a water temperature sensor detects the inlet water temperature to the hot water heat exchanger 15, and
For example, the compressor 11 in the heat pump cycle
For controlling the heat absorption conditions of the hot water heat exchanger 15 and for preventing low pressure overload of the refrigeration circuit 10. However, even when the heating is started at a low outside air temperature, the temperature of the engine cooling water rises very quickly as shown in the following example.
The heat pump cycle can be established without using any of the first detection signals.

FIG. 2 shows an example of the transition of the water temperature at the outlet of the heater core at the time of starting the heating of the fuel-efficient vehicle at a low outside air temperature, and also shows the data measurement conditions. As shown in FIG. 2, for example, when heating is started under a low outside temperature of about −20 ° C., the outlet water temperature of the heater core 4 becomes about one minute after the start of the operation, and becomes equal to the water temperature at the control thermistor 21. 5
C., which indicates that the hot water heat exchanger 15 can sufficiently absorb heat as an evaporator in the heat pump cycle after that point. That is, there is no problem of frost formation or a decrease in the heating capacity of the heater core 4 itself.

FIG. 3 schematically shows the technical concept of the present invention. The engine cooling water sent to the heater core 4 firstly has a difference between the inlet water temperature of the heater core 4 and the outlet water temperature of the heater core 4. A corresponding amount of heat is radiated by the heater core 4, and subsequently, a heat amount corresponding to the difference between the outlet water temperature of the heater core 4 and the outlet water temperature of the hot water heat exchanger 15 is pumped up by the heat pump cycle. About 1.2 to 1.4 times the amount of heat pumped by the heat pump is dissipated into the duct 1 via the indoor heat exchanger 3. Therefore, as compared with the conventional heating using only the heater core 4 alone, heating rises significantly faster, the heating performance is greatly improved, and the shortage of the heating capacity at low outside air temperature is solved.

When the heating capacity is not insufficient, that is, when the heating performance can be satisfied by simply using the heater core 4 as usual, the circuit configuration using only the heater core 4 can be provided as in the conventional case. . That is, as shown in FIG. 4, the circuit configuration is such that the engine cooling water from the engine 6 is simply passed through the heater core 4 (only the bold line is passed), the heat pump cycle is turned off, and the compressor 11 is turned off. .

Since a heat pump cycle is not required during cooling, a normal refrigerant circulation circuit configuration (thick line in FIG. 5) is used as shown in FIG. That is, the first and second switching valves 16 and 18 are switched, the cooling expansion valve 14 is operated without using the bypass circuits A, B17 and 20, and the indoor heat exchanger 3 is turned into the evaporator and the outdoor heat exchange. By operating the cooler 12 as a condenser, a normal cooling circuit is formed. Since the hot water heat exchanger 15 is completely outside the cooling circuit, there is no adverse effect on the cooling performance.

In the above vehicle air conditioner, the refrigeration circuit 1
In order to cope with a low pressure overload of 0, a configuration as shown in FIG. 6 can be added. For example, the heating expansion valve 19 in FIG. 1 may be replaced with an expansion valve 31 with a MOP function, or a suction pressure regulating valve 32 may be provided on the bypass circuit B20, that is, on the suction side of the compressor 11.
Either the expansion valve 31 with the MOP function or the suction pressure adjusting valve 32 is sufficient.

Further, in the vehicle air conditioner according to the above embodiment, the heat pump cycle is configured between the hot water heat exchanger 15 and the indoor heat exchanger. It is also possible to configure between the exchanger 15 and the hot water circuit on the inlet side of the heater core 4. That is, the heat pumped in the outlet hot water circuit of the heater core 4 is radiated to the inlet hot water circuit of the heater core 4,
The purpose is to increase the heat radiation efficiency of the heater core 4 to compensate for the lack of heating capacity.

For example, as shown in FIG. 7, the outlet hot water circuit 9 of the heater core 4 is provided with a hot water heat exchanger 15 for absorbing heat, and the inlet hot water circuit 8 of the heater core 4 is provided with a hot water heat An exchanger 41 is provided, a heating expansion valve 19 is provided on the inlet side of the hot water heat exchanger 15, and a compressor 42 is provided on the outlet side of the hot water heat exchanger 15 to constitute a circuit 43 for circulating the heat medium. The hot water heat exchanger 15 functions as an evaporator, absorbs heat in the hot water heat exchanger 15, and the hot water heat exchanger 41 functions as a condenser. The heat pumped by the hot water heat exchanger 15 is supplied to the inlet side of the heater core 4. Release heat to the hot water circuit. Even in such a configuration, the calorific value of the warm water that has been returned to the engine 6 as it is conventionally can be effectively used, and can be used to solve the lack of the heating capacity under a low outside air temperature. At the time of cooling, a normal refrigeration circuit may be used.

[0037]

As described above, according to the vehicle air conditioner of the present invention, the hot water heat exchanger for absorbing heat is provided in the outlet hot water circuit of the heater core, and the heat pumped by the hot water heat exchanger is used as the heat pump cycle. Thus, it is possible to effectively use the heater for heating through the air conditioner, so that it is possible to solve the shortage of the heating capacity at the time of heating under a low outside temperature, and to obtain a sufficiently high heating performance that does not cause discomfort to the occupant.

Further, since the heat is pumped by the hot water heat exchanger, there is no fear of frost formation even at a low outside temperature, and since the hot water is circulated with the engine, the heating capacity of the heater core itself decreases. Also does not invite.

Since the hot water heat exchanger for heat absorption is completely outside the cooling refrigeration circuit, it has essentially no effect on cooling performance. There is no need to add accessories or change specifications.

Further, there is substantially no additional equipment in the indoor unit, and it is possible to sufficiently meet the demand for small size and light weight.

As described above, the present invention has an excellent effect particularly on a recent fuel-efficient vehicle with high engine efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic device diagram showing a circuit configuration of a vehicle air conditioner according to an embodiment of the present invention when a heating capacity is insufficient.

FIG. 2 is a characteristic diagram showing an example of transition of a heater core outlet water temperature at the time of starting heating.

FIG. 3 is a characteristic diagram showing a basic technical idea of the present invention.

FIG. 4 is a schematic system diagram showing a circuit configuration when the heating performance is satisfied in the apparatus of FIG.

FIG. 5 is a schematic device diagram showing a circuit configuration during cooling in the apparatus of FIG. 1;

FIG. 6 is a schematic device system diagram showing a modification of the device of FIG. 1;

FIG. 7 is a partial schematic system diagram of a vehicle air conditioner according to another embodiment of the present invention.

FIG. 8 is a schematic device diagram showing a heating circuit configuration of a conventional vehicle air conditioner.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ventilation duct 2 blower 3 indoor heat exchanger 4 heater core 5 air mix damper 6 engine 7 pump 8 heater core inlet hot water circuit 9 heater core outlet hot water circuit 10 refrigeration circuit 11 compressor 12 outdoor heat exchanger 13 receiver 14 for cooling Expansion valve 15 Hot water heat exchanger 16 First switching valve 17 Bypass circuit A 18 Second switching valve 19 Heating expansion valve 20 Bypass circuit B 21 Control thermistor 31 Expansion valve with MOP function 32 Suction pressure regulating valve 41 Radiation Hot water heat exchanger 42 Compressor 43 Heat medium circuit

Claims (7)

[Claims] In a vehicle air conditioner having a heater core in which at least engine cooling water is used as a heat source in a ventilation duct to a vehicle interior, hot water heat exchange that absorbs heat from a heater core outlet water is provided to a heater core outlet side hot water circuit. An air conditioner for a vehicle, comprising: a heat pump cycle that includes a heat exchanger and radiates heat absorbed by the hot water heat exchanger for heating. 2. A heater core and an indoor heat exchanger capable of circulating a refrigerant of a refrigeration circuit are provided in the ventilation duct, and the heat pump cycle is provided between the hot water heat exchanger and the indoor heat exchanger. The vehicle air conditioner according to claim 1, wherein 3. The air conditioner for a vehicle according to claim 1, wherein the heat pump cycle is configured between the hot water heat exchanger and a heat exchanger provided in an inlet-side hot water circuit of a heater core. 4. The refrigeration circuit has a cooling circuit capable of circulating refrigerant in order of a compressor, an outdoor heat exchanger, a cooling expansion valve, the indoor heat exchanger, and the compressor. A first switching valve is provided on the compressor discharge side, a bypass circuit A is connected from the first switching valve to the outlet side of the cooling expansion valve, and a second switching valve is connected to the outlet side of the indoor heat exchanger. Is provided, one side of the second switching valve is connected to the suction side of the compressor, the other side is connected to the inlet side of the hot water heat exchanger via a heating expansion valve, The air conditioner for a vehicle according to claim 2, wherein a bypass circuit (B) is connected from an outlet side of the hot water heat exchanger to a suction side of the compressor. 5. The vehicle air conditioner according to claim 4, wherein said heating expansion valve is an expansion valve with a maximum operating pressure control function. 6. A compressor suction side of the bypass circuit B,
The vehicle air conditioner according to claim 4, further comprising a suction pressure regulating valve. 7. The air conditioner for a vehicle according to claim 1, wherein a water temperature sensor is provided on a hot water inlet side of the hot water heat exchanger.