US20080041071A1

US20080041071A1 - Heat pump cycle device

Info

Publication number: US20080041071A1
Application number: US11/784,107
Authority: US
Inventors: Satoshi Itoh
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2006-04-07
Filing date: 2007-04-05
Publication date: 2008-02-21
Also published as: DE102007016298A1; JP2007278624A

Abstract

A heat pump cycle device includes a compressor for drawing and compressing refrigerant, a first high-pressure heat exchanger located for heating a first fluid circulating in a first fluid circuit using high-pressure refrigerant discharged from the compressor, a second high-pressure heat exchanger for heating a second fluid circulating in a second fluid circuit using the high-pressure refrigerant flowing out of the first high-pressure heat exchanger, a first heating heat exchanger located to heat a third fluid using the first fluid, a second heating heat exchanger located to heat the third fluid using the second fluid, a decompression unit located to decompress the high-pressure refrigerant flowing out of the second high-pressure heat exchanger, and a low-pressure heat exchanger for evaporating low-pressure refrigerant decompressed by the decompression unit. Because the first and second high-pressure heat exchangers are located, cycle efficiency can be improved.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2006-106788 filed on Apr. 7, 2006, the contents of which are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a heat pump cycle device in which heat is transported from a low-temperature side to a high-temperature side.
2. Description of the Related Art
U.S. Pat. No. 6,574,977 B2 (corresponding to JP-A-2002-98430) describes a heat pump cycle device that includes a first high-pressure heat exchanger in which high-pressure refrigerant is heat-exchanged with a first fluid, and a second high-pressure heat exchanger in which high-pressure refrigerant flowing out of the first high-pressure heat exchanger is heat-exchanged with a second fluid having a temperature lower than that of the first fluid. Accordingly, a heat quantity obtained from the heat pump cycle device is the sum of a heat amount obtained from the first high-pressure heat exchanger and a heat amount obtained from the second high-pressure side heat exchanger.
Furthermore, JP-A-2002-98430 describes a heat pump cycle device used for an air conditioner in which an interior heat exchanger is used as an evaporator (low-pressure heat exchanger) in a cooling operation mode, and as a refrigerant radiator (high-pressure heat exchanger) in a heating operation mode. However, because the interior heat exchanger is used for both the evaporator and the refrigerant radiator, condensed water generated on the interior heat exchanger during the cooling operation mode or a dehumidifying operation mode is heated and evaporated in the heating operation mode, and is blown into the vehicle compartment together with air, thereby easily causing fog on a windshield of the vehicle.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is a first object of the present invention to provide a heat pump cycle device which can effectively improve cycle efficiency.
It is another object of the present invention to provide a heat pump cycle device used for an air conditioner, which effectively improve cycle efficiency.
It is another object of the present invention to provided a vehicle air conditioner with a heat plump cycle device, which can improve cycle efficiency while preventing a fog on a windshield of the vehicle.
According to an aspect of the present invention, a heat pump cycle device includes: a compressor for drawing and compressing refrigerant; a first high-pressure heat exchanger located to heat a first fluid circulating in a first fluid circuit, using high-pressure refrigerant discharged from the compressor; a second high-pressure heat exchanger located to heat a second fluid circulating in a second fluid circuit, using the high-pressure refrigerant flowing out of the first high-pressure heat exchanger; a first heating heat exchanger located to heat a third fluid using the first fluid; a second heating heat exchanger located to heat the third fluid using the second fluid; a decompression unit located to decompress the high-pressure refrigerant flowing out of the second high-pressure heat exchanger; and a low-pressure heat exchanger which is located to evaporate low-pressure refrigerant decompressed by the decompression unit. Accordingly, efficiency of refrigerant cycle can be improved using the first and second high-pressure heat exchangers and the first and second heating heat exchangers.
Furthermore, because the first and second heating heat exchanger are constructed separately from the low-pressure heat exchanger used as a cooling heat exchanger, the low-pressure heat exchanger is not switched to be operated as a refrigerant radiator. Therefore, it can prevent a windshield from being fogged due to the evaporation of condensed water on the low-pressure heat exchanger during a heating operation mode when the heat pump cycle device is used for an air conditioner.
For example, the first heating heat exchanger may be located downstream of the second heating heat exchanger in a flow direction of the third fluid, or the first high-pressure heat exchanger may have a refrigerant passage extending to a refrigerant passage of the second high-pressure heat exchanger. Furthermore, a heat generating unit may be located in the first fluid circuit, or/and a heat generating unit may be located in the second fluid circuit.
Alternatively, the high-pressure refrigerant may be used as a first heat source. In this case, a second heat source may be located in the first fluid circuit to supply a heat quantity to the first fluid, and a third heat source may be located in the second fluid circuit to supply a heat quantity to the second fluid, which is smaller than the heat quantity supplied from the second heat source.
Alternatively, the decompression unit may include a first decompression portion for decompressing the high-pressure refrigerant from the second high-pressure heat exchanger in a first operation mode, and a second decompression portion for decompressing the high-pressure refrigerant bypassing the first decompression portion in a second operation mode. In this case, the low-pressure heat exchanger includes a first evaporator for evaporating the refrigerant decompressed in the first decompression portion in the first operation mode, and a second evaporator for evaporating the refrigerant decompressed in the second decompression portion in the second operation mode.
Furthermore, the heat pump cycle device may be suitably used for a vehicle air conditioner or an air conditioner for the other use.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments when taken together with the accompanying drawings. In which:
FIG. 1 is a schematic diagram showing a heat pump cycle device according to a first embodiment of the present invention;
FIG. 2 is a perspective view showing an integrated unit of first and second water/refrigerant heat exchangers in which refrigerant is heat-exchanged with water of the first embodiment;
FIG. 3 is a p-h diagram (pressure-specific enthalpy diagram) of the heat pump cycle device according to the first embodiment;
FIG. 4 is a schematic diagram showing a heat pump cycle device according to a second embodiment of the present invention; and
FIG. 5 is a p-h diagram (pressure-specific enthalpy diagram) of a heat pump cycle device in a comparison example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A first embodiment of the present invention will be now described with reference to FIGS. 1 to 3. In this embodiment, a heat pump cycle device of the present invention is typically used for an air conditioner for a vehicle, and is provided to improve a cycle efficiency while having an auxiliary heating function.
As shown in FIG. 1, the heat pump cycle device includes a refrigerant cycle R in which refrigerant circulates, a first water circuit W1 in which engine-cooling water as a first fluid circulates, and a second water circuit W2 in which water as a second fluid circulates. In this embodiment, the first water circuit W1 and the second water circuit W2 are formed independently from each other. However, the first water circuit W1 and the second water circuit W2 may be partially joined with each other.
First, the refrigerant cycle R will be described. In the refrigerant cycle R of FIG. 1, a compressor 1 draws and compresses low-pressure side refrigerant, and discharges compressed high-temperature and high-pressure refrigerant. A first water/refrigerant heat exchanger (first high-pressure heat exchanger) 2 is arranged to perform heat exchange between the high-temperature and high-pressure refrigerant discharged from the compressor 1 and engine-cooling water circulating in the first water circuit W1. Furthermore, a second water/refrigerant heat exchanger (second high-pressure heat exchanger) 3 is arranged to perform heat exchange between the high-pressure refrigerant flowing out of the first water/refrigerant heat exchanger and water circulating in the second water circuit W2.
FIG. 2 shows the first water/refrigerant heat exchanger 2 and the second water/refrigerant heat exchanger 3 in which refrigerant passages 2 a, 3 a are integrally formed. The first water/refrigerant heat exchanger 2 includes the refrigerant passage 2 a in which refrigerant flows, and a water passage 2 b in which engine-cooling water of the first water circuit W1 flows. The first water/refrigerant heat exchanger 2 is provided such that the refrigerant passage 2 a and the water passage 2 b are thermally in contact with each other to perform heat exchange between the refrigerant and the engine-cooling water. Similarly, the second water/refrigerant heat exchanger 3 includes the refrigerant passage 3 a in which the high-pressure refrigerant flows, and a water passage 3 b in which water of the second water circuit W2 flows. The second water/refrigerant heat exchanger 3 is provided such that the refrigerant passage 3 a and the water passage 3 b are thermally in contact with each other to perform heat exchange between the refrigerant and the water. In this embodiment, as shown in FIG. 2, the refrigerant passages 2 a, 3 a are constructed with a continuously extending tube which extends continuously between the first water/refrigerant heat exchanger 2 and the second water/refrigerant heat exchanger 3. Therefore, the first and second water/ refrigerant heat exchangers 2, 3 are integrated by the refrigerant passages 2 a, 3 a.
A heating expansion valve (decompression unit for heating) 10 is located to decompress the high-pressure refrigerant flowing out of the second water/refrigerant heat exchanger 3 during a heating operation mode for heating a vehicle compartment. In contrast, during a cooling operation mode for cooling the vehicle compartment, a cooling bypass valve 11 is opened so that refrigerant bypasses the heating expansion valve 10. Therefore, during the cooling operation mode, the heating expansion valve 10 does not decompresses refrigerant. An exterior heat exchanger 4 located outside of an air conditioning case is used as an evaporator, during the heating operation mode. During the heating operation mode, the exterior heat exchanger 4 evaporates low-pressure refrigerant decompressed in the heating expansion valve 10 by absorbing heat from outside air. In contrast, during the cooling operation mode, the exterior heat exchanger 4 is used as a gas cooler for cooling high-pressure refrigerant from the second water/refrigerant heat exchanger 3.
As shown in FIG. 1, an electrical fan 15 is located to blow air toward the exterior heat exchanger 4 and a water radiator 54. A three-way valve 5 is located downstream of the exterior heat exchanger 4 to switch a refrigerant flow direction in the heating operation mode and in the cooling operation mode. When the three-way valve 5 is switched to a refrigerant flow direction for the heating operation mode, refrigerant flows from the three-way valve 5 along the solid line in FIG. 1, so that the refrigerant from the three-way valve 5 flows into an accumulator (gas-liquid separator) 9.
The accumulator 9 separates the refrigerant flowing out of the exterior heat exchanger 4 into gas refrigerant and liquid refrigerant, and the separated gas refrigerant is drawn into a refrigerant suction side of the compressor 1. A residual refrigerant in the refrigerant cycle R is stored in the gas-liquid separator 9 as liquid refrigerant.
When the three-way valve 5 is switched to a refrigerant flow direction for the cooling operation mode, refrigerant flows from the three-way valve 5 along the chain line in FIG. 1, so that the refrigerant from the three-way valve 5 flows into a cooling expansion valve 7. The cooling expansion valve 7 decompresses high-pressure refrigerant from the exterior heat exchanger 4 during the cooling operation mode.
An evaporator 8 is an interior heat exchanger (low-pressure heat exchanger) located inside the air conditioning case, and cools air (third fluid) passing therethrough. The evaporator 8 evaporates low-pressure refrigerant decompressed in the cooling expansion valve 7 by absorbing heat from air passing through the evaporator 8, during the cooling operation mode. Therefore, during the cooling operation mode, air to be blown into the vehicle compartment can be cooled by the evaporator 8 located in the air conditioning case. The refrigerant flowing out of the evaporator 8 is drawn into the refrigerant suction side of the compressor 1 through the accumulator 9 so that refrigerant circulates again in the refrigerant cycle R.
An inner heat exchanger 6 may be located as a heat recovery unit between the accumulator 9 and the compressor 1. The inner heat exchanger 6 includes a first refrigerant passage 6 a in which refrigerant flowing out of the exterior heat exchanger 4 flows in the cooling operation mode, and a second refrigerant passage in which gas refrigerant flowing out of the evaporator 8 flows to be drawn into the compressor 1. Therefore, during the cooling operation mode, the low-pressure refrigerant to be drawn toward the compressor 1 through the second refrigerant passage 6 b is heat exchanged with high-pressure refrigerant flowing through the first refrigerant passage 6 a, thereby increasing the temperature (enthalpy) of refrigerant to be drawn into the compressor 1. For example, in this embodiment, carbon dioxide can be used as the refrigerant. In this case, the refrigerant cycle R is a super-critical refrigerant cycle in which the pressure of high-pressure side refrigerant before being decompressed becomes equal to or higher than the critical pressure of the refrigerant.
Next, the first water circuit W1 with the first water/refrigerant heat exchanger 2 will be described. An engine 52 for a vehicle running is used as a heat source. Therefore, engine-cooling water (hot water) is heated by the heat generated by the engine 52, and circulates in the first water circuit W1. As shown in FIG. 1, first and second water pumps 53, 56 are located in the first water circuit W1 to circulate water in the first water circuit W1.
A water path directly connected to the engine 52 is provided with the first water pump 53. In contrast, the second water pump 56 is located in a water path between the engine 52 and the first water heater 59 to be coupled with the first water heater 59. The water radiator 54 is for cooling the engine-cooling water flowing out of the engine 52. Furthermore, a bypass water passage 51 is provided such that the engine-cooling water flowing out of the engine 52 returns to the engine 52 through the bypass water passage 51.
A flow adjusting valve 55 is made of a thermostat, for example, to adjust a water flow amount in accordance with a cooling water temperature. In this embodiment, the flow adjusting valve 55 is located so as to adjust a flow amount of water flowing through the bypass water passage 51 and a flow amount of water flowing through the radiator 54. The first water heater 59 (first heating heat exchanger) is located in the air conditioning case to heat air (third fluid) to be blown into the vehicle compartment using the engine-cooling water (hot water) as the heating source. The first water/refrigerant heat exchanger 2 used as an auxiliary heater is located in the first water circuit W1 between the first water pump 53 and the first water heater 59.
A bypass water passage 57 is provided such that the engine-cooling water flowing out of the engine 52 bypasses the first water heater 59 and returns to the engine 52 through the bypass water passage 57. A flow adjusting valve 58 is located to adjust a flow amount of water flowing through the bypass water passage 57 and a flow amount of water flowing through the first water heater 59.
In this embodiment, the second water/refrigerant heat exchanger 3 used as another auxiliary heater is located in the second water circuit W2 in which a second fluid (e.g., water) circulates. Water heated in the second water/refrigerant heat exchanger 3 is circulated in the second water circuit W2. The second water heater 60 is located in the air conditioning case to heat air (third fluid) passing through the second water heater 60 using water heated in the second water/refrigerant heat exchanger 3 as a heating source. A third water pump 61 is located to circulate hot water (second fluid) in the second water circuit W2.
Next, an interior air conditioning unit of the air conditioner, including the air conditioning case accommodating the evaporator 8, the first and second water heaters 59, 60, etc. will be described. For example, the interior air conditioning unit is mounted inside a dashboard (instrument panel) in the vehicle compartment. The air conditioning case of the air conditioning unit forms therein an air passage through which air flows into the vehicle compartment.
A blower is located upstream of the evaporator 8 in an air flow direction within the air conditioning case to blow air into the vehicle compartment through the air passage. For example, the blower includes an air-blowing fan (e.g., centrifugal fan), and a driving motor 12 for driving the air-blowing fan. Furthermore, an inside/outside air switching box is located at an air suction side of the air blowing fan. The inside/outside air switching box includes an outside air introduction port through which outside air (i.e., air outside the vehicle compartment) is introduced, an inside air introducing port through which inside air (i.e., air inside the vehicle compartment) is introduced, and an inside/outside air switching door for opening and closing the outside air introduction port and the inside air introduction port. The inside/outside air switching door is opened and closed by a driving motor 13 shown in FIG. 1.
An air mixing door is located in the air conditioning case at a downstream air side of the evaporator 8, and the first and second water heaters 59, 60 for heating air are located at downstream air sides of the air mixing door. The air mixing door is operated by a driving motor 14 to adjust a flow amount of air passing through the first and second water heaters 59, 60 and a flow amount of air bypassing the first and second water heaters 59, 60. In this embodiment, the first water heater 59 is located at a downstream air side of the second water heater 60. Air from the evaporator 8 bypasses the first and second water heaters 59, 60 through a bypass passage provided in the air conditioning case.
The air mixing door may be a rotatable plate door shown in FIG. 1, and a rotation position of the air mixing door is adjusted by a control unit (ECU) 20 via the driving motor 14. The air mixing door adjusts the flow amount of air passing through the first and second water heaters 59, 60 and the flow amount of air bypassing the first and second water heaters 59, 60, so as to adjust the temperature of air to be blown into the vehicle compartment.
The heated warm air from the first and second water heaters 59, 60 and cool air from the evaporator 8 are mixed in an air mixing portion so that conditioned air having a desired temperature can be obtained. Furthermore, an air-outlet mode switching portion including air outlet openings and air-outlet mode doors is provided at a downstream air side of the air mixing portion.
The air outlet openings include a defroster opening through which air is blown toward an inner surface of a windshield of the vehicle, a face opening through which air is blown toward the upper body of an occupant in the vehicle compartment, a foot opening through which air is blown toward the foot area of the occupant in the vehicle compartment, etc. The air-outlet mode doors includes a defroster door, a face door and a foot door, for example, to open and close the defroster opening, the face opening and the foot opening. The components 1, 5, 7, 10-15, 56, 58 and 61 of the heat pump cycle device with the air conditioning unit are controlled by the control unit 20 so that the operation of the air conditioner is controlled.
Next, the operation of the air conditioner with the heat pump cycle device according to the first embodiment will be described.
1. Heating Operation Mode
When the temperature of the engine-cooling water flowing out of the engine 52 is lower than a predetermined temperature (i.e., a water temperature sufficient to perform the heating operation mode), the components of the refrigerant cycle R are controlled by the control unit 20, such that refrigerant flows through in this order of the compressor 1, the refrigerant passage 2 a of the first water/refrigerant heat exchanger 2, the refrigerant passage 3 a of the second water/refrigerant heat exchanger 3, the heating evaporator 10, the exterior heat exchanger 4, the three-way valve 5, the accumulator 9, and the compressor 1. In contrast, the engine-cooling water (first fluid) circulates in the first water circuit W1 in this order of the water passage 2 b of the first water/refrigerant heat exchanger 2, the first water heater 59, the second water pump 56, the flow adjusting valve 58, the bypass water passage 57, and the water passage 2 b of the first water/refrigerant heat exchanger 2. At the same time, water (second fluid) circulates in the second water circuit W2 in this order of the water passage 3 b of the second water/refrigerant heat exchanger 3, the second water heater 60, the third water pump 61, and the water passage 3 b of the second water/refrigerant heat exchanger 3. Therefore, the engine-cooling water (first fluid) is heated by the high-pressure refrigerant in the first water/refrigerant heat exchanger 2, and water (second fluid) is heated by the high-pressure refrigerant in the second water/refrigerant heat exchanger 3.
Accordingly, a part of heat generated in the refrigerant cycle R is transmitted to the engine-cooling water (first fluid) in the first water/refrigerant heat exchanger 2, and the water (second fluid) in the second water/refrigerant heat exchanger 3, thereby being discharged in the first and second water heaters 59, 60 to air to be blown into the vehicle compartment. In this embodiment, the first water heater 59 is located downstream of the second water heater 60 in the air flow direction in the air conditioning case so as to heat air after being heated in the second water heater 60. Generally, because the temperature of the engine cooling water (first fluid) flowing into the first water heater 59 is higher than the temperature of the water (second fluid) flowing into the second water heater 60, the air after being heated in the second water heater 60 can be further heated by the first water heater 59.
FIG. 3 is a p-h diagram of the refrigerant cycle R (heat pump cycle) with the isothermal line and the saturated vapor line. As shown in FIG. 3, because both the first and second water/ refrigerant heat exchangers 2, 3 are provided, the heat quantity (enthalpy) obtained in the refrigerant cycle R can be effectively increased as compared with a case shown in FIG. 5 where only a single water/refrigerant heat exchanger 2 is provided. Thus, as compared with the refrigerant cycle shown in FIG. 5, the refrigerant cycle R of the present invention can prevent the coefficient of performance (COP) from being reduced due to a reduce of the heat quantity obtained from the refrigerant cycle R. As a result, in this embodiment, the temperature of air to be blown into the vehicle compartment can be quickly increased even when the temperature of the engine-cooling water flowing out of the engine 52 is lower than the predetermined temperature.
In the heating operation mode, because the engine-cooling water is circulated by the second water pump 56 through the bypass water passage 57 as described above, it can prevent heat of the engine 52 from being radiated to the side of the first water heater 59, and the heating operation mode of the engine 52 can be quickly ended.
Furthermore, when the temperature of the engine-cooling water flowing out of the engine 52 becomes equal to or higher than a water temperature flowing out of the first water heater 59, the heating operation mode may performed only using the waste heat of the engine 52. However, the heating operation mode may be performed using both the waste heat of the engine 52 and the refrigerant cycle R.
In the above-described embodiment, at the engine start time, the control unit 20 controls the flow amount adjusting valve 58, such that the side of the engine 52 and the side of the water/refrigerant heat exchanger 2 are separated by the flow amount adjusting valve 58. However, at the engine start time, the flow amount adjusting valve 58 may be operated such that the side of the engine 52 communicates with the side of the water/refrigerant heat exchanger 2. In this case, heating operation mode can be performed using the refrigerant cycle R while the heating of the engine 52 can be fastened by the engine-cooling water heated by the high-pressure refrigerant.
2. Cooling Operation Mode
When the cooling operation mode is set for cooling or/and dehumidifying air in the evaporator 8, refrigerant flows in this order of the compressor 1, the refrigerant passage 2 a of the first water/refrigerant heat exchanger 2, the refrigerant passage 3 a of the second water/refrigerant heat exchanger 3, the cooling bypass valve 11, the exterior heat exchanger 4, the three-way valve 5, the first refrigerant passage 6 a of the inner heat exchanger 6, the cooling expansion valve 7, the evaporator 8, the accumulator 9, the second refrigerant passage 6 b of the inner heat exchanger 6, and the compressor 1.
On the other hand, in the air conditioning case of the air conditioning unit, the air mixing door closes the core surface (air passing portion) of the first and second water heaters 59, 60, so that air cooled by the evaporator 8 is not heated by the waste heat of the engine 52. Furthermore, in this case, the engine-cooling water is circulated in this order of the engine 52, the water passage 2 b of the first water/refrigerant heat exchanger 2, the first water heater 59, the second water pump 56, the flow adjusting valve 58 and the engine 52, while water (second fluid) does not circulate in the second water circuit W2. Alternatively, in the cooling operation mode, the engine-cooling water may bypasses the water/refrigerant heat exchanger 2, the first water heater 59, and the second water pump 56 by the operation of the flow adjusting valve 58, while water (second fluid) also does not circulate in the second water circuit W2.
In the above-described embodiment, in the heating operation mode for heating air in the first and second water heaters 59, 60, the refrigerant cycle R is used as a first heat source for the heating operation mode, and the engine 52 is used as a second heat source for the heating operation mode. However, as the second heat source, a heat-generating unit such as a fuel cell unit (FC stack) which generates electrical power by chemical reaction of Oxygen and Hydrogen may be used.
In the above-described first embodiment, during the cooling operation mode for cooling and/or dehumidifying air in the evaporator 8, the air mixing door fully closes the core portion (air passing portion) of the first and second water heaters 59, 60. However, an open degree of the air mixing door can be suitably adjusted so that the conditioned air having a desired temperature can be obtained.
According to the first embodiment of the present invention, the heat pump cycle device includes the compressor 1 for drawing and compressing refrigerant, the first water/refrigerant heat exchanger 2 which heats the engine cooling water (first fluid) circulating in the first water circuit W1 using the high-pressure refrigerant discharged from the compressor 1, the first water heater 59 for heating air using the engine-cooling water, the second water/refrigerant heat exchanger 3 which heats water (second fluid) circulating in the second water circuit W2 using the high-pressure refrigerant flowing out of the first water/refrigerant heat exchanger 2, the second water heater 60 for heating air using water (second fluid), the expansion valves 7, 10, and the low-pressure heat exchangers 4, 8 (evaporators).
According to the first embodiment of the present invention, even when the first fluid is the engine-cooling water which has a high water temperature in a normal state, the heat of the refrigerant cycle R can be absorbed by the second fluid (water) in the second water circuit W2 and is exhausted in the second water heater 60. Therefore, it is possible to improve the efficiency of the refrigerant cycle R in the heat pump cycle device. Accordingly, when the heat pump cycle device is used for a vehicle air conditioner, a heating heat exchanger for heating air and a cooling heat exchanger for cooling air can be respectively constructed. That is, the first and second water/ refrigerant heat exchangers 2, 3 connected to the first and second water heaters 59, 60 are used as heating heat exchangers for heating air, and the evaporator 8 is used as a cooling heat exchanger for cooling air.
Accordingly, even when the heating operation mode with the first and second water/refrigerant heat exchangers is switched from the cooling operation mode or dehumidifying operation mode with the operation of the evaporator 8, because the evaporator 8 is not used as a heater in the heating operation mode, condensed water generated on the evaporator 8 during the cooling operation mode or the dehumidifying operation mode is not heated by refrigerant. Therefore, the condensed water on the evaporator 8 is not heated and evaporated by the refrigerant flowing in the evaporator 8, thereby effectively restricting water vapor from being blown into the vehicle compartment together with air.
Because the first water/refrigerant heat exchanger 2 is located upstream of the second water/refrigerant heat exchanger 3 in the refrigerant flow, the temperature of the engine-cooling water heated in the first water/refrigerant heat exchanger 2 is generally higher than the temperature of the second fluid (water) heated in the second water/refrigerant heat exchanger 3. Thus, in this embodiment, the first water heater 59 is located downstream from the second water heater 60 in an air flow direction.
Furthermore, because the temperature of the engine-cooling water flowing into the first water heater 59 becomes higher than the temperature of the second fluid (water) flowing into the second water heater 60, heat exchanging efficiency can be effectively improved in both the second water heater 60 on the upstream air side and the first water heater 59 on the downstream air side of the second water heater 60.
In the above-described embodiment, both the first water/refrigerant heat exchanger 2 and the second water/refrigerant heat exchanger 3 are integrally formed using the integrally and continuously extended refrigerant passages 2 a, 3 a. Accordingly, the first water/refrigerant heat exchanger 2 and the second water/refrigerant heat exchanger 3 can be constructed in compact without using a connection pipe between the first water/refrigerant heat exchanger 2 and the second water/refrigerant heat exchanger 3.
When carbon dioxide (CO₂) is used as the refrigerant, the refrigerant pressure on the high-pressure side becomes higher than the critical pressure of the refrigerant. In this case, the refrigerant temperature on the high-pressure side becomes higher (e.g., 150° C. or more), and the heat pump cycle device can be effectively operated.
In this embodiment, the engine 52 (second heat source) is located in the first water circuit W1. Therefore, by locating another second heat source such as a FC stack and a vehicle running engine in the first water circuit W1, the heat-exchanging efficiency with air can be improved.
In this embodiment, when the heat pump cycle device is used for the vehicle air conditioner, an immediately heating efficiency for heating the vehicle compartment can be improved.
According to the first embodiment of the present invention, in the vehicle air conditioner using the heat pump cycle device, the high-pressure refrigerant in the refrigerant cycle R is used as the first heat source for performing the heating operation mode, the engine 52 provided in the first water circuit W1 is used as the second heat source for performing the heating operation mode. In contrast, the evaporator 8 is used only for cooling air (third fluid).
Accordingly, heat of high-temperature refrigerant discharged from the compressor 1 can be exhausted to the engine-cooling water until the temperature (e.g., 85° C.) of the engine-cooling water in the first water circuit W1 including the engine 52. Therefore, heat radiating load of the exterior heat exchanger 4 can be reduced, thereby improving the cycle efficiency. In addition, at the start time of the engine 52, the engine-cooling water in the first water circuit W1 is heated by the heat from the high-pressure refrigerant from the compressor 1. In this case, the heating of the engine 52 can be fastened thereby improving the fuel consumption rate in the vehicle.

Second Embodiment

FIG. 4 is a schematic diagram showing a heat pump cycle device according to a second embodiment of the present invention. In the second embodiment, a third heat source 62 is additionally provided in the second water circuit W2, compared with the above-described first embodiment.
The third heat source 62 is an auxiliary machine (heat generating unit) such as an inverter and an electronic member of a hybrid vehicle, which generates heat when being operated. The auxiliary machine is located in the second water circuit W2 to recover exhaust heat. Furthermore, an auxiliary radiator 63 may be located in the second water circuit W2. In this embodiment, because the third heat source 62 is located in the second water circuit W2 in which the second fluid (water) circulates, the air heating efficiency of the second water heater 60 in the second water circuit W2 can be further improved.
The heat quantity supplied from the second heat source (e.g., engine) 52 is normally larger than the heat quantity supplied from the third heat source (e.g., inverter) 62. Accordingly, the temperature of the engine-cooling water flowing into the first water heater 59, which is located downstream of the second water heater 60, can be made higher than the temperature of the water flowing into the second water heater 60, thereby improving heating efficiency for heating air in both the first water heater 59 and the second water heater 60.
In addition, in this embodiment, the third heat source 62 is located in the second water circuit W2. Because the third heat source 62 is additionally provided in the second water circuit W2, the air heating efficiency in the second water heater 60 can be further improved. In the second embodiment, the other parts may be made the same as those of the above-described first embodiment.
According to the second embodiment, in the heat pump cycle device, the high-pressure refrigerant discharged from the compressor 1 is used as the first heat source, the engine 52 is provided in the first water circuit W1 as the second heat source, and the inverter 62 is provided in the second water circuit W2 as the third heat source. Furthermore, the heat quantity supplied from the engine 52 is generally larger than the heat quantity supplied from the inverter 62. Accordingly, the temperature of the engine cooling water (first fluid) flowing into the first water heater 59 in the first water circuit W1 can be made higher than the temperature of water (second fluid) flowing into the second water heater 60 in the second water circuit W2, thereby improving the air heating efficiency in both the first water heater 59 and the second water heater 60.

Other Embodiments

Although the present invention has been fully described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art.
For example, in the above-described first embodiment, the high-pressure refrigerant discharged from the compressor 1 is used as the first heat source, the engine 52 is used as the second heat source. Furthermore, in the second embodiment, the inverter 62 is used as the third heat source. However, as the first, second or third heat source, the other heat-generating unit such as a fuel device, a fuel cell stack and an electronic device can be used.
In the above-described embodiments, the heat pump cycle device can be used for an air conditioner other than for a vehicle. Furthermore, the heat pump cycle device may be used for a heating apparatus only having a heating operation mode.
In the above-described first and second embodiments, the three-way valve 5 is set such that refrigerant does not flow into the evaporator 8. However, the three-way valve 5 can be set such that refrigerant flows into the evaporator 8 even in the heating operation mode. In this case, low-pressure refrigerant can be evaporated in both the exterior heat exchanger 4 and the evaporator 8. Therefore, even in the heating operation mode, air to be blown into the vehicle compartment can be defogged, thereby improving defogging effect of the windshield of the vehicle.
Such changes and modifications are to be understood as being within the scope of the present invention as defined by the appended claims.

Claims

1. A heat pump cycle device comprising:

a compressor for drawing and compressing refrigerant;

a first high-pressure heat exchanger located to heat a first fluid circulating in a first fluid circuit, using high-pressure refrigerant discharged from the compressor;

a second high-pressure heat exchanger located to heat a second fluid circulating in a second fluid circuit, using the high-pressure refrigerant flowing out of the first high-pressure heat exchanger;

a first heating heat exchanger located to heat a third fluid using the first fluid;

a second heating heat exchanger located to heat the third fluid using the second fluid;

a decompression unit located to decompress the high-pressure refrigerant flowing out of the second high-pressure heat exchanger; and

a low-pressure heat exchanger which is located to evaporate low-pressure refrigerant decompressed by the decompression unit.

2. The heat pump cycle device according to claim 1, wherein the first heating heat exchanger is located downstream of the second heating heat exchanger in a flow direction of the third fluid.

3. The heat pump cycle device according to claim 1, wherein the first high-pressure heat exchanger has a refrigerant passage extending to a refrigerant passage of the second high-pressure heat exchanger.

4. The heat pump cycle device according to claim 1, wherein the high-pressure refrigerant discharged from the compressor is higher than a critical pressure of the refrigerant.

5. The heat pump cycle device according to claim 1, wherein the refrigerant is carbon dioxide.

6. The heat pump cycle device according to claim 1, further comprising a heat generating unit located in the first fluid circuit.

7. The heat pump cycle device according to claim 1, further comprising

a heat generating unit located in the second fluid circuit.

8. The heat pump cycle device according to claim 1, wherein the high-pressure refrigerant is used as a first heat source, the device further comprising:

a second heat source located in the first fluid circuit to supply a heat quantity to the first fluid; and

a third heat source located in the second fluid circuit to supply a heat quantity to the second fluid, which is smaller than the heat quantity supplied from the second heat source.

9. The heat pump cycle device according to claim 1, wherein:

the decompression unit includes a first decompression portion for decompressing the high-pressure refrigerant from the second high-pressure heat exchanger in a first operation mode, and a second decompression portion for decompressing the high-pressure refrigerant bypassing the first decompression portion in a second operation mode; and

the low-pressure heat exchanger includes a first evaporator for evaporating the refrigerant decompressed in the first decompression portion in the first operation mode, and a second evaporator for evaporating the refrigerant decompressed in the second decompression portion in the second operation mode.

10. The heat pump cycle device according to claim 9, wherein the second evaporator is located in a third fluid passage in which the third fluid flows, at an upstream side of the first and second heating heat exchangers in a flow direction of the third fluid.

11. The heat pump cycle device according to claim 1, wherein the first fluid circuit is provided independently from the second fluid circuit.

12. An air conditioner having the heat pump cycle device according to claim 1, wherein the third fluid is air.

13. A vehicle air conditioner having the heat pump cycle device according to claim 1, wherein:

the high-pressure refrigerant is a first heat source;

the first fluid circuit is a water circuit in which water as the first fluid circulates, and is provided with an engine for driving the vehicle as a second heat source; and

the low-pressure heat exchanger is located to cool air as the third fluid.