JP2008111660A - Air conditioner for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a desired operation by circulating properly oil leaked from a compressor, while keeping a desired cooling capacity. <P>SOLUTION: This air conditioner is provided with a refrigeration cycle 100 with a refrigerant flowing in a supercritical condition and a subcritical condition depending on using conditions, when returning the refrigerant delivered from the compressor 1 to the compressor 1 to be circulated, through a vehicular outside heat exchanger 4, the first refrigerator decompression means 5 and a vehicular outside heat exchanger 6. The air conditioner is provided further with a water-refrigerant heat exchanger 2 for conducting heat exchange between the refrigerant of supercritical condition delivered from the compressor 1 while keeping a gas phase condition and engine cooling water, an oil separation means 16 for separating the oil of liquid state from the refrigerant of gaseous state flowing out from the water-refrigerant heat exchanger 2, and an oil decompression means 20a for decompressing the oil separated by the oil separating means 15 to be returned to the compressor 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle air conditioner.

  Conventionally, there is a vehicle air conditioner that circulates carbon dioxide in a refrigeration cycle. In such an air conditioner, in order to improve cycle efficiency, the refrigerant is circulated in a supercritical state, and an oil separator is provided on the outlet side of the vehicle exterior heat exchanger (see, for example, Patent Documents 1 and 2). ).

JP 2000-274844 A JP 2000-274890 A

  However, in the vehicle air conditioner, when the outside air temperature is low (for example, around 10 ° C.), the amount of heat dissipated in the outside heat exchanger increases, and the refrigerant becomes subcritical and the outlet of the outside heat exchanger. It becomes liquid phase on the side. For this reason, although the oil separator is provided, the oil cannot be separated, and it becomes difficult to operate at a desired cycle efficiency. In addition, there is a risk that a problem such as an abnormal stoppage occurs due to insufficient oil in the compressor. Conversely, if the refrigerant is to be maintained in a supercritical state so that the oil can be separated by the oil separator, the cooling capacity of the vehicle interior heat exchanger must be suppressed, and the vehicle interior is sufficiently cooled. It becomes impossible.

  Then, this invention makes it a subject to provide the vehicle air conditioner which can ensure the desired operation | movement by appropriately recirculating the oil which leaks from a compressor, maintaining a desired cooling capability.

As a means for solving the above problems, the present invention provides:
When the refrigerant discharged from the compressor is circulated back to the compressor via the vehicle exterior heat exchanger, the first refrigerant decompression means, and the vehicle interior heat exchanger, the refrigerant on the high-pressure side is supercritical and In a vehicle air conditioner equipped with a refrigeration cycle that flows in a critical state,
A water-refrigerant heat exchanger that maintains the refrigerant discharged from the compressor in a supercritical or gas phase state and exchanges heat with engine cooling water;
Oil separating means for separating oil in a liquid phase from a refrigerant in a gas phase flowing out of the water-refrigerant heat exchanger;
Oil decompression means for decompressing the oil separated by the oil separation means and returning it to the compressor;
It is equipped with.

  With this configuration, the high-temperature refrigerant discharged from the compressor is radiated to the engine cooling water by passing through the water-refrigerant heat exchanger, and flows into the oil separator while maintaining the gaseous state. For this reason, in an oil separator, oil and a refrigerant will be in the state divided into two phases, and are separated appropriately. That is, unlike the case of cooling by the vehicle outside heat exchanger, the cooling does not become excessive due to the influence of the outside air temperature, and there is no fear that the oil and the refrigerant become a liquid phase that is difficult to separate. Therefore, it is possible to sufficiently perform heat exchange in the vehicle exterior heat exchanger, and to sufficiently exhibit the cooling ability of the vehicle interior heat exchanger.

Second refrigerant decompression means for reducing the refrigerant flowing out from the oil separation means as it is during cooling and reducing the pressure during heating into the vehicle exterior heat exchanger;
Bypass means for allowing the refrigerant flowing out of the vehicle exterior heat exchanger to flow back to the compressor by bypassing the first refrigerant decompression means and the vehicle interior heat exchanger during heating;
An internal heat exchanger that exchanges heat between the refrigerant flowing out of the vehicle exterior heat exchanger and the refrigerant flowing out of the vehicle interior heat exchanger;
Is preferably further provided.

  With this configuration, cooling by the vehicle interior heat exchanger can be stopped during cooling. Further, the amount of heat released to the engine coolant can be increased by the water-refrigerant heat exchanger by depressurizing the refrigerant by the second refrigerant depressurizing means and enabling the heat absorption by the outside heat exchanger. Moreover, the oil can be separated by the oil separation means not only during cooling but also during heating. In addition, the cycle efficiency can be further improved.

  If the oil separation means is provided integrally with the water-refrigerant heat exchanger, it is preferable in that a compact and inexpensive configuration can be achieved.

  Cooling of the refrigerant by the water-refrigerant heat exchanger is performed under the most suitable condition by providing a flow rate adjusting means for adjusting the flow rate of the engine cooling water flowing into the water-refrigerant heat exchanger based on the water temperature. Is preferable in that it becomes possible.

  Carbon dioxide can be used as the refrigerant.

  According to the present invention, since the water-refrigerant heat exchanger is provided between the compressor and the vehicle exterior heat exchanger, it is possible to cool the refrigerant and the oil in a state where the refrigerant and the oil are surely separated into two gas phases. It is possible to easily separate the oil by the oil separating means. Further, since the oil separated by the oil separating means can be returned to the compressor in a state where the oil is depressurized and vaporized by the pressure reducing means, there is no problem such as abnormal stop of the compressor.

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

  FIG. 1 is a schematic diagram showing a refrigeration cycle 100 of a vehicle air conditioner according to the present embodiment. In the refrigeration cycle 100, the refrigerant discharged from the compressor 1 is a water-refrigerant heat exchanger 2, a throttle valve 3 as second refrigerant decompression means, an outside heat exchanger 4, and first refrigerant decompression means. It circulates back to the compressor 1 via the expansion valve 5 and the vehicle interior heat exchanger 6. The refrigerant flowing out from the vehicle exterior heat exchanger 4 and flowing toward the vehicle interior heat exchanger 6 and the refrigerant flowing out from the vehicle interior heat exchanger 6 and returning to the compressor 1 are heated by the internal heat exchanger 7. Have been replaced. Here, carbon dioxide is used as the refrigerant.

  The compressor 1 receives the driving force of the engine 8 via a clutch (not shown), and is driven at a predetermined rotational speed to discharge the refrigerant in a high temperature / high pressure state.

  As shown in FIGS. 2 to 4, the water-refrigerant heat exchanger 2 includes a flat first tube between the first header 9 and the second header 10 and between the third header 11 and the fourth header 12. 13 and the second tube 14, and the tubes 13 and 14 are in surface contact with each other. High temperature and high pressure refrigerant discharged from the compressor 1 flows into the first header 9. The high temperature / high pressure refrigerant flows into the second header 10 through the first tube 13. Engine coolant flows into the third header 11 and flows to the fourth header 12 via the second tube 14. The amount of engine cooling water is adjusted by the flow rate adjustment valve 30. The flow rate adjustment valve 30 is adjusted in opening degree based on a temperature detected by a temperature sensor (not shown) that detects the temperature of engine cooling water.

  As shown in FIG. 2, the second header 10 is divided into two in the longitudinal direction by the first shielding plate 15, and a refrigerant chamber 16 to which the first tube 13 is connected and an oil separation chamber 17 are formed. A plurality of through holes 15 a are formed in the first shielding plate 15 in two rows along the longitudinal direction. The through holes 15a are located on both sides displaced parallel to the flow direction so that the refrigerant flowing into the refrigerant chamber 16 from the first tube 13 does not directly flow out to the refrigerant chamber. Thereby, a refrigerant | coolant once collides with the 1st shielding board 15, and separation of the oil from a refrigerant | coolant is performed appropriately.

  Further, as shown in FIG. 4, a second shielding plate 18 is provided at the lower part of the second header 10, and an oil recovery chamber 19 is formed. A plurality of communication holes 18 a communicating with the oil separation chamber 17 are formed in the second shielding plate 18 so that oil separated from the refrigerant is collected. The oil recovered in the oil recovery chamber 19 is returned to the compressor 2 through the oil recovery pipe 20. A throttle portion 20a (orifice), which is an oil decompression means, is formed in the oil recovery pipe 20 so that the oil passing therethrough is decompressed.

  As shown in FIGS. 2 and 3, the first tube 13 is formed by forming a plurality of communication holes 13a at a predetermined interval in a plate-like material formed of a metal material or the like having excellent heat conductivity. Etc. and is excellent in pressure resistance. The 2nd tube 14 is partitioned off by the partition part 14a which provided the inside with the predetermined space | interval, and each partition part 14a is excised by each upper and lower ends so that the flow of a refrigerant may meander. The 1st tube 13 and the 2nd tube 14 are integrated so that a surface contact may be carried out except the connection part to each header 9,12,10,11 of both ends. Heat can be dissipated from the refrigerant to the engine coolant at this surface contact portion.

  The vehicle exterior heat exchanger 4 is disposed in the front part of the vehicle, and exchanges heat between the high-temperature and high-pressure refrigerant passing therethrough and the outside air to cool the refrigerant.

  The first expansion valve 5 depressurizes the passing refrigerant to a state where it easily vaporizes.

  The vehicle interior heat exchanger 6 is provided in an air conditioning unit 21 disposed in the front part of the vehicle, and cools and dehumidifies the air passing through the air conditioning unit 21 as the refrigerant passing through the interior is vaporized. The air conditioning unit 21 is provided with an air mix damper 22 on the downstream side of the vehicle interior heat exchanger 6, and the cold air passing therethrough is divided. One of the divided cold air is heated by the heater core 23 in which the engine cooling water flows, mixed with the remaining cold air, adjusted to a desired temperature, and then blown into the vehicle.

  An on-off valve 25 is connected in parallel to the vehicle interior heat exchanger 4 and the first expansion valve 5 by a bypass pipe 24. The on-off valve 25 is fully closed during cooling and dehumidifying heating, and is fully opened during heating.

  Next, the operation of the vehicle air conditioner provided with the refrigeration cycle having the above configuration will be described.

  In the cooling operation, the throttle valve 3 is fully opened and the on-off valve 25 is fully closed. When the compressor 1 is driven, the refrigerant is discharged in a high temperature / high pressure state, and first flows into the first header 9 of the water-refrigerant heat exchanger 2 and flows to the second header 10 through the first tube 13. To do. While the refrigerant flows through the first tube 13, the refrigerant is cooled by exchanging heat with the engine cooling water flowing through the second tube 14. At this time, the amount of engine cooling water flowing through the second tube 14 is adjusted to a value corresponding to the difference in water temperature by the flow rate adjusting valve 30. That is, the heat exchange capacity of the water-refrigerant heat exchanger 2 is set to a desired value so that the refrigerant after passing does not condense.

  The refrigerant that has flowed into the second header 10 flows from the refrigerant chamber 16 into the oil separation chamber 17 through the through hole 15 a of the first shielding plate 15. Although the refrigerant and the oil mixed therein are cooled by passing through the water-refrigerant heat exchanger 2, the refrigerant and the oil are maintained in a vaporized state, so that they are separated into refrigerant and oil without mixing. It has become a state. For this reason, oil with a large specific gravity moves downward by its own weight by the first shielding plate 15. Then, the oil is recovered in the oil recovery chamber 19 through the communication hole of the second shielding plate 18 and is returned to the compressor 1 through the oil recovery pipe 20. The oil is decompressed by the throttle portion 20a when flowing through the oil recovery pipe 20, and is completely vaporized when flowing into the compressor 1.

  The refrigerant that has flowed into the refrigerant chamber 16 flows through the vehicle exterior heat exchanger 4 and is cooled by heat exchange with the outside air. The refrigerant cooled by the vehicle exterior heat exchanger 4 flows through the internal heat exchanger 7 and is further cooled, and then flows into the vehicle interior heat exchanger 6. In the vehicle interior heat exchanger 6, the refrigerant partially vaporizes by flowing inside, and cools and dehumidifies the air passing through the air conditioning unit 21. The refrigerant that has flowed out of the vehicle interior heat exchanger 6 passes through the internal heat exchanger 7 and absorbs heat from the high-temperature refrigerant that travels from the vehicle exterior heat exchanger 4 toward the vehicle interior heat exchanger 6 to be completely vaporized. For this reason, an accumulator (gas-liquid separator) is unnecessary.

  On the other hand, in the heating operation, if the temperature of the engine coolant does not rise sufficiently immediately after the start of the operation, the compressor 1 is driven with the opening of the throttle valve 3 adjusted and the on-off valve 25 fully opened. Start. As a result, the refrigerant discharged from the compressor 1 flows through the water-refrigerant heat exchanger 2 and exchanges heat with the engine coolant in a high temperature and high pressure state, as described above. The oil contained in the refrigerant is returned to the compressor 1 as described above. The refrigerant cooled by the water-refrigerant heat exchanger 2 is depressurized by the throttle valve 3 and is vaporized and absorbs heat from the outside air when passing through the vehicle exterior heat exchanger 4. Then, the vehicle interior heat exchanger 6 is bypassed and returned to the compressor 1 for circulation. As described above, the refrigerant is vaporized by the vehicle exterior heat exchanger 4, and the temperature sufficiently rises by bypassing the vehicle interior heat exchanger 6. Therefore, the temperature of the engine coolant can be rapidly increased by the water-refrigerant heat exchanger 2, and the heating of the vehicle interior by the heater core 23 can be started immediately after the start of the heating operation. Thereafter, when the temperature of the engine coolant rises and heating of the engine coolant by the water-refrigerant heat exchanger 2 becomes unnecessary, the driving of the compressor 1 is stopped.

  When dehumidifying heating is required, the throttle valve 3 may be fully opened and the open / close valve 25 may be fully closed, as in the cooling operation. Thereby, the dehumidification of the air which passes the inside of the air-conditioning unit 21 is attained by the vehicle interior heat exchanger 6 like the above.

It is the schematic which shows the refrigerating cycle of the vehicle air conditioner which concerns on this embodiment. It is a perspective view which shows the water-refrigerant heat exchanger of FIG. (A) is a top view of FIG. 2, (b) is a front view. It is a longitudinal cross-sectional view of the 2nd header of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Compressor 2 ... Water-refrigerant heat exchanger 3 ... Throttle valve (2nd refrigerant | coolant decompression means)
4 ... Outside heat exchanger 5 ... First expansion valve (first refrigerant pressure reducing means)
6 ... Inside heat exchanger 7 ... Internal heat exchanger 8 ... Engine 9 ... First header 10 ... Second header 11 ... Third header 12 ... Fourth header 13 ... First tube 14 ... Second tube 15 ... First Shield plate (oil separation means)
DESCRIPTION OF SYMBOLS 16 ... Refrigerant chamber 17 ... Oil separation chamber 18 ... 2nd shielding plate 19 ... Oil recovery chamber 20 ... Bypass flow path 20a ... Restriction part (oil decompression means)
23 ... Heater core 24 ... Bypass pipe 25 ... Open / close valve 30 ... Flow rate adjusting valve (flow rate adjusting means)
100: Refrigeration cycle

Claims (5)

When the refrigerant discharged from the compressor is circulated back to the compressor via the vehicle exterior heat exchanger, the first refrigerant decompression means, and the vehicle interior heat exchanger, the refrigerant on the high pressure side is supercritical and In a vehicle air conditioner equipped with a refrigeration cycle that flows in a critical state,
A water-refrigerant heat exchanger that maintains the refrigerant discharged from the compressor in a supercritical or gas phase state and exchanges heat with engine cooling water;
Oil separating means for separating oil in a liquid phase from a refrigerant in a gas phase flowing out of the water-refrigerant heat exchanger;
Oil decompression means for decompressing the oil separated by the oil separation means and returning it to the compressor;
A vehicle air conditioner comprising: Second refrigerant decompression means for reducing the refrigerant flowing out of the oil separation means as it is during cooling and depressurizing during heating and flowing into the vehicle exterior heat exchanger;
Bypass means for allowing the refrigerant flowing out of the vehicle exterior heat exchanger to flow back to the compressor by bypassing the first refrigerant decompression device and the vehicle interior heat exchanger during heating;
An internal heat exchanger that exchanges heat between the refrigerant flowing out of the vehicle exterior heat exchanger and the refrigerant flowing out of the vehicle interior heat exchanger;
The vehicle air conditioner according to claim 1, further comprising:   The vehicle air conditioner according to claim 1 or 2, wherein the oil separation means is provided integrally with the water-refrigerant heat exchanger.   4. The vehicle according to claim 1, further comprising a flow rate adjusting unit that adjusts a flow rate of the engine cooling water flowing into the water-refrigerant heat exchanger based on a water temperature thereof. 5. Air conditioner.   The vehicle air conditioner according to any one of claims 1 to 4, wherein carbon dioxide is used as the refrigerant.

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