JP2005061364A - Engine cooling system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine cooling system capable of improving fuel consumption of an engine, and improving quick warming performance for heating while securing favorable heating efficiency. <P>SOLUTION: This engine cooling system is provided with a water-medium heat exchanger 18 to heat-exchange between cooling water of the engine 1 and heat exchanging medium of a heat pump cycle 2, an outside air heat exchanger 5 to heat-exchange with outside air taken into the cabin by heat-insulating and expanding the heat exchanging medium of the heat pump cycle 2 to lower its temperature, and a water-outside air heat exchanger 6 to heat-exchange with the outside air passing the outside air heat exchanger 5 by introducing cooling water. When the temperature of the cooling water is lower than a prescribed value, a medium heat exchanging method using the water-medium heat exchanger 18 is used. Cooling water is heated immediately after the engine is started, so that engine friction is reduced when cold to improve fuel consumption. When the temperature of cooling water is a prescribed value or higher, an outside air heat exchange method using the water-outside air heat exchanger 6 is used, so that outside air taken in is heated to improve heating efficiency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling system for an engine having a heat pump cycle / refrigeration cycle using a supercritical medium.

  In a heat pump cycle using a heat exchange medium with a supercritical medium such as carbon dioxide gas, the heat of compression of the heat exchange medium pressurized to a high pressure by a compressor is supplied to the evaporator of the air conditioner and used for heating. On the other hand, the heat exchange medium pressurized by the compressor is cooled and adiabatically expanded to constitute a refrigeration cycle, and this adiabatic-expanded heat exchange medium is supplied to the evaporator so as to be used for cooling the air conditioner. It has become.

By the way, in the air conditioning apparatus for vehicles using such a heat pump cycle, when operating a heat pump cycle, it heat-exchanges between engine cooling water and the heat exchange medium which was discharged | emitted from the evaporator and was low-temperature-ized. A water-medium heat exchanger is provided, and an engine cooling system using the water-medium heat exchanger has been proposed.
2002 SAE AUTOMOTIVE ALTERNATE REFRIGERANT SYSTEMS SYMPOSIUM's Xexel Valeo presentation: “Results from CO2 heat pump applications” on WWW.sae.org/calender/aars/2002/presentations.htm

  However, in such a conventional engine cooling system, there is no need to provide a new radiator in the heater unit, and there is an advantage that it is generally formed only by the heater core provided in the air conditioner, but the cooling water temperature of the engine rises. Therefore, the temperature difference from the high-temperature heat exchange medium becomes small, the heat radiation amount in the water-medium heat exchanger decreases, and the heating efficiency of the air conditioner also decreases.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, the present invention has an object to provide an engine cooling system that improves the fuel efficiency of an engine and increases the speed of heating while ensuring efficient heating efficiency. .

The present invention provides a water-medium heat exchanger for exchanging heat between the engine cooling water and the heat exchange medium of the heat pump cycle, and used for the engine medium heat exchange system,
An outside air heat exchanger that adiabatically expands the heat exchange medium of the heat pump cycle, introduces it at a low temperature, and exchanges heat with the outside air taken into the passenger compartment,
Introducing engine cooling water, exchanging heat with the outside air that has passed through the outside air heat exchanger, providing a water-outside air heat exchanger for use in an engine outside air heat exchange system,
When the engine coolant temperature is lower than the predetermined temperature, the medium heat exchange method and, if necessary, the outside air heat exchange method are used. On the other hand, when the coolant temperature is equal to or higher than the predetermined temperature, only the outside air cooling method is used. And

  The engine cooling system according to the present invention selects the medium heat exchange method in accordance with the operation of the heat pump cycle, so that the engine cooling water is supplied via the water-medium heat exchanger immediately after the engine is started when the outside air temperature is low. Since it can be warmed up, it is possible to reduce engine friction during cold operation and improve fuel efficiency.

  Also, by switching to the outside air heat exchange system as the engine warms up, it is possible to warm the outside air taken in by exchanging heat between the engine cooling water and the water-outside air heat exchanger. Can improve the heating efficiency.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 3 show an embodiment of an engine cooling system according to the present invention, FIG. 1 is a configuration diagram showing a relationship between an engine cooling water passage and a heat pump cycle, and FIG. 2 is an engine cooling water passage and refrigeration. FIG. 3 is a flow chart for selecting a medium heat exchange method and an outside air heat exchange method.

  As shown in FIG. 1, the engine 1 cooling system of the present invention includes a heat pump cycle 2 using carbon dioxide as a heat exchange medium, and a refrigeration cycle 3 using the heat exchange medium of the heat pump cycle 2. An air conditioner 4 is provided.

  The air conditioner 4 includes an evaporator 5 as an outside air heat exchanger, and a heater core 6 as a water-outside air heat exchanger that introduces cooling water of the engine 1 through a passage P. By switching the direction valve 7, the heat exchange medium of the heat pump cycle 2 or the heat exchange medium of the refrigeration cycle 3 is allowed to pass.

  That is, the heat pump cycle 2 supplies the heat exchange medium (carbon dioxide gas) pressurized by the compressor 8 to the evaporator 5 through the four-way valve 7 and the passage P1, and the heat exchange medium that has passed through the evaporator 5 is Then, after being supplied to the gas cooler 9 through the passages P2 and P3, a circuit is circulated to the compressor 8 through the four-way valve 7 and the passage P4.

  The passage P2 is provided with a first electromagnetic valve 10 and a check valve 11, the passage P3 is provided with a sub-expansion valve 12 and a check valve 13, and the passage P4 is provided with an accumulator 14. It is provided.

  On the other hand, in the refrigeration cycle 3, the heat exchange medium pressurized by the compressor 8 is radiated through the gas cooler 9 through the four-way valve 7 and then cooled through the main expansion valve 15 from the passage P5. The heat exchange medium (refrigerant) supplied to the evaporator 5 and passed through the evaporator 5 constitutes a circuit that flows through the passage P1 in the reverse direction and circulates to the compressor 8 through the four-way valve 7 and the passage P4. .

  At this time, a check valve 16 is provided in the passage P5 on the downstream side of the main expansion valve 15, and an internal heat exchanger is provided between the upstream side of the passage P5 and the upstream side of the compressor 8 in the passage P4. 17 is provided.

  Here, the passage P1 of the heat pump cycle 2 is provided with a passage P6 that communicates the upstream side of the evaporator 5 with the passage P3, and the water-medium heat exchange is performed between the passage P6 and the cooling passage P of the engine 1. A medium heat exchanger 18 is provided as a heat exchanger, and the medium heat exchanger 18 exchanges heat between the cooling water and the heat exchange medium.

  A second electromagnetic valve 19 is provided on the upstream side of the medium heat exchanger 18 and a check valve 20 is provided on the downstream side of the medium heat exchanger 18 in the passage P6.

  As shown in FIG. 1, the air conditioner 4 exchanges heat between the heat exchange medium of the heat pump cycle 2 and the outside air taken into the passenger compartment by the evaporator 5 during heating, and passes the warmed outside air to the heater core 6. After further heating, heating air is blown into the passenger compartment from the respective outlets (not shown).

  In addition, as shown in FIG. 2, during dehumidifying heating, the evaporator 5 exchanges heat between the heat exchange medium (refrigerant) of the refrigeration cycle 3 and the intake outside air, and passes the cooled and dehumidified outside air through the heater core 6 to warm it. After that, it is designed to be taken into the passenger compartment.

  Therefore, the engine 1 is cooled by heat exchange between the medium heat exchange system that exchanges heat with the heat exchange medium of the heat pump cycle 2 through the medium heat exchanger 18 and the outside air through the heater core 6. In this embodiment, when the cooling water temperature of the engine 1 is lower than a predetermined temperature (for example, 50 ° C.), the medium heat exchange method is used, while the cooling water is used. When the temperature is equal to or higher than the predetermined temperature, the outside air cooling method is used.

  That is, in the medium heat exchange system, the first electromagnetic valve 10 is closed in FIG. 1 and the second electromagnetic valve 19 is opened, so that the pressurized medium of the heat pump cycle 2 is not passed through the evaporator 5 and the medium heat exchanger. 18 is used for heat exchange with the cooling water of the engine 1 exclusively.

  In the outdoor air heat exchange system, the first electromagnetic valve 10 and the second electromagnetic valve 19 are closed in FIG. 1, and the evaporator is used without passing the pressurized medium of the heat pump cycle 2 through the medium heat exchanger 18. 5 is supplied, and the intake outside air is warmed.

  FIG. 3 shows a processing flowchart of a microcomputer (not shown) for switching the first and second electromagnetic valves 10 and 19. First, by operating the air conditioner 4 in step S1, the cooling water temperature inputted in step S2 is changed. Based on the outside air temperature, it is determined whether the medium heat exchange mode or the outside air heat exchange mode. If it is determined that the outside air heat exchange mode is selected, the process proceeds to step S3 and the first solenoid valve 10 is opened and the second solenoid valve 19 is opened. Is closed, and a heat exchange medium is passed through the evaporator 5 to directly warm the outside air.

  On the other hand, if it is determined in step S2 that the medium heat exchange mode is selected, the process proceeds to step S4, where the first electromagnetic valve 10 is closed and the second electromagnetic valve 19 is opened to exchange heat with the medium heat exchanger 18. Run the medium to warm the engine coolant.

  In the next step S5, it is determined whether or not the detected cooling water temperature has reached a predetermined temperature, in this case, 50 ° C. If it is determined that it is less than 50 ° C (NO), the process returns to step S4. If it is determined that the temperature is 50 ° C. or higher (YES), the process proceeds to step S3.

  According to the engine cooling system of the present embodiment configured as described above, the medium heat exchanger 18 is selected immediately after starting the engine when the outside air temperature is low by selecting the medium heat exchange system in accordance with the operation of the heat pump cycle 2. Since the cooling water of the engine 1 can be warmed through, the engine friction at the time of cooling can be reduced and the fuel efficiency can be improved.

  Moreover, since the outside air heat exchange system is switched to the warming-up of the engine 1, the outside air taken in by exchanging heat between the cooling water of the engine 1 and the evaporator 5 can be warmed. Combined with the effect, the heating efficiency of the air conditioner 4 can be increased.

  Further, although not shown in the flowchart of FIG. 3, if necessary, both the first and second electromagnetic valves 10, 19 are opened, so that the heat exchange medium is changed between the evaporator 5 and the medium heat exchanger 18. The medium heat exchanging method and the outside air heat exchanging method can be used together immediately after the engine is started. In this case, the outside air can be warmed early to obtain a quick heating effect.

  The present invention can be applied to other embodiments within the scope of the gist of the present invention.

It is a block diagram which shows the relationship between the engine cooling water channel | path and heat pump cycle in one Embodiment of this invention. It is a block diagram which shows the relationship between the engine cooling water channel | path and refrigeration cycle in one Embodiment of this invention. It is a flowchart which selects the medium heat exchange system and external air heat exchange system in one Embodiment of this invention.

Explanation of symbols

1 Engine 2 Heat pump cycle 3 Refrigeration cycle 4 Air conditioner 5 Evaporator (outside air heat exchanger)
6 Heater core (water-outside air heat exchanger)
10 First solenoid valve 18 Medium heat exchanger (water-medium heat exchanger)
19 Second solenoid valve

Claims (3)

A water-medium heat exchanger (18) for exchanging heat between the cooling water of the engine (1) and the heat exchange medium of the heat pump cycle (2);
An outside air heat exchanger (5) that heat-exchanges heat with the outside air introduced into the passenger compartment by adiabatically expanding and introducing the heat exchange medium of the heat pump cycle (2) at a low temperature;
Water (outside air heat exchanger) used for the outside air heat exchange system of the engine (1) by introducing cooling water of the engine (1) and exchanging heat with outside air passing through the outside air heat exchanger (5). 6) and
When the cooling water temperature of the engine (1) is lower than a predetermined temperature, the medium heat exchange method and, if necessary, the outside air heat exchange method are used, and when the cooling water temperature is equal to or higher than the predetermined temperature, only the outside air cooling method is used. And engine cooling system.   2. The engine cooling system according to claim 1, wherein when the cooling water temperature is lower than a predetermined temperature, the outside air heat exchange method is used in combination with the medium heat exchange method. The outside air heat exchanger uses an evaporator (5) of an air conditioner (4), and the water-outside air heat exchanger uses a heater core (6) of an air conditioner (4). The engine cooling system according to claim 1 or 2.

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