GB2072318A

GB2072318A - Heating and cooling vehicles

Info

Publication number: GB2072318A
Application number: GB8006131A
Authority: GB
Original assignee: Ford Motor Co Ltd; Ford Motor Co
Current assignee: Ford Motor Co Ltd; Ford Motor Co
Priority date: 1980-02-22
Filing date: 1980-02-22
Publication date: 1981-09-30

Abstract

A heating and cooling system for a motor vehicle comprises a heat exchanger (2) for exchanging heat with air for the passenger compartment (1), an evaporator (9) in a refrigerant circuit (5) arranged to cool a liquid coolant, and two-way flow control valves (14, 15) for directing liquid coolant either from the evaporator (9) or from the engine cooling circuit so that the heat exchanger (2) acts either to heat or to cool the passenger compartment, allowing the evaporator to be positioned at any suitable location in the vehicle. <IMAGE>

Description

SPECIFICATION Heating and cooling system for motor vehicles This invention relates to heating and cooling systems for motor vehicles.

Conventional heating and cooling systems for motor vehicles comprise separate systems for heating and cooling the air in the passenger compartment. Cooling is effected by a refrigerant circuit containing refrigerant fluid and an evaporator which is arranged in heat-exchanging relationship with air in the passenger compartment of the vehicle. Heating is effected by a separate heat exchanger which is arranged to receive hot liquid coolant from the engine cooling circuit of the vehicie.

The evaporator and the heat exchanger occupy a considerable space in the vehicle and must be positioned adjacent the passenger compartment so that they can effectively control the temperature of the air therein. This limits the amount of space available in the vehicle for other components, and places undesirable constraints on the layout of the engine compartment.

According to the present invention, there is provided a heating and cooling system for a motor vehicle comprising a refrigerant circuit containing a refrigerant fluid and including an evaporator; an engine cooling circuit containing liquid coolant and communicating with the vehicle engine; and a heat exchanger for exchanging heat with air for the passenger compartment of the vehicle; characterised in that the evaporator is arranged to transfer heat from liquid coolant to the refrigerant, and in that flow control means is provided for directing liquid coolant either from the evaporator or from the engine cooling circuit through the heat exchanger.

By arranging the evaporator to exchange heat between the refrigerant and liquid coolant rather than between the refrigerant and the air for the passenger compartment, the heat exchanger can operate either to heat or to cool the passenger compartment. As a result, the evaporator need not be located adjacent the passenger compartment, and can be accommodated elsewhere on the vehicle where space is more freely available. The refrigerant circuit can also be fitted more easily to the vehicle after construction.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing, in which: Figure 1 is a schematic diagram of a conventional heating and cooling system; and Figure 2 is a schematic diagram of a vehicle incorporating a heating and cooling system in accordance with the invention.

Referring to Figure 1, a vehicle includes a passenger compartment 1, the front wall of which is indicated by the broken lines. A heat exchanger 2 is installed in the engine compartment of the vehicle in heat exchanging relationship with air passing therethrough into the passenger compartment 1. Hot liquid coolant from the cooling circuit (not shown) of the vehicle engine can be fed along flow line 3 to the heat exchanger 2 and returns to the cooling circuit along return line 4. A refrigerant circuit 5 comprises a compressor 6 which passes refrigerant gas into a condenser 7 from which liquid refrigerant passes through an expansion valve 8 into an evaporator 9 which is in heat-exchanging relationship with air entering the passenger compartment 1 of the vehicle. Gaseous refrigerant returns from the evaporator 9 into the compresser 6.

Since both the heat exchanger 2 and the evaporator 9 exchange heat with air for the passenger compartment 1, both these units must be positioned close to the passenger compartment 1 which places undesirable constraints on the design of adjacent components in the engine compartment.

Referring now to Figure 2, in which parts similar to those shown in Figure 1 have been identified by like reference numerals, the refrigerant circuit 5 is similar to that of Figure 1 except that the evaporator 9 is not arranged to exchange heat with air for the passenger compartment 1. Instead, the evaporator 9 exchanges heat between the refrigerant and liquid coolant which is fed through the evaporator 9 along lines 12, 13 which each terminate in a twoway valve 14, 1 5. The two-way valves are also connected to the flow and return lines 3 and 4 of the heat exchanger 2 so that the heat exchanger 2 can communicate either with the engine cooling circuit (as illustrated) or with the evaporator 9. A pump 1 6 is provided for passing the liquid coolant through the evaporator 9.This pump is preferably an impeller pump driven from the compressor 6.

In the position illustrated, hot coolant from the engine cooling circuit can flow through the heat exchanger 2 to heat air entering the passenger compartment 1.

If the valves 14, 1 5 are rotated 900 clockwise and anti-clockwise respectively, coolant from the evaporator can be passed through the heat exchanger 2 by means of the pump 1 6. When the refrigerant circuit 5 is switched on, the coolant in the evaporator will be cooled, so that the heat exchange 2 cools the air passing into the engine compartment 1.

A bleed valve (not shown) interconnects the coolant in the heat exchanger with the coolant in the engine cooling system to make up for the changes in the volume of liquid coolant circulated through the evaporator 9 resulting from temperature changes.

The arrangement illustrated in Figure 2 has the advantage that the evaporator can be connected to the heat exchanger 9 by flexible hoses. It need not therefore be positioned adjacent the passenger compartment 1, and can be installed in any convenient position on the vehicle. Moreover, if it is desired to fit an air conditioning system to the vehicle after final assembly of the vehicle, the existing heat exchange unit can be used, thus reducing the cost of the installation and facilitating its installation.

Claims

1. A heating and cooling system for a motor vehicle comprising a refrigerant circuit containing a refrigerant fluid and including an evaporator; an engine cooling circuit containing liquid coolant and communicating with the vehicle engine; and a heat exchanger for exchanging heat with air for the passenger compartment of the vehicle; characterised in that the evaporator is arranged to transfer heat from liquid coolant to the refrigerant, and in that flow control means is provided for directing liquid coolant either from the evaporator or from the engine cooling circuit through the heat exchanger.

2. A system according to Claim 1 wherein the evaporator is connected in parallel with the engine cooling circuit and the flow control means includes a two-way valve.

3. A heating and cooling system for a motor vehicle substantially as hereinbefore described with reference to the drawings.