Heat pump and air conditioning systemn for a vehicle

Abstract

A heat pump and air conditioning system for a vehicle that has at least one coolant loop selectively connecting an engine cooling system with a heater core, a first coolant / refrigerant heat exchanger, and / or a second coolant / refrigerant heat exchanger, in order to warm a passenger compartment of the vehicle. The system also includes a refrigerant loop that includes a first expansion device between a condenser and evaporator, and a second expansion device between the first coolant / refrigerant heat exchanger and the second coolant / refrigerant heat exchanger. The refrigerant loop provides for cooling of the passenger compartment of the vehicle, as well as operating as a heat pump, together with the at least one coolant loop, to provide heat to the vehicle passenger compartment.

Description

BACKGROUND OF INVENTION [0001] The present invention relates to heating, ventilation and air conditioning (HVAC) systems for vehicles, and in particular to such systems having dual modes for providing heat to passenger compartments of the vehicles. [0002] In a conventional automotive vehicle employing an internal combustion engine, the heating of the passenger compartment is accomplished by running engine coolant, typically a mix of water and glycol (antifreeze), through a heater core in the passenger compartment, and then blowing air over the heater core and onto the passengers. The drawback with this is that the heater core will not provide heat until the engine has caused the coolant to warm up. For most conventional engines, this time to warm up the coolant is sufficiently short to satisfy the vehicle passengers. [0003] Now, however, newer engines and powertrain arrangements are being developed where the engine does not produce as much excess heat for the coolant to absorb. Some...

AI Technical Summary

Benefits of technology

[0011] An advantage of the present invention is that the vehicle heating and cooling system can operate in a conventional air conditioning mode, with cooling effectiveness essentially as good as with a conventional air conditioning system, and yet still operate in a heat pump mode to provide supplemental heating when the conventional heating system is not up to an effective operating temperature.

[0012] An additional advantage of the present invention is that a heat pump type of system operation can be combined with an essentially conventional air conditioning operation, without creating potential flash fogging issues.

[0013] Another advantage of the present invention is that, in the heat pump mode of operation, the coolant which flows through the heater core absorbs heat from the refrigerant in the heat pump system, which is more effective than absorbing heat from the ambient air.

[0014] A further advantage of the present invention is that the heating and cooling system can operate in all three modes, with the advantages noted above, while minimizing the additional cost of the system over a conventional HVAC system. That is, heat pump heat exchangers can be added in a loop that is generally in parallel with the conventional air conditioning heat exchangers, while minimizing the costs of the components and valving.

Problems solved by technology

The drawback with this is that the heater core will not provide heat until the engine has caused the coolant to warm up.

Now, however, newer engines and powertrain arrangements are being developed where the engine does not produce as much excess heat for the coolant to absorb.

But these systems become less and less efficient for heating as the heat source temperature becomes colder.

Moreover, since these types of combination air conditioning / heat pump systems employ the air conditioning system evaporator as a condenser in heat pump mode, there can be a flash fogging concern that occurs when the system is switched from operating in the air conditioning mode to operating in the heat pump mode.

That is, when operating in the air conditioning mode, water may condense on the evaporator.

Blowing the humid air on the windshield can possibly cause fogging on a cold windshield, which is generally disliked by vehicle occupants

Another limitation to the air conditioning / heat pump types of systems is that they need to be capable of performing this additional function—over and above a conventional vehicle HVAC system—while minimizing the additional cost of such a system.

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