Air-conditioning system for a motor vehicle
View Patent ↗In an air-conditioning system for a motor vehicle having an integrated heat pump for cooling and heating, in which refrigerant is circulated and which allows heat exchange with the incoming air for the interior compartment of the motor vehicle, the heat transfer is effected either directly, by means of a refrigerant/air heat exchanger through which the air for the interior compartment is conducted, or by means of a secondary refrigerant circuit, which includes two expansion devices and three heat exchangers provided in the refrigerant circuit of the system.
1. An air conditioning system with a heating circuit for heating and a cooling circuit for cooling an incoming air stream for an interior compartment of a motor vehicle having an engine coolant circuit, said system including
a refrigerant circuit, which includes
a refrigerant compressor ( 12 ) for compressing substantially gaseous refrigerant,
a switchover valve ( 13 ) arranged downstream of said refrigerant compressor ( 12 ) for directing the refrigerant compressed in said refrigerant compressor ( 2 ) selectively through one of said cooling and heating circuits,
a first heat exchanger ( 14 ) arranged in said cooling circuit downstream of the refrigerant compressor ( 12 ) for dissipating heat from the refrigerant,
a first expansion device ( 16 ) arranged downstream of the first heat exchanger ( 14 ),
a second heat exchanger ( 15 ) arranged downstream of said first heat exchanger ( 14 ) for transferring heat from the compressed refrigerant to the expanded refrigerant before it is returned said refrigerant compressor ( 12 ),
a second expansion device ( 17 ) arranged in said cooling circuit downstream of said first expansion device ( 16 ) and upstream of said second heat exchanger ( 15 ),
a third heat exchanger ( 5 ) arranged in the cooling circuit between said first and second expansion devices ( 16 , 17 ), such that the pressure level of the third heat exchanger ( 5 ) can be controlled by controlling the first and second expansion devices ( 16 , 17 ) and a forth heat exchanger ( 27 ) arranged in said heating circuit for transferring heat to the engine coolant circuit when the switch-over valve ( 13 ) is set to direct the refrigerant compressed in the refrigerant compressor ( 12 ) to the heating circuit.
2. The air conditioning system as claimed in claim 1 , wherein
the installed heat transfer capacity of the first and third heat exchangers corresponds to the maximum heating capacity of the heat pump system for the incoming air for the interior compartment of the motor vehicle.
3. The air conditioning system as claimed in claim 1 , wherein at least one of
the first and the third heat exchangers is a refrigerant/heat-transfer liquid heat exchanger,
a heat-transfer liquid being conducted through a second circuit, via which
heat can be transferred from the refrigerant circuit to the air flow to the interior compartment of the vehicle.
4. The air conditioning system for a motor vehicle as claimed in claim 1 ,
in which the incoming air for the interior compartment of the motor vehicle can be heated via the first heat exchanger of the cooling circuit,
the refrigerant can be expanded in the first expansion device ( 16 ) from a higher pressure level to a suitable intermediate pressure level by means of the first expansion device ( 16 ), and
in which heat can be taken up from the compressed refrigerant via the second heat exchanger ( 15 ), and
heat can be transferred from or to the refrigerant via the third heat exchanger ( 5 ) at the intermediate pressure level, a
the refrigerant can be expanded from the intermediate pressure level by means of a second expansion device ( 17 ).
5. The air conditioning system as claimed in claim 4 , wherein
the incoming air flow for the interior compartment is dried with the aid of the heat which is supplied to the air supplied to the interior vehicle compartment at the intermediate pressure level.
6. The air conditioning system as claimed in claim 1 , wherein the heating circuit extending from the switch-over valve ( 13 ) extends through the engine coolant heat exchanger ( 27 ) for transferring heat to the engine coolant and is connected to the line extending from the second beat exchanger ( 15 ) to the refrigerant compressor ( 12 ) which line includes a switch-over valve ( 21 ), and duct means for selectively conducting the refrigerant through the first heat exchanger ( 14 ) before it is returned to the refrigerant compressor ( 12 ).
7. The air conditioning system as claimed in claim 6 , wherein the duct means for selectively conducting the refrigerant through the first heat exchanger ( 14 ) before it is returned to the refrigerant compressor includes the second expansion valve ahead of the first heat exchanger ( 14 ).
8. The air conditioning system as claimed in claim 6 , wherein the heating circuit extending from the switch-over valve ( 13 ) through the engine coolant heat exchanger ( 27 ) is connected to the upstream end of the first heat exchanger ( 14 ) so that the refrigerant is returned to the refrigerant compressor via the first heat exchanger ( 14 ), the second heat exchanger ( 15 ) and the third heat exchanger ( 5 ).
9. The air conditioning system as claimed in claim 8 , wherein a bypass line is disposed at the upstream end of the second beat exchanger ( 15 ) and provided with a second switch over valve ( 21 ) such that the refrigerant in the heating circuit can selectively bypass the first heat exchanger ( 14 ).
10. The air conditioning system as claimed in claim 1 , wherein a refrigerant-coolant heat exchanger ( 18 ) is arranged downstream of the second expansion device ( 17 ) and a bypass line with a valve ( 26 ) is provided so as to bypass the second expansion device ( 17 ) and the refrigerant-coolant heat exchanger ( 18 ).