Vehicle air conditioning system with unidirectional fluid flow in heating and cooling modes - has valve to direct flow to outer heat-exchanger for cooling and to inner heat exchangers for heating

摘要

The output from the compressor (31) is switched by the control valve (32) either to the outside heat exchanger (38) or direct to the first of the internal heat exchangers (33). The outlet of the outer heat exchanger has a non-return valve (70) to connect to the first inner heat-exchanger. A pressure reduction valve (34) is set between the two inner heat-exchangers with the second heat-exchanger (35) feeding the pump inlet. Switching the control valve selects cooling or heating without changing the fluid flow direction. A blower (37) upstream of the inner heat-exchangers controls the airflow. Heat sensors spaced about the system, and a selector control, are connected to a control unit (43) for a simple control. For enhanced heating effect part of the airflow can be recycled (50) to the front of the blower. ADVANTAGE - No risk of icing the heat exchangers, no defrost facility required, simple valve control.