| 摘要 |
The invention concerns an air-conditioning unit which is intended for motor vehicles, in particular for passenger cars, and which can be switched between cooling and heating. It has a coolant circuit with a compressor 2 driven by the vehicle engine 1, a condenser 3, an expansion valve 4 and an evaporator 5. A four-way valve 6 for changing the direction of flow of the coolant is arranged between the compressor 2 on one side and the evaporator 5 and condenser 3 on the other side. Between the condenser 3 and the evaporator 5 there are two parallel lines, of which one contains the expansion valve 4 and a check valve 7 opening towards the evaporator 5, while the other contains a check valve 10, opening towards the condenser 3, and an arrangement 8 which, when the unit is in heating mode, conveys coolant away from the evaporator 5 to the condenser 3. The inlet side and outlet side of the condenser 3 are connected to each other via a short-circuiting line 14 which contains a further valve 151. The object of the invention is to improve the above-mentioned air-conditioning unit. This object is achieved by the fact that the further valve 151 is in the form of a directional valve which is controlled (pressure sensor 16) as a function of the pressure in the evaporator 5 and is set to its locking position when this pressure exceeds a predetermined value. In this way, the heat developed in the condenser 3 is reduced. <IMAGE> |
