Motor vehicle compartment temp. control - has electromagnetically controlled switching valves, whose flow cross=section is operated in stages

摘要

In the process the actual and rated temperatures are supplied to a control circuit which converts them into square pulses of constant frequency and variable width. These pulses form input signals for an electromagnetic servo-drive of a switching valve, controlling the flow volume of a heating medium. The entire flow cross section (5) of the valve (1) is opened or closed in stages, preferably in two steps. The switching valve may have two stop elements (7,8) of differing flow cross sections (5,6). The stop element (7) with the greater flow cross section (5) may form simultaneously the valve seat for the stop element (8) with the smaller flow cross section (6). It has flow ports (6') for the heating medium passage with the smaller cross section open. The two stop elements are typically actuated by spring-loaded solenoid armatures (9,10), movable by independent magnetic coils (15,16).