Coolant circuit with a heater for a vehicle engine

Claim 1

A coolant circuit for a motor vehicle, comprising: an internal combustion engine; a coolant/air heat exchanger for heating an interior space of the motor vehicle; an independent heater generating heat by combustion, said heater including a combustion gas/coolant heat exchanger; a coolant circuit line connected to said internal combustion engine, said combustion gas/coolant heat exchanger and said heater; a bypass line, connected to said coolant circuit line and bypassing said internal combustion engine; and a thermostat valve connected to said coolant circuit line, downstream of said internal combustion engine, and connected to said bypass line for regulating a return temperature within a predetermined range of adjustment by controlling coolant flow through said bypass line and through said coolant circuit line, downstream of said internal combustion engine, said thermostat valve including a valve housing including two intake chambers and one discharge chamber, a valve piston formed of an expanding material element connected to two valve disks, said valve disks cooperating with valve seats to separate said intake chambers from said discharge chamber, adjusting means for moving the relative position of said valve seats with respect to said valve disks, said adjusting means being operable from the outside of said valve housing, at least one cooperating pair of said valve seats and said valve disks being shaped such that sealing of said at least one cooperating pair is independent of a change in relative position of the valve disk and the valve seat, over a range of relative movement of said valve seat with respect to said valve disks.