Patent ID: 8740105

Claim:
A control device for an engine-independent heater that heats a liquid heat transfer medium of a heat transfer medium circuit especially for motor vehicles, the control device reducing a heating capacity of the heater when a current temperature gradient ((dT/dt) Ist ) of the heat transfer medium is equal to or greater than a temperature gradient threshold value ((dT/dt) schwell ), wherein the control device repeatedly recalculates the current temperature gradient ((dT/dt) Ist ) from heat transfer medium temperatures (θ Ist ) measured at different times, wherein the control device repeatedly recalculates the temperature gradient threshold value ((dT/dt) schwell ) dynamically as a function of a temperature difference (Δθ=θ soll −θ Ist ) between a target temperature (θ soll ) of the heat transfer medium that is to be achieved where the heat transfer medium temperature is measured and the current heat transfer medium temperature (θ Ist ), and wherein the temperature gradient threshold value ((dT/dt) schwell ) rises with increasing temperature difference Δθ=θ soll −θ Ist .