Operating method for an electric heater
AssigneeMahle International GmbH
InventorsNajim Belkaid, Guillaume Daudon, Jean-Francois Walter
Life of this patent
Estimating the term…
Abstract
An operating method for an electric heater may include heating a fluid passing the electric heater to an outlet temperature by at least one heating element and operating the electric heater in one of a normal mode or a protection mode. In the normal mode, the at least one heating element may be supplied with at least one of a direct current and a direct voltage. In the protection mode, electrical power supplied to the at least one heating element may be regulated by pulse width modulation. The electric heater may be operated in the normal mode if a reference temperature is less than or equal to a critical temperature and in the protection mode if the reference temperature is greater than the critical temperature.
Claims19
An operating method for an electric heater having at least one control unit with at least one temperature sensor measuring a reference temperature, and at least one heating element having a positive temperature coefficient mode above a critical temperature and a negative temperature coefficient mode below the critical temperature, the operating method comprising:
- heating a fluid passing the electric heater to an outlet temperature by the at least one heating element;
- operating the electric heater in one of a normal mode, in which the at least one heating element is supplied with at least one of a direct current and a direct voltage, or a protection mode, in which electrical power supplied to the at least one heating element is regulated by pulse width modulation;
- wherein the control unit compares the reference temperature with the critical temperature;
- wherein the electric heater is operated in the normal mode if the reference temperature is less than or equal to the critical temperature;
- wherein the electric heater is operated in the protection mode if the reference temperature is greater than the critical temperature;
- and
- wherein the critical temperature includes a temperature at which the heating element changes from the negative temperature coefficient mode to the positive temperature coefficient mode.
An electric heater comprising:
- at least one control unit with at least one temperature sensor measuring a reference temperature;
- and
- at least one heating element having a positive temperature coefficient mode above a critical temperature and a negative temperature coefficient mode below the critical temperature;
- wherein the control unit is at least one of formed, configured, and programmed to:
- compare the reference temperature with the critical temperature;
- operate the electric heater in a normal mode, in which the at least one heating element is supplied with at least one of a direct current and a direct voltage, if the reference temperature is less than or equal to the critical temperature;
- and
- operate the electric heater in a protection mode, in which electrical power supplied to the at least one heating element is regulated by pulse width modulation, if the reference temperature is greater than the critical temperature;
- and
- wherein the critical temperature includes a temperature at which the heating element changes from the negative temperature coefficient mode to the positive temperature coefficient mode.
An operating method for an electric heater having at least one control unit with at least one temperature sensor measuring a reference temperature, and at least one heating element having a positive temperature coefficient mode above a critical temperature and a negative temperature coefficient mode below the critical temperature, the operating method comprising:
- heating a fluid passing the electric heater to an outlet temperature by the at least one heating element;
- comparing, by the control unit, the reference temperature with the critical temperature, which is stored in the control unit;
- operating the electric heater in a normal mode, in which the at least one heating element is supplied with at least one of a direct current and a direct voltage, if the reference temperature is less than or equal to the critical temperature;
- operating the electric heater in a protection mode, in which electrical power supplied to the at least one heating element is regulated by pulse width modulation, if the reference temperature is greater than the critical temperature;
- and
- determining an electrical resistance of the at least one heating element while the electric heater is being operated in the protection mode;
- wherein the critical temperature includes a temperature at which the heating element changes from the negative temperature coefficient mode to the positive temperature coefficient mode.
Dependencies are inferred from the claim text.