Electric heating device for a vehicle

Abstract

A heating device has PTC heating thermistors connected in groups, and a circuit for selectively turning on one or more groups. At least two of the groups have different rated heating powers. The circuit turns on the selection of the groups at least on the basis of the available electrical power. A method for electrically heating a vehicle is also disclosed.

1 . An electrical heating device, in particular a PTC heating device, for a vehicle, having a plurality of heating resistors, in particular PTC heating thermistors, which are connected in groups, and having a circuit by means of which one or more groups can be turned on selectively, wherein the circuit turns on a selection of the groups at least on the basis of the available electrical power.  
     
     
         2 . The device of  claim 1 , wherein at least two of the groups have different rated heating powers.  
     
     
         3 . The device of  claim 1  or  2 , wherein the group with the lowest rated heating power provides a temperature increase, for the medium to be heated up, in the operating range.  
     
     
         4 . The device of  claim 1 , wherein the maximum difference in rated heating power between at least two groups provides a temperature increase, for the medium to be heated up, of at most 1 kelvin in the operating range.  
     
     
         5 . The device of  claim 1 , wherein the selection provides a total rated heating power graduation, in particular with an increment which corresponds to a temperature increase, for the medium to be heated up, of at most 1 kelvin in the operating range.  
     
     
         6 . The device of  claim 1 , wherein the rated heating power of at least one group substantially satisfies the following equation: 
         P   n   =P   1 +( n −1)× P   1   
       where, in a series of groups with different rated heating power in order of increasing heating power, n denotes a group.  
     
     
         7 . The device of  claim 1 , wherein the rated heating power of at least one group substantially satisfies the following equation: 
         P   n =2 (n−1)   ×P   1   
       where, in a series of groups with different rated heating power in order of increasing heating power, n denotes a group.  
     
     
         8 . A method for electrically heating a vehicle by using electrical heating elements, in particular PTC heating elements, which are connected in groups, with the step of turning on one or more groups, wherein the said step of turning-on is carried out in relation to a selection of groups, at least on the basis of the available power.  
     
     
         9 . The method of  claim 8 , wherein at least two groups have different rated heating powers.  
     
     
         10 . The method of  claim 8 , wherein the device of claims  1  is used.  
     
     
         11 . The method of  claim 8 , wherein the step of turning-on is carried out on the basis of signals provided by sensors and/or of user-setting signals.