An ironing appliance with means for controlling the heating power

Abstract

The present application relates to an ironing appliance comprising a soleplate ( 10 ), a heating element ( 20 ) for heating the soleplate ( 20 ), a controller ( 30 ) for controlling the heating power of the heating element ( 20 ), a temperature sensor ( 40 ) for sensing a temperature of the soleplate ( 10 ). The controller ( 30 ) is adapted to determine a temperature gradient of the soleplate ( 10 ) as a rate of change of the temperature of the soleplate over time, and a temperature difference between the temperature of the soleplate ( 10 ) and a first predetermined temperature (T 1 ). The controller ( 30 ) is adapted to control the heating power of the heating element ( 20 ) based on the temperature gradient and the temperature difference. This solution allows that the soleplate can be heated in a way that minimises overshoot and undershoot of temperature.

1 . An ironing appliance comprising:
 a soleplate;   a heating element for heating the soleplate;   a temperature sensor for sensing a temperature of the soleplate;   a controller for:
 a) determining a temperature gradient of the soleplate as a rate of change of the temperature of the soleplate over time, and a temperature difference between said temperature of the soleplate and a first predetermined temperature (T 1 ), 
 b) controlling the heating power of the heating element based on said temperature gradient and said temperature difference; 
 wherein the controller is arranged to control the heating element to use a first heating power when temperature of the soleplate is less than a second predetermined temperature (T 2 ) that is lower than the first predetermined temperature (T 1 ), and to control the heating power of the heating element based on said temperature gradient and said temperature difference when the temperature of the soleplate is between the second predetermined temperature (T 2 ) and the first predetermined temperature (T 1 ); and 
 wherein, if said temperature gradient is positive, the controller is arranged to control the heating power of the heating element so that the heating power decreases for increasing values of the temperature of the soleplate from the second predetermined temperature (T 2 ) to the first predetermined temperature (T 1 ), wherein this decrease in heating power is larger for larger positive temperature gradients. 
   
     
     
         2 . An ironing appliance according to  claim 1 , wherein the controller is arranged to control the heating power of the heating element by varying the time duration the heating element is turned on in a given time period with a constant electrical power supplied to the heating element. 
     
     
         3 . An ironing appliance according to  claim 1 , wherein the controller is arranged to control the heating power of the heating element by varying the electrical power supplied to the heating element. 
     
     
         4 . (canceled) 
     
     
         5 . An ironing appliance according to  claim 1 , wherein the first heating power is a maximum heating power. 
     
     
         6 . (canceled) 
     
     
         7 . An ironing appliance according to  claim 5 , wherein, if said temperature gradient is negative, the controller is arranged to control the heating power of the heating element so that the heating power decreases for increasing values of the temperature of the soleplate from the second predetermined temperature (T 2 ) to the first predetermined temperature (T 1 ), wherein this decrease in heating power is larger for smaller negative temperature gradients. 
     
     
         8 . An ironing appliance according to  claim 1 , wherein the controller is arranged to control the heating power of the heating element based on said temperature gradient and said temperature difference when the temperature of the soleplate is between the first predetermined temperature (T 1 ) and a third predetermined temperature (T 3 ) that is higher than the first predetermined temperature (T 1 ). 
     
     
         9 . An ironing appliance according to  claim 8  wherein, if said temperature gradient is positive, the controller is arranged to control the heating power of the heating element so that the heating power is off as the temperature of the soleplate decreases from the third predetermined temperature (T 3 ) to the first predetermined temperature (T 1 ). 
     
     
         10 . An ironing appliance according to  claim 8 , wherein, if said temperature gradient is negative, the controller is arranged to control the heating power of the heating element so that the heating power increases for decreasing values of the temperature of the soleplate from the third predetermined temperature (T 3 ) to the first predetermined temperature (T 1 ), wherein this increase in heating power is larger for larger negative temperature gradients. 
     
     
         11 . An ironing appliance according to  claim 8 , wherein the controller is arranged to control the heating element so that the heating power is off if the temperature of the soleplate is above the third predetermined temperature (T 3 ). 
     
     
         12 . An ironing appliance according to  claim 1 , further comprising a memory to store a look up table containing values of heating powers at different combinations of temperature differences between the sole plate and the first predetermined temperate and the temperature gradient of the sole plate, the controller being arranged to use said values in the look up table to control the heating power of the heating element. 
     
     
         13 . A method of controlling an ironing appliance comprising a soleplate and a heating element for heating the soleplate, the method comprising the steps of:
 determining (S 10 ) a temperature gradient of the soleplate as a rate of change of the temperature of the soleplate over time and determining (S 20 ) a temperature difference between the temperature of the soleplate and a first predetermined temperature (T 1 ); and   controlling (S 30 ) the heating power of the heating element based on said temperature gradient and said temperature difference;   wherein the controlling the heating power of the heating element comprises using a first heating power when temperature of the soleplate is less than a second predetermined temperature (T 2 ) that is lower than the first predetermined temperature (T 1 ), and controlling the heating power of the heating element based on said temperature gradient and said temperature difference when the temperature of the soleplate is between the second predetermined temperature (T 2 ) and the first predetermined temperature (T 1 ); and   wherein, if said temperature gradient is positive, the controlling the heating power of the heating element comprises controlling the heating power of the heating element so that the heating power decreases for increasing values of the temperature of the soleplate from the second predetermined temperature (T 2 ) to the first predetermined temperature (T 1 ), wherein this decrease in heating power is larger for larger positive temperature gradients.