Electric heating device

Abstract

An electric heating device includes a main tube which includes multiple heating areas. Each heating area has a hating bar received therein to provide thermal energy to the liquid passing through the heating areas and to increase the temperature of the liquid. A control unit has multiple control members and each control member is electrically connected to and controls one of the heating bars. Each of the control members has a heat dissipating tube connected thereto. The multiple heating areas are cooperated respective heating bars to increase the contact areas between the liquid and the heating bars to quickly increase the temperature of the liquid.

What is claimed is: 
     
         1 . An electric heating device comprising:
 a heating unit having a main tube which has an inlet and an exit, multiple heating areas formed between the inlet and the exit of the main tube, each heating area having a hating bar received therein and a spiral path defined in each heating area, a first temperature sensing member connected to the main tube and located close to the inlet; and   a control unit having a circuit board which has multiple control members electrically connected thereto, each of the control members electrically connected to and controlling one of the heating bars, each of the control members having a heat dissipating tube connected thereto which is connected between the inlet of the main tube and a fluid switch, the fluid switch electrically connected to the circuit board.   
     
     
         2 . The device as claimed in  claim 1 , wherein the heating areas are located in parallel to each other, and the heating bars are located in parallel to each other. 
     
     
         3 . The device as claimed in  claim 2 , wherein an output power of each of the heating bar is gradually reduced from the heating bar located close to the inlet of the main tube toward the heating bar located close to the exit when total output power of all of the heating bars is not changed. 
     
     
         4 . The device as claimed in  claim 1 , wherein a second temperature sensing member is connected to the main tube and located close to the exit, the second temperature sensing member is electrically connected to the control unit. 
     
     
         5 . The device as claimed in  claim 1 , wherein the control members are triacs. 
     
     
         6 . The device as claimed in  claim 1 , wherein the control members are threadedly connected to the heat dissipating tube. 
     
     
         7 . The device as claimed in  claim 1 , wherein the control unit is an electronic control unit.