| 摘要 |
PURPOSE:To save an electric power and improve the durability of a heater in an internal combustion engine, by forming PTC heater electrodes of a heat riser part in an intake air supply line into two systems and allowing the PTC heater to variably control its conduction area of electric current in accordance with an operating condition of the engine. CONSTITUTION:In a curved portion of an intake air supply line 1, a hole 11 of round shape is provided on a pipe wall 10 that constructs the line 1, and to said hole 11 an intake air heater A is mounted to construct a heat rise part. The heater A is constituted by a heating plate 2 of the cover consisting of thin plate of rolled steel, heat generating unit 4, electrode plate 5 and a support substance 3 that supports to clamp the heat generating unit 4 and the electrode plate 5. The above described heat generating unit 4 is formed by using a PTC heater with a positive resistance- temperature characteristic having a Curie point at a specific temperature, and on its bottom face two-system of electrode surfaces 6a, 6b intruding to each other in a comb pattern are formed. The electrode surface 6b is constituted in such a manner as to be controlled to conduct an electric current by a water temperature switch S2. |
