| 摘要 |
[Objective] To provide a glow plug having a combustion pressure sensor whose accuracy in sensing combustion pressure is improved by preventing instantaneous, anomalous thermal expansion of a seal member (holding member) which is caused by combustion gas which rushes inward through an annular gap between the inner circumferential surface of the forward end of a housing and the outer circumferential surface of a heater projecting therefrom. [Means for Solution] A combustion gas prevention wall 67 extends radially outward on the outer circumferential surface of the heater 10 such that when the heater 10 is viewed rearward from its forward end 10a along the axial direction, the combustion gas prevention wall 67 closes an annular gap K1 at a position forward of the annular membrane portion 63 of the seal member 60. The combustion gas prevention wall 67 has an outer diameter D2 greater than the inner diameter D1 of the forward end 136 of the housing. Since combustion gas which rushes from the forward end 10a of the heater 10 toward the rear end thereof hits against the combustion gas prevention wall 67, it does not hit against the annular membrane portion 63. Therefore, it is possible to mitigate the phenomenon that the heater 10 is pushed axially forward as a result of anomalous thermal expansion of the annular membrane portion 63 as in a conventional glow plug. |
