Patent ID: 8113171

Claim:
An engine intake system comprising a throttle body ( 1 ) having a horizontal intake path ( 2 ), a butterfly type throttle valve ( 5 ) mounted on a valve shaft ( 5 a ) horizontally and rotatably supported by a bearing hole ( 4 ) of the throttle body ( 1 ), the throttle valve ( 5 ) opening and closing the intake path ( 2 ), and a sensor unit ( 16 ) formed by mounting a throttle sensor ( 18 ) and a negative pressure sensor ( 20 ) on a sensor housing ( 17 ) mounted on one side of the throttle body ( 1 ), the throttle sensor ( 18 ) detecting a degree of opening of the throttle valve ( 5 ), the negative pressure sensor ( 20 ) detecting an intake negative pressure of the intake path ( 2 ), and the intake path ( 2 ) and the negative pressure sensor ( 20 ) being connected via a negative pressure transmission path ( 35 ), characterized in that the negative pressure transmission path ( 35 ) is formed in a crank shape from a first passage ( 35 a ) having one end opening on a peripheral face of an upper half of the intake path ( 2 ) in proximity to a horizontal plane (H) containing an axis of the intake path ( 2 ), a groove-shaped second passage ( 35 b ) formed between mating faces of the throttle body ( 1 ) and the sensor housing ( 17 ) so as to extend while bending upward at substantially right angles from the other end of the first passage ( 35 a ), and a third passage ( 35 c ) formed in the throttle body ( 1 ) so as to extend from the upper end of the second passage ( 35 b ) in a direction opposite to the first passage ( 35 a ) and reach the negative pressure sensor ( 20 ).