Patent ID: 7174883

Claim:
An intake-negative-pressure-increasing apparatus for an engine comprising a bypass passage extending from an intake pipe portion in the neighborhood of the throttle valve to an intake pipe portion downstream of the intake pipe portion in the neighborhood of the throttle valve, wherein a negative pressure is generated by the air flowing through the bypass passage and is supplied to an actuator operated with the negative pressure as the driving power, and wherein at least one air inlet opening of the bypass passage open to the intake pipe portion in the neighborhood of the throttle valve is formed in the intake pipe in such a manner that as long as the opening degree of the throttle valve is within a specified range, a part of the air inlet opening is closed by the outer peripheral end surface of the throttle valve, and the area of the part of the air inlet opening not closed by the outer peripheral end surface of the throttle valve and kept open upstream of the throttle valve can be changed by adjusting the opening degree of the throttle valve.