Device for preventing the turbo-charger from over-running

摘要

A device for preventing the turbo-charger from over-running, wherein an actuator is arranged in a by-pass bypassing a turbine of the turbo-charger and operates a waste gate valve. The actuator has a positive pressure chamber communicated, via a boost pipe, with an intake air passage downstream of a compressor and a negative pressure chamber communicated with a source of negative pressure via a negative pressure pipe. The negative pressure chamber is so constituted as to be supplied with a negative pressure to have a target pressure that is set relative to the atmospheric pressure.