Atmospheric pressure compensating means for an engine intake system

In an intake system for an internal combustion engine having intake passage means provided with throttle valve means therein, an atmospheric pressure compensating device comprising:

• a. air bypass passage means having one end communicating with the intake passage means on the downstream side of the throttle valve means and the other end communicating with the intake passage means on the upstream side of said throttle valve means,
• b. control valve means in said bypass passage means for controlling the air flow therethrough,
• c. said control valve means including a valve housing defining a valve chamber, and having a valve face and an air inlet, said valve chamber being in communication with said one end of said bypass passage means at said valve face and with said other end of said bypass passage means at said air inlet,
• d. a valve member arranged for sliding movement in said valve housing and having one end opposed to said valve face to control a clearance space between said valve face and said valve number one end in response to the pressure difference between the atmospheric pressure and suction pressure in said intake passage means so that said clearance is increased in response to a decrease in said pressure difference,
• e. spring means disposed in said valve housing for urging said valve member away from said valve face to increase said clearance.