Throttle valve positioner

摘要

A vacuum control valve is actuated by a vacuum created in the intake passage of an internal combustion engine for directly controlling on-off of a vacuum circuit thereby energizing or deenergizing a throttle valve positioner diaphragm device which controls motion of the throttle valve so as not to be abruptly urged in a closing direction. A first vacuum bleed port is connected by a conduit to a diaphragm chamber in the throttle valve positioner diaphragm device through an orifice and is located downstream relative to the throttle valve during rotation of the engine at an idling speed. A rod is connected to the diaphragm in the throttle valve positioner diaphragm device to restrict swinging movement of the throttle valve in the closing direction. The vacuum control valve is disposed in a conduit branched from the conduit connecting the first vacuum bleed port to the orifice and has a port which can communicate with the atmosphere. The vacuum control valve is actuated by a vacuum applied from a second vacuum bleed port located always downstream relative to the throttle valve. The vacuum control valve permits admission of air at the atmospheric pressure into the conduit leading to the diaphragm chamber in the throttle valve positioner diaphragm device thereby inhibiting swinging movement of the throttle valve in the closing direction, when the absolute value of the vacuum in the intake passage exceeds a predetermined setting.