Control for supercharger turbines

A waste gate control for an engine turbosupercharger having a turbine driven by gases exhausted from the engine to operate a compressor for supplying induction air to the engine through a throttle valve, said control comprising

• a first passage for bypassing exhaust gases around the turbine,
• first valve means in said first passage for controlling fluid flow therethrough,
• means normally biasing said first valve means toward a closed position,
• means for operating to force said first valve means to an open position in response to the induction pressure exceeding a first predetermined magnitude and the induction pressure falling below a second predetermined magnitude lower than said first predetermined magnitude,
• a second passage connecting the outlet of the compressor to the inlet thereof around the compressor,
• second valve means in said second passage for controlling fluid flow therethrough,
• means normally biasing said second valve means toward a closed position,
• means for operating to force said second valve means to an open position in response to the induction pressure prevailing downstream of the throttle valve exceeding said first predetermined magnitude and the induction pressure falling below said second predetermined magnitude, and
• said means to open said first valve means comprising a first controller operatively responsive to the induction pressure for producing first, second and third pressure signals when the induction pressure exceeds said first predetermined magnitude, when the induction pressure falls below said second predetermined magnitude, and when the induction pressure is between said first and second predetermined magnitudes, respectively,
• a second controller operatively responsive to the induction pressure for producing fourth and fifth pressure signals when the induction pressure exceeds said first predetermined magnitude and when the induction pressure falls below said second predetermined magnitude, respectively, and
• means operable in dependence on the pressure difference between the pressure signals produced by said first and second controller for moving said first valve means to an open position.

In an internal combustion engine having a turbosupercharger which includes a turbine driven by hot exhaust gases exhausted from said engine and a compressor driven by said turbine for supplying induction air under pressure via a throttle valve into the induction manifold of said engine, a waste gate having a control system comprising

• a turbine bypass passage which by bypasses the hot exhaust gases around said turbine;
• a valve disposed in said bypass passage for controlling the fluid flow through said passage,
• a first pressure differentially operated motor which is operatively connected to said valve for operating same, said motor having first and second variable volume chambers sealingly divided by a flexible diaphragm;
• biasing means for biasing said valve toward a closed position;
• a first controller which controls the pressure in said first variable volume chamber, said first controller having a first port which provides fluid communication between the atmosphere and said first variable volume chamber, a second port which provides fluid communication between said first variable volume chamber and the induction manifold downstream of the throttle valve, and a second pressure differentially operated motor which is operated by a pressure signal fed thereto from said induction manifold downstream of said throttle valve for positioning a first valve element to block said first port when fed a predetermined vacuum, for positioning said first valve element to block said second port when fed a predetermined positive pressure, and for positioning said first valve element such that said first and second ports are partially or fully open when fed a pressure between said predetermined vacuum and positive pressure;
• and
• a second controller which controls the pressure in said second variable volume chamber, said second controller having a third port which provides fluid communication between said second variable volume chamber and the atmosphere, a fourth port which provides fluid communication between said second variable volume chamber and the induction manifold downstream of the throttle valve, and a second valve element operative for normally permitting fluid communication between said fourth port and said second variable volume chamber and for moving to permit exclusive communication between said third atmospheric port and said second variable volume chamber when said predetermined vacuum prevails at said fourth induction port.