Abstract: A linkage mechanism for linking for example actuator rods to the nozzle ring of a variable geometry turbine. First and second components of the mechanism are interconnected by at least two links which are displaceable in a predetermined direction relative to the first component and connected at spaced apart locations to the second component. At least one of the links incorporates an element which is pivotal relative to the first component about a first axes and pivotal relative to the second component about a second axis, the two axis being parallel to each other, parallel to the predetermined direction, and offset relative to each other.

Abstract: A variable geometry turbine in which an inlet passageway has a movable wall the position of which is adjusted to match the turbine characteristics to the flow rate through the turbine. Nozzle vanes extend through the movable wall and are mounted on a nozzle support which is normally stationary so that the nozzles contact the facing wall of the inlet passageway. The nozzle support is arranged to move with the movable wall however when the movable wall opens the inlet passageway beyond a predetermined extent so that the nozzle vanes are at least partially retracted when the movable wall is in the fully open position.

Abstract: A pneumatic control system for the variable area turbine inlet of a turbocharger of an internal combustion engine. The variable turbine inlet is actuated by a pneumatic actuator having a first connection to compressor boost pressure and a second connection to turbine inlet pressure. The actuator increases turbine inlet area in response to an increase in pressure and a one way valve in the compressor boost connection causes the actuator pressure to be the higher of compressor boost or turbine inlet pressure. As a result, turbine pumping losses during high engine rpm low power conditions are minimized.

Abstract: The disclosure illustrates a self calibrating control system for a variable area turbocharger incorporating a pneumatic actuator having a limiting position achieved at low actuating pressure levels. The calibration takes place by monitoring the demanded actuator signal. If it stays at a level reflecting a physically limiting position of the actuator for a predetermined time air pressure to the actuator is terminated to positively maintain the actuator in the no air position. A signal reflecting the actual position of the actuator is then substituted in the control system as a new zero pressure condition. This procedure is performed periodically and is aborted if normal control inputs are demanded thus resulting in a minimum disruption to normal control inputs. In addition the system provides for fault indications if the calibration procedure fails to result in a zero pressure calibration within predetermined limits.