Abstract: An apparatus for providing an antisurge operating mode for a turbocharged engine may include a processor. The processor may be configured to receive indications of engine operating parameters and engine accelerator pedal position, determine whether the received indications correspond to antisurge mode activation conditions, and, in response to a determination that the received indications correspond to antisurge mode activation conditions, initiate control of selected engine components by directing the selected engine components to operate based on stored engine operating parameters recorded a predetermined time prior to the determination.

Abstract: A turbocharger with an exhaust gas-driven turbine includes a variable nozzle formed by a stator supporting fixed vanes and defining bypass openings, and a rotor supporting movable vanes and defining bypass channels. Each fixed vane overlaps with a movable vane by a varying extent dependent on rotational position of the rotor. In a fully open position of the rotor, the movable vanes have a maximum extent of overlap with the fixed vanes, and the bypass channels align with the bypass openings so that some of the exhaust gas flows through the aligned bypass openings and channels, bypassing the turbine wheel.

Abstract: A turbine assembly for a turbocharger includes a variable nozzle formed by a sliding half-collar piston. A first-stage nozzle has a plurality of first vanes supported by a first nozzle ring and extending axially therefrom. A second-stage nozzle has a second nozzle ring connected to the ends of the first vanes, and a plurality of second vanes extending axially therefrom. The piston regulates flow through the second-stage nozzle, while the first-stage nozzle remains open when the piston is fully closed. The second nozzle ring at least partially divides the first vanes from the second vanes. The half-collar piston includes recesses that receive the second vanes and only partially surround the girth of each second vane.

Abstract: A turbine assembly for a variable-geometry turbocharger includes a turbine housing defining a divided volute having first and second scrolls, wherein the first scroll has a substantially smaller volume than the second scroll. The first scroll feeds exhaust gas to a first portion of a turbine wheel upstream of the throat of the wheel, while the second scroll feeds gas to a second portion of the wheel at least part of which is downstream of the throat. Flow from the second scroll is regulated by a sliding piston. The first scroll can be optimized for low-flow conditions such that the turbocharger can operate effectively like a small fixed-geometry turbocharger when the piston is closed. The turbine housing defines an inlet that is divided by a dividing wall into two portions respectively feeding gas to the two scrolls, a leading edge of the dividing wall being downstream of the inlet mouth.

Abstract: A turbocharger having a sliding piston for regulating exhaust gas flow into the turbine wheel includes a set of fixed vanes mounted on a fixed first wall of the turbine nozzle and projecting axially toward an opposite second wall of the nozzle, and a set of moving vanes mounted on the end of the piston and projecting in an opposite axial direction toward the first wall of the nozzle. The two sets of vanes are circumferentially staggered relative to each other and overlap each other, the degree of overlap depending on the piston's axial position. The turbine wheel can be a splittered turbine wheel having long blades alternating with shorter blades.