Turbocharger with divided turbine housing and annular rotary bypass valve for the turbine

Abstract

The invention provides a turbocharger with a divided turbine housing and an annular rotary bypass valve for a turbine. The turbocharger includes a turbine wheel mounted within a turbine housing and connected to a compressor wheel by a shaft. The turbine housing defines an exhaust gas inlet connected to a divided volute that surrounds the turbine wheel, and an axial bore through which exhaust gas that has passed through the turbine wheel is discharged from the turbine housing. The turbine housing further defines a pair of concentric annular bypass passages surrounding the bore and arranged to allow exhaust gas to bypass the turbine wheel as two separate bypass streams. An annular bypass valve is disposed in the bypass passage. The bypass valve comprises a fixed annular valve seat and a rotary annular valve member arranged coaxially with the valve seat. The valve member is disposed against the valve seat and is rotatable about the axis for selectively varying a degree of alignment between respective orifices in the valve seat and valve member.

Description

[0001] Cross References to Related Applications [0002] This application is related to U.S. Patent Application Serial No. 12 / 611,816, filed November 3, 2009, and U.S. Patent Application Serial No. 12 / 711,434, filed April 30, 2010, the entire contents of which are hereby incorporated by reference incorporated into this article. technical field [0003] The present disclosure relates to an exhaust driven turbocharger having a split turbine housing for two independent exhaust streams supplied to the turbine. The present disclosure more particularly relates to bypass devices that allow exhaust gas to bypass a turbine under certain engine operating conditions. Background technique [0004] In a conventional turbocharger, the turbine housing defines a bypass duct, usually on the side of the main bore through the housing, and the bypass duct is connected via a bypass valve to the exhaust inlet or to the volute of the housing . Bypass valves are typically rotary or poppet type v...

AI Technical Summary

Problems solved by technology

One disadvantage associated with this arrangement is that it is difficult to fully seal the valve in the closed position as air pressure tends to open the valve

Leakage through a closed bypass valve is the cause of a reduction in the performance of the turbine and thus the turbocharger and its associated engine

A typical solution to the leakage problem is to preload the bypass valve member against the valve seat, but this often does not completely eliminate the leakage and in any case it leads to additional problems such as an increase in the actuation force required to open the valve

[0005] In addition, rotary or poppet valves tend to be poor in controllability, especially in the crack-open position, and in general, bypass flow rate is highly non-linear with valve position, making proper adjustment of bypass Throughflow rate is very difficult

This leads to problems such as poor transient response of turbochargers and engine systems

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