Wastegate
Encyclopedia : W : WA : WAS : Wastegate
A wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharger. Diversion of exhaust gases causes the turbine to lose speed, which in turn reduces the rotating speed of the compressor. The primary function of the wastegate is to stabilize boost pressure in turbocharger systems. The wastegate is controlled by a wastegate actuator.
Contents
Wastegate types
Internal
An internal wastegate is an integral part of the turbine housing. The wastegate actuator is commonly attached to the compressor housing with a metal bracket.External
An external wastegate is a separate self-contained mechanism designed for turbochargers that don't have internal wastegates. An external wastegate requires a specially constructed turbo manifold with a dedicated runner going to the wastegate. The external wastegate may be part of the exhaust housing itself. External wastegates are commonly used for regulating boost levels more precisely than internal wastegates in high power applications, where high boost levels can be achieved.Atmospheric/Divorced Wastegates
These terms refer to the handling of the gases after they leave the wastegate, instead of the wastegate mechanism itself. A divorced wastegate dumps the gases directly into the atmosphere, instead of returning it with the rest of an engine's exhaust. This is done to prevent turbulence to the exhaust flow. 'Divorced' wastegate dumper pipes are commonly referred to as Screamer Pipes due to the unmuffled waste exhaust gasses and the associated loud noises they produceWastegate Chatter Myth
There is a common myth in the automotive world about so called "wastegate chatter", a noise created on lifting off the throttle in a turbocharged car. The sound is commonly described as a chipmunk or a rattlesnake. This sound is in fact caused by a component callled a blowoff valve (BOV) malfunctioning or being incorrectly setup. The BOV releases the excess pressure (from turbocharging/supercharging) between the throttle flap and the turbo when the throttle closes. However when this volume of air is too large the BOV cannot release it all and the pressure is vented back through the compressor turbine. As the air passes back through the turbine the pressure wave is "chopped" by the still spinning turbine creating the fluttering sound that is commonly termed wastegate chatter.See also
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.