WastegateA wastegate is a valve that diverts exhaust gases away from the turbine wheel in a turbocharged engine system. 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, to protect the engine and the turbocharger. The wastegate is controlled by a wastegate actuator. Different Types of WastegatesInternal An internally gated turbocharger. The internal gate is located to the right of the turbine wheel, but built into the turbine housing. Partially seen at the top is the wastegate actuator arm. 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. A flapper valve is generally used by internal wastegates. External An external wastegate is a separate self-contained mechanism typically used with turbochargers that do not 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. External wastegates can be much larger since there is no constraint of integrating the valve or spring into the turbocharger and turbine housing. It is possible to use an external wastegate with an internally gated turbocharger, though this generally involves welding the internal wastegate shut to avoid unwanted leaks. External wastegates generally use a valve similar to the poppet valve found in the cylinder head. However they are controlled by pneumatics rather than a camshaft and open in the opposite direction. External wastegates can also use a butterfly valve, though that is far more rare. |
| Document statistics: Last modified on 2006-12-17 15:28:26 by cc8balla |