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A 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 in which the actuator is controlled by pressure coming from the intake manifold. These water valves are operated by handles. ...
Automobile exhaust Exhaust gas is flue gas which occurs as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel, fuel oil or coal. ...
A Siemens steam turbine with the case opened. ...
Turbocharger Cut-away A turbocharger is a device used in internal-combustion engines to increase the power output of the engine by increasing the mass of oxygen and fuel entering the engine. ...
A Siemens steam turbine with the case opened. ...
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ...
Wastegate types
Internal
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. Image File history File links Metadata No higher resolution available. ...
Image File history File links Metadata No higher resolution available. ...
On left, an example external wastegate. Partially visible is the shaft of the poppet valve built into the wastegate. The port on top of this wastegate is a secondary control port. Not visible is the primary control port. Image File history File links No higher resolution available. ...
Image File history File links No higher resolution available. ...
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ...
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. Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. ...
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. A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. ...
The cylinder head from a GMC van. ...
Table of Pneumaticks, 1728 Cyclopaedia This article is about the tool. ...
For the fictional characters of the same name, see Camshaft (Transformers). ...
A butterfly valve is a type of flow control device, typically used to regulate a fluid flowing through a section of pipe. ...
Atmospheric/divorced wastegates A "divorced" wastegate dumps the gases directly into the atmosphere, instead of returning them with the rest of an engine's exhaust. This is done to prevent turbulence to the exhaust flow and reduce total back pressure in the exhaust system. Divorced wastegate dumper pipes are commonly referred to as "screamer pipes" due to the unmuffled waste exhaust gasses and the associated loud noises they produce. Backpressure usually refers to the pressure exerted on a moving fluid by obstructions or tight bends in the confinement vessel along which it is moving, such as piping or air vents, against its direction of flow. ...
Internal gates cannot generally be vented to the atmosphere because the internal wastegate port and turbine exducer are built into the same housing. Occasionally an exhaust downpipe for an internally gated turbocharger will be called 'divorced' because it integrates two tubes where one is intended for the wastegate only. It should be noted that it is difficult to truly separate the exhaust flow of the turbine and wastegate. Thus, internal wastegate turbos will rarely if ever feature an external dump.
Control
Pneumatic The simplest control for a wastegate is to supply boost pressure directly from the charge air side to the wastegate actuator. A small hose can connect from the turbocharger compressor outlet, charge pipes, or intake manifold to the nipple on the wastegate actuator. The wastegate will open further as the boost pressure pushes against the force of the spring in the wastegate actuator until equilibrium is obtained. More intelligent control can be added by integrating an electronic boost controller. Helical or coil springs designed for tension A spring is a flexible elastic object used to store mechanical energy. ...
A standard definition of mechanical equilibrium is: A system is in mechanical equilibrium when the sum of the forces, and torque, on each particle of the system is zero. ...
A boost controller is a device in a turbocharged or supercharged car that regulates boost pressure. ...
Standard wastegates have one port for attaching the boost control line from the charge air supply line or boost control solenoid. This is the most common configuration and the only type of configuration found on internal wastegates.
A dual port Tial 44mm wastegate. The side port is the primary port. The top port is the secondary port and not necessary for proper operation. A dual port wastegate adds a second port on the opposite side of the actuator. Air pressure allowed to enter this second port aids the spring to push harder in the direction of closing the wastegate. This is exactly the opposite of the first port. The ability to help the wastegate remain closed as boost pressure builds can be increased. This also adds further complexity to boost control, requiring more control ports on the solenoid or possibly a complete second boost control system with its own separate solenoid. Use of the second port is not necessary. Secondary ports, unlike primary ports, cannot be simply attached to a boost control line and require electronic control to be useful. Image File history File links Metadata No higher resolution available. ...
Image File history File links Metadata No higher resolution available. ...
Hydraulic systems for aircraft Most turbocharged aircraft use a hydraulic wastegate control with engine oil as the fluid. Modern systems from Lycoming and Continental operate on the same principles and use similar parts which differ only in name. Inside the wastegate actuator, a spring acts to open the wastegate, and oil pressure acts to close the wastegate. On the oil output side of the wastegate actuator sits the density controller, an air-controlled oil valve which senses upper deck pressure and controls how fast oil can bleed from the wastegate actuator back to the engine. As the aircraft climbs and the air density drops, the density controller slowly closes the valve and traps more oil in the wastegate actuator, closing the wastegate in order to increase the speed of the turbocharger and maintain rated power. Some systems also use a differential pressure controller which senses the air pressures on either side of the throttle plate and acts to maintain an optimum balance between a low turbocharger workload and a quick spool-up time. Lycoming Engines is a major aircraft engine company, known primarily for their smaller general aviation engines. ...
Continental Motors is a corporation in Mobile, Alabama, USA, that produces aircraft engines. ...
Wastegate chatter myth There is a common myth in the automotive world about so called "wastegate chatter" or "turbo flutter", a noise created on lifting off the throttle in a turbocharged car. The sound is commonly described as a chipmunk or a rattlesnake and is often stated incorrectly as being a result of the turbo's wastegate closing.
The noise is in fact the air compressed by the turbo passing back through the compressor wheel of the turbo after the airflow is abruptly halted by the throttle plate closing. However, in some cases, i.e. where it doesn't open fast enough or is set up to only react to high boost, some chatter will remain. Surge can occur on diesels when the turbo is attempting to pressurize the air at a higher pressure ratio than the compressor wheel can flow at a given speed. Diesels have no use for a Blow off Valve as they do not have a throttle. Dump valves are fitted to the engines of (usually older) turbo charged cars and sit between the turbo outlet and the throttle body. ...
The chatter noise is very noticeable on WRC Rally cars, where no BOV is allowed.
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