Balbes писал(а):с 2004 - WGT - waste gate actuator;
с 2006 - VGT - Vane control actuator;
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Все же расшифровка VGT от
Татарина более верная:
Variable Geometry Turbocharger.
Vane control actuator является частью VGT, Waste Gate Actuator является частью WGT (см. иллюстрации ниже):
Немного теории по VGT, прошу прощения, что по-английски:
VGT - General
Boost pressure governing is used to control an exhaust turbocharger with Waste-gate as well as a turbocharger with Variable Geometry Turbine (VGT) or Variable Nozzle Turbine (VNT).
For governing an exhaust turbocharger with Waste gate, the actuator is a bypass valve through which the exhaust flow is directed to or past the turbine as mentioned in turbocharger control.
But for governing a VGT turbocharger, the actuator which is activated by ECM PWM (Pulse With Modulation) control is the variable geometry turbine.
Boost pressure governing in VGT system is subdivided into recognition of driving style, setpoint value calculation which is mainly considered by the boost pressure with fuel quantity and shut off condition.
VGT - Operating Principles
Today’s diesel customers demand engines with excellent transient response, high torque backup and maximum fuel economy at all operating points. Large, high flow turbines allow for high positive energy and good fuel economy at high engine speeds, but typically have sluggish transient response and cannot provide as much low-end torque as a turbocharger with a low flow turbine. Technically it is called as “Turbo Lag”.
To counteract this turbo lag, VGT (Variable Geometry Turbine) technology is the ideal solution to what has traditionally been a large compromise. The VGT uses a set of adjustable vanes, or nozzles, to direct flow into the turbocharger turbine. When the vanes are closed, flow is directed tangentially into the turbine wheel. This imparts maximum energy into the turbine, causing the turbocharger to spin faster.
VGT - Operating principles
Conversely, when the vanes are opened, they direct flow into the turbine in a more radial direction. This reduces the angular momentum of the flow going into the wheel, producing less turbine work and ultimately slowing down the turbocharger.
Therefore, at high engine speeds, the vanes can be opened and at low engine speeds, the vanes can be closed.
VGT turbochargers make the best use of exhaust gas flow by contacting the vanes at the right angle, therefore, the theory of the variable geometry turbocharger is to optimize the angle of the vanes to suit the particular engine condition, as a result the optimum engine performance can be achieved.
The ECM is controlling a solenoid valve (duty ratio) to effect a vacuum on the actuator which in turn is connected to a linkage which pulls a rotating base plate. Inside the base plate are connected the vanes using a cam mechanism to determine the angle of vane pitch.
Добавлено: 06 ноя 2007, 01:14
думал, что это отличает только рестайл 
