Electric recirculating air valves

Technology to prevent turbo lag

Information on the product

The electrically operated recirculating air valve offers an innovative solution for modern turbo engines by preventing sudden braking of the loader when the throttle valve is closed, significantly reducing the turbo lag. The direct electronic control eliminates pneumatic components such as vacuum reservoirs and non-return valves, which leads to a shortened switching process and improved response behaviour.

During operation, the valve causes a rapid drop in pressure in the charged air system, meaning that the compressor, the turbine impeller and the exhaust gas turbocharger are braked less sharply. This regulation supports optimum engine speed and increased torque in the vehicle, while the controlled air supply ensures constant piston operation and the exhaust gas flow is precisely regulated so that the exhaust gas also meets emission requirements and losses of power are avoided.

The optimised tuning in the engine speed range virtually eliminates the characteristic lag in the shifting process, further reducing the loads on the pistons and supporting engine operation.

The bypass valve prevents unnecessary braking of the turbocharger with sudden closing of the throttle valve, so clearly reducing the turbo lag effect.

Compared with existing pneumatic solutions the electric bypass valve is more compact, efficient and cost-effective: There is no need for pneumatic lines, a vacuum tank, non-return valve or electric air switching valve.

Direct actuation cuts switching times by as much as 70 percent, a particular benefit for sporty turbocharged engines with fast load alternation.

Function

If the accelerator is suddenly released at a high turbocharger speed (causing the throttle valve to close), a high back pressure is produced behind the compressor and is not able to escape. This has a strong braking effect on the compressor wheel, exposing the closed throttle valve and turbine side of the turbocharger to great loads.
When the throttle valve opens, the turbocharger first has to be brought back up to speed. This effect is known as turbo lag, i.e. a lack of power when accelerating after overrun operation.

The bypass valve will prevent this. It releases a bypass to the suction side in overrun, so ensuring a fast drop in pressure on the compressor side. This means that the braking effect on the compressor is not as strong. When the driver accelerates again, i.e. when the throttle valve opens, the recirculating air valve closes, and full boost pressure is immediately available again. This reduces turbo lag, which is now barely noticeable.

Pierburg has incorporated the electrically operated recirculating air valve into the turbocharger design, creating a highly complex component for new engine generations.