Watercooled Electronic Actuators for Garrett by Honeywell VNT Turbochargers
Downsizing of engines is happening in every sector of the motor industry, affecting all parts of the vehicle drivetrains and this of course includes turbos. One of the impacts of coaxing more and more power and torque out of ever smaller, higher efficiency engines is that temperatures around the engine are getting higher. With the addition of acoustic covers above and below engines, the ambient temperature around the turbocharger can now be as high as 180°C which means that special attention must paid to sensitive electrical components, as contained within our electronic actuators.
The maximum temperature allowed within an electronic actuator to avoid damaging components is around 140°C, so to ensure that this is not exceeded, increasingly, watercooling of the actuator is becoming necessary. The first of these watercooled actuators is already in production, on our GTD1449VK turbo as used by Mercedes Benz on their latest E220d model.
This uses a sUTA (Simple Universal Turbo Actuator) similar to the model illustrated below. It uses water in/out connections on the aluminium base of the actuator to connect to the vehicles cooling system. The use of an electric water circulating pump on the vehicle can also help to maintain safe temperatures, even during periods of hot shutdown, when internal actuator temperatures can reach their peak values. In this case the cooling system of the engine continues to run for a defined period after the engine is switched off.
The maximum water inlet temperature would be 110°, so ensuring the safety of the electronics. A further refinement of these new actuators is the capability to feedback not only positional information to the vehicle ECU (like with existing REA & SREA actuators), but also to feed back the actual temperature of the circuit board components within the actuator, to safeguard the electronics under all running or hot shutdown conditions.