Load control on gasoline engines is normally performed by throttling the intake air. This function is enabled by throttle bodies, which simultaneously, can also carry out traditional functions such as idle speed control, travel speed control and anti-slip control.
Even today's modern direct-injection gasoline engines or engines with variable valve timing require throttle and/or control plates either for a more homogeneous mixture formation or for controlling residual gases. All these options for influencing intake airflow and the associated functions are achievable with the aid of electric motor-controlled ETC-E (drive-by-wire) systems. The ongoing optimization of these is reflected in today's fifth product generation.
Good position reproducibility allows EDR-E the possibility of reducing fuel consumption and emissions on gasoline engines. Today's diesel engines likewise require a control flap to assist in exhaust-gas recirculation.
Reduced engine displacements and the growing significance of heat management have given rise to many new applications for control flaps within the engine compartment. The expanding range of possibilities extends from simple bypass flaps to permanently coupled multi-path throttle bodies.
The D.C. motor with dual-stage gear is the basic concept for all throttle and control plates. Integrated position control, a redundant return system and diameter options from under 40 to 90 mm-these are some of the outstanding functions and features available to customers through this system.
On both gasoline and diesel engines there are very many control functions performed with the aid of path or angle adjustment. By adjusting the intake manifold flaps on variable- length manifolds or the actuation of air-swirl flaps for air control and cylinder charge fine-tuning electric actuators out of the Pierburg portfolio can be used.
Even in the exhaust gas system, flaps are increasingly used for emission reduction and acoustic fine-tuning. The work previously performed by vacuum actuators is increasingly being taken over by electric drive modules.
The rotation of the D.C. motor is converted by a gear unit into an angular position. This allows high actuating speeds and forces to be achieved. Depending on requirements, either spur or worm gears are used. A wide variety of modules-ranging from basic to "smart" actuators (EAM-I, through internal feedback permitting position control) ensures that all customer requirements can be met.
Self-calibration and self-diagnosis functions are standard features just as the facility to communicate with a BUS system. Depending on their location within the engine compartment, the housings are made from aluminum or plastic.
It is evident that the various market demands cannot be addressed simply with one universal actuator and so throttle body development work has once again emphasized the use of a modular kit in order to reduce verification input while offering customers an economically attractive option. Meanwhile certified production facilities are available worldwide for supplying customer needs.