EGR module versions. Source: KSPG. Click to enlarge.

In answer to the rising cost of fuel and ever tighter regulations regarding CO₂ emissions, Pierburg GmbH has for decades been specializing in, among other things, exhaust-gas recirculation (EGR) modules. EGR modules consist of an EGR valve, an EGR cooler to cool the exhaust gases and optionally, a bypass flap which is used to regulate the controlled re-routing of the exhaust gas flow—i.e., through the EGR cooler or past the EGR cooler.

Among the observable trends is that EGR valves—customarily employed for the reduction of diesel engine emissions since the 1980s—are increasingly being fitted to gasoline engines given the incremental fuel-saving potential of such valves.

The effect of exhaust-gas recirculation is based on a lowering of combustion temperatures in diesel and gasoline engines. Lower temperatures result in a reduction in nitrogen oxides. On gasoline units, this is accompanied by less fuel consumption because of engine dethrottling under partial load—one reason, in particular, why EGR modules are of broader interest.

The Pierburg cEM EGR valve is a so-called “hot mount,” able to withstand exhaust gas temperatures of up to 800 °C with water-cooling. Depending on customer wishes, it may feature electromagnetic protection and integrated water cooling. It is available in standalone, plug-in as well as fully integrated cooler module versions. The unit’s small footprint allows it to be mounted directly in the cooler module.

The cEM EGR valve serves to precisely control the recirculated mass of exhaust gases. In order to permit the passage of high mass flow rates, the EGR valve opens in the direction of the exhaust gases; a geared DC electric motor controls the valve setting, between shut and open.

A contactless Hall sensor determines the position. Direct position identification with the aid of a sensor magnet on the valve rod enables more precise control of the recirculated exhaust gases. With a powerful actuator, this is also able to tightly seal off for brief periods exhaust gas pressures of up to 5 bar.

Pierburg’s annual production volume of EGR valves and modules is as high as six million units. The valves are made not only at the German plants but also in the Czech Republic, Spain, USA, India, and China.