Variable valve actuation as an efficient measure for Off-Highway (OHW) drive systems

Zusammenfassung

Modern legislation for internal combustion engines is forcing the truck and the Off-highway engine designers to manage the trade-off between efficiency in terms of TCO and the ecological foot print regarding fuel consumption and exhaust gas emissions. Therefore, modern exhaust gas aftertreatment systems are used to decrease the emissions of PM, NOx and CO but these systems require a certain gas temperature to start the exothermal catalytic reaction in the SCR system and ensure an adequate CRT-effect on the Diesel particle filter. In part load conditions the heat from the exhaust gas is often not sufficient and options to increase the temperatures are required. There are different possibilities of engine modifications that can enable such thermal management effects with differences in temperature increase on one hand and the fuel penalty on the other hand.

In this approach DEUTZ, MAHLE and HILITE investigated the use of a variable exhaust valve train in a DEUTZ 4-cylinder SOHC development engine. The variable valve actuation is realized by a MAHLE CamInCam truck camshaft providing DOHC functionality in a SOHC envelope in combination with a truck specific generic phasing system by HILITE.

This paper shall describe the DEUTZ engine architecture and explain the details of the hardware used as functional description of the CamInCam camshaft and the truck phasing system.

The trials itself and the results from these investigations in a fired engine condition in terms of exhaust gas temperature increase will be presented. Additionally, findings on how to improve in parallel (same hardware) the low-end torque potential of the engine are described. Therefore, the system will contribute to the legislative admissions without sacrificing driveability.