On the Availability of Commercial Off-the-Shelf (COTS) Heavy-Duty Diesel Engines for Military Ground Vehicle Use

摘要

The continual reduction of diesel engine heavy-duty nitrous oxides and particulate matter emissions due to Environmental Protection Agency (EPA) regulations has resulted in significant changes to engine hardware since 1998. Such changes have included use of cooled exhaust gas recirculation, clean gas induction, oxidation catalysts, variable geometry turbochargers, lean nitrous oxide traps, urea selective catalytic reduction, passive and catalyzed particulate matter filters, and engine design changes to reduce oil consumption while allowing use of low sulfur diesel fuel (DF-2) and maintaining oil change intervals and subsystem durability levels of previous model years. The net result from a propulsion system perspective is increased heat rejection, additional induction and exhaust system volume, increased system weight, and less tolerance to military fuels and lubricants. Such changes are detrimental to the performance of military vehicles that are required to operate in both desert and artic-like conditions while meeting stringent mission dependent mobility and cooling requirements. To partially address this issue, the U.S. Army obtained National Security Exemptions that effectively allow use of non-compliant engines for tactical vehicles with permanent armor and use of 1998 compliant on-road and Tier III off-road engines for nonarmored tactical vehicles. Nevertheless, there still exists the practicality of introducing current and future commercial engines into military applications through necessary engine system modifications that allow vehicles to meet mobility, cooling, and survivability requirements while either meeting 1998 standards or not complying with any particular standard. Such a scenario may result in the development of military aftermarket opportunities and the utilization of export markets for engine manufacturers and selected partners given the typical low volume military engine production rates. This submission will address this key topic and also provide background concerning the U.S. Army's emission compliance strategy.