Development of an Intake Air Temperature Estimation Method for Transient Control of Diesel Engines (First Report)
-Proposal of an Intake Air Temperature Estimation Formula for Steady-State Operation-

Kazuhisa Inagaki (TOYOTA CENTRAL R&D LABS)･Akitaka Ueno (Toyota Industries Corporation)･Tsubasa Sugano (Toyota Motor)･Takeshi Nishio (Toyota Industries Corporation)

In modern common-rail diesel engines, noise and exhaust emissions are controlled through multi-stage fuel injection. For optimal pilot injection control, intake air temperature prediction is crucial. In this study, the in-cylinder temperature at intake valve closing (Tivc) is defined, and a predictive formula under steady-state operation is proposed. Tivc can be estimated as a linear combination of intake manifold gas temperature, coolant temperature, and engine output. Simulation results agree with experimental data, confirming the validity of the proposed formula.

Range extender ICE solutions to accelerate time-to-market for HD BEV trucks

Anton Arnberger (AVL List)･Toro Nishizawa (AVL Japan K.K.)･Daniele Corsini･Bernhard Raser (AVL List)

In different markets, commercial vehicle manufacturers face increasingly stringent CO₂ regulations. Today, there are viable use cases for battery-electric trucks (BEVs), particularly when cost-effective charging at depots is possible. However, operational flexibility remains limited: public charging infrastructure is often unavailable, impractical in dense metropoles such as those in Japan, or expensive in terms of cost per kWh. This presentation introduces a diesel-based industrial range extender (REX) integrated into a BEV truck as a bridging solution. Diesel offers efficiency, durability, and logistical compatibility for this application. Nevertheless, its role as a range extender requires targeted modifications to achieve maximum efficiency across relevant mission profiles while ensuring the most compact packaging. The publication will address the dedicated engine design for REX applications as well as key aspects of vehicle integration.

Evolving HD Engine Efficiency to the next level
-A Pathway to 56% Brake Thermal Efficiency for Commercial Applications-

Anton Thomas Koerfer (FEV Group GmbH)･Lukas Virnich (FEV Europe)･Michael Franke (FEV North America Ltd.)･Stefano Ghetti･Ulrich Gruetering (FEV Europe)

The Diesel powerplant in heavy applications characterizes all over the world the backbone of goods transport. Driven by a variety of objectives, fuel efficiency has always displayed an engineering goal and will continue in the mid-term horizon. This paper reviews an innovative study based on an in-series engine definition in the 2 l/cyl class. The most important aspects include design elements as uplifted combustion pressure with higher compression ratios and innovative bowl geometries, supported by upgradations on fuel and air delivery side, but include also novel S/B ratios and adjusted stroke characteristics, plus thermal coating for reduction of heat losses

Relationship Between Wall Surface Roughness and the Flow fFeld Inside a Spray Flame After Wall Impingement

Yoshio Zama･Yusei Fukamachi (Gunma University)･Shinya Furukawa (Isuzu Advanced Engineering Center, Ltd)

In this report, the effect of wall roughness on the flow field of spray flames In this report, the effect of wall roughness on the flow field of spray flames impinged on the wall based on velocity information obtained over macroscopic and microscopic scales was investigated. The results indicate that the wall roughness employed in the experiments was smaller than the thickness of the viscous sublayer inside the spray, and consequently, no significant effect of wall roughness on the flow field along the wall surface was observed.

Thermal efficiency improvement of a diesel engine by High-heels heat release rate profile
-(Engine experimental results and analysis by utilizing multiple-injector system)-

Teruo Machii･Noboru Uchida (New A.C.E Institute)

Further increase in degree of constant volume combustion cannot necessarily achieve higher thermal efficiency probably caused by increased cooling loss. Therefore, High-heels heat release rate profile, which rather reduces degree of constant volume combustion, has proposed as a potential combustion concept to improve cooling loss and thermal efficiency simultaneously. To achieve the target profile, the feasibility of controlling heat release rate profile with more degrees of freedom by utilizing a multiple-injector system was numerically confirmed in the previous study. This study investigates the factors contributed to the thermal efficiency improvement by analyzing experimental results conducted by a heavy-duty single-cylinder engine.