Optimization of Fuel Injection Control Based on Combustion Chamber Wall Temperature Estimation for Improved Fuel Economy and Reduced Emissions

Ryutaro Morioka･Ryo Adachi･Takeshi Tsuda･Susumu Shimura･Kotaro Atsushi (SUBARU)

In hybrid vehicles that restart the engine frequently, the engine condition changes a lot at restart, which affects emissions and fuel economy. In this study, vehicle tests were conducted using an engine equipped with a wall temperature sensor, confirming fuel injection reduction during restarts. In addition, an AI model was developed to estimate wall temperature from existing control parameters, showing the potential of wall-temperature-based injection control.

Proposal of numerical methods for computationally affordable and high-fidelity large eddy simulation of automotive engines

Hiroki Yao (Ryoyu Systems)･Takayuki Ito (JARI)･Toru Takabayashi (Honda R&D)

As the circumstances surrounding the development of automotive internal combustion engines have become increasingly complex, there is a growing need to reduce the cost of CFD simulations, one of the key analysis tools, and to improve its prediction accuracy. In response to this demand, the authors have been developing a CFD code that employs cell-based AMR and high-order discretization methods. This paper presents the progress of these efforts, along with demonstrative computational examples.

A Fundamental Study on the Geometry of Intake Manifolds for Multi-Cylinder Engines with a Single Throttle System
-Evaluation of Intake Air Distribution Characteristics Using Transient Flow Analysis-

Takumu Takayama･Kenshin Koshimizu･Shinobu Kasamatsu･Wenbao Wu (Tokai University)･Kazuki Ogawa (Aichi University of Technology)･Takayoshi Narita･Hideaki Kato (Tokai University)

The authors are conducting ongoing research into improving the performance of multi-cylinder gasoline engines suitable for small-scale racing vehicles. This report presents a fundamental study on the effects of intake manifold geometry on air mass distribution characteristics, focusing on the flow pattern from the intake port—equipped with an air restrictor—to the cylinders, and utilizing unsteady fluid dynamics analysis to evaluate these geometries.

Experimental Analysis of Unburned Hydrocarbon Emissions in Lean-Burn Spark-Ignition Engines

Shoya Kawaguchi･Tatsuya Kuboyama･Yasuo Moriyoshi (Chiba University)

Incomplete combustion and associated unburned hydrocarbon (UHC) emissions remain critical challenges limiting the application of lean-burn combustion as a high-efficiency engine operating strategy. In this study, combustion characteristics and UHC formation and emission behavior were investigated under lean-burn conditions using an exhaust gas analysis system equipped with Fast FID and NDIR, together with heat flux sensors. The dominant factors governing exhaust UHC emissions were identified.

Development of High Thermal Efficiency PFI Lean-Burn Engine (1st report)

Kazunari Watanabe･Yukihide Nagano･Hiroaki Masatsuki･Kazuhito Okui･Keiichi Sata･Kousuke Kusaba･Akishige Sakuragi･Yuuta Shima･Kazuya Naitou･Tatsuya Ehara (Daihatsu Motor)

We have been developing a high-quality, affordably priced port fuel-injection (PFI) lean-burn gasoline engine for compact vehicles (λ ≥ 2). Modifications to the combustion-chamber geometry improved in-cylinder flow, enhancing flame speed and combustion stability, and extending the lean limit to λ = 3. In the low-to-mid engine speed range, the engine achieved indicated thermal efficiency exceeding 45% and low NOx emissions.

Investigation of a Combined ORC-TEG Waste Heat Recovery System for a Hybrid Electric Vehicle with a Lean-Burn SI Engine

Masaki Naruke･Takaaki Kitamura (JARI)

Recovering waste heat is essential for improving the fuel efficiency of hybrid electric vehicles. In this study, a waste heat recovery system combining an organic Rankine cycle (ORC), including engine cooling, and a thermoelectric generator (TEG) is applied to a hybrid electric vehicle equipped with a lean-burn spark-ignition engine capable of operating at an excess air ratio of 2.0 or higher. The performance of the combined ORC-TEG system is evaluated using one-dimensional numerical simulations.