小型商用車向け水素エンジン開発

松井　良輔（トヨタ自動車）

水素の普及拡大を目指して小型商用車向けに水素エンジンを開発した．V型6気筒3.5Lガソリン過給エンジンをベースに90%以上の部品を流用し，性能/信頼性を満足した上で熱効率40%を実現，排気はEuro7相当の規制値をクリアした．本講演では水素起因の異常燃焼などの技術的な課題とその対応について報告する．

Transient NOx reduction for lean burn SI H2-ICE by water injection utilizing water recovered from exhaust gasses

Xander Seykens･Jinlin Han･Erik Doosje (TNO)

The hydrogen internal combustion engine (H2-ICE) is a promising pathway for complying with heavy-duty CO2 regulations. The lean burn SI H2-ICE is characterized by its ultra-low engine-out NOx potential in steady-state operation. The main source of engine-out NOx is thermal NO formed during dynamic engine operation when in-cylinder air-excess ratio momentarily drops due to insufficient supply of air. In this paper, a proof-of-concept for transient NOx reduction is provided. In this proof-of-concept NOx emissions during dynamic engine operation (step loads) are effectively reduced by the application of port water injection. The utilized water is recovered from the exhaust gases, making the NOx reduction a self-sustaining process.

アンモニア/水素SIエンジンの開発（第3報）
-アンモニア/水素供給方式のPFI化と性能への影響検証-

牟田　直輝・草塲　耕佑・正月　宏明・西橋　知博・黒木　志典・永野　幸秀・澤下　真人・島　祐太・内藤　一哉・江原　達哉（ダイハツ工業）

内燃機関からのCO2低減策の一つとしてアンモニア水素火花点火機関の開発を進めている．第1報で構築したDI水素噴流モデルを基にPFI噴流モデルを構築し，アンモニア/水素供給方式のPFI化がエンジン性能へ及ぼす影響について検証したため，その内容について報告する．

Combustion System Design Study for a Commercial Vehicle Hydrogen Engine Application

Thomas Briggs･Daniel Ryan Williams (Southwest Research Institute)･Tomoyuki Itou (Isuzu Motors)

A pent-roof combustion chamber design was adapted from a previous natural gas engine demonstration to allow for single-cylinder engine combustion studies on PFI and LPDI hydrogen operation. Comparisons were made of the impact of tumble and injector type on the efficiency and performance of this engine. The results demonstrated an improvement in efficiency for LPDI relative to PFI and that tumble ratio did not have a strong impact on hydrogen combustion. Peak net indicated thermal efficiency of 46% was measured, with engine-out NOX emissions and engine out exhaust temperature at levels which are compatible with standard lean-NOX aftertreatment solutions.