Internal Combustion Engines and Powertrain Systems for Future Transport 2019

Proceedings of the International Conference on Internal Combustion Engines and Powertrain Systems for Future Transport, (ICEPSFT 2019), December 11-12, 2019, Birmingham, UK

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• Publisher: CRC Press
• Year: 2020
• Print ISBN: 9780367903565
• eBook ISBN: 9781000038309
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

With the changing landscape of the transport sector, there are also alternative powertrain systems on offer that can run independently of or in conjunction with the internal combustion (IC) engine. This shift has actually helped the industry gain traction with the IC Engine market projected to grow at 4.67% CAGR during the forecast period 2019-2025. It continues to meet both requirements and challenges through continual technology advancement and innovation from the latest research. With this in mind, the contributions in Internal Combustion Engines and Powertrain Systems for Future Transport 2019 not only cover the particular issues for the IC engine market but also reflect the impact of alternative powertrains on the propulsion industry. The main topics include:

• Engines for hybrid powertrains and electrification
• IC engines
• Fuel cells
• E-machines
• Air-path and other technologies achieving performance and fuel economy benefits
• Advances and improvements in combustion and ignition systems
• Emissions regulation and their control by engine and after-treatment
• Developments in real-world driving cycles
• Advanced boosting systems
• Connected powertrains (AI)
• Electrification opportunities
• Energy conversion and recovery systems
• Modified or novel engine cycles
• IC engines for heavy duty and off highway

Internal Combustion Engines and Powertrain Systems for Future Transport 2019 provides a forum for IC engine, fuels and powertrain experts, and looks closely at developments in powertrain technology required to meet the demands of the low carbon economy and global competition in all sectors of the transportation, off-highway and stationary power industries.

SESSION 1: INTERNAL
COMBUSTION ENGINES
AND COMBUSTION
ELEMENTS

Assessing the low load challenge for jet ignition engine operation

M.P. Bunce, N.D. Peters, S.K. Pothuraju Subramanyam, H.R. Blaxill

MAHLE Powertrain LLC, USA

ABSTRACT

Lean combustion in spark ignition engines is an advanced engine operating mode that has been proven to produce significant increases in efficiency, a requirement for future internal combustion engines in the transportation sector. This operation necessitates the use of advanced ignition or ignition controls concepts in order to achieve acceptable levels of combustion stability.

This study utilizes a Jet Ignition concept that has been under development for several years. MAHLE Jet Ignition^® is a pre-chamber-based concept that produces high energy jets of partially combusted species that induce ignition and enable rapid, stable combustion at lambda values in excess of 2. In light duty engines this has resulted in minimum brake specific fuel consumption (BSFC) values of approximately 200 g/kWh with reductions in engine-out nitrogen oxides (NO_x) emissions of 95% compared to conventional gasoline engines.

Historically pre-chamber-based combustion concepts have had limited success achieving acceptable combustion stability under low load operation including idle and catalyst light-off. These conditions require a high degree of spark retard capability, a capability that is typically lacking with jet ignition concepts. The purpose of this study is to evaluate the challenges associated with idle and catalyst light-off jet ignition operation, examine the underlying causes, and explore potential solutions with a goal of achieving similar performance to a conventional spark ignited engine under these conditions. Test results from a dedicated 1.5L 3-cylinder jet ignition engine are provided with comparisons to a conventional spark ignition variant of the same engine. Potential solutions to achieving comparable performance metrics to a conventional spark ignited engine are proposed and evaluated on the testbed. The influence of in-cylinder charge motion is assessed relative to low load performance. The applicability of these results to other jet ignition engine applications is discussed.

1 INTRODUCTION

1.1 Background

The perpetual desire to conserve fuel is being coupled with an increasing modern awareness of the deleterious environmental impact of tailpipe emissions from the transportation sector. In response, increasingly stringent global legislation of greenhouse gas emissions will require a step change in internal combustion engine (ICE) efficiency. Concurrently, the reduction in popularity of diesel engines in the passenger car market is applying pressure on manufacturers’ ability to adhere to fleet average fuel economy legislation. It is therefore imperative that technologies that significantly reduce the fuel consumption of gasoline spark ignition (SI) engines are developed and implemented.

A method being increasingly explored to accomplish this goal is dilute gasoline combustion [1-8]. The major limitation in developing dilute combustion systems is the less favorable ignition quality of the mixture. This has necessitated the development of higher energy ignition sources [9,10]. A pre-chamber combustor application is one such technology, having been researched extensively [11-15]. Pre-chamber combustion concepts have demonstrated the potential for stable main chamber combustion at higher levels of dilution than are allowable in typical SI engines [16].

Despite the extensive research and application history of pre-chambers, practical barriers to modern implementation of these systems in passenger car engines remain. An historic key challenge for pre-chambers has been ensuring acceptable low load, idle, and cold start performance [17]. The stringency of tailpipe emissions standards since the last significant commercial implementation of a pre-chamber in a passenger car engine has made acceptable performance at the latter condition particularly critical. Prior research has suggested that pre-chamber geometry must be tailored to encompass acceptable low load performance and to maintain the expected efficiency benefit at part load, and that identifying a common pre-chamber geometry that can accomplish both is challenging [18].

1.2 Jet ignition

MAHLE Jet Ignition^® (MJI) is an auxiliary fueled pre-chamber concept that has been under development for several years [17-19]. The concept incorporates elements studied in previous pre-chamber research including: small pre-chamber volume (< 5% of main combustion chamber clearance volume) for minimizing crevice volume and heat loss, small orifice diameter to promote a high degree of flame quenching, and auxiliary fueling in the pre-chamber to allow separate fueling strategies for pre-chamber and main chamber.

A prototype low-flow direct injection (DI) fuel injector provides a separate fueling event in the pre-chamber. This allows precise, effectively de-coupled control over the mixture in both chambers. This low-flow DI injector also enables the use of a common liquid gasoline for both pre-chamber and main chamber injection. Historically, auxiliary fuel injected in the pre-chamber is gaseous due to metering repeatability and impingement issues with liquid gasoline. Both of these issues have been mitigated through pre-chamber injector development (not described in this study). Up to approximately 3% of total system fuel is injected via auxiliary pre-chamber injection. The remainder is delivered to the main combustion chamber conventionally with port fuel injection (PFI) or DI fueling utilizing off-the-shelf fuel injectors.

Pre-chamber combustion creates a rapid pressure increase in the pre-chamber, forcing contents into the main chamber via the ...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Organising Committee
• SESSION 1: INTERNAL COMBUSTION ENGINES AND COMBUSTION ELEMENTS
• SESSION 2: HYBRID APPLICATIONS
• SESSION 3: EMISSIONS AND AFTER-TREATMENT
• SESSION 4: FUELS AND FUEL INJECTION
• SESSION 5: INCREASING EFFICIENCY AND REDUCING EMISSIONS
• SESSION 6: INTERNAL COMBUSTION ENGINES
• SESSION 7: SIMULATION OF INTERNAL COMBUSTUION ENGINES
• SESSION 8: DESIGN AND DEVELOPMENT OF INTERNAL COMBUSTION ENGINES
• Author index