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Journal Article

0W-16 Fuel Economy Gasoline Engine Oil Compatible with Low Speed Pre-Ignition Performance

2017-10-08
2017-01-2346
The development of low viscosity gasoline engine oils should not only focus on fuel economy improvement, but also on the low speed pre-ignition (LSPI) prevention property. In previous LSPI prevention literatures, the necessity of applying Ca/Mg-based detergents system in the engine oil formulations was proposed. ...This newly developed engine oil also passed LSPI test and all of the bench and engine tests required by GF-5, which implied that this oil could provide good protection for engines.
Journal Article

A Comparative Low Speed Pre-Ignition (LSPI) Study in Downsized SI Gasoline and CI Diesel-Methane Dual Fuel Engines

2014-10-13
2014-01-2688
Low speed pre-ignition (LSPI) in downsized spark-ignition engines has been studied for more than a decade but no definitive explanation has been found regarding the exact sources of auto-ignition. ...No single mechanism can explain all the occurrences of LSPI and that each engine should be considered as a particular case supporting different conditions for auto-ignition. ...However, if Dual Fuel combustion is less knock sensitive, LSPI remains one of the main limitations of low-end torque also for dual fuel engines. Indeed, in some cases, premature ignition of CNG can be observed before the Diesel pilot injection as LSPI can classically be observed before the spark in gasoline engines.
Technical Paper

A Technical Review on Low Speed Pre Ignition in Turbocharged Gasoline Direct Injection Engines

2022-10-05
2022-28-0023
The increase of pressure and temperature inside the combustion chamber at high loads also leads to a pre-ignition induced super knock and in severe cases, LSPI leads to broken piston rings, damaged pistons and bent connecting rods. Thus LSPI has become a great concern since it operates in a very common driving pattern of rapidly accelerating the vehicle at lower speed range, thereupon limiting further downsizing of gasoline engines. ...The power lost can be compensated by integrating a turbocharger to the engine to increase the boost pressure however, this again may create an abnormal combustion event known as low-speed pre-ignition (LSPI). The increase of pressure and temperature inside the combustion chamber at high loads also leads to a pre-ignition induced super knock and in severe cases, LSPI leads to broken piston rings, damaged pistons and bent connecting rods. ...The present review paper comprehends the details the conditions for occurrence of LSPI mainly focusing on cause and effect of the local auto ignition taking place inside the cylinder due to formation of contaminants entering from the top land crevice during blow-down and washed from the cylinder walls during direct injection wall impingement, the parameters effecting it and various methods to mitigate the LSPI issue in turbo charged gasoline direct injection engines.
Technical Paper

A real-world fleet test of the effects of engine oil on Low Speed Pre-Ignition occurrence in TGDi engine

2019-12-19
2019-01-2294
The findings from this study have shown that LSPI does happen in the field and engine oil formulations impact the number of LSPI events whilst operating in uncontrolled real-world conditions, further confirming that the right engine oil formulation is a critical component for protecting TGDi engines. ...In the last decade, numerous studies have been conducted to investigate the mechanism of Low Speed Pre-Ignition (LSPI) in Turbocharged Gasoline Direct Injection (TGDi) engines. According to technical reports, engine oil formulations can significantly influence the occurrence of LSPI particularly when higher levels of calcium-based additives are used, increasing the tendency for LSPI events to occur. ...According to technical reports, engine oil formulations can significantly influence the occurrence of LSPI particularly when higher levels of calcium-based additives are used, increasing the tendency for LSPI events to occur.
Journal Article

Advanced Methods to Handle LSPI in TGDI Engines

2020-08-18
2020-28-0008
However, TGDI technology is susceptible to an abnormal combustion phenomenon termed as Low Speed Pre-Ignition (LSPI) event. This event happens prior to the intended combustion, which causes the catastrophic engine damage. ...In this paper, advanced methods to handle the LSPI occurrence severity and component level advances in design robustness to avoid the engine damage are reported. ...In overall, the techniques related to engine design to predict the LSPI occurrence in terms of peak cylinder pressure (PCP) and number of events are summarized.
Technical Paper

Alternative Engine Oil Formulating Solutions to Reduce Low Speed Pre-Ignition

2019-12-19
2019-01-2153
Operating downsized, turbocharged, direct injection engines at low speeds and high loads has led to an abnormal combustion phenomenon known as Low Speed Pre-Ignition (LSPI), wherein the fuel-air mixture ignites before the spark occurs. LSPI can lead to extremely high pressures in the combustion chamber, which can damage hardware such as pistons, piston rings, and spark plugs. ...Lubricants, fuels, and engine operating conditions have been shown to impact LSPI. Any of these can be modified to improve LSPI performance. One solution which has been used widely in the industry is reformulating the lubricant additive package. ...In particular, calcium-based detergents have been shown to promote LSPI, while magnesium detergents appear neutral to LSPI. Reducing the usage of calcium detergents can impact other performance areas such as deposit control and fuel economy, and limits formulating flexibility.
Journal Article

An Experimental Investigation on Low Speed Pre-Ignition in a Highly Boosted Gasoline Direct Injection Engine

2015-04-14
2015-01-0758
The biggest challenge in developing Turbocharged Gasoline Direct Injection (TGDI) engines may be the abnormal combustion phenomenon occurring at low speeds and high loads, known as low-speed pre-ignition (LSPI). LSPI can trigger severe engine knocks with intensities much greater than those of spark knocks and thus characterized as super knocks. ...Based on findings in this study, it was proposed that the oil particles as oil loading in the blowby recirculation could be the root cause for LSPI as they cause dirtiness of the combustion chamber roof where the oil particles could be attached and then initiate LSPI in the late compression stroke. It was demonstrated that although LSPI may not be eliminated due to the nature of the triggers, TGDI engines can be operated super-knock free through controlling conditions for combustion and engine cooling. ...In this study, behavior and patterns of LSPI were investigated experimentally with a highly-boosted 1.5L TGDI engine. It was found that LSPI could occur as an isolated event, a couple of events in sequence, or a trail of events.
Technical Paper

An Introduction to How Low Speed Pre Ignition Affects Engine Components

2017-03-28
2017-01-1042
This phenomenon has the potential to catastrophically damage the power cylinder unit (PCU); therefore, engine manufacturers and suppliers are working to eliminate LSPI or design components to survive LSPI events if they occur. This paper is the first of a series of papers that will discuss MAHLE’s LSPI research, focused on power cylinder unit (PCU) components and systems designed to withstand LSPI events, as well as minimizing or eliminating the propensity of LSPI to occur. ...This paper is the first of a series of papers that will discuss MAHLE’s LSPI research, focused on power cylinder unit (PCU) components and systems designed to withstand LSPI events, as well as minimizing or eliminating the propensity of LSPI to occur....This operating condition results in an environment within the combustion chamber which has the propensity to experience a disruptive abnormal combustion event known as low speed pre-ignition (LSPI). This phenomenon has the potential to catastrophically damage the power cylinder unit (PCU); therefore, engine manufacturers and suppliers are working to eliminate LSPI or design components to survive LSPI events if they occur.
Journal Article

An Investigation on the Ignition Characteristics of Lubricant Component Containing Fuel Droplets Using Rapid Compression and Expansion Machine

2016-10-17
2016-01-2168
With the development of downsized spark ignition (SI) engines, low-speed pre-ignition (LSPI) has been observed more frequently as an abnormal combustion phenomenon, and there is a critical need to solve this issue. ...It has been acknowledged that LSPI is not directly triggered by autoignition of the fuel, but by some other material with a short ignition delay time. ...It was previously reported that LSPI can be caused by droplets of lubricant oil intermixed with the fuel. In this work, the ignition behavior of lubricant component containing fuel droplets was experimentally investigated by using a constant volume chamber (CVC) and a rapid compression and expansion machine (RCEM), which enable visualization of the combustion process in the cylinder.
Journal Article

Analysis of Interaction between Autoignition and Strong Pressure Wave Formation during Knock in a Supercharged SI Engine Based on High Speed Photography of the End Gas

2017-11-15
2017-32-0119
The measured results for the actual development of autoignition made it clear that extremely strong knock, such as what occurs under high-speed, high-load operation and also that induced by low-speed pre-ignition (LSPI) in a supercharged downsized engine under low-speed, high-load operation (Super-Knock), is presumably caused by such phenomena.
Technical Paper

Analysis of the Impact of Production Lubricant Composition and Fuel Dilution on Stochastic Pre-Ignition in Turbocharged, Direct-Injection Gasoline Engines

2019-04-02
2019-01-0256
These abnormal combustion events have been referred to as Stochastic Pre-Ignition (SPI) or Low-Speed Pre-Ignition (LSPI). The events are characterized by an undesired, early start of combustion of the cylinder charge which occurs before or in parallel to the intended flame kernel development from the spark plug.
Journal Article

Assessing the Impact of Lubricant and Fuel Composition on LSPI and Emissions in a Turbocharged Gasoline Direct Injection Engine

2020-04-14
2020-01-0610
However, high specific torque levels, especially at low speeds, can lead to abnormal combustion phenomena such as knock or Low-Speed Pre-Ignition (LSPI). LSPI, in particular, can limit further downsizing due to resulting and potentially damaging mega-knock events. ...Herein, we characterize the impacts of lubricant and fuel composition on LSPI frequency in a TGDI engine while specifically exploring the correlation between fuel composition, particulate emissions, and LSPI events. Our research shows that: (1) oil composition has a strong impact on LSPI frequency and that LSPI frequency can be reduced through a carefully focused approach to lubricant formulation. ...Herein, we characterize the impacts of lubricant and fuel composition on LSPI frequency in a TGDI engine while specifically exploring the correlation between fuel composition, particulate emissions, and LSPI events.
Technical Paper

Assessment of the impact of low-speed-pre-ignition mitigation techniques on emission levels

2018-09-03
2018-36-0100
Low-speed-pre-ignition (LSPI) presents a great challenge for developing smaller, more efficient internal combustion engines. ...Current research focuses on understanding the causes of LSPI and developing strategies to mitigate its intensity or eliminate it completely. On this paper, the effect of different LSPI mitigation strategies on emission levels is evaluated. ...On this paper, the effect of different LSPI mitigation strategies on emission levels is evaluated. For this purpose, a 1.0 naturally aspirated port fuel injection (PFI) engine was used.
Technical Paper

Autoignition of Lubricating Oil from Piston Crown and In-Cylinder Condition on Abnormal Combustion of Supercharged SI Engine

2022-01-09
2022-32-0008
It is called the LSPI (Low Speed Pre-Ignition)[1]. This research focuses on one of the source of abnormal combustion which is the autoignition of lubricating oil from piston crown in cylinder, here especially, frequency of autoignition in cylinder[2,3,4]. ...The special behavior of the LSPI has been measured. The autoignition timing is ATDC in the initial stage. When the cycle of autoignition proceed, its timing is advance to BTDC. ...The dangerous activation energy E for the LSPI is under 6452(× 104 J/mol)in this research. The activation energy E would be able to take advantage of the engine design and simulation to prevent from the LSPI.
Technical Paper

Autoignition of a Lubricating Oil Droplet with Fuel Ingredients on Abnormal Combustion of Supercharged SI Engine

2020-11-30
2020-32-2318
It is called Low Speed Pre-ignition (LSPI). The lubricating oil which has a tolerance for LSPI has been introduced already in automobile market nowadays. ...However, cause and mechanism of LSPI does not clear sufficiently. It has been reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown [1, 2]. ...This paper focuses on effect of fuel ingredients on autoignition of a lubricating oil droplet about LSPI. On the ignition source point of view, it is important to clear the mechanism of a lubricating oil droplet autoignition in cylinder.
Technical Paper

Characteristics of Abnormal Combustion in the Scavenging Zone for a Highly-Boosted Gasoline Direct Injection Engine

2017-03-28
2017-01-1721
It was demonstrated that with proper mixture enrichment, intensities and frequencies of superknock induced by LSPI could be reduced; when the mixture was enriched sufficiently, LSPI events occurred without leading to superknock. ...The low-speed pre-ignition (LSPI) events observed in the engine tests fell mainly in the scavenging zone. The most representative LSPI pattern observed was a sequence of the events, with the event number varying from one to 10 in the sequence. ...The most representative LSPI pattern observed was a sequence of the events, with the event number varying from one to 10 in the sequence.
Technical Paper

Characteristics of Auto-Ignition for Lubricants and Lubricant/Gasoline Based on an Innovative Single Droplet Test System

2020-04-14
2020-01-1428
However, Low-Speed Pre-Ignition (LSPI) phenomenon observed in these engines restricts their improvement of performance. Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. ...Some researchers have shown that auto-ignition of lubricant in the combustion chamber has a great effect on the LSPI frequency. To study the auto-ignition characteristics of lubricant, an innovative single droplet auto-ignition test system for lubricant and its mixture is designed and developed, with better accuracy and effectiveness.
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