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KR-102963073-B1 - Method for preventing or reducing low-speed pre-ignition in a direct-injection spark-ignition engine having a silane-containing lubricant

KR102963073B1KR 102963073 B1KR102963073 B1KR 102963073B1KR-102963073-B1

Abstract

A lubricating engine oil composition for use in a small boosted engine is disclosed, comprising a lubricating oil base stock as a major component and one or more silane-containing compounds. Additionally, a method for preventing or reducing low-speed pre-ignition in a direct injection, boosting, spark-ignition internal combustion engine, and the use of one or more silane-containing compounds in a lubricating engine oil composition for preventing or reducing low-speed pre-ignition in a direct injection, boosting, spark-ignition internal combustion engine are disclosed.

Inventors

  • 밀러, 존 로버트
  • 구나완, 테레사 리앙
  • 셰어팩, 리차드 유진
  • 엘리오트, 이안 쥐.
  • 마리아, 아미르 가말

Assignees

  • 셰브런 오로나이트 컴퍼니 엘엘씨
  • 셰브런 유.에스.에이.인크.

Dates

Publication Date
20260513
Application Date
20190509
Priority Date
20180525

Claims (14)

  1. A method for preventing or reducing low-speed pre-ignition in a direct injection, boosting, or spark-ignition internal combustion engine, comprising the step of lubricating the crankcase of said internal combustion engine with a lubricating oil composition comprising 100 to 3000 ppm of silicon and a calcium detergent from one or more sulfur-containing silane compounds based on the total weight of the lubricating oil composition.
  2. A method according to claim 1, wherein the engine is operated under a load having a brake average effective pressure (BMEP) of 12 to 30 bar.
  3. A method according to claim 1, wherein the engine is operated at a speed of 500 to 3,000 rpm.
  4. Method of claim 1, wherein the sulfur-containing silane compound has the following general formula (I): In the above formula, R1 is selected from the group consisting of saturated and unsaturated hydrocarbyl and chain-substituted saturated and unsaturated hydrocarbyl; R2 is selected from the group consisting of hydrogen, saturated and unsaturated hydrocarbyl and chain-substituted saturated and unsaturated hydrocarbyl; a is an integer from 1 to 3, and A is a group of valence r, r is an integer of 1 or more, said A is selected from the group consisting of saturated and unsaturated, linear, branched, or cyclic hydrocarbyl groups, or linear, branched, or cyclic siloxane or polysiloxane groups, each of which comprises a substituent having a sulfur heteroatom.
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  7. A method according to claim 1, wherein the lubricating oil composition further comprises a molybdenum-containing compound.
  8. The method according to claim 1, wherein the lubricating oil composition further comprises one or more other additives selected from ash-free dispersants, ash-free antioxidants, phosphorus-containing anti-wear additives, friction modifiers, and polymeric viscosity modifiers.
  9. A method according to claim 1, wherein the engine is fueled by liquid hydrocarbon fuel, liquid non-hydrocarbon fuel, or a mixture thereof.
  10. A method according to claim 1, wherein the engine is fueled by natural gas, liquefied petroleum gas (LPG), compressed natural gas (CNG), or a mixture thereof.
  11. A lubricating engine oil composition comprising a sulfur-containing silane compound for preventing or reducing low-speed pre-ignition in direct injection, boosting, or spark-ignition internal combustion engines, wherein the lubricating engine oil composition comprises 100 to 3000 ppm of silicon and a calcium detergent from the sulfur-containing silane compound based on the total weight of the lubricating engine oil composition.
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Description

Method for preventing or reducing low-speed pre-ignition in a direct-injection spark-ignition engine having a silane-containing lubricant Field of invention The present disclosure relates to a lubricant composition for direct injection, boosting, spark ignition internal combustion engines containing at least one silane compound. Additionally, the present invention relates to a method for preventing or reducing low-speed pre-ignition in an engine lubricated with a formulated oil. The formulated oil has a composition comprising at least one oil-soluble or oil-dispersible silane compound. Background of the Invention Recently, engine manufacturers have developed smaller engines that provide high power density and superior performance while reducing friction and pumping losses. This is achieved by using turbochargers or mechanical superchargers to increase boost pressure and lowering engine speeds by utilizing higher transmission gear ratios, which are allowed by generating higher torque at lower engine speeds. However, it has been found that higher torque at lower engine speeds causes random pre-ignition in low-speed engines, a phenomenon known as Low Speed Pre-Ignition (LSPI). This results in very high cylinder peak pressure, which can lead to catastrophic engine failure. The potential for LSPI prevents engine manufacturers from fully optimizing engine torque at lower speeds in these smaller, high-output engines. One of the prior theories regarding the cause of low-speed pre-ignition (LSPI) is that it is caused, at least in part, by the autoignition of engine oil droplets entering the engine combustion chamber from the piston gap under high pressure during the longest period of the compression stroke while the engine is operating at low speed (Amann et al., SAE 2012-01-1140). While some engine knocking and pre-ignition problems can and are being solved through new engine technologies, such as the use of electronic control and knock sensors, and the optimization of engine operating conditions, there is a need for lubricating oil compositions that can reduce or prevent LSPI problems and also improve or maintain other performance such as wear and oxidation protection. Detailed description of the invention The term "boosting" is used throughout the specification. Boosting refers to operating an engine at a higher intake pressure than in a naturally aspirated engine. Boosting conditions can be achieved by using a turbocharger (driven by exhaust) or a supercharger (driven by the engine). "Boosting" enables engine manufacturers to use smaller engines that provide high power density to deliver superior performance while reducing friction and pumping losses. Throughout the specification and claims, the terms usefulness or dispersibility are used. Usefulness or dispersibility means that an amount necessary to provide a desired level of activity or performance can be incorporated by being dissolved, dispersed, or suspended in a lubricating viscosity oil. Generally, this means that at least about 0.001 weight percent of the substance can be incorporated into the lubricating oil composition. For further discussion of oil solubility and dispersibility, particularly the term “stable dispersibility,” reference is made to U.S. Patent No. 4,320,019, which is set forth herein by reference for relevant teachings in this regard. The term "sulfated ash" refers to non-flammable residues generated from detergents and metal additives in lubricating oil. Sulfated ash can be measured using ASTM test D874. The term "Total Base" or "TBN" refers to the amount of base equivalent to a milligram of KOH in 1 gram of a sample. Therefore, a higher TBN number reflects more alkaline products and thus reflects greater alkalinity. TBN was measured using the ASTM D 2896 test. Unless otherwise specified, all percentages are expressed as weight percentages. Generally, the sulfur level in the lubricating oil composition of the present invention is about 0.7 wt.% or less, based on the total weight of the lubricating oil composition, for example, about 0.01 wt.% to about 0.70 wt.%, 0.01 to 0.6 wt.%, 0.01 to 0.5 wt.%, 0.01 to 0.4 wt.%, 0.01 to 0.3 wt.%, 0.01 to 0.2 wt.%, or 0.01 wt.% to 0.10 wt.%. In one embodiment, the sulfur level in the lubricating oil composition of the present invention is about 0.60 wt.% or less, about 0.50 wt.% or less, about 0.40 wt.% or less, about 0.30 wt.% or less, or about 0.20 wt.% based on the total weight of the lubricating oil composition. % or less, approximately 0.10 wt. % or less. In one embodiment, the phosphorus level in the lubricating oil composition of the present invention is about 0.12 wt.% or less, for example, about 0.01 wt.% to about 0.12 wt.%, based on the total weight of the lubricating oil composition. In one embodiment, the phosphorus level in the lubricating oil composition of the present invention is about 0.11 wt.% or less, for example, about 0.01 wt.% to about 0.11 wt.%, based on the total weight of the