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EP-4484529-B1 - METHOD FOR LUBRICATING INTERNAL COMBUSTION ENGINE

EP4484529B1EP 4484529 B1EP4484529 B1EP 4484529B1EP-4484529-B1

Inventors

  • TAKESHIMA, SHIGEKI

Dates

Publication Date
20260513
Application Date
20171018

Claims (8)

  1. A method for lubricating an internal combustion engine, the method comprising: supplying a lubricating oil composition to a cylinder of an internal combustion engine, wherein the internal combustion engine has a mean effective pressure of no less than 1.3 MPa, the lubricating oil composition comprising: a mineral base oil or a synthetic base oil or a mixture thereof, as a lubricant base oil; and (A) a metallic detergent; and (C) at least one phosphorus-containing anti-wear agent selected from (C1) a zinc dialkyl dithiophosphate having C 3-8 primary alkyl groups and (C2) a zinc dialkyl dithiophosphate having C 3-8 secondary alkyl groups, in an amount of 400 to 1200 mass ppm in terms of phosphorus on the basis of the total mass of the composition, the component (A) comprising: (A1) a calcium borate-containing carboxylate detergent, and/or a calcium borate-containing sulfonate detergent, in an amount of 0.25 to 1.20 mass% in terms of calcium on the basis of the total mass of the composition; and (A2) a calcium carbonate-containing metallic detergent, in an amount of 0.25 to 0.90 mass% in terms of calcium on the basis of the total mass of the composition, wherein a molar ratio B/Ca of a boron content B (unit: mol) of the lubricating oil composition derived from the component (A) and a calcium content Ca (unit: mol) of the lubricating oil composition derived from the component (A) is no less than 0.52; the lubricating oil composition has a kinematic viscosity at 100°C of 13.0 to 16.3 mm 2 /s; and an integrated intensity ratio of peaks of CaO in an X-ray diffraction spectrum of an ash is no more than 16.5%, the ash being obtained by incinerating the lubricating oil composition in an air at 950°C, wherein the X-ray diffraction spectrum of the ash is measured in a range of a diffraction angle 2θ of 5 to 90° using CuKα radiation as a X-ray source; and wherein the integrated intensity ratio is a ratio of a total integrated intensity of peaks derived from CaO to a total integrated intensity of all peaks in a X-ray diffraction spectrum which plots diffracted X-ray intensity (unit: cps) along the vertical axis against a diffraction angle 2θ (unit: deg) along the horizontal axis; and wherein in the X-ray diffraction spectrum, the peaks derived from CaO appear on 2θ = 32.24°, 37.40°, 53.93°, 64.24°, 67.47°, 79.77° and 88.66°; and the internal combustion engine is a premix combustion medium-speed trunk piston diesel engine using a first fuel as a main fuel, wherein the first fuel has a flash point of no more than 15°C.
  2. The method according to claim 1, the lubricating oil composition further comprising one or more selected from the group consisting of: (B) an ashless dispersant, (D) an amine antioxidant, and (E) an oil-soluble organic molybdenum compound.
  3. The method according to claim 1 or 2, the method comprising: operating the internal combustion engine using the first fuel as a main fuel.
  4. The method according to claim 3, the first fuel comprising a hydrocarbon having a carbon number of 1 to 4.
  5. The method according to claim 3 or 4, the first fuel comprising one or more selected from the group consisting of: methane, ethane, ethylene, propane, butane, methanol, ethanol, and dimethyl ether.
  6. A lubricating oil composition for an internal combustion engine, the lubricating oil composition comprising: a mineral base oil or a synthetic base oil or a mixture thereof, as a lubricant base oil; and (A) a metallic detergent; and (C) at least one phosphorus-containing anti-wear agent selected from (C1) a zinc dialkyl dithiophosphate having C 3-8 primary alkyl groups and (C2) a zinc dialkyl dithiophosphate having C 3-8 secondary alkyl groups, in an amount of 400 to 1200 mass ppm in terms of phosphorus on the basis of the total mass of the composition, the component (A) comprising: (A1) a calcium borate-containing carboxylate detergent, and/or a calcium borate-containing sulfonate detergent, in an amount of 0.25 to 1.20 mass% in terms of calcium on the basis of the total mass of the composition; and (A2) a calcium carbonate-containing metallic detergent, in an amount of 0.25 to 0.90 mass% in terms of calcium on the basis of the total mass of the composition, wherein an integrated intensity ratio of peaks of CaO in a X-ray diffraction spectrum of an ash is no more than 16.5%, the ash being obtained by incinerating the lubricating oil composition in an air at 950°C, wherein the X-ray diffraction spectrum of the ash is measured in a range of a diffraction angle 2θ of 5 to 90° using CuKα radiation as a X-ray source; and wherein the integrated intensity ratio is a ratio of a total integrated intensity of peaks derived from CaO to a total integrated intensity of all peaks in a X-ray diffraction spectrum which plots diffracted X-ray intensity (unit: cps) along the vertical axis against a diffraction angle 2θ (unit: deg) along the horizontal axis; and wherein in the X-ray diffraction spectrum, the peaks derived from CaO appear on 2θ = 32.24°, 37.40°, 53.93°, 64.24°, 67.47°, 79.77° and 88.66°; a molar ratio B/Ca of a boron content B (unit: mol) of the lubricating oil composition derived from the component (A) and a calcium content Ca (unit: mol) of the lubricating oil composition derived from the component (A) is no less than 0.52; the lubricating oil composition has a kinematic viscosity at 100°C of 13.0 to 16.3 mm 2 /s; and the internal combustion engine is a premix combustion medium-speed trunk piston diesel engine using a first fuel as a main fuel, wherein the first fuel has a flash point of no more than 15°C.
  7. The lubricating oil composition according to claim 6, further comprising: one or more selected from the group consisting of: (B) an ashless dispersant, (D) an amine antioxidant, and (E) an oil-soluble organic molybdenum compound.
  8. Use of the lubricating oil composition as defined in claim 6 or 7, wherein the lubricating oil composition is used to lubricate at least a cylinder in a premix combustion middle-speed trunk piston diesel engine using a first fuel as a main fuel, wherein the first fuel has a flash point of no more than 15°C.

Description

FIELD The present invention relates to methods for lubricating internal combustion engines, and particularly to a method for lubricating an internal combustion engine wherein the method can suppress preignition. BACKGROUND Internal combustion engines support most of modern transportation. As regards automobile engines, it has been recently proposed to replace conventional natural aspiration engines with turbocharged engines having smaller displacements (turbocharged downsized engines), so as to reduce fuel consumption of, in particular, automobile gasoline engines. A turbocharged downsized engine is equipped with a turbocharger, which makes it possible to reduce a displacement while maintaining power, and thus to reduce fuel consumption. WO 2016/043333 A1 discloses a lubricating oil composition and a method for manufacturing said lubricating oil composition. EP 2 522 710 A1 discloses a lubricating oil composition comprising a lubricating base oil with a 100°C kinematic viscosity of 1-20 mm2/s, a friction modifier, a first overbased metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal borate, and an overbased second oil-soluble metal salt obtained by overbasing an oil-soluble metal salt with an alkaline earth metal carbonate. EP 1 736 529 A1 discloses a lubricating oil composition for a diesel engine. Citation List Patent Literature Patent Literature 1: WO 2015/114920 A1Patent Literature 2: JP H7-316577 APatent Literature 3: JP 2014-152301 APatent Literature 4: JP 2015-143304 APatent Literature 5: JP 2015-140354 APatent Literature 6: JP 5727701 BPatent Literature 7: WO 2015/111746 A1Patent Literature 8: WO 2015/042337 A1Patent Literature 9: WO 2015/042340 A1Patent Literature 10: WO 2015/042341 A1Patent Literature 11: WO 2015/023559 A1Patent Literature 12: WO 2016/043333 A1Patent Literature 13: WO 2017/099052 A1Patent Literature 14: WO 2017/057361 A1Patent Literature 15: WO 2014-196517 A1 Non Patent Literature Non Patent Literature 1: Takeuchi, K.; Ito, Y.; Fujimoto, K., "Investigations of Engine Oil Effect on Abnormal Combustion in Turbocharged Direct Injection - Spark Ignition Engines (Part 1) - Preventing or Contributing to Low-Speed Pre-Ignition through Effects of Engine Oil Additives", Proceedings of JSAE Annual Congress 2012, No. 70-12, pp. 1-4, 20125101 (May 25, 2012, JSAE Annual Congress (Spring)).Non Patent Literature 2: Fujimoto, K.; Yamashita, M.; Kaneko, T.; Takeuchi, K.; Ito, Y.; Matsuda, H., "Investigations of Engine Oil Effect on Abnormal Combustion in Turbocharged Direct Injection - Spark Ignition Engines (Second Report) - Correlation between Auto-Ignition Temperature of Engine Oil and Low-Speed Pre-Ignition Frequency", Proceedings of JSAE Annual Congress 2012, No. 70-12, pp. 5-8, 20125109 (May 25, 2012, JSAE Annual Congress (Spring)).Non Patent Literature 3: Okada, Y.; Miyashita, S.; Yaguchi, H.; Izumi, Y.; Aoki, F., "Study of LSPI Occurring Mechanism from Deposit", Proceedings of JSAE Annual Congress 2014, No. 94-14, pp. 11-16, 20145633 (October 22, 2014, JSAE Annual Congress (Autumn)).Non Patent Literature 4: Seki, Y.; Negoro, K.; Sato, Y.; Matsuura, K.; Nishi, M.; Iida, N., "An Analysis of the mechanism of Pre-ignition in turbo-charged Direct injection spark ignition engines", Proceedings of JSAE Annual Congress 2014, No. 94-14, pp. 23-28, 20145825 (October 22, 2014, JSAE Annual Congress (Autumn)).Non Patent Literature 5: Fujimoto, K.; Yamashita M.; Hirano, S.; Kato, K., et al., "Engine Oil Development for Preventing Pre-Ignition in Turbocharged Gasoline Engine", SAE Int. J. Fuels Lubr. 2014, 7(3), 869-874. doi:10.4271/2014-01-2785.Non Patent Literature 6: Yasueda, S.; Tozzi, L.; Sotiropoulou, E., "Predicting Autoignition caused by Lubricating Oil in Gas Engines", 27th CIMAC Congress Paper No. 37, May 2013, ShanghaiNon Patent Literature 7: Yasueda, S.; Kuboyama, T.; Matsumura, M., et al., "The Examination on the Main Contributing Factors of Lube Oil Pre-Ignition", 28th CIMAC Congress paper No. 147, June 2016, Helsinki SUMMARY Technical Problem A turbocharged downsized engine may suffer a phenomenon that ignition occurs in a cylinder earlier than expected (i.e., prior to spark ignition) when torque increases in a low speed range (LSPI: Low Speed Pre-Ignition). LSPI increases energy loss, and leads to restrictions on improvements of fuel efficiency and low-speed torque. It is suspected that an engine oil has an influence on occurrence of LSPI. As regards marine engines, IMO (International Maritime Organization) has decided to tighten regulations over exhaust gases from marine vessels in view of environmental preservation. For example, it has been obliged to use a fuel having a sulfur content of no more than 0.1 mass% (ULSFO) in regulated sea areas called ECA (Emission Control Area) since 2015, and a further regulation, which obliges marine vessels without an exhaust gas desulfurizer to use a fuel having a sulfur content of no more than 0.5 mass % even in g