JP2015500367A - Engine lubricant for hybrid or micro hybrid vehicles - Google Patents

Abstract

A lubricant composition that enables reliable operation of an internal combustion engine of a hybrid vehicle or a micro-hybrid vehicle with a stop-and-start system and use thereof. By using a lubricating composition comprising at least one base oil and at least one organomolybdenum compound, the wear of a bearing of an internal combustion engine of a hybrid drive vehicle and / or a micro hybrid drive vehicle is reduced, Lubricate the metal surface and / or polymer surface and / or amorphous carbon surface of the internal combustion engine. [Selection figure] None

Description

  The present invention relates to a lubrication technique for an engine of a hybrid drive vehicle or a micro hybrid drive vehicle, and particularly to a lubrication technique for an engine of a micro hybrid drive vehicle equipped with a “stop and start” system.

  Vehicles equipped with electric motors have been developed for the purpose of environmental considerations and fossil energy resource savings. However, the electric motor not only has a limited output and range, but also requires a very long time to charge the battery.

  On the other hand, the hybrid drive system addresses the above problem by connecting and using a general internal combustion engine and an electric motor in a series system, a parallel system, or a combination thereof.

  In a hybrid vehicle, starting is performed by an electric motor. Until the speed reaches about 50 km / hour, the motive power of the vehicle is supplied by the electric motor. When this speed is exceeded, or when high acceleration is required, the engine is switched to the internal combustion engine. When the speed is reduced or when the vehicle is stopped, the internal combustion engine is stopped and switched to the electric motor. Therefore, the number of times of stopping / restarting the internal combustion engine of the hybrid vehicle is significantly greater than the number of times of stopping / restarting the internal combustion engine of a normal vehicle.

  Some vehicles are also provided with an automatic stop / restart device (hereinafter sometimes referred to as a “stop and start” system). In general, such vehicles are referred to as “micro hybrid” vehicles. In fact, such a vehicle is provided with a starter alternator or a heavy duty starter in order to reliably stop and restart the internal combustion engine when the vehicle is stopped, in addition to the internal combustion engine. Therefore, like the internal combustion engine of a hybrid vehicle, the number of times of stopping and restarting the internal combustion engine of a micro hybrid vehicle equipped with a “stop and start” system is also larger than the number of times of stopping and restarting the internal combustion engine of a normal vehicle. There will be much more.

  Thus, the internal combustion engine of a hybrid vehicle or micro hybrid vehicle experiences much more stops / restarts during its life than the internal combustion engine of a normal vehicle. Therefore, particularly in the long term, there is a tendency to cause wear problems specific to the internal combustion engine of hybrid vehicles and micro hybrid vehicles. Such specific wear problems are particularly prominent in connecting rod bearings. Therefore, it has been recognized that the wear on the internal combustion engine bearings of hybrid and micro hybrid vehicles is much more serious than the wear on the internal combustion engine bearings of normal vehicles.

  As is well known to those skilled in the art, as a means for reducing the wear of the bearing as a first object, it is considered to increase the viscosity of the lubricant in order to improve the retention of the oil film on the surface of the bearing.

  In addition, antiwear compositions containing friction modifiers have been proposed.

  Patent Document 1 discloses the use of engine oil having a kinematic viscosity of 16 to 27 cSt at 100 ° C. measured according to the ASTM D445 standard, and the maximum torque measured at 1,000 to 3,000 rpm. In order to lubricate an internal combustion engine of a hybrid drive vehicle exceeding 1,000 Nm, the use of said oil comprising at least one ester represented by formula (a) is described. Here, the ester represented by the formula (a) is an organic friction modifier. By using such specific organic friction modifiers, wear of the connecting rod bearings of the engine can be reduced. However, there is still room for improvement in reducing wear.

  Patent Document 2 and Patent Document 3 describe compositions containing an organomolybdenum compound as a friction modifier. However, neither document teaches or suggests that the composition be used to reduce the wear on the bearings of internal combustion engines in hybrid and micro hybrid vehicles. Furthermore, it is a well-known fact for those skilled in the art that the wear resistance solving means applicable to the internal combustion engine of a conventional vehicle cannot be used as it is for the internal combustion engine of a hybrid vehicle or a micro hybrid vehicle.

International Publication No. 2011/045773 International Publication No. 2010/046620 US Patent Application Publication No. 2011/071062

  Therefore, a lubricant composition that enables reliable operation of an internal combustion engine of a hybrid vehicle or a micro hybrid vehicle equipped with a stop-and-start system, and in particular, a lubricant capable of reducing wear of the internal combustion engine. There is a need for the development of a composition, and more particularly, a lubricant composition that can reduce the wear of bearings and connecting rod bearings of the internal combustion engine.

  Applicant has surprisingly found that when a lubricant composition comprising a particular inorganic friction modifier is used for an internal combustion engine of a hybrid drive vehicle or a micro hybrid drive vehicle with a stop-and-start system, the lubricant Bearing wear present in the internal combustion engine can be greatly reduced without increasing the viscosity of the composition, and such lubricants are available under actual conditions, thus reducing the life of the internal combustion engine. It has been found that it is possible to increase the interval of replacement of internal combustion engine parts.

  The present invention relates to the use of a lubricating composition comprising at least one base oil and at least one organomolybdenum compound. Such use reduces the wear on the bearings of internal combustion engines of hybrid and / or micro hybrid drive vehicles, and lubricates the metal and / or polymer and / or amorphous carbon surfaces of the internal combustion engine. Is for use.

  The present invention includes at least one base oil and at least one organomolybdenum compound to reduce bearing wear of an internal combustion engine of a hybrid drive vehicle and / or a micro hybrid drive vehicle, and to provide a metal for the internal combustion engine. The present invention relates to a lubricant composition for lubricating a surface and / or a polymer surface and / or an amorphous carbon surface.

  Preferably, the starter alternator or the heavy duty starter is provided in the micro hybrid drive vehicle.

  Preferably, the use of the lubricant composition can reduce the wear of the internal combustion engine, in particular, the wear of the bearing of the internal combustion engine, and more particularly, the connecting rod bearing of the internal combustion engine. Wear can be reduced.

  Preferably, the life of the internal combustion engine can be increased by using the lubricant composition, in particular, the life of the bearing of the internal combustion engine can be increased, and more particularly, the connecting rod bearing of the internal combustion engine. Can increase the lifespan.

  Preferably, by using the lubricant composition, it is possible to extend the replacement interval of the components of the internal combustion engine, in particular, it is possible to extend the replacement interval of the bearings of the internal combustion engine, more particularly, the internal combustion engine. The exchange interval of the connecting rod bearing of the engine can be extended.

  Preferably, in the lubricant composition, the organomolybdenum compound is 0.1% to 10%, more preferably 0.5% to 8%, and still more preferably, in mass%, based on the total mass of the lubricant composition. 1 to 5%, still more preferably 2 to 4%.

  Preferably, the organomolybdenum compound is a single or mixture of organomolybdenum compounds selected from molybdenum dithiocarbamates and / or molybdenum dithiophosphates.

  In one embodiment, the organomolybdenum compound is selected from molybdenum dithiocarbamates represented by the following formula (I).

[Wherein R ₁ , R ₂ , R ₃ and R ₄ are independently of each other, preferably a saturated or unsaturated linear alkyl group having 4 to 18 carbon atoms, more preferably 8 to 13 carbon atoms. Or it is a branched alkyl group. ]

  In another embodiment, the organomolybdenum compound is selected from molybdenum dithiophosphates represented by the following formula (II):

[Wherein R ₅ , R ₆ , R ₇ and R ₈ are independently of each other preferably a saturated or unsaturated linear alkyl group having 4 to 18 carbon atoms, more preferably 8 to 13 carbon atoms. Or it is a branched alkyl group. ]

  In one embodiment, the metal surface is an alloy.

  Preferably, the alloy is steel.

  Preferably, the alloy includes tin (Sn), lead (Pb), copper (Cu), aluminum (Al), cadmium (Cd), silver (Ag), or zinc (Zn) as a base element.

  Preferably, the alloy includes lead (Pb) and copper (Cu).

  Preferably, the polymer surface comprises polytetrafluoroethylene.

  Preferably, the lubricant composition has a kinematic viscosity at 100 ° C. measured in accordance with ASTM D445 standard of 5.6 to 12.5 cSt.

  The subject of the present invention is to reduce the wear on the bearings of the internal combustion engine of hybrid and micro hybrid drive vehicles and to lubricate the internal combustion engine.

Here, the hybrid drive vehicle means a vehicle that uses two different types of energy storage sources as energy storage sources capable of moving the vehicle. Specifically, a hybrid vehicle is a vehicle that combines an internal combustion engine with an electric motor that participates in the generation of the driving force of the vehicle. The operating principle of a hybrid vehicle is as follows:
-In the stationary phase (phase in which the vehicle is not moving), both types of engines are stopped;
-At start-up, an electric motor drives the vehicle to a high speed (25 km / h or 30 km / h);
-Switch to internal combustion engine when high speed is reached;
If it is desired to obtain a high acceleration, it is possible to obtain an acceleration of an engine having a comparable output or an acceleration of an engine having a higher output by starting both types of engines simultaneously;
-Optionally, use kinetic energy to charge the battery during deceleration and braking phases.

  Thus, the internal combustion engine of a hybrid vehicle will experience a much greater number of stops / restarts during its life than the internal combustion engine of a normal vehicle (“stop and start” phenomenon).

  A micro-hybrid drive vehicle is equipped with an internal combustion engine, but not an electric motor like a hybrid vehicle, and a starter alternator that reliably stops and starts the internal combustion engine when the vehicle is stopped or restarted. A stop-and-start system using a heavy-duty starter means a vehicle that has achieved “hybrid” properties.

  As a more preferred configuration, the present invention relates to a lubrication technique for an internal combustion engine of a vehicle including a hybrid system or a micro hybrid system in an urban environment where the stop-and-start phenomenon and the accompanying wear increase.

  The wear caused by repeated stop and restart is found in various parts that come into contact with the lubricant. Such parts: piston; piston ring; piston pin; piston pin boss; small end; large end; connecting rod bearing; crank pin; journal; trunnion; crankshaft bearing; crank bearing, journal bearing or main bearing; Oil pump gears, gear systems, camshafts, camshaft bearings, cam followers, rocker arm rollers, hydraulic valve lifters, turbocharger shafts, turbocharger bearings, and the like.

  In an automobile engine, there is a stationary portion including an engine block, a cylinder head, a cylinder head gasket, a liner, and various parts for ensuring the assembly structure and sealing performance of these parts. Automotive engines also have moving parts including a crankshaft, a connecting rod, a connecting rod bearing, a piston, and a piston ring.

  The role of the connecting rod (connection rod) is to transmit the force received by the piston to the crankshaft and convert the reciprocating linear motion into a unidirectional rotational motion.

  The connecting rod has two circular holes, one is a small diameter hole referred to as a small end hole, and the other is a large diameter hole referred to as a large end hole. The main body portion of the connecting rod connecting the small end portion and the large end portion is located between these two holes.

  The small end portion is engaged with the piston pin so as to surround the piston pin. The friction between these small ends and the piston pin is a circle that is interposed between these two moving parts, coated with or made of a wear resistant metal (eg bronze). Reduced by bushing or bearings (mostly needle roller bearings).

  The large end is engaged with the crank pin so as to surround the crank pin of the crank shaft. The friction between the large end portion and the crank assembly is reduced by an oil film existing between the large end portion and the crank pin and a bearing interposed therebetween. The bearing in this case is referred to as a large end bearing.

  The crankshaft is a rotating member. The crankshaft is held in place by a predetermined number of bearings called journals. For this rotating member, the crankshaft serves as a fixed member and surrounds a crankshaft journal which is a movable part. Lubrication between these two members is essential, and bearings are also installed to withstand the forces that act. The bearing in this case is called a journal bearing (or a crank bearing or a main bearing).

  The role of the large end bearing or journal bearing is to rotate the crankshaft appropriately. These bearings are in the form of a semi-cylindrical thin shell. These bearings are parts that are greatly affected by the lubrication state. When contact occurs between the bearing and the rotating shaft (or between the bearing and the crankpin or between the bearing and the journal), the energy released due to the configuration results in significant wear and, in some cases, damage to the engine. May also occur. The generated wear further amplifies this phenomenon and makes contact even more serious.

  When stop / restart is repeated as in a hybrid drive vehicle or a micro hybrid drive vehicle, the oil film is repeatedly ruptured / reformed in the bearing. That is, every time stop / restart is performed, contact occurs at the metal-metal interface. Such frequent contact is a major problem for bearings.

  There are various types of bearing wear in engines. Various types of wear that can occur in engines: adhesive wear (ie, wear due to metal-metal contact); abrasive wear; corrosive wear; fatigue wear; complex forms of wear (contact corrosion, cavitation erosion, electrical wear, etc.) ); Among them, the bearing provided in the engine is liable to cause adhesive wear. While the present invention is very suitable for reducing this type of wear, it is also suitable for the other types of wear described above.

  The surface subjected to wear, specifically, the surface of the bearing subjected to wear is a metal surface or a metal surface coated with another material layer, and such a different material layer includes a polymer layer. And amorphous carbon layers. When the oil film becomes insufficient, contact occurs at the interface between such surfaces and wear occurs.

  The metal surface may be a surface made of a pure metal such as tin (Sn) or lead (Pb). In most cases, the metallic surface is a metal-based alloy comprising a metal and at least one other metal or non-metal element. A frequently used alloy is steel, that is, an alloy of iron (Fe) and carbon (C). In most cases, the bearing used in the automotive industry is a bearing whose bearing part is made of steel, which may or may not be covered with another metal alloy.

  In the present invention, examples of other metal alloys that can constitute the metal surface include alloys containing tin (Sn), lead (Pb), copper (Cu), or aluminum (Al) as a base element. In the present invention, other examples of the base element of the metal alloy that can constitute the metal surface include cadmium (Cd), silver (Ag), and zinc (Zn). In addition to such base elements, the alloys include antimony (Sb), arsenic (As), chromium (Cr), indium (In), magnesium (Mg), nickel (Ni), platinum (Pt) and silicon. Another element selected from (Si) may also be included.

  Preferred alloys are those based on the following combinations: Al / Sn; Al / Sn / Cu; Cu / Sn; Cu / Al; Sn / Sb / Cu; Pb / Sb / Sn; Cu / Pb; Sn / Cu; Al / Pb / Si; Pb / Sn; Pb / In; Al / Si; Al / Pb; Among these, more preferred combinations are: Sn / Cu; Sn / Al; Pb / Cu; or Pb / Al.

  Copper-based alloys and lead-based alloys are preferred alloys. They are sometimes referred to as copper-lead alloys and white metal alloys.

  In another embodiment, the surface affected by wear is a polymer-based surface. In most cases, the bearing is made of steel and has such a polymer surface. Examples of the polymer that can be used include: thermoplastic polymers such as polyamide and polyethylene; fluoropolymers such as tetrafluoroethylene (especially polytetrafluoroethylene (PTFE)); thermosetting polymers such as polyimide and phenolic plastics; Can be mentioned.

In yet another embodiment, the surface affected by wear is an amorphous carbon surface. In most cases, the bearing is made of steel and has such an amorphous carbon surface. The surface made of amorphous carbon has sp ² hybrid carbon and sp ³ hybrid carbon, and is also called DLC, diamond-like carbon, diamond-like coating, or the like.

  The surface affected by wear is not a ceramic surface. Such ceramic coatings are very rarely used in the vehicle field due to their brittleness and the recycling requirements imposed on modern engines.

  The lubricant composition used in the present invention contains at least one inorganic friction modifier selected from organic molybdenum compounds. As the name indicates, an organomolybdenum compound is a molybdenum-carbon-hydrogen based compound, but may contain sulfur, phosphorus, and even oxygen and nitrogen.

  Examples of organic molybdenum compounds according to the present invention include: molybdenum dithiophosphates; molybdenum dithiocarbamates; molybdenum dithiophosphinates; molybdenum xanthates; molybdenum thioxanthates; Various organic molybdenum complex compounds such as rates; molybdenum ester compounds; molybdenum amide compounds; Such organic molybdenum complex compounds are prepared by reacting molybdenum oxides or ammonium molybdates with oils, glycerides, fatty acids or fatty acid derivatives (eg, fatty acid esters, fatty acid amines, fatty acid amides, etc.). Can do.

  Organomolybdenum compounds suitable for incorporation in the lubricant composition according to the invention are described, for example, in paragraphs [0036] to [0062] of EP-A-2078745.

  Suitable organomolybdenum compounds are molybdenum dithiophosphates and / or molybdenum dithiocarbamates.

  In particular, molybdenum dithiocarbamates have been found to be extremely effective in reducing bearing wear. Such molybdenum dithiocarbamates are described by the following general formula (I).

[Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a saturated or unsaturated linear alkyl group having 4 to 18 carbon atoms (preferably 8 to 13 carbon atoms) or It is a branched alkyl group. ]

  Similar effects were found for molybdenum dithiophosphates. Such molybdenum dithiophosphates are described by the following general formula (II):

[Wherein R ₅ , R ₆ , R ₇ and R ₈ are each independently a saturated or unsaturated linear alkyl group having 4 to 18 carbon atoms (preferably 8 to 13 carbon atoms) or It is a branched alkyl group. ]

  In the lubricant composition according to the present invention, the organomolybdenum compound is contained in an amount of 0.1 to 10%, preferably 0.5 to 8%, more preferably, based on the total mass of the lubricant composition. It may contain 1 to 5%, more preferably 2 to 4%.

  The applicant has surprisingly found that in the engine of a hybrid vehicle or a micro hybrid vehicle, the organic molybdenum compound as described above is blended in the engine oil without changing the fuel consumption or reducing the fuel consumption. It has been demonstrated that the wear of connecting rod bearings can be greatly reduced.

  The organomolybdenum compound that can be used in the present invention is molybdenum in an amount of 1 to 30%, preferably 2 to 20%, more preferably 4 to 10%, based on the total mass of the organomolybdenum compound. Preferably it has 5 to 8%.

  The organomolybdenum compound that can be used in the present invention is 1 to 30%, preferably 2 to 20%, more preferably 4 to 10%, and more preferably 4 to 10% by mass, based on the total mass of the organomolybdenum compound. Preferably it has 5 to 8%.

  The organomolybdenum compound that can be used in the present invention has a phosphorus content of 1 to 10%, preferably 2 to 8%, more preferably 3 to 6%, based on the total mass of the organomolybdenum compound. Preferably it has 4 to 5%.

  In the lubricant composition used in the present invention, at least one base oil is contained in an amount of 50 to 90%, preferably 60 to 85%, more preferably, based on the total mass of the lubricant composition. May comprise 65-80%, more preferably 70-75%.

  The at least one base oil blended in the lubricant composition according to the present invention is a mineral-derived or synthetic-derived base oil of the API classification group 1-5 summarized below (or an equivalent of the ATIEL classification). Or a mixture of such base oils.

  The base oil may be a plant-derived, animal-derived or mineral-derived base oil. The mineral-derived base oil according to the present invention is obtained by subjecting crude oil to atmospheric distillation or vacuum distillation, followed by solvent extraction, deasphalting, solvent dewaxing, hydrogenation, hydrocracking / hydroisomerization, hydrofinishing, etc. All types of base oils obtained by passing through the following refining steps can be included.

  The base oil blended in the lubricant composition according to the present invention may be a base oil derived from synthesis. Examples of such synthetically derived base oils include: specific esters of carboxylic acids and alcohols; polyalphaolefins; and the like. When using poly α olefin as a base oil, the poly α olefin is derived from, for example, a monomer having 4 to 32 carbon atoms (for example, octene, decene, etc.), and conforms to the ASTM D445 standard. The viscosity at 100 ° C. is 1.5 to 15 cSt. The polyalphaolefins typically have a weight average molecular weight (measured according to the ASTM D5296 standard) of 250 to 3,000.

  A mixture of a synthetic base oil and a mineral base oil may be used. Such a mixture is used, for example, when it is desired to formulate a multigrade oil that can prevent problems during cold start (cold start).

  The lubricant composition may contain a viscosity index improving polymer (VI improver). Examples of such viscosity index enhancing polymers include: ester polymers; olefin copolymers (OCP); styrene-based, butadiene-based, or isoprene-based homopolymers or copolymers; polymethacrylate (PMA);

  In the lubricant composition according to the present invention, the viscosity index-improving polymer (VI improver) is about 0 to 20% or about 5 to 15% by mass with respect to the total mass of the lubricant composition. Or it may contain about 7 to 10%. Such viscosity index improving polymers are selected from, for example: ester polymers; olefin copolymers (OCP); styrene-based, butadiene-based, or isoprene-based homopolymers or copolymers; and polymethacrylates (PMA).

  Preferably, the lubricant composition according to the present invention has a viscosity index (ie VI value) measured according to the ASTM D2270 standard of greater than 130, more preferably greater than 140, even more preferably greater than 150.

  Preferably, the lubricant composition according to the present invention has a kinematic viscosity (KV100) at 100 ° C. measured according to ASTM D445 standard of 3.8 to 26.1 cSt, more preferably 5.6 to 12 .5 cSt. The latter viscosity value corresponds to grade 20 (5.6 to 9.3 cSt) or grade 30 (9.3 to 12.5 cSt) at high temperature in the SAE J300 classification.

  Preferably, the lubricant composition according to the present invention is a multi-grade engine oil according to SAE J300 classification, having a low temperature viscosity grade of grade 0W or 5W and a high temperature viscosity grade of grade 20 or 30. is there.

  The engine lubricant composition used in the present invention may further contain any kind of lubricant for making the lubricant composition suitable for use as an engine oil. Such lubricants may be added separately and / or for commercial lubricant formulations that meet performance levels defined by the ACEA (European Automobile Manufacturers Association) and / or API (American Petroleum Institute). It may be contained in the package additive. Such a package additive (ie, additive composition) may be a concentrate containing about 30% by weight of a diluent base oil.

  That is, the lubricant composition according to the present invention includes, for example: antiwear / extreme pressure agent; antioxidant; overbased detergent, non-overbased detergent; cloud point depressant; dispersant; A thickener; and the like. It should be noted that these additives are merely specific examples, and are not limited thereto.

  The antiwear / extreme pressure agent forms a protective film by being adsorbed on the surface to be protected and protects the surface from friction. The most commonly used antiwear and extreme pressure agents are zinc dithiophosphates (ZnDTP). There are various other antiwear / extreme pressure agents such as phosphorus-containing, sulfur-containing, nitrogen-containing, chlorine-containing, and boron-containing compounds.

Although there are a wide variety of antiwear agents, the antiwear agents most commonly formulated in engine oils are phosphorus-containing sulfur-based antiwear agents such as metal alkylthiophosphates, specifically zinc alkylthiophosphates. More specifically, zinc dialkyldithiophosphates (ZnDTP) s. Among them, preferred compounds are those represented by the formula: Zn ((SP (S) (OR ₉ ) (OR ₁₀ )) ₂ , wherein R ₉ and R ₁₀ are preferably saturated or unsaturated having 1 to 18 carbon atoms. It is a straight chain alkyl group or a branched chain alkyl group.] The lubricant composition according to the present invention generally contains the ZnDTP with respect to the total mass of the lubricant composition. About 0.1 to about 2%.

  Other frequently used antiwear agents include amine phosphates, polysulfides, especially sulfur-containing olefins, and the like.

  In the engine lubricant composition according to the present invention, the antiwear / extreme pressure agent is generally 0.5 to 6%, preferably 0.7 to 2%, based on the total mass of the lubricant composition. , More preferably 1 to 1.5%.

  The antioxidant delays the deterioration of the oil in use, and suppresses the formation of deposits (sediment) and sludge due to the deterioration of the oil, or the increase in the viscosity of the oil. Antioxidants act as radical inhibitors or hydroperoxide decomposers. Examples of frequently used antioxidants include phenolic and amino antioxidants.

  The phenolic antioxidant may be ashless, or may be a neutral metal salt or a basic metal salt. Typical phenolic antioxidants include sterically hindered (hindered) hydroxy groups, such as compounds having two hydroxy groups in the ortho or para positions, respectively, And compounds having a phenol moiety substituted with 6 or more alkyl groups.

Another type of antioxidant is an amino compound. Amino compounds can be used alone or optionally in combination with phenolic compounds. Typical examples of amino-based antioxidants include: an aromatic amine represented by the formula: R ₁₁ R ₁₂ R ₁₃ N [wherein R ₁₁ is an aliphatic group or an optionally substituted aromatic group. R ₁₂ is an optionally substituted aromatic group, R ₁₃ is hydrogen, an alkyl group, an aryl group, or a group represented by the formula: R ₁₄ S (O) _x R ₁₅ (wherein R 12 ₁₄ and R ₁₅ are an alkylene group, an alkenylene group or an aralkylene group, and x is 0, 1 or 2. ]; Etc. are mentioned.

  In addition, sulfurized alkylphenols, alkali metal salts thereof, alkaline earth metal salts thereof, and the like can also be used as antioxidants.

  Still other types of antioxidants include oil-soluble copper compounds such as copper thiophosphates; copper dithiophosphates; copper and carboxylic acid salts; copper dithiocarbamates; copper sulfonates; copper phenates; Acetonates; and the like. Copper (I) and copper (II) salts of succinic acid or succinic anhydride may also be used.

  In the engine lubricant composition according to the present invention, the above-mentioned at least one antioxidant is generally 0.1% to 5% by mass, preferably 0.1% to 5%, preferably based on the total mass of the lubricant composition. It may contain 0.3-2%, more preferably 0.5-1.5%.

  Detergents reduce oxidation deposits on the surface of metal parts by dissolving oxidation and combustion by-products, and neutralize specific acidic impurities that are generated by combustion and present in oil. To do.

  A typical detergent often used in formulating a lubricant composition is an anionic compound having a long lipophilic hydrocarbon chain and a hydrophilic head. The metal cation bonded thereto is an alkali metal or alkaline earth metal cation.

  Preferably, the detergent comprises alkali metal salts and alkaline earth metal salts of carboxylic acid, alkali metal salts and alkaline earth metal salts (sulfonates) of sulfonic acid, alkali metal salts and alkaline earth metal salts of salicylic acid ( Salicylates), alkali metal salts and alkaline earth metal salts of naphthenic acid (naphthenates), and alkali metal salts and alkaline earth metal salts of carboxylic acid (phenates), more preferably calcium salts and magnesium salts , Sodium salt and barium salt.

  The metal salt may contain an amount of metal that is approximately equal to or greater than the stoichiometric amount. The detergent in the latter case is a so-called overbased detergent.

  The surplus metal that imparts overbasing to the overbased detergent is a metal salt that cannot be dissolved in oil, such as carbonate, hydroxide, oxalate, acetate, glutamate, and preferably carbonate. It is present in the form of a salt, more preferably calcium carbonate, magnesium carbonate, sodium carbonate or barium carbonate.

  The lubricant composition according to the present invention may contain any type of detergent known to those skilled in the art, whether neutral or overbased. The degree of overbasing of the detergent is represented by the base number (BN) (mg KOH / g) measured according to the ASTM D2896 standard. The neutral detergent has a BN of 0-80 mg KOH / g. On the other hand, the BN of the overbased detergent is typically in the range of 150 mg KOH / g or more, further 250 mg KOH / g or more, or 450 mg KOH / g or more. The BN of the lubricant composition in the case of containing the detergent is also represented by a base number (BN) (mg KOH / g) measured according to ASTM D2896 standard.

  Preferably, the amount of the detergent blended in the engine oil according to the present invention is more preferably 5 to 20 mg KOH / g (per 1 g of engine oil) of BN of the engine oil measured according to ASTM D2896 standard. Is adjusted to 8-15 mg KOH / g.

  Cloud point depressants improve oil behavior at low temperatures by delaying the formation of paraffin crystals. Examples of cloud point depressants include: alkylated polymethacrylates; polyacrylates; polyarylamides; polyalkylphenols; polyalkylnaphthalenes; The lubricant composition according to the present invention may contain the cloud point depressant in an amount of 0.1 to 0.5% by mass in general, based on the mass of the lubricant composition.

  Examples of dispersants include: succinimides; PIB (polyisobutene) succinimides; Mannich bases; The dispersant keeps the insoluble solid impurities composed of oxidation by-products generated during the use of engine oil in suspension and ensures their removal. In general, the lubricant composition according to the present invention may contain the dispersant in an amount of 0.5 to 10%, preferably 1 to 5% by mass based on the total mass of the lubricant composition.

  The present invention further reduces the wear of a bearing of an internal combustion engine of a hybrid drive vehicle and / or a micro hybrid drive vehicle by using a lubricant composition comprising at least one base oil and at least one organomolybdenum compound. It relates to a method for reducing and lubricating metal surfaces and / or polymer surfaces and / or amorphous carbon surfaces of the internal combustion engine. All the features and preferred configurations described for the lubricant composition according to the present invention are also applicable to the method according to the present invention.

(Example)
For engine bearings with a stop-and-start system, the exacerbated wear was simulated by tests that run 12,000 stop / start cycles in 150 hours. In particular:
1) Starting the engine;
2) Run for 10 seconds at idling speed; 3) Stop engine;
Was repeatedly executed.

  The system used in this test is equipped with a 4-cylinder diesel engine with a maximum torque of 200 Nm at 1,750 to 2,500 rpm. This system is a stop-and-start system, and includes a starter alternator between a vehicle clutch and a gear box. In this test, the engine oil was maintained at a temperature of about 100 ° C. Wear was monitored by a common radio tracer method. Specifically, the surface of the connecting rod bearing to be subjected to the wear test is irradiated to increase the radioactivity of the engine oil during the test period, that is, the rate of increase of the irradiated metal particles in the engine oil. It was measured. This increase rate is directly proportional to the wear rate of the bearing.

The damage rate of the reference oil was compared with the damage rate of the test oil, and compared with the reference oil in order to incorporate a positive or negative surface shape correction factor into the damage rate.

  Specifically, the damage rate of all test target oils is compared with the damage rate of the reference oil. Thereby, each damage rate is quantified as a wear rate (%) shown in the line labeled “wear” in Table 1 described later.

  Lubricant composition A is a reference lubricant composition (grade 5W30).

  Lubricant composition B is a lubricant composition containing a known antiwear agent (ZnDTP) and a zinc dithiophosphate compound represented by the following formula (III).

[Wherein, R ₁₆ represents an alkyl group having 1 to 24 carbon atoms. ]

  The lubricant composition C is a lubricant composition containing a known antiwear agent (ZnDTC) and a zinc diamyldithiocarbamate compound.

The lubricant composition D is a lubricant composition of the prior art, specifically, the lubricant composition disclosed in Patent Document 1, which is represented by the general formula (a): R (OH) _m (COOR ′ ( OH) _p (OOCR ″) _q ) _{n wherein} m is 1, p is 0, q is 0, n is 3 and R ′ is an ethyl group. ] The lubricant composition containing the ester organic friction modifier corresponding to.

The lubricant composition E is a lubricant composition according to the present invention, which is an inorganic organic molybdenum compound represented by the general formula (I) [wherein R ₁ , R ₂ , R ₃ and R ₄ are An alkyl group having 13 carbon atoms and / or an alkyl group having 18 carbon atoms. ] As a friction modifier, and the inorganic organic molybdenum compound has 10% by mass of molybdenum with respect to the mass of the compound and 11% by mass of sulfur with respect to the mass of the compound. is there.

The lubricant composition F is a lubricant composition according to the present invention, and is an inorganic organic molybdenum compound represented by the general formula (II) [wherein R ₅ , R ₆ , R ₇ and R ₈ are It is an alkyl group having 8 carbon atoms. ] As a friction modifier, the inorganic organic molybdenum compound has 9% by mass of molybdenum with respect to the mass of the compound, 10.1% by mass of sulfur with respect to the mass of the compound, and phosphorus. It is a lubricant composition which has 3.2 mass% with respect to the mass of the said compound.

  Table 1 below summarizes the mass composition and properties of the lubricant compositions to be tested:

  The base oil used is a mixture of Group 3 base oils (viscosity index 171).

The polymer used is a linear styrene / butadiene polymer having a weight average molecular weight _Mw of 139,700, a number average molecular weight _Mn of 133,000, a polydispersity of 1.1, This is a polymer having a PSSI (Permanent Shear Stability Index) of 15, specifically 8% as an active ingredient in a Group 3 base oil.

  The antioxidant to be used is an amino antioxidant having an alkylarylamine structure.

  The PPD (cloud point depressant) used is of polymethacrylate type.

  Package additives used include antiwear agents, antioxidants, dispersants and common detergents.

  Lubricant composition A is used for reference.

  In the test using the lubricant composition B, significant wear occurred, and this could be confirmed visually (wear rate was 72%). The same can be said for the lubricant composition C (wear rate is 74%). In the lubricant composition D, wear can be reduced by using an organic friction modifier (wear rate is 68%), but there is still room for improvement. On the other hand, in the lubricant composition E and the lubricant composition F, the above results can be improved by using an inorganic friction modifier, and the wear rate is 50% or less.

Claims (15)

  At least one for reducing the wear of the bearings of the internal combustion engine of a hybrid drive vehicle and / or a micro hybrid drive vehicle and for lubricating the metal surface and / or polymer surface and / or amorphous carbon surface of the internal combustion engine Of a lubricating composition comprising a base oil and at least one organomolybdenum compound.   Use according to claim 1, wherein the microhybrid drive vehicle is provided with a starter alternator or a heavy duty starter.   3. Use according to claim 1 or 2 for reducing wear of a connecting rod bearing of an internal combustion engine.   Use according to any one of claims 1 to 3 for use in increasing the life of an internal combustion engine (especially for use in increasing the life of a bearing of an internal combustion engine, more particularly for use in an internal combustion engine). Use to increase the life of connecting rod bearings).   The use according to any one of claims 1 to 4, wherein the use is for extending the exchange interval of the bearing of the internal combustion engine (especially the use for extending the exchange interval of the connecting rod bearing of the internal combustion engine).   The use according to any one of claims 1 to 5, wherein the lubricant composition contains the organic molybdenum compound in an amount of 0.1 to 10% by mass relative to the total mass of the lubricant composition. (Preferably 0.5 to 8%, more preferably 1 to 5%, and still more preferably 2 to 4%).   Use according to any one of claims 1 to 6, wherein the organomolybdenum compound is a single or mixture of organomolybdenum compounds selected from molybdenum dithiocarbamates and / or molybdenum dithiophosphates. The use according to any one of claims 1 to 7, wherein the organomolybdenum compound is selected from molybdenum dithiocarbamates represented by the following formula (I).

[Wherein R ₁ , R ₂ , R ₃ and R ₄ are independently of each other (preferably 4 to 18 carbon atoms, more preferably 8 to 13 carbon atoms), saturated or unsaturated, linear An alkyl group or a branched alkyl group; ] The use according to any one of claims 1 to 7, wherein the organomolybdenum compound is selected from molybdenum dithiophosphates represented by the following formula (II).

[Wherein R ₅ , R ₆ , R ₇ and R ₈ are, independently of one another, preferably a saturated or unsaturated linear chain (preferably having 4 to 18 carbon atoms, more preferably 8 to 13 carbon atoms). An alkyl group or a branched alkyl group; ]   Use according to any one of claims 1 to 9, wherein the metal surface is an alloy.   Use according to claim 10, wherein the alloy is steel.   The use according to claim 10, wherein the alloy is tin (Sn), lead (Pb), copper (Cu), aluminum (Al), cadmium (Cd), silver (Ag) or zinc (Zn) as a base element. Including, use.   Use according to claim 12, wherein the alloy comprises lead (Pb) and copper (Cu).   Use according to any one of claims 1 to 9, wherein the polymer surface comprises polytetrafluoroethylene.   The use according to any one of claims 1 to 14, wherein the lubricant composition has a kinematic viscosity at 100 ° C measured in accordance with ASTM D445 standard of 5.6 to 12.5 cSt. use.