JP2022058477A - Methods for improving oxidative stability of lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for improving oxidative stability of a lubricant composition that is used to lubricate a spark ignition internal combustion engine contained within a powertrain of a hybrid electric vehicle.

SOLUTION: The method comprises a step for introducing a gasoline composition into a combustion chamber of a spark-ignition engine, wherein the gasoline composition is a hydrocarbon basic fuel, the hydrocarbon basic fuel has 10 to 20% by volume of olefin, an olefin having at least 10 carbon atoms of 5% by volume or less, and an aromatic compound having at least 10 carbon atoms of 5% by volume or less, based on a basic fuel, and the hydrocarbon basic fuel has an initial boiling point in a range of 30-40°C, a T10 in the range of 45-57°C, a T50 in the range of 82-104°C, a T90 in the range of 140-150°C, and a final boiling point of 220°C or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a method of improving the oxidative stability of a lubricating composition used to lubricate a spark-ignition combustion engine, wherein the spark-ignition combustion engine is housed in the power train of a hybrid electric vehicle.

Rising costs for hydrocarbon fuels and growing concerns about the environmental impact of carbon dioxide emissions are driving demand for vehicles that are partially or wholly powered by electrical energy.

Hybrid electric vehicles (HEVs) utilize both the electrical energy stored in rechargeable batteries and the mechanical energy normally converted from hydrocarbon-based fuels by conventional internal combustion engines (ICEs). The battery is charged by the ICE during operation and also by recovering kinetic energy during deceleration and braking. This process is provided by many original equipment manufacturers (OEMs) for several automotive models. HEVs typically provide a normal driving experience and have the major advantage of improved fuel economy over traditional ICE-only vehicles. Plug-in hybrid electric vehicles (PHEVs) have similar functionality to HEVs, but in this application the battery can also be connected to the main electrical system to charge the vehicle when it is parked. can. PHEVs typically have a larger battery pack than HEVs, thus providing capacity for some of the full electrical range. Working areas that use an internal combustion engine (ICE) for propulsion may be limited to cruising and intercity driving, but dynamic driving will use electric power and ICE. As a result, the desire for fuel in automobiles can be quite different from what is currently required for conventional ICE or HEV equipped vehicles. For urban environment vehicles, the level of ICE activity will be further reduced due to the increase in EV mode capacity and plug-in charging function. This can result in significantly longer residence times for the contents of the fuel tank as compared to HEVs and conventional ICE vehicles.

Conventional ICE vehicles typically achieve a range of about 600 km (400 miles) for a propulsion system weight of about 200 kg and require about 2 minutes of replenishment time. By comparison, current Li-ion technology-based battery packs that can provide comparable range and useful battery life are believed to weigh about 1700 kg. By adding the weight of the motor, power electronics, and car chassis, the car will be much heavier than the traditional ICE equivalent.

In a conventional ICE vehicle, the engine torque and power transmission from the engine must cover the entire range of vehicle operating dynamics. However, the thermodynamic efficiency of internal combustion engines cannot be fully optimized over a wide range of operating conditions. ICE has a relatively narrow dynamic range. Therefore, a major challenge for original equipment manufacturers (OEMs) is to develop engine technologies and transmission systems that allow engine torque and power transmission from the engine to operate over the full range of vehicle operating dynamics. On the other hand, electromechanical machines can be designed to have a very wide dynamic range, for example, to supply maximum torque at zero speed. This flexibility of control is well recognized as a useful feature in industrial drive applications and offers potential in automotive applications. Within their operating range, electrical machinery can be controlled using high performance electronics to provide the very smooth torque transmission applied to the requirements of demand. However, it may be possible to provide different torque transfer profiles that are more attractive to the driver. Therefore, this could be an area of interest for automotive designers in the future. At higher speeds, electric drive systems tend to be limited by the heat removal capacity of power electronics and the cooling system for the electric motor itself. Further studies on high torque motors at high speeds relate to the mass of rotating parts where very high centrifugal forces can be generated at high speeds. These can be destructive. In HEVs and PHEVs, electric motors can therefore provide only part of the dynamic range. However, this may make it possible to optimize the efficiency of the ICE over a narrower operating range. This offers several advantages in terms of engine design.

Therefore, current hydrocarbon fuels developed for full range ICE may not be optimized or may not be practically beneficial for HEV or PHEV ICE units. Since fuels have been compounded and regulated for traditional ICE vehicles for many years, the degrees of freedom in the compounding space are well understood and can therefore be considered stable. The introduction of hybrid technology in relatively recent years offers an opportunity to consider fuel compounding spaces from a whole new perspective.

In addition, in order to maximize the efficient operation of the HEV or PHEV ICE unit, it is necessary to consider the lubrication composition used to lubricate the ICE in the HEV or PHEV powertrain. Due to the different operating cycles in HEV or PHEV ICE units compared to conventional ICE units, lubrication compositions tend to be exposed to more extreme conditions and greater oxidative stress in HEV / PHEV environments.

In the automotive industry, the "Aunt Minie" driving cycle (a vehicle that is rarely used on short-distance trips without the engine being completely warmed to optimum operating temperature before it stops in cold weather. It is already known to have designed specific requirements for lubricating oil compositions that operate under specific operating conditions, such as simulated operating cycles). In HEV or PHEV ICE units, the engine is frequently stopped and started, so that the ICE is used only for a short time and is not completely warmed up before it is stopped. In general, the ICE of a hybrid vehicle tends to have a high risk of an "Ant Minie" type driving cycle because the ICE is rarely used in the same driving pattern. This means that the crankcase lubricant does not warm completely in the HEV or PHEV and therefore presents severe conditions for oxidation of the lubricant. Decreased oxidative stability of the lubricant can result in increased engine deposits, which in turn can have undesired effects such as reduced fuel economy performance. As mentioned above, this stop / start problem is more serious in HEVs and PHEVs than in traditional ICE units and therefore should be considered carefully to improve the oxidative stability of the lubricant in HEVs / PHEVs. There is a need.

Therefore, in order to maximize the efficient operation of PHEV / HEV vehicles, it is desirable to find a method for improving the oxidative stability of the lubricating composition in PHEV / HEV vehicles.

At the same time, the oxidative stability of the fuel composition also needs to be considered in the case of HEV / PHEV.

WO 2004/11476 discloses a gasoline composition that meets certain parameters whose use as a fuel in a spark-ignition engine results in improved stability of the engine crankcase lubricant. However, this document does not mention the use of such fuels in HEV or PHEV vehicles, or the specific advantages of using such fuels for hybrid vehicles.

International Publication No. 2004/11476

According to the present invention, a method for improving the oxidative stability of a lubricating composition used to lubricate a spark-ignition engine, wherein the spark-ignition engine is included in the power train of a hybrid electric vehicle. The method comprises the step of introducing the gasoline composition into the combustion chamber of a spark-ignition engine, wherein the gasoline composition is a hydrocarbon basic fuel and is 10 to 20% by volume of olefins and 5% by volume based on the basic fuel. An initial boiling point in the range of 30-40 ° C., comprising a hydrocarbon basal fuel containing the following olefins with at least 10 carbon atoms and aromatic compounds with at least 5% by volume of carbon atoms: Methods are provided that include T10 in the range 45-57 ° C, T50 in the range 82-104 ° C, T90 in the range 140-150 ° C, and a final boiling point of 220 ° C or lower.

Surprisingly, it has been found that selecting a gasoline composition that meets certain parameters improves the oxidative stability of the lubricating composition in an HEV or PHEV.

In a spark ignition internal combustion engine fueled by the gasoline composition of the present invention contained in the power train of a hybrid electric vehicle, the light olefin content in combination with T ₁₀ in the range of 38 to 60 ° C. is the engine lubricating oil ( Frequent engine shutdowns and starts in HEVs and PHEVs where ICE is used only occasionally and for a short period of time, which is considered to be an important parameter to achieve improved stability of the crankcase lubricant), is the crankcase lubricant. Means that it does not warm up completely and presents severe conditions for the oxidation of the lubricating oil. The effects of these start / stop driving cycles are more severe in HEV / PHEV vehicles than they are in conventional ICE vehicles. High front-end volatility (low T ₁₀ ) and certain olefin content are believed to reduce the blow-off of harmful combustion gases into the engine crankcase.

"5% by volume or less olefin having at least 10 carbon atoms" and "5% by volume or less aromatic compound having at least 10 carbon atoms" are the hydrocarbon basic fuels based on the basic fuel. It means that the amount of the olefin having 10 or more carbon atoms or the amount of the aromatic compound having 10 or more carbon atoms is contained in the range of 0 to 5% by volume, respectively.

Gasoline contains a mixture of hydrocarbons, the optimum boiling range and distillation curve of which varies with climate and the season of the year. Hydrocarbons in gasoline as defined above are straight-run gasoline, synthetically produced aromatic hydrocarbon mixtures, thermal or catalytically cracked hydrocarbons, hydrocracked petroleum fractions, or catalytically reformed hydrocarbons. , And mixtures thereof can be conveniently derived in a known manner. Oxygen-containing additives may be incorporated into gasoline, which include alcohols (eg, methanol, ethanol, isopropanol, tert-butanol, and isobutanol), and ethers, preferably 5 or more carbon atoms per molecule. Examples thereof include ethers containing, for example, methyl tert-butyl ether (MTBE), or ethyl tert-butyl ether (ETBE). Ethers containing 5 or more carbon atoms per molecule can be used in quantities up to 15% v / v, but when methanol is used, it is only in quantities up to 3% v / v. And a stabilizer is needed. Ethanol also requires a stabilizer, and ethanol can be used from 5% to 10% v / v. Isopropanol can be used up to 10% v / v, tert-butanol up to 7% v / v, and isobutanol up to 10% v / v.

It is preferable to avoid inclusion of tert-butanol or MTBE. Therefore, the preferred gasoline composition of the present invention contains 0-10% by volume of at least one oxygen-containing additive selected from methanol, ethanol, isopropanol, and isobutanol.

Theoretical modeling suggests that the inclusion of ethanol in the gasoline composition of the present invention further improves the stability of the engine lubricant, especially under cooler engine operating conditions. Therefore, the gasoline composition of the present invention preferably contains up to 10% by volume of ethanol, preferably 2 to 10% by volume, more preferably 4 to 10% by volume, for example 5 to 10% by volume of ethanol.

The gasoline composition according to the invention is advantageously lead-free (lead-free), which may be required by law. Where permitted, lead-free anti-knock compounds and / or valve seat retreat protective agent compounds (eg, known potassium salts, sodium salts, or phosphorus compounds) may be present.

The octane number, (R + M) / 2, is generally greater than 85.

Modern gasoline essentially contains a low sulfur fuel, such as less than 200 ppmw of sulfur, preferably less than 50 ppmw of sulfur.

As will be readily appreciated by those of skill in the art, in order to meet the defined parameters, the hydrocarbon basic fuels defined above are known to be mixed with suitable hydrocarbons, such as refinery streams, etc. Can be conveniently prepared with. The olefin content can be increased by including a refinery stream containing a large amount of olefins and / or by adding synthetic components such as diisobutylene in any relative ratio.

Diisobutylene, also known as 2,4,4-trimethyl-1-pentene (Sigma-Aldrich Fine Chemicals), typically brings the sulfated extract of isobutylene from the butene isomer separation process to about 90 ° C. A mixture of isomers (2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene) prepared by heating. Kirk-Othmer, "Encyclopedia
As described in "of Chemical Technology", 4th ^Ed . Vol. 4, Page 725, the yield of the mixture of 80% dimer and 20% trimmer is typically 90%.

Gasoline compositions defined above vary from one or more additives such as antioxidants, corrosion inhibitors, ashless detergents, antifogging agents, dyes, lubricity improvers, and synthetic or mineral oil carrier fluids. Can be contained in. Examples of suitable such additives are generally described in US Pat. No. 5,855,629 and DE-A-199555651.

The additive components can be added separately to the gasoline or mixed with one or more diluents to form an additive concentrate and added together to the basic fuel.

Preferred gasoline compositions for use in the methods of the invention include one or more antioxidants to improve the oxidative stability of the gasoline composition. Any antioxidant additive suitable for use in gasoline compositions can be used herein. Preferred antioxidants for use herein are hindered phenols, such as BHT (butylhydroxytoluene). The gasoline composition preferably contains 10 ppmw to 100 ppmw of the antioxidant.

The preferred gasoline composition used in the method of the present invention has one or more of the following characteristics.
(I) The hydrocarbon basic fuel contains at least 10% by volume of olefin.
(Ii) The hydrocarbon basic fuel contains at least 12% by volume of olefin.
(Iii) The hydrocarbon basic fuel contains at least 13% by volume of olefin.
(Iv) Hydrocarbon basic fuel contains up to 20% by volume of olefin.
(V) Hydrocarbon basic fuel contains up to 18% by volume of olefin.
(Vi) The basic fuel has an initial boiling point (IBP) of at least 28 ° C.
(Vii) The basic fuel has an IBP of at least 30 ° C.
(Viii) The basic fuel has an IBP of up to 42 ° C.
(Ix) The basic fuel has an IBP of up to 40 ° C.
(X) The basic fuel has a T ₁₀ of at least 42 ° C.
(Xi) The basic fuel has a T ₁₀ of at least 45 ° C.
(Xii) The basic fuel has a T ₁₀ of at least 46 ° C.
(Xiii) The basic fuel has a T ₁₀ of up to 58 ° C.
(Xiv) The basic fuel has a T ₁₀ of up to 57 ° C.
(Xv) The basic fuel has a T ₁₀ of up to 56 ° C.
(Xvi) The basic fuel has a T ₁₀ of at least 80 ° C.
(Xvii) The basic fuel has a T ₁₀ of at least 82 ° C.
(Xviii) The basic fuel has a T ₁₀ of at least 83 ° C.
(Xix) The basic fuel has a T ₁₀ of up to 105 ° C.
(Xx) The basic fuel has a T ₁₀ of up to 104 ° C.
(Xxi) The basic fuel has a T ₁₀ of up to 103 ° C.
(Xxii) The basic fuel has a T ₉₀ of at least 135 ° C.
(Xxiii) The basic fuel has a T ₉₀ of at least 140 ° C.
(Xxiv) The basic fuel has a T ₉₀ of at least 142 ° C.
(Xxv) The basic fuel has a T ₉₀ of up to 170 ° C.
(Xxvi) The basic fuel has a T ₉₀ of up to 150 ° C.
(Xxvii) The basic fuel has a T ₉₀ of up to 145 ° C.
(Xxxviii) The basic fuel has a T ₉₀ of up to 143 ° C.
(Xxix) The basic fuel has a final boiling point (FBP) of 200 ° C. or lower.
(Xxxx) The basic fuel has an FBP of 195 ° C or less.
(Xxxx) The basic fuel has an FBP of 190 ° C. or less.
(Xxxxi) The basic fuel has an FBP of 185 ° C or less.
(Xxxxii) The basic fuel has an FBP of 180 ° C or less.
(Xxxx) The basic fuel has an FBP of 175 ° C or less.
(Xxxxv) The basic fuel has an FBP of 172 ° C or less.
(Xxxxvi) The basic fuel has an FBP of at least 165 ° C.
(Xxxxvii) The basic fuel has an FBP of at least 168 ° C.

Examples of preferred combinations of the above features are (i) and (iv); (ii) and (v); (iii) and (v); (vi), (viii), (x), (xii). , (Xvi), (xix), (xxiii), (xxv), and (xxix); (Xxvi), and (xxxxi); and (vii), (ix), (xii), (xv), (xviii), (xxi), (xxiv), (xxxvii), (xxxvi), and (xxxvii). Can be mentioned.

The use of the gasoline compositions described herein as fuel for spark-ignition engines in PHEVs or HEVs, in addition to improving the stability of engine lubricants (crankcase lubricants), has several. It can give one of the benefits. These advantages include reduced oil change frequency, reduced engine wear, such as engine bearing wear, engine component wear (eg, camshaft and piston crank wear, etc.), improved acceleration performance, higher maximum power, and / Or improvement of fuel efficiency can be mentioned.

Accordingly, the present invention further relates to the gasoline as defined above as a fuel for a spark-ignition engine to improve the oxidative stability of the engine crankcase lubricating oil and / or reduce the frequency of engine lubricating oil replacement. Providing the use of the composition, the spark-ignition engine is included within the powertrain of the hybrid electric vehicle.

The present invention will be understood from the following exemplary embodiments, where temperature is in degrees Celsius and parts, percentages and ratios are by volume, unless otherwise indicated. One of skill in the art will readily appreciate that various fuels are prepared in a known manner from a known refinery stream and thus are easily reproducible from knowledge of a given composition parameter.

In the examples, the oxidative stability test of the lubricating oil in the engine fueled by the test fuel was performed using the following procedure.

Bench engine, Renault Megane (K7M702) 1.6 liter, 4-cylinder spark ignition type (gasoline) engine is honed to increase the leakage rate of combustion gas to increase the cylinder inner diameter, and the end of the piston ring. Was modified by polishing to increase the butt gap. In addition, a bypass pipe was installed between the cylinder head wall above the engine valve deck and the crankcase to provide an additional path for combustion gas to leak into the crankcase. A rocker arm cover with a jacket (RAC) was installed to facilitate control of the environment surrounding the engine valve train.

The engine was thoroughly cleaned before and during each test to remove any trace of possible contamination. The engine was then filled with 15W / 40 engine oil that meets the API SG specifications and the cooling system for both engine coolant and RAC coolant was filled with a 50:50 water: antifreeze mixture.

続いて、表１の段階３を１０分のアイドル期間（８５０±１００ｒｐｍ）の間に２５ｇの
オイル試料を取り出す修正段階で置き換えたオイルサンプリングサイクルを行った。（２日毎および７日目（のみ）に試料を取り出した）。次いで、エンジンを停止し、２０分間放置した。次の１２分間、オイルディップスティックの読みをチェックし、エンジンオイルを補充した（試験中のみ、試験終了時ではない）。この４５分間の段階の最後の３分間に、エンジンを再始動した。 Engine tests were performed according to Table 1 for 7 days according to a test cycle in which each 24-hour period included 5 4-hour cycles.

Subsequently, an oil sampling cycle was performed in which step 3 in Table 1 was replaced with a modification step in which a 25 g oil sample was taken out during an idle period (850 ± 100 rpm) of 10 minutes. (Samples were taken out every 2 days and on the 7th day (only)). Then the engine was stopped and left for 20 minutes. For the next 12 minutes, the oil dipstick readings were checked and engine oil was replenished (during the test only, not at the end of the test). During the last 3 minutes of this 45 minute phase, the engine was restarted.

Test measurements of oil samples were performed to determine heptane insoluble material (based on DIN 51365 except that oleic acid was not used as a coagulant), total acid value (TAN) (based on IP177), total basic value (based on IP177). TBN) (according to ASTM D4739) and the amount of wear metal (Sn, Fe, and Cr) (according to ASTM 5185 except that the sample was diluted 20-fold with white spirit instead of 10-fold) were evaluated. The TAN / TBN crossover point was calculated from the TAN and TBN values (unit: KOHg / lubricating oil g) (test time).

Example 1
Three hydrocarbon basic fuel gasolines were tested. Comparative Example A was a basic fuel widely used as a fuel sold in the Netherlands in 2002. Comparative Example B corresponds to Comparative Example A, but in order to increase the aromatic compound, a heavy platform (high boiling point fraction of refinery steam produced by modifying naphtha on a platinum catalyst) was used. Added. Example 1 corresponds to Comparative Example A, but light cat cracking gasoline (a low boiling point fraction of the refinery stream produced by catalytic decomposition of heavier hydrocarbons) was added to increase olefins. The sulfur content of the fuel was adjusted to 50 ppmwS by adding dimethyl sulfide as needed to eliminate possible effects from differences in sulfur levels.

The obtained fuel had the characteristics shown in Table 2.

The test results for these fuels are shown in Table 3.

The time point at which the TAN / TBN crossover occurs is considered to be an indicator of the time point when significant oxidative changes are occurring in the oil.

The above results show that the use of the fuel of Example 1 has a very beneficial effect on the oxidative stability of the crankcase lubricating oil, extending the lubricating oil life and reducing the frequency of engine lubricating oil replacement (extending the service interval). And well show that it results in a reduction in engine wear.

Tin concentration is most likely associated with engine bearing wear. Iron concentration is associated with wear of engine parts (camshafts and piston cranks).

Examples 2 and 3
Four hydrocarbon basic fuel gasolines were tested. Comparative Example C was a basic fuel widely used as a fuel sold in the Netherlands in 2002. Comparative Example D corresponded to Comparative Example C, but a heavy platform was added in order to increase the aromatic compound. Example 1 corresponds to Comparative Example C, but 15 parts by volume of diisobutylene was added per 85 parts by volume of the basic fuel of Comparative Example C. Diisobutylene is a mixture of 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene in proportions obtained from commercial production. Example ₃ corresponds to Comparative Example C, but was added from the refinery stream of C5 and C6 olefins at a ratio of ₁₅ parts by volume of olefins to 85 parts by volume of basal fuel of Comparative Example C.

The obtained fuel had the characteristics shown in Table 4.

The test results for these fuels are shown in Table 5.

Overall, the above results show that the use of fuel in Examples 2 and 3 provides an overall unexpected benefit to the oxidative stability of the crankcase lubricant, as described above in Example 1. , Shows well that it produces similar results.

Example 4
The same fuel as in Comparative Example C (Comparative Example E) was mixed with diisobutylene and ethanol to obtain a gasoline composition containing 10% v / v diisobutylene and 5% v / v ethanol (Example). 4). The obtained gasoline contained 13.02% by volume of olefin, had an initial boiling point of 40 ° C. and a final boiling point of 168.5 ° C., and satisfied the other parameters of the present invention. Toyota Avensis 2.0l VVT-i direct injection spark ignition engine comparing this fuel with Comparative Example E and with the same basic fuel containing 5% v / v ethanol (Comparative Example F). Tested in. Both Comparative Example E and Comparative Example F are outside the scope of the parameters of the invention due to their olefin content (total olefins of 3.51% v / v and 3.33% v / v, respectively). Details of the fuel are shown in Table 6.

Under an accelerated test (1200-3500 rpm, 5th speed, fully open throttle (WOT), 1200-3500 rpm, 4th speed, WOT, and 1200-3500 rpm, 4th speed, 75% throttle), Example 4 is shown in Comparative Example E and Consistently excellent performance (acceleration time) was shown for any of F. When the engine used Example 4 as fuel with respect to Comparative Example E or Comparative Example F, significantly higher power was generated at both 1500 rpm and 2500 rpm.

Under an accelerated test (1200-3500 rpm, 5th speed, fully open throttle (WOT), 1200-3500 rpm, 4th speed, WOT, and 1200-3500 rpm, 4th speed, 75% throttle), Example 4 is shown in Comparative Example E and Consistently excellent performance (acceleration time) was shown for any of F. When the engine used Example 4 as fuel with respect to Comparative Example E or Comparative Example F, significantly higher power was generated at both 1500 rpm and 2500 rpm.
The present specification includes the following aspects of the invention.
[1] A method for improving the oxidative stability of a lubricating composition used for lubricating a spark-ignition engine, wherein the spark-ignition engine is included in the power train of a hybrid electric vehicle. The method comprises the step of introducing a gasoline composition into the combustion chamber of the spark-ignition engine, wherein the gasoline composition is a hydrocarbon basic fuel and 10 to 20% by volume of olefins based on the basic fuel. An initial boiling point in the range of 30-40 ° C., 45-57 ° C., containing an olefin having at least 10 carbon atoms of 5% by volume or less and an aromatic compound having at least 10 carbon atoms of 5% by volume or less. T10 in the range of T10, T50 in the range 82-104 ° C, T90 in the range 140-150 ° C, and a hydrocarbon basic fuel having a final boiling point of 220 ° C or lower.
[2] The method according to [1], wherein the gasoline composition contains 0 to 10% by volume of at least one oxygen-containing additive selected from methanol, ethanol, isopropanol, and isobutanol.
[3] The method according to [1] or [2], wherein the hydrocarbon basic fuel contains 10 to 20% by volume of olefin.
[4] The method according to any one of [1] to [3], wherein the hydrocarbon basic fuel contains 12 to 18% by volume of olefin.
[5] The basic fuel has an initial boiling point in the range of 28 to 42 ° C, a T ₁₀ in the range of 42 to 58 ° C, a T ₅₀ in the range of 80 to 105 ° C , a T ₉₀ in the range of 135 to 170 ° C , and 200. The method according to any one of [1] to [4], which has a final boiling point of ° C. or lower.
[6] The basic fuel has an initial boiling point in the range of 30 to 40 ° C, a T ₁₀ in the range of 45 to 57 ° C, a T ₅₀ in the range of 82 to 104 ° C , a T ₉₀ in the range of 140 to 150 ° C , and 180. The method according to any one of [1] to [5], which has a final boiling point of ° C. or lower.
[7] The method according to any one of [1] to [6], which is the gasoline composition.
[8] The method according to any one of [1] to [7], wherein the fuel composition contains one or more antioxidants.
[9] The method according to any one of [1] to [8], wherein the gasoline composition contains a hindered phenol type antioxidant.
[10] The method according to any one of [1] to [9], wherein the hybrid electric vehicle is a plug-in hybrid electric vehicle.
[11] The use of a gasoline composition as a fuel for a spark-ignited engine to improve the oxidative stability of the engine crankcase lubricating oil and / or reduce the frequency of replacement of the engine lubricating oil. The spark ignition engine is included in the power train of a hybrid electric vehicle, the gasoline composition is a hydrocarbon basic fuel, and 10 to 20% by volume of olefins and 5% by volume or less based on the basic fuel. Initial boiling point in the range of 30-40 ° C, T10 in the range of 45-57 ° C, containing an olefin having at least 10 carbon atoms and an aromatic compound having at least 10 carbon atoms of 5% by volume or less. , T50 in the range 82-104 ° C, T90 in the range 140-150 ° C, and the use of a hydrocarbon composition comprising a hydrocarbon basic fuel having a final boiling point of 220 ° C or lower.

Claims (11)

A method of improving the oxidative stability of a lubricating composition used to lubricate a spark-ignition engine, wherein the spark-ignition engine is included in the power train of a hybrid electric vehicle. Including the step of introducing a gasoline composition into the combustion chamber of a spark-ignition engine, the gasoline composition is a hydrocarbon basic fuel, and 10 to 20% by volume of olefins and 5% by volume based on the basic fuel. An initial boiling point in the range of 30-40 ° C, an initial boiling point in the range of 45-57 ° C, containing the following olefins with at least 10 carbon atoms and aromatic compounds with at least 10 carbon atoms of 5% by volume or less. A method comprising T10, T50 in the range 82-104 ° C, T90 in the range 140-150 ° C, and a hydrocarbon basic fuel having a final boiling point of 220 ° C or lower. The method according to claim 1, wherein the gasoline composition contains 0 to 10% by volume of at least one oxygen-containing additive selected from methanol, ethanol, isopropanol, and isobutanol. The method according to claim 1 or 2, wherein the hydrocarbon basic fuel contains 10 to 20% by volume of olefin. The method according to any one of claims 1 to 3, wherein the hydrocarbon basic fuel contains 12 to 18% by volume of olefin. The basic fuels are an initial boiling point in the range of 28-42 ° C, a T ₁₀ in the range of 42-58 ° C, a T ₅₀ in the range of 80-105 ° C, a T ₉₀ in the range of 135-170 ° C, and 200 ° C or less. The method according to any one of claims 1 to 4, which has a final boiling point. The basic fuels are an initial boiling point in the range of 30-40 ° C, a T ₁₀ in the range of 45-57 ° C, a T ₅₀ in the range of 82-104 ° C, a T ₉₀ in the range of 140-150 ° C, and 180 ° C or less. The method according to any one of claims 1 to 5, which has a final boiling point. The method according to any one of claims 1 to 6, which is the gasoline composition. The method according to any one of claims 1 to 7, wherein the fuel composition contains one or more antioxidants. The method according to any one of claims 1 to 8, wherein the gasoline composition contains a hindered phenol type antioxidant. The method according to any one of claims 1 to 9, wherein the hybrid electric vehicle is a plug-in hybrid electric vehicle. The use of a gasoline composition as a fuel for a spark-ignited engine to improve the oxidative stability of the engine crankcase lubricant and / or reduce the frequency of engine lubricant replacement, said spark ignition. The formula engine is included in the power train of a hybrid electric vehicle, and the gasoline composition is a hydrocarbon basic fuel, and the olefin is 10 to 20% by volume based on the basic fuel, and at least 10 of 5% by volume or less. Initial boiling point in the range of 30-40 ° C., T10, 82-in the range of 45-57 ° C., containing an olefin with 15 carbon atoms and an aromatic compound with at least 10 carbon atoms of 5% by volume or less Use of a gasoline composition comprising a T50 in the range of 104 ° C, a T90 in the range of 140-150 ° C, and a hydrocarbon basic fuel having a final boiling point of 220 ° C or lower.