LUBRICATION OF RECHARGEABLE HYBRID VEHICLE ENGINE AND HYBRID VEHICLE COMPRISING A RANGE EXTENDER

Abstract

The application concerns the use of a lubricant composition of grade 0W-8 according to the SAEJ300 classification, comprising at least one base oil, from 1 to 1000 ppm of at least one friction modifying additive and from 0.1 to 10% by weight of at least one polymer improving the viscosity index, said lubricant composition having kinematic viscosity measured at 40? C. according to standard ASTM D445 lower than or equal to 20 mm2/s, kinematic viscosity measured at 100? C. according to standard ASTM D445 lower than 5 mm2/s, and Noack volatility measured at 250? C. according to standard CEC-L-40-A-93 of between 10 and 85%, preferably between 25 and 85%, more preferably between 60 and 85%, for the lubrication of a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender.

Claims

1.-8. (canceled)

9. A method for lubricating a rechargeable hybrid vehicle engine or a hybrid vehicle engine comprising a range extender, comprising contacting at least one mechanical part of the engine with a lubricant composition of grade 0W-8 according to the SAEJ300 classification, comprising at least one base oil, at least one friction modifying additive, from 0.1 to 10% by weight of at least one polymer improving the viscosity index, the lubricant composition having a kinematic viscosity measured at 40? C. according to standard ASTM D445 lower than 20 mm.sup.2/s, a kinematic viscosity measured at 100? C. according to standard ASTM D445 lower than 5 mm.sup.2/s, and a Noack volatility measured at 250? C. according to standard CEC-L-40-A-93 of between 10 and 85%.

10. A method for reducing the fuel consumption of a rechargeable hybrid vehicle or hybrid vehicle comprising a range extender, comprising contacting at least one mechanical part of the engine with a lubricant composition of grade 0W-8, according to the SAEJ300 classification, comprising at least one base oil, at least one friction modifying additive, from 0.1 to 10% by weight of at least one polymer improving the viscosity index, the lubricant composition having a kinematic viscosity measured at 40? C. according to standard ASTM D445 lower than 20 mm.sup.2/s, a kinematic viscosity measured at 100? C. according to standard ASTM D445 lower than 5 mm.sup.2/s, and a Noack volatility measured at 250? C. according to standard CEC-L-40-A-93 of between 10 and 85%.

11. The method of claim 9, wherein the base oil has a kinematic viscosity measured at 40? C., according to standard ASTM D445, of less than 15 mm.sup.2/s.

12. The method of claim 9, wherein the base oil has a kinematic viscosity measured at 100? C., according to standard ASTM D445, of between 1 and 4 mm.sup.2/s.

13. The method of claim 9, wherein the lubricant composition comprises between 0.5 and 4.0% by weight of dispersant, relative to the total weight of the lubricant composition.

14. The method according to claim 9, wherein the kinematic viscosity measured at 40? C., according to standard ASTM D445, is between 10 and 20 mm.sup.2/s.

15. The method according to claim 9, wherein the kinematic viscosity measured at 100? C., according to standard ASTM D445, of the lubricant composition is between 1 and 5 mm.sup.2/s.

16. The method according to claim 9, wherein the lubricant composition comprises from 50 to 95% by weight of base oil, relative to the total weight of the lubricant composition.

17. The method according to claim 9, wherein the lubricant composition comprises from 0.01 to 10% by weight of friction modifying additive, relative to the total weight of the lubricant composition.

18. The method according to claim 9, wherein the friction modifying additive is molybdenum-based.

19. The method of claim 10, wherein the base oil has a kinematic viscosity measured at 40? C., according to standard ASTM D445, of less than 15 mm.sup.2/s.

20. The method of claim 10, wherein the base oil has a kinematic viscosity measured at 100? C., according to standard ASTM D445, of between 1 and 4 mm.sup.2/s.

21. The method of claim 10, wherein the lubricant composition comprises between 0.5 and 4.0% by weight of dispersant, relative to the total weight of the lubricant composition.

22. The method according to claim 10, wherein the kinematic viscosity measured at 40? C., according to standard ASTM D445, is between 10 and 20 mm.sup.2/s.

23. The method according to claim 10, wherein the kinematic viscosity measured at 100? C., according to standard ASTM D445, of the lubricant composition is between 1 and 5 mm.sup.2/s.

24. The method according to claim 10, wherein the lubricant composition comprises from 50 to 95% by weight of base oil, relative to the total weight of the lubricant composition.

25. The method according to claim 10, wherein the lubricant composition comprises from 0.01 to 10% by weight of friction modifying additive, relative to the total weight of the lubricant composition.

26. The method according to claim 10, wherein the friction modifying additive is molybdenum-based.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0075] The present invention will be described below with the aid of the following examples that are by no means limiting.

[0076] FIG. 1 shows the trend in engine speed (right-side axis in rpm) and temperature of the lubricant (left-side axis in ? C.) during a WLTC test.

DETAILED DESCRIPTION

Example 1: Compositions of the Invention and Comparative Compositions

[0077] The lubricant compositions below (CC comparative composition; CL composition of the invention) were prepared.

TABLE-US-00002 TABLE 2 Composition CC1 CC2 CC3 CC4 CL1 CL2 CL3 Grade 0W-8 0W-8 0W-16 0W-12 0W-8 0W-8 0W-8 Additive 10.1 (including 10.1 (including 10.1 (including 10.1 (including 10.1 (including 5 (including 10.1 (including package 3.8% 3.8% 3.8% 3.8% 3.8% 1.9% 3.8% (wt. %) dispersant) dispersant) dispersant) dispersant) dispersant) dispersant) dispersant) Viscosity 4.1 1.6 5 5 3.3 modifier (wt. %) MoDTC (wt. %) 0.5 0.5 0.5 0.5 Base oil 1 5 5 (wt. %) Base oil 2 84.4 84.9 85.8 88.3 (wt. %) Base oil 3 88.4 89.5 76.1 (wt. %) Base oil 4 10 in Group III (wt. %) HTHS 100? C. 3.87 2.9 2.58 3.10 CEC L-036-90 or ASTM D4683 HTHS 150? C. 1.8 1.8 2.28 2.02 1.69 1.50 1.66 CEC L-036-90 or ASTM D4683 KV40 ASTM 23.66 22.792 26.037 23.953 13.64 11.24 14.78 D445-97 (mm.sup.2/s) KV100 ASTM 5.039 5.01 6.233 5.474 4.578 4.058 4.367 D445-97 (mm.sup.2/s) VI 146 300 BOV 4.1 4.1 4.1 4.1 2 2 2 Estimated 13.5 13.5 <13 <13 78 78 68 Noack 250 (%) ASTM D5800 or CEC L-040-93 Estimated 2 2 <2 <2 30 30 30 Noack 200 (%) ASTM D5800 or CEC L-040-93

Example 2: WLTC Cycle Savings in Consumption

[0078] The compositions in Example 1 were subjected to simulation for hybrid application under the WLTC test (or WLTPWorldwide Harmonized Light Vehicles Test Procedure) to determine the savings in fuel consumption.

[0079] In this respect, friction tests (FMEP=Friction Mean Effective Pressure) of the different lubricant compositions described in Example 1 were conducted on a test bed comprising a driven Nissan X-Trail MR20 engine, having a power of 108 KW at 5600 rpm, driven by an electric generator producing a rotation speed of between 550 and 2800 rpm, whilst a torque sensor allowed measurement of the friction torque generated by the movement of the engine parts. The friction torque induced by the lubricant composition to be tested was compared, for each engine speed and for each mean torque at each temperature, with that induced by the reference lubricant composition (SAE 0W16) which was evaluated before and after each of the lubricant compositions to be tested.

[0080] The higher the value of the reduction in friction torque, the more the lubricant composition can allow friction occurring in the engine to be reduced.

[0081] The conditions of this test were the following.

[0082] The tests were conducted in the following sequence: [0083] rinsing the engine with a detergent additive for lubricant oil comprising one rinsing, followed by two rinsings with a reference lubricant composition of grade 0W-12 comprising 81.7% by weight of base oil, 17.8% by weight of usual additives (4.4% viscosity index improver, 0.5% antioxidant, 0.20% pour point depressant and 12.7% additive package) and 0.05% by weight of molybdenum dithiocarbamate (MoDTC), relative to the total weight of the base oil; [0084] measuring the friction torque at the two different temperatures indicated below on the engine using the reference lubricant composition; [0085] rinsing the engine with a detergent additive for lubricant oil comprising one rinsing, followed by two rinsings with a lubricant composition to be evaluated; [0086] measuring the friction torque at the two different temperatures on the engine using the lubricant composition to be evaluated; [0087] rinsing the engine with a detergent additive for lubricant oil comprising one rinsing, followed by two rinsings with the reference lubricant composition; and [0088] measuring the friction torque at the two different temperatures indicated below on the engine using the reference lubricant composition.

[0089] The speed ranges, variation in speed and temperature were chosen in agreement with Nissan, to be representative of the WLTC cycle.

[0090] The instructions followed were: [0091] Temperature of water leaving the engine: 30? C./50? C./80? C.+/?0.5? C. [0092] Petrol temperature ramp: 50? C./80? C.+/?0.5? C.

[0093] The results are given in following Table 3 and show the reduction in friction expressed as % (compared with the Nissan Strong Save X 0W-16 oil, used as reference oil and point of comparison for this part of the test) as a function of engine speed and temperature for the compositions in Example 1.

TABLE-US-00003 TABLE 3 550 650 800 1000 1200 1400 1600 1800 2000 2400 2800 CC3 30 0.197 0.247 0.331 0.382 0.393 0.454 0.423 0.405 0.300 0.443 0.647 50 ?0.074 0.026 0.087 0.133 0.235 0.304 0.358 0.408 0.379 0.430 0.435 80 ?0.860 ?0.702 ?0.601 ?0.341 ?0.232 ?0.158 ?0.036 ?0.046 ?0.003 0.04 0.135 CC4 30 0.298 0.347 0.456 0.440 0.601 0.739 0.696 0.709 0.689 0.655 0.898 50 0.032 0.131 0.088 0.310 0.338 0.432 0.564 0.544 0.490 0.566 0.649 80 ?0.812 ?0.582 ?0.479 ?0.216 ?0.111 ?0.034 0.090 0.182 0.201 0.223 0.268 CC2 30 0.399 0.474 0.669 0.708 0.802 0.979 0.917 0.865 0.868 0.950 1.074 50 0.042 0.143 0.195 0.419 0.445 0.618 0.654 0.636 0.613 0.796 0.853 80 ?0.866 ?0.636 ?0.437 ?0.081 0.119 0.094 0.118 0.265 0.263 0.283 0.321 CC1 30 0.499 0.599 0.696 0.777 0.920 0.901 0.883 0.961 0.977 0.963 1.199 50 0.391 0.469 0.398 0.473 0.598 0.696 0.770 0.793 0.740 0.813 0.908 80 0.100 0.172 0.168 0.365 0.367 0.317 0.392 0.467 0.563 0.512 0.552 CL3 30 1.745 1.931 2.199 2.430 2.928 3.423 3.640 3.658 3.644 3.684 4.096 50 0.726 0.948 1.210 1.515 1.719 2.007 2.290 2.473 2.450 2.592 2.866 80 ?0.292 ?0.052 0.173 0.498 0.691 0.921 0.969 1.054 1.199 1.390 1.434 CL2 30 2.348 2.635 2.918 3.368 3.930 4.588 4.806 4.960 4.900 5.042 5.447 50 1.156 1.482 1.831 2.141 2.337 2.627 2.923 3.107 3.174 3.372 3.650 80 0.081 0.295 0.433 0.845 0.972 1.246 1.295 1.397 1.473 1.444 1.346 CL1 30 1.901 2.201 2.479 2.853 3.399 3.982 4.088 4.105 4.158 4.338 4.288 50 0.813 1.064 1.393 1.706 1.857 2.160 2.314 2.569 2.508 2.630 2.833 80 ?0.027 0.177 0.410 0.689 0.843 0.962 1.039 1.194 1.152 1.152 1.162

[0094] In parallel, a WLTC test on a vehicle having the same engine as the one mentioned at the preceding step was also conducted for tangible measurement of fuel consumption and oil temperature throughout said cycle. This driving test was conducted with a single reference lubricant, the same as the one used to establish the reference for the PMF tests described above: Nissan Strong Save X 0W16 oil according to graph in FIG. 1.

[0095] Therefore, oil temperatures and levels of fuel consumption were measured under the WLTC cycle on a Nissan X-Trail MR20 engine. Different power levels of electrical assistance were considered from 1 kW up to 35 KW (representing several types of hybridization).

[0096] In this respect, powers of 1 or 2 KW represent electrical assistance of light hybridization types (Micro-Hybrid and Mild-Hybrid respectively).

[0097] A power of 5 KW represents the electrical assistance of a Full-Hybrid vehicle.

[0098] Finally, powers of 18 or 33 KW represent electrical assistance of the most advanced hybridization types (Range Extender and rechargeable (Plug-In) Hybrid respectively).

[0099] Next, simulation of oil temperature and fuel consumption was carried out for the different types of hybrid vehicles concerned, as a function of the types of hybridization described above, and considering that the internal combustion engine is shut off when power demand is lower than the available level of electrical power. These simulations were conducted for the lubricant compositions such as described in Example 1, and for which results in terms of coefficient of friction were already known.

[0100] Finally, the simulated oil temperature was projected (by linear interpolation of friction results) and the advantage or penalty obtained (results of the coefficients of friction obtained) was applied to fuel consumption. Fuel consumption was only taken into account when the engine was running.

[0101] Each trace line of simulated oil temperature was transposed by linear interpolation of FTT FE [=f(T ? C.) & engine speed (rpm)] results, and the advantage/penalty ratio was applied to the corresponding point of fuel consumption. The fuel consumption trace was then integrated to obtain levels of overall Fuel Economy performance which can be compared and are comparable.

[0102] The following results were obtained and show the fuel savings when the engine was lubricated with the compositions in Example 1.

TABLE-US-00004 TABLE 4 Fuel savings (%) Dispersant Non- Micro- Mild- Full- Range Plug-In Composition % hybrid hybrid Hybrid hybrid Extender Hybrid CC4 3.8 0.18 0.30 0.34 0.38 0.48 0.53 CC3 3.8 0.03 0.13 0.17 0.21 0.31 0.37 CL2 1.9 1.58 2.13 2.33 2.52 3.04 3.23 CL1 3.8 1.30 1.75 1.91 2.08 2.47 2.56 CC1 3.8 0.46 0.59 0.63 0.66 0.68 0.71 CC2 3.8 0.27 0.41 0.45 0.50 0.63 0.65 CL3 3.8 1.27 1.69 1.85 2.00 2.33 2.44 T? C. of the 71.7 60.7 56.7 52.5 34.1 25.3 lubricant composition

[0103] The results in Table 4 show that the compositions of the invention allow major fuel savings for the rechargeable hybrid systems (plug-in hybrids) and hybrids comprising a range extender. On the contrary, these same compositions of the invention do not allow a substantial reduction in the other types of hybrid motorization. These results show that the compositions of the invention are specifically efficient for rechargeable hybrid motorizations and for hybrid motorizations comprising a range extender.

[0104] Additionally, the mean temperature of the lubricant was extrapolated and is higher than 70? C. for a non-hybrid vehicle engine, higher than 60? C. for a micro-hybrid vehicle, higher than 55?C for a mild-hybrid vehicle, higher than 50? C. for a full-hybrid vehicle, and is lower than 40? C. for hybrid vehicles comprising a range extender and for rechargeable hybrid vehicles.