Composition for an electric vehicle

Abstract

The use of a lubricant composition in order to cool and/or lubricate the engine of an electric vehicle and the different parts thereof, particularly moving parts, is disclosed. In particular, the use of a lubricant composition includes at least one polyalkylene glycol.

Claims

1. A method for cooling one or more components of an electric vehicle, said components comprising an engine, power electronics, a rotor, a stator of the engine, or a battery, said method comprising: cooling the one or more components of the electrical vehicle with a composition comprising at least one polyalkylene glycol (PAG) obtained by polymerisation of butylene oxide or by copolymerisation of ethylene oxide and propylene oxide, wherein the lubricant composition comprises 50 to 99% of PAG by weight with respect to the total weight of the composition, wherein the electric vehicle comprises an electric engine as a single drive.

2. The method according to claim 1, comprising: cooling and lubricating the engine.

3. The method according to claim 1, comprising: cooling the engine and lubricating the transmission.

4. The method according to claim 1, wherein the lubricant composition comprises 70 to 99% of PAG by weight with respect to the total weight of the composition.

5. A method for lubricating one or more components of an electric vehicle, said components comprising an engine, bearings located between a rotor and a stator, a reduction gear of the engine, or a transmission, said method comprising: lubricating the one or more components of the electric vehicle with a composition comprising at least one polyalkylene glycol (PAG) obtained by polymerisation of butylene oxide or by copolymerisation of ethylene oxide and propylene oxide, wherein the lubricant composition comprises 50 to 99% of PAG by weight with respect to the total weight of the composition, wherein the electric vehicle comprises an electric engine as a single drive.

6. A method for cooling a battery of an electric vehicle, said method comprising: cooling the battery of the electrical vehicle with a composition comprising at least one polyalkylene glycol (PAG) obtained by polymerisation of butylene oxide or by copolymerisation of ethylene oxide and propylene oxide, wherein the lubricant composition comprises 50 to 99% of PAG by weight with respect to the total weight of the composition, wherein the electric vehicle comprises an electric engine as a single drive.

Description

(1) FIG. 1 is a schematic representation of an electric motorisation system.

(2) The engine of an electric vehicle (1) comprises power electronics (11) connected to a stator (13) and a rotor (14). The rotation speed of the rotor is very high, which involves adding a speed reduction gear (3) between the electric engine (1) and the wheels of the vehicle.

(3) The stator comprises coils, in particular copper coils which are supplied alternatively by an electric current. This makes it possible to generate a rotating magnetic field. The rotor itself comprises coils or permanent magnets or other magnetic materials and is rotated by the rotating magnetic field.

(4) The power electronics, the stator and the rotor of an electric engine are parts featuring a complex structure and generating a high quantity of heat during the functioning of the engine. That is why the lubricant composition such as defined above is more specifically used to cool the power electronics and/or the rotor and/or the stator of the electric engine.

(5) In a preferred embodiment, the invention relates to the use of a lubricant composition such as defined above to cool the power electronics, the rotor and the stator of the electric engine.

(6) A bearing (12) making it possible to maintain the rotation axis is also integrated between the rotor and the stator. This bearing undergoes high mechanical stresses and poses wear problems through fatigue. It is therefore necessary to lubricate the bearing, in order to increase the lifespan thereof. That is why the lubricant composition such as defined above is also used to lubricate an electric vehicle engine.

(7) In a preferred embodiment, the invention relates to the use of a lubricant composition such as defined above to lubricate the bearings located between the rotor and the stator.

(8) The reduction gear (3), which forms part of the transmission, has the role of reducing the rotation speed at the outlet of the electric engine and adapting the speed transmitted to the wheels, making it possible at the same time to control the speed of the vehicle. This reduction gear undergoes high friction stresses and therefore requires being lubricated suitably in order to avoid it being damaged too quickly. That is why the lubricant composition such as defined above is also used to lubricate the reduction gear and the transmission of an electric vehicle.

(9) In a preferred embodiment, the invention relates to the use of a lubricant composition such as defined above to lubricate the reduction gear of an electric vehicle.

(10) The invention also relates to the use of a lubricant composition such as defined above to cool the power electronics and/or the rotor/stator couple and to lubricate the reduction gear and/or the bearings of the rotor/stator couple of an engine of an electric vehicle.

(11) The invention also relates to the use of a lubricant composition such as defined above to cool the battery of an electric vehicle.

(12) Indeed, the electric engine is supplied by an electric battery (2). The lithium-ion batteries are more common in the field of electric vehicles. The development of more and more powerful batteries and of which the size is more and more reduced, involves the appearance of the problem of cooling this battery. Indeed, as soon as the battery exceeds temperatures of around 50 to 60° C., there is a high risk that the battery ignites, even explodes. There is also a need to maintain the battery at a temperature greater than around 20 to 25° C. in order to avoid the battery being discharged too quickly and to extend the lifespan thereof. There is therefore a need to maintain the battery at an acceptable temperature.

(13) The invention also relates to the use of a composition such as defined above to cool the battery and the engine of a motor vehicle.

(14) The invention also relates to the use of a lubricant composition such as defined above to cool a hybrid vehicle electric engine.

(15) All of the characteristics and preferences described for the lubricant composition and for the PAG also apply to these uses.

(16) The invention also relates to a method for cooling an electric vehicle engine comprising at least one step of contacting a mechanical part of the engine with a composition as defined above.

(17) The invention also relates to a method for cooling the power electronics and/or the rotor and/or the stator of an electric vehicle engine comprising at least one step of contacting the power electronics and/or the rotor and/or the stator with a composition as defined above.

(18) The invention also relates to a method for lubricating an electric vehicle engine comprising at least one step of contacting a mechanical part of the engine with a composition as defined above.

(19) The invention also relates to a method for lubricating bearings located between the rotor and the stator and/or the reduction gear of an electric vehicle engine comprising at least one step of contacting said bearings with a composition as defined as above.

(20) The invention also relates to a method for cooling and lubricating an electric vehicle engine comprising at least one step of contacting a mechanical part of the engine with a composition as defined above.

(21) The invention also relates to a method for cooling an electric vehicle engine and lubricating the transmission of said electric vehicle comprising at least one step of contacting a mechanical part of the engine and of the transmission with a composition as defined above.

(22) The invention also relates to a method for cooling the power electronics and/or of the rotor/stator couple and lubricating the reduction gear and/or the bearings of the rotor/stator couple of an electric vehicle engine comprising at least one step of contacting the power electronics and/or the rotor and/or the stator and the reduction gear and/or the bearings of the rotor/stator couple with a composition as defined above.

(23) The invention also relates to a method for cooling the battery of an electric vehicle comprising at least one step of contacting the battery with a composition as defined above.

(24) The invention also relates to a method for cooling the battery and the engine of an electric vehicle comprising at least one step of contacting the battery and a mechanical part of the engine with a composition as defined above.

(25) The invention also relates to a method for cooling a hybrid vehicle engine comprising at least one step of contacting a mechanical part of the engine with a composition as defined above.

(26) All of the characteristics and preferences described for the lubricant composition and for the PAG above also apply to these methods.

(27) The cooling of the electric engine by the lubricant composition according to the invention can be implemented by any method known to a person skilled in the art.

(28) As implementation examples, cooling by jet, by spraying or also by forming a mist from the lubricant composition according to the invention, pressurised and by gravity can be cited, in particular on the coiling of the rotor and/or of the stator.

EXAMPLES

(29) Two lubricant compositions, CI1 and CC1 have been formulated as described in table 1. The quantities of different compounds are expressed as a mass percentage with respect to the total weight of the composition.

(30) TABLE-US-00002 TABLE 1 CI1 CC1 (according to (compar- the invention) ative) PAG 1 obtained by polymerisation of 52.8 — propylene oxides (SYNALOX 100-20B ® of the company DOW) PAG 2 obtained by polymerisation of 44 — propylene oxides (SYNALOX 100-50B ® of the company DOW) PAO 1 (viscosity of 4 mm.sup.2/s — 68.1 measured at 100° C. according to the ASTM D445 standard) PAO 2 (viscosity of 1000 mm.sup.2/s — 19.6 measured at 100° C. according to the ASTM D445 standard) Ester (NB7400 ® of the company NYCO) — 10 Package of additives 1 3.2 — Package of additives 2 — 2.3

(31) A means for measuring the thermal properties of a fluid consists in measuring the thermal exchange coefficient of the fluid (thermal transfer by surface unit and temperature). A fluid having a higher thermal exchange coefficient has better cooling properties.

(32) A test making it possible to measure the thermal exchange coefficient of each of the lubricant compositions described in table 1 has been carried out.

(33) The principle of the test consists in projecting an oil jet using a sprinkler perpendicularly on the metal plate heated by induction. A thermal camera, placed above the plate, records the temperature profile during the projection of oil. From the variation values of the temperature on the plate, it is thus possible to calculate the thermal exchange coefficient means of the lubricant composition.

(34) It is possible to make different parameters vary, in particular the temperature of the plate, the size of the sprinkler and the pressure at which the oil is projected. The measurement of the thermal coefficient is taken at different distances from the impact point of the jet on the metal plate, this distance corresponding to the radius. The conditions of the test are described in table 2.

(35) TABLE-US-00003 TABLE 2 Conditions of the test Characteristic Unit Temperature ° C. 113 Pressure bar 20-40 Diameter of the sprinkler mm 0.5 Radius mm  0-15

(36) The values of the thermal coefficients of the compositions tested under the test conditions of table 2, according to the radius, are presented in tables 3 to 6. The values of the thermal exchange coefficients are expressed in W/K.Math.m.sup.2.

(37) TABLE-US-00004 TABLE 3 Thermal exchange coefficients of the compositions - Radius 0 mm Pressure (bar) CI1 CC1 40 4015 2520 38 3954 2486 36 4109 2557 34 4200 2323 32 3881 2135 30 3550 2060 28 3240 1858 26 4674 1815

(38) TABLE-US-00005 TABLE 4 Thermal exchange coefficients of the compositions - Radius 5 mm Pressure (bar) CI1 CC1 40 3404 2459 38 3296 2417 36 3359 2389 34 3458 2216 32 3236 2019 30 3048 1966 28 2811 1819 26 3837 1780

(39) TABLE-US-00006 TABLE 5 Thermal exchange coefficients of the compositions - Radius 10 mm Pressure (bar) CI1 CC1 40 2993 2031 38 2831 1962 36 2808 1919 34 2822 1765 32 2655 1583 30 2489 1523 28 2329 1375 26 3275 1318

(40) TABLE-US-00007 TABLE 6 Thermal exchange coefficients of the compositions - Radius 15 mm Pressure (bar) CI1 CC1 40 2398 1323 38 2211 1269 36 2141 1239 34 2021 1147 32 1880 1052 30 1734 1012 28 1630 928 26 2402 908

(41) The thermal exchange coefficient is even higher for the composition CI according to the invention than for the comparative composition CC corresponding to a composition of the prior art. This demonstrates that a composition according to the invention has better thermal properties compared with a composition of the prior art, thus involving better cooling properties of an electric vehicle engine.

(42) Moreover, a deaeration measurement according to the method ASTM D3427 was taken on the composition CI according to the invention. This measurement has made it possible to highlight that no air volume is absorbed by the composition during the test. This makes it possible to demonstrate that a composition according to the invention has good deaeration properties, and therefore conserves good cooling properties over time.