Transmission for a hybrid traction or propulsion motor vehicle

Abstract

The invention relates to a transmission (1) for a hybrid traction or propulsion motor vehicle, the transmission (1) comprising: • - a first machine (20) comprising a rotor (22) secured to a main power transmission shaft (21) that rotates conjointly with a main gearbox input shaft (25) configured to be coupled to or uncoupled from the wheels of the vehicle, • - a second machine (40) comprising a rotor (42) secured to a secondary power transmission shaft (41) that rotates conjointly with a secondary gearbox input shaft (45) configured to be coupled to or uncoupled from the wheels of the vehicle, and • - a combustion engine secured to an input shaft (60). The second electric machine (40) is connected to the wheels independently of the combustion engine.

Description

[0001] DESCRIPTION

[0002] TITLE: Transmission for a motor vehicle with hybrid propulsion or traction

[0003] The present invention relates to the field of transmissions for motor vehicles with hybrid propulsion or traction comprising on the one hand a means of traction by a thermal engine, and on the other hand an electric means of traction.

[0004] More particularly, the invention relates to hybrid transmissions comprising a heat engine, two electric drive machines, and three primary shafts, one connected to the crankshaft of the heat engine and the other two connected to each of the electric machines. The connection of each of the traction means with its primary shaft is devoid of decoupling means.

[0005] Document FR 3 022 495 is known, which describes a hybrid transmission configured to transmit the power of a thermal engine and two electric machines to the wheels of the motor vehicle. The thermal engine and the main electric machine, called the driving machine, are each connected to a primary shaft without a decoupling device. These two primary shafts are coaxial and the shaft of the electric machine is concentric with the shaft of the thermal engine. The second electric machine, called the generator, is offset laterally relative to the crankshaft axis and connected to the primary shaft linked to the thermal engine, permanently by a succession of pinions.

[0006] The main electric machine is configured to be connected to the vehicle wheels in two different ratios by dog ​​clutch engagement means without a synchronization device. The heat engine is configured to be connected to the vehicle wheels in four different ratios using the same engagement means. Two of the ratios of the heat engine are dependent on the ratios of the main electric machine and two ratios, including the fourth ratio, are dedicated to the heat engine. The heat engine and the electric machines are attached to the gearbox. A spline drive and a dynamic seal are present between said gearbox and each electric machine.The electric generator machine has a very high rotation speed compared to that of the thermal engine, so that the reliability of the assembly is difficult to guarantee due to its arrangement in height and without means of correcting coaxiality defects.

[0007] Each electric machine has its own water cooling system, which, added to that of the gearbox, generates three cooling systems to manage. The Joule effect losses of electric machines cannot be directly used to accelerate the temperature rise of the gearbox oil during the first kilometers, and thus improve its energy efficiency.

[0008] The electric generator is permanently connected to the combustion engine. When driving in electric mode, particularly in the case of a plug-in hybrid electric vehicle (PHEV), the electric generator cannot participate in the vehicle's traction. The main electric motor must then be sized to handle driving in electric mode alone.

[0009] Furthermore, the main electric machine is a so-called slow machine, it has two ratios, namely a so-called short ratio to ensure acceleration at low speed and a so-called long ratio to ensure maximum speed. During the gear change, the continuity of the torque to the wheel is taken care of by the generating electric machine but is only partially ensured.

[0010] There is a need to improve state-of-the-art hybrid transmissions of motor vehicles.

[0011] The object of the present invention is therefore to provide a hybrid transmission whose energy performance is improved. - a first machine or main electric machine comprising a rotor secured to a main power transmission shaft secured in rotation to a main gearbox input shaft by a splined connection, the main gearbox input shaft being configured to be coupled or decoupled from the wheels of the vehicle by a first coupling system,

[0012] - a second machine or secondary electrical machine comprising a rotor secured to a secondary power transmission shaft secured in rotation to a secondary gearbox input shaft by a splined connection, the secondary gearbox input shaft being configured to be coupled or decoupled from the wheels of the vehicle by a second coupling system, and

[0013] - a heat engine connected to an input shaft.

[0014] The second electric machine is connected to the wheels independently of the thermal engine.

[0015] Thus, when the powertrain is a plug-in hybrid, the generator can be used as a motor for driving in electric mode. By supporting the traction machine, it allows the latter to reduce its size.

[0016] For example, the electrical machines are integrated into a dedicated compartment of the gearbox, at the end of the gearbox.

[0017] This allows for a common output of the three phases of each machine and the wiring of the resolvers and promotes the installation of the power electronics directly on the gearbox with a busbar connection and without wiring.

[0018] Electric machines preferably operate in oil. The transmission may include a single cooling system for both electric machines and the gearbox.

[0019] In this way, the Joule effect losses of the electrical machines are recovered to accelerate the heating of the oil and improve the efficiency of the transmission on the homologation cycle and driving in real conditions with low load and short duration.

[0020] In addition, seals and associated losses can be eliminated. Finally, the splined connections of the electrical machines with the input shafts are lubricated with circulating oil.

[0021] Advantageously, the transmission comprises a first secondary shaft configured to be coupled or decoupled from the main gearbox shaft and a second secondary shaft configured to be coupled or decoupled from the secondary gearbox shaft.

[0022] Having two secondary shafts allows for good compactness and better mechanical strength. The drive gears are relocated to the ends of said secondary shafts.

[0023] For example, the main gearbox shaft carries a single idler gear and the first secondary shaft carries a fixed gear configured to mesh with the first idler gear and a toothing configured to mesh with a crown wheel of a differential assembly.

[0024] For example, the first coupling system is carried by the gearbox shaft and comprises a hub and a sliding or sliding sleeve.

[0025] For example, the secondary gearbox input shaft carries two idler gears and the second secondary shaft carries a fixed gear configured to mesh with a first intermediate gear carried by an intermediate shaft and configured to mesh with the first idler gear of the secondary gearbox input shaft, the second secondary shaft further carrying a toothing configured to mesh with the crown wheel of the differential assembly.

[0026] For example, the second coupling system is carried by the secondary gearbox shaft and comprises a hub and a sliding or sliding sleeve.

[0027] For example, the input shaft of the thermal engine carries a fixed pinion configured to mesh with the second idler pinion of the secondary input shaft of the gearbox.

[0028] The pair of connecting pinions between the generator and the thermal engine is integrated in the axial space of the crown wheel.

[0029] Advantageously, the transmission has, for the thermal engine, several ratios independent of the electric machines, which allows driving in thermal mode alone on all ratios. For example, the input shaft of the thermal engine carries five fixed gears, namely a gear corresponding to the gear of the second ratio, a gear corresponding to the gear of the first ratio, a gear corresponding to the gear of the third ratio, a gear corresponding to the gear of the fourth ratio and the gear corresponding to the drive gear of the thermal engine by the secondary electric machine, the fixed gears, respectively of the first and third ratios, being configured to mesh respectively with idle gears carried by the first secondary shaft and the fixed gears, respectively of the second and fourth ratios, being configured to mesh respectively with idle gears carried by the second secondary shaft.

[0030] Advantageously, the transmission further comprises a parking brake device comprising a toothed wheel, the axial position of said wheel being inscribed in the axial edge of the crown wheel of the differential assembly.

[0031] For example, the gear wheel is located on the main input shaft of the main electric machine box and is integrated into the axial space of the bridge crown.

[0032] Advantageously, the main electrical machine is offset from the crankshaft axis of the thermal engine, which results in the elimination of the hollow shaft.

[0033] For example, the traction machine is chosen as a fast type capable of reaching 15,000 rpm, which eliminates the problem of gear changes, and is configured to be disconnected.

[0034] According to a second aspect, the invention relates to a motor vehicle with hybrid propulsion or traction comprising at least two drive wheels and a transmission, as described previously, configured to drive said drive wheels in rotation.

[0035] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the appended drawings in which: [Fig 1] represents a schematic cross-sectional view of a transmission of a motor vehicle according to an embodiment of the invention;

[0036] [Fig 2] is a longitudinal sectional view II-II of the transmission of Fig. 1, passing through the main engine, the secondary engine, the secondary shaft and the differential;

[0037] [Fig 3] is a cross-sectional view III-III of a crown wheel of the transmission of Figure 2;

[0038] [Fig 4] represents the power path from the electrical machines to the wheels of the transmission of Figure 2;

[0039] [Fig 5] represents the power path from the heat engine to the wheels of the transmission of figure 2 in first and third gears;

[0040] [Fig 6] represents the power path from the heat engine to the wheels of the transmission of Figure 2 in second and fourth gears; and

[0041] [Fig 7] represents the power path between the heat engine and the secondary electric generating machine.

[0042] As illustrated very schematically in Figure 1, a powertrain or transmission, referenced 1 as a whole, is intended to be integrated into a motor vehicle with hybrid propulsion or traction (not shown).

[0043] The powertrain 1 comprises two electric machines 20, 40 each intended to drive a drive shaft (not shown) of the drive wheels of the vehicle via a differential assembly 100. The electric machines 20, 40 each comprise their own power transmission path.

[0044] The powertrain 1 further comprises a heat engine represented by its input shaft 60.

[0045] Each power source is connected to an input shaft. The main engine, called the driving engine, 20 is connected to an input shaft 25. The secondary traction engine, called the generator, 40 is connected to an input shaft 45. There is no decoupling device between the power sources and the input shafts 25, 45, 60.

[0046] All power sources are configured to be connected to the vehicle wheels through shafts, gears and coupling devices in one or more ratios.

[0047] As illustrated, the powertrain 1 comprises three separate casings 10, 11, 12, namely a flywheel casing 10, a mechanism casing 11 and an electrical machine casing 12.

[0048] The flywheel housing 10 incorporates a flywheel (not shown) of a thermal engine.

[0049] The flywheel casing 10 and the mechanism casing 11 delimit between them a first compartment (not referenced) in which all of the mechanics are mounted, such as in particular the power transmission means, the coupling systems, the mechanism for engaging a parking brake, etc.

[0050] The casing 11 of the mechanisms and the casing 12 of the electrical machines delimit between them a second compartment (not referenced) in which the two electrical machines 20, 40 are mounted.

[0051] These two compartments are not sealed against each other. Thus, the lubricating and cooling fluid of the bearings, the pinion bearings corresponds to the cooling fluid of the electrical machines 20, 40.

[0052] Thus, there is a pooling of the heating and cooling fluid, and therefore a single exchange and regulation system. A major advantage of such pooling is the direct use, and therefore with greater efficiency, of the calories dissipated by the electrical machines to heat the lubricating fluid quickly after starting the engine and over a short distance. The efficiency of the mechanical part of the transmission is thus improved.

[0053] The first electrical machine 20 or main machine, called the driving machine, comprises a shaft 21 supporting a rotor 22 and a stator 23. This electrical machine can be controlled using a speed and angular position sensor 24. The rotor shaft 21 is rotationally fixed to the main gearbox input shaft 25 by a splined connection 29. These two shafts 21,

[0054] 25 are supported by three bearings 26, 27, 28. The first bearing

[0055] 26 is mounted in the intermediate casing 11, the second bearing 27 is mounted in the machine casing 12 and supports the rotor shaft 21, and the third bearing 28 is mounted in the flywheel casing 10.

[0056] The main gearbox input shaft 25 is supported on the one hand by the third bearing 28 and, on the other hand, by the rotor shaft 21 by a centering and guiding zone 29a juxtaposed with the splines 29.

[0057] The gearbox shaft 25 carries a single idler gear 30 and a first coupling system composed of a hub 31 and a sliding sleeve 32 or sliding gear.

[0058] The transmission 1 further comprises a parking brake device comprising a toothed wheel 33 arranged near the third bearing 28 and close to the joint plane of the flywheel 10 and intermediate 11 casings. The axial position of this parking wheel 33 is inscribed in the axial edge of the crown wheel 102 of the differential assembly 100, as visible in FIG. 3.

[0059] The movement of the sleeve 32 allows the coupling of the gearbox input shaft 25 with the pinion 30. The latter meshes with a fixed pinion 82 carried by a secondary shaft 80, called high. This secondary shaft 80 has, at its opposite end, a toothing 81 which meshes with the crown wheel 102, carried by a differential housing 101 of the differential assembly 100. This double meshing 30, 82 and 81, 102 constitutes the only connection of the main machine 20 with the wheels, as can be seen on the power transmission path illustrated in broken lines in Figure 4.

[0060] The second electrical machine 40 or secondary machine, called the generator, comprises a shaft 41 supporting a rotor 42 and a stator 43. This electrical machine can be controlled using a speed and angular position sensor 44.

[0061] The rotor shaft 41 is rotationally fixed to the secondary gearbox input shaft 45 by a splined connection 49. These two shafts 41, 45 are supported by three bearings 46, 47, 48. The first bearing

[0062] 46 is mounted in the intermediate casing 11, the second bearing 47 is mounted in the engine casing 12 and the third bearing 48 is mounted in the flywheel casing 10 and supports the secondary gearbox input shaft 45.

[0063] The rotor shaft 41 is supported on the one hand by the second bearing 47 and, on the other hand, by the secondary gearbox input shaft 45 by a centering and guiding zone 49a juxtaposed with the splines

[0064] 49.

[0065] The secondary input shaft of gearbox 45 carries two idle gears

[0066] 50, 51 and a second coupling system composed of a hub 52 and a sliding sleeve 53 or sliding sleeve. By moving the sleeve 53 to the left, that is to say towards the electric machine 40, the secondary gearbox input shaft 45 is coupled to the idler gear 50. This gear 50 meshes with an intermediate gear 71, mounted on a needle bearing 72 and carried by an intermediate shaft 70. This shaft 70 is immobilized in rotation by an anti-rotation pin 73. The intermediate gear 71 meshes with a fixed gear 92 carried by the so-called low secondary shaft 90. Said shaft 90 comprises, at its opposite end, a toothing 91 which meshes with the crown wheel 102. This triple meshing 50, 71 then 71, 92 and 91, 102 constitutes the only connection of the secondary electric machine 40 with the wheels as can be seen on the power transmission path illustrated in a continuous line on the Figure 4.

[0067] Thus, the drive of the differential 100 in electric traction is possible in three different ways. Either by the main machine 20, or by the secondary machine 40, or by the two electric machines 20, 40.

[0068] The possibility of making the two electrical machines work in tandem is important because it allows, for a targeted total electrical power, to reduce the size of the main electrical machine 20.

[0069] By moving the sleeve 53 to the right, that is to say towards the heat engine, the secondary gearbox input shaft 45 is coupled to the idler gear 51 which meshes with a fixed gear 65 carried by the input shaft 60 of the heat engine. This connection drives the secondary electrical machine 40 and the heat engine operates in both directions: either the secondary machine 40 is the driving machine and allows the heat engine to start, or it is the receiving machine, that is to say the generator, and takes part of the power from the heat engine in order to recharge the battery, as can be seen on the power transmission path illustrated in solid lines in Figure 7.

[0070] The pair of pinions 51, 65, as well as the parking wheel 33 is inscribed in the axial edge of the crown wheel 102. This pair of pinions 51, 65 does not impact the length of the transmission and contributes to its compactness.

[0071] The input shaft 60 of the transmission corresponds to the shaft of the thermal engine.

[0072] From left to right in Figure 2, the input shaft 60 carries five fixed gears, namely a gear 61 corresponding to the gear of the second gear, a gear 62 corresponding to the gear of the first gear, a gear 63 corresponding to the gear of the third gear, a gear 64 corresponding to the gear of the fourth gear and the gear 65 corresponding to the gear for driving the heat engine by the generator 40.

[0073] Transmission 1 has four independent gears for the thermal engine.

[0074] The fixed gears 62, 63, that is to say the odd ratios, mesh respectively with the idle gears 93, 94 carried by the second secondary shaft 90, respectively idle gear 93 of first and idle gear 94 of third. This shaft 90 also carries a coupling device comprising a hub 95 and a sliding sleeve 96 or sliding sleeve.

[0075] By moving the sleeve 96 to the left, i.e. towards the electric machine 40, the secondary shaft 90 is coupled to the first idler gear 93. The first gear is established as can be seen on the power transmission path illustrated in dotted lines in Figure 5. By moving the sleeve 96 to the right, i.e. towards the heat engine, the secondary shaft 90 is coupled to the third idler gear 94. The third gear is established as can be seen on the power transmission path illustrated in solid lines in Figure 5 and in broken lines for the common part.

[0076] These two ratios are independent gear ratios and the engagements are independent of that of the electric machines 20, 40.

[0077] The fixed gears 61, 64, that is to say the even ratios, mesh respectively with the idle gears 83, 84 carried by the first secondary shaft 80, respectively the second idle gear 83 and the fourth idle gear 84. This shaft 80 also carries a coupling device comprising a hub 85 and a sliding sleeve 86 or sliding sleeve.

[0078] By moving the sleeve 86 to the left, i.e. towards the electric machine 40, the secondary shaft 80 is coupled to the second idler gear 83. The second gear is established as can be seen on the power transmission path illustrated in dotted lines in Figure 6.

[0079] By moving the sleeve 86 to the right, i.e. towards the heat engine, the secondary shaft 80 is coupled to the fourth idler gear 84. The fourth gear is established as can be seen on the power transmission path illustrated in solid lines in Figure 6 and in broken lines for the common part.

[0080] These two ratios are independent gear ratios and the engagements are independent of that of the electric machines 20, 40.

[0081] Thanks to the invention, it is possible to use the generator as a motor for electric driving. By supporting the traction machine, it allows the latter to be reduced in size.

Claims

CLAIMS 1. Transmission (1) for a motor vehicle with hybrid propulsion or traction, the transmission (1) comprising: - a first machine (20) comprising a rotor (22) secured to a main power transmission shaft (21) secured in rotation to a main gearbox input shaft (25) by a splined connection (29), the main gearbox input shaft (25) being configured to be coupled or decoupled from the wheels of the vehicle by a first coupling system (31, 32), - a second machine (40) comprising a rotor (42) secured to a secondary power transmission shaft (41) rotationally secured to a secondary gearbox input shaft (45) by a splined connection (49), the secondary gearbox input shaft (45) being configured to be coupled or decoupled from the wheels of the vehicle by a second coupling system (52, 53), and - a heat engine secured to an input shaft (60), characterized in that the second electric machine (40) is linked to the wheels independently of the heat engine.

2. Transmission (1) according to claim 1, in which the electrical machines (20, 40) are integrated in a dedicated compartment of the gearbox, at the end thereof.

3. Transmission (1) according to claim 1 or 2, wherein the electrical machines (20, 40) operate in oil and wherein the transmission (1) comprises a single cooling system for both electrical machines (20, 40) and the gearbox.

4. Transmission (1) according to any one of the preceding claims, comprising a first secondary shaft (80) configured to be coupled or decoupled from the main gearbox shaft (25) and a second secondary shaft (90) configured to be coupled or decoupled from the secondary gearbox shaft (45).

5. Transmission (1) according to claim 4, in which the main gearbox shaft (25) carries a single idler gear (30) and the first secondary shaft (80) carries a fixed pinion (82) configured to mesh with the first idler pinion (30) and a toothing (81) configured to mesh with a crown wheel (102) of a differential assembly (100).

6. Transmission (1) according to claim 4 or 5, in which the secondary gearbox input shaft (45) carries two idler gears (50, 51) and the second secondary shaft (90) carries a fixed gear (92) configured to mesh with a first intermediate gear (71) carried by an intermediate shaft (70) and configured to mesh with the first idler gear (50) of the secondary gearbox input shaft (45), the second secondary shaft (90) further carrying a toothing (91) configured to mesh with the crown wheel (102) of the differential assembly (100).

7. Transmission (1) according to claim 6, in which the input shaft (60) of the thermal engine carries a fixed pinion (65) configured to mesh with the second idler pinion (51) of the secondary gearbox input shaft (45).

8. Transmission (1) according to any one of the preceding claims, in which the transmission (1) has, for the thermal engine, several ratios independent of the electric machines (20, 40).

9. Transmission (1) according to claim 8, wherein the input shaft (60) of the heat engine carries five fixed gears, namely a gear (61) corresponding to the gear of the second gear, a gear (62) corresponding to the gear of the first gear, a gear (63) corresponding to the gear of the third gear, a gear (64) corresponding to the gear of the fourth gear and the gear (65) corresponding to the drive gear of the heat engine by the secondary electric machine (40), the fixed gears (62, 63), respectively of the first and third gears, being configured to mesh respectively with idle gears (93, 94) carried by the first secondary shaft (90) and the fixed gears (61, 64), respectively of the second and fourth gears, being configured to mesh respectively with idler gears (83, 84) carried by the second secondary shaft (80).

10. Transmission (1) according to any one of the preceding claims, further comprising a parking brake device comprising a toothed wheel (33), the axial position of said wheel (33) being inscribed in the axial edge of the crown wheel (102) of the differential assembly (100).

11. Transmission (1) according to claim 10, wherein the toothed wheel (33) is located on the main gearbox input shaft (25) of the main electrical machine (20) and is integrated in the axial space of the crown wheel (102).

12. Transmission (1) according to any one of the preceding claims, in which the main electric machine (20) is offset from the axis of the crankshaft of the thermal engine.

13. Motor vehicle with hybrid propulsion or traction comprising at least two drive wheels and a transmission (1) according to any one of the preceding claims configured to drive said drive wheels in rotation.

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