Powertrain for hybrid vehicles equipped with an epicyclic gear train and operating method

Abstract

Title: Powertrain for a hybrid vehicle equipped with an epicyclic gear train and method of operation. Powertrain (1) for a hybrid vehicle, comprising at least one internal combustion engine (4), a first electric motor (2), a second electric motor (3), an epicyclic gear train (7) with three points of rotation, and a gearbox (8) comprising at least one main drive shaft (5), a first shaft (6), and a second shaft (9), the second shaft (9) being rotationally linked to a first point of rotation of the epicyclic gear train (7), the internal combustion engine (4) being rotationally linked to a second point of rotation of the epicyclic gear train (7), characterized in that the second electric motor (3) is rotationally linked to a third point of rotation of the epicyclic gear train (7). Figure 1

Description

Title of the invention: Powertrain for hybrid vehicle equipped with an epicyclic gear train and operating method

[0001] The present invention relates to the field of transmission chains. The present invention relates more particularly to a traction chain provided with an epicyclic train of a vehicle comprising at least one thermal engine, an electric motor and a gearbox.

[0002] Hybrid vehicles are vehicles capable of transporting people and / or goods and equipped with at least one thermal engine and at least one electric motor capable of moving the vehicle by rotating the vehicle's wheels.

[0003] In some hybrid vehicles, the electric motor is accompanied by a second electric motor which can serve as a starter or generator. However, this second electric motor is permanently mechanically linked to the thermal engine, generating significant no-load losses and excessive energy consumption.

[0004] In such hybrid vehicles, the electric motor is commonly supplied with electrical energy by a battery and ensures the movement of the wheels, in particular when starting and up to speeds which can go, for example, up to 145 km / h. The operation of the electric motor takes into account the speed of movement of the vehicle but also the charge level of the battery supplying the electric motor.

[0005] When the charge level of the battery intended to supply energy to the electric motor is low, the electric motor is not supplied with sufficient energy to set the vehicle's wheels in motion when starting. In such a situation, the thermal engine ensures the vehicle's wheels are set in motion when starting. Such a situation requires the use of a clutch mechanism allowing a gradual transfer of torque from the thermal engine in order to set the vehicle's wheels in motion when starting. A disadvantage of this technology is that the clutch mechanism is an expensive part. Another disadvantage is that this clutch mechanism wears out. It is therefore necessary to ensure its replacement.

[0006] The present invention proposes to overcome the drawbacks of the prior art set out above by proposing a powertrain for a hybrid vehicle, the powertrain comprising at least one thermal engine, a first electric motor, a second electric motor participating together or individually in the drive. of the hybrid vehicle, the powertrain comprising an epicyclic gear train with three points of rotation and a gearbox comprising at least one main drive shaft, a first shaft and a second shaft, the gearbox being configured to transmit a torque from the heat engine or the first electric motor to the first shaft, the second shaft being rotationally connected to a first point of rotation of the epicyclic gear train, the heat engine being rotationally connected to a second point of rotation of the epicyclic gear train, characterized in that the second electric motor is rotationally connected to a third point of rotation of the epicyclic gear train.

[0007] The present invention applies to a hybrid vehicle equipped with a dual engine. It should be noted that a hybrid vehicle is understood to mean a vehicle equipped with at least one electric motor and one thermal engine involved in setting the vehicle in motion. The electric motor and the thermal engine provide a torque enabling the wheels of the vehicle to rotate and thus setting said hybrid vehicle in motion. It should also be noted that torque is understood to mean all the forces generated by the first electric motor, the second electric motor or the thermal engine enabling a shaft or a pinion of a shaft or an element of the epicyclic gear train to rotate.

[0008] The epicyclic gear train is an epicyclic gear train with at least two points of rotation, the third point being able to be a point of rotation or a point of blocking the rotation. Two points of rotation are understood to mean that each entry or exit point of the epicyclic gear train is driven in rotation. In one example, none of the points of rotation of the epicyclic gear train is blocked in rotation by contact with a frame of the hybrid vehicle. In an alternative, one of the points is blocked in rotation by connecting it to a reversible blocking member of the brake or dog clutch type, such a blocking member being able in a first situation to allow the rotation of the point concerned or in a second situation to prohibit the rotation of the point concerned.

[0009] According to a characteristic of the invention, the epicyclic gear train comprises a crown, a planet carrier and a sun gear, the second shaft being rotationally connected to the crown of the epicyclic gear train, the heat engine is rotationally connected to the planet carrier of the epicyclic gear train and the second electric motor is rotationally connected to the sun gear of the epicyclic gear train. The second shaft mentioned here is a primary shaft of the gearbox. It should be noted that rotationally connected means that the rotary motion of one element is transmitted to the other element to which it is rotationally connected. It is understood that a rotary motion of the crown is transmitted to the second shaft, that a rotary motion generated by the heat engine is transmitted to the planet carrier and that a rotary motion generated by the second electric motor is transmitted to the sun gear of the epicyclic gear train.

[0010] According to another characteristic of the invention, the second shaft and the main drive shaft are concentric. This characteristic makes it possible to reduce the size of the gearbox and thus to limit the space occupied by the drive train.

[0011] According to a characteristic of the invention, the second shaft, the drive shaft and the planet carrier are concentric. It is understood from this characteristic that the axes of the second shaft, the main drive shaft and the planet carrier are coaxial.

[0012] According to another characteristic of the invention, the second electric motor has a variable rotation speed. This variable rotation speed makes it possible to precisely control the torque supplied by the second electric motor in order to provide a resistive torque to the torque generated by the thermal engine, to allow the thermal engine to put the hybrid vehicle in motion when the latter is stationary.

[0013] According to a characteristic of the invention, the thermal engine imposes a first torque on the planet carrier, the second electric motor imposes a second torque on the sun gear, the second shaft being driven in rotation according to a third torque which is a function of the first torque and the second torque.

[0014] According to another characteristic of the invention, the sun gear is driven in rotation in a direction of rotation opposite to the direction of rotation of the planet carrier. In an operating mode in which the heat engine ensures the movement of the hybrid vehicle when the latter is stationary, the sun gear is driven in rotation in a direction of rotation opposite to the direction of rotation of the planet carrier so as to impose a resistive torque on the drive torque generated by the heat engine.

[0015] According to a characteristic of the invention, the first shaft is configured to drive the rotation of wheels of the hybrid vehicle.

[0016] According to another characteristic of the invention, the thermal engine drives the planet carrier in rotation according to the first torque, the second electric motor generating on the planetary a resistive torque which opposes the first torque so as to progressively increase the rotation speed of the first shaft.

[0017] According to a characteristic of the invention, the second electric motor is configured to recharge at least one electrical element, in particular an electrical energy storage element such as a battery of the hybrid vehicle, when the main drive shaft drives the second shaft in rotation.

[0018] According to another characteristic of the invention, the gearbox comprises a third shaft which connects the second electric motor in rotation to the epicyclic gear train.

[0019] According to a characteristic of the invention, the third shaft is linked in rotation to the sun gear of the epicyclic gear train.

[0020] The invention also relates to a hybrid vehicle comprising a powertrain conforming to any one of the preceding characteristics.

[0021] The invention also relates to a method for implementing a traction chain, the implementation method comprising at least: - a first operating mode in which a torque supplied to the wheels is delivered by the first electric motor; - a second operating mode in which the torque supplied to the wheels is delivered by the thermal engine; - a third operating mode which consists of setting the vehicle in motion, during which the thermal engine generates the first torque which passes through the epicyclic gear train and the second electric motor generates a second variable resistive torque which passes through the epicyclic gear train so as to set the vehicle in motion.

[0022] The third operating mode begins when the hybrid vehicle is stationary, that is to say when the wheels of the vehicle are not rotated. It is therefore the thermal engine combined with the second electric motor via the epicyclic gear train which sets the hybrid vehicle in motion. Once the vehicle is set in motion and from a given vehicle travel speed, the method for implementing the powertrain applies the first operating mode and / or the second operating mode.

[0023] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description which follows on the one hand, and several examples of embodiment given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0024] [Fig.l] schematically illustrates a drive train according to the invention when the vehicle is in neutral;

[0025] [Fig.2] schematically illustrates the traction chain of [Fig.l] according to the third operating mode, when the heat engine is used to generate the first torque and the second electric motor generates a resistive torque allowing the vehicle to be set in motion when the vehicle is initially stationary;

[0026] [Fig.3] schematically illustrates the drive train of [Fig.l], according to the first operating mode in which the vehicle is set in motion by the first electric motor;

[0027] [Fig.4] schematically illustrates the traction chain according to a mode of operation operation in which the first electric motor and the second electric motor set the vehicle in motion;

[0028] [Fig.5] schematically illustrates the drive train according to the second operating mode in which the thermal engine ensures the movement of the vehicle and wherein the first electric motor and the second electric motor simultaneously recharge an electrical energy storage element;

[0029] [Fig.6] schematically illustrates the powertrain according to an operating mode in which the thermal engine and the first electric motor jointly set the vehicle in motion and in which the second electric motor recharges an electrical energy storage element;

[0030] [Fig.7] schematically illustrates the drive train according to a variant of the invention when the vehicle is in neutral;

[0031] [Fig.8] schematically illustrates the powertrain of [Fig.7], according to an operating mode in which the first electric motor, the second electric motor and the thermal engine deliver a torque which sets the vehicle in motion.

[0032] The features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the art.

[0033] Furthermore, it should be noted that with reference to the different torques described in the following description, the first torque C1 corresponds to the torque generated by the heat engine and is schematically represented by a two-dash line, the second torque C2 corresponds to the torque generated by the second electric motor and is schematically represented by a short broken line, the third torque C3 corresponds to the torque resulting from the first torque C1 and the second torque C2 and is schematically represented by a one-dash line, and the fourth torque C4 corresponds to the torque generated by the first electric motor and is schematically represented by a long broken line. It should also be noted that each torque is expressed in Newton meters.

[0034] The second torque C2 can be a torque resistive to the first torque Cl, that is to say which opposes the torque generated by the thermal engine within the epicyclic train.

[0035] [Fig.l] illustrates a powertrain 1 of a hybrid vehicle comprising a first electric motor 2, a second electric motor 3, a heat engine 4, an epicyclic gear train 7 and a gearbox 8. The gearbox 8 comprises a main drive shaft 5, a first shaft 6 and a second shaft 9.

[0036] The first electric motor 2 is rotatably connected to a main drive shaft 5. It should be noted that, in the present case, the first electric motor 2 and the main drive shaft 5 are rotationally linked in such a way that the torque generated by the first electric motor 2 is transmitted to the main drive shaft 5. The first electric motor 2 is supplied with energy by an electrical energy storage element, for example one or more batteries, not shown here, and provides a variable torque to the main drive shaft 5 according to the demand of the user of the vehicle.

[0037] The main drive shaft 5 comprises a first fixed pinion 51 and a second fixed pinion 52 each integral with the main drive shaft 5. It should be noted that “fixed”, in connection with the first fixed pinion 51 and the second fixed pinion 52 but also for all the fixed pinions of the present description, is understood to mean that the fixed pinions are integral in rotation with the associated shaft, such that the rotational driving of a fixed pinion drives the associated shaft in rotation. The first fixed pinion 51 having a diameter smaller than the diameter of the second fixed pinion 52. When the main drive shaft 5 is rotated by the first electric motor 2, the first fixed pinion 51, the second fixed pinion 52 and the main drive shaft 5 are rotated at an identical rotational speed.It is understood that the first fixed pinion 51 and the second fixed pinion 52 are integral with the main drive shaft 5 and that the axes of rotation of the main drive shaft 5, the first fixed pinion 51 and the second fixed pinion 52 are coaxial.

[0038] Parallel to the main drive shaft 5 extends the first shaft 6 whose role is to transmit a torque from the drive train, whatever its origin, to a differential connected to the wheels of the vehicle. It is understood that the first shaft 6 is connected to the wheels of the vehicle and that the rotation of the first shaft 6 makes it possible to rotate the wheels of the vehicle and thus to move the vehicle.

[0039] The first shaft 6 comprises a first idler gear 61, a second idler gear 62, a third fixed gear 63 and a fourth fixed gear 64. The first idler gear 61 is aligned with the first fixed gear 51 and the second idler gear 62 is aligned with the second fixed gear 52. The first idler gear 61 and the second idler gear 62 are respectively rotated by the first fixed gear 51 and the second fixed gear 52, these gears being meshed with each other. The first idler gear 61 has a diameter greater than the diameter of the first fixed gear 51 and the second idler gear 62 has a diameter less than the diameter of the second fixed gear 52. It is understood that these different diameters make it possible to generate two different speed ratios.

[0040] It should be noted that the designation “idle” in connection with the first idle gear 61, the second idle gear 62, and more generally with the idle gears which will be described in the present description, corresponds to a pinion mounted, for example, on a needle bearing and capable of rotating on the shaft which carries it without driving said shaft in rotation.

[0041] The first shaft 6 comprises, between the first idler gear 61 and the second idler gear 62, a first coupling means 65 arranged on the first shaft 6. More particularly, the first coupling means 65 may be, by way of non-limiting examples, a dog clutch system. This first coupling means 65 makes it possible to connect the first shaft 6 in rotation with the first idler gear 61 or with the second idler gear 62.

[0042] In the embodiment shown in [Fig. 1], the first coupling means 65 can take three positions. In a first position of the first coupling means 65, the first coupling means 65 is associated with the first idler gear 61. In this first position of the first coupling means 65, the first idler gear 61 is rotationally connected to the first shaft 6. In a second position of the first coupling means 65, the first coupling means 65 is not associated with either of the first and second idler gears 61 and 62. In a third position of the first coupling means 65, the first coupling means 65 is associated with the second idler gear 62. In this third position of the first coupling means 65, the second idler gear 62 is rotationally connected to the first shaft 6.

[0043] It is understood that the position of the first coupling means 65 makes it possible to control the rotation of the first shaft 6 as well as the rotation speed thereof, and more generally the speed of movement of the vehicle.

[0044] The main drive shaft 5 is a hollow shaft. This hollow within the main drive shaft 5 forms a channel within which the second shaft 9 extends such that the main drive shaft 5 and the second shaft 9 are concentric.

[0045] The second shaft 9 extends parallel to the first shaft 6 and comprises a third idler gear 91, a fourth idler gear 92 and a fifth fixed gear 93. The third idler gear 91 has a diameter smaller than the diameter of the fourth idler gear 92. The third idler gear 91 is aligned with the third fixed gear 63 and the fourth idler gear 92 is aligned with the fourth fixed gear 64. More particularly, the arrangement of the third idler gear 91 and the fourth idler gear 9 is such that the third idler gear 91 and the fourth idler gear 92 can respectively be rotated by, or rotate, the third fixed gear 63 and the fourth fixed gear 64. It should be noted that the diameter of the third fixed gear 63 is greater than the diameter of the fourth fixed gear 64.

[0046] The second shaft 9 comprises, between the third idler gear 91 and the fourth idler gear 92, a second coupling means 95. This second coupling means 95 can, like the first coupling means 65, take three positions. In a first position of the second coupling means 95, the third idler gear 91 is rotatably connected to the second shaft 9. In a second position of the second coupling means 95, neither of the third idler gear 91 nor of the fourth idler gear 92 is rotatably connected to the second shaft 9. In a third position of the second coupling means 95, the fourth idler gear 92 is rotatably connected to the second shaft 9.

[0047] It should be noted that the diameter of the third idler gear 91 is smaller than the diameter of the third fixed gear 63 and the diameter of the fourth idler gear 92 is smaller than the diameter of the fourth fixed gear 64. Furthermore, the third fixed gear 63 and the fourth fixed gear 64 are fixed gears of the first shaft 6, in other words, the rotation of the third fixed gear 63 or of the fourth fixed gear 64 causes the rotation of the first shaft 6, and more broadly the movement of the vehicle.

[0048] It is understood that the diameters of these different pinions, namely the third fixed pinion 63, the fourth fixed pinion 64, the third idler pinion 91 and the fourth idler pinion 92, make it possible to generate two different rotation speed ratios of the first shaft 6 when the first shaft 6 is driven in rotation by the second shaft 9. It is understood that the position of the second coupling means 95, like the first coupling means 65, makes it possible to control the rotation of the first shaft 6 as well as the rotation speed of this first shaft 6, and more broadly the speed of movement of the vehicle.

[0049] As described above, the second shaft 9 comprises a fifth fixed pinion 93. This fifth fixed pinion 93 is rotationally connected to a sixth fixed pinion 103 rotationally secured to a third shaft 10 extending substantially parallel to the second shaft 9. This third shaft 10 comprises the sixth fixed pinion 103, a fifth idler pinion 101 and a sixth idler pinion 102. It should be noted that the fifth idler pinion 101 has a diameter smaller than the diameter of the sixth idler pinion 102. The fifth idler pinion 101 is rotationally connected to the second fixed pinion 52 of the main drive shaft 5 and the sixth idler pinion 102 is rotationally connected to the fourth idler pinion 92 of the second shaft 9.

[0050] A third coupling means 105, similar to the first coupling means 65 and the second coupling means 95, is arranged between the fifth idler gear 101 and the sixth idler gear 102. The third coupling means 105 can, like the first coupling means 65 and the second coupling means 95, take three positions. In a first position of the third coupling means 105, the fifth idler gear 101 is rotatably connected to the third shaft 10. In a second position of the third coupling means 105, the third coupling means 105 is in a neutral position, i.e. a position in which the third coupling means 105 is not rotationally connected to any of the fifth or sixth idler gears 101 and 102. In a third position of the third coupling means 105, the sixth idler gear 102 is rotationally connected to the third shaft 10.

[0051] The epicyclic gear train 7 is a three-point rotation epicyclic gear train. It should be understood that the epicyclic gear train 7 has three output or input points for a torque. These torques can be sent to or come from the second electric motor 3, the thermal engine 4 or the second shaft 9.

[0052] The epicyclic gear train 7 comprises a ring gear 74 forming a first point of rotation of the epicyclic gear train 7, satellites 72 of a planet carrier 73, the planet carrier 73 forming a second point of rotation of the epicyclic gear train 7 and a sun gear 71 forming a third point of rotation of the epicyclic gear train 7. The epicyclic gear train 7 has three points of rotation in that no aforementioned point of rotation is fixed relative to a frame of the gearbox or the hybrid vehicle. In other words, the sun gear 71, the planet carrier 73 and the ring gear 74 are rotated in the epicyclic gear train 7 according to the invention. It is understood that the sun gear 71, the planet carrier 73 and the ring gear 74 are not rotationally connected to a frame of the hybrid vehicle.

[0053] More particularly, the crown 74 is a toothed wheel comprising teeth extending radially inwards, that is to say towards the axis of rotation of the epicyclic gear train, and intended to cooperate with teeth of the planet gears 72. The planet gears 72 are gears present, in the embodiment, three in number and distributed radially inside the crown 74. The teeth of the planet gears 72 are engaged with the teeth of the crown 74 and are capable of mutually driving the crown 74 or the planet carrier 73 in rotation. The sun gear 71 forms a toothed wheel comprising teeth oriented radially towards the outside of the epicyclic gear train. The teeth of the sun gear 71 are arranged, at least in part, opposite the teeth of the planet gears 72 such that the teeth of the sun gear 71 are capable of driving the planet gears 72 in rotation.

[0054] Note that the planetary gear 71, the planet carrier 73 and the satellites 72 are arranged ra dially inside the crown 74. It should be noted that the crown 74 rotates about a first axis of rotation 90 coaxial with the axis of rotation of the second shaft 9. The sun gear 71 rotates about a second axis of rotation 30 and the planet carrier 73 rotates about a third axis of rotation 40. The first, second and third axes of rotation 90, 30 and 40 are coaxial with each other.

[0055] The second shaft 9 is connected in rotation with the crown 74 of the epicyclic gear train 7. It is understood that the rotation of the crown 74 of the epicyclic gear train 7 causes the rotation of the second shaft 9. As described previously, this second shaft 9 directly transmits a torque to the first shaft 6 via the fourth idler gear 92 and the fourth fixed gear 64 when the second coupling means 95 is in its third position, or, by the third idler gear 91 and the third fixed gear 63 when the second coupling means 95 is in its first position.

[0056] The satellites 72 of the epicyclic gear train 7 are carried by the planet carrier 73 which is linked in rotation with the heat engine 4. It should be noted that the heat engine 4 generates a driving torque transmitted to the planet carrier 73. It is understood that the heat engine 4 transmits a driving torque to a transmission shaft 731 of the planet carrier 73, this transmission shaft 731 having an axis of rotation coaxial with the third axis of rotation 40 of the planet carrier 73.

[0057] The sun gear 71 is rotationally connected to the second electric motor 3. Furthermore, in the embodiment shown, the sun gear 71 is rotationally connected to the second electric motor 3 via a fourth shaft 31 and a seventh fixed pinion 32. More particularly, the second electric motor 3 drives the fourth shaft 31 in rotation, which is rotationally connected to the seventh fixed pinion 32 which is rotationally connected to the sun gear 71.

[0058] [Fig.2] illustrates the traction chain 1 as shown in [Fig.l] according to the third mode of operation, the thermal engine 4 being used to generate a torque to set the vehicle in motion when the vehicle is initially stationary. It should be noted that in the embodiment shown, the first electric motor 2 is stationary.

[0059] The heat engine 4 drives the transmission shaft 731 in rotation with a first torque CL. It should be noted that “torque” means the force or combination of forces which produces a rotational movement of the shaft concerned, in this case the transmission shaft 731. The first torque Cl is transmitted to the planet carrier 73 which is driven in rotation according to the first torque CL.

[0060] The second electric motor 3 drives the fourth shaft 31 in rotation with a second torque C2, the second torque C2 is transmitted to the sun gear 71. It should be noted that, in the embodiment represented by [Fig.2], the sun gear 71 and the planet carrier 73 are driven in rotation in an opposite direction of rotation, in particular for a vehicle starting situation. Outside of this situation, the direction of rotation of the rotating elements of the epicyclic gear train 7 is identical.

[0061] The crown 74 of the epicyclic gear train 7 is driven in rotation by the planet carrier 73 via the planet gears 72. It is understood that the first torque C1 generated by the heat engine 4 makes it possible to drive, via the planet carrier 73 and the planet gears 72, the crown 74, and more particularly the second shaft 9 linked in rotation with the crown 74 of the epicyclic gear train 7.

[0062] In the embodiment shown here, the first torque Cl generated by the motor thermal motor 4 has a variable rotation speed as does the second torque C2 generated by the second electric motor 3. The second torque C2 generated by the second electric motor 3 is a resistive torque to the first torque Cl. Resistive torque should be understood to mean that the second torque C2 generated by the second electric motor 3 makes it possible to rotate the crown 74 at a rotation speed lower than the rotation speed of the planet carrier 73. As a result, the second shaft 9 is rotated with a third torque C3 whose rotation speed is lower than the rotation speed of the first torque Cl, thus making it possible to gradually start the hybrid vehicle.

[0063] The second torque C2 is variable in that it can be adapted so that the rotational speed of the second shaft 9 increases progressively. This progressive increase in the rotational speed of the second shaft 9 is achieved by a progressive increase in the resistive torque, i.e. in the embodiment shown, the second torque C2, generated by the second electric motor 3.

[0064] More particularly, the rotational speed of the crown 74 must be increased progressively so that the vehicle can be set in motion progressively, while the latter is initially stationary.

[0065] [Fig. 3] schematically illustrates the drive train 1 in which the first electric motor 2 transmits a fourth torque C4 to the first shaft 6 allowing the vehicle to be kept in motion. This is a mode of vehicle movement known as “all electric”.

[0066] In the embodiment shown in [Fig. 3], the first electric motor 2 drives the main drive shaft 5 in rotation according to the fourth torque C4, in accordance with the first operating mode. It should be noted that in this embodiment shown, the heat engine 4 and the second electric motor 3 are stopped.

[0067] The first coupling means 65 is in its third position in which the second idler gear 62 is rotatably connected to the first shaft 6. The second coupling means 95 and the third coupling means 105 are respectively in their second position in which neither of the idler gears 91 and 92 is rotatably connected to the second shaft 9 and neither of the idler gears 101 and 102 is rotatably connected to the third shaft 10. The fourth torque C4 generated by the first electric motor 2 is transmitted by the second fixed gear 52 of the main drive shaft 5 to the second idler gear 62 which is rotatably connected to the first shaft 6 such that the first electric motor 2 drives the first shaft 6 in rotation according to the fourth torque C4.

[0068] [Fig.4] illustrates a mode of operation similar to that of [Fig.3], in which the first electric motor 2 and the second electric motor 3 provide a torque to set the vehicle in motion. This is a mode of vehicle movement known as “all-electric with boost”.

[0069] As illustrated in [Fig. 4], the first electric motor 2 generates the fourth torque C4 driving the first shaft 6 in rotation to set the vehicle in motion. In the embodiment shown here, in which the heat engine 4 is stopped, the second electric motor 3 also delivers its torque to the first shaft 6 so as to participate in setting the vehicle in motion. According to the example illustrated here, the third coupling means 105 is in its first position in which the fifth idler gear 101 is linked in rotation with the third shaft 10. In this configuration of the powertrain 1, the fourth torque C4 and the second torque C2 combine at the second fixed gear 52 of the main drive shaft 5. The second idler gear 62 transmits a combined torque C5 to the first shaft 6.The combination of the second torque C2 and the fourth torque C4 can also occur at the level of the first shaft 6, the fourth torque C4 driving the primary shaft 6 either when the first coupling means 65 is clutched on the second idler gear 62, or when the first coupling means 65 is clutched on the first coupling means 61.

[0070] According to a first alternative, the second pair C2 joins the first shaft 6 by a dog clutch of the second coupling means 95 on the fourth idler gear 92, then via the fourth fixed gear 64. According to another alternative, the second pair C2 joins the first shaft 6 by a dog clutch of the second coupling means 95 on the third idler gear 91, then via the third fixed gear 63.

[0071] The second shaft 9 is driven in rotation according to the second torque C2, via a rotation of the crown 74 of the epicyclic gear train 7. The second torque C2 is generated by the second electric motor 3, passes through the sun gear 71 via the satellites 72, until it drives the crown 74 in rotation.

[0072] During this operating mode, the second electric motor 3 behaves like an electric motor. In this operating mode, the powertrain 1 which is the subject of the invention moves the vehicle in an all-electric mode, that is to say without the input of torque by the thermal engine 4, but with an increased acceleration effect compared to the embodiment of [Fig.3].

[0073] [Fig. 5] illustrates an operating mode in which the heat engine 4 drives the first shaft 6 in rotation so that the vehicle is set in motion jointly with the recharging of the electrical energy storage element 12 by the first electric motor 2 and by the second electric motor 3.

[0074] In the embodiment shown, the heat engine 4 generates the first torque Cl which is transmitted on the one hand, by the sun gear 71 to the fourth shaft 31 and on the other hand, by the crown 74 to the second shaft 9. The first torque Cl separates in a couple Cia which drives the second electric motor 3 in rotation, the latter acting as a generator making it possible to generate energy for the electrical energy storage element 12.

[0075] A torque Clb of the first torque C1 passes through the second shaft 9 and through the fifth fixed pinion 93 to reach the sixth fixed pinion 103 of the third shaft 10. The third coupling means 105 is in its first position in which the fifth idler pinion 101 is rotatably connected to the third shaft 10. The torque Clb is thus transmitted from the third shaft 10 to the main drive shaft 5 by means of the fifth idler pinion 101. It should be noted that in the embodiment shown, the first electric motor 2 operates as an electric generator generating electrical energy that can also be stored in the electrical energy storage element 12. The first coupling means 65 is in its first position in which the first idler pinion 61 is rotatably connected to the first shaft 6.Thus, the thermal engine 4 generates a torque allowing an electrical energy storage element to be recharged while driving the first shaft 6 in rotation so as to set the vehicle in motion.

[0076] [Fig. 6] illustrates an operating mode in which the first electric motor 2 and the heat engine 4 jointly participate in driving the first shaft 6 in rotation and in which the second electric motor 3 generates electrical energy intended to be stored in the electrical energy storage element 12. In this operating mode, the first electric motor 2 generates the fourth torque C4 driving the main drive shaft 5 in rotation. The first coupling means 65 is in its third position in which the second idler gear 62 is connected in rotation with the first shaft 6. The fourth torque C4 is thus transmitted from the main drive shaft 5 to the first shaft 6 by means of the second fixed gear 52 and the second idler gear 62.

[0077] The heat engine 4 generates the first torque C1 transmitted to the planet carrier 73. The first torque C1 is separated into a torque Cia and a torque Clb, the torque Cia being transmitted to the sun gear 71 so as to rotate the second electric motor 3 which generates electrical energy transmitted to the electrical energy storage element 12 while the torque Clb is transmitted to the ring gear 74 rotating the second shaft 9. The second coupling means 95 is in its third position in which the fourth idler gear 92 is connected in rotation with the second shaft 9. The torque Clb is transmitted from the second shaft 9 to the first shaft 6 by means of the fourth idler gear 92 and the fourth fixed gear 64 of the first shaft 6. It should be noted that the first electric motor 2 can adapt its rotation speed so as to align it with the rotation speed of the heat engine 4.

[0078] [Fig.7] illustrates a variant of the drive train 1 in which the second electric motor is rotationally connected to the planet carrier 73 via the third shaft 10. The fourth shaft 31 is rotationally connected to the second electric motor 3 and comprises the seventh fixed pinion 32. In this embodiment, the seventh fixed pinion 32 is rotationally connected to an eighth fixed pinion 104 of the third shaft 10. It is understood that the second electric motor 3 can drive or be driven in rotation directly by the third shaft 10.

[0079] In the embodiment shown in [Fig. 7], the sixth fixed pinion 103 is rotationally connected to an epicyclic gear train 11 different from that shown in FIGS. 1 to 6. This epicyclic gear train 11 comprises a sun gear 111 rotationally connected to the sixth fixed pinion 103, a planet carrier 113 comprising planet gears 112 and rotationally connected to the drive shaft 731 of the heat engine 4 and a crown 114 rotationally connected to the second shaft 9.

[0080] More particularly, the crown 114 is a toothed wheel comprising teeth extending radially inwards, that is to say towards the axis of rotation of the epicyclic gear train, and intended to cooperate with teeth of the satellites 112. The satellites 112 are gears present, in the embodiment, three in number and distributed radially inside the crown 114. The teeth of the satellites 112 are engaged with the teeth of the crown 114 and are capable of mutually driving the crown 114 or the planet carrier 113 or the sun gear 111 in rotation. The sun gear 111 forms a toothed wheel comprising teeth oriented radially towards the outside of the epicyclic gear train and meshing with the satellites 112. It should be noted that the crown 114 rotates around a first axis of rotation 90 coaxial with the axis of rotation of the second shaft 9.The sun gear 111 rotates about a second axis of rotation 30 and the planet carrier 113 rotates about a third axis of rotation 40. The first, second and third axes of rotation 90, 30 and 40 are coaxial with each other.

[0081] It is noted that the sun gear 111, the satellites 112 and the crown 114 are arranged radially inside the planet carrier 113. [Fig.8] schematically illustrates the drive train 1 of [Fig.7] in which the first electric motor 2, the second electric motor 3 and the thermal engine 4 each simultaneously transmit a torque allowing the vehicle to be set in motion.

[0082] In the embodiment shown, the first electric motor 2 generates the fourth torque C4, the first coupling means 65 being in its third position in which the second idler gear 62 is rotationally connected to the first shaft 6. The fourth torque C4 is then transmitted to the first shaft 6 by means of the second fixed gear 52 of the main drive shaft 5 and the second idler gear 62.

[0083] The second electric motor 3 generates the second torque C2 which is transmitted to the third shaft 10 by means of the seventh fixed gear 32 and the eighth fixed gear 104. The third coupling means 105 is in its first position in which the fifth idler gear 101 is rotationally connected to the second fixed gear 52. The second torque C2 is thus transmitted to the main drive shaft 5, then to the first shaft 6. It is understood that, in the embodiment shown, the second electric motor 3 is capable of generating the torque C2 transmitted to the first shaft 6 without passing through the epicyclic gear train 11 so that said torque directly participates in setting the hybrid vehicle in motion.

[0084] The heat engine 4 generates the first torque C1 transmitted to the planet carrier 113 by means of the transmission shaft 731. The planet carrier 113 sets the planets 112 in rotation, which in turn set the crown 114 in rotation, and consequently the second shaft 9. This rotation is made possible by the fact that a torque coming from the second electric motor 3 reaches the sun gear 111.

[0085] The second coupling means 95 is in its first position in which the third idler gear 91 is linked in rotation with the second shaft 9. This third idler gear 91 drives in rotation the third fixed gear 63 of the first shaft 6.

[0086] The invention achieves the aim it set itself by proposing a powertrain in which a second electric motor is capable of generating a torque that is resistive to a drive torque of a heat engine such that the heat engine is capable of setting the vehicle in motion after the vehicle has stopped. In addition, the invention limits the energy losses that may result from a permanent mechanical connection between the heat engine and the second electric motor.

Claims

Claims

1. Powertrain (1) for a hybrid vehicle, the powertrain (1) comprising at least one heat engine (4), a first electric motor (2), a second electric motor (3) participating together or individually in the drive of the hybrid vehicle, the second electric motor (3) being of variable rotation speed, the powertrain (1) comprising an epicyclic gear train (7, 11) with three rotation points and a gearbox (8) comprising at least one main drive shaft (5), a first shaft (6) and a second shaft (9), the gearbox (8) being configured to transmit a torque from the heat engine (4) or from the first electric motor (2) to the first shaft (6), the second shaft (9) being rotationally connected to a first rotation point of the epicyclic gear train (7, 11), the heat engine (4) being rotationally connected to a second rotation point of the epicyclic gear train (7, 11),characterized in that the second electric motor (3) is rotationally connected to a third point of rotation of the epicyclic gear train (7, 11).,

2. Powertrain (1) according to the preceding claim, the epicyclic gear train (7, 11) comprising a crown (74, 114), a planet carrier (73, 113) and a sun gear (71, 111), characterized in that the second shaft (9) is rotationally connected to the crown (74, 114) of the epicyclic gear train (7, 11), the heat engine (4) being rotationally connected to the planet carrier (73, 113) of the epicyclic gear train (7, 11) and the second electric motor (3) is rotationally connected to the sun gear (71, 111) of the epicyclic gear train (7, H).

3. A traction chain (1) according to any one of the preceding claims, characterized in that the second shaft (9) and the main drive shaft (5) are concentric.

4. Traction chain (1) according to claim 2, characterized in that the second shaft (9), the main drive shaft (5) and the planet carrier (73, 113) are concentric.

5. Powertrain (1) according to any one of claims 2 to 4, in which the thermal engine (4) imposes a first torque (Cl) on the planet carrier (73, 113), the second electric motor (3) imposes a second torque (C2) on the sun gear (71, 111), characterized in that the second shaft (9) is driven in rotation according to a third torque (C3) which is a function of the first torque (Cl) and the second torque (C2).

6. Powertrain (1) according to the preceding claim, in which the heat engine (4) drives the planet carrier (73, 113) in rotation according to the first torque (Cl), characterized in that the second electric motor (3) generates on the sun gear (71, 111) a resistive torque which opposes the first torque (Cl) so as to progressively increase the rotation speed of the first shaft (6).

7. Traction chain (1) according to any one of claims 2 to 5, characterized in that the sun gear (71, 111) is driven in rotation in a direction of rotation opposite to the direction of rotation of the planet carrier (73, 113).

8. Powertrain (1) according to any one of the preceding claims, characterized in that the gearbox (8) comprises a third shaft (10) which rotatably connects the second electric motor (3) to the epicyclic gear train (11).

9. Hybrid vehicle comprising a powertrain (1) according to any one of the preceding claims.

10. Method for implementing a powertrain (1) according to any one of claims 1 to 8, the implementation method comprising at least: - a first operating mode in which a torque supplied to the wheels is delivered by the first electric motor (2); - a second operating mode in which the torque supplied to the wheels is delivered by the heat engine (4); - a third operating mode which consists of setting the vehicle in motion, during which the heat engine (4) generates the first torque (C1) which passes through the epicyclic gear train (7, 11) and the second electric motor (3) generates a second variable resistive torque (C2) which passes through the epicyclic gear train (7, 11) so as to set the vehicle in motion.

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