Powertrain, vehicle, control method and assembly method

Abstract

The invention relates to a powertrain (1) of a pedal-vehicle propulsion assembly, the powertrain comprising a differential system, a first electric motor (40) and a second electric motor (50), and an electronic board (19) supporting at least one control unit (19) capable of controlling the first motor and the second motor. The first motor and the second motor respectively have an output shaft (402, 502) driven by a rotor, each output shaft driving a shaft-mounted pinion (101, 54). The powertrain is such that the output shaft (402) of the first motor and the output shaft (502) of the second motor extend through a plane (80) comprising a face of the electronic board (19), the shaft-mounted pinion (101) driven by the first motor and the shaft-mounted pinion (54) driven by the second motor being on the same side of the plane.

Description

[0001] POWERTRAIN ASSEMBLY, VEHICLE, INSPECTION METHOD AND ASSEMBLY METHOD

[0002] technical field

[0003] The present invention relates to a powertrain of a pedal vehicle propulsion assembly, a vehicle with the powertrain, a method of controlling the powertrain and a method of assembling the powertrain.

[0004] Previous art

[0005] Powertrains are known from the prior art, for example, documents WO2013 / 160477, WO2016 / 034574, WO2019 / 043123.

[0006] Document CN207241949 describes a pedal vehicle drive system, including a differential. In this system, a motor 12 drives gears 3A and 3B, which mesh with a ring gear 4 forming an input element. This results in an additional, bulky gear ratio (a stage). Furthermore, in the system described in this document, a sun gear 8 is concentric with the bottom bracket axle 9 and is driven by it. Consequently, the sun gear has a large diameter.

[0007] Documents US5375676, W02005 / 007439, and US2017217537 also describe powertrains. However, the powertrains described in these documents are complex to assemble.

[0008] There is a need for a powertrain that allows for simpler assembly.

[0009] Description of the invention

[0010] To this end, the invention proposes a powertrain for a pedal-powered vehicle propulsion system comprising

[0011] • A differential system comprising a first input element, a second input element, and an output element,

[0012] • A first motor comprising an output shaft driven by a rotor, the output shaft driving a shaft-mounted pinion which is the first input element, • A second motor comprising an output shaft driven by a rotor, the output shaft driving a shaft-mounted pinion, the second motor being connected to the differential system by the shaft-mounted pinion,

[0013] • An electronic board supporting at least one control unit capable of controlling the first and second motors, the electronic board having one face lying in a plane,

[0014] • An input body driven by a pedal assembly, the input body being connected to the second input element of the differential system,

[0015] • An output body driven in rotation by the output element of the differential system, and in which the output shaft of the first motor and the output shaft of the second motor extend through the plane comprising the face of the electronic board, the pinion shaft driven by the first motor and the pinion shaft driven by the second motor being on the same side of the plane.

[0016] According to one variant, the group includes a casing with several compartments, the first motor, the second motor and the electronic board are in the same first compartment and the shaft gears are in a second compartment.

[0017] According to one variant, the group also includes a structural piece delimiting the first and second compartments of the crankcase.

[0018] According to one variant, the electronic board extends parallel and against the structural part, the structural part supporting at least one of the parts among an output shaft bearing of the first motor, an output shaft bearing of the second motor, the electronic board.

[0019] According to one variant, the casing comprises a first shell defining the first compartment with the structural part and a second shell defining the second compartment with the structural part, the first shell and the second shell being on either side of the structural part.

[0020] In one variant, the assembly further includes a first seal between the first shell and the structural component, and a second seal between the second shell and the structural component. In another variant, the first and second motors have power windings positioned opposite the first shell and the electronic board.

[0021] According to one variant, the first motor and the second motor have identical output shaft lengths between the electronic board and the first shell.

[0022] According to one variant, the group further includes a second freewheel between the input body and the output body so that the input body drives the output body at least at the same speed in the normal direction of pedaling.

[0023] According to one variant, the group also includes a first freewheel between the crankset and the input element of the differential system.

[0024] According to one variant, the second free wheel is arranged in such a way that the second input element is able to drive the output body via the second free wheel.

[0025] According to one variant, the group further includes a third free wheel between the output element of the differential system and a rear wheel of the pedal vehicle, the free wheel being capable of coupling or decoupling the rear wheel and the pedal assembly.

[0026] According to one variant, the electronic board is the single electronic control board for the first motor and the second motor and supports the current control chopper bridge of the first motor and the current control chopper bridge of the second motor, execution components of the motor control algorithm, and measurement of the angular positions of the output shaft of the first motor and the output shaft of the second motor.

[0027] According to one variant, the group includes several sensors on the electronic board, the sensors being able to measure the angular positions of the output shaft of the first motor and the output shaft of the second motor.

[0028] According to one variant, the group further includes a bottom bracket axle through the plane comprising the face of the electronic board and a sensor on the electronic board, the sensor being capable of measuring the angular position of the bottom bracket axle.

[0029] According to one variant, at least one of the sensors is of the inductive type. According to another variant, the differential system comprises a planetary gear forming the first input element and a ring gear forming the second input element and one or more transmission elements between on the one hand the pinion shaft of the second motor and on the other hand the ring gear, the transmission element(s) comprising at least one or more intermediate gears.

[0030] According to one variant, the differential system further includes a planet carrier forming the output element, the planet carrier being connected to the output body by a toothed wheel, the planet carrier being in the ring, the planet carrier and the toothed wheel are connected through the ring by a spline.

[0031] According to one variant, the group also includes power supply and information exchange connectors for the powertrain, the connectors being located on the electronic board and accessible through the casing.

[0032] According to one variant, the group is capable of driving a rear wheel of the pedal vehicle by a downstream transmission, the downstream transmission being of a flexible type such as a chain or belt.

[0033] According to one variant, the pedal unit is connected to the second input element.

[0034] According to one variant, the group also includes a direct connection between the electronic board and the power windings of the first motor and the second motor.

[0035] According to one variant, the first and second motors include stators which are juxtaposed in the casing and aligned along a direction of a pedal axis.

[0036] The invention also relates to a pedal vehicle, comprising a propulsion assembly including the powertrain as described above.

[0037] The invention also relates to a method for controlling a powertrain of a pedal-powered vehicle propulsion system as described above, the pedals being driven by a cyclist, and the method comprising

[0038] • a first operating mode in which o the cyclist provides torque to the crankset, o the control unit determines a rotational speed command for the first motor and controls this motor according to this command, the rotational speed control acting on the speed ratio between the output body and the input body and o the control unit determines a torque or current command for the second motor and controls this motor according to this command, this command corresponding to a level of total assistance,

[0039] • a second mode of operation in which o the cyclist applies a torque to the pedals, o the control unit determines only a driving instruction in torque or current, corresponding to a level of assistance, for the first motor and / or the second motor and drives this or these motors according to this instruction, and o the speed ratio between the output body and the input body is mechanically fixed.

[0040] According to one variant, the process further includes a third mode of operation in which the cyclist provides torque to the crankset, and the control unit does not determine a piloting instruction for the first motor or for the second motor.

[0041] According to one variant, in the third operating mode, the torque supplied by the first motor and the second motor is zero.

[0042] According to one variant, in the second operating mode,

[0043] • The control unit determines a torque control setpoint corresponding to an assistance level for the first motor and for the second motor,

[0044] • The torque supplied by the cyclist to the crankset is positive.

[0045] • The torque supplied by the second motor is positive,

[0046] • The torque supplied by the first motor is negative,

[0047] • The speed of the first motor is negative.

[0048] In one variant, the method further includes monitoring the second operating mode by estimating the mass of the vehicle and the cyclist. In another variant, the mass of the vehicle and the cyclist is estimated during the first operating mode.

[0049] According to one variant, the process further includes the control of the second operating mode by distributing the torque supplied by the first motor, by the second motor or by the torques of both motors.

[0050] According to one variant, the process further includes a step of switching from one operating mode to another, the switching from one operating mode to another being achieved by continuously adapting the torque and speed between the operating point of one operating mode and the other.

[0051] According to one variant, the adaptation of the operating point in speed and torque is done sequentially, starting with speed or torque, or is done simultaneously.

[0052] According to one variant, the cyclist's torque on the crankset is estimated, on the one hand, by measuring the deformation of a section of the kinematic chain of the powertrain crossed by the cyclist's effort, by comparing the position at the two ends of this section, and, on the other hand, by the stiffness of this section determined beforehand.

[0053] According to one variant, the process is such that

[0054] • In the first operating mode, the input body is coupled to the second input element by the first freewheel, and the input body is decoupled from the output body by the second freewheel.

[0055] • In the second operating mode, the input body is coupled to the second input element by the first free wheel and the input body is coupled to the output body by the first free wheel and by the second free wheel.

[0056] According to one variant, when the cyclist does not apply torque to the pedals, compensating torques are applied by the first and second motors to constrain the transmission.

[0057] The invention also relates to a method for assembling the powertrain as described above, comprising

[0058] • Supply of the first motor, the second motor, the electronic board, a first hull and a structural part, • Assembly of the electronic board to the structural part,

[0059] • The assembly of the first engine and the second engine in the first hull,

[0060] • The closure of the first compartment by the structural piece by assembling the structural piece with the first shell, the structural piece being assembled with the first shell with the electronic board in the first compartment,

[0061] The first compartment is supplied as a partially closed module.

[0062] According to one variant, the process also includes

[0063] • The supply of transmission gears and a second shell,

[0064] • The assembly of the transmission gears to the module formed by the first compartment,

[0065] • The closure of a second compartment by assembling the second shell to the structural piece, the second compartment enclosing the toothed transmission roads.

[0066] According to one variant, the powertrain includes

[0067] • a target mounted to rotate on a crank axle, the target having a circumferential irregularity

[0068] • at least one inductive sensor on the electronic board, the sensor being capable of detecting the rotations of the target, the method comprising, before the closure of the second compartment,

[0069] • attaching the target to the bottom bracket axle,

[0070] • the assembly of the bottom bracket axle and the target to the module formed by the first compartment, the circumferential irregularity of the target being oriented to ensure the passage of the target relative to the transmission gears assembled to the module formed by the first compartment.

[0071] The use of the verb "comprendre" (to understand), its variants, and its conjugations in this document does not in any way preclude the presence of elements other than those mentioned. The use of the indefinite article "un" (a / an) or the definite article "le" (the / it) to introduce an element does not preclude the presence of multiple such elements.

[0072] The terms "first >>", "second >>", "third >>, etc. are used in this document exclusively to differentiate different elements, without implying any order between these elements.

[0073] All preferred embodiments and all advantages of the powertrain according to the invention are applicable mutatis mutandis to the present vehicle, control method, and assembly method, and vice versa. The various embodiments may be considered individually or in combination.

[0074] Brief description of the figures

[0075] Other features and advantages of the present invention will become apparent upon reading the detailed description that follows, for understanding of which reference should be made to the accompanying figures which show:

[0076] - Figure 1, an example of a functional view of a propulsion assembly in which the powertrain is implemented;

[0077] - Figure 2, a detailed functional view of Figure 1;

[0078] - Figure 3, a schematic view of a powertrain group from Figure 2;

[0079] The drawings in the figures are not to scale. Similar features are generally denoted by similar reference numerals in the figures. Within the scope of this document, identical or analogous features may bear the same reference numerals. Furthermore, the presence of reference numerals or letters in the drawings shall not be considered limiting, even when such numerals or letters are specified in the claims.

[0080] Detailed description of embodiments of the invention

[0081] The invention relates to a powertrain for a pedal vehicle propulsion system. The powertrain comprises a differential system, a first electric motor, and a second electric motor, and an electronic circuit board supporting at least one control unit capable of controlling the first and second motors. The first and second motors each have an output shaft driven by a rotor, each output shaft driving a pinion shaft. The powertrain is such that the output shaft of the first motor and the output shaft of the second motor extend through a plane comprising one face of the electronic circuit board, with the pinion shaft driven by the first motor and the pinion shaft driven by the second motor being on the same side of the plane. This simplifies the assembly of the powertrain.

[0082] Figure 1 is an example of a functional view of a propulsion system 2 in which a drive unit 1 can be implemented. The propulsion system 2 is contained within a pedal-powered vehicle. The propulsion system 2 is schematically positioned between a cyclist 5 (C) and a rear wheel 16 (with an angular velocity ωW). The pedal-powered vehicle can be, for example, a bicycle, a tricycle, or other similar vehicles. In particular, it can be a bicycle, tricycle, or other similar vehicle with electric assist. The propulsion system 2 includes a crankset 21 (including pedals) operated by the cyclist 5. The crankset allows the cyclist to propel the vehicle with or without the assistance of electric motors described later. The propulsion system 2 includes the drive unit 1 (DU), which can be located at the crankset 21 (a "mid-drive" type propulsion system 2).

[0083] The drive unit 1 may include an input body 11 and an output body 13. The pedal assembly 21 may be confused with the input body 11 of the drive unit 1. Alternatively, the output body 13 may be confused with the wheel rim 16.

[0084] The drive assembly 2 may include an upstream transmission 18 (Tin) between the crankset 21 and the input body 11 of the drive unit 1. The upstream transmission 18 connects the crankset 21 and the input body 11. The upstream transmission 18 may be of a flexible type, for example, a chain, a belt, or any type of transmission element. The upstream transmission 18 may change the angular velocity of the crankset (or crank axle) to an angular velocity. The upstream transmission 18 may be optional. The drive assembly 2 may include a downstream transmission 20 (All) between the output body 13 of the drive unit 1 and one or more rear wheels 16 of the vehicle. The downstream transmission 20 connects the output body 13 and one or more rear wheels 16. The downstream transmission 20 can modify the angular velocity wO of the output body 13 into an angular velocity wTO. The downstream transmission 20 may be optional.The downstream transmission is for example of a flexible type such as a chain or a belt.

[0085] Thus, in a mid-drive type drivetrain 2 of a vehicle with the drivetrain 1 located at the bottom bracket 21, the bottom bracket 21 can be considered the input body 11 (and therefore the upstream transmission 18 is absent), and the downstream transmission 20 can be a chain or belt connecting the output body 13 of the drivetrain 1 to the rear wheel. Alternatively, the upstream transmission 18 can be a chain or belt (or any other type of transmission element) connecting the bottom bracket 21 to the input body 11 of the drivetrain 1, and the downstream transmission 20 can be a chain or belt (or any other type of transmission element) connecting the output body 13 of the drivetrain 1 to the rear wheel 16. This alternative drivetrain configuration could be used in certain specific bicycles, namely cargo bikes.

[0086] Figure 2 shows a detailed functional view of Figure 1. The drive unit 1 comprises a first motor 40 (M1) and a second motor 50 (M2). The drive unit 1 may further include a differential system 10 (D). The use of a differential system 10 allows for a continuous change in the transmission ratio (or speed ratio) between the rotation of the output body 13 and the rotation supplied by the rider to the input body 11. The differential system 10 may include a first input element 101 (with an angular velocity ω1), a second input element 102 (with an angular velocity ω2), and an output element 103 (with an angular velocity ω3).

[0087] The input body 11 can be connected to the second input element 102 of the differential system 10. The input body 11 transmits the power supplied by the cyclist to the input of the differential system 10. The input body 11 can drive the second input element 102, preferably with a fixed ratio. The drive unit may include a first freewheel 26 (F1) between the crankset 21 and the second input element 102 of the differential system 10. The input body 11 can be indirectly connected to the second input element 102 via the first freewheel 26.The function of the freewheel 26 is to allow the pedal assembly 21 to drive the second input element 102 in the normal operating direction of the differential system, but to prevent the second motor 50 from driving the pedal assembly 21 in the normal operating direction (in the context of this document, the normal pedaling direction being the direction of rotation of the pedal assembly axle that corresponds to forward movement of the pedal vehicle). The input body 11 can be indirectly connected to the second input element 102 via a reduction gear 28 (RI1), modifying the angular velocity wF1. Alternatively, the input body 11 can be directly connected to the second input element 102 – a connection establishing the link between the input body 11 and the second input element 102.

[0088] The drive unit may include a second freewheel 30 between the input body 11 and the output body 13, such that the input body 11 drives the output body 13 in the normal direction of operation. The input body 11 may be indirectly connected to the output body 13 via the second freewheel 30 (F2). The input body 11 can then transmit the power supplied by the cyclist to the output of the drive unit 1. The input body 11 may be indirectly connected to the output body 13 via a reduction gear 32 (RI2) and potentially the reduction gear 28 (RI1), modifying (i.e., multiplying or reducing) the angular velocity wF2. The input body 11 may be indirectly connected to the output body 13 via a reduction gear 34 (R0), along various paths.

[0089] More specifically, the first freewheel 26 can be downstream of the input body 11 and can be connected to the second input element 102 directly or indirectly via the gearbox 28. The second freewheel 30 can be downstream of the first freewheel 26, or downstream of the gearbox 28 if necessary, along different paths. The first freewheel 26 and the second freewheel 30 are arranged such that the second input element 102 is able to drive the output body 13 via the first freewheel 26 and the second freewheel 30. In other words, the second freewheel 30 is in series with the first freewheel 26, between the input body 11 and the output body 13.The crankset 21 (and the input body 11) can drive the second input element 102 via the first freewheel 26 in the normal direction of operation and the crankset 21 (and the input body 11) can possibly drive the output body 13 via the first freewheel 26 and the second freewheel 30 in the normal direction of operation.

[0090] Figure 2 schematically represents the different configurations and paths using the paths a and ?, such that a = j.

[0091] If path a is active (the second freewheel 30 is directly connected downstream of the first freewheel 26), then:

[0092] (x denoting any variable).

[0093] If path [3] is active (the second freewheel 30 is indirectly connected downstream of the first freewheel 26 via the reducer 28), then:

[0094] The same applies to paths y and <5, such that y = <5. When path y is active, the input body 11 is indirectly connected to the output body 13 via the reducer 34. When path ô is active, the input body 11 is directly connected to the output body 13 (without the reducer 34).

[0095] The first motor 40 can be connected to the first input element 101 of the differential system 10. The first motor 40 can drive the first input element 101, preferably with a fixed ratio. The first motor 40 then allows the speed ratio of the drive unit 1 to be controlled. The first motor 40 can be connected indirectly to the first input element 101 via a reduction gear 24 (RM1). The reduction gear 24 modifies the angular velocity wM1 of the first motor 40 into an angular velocity col. Alternatively, the first motor 40 can be connected directly to the first input element 101, without the reduction gear 24, the angular velocity wM1 of the first motor 40 corresponding to the angular velocity œ1.

[0096] The second motor 50 can be connected to the second input element 102 of the differential system 10. The second motor 50 can drive the second input element 102, preferably with a fixed ratio. The second motor 50 allows for the correct level of assistance regulation from the input of the differential system 10. The second motor 50 can be indirectly connected to the second input element 102 via an intermediate reduction gear 36 (RM2). The reduction gear 36 modifies (i.e., multiplies or reduces) the angular velocity wM2 of the second motor 50 into an angular velocity w2.

[0097] Furthermore, the second motor 50 is capable of driving the output body 13 in a direction corresponding to the normal pedaling direction. According to Figure 2, the second motor 50 can drive the output body 13 via the second freewheel 30 (and optionally via the reduction gear(s) 32, 34, 36). Thus, the second motor 50 is always capable of driving the output body 13 in a direction corresponding to the normal pedaling direction.

[0098] The drive assembly 2 may further include a third freewheel 14 (F3). The third freewheel 14 is located between the pedal assembly 21 and a rear wheel 16 of the pedal vehicle, the freewheel being capable of coupling (synchronizing) or decoupling (desynchronizing) the rear wheel and the pedal assembly. The freewheel allows pedaling (and the rotation of the pedal axle 21) to be interrupted while allowing the vehicle to continue moving in the direction of travel. The freewheel is, for example, located between the output element 103 of the differential system and the rear wheel 16. The freewheel 14 is located, for example, downstream of the output body 13. The freewheel 14 is located, for example, downstream of the downstream transmission 20, if applicable. The third freewheel 14 is located, for example, in the hub of the rear wheel.

[0099] The differential system 10 can be, for example, an epicyclic gear train (as described later in connection with Figure 3). The epicyclic gear train comprises a sun gear, a ring gear, and a planet carrier, and one or more planets (single or double), carried by the planet carrier, between the sun gear and the ring gear. The first input element 101 can be the sun gear. The second input element 102 can be the ring gear, and the output element 103 can be the planet carrier. Alternatively, the second input element 102 can be the planet carrier, and the output element 103 can be the ring gear.

[0100] The equations for the powertrain components are as follows. Throughout, "R" denotes the ratio of the component designated afterward (according to the convention above). For example, "RDU" means the ratio of powertrain 1 (DU), or "RRM1" means the ratio of reduction gear 24 (RM1).

[0101] The powertrain transmission ratio is:

[0102] 0)0 RDU = — 0)1

[0103] One characteristic of powertrain 1 is its ratio range r-., , . RDUmax

[0104] Plag

[0105] 3 e de rap rp rort = - RDUmin

[0106] The consecutive equation of the differential system 10 is: o)l — o)3 RD = — - -

[0107] 0)2 — 0)3

[0108] The following equations are written in relation to Figure 2. The consecutive equations for the internal transmissions (reducers 24, 36, 34, 28, 32) to the powertrain are: The upstream ions 18 and downstream ions 20 are respectively: 0)1

[0109] RTin = o)CK o)TO

[0110] RTout =

[0111] 0)0

[0112] The consecutive equations for freewheels 26, 30, 14 are:

[0113] 0)W > )T0 RF3 = — > 1

[0114] In this context, but also independently of this context, Figure 3 shows a schematic view of the powertrain group 1 according to a preferred embodiment.

[0115] Figure 3 shows a schematic view of the powertrain 1 of Figure 2. In the configuration of Figure 3, paths a and ô are shown. The reduction gears 24 (RM1), 32 (RI2), and the upstream transmission 18 (Tin) are not present. The reduction gear 34 is formed by gears 33 and 38. The reduction gear 36 is formed by a shaft pinion 54, a tooth 37 of the ring gear 102, and an intermediate gear 35. The reduction gear 28 is formed by a gear 29 and a gear 27 of the ring gear 102. The powertrain 1 comprises the first motor 40 and the second motor 50. In this example, the differential system 10 is an epicyclic gear train comprising transmission components.The epicyclic gear train includes a planet which is a shaft pinion corresponding to the first input element 101, a ring corresponding to the second input element 102, a planet carrier corresponding to the output element 103 and one or more planets 52 (single or double), carried by the planet carrier 103. The planets 52 are between the planet 101 and the ring 102 (and are meshed with it). The satellites 52 are guided in rotation relative to the planet carrier 103 by a bearing 69. The planet carrier 103 is connected by a spline 78 to the output plate corresponding to the output body 13. The output plate 13 is driven in rotation by the planet carrier 103 via the reduction gear 34 (formed by the gears 33 and 38) and the spline 78. The output plate 13 is guided in rotation relative to a housing 56 (described hereafter) by a bearing 70.The crankset 21 (axle 211 of the crankset) is guided in rotation relative to the output chainring 13 and relative to the casing 56 by bearings 66.

[0116] The first motor 40 comprises an output shaft 402 driven by a rotor 404. The output shaft 402 drives a pinion shaft, which is the planetary gear and the first input element 101. The pinion shaft 101 (or pinion shaft) is a component of a transmission system where a pinion (for example, a small gear) is directly integrated into or fixed to a shaft, forming a single unit. The pinion and output shaft of the motor are a single unit. The pinion shaft 101 can be, for example, machined directly onto the output shaft 402 or, for example, pressed onto the output shaft 402. The pinion shaft 101 and the output shaft 402 can be a single unit. The shaft-mounted pinion allows for a more compact construction, greater robustness and more efficient transmission of motion, particularly in the present powertrain where space is limited and the power transmitted is significant.The first motor 40 also includes a stator 406, driving the rotor 404.

[0117] The output shaft 402 of the first motor drives the shaft pinion, which is the first input element. In other words, the shaft pinion is directly the first input element, or rather, the shaft pinion is itself the first input element. This eliminates the need for an additional gear ratio (a stage, such as in the reduction gear 24) between the first motor and the first input element. This increases the compactness of the geared motor assembly and reduces its manufacturing cost. It also has the advantage of reducing the mass and inertia of the drive train (between the first motor and the first input element), resulting in improved responsiveness to changes in the powertrain's speed ratio. Furthermore, driving the shaft pinion as the first input element via the motor's output shaft allows for a small-diameter input element (since the output shaft of such a motor is small).The powertrain of the invention allows for a high multiplication factor (in absolute value) provided by the differential's RD ratio to combine the movements of powertrain components at very different speeds. Specifically, the speed of the pedals (between 40 and 100 revolutions per minute, for example) drives the input shaft connected to the second input element, while the speed of the first motor (which is at more than 5,000 revolutions per minute, for example) drives the shaft pinion forming the first input element. Implementing the first motor's shaft as a shaft pinion acting as the first input element of the differential also results in less stress on the motor shaft: the planetary gears of the epicyclic gear train apply parasitic forces (radial meshing force) that balance each other.This is not the case when the motor shaft drives a simple gear. Consequently, the shaft-driven pinion is under less stress in this solution, potentially increasing its durability, while also reducing noise and / or enabling a more efficient and high-performing design (particularly since the shaft rotates rapidly). Furthermore, this assembly improves the control of the continuously variable transmission (CVT) ratio: as the rotor of the first motor is fixed to the first input element, there is no backlash between the two. The position sensor of the first motor allows for efficient control not only of the motor but also, and directly, of the first input element. Excessive backlash and / or flexibility in the kinematic chain between these two elements makes control imprecise or even unstable. The proposed configuration is optimal from these considerations.Furthermore, the shaft-mounted pinion, which is the first input element (driven by the first motor) and also the planetary gear, allows for a small diameter planetary gear and thus a high RD ratio (without needing a very large diameter ring gear, which would be detrimental to compactness). This is not the case in document CN207241949, where the planetary gear is concentric with the bottom bracket axle, and therefore has a larger diameter. The bottom bracket axle of CN207241949 has a square taper fitting (according to the ISO6695 standard governing dimensions), which makes the diameter of the planetary gear accordingly larger.

[0118] The second motor 50 also includes an output shaft 502 driven by a rotor 504. The output shaft 502 drives a pinion shaft 54. The pinion shaft 54 ​​(or pinion shaft) can be, for example, machined directly onto the output shaft 502 or, for example, pressed onto the output shaft 502. The pinion shaft 54 ​​and the output shaft 502 can be a single unit. The same elements described for the pinion shaft 101 apply here. The second motor 50 further comprises a stator 506, driving the rotor 504. The second motor 50 is connected to the differential system 10 by the shaft pinion 54. The shaft pinion 54 is connected to the teeth 37 of the ring gear 102 by one or more transmission elements such as the intermediate gear 35. The shaft pinion 54, the teeth 37 of the ring gear 102 and the intermediate gear 35 form the reduction gear 36.The intermediate gear 35 transmits motion between the shaft pinion 54 and the gear teeth 37 without changing the reduction ratio. The gear 35 provides the connection between the shaft pinion 54 and the gear teeth 37, even though the distance between the shaft pinion 54 and the gear teeth 37 is determined by the diameters of the first and second motors. If a direct transmission were required between the shaft pinion 54 and the gear teeth 37 with a predetermined reduction ratio, this would result in large and bulky diameters for both the shaft pinion 54 and the gear teeth 37. The gear 35 avoids this problem.

[0119] The powertrain 1 further includes an electronic board 19 supporting a control unit 22 (not visible in Figure 3). The electronic board 19 supports all or part of the electronic components forming the control unit 22. The control unit 22 is capable of controlling the first engine 40 and the second engine 50. The control unit 22 is connected to the first engine 40 and the second engine 50 and is configured to control both the first and second engines. The electronic board 19 has one face lying within a plane 80. The electronic board is a printed circuit board (PCB), which is a flat substrate on which various electronic components are mounted and connected—particularly for engine control. The flat substrate comprises a first face and a second face, one of which lies within the plane 80. The electronic board has a shape that adapts to the configuration of the powertrain.The output shaft 402 of the first motor 40 and the output shaft 502 of the second motor 50 extend through the plane 80, which comprises the face of the electronic board 19 (not just the abstract axis of rotation of the shafts, but the physical shafts themselves are through the electronic board 19). The output shafts 402 and 502 may pass through an opening in the board, the opening being circumscribed by the board itself. The opening may also be a notch in the board, the opening not being circumscribed by the board itself (the opening being through the plane 80). The shaft pinion 101 driven by the first motor 40 and the shaft pinion 54 driven by the second motor 50 are on the same side of the plane 80.In other words, the first motor 40 (comprising its rotor 404 and stator 406) and the second motor 50 (comprising its rotor 504 and stator 506) are on the same side of the plane (and opposite one face of the electronic board 19), while the shaft-driven gears 101 and 54 are on the other side of the plane (and opposite the other face of the electronic board 19, which could be the one in plane 80). The first and second motors 40 and 50 are (essentially) aligned on the side of their mechanical output (shaft-driven gears), so as to interface with the electronic board 19 (which is perpendicular to the axes of rotation of the shafts). This makes it easier to assemble the powertrain assembly 1. Also, this makes it easier to position the electronic board and connect the electronic board to the parts powered and / or controlled by the electronic board (such as connecting the motors to the board).The intermediate position of the board in the powertrain also facilitates the arrangement of the electronic components of board 19. In addition, this allows the first and second motors 40, 50 to be arranged with parallel axes of rotation of the output shafts, arranged so that the center distance is reduced to a maximum in order to make the powertrain 1 more compact.

[0120] In Figure 3, the powertrain also includes the pedal assembly 21, which corresponds to the input body 11. The pedal assembly 21 (forming the input body 11) is connected to the ring gear 102 (forming the second input element). The second motor 50 can be connected to the second input element in parallel with the pedal assembly.

[0121] The drive unit 1 includes a casing 56. The casing 56 supports the guide bearings for the transmission components. The casing 56 protects the drive unit 1 from the environment. The casing 56 protects the unit's components (such as electronic components and transmission elements) from weather and dirt. It also protects the rider. The casing 56 encompasses all the components (such as electronic components and transmission elements) of the drive unit 1, except for the crankset 21 and the chainring 13. The crankset 21 passes completely through the casing 56 (which supports the crankset bearings 66), and the chainring 13 is located outside the casing 56. The casing 56 may have several compartments.The first motor 40, the second motor 50, and the electronic control unit 19 can be housed in the same first compartment 561, while the shaft-mounted gears 101 and 54 are located in the same second compartment 562. This allows the motors to be isolated from the rest of the transmission components. It also allows the clean (grease-free) portion of the powertrain, containing the motors and the electronic control unit 19, to be separated. Furthermore, it allows the motors and the electronic control unit 19 to be assembled in one compartment, and the other components to be assembled in the other compartment—for example, at different times and locations during the powertrain assembly process. This simplifies the construction of the powertrain. The powertrain thus combines electric assistance and an automatic transmission within a single housing.

[0122] According to Figure 3, the powertrain 1 further includes a structural part 58 delimiting the first compartment 561 and the second compartment 562 of the casing 56. The structural part 58 facilitates the joining of the compartments together. Structural part 58 also facilitates the positioning of the various parts within the powertrain assembly 1. For example, the output shafts 402, 502 of the first and second motors 40, 50 are guided in rotation relative to structural part 58 by bearings 60, 62 respectively. The bearings 60, 62 are supported by structural part 58 between, on the one hand, the rotors and stators of the motors and, on the other hand, the shaft-mounted pinions 101, 54. Also, the gear 35 and the planet carrier 103 are also guided in rotation relative to structural part 58 by a bearing 64 and a bearing 65 respectively.The gear wheel 35 can be held only by the structural part 58 or by the structural part 58 and the housing 56 (as seen in figure 3).

[0123] Structural part 58 also allows the assembly of the housing 56, which comprises a first shell 71 and a second shell 72. The first shell 71 defines the first compartment 561 with structural part 58. The second shell 72 defines the second compartment 562 with structural part 58. The first shell 71 and the second shell 72 are located on either side of structural part 58. In Figure 3, fasteners 74 allow the first shell 71 and the second shell 72 to be attached to structural part 58. A first seal between the first shell 71 and structural part 58 and a second seal between the second shell 72 and structural part 58 can be provided. The seals can be held in position at the interface between the first and second hulls 71, 72 and the structural part 58 to ensure the sealing of compartments 561, 562. The fasteners 74 can hold the seals in place.The seals can be a joint following the perimeter of the hulls 71, 72.

[0124] Structural part 58 extends across the space defined by the housing 56, delimiting the two compartments and facilitating the construction of the powertrain assembly 1. Structural part 58 is essentially flat. This part can be described as a spacer, such that the interface between the spacer and each of the shells 71, 72 forms a closed perimeter. Structural part 58 is a rigid part that connects the two shells 71, 72 and holds them together. Furthermore, the electronic board 19 can be positioned parallel to and against structural part 58. Since both are flat parts, the electronic board 19 can be supported against structural part 58 in the first compartment 561. The structural part can be positioned opposite the face of the electronic board 19 that lies within plane 80.The advantage of such a structural part 58 is that the electronic board 19 can thus be easily positioned in the housing 56 while providing a large surface area to accommodate numerous electronic components. The structural part 58 allows for the handling of a mechanical component rather than the electronic board 19 during assembly, avoiding the risk of improper handling that could damage the electronics.

[0125] Structural part 58 allows for stable and transportable partial assemblies of the powertrain 1. These partial assemblies can be the electronic board 19 on structural part 58, the engines 40, 50 in the first compartment 561 delimited by the first hull 71 or these two assemblies forming a partially closed module.

[0126] The positioning of the electronic board 19 between the motors 40, 50 and the shaft-mounted gears 101, 54 allows the electronic board 19 to be located in a more central area of ​​the housing 56 and thus further away from the shells 71, 72. In particular, the first motor 40 and the second motor 50 have power windings positioned opposite the first shell 71 and away from the electronic board 19. Since the electronic board 19 is in an equatorial area of ​​the housing 56 (and not against the housing), the motor windings can be located at the bottom of the housing. This allows for improved thermal management and cooling of the motors. The electronic board 19 is cooled by the heat flow in the structural component 58. The powertrain also includes a direct connection between the electronic board 19 and the power windings of the first motor 40 and the second motor 50.Due to the position of the electronic board 19 relative to the motors, the motors 40 and 50 are positioned close to the electronic board 19. The motors 40 and 50 are aligned with the electronic board 19. The electrical connection between the motors and the board is not obstructed by any components of the powertrain. The power supply connection between the motors 40 and 50 and the electronic board 19 is facilitated.

[0127] The first motor 40 and the second motor can have identical output shaft lengths 402 and 502 between the electronic board 19 and the first housing 71. This maximizes the power and torque capacity of the motors 40 and 50 while maintaining the lateral space between the pedals under constraint (cofactor). This also facilitates the manufacturing of the housing 56 and the assembly of the drive unit 1. The motors 40 and 50 can have shafts 402 and 502 passing through their respective rotors and stators. The shafts 402 and 502 can extend from the bottom of the first housing 71, through the plane 80 comprising the face of the electronic board 19, and to the second compartment 562. The output shafts 402 and 502 can be guided in rotation relative to the first housing 71 by bearings 61 and 63, respectively.

[0128] Preferably, the electronic board 19 is the sole control board for the first motor 40 and the second motor 50. The electronic board 19 supports the current control chopper bridge for the first motor 40 and the current control chopper bridge for the second motor 50. The electronic board 19 also supports components for executing the motor control algorithm, such as a microcontroller or equivalent systems such as a programmable chip, FPGA (Field-Programmable Gate Array). The electronic board 19 can also support the measurement of the positions of the output shaft 402 of the first motor 40 and the output shaft 502 of the second motor 50.The electronic board 19 can also support the electronic components responsible for executing a high-level control algorithm for the powertrain 1 (specifically for calculating the torque of the second motor 50 to ensure the level of assistance of the second motor 50 and the speed). The presence of a single electronic control board 19 reduces manufacturing costs because it limits the use of expensive connectors.

[0129] The control unit 22 controls the first motor 40 and the second motor 50 based on the angular positions of the first motor 40, the angular positions of the second motor 50, the angular velocity of the first motor 40, the angular velocity of the second motor 50, the current of the first motor 40, and / or the current of the second motor 50, this information being provided to it by the measuring elements. To this end, the drive unit 1 may include several sensors 76 on the electronic board 19, the sensors 76 being capable of measuring the angular positions of the output shaft 402 of the first motor 40 and the output shaft 502 of the second motor 50. An additional sensor 76 may be provided to measure the angular position of the pedal assembly 21. More specifically, the powertrain group 1 includes the crank axle 211 through the plane 80 comprising the face of the electronic board 16 and the sensor 76 measures the angular position of the crank axle 211.Thus, as an example, three 76 sensors are present.

[0130] As an example, sensors 76 detect the rotational movements of a target 77 mounted for rotation on shafts 402, 502, and the bottom bracket axle 211. The targets 77 have alternating (phase-dependent) electrically conductive and non-conductive parts. Generally, these alternations occur regularly around the entire circumference. In some embodiments, the targets have protrusions, for example, flower petal-shaped, meaning that the non-conductive parts are not materialized. The targets 77 have an electrically conductive material for the conductive and materialized parts. The targets 77 rotate relative to coils of sensors 76, printed on the electronic board 19. The transmitting coil of sensors 76 is electrically powered, generating a magnetic field in which the target 77 rotates.The rotation of the target 77 then in turn generates an induced current in the receiver winding(s) (a minimum winding) of the sensor 76. This makes it possible to detect the rotations of the shafts 402, 502 and axis 21 1, and therefore to know the angular position of the motors 40, 50 and pedal 21.

[0131] The positioning of the satellite carrier 103 in the housing 56, and in particular in the second compartment 562, is carried out in a compact manner, so as to reduce the footprint. The planet carrier 103 is housed within the ring gear 102. The planet carrier 103 is guided in rotation relative to the structural part 58 by the bearing 65 and relative to the ring gear 102 by the bearing 59. The planet carrier 103 allows the planet gears 52 to be positioned opposite an internal tooth 31 of the ring gear 102. The planet carrier 103 is also rotationally connected to the gear 38 through the ring gear 102. The ring gear 102 can be solid, and the planet carrier 103 and the gear 38 can be connected through the ring gear 102. To facilitate assembly, the planet carrier 103 and the gear 38 are connected through the ring gear 102 by the spline 78.The toothed wheel 38 is guided in rotation relative to the shell 72 by a bearing 67 and relative to the ring 102 by a bearing 68.

[0132] Figure 3 shows the freewheels 26 and 30. The first freewheel 26 is implemented between the crankset 21 (the bottom bracket axle 211) and the sprocket 29. The sprocket 29 is meshed with the sprocket 27 of the ring gear 102, which is the second input element of the differential system 10. The second freewheel 30 is arranged such that the ring gear 102, forming the second input element, is able to drive the chainring 13, forming the output body, via the second freewheel 30.

[0133] The powertrain 1 also includes power and data exchange connectors 90 for the powertrain 1. The connectors 90 are located on the electronic board 19 and are accessible through the housing 56. The (external) connector(s) 90 are directly integrated into the electronic board 19. A seal (visible in Figure 3) is provided between the connectors 90 and the housing 56. This facilitates the construction of the powertrain and ensures the housing is sealed.

[0134] The powertrain 1 incorporates an arrangement of its component parts that optimizes space, making the unit less bulky and easier to assemble. The motors 40 and 50 are of identical (or nearly identical) length along the direction of the crankshaft 211. More specifically, the stators 406 and 506 are of identical (or nearly identical) length along this direction. In other words, the length occupied by the stators between the housing 56's shell 71 and the electronic board 19 is identical (or nearly identical) along this direction. The motors 40 and 50, particularly the stators 406 and 506, are positioned side-by-side within the housing 56 (the shell 71) and aligned along the direction of the crankshaft 211. Furthermore, the center distance between the output shafts 402 and 502 is minimized. Furthermore, structural part 58 is according to an average plan 82.The transmission elements, such as the gears forming the differential system, the gears between the input body and the second input element, and the gears between the output element of the differential system and the output body, extend along respective mean planes 83, 84, 85, etc. In a direction along the axis 211 of the pedal assembly, the drive unit 1 successively comprises the first and second motors 40, 50 juxtaposed, the plane 80 comprising the face of the electronic board 19, the mean plane 82, and then the respective mean planes of the transmission elements 83, 84, 85, etc. The planes are parallel to each other and perpendicular to the axis 211 of the pedal assembly.

[0135] When using the vehicle, the cyclist can propel it forward by pedaling in the normal direction. The cyclist can provide torque. The cyclist can be assisted by the first and second motors, which can add or subtract torque from that provided by the cyclist. The cyclist can stop pedaling while the vehicle continues to move, freewheeling.

[0136] The invention also relates to a method for controlling the powertrain of a pedal-powered vehicle propulsion system. The method may include a first operating mode (corresponding to a first operating mode in which the powertrain is configured). In the first operating mode, the cyclist provides torque to the crankset 21, and the control unit 22 determines a speed command for the first motor 40 and drives this motor accordingly. This allows the speed ratio between the output body 13 and the input body 11 to be adjusted. The control unit 22 determines a torque or current command (corresponding to a level of total assistance) for the second motor 50 and drives this motor accordingly.In the first operating mode, due to the kinematics of the differential system 10, the first motor 40 is speed-controlled to act on the speed ratio between the output body 13 and the input body 11, and the second motor 50 is torque-controlled to act on the level of assistance. In other words, in the first operating mode, the control unit 22 determines a speed command for the first motor 40 to act on the speed ratio between the output body 13 and the input body 11, and the control unit 22 determines a torque command for the second motor 50 corresponding to a level of full assistance. Thus, the powertrain combines electric assistance and an automatic transmission. The powertrain provides a continuously variable transmission ratio (CVT).

[0137] According to the first operating mode of the process, the first motor 40 manages the speed ratio of the drive unit 1. One of its functions is to provide a given transmission ratio. This transmission ratio is the ratio between the angular velocity of the output body 13 of the drive unit 1 and the angular velocity of the input body 11 of the drive unit 1. This transmission ratio can, for example, be determined based on a speed ratio parameter provided by the cyclist or be automatically determined by the control unit 22 in order to provide the cyclist with continuous or discrete gear changes. This determination can, in particular, be performed by a gear-shifting algorithm.The first motor 40 can be controlled in angular position or angular velocity, for example via the control unit 22 which controls the first motor in such a way that a setpoint for angular position or angular velocity is respected.

[0138] According to the first operating mode of the process, the second motor 50 is responsible for managing the correct level of assistance regulation for the powertrain. One of its functions is to assist the cyclist's movement by adding torque to that supplied by the cyclist and the first motor. In other words, the power supplied by the second motor is added to the power supplied by the cyclist. Preferably, the level of assistance is determined by the control unit 22, based in particular on an assistance level parameter. The assistance level parameter can be determined by the cyclist or automatically by the powertrain's control unit 22. The second motor can be controlled by current or torque, for example, via the control unit 22, which controls the second motor so that a current or torque setpoint is maintained.In addition, the control unit 22 can control the second motor according to a torque setpoint with regulation.

[0139] The control unit 22 can be configured to determine a rotational speed setpoint and to impose said rotational speed setpoint on the first motor 40, the rotational speed setpoint being determined as a function of the speed of the second motor 50 and / or the pedal speed. The control unit 22 can further use the gear ratio parameter and the powertrain assistance level parameter to control the second motor 50. The control unit 22 can be configured to determine a current or torque setpoint and to impose said current or torque setpoint on the second motor 50.The current or torque setpoint of the second motor is determined by taking into account one or more criteria including the torque or current of the first motor obtained by the current measuring element of the first motor, the speed of the first motor, the speed of the second motor, the speed ratio parameter of the powertrain and the powertrain assistance level parameter.

[0140] More specifically, in the first mode of operation, the first motor 40 transmits its motion to the first input element 101 of the differential system 10 (the pinion shaft 101 in Figure 3), possibly through the reducer 24 (not shown in Figure 3). The action of the first motor 40 is transmitted to the shaft pinion forming the first input element 101 of the differential system 10. The cyclist 5 provides a torque on the crankset 21, the movement then being transmitted to the input body 11, possibly via the upstream transmission 18. The input body 11 can also be confused with the crankset 21, as is the case in Figure 3. In the case of pedaling in the normal direction, the movement is transmitted from the input body 11 to the ring forming the second input element 102 of the differential system 10, possibly via the reducer 28 (comprising the toothed wheel 29 and the toothed wheel 27).The cyclist's movement is assisted by the second motor 50, which can act, in conjunction with the cyclist, on the ring forming the second input element 102 of the differential system 10. The movements performed on the input elements 101 and 102 of the differential system 10 are combined into a single movement transmitted to the planet carrier forming the output element 103 of the differential system 10. This movement is then transmitted to the plate forming the output body 13, possibly via the reduction gear 34 (comprising the gears 33 and 38). The output body 13 transmits its movement to the wheel 16, possibly through a downstream transmission 20, and possibly through the third freewheel 14. The output body 13 may be considered the same as the wheel 16.

[0141] In the first operating mode, the input body 11 is coupled to the second input element 102 (the ring in Figure 3) by the first freewheel 26 (conducting), and the input body 11 is decoupled from the output body 13 by the second freewheel 30 (non-conducting). The second freewheel 30 is non-conducting, so no torque is transmitted from the input body 11 to the output body 13 without passing through the differential system 10.

[0142] By combining the consecutive equations of the internal transmissions (of the reducers 24, 36, 34, 28, 32) with the consecutive equation of the differential system 10:

[0143] Assuming that RD < 0, then

[0144] Thus, from the perspective of the design of drive unit 1 (DU), for a given input speed 0, in order to increase the RDU ratio of drive unit 1 (for example, at low speeds, for a mountain bike, there is a small gear ratio) while limiting the speed a>Ml of the first motor 40 (for example, due to physical or control limitations), one possibility is to increase the RRO ratio of the output stage and decrease the RRI1 ratio of the input stage. This possibility is used to obtain a wide range of maximum drive unit ratios, with a reasonable maximum rotational speed of the first motor 40. Beyond a limit defined by the design choices, at low gear ratios, the speed of the first motor 40 is in the opposite direction to the speed at high gear ratios.This sub-mode of operation (a) of the first mode of operation implies that the first motor 40 behaves as a generator. Since the speed of the first motor 40 is directly determined by the desired gear ratio, this ratio conditions the power, which is negative in this case. Indeed, the first motor 40 absorbs mechanical power and then converts it electrically (with positive torque and negative speed). Consequently, for a given level of assistance, the second motor 50 provides both the assistance power and the power regenerated by the first motor 40. The second motor 50 may need to be oversized to deliver this power.Furthermore, if the power outputs of the first motor (40) and the second motor (50) partially compensate for each other, the losses, proportional to the power of each motor, are cumulative (an unnecessary loss consists of the loss on the energy regenerated by the first motor (40) plus an additional loss due to the overcompensation of the second motor (50). The more negative the power regenerated by the first motor (40), the higher the losses, which can lead to reduced range and significant overheating.

[0145] In the first operating mode, the ratio (e.g., the respective rotational speeds relative to the non-rotating body) between the output body and / or the wheel, and the input body is continuously adjusted. For example, the control unit 22 can be configured to control the speed ratio accordingly. The objective may be to maintain the reference pedaling speed. Alternatively, the control unit 22 can be configured to determine and / or control the torque of the second motor in order to maintain a predefined level of assistance (ratio between input power and output power).

[0146] To avoid reduced range and significant overheating, the system may include a second operating mode (corresponding to a second operating mode in which the powertrain is configured). In this second operating mode, the cyclist applies torque to the crankset 21, and the control unit 22 determines only a torque (or current) command, corresponding to an assistance level, for the first motor 40 and / or the second motor 50, and drives this motor or these motors accordingly. The speed ratio between the output body 13 and the input body 11 is mechanically fixed. The speed ratio is mechanically fixed in the sense that it is not defined and is variable through the differential system, possibly due to the presence of one or more freewheels.

[0147] More specifically, in the second mode of operation, the movement can be transmitted from the input body 11 (the pedal assembly 21 in Figure 3) to the output body 13 (the output platform in Figure 3) through the first free wheel 26, and possibly the second free wheel 30, and possibly through the reducers 28, 32, 34. The speed ratio between the output body 13 and the input body 11 is therefore mechanically fixed. In this second mode of operation, the input body 11 is coupled to the second input element 102 (the ring in Figure 3) by the first free wheel 26 and the input body 11 is coupled to the output body 13 by the first free wheel 26 and by the second free wheel 30. The first free wheel 26 and the second free wheel 30 are through (i.e. the free wheels are locked and transmit torque).This allows the power from the first motor 40 to be transmitted to the output body 13 by the differential system 10 via the second input 102 (the ring gear in Figure 3). Thus, the input body 11 also drives the second input element 102 of the differential system 10. Since the output element 103 (the planet carrier in Figure 3) is also driven by the closing of the second freewheel 30, the first input element 101 (the pinion shaft in Figure 3) is also in motion.

[0148] Furthermore, in this second operating mode, thanks to the configuration of the transmission components, and in particular the freewheels within the powertrain, it is possible to assist the cyclist with the first motor 40 and / or the second motor 50. Indeed, the second motor 50 is mounted directly in parallel with the input body 11 or connected to the output body 13, so that torque can be supplied by the cyclist and / or the second motor 50 (through their respective transmissions). As for the first motor 40, it is possible to use it to provide torque assistance to the cyclist. This assistance from the first motor 40 can be achieved without using the differential system 10 as a speed variator and without changing the speed ratio of the powertrain. Energy is divided within the differential system 10, with some output via the second input element 102 and others via the output element 103.

[0149] The equilibrium equation in torque at the first input element 101 of the differential system 10 is:

[0150] The equilibrium equation in torque at the second input element 102 of the

[0151] The equilibrium equation in torque at the second input element 102 of the differential system 10:

[0152] The equilibrium equation in torque of the differential system 10:

[0153] -1 -1

[0154] Tl = - T2 = - T3

[0155] RD RD — 1)

[0156] By combining the four equations, we obtain:

[0157] Thus, we observe that a torque can be obtained at the output body 13 by introducing a positive torque on the input body 11 (corresponding to the torque supplied by the cyclist at the crankset), a positive torque by the second motor 50, a negative torque by the first motor 40, and a negative speed of the first motor

[0158] 40. In the second operating mode, the cyclist's assistance can be provided by the second motor 50 and / or by the first motor 40, which provides negative torque and negative speed, thus introducing positive power.

[0159] The advantage of the second operating mode is that it allows for assistance from one or both motors simultaneously, depending on the operating point, in order to optimize the overall efficiency and / or thermal state of the powertrain while preserving battery range. Compared to the first operating mode, at lower gears, the efficiency is better. This is because neither motor regenerates energy injected into the system. Thus, the method and powertrain according to the invention make it possible to cover a wide range of speed ratios. These wide ranges are covered while optimizing the overall efficiency and / or thermal state of the powertrain and preserving battery range.

[0160] The control of the second operating mode can be based on several steps. Optionally, the control can include an estimation of the vehicle and rider mass. The control can also include the calculation of the total torque required, the calculation of the assistance torque (a fraction of the total torque), and the distribution of the assistance torque between the first motor (40) and the second motor (50).

[0161] Regarding the estimation of the mass of the vehicle and the cyclist, it is possible to measure or estimate this data using several methods. These may include taking into account the average value for cyclists in a target group, inputting the cyclist's mass by the cyclist themselves through an interface, measuring the deformation of an element subjected to the stress associated with the cyclist's weight (such as the deformation of a part of the frame, the deformation in the saddle, the travel of a possible suspension, etc.), calculating the mass by solving the dynamic equilibrium equation (Newton's law) on the vehicle-cyclist system, and / or a combination of the aforementioned methods.

[0162] Regarding the estimation of the vehicle-cyclist combination's mass, the estimate can be calculated by solving the dynamic equilibrium equation (Newton's law) for the vehicle-cyclist combination. Such an estimation is made, in particular, during the first operating mode, with a view to a transition to the second operating mode (and assuming that the mass remains constant). In simplified terms:

[0163] > F = my

[0164] With

[0165] F (force) represents the forces acting on the system, m (mass) represents the inertia of the system, and a (acceleration) represents the kinematics. More precisely, the inertia of the vehicle-cyclist system is not only due to their mass but also to a contribution from the rotational inertia of the parts in circular motion, such as the wheels. This equivalent inertia is denoted m*.

[0166] The efforts across the cycling community are multifaceted:

[0167] - The torque of the transmission applied to the wheel (Tw)

[0168] - Gravity

[0169] - Aerodynamic friction losses of the bicycle and the cyclist

[0170] - Friction losses in mechanics

[0171] - Rolling resistance, i.e., losses within the tires due to deformation (hysteresis cycles),

[0172] - Losses due to suspension damping, if the bicycle is equipped with it

[0173] - Other types of losses

[0174] Thus, we can write (in the coordinate system associated with the direction of the cyclist)

[0175] With

[0176] - rw: the radius of the drive wheel

[0177] - g: gravitational acceleration

[0178] - a: the slope of the coast

[0179] - Losses: the sum total of the losses

[0180] - m*: the inertia of the bicycle and cyclist group

[0181] In the first mode of operation, the dynamic equilibrium equation is solved at regular intervals.

[0182] The kinematics (specifically speed and acceleration) are estimated directly and indirectly using the inertial measurement unit (accelerometer, gyroscope, and / or inclinometer) implemented on the bicycle, potentially within the drivetrain. The transmission forces are determined by the drivetrain's torque control strategy. Other forces acting on the bicycle are either estimated or neglected.

[0183] In simplified terms: F = ma

[0184] In detail:

[0185] Tw

[0186] - mq sin sin a — Flosses m » = - rw a has

[0187] Thus, it is possible to calculate an estimate of the mass via an iterative calculation. For reasons of accuracy, it is preferable to perform the calculation

[0188] - During a sharp acceleration

[0189] - When crossing terrain with a slight / bare slope (unless a good estimate of the slope is available)

[0190] - When losses are low (above a critical speed to avoid proportionally significant rolling resistance, and lower than another critical speed to avoid aerodynamic losses).

[0191] Inertia estimation can perform the calculation during certain periods when these conditions are more closely met. In some cases, losses and the effect of gravity can be neglected. A robust mass estimate is obtained by filtering the point-based estimation signal. This value is stored in memory.

[0192] Regarding the calculation of the total torque required at the output of the powertrain unit (TDU), it is possible to determine the total torque needed to achieve the desired behavior in several ways:

[0193] - By choosing a fixed torque, determined by design

[0194] - By calculating a torque that depends on the speed and / or acceleration of the bicycle

[0195] - By calculating a torque that depends on the speed of the pedals

[0196] - By calculating a torque that depends on the slope

[0197] - By calculating a torque that depends on the cyclist's torque (assistance proportional to pedaling torque is sought by electric bike users because it is more pleasant and more natural)

[0198] - By solving the dynamic equilibrium equation (Newton's law) on the vehicle-cyclist system

[0199] - By a combination of the aforementioned methods - By using a neural network or artificial intelligence that can use the same input data as the previous methods (or any other available input data) and that is trained elsewhere.

[0200] The cyclist's torque can be estimated or measured:

[0201] - By measuring the deformation of one or more parts of the transmission's kinematic chain. For example, a strain gauge torque sensor can be used on a specific part. According to another method, the cyclist's torque on the crankset is estimated, firstly, by measuring the deformation of a section of the powertrain's kinematic chain through which the cyclist's force passes, by comparing the position at the two ends of this section, and secondly, by comparing the stiffness of this section, which has been determined beforehand.

[0202] - By measuring the deformation of a support part (direct or indirect) of the transmission chain, provided that it is subjected to stress during pedaling by the cyclist

[0203] - By measuring the acceleration of the pedal assembly relative to the input body

[0204] - By applying a positive and increasing torque to the first motor 40 until the second freewheel opens, in order to calculate the dynamic equilibrium on the differential system

[0205] By measuring the amplitude of a sinusoidal signal corresponding to the speed of the pedals (the constant part of the speed coming mainly from the assistance and the cyclically variable part coming mainly from the pedaling effort of the cyclist)

[0206] - Through a combination of the aforementioned estimates and measures.

[0207] In one particular embodiment, the estimation of pedaling torque (or torque on the crankset) by measuring the transmission deformation is implemented through calculation based on the position of the bottom bracket axle position sensor and the position of the second motor. More precisely, the estimated pedaling torque estimator could be: coefA, a coefficient, is defined based on the elasticity of the transmission, including the elasticity of the transmission from the bottom bracket axle to the axle of the second motor, but also and especially that of the first freewheel F1. It is also possible to imagine more complex laws that also take into account the position sensor of M1.

[0208] The slope can be estimated or measured:

[0209] - Through information received by an inclinometer

[0210] - Through information received from an inertial navigation system

[0211] - By combining the position determined using the GPS system (or equivalent) and map data (spatial derivative of altitude)

[0212] - By combining data received from a barometric altimeter with the speed of the bicycle

[0213] - Etc.

[0214] - Through a combination of the aforementioned estimates and measures.

[0215] The total torque can be estimated using Newton's law as follows. Calculating the assistance torque in the second operating mode relies on the same equation as estimating the mass in the first operating mode, but this time, the mass is considered known, and the goal is to determine the torque to be applied. The system mass is assumed to be unchanged from the mass in the first operating mode; there is no reason for it to have changed significantly. Therefore, the value recorded during the first mode is an excellent approximation. This allows us to calculate the required torque:

[0216] Tw = rw (m* a + mg sin a + Flosses)

[0217] In one embodiment, acceleration and losses can be considered negligible. Therefore, we obtain:

[0218] Tw = rw mg sin aa, the slope of the hill, is obtained by estimation based on measurements from the inertial measurement unit. Torque is transmitted from the powertrain to the wheel, possibly via the downstream transmission:

[0219] TDU = RTout Tw

[0220] If the third freewheel 14 (optional) is in transit, which is generally the case when the second operating mode is active.

[0221] Regarding the calculation of the assistance torque, this is mainly based on the total torque:

[0222] Tassist@out = fct TDU)

[0223] The torque of the powertrain is the sum of the assistance torque and the cyclist's torque, both evaluated at the output:

[0224] TDU@out = Tassist@out + Tcyclist@out

[0225] In one embodiment, the assistance torque is a function of the cyclist's torque and possibly can be proportional to the cyclist's torque:

[0226] Tassist@out = Kassist Tcyclist@out

[0227] Regarding the distribution of assistance torque between the first motor (40) and the second motor (50), the torque at the output of the powertrain is a combination of the rider's torque and the torque supplied either by the first motor (40), the second motor (50), or the combined torques of both motors (40 and 50) in a proportion determined by a distribution method. The objective of the distribution method may be:

[0228] - To increase the overall efficiency of the powertrain

[0229] - To protect one or another of the components and organs (electronics, engine, transmission, etc.) according to their condition, thermal for example

[0230] - To minimize noise, vibration or any other undesirable effects of system operation

[0231] - To do without a defective component or part

[0232] - Etc.

[0233] - Through a combination of the aforementioned objectives.

[0234] In the second operating mode, the ratio (for example, the respective rotational speeds relative to the non-rotating body – for example, between the output and input bodies) is continuously the minimum ratio. For example, the control unit 22 can be configured to control the transmission ratio accordingly. This can be advantageous, for example, when climbing steep hills.

[0235] In the event of a powertrain failure, a depleted battery 25, or certain component failures (or for any other reasons specific to the control strategy), the method may include a third operating mode (corresponding to a third operating mode in which the powertrain is configured). In this third operating mode, the cyclist provides torque to the crankset 21, and the control unit 22 does not provide a drive command to the first motor 40 or the second motor 50. This allows the cyclist to propel the vehicle even when the powertrain is no longer operational.

[0236] More specifically, in the third operating mode, the kinematics are identical to the second operating mode. Motion can be transmitted from the input body 11 (the crankset 21 in Figure 3) to the output body 13 (the chainring in Figure 3) via the first freewheel 26, the second freewheel 30, and possibly via the reduction gears 28, 32, 34. In this case, the first freewheel 26 and the second freewheel 30 are engaged to transmit the cyclist's power to the output body 13. Thus, the input body 11 also drives the second input element 102 (the sprocket in Figure 3) of the differential system 10. Since the output element 103 is also driven by the engagement of the second freewheel 30, the first input element 101 (the pinion shaft in Figure 3) is also in motion. In these modes, the two motors are not controlled and their torque is therefore zero (losses are neglected).

[0237] In this third operating mode, the powertrain provides no assistance. The torque supplied by the first motor 40 and the second motor 50 is zero. The powertrain also does not control the gear ratio. The gear ratio is mechanically fixed and is determined by the ratio of the optional reduction gears 32 and 34. The table below summarizes the three operating modes, along with the sign of the speed, torque, and power of the rider, the first motor 40, and the second motor 50. A "0" indicates that the motor is inoperative.

[0238] With :

[0239] - Mode: 1, 2, 3: the first, second and third operating modes described

[0240] - Wax: the circumstances of the sub-Mode

[0241] - Cy: Cyclist

[0242] - M40: First 40 engine

[0243] - M50: Second 50 engine

[0244] - V: Speed

[0245] - C: Couple

[0246] - P: Power

[0247] - R: Ratio

[0248] - A: assistance

[0249] - CVT: Continuously Variable Transmission

[0250] - Fix. : Fixed.

[0251] Furthermore, the first operating mode can be further divided into two sub-modes ((a) and (b)). The power of drive unit 1 (DU) is equal to the sum of the assistance power (Passist) and the rider's power (neglecting losses). The assistance power corresponds to the sum of the powers of motors 40 and 50. Thus, sub-modes (a) and (b) of the first operating mode vary depending on whether the power of the first motor 40 (PM40) is greater or less than the assistance power (Passist). The second operating mode can also be divided into three sub-modes (M40, M50, M40+50) depending on whether only the first motor 40 is operating, only the second motor 50 is operating, or both the first motor 40 and the second motor 50 are operating.

[0252] Other modes of operation may be conceivable.

[0253] In certain embodiments and / or modes of operation, the ratio (e.g., the respective rotational speeds relative to the non-rotating body) between the output and input bodies can be selected by the rider or by software (e.g., the control unit) from a set of predefined (discrete) ratio values. For example, the control unit 22 can be configured to control the transmission ratio accordingly. In this case, step-by-step gear changes are emulated because the selected ratio values ​​are virtual speed ratios.

[0254] In some embodiments and / or modes of operation, the powertrain is configured to apply torque at the output body even if the cyclist provides virtually no (or no) power at the input body, which can, for example, allow the cyclist to move the vehicle with little effort, for example when walking with a bicycle.

[0255] In certain embodiments and / or operating modes, the powertrain is configured to apply a negative (braking) torque to the output shaft. In this case, the powertrain is configured to absorb kinetic energy. The powertrain can, for example, be configured to supply the recovered energy to the battery, for example, to store this recovered energy.

[0256] The invention also proposes a step for identifying the condition(s) that trigger the transition from one mode to another, in particular between the first operating mode and the second operating mode. This step initiates a transition with the aim of:

[0257] - To increase the overall efficiency of the powertrain

[0258] - To protect one or another of the components or parts (electronics, engine, transmission, etc.) according to their condition, thermal for example - To minimize noise, vibrations or any other undesirable effects of the system's operation

[0259] - To do without a defective component or part

[0260] - etc

[0261] - Through a combination of the aforementioned goals.

[0262] The transition between modes is preferably smooth and allows for continuous adjustment of torque and speed between the operating point of the initial mode and that of the final mode. The adjustment of the operating point in terms of speed and torque can be done sequentially, starting with speed or torque, or simultaneously.

[0263] T = i Tmode2 + (1 — i) Tmodel

[0264] RDU = j RDUmode2 + (1 — j) RDUmodel

[0265] With i and j being the transition coefficients:

[0266] - From the first mode to the second mode: i: 0 - 1 j: 0 1

[0267] - And conversely, from the second mode to the first mode: i: 1 - 0 j: 1 0

[0268] In one embodiment, the transition between the first and second modes is achieved first by adapting the transmission ratio and then by adapting the torque. In another embodiment, the transition between the second and first modes is achieved first by adapting the torque and then by adapting the transmission ratio. In one embodiment, the transition coefficients can evolve continuously between their extreme values ​​according to more or less regular functions (i.e., differentiable to a greater or lesser degree) and over more or less long time intervals. The length of the transition intervals is chosen to ensure a smooth transition (without any perceived jolt) while also ensuring the responsiveness of the process and the vehicle.Within the scope of this document, the normal direction of pedaling is the direction of rotation of the pedal axle that corresponds to forward movement of the pedal-powered vehicle. Due to the couplings in the powertrain, in the first operating mode, the powertrain components preferably each have a direction of rotation that corresponds to this normal direction of pedaling (corresponding to mode 1(b) with PM40). <Passist). En outre, deux organes connectés ou reliés peuvent être connectés ou reliés directement ou indirectement. Ils peuvent, par exemple, être connectés directement ou être connectés indirectement via au moins une roue dentée intermédiaire, une courroie.

[0269] The powertrain control method may also include a "no-pedaling" mode, which is an additional mode to the others. Each transmission component of the powertrain is shown with play that generates vibrations when the cyclist does not apply torque to the crankset 21 (for example, when going downhill). Thus, when the cyclist does not apply torque to the crankset, balancing torques are applied by the first motor 40 and second motor 50 to constrain the transmission. The torques are low but sufficient to constrain the transmission components such as the sprockets. A low torque is applied to the first motor 40 and a reactive torque is applied to the second motor 50 to lock the transmission and prevent unwanted vibrations. The torques balance each other to avoid introducing net power or torque to the vehicle.By applying stress to the transmission, play in the transmission components is eliminated and unwanted vibrations are prevented. This improves driving comfort. This mode can be applied continuously, when vibrations are detected, or when such vibrations are likely to occur.

[0270] The invention also relates to a method for assembling the powertrain 1. The method may include supplying the first engine 40, the second engine 50, the electronic board 19, the structural part 58, and the first hull 71. The electronic board 19 is assembled to the structural part 58, with a thermal bond between the board and the part. The first engine 40 and the second engine 50 are assembled in the first hull 71. The output shafts 402, 502 (which include the shafted gears 101 and 54 respectively) of the first motor 40 and the second motor 50 are passed through the plane 80 comprising the face of the electronic board 19 and the structural part 58. Then the first compartment 561 delimited by the first shell 71 is closed by the structural part 58 so that the connection is established between the motors 40, 50 and the electronic board 19.To achieve this, the structural component 58 is assembled with the first shell 71 in such a way that the electronic board 19 is located in the first compartment 561 and in such a way as to align the rotors. The first compartment 561 is then supplied as a partially closed module. By partial closure, we mean an incomplete attachment of the structural component 58 to the first shell 71. For example, some fasteners 74 are installed to assemble the structural component 58 to the first shell 71. Other fasteners 74 will be added later to assemble the second shell 72 to the structural component 58. The closed module of the first compartment thus allows the motors 40, 50 and the electronic board 19 to be installed, with the motor output shafts protruding from the module through the structural component 58. The electronic board 19 is protected during subsequent handling.This module can be transported to another site to finalize the assembly of the powertrain 1. As such, the assembly process then includes the supply of transmission gears and the second housing 72. The gears are, in particular, all those of the differential system 10. The transmission gears of the differential are assembled to the module formed by the first compartment 561, along with gear 35. Next, an assembly consisting of the pedal assembly 21 and its axle 211, and gears 29 and 33, is also assembled to the module formed by the first compartment 561. At this stage, the assembly of this unit is made possible by the particular shape of the target 77 fixed to the axle 211 of the pedal assembly: the alternating sequence (conductor-insulator) is interrupted along part of its circumference.The portion of the target without alternating teeth is not materialized, thus avoiding the teeth 37 when the assembly is engaged along the axis of the crankset 211. The target 77 extends partially in a plane transverse to the axis 211 of the crankset. In other words, the target 77 (which measures the angular position of the crankset axis 211) has a circumferential irregularity (for example, like a notch) oriented to ensure the passage of the target 77 relative to the transmission gears already assembled into the module formed by the first compartment. In particular, the orientation of the target 77 avoids the teeth 37 of the sprocket 102, which forms the second input element and is already assembled into the module formed by the first compartment. The gear 38 is also assembled, in particular via the spline 78.The process then involves closing the second compartment 562 by assembling the second shell 72 to the structural part 58. The second compartment 562 encloses the transmission gears. The fact that the motors 40, 50 and the electronic board 19 are already in place in the first compartment facilitates the assembly of the gears and reduces the risk of damage to the motors 40, 50 and the electronic board 19. Organizing the motors and board in one compartment and the transmission components such as the gears in the other compartment simplifies the assembly of the powertrain.

[0271] Preferably, the propulsion assembly 2 includes one or more batteries 25 supplying electricity to any object, part, component, organ or element requiring it of the propulsion assembly 2 or more specifically of the powertrain 1, such as the (electric) motors 40, 50, the control unit 22, the sensors 76, etc.

[0272] A person skilled in the art will be able to adapt the equations to the different configurations and modes of operation. It will be evident to a person skilled in the art that the invention is not limited to the embodiments and examples illustrated and / or described above, but that its scope is more broadly defined by the claims introduced below.

Claims

47 Demands 1. Powertrain (1) of a pedal vehicle propulsion system comprising • A differential system (10) comprising a first input element (101), a second input element (102) and an output element (103), • A first motor (40) comprising an output shaft (402) driven by a rotor (404), the output shaft (402) driving a shaft-mounted pinion which is the first input element (101), • A second motor (50) comprising an output shaft (502) driven by a rotor (504), the output shaft (502) driving a shaft-mounted pinion (54), the second motor (50) being connected to the differential system by the shaft-mounted pinion (54), • An electronic card (19) supporting at least one control unit (22) capable of controlling the first motor (40) and the second motor (50), the electronic card (19) having a face included in a plane (80), • An input body (11) driven by a pedal assembly (21), the input body being connected to the second input element (102) of the differential system, • An output body (13) driven in rotation by the output element (103) of the differential system, and in which the output shaft (402) of the first motor (40) and the output shaft (502) of the second motor (50) extend through the plane (80) comprising the face of the electronic board (19), the shaft pinion (101) driven by the first motor (40) and the shaft pinion (54) driven by the second motor (50) being on the same side of the plane. - 48 - 2. Powertrain (1) according to claim 1, comprising a casing (56) with several compartments, the first motor, the second motor (50) and the electronic board (19) are in the same first compartment (561) and the shaft gears (54, 101) are in a second compartment (562).

3. Powertrain (1) according to the preceding claim, further comprising a structural part (58) delimiting the first and second compartments (561, 562) of the casing (56).

4. Powertrain (1) according to the preceding claim, wherein the electronic board (19) extends parallel and against the structural part (58), the structural part supporting at least one of the following parts: an output shaft bearing (402) of the first motor (40), an output shaft bearing (502) of the second motor, the electronic board (19).

5. Powertrain (1) according to either of the two preceding claims, wherein the housing (56) comprises • a first shell (71) defining the first compartment (561) with the structural piece (58) and • a second shell (72) defining the second compartment (562) with the structural part (58), The first shell (71) and the second shell (72) being on either side of the structural piece (58).

6. Powertrain (1) according to the preceding claim, further comprising a first seal between the first shell (71) and the structural part (58) and a second seal between the second shell (72) and the structural part (58). - 49 7. Powertrain (1) according to one of the two preceding claims, wherein the first motor (40) and the second motor (50) comprise power windings positioned opposite the first shell (71) on the opposite side of the electronic board (19).

8. Powertrain (1) according to any one of the three preceding claims, wherein the first motor (40) and the second motor (50) have identical output shaft lengths (402, 502) between the electronic board (19) and the first shell (71).

9. Powertrain (1) according to any one of the preceding claims, further comprising a second freewheel (30) between the input body (11) and the output body (13) such that the input body (11) drives the output body (13) at least at the same speed in the normal direction of pedaling.

10. Powertrain (1) according to the preceding claim, further comprising a first freewheel (26) between the crankset (21) and the input element (102) of the differential system (10). 1 1. Powertrain (1) according to one of the two preceding claims, the second freewheel (30) is arranged in such a way that the second input element (102) is able to drive the output body (13) via the second freewheel (30).

12. Powertrain (1) according to any one of the preceding claims, further comprising a third free wheel (14) between the output element (103) of the differential system and a rear wheel of the pedal vehicle, the free wheel being capable of coupling or uncoupling the rear wheel and the pedal assembly. 50 13. Powertrain (1) according to any one of the preceding claims, wherein the electronic board (19) is the single electronic control board of the first motor (40) and the second motor (50) and supports the current control chopper bridge of the first motor (40) and the current control chopper bridge of the second motor (50), execution components of the motor control algorithm, and the measurement of the angular positions of the output shaft (402) of the first motor (40) and the output shaft (502) of the second motor.

14. Powertrain (1) according to the preceding claim, comprising several sensors (76) on the electronic board (19), the sensors (76) being able to measure the angular positions of the output shaft (402) of the first motor (40) and of the output shaft (502) of the second motor.

15. Powertrain (1) according to any one of the preceding claims, further comprising a crankshaft (211) through the plane (80) comprising the face of the electronic board (19) and a sensor (76) on the electronic board (19), the sensor (76) being capable of measuring the angular position of the crankshaft.

16. Powertrain (1) according to one of the two preceding claims, wherein at least one of the sensors (76) is of the inductive type.

17. Powertrain (1) according to any one of the preceding claims, wherein the differential system comprises a planetary gear forming the first input element (101) and a ring gear forming the second input element (102) and one or more transmission elements between, on the one hand, the shaft pinion (54) of the second motor (50) and, on the other hand, the ring gear, the transmission component(s) comprising at least one or more intermediate gear wheels (35).

18. Powertrain (1) according to the preceding claim, wherein the differential system further comprises a planet carrier (103) forming the output element, the planet carrier (103) being connected to the output body (13) by a gear (38), the planet carrier (103) being in the ring gear (102), the satellite carrier (103) and the gear wheel (38) are connected through the crown (102) by a spline (78).

19. Powertrain (1) according to any one of the preceding claims when they depend on claim 2, further comprising power supply and information exchange connectors (90) for the powertrain (1), the connectors being located on the electronic board (19) and accessible through the casing (56).

20. Powertrain (1) according to any one of the preceding claims, capable of driving a rear wheel of the pedal vehicle by means of a downstream transmission (20), the downstream transmission being of a flexible type such as a chain or a belt.

21. Powertrain (1) according to the preceding claim, wherein the pedal assembly (21) is connected to the second input element (102).

22. Powertrain (1) according to any one of the preceding claims, further comprising a direct connection between the electronic board (19) and the power windings of the first motor (40) and the second motor (50).

23. Powertrain (1) according to any one of the preceding claims when they depend on claim 2, wherein the first and second motors (40, 50) include stators (406, 506) which are juxtaposed in the casing (56) and aligned along a direction of an axis (211) of the pedal assembly (21).

24. Pedal vehicle, comprising a propulsion assembly (2) including the powertrain (1) according to any one of the preceding claims.

25. A method for controlling a powertrain (1) of a pedal-powered vehicle propulsion system according to any one of the preceding claims, the pedals being driven by a cyclist and the method comprising • a first operating mode in which o the cyclist provides torque to the crankset, o the control unit (22) determines a rotational speed command for the first motor (40) and controls this motor according to this command, the rotational speed control acting on the speed ratio between the output body (13) and the input body (11) and o the control unit determines a torque or current command for the second motor (50) and controls this motor according to this command, this command corresponding to a level of total assistance, • a second mode of operation in which o the cyclist applies a torque to the crankset (21), o the control unit (22) determines only a driving instruction in torque or current, corresponding to a level of assistance, for the first motor (40) and / or the second motor (50) and drives this or these motors according to this instruction, and o the speed ratio between the output body (13) and the input body (11) is mechanically fixed. - 53 - 26. A method according to the preceding claim, further comprising • a third mode of operation in which o the cyclist provides torque to the crankset (21 ), o the control unit (22) does not determine a control command for the first motor (40) or for the second motor (50).

27. Method according to the preceding claim, wherein, in the third mode of operation, the torque supplied by the first motor (40) and the second motor (50) is zero.

28. A method according to any one of the preceding claims, wherein, in the second operating mode, • The control unit (22) determines a torque control setpoint corresponding to an assistance level for the first motor (40) and for the second motor (50), • The torque supplied by the cyclist to the crankset is positive. • The torque supplied by the second motor (50) is positive, • The torque supplied by the first motor (40) is negative, • The speed of the first motor (40) is negative.

29. A method according to any one of the preceding claims, further comprising the control of the second mode of operation by estimating the mass of the vehicle and the cyclist.

30. Method according to the preceding claim, wherein the estimation of the mass of the vehicle and the cyclist is made during the first mode of operation. 54 - 31. Method according to any one of the preceding claims, further comprising control of the second mode of operation by distribution of the torque supplied by the first motor (40), by the second motor (50) or by the torques of the two motors (40, 50).

32. A method according to any one of the preceding claims, further comprising a step of switching from one operating mode to another, the switching from one operating mode to another being achieved by continuously adapting the torque and speed between the operating point of one operating mode and the other.

33. Method according to the preceding claim, wherein the adaptation of the operating point in speed and torque is done sequentially starting with the speed or with the torque or is done simultaneously.

34. A method according to any one of the preceding claims, wherein the torque of the cyclist on the crankset is estimated, on the one hand, by measuring the deformation of a section of the kinematic chain of the powertrain traversed by the effort of the cyclist, by comparing the position at the two ends of this section, and, on the other hand, of the stiffness of this section determined beforehand.

35. A method according to any one of the preceding claims, the powertrain being according to any one of claims 9 to 11, the method being such that • In the first operating mode, the input body (11) is coupled to the second input element (102) by the first freewheel (26) and the input body (11) is decoupled from the output body (13) by the second freewheel (30), • In the second operating mode, the input body is coupled to the second input element (102) by the first freewheel 55 (26) and the input body (11) is coupled to the output body (13) by the first freewheel and by the second freewheel (30).

36. A method according to any one of the preceding claims, wherein, when the cyclist does not apply torque to the pedals, compensating torques are applied by the first motor (40) and second motor (50) to constrain the transmission.

37. A method for assembling the powertrain (1) according to any one of the preceding claims, comprising • The supply of the first engine (40), the second engine (50), the electronic board (19), a first hull (71) and a structural part (58), • The assembly of the electronic board (19) to the structural part (58), • The assembly of the first engine (40) and the second engine (50) in the first hull (71), • The closure of a first compartment (561) by the structural part (58) by assembly of the structural part (58) with the first shell (71), the structural part (58) being assembled with the first shell (71) with the electronic board (19) in the first compartment (561), The first compartment (561) is supplied as a partially closed module.

38. Assembly method according to the preceding claim, further comprising • The supply of transmission gears and a second shell (72), • The assembly of the transmission gears to the module formed by the first compartment (561), 56 - • The closure of a second compartment (562) by assembling the second shell (72) to the structural part (58), the second compartment (562) enclosing the toothed transmission roads.

39. Assembly method according to the preceding claim, the powertrain comprising • a target (77) mounted for rotation on an axis (211) of the crankset, the target (77) having a circumferential irregularity • at least one inductive type sensor (76) on the electronic board (19), the sensor (76) being capable of detecting the rotations of the target (77), the method comprising, before the closure of the second compartment (562), • the fixing of the target (77) to the bottom bracket axle (211), • the assembly of the crank axle (211) and the target (77) to the module formed by the first compartment (561), the circumferential irregularity of the target being oriented to ensure the passage of the target relative to the transmission gears assembled to the module formed by the first compartment.

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