METHOD FOR BRAKING A VEHICLE COMPRISING A HYBRID DRIVE SUB-ASSEMBLY

Abstract

A braking method for a vehicle comprising a hybrid drive sub-assembly which includes a transmission (18) with a multi-disc type shaft braking device (90) meshing with the output shaft (57) and arranged to brake a secondary shaft (16) when the coupling device is in the second coupling position, and an electric motor unit (5) comprising at least one reversible electric machine (56) and a coupling device (58); the braking method having the successive steps of: - positioning the coupling device (58) in the second coupling position; - over a first time interval, generating a first resistive torque to brake the secondary shaft (16) with the reversible electric machine (56) operating as a generator;- over a second time interval, generate a second resistive braking torque via the shaft braking device (90) simultaneously with a third resistive torque with the reversible electric machine (56) operating as a generator. (Abstract figure: Figure 1);

Description

Title of the invention: METHOD FOR BRAKING A VEHICLE COMPRISING A HYBRID DRIVE SUB-ASSEMBLY Technical field of the invention

[0001] The invention relates to a braking method for a vehicle comprising a hybrid drive sub-assembly.

[0002] The hybrid drive subassembly is positioned between an engine, for example an internal combustion engine, and one or more drive wheels of a vehicle. It relates in particular, though not exclusively, to such a subassembly intended for use on a heavy goods vehicle, i.e., a road vehicle weighing more than 3.5 tonnes, especially a tractor unit. The vehicle may also be a coach, as per prior art.

[0003] Document WO2011 / 072986A1 describes a hybrid sub-assembly for a vehicle drive, comprising a primary shaft intended to be driven by a thermal engine of the vehicle, a secondary shaft intended to drive a set of one or more drive wheels of the vehicle, and a transmission comprising one or more primary gears fixed in rotation to the primary shaft or capable of being coupled to the primary shaft, a plurality of secondary gears fixed in rotation to the secondary shaft or capable of being coupled to the secondary shaft, and two intermediate shafts to which intermediate gears are fixed in rotation, the primary gear(s) and the secondary gears each meshing with a corresponding gear among the intermediate gears.The hybrid drive sub-assembly further comprises a reversible electric machine kinematically linked to the intermediate shafts via an upstream reduction stage and a dog clutch coupling mechanism, said electric machine being capable of operating as a current generator to brake the intermediate shafts or as a drive motor for the intermediate shafts.Such an electric machine allows for different operating modes, including transient operation to brake or accelerate intermediate shafts and facilitate transmission synchronization during gear changes; motor operation to assist the vehicle's main engine outside of gear changes; and generator operation to power vehicle accessories or a battery, particularly during vehicle braking. In this hybrid sub-assembly, the machine... reversible electric is arranged in line with the heat engine, that is to say that the rotor of the electric machine is concentric with the output of the heat engine.

[0004] In document WO2011 / 072986A1, the reversible electric machine is necessarily kinematically linked to the secondary shaft via the intermediate shaft. This connection to the secondary shaft cannot be direct, so certain operating modes are not optimized in terms of mechanical efficiency, particularly the vehicle braking phases and the battery regeneration phase. During these operating phases, the torque from the vehicle's wheels must pass through the entire transmission to enter the reversible electric machine and allow it to operate in electric generator mode. With this type of vehicle architecture, it will be necessary to increase the size of the reversible electric machine to improve the vehicle's braking capacity.

[0005] It is therefore necessary to consider a mechanical configuration allowing the reversible electric machine to be kinematically linked directly to the secondary shaft with a suitable reduction ratio in order to consider new functionalities such as the vehicle braking assistance mode without intervention of the intermediate shaft and to use a suitable braking method. Description of the invention

[0006] The invention aims to remedy the drawbacks of the prior art and to propose a high-performance vehicle braking method without the need to increase the size of the reversible electric machine, in particular through better integration of the electric machine within the intermediate and secondary shafts of the transmission box.

[0007] To this end, according to a first aspect of the invention, a braking method for a vehicle is proposed, comprising a hybrid drive sub-assembly which includes:

[0008] • at least one primary tree;

[0009] • at least one secondary tree;

[0010] • a transmission box comprising at least one intermediate shaft separate from the primary shaft and the secondary shaft and gear trains to achieve several transmission ratios between the primary shaft and the secondary shaft via the intermediate shaft;

[0011] • an electromotor unit comprising at least one reversible electrical machine, and a coupling device which, in a first coupling position, kinematically links the output shaft of the reversible electric machine to the intermediate shaft and, in a second coupling position, kinematically links the output shaft of the reversible electric machine to the secondary shaft without passing through the shaft intermediate ;

[0012] • a multi-disc type shaft braking device kinematically linked with the output shaft to brake the secondary shaft when the coupling device is in the second coupling position;

[0013] the braking method comprising the successive steps of:

[0014] - position the coupling device in the second coupling position

[0015] - then, over a first time interval, generate a first resistive torque for brake the secondary shaft with the reversible electric machine operating as a generator in a torque range exceeding the maximum continuous torque value permissible by the electric machine;

[0016] - then, over a second time interval, generate a second resistive torque of braking via the shaft braking device simultaneously with a third resisting torque with the reversible electric machine operating as a generator in a torque range below the maximum continuous torque value permissible by the electric machine.

[0017] According to the braking method of the invention, it is advantageous to brake the secondary shaft relative to a fixed part of the transmission when the coupling device is in the second secondary coupling position. This provides a simple way to add braking capacity to the vehicle.

[0018] In the second coupling position, the coupling device allows direct power transmission between the reversible electric machine and the secondary shaft without driving the intermediate shaft. This makes it possible, in particular, to consider a vehicle braking assistance mode in which the shaft braking device is arranged to slow down the secondary shaft. The shaft braking device of the hybrid subassembly makes it possible to slow the vehicle down when it is on a gentle slope and the driver does not want to use the main braking system. In this braking assistance mode, the braking capacity of the multi-disc type shaft braking device can be between 20% and 60% of the braking capacity of the reversible electric machine.The vehicle's deceleration function without a shaft braking device would require a high-power reversible electric machine. A large amount of energy needs to be dissipated over a short period. Therefore, the reversible electric machine used alone for this deceleration function would need to have maximum power characteristics specifically tailored to this application. Through this braking method, the shaft braking device immediately provides the vehicle driver with significant braking power. Subsequently, the driver has access to additional shaft braking. Secondary power is available over a long period because the electric machine is used below its maximum permissible continuous torque. This allows for a reduction in the size of the reversible electric machine while still ensuring the vehicle's other operating modes. The cost of the reversible electric machine is thus reduced.

[0019] Preferably, the second time interval is greater than the first time interval.

[0020] According to a variant of this braking method, the second resisting torque can be lower than the third resisting torque. This reduces the cost of the electric machine. Thanks to this proportion of resisting torque, the shaft braking device provides the necessary additional braking of the secondary shaft and allows for a reduction in the size of the reversible electric machine while ensuring the other operating modes.

[0021] According to a variant of this braking method, the second resisting torque can be greater than or equal to the third resisting torque. This makes it possible to reduce the size of the reversible electric machine.

[0022] Preferably, the braking method comprises the following successive step:

[0023] - then, over a third time interval, generate only the second couple braking resistance via the shaft braking device without intervention from the reversible electric machine.

[0024] According to this braking method, the multi-disc shaft braking device may comprise a rotating disc carrier arranged to be rotationally linked with a drive shaft of the electric motor unit, a static disc carrier arranged to be rotationally linked with a fixed part of the gearbox, and a multi-disc assembly consisting of a first set of discs engaging with splines of the rotating disc carrier, and a second set of discs engaging with splines of the static disc carrier. The shaft braking device is indirectly driven by the output shaft of the reversible electric machine using a speed reducer, the rotating disc carrier being rotationally fixed to the output pinion of the speed reducer. Thus, the dimensioning of the shaft braking device takes into account the reduction ratio associated with the speed reducer.The risk of centrifugal force on the multi-disc assembly of the shaft braking device is limited due to the reduction in rotational speed.

[0025] According to this braking method, the multi-disc assembly of the shaft braking device can be axially pressed by an annular actuating piston, the actuating piston being axially guided within a pressure chamber formed directly or indirectly in a protective housing of the electromotor unit.

[0026] According to this braking method, the rotating disc carrier of the shaft braking device can be linked in rotation by spline with the transmission shaft of the remote electric motor unit the axis of revolution of the output shaft or rigidly fixed on the transmission shaft of the remote electric motor unit the axis of revolution of the output shaft by means of fixing screws, rivets or by welding.

[0027] According to this braking method, the coupling device may comprise one or more of the following coupling mechanisms:

[0028] - a dog clutch mechanism;

[0029] - a clutch mechanism, preferably a friction clutch mechanism, preferably moist;

[0030] - a dual friction clutch, preferably wet.

[0031] According to this braking method, the output shaft of the reversible electric machine may have an axis of revolution parallel to an axis of revolution of the intermediate shaft, one or more of the following characteristics preferably being realized:

[0032] - the axis of revolution of the output shaft coincides with the axis of revolution of the intermediate tree;

[0033] - the axis of revolution of the output shaft is distant from the axis of revolution of the shaft intermediate ;

[0034] - the axis of revolution of the output shaft is distant from one axis of revolution of the shaft primary ;

[0035] - the axis of revolution of the output shaft is distant from one axis of revolution of the shaft secondary.

[0036] According to this braking method, the electromotor group can comprise two reversible electric machines, each comprising a rotor with an output shaft rotating around an axis of rotation, the two output shafts simultaneously engaging with a common toothed wheel arranged parallel to the two axes of rotation, the shaft braking device being indirectly engaged with the output shafts by braking the associated common toothed wheel.

[0037] According to another aspect of the invention, it relates to a hybrid drive subassembly for a vehicle, of the type comprising: at least one primary shaft, at least one secondary shaft, and a gearbox comprising at least one intermediate shaft separate from the primary and secondary shafts, and gear trains for achieving several transmission ratios between the primary and secondary shafts via the intermediate shaft. The hybrid subassembly also comprises an electric motor unit comprising at least one reversible electric machine, and a coupling device which, in a first coupling position, kinematically connects the output shaft of the reversible electric machine to the intermediate shaft and, in a second coupling position, connects ci- The output shaft of the reversible electric machine is directly connected to the secondary shaft without passing through the intermediate shaft. Remarkably, the hybrid subassembly includes a multi-disc shaft braking device kinematically linked to the output shaft to brake the secondary shaft when the coupling device is in the secondary coupling position.

[0038] Preferably, the shaft braking device can be indirectly connected to the output shaft. According to the invention, when the shaft braking device is indirectly connected to the output shaft, one of the components of the shaft braking device meshes with a drive shaft kinematically linked to the output shafts of the electrical machine(s). The kinematic linkage can be achieved using a gear, a belt, or a drive chain. In this case, one of the components of the shaft braking device directly meshes with the associated drive shaft. Thus, the shaft braking device is indirectly connected to the output shaft by braking the associated drive shaft.

[0039] The direct transmission of power between the reversible electric machine and the secondary shaft without driving the intermediate shaft also allows for other modes of operation which will be described later, including: a mode of permanent electric drive of the secondary shaft by the reversible electric machine operating as a motor, a transient mode of maintaining traction during gear changes, a pure regenerative braking mode minimizing the resisting mechanical torque.

[0040] Preferably, the shaft braking device comprises a multi-disc assembly.

[0041] Advantageously, the multi-disc type shaft braking device can be interposed in the direction of torque transmission between the rotor of the reversible electric machine and the coupling device.

[0042] According to a variant of the invention, the shaft braking device can be indirectly connected to the output shaft of the reversible electric machine by using a speed reducer, the rotating disc carrier being rotationally fixed to the output pinion of the speed reducer.

[0043] According to one embodiment of the invention, the multi-disc assembly of the shaft braking device can be axially pressed by an annular actuating piston coaxial with the output shaft of the reversible electric machine, the actuating piston being axially guided within a pressure chamber formed directly or indirectly in a protective housing of the electric motor unit. This shaft braking device structure has the advantage of being radially compact and easily integrated into a gearbox.

[0044] According to another embodiment of the invention, the multi-disc assembly of the shaft braking device can be axially pressed by an actuating piston of the shape annular, coaxial to the output shaft of the reversible electric machine, the actuating piston being guided axially within a pressure chamber formed directly or indirectly in the gearbox housing.

[0045] The reversible electric machine may in particular be a permanent magnet synchronous machine, an asynchronous machine, a variable reluctance electric machine or a variable reluctance synchronous electric machine, known as a synchro-reluctant machine.

[0046] The reversible electric machine can preferably be sized so as to be fully operational over wide operating ranges in the various operating modes envisaged. Thus, it is preferable that the reversible electric machine meet one or more of the following criteria:

[0047] - the reversible electric machine is capable of continuously developing a torque engine greater than 300 Nm, and preferably greater than 350 Nm, in a speed range of more than 1000 rpm, and preferably more than 2000 rpm inclusive, having a lower limit which is less than 6000 rpm, and preferably less than 5000 rpm, and an upper limit which is greater than 6000 rpm, preferably greater than 7000 rpm, and preferably greater than 9000 rpm;

[0048] - the reversible electric machine is capable of developing a higher resistive torque at 400 Nm and preferably above 450 Nm in a speed range of more than 3000 rpm, and preferably above 4000 rpm having a lower bound which is less than 6500 rpm, and preferably less than 6000 rpm and an upper bound which is greater than 9000 rpm, and preferably greater than 10000 rpm, for 30 seconds;

[0049] - the reversible electric machine is capable of developing a motor torque greater than 50 Nm and preferably more than 60 Nm in a speed range of more than 5500 rpm, and preferably more than 7000 rpm having a lower bound which is less than 5000 rpm, and preferably less than 4500 rpm and an upper bound which is more than 10000 rpm, and preferably more than 11000 rpm, for 5 seconds in transient gear change regime.

[0050] According to a particularly advantageous embodiment, the hybrid sub-assembly further comprises a power take-off element, suitable for being driven at least by the reversible electric machine, preferably the power take-off element is permanently kinematically linked to the intermediate shaft;

[0051] According to this embodiment, the power take-off element can be coaxial with the intermediate shaft.

[0052] According to another particularly advantageous embodiment, the hybrid subassembly comprises a power take-off element, capable of being driven at least by the reversible electric machine, the power take-off element being kinematically linked to permanently attached to the output shaft of the reversible electric machine.

[0053] According to another particularly advantageous embodiment, the electric motor unit may comprise two reversible electric machines, each comprising a rotor with an output shaft rotating about an axis of rotation. The two output shafts mesh simultaneously with a common gear arranged parallel to the two axes of rotation. The shaft braking device is indirectly engaged with the output shafts by braking the associated common gear. In this way, the use of two reversible electric machines improves the traction capacity of the vehicle operating in the permanent electric drive mode of the secondary shaft via the reversible electric machine. The association of the shaft braking device with the common gear allows the vehicle's braking assistance mode to be distributed between the two reversible electric machines.

[0054] It is then possible to consider driving the power take-off by the reversible electric machine without using the vehicle's main engine, which makes it possible to reach rotational speeds much higher than 1000 rpm, for example higher than 1500 rpm, and where appropriate up to 5000 rpm.

[0055] In practice, the transmission box may advantageously comprise:

[0056] - one, or preferably several primary gears suitable for being coupled to the primary shaft, for example by one or more coupling and uncoupling mechanisms, for example synchronizers and / or dog clutches,

[0057] - several secondary gears suitable for being coupled to the secondary shaft, by for example by one or more coupling and uncoupling mechanisms, for example synchronizers and / or dog clutches,

[0058] - intermediate gears permanently fixed to the intermediate shaft median, the primary gear(s) and the secondary gears each permanently meshing with a corresponding gear among the intermediate gears to make the gear trains.

[0059] In practice, the transmission includes coupling mechanisms for alternately coupling each of the primary gears to the primary shaft, and each of the secondary gears to the secondary shaft. If necessary, the hybrid sub-assembly may further include a dry or wet friction clutch for placement between the primary shaft and the main motor.

[0060] Various configurations of the primary gears, secondary gears, intermediate shaft and rotor of the reversible electric machine are conceivable.

[0061] According to one embodiment, the primary tree and the secondary tree have coincident axes of revolution. Alternatively, these axes are parallel and distant.

[0062] According to an example embodiment, the output shaft of the electric machine re- reversible has an axis of revolution parallel to an axis of revolution of the intermediate shaft, one or more of the following characteristics preferably being realized:

[0063] - the axis of revolution of the output shaft is coincident with the axis of revolution of the intermediate tree;

[0064] - the axis of revolution of the output shaft is distant from the axis of revolution of the shaft intermediate ;

[0065] - the axis of revolution of the output shaft is distant from one axis of revolution of the shaft primary ;

[0066] - the axis of revolution of the output shaft is distant from one axis of revolution of the shaft secondary.

[0067] According to one embodiment, the coupling device comprises an epicyclic gear train arranged kinematically between the output shaft and the secondary shaft.

[0068] Depending on different variants, the coupling device comprises one or more of the following coupling mechanisms:

[0069] - a dog clutch mechanism,

[0070] - a synchronizer mechanism,

[0071] - a clutch mechanism, preferably a friction clutch mechanism, preferably damp

[0072] - a dual friction clutch, preferably wet,

[0073] - a triple friction clutch, preferably wet.

[0074] In particular, a non-synchronizing dog clutch mechanism may be considered in cases where the electric machine itself is intended to be used to synchronize the coupling device with the associated gear.

[0075] According to one embodiment, the hybrid subassembly can be equipped with a control unit for the reversible electric machine and the coupling device, and sensors capable of generating a signal representing the rotational speed of the intermediate shaft or a kinematically linked component thereof, and a signal representing the rotational speed of the reversible electric machine or a kinematically linked component thereof. The control unit can, in particular, be used to synchronize the coupling device.Preferably, the control unit is capable, in a disengaged state of the coupling device, of controlling the reversible electric machine so that a relative rotational speed between the coupling member kinematically linked to the reversible electric machine and the coupling member kinematically linked to the intermediate shaft is achieved under a predetermined condition, and, when the predetermined condition is met, of controlling a coupling of the coupling device. The predetermined condition could, for example, be a zero relative rotational speed or a predetermined relative sliding speed.

[0076] According to another aspect of the invention, it comprises a hybrid power unit with a main engine, preferably an internal combustion engine, and a hybrid sub-assembly as described above. The main engine is equipped with a main drive shaft connected to the primary shaft directly or via a clutch or torque converter. brief description of the figures

[0077] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures.

[0078] [Fig-1] [Fig.1] illustrates a hybrid drive subassembly of a vehicle following a first embodiment.

[0079] [Fig.2] The [Fig.2] illustrates a detailed view of an electromotor group of the hybrid drive subassembly of the [Fig.1].

[0080] [Fig.3] Fig.3 illustrates the shaft braking device of the hybrid subassembly according to the first embodiment.

[0081] [Fig.4] The [Fig.4] illustrates a diagram comparing the resisting torque available within the reversible electric machine with the resisting braking torque of the shaft braking device.

[0082] [Fig.5] Fig.5 illustrates the evolution of the vehicle's speed over time during the use of the braking method.

[0083] [Fig.6] Fig.6 illustrates a hybrid drive subset of a vehicle according to a second embodiment.

[0084] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of implementation methods

[0085] Figures 1 and 2 illustrate a hybrid sub-assembly 10 of a vehicle drive system, comprising a primary shaft 12 intended to be driven by a main engine 14 of the vehicle, for example a heat engine, a secondary shaft 16 intended to drive an assembly of one or more drive wheels of the vehicle (not shown), and a transmission 18.

[0086] The connection of the main motor 14 to the primary shaft 12 may include a clutch 20 of any suitable type, for example a slip clutch. The connection of the secondary shaft 16 to the vehicle wheels may include one or more drive axles.

[0087] The transmission 18 comprises an intermediate shaft 26 to which intermediate gears 28, 30, 32, 34, 36 are rotationally fixed. Two primary gears 38, 40, coaxial with the primary shaft 12, each form a gear train with a corresponding gear 28, respectively 30, among the intermediate gears. The meshings of the gear trains 38, 28 and 40, The connections between primary gears 38, 40 and the corresponding intermediate gears 28, 30 are permanent. A double synchronizer 41 with three positions allows either of the primary gears 38, 40 to be coupled to the primary shaft 12, and provides a neutral position in which neither of the primary gears 38, 40 is coupled to the primary shaft 12. The various gears and primary, secondary, and intermediate shafts are housed within a cavity in a casing 24 of the transmission 18.

[0088] Secondary gears 42, 44, 46, coaxial with the secondary shaft 16, each also form a gear train with a corresponding gear 32, 34, 36, respectively, from among the intermediate gears, one of the gear trains being reversing and comprising an intermediate gear 48 to achieve a reverse gear ratio. The meshing of the gear trains formed by the secondary gears 42, 44, 46 and the corresponding intermediate gears 32, 34, 36 is permanent. A three-position dog clutch coupling without synchronizers 50, positioned between two of the secondary wheels 44, 46, allows either to couple to the secondary shaft 16 one or the other of the two associated secondary wheels 44, 46, or, in an intermediate neutral position, to keep the associated secondary gears 44, 46 decoupled from the secondary shaft 16.

[0089] In this embodiment, the axis of revolution 100 of the primary shaft 12 is aligned with the axis of revolution 200 of the secondary shaft 16, which allows the primary end gear 40 to be used alternately as a primary gear, associated with the primary shaft 12 by the synchronizer 41, or as a secondary gear associated with the secondary shaft 16. For this purpose, a three-position dog clutch 52 without synchronizers, positioned between the primary end gear 40 and the secondary gear 42, allows either the primary end gear 40 or the secondary gear 42 to be coupled to the secondary shaft 16, and also allows, in an intermediate neutral position, the primary end gear 40 and the secondary gear 42 to be kept decoupled from the secondary shaft 16.

[0090] A transmission gearbox 18 with six forward gears and potentially two reverse gears is thus established, which can, if necessary, be coupled at the output of the secondary shaft 16 to an epicyclic gear train (not illustrated) in order to obtain a twelve-speed gearbox.

[0091] Remarkably, the hybrid drive subassembly 10 is equipped with an electromotor unit 5 comprising a reversible electric machine 56, whose output shaft 57 rotates about an axis of revolution XI, and a coupling device 58, comprising in this example a three-position dog clutch mechanism 59 without a synchronizer and two gear reduction trains 60, 62, 64, 66, 68. In a connection position to the intermediate shaft 26, also called the coupling position In an intermediate position, the coupling device 58 performs a rotational coupling of the output shaft 57 with an intermediate speed reducer 260, which here comprises a gear 60 that permanently meshes with a gear 62 fixed to the intermediate shaft 26. In a secondary shaft coupling position, also called the secondary coupling position, the coupling device 58 performs a coupling of the output shaft 57 with a secondary speed reducer 264, which comprises a gear 64 that permanently meshes with a reversing gear 66, which itself permanently meshes with a gear 68 fixed to the secondary shaft 16. Finally, the coupling device 58, in a neutral position, keeps the output shaft 57 decoupled from the gears 60, 64.Within the coupling device 58, the transition from the intermediate coupling position to the secondary coupling position is achieved via the coupling mechanism 59, which is controlled by a control unit 76. For example, the coupling mechanism 59 is actuated by means of an actuating fork which axially moves the dog clutch along the transmission shaft 55.

[0092] Where applicable, the intermediate shaft 26 is equipped with a power take-off 98, intended to allow the coupling of one or more vehicle accessories, for example a winch, a pump, or a tool. The power take-off 98 may, for example, be a transmission shaft comprising an external connection interface, for example a spline.

[0093] The output shaft 57 illustrated in [Fig. 1] is integral with the rotor of the reversible electric machine 56 and constitutes a drive shaft. Alternatively, the reversible electric machine can incorporate a gearbox between the drive shaft and the output shaft 57. The output shaft 57 with axis of rotation XI drives a transmission shaft 55 via a first speed reducer Z1, Z2. The transmission shaft 55 supports the coupling device 58.

[0094] The reversible electric machine 56 is powered by a battery 70 via a bidirectional current converter, which allows the reversible electric machine 56 to be powered as a motor, and conversely, to rotate the reversible electric machine 56 as a generator to power the battery 70.

[0095] The reversible electric machine 56 is preferably a high-voltage machine, supplied for example at a nominal voltage between 300 Volts and 800 Volts, capable of delivering significant torque and power, as will be discussed later. The nominal voltage may be greater than 800 volts.

[0096] The control unit 76 allows the reversible electric machine 56 and its coupling device 58 to be controlled. Sensors 78, 80, 82 are connected to this control unit to measure the rotational speed of the output shaft 57, the intermediate shaft 26 and the secondary shaft 16 or the rotational speeds of elements permanently driven by these shafts. This control unit 76 can be integrated into a robotic control of the transmission 18 which controls the opening and closing of the synchronizers 41, the dog clutch mechanisms 50, 52, and where applicable the main clutch 20, to respond to a torque or speed command.

[0097] The hybrid subassembly 10 also includes a multi-disc shaft braking device 90 meshing with the transmission shaft 55 and arranged to brake the secondary shaft 16 when the coupling device 58 is in the secondary coupling position. The shaft braking device 90 comprises a multi-disc assembly 91. The multi-disc shaft braking device 90 is interposed, in the direction of torque flow, between the rotor of the reversible electric machine 56 and the coupling device 58.

[0098] As illustrated in Figures 2 and 3, the multi-disc shaft braking device 90 comprises a rotating disc carrier 92 meshing with the transmission shaft 55, a static disc carrier 93 arranged to be rotationally linked with a fixed part of the transmission, and a multi-disc assembly 91 consisting of a first set of discs meshing with splines of the rotating disc carrier, and a second set of discs meshing with splines of the static disc carrier. For example, the rotating disc carrier 92 of the shaft braking device 90 is rotationally linked by splines to the transmission shaft 55.

[0099] In this example, the shaft braking device 90 is indirectly connected to the output shaft 57 of the reversible electric machine by means of a speed reducer Z1, Z2, the rotating disc carrier 92 being rotationally fixed to the output pinion Z2 of the speed reducer. In this example, the dimensioning of the shaft braking device takes into account the reduction ratio associated with the speed reducer Z1, Z2. The risk of centrifugal force on the multi-disc assembly 91 of the shaft braking device 90 is limited due to the reduction in rotational speed.

[0100] In the example of implementation of the invention in [Fig.3], the multi-disc assembly of the shaft braking device 90 is axially pressed by an actuating piston 95 of annular shape, coaxial with the transmission shaft 55. The actuating piston 95 is axially guided within a pressure chamber 96 formed directly or indirectly in a protective housing of the electromotor unit 5.

[0101] Alternatively, the actuating piston 95 can be guided axially within a pressure chamber 96 formed directly or indirectly in the transmission housing 18.

[0102] The reversible electric machine 56 allows for several operating modes, such as pure regenerative braking or braking assistance. Each reversible electric machine has what is called a " Continuous power, which is the power it is capable of delivering over a long period of time, and maximum power (also known as peak power), which is the maximum power that cannot be exceeded. Advantageously, maximum power is only used for a very short time, on the order of a few seconds, to prevent excessive overheating and damage to the electrical machine's components. Under normal vehicle operating conditions, the power delivered by the electrical machine remains less than or equal to the corresponding rated power.

[0103] In pure regenerative braking mode or in braking assistance mode, the rotor of the electric machine is braked by an electromagnetic field. This resistive torque is obtained, for example, by reversing the direction of the stator phases in the case of alternating current machines (wound-rotor synchronous machine, magnetic synchronous machine, asynchronous machine).

[0104] As illustrated in [Fig. 4], the reversible electric machine 56 can be continuously braked up to a maximum continuous torque value permitted by the electric machine, corresponding to curve C3. Below this maximum continuous torque value C3 max, the electric machine can run for hours without reaching the thermal heating limit. However, the electric machine can be braked for a limited time beyond the maximum continuous torque value until a maximum resistive torque corresponding to curve Cl is reached. Beyond the maximum resistive torque Cl max, the reversible electric machine will malfunction due to the risk of overheating.

[0105] Fig. 4 also compares the resisting torque available within the reversible electric machine 56 with the resisting braking torque C2 of the shaft braking device 90. The torque capacity of the braking device 90 generally corresponds to 20%, for example 40%, for example 60% of the maximum continuous torque value C3 max allowed by the reversible electric machine.

[0106] Figure 6 illustrates a second embodiment of the invention, which differs of the first embodiment by the use of two reversible electric machines 56, each electric machine comprising a stator and a rotor having a movable output shaft rotating around an axis.

[0107] The reversible electrical machines 56 are of the same type and are, for example, permanent magnet synchronous machines. Each electrical machine provides the same rated mechanical power.

[0108] As can be seen in [Fig. 6], the first electric machine 56 in the described example has a rotor with a first output shaft 57 rotating about a first axis of rotation XI, and the second electric machine 56 has a rotor with a second output shaft 57 rotating about a second axis of rotation X2. In the described example, the axes of rotation of the reversible electric machines are parallel but not coincident, the two electrical machines 56 not having their axes of rotation aligned.

[0109] The output shafts 57 of the two electric machines simultaneously mesh with a common gear 110 arranged between axes XI, X2. The common gear 110 is kinematically linked to the two output shafts and receives the motor torque supplied by the two electric machines, which are distributed around the common gear 110 so as to form a first speed reducer Z1, Z2. The common gear 110 is kinematically linked to a transmission shaft 55 specific to the coupling device 58 of this second embodiment of the invention by means of a second speed reducer Z3, Z4. This second speed reducer Z3, Z4 is optional so that it is possible to connect the common gear directly to the transmission shaft 55.

[0110] Similar to the first embodiment, the coupling device 58 comprises a three-position dog clutch mechanism 59 without a synchronizer and two gear reduction trains 60, 62, 64, 66, 68. In a connection position to the intermediate shaft 26, also called the intermediate coupling position, the coupling device 58 achieves a rotational coupling of the transmission shaft 55 with a so-called intermediate speed reducer 260 comprising here a gear 60 which permanently meshes with a gear 62 fixed to the intermediate shaft 26.In a secondary shaft connection position, also called secondary coupling position, the coupling device 58 performs a coupling of the transmission shaft 55 with a speed reducer called secondary 264, comprising a toothed wheel 64 which permanently meshes with a reversing toothed wheel 66 which itself permanently meshes with a toothed wheel 68 fixed to the secondary shaft 16. .

[0111] The hybrid subassembly 10 also includes a multi-disc shaft braking device 90 meshing with the output shafts 57 of the two electric machines via the common gear 110 and arranged to brake the secondary shaft 16 when the coupling device 58 is in the secondary coupling position. The shaft braking device 90 comprises a multi-disc assembly 91. The multi-disc shaft braking device 90 is interposed, in the direction of torque flow, between the rotor of the reversible electric machine 56 and the coupling device 58.

[0112] As illustrated in [Fig. 6], the multi-disc shaft braking device 90 comprises a rotating disc carrier 92 arranged to be rotationally linked with the common gear 110 with axis of rotation 111, a static disc carrier 93 arranged to be rotationally linked with a fixed part of the transmission, and a multi-disc assembly 91 consisting of a first set of discs engaging with splines of the a rotating disc carrier, and a second set of discs engaging with splines of the static disc carrier. For example, the rotating disc carrier 92 of the shaft braking device 90 is rotationally connected by splines to the common gear 110.

[0113] The various embodiments described have in common a coupling device 58 capable of assuming at least a first coupling position in which the reversible electric machine 56 is kinematically connected to the intermediate shaft, and a second coupling position in which the reversible electric machine 56 is kinematically connected to the secondary shaft 16 without passing through the intermediate shaft 26. These various couplings can be used to achieve a wide variety of operating modes, as will now be discussed.

[0114] First, several modes of operation can be implemented while the coupling device 58 connects the output shaft 57 to the secondary shaft 16 without intervention of the intermediate shaft 26.

[0115] A braking assistance mode without intervention of the intermediate shaft 26 can be envisaged, in which the coupling device 58 is positioned in the second coupling position, the secondary shaft 16 is disengaged from the intermediate shaft 26 by acting on the dog clutch mechanisms 50, 52, and simultaneously electrical energy is generated by the reversible electric machine 56 operating as a generator and the shaft braking device 90 is actuated, which then applies a resisting braking torque C2 to the transmission shaft 55 via the pressurized multi-disc assembly 91. This braking assistance mode can be advantageous when the vehicle is on a gentle slope and the driver does not want to use the main braking system.In this braking assistance mode, the braking capacity of the multi-disc type shaft braking device 90 can be between 20% and 60% of the braking capacity of the reversible electric machine 56.

[0116] A braking assistance mode without intervention of the intermediate shaft 26 is particularly effective when the following successive steps are applied:

[0117] - the coupling device 58 is positioned in the second position mating;

[0118] - then, over a first time interval 11, a first resistive torque is generated Cl to brake the secondary shaft 16 with the reversible electric machine 56 operating as a generator in a torque range exceeding the maximum continuous torque value permissible by the electric machine;

[0119] - then, over a second time interval i2, a second couple is generated braking resistor C2 via the shaft braking device 90 simultaneously with a third resisting torque C3 with the reversible electric machine 56 operating as a generator in a torque range lower than the torque value Maximum continuous c3 max permissible by the electrical machine.

[0120] This braking assistance mode is particularly advantageous for braking the vehicle when the vehicle starts a descent and the driver wants to limit the use of the vehicle's mechanical braking system as much as possible.

[0121] When the battery 70 is fully recharged, it is no longer possible to use the reversible electric machine; the following step is then applied:

[0122] - on a third time interval i3, only the second couple is generated resistant C2 via the shaft braking device 90 without intervention of the reversible electric machine.

[0123] Figure 5 illustrates the behavior of the electric machine(s) 56 and the shaft braking device 90 of the hybrid subassembly and the vehicle, as well as the evolution of the vehicle speed V as a function of time t during this braking assistance mode without intervention of the intermediate shaft 26. In this figure, curve 5a illustrates the vehicle speed V, curve 5b illustrates the level of resisting torque within the electric machine 56 and curve 5c illustrates the level of resisting braking torque within the braking device 90.

[0124] Furthermore, in this [Fig. 5], a first phase illustrates the downhill rolling of the vehicle between times t0 and t1, during which the vehicle's speed increases. Between t1 and t2, the coupling device 58 is positioned in the second coupling position and the reversible electric machine is switched to generator operation.

[0125] Between t2 and t3, which corresponds to the first time interval 11, a first resistive torque 11 is generated to brake the secondary shaft 16 with the reversible electric machine 56 operating as a generator in a torque range exceeding the maximum continuous torque value permissible by the electric machine. The vehicle speed 5 drops sharply.

[0126] Beyond a limited time, for example 30 seconds, it is necessary, between t3 and t4, to reduce the resisting torque inside the electrical machine at the risk of damaging it.

[0127] Between t4 and t5, the shaft braking device 90 is started to be actuated by increasing the control pressure within the pressure chamber 96.

[0128] Between t5 and t6, corresponding to the first time interval i2, a second braking torque C2 is generated by the shaft braking device 90 simultaneously with a third braking torque C3 using the reversible electric machine 56 operating as a generator in a torque range below the maximum continuous torque allowed by the electric machine. During this time interval i2, the cumulative braking torque corresponds to the sum C2 + C3. The vehicle speed V continues to decrease.

[0129] Between t6 and t7, the electric machine is switched off since battery 70 is fully recharged.

[0130] Between t7 and t8, which corresponds to the first time interval i3, only the second resisting torque C2 is generated on the transmission shaft 55 to brake the secondary shaft 16 via the shaft braking device 90 without intervention of the reversible electric machine.

[0131] Between t8 and t9, the control pressure is released within the pressure chamber 96. The vehicle has reached a low speed V.

[0132] This braking method can also be used when the vehicle is traveling on a flat road and the driver wants to stop the vehicle at a traffic light by limiting the use of the vehicle's mechanical braking system as much as possible.

[0133] A pure regenerative braking mode without the intermediate shaft 26 can also be envisaged, in which the coupling device is positioned in the second secondary coupling position, the secondary shaft 16 is uncoupled from the intermediate shaft 26 by acting on the dog clutch mechanisms 50, 52 and electrical energy is generated with the reversible electric machine 56 operating as a generator. To optimally achieve this regenerative braking mode without the main motor, it is advantageous that the reversible electric machine be able to develop a resisting torque greater than 400 Nm and preferably greater than 450 Nm in a speed range of more than 3000 rpm, and preferably more than 4000 rpm with a lower limit which is less than 6500 rpm, and preferably less than 6000 rpm and an upper limit which is greater than 9000 rpm, and preferably greater than 10000 rpm, for at least 30 seconds.

[0134] Particularly advantageously, other modes of operation can be envisaged while the coupling device 58 connects the output shaft 57 to the secondary shaft 16.

[0135] A transient mode of maintaining traction during a gear change can thus be implemented, in which the coupling device 58 is positioned in the second coupling position, the main motor 14 is uncoupled from the intermediate shaft 26, and the reversible electric machine 56 is controlled so as to generate a motor torque on the secondary shaft 16 or to minimize a speed variation of the secondary shaft while a gear change of the transmission 18 is controlled between the main motor 14 and the intermediate shaft 26 and / or between the intermediate shaft 26 and the secondary shaft 16.

[0136] The transient traction maintenance mode during a gear change and the pure regenerative braking mode without the intermediate shaft 26 are transient operating modes, not intended to last more than about thirty seconds. A As an indicative title, with a transmission ratio of the order of 8 between the output shaft 57 and the secondary shaft 16, it is advantageous to size the reversible electric machine to develop a resisting torque greater than 400 Nm and preferably greater than 450 Nm in a speed range of more than 3000 rpm, and preferably more than 4000 rpm having a lower limit which is less than 6500 rpm, and preferably less than 6000 rpm and an upper limit which is greater than 9000 rpm, and preferably greater than 10000 rpm, for 30 seconds.

[0137] A direct electric drive mode can be implemented without the intermediate shaft 26, in which the coupling device 58 is positioned in the second coupling position and the intermediate shaft 26 is uncoupled from the secondary shaft 16 at the dog clutch mechanisms 50, 52, the reversible electric machine acting in a driving or regenerative manner according to the acceleration or braking requirements.

[0138] The reversible electric machine 56 can also be used as a motor to drive the power take-off 98 while the transmission 18 is in the neutral position to interrupt the connection between the intermediate shaft 26 and the primary shaft 12 on the one hand, and between the intermediate shaft 26 and the secondary shaft 16 on the other hand.

Claims

Demands

1. A braking method for a vehicle comprising a hybrid drive sub-assembly (10) which includes: • at least one primary tree (12); • at least one secondary tree (16); • a transmission box (18) comprising at least one intermediate shaft (26) separate from the primary shaft (12) and the secondary shaft (16) and gear trains (38, 28, 40, 30, 32, 42, 36, 48, 44, 46) to achieve several transmission ratios between the primary shaft (12) and the secondary shaft (16) via the intermediate shaft (26); • an electromotor set (5) comprising at least one reversible electric machine (56), and a coupling device (58) which, in a first coupling position, kinematically links the output shaft (57) of the reversible electric machine (56) to the intermediate shaft (26) and in a second coupling position, kinematically links the output shaft (57) of the reversible electric machine (56) to the secondary shaft (16) without passing through the intermediate shaft (26); • a multi-disc type shaft braking device (90) kinematically linked with the output shaft (57) to brake the secondary shaft (16) when the coupling device is in the second coupling position; The braking process involves the following successive stages: - position the coupling device (58) in the second coupling position; - then, over a first time interval (il), generate a first resistive torque (Cl) to brake the secondary shaft (16) with the reversible electric machine (56) operating as a generator in a torque range exceeding the maximum continuous torque value (C3 max) admissible by the electric machine; - then, over a second time interval (i2), generate a second resistive braking torque (C2) via the shaft braking device (90) simultaneously with a third resistive torque (C3) with the reversible electric machine (56) operating as a generator in a torque range below the maximum continuous torque value (C3 max) permissible by the electric machine.

2. Braking method according to the preceding claim, wherein the second time interval (i2) is greater than the first time interval (il).

3. Braking method according to any one of the preceding claims, wherein the second resisting torque (C2) is less than the third resisting torque (C3).

4. A braking method according to any one of the preceding claims, having the following successive step: - then, over a third time interval (i3), generate only the second resisting braking torque (C2) via the shaft braking device (90) without intervention of the reversible electric machine.

5. A braking method according to any one of the preceding claims, wherein the multi-disc shaft braking device (90) comprises a rotating disc carrier (92) arranged to be rotationally linked with a transmission shaft (55) of the electric motor unit (5), a static disc carrier (93) arranged to be rotationally linked with a fixed part of the transmission box (18) and a multi-disc assembly (91) consisting of a first set of discs (91a) engaging with splines of the rotating disc carrier, and a second set of discs (91b) engaging with splines of the static disc carrier, the shaft braking device (90) being indirectly engaged with the output shaft (57) of the reversible electric machine by means of a speed reducer (Z1, Z2), the rotating disc carrier (92) being rotationally fixed to the output pinion (Z2) of the speed reducer.

6. Braking method according to the preceding claim, wherein the multi-disc assembly of the shaft braking device (90) is axially pressed by an actuating piston (95) of annular shape, the actuating piston (95) being axially guided within a pressure chamber (96) formed directly or indirectly in a protective housing of the electromotor unit (5).

7. A braking method according to any one of claims 5 or 6, wherein the rotating disc carrier (92) of the shaft braking device (90) is rotationally linked by a spline (94) with the drive shaft (55) of the electric motor unit (5) located at the axis of revolution of the shaft. output (57) or rigidly fixed on the transmission shaft (55) of the electromotor unit (5) distant from the axis of revolution of the output shaft (57) by means of fixing screws, rivets or by welding.

8. Braking method according to any one of the preceding claims, wherein the coupling device (58) comprises one or more of the following coupling mechanisms: - a dog clutch mechanism (59, 159), - a clutch mechanism (259, 359), preferably a friction clutch mechanism, preferably wet, - a double friction clutch (259), preferably wet.

9. A braking method according to any one of the preceding claims, wherein the output shaft (57) of the reversible electric machine (56) has an axis of revolution (XI) parallel to an axis of revolution of the intermediate shaft (26), one or more of the following features being preferably realized: - the axis of revolution of the output shaft (57) coincides with the axis of revolution of the intermediate shaft (26); - the axis of revolution of the output shaft (57) is distant from the axis of revolution of the intermediate shaft (26); - the axis of revolution of the output shaft (57) is distant from one axis of revolution (100) of the primary shaft (12); - the axis of revolution of the output shaft (57) is distant from one axis of revolution of the secondary shaft (16).

10. A braking method according to any one of the preceding claims, wherein the electromotor group (5) comprises two reversible electric machines (56), each comprising a rotor with an output shaft (57) rotating about an axis of rotation (XI, X2), the two output shafts (57) simultaneously engaging with a common toothed wheel (110) arranged parallel to the two axes of rotation (XI, X2), the shaft braking device (90) being indirectly engaged with the output shafts (57) by braking the associated common toothed wheel (110).

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