FR2913225A1 - Speed ratio changing method for e.g. hybrid vehicle, involves controlling electrical machine for inducing torque on main shaft to produce rotation in direction same as that of vector resulting from natural torque of main shaft - Google Patents

Abstract

The method involves connecting a sleeve to a secondary shaft (11) meshed in receiver jaw clutches that are connected to a main shaft (8) in a turning phase, where the clutches have a beveled tooth comprising tooth sectors respectively form angles. An electrical machine (12) is controlled by a control unit (20) for inducing torque on the main shaft to produce rotation in a direction same as that of a vector resulting from natural drag torque of the main shaft. A steering wheel (10) is driven by the secondary shaft. An independent claim is also included for a gear box for a vehicle.

Description

Gearshift method in a gearbox equipping a

  The present invention relates to a method of shifting gear in a gearbox. It also relates to a gearbox, in particular for a hybrid vehicle. More generally, it applies to vehicles equipped with an electric machine.

  Currently, some hybrid vehicles use one or more electrical machines involved in the traction of the vehicle and a gearbox driven to transmit a determined torque to the drive wheels of the vehicle. A gearbox provides multiple gear ratios between the engine and the wheels. The traction chain therefore comprises a gearshift mechanism that allows either to obtain a significant torque at the drive wheels, or to achieve the maximum speed. Then there is the problem of making gear changes as imperceptible as possible. More particularly, there is the problem of being as free as possible from the inertia of the electric machine placed in series with the heat engine on the power train, at the time of gear changes, that is to say changes in the context of a hybrid vehicle.

  Thus, to ensure a gear shift in the best conditions, the invention is intended in particular to reduce the time of passage of reports and limit the mechanical forces preventing the fluidity of the passage of reports.

  For this purpose, the subject of the invention is a method of shifting gear in a gearbox fitted to a vehicle driven by a power train comprising at least one electric machine capable of driving a primary shaft, the electric machine being mechanically secured to the primary shaft, a driving wheel being driven by a secondary shaft mechanically coupled to the primary shaft via the gearbox, said method comprising a phase of unwinding followed by a phase of interconnection in which a sleeve connected to a secondary shaft engages in receptor claws connected to the shaft, said claws having a beveled tooth of which at least a first tooth sector forms a first angle with the axis of the sleeve and a second tooth sector forms a second angle with the axis of the lower sleeve at the first angle. Advantageously, at least in the interconnection phase the electric machine is controlled to induce on the primary shaft a torque producing a rotation in the same direction as the vector resulting from the natural drag torque of the primary shaft.

  Advantageously, the value of the drag torque induced by the electric machine is determined as a function of the speed of the primary shaft and the speed of the secondary shaft. Advantageously, the sum of the values of the drag torque induced by the electric machine and the natural drag torque of the primary shaft is constant. Advantageously, the gearbox according to the invention equipping a vehicle driven by a traction chain comprises at least one electric machine driving a primary shaft, the electric machine being mechanically secured to the primary shaft, a driving wheel being driven by a secondary shaft, mechanically coupled via the gearbox to the primary shaft means for synchronizing primary and secondary shafts capable of implementing a phase of unwinding followed by a phase of interconnection, said synchronization means comprising a sleeve connected to the secondary shaft meshing with receptor clutches connected to the other shaft, said claws having a beveled head of which at least a first tooth sector forms a first angle with the axis of the sleeve and a second sector of teeth forms a second angle with the axis of the lower sleeve at the first angle. Advantageously, the box comprises a control unit which, at least in the jaw clutching phase, controls the electric machine to induce on the primary shaft a torque producing a rotation in the same direction as the vector resulting from the natural drag torque of the primary tree.

  Other features and advantages of the invention will become apparent from the following description made with reference to the accompanying drawings which show: FIG. 1, a block diagram of an example of a traction chain of a hybrid vehicle ; Figure 2, the position of the sleeve at the beginning of the phase of interconnection; Figure 3, the position of the sleeve at the end of the phase of interconnection; Figure 4, a sectional view of the sleeve meshing in a jaw clutch; Figure 5, a top view of the sleeve meshing in a jaw clutch; • Figure 6, the contact between the sleeve and a symmetrical tooth clutch of the dog clutch; • Figure 7, the contact between the sleeve and an asymmetric tooth clutch of the dog clutch;

  Figure 1 shows a block diagram of an exemplary traction chain of a hybrid vehicle. It comprises a heat engine 1 coupled for example to an electric auxiliary machine 2, by means of a belt 3 driven by pulleys 3 ', 3 "secured to one of the engine and the other of the auxiliary machine, this auxiliary machine allowing restarting the engine in a so-called stop and go mode, which does not participate directly in the traction of the vehicle.

  An flywheel 4 is fixed on the output shaft 5 of the heat engine 1. The output shaft is on its side coupled to the crankshaft of the engine. The output shaft is then connected to the clutch 6. The latter 30 makes a sliding movement 7 in the direction of the output shaft to move from an open position to a closed position or vice versa. The clutch is also connected to the primary shaft 8. This primary shaft 8 connects the motor output shaft 5 to a controlled mechanical gearbox 9, when the clutch is in the closed position. This mechanical gearbox transmits the driving power to the wheels 10, only one of which is shown in FIG. 1. More particularly, the gearbox 9 transmits, after reduction, the power output to the wheels 10 by the intermediate of an output shaft 11, or secondary shaft, coupled to a transmission shaft not shown.

  In the example described, an electric traction machine 12 is inserted in series between the clutch 6 and the driven mechanical gearbox 9. This electric traction machine 11 comprises a rotor 13 and a stator 14. The rotor 13 is integral with the primary shaft 8 and the stator 14, fixed, is for example integral with the motor housing. A battery 15 or a set of batteries, of high power, supplies electrical energy to the traction machine 12 via an inverter 16. This latter makes it possible to transform the DC voltage at the battery output into an alternating voltage suitable for driving the rotor 13 in rotation. .

  A control unit 20 associated with sensors, not shown, controls the traction chain associated with the wheel 10. The control unit controls in particular the electric machine 12. The sensors make it possible in particular to measure the different speeds of rotation involved in the traction chain. With such a traction chain architecture, the vehicle can in particular operate according to the following modes: the vehicle is traveling in pure thermal mode when the clutch 6 is closed and the electric traction machine 12 is not powered or controlled, the heat engine 1 ensuring only traction; • the vehicle is running in pure electric mode when the clutch 6 is open and the electric machine 12 is powered or controlled to ensure only the traction of the vehicle; the vehicle is traveling in mixed mode when the engine 1 ensures the traction of the vehicle assisted by the electric machine 12, the clutch 6 being closed.

  The electric machine 12 arranged in series on the primary shaft 8 35 of the gearbox 9 imposes a significant constraint. Indeed, the constraint of the electric machine 12 is its significant inertia. This additional inertia is equivalent, for example, to add a dozen clutches. Therefore, to mesh the gears during a phase of interlocking in particular, it is necessary to provide very significant efforts compared to a conventional architecture. This extra effort can lead to performance losses, such as the impossibility of gear shifts or too long passage times from one gear to the other.

  The invention makes it possible to optimize gear shifting by reducing the aforementioned performance losses, despite the considerable inertia of the electric machine 12.

  FIG. 2 illustrates, in a flat view, a synchronization device, or synchronizer, arranged on a secondary shaft section supporting in order, from left to right: a 2nd idle gear, a 2nde synchronization ring , a sleeve 27 connected to a synchronizing cocking device 22, a second synchronization ring of 1 era and a crazy pinion 1 era 2nd and 1st idle gears are also designated by the term idle gear. According to the representation of Figure 2, the sleeve 27 moves in a translational direction 25 ', that is to say to the right in the figure, between the synchronization ring of lère and coming into contact with the jaw 28' of the clutching ring 21 of the idler gear 1 è 'to engage the ratio of lé'. The clutching ring 21 rotates around the secondary shaft 11 in a direction of rotation 29. The synchronization ring of 1st 23 makes it possible to approach the phase of interconnection between the sleeve 27 and the claws 28 'of the clutching crown. During a engagement of a report, the sleeve 27 fits into the claws 28 'of the clutch crown 21 and can come into random contact with one of the jaw 28'. In the latter case, given the geometry of the tooth of the dog 28 ', a component 26 of the force resulting from the force applied by the sleeve 27 on the clutch 28' is oriented for example in the direction of rotation 29 of the clutch crown 21.

  FIG. 3 shows the sleeve 27 between two dogs 28 'of the dog clutch ring 21. The component 26 of the application force of the sleeve on the clutch engages a rotation of the clutch crown with respect to the sleeve 27 in the direction of rotation 29. The thrust applied to the sleeve 27 during a gear change enables said sleeve 27 to fit into the free space between two claws 28 '. The speeds of the sleeve 27 and gear ratio engaged are then equalized with the game. The ratio engaged in the example illustrated by the figure is the ratio of 10 lère Figure 4 illustrates the various parts involved by a synchronizer of the gearbox 9 during a phase of interconnection. The interconnection phase follows a phase of free flight and a phase of 15 devolution synchronization. The unwinding is the phase during which a synchronizing ring is unlocked after equalization of the speeds between the primary shaft 8 and the secondary shaft 11, the latter being not shown in the figure.

  The sleeve 27 cooperates with the synchronizing ring 23 having a substantially conical inner diameter, this ring being further referred to as the unwinding ring. The sleeve 27 is fixed on a hub 43 connected to the secondary shaft 11. The translational movement of the sleeve 27 on the hub 43 is produced by a not shown actuator, via a fork 25 located in the gearbox, also not shown .

  The synchronizing ring 23 has a contact surface 46 on its conical inner surface which makes it possible to transmit by friction or friction a torque between the ring 23 and the idler gear of 1 to 45 during the application of the force of the sleeve 27 on the teeth of the synchronizing ring 23. This idler gear 45 is then secured in rotation with the secondary shaft 11 when the sleeve 27 is fully engaged in the teeth of the clutch crown of the idler gear 45 of 1 e . Following this interconnection, the engagement of the idler pinion 1 45 of the secondary shaft 11 35 with the pinion of the latter, not shown, of the primary shaft, the latter is also not shown , can transmit the torque from the engine to the wheels with the desired gear ratio. The synchronizing ring 23 plays a buffer groove in that it allows the sleeve 27 to apply a torque related to the speed differential between the primary shafts 8 and 11 secondary. Indeed, when changing gear, it is provided to readjust the speed of rotation of the primary shaft 8 and secondary 11 to a compatible level of the speed of the wheel 10, driven by the secondary shaft, when the power train will use the ratio that is planned to select. This is the synchronization operation. During this synchronization the difference in speed between the primary shaft and the secondary shaft creates a torque that opposes the advance of the sleeve, this torque is called synchronization torque. The axial force produced by the sleeve, also called the driving force, creates a torque that tends to rotate the synchronizing ring 23 to release the passage of the sleeve. This torque, called deviating torque, is related to the geometry of the teeth of the sleeve and the ring.

  The free flight phase corresponds to the displacement of the sleeve 20 without any significant effort before it encounters the jaws of the idler gear 45. During a gearshift, is provided to readjust the speed of rotation of the primary shaft 8 at a compatible level of the speed of the wheel 10, driven by the secondary shaft, when the traction chain 25 will use the ratio that is considered to select.

  The interconnection phase corresponds to the joining of the sleeve 27 and the idler gear 45 to connect the primary shaft 8 to the wheel 10 of the vehicle before re-clutching or torque transfer by the electric machine 12. FIG. top view of the sleeve 27 and the synchronizing ring 23. The sleeve 27 meshes with the jaws of the jaw clutch 40. FIG. 6 illustrates the case where the sleeve 61 comes into contact with a dog tooth 60 of the interconnection crown. The dog tooth 60 of the interconnection ring is bevelled and forms substantially two symmetrical sections.

  A first angle 65 defines a first orientation of a first section of the dog tooth of the jaw clutch crown with the axis 68 of the dog clutch of the clutch crown and a second angle 64 defines a second orientation of the second section with the clutch. axle 68 of the dog of the 0 10 crown of interconnection. During the interconnection phase, the teeth of the sleeve and the claws come into contact creating a force resulting from the applied force, a component 62 of which, along the axis 68 of the pinion, opposes the gearing of the gears and a component 63 perpendicular to the axis 68 of the clutch 15 generates a rotational movement of the jaw clutch ring in a direction depending on the contact section of the dog tooth of the jaw clutch crown. The rotation is in the same direction as the component 63 perpendicular to the axis 68 of the clutch. A resultant torque is thus created by the thrust of the sleeve coming into contact with the dog tooth 20 of the clutching crown. According to the contact section of the teeth of the clutch of the dog clutch crowns with those of the sleeve, the torque generated by the thrust of the sleeve, called the clutch torque, can either generate a couple of forces in the same direction as the drag torque of the primary tree, to oppose it. In the example of FIG. 6, the drag torque 67 generated by the electric machine MEL then opposes the interlocking torque 66 induced by the contact between the sleeve and the interconnection ring.

  FIG. 7 represents the case of a tooth 70 of a clutch of the clutching crown whose head is canted asymmetrically. A first section F1 forms a first angle 64 'with the axis 68 of the clutch and a second section F2, larger than the previous section, forms an angle 65' with the axis 68 of the clutch.

  The invention proposes to control, by means of the MEL, a drag torque on the primary shaft, during contact of the teeth of the sleeve and the interconnection ring, generated in the same direction as the natural drag torque of the primary tree.

  Electromechanical sensors placed in the gearbox make it possible to measure the force of the actuator and to slave the MEL by a setpoint. The MEL is able to provide a torque of effort to the primary shaft in a preferred direction of rotation.

  Two cases arise, then: If the teeth of the sleeve come into contact on the sidewalls F1, the drag torque 67 generated by the MEL comes to oppose the clutch torque 66, induced by the contact between the sleeve and the dog. The first angle 64 'being small, the torque of interconnection is high. The interconnection is achieved more easily than in the case of a symmetrical head tooth, despite the drag torque 67 which opposes the displacement. The force to be provided by the sleeve is less important than in the case where the jaw teeth are symmetrical. If the teeth of the sleeve come into contact on the flanks F2, the torque of clutch 66, low since the second angle 65 'is large, and the drag torque 67 are in the same direction. The interconnection is then facilitated compared to the case of use of symmetrical jaw teeth.

  The invention makes it possible to associate jaw teeth of the jaw clutch whose beveled head comprises asymmetrical sections with an MEL control of an instruction generating a couple of forces on the primary shaft in the same direction as the natural trail couple.

  When the MEL is driven so as to create a drag torque to the primary shaft in the same direction as the natural drag torque, the interconnection is facilitated by the asymmetrical architecture of the teeth of the jaw whatever the section of the tooth of clutch in contact with sleeve.

  In one embodiment, the value of the drag torque on the primary shaft induced by the MEL is advantageously calculated as a function of the speed differential of the primary and secondary shafts. The induced drag torque on the primary shaft is thus calculated according to the engaged ratio.

  Advantageously, the overall drag torque of the primary shaft including the natural drag torque of the shaft, the latter being dependent on the engaged ratios, and the drag torque induced by the MEL may be constant in one embodiment.

  In the example of an architecture comprising symmetrical claws, in a configuration where the drag torque of the primary shaft has not been modified by the control of the MEL, for different angles of possible clutching, a calculation for example of the average interconnection impulse is 17.17 Ns with a standard deviation of 16.53 Ns These values are related to the drag torque of the primary shaft which changes as a function of the passage of a ratio. On the other hand, for an architecture of asymmetrical claws and a global drag torque of the primary shaft of the order of 1 Nm following the generation of a drag torque of the MEL on the primary shaft, for different angles of possible interconnection, an exemplary calculation of the average interconnection impulse is 12.11 Ns with a standard deviation of 11.64 Ns These values are substantially identical for all gear changes with identical MEL control with the same drag torque.

  The asymmetrical architecture of the claw teeth combined with the generation of a drag torque by the control of the MEL facilitates the interconnection for all gear changes. In the preceding examples, the average pulse of interconnection is reduced by 40%.

  The invention has the main advantage of reducing the effort of interconnection and reduce the time of interconnection. In addition, the reliability is increased because the resistance force opposing the actuator is reduced, the wear of the mechanical parts is reduced,

Claims (2)

  1. A gear change method in a gearbox (9) fitted to a vehicle driven by a traction chain (8, 12, 9, 11) comprising at least one electric machine (12) adapted to drive a primary shaft (8). ), the electric machine (12) being mechanically secured to the primary shaft (8), a driving wheel (10) being driven by a secondary shaft (11) mechanically coupled to the primary shaft via the gearbox, said method comprising a phase of unwinding followed by a phase of interconnection in which a sleeve (21) connected to a secondary shaft (11) meshes with receiver claws (41) connected to the shaft (8), said jaws comprising 15 a beveled tooth of which at least a first tooth sector forms a first angle with the axis of the sleeve and a second tooth sector forms a second angle with the axis of the sleeve below the first angle, characterized in that at least in the phase of interconnection the electric machine (12) is controlled to induce on the primary shaft (8) a torque producing rotation in the same direction as the resultant vector of the natural drag torque of the primary shaft (8).   2. Method according to claim 1, characterized in that the value of the drag torque induced by the electric machine (12) is determined as a function of the speed of the primary shaft (8) and the speed of the shaft. secondary (11). Method according to claim 1 or 2, characterized in that the sum of the values of the drag torque induced by the electric machine (12) and the natural drag torque of the primary shaft (8) is constant. 4. Transmission (9) fitted to a vehicle driven by a traction chain (8, 12, 9, 11) comprising at least one electric machine (12) driving a primary shaft (8). the electric machine (12) being mechanically integral with the primary shaft (8), a driving wheel (10) being driven by a secondary shaft (11), mechanically coupled via the gearbox to the primary shaft (8) a means synchronization of the primary and secondary shafts capable of implementing a phase of unwinding followed by a phase of interconnection, said synchronization means comprising a sleeve (21) connected to the secondary shaft (11) meshing in receiver claws (41). ) connected to the other shaft (8), said claws having a beveled head of which at least a first tooth sector forms a first angle with the axis of the sleeve and a second tooth sector forms a second angle with the axis of the sleeve lower than the first angle, characterized in that said box comprises a control unit which, at least in the dog clutch phase controls the electric machine (12) to induce on the primary shaft (8) a torque producing a rotation of the samemeaning that the resulting vector of the natural drag torque of the primary shaft (8). 5. Transmission (9) according to claim 4, characterized in that the value of the drag torque induced by the electric machine (12) is determined as a function of the speed of the primary shaft (8) and the speed of the secondary shaft (11). Gearbox (9) according to claim 4 or 5, characterized in that the sum of the values of the drag torque induced by the electric machine (12) and the natural drag torque of the primary shaft (8) is constant.