Method for controlling a synchronizing device of a controlled gearbox of a motor vehicle

Abstract

The invention relates to a method for controlling a synchronizing device of a controlled gearbox (8,9) of a motor vehicle, the control method comprising: - a step measuring the difference in speeds to be synchronized between a rotational speed of a synchronizing ring of the synchronizing device and a rotational speed of a gear to be synchronized; - a step of bringing the synchronizing ring and the gear to be synchronized into alignment; - a synchronization step by applying an increasing synchronizing force to the synchronizing ring in order to create a synchronizing torque, the synchronizing force being applied according to a predetermined coefficient of increase in synchronizing force prior to the synchronization step and which depends on the use of the motor vehicle; - a step of engaging a new gear ratio. Figure 1

Description

Title of the invention: Method for controlling a synchronization device of a controlled gearbox of a motor vehicle

[0001] The technical context of the present invention is that of controlled gearboxes for motor vehicles. More particularly, the invention relates to a method for controlling a synchronization device of a controlled gearbox of a motor vehicle.

[0002] In a known manner, manually operated gearboxes for motor vehicles comprise a first shaft connected to the engine by a clutch, and a second parallel shaft connected to the drive wheels of the motor vehicle. These shafts can be connected to each other by pairs of pinions transmitting the movement from one to the other according to different gear ratios, to produce transmission ratios. One of the pinions of each pair is secured to one of the shafts, the other pinion of the pair is mounted to rotate freely on the other shaft, and can be made secured to its shaft by the axial sliding of a synchronizing sleeve.

[0003] In a known manner, this axial sliding firstly achieves a synchronization of the speeds of the two elements by a synchronization device comprising friction cones, then a dog clutch of the pinion on the shaft. The movement of the synchronization sleeve thus comprises:

[0004] - a neutral center position of dead center where no gear is engaged, and

[0005] - one or two axially offset positions on either side, for the engagement of the free gears.

[0006] Document FR-A1-2837889 is also known, which describes such a gearbox for a hybrid-type motor vehicle. This motor vehicle comprises a rotating electrical machine arranged between the thermal engine and the gearbox. The rotating electrical machine performs various functions such as, for example, starting the thermal engine, recovering energy during braking, or providing additional engine torque.

[0007] A known drawback of these architectures lies in the fact that the primary shaft supporting a rotor of the rotating electrical machine has a significant moment of inertia, leading to the need to provide significant work to synchronize the speeds during gear changes.

[0008] Another known disadvantage is that if the synchronization control during preselection of the next gear is not optimal, then the Changing gears can cause shocks that can lead to premature wear and unwanted noise in the gearbox.

[0009] The object of the present invention is to propose a new method for controlling a synchronization device of a controlled gearbox in order to respond at least to a large extent to the preceding problems and to also lead to other advantages.

[0010] Another aim of the invention is to reduce the noise perceived by the user of a motor vehicle equipped with such a controlled gearbox.

[0011] Another aim of the invention is to allow better adaptability of the gearbox, while guaranteeing optimal operation each time.

[0012] According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a method for controlling a synchronization device comprising a sleeve implementing a first friction cone belonging to a synchronization ring arranged between the sleeve and a pinion to be synchronized, and a second friction cone belonging to the pinion and arranged opposite the first friction cone, to effect a gear ratio change on a controlled gearbox of a motor vehicle comprising an electrical machine linked to the primary shaft of the gearbox, the sleeve being moved axially by an actuator controlled by a computer which successively performs:

[0013] - a step measuring the difference in speeds to be synchronized;

[0014] - a step of approaching the friction cones;

[0015] - a synchronization step by applying a synchronization effort increasing on the first and second cones to create a synchronization torque, the synchronization force being applied, with increasing intensity, until the speed difference becomes lower than a predetermined high threshold;

[0016] - a step of dog-engaging a new gear ratio.

[0017] In the control method according to the first aspect of the invention, the computer carries out, prior to the synchronization step, a step of determining a coefficient of increase in synchronization force used, during the synchronization step, to reach the synchronization force - called saturated - between the first and second cones.

[0018] In the context of the present invention, the synchronization force increase coefficient corresponds to the slope according to which the axial force is applied to the first and second cones of the synchronization device. In other words, the synchronization force increase coefficient corresponds to the temporal variation of the axial force applied to the first and second cones during the synchronization step.

[0019] In the context of the present invention, the saturated synchronization force is the synchronization force which makes it possible to establish synchronization between the first and second cones, making possible synchronization of the pinions allowing the passage of the new speed ratio, during the successive dog clutch step.

[0020] In the context of the present invention, the step of determining the coefficient of increase in synchronization force comprises a step of preselecting a predetermined value of the coefficient of increase in synchronization force, by means of one or more values ​​stored in memory or available on an on-board network of the motor vehicle.

[0021] Thus, the control method according to the first aspect of the invention makes it possible to control the gearbox by controlling the synchronization step according to the needs of the motor vehicle and its driver. In other words, the control method according to the invention makes it possible to control a synchronization duration by controlling functional parameters of the synchronization device, and more particularly its synchronization force increase coefficient: defining a high synchronization force increase coefficient will make it possible to reduce the synchronization duration, while defining a lower synchronization force increase coefficient will make it possible to reduce the synchronization duration.

[0022] Consequently, controlling the synchronization duration makes it possible to better control the acoustic noise generated by the gearbox during a gear change, thus improving the comfort of use and the quality perceived by the driver.

[0023] The piloting method according to the first aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

[0024] - the piloting method comprises a step of applying a force of synchronization on the sleeve during the synchronization step;

[0025] - the coefficient of increase in synchronization effort determined during the step of determination depends on a percentage of depression of an accelerator pedal of the motor vehicle;

[0026] - the coefficient of increase in synchronization force is chosen from (i) first coefficients of increase in synchronization force when the percentage of depression of the accelerator pedal is included in a first depression interval, the synchronization force being included in a first saturation interval, (ii) second coefficients of increase in synchronization force when the percentage of depression of the accelerator pedal is included in a second depression interval, the synchronization force being included in a second saturation interval, the second coefficients of increase in synchronization force, the second depression interval and the second saturation interval being respectively greater than the first coefficients of increase in synchronization force, the first depression interval and the first saturation interval, and possibly (iii) third coefficients of increase in synchronization force when the percentage of depression of the accelerator pedal is included in a third depression interval, the synchronization force being included in a third saturation interval, the third coefficients of increase in synchronization force, the third depression interval and the third saturation interval being respectively greater than the second coefficients of increase in synchronization force, the second depression interval and the second saturation interval;

[0027] - the first coefficients of increase in synchronization effort are between 4000 N / s and 6000 N / s;

[0028] - the first depression interval is between 0% and 30% of a depression total accelerator pedal;

[0029] - the first saturation interval is between 350 N and 450 N;

[0030] - the second coefficients of increase in synchronization effort are included between 8500 N / s and 10500 N / s;

[0031] - the second sinking interval is between 31% and 98% of a fully depressing the accelerator pedal;

[0032] - the second saturation interval is between 550 N and 650 N;

[0033] - the third coefficients of increase in synchronization effort are included between 12500 N / s and 14500 N / s;

[0034] - the third depression interval is greater than 99% of a total depression of the accelerator pedal;

[0035] - the third saturation interval is between 750 N and 950 N;

[0036] - a synchronization duration of the synchronization step is variable depending on of the synchronization force increase coefficient determined by the calculator during the determination step, the synchronization duration being between 70 ms and 200 ms;

[0037] - the piloting method comprises a step of selecting a piloting profile of the gearbox among several control profiles, each control profile comprising a predefined triplet and comprising a synchronization force increase coefficient, a depression interval and a saturation interval.

[0038] Various embodiments of the invention are provided, integrating according to all of their possible combinations the different optional characteristics set out here.

[0039] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the attached schematic drawings on the other hand, in which:

[0040] [Fig-1] illustrates a schematic view of a vehicle powertrain hybrid-type electrified automobile;

[0041] [Fig.2] illustrates a sectional view of the synchronization device in a idle configuration;

[0042] [Fig.3] illustrates a sectional view of the synchronization device in a synchronization configuration;

[0043] [Fig.4] illustrates a sectional view of the synchronization device in a engagement configuration;

[0044] [Fig.5] illustrates a functional diagram of the synchronization device.

[0045] Of course, the features, variants and different embodiments of the invention may be combined with each other, in various combinations, provided that they are not incompatible or mutually exclusive. In particular, variants of the invention may be imagined comprising only a selection of features described below in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0046] In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

[0047] In the figures, the elements common to several figures retain the same reference.

[0048] With reference to [Fig.l], such a traction chain comprises:

[0049] - a heat engine 1 rotating a primary input shaft 11 of a 6-speed dual clutch system;

[0050] - the dual clutch system 6 configured to allow selection of a speed ratio in order to couple a secondary output shaft 12, linked in rotation to a drive wheel 10 of the motor vehicle, to the primary input shaft 11;

[0051] - an electric motor 3 configured to be able to be coupled in rotation to the shaft primary input shaft 11 in order, if necessary, to generate a motor torque on said primary input shaft 11;

[0052] - a controlled device 2 for coupling the electric motor to the primary shaft 11 input, the controlled coupling device 2 being configured to allow rotational coupling of the electric motor 3 with the primary input shaft 11, or to allow decoupling of said electric motor 3 with said primary input shaft 11.

[0053] In the context of the present invention, the dual clutch system 6 6 comprises a first gearbox 8, configured to control even speed ratios, and a second gearbox configured to control odd speed ratios. Thus, the first gearbox 8 makes it possible to couple the secondary output shaft 12 to the primary input shaft 11 through a selection of several even speed ratios, and the second gearbox 9 makes it possible to couple the secondary output shaft 12 to the primary input shaft 11 through a selection of several odd speed ratios.

[0054] Thus, the double clutch system 6 makes it possible to establish a rotational coupling of the secondary output shaft 12 with the primary input shaft 11 through one of the speed ratios, even or odd, of the first gearbox 8 or the second gearbox 9 respectively and, simultaneously, to establish a rotational coupling of the primary shaft with the second gearbox 9 or the first gearbox 8 respectively.

[0055] In other words, when the secondary output shaft 12 is rotationally coupled to the primary input shaft 11 via the first gearbox 8 -via an even speed ratio, then the second gearbox is coupled to the primary input shaft 11 in order to pre-engage an odd speed ratio directly higher or lower than the even speed ratio by which the rotational coupling between the primary input shaft 11 and the secondary output shaft 12 is established.Conversely, when the secondary output shaft 12 is rotationally coupled to the primary input shaft 11 via the second gearbox 9 - via an odd speed ratio, then the first gearbox 8 is coupled to the primary input shaft 11 in order to pre-engage an even speed ratio directly higher or lower than the odd speed ratio by which the rotational coupling between the primary input shaft 11 and the secondary output shaft 12 is established.

[0056] In order to achieve such an alternative coupling, the dual clutch system 6 comprises:

[0057] - a first clutch 4 configured to control a rotational coupling between the first gearbox 8 and primary shaft 11; and

[0058] - a second clutch 5 configured to control a rotational coupling between the second gearbox 9 and the primary shaft.

[0059] Each gearbox 8, 9 of the dual clutch system 6 comprises a synchronization device 20 which makes it possible to control the engagement of the gear ratios during rotational coupling with the primary shaft.

[0060] For this purpose, and with reference to [Fig.2], the synchronization device 20 comprises a synchronization sleeve 21 making it possible to engage two gears, by the dog-engagement of two pinions 30 on a transmission shaft 7 of the gearbox. The pinions 30 are placed axially on either side of the sleeve 21. An actuator 22 located in the synchronization sleeve 21 makes it possible to immobilize said sleeve 21 in a position creating a neutral position for the gearbox, in which neutral position no rotational coupling is established with the primary input shaft 11 or the secondary output shaft 12.

[0061] The sleeve 21 is moved by a fork (not shown) which is controlled by the actuator 22. The fork comprises two arms whose axial ends fit into a circular groove in the sleeve 21 in order to be able to push it axially in the direction of one of the speed ratios while allowing it to rotate freely.

[0062] The sleeve 21 comprises, in its bore, internal grooves which fit onto those of a hub 23 linked to the transmission shaft 7 of the gearbox, in order to transmit the torque of the engine between the sleeve 21 and the transmission shaft 7.

[0063] Figures 3 and 4 detail the operation of the synchronization device 20, in particular through respectively a synchronization step and a dog clutch step during a gear change.

[0064] The synchronizing sleeve 21 comprises, at each axial end, internal teeth which axially bear, when sliding towards a front side, on external teeth of a synchronizing ring 24 comprising an internal conical friction surface. During the synchronizing step, the sleeve 21 transmits by the teeth an increasing axial force on the synchronizing ring, which in turn presses the internal conical surface on a corresponding external conical surface 31 of the pinion 30. The pressure of the conical surfaces, 24, 31 on each other, thus generates an increasing synchronizing torque which tends to equalize the respective speeds of the sleeve 21 linked to the transmission shaft 7, and of the pinion 30. During the dog-engagement step, the rotational coupling between the transmission shaft 7 and the pinion 30 is established.

[0065] [Fig.5] illustrates the operation of the synchronization device 20, in which:

[0066] - the first curve 41 illustrates an axial displacement of the sleeve 21;

[0067] - the second curve 42 illustrates a rotation speed of the pinion 30; and

[0068] - the third curve 43 illustrates an axial force exerted on the sleeve 21.

[0069] We can thus distinguish several stages:

[0070] - an approach step PI during which the sleeve 21 is moved axially in direction of pinion 30 of the gear ratio to be engaged. During this PI approach step, actuator 22 is controlled in speed. During this PI approach step the rotation speed of pinion 30 associated with the gear ratio to be engaged does not increase since, although understood, the rotational coupling is not yet established. This axial displacement carried out during the PI approach step is carried out with a substantially constant axial force;

[0071] - a synchronization step P2 during which frictional coupling is achieved between the synchronization device 20 and the pinion 30 of the gear ratio to be engaged. During this frictional coupling, a gradient of increase in synchronization force is applied to the sleeve 21 in order to achieve such a frictional coupling. During this synchronization step P2, the actuator 22 is controlled as a function of the axial force. The object of the invention is precisely to control the gradient of increase in synchronization force by determining a coefficient of increase in synchronization force which can vary according to the use cases, the type of driving or the driver's request and his pressure on an accelerator pedal of the motor vehicle. During this synchronization step P2, the rotation speed of the pinion 30 of the gear ratio to be engaged increases proportionally to the axial force applied by the sleeve 21 to the pinion 30.The axial force applied to the sleeve 21 increases up to a maximum force, from which the axial force becomes constant while the rotation speed of the pinion 30 continues to increase. During the synchronization step P2, the sleeve 21 no longer follows any axial displacement. ; .

[0072] - when the rotation speed of the pinion 30 associated with the gear ratio engaged reaches the expected synchronization speed, then the engagement step appears, during which the axial force of the sleeve 21 decreases sharply during a backoff step P3. During the backoff step, the synchronization ring is detached from the pinion 30 and the sleeve 21 resumes an axial displacement: it is now possible to achieve the rotational coupling with the pinion 30 of the speed ratio to be engaged because the rotational speed of said pinion 30 is then equal to the target rotational speed. Also, the engagement step ends with a dog clutch step during which the rotational coupling is established: the speed ratio is engaged and the primary input shaft 11 is then coupled to the secondary output shaft 12, through said speed ratio. During this dog clutch step, a jump is observed in the axial force of the sleeve 21, at the very moment of the dog clutch entries.

[0073] The invention thus aims to determine the best parameters for controlling synchronization, and in particular for adapting a synchronization duration according to usage. Such a synchronization duration is defined by the following formula:

[0074] j = sjgn (^11 x varjap + jx

[0075] Where:

[0076] T is the synchronization duration, i.e. the duration of the synchronization step P2;

[0077] ^diff is the speed difference in radians per second measured at the synchronization device 20;

[0078] is worth 1 if we make an upshift, and -1 if we make a , is worth i if we rean downshift;

[0079] varJAP is the inertia of the primary shaft, in kg.m2;

[0080] b is the ramp for increasing the synchronization force, called the coefficient for increasing the synchronization force until reaching the maximum synchronization torque CM.

[0081] Thus, the control of the synchronization step P2 consists of providing the greatest possible axial force in order to reduce the synchronization duration to prepare the gearbox for the future gear change.

[0082] However, the energy stored during the synchronization step P2 leads to a loss of control of the actuator 22 in the deflection step P3 and dog clutching, which can cause unwanted shocks.

[0083] The invention thus aims to optimize the synchronization step P2 in order to find the best axial force on the sleeve 21 to optimize the synchronization duration with regard to the appearance of shocks during the deflection step P3.

[0084] To this end, the invention cleverly makes it possible to determine or calculate the coefficient of increase in synchronization force - b in the formula presented above and relating to the calculation of the synchronization duration, and possibly also to associate with it the maximum synchronization torque to be applied to the synchronization device 20 as a function of the time available to carry out the gear ratio preselection, according to the current use of the motor vehicle.

[0085] In particular, several ranges of values ​​of coefficients of increase in force and / or several intervals of depression of the accelerator pedal of the motor vehicle and / or several saturation intervals defining limit values ​​of axial force to be applied to the sleeve 21 of the synchronization device 20 are envisaged depending on the type of preselection to be carried out. Thus, the invention makes it possible to define several operating modes of a gearbox, in particular for a clutch of the double clutch type 6.

[0086] Thus, the percentage of depression of the accelerator pedal is considered to be representative of the driver's wishes, and cleverly leads to defining several scenarios for the parameterization of the coefficient of increase in synchronization force of the synchronization device 20:

[0087] - in the event of heavy use of the accelerator pedal, it may be desirable to skip a gear ratio. In this case, controlling the synchronization device 20 leads to strongly stressing the synchronization device 20 and determining a significant synchronization effort increase coefficient in order to reduce synchronization time;

[0088] - in the event of low demand on the accelerator pedal, it may be desirable to to carry out a simple gear change and to request the synchronization device 20 in a way that does not induce shocks or noise, even if it means increasing the synchronization duration and reducing the coefficient of increase in synchronization force.

[0089] In summary, the invention relates to a method for controlling a synchronization device of a controlled gearbox of a motor vehicle, the control method comprising:

[0090] - a step measuring the difference in speeds to be synchronized between a speed of rotation of a synchronizing ring of the synchronizing device and a rotation speed of a pinion to be synchronized;

[0091] - a step of approaching the synchronizing ring and the pinion to be synchronized;

[0092] - a synchronization step by applying a synchronization effort increasing on the synchronizing ring in order to create a synchronizing torque, the synchronizing force being applied according to a synchronizing force increase coefficient predetermined before the synchronizing step and which depends on the use of the motor vehicle;

[0093] - a step of dog-engaging a new gear ratio.

[0094] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive. In particular, all the variants and embodiments described above can be combined with each other.

Claims

Claims

1. Method for controlling a synchronization device (20) of a controlled gearbox (8, 9) of a motor vehicle, the synchronization device (20) comprising a sleeve (21) implementing a first friction cone belonging to a synchronization ring arranged between the sleeve (21) and a pinion (30) to be synchronized, and a second friction cone belonging to the pinion (30) and arranged opposite the first friction cone, to effect a change of gear ratio on the controlled gearbox (8, 9) comprising an electric machine linked to the primary shaft (11) of the gearbox (8, 9), the sleeve (21) being moved axially by an actuator (22) controlled by a computer which successively performs: - a step of measuring the difference in the speeds to be synchronized; - a step of approaching (PI) the friction cones;- a synchronization step (P2) by applying an increasing synchronization force to the first and second cones to create a synchronization torque, the synchronization force being applied to the sleeve (21) during the synchronization step (P2), according to an increasing intensity, until the speed difference becomes lower than a predetermined high threshold; - a step of dog-engaging a new gear ratio; characterized in that the computer carries out, prior to the synchronization step (P2), a step of determining a coefficient of increase in synchronization force (CM) depending on a percentage of depression of an accelerator pedal of the motor vehicle, this coefficient being used during the synchronization step (P2) to reach the synchronization force (CM) - called saturated - between the first and second cones.;

2. Control method according to the preceding claim, in which the coefficient of increase in synchronization force (CM) is chosen from: - first coefficients of increase in synchronization force (CM) when the percentage of depression of the accelerator pedal is included in a first depression interval, the synchronization force (CM) being included in a first saturation interval; - second coefficients of increase in synchronization force (CM) when the percentage of depression of the accelerator pedal is included in a second depression interval, the synchronization force (CM) being included in a second saturation interval, the second coefficients of increase in synchronization force (CM), the second depression interval and the second saturation interval being respectively greater than the first coefficients of increase in synchronization force (CM), the first depression interval and the first saturation interval;- third coefficients of increase in synchronization force (CM) when the percentage of depression of the accelerator pedal is included in a third depression interval, the synchronization force (CM) being included in a third saturation interval, the third coefficients of increase in synchronization force (CM), the third depression interval and the third saturation interval being respectively greater than the second coefficients of increase in synchronization force (CM), the second depression interval and the second saturation interval.;

3. Control method according to the preceding claim, in which the first coefficients of increase in synchronization force (CM) are between 4000 N / s and 6000 N / s, the first depression interval is between 0% and 30% of a total depression of the accelerator pedal, and the first saturation interval is between 350 N and 450 N.

4. Control method according to the preceding claim, in which the second coefficients of increase in synchronization force (CM) are between 8500 N / s and 10500 N / s, the second depression interval is between 31% and 98% of a total depression of the accelerator pedal, and the second saturation interval is between 550 N and 650 N.

5. Control method according to the preceding claim, in which the third coefficients of increase in synchronization force (CM) are between 12500 N / s and 14500 N / s, the third depression interval is greater than 99% of a total depression of the accelerator pedal, and the third saturation interval is between 750 N and 950 N.

6. Control method according to any one of the preceding claims, in which a synchronization duration of the synchronization step (P2) is variable depending on the synchronization force increase coefficient (CM) determined by the computer during the determination step, the synchronization duration being between 70 ms and 200 ms.

7. Control method according to any one of claims 2 to 6, in which the control method comprises a step of selecting a control profile of the gearbox (8, 9) from among several control profiles, each control profile comprising a predefined triplet and comprising a synchronization force increase coefficient (CM), a depression interval and a saturation interval.

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