WO2012107679A1

WO2012107679A1 - Device and method for controlling a twin-clutch gearbox

Info

Publication number: WO2012107679A1
Application number: PCT/FR2012/050257
Authority: WO
Inventors: Eric Schaeffer
Original assignee: Peugeot Citroen Automobiles Sa
Priority date: 2011-02-07
Filing date: 2012-02-06
Publication date: 2012-08-16
Also published as: FR2971316A1; FR2971316B1; EP2673532A1

Abstract

The present invention relates to a device for controlling a twin-clutch gearbox (101) when changing gear ratios to shift from an initial gear ratio to a target gear ratio, said gearbox including two clutches (216, 218), each combined with an input shaft (222, 200) which said clutches rotatably connect to a power train (102), two output shafts (230, 232) connected to slaves (103), and dogs (15) provided with synchronisers (252, 254) combined with the gear ratios, each input shaft (222, 200) being connected to an output shaft (230, 232) by means of synchronised gear trains in order to transmit power according to a rotary movement between the power train (102) and the slave (103), said gear trains each corresponding to a transmission ratio (241 to 247) combined with a gear-shifting mechanism. The present invention also relates to a method for controlling a gearbox (101) equipped with such a device.

Description

DEVICE AND METHOD FOR CONTROLLING A GEARBOX

DOUBLE CLUTCH

The present invention relates to a device, a method for controlling a double-clutch gearbox more particularly adapted for power transmission in a motor vehicle, and a motor vehicle incorporating such a device.

More particularly, the subject of the invention is a device and a method for adapting the synchronization strategy of a dual-clutch gearbox as a function of the time available for the gearshift. The invention aims to limit the wear of the synchronizers of a double-clutch gearbox.

According to the prior art, a motor vehicle comprises a power transmission chain comprising a powertrain such as a heat engine and / or an electric machine, a clutch, and a gearbox, itself connected to the drive wheels. The clutch ensures the transmission of power between the powertrain and the gearbox, itself connected to the wheels.

This gearbox is a mechanical element comprising a plurality of gear trains delivering torque transmission ratios, originating from a primary shaft, coupled to the powertrain, to a secondary shaft, coupled to receivers, for example, the drive wheels of a vehicle. The gearbox makes it possible to adapt the transmission ratio between the powertrain and the receiver, in particular as a function of the available engine torque and the torque required to drive the receiver.

The transmission ratio of a train designates the ratio between the speed of rotation of the receiver and the speed of rotation of the motor shaft when they are coupled via said train.

Double clutch gearboxes are known from the prior art, especially in the field of motor vehicles, to allow the gear ratio change without breaking the acceleration of the vehicle. Each transmission ratio corresponds to a report of the gearbox, which reports are generally classified according to an increasing number according to the transmission ratio, each transmission ratio receiving a serial number.

These gearboxes have the advantage of using mechanical technology and a kinematics approaching manual mechanical gearboxes. conventional, parallel gear trains, whose performance is significantly better than that of automatic gearboxes planetary gear.

A double-clutch gearbox is a gearbox that takes the architecture of a conventional manual gearbox, split into two half-boxes.

Indeed, the basic principle of a double-clutch gearbox is to separate the box reports in two sub-boxes, a half-box comprising the trains corresponding to the reports whose number is even, a second half -box for trains with an odd order number.

Each gear train has a wheel connected to one of the shafts and a pinion, called idler, mounted on the other shaft. Dogs each provided with a synchronizer are used to selectively link the idle gears to the shaft on which they are mounted to ensure a gear shift. For this purpose, the dog is rotatably connected to its shaft but is movable axially to allow attachment with a pinion.

It is called dog clutch when the dog realizes the connection in rotation of the shaft with the idler gear, so that a gear ratio is engaged.

The synchronizers, mounted on the claws have the role of bringing the clutch and the idler gear identical rotational speeds before realizing the clutch. Indeed, during a gearshift, the clutch is linked to the secondary shaft which is connected to the wheels, while the idler gear ratio to engage is rotatably connected to the primary shaft (or vice versa) . But the primary shaft and the secondary shaft rotate at different speeds. The synchronizer then makes it possible to synchronize the speed of the primary shaft with that of the secondary shaft connected to the wheels.

There are different types of synchronizers also called "synchronization hubs" including cone synchronizers.

A cone synchronizer is splined inside and slides on the splines of the secondary shaft. Its two front and rear faces are machined cone-shaped, usually female, while its perimeter is crenellated. A crenellated ring inside, slides around the hub in the longitudinal direction, and has a circular groove in which is engaged the gear control fork. The face of the pinion situated opposite the synchronizer comprises a male cone corresponding to the female cone of the synchronizer, and at the periphery of the cone, "slots" having the same diameter and the same teeth as the slots of the periphery of the synchronizer. . Thus, the slots of the synchronization ring can come to engage on the crenellations of the pinion. This is achieved by moving the lever of the transmission linkage, which slides the bushing synchronization on the splines of the hub. Pinion and synchronization hub are coupled; the drive of the tree is done so smoothly.

In a double-clutch gearbox, for each half-box the synchronizers make up-and-down passages, that is, between two odd-order number reports or two odd-order number reports. .

In other words, the shift strategy of a dual clutch transmission is to synchronize the best transmission ratio, this transmission ratio being determined autonomously by the shift management system, said calculator, thanks to the interpretation of information such as the torque and the speed of rotation of the engine, the depression of the accelerator pedal, the speed of the vehicle, the operating mode of the gearbox, the resistant torque of the vehicle . This information makes it possible to inform the management system on the will of the driver to accelerate the vehicle on the one hand and power transmission conditions on the other hand.

The synchronized report is then pre-engaged pending the crossing of the two clutches finalizing the change of transmission ratio.

The dual clutch gearbox has at least two primary shafts, each coupled to the motor shaft via a dual clutch system. The first primary shaft is coupled to a first secondary shaft by engagement of at least one transmission train whose transmission ratio defines a first speed. The second primary shaft is coupled to a second secondary shaft by the engagement of at least one transmission train whose transmission ratio defines a second speed. This second speed allows a higher transmission ratio compared to the first speed.

In a double clutch gearbox, the engagement and selection of the gear trains corresponding to the order numbers of the reports are controlled by a control system, by means of actuators. The dual-clutch gearbox can thus preselect the top or bottom speed, to raise or lower the desired gear ratio.

During a gearshift, the control system controls the clutch and shifts the gear in place of the driver. The control control system opens the clutch of the first half-box and closes simultaneously that of the second. The control system is controlled by an electronic computer, capable of adapting its actions according to the driving mode of the driver. Such a gearbox is described in document FR-A-2 885 978. This document also discloses a strategy for controlling the synchronizers of such gearboxes, thus making it possible, during a gear change, to go through an intermediate value of close value, by transferring the driving torque from one primary motor shaft to another.

However, when changing gear with a dual-clutch gearbox as in FR-A-2 885 978, all synchronizers is substantially more stressed than in a conventional architecture gearbox.

Indeed, to perform for example, a change from the second to the third gear, the synchronizer previously interlocked with the gear train of the first gear ratio is found clutching the gear train of the third gear ratio. The large difference in speed during the transition from the first speed to the third speed generates a risk in terms of the energy dissipated in the synchronizer of the third gear ratio. This risk is due to the important jump of transmission ratio during the passage between the two speeds. This constraint during the change of speed, leads on the one hand, to a large dimensioning of the diameter of each friction cone, and on the other hand, to a multiplication of said cones in the gearbox.

The object of the invention is to solve these disadvantages of the prior art.

For this purpose, according to a first aspect, the present invention is directed to a device for controlling a double-clutch gearbox during the change of speed ratio from an initial speed ratio to a target gear ratio. said box comprising two clutches, each associated with a primary shaft that they rotate with a powertrain, two secondary shafts connected to receivers, and claws with synchronizers associated with the reports, each primary shaft being linked to a secondary shaft via synchronized gear trains for the transmission of power in a rotational movement between the power train and the receiver, said trains each corresponding to a transmission ratio associated with a gearshift mechanism, said group power train comprising an acceleration control, said device comprising:

a power transmission condition sensor and a speed control sensor of the acceleration control,

a means for determining the available time Td between two gear ratio changes, and management means capable of adapting the choice of a synchronization strategy of the gear trains of the target speed ratio as a function of the available time Td between two gear ratio changes.

In other words, the device according to the invention makes it possible to adopt the optimal strategy of soliciting the synchronizers as a function of the available time Td to effect the passage of the target speed ratio.

One of the advantages of the invention is to allow a better synchronization of gear ratios in dual-clutch type gearboxes, especially for applications involving motor vehicles. The device according to the invention solves the problem of overstressing synchronizers in this type of gearboxes.

Another advantage of the device according to the invention is its ease of implementation in a motor vehicle.

The invention can be implemented according to the advantageous embodiments described below which can be considered individually or in any operating combination.

According to particular characteristics, the sensors of the power transmission conditions comprise one of the following sensors:

a speed sensor of the receiver;

- a motor rotation speed sensor;

a speed sensor for rotating one of the two primary shafts;

a position sensor of one of the clutches.

Advantageously, the set of these sensors makes it possible to provide the necessary information to determine the available time Td between two gear changes, as well as the synchronization time Ts, the energy and the power dissipated by the synchronizers among others.

This information informs the means of management of the device on the running conditions of the vehicle and the speed of loading of the throttle control thus making it possible to select the best synchronization strategy of the gear train of the target gear ratio.

According to particular features, the gearshift mechanism includes a gear shift fork and the gear condition sensors comprise a position sensor of said fork.

According to particular features, the device which is the subject of the invention comprises a braking command and the power transmission condition sensors comprise a solicitation sensor of the said braking command. According to particular characteristics, the management means is a transmission control system comprising a computer and actuators.

In other words, the sensors inform the computer of the gearbox which, based on these data, controls the actuators.

The actuators may be, for example, actuators of the synchronizers, actuators of the clutches.

A second aspect of the invention provides a method for controlling a gearbox equipped with a device according to the invention comprising:

a determination step of determining the power transmission conditions from the information supplied by the power transmission condition sensor and the acceleration control load speed sensor,

a calculation step consisting in determining the available time Td between two gear ratio changes, and

an adaptation step, of selecting a strategy for synchronizing the gear trains of the target speed ratio as a function of the available time Td between two gear ratio changes.

According to particular features, the adaptation step consists in selecting a strategy from the set comprising:

- a strategy of soliciting the synchronizer of the train of the target speed ratio only,

a strategy comprising steps for sequentially soliciting several synchronizers,

a strategy of soliciting the clutch not in engagement, and

a strategy of sequential solicitation of a synchronizer.

Thus, the method which is the subject of the invention advantageously makes it possible to select the synchronization strategy of the double-clutch gearbox which results in an optimal use of the synchronizers and an gearshift that is efficient in the time available for synchronization.

These different synchronization strategies are known and their implementation is simple.

One strategy is to directly request the train synchronizer of the target gear only.

Another strategy for controlling a double-clutch gearbox is a control method comprising steps of sequential solicitation of one or more synchronizers described in the document FR0956512. This allows a shift from a lower gear to a higher gear or vice versa, with a greater speed difference than soliciting a single synchronizer. This method makes it possible to solicit, at the end of a passage in a gear ratio, the synchronizer of the final gear ratio, in order to perform part of the synchronization phase, the final synchronizer being solicited prior to the interconnection of the latter.

Next, the document EP1672253 describes the strategy of engaging the non-engaged clutch which consists in implementing the clutch of the disengaged half-gearbox to achieve synchronization when the predetermined maximum synchronization time exceeds the maximum effort. that the synchronization device can provide.

Finally, the sequential solicitation of a synchronizer is a strategy described by the document FR0959085 in which the application of the synchronizer is in two parts.

According to particular features, in the adaptation step, when the available time Td is shorter than a predefined time Td min (Td <Td min), the synchronization strategy is the strategy (326) of sequential solicitation of a synchronizer or strategy (324) for soliciting the synchronizer of the target gear train only.

In other words, in this case, it is necessary to perform a calculation of the synchronization time Ts. The synchronization time Ts depends mainly on the speed difference, and therefore on the initial synchronization speed. The synchronization time decreases as the force applied to this synchronizer increases. The speed of rise in effort and the maximum effort of synchronization also affect the synchronization time Ts.

Thus, when the synchronization time is sufficiently short, the synchronization strategy comprises sequential solicitation steps of several synchronizers while, in the opposite case, the synchronization strategy is the strategy of soliciting the synchronizer of the train of the target speed ratio only. .

According to particular characteristics, when the available time Td longer than a predefined time Td max (Td> Td max), the selected synchronization method is the solicitation of the non-engaged clutch.

This advantageously makes it possible to limit the solicitation of the synchronizer of the target ratio.

According to particular characteristics, in the adaptation step, in cases where the available time Td is intermediate between Td min and Td max (Td min <Td < Td max), a step of calculating the maximum power Pmax allowed by the synchronizer is performed.

One of the limitations of the synchronization system lies in the power dissipated by the synchronizer without risk of deterioration of its components. In order to guarantee an optimized synchronization time, whatever the type of shift, without causing damage to the synchronizer mechanism, the method that is the subject of the invention takes into account the maximum power allowed by the synchronizer. This power Pmax depends on the materials of the synchronizer and the friction surface between the idle gear and the synchronizer. The calculation of Pmax is described in document FR2915259.

According to particular characteristics, the synchronization strategy adopted is the strategy of sequential solicitation of a synchronizer or the strategy of sequential solicitation of several synchronizers.

More particularly, when the calculated maximum power Pmax admissible by the synchronizer is less than a threshold Pliml, the synchronization strategy adopted is the sequential solicitation of several synchronizers and when the maximum power Pmax allowed by the synchronizer is greater than a threshold Plim2 the strategy adopted synchronization is the sequential solicitation of a synchronizer.

It will be noted that Plim1 and Plim2 are predetermined power threshold values according to the characteristics of the synchronizers in a manner known as Plim1 respectively for the threshold beyond which the power allowed by the synchronizers is high and for Plim2 the threshold below which the power output by synchronizers is low. In other words a Pmax <Plim1 is considered to be a maximum allowable power by the weak synchronizers and a Pmax> Plim2 is considered to be a maximum allowable power by the strong synchronizers.

Another aspect of the invention is a motor vehicle characterized in that it comprises a device according to any one of the preceding embodiments.

The advantages, aims and particular characteristics of this method and this vehicle being similar to those of the device object of the present invention, they are not recalled here.

Other advantages, aims and features of the invention will appear on reading the following description given by way of example, in no way limiting, and with reference to the figures in which: - Figure 1 shows, schematically, a vehicle comprising a double clutch gearbox control device object of the invention in a particular embodiment,

- Figure 2 shows schematically in plan view, a double clutch gearbox comprising a control device object of the invention in a particular embodiment,

FIG. 3 represents, in the form of a logic diagram, the steps implemented in a particular embodiment of the method that is the subject of the present invention, and

- Figure 4 shows schematically an example of sequencing of upshifts speeds reports.

It is noted that the figures are not to scale.

In general, the present invention relates to gearboxes 101 comprising synchronized trains corresponding to transmission ratios, when changing a speed towards a target speed, for a vehicle 100 comprising an acceleration control 105 and a brake control 106.

As illustrated in FIG. 1, the gearbox 101 is a mechanical element proposing several transmission ratios of a torque coming from a primary shaft, coupled to the motor 102, to a secondary shaft, coupled to the vehicle's driving wheels 103. . The gearbox 101 makes it possible to adapt the available engine torque to the torque required to move the vehicle 100.

In the remainder of the description, reference is made primarily, by way of non-limiting example, to a motor vehicle 100 equipped with a gearbox 101 with a double clutch.

As illustrated in FIG. 2, in a particular embodiment, a gearbox 101 with a dual clutch of a motor vehicle consists mainly of a flywheel 212 rotated by the output shaft 214 of the engine 102 and two clutches 216 and 218 concentric.

A first clutch 218, driving a first hollow primary shaft 222 and a second clutch 216, juxtaposed to the first 218, driving a second primary shaft 200 full, passing inside the hollow primary shaft 222.

The primary shafts 200, 222 are each coupled to the secondary shafts 230, 232 via transmission trains whose transmission ratios define gear ratios.

These speed ratios are divided into two half-boxes. a first half-box comprises the trains corresponding to the ratios whose sequence number is even (the second gear ratio 242, the fourth gear ratio 244 and the sixth gear ratio 246), and

a second half-box comprises the trains corresponding to the ratios whose order number is odd (the first gear ratio

241, the third gear ratio 243, the fifth gear ratio 245 and the seventh gear ratio 247).

The gear train of a gear ratio, for example that of the second gear ratio 242, comprises a first pinion 281 called "fixed gear", integrally bonded to a primary shaft 222, meshing with a second pinion 280 called "pinion" mad "mounted free in rotation and fixed in translation on the secondary shaft 232.

A synchronization device 252 comprising a synchronization ring 254, mounted free in translation and fixed in rotation on the secondary shaft 232, is controlled by a synchronization actuator 260 rotated on a secondary shaft 232 and secured to this shaft by means of a jaw box.

On the primary shafts 200 and 222 are mounted sensors 265 of the angular velocity of the primary shafts 200, 222.

The adaptation management means of the choice of the best synchronization strategy of the gear trains comprise a computer 104 which receives signals from the sensors 265 representative of the angular speed of the primary shaft 200 and the engine speed 102 and transmits control signals of the synchronization actuators 260 and clutch actuators 268.

When it is desired to change the gear ratio, in particular to engage a gear that requires a gear shaft 200, 222 to be engaged, it is necessary to synchronize and then engage the idle gear 280, corresponding to the target gear ratio. The synchronization in question amounts to equalizing the speed of this idle gear 280, and the speed of the secondary shaft 232.

By means of the device according to the invention, it is possible to use different sensors 265, present in the gearbox 101 and / or in the automobile vehicle 100, able to transmit to the computer 104 the information necessary to determine power transmission conditions and the accelerating speed of the acceleration control, in order to calculate the available time Td for effecting the synchronization of the target speed ratio and thus correspondingly adapting the synchronization strategy of the gear train which guarantees optimum operation.

These sensors can be: a speed sensor of the receiver 103;

a motor rotation speed sensor 102;

a speed sensor for rotation of one of the two primary shafts 200, 222;

a position sensor of one of the clutches 218,216;

sensors for soliciting the acceleration control 105;

- Sensors of the position of the shift forks, in this case each report 241 to 247 is equipped with a position sensor.

FIG. 3 represents in the form of a logic diagram the method for controlling a gearbox 101 of a device that is the subject of the invention, comprising:

a determination step 305 consisting in determining the power transmission conditions from the information supplied by the power transmission condition sensor and the acceleration control biasing speed sensor,

a calculation step 310 consisting in determining the available time Td between two changes in gear ratios, and

a step 315 of adaptation, of selecting a strategy 324, 326, 328, 336 for synchronizing the gear trains of the target speed ratio as a function of the available time Td between two changes of gear ratios.

In a step 305, the various sensors 265 of the device according to the invention make it possible to obtain information that provides information on the power transmission conditions of the vehicle and the speed of loading of the acceleration control. This information may concern, for example, the speed of the engine 102, the position of the accelerator pedal 105, the brake pedal 106 or even the speed of the vehicle.

From the quantities and information available to the computer 104 including the gear ratio engaged and the speed ratio to be engaged, in a second step 310 the computer 104 calculates the available time Td for the synchronization gear ratio report target speed.

Then, in a step 315, the computer 104 controls the various actuators 268, 260 to adapt as a function of the available time (Td) calculated in the previous step the choice of a synchronization strategy of the gearbox 101. As a function of the available time Td, the device according to the invention selects the optimal strategy for synchronization from among the set comprising:

the strategy 322 for soliciting the synchronizer of the gear of the target gear ratio only,

the strategy 326 comprising steps of sequential solicitation of several synchronizers, according to the proposal of the patent application FR0956512,

the strategy 328 of soliciting the clutch not in engagement, in order to limit the loading of the synchronizer of the target ratio as known in the document EP 1 672 253 A1, and.

- Strategy 336 sequential solicitation of a synchronizer according to the proposal of the patent application FR0959085.

In other words, different cases, which we will detail below, can occur in this step 315.

More precisely, these are the cases where the time, Td, between two changes of ratio will be:

- the shortest Td min

- the longest Td max, and

- the intermediate cases where Td min <Td <Td max.

By "Td max", the longest time between two gear ratio changes means a time of the order of several tens of minutes for example when driving the motor vehicle on the highway.

By "Td min" the shortest time between two changes of gears is a time of a few hundred milliseconds. This is the case, for example, of the sequence of gear changes at the exit of a motorway toll, and / or the departure of the vehicle at a standstill with a depression of the maximum accelerator pedal.

In other words, the speed of the vehicle and the depression of the accelerator pedal on a scale of 0 to 100% determine the range of available time. So the time, Td, between two changes of ratio is:

- Td min when it is between 250 ms and 2 s,

- Td max from 10 s, and

- intermediate T when it is between 2 and 10 s.

In the case 320 where the time Td between two changes of ratio is the shortest Td min is the least favorable case. The speed of the motor 102 is maximum and the acceleration of the vehicle is not zero.

This case is in particular detected by the position of the accelerator pedal 105. Indeed, in the case where the pedal 105 is in a fully depressed position, this indicates a desire for significant acceleration from the driver. The gearshift passages are thus linked very quickly to meet this acceleration need of the vehicle 100.

FIG. 4 illustrates an example of the passage of upshift gears when the acceleration control is fully loaded 401, which is equivalent to a total depression of the acceleration pedal 105.

Three successive phases are then linked together.

In the first phase 405, the first gear is engaged. The speed curve 402 of the odd prime shaft 200 increases linearly in the same manner as the speed curve 403 of the motor 102 until reaching the threshold 404 of the maximum speed of the motor 102.

During this time, the second speed is preselected and the speed curve 406 of the primary shaft 222 par increases also linearly, less than the speed curve 402 of the odd primary shaft 200.

Then in a second phase 410, the crossing 41 1 clutches 216, 218 allows the passage of the first speed to the second.

The velocity curve 402 of the odd prime shaft 200 continues to grow, while the speed 403 of the motor 102 decreases to join the velocity curve 406 of the rising prime shaft 222.

Closing 412 of the even clutch 218 drives a third phase 415, in which the speed curve of the odd prime shaft 200 decreases 416 until it becomes less than the curve of the speed of the even prime shaft 222.

It is noted that the synchronization of the third gear ratio can not be performed before the end of the shift of the first gear to the second gear.

In this case it is necessary to synchronize the target report as soon as the closing of the clutch is actually detected.

In other words in the case 320 where the available time Td is the shortest, that is to say Td min of the order of a few hundred milliseconds, the calculation of the synchronization time Ts is performed. Two cases are then possible:

the synchronization time Ts is not short enough, the synchronization strategy adopted then is the synchronization strategy 324 comprising the solicitation of the synchronizer of the target speed ratio only, - The synchronization time is short enough, the synchronization strategy adopted is the strategy 326 described in the patent application FR0959085 in which it is to solicit one or more synchronizers sequentially.

The strategy described in the document FR 0959085 comprises:

a step of beginning to synchronize the gear trains in which a force is applied to the synchronizer 252, 254 sufficient to bring the first primary shaft 222 to a speed of rotation between the initial speed and a final synchronization speed on the next gear ratio;

a synchronization relaxation step in which the force applied to the synchronizer 252, 254 is released; and

a finalization step in which the force is again applied to the synchronizer 252, 254 until said primary shaft 222 is brought to the final synchronization speed.

A second case 325, the most "comfortable", is the case where the time Td available for synchronization is the longest Td max.

In this case, the speed of the motor 102 is less than a maximum while the acceleration is zero.

This is particularly the case of the gearshifts on "wandering" that is to say with acceleration pedal depression 105 zero.

Indeed, this life situation of the vehicle 100 is considered comfortable because it ensures a passage time between two reports long enough to use the strategy 328 described in EP 1 672 253 A1.

The method according to EP 1 672 253 A1 for synchronizing the shafts 222, 232 of a gearbox 101 with a double clutch enables the clutch of the disengaged half-gearbox to be stressed, in order to limit the loading of the synchronizer 252, 254 of the report. target speed.

According to the strategy described in document EP 1 672 253 A1, if the effort required for the synchronization to be carried out in a predetermined maximum duration of synchronization Ds exceeds the maximum effort that the synchronization device can provide, then the clutch no in-put is also implemented so as to achieve the synchronization in the imparted duration Ds.

Thus, if the synchronizing ring device is not sufficient to synchronize the shaft 222 to synchronize in the time provided, the non-engaged clutch is implemented either simultaneously or prior to the implementation of the device to be synchronized. rings. Synchronization is accelerated. Finally, in intermediate 330 cases, the method comprises an additional step 335 for calculating the maximum power Pmax allowed by the synchronizer.

It should be noted that "intermediate cases" are understood to mean the cases where the available time Td has an intermediate value between Td min and Td max. In these cases the vehicle has a medium speed and an average acceleration.

In step 335, the calculation of the synchronization time of the trains and Pmax is carried out according to the different utilization hypotheses of the synchronizers, that is to say the strategy with a single synchronizer or the sequential control of several synchronizers.

The calculation of the maximum power Pmax allowed by the synchronizer 252, 254 is described in the patent application FR 2915259. In this case the selection of the synchronization solicitation strategy 252, 254 is done by comparing Pmax with a threshold value of Pliml power, Plim2.

It should be noted that Plim1 and Plim2 are predetermined power threshold values by calculations according to the characteristics of the synchronizers 252, 254 in a manner known per se for Plim1, the threshold beyond which the power allowed by the synchronizers 252, 254 is high. and for Plim2 the threshold below which the power allowed by the synchronizers 252, 254 is low. In other words a Pmax <Plim1 is considered to be a maximum allowable power by the weak synchronizers and a Pmax> Plim2 is considered to be a maximum allowable power by the synchronizers 252, 254 strong.

On the one hand, when the maximum power Pmax allowed by the synchronizer 252, 254 is greater than a threshold Plim2, the synchronization strategy 326 adopted is the sequential solicitation of a synchronizer 252, 254 described in the patent application FR0959085.

On the other hand, when the maximum power Pmax allowable by the synchronizer 252, 254 is less than a threshold Plim1, the strategy 336 of sequential biasing of several synchronizers 252, 254 is used before effecting the interconnection of the gear of the gear ratio. target described in the patent application FR0956512.

This strategy 336 comprises the following steps:

a speed ratio currently engaged and a desired final speed ratio are determined,

a variation in the speed of the primary shaft 222 biased for the synchronization of the final ratio is determined, - When the speed of the primary shaft 222 increases then it solves sequentially and decreasingly, as soon as the end of the passage of the gear ratio engaged, one or more synchronizers 252, 254 reports higher than the desired final speed ratio of the half -box,

when the speed of the primary shaft 222 decreases, one or more synchronizers 252, 254 of ratios lower than the desired final speed ratio of the half, are sequentially and progressively solicited as soon as the passage of the engaged speed ratio is solicited; -box.

The method and the device which is the subject of the present invention make it possible to solve the problem of the increased loading of the synchronizers 252, 254 in the double-clutch gearboxes 101 by adopting the strategy 324, 326, 328, 336 of optimal synchronization as a function of the available time Td to synchronize the gear trains of the target gear ratio.

Claims

Apparatus for controlling a double-clutch gearbox (101) when shifting gears from an initial speed ratio to a target gear ratio, said gearbox comprising two clutches (216, 218) , each associated with a primary shaft (222, 200) rotatably connected to a power unit (102), two secondary shafts (230, 232) connected to receivers (103), and claws with synchronizers (252). , 254) associated with the ratios (241 to 247), each primary shaft (222, 200) being connected to a secondary shaft (230, 232) via synchronized gear trains for transmitting power in accordance with a rotational movement between the power train (102) and the receiver (103), said trains each corresponding to a transmission ratio (241 to 247) associated with a gearshift mechanism, said power train (102) comprising a power control 'Acceler a device (105), said device being characterized in that it comprises: - a power transmission condition sensor (265) and an acceleration control biasing speed sensor (105), - a means ( 104) for determining the available time Td between two speed ratio changes, and - management means (260, 268) adapted to suit the choice of a train synchronization strategy (324, 326, 328, 336). gear ratio of the target speed as a function of the available time Td between two gear shifts. Device according to Claim 1, characterized in that the sensors (265) of the power transmission conditions comprise one of the following sensors: a speed sensor of the receiver (103); a motor rotation speed sensor (102); a speed sensor of one of the two primary shafts (200, 222); a position sensor of one of the clutches (218, 216). Device according to one of claims 1 to 2, characterized in that the gear change mechanism comprises a shift fork and the transmission condition sensors comprise a position sensor of said fork. Device according to one of claims 1 to 3, characterized in that it comprises a brake control (106) and that the power transmission condition sensors comprise a biasing sensor of said brake control (106). Device according to one of claims 1 to 4, characterized in that the management means is a control system of the gearbox (101) comprising a computer (104) and actuators (260, 268). A method for controlling a gearbox (101) equipped with a device according to any one of the preceding claims, characterized in that it comprises: - a determination step (305) consisting in determining the transmission conditions power from the information supplied by the power transmission condition sensor (265) and the acceleration control load speed sensor (105), - a calculation step (310) of determining the time available Td between two changes in speed ratios, and - a step (315) of adaptation, of selecting a strategy (324, 326, 328, 336) for synchronizing the gear trains of the target speed ratio as a function of the available time Td between two gear changes. Method according to claim 6, characterized in that the adaptation step (315) consists in selecting a strategy from the set comprising: a strategy (324) for biasing the synchronizer of the train of the target speed ratio only; a strategy (336) including steps of sequentially soliciting multiple synchronizers, - a strategy (328) soliciting the unengaged clutch, and - a strategy (326) for sequentially soliciting a synchronizer. Method according to claim 6, characterized in that in the adaptation step (315), when the available time Td is shorter than a predefined time Td min (Td <Td min), the synchronization strategy is the strategy (326) sequential biasing of a synchronizer or strategy (324) of soliciting the synchronizer of the gear of the target gear ratio only. Method according to claim 6, characterized in that in the adaptation step when the available time Td is longer than a predefined time Td max (Td> Td max), the synchronization strategy is the strategy (328) of solicitation of the clutch not engaged. 0. Method according to claim 6, characterized in that in the adaptation step, in cases 330 where the available time Td is intermediate between Td min and Td max (Td min <Td <Td max), a step 335 calculation of the maximum power Pmax allowed by the synchronizer is performed.

1. Method according to claim 10, characterized in that the synchronization strategy adopted is the strategy (326) of sequential solicitation of a synchronizer or the strategy (336) of sequential solicitation of several synchronizers.

2. Vehicle, especially automobile, characterized in that it comprises a device according to one of claims 1 to 5.