FR2808065A1 - Hydraulically controlled transmission for motor vehicles, uses controlled solenoid valves to selectively connect pressure source to engine coupling clutch or gear engagement clutches - Google Patents

Abstract

The transmission has a hydraulic clutch (16) coupling the transmission to the engine and hydraulic multi-disk clutches (46) that engage a gear by coupling it to the gearbox shaft. A single source (118) of hydraulic pressure selectively supplies the clutches through control of solenoid valves (128,130) connecting the clutches to the pressure source.

Description

The invention relates to a hydraulically controlled transmission for a motor vehicle.

The invention more particularly relates to a hydraulically-controlled transmission for a motor vehicle, of the type which comprises a gearbox which can be selectively coupled to a vehicle engine via a coupling hydraulic clutch which comprises a primary shaft and at least one secondary shaft, parallel to the primary shaft, between which are arranged at least two transmission gears whose idler gears are likely to be selectively engaged to determine associated gear ratios of the type, of the type which comprises at least one synchronization gear, arranged between the primary shaft and the secondary shaft, whose idle gear is likely to be to the shaft which carries it via a multi-disc hydraulic clutch, particularly for deflect the drive torque of the transmission gear associated with the current transmission ratio to the gearbox e synchronization before disengagement of said transmission ratio, and to synchronize together in rotation the primary shaft and the secondary shaft before the engagement of the gear ratio associated with the other gear transmission.

There are many examples of hydraulically controlled transmissions of this type.

These transmissions implement multi-disk clutches, that is to say clutches for each of which a plurality of disks integral with a hub connected to a first rotating element are capable of being axially clamped against a plurality of disks solidarity tray linked to a second rotating element. Document US Pat. No. 5,313,856 describes and represents a hydraulically-controlled transmission comprising a gearbox of this type of which a primary shaft may be connected to a motor of the vehicle by means of a clutch of coupling. A box synchronization gear, whose idler gear can be linked to the primary shaft the door through a multi-disk clutch, capable of deflecting the engine torque of the transmission gear associated with the current transmission ratio to the synchronization gear before disengaging said transmission ratio, and then synchronizing together in rotation the primary shaft and the secondary shaft before engaging the gear ratio associated with the other transmission gear. The primary shaft coupling clutch and the multiple idler gear clutch are each controlled by an independently powered electromagnetic or hydraulic actuator.

The disadvantage of such a design applied to a hydraulically controlled transmission lies in the large number of actuators necessary for its proper operation.

Indeed, the increasing complexity of today's powertrain vehicles requires having transmissions as compact as possible, and it is therefore desirable to minimize the space devoted to such actuators: Moreover, such a design also poses a problem because of its complexity. A large number of independent hydraulic actuators greatly increases the risk of failure. It is therefore desirable to benefit from a hydraulically controlled transmission for which the hydraulic circuit is as simple as possible, ie having a large number of common members, which is not the case with the transmission described in FIG. US-A-5,313,856. The invention therefore proposes a hydraulically controlled transmission of the type described above comprising a simple hydraulic circuit.

For this purpose, the invention therefore proposes a hydraulically controlled transmission of the type described above, characterized in that it comprises a single source of hydraulic pressure which is capable of selectively supplying coupling hydraulic clutches and multidiscs to the intermediate controlled solenoid valves. According to other features of the invention, the single hydraulic pressure source is an electro-hydraulic actuator comprising at least one hydraulic jack in which a controlled piston, which is actuated via an electric motor, defines a chamber of front pressure and a rear pressure chamber - the electro-hydraulic actuator comprises a clutch cylinder and a synchronization cylinder whose pistons controlled, integral with each other, are actuated by a common electric motor; the clutch and synchronization cylinders each comprise an additional piston, called a capacity piston, which is arranged in their front pressure chamber and which resiliently returns by a calibrated spring fixed to the piston controlled so as to delimit between the controlled piston and the capacity piston a so-called capacity chamber connected supply reservoir which is intended to maintain constant pressure in the front pressure chamber during the movements of the controlled piston; the front pressure chamber of the clutch cylinder is connected to a chamber of the coupling clutch in a direct manner and is connected to a supply tank via a first non-return valve, - the chamber of the rear pressure of the clutch cylinder is connected to the chamber of the coupling clutch via a first variable-displacement solenoid valve which is connected to the supply tank via a second fixed-rate solenoid valve the front pressure chamber of the synchronizing cylinder is connected to a chamber of the multi-disk clutch in a direct manner and is connected to the supply tank via a second non-return valve, and the rear pressure chamber of the synchronization cylinder is connected to the chamber of the multidisc clutch via a third variable-displacement solenoid valve and is connected to the supply tank; via a fourth fixed-rate solenoid valve; the front pressure chamber of the clutch cylinder is connected to a chamber of the coupling clutch in a direct manner and is connected to a supply tank via a first fixed-rate solenoid valve, and the front pressure chamber of the synchronizing cylinder is connected to a chamber of the multi-disk clutch via a second fixed-rate solenoid valve and is connected to the supply tank both via a non-return valve and a third fixed-rate solenoid valve; the hydraulically-controlled transmission comprises a pressure limiter which is arranged upstream of the hydraulic coupling clutch; the electro-hydraulic actuator comprises a single jack whose controlled piston is actuated by an electric motor; the front pressure chamber of the cylinder is connected to the chamber of the coupling clutch via a first fixed-rate solenoid valve, to a chamber of the multi-plate clutch via a second solenoid valve to fixed flow rate, and to a feed tank both via a check valve and a third regulated-rate solenoid valve; the hydraulically-controlled transmission comprises at least two multi-plate clutches whose respective chambers are capable of being selectively connected to a source of hydraulic pressure via a solenoid valve with a slide; - The hydraulically controlled transmission comprises central control unit of the solenoid valves and the electro-hydraulic actuator; the hydraulically controlled transmission comprises a pressure sensor which transmits to the central unit information representative of the pressure upstream the multi-disc hydraulic clutch for the electric motor control associated with the electro-hydraulic actuator for controlling the solenoid valves.

Other features and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the accompanying drawings in which - Figure 1 is a schematic view of a powertrain comprising a transmission to hydraulic control according to the invention comprising a coupling clutch and a multi-disk clutch; - Figure 2 is a schematic view of a powertrain comprising a hydraulically controlled transmission according to the invention comprising a coupling clutch and two multi-plate clutches; FIG. 3 is a schematic view of a first embodiment of a hydraulic control circuit of the actuators of the coupling clutch and the multi-disc clutch of the hydraulically controlled transmission of the figure; FIG. 4 is a diagrammatic view of a second embodiment of a hydraulic circuit controlling the actuators of the coupling clutch of the multi-disc clutch of the hydraulically-controlled transmission of FIG. 1; FIG. 5 is a diagrammatic view of a third embodiment of a hydraulic circuit which controls the actuators of the coupling clutch of the multi-disc clutch of the hydraulically controlled transmission of FIG. 1; FIG. 6 is a diagrammatic first embodiment of a hydraulic circuit which controls the actuators of the coupling clutch of the multi-disc clutches of the hydraulically controlled transmission of FIG. 2; FIG. 7 is a diagrammatic view of a second embodiment of a hydraulic circuit controlling the actuators of the coupling clutch and multi-disc clutches of the hydraulically-controlled transmission of FIG. 2; and FIG. 8 is a diagrammatic view of a third embodiment of a hydraulic control circuit of the coupling clutch actuators and multidisk clutches of the hydraulically controlled transmission of FIG. 2.

In the following description, like reference numerals designate like parts or having similar functions.

Moreover, by convention, the term "front" will designate position to the left of the figures, the term "back" will refer to the position to the right of the figures, the word "go" will refer to a movement from the right to the left of the figures, and the term "return" will designate a movement from left to right figures.It is shown in Figure 1 the assembly of a powertrain 10 motor vehicle comprising a motor 14 which coupled a transmission 12 hydraulically controlled according to the invention.

In a known manner, the hydraulically controlled transmission 12 comprises a coupling clutch 16 of which, for example, at least one movable plate 18 is coupled to an output shaft of the engine 14, and of which at least one fixed lining 22 is coupled to a primary shaft 22 of a gearbox 26 of the transmission 10. The coupling clutch 16 is movable between a closed position, that is to say engaged, in which its plate 18 is attached to the lining 22 to transmit a driving power of the motor 14 to the primary shaft and an open position, ie disengaged, in which its plate 18 is disjoint from its lining 22 so as to interrupt the transmission of its driving power.

The coupling clutch 16 comprises a hydraulic actuator 25 whose piston 27, integral with the plate 18, is movable in a chamber 28 of said actuator 25 between an inactive position in which it does not urge the plate 18, the clutch 16 being closed , and an active position in which it spreads the plate 18 of the seal 22 to open the clutch 16. In the absence of hydraulic pressure, the piston 27 is resiliently returned to the inactive position in the chamber 28 by a return spring 30 .

In known manner, the gearbox 26 comprises a secondary shaft 32 is parallel to the primary shaft 24. Between these two shafts and 32 are arranged at least two gears 34 and 36 of transmission whose idler gears 38 and 40 are capable of selectively clutched by a dog clutch device 42 to determine gear ratios of the gearbox, and at least one gear 44 for synchronization, of which an idler gear 45 is likely to be connected to the shaft which carries it by Intermediate clutch 46 hydraulic multidiscs. The idler gear 44, for example and without limitation of the invention, carried the secondary shaft 32, and the clutch clutch 46 associated for example a multi-disk clutch. The coupling clutch 46 comprises a hydraulic actuator 48 whose piston 50, integral with a plate 52, is movable in chamber 54 of said actuator 56 between an inactive position in which it does not urge the plate 52 against the disks 54 of the clutch, the clutch 46 being open, that is to say loosened, and an active position in which it presses the plate 52 against the disks 54 to close, that is to say clamp, the clutch 46. In the absence of hydraulic pressure, piston 50 is resiliently returned to the inactive position in chamber 54 by a return spring 56.

The hydraulic actuator 25 of the coupling clutch 16, the hydraulic actuator 48 of the multi-disk clutch, and the device 42 of interconnection are controlled transmission control unit 58. In particular, the control unit 58 controls the operation of a hydraulic circuit 60 which is intended to distribute the hydraulic pressure between the hydraulic actuator 25 of the clutch 16 of coupling and the hydraulic actuator 48 the clutch 46 Array. The associated hydraulic circuit 60 will be described with reference to FIGS. 3 to 5.

In known manner, during a gear change, the drive control unit 58 controls the clamping of the multi-disc clutch 48 to deflect the driving torque of the transmission gear 34 or 36 associated with the current transmission ratio to the gear 44 synchronization. Then, the transmission control unit 58 controls the interconnection device 42 to disengage the transmission ratio. Then the control unit 58 of the transmission controls the clamping the multi-disk clutch to synchronize together in rotation the primary shaft 24 and the secondary shaft 32. Finally, the control unit 58 of the transmission controls the interconnection device to engage the gear ratio associated with the other transmission gear 36 or 34.

According to the invention, the hydraulic circuit comprises a single source of hydraulic pressure which is capable of selectively supplying the coupling and multi-disc hydraulic clutches via associated controlled solenoid valves.

Figures 3 to 5 illustrate first, second and third embodiments of the hydraulic circuit 60.

In each of these circuits 60, the single hydraulic pressure source is an electro-hydraulic actuator 62 comprising at least one hydraulic cylinder in which a controlled piston, which is actuated via an electric motor 64, defines a chamber front pressure and a rear pressure chamber.

More particularly, according to a first embodiment is shown in Figure 3, the electro-hydraulic actuator comprises a clutch jack 66 and a synchronizing jack 68, the respective pistons 70 and 72, respectively, secured to one of the other, are actuated by a common electric motor 64. The pistons 70 and 72 may, for example, be integral in translation with a rod 73 of common cylinder which is driven by the electric motor 64 via a system for transforming a rotation system into a linear motion, in particular a system for wheel and worm or a screw and nut system (not shown).

In this way the controlled piston 70 delimits in a chamber of the clutch jack 66 a front pressure chamber 76 and a rear pressure chamber 78. In a similar manner, the controlled piston 72 defines in a chamber of the synchronization cylinder 68 a front pressure chamber 80 and a rear pressure chamber 84.

In this first embodiment, the hydraulic circuit 60 is then established as follows - the front pressure chamber 76 of the clutch cylinder is connected to the chamber 28 of the actuator 25 of the coupling clutch in a direct manner and is connected to a supply reservoir 86 via a first non-return valve 88, the rear pressure chamber of the clutch cylinder 66 is connected to the chamber of the actuator 26 of the coupling clutch 16 via a first variable-flow solenoid valve 90 and connected to the supply tank 86 via a second solenoid valve 92 with a fixed flow rate, the front pressure chamber 80 of the synchronizing jack 68 is connected to the chamber 54 of the actuator 48 of the clutch 46 multidiscs directly and is connected to the supply reservoir 86 via a second check valve 94 of non-return, and - Chamber 84 The rearward pressure of the synchronizing jack 68 is connected to the chamber 54 of the actuator 48 of the multi-disk clutch 46 via a third variable-flow solenoid valve 96 and is connected to the supply tank 86 by means of a third valve. intermediate of a fourth solenoid valve 98 fixed flow.

Furthermore, the clutch and synchronization cylinders advantageously comprise respective additional pistons 100 and 102, referred to as capacity, which are respectively arranged in each front pressure chamber 76, 80. The pistons 100 and 102 are each resiliently biased by a associated calibrated spring 104, 106 attached to the piston 70 and 72 controlled associated so as to delimit between the controlled piston 70, 72 and the capacity piston 100, 102 chamber 103, 105 associated said capacity, which is connected supply reservoir 86 and which is intended to maintain a constant pressure in the front pressure chamber 80 during the movements of the controlled piston 70,72. pistons 100 and 102 are guided on the rod 74 and are respectively pushed by the springs 104 and 106. The pistons 102 are stopped axially on the rod 74 so that there is always a force on the pistons which is produced the springs 104 and 106 .

In addition, the hydraulic circuit 60 comprises a pressure sensor 107 which transmits to the central unit 58 information representative of the pressure upstream of the multi-disc hydraulic clutch for controlling the electric motor 64 associated with the electromagnetic actuator 62. hydraulic and for controlling the solenoid valves 90, 92, 96, 98.

In this configuration, the hydraulic circuit 60 and the transmission 26 previously described are likely to be controlled by the transmission control unit 58 according to several modes of operation.

Initially, the hydraulic circuit 60 is in the rest position. The pistons 70 and 72 of the electro-hydraulic actuator 62 are in the rear position. The oil volumes available in the front chamber 76 of the cylinder 66 and in the front chamber 80 of the cylinder 68 are maximum. The hydraulic actuator 25 coupling clutch 16 and the hydraulic actuator of the multi-disc clutch 48 are in the retracted position. The coupling clutch 16 is closed and the multi-disk clutch 46 is open.

When it is desired to start the vehicle from an initial stopping position in which the box 26 is in neutral, it is first necessary to open the coupling clutch 16, then to rattle a report of the box 26, then to close again the coupling clutch 16. this effect, the solenoid valves 90 and 98 are closed, while the solenoid valves 92 and 96 are open. Then the motor is controlled so that the electro-hydraulic actuator 62 is turned on in the forward direction, ie from the right to the left of FIG. 3. In this way, the oil contained in the chamber before 76 of the cylinder 66 travels to the chamber 28 of the hydraulic actuator 25 of the clutch 16 coupling which opens gradually. At the same time, the oil contained in the cylinder 68 passes from its front chamber 80 to its rear chamber 84 without causing movement of the clutch 46 multidiscs.

that the coupling clutch 16 is open, the motor of the electro-hydraulic actuator 62 is stopped.

The transmission control unit 58 then controls the dog clutch device 42 to obtain the engagement of a gear, for example by engaging the idler gear 38 previously described.

To close the coupling clutch 16 again, the unit 58 controls the closing of the solenoid valves 90 and 98 while the solenoid valves 92 and 96 remain open. The motor 64 of the electro-hydraulic actuator 62 is controlled so that the electro-hydraulic actuator 62 is started in the return direction, ie from the left to the right of FIG. of the clutch 16 obtained by regulating the speed of the motor 64 of the electro-hydraulic actuator 62, and the vehicle can start. At the same time, the oil contained in the cylinder 68 passes from its rear chamber 84 to its front chamber 80 without movement of the clutch 46 multidiscs.

Then, the unit 58 controls the return of the electro-hydraulic actuator 62 by controlling the closing of the solenoid valves 92 and 98, and the starting of the motor of the electro-hydraulic actuator 62 in the return direction. In this case, the oil contained in the rear chambers 78 and 84 passes into the front chambers 76 and 80. The additional oil in the front chambers 76 and 80 is made by suction through the non-return valves 88 and 94.

Finally, the electro-hydraulic actuator 62 is stopped the solenoid valves 92 and 98 are open, the circuit 60 is in the rest position.

When it is desired to switch from a transmission ratio to a higher transmission ratio, it is first necessary to tighten the clutch 46 multidiscs, disengage the current ratio, drive the clutch 46 multi-disc to reach the adequate synchronization speed and cancel the torque passing through the current ratio by deflection, then jab the next report.

To obtain the clamping of the clutch 46 multidiscs, the unit 58 controls the closing of the solenoid valves 92 and 96, the opening of the solenoid valves 90 and 98. Then the electro-hydraulic actuator 62 is turned on in the forward direction. In fact, the oil contained in the jack 68 travels to chamber 54 of the clutch 46 multidiscs which is gradually tightened. The torque of the gear ratio is then diverted to the pinion integral with the clutch 46. The rise in pressure is controlled by the pressure sensor 107. The oil contained in the jack 66 passes from its front chamber 76 to its rear chamber 78 without causing movement of the clutch 16 coupling.

The central unit 58 then controls the interconnection device 42 to disengage the idler gear associated with the current transmission ratio, for example the idler gear 38.

The multi-disc clutch 46 is always driven in order to bring the speed of rotation of the primary shaft 24 to the synchronization speed. As soon as this synchronization speed is reached, the central unit 58 controls the opening of the multi-disk clutch 46 by controlling the closing of the solenoid valves 92 and 96, the opening of the solenoid valves 90 and 98, and then starting the electro-actuator. -hydraulic 62 in the return direction. As a result, the oil contained in the chamber of the actuator 48 of the multi-disk clutch is sucked by the return of the piston 72 of the electro-hydraulic actuator 62, which causes the clutch 46 to be released. The oil contained in the cylinder 66 passes from its rear chamber 78 to its front chamber 76 without movement of the clutch 16 coupling.

The central unit 58 then controls the dog clutch device 42 to engage the idle gear, for example the idle gear 40, associated with the desired gear ratio.

After the interconnection of the desired ratio, the central unit 58 controls the return of the electro-hydraulic actuator 62. For this purpose, the solenoid valves 92 and 98 are closed, while the solenoid valves 90 and 96 are open. The electro-hydraulic actuator 62 is controlled in the return direction, and the oil contained in the rear chambers 78 and 84 cylinders 66 and 68 passes into the front chambers 76 and 80. Additional oil is made by suction through check valves 88 and 94.

The electro-hydraulic actuator 62 is stopped and the solenoid valves 92 and 98 are opened again. The hydraulic circuit 60 is in the rest position.

When it is desired to change from a transmission ratio to a lower transmission ratio, it is first necessary to tighten the multi-disc clutch in order to cancel the torque on the current ratio although to cancel the engine torque. without clutching the clutch disengage the current ratio, bring the primary shaft to the proper speed of synchronization, then jab the next gear.

The hydraulic circuit 60 is controlled in a manner analogous to the case previously described for passing from a current ratio to a ratio of higher rank, with the difference that the primary shaft 24 is brought to the speed of synchronization not by driving the gear. clutch 46 multidiscs, but by restarting the engine 14 of the vehicle. Before restarting the engine speed 14 of the vehicle, it is necessary to loosen the clutch 46, if it had previously been decided to cancel the torque passing through the current ratio by tightening said clutch 46.

It is possible that it is desired to engage a transmission ratio while the vehicle is traveling in neutral in the sense that the report that is desired to engage. This may be the case when one wishes to leave configuration in which it was desired to reduce the maximum engine brake while the vehicle rolled "on its momentum", that it is then desired to restart the vehicle. In this configuration, it is successively necessary to restart the engine so as to accelerate the primary shaft 24 of the box 26, then disengage the coupling clutch 16, drive the clutch 46 multidiscs to achieve the appropriate speed of synchronization of the primary shaft 24, then release the clutch 46 multidiscs, close the desired ratio, close the coupling clutch 16 and finally bring the hydraulic circuit 60 to its rest position.

For this purpose, the gearbox 26 is initially in neutral, the unit 58 first controls the motor 14 so as to accelerate the primary shaft 24. Then it controls the opening of the clutch 16 coupling . For this purpose the unit 58 controls the closing of the solenoid valves 90 and while the solenoid valves 92 and 96 are released.

The electro-hydraulic actuator 62 is then turned on in the forward direction. The oil contained in the jack 66 travels to the chamber 28 of the actuator 25 of the coupling clutch 16 which opens gradually. At the same time, the oil contained in the cylinder 68 passes from its front chamber 80 to its rear chamber 84, without movement the clutch 46 multidiscs. As soon as the coupling clutch is opened, the electro-hydraulic actuator 62 is stopped. The unit 58 controls the closing solenoid valves 92 and while the solenoid valves 90 and are open. The electro-hydraulic actuator 62 is then restarted in the forward direction. As a result, the oil contained in the jack 68 travels towards the multidisc clutch 46 which is progressively tightened, the rise in pressure being controlled by the pressure sensor 107.

This produces the synchronization in speed of the primary shaft 24 by means of the clutch 46 multidiscs. At the same time, the oil contained in the jack 66 passes from its front chamber 76 to its rear chamber 78 without movement of the clutch 16 coupling. The pressure allowing the opening of the coupling clutch 16 is maintained thanks to the spring 104 of the piston 100 of capacity which is in the front chamber 76 of the cylinder 66. As soon as the synchronization speed of the primary shaft 24 is reached , the unit 58 controls the closing of the solenoid valves 92 and 96 and the opening of the solenoid valves 90 and 98 and then actuating the electro-hydraulic actuator 62 in the direction of the return direction. The oil contained in the cylinder 66 passes from its rear chamber 78 to its front chamber 76 without movement of the clutch 16 coupling. The oil contained in the chamber 54 of the hydraulic actuator 48 the clutch 46 multidiscs is sucked by the return of the piston 102 of the cylinder 68, which leads the clutch 46 multidiscs to loosen.

The unit 58 then controls the interconnection idler gear of the secondary shaft, for example the idler Then the unit 58 controls the closing of the solenoid valves 90 and 98, the opening of the solenoid valves and 96, then the starting the electro-hydraulic actuator in the return direction. The oil contained in the cylinder 68 passes from its rear chamber 84 to its front chamber 80 without movement of the clutch 46 multidiscs. This causes the clutch 16 to close. Slippage of the coupling clutch is obtained by regulating the speed of the motor of the electro-hydraulic actuator 62. The vehicle is then driven by the motor 14 and the transmission 26.

Finally, the unit 58 controls the return of the electro-hydraulic actuator 62. For this purpose, the solenoid valves 92 and are closed, the solenoid valves 90 and 96 are open, the electro-hydraulic actuator 62 is started in direction return. The oil contained in the rear chambers and 84 cylinders 66 and 68 at the rear passes into the front chambers 76 and 80. The oil is supplemented by suction through check valves 88 and 94. The hydraulic circuit 60 is then returned to the rest position, all solenoid valves 90, 92, 96, 98 being open.

It is possible that it is desired to engage a transmission ratio while the vehicle is traveling in neutral in a direction opposite to that associated with the report that it is desired to engage. In this case, as for a vehicle equipped with a conventional transmission, it is necessary to bring the vehicle to a standstill.

case of failure of the unit 58, all the solenoid valves 90, 96, 98 are open. The cylinders 66, 68 and the hydraulic actuators 25 and 48 are thus placed in communication with the feed tank 86, which allows them to return to their initial rest position.

In a similar manner to the first embodiment shown in FIG. 3, the hydraulic circuit 60 can be made according to a second embodiment, represented in FIG. 4, in which the electro-hydraulic actuator comprises a jack 66 of a clutch and a synchronizing jack 68, the respective pistons 70 and 72 of which are secured to one another, are actuated by a common motor. Pistons 70 and 72 may, for example, be integral in translation with a rod 74 of common jack which drives via an electric motor 64 and through a system for transforming a rotational movement into linear motion, especially a wheel system and * endless, or screw and nut (not shown).

In this way, the pistons 70 and 72 controlled respectively define a front pressure chamber 76 in the clutch jack 66 and a front pressure chamber 80 in the jack 68.

In this second embodiment, the hydraulic circuit 60 is then established as follows - the front pressure chamber 76 of the clutch cylinder is connected to a chamber 28 of the actuator 25 of the clutch 16 coupling directly and it is connected to a supply tank 86 via a first solenoid valve 108 with fixed flow, and the front pressure chamber 80 of the synchronization cylinder 68 is connected to a chamber 54 of the actuator of the clutch 46 multidiscs via a second solenoid valve 110 with a fixed flow rate and is connected to the supply reservoir 86 at the same time via check valve 112 and a third solenoid valve 1 with a fixed flow rate.

moreover, a pressure limiter 116 is arranged upstream of the actuator 25 of the coupling hydraulic clutch. This pressure limiter 116 is intended to organize a return of oil to the supply reservoir 86 when the pressure upstream of the actuator 25 exceeds the determined threshold.

In addition, the hydraulic circuit 60 comprises a pressure sensor 107 which transmits to the central unit 58 an information representative of the pressure upstream of the multi-disc hydraulic clutch 48, for controlling the electric motor 64 associated with the actuator 62 in this configuration, the hydraulic circuit 60 the transmission 26 described above can be controlled by the control unit 58 of the transmission according to several modes of operation .

In a rest position of the hydraulic system 60, the pistons 100 and 102 of the electro-hydraulic actuator 62 are in the rear position, ie to the right of FIG. 4. oil available in the front chamber 68 of the coupling cylinder 66 and in the front chamber 80 of the synchronization cylinder are maximum. The coupling clutch 16 is closed and the multi-disc clutch 46 is open.

When it is desired to start the vehicle from an initial stop position in which the gearbox 26 is in neutral, it is first necessary to open the coupling clutch 16, then to engage a gear of the box and then close the coupling clutch 16 again.

For this purpose, the unit 58 first controls the closing of the solenoid valve 108, and the opening of the solenoid valves 110 and 114. Then, the electro-hydraulic actuator 62 is turned on in the forward direction, right to the left of Figure 4.

The oil contained in the jack 66 travels towards the coupling clutch 16 which opens progressively while the oil contained in the jack 68 is evacuated towards the tank 86 via the solenoid valve 114. When the coupling clutch 16 is open, the electro-hydraulic actuator 62 is stopped. The unit 58 then controls the interlocking device 42 to engage a gear ratio, for example the first or the second transmission ratio, or the reverse gear ratio. Then the unit 58 controls the opening of the input coupling clutch 16 maintaining the closing of the solenoid valve 108, and the opening of the solenoid valves 110 and 114, and starting the electro-actuator. -hydraulique 62 back from the left to the right of Figure 4. The oil contained in the chamber 26 of the hydraulic actuator 25 of the coupling clutch is sucked by the return of the piston 100, which causes again closes the clutch 16 coupling. The chamber 76 of the jack 66 is filled by suction through the solenoid valve 114 or the check valve 112. The slip of the coupling clutch 16 is obtained by regulating the return speed of the motor 64 of the actuator electro-hydraulic 62.

If the actuator 62 is not completely returned to position, the unit 58 controls the opening of the solenoid valves 110, 114, and 108, and then the electro-hydraulic actuator is turned back. The additional oil chambers 76 and 80 of the cylinders 66 and 68 of the actuator is made by suction through the solenoid valves 110, 114, and when it is desired to change from a transmission ratio to a transmission ratio of rank higher, is first necessary to tighten the clutch 46 multidiscs, disengage the current ratio, drive the clutch 46 multidiscs to achieve the appropriate speed of synchronization, then craboter the following report.

For this purpose, the unit 58 controls the clamping of the multi-disk clutch 46 by controlling the closing of the solenoid valve 114 and the opening of the solenoid valves 108 and 110. Then the electro-hydraulic actuator 62 is turned on in the sense to go. The oil contained in the jack 68 travels to chamber 54 of the hydraulic actuator 48 of the multi-disc clutch, which is tightened. At the same time, the oil contained in the jack 66 is evacuated towards the tank 86 via the solenoid valve 108. The clamping of the multi-disk clutch 46 is controlled by the pressure sensor 107.

As soon as the torque is almost canceled on the current ratio, the unit 58 then controls the device 42 of interconnection so that it decrabotes the idler gear associated with the engaged gear ratio, for example the idler gear 38 of the figure. Meanwhile, the multi-disk clutch 46 is always driven to bring the speed of rotation of the primary shaft 24 the appropriate synchronization speed. As soon as the synchronization speed is reached, the unit 58 controls the release of the multi-disc clutch 46 while keeping the solenoid valve 114 closed and the solenoid valves 108 and 1 open and then switching on the electro-hydraulic actuator in the return direction. As a result, the oil contained in the chamber 54 of the hydraulic actuator 48 is sucked by the return of the piston 102, which causes the clutch 46 to disengage. At the same time, the chamber of the coupling jack 66 is filled by suction through the solenoid valve 114.

The unit 58 then controls the interconnection device 42 to engage the idle gear associated with the desired transmission ratio, for example the idle gear 40 of FIG. 1.

If the actuator 62 is not fully returned to position, the unit 58 controls its return by controlling the opening of the solenoid valves 108, 110, and 114, and then controlling the operation of the electrohydraulic actuator in the direction return. The additional oil of the chambers 76 and 80 of the actuator is made by suction through the solenoid valves 108, 110, and 114.

When it is desired to change from a transmission ratio to a lower transmission ratio, it is first necessary to tighten the multi-disc clutch 46 or to cancel the engine torque without tightening the clutch in order to cancel the transmission. torque on the current ratio, decelerate current ratio, bring the primary shaft 24 to the appropriate speed of synchronization, then dog the next report.

The hydraulic circuit 60 is controlled in a manner analogous to the case previously described for the passage from a current ratio to a higher gear ratio, with the difference that the primary shaft 24 is brought to the speed of synchronization not in driving the clutch 46 multidiscs, but by restarting the engine 14 of the vehicle. Before restarting the engine 14 of the vehicle, it is necessary to loosen the clutch 46, if it had been chosen to cancel torque by tightening it.

It is possible that one wishes to engage transmission ratio while the vehicle is traveling in neutral in the same direction as the report that is desired to engage. In this configuration, it is successively necessary to restart the engine so as to accelerate the primary shaft 24 of the box 26, then open the coupling clutch 16, drive the clutch 46 multidiscs to achieve the appropriate speed of synchronization of the primary shaft 24, then release the clutch 46 multidiscs, clutch the desired ratio, close the coupling clutch 16 and finally bring the hydraulic circuit 60 to its rest position.

To perform this series of operations, starting from the situation in which the gearbox 26 is in neutral, the unit 58 first controls the engine restart 14 so as to accelerate the speed of rotation of the primary shaft 24 Then, to open the coupling clutch 16, the unit 58 controls the closing of the solenoid valve 108 and the opening of the solenoid valves 110 and 114. The electro-hydraulic actuator 62 is then turned on in the opposite direction. go. As a result, the oil contained in the front chamber 76 of the jack 66 travels towards the coupling clutch 16 which opens progressively, while at the same time the oil contained in the chamber 80 of the jack 68 is discharges to the reservoir 86 via the solenoid valves 114 and 108.

As soon as the coupling clutch 16 is open, the motor 64 of the electro-hydraulic actuator 62 is stopped. The unit 58 then controls the clamping of the multi-disk clutch 46 to synchronize the speed of the primary shaft 24. To this end, the unit 58 controls the closing solenoid valves 114 and 116 and the opening of the solenoid valve 1 and then the actuation of the electro-hydraulic actuator in the forward direction so that the oil contained in the chamber 80 of the jack 68 travels towards the chamber 54 the hydraulic actuator 48 of the clutch 46 multidiscs that the oil contained in the chamber 76 of the coupling cylinder is evacuated to the reservoir 86 through pressure limiter 116. In this time, the multi-disk clutch is controlled by the pressure sensor 107.

As soon as the synchronization speed of the primary shaft 24 is reached, the unit 58 controls the release of the multi-disk clutch 46 by controlling the closing of the solenoid valve 108, and the opening of the solenoid valves 114 and 11 thereby, the pressure of the circuit is evacuated naturally to reservoir 86.

The unit 58 then controls the interconnection device 42 to engage an idle gear, for example the idler gear 38, the secondary shaft 32.

Then the unit 58 controls again closing the clutch 16 coupling. For this purpose, the unit controls the closure of the solenoid valve 108 and the solenoid opening 110 and 114 while the electro-hydraulic actuator 62 is turned on in the return direction. this fact, the oil contained in the chamber 28 of the actuator of the clutch 16 coupling is sucked by the return of the piston 100, which causes the coupling clutch 16 to close, the vehicle then being driven by the motor 14. At the same time, the chamber 80 of the synchronization jack 68 is filled by suction through the solenoid valve 114.

The slippage of the coupling clutch 16 is obtained by controlling the return speed of the electro-hydraulic actuator 62. Finally, if the actuator 62 is not completely returned to position, the unit 58 controls its return by opening the solenoid valves 110, 114, and 108, then controlling the start of the electro-hydraulic actuator 62 in the sense of return. The additional oil chambers 76 and 80 of the actuator is then sucked through solenoid valves 108 and 114.

It is possible that it is desired to engage a transmission ratio while the vehicle is traveling in neutral in a direction opposite to that associated report that is desired to engage. In this case, as for a vehicle equipped with a conventional transmission, it is necessary to bring the vehicle to a standstill.

In case of failure of the unit 58, all the solenoid valves 110, 114, 108 are open. jacks 66, 68 and the hydraulic actuators 25 are thus placed in communication with the supply tank, which allows them to return to their original rest position.

According to a third embodiment of the invention shown in FIG. 5, the circuit 60 may comprise an electro-hydraulic actuator 1 equipped with a single jack 120 whose controlled piston 122 is actuated by an electric motor 124. The piston 122 delimits inside the cylinder 120 a front pressure chamber In this configuration, the front pressure chamber 126 of the cylinder 120 is connected to the chamber 28 of the actuator 25 of the coupling clutch 16 via a first solenoid valve 128 with a fixed flow rate, to the chamber 54 of the actuator 48 of the multidisc clutch 46 via a second solenoid valve 130 with a fixed flow rate, and to a supply reservoir 86 at a time by means of intermediate of a non-return valve 132 and a third solenoid valve 134 at a controlled rate. In addition, the hydraulic circuit 60 comprises a pressure sensor 136 which transmits to the central unit 58 information representative of the pressure upstream of the multi-disc clutch 48 and / or the coupling clutch, for steering of the electric motor associated with the electro-hydraulic actuator 118 and for controlling the solenoid valves 128, 130 and 134.

In this configuration, the hydraulic circuit 60 and the transmission 26 previously described may be controlled by the transmission control unit 58 according to several modes of operation: Initially, in the rest position of the hydraulic circuit 60, the piston 122 the electro-hydraulic actuator 118 is in the rear position, ie to the right of Figure 5. In this way, the volume of oil available in the front chamber 126 is maximum.

The actuators 25 and 48 of the two coupling clutches 16 and 48 multidiscs are in the retracted position. Thus the coupling clutch 16 is closed and the clutch 46 is open.

When it is desired to start the vehicle from an initial stopping position in which the box 26 is in neutral, it is first necessary to open the clutch coupling 16, then to engage a dog. report of the box 26, then to close again the coupling clutch 16.

To perform this series of operations, the gearbox 26 being in neutral, the unit 58 controls the closing of the solenoid valves 130 and 134, and the opening of the solenoid valve 128. Then the unit 58 controls the implementation. operating the electro-hydraulic actuator 118 in the forward direction. As a result, the oil contained in the front chamber 126 of the jack 120 travels towards the chamber 28 of the actuator 25 of the input clutch 16 which opens progressively. The actuator of the multi-disc clutch 46 is not powered.

that the coupling clutch 16 is open, the electro-hydraulic actuator 118 is stopped. The unit 58 then controls the jaw clutch device 42 to jerk crazy gear, for example the idler gear 38, which is associated with reduced gear ratio, including the first gear ratio, second gear or reverse gear.

Then the unit 58 again controls the clutch of the coupling clutch 16 by controlling the closing solenoid valves 130 and 134, the opening of the solenoid valve and the starting of the electro-hydraulic actuator 18 in the sense of return. In this way, the oil contained in chamber 28 of the actuator 25 of the clutch 16 coupling is sucked by the return of the piston 122, which causes again the closing of the clutch 16 coupling.

The slippage of the coupling clutch 16 is obtained by regulating the speed of the motor 124 of the actuator 1 during the return of the electro-hydraulic actuator 118.

If the actuator 118 is not fully returned position, the unit 58 controls the return thereof by opening the solenoid valves 128 and 130 and closing the solenoid valve and starting the electro-hydraulic actuator 1 in the sense of return. The oil supplement of the chamber 126 of the actuator 118 is then made by suction.

The additional oil of the chambers of the actuator is made by suction through the solenoid valve 134 and the nonreturn valve 132. When it is desired to change from a transmission ratio to a higher transmission ratio, it is necessary to first necessary to tighten the clutch 46 multidiscs, disengage the current ratio, drive the clutch 46 multi-discs to achieve the appropriate speed of synchronization, then craboter the following report.

To control the clamping of the multi-disk clutch 46, the unit 58 controls the closure of the solenoid valves 128 and 134, the opening of the solenoid valve 130, and then starts the electro-hydraulic actuator 118 in the one-way direction. . As a result, the oil contained in the front chamber 126 of the cylinder 120 travels towards the chamber 54 of the actuator 48 of the multidisc clutch 46 which is tightened. Clutching the multi-disc clutch 46 is controlled by pressure sensor 136. At the same time, the coupling clutch is not energized.

When the torque of the current ratio considered is deflected by the idler gear secured to the clutch the unit 58 then controls the device 42 of interconnection so that it decrabote idler gear associated with the transmission gear engaged, for example the idler gear 38.

The multi-disk clutch 46 is always driven by the unit in order to bring the speed of the primary shaft 24 to the appropriate synchronization speed.

As soon as the synchronization speed is reached, the unit 58 controls the loosening of the multi-disk clutch 46 by controlling the closing of the solenoid valves 128 and 134, and the opening of the solenoid valve 130, then starting the electro-actuator. -hydraulic 118 in the direction of return. As a result, the oil contained in the chamber 54 of the actuator 25 of the clutch is sucked by the return of the piston 122, which leads to the opening of the clutch 46 multidiscs. The unit 58 then controls the interconnection device so that it crabote the idler gear associated with the desired ratio, for example the idle gear 40.

If the actuator 118 is not fully returned to position, the unit 58 controls the return of the one 'by opening the solenoid valves 128 and 130 and closing the solenoid valve 134, then switching on the electro-hydraulic actuator 118 in the sense of return. The oil supplement of the chamber 126 of the actuator 118 is then made by suction.

When it is desired to change from a transmission ratio to a lower transmission ratio, it is first necessary to tighten the multi-disc clutch 46 or to cancel the engine torque in order to cancel the torque on the current ratio, Disengage the current ratio bring the primary shaft to the proper speed of synchronization, then lower ratio jabber.

hydraulic circuit 60 is controlled in a manner analogous to the previously described case for passing from a current ratio to a higher gear ratio, with the difference that the primary shaft 24 is brought to the speed of synchronization not by driving the clutch 46 multidiscs, but by restarting the engine 14 of the vehicle. Before restarting the motor 14, it is necessary to loosen the clutch 46 if it had been previously tightened to cancel the torque on the current ratio.

It is possible that it is desired to engage a transmission ratio while the vehicle is traveling in neutral in the same direction as the report that is desired to engage. In this configuration, it is successively necessary to restart the engine so as to accelerate the primary shaft 24 of the box 26, then open the coupling clutch 16, drive the clutch 46 multidiscs to achieve the appropriate speed of synchronization of the primary shaft 24, then release the clutch 46 multidiscs, close the desired ratio, then close the coupling clutch 16 and finally return the hydraulic circuit 60 to its rest position.

To perform this series of operations, starting from the situation in which the gearbox is in neutral, the unit 58 first controls the engine restart 14 so as to accelerate the speed of rotation of the primary shaft 24 Then, to open the coupling clutch 16, the unit 58 first controls the opening of the solenoid valve 128 and the closing of the solenoid valves 130 and 134, then the start of the electro-hydraulic actuator. 118 in the forward direction. As a result, the oil contained in the chamber 128 of the jack 120 travels towards the chamber 28 of the actuator 25 of the coupling clutch 16 which opens progressively. Meanwhile, the multi-disc clutch 46 is not powered. As soon as the coupling clutch 16 is disengaged, the electro-hydraulic actuator 118 is stopped.

Then the unit 58 controls the clamping of the clutch 46 multidiscs by closing the solenoid valves 128 and 134 and opening the solenoid valve 130. The electro-hydraulic actuator 118 is restarted in the forward direction, this brings the oil contained in the chamber 126 of the cylinder 120 to move to the chamber 54 of the actuator 48 of the clutch 46 multidiscs to cause its clamping. In this time, the clutch 16 coupling is not powered. The clamping of the multi-disc clutch 46 is controlled by the pressure sensor 36.

once the synchronizing speed the primary shaft 24 is reached, the unit 58 controls the loosening of the multi-disk clutch by closing the solenoid valves 128 and 134, opening the solenoid valve 130 and then turning on the electro-hydraulic actuator 118 in the sense of return. As a result, the oil contained in the chamber 54 of the actuator 48 is sucked by the return of the piston 122, which leads to the loosening of the clutch 46 multidiscs. Then the unit 58 controls the dog clutch device 42 for synchronizing an idle gear of the secondary shaft 32, for example the idler pinion 40. Finally, the unit 58 controls the closing of the coupling clutch 16 by closing the solenoid valves. 130 and 134, opening the solenoid valve 128, then by switching on the electro-hydraulic actuator 118 in the return direction. The oil contained in the chamber 28 of the actuator 25 is sucked by the return of the piston 122, which leads to the closing of the clutch 16 coupling.

Skidding is achieved by regulating the return speed of the motor 124 of the electro-hydraulic actuator 118.

If the electro-hydraulic actuator 118 is completely returned to position, the unit 58 controls its return by opening the solenoid valves 128 and 130, closing the solenoid valve and then turning on the electro-hydraulic actuator 1 in the sense of return. The oil supplement of the chamber 126 of the actuator 118 is sucked through the nonreturn valve 132.

It is possible that it is desired to engage a transmission ratio while the vehicle is traveling in neutral in a direction opposite to that associated with the report that wishes to engage. In this case, as for a vehicle equipped with a conventional transmission, it is necessary to bring the vehicle to a standstill.

In case of failure of the unit 58, all the solenoid valves 128, 130, 134 are open. The actuators and 48, and the electro-hydraulic actuator 118 is placed in communication with the supply reservoir 86, which allows circuit 60 to return to its initial rest position.

The previously described arrangements, comprising a single clutch 46 multidiscs are not limiting of the invention. Indeed, as described in FIG. 2, the gearbox 26 may be a gearbox similar to the box 26 previously described, but including, in addition, the first secondary shaft 32 comprising elements similar to those previously described with reference to FIG. Figure 1, second secondary shaft 33.

In known manner, the second secondary shaft 33 is parallel to the primary shaft 24. Between these two shafts 24 and 33 are arranged at least two gears 35 and 37 transmission whose idler gears 39 and 41 are likely to be selectively clutched by a device 43 for interconnection to determine associated gear ratios of the gearbox, and at least one synchronization gear 47, including a pinion 49 is likely to be connected to the secondary shaft 33 which carries it through a second clutch 51 hydraulic multidiscs. The second clutch 51 associated with the idler gear 49 is for example a multi-disk clutch.

The coupling clutch 51 comprises a hydraulic actuator 53 including a piston 55, integral with a plate 61, movable in a chamber 59 of said actuator 53 between inactive position in which it does not urge the plate 61 against disks 63 of the clutch 51, the clutch 53 being released, and an active position in which it presses plate 61 against disks 63 to tighten the clutch In the absence of hydraulic pressure, the piston 55 is resiliently returned to the inactive position in chamber 59 by return spring 65.

The hydraulic actuator 25 of the coupling clutch 16, the hydraulic actuator 48 of the first clutch 46 multidiscs, the hydraulic actuator 53 second multi-disk clutch and the devices 42 and 43 interconnection are controlled by the control unit 58. transmission. In particular, the control unit 58 controls the operation of a hydraulic circuit 60 which is intended to distribute the hydraulic pressure between the hydraulic actuator 26 of the coupling clutch 16 and the hydraulic actuators 48 and 53 of the clutches. 46 and 51 multidiscs.

In known manner, during a gear change associated with the second secondary shaft 33, the unit 58 controls the transmission activates the second multi-disk clutch to deflect the engine torque of the transmission gear 37 associated with the current transmission ratio. to the synchronization gear 47. Then, the control unit 58 of the transmission controls the device 43 interconnection to disengage the transmission ratio. Then the transmission control unit 58 controls the clamping of the multi-disk clutch 53 to synchronize together in rotation the primary shaft 24 and the second secondary shaft 33. Finally, the control unit 58 of <B> 1 < Transmission transmits the clutch device 43 to engage the gear ratio associated with the other transmission gear 37 or 35.

Preferably, one of the multi-disk clutches 46 is associated with the idler gear of the highest gear ratio ratio of the gearbox, and the other is associated with the idler gear of the lowest gear ratio of the gearbox. . The multi-disk clutch associated with the highest gear ratio gear ratio of the gearbox to ensure the synchronization of the shaft the door to deflect the torque of the current ratio, while the multi-plate clutch associated with the crazy gear ratio gear ratio The lowest rank is more specifically intended to deflect the torque and accelerate the speed of rotation of the primary shaft 24 during the descent of the reports.

The corresponding hydraulic circuits 60 are shown in FIGS. 6 to 8.

The hydraulic circuits 60 of Figures 6 and 7 are similar to the hydraulic circuits of Figures 3 and 4; with the difference that they comprise a slide solenoid valve arranged upstream of the clutches 46 and 51 multidiscs, to distribute the hydraulic pressure between the chamber 54 of the actuator 48 of the first clutch 46 multidiscs chamber 59 of the actuator 53 of the second clutch multidiscs.

Depending on the secondary shaft that is desired to synchronize, the unit 58 controls the solenoid valve drawer 138 to allow the flow of oil to the desired clutch 46 or 51 multidiscs.

The hydraulic circuit 60 of FIG. 8 is similar to the hydraulic circuit 60 of FIG. 5, with this difference comprises a fourth solenoid valve 140 with fixed flow which is connected to the front chamber 126 of the cylinder 120. This fourth solenoid valve 140 is intended to supply the chamber 59 of the actuator 53 of the second multi-disk clutch.

According to the tree that wishes to synchronize, the unit 58 controls one or the other solenoid valves 130 or 140 with fixed flow, respectively for the supply of the first clutch 46 multidiscs of the second clutch 51 multidiscs.

In a variant (not shown), the circuit 60 of FIG. 8 could not comprise a fourth fixed-rate solenoid valve 140, but could include a solenoid valve with a solenoid valve type 138 of the type described, referring to FIGS. 6 and 7, which would be arranged downstream. of the solenoid valve 130 and which would allow the selective distribution of the hydraulic pressure between one or the other of the first multi-disc clutch 46 or the second multi-disc clutch 51.

It will be understood in a variant (not shown), the gearbox 26 may comprise a secondary shaft carrying two multi-plate clutches associated with two pairs of associated gears.

It will also be understood that the control of the device 42 for interconnection may not be ensured by the control unit 58, but may be actuated by a conventional manual gearshift device, without restricting the scope of the invention.

The invention therefore advantageously makes it possible to obtain a simple hydraulic control for a semi-automated or fully automated box. Such an automated box, called "robotic" box, comprising many common hydraulic members for actuating the coupling clutch 16 or clutches 46, 51 is inexpensive to manufacture and a simplicity that guarantees its reliability.

Claims (12)

<U> CLAIMS </ U> 1. Transmission (1 with hydraulic control for a motor vehicle, of the type which comprises a gearbox (26) which can be selectively coupled to a motor (14) of the vehicle via a clutch (16) hydraulic coupling member and which comprises a primary shaft (24) and at least a secondary shaft (32, 33), parallel to the primary shaft (24), between which are arranged at least two gears (34, 35, 36, 37). transmission gear whose idle gears (38, are likely to be selectively engaged to determine associated gear ratios of the gearbox, and of the type which comprises at least one synchronization gear (44), arranged between the primary shaft (24), ) and the secondary shaft (32, 33), whose idle gear (45, 49) is capable of being connected to the shaft (32, 33) which carries it via a clutch (46, 51), in particular to deflect the driving torque of the gear (34, 35, 36, transmission associated with the current transmission ratio to the synchronization gear (46, 51) before disengagement of said transmission ratio, and to synchronize together in rotation the primary shaft (24) and the secondary shaft (32, 33). ) prior to engaging the gear ratio associated with the other transmission gear (34, 35, 36, 37), characterized in that it comprises a single hydraulic pressure source is capable of selectively supplying the coupling hydraulic clutches (16) and multidiscs (46, via associated solenoid valves (90, 92, 96, 98, 110, 14, 116, 128, 130, 134, 138, 140). 2. Transmission (12) hydraulically controlled according to the preceding claim, characterized in that the single hydraulic pressure source is an electro-hydraulic actuator (62, 118) having at least one hydraulic cylinder (66, 120) in which a piston (70, 72, 122) which actuates via an electric motor 124), defines a front pressure chamber (76, 80, 126) and a rear pressure chamber (78, 84). 3. Transmission (12) hydraulically controlled according to the preceding claim, characterized in that the electro-hydraulic actuator (62) comprises a clutch jack (66) a synchronizing jack (68) whose pistons ordered (70, 72 ), integral with each other, are actuated by a common electric motor (64). 4. transmission (12) hydraulically controlled according to the preceding claim, characterized in that the clutch (66) and synchronization cylinders (68) each comprise an additional piston (100, 102), said capacity, which arranged in their front pressure chamber (76, 80) and resiliently biased by a calibrated spring (104, 106) fixed controlled piston (70, 72) so as to delimit between the controlled piston (70, 72) and the capacity piston ( 100, 1 a chamber (103, 105) said capacity connected to the supply tank which is intended to maintain a constant pressure in the front pressure chamber (76, 80) during movements of the controlled piston (70, 72). 5. Transmission (12) hydraulically controlled according to one of claims 3 or 4, characterized in that - the front pressure chamber (76) of the clutch cylinder (66) is connected to a chamber (28) of the coupling clutch (16) directly and is connected to a supply tank (86) via a first non-return valve (88), - the rear pressure chamber (78) of the clutch actuator (66) is connected to the coupling clutch chamber (28) via a first variable-rate solenoid valve (90) and is connected to the supply reservoir (86) by means of a second solenoid valve (92) with a fixed flow rate, the front pressure chamber (80) of the synchronization cylinder (68) is connected to a chamber (54) with the clutch (46) in a direct and it connected supply tank (86) via a second check valve (94), and the chamber of pre rear ssion (84) of the synchronizing jack (68) is connected to the multi-disc clutch chamber (54) through a third variable-flow solenoid valve (96) and is connected to the supply tank (86) via a fourth solenoid valve (98) with a fixed flow rate. Hydraulically controlled transmission (12) according to claim 3, characterized in that - the front pressure chamber (76) of the clutch cylinder (66) is connected to a chamber (28) of the coupling clutch ( 16) and is connected to a supply tank (86) via a first solenoid valve (108) with a fixed flow rate, and - the front pressure chamber (80) of the synchronization cylinder (68). ) is connected to a chamber (54) of the multi-plate clutch (46) via a second fixed-rate solenoid valve (110) and is connected to the supply tank (86) by both intermediate of a non-return valve (112) and a third fixed-rate solenoid valve (114). 7. transmission (12) hydraulically controlled according to the preceding claim, characterized in that it comprises a pressure limiter (116) which is arranged upstream clutch (16) hydraulic coupling. 8. Transmission (12) hydraulically controlled according to claim 2, characterized in that the electro-hydraulic actuator (118) comprises a single cylinder (120) whose controlled piston (122) is actuated by an electric motor (124). 9. Transmission (12) hydraulically controlled according to the preceding claim, characterized in that the front pressure chamber (126) of the cylinder (120) is connected to the chamber (28) of the coupling clutch (16) via a first solenoid valve (128) with a fixed flow rate, the chamber (54) of the multi-plate clutch (46) via a second solenoid valve (130) with a fixed flow rate, and a feed tank (86). ) both through check valve (132) anti-return and a third solenoid valve 34) at a controlled rate. 10. transmission (12) hydraulically controlled according to any one of claims 1 to 9, characterized in that it comprises at least two clutches (46, 51) multidiscs whose respective chambers (53, 54) are likely to selectively connected to the hydraulic pressure source via a solenoid valve (1 with slide. 11. transmission (12) hydraulically controlled according to any one of claims 2 to 10, characterized in that it comprises a central unit (58) controlling the solenoid valves (90, 92, 96, 98, 110, 114, 1 128, 130, 134, 140) and the electro-hydraulic actuator (64, 118). 12. transmission (12) hydraulically controlled according to the preceding claim, characterized in that it comprises pressure sensor (107, 136) which transmits to the central unit (58) representative pressure information upstream of the clutch hydraulic motor (46, 51) for controlling the electric motor (64, 124) associated with the electro-hydraulic actuator 118) and for controlling the solenoid valves (90, 92, 96, 98, 110, 114, 116, 128 , 130, 134, 140).