WO2019211289A1

WO2019211289A1 - Progressive engagement and disengagement of a clutch device for a vehicle

Info

Publication number: WO2019211289A1
Application number: PCT/EP2019/061081
Authority: WO
Inventors: Bastien CLAPIT
Original assignee: Poclain Hydraulics Industrie
Priority date: 2018-04-30
Filing date: 2019-04-30
Publication date: 2019-11-07
Also published as: FR3080660A1; FR3080660B1

Abstract

The invention relates to a method for progressively engaging a clutch device (2) for a vehicle, comprising an actuator (20) which comprises a chamber (200), the method comprising the steps of: - supplying the chamber (200) at a first pressure, - supplying the chamber (200) at a second pressure which is lower than the first pressure, and - supplying the chamber (200) at a third pressure which is higher than the second pressure.

Description

Commitment and progressive disengagement of a vehicle clutch device

TECHNICAL AREA

The invention relates to the control of engagement and / or disengagement of a clutch device comprising a jack.

The invention more specifically relates to a progressive engagement method and a method of progressively disengaging a clutch device comprising a jack, and a system configured to implement said methods.

STATE OF THE ART

There is shown in Figure 1 a known system 1 for engaging and / or disengaging a clutch device 2.

The clutch device 2 comprises a jack 20 comprising a chamber 200 within which slides a piston 210 whose rod 212 is connected to a first side 220 of a set of clutch disks 22. The clutch device 2 further comprises return means 24 connected to a second side 222 of the set of clutch disks 11, opposite the first side 220, and forcing the clutch disks 22 in a loose position.

Thus, when the pressure is sufficiently high within the chamber 200 (ie greater than the force exerted by the return means 24), the piston 210 is pushed outwardly of the cylinder 20 so as to tighten the clutch discs 22.

Conversely, when the pressure is not sufficiently high within the chamber 200 (ie less than the force exerted by the return means 24), the piston 210 is pushed towards the inside of the jack 20 so that loosen clutch discs 22.

Such a clutch device 2 may, for example, be disposed on a vehicle axle (not shown), in order to engage a hydraulic traction assistance motor (not shown) with the non-tractive wheels of the vehicle, the vehicle is stationary or moving.

As can be seen in FIG. 1, the engagement and / or disengagement system 1 comprises a booster pump 10 driven by an element 13, and fluidly connected to the chamber 200 of the cylinder 20. The booster pump 10 is configured to supply the chamber 200 with hydraulic fluid at a fixed pressure, from a hydraulic reservoir 12, to put the cylinder The booster pump 10 delivers at its nominal speed, whatever the need of the circuit, and the pressure is limited by a pressure limiter 15. This flow work exceeds the need required most of the time, and therefore consumes energy, which causes unnecessary heating of the hydraulic fluid. Moreover, the booster pump 10 can also be used to fill a power line of a closed loop hydraulic circuit, or hydraulic actuators, such as control drawers, or organ couplers (eg pumps, motors , transmission shafts, PTO disengageable). The booster pump 10 may also be useful for the pressurization of chambers such as crankcases (eg piston release engines) in the case of a temporary hydraulic transmission of machine or vehicle (eg commercial vehicle). Indeed, it is preferable to maintain such crankcases at a low pressure when the vehicle does not use the hydraulic assistance.

As also visible in Figure 1, the clutch device 2 further comprises one (or more) line (s) 26 (or drain (s) 26). To disengage the clutch device 2, the booster pump 10 is deactivated, and the hydraulic fluid is discharged from the cylinder 20 via said creepage 26, so as to reduce the pressure within the chamber 200.

The operation of such a system 1 is binary (booster pump 10 in maximum flow operation or booster pump deactivated), and the engagement and / or disengagement are implemented very quickly. This can lead to problematic transient behavior when the speed difference between the two elements engaged by the clutch device 2 is large (typically high differential between the speed of rotation of a hydraulic machine and the axle of the vehicle). Indeed, from the coupling performed, there is a risk of water hammer within the hydraulic supply circuit of the clutch device 2. Such a phenomenon generates a shock of high intensity, very clearly perceptible by a user. In addition to the acoustic nuisance, such pressure peaks can lead to accelerated wear of the mechanical parts of the engagement and / or disengagement system 1 and the clutch device 2.

There is therefore a need for a booster pump control system more energy-efficient, and a method and a system for engaging and disengaging a clutch device that is progressive to overcome at least one of the disadvantages described above. SUMMARY OF THE INVENTION

An object of the invention is to provide a booster or control system for hydraulic circuit that is adaptable pressure according to the needs of said hydraulic circuit.

Another object of the invention is to improve the acoustic behavior of engagement and disengagement of a clutch device.

Another object of the invention is to provide a system for engaging and disengaging a clutch device that is reactive.

Another object of the invention is to reduce the wear of mechanical parts of hydraulic transmission.

Another object of the invention is to facilitate the clutch of moving elements at different speeds.

The invention proposes in particular a method of progressively engaging a vehicle clutch device comprising a jack comprising a chamber, the method comprising the steps of:

- supply of the chamber at a first pressure,

- feeding the chamber at a second pressure, less than the first pressure, and

- feeding the chamber at a third pressure, greater than the second pressure.

With such a method of engagement, it is possible to control the coupling phase of the clutch device accurately. Indeed, after the rapid filling of the cylinder at the first supply pressure, the reduction of the power supply with the second pressure, lower than the first pressure, can contain the increase in pressure of gavage due to the arrival at the stop of the cylinder. The pressure peaks in the supply circuit of the cylinder are thus reduced, and the phenomenon of water hammer can be avoided. In addition, the engagement of the elements coupled by the clutch is progressive until a final phase full engagement, during which the coupling force is made maximum thanks to the third supply pressure, greater than the second pressure.

The progressive engagement method according to the invention may further comprise the following characteristic:

the first pressure, the second pressure and the third pressure are substantially equal if the speed of the vehicle is below a threshold.

The invention further relates to a method of progressively disengaging a vehicle clutch device comprising a jack having a chamber, said chamber and / or the hydraulic circuit connected thereto including leaks which tend to empty the chamber when the pressure within said chamber is greater than a leakage pressure, the method comprising the steps of:

o supplying the chamber with a supply pressure lower than the leakage pressure, and

o emptying the room.

With such a process of disengagement, the pressure drop within the chamber is carried out gradually, while being implemented more quickly by means of the active emptying step of the chamber.

The progressive disengagement process according to the invention may further comprise the following characteristic:

- the supply pressure is non-zero.

The invention also relates to a system for progressively engaging and / or disengaging a clutch device comprising a jack comprising a chamber, the system comprising:

a booster pump fluidly connected to the chamber, and

means for controlling the supply pressure of the chamber and / or emptying the chamber,

the system being configured to implement a method as previously described With such a system, the pressure within the cylinder chamber is continuously controlled by the control means of the feed rate and / or emptying. This ensures the implementation of a commitment and / or progressive disengagement of the clutch device.

The progressive engagement and / or disengagement system according to the invention may further comprise the following features taken alone or in combination:

the booster pump is driven by an electric motor,

the control means comprise a module for controlling the speed of the electric motor,

the module controls the speed of the electric motor according to a predetermined operation,

it further comprises a pressure sensor configured to measure the pressure within the cylinder chamber, the module controlling the speed of the electric motor as a function of the pressure measured by said sensor,

the module controls the speed of the electric motor by cutting in DC voltage,

the module controls the speed of the electric motor by frequency division,

the booster pump is driven by a heat engine,

- it also includes:

a pressure sensor disposed between the booster pump and the cylinder chamber, and

o a pressure relief valve arranged between the booster pump and the cylinder chamber,

the control means comprising a processor configured to control the pressure relief valve as a function of the pressure measured by said sensor, and

- The booster pump is configured to alternately inject or aspirate hydraulic fluid within the chamber.

The invention finally relates to a vehicle comprising:

a clutch device comprising a jack, and a system as previously described, the booster pump of the system being fluidly connected to a chamber of the jack.

QUICK DESCRIPTION OF FIGURES

Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows and with reference to the appended drawings given by way of non-limiting example and in which:

FIG. 1, already described, illustrates an engagement and disengagement system, known from the prior art, of a clutch device,

FIG. 2 illustrates a first exemplary embodiment of a progressive engagement and disengagement system, according to the invention, of a clutch device,

FIG. 3 illustrates a second exemplary embodiment of a progressive engagement and disengagement system, according to the invention, of a clutch device,

FIG. 4 illustrates a third exemplary embodiment of a progressive engagement and disengagement system, according to the invention, of a clutch device,

FIG. 5 is a flowchart schematically illustrating a first example of implementation of a progressive engagement method, according to the invention, of a clutch device,

FIG. 6 comparatively illustrates the chronogram of the evolution of the supply pressure of a chamber of a clutch device after an engagement instruction of said device, in an exemplary implementation of FIG. a progressive engagement method according to the invention and in an engagement method according to the prior art,

FIG. 7 is a flowchart schematically illustrating a second example of implementation of a progressive engagement method, according to the invention, of a clutch device,

FIG. 8 is a flowchart schematically illustrating an example of implementation of a method of progressive disengagement, according to the invention, of a clutch device, and

FIG. 9 comparatively illustrates the chronogram of evolution the supply pressure of a chamber of a clutch device after a disengagement of said device, in an example of implementation of a progressive disengagement process according to the invention and in a disengagement process according to the prior art

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures, will now be described a progressive engagement method E1 and a progressive disengagement process E2 of a vehicle clutch device, and a system of engagement and / or progressive disengagement 1 of a clutch device 2.

As can be seen in FIGS. 2 to 4, a clutch device 2 comprises one (or more) jack (s) comprising (each) a chamber 200 within which a piston 210 slides.

In a preferred embodiment illustrated in FIGS. 2 to 4, the rod 212 of the piston 210 is connected to a first side 220 of a coupling mechanism comprising a set of clutch disks 22. The clutch device 2 comprises then return means 24 connected to a second side 222 of the coupling mechanism, opposite the first side 220, and forcing the coupling mechanism into a decoupled position, in which the clutch disks 22 are remote from the second side 222. As 3 and 4, the clutch device 2 also comprises additional return means 28 arranged opposite the stack of the clutch discs 22. These additional return means 28 may for example be a set of springs or a Belleville washer. The additional return means 28 have a free length sufficiently small not to impact the space between the different discs 22 when the clutch device 2 is not engaged (i.e. the coupling mechanism is decoupled).

This is not, however, limiting, since the rod 212 of the piston 210 can also be connected to any type of known coupling mechanism, such as a drum or conical clutch.

The clutch device 2 may, in a preferred embodiment illustrated in FIGS. 2 to 4, allow the coupling between a transmission system However, this is not limitative, since the clutch device 2 may, for example, also be used to allow a coupling controlled by a force-feeding pressure between a box speed or the motor shaft of the vehicle on the one hand, and a hydraulic power pump or a hydraulic motor on the other hand.

With reference to FIGS. 2 to 4, the hydraulic assistance transmission system 3 may, in one embodiment, be of the "bicycle chain" type. It then comprises a first hydraulic machine 31 and a second hydraulic machine 32, each of which can be coupled by a clutch device 2 respectively to an axle 4 of the vehicle. The first hydraulic machine 31 and the second hydraulic machine 32 are fluidly connected by a hydraulic circuit comprising a first supply line 33 and a second supply line 34, so as to form a closed circuit. The hydraulic machines 31, 32 are configured to alternatively perform the function of hydraulic power pump or hydraulic motor, depending on the additional motor needs required by one or other of the axles 4. According to the function provided by the hydraulic machines the first 33 and the second 34 supply line respectively act as high pressure line and low pressure line of the hydraulic circuit, and vice versa. The pressure difference between the two feed lines 33, 34 is maintained fixed by means of a differential selector 35 arranged between the two feed lines 33, 34. The hydraulic fluid supply of the hydraulic circuit is ensured by a booster circuit comprising a booster pump 10 fluidly connected to the hydraulic circuit, and configured to deliver hydraulic fluid from a hydraulic reservoir 12. For this purpose, a selector 36 may be disposed at the junction between the booster circuit and the hydraulic circuit, in order to standardize the injection of hydraulic fluid between the supply lines 33, 34. A "bicycle chain" type transmission is described in detail in the applications FR 2 996 176 and FR 2 996 267, in the name of the plaintiff.

In an alternative embodiment (not shown), the hydraulic transmission system comprises a hydraulic power pump that can be coupled to the engine of the vehicle by a first clutch device, and disposed on the tractor axle. The system further comprises a hydraulic motor that can be coupled to the non-tractor axle of the vehicle by a second clutch device. In operation, the clutch devices being engaged, the hydraulic power pump delivers hydraulic fluid into the hydraulic motor via a high pressure line. The hydraulic motor thus provides additional traction to the non-tractor axle, and circulates hydraulic fluid in a low pressure line connected to the hydraulic power pump. The hydraulic circuit thus formed is also fed via a booster circuit as previously described.

In any case, the clutch devices 2 may be substantially identical, as illustrated in Figures 2 to 4.

As can be seen in FIGS. 2 to 4, the booster pump 10 is fluidly connected to the cylinder chamber 200. In addition, the jack 20 and the hydraulic machine 31 each comprise leaks fluidly connected to one (or more) line ( s) 26 (or drain (s) 26), through which the chamber 200 is permanently empty as the pressure P within said chamber 200 is greater than a leakage pressure P _f . In operation, this emptying by the leaks is permanently compensated by the supply of the chamber 200 to maintain the clutch device 2 engaged. The excess hydraulic fluid thus discharged from the chamber 200 returns to the hydraulic reservoir 12 via said drains 26. In operation, the pressure P within the chamber 200 determines the force exerted by the rod 212 of the piston 210 on the coupling mechanism, for example the set of clutch discs 22 biased by the biasing means 24, 28. More specifically, when the pressure P is established within the chamber 200, the rod 212 is set in motion. so compressing the biasing means 24 and coupling the coupling mechanism, for example by putting all the clutch disks 22 bears against the second side 222 of the coupling mechanism. Subsequently, with the increase of the pressure P within the chamber 200, the discs 22 are compressed in a progressive manner by crushing the additional return means 28. To disengage the clutch device 2, the pressure P within the chamber 200 decreases, and the discs 22 are loosened by the extension of the additional return means 28, and the return means 24 are extended in turn, so as to decouple the coupling mechanism.

The booster pump 10 supplies the hydraulic circuit with a given power. This boosting power determines a flow rate and pressure that depend on the properties of the hydraulic circuit. Depending on the needs of the hydraulic circuit and / or the sizing choices, it is therefore possible to control the hydraulic circuit under pressure (eg by means of a nozzle) or flow (eg by means of a flow limiter), one determining the other at a given power of the booster pump 10. In all that follows, a progressive engagement method E1, progressive disengagement E2, and a control system. commitment and / or progressive disengagement will be described for pressure steering. This is however not limiting since such methods and such a system also apply to flow control.

The control of the supply pressure P _a of the chamber 200 makes it possible to precisely control the engagement and / or disengagement forces of the clutch device 2. In addition, in the illustrated example of a disk coupling 22 , the control also makes it possible to control the plating force of the discs 22 with each other and hence the torque transmissible by the clutch device 2. This is in particular implemented thanks to the combination of the return means 24 and the additional return means 28 which give the clutch device 2 more progressivity depending on the movement of the coupling mechanism, that is to say as a function of the pressure P within the chamber 200. Indeed, the means additional return 28 allow a progressivity of the contact force of the discs 22 as a function of crushing, or depression of the relative movement of the coupling mechanism. The additional return means 28 exert a counter-force on the clutch disks 22 in the transitional phase of engagement. This counter-force itself is progressive as the supply pressure P _a increases, and the piston 210 makes its travel, until the abutment of the stack of clutch disks 22 In this respect, the additional return means 28 has a stiffness that is sufficiently large for the counter-force generated to be able to allow transmission of the torque that can be transmitted by the clutch device 2. Such a control allows progressive engagement and / or disengagement. . By progressive engagement and / or disengagement, it is understood that the engagement and / or the disengagement are implemented in successive steps that are linked in a regular and continuous manner, so as to cause a gradual and constant increase / decrease in the pressure P in the bedroom 200.

With reference to FIG. 5, a progressive engagement method E1 of a clutch device 2 for a vehicle comprising a jack 20 comprising a chamber 200, comprises the steps of:

- Supply E11 of the chamber 200 at a first pressure P _ai , supply E12 of the chamber 200 at a second pressure P _a 2, lower than the first pressure P _ai , and

- E13 supply of the chamber 200 at a third pressure P _a 3, greater than the second pressure P _a 2.

In the first step E11, the chamber 200 of the jack 20 is loaded with hydraulic fluid. In addition, in the embodiment illustrated in FIGS. 2 to 4, in which the rod 212 of the jack 20 is connected to clutch disk assembly 22, this first step E11 also allows the disks 22 of the second side 222 of the coupling mechanism. In a preferred manner, in order to carry out this preparatory race of the clutch device 2 as quickly as possible, the first pressure P _ai is very high, and corresponds, for example, to the maximum power delivered by the booster pump 10.

During the second step E12, the progressive commitment is implemented by reducing the supply pressure P _a of the chamber 200. In this step E12, it is necessary to contain the pressure increase P within of the chamber 200 born from the end of the filling of the cylinder 20 and, in the illustrated embodiment of disk clutch 22, the coming into contact of the disks 22 between them following the contact against the second side 222 of the coupling mechanism . By reducing the supply pressure P _a , the clutch disks 22 begin to slide between them during the first moments of the engagement. This ensures progressive rotation of the coupling members. The piloting of the second pressure P _a 2 also makes it possible to control this sliding in order to reduce its acoustic impact.

In the third step E13, the supply pressure P _a is again gradually increased in order to implement the final coupling phase. In the embodiment illustrated in FIGS. 2 to 4, this third step E13 ensures the final plating of the clutch disks 22, with a maximum coupling force.

Once the coupling is guaranteed, the engagement is maintained by a high pressure supply, corresponding for example to the maximum power delivered by the booster pump 10. Thus, in one embodiment, the third pressure P _a 3 is substantially equal to the first pressure P _ai . By substantially equal, it is understood that the third pressure P _a 3 is equal to the first pressure P _ai 10%. FIG. 6 illustrates the timing diagram of the supply pressure P _a of the chamber 20 during the implementation of the progressive engagement method E 1, and during the implementation of a method of engagement according to the art. prior. As shown in this figure, the complete engagement of the clutch device 2 is deferred with respect to the prior art.

This can impact the reactivity of the coupling and hence the elements to be coupled. For example, in the case illustrated in FIGS. 2 to 4 of a clutch device 2 for coupling a hydraulic assistance transmission system 3 and the axles 4 of a vehicle, an availability period of the system 3 may appear between the moment when the user requires assistance, and the moment when the transmission of power actually takes place from one axle 4 to the other.

However, this engagement reactivity is only necessary under very particular conditions. In the case of use for a hydraulic assistance transmission system 3, this reactivity is particularly useful if the driving situation can cause a risk of immobilization of the vehicle, that is to say at low speed. Such situations may for example be encountered when a vehicle passes through a sandy area.

With reference to FIG. 7, in one embodiment of the progressive engagement method E1, if the speed of the vehicle V is less than a threshold V _s , the first pressure P _ai , the second pressure P _a2 and the third pressure P _a 3 are substantially equal. In addition, these three pressures P _ai , P _a2 , P _a 3 correspond to the maximum power supplied by the booster pump 10. By substantially equal, it is understood that these three pressures P _ai , P _a2 , P _a3 are equal to 5 % near. This is an embodiment where the commitment is no longer progressive, but abrupt, to ensure rapid responsiveness of the system. In this situation, the risk of water hammer or peak pressure is very limited, since the speed of the axle 4 is low.

With reference to FIG. 8, a progressive disengagement process E2 of a vehicle clutch device 2 will now be described, said clutch device 2 comprising a jack 20 comprising a chamber 200, said chamber 200 and / or the hydraulic circuit connected thereto comprising leaks 26 which tend to empty the chamber 200 when the pressure P within said chamber 200 is greater than a leakage pressure P _f . The progressive disengagement process E2 comprises the steps of:

supply E21 of chamber 200 at a pressure P _a , preferably not zero, and lower than the leakage pressure P _f , and

emptying E22 of the chamber 200.

During the first step E21, the pressure drop P in the chamber 200 is progressively made, which improves the acoustic behavior of the clutch device 2. In particular, it avoids a water hammer, or pressure wave that propagates in the hydraulic circuits connected to the clutch device 2, as well as mechanical shaking.

During the second step E22, the disengagement is implemented more quickly by accelerated evacuation of the chamber 200.

In this regard, FIG. 9 illustrates a timing diagram of the supply pressure P _a of the chamber 200. By convention, a positive pressure corresponds to a supply of the chamber 200 with hydraulic fluid, and a negative pressure corresponds to a draining of the chamber 200. As shown in this figure, the emptying step E22 can be done by increasing depression in a first phase, then a constant maximum emptying vacuum during a second phase. In a last phase, the P supply _pressure becomes gradually zero, which corresponds to a cut-off of the fuel pump 10.

With reference to FIGS. 2 to 4, a progressive engagement and / or disengagement system 1 of a clutch device 2 comprising a jack 20 comprising a chamber 200, comprises:

a booster pump 10 fluidly connected to the chamber 200, and

- Control means 14, 15, 16, 17, 18 of the supply pressure P _a of the chamber 200 and / or emptying the chamber 200.

In addition, the system 1 is configured to implement a progressive engagement method E1 and / or a progressive disengagement process E2 according to any one of the previously described implementations. More specifically, the control means 14, 15, 16, 17, 18 are configured to control the supply pressure P _a and / or empty the chamber.

In a preferred manner, the booster pump 10 is fixed displacement.

In a first embodiment, with reference to FIGS. 2 to 4, the booster pump 10 is driven by an electric motor 13.

The electric motor 13 can be powered by the vehicle electrical network (not shown). The electric motor 13 can drive the booster pump 10 in two opposite directions, so that the booster pump 10 injects hydraulic fluid into the chamber 200 (rotating operation) or, alternatively, draws hydraulic fluid from the chamber 200 (operation in contra-rotation). Thus, the feed stages E11, E12, E13, E21 or E22 of the emptying chamber 200 of the progressive engagement process E1 and / or progressive disengagement E2 can be implemented.

According to a privileged implementation of the method of progressive commitment E1 by the system 1, the method E1 comprises a starting phase E10 of the electric motor 13 during which the full voltage is established progressively, so as to avoid a strong call from current in the electrical network of the vehicle. This is notably visible on the chronogram illustrated in FIG.

According to a also privileged implementation of the method of progressive disengagement E2 by the system 1, the feeding step E21 of the pressure chamber P _a is implemented by gradually reducing the power of the booster pump 10. In In the prior art, the counter-rotation disengagement comprises a phase in which the electric motor is cut in order to absorb the current peak due to the braking of the moving mechanical inertia in the coupling assembly. In the progressive disengagement process, on the contrary, the braking of the booster pump 10 can thus be controlled so as to smooth the absorbed current without having an unnecessary stopping phase to the effective disengagement of the coupled elements. The difference with the prior art is notably visible on the timing diagrams illustrated in FIG. 9. As illustrated in FIG. 2, according to a first variant, the system 1 furthermore comprises:

a pressure sensor 14 configured to measure the pressure P within the chamber 200 of the jack 20, and

- A pressure relief valve 15 disposed between the booster pump 10 and the chamber 200 of the cylinder 20.

Advantageously, the pressure relief valve 15 has a proportional setting.

In this first variant, the control means comprise a processor 16 configured to control the overpressure valve 15 as a function of the pressure measured by said sensor 14. In operation, the motor 13 drives the booster pump 10 at a maximum duty cycle, corresponding to a power maximum provided by the booster pump 10. Thereafter, the supply pressure P _a of the chamber 200 of cylinder 20 is controlled by actuation of the pressure relief valve 15. More precisely, as the pressure P noted in the chamber 200 of cylinder 20 by the sensor 14 is less than a threshold corresponding to the arrival at the stop of the cylinder 20, at the end of the filling of the chamber 200, the pressure relief valve 15 is in the closed position, and the first pressure P _ai corresponds to the maximum power of the booster pump 10. Then, the pressure relief valve 15 is open so as to reduce the supply pressure P _a of the chamber 200 at the second pressure P _a 2, to ensure a progressive engagement of the clutch device 2. Finally, when the pressure P in the chamber 200 reaches again a threshold corresponding to the final phase of the engagement, the pressure relief valve 15 is again partially or completely closed, in order to ensure a third pressure P _a 3 higher than the second pressure P _a 2, preferably substantially equal to the first pressure P _ai .

Alternatively to the pressure sensor 14, the system may also comprise a servo control loop comprising a sensor of the current absorbed by the motor 13 (not shown) or a sensor 17 for moving the rod 212 within the cylinder 20. In any case, the processor 16 controls the overpressure valve 15 according to the information relating to the state of engagement of the clutch device 2, said information being provided by the servo-control loop.

Alternatively, in a second embodiment, this first variant can also be implemented if the booster pump 10 is driven by a heat engine (not shown), typically via a PTO of the main engine of the engine. vehicle. In this embodiment, it is also possible to drive the booster pump 10 in two opposite directions, so that the booster pump 10 injects hydraulic fluid into the chamber 200 (rotating operation) or, alternatively, draws fluid hydraulic chamber 200 (contra-rotation operation).

As illustrated in FIGS. 3 and 4, according to a second variant of the first embodiment, the control means comprise a control module 18 for the speed of the electric motor 13. Thus, it is possible to directly control the hydraulic fluid pressure. injected into the chamber 200 or removed from the chamber 200. In addition, this variant offers the advantage of limiting the consumption of the electric motor 13, which offers an advantageous economic gain and reduces heating of the booster pump 10 itself, thus increasing its service life.

As illustrated in FIG. 3, the module 18 can control the speed of the electric motor according to a predetermined operation. More precisely, the timing diagram illustrated in FIG. 6 can be pre-recorded and implemented by temporal modulation of the speed of the electric motor 13, and therefore of the supply pressure P _a of the chamber 200, or the emptying of the chamber 200. by the booster pump 10. This timing diagram can be determined by a manufacturer from estimates of the pressure drops of the system 1, the slipping rate of the clutch disks 22, and / or the mapping of the leaks. of the jack 20. The operation of the booster pump 10 is thus sequenced temporally to ensure the progressive engagement of the clutch device 2 by passing the first pressure P _ai at the third pressure P _a 3, passing through the second pressure P _a 2. In the same manner, the booster pump 10 will have a temporally sequenced operation to ensure a progressive disengagement of the clutch device 2, according to the timing diagram illustrated in FIG. 9.

As illustrated in FIG. 4, the module 18 can alternately control the speed of the electric motor 13 as a function of the pressure P measured by a pressure sensor 14 configured to measure the pressure P within the chamber 200 of the cylinder 20. This servocontrol in pressure is substantially identical to that already described in the first variant. As in the first variant, the control loop may also comprise a sensor of the current absorbed by the motor 13 or a displacement sensor of the rod 212 within the cylinder 20. In any case, the control module 18 the speed of the electric motor 13, and therefore the feeding pressure at the booster pump outlet 10, as a function of the information relating to the engagement state of the clutch device 2, said information being provided by the buckle servo.

The control of the speed of the electric motor 13 can be implemented by cutting in DC voltage. In this embodiment, the booster pump 10 can thus be controlled by pulse width modulation (or "width modulation pulse" in the English terminology). In this case, the module 18 comprises a computer generating a high frequency square signal in order to establish a supply voltage of the booster pump 10 less than its maximum supply voltage. Thus, it is possible to adjust the output power of the booster pump 10 by modulating the frequency of the square signal. In addition, the square signal may vary between positive and negative voltage values so as to provide the previously described rotation or contra rotation operation.

Alternatively, in the case where the electric motor 13 is synchronous, the control of the speed can be implemented by frequency cutting. This type of control can for example be implemented within an electric motor with a pitch. To carry out the frequency division, the module 18 comprises an electronic speed variator.

In any case, such a control of the speed of the electric motor 13 may be particularly useful when the clutch device 2 is implemented within a temporary hydraulic transmission of machine or vehicle (eg utility vehicle ). Thanks to such a control, in addition to the minimum pressurization of crankcases, the booster pump 10 and controlled can allow feeding of the components of the temporary hydraulic transmission at a different pressure during other phases, such as the coupling of organs, feeding of the power transmission circuit, or actuation of selection drawers.

A vehicle equipped with:

a clutch device 2 comprising a chamber 200, such as those previously described, and

a system of engagement and / or progressive disengagement 1 according to one of the embodiments as previously described, the booster pump 10 of the system 1 being fluidly connected to the chamber 200, can therefore ensure the user commitment and / or a disengagement of the clutch device whose acoustic nuisance and the risk of wear by water hammer are reduced.

Claims

A method of progressively engaging (E1) a clutch device (2) for a vehicle comprising a jack (20) having a chamber (200), the method (E1) comprising the steps of:

supplying (E11) the chamber (200) at a first pressure (P _ai ), feeding (E12) the chamber (200) at a second pressure (P _a 2), lower than the first pressure (P _ai ), and

supply (E13) of the chamber (200) at a third pressure (P _a 3), greater than the second pressure (P _ai ).

2. A method of progressive engagement (E1) according to claim 1, wherein the first pressure (P _ai ), the second pressure (P _a2 ) and the third pressure (P _a 3) are substantially equal if the speed (V) vehicle is less than a threshold (V _s ).

A method of progressively disengaging (E2) a clutch device (2) for a vehicle comprising a jack (20) having a chamber (200), said chamber (200) and / or the hydraulic circuit connected thereto comprising leaks (26) tending to empty the chamber (200) when the pressure (P) within said chamber (200) is greater than a leakage pressure (P _f ), the method (E2) comprising the steps of:

supply (E21) of the chamber (200) at a supply pressure (P _a ) less than the leakage pressure (P _f ), and

- emptying (E22) of the chamber (200).

4. Process of progressive disengagement (E2) according to claim 3, wherein the supply pressure (P _a ) is non-zero. 5. System for engaging and / or gradually disengaging (1) a clutch device (2) comprising a jack (20) having a chamber (200), the system (1) comprising:

a booster pump (10) fluidly connected to the chamber (200), and means (14, 15, 16, 17, 18) for controlling the supply pressure (P _a ) of the chamber (200) and / or of emptying the chamber (200), the system (1) being configured to implement a method (E1, E2) according to any one of claims 1 to 4.

6. System of engagement and / or progressive disengagement (1) according to claim 5, wherein the booster pump is driven by an electric motor (13). 7. System of engagement and / or progressive disengagement (1) according to claim 6, wherein the control means comprise a module (18) for controlling the speed of the electric motor (13).

8. A system of engagement and / or progressive disengagement (1) according to claim 7, wherein the module (18) controls the speed of the electric motor (13) according to a preset operation.

The progressive engagement and / or disengagement system (1) according to claim 7, further comprising a pressure sensor (14) configured to measure the pressure (P) within the cylinder chamber (200) (20). ), the module

(18) controlling the speed of the electric motor (13) as a function of the pressure (P) measured by said sensor (14).

10. A system of engagement and / or progressive disengagement (1) according to one of claims 7 to 9, wherein the module (18) controls the speed of the electric motor (13) by cutting in DC voltage.

11. System of engagement and / or progressive disengagement (1) according to one of claims 7 to 9, wherein the module (18) controls the speed of the electric motor (13) by frequency cutting.

12. System of engagement and / or progressive disengagement (1) according to claim 5, wherein the booster pump (10) is driven by a heat engine.

13. System of engagement and / or progressive disengagement (1) according to one of claims 6 or 12, further comprising:

a pressure sensor (14) disposed between the booster pump (10) and the chamber (200) of the cylinder (20), and

a pressure relief valve (15) disposed between the booster pump (10) and the chamber (200) of the cylinder (20),

the control means comprising a processor (16) configured to control the pressure relief valve (15) as a function of the pressure measured by said sensor (14).

14. A system of engagement and / or progressive disengagement (1) according to one of claims 5 to 13, wherein the booster pump (10) is configured to alternately inject or draw hydraulic fluid within the chamber ( 200).

15. Vehicle comprising:

a clutch device (2) comprising a jack (20), and

a system of engagement and / or progressive disengagement (1) according to one of claims 5 to 14, the booster pump (10) of the system (1) being fluidly connected to a chamber (200) of the cylinder (20) .