FR3072148B1 - METHOD AND SYSTEM FOR SELF-MAINTENANCE - Google Patents

Abstract

The invention relates to a method for self-maintenance (E) of a hydraulic assist device (2) of a vehicle, said device (2) comprising: • a hydraulic machine (21, 23), • a reservoir (12), • a filter (101, 103), • a booster pump (10), the method (E) comprising the steps of: • putting the hydraulic machine (23) into operation (E1) for a predetermined period of time , and • deactivating (E2) the hydraulic machine (23), at the end of the commissioning step (E1), so as to circulate hydraulic fluid through the filter (101, 103) successively in two opposite traffic directions, the commissioning (E1) and deactivation (E2) steps being implemented independently of a commitment command and / or a disengagement of the assistance.

Description

TECHNICAL FIELD The invention relates to a method and a system for self-maintenance of a hydraulic assistance device of a vehicle. The invention relates more specifically to the self-maintenance of a hydraulic assistance device that is little used and / or of which a hydraulic fluid is used.

STATE OF THE ART

In order to provide additional traction to one or more wheels of a vehicle, numerous devices for hydraulic traction assistance, or temporary hydraulic transmission, for vehicles have been proposed.

These devices generally use at least two hydraulic machines placed in fluid communication, and configured to transform a pressure difference between their inlet and their outlet into a motor torque, and vice versa.

Typically, such devices include a hydraulic pump, called a power pump, connected to the vehicle powertrain, said power pump delivering in one or more hydraulic motors connected to the non-driving wheels. Thus, it is possible to switch from a 4 * 2 type of vehicle propulsion to a 4 * 4 type propulsion, for example in environments where the vehicle is likely to skate.

Alternatively, the assistance includes a first hydraulic machine connected to the front axle of the vehicle, and a second hydraulic machine connected to the rear axle of the vehicle. These two machines can alternatively play the role of power pump or hydraulic motor, according to the needs in additional traction required by one or the other of the axles. This type of device is conventionally designated under the title of "bicycle chain", and also makes it possible to transform a 4 * 2 vehicle into a 4 * 4.

In any event, such systems are disengageable, so that assistance can be engaged or disengaged as a function of a user command and / or vehicle running conditions, for example at given speed thresholds , or at a slip threshold. Furthermore, these devices can be controlled on command, by an automaton or a user, so as to permanently control the assistance provided to the wheels.

Thus, an assistance system that is, for example, engaged only to avoid skating, could remain uncommitted for a very long time. For example, a vehicle with such a system would only activate assistance in the event of snow. For example, in some countries, assistance may never be engaged for most of the year.

The hydraulic machines of such systems generally comprise a set of moving parts, in relative movement with respect to each other under the action of a hydraulic fluid circulating within the hydraulic machines. However, to ensure the proper functioning of such machines, it is necessary to regularly activate the movement of the moving parts, in order to avoid the appearance of wear or corrosion at the contact points, or deposits at different locations. , especially in backgrounds and filters. Contact with stationary parts can cause occasional abrasion when the vehicle receives vibrations from driving. Deposits can cause some polymerization, sticking of parts, or clogging of strainers, which may damage the surface when restarting machines after a long period of inactivity, and considerably reduce their service life.

In addition, the high operating temperatures of such machines can lead to premature aging of the operating fluid, by heating stagnant deposits, in certain localized places which are particularly hot. A portion of fluid kept immobile in this part of the system would be regularly heated, and could then degrade locally. This degraded fluid could polymerize and create a plug, or travel in the system at the first start-up, and be placed on a strainer or a small mechanism. This is particularly problematic when the fluid circuits of the assistance devices are provided with filtering systems aimed at preserving the ingestion of impurities by the components of the device. Typically, it is customary to provide the booster pump with such circuits with a filter strainer at the point of suction of hydraulic fluid from the reservoir. The fouling of this strainer can make the assistance system unavailable because the booster pump would no longer be able to suck through this strainer, and therefore create the pressure necessary for engagement. This significantly reduces the time spent between two system drains.

In addition to reducing the service life of hydraulic assist devices, the drawbacks described above require regular maintenance by a professional. These interviews can be costly and time consuming for the user.

There is therefore a need to ensure the long-term availability of hydraulic assistance devices without jeopardizing the safety of the vehicle.

SUMMARY OF THE INVENTION

An object of the invention is to provide continuous self-maintenance of a vehicle hydraulic assistance device without modifying its structure.

Another object of the invention is to increase the service life of a hydraulic assist device in an inexpensive manner.

Another object of the invention is to increase the time interval separating two oil changes from a vehicle hydraulic assistance device. The invention proposes in particular a method of self-maintenance of a hydraulic assistance device of a vehicle, said device comprising: • a hydraulic machine, • a tank, • a filter, • a booster pump comprising: o a fluid inlet placed in fluid communication with the tank, and o a fluid outlet outlet put in fluid communication with the hydraulic machine, the device being configured to circulate a hydraulic fluid alternately: • from the tank to the hydraulic machine, by action of the booster pump, to put the hydraulic machine into service and thus engage the hydraulic assistance, and • from the hydraulic machine to the tank to deactivate the hydraulic machine and thus disengage the hydraulic assistance, engagement and disengagement of assistance being controllable on command, the method comprising the steps consisting in: service the hydraulic machine for a fixed period, and • deactivate the hydraulic machine, at the end of the commissioning step, so as to circulate hydraulic fluid through the filter successively in two opposite directions of circulation, commissioning and deactivation steps being implemented independently of an assistance engagement and / or disengagement command.

Thanks to such a self-maintenance process, the filters of the hydraulic assistance device are regularly unclogged, by successive commissioning and deactivation of the hydraulic machine. This one-time activation is also independent of commands for engaging and / or disengaging the hydraulic assistance. Thus, continuous self-maintenance of the hydraulic assistance system is made possible, even if the system is not used regularly. This continuous self-maintenance consists of maintaining the integrity of the hydraulic fluid and the quality of the lubrication, as well as regular cleaning of the filters. Such self-maintenance is therefore different from the periodic maintenance operation carried out by a professional, which consists in changing the hydraulic fluid, and possibly the filters of the hydraulic assistance system. In addition, such self-maintenance offers the advantage of not modifying the existing structures of the hydraulic device, while significantly increasing the service life.

The method according to the invention can also comprise the following characteristics taken alone or in combination: - it is implemented for a given range of vehicle speed, for example the vehicle speed being between 0 and 40 km / h, - the alternation of the commissioning and deactivation steps is repeated successively at a given frequency, for example ten times in succession, - assistance is engaged, the process then being alternately implemented: o the vehicle being in motion , the assistance then being partially disengaged during the deactivation step, or o the vehicle being stopped, - the assistance is disengaged, the method being alternately implemented with the vehicle in motion, or the vehicle being stopped, - it is implemented each time the vehicle is started, - it is implemented at a given rate, said rate can be functional, for example each time the vehicle has traveled a given distance, and / or time, for example once every month of operation of the vehicle, and - it is implemented from a given level of wear of the hydraulic fluid. The invention also relates to a self-maintenance system for a hydraulic assistance device for a vehicle, said device comprising: • a hydraulic machine, • a tank, • a filter, • a booster pump, said booster pump comprising o a fluid inlet placed in fluid communication with the reservoir, and o a fluid outlet outlet put in fluid communication with the hydraulic machine, the device being configured to circulate hydraulic fluid alternately: • from the reservoir towards the hydraulic machine, by action of the booster pump, to put the hydraulic machine into service and thus engage the hydraulic assistance, and • from the hydraulic machine to the tank to deactivate the hydraulic machine and thus disengage the hydraulic assistance, the engagement and disengagement of the assistance being controllable on command, said system comprising a pilo module tage configured to implement a method as previously described.

The system according to the invention may further comprise the following characteristics taken alone or in combination: - it comprises a strainer disposed between the reservoir and the fluid inlet of the Gave pump, and a main filter disposed between the fluid outlet of the booster pump and the hydraulic machine, the strainer and the main filter being configured to protect the hydraulic assistance device from the ingestion of particulate pollution, - it includes a secondary filter and a bypass valve, arranged between the filter main and the fluid outlet of the booster pump, the secondary filter being configured to discharge impurities from the main filter during the backflow of hydraulic fluid from the hydraulic machine, and - it further comprises a vacuum valve controlled by the control module, and configured to favor the flow of hydraulic fluid from the hydraulic machine. Finally, the invention relates to a vehicle comprising a disengageable hydraulic assistance device and a self-maintenance system as described above.

QUICK DESCRIPTION OF THE 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: - Figures 1a to 1f schematically illustrate different embodiments of a self-maintenance system of a hydraulic assistance device of a vehicle, - Figures 2a and 2b schematically illustrate different embodiments of a hydraulic assistance device of a vehicle, - Figure 3 illustrates different stages of a method of self-maintenance of a hydraulic assistance device of a vehicle, and - Figures 4a and 4b show functional diagrams of different embodiments of a method of self-maintenance of a hydraulic assistance device of a vehicle.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures, a self-maintenance system 1 of a hydraulic assistance device 2 of a vehicle will now be described.

In the following, “self-maintenance” means all of the actions implemented automatically by a system 1 as described, with a view to ensuring the permanent availability of the functions of a hydraulic assistance device 2 of a vehicle. . As will be developed more precisely, the self-maintenance of a hydraulic assistance device 2 includes regular fouling of the various elements of the device 2, such as the filters 101, 103 or the deposition zones, by circulating the hydraulic fluid. within the device 2. The self-maintenance also includes a renewal and a regular homogenization of the hydraulic fluid, by stirring and mixing, in order to avoid stagnation of fluid, in particular in the portions of elements of the device 2 which are close to '' a hot component of the vehicle.

With reference to FIGS. 1a to 1f, 2a and 2b, a hydraulic assistance device 2 of a vehicle comprises a hydraulic machine 21,23.

The hydraulic machine 21, 23 comprises a fluid inlet 210, 230 and a fluid outlet 212, 232, and mechanical elements movable under the action of a hydraulic fluid circulating within the hydraulic machine 21, 23. The fluid inlet 210, 230 and outlet 212, 232 are generally placed in fluid communication with a hydraulic assistance circuit 27. Such a machine 21, 23 is then configured to transform a pressure difference between the fluid inlet 210, 230 and the fluid outlet 212, 232 into a driving torque, and vice versa, the transformation being implemented by movement of mobile elements of the hydraulic machine 21, 23. This transformation also makes it possible to provide the assistance function device 2.

The hydraulic machine 21, 23 is also configured to be switched on or off alternately, the switching on and off ensuring respectively the engagement and disengagement of the hydraulic assistance. In this regard, the hydraulic machine 21, 23 includes mobile elements for bringing into service 211, 231 which are also mobile under the action of a hydraulic fluid circulating within the hydraulic machine 21, 23. By way of non-limiting example, such movable elements 211, 231 can be clutches 211 with discs or dog clutch, for example of the same type as the state of the art of a gearbox. In this case, the mobile elements for putting into service 211 are connected to a fluid circuit 29 different from the hydraulic assistance circuit 27, and their movement is independent of the other mobile elements of the hydraulic machine 21. This is called mobile elements of “independent” commissioning 211. Alternatively, such elements may be radial pistons 231 which disengage from their cam by retraction of the pistons 231. In this case, the mobile elements of commissioning 231 are directly connected to the circuit. hydraulic assistance 27. Their movement is dependent on the other mobile elements of the hydraulic machine, or even these are the same elements 231. We then speak of “dependent” mobile commissioning elements 231. Commissioning and deactivation such machines 21, 23 are for example described in patent applications FR 2 996 267 and FR 3 033 529 in the name of the Applicant, and will not be p have more details here.

The hydraulic machine 21, 23 generally has a sump drain 215, 235, which collects internal leaks from all the organs of the machine 21, 23 subjected to pressure, and returns them to an oil tank 12. More particularly, the hydraulic machine 21, 23 can have a leakage nozzle 213, 233 intended to renew the oil, and cool certain internal organs, which is connected to a drain 215, 235 by which the excess hydraulic fluid can be evacuated towards the reservoir 12.

Still with reference to FIGS. 1a to 1f, 2a and 2b, a vehicle provided with such a hydraulic assistance device 2 comprises a self-maintenance system 1 of the device 2. This system 1 notably comprises a control module 11 configured to control the hydraulic assistance. More specifically, the control module 11 is configured to receive an engagement or disengagement command from the hydraulic assistance, and transmit a corresponding command to commission or deactivate the hydraulic machine 21, 23. The engagement and assistance can be disengaged on command. In this regard, the engagement or disengagement command of the hydraulic assistance can be transmitted to the control module 11 directly by a user. Alternatively, such a command can be transmitted by an automaton 13 of the vehicle as a function of the running conditions. Typically, the controller 13 requires hydraulic assistance when slippage is detected, for example when the vehicle is approaching snowy or sandy surfaces. Similarly, the automaton 13 cuts the hydraulic assistance when the speeds reached by the vehicle are above a level admissible by the hydraulic machine 21,23. The control module 11 is further configured to control the commissioning of the hydraulic machine 21, 23 for a determined period, then the deactivation of the hydraulic machine 21, 23 at the end of the determined commissioning period, said command being independent of an engagement command, respectively disengagement, assistance. More specifically, the control module 11 is configured to control the operation of the hydraulic assistance device 2 alternately in response to an engagement or disengagement command, or on its own initiative, for the purposes of self-maintenance, without having received an engagement and / or disengagement order. Indeed, the commissioning of the hydraulic machine 21, 23 for a determined period, then the deactivation of the hydraulic machine 21, 23, ensure the setting in motion of mobile elements of the hydraulic machine 21, 23 to force the circulation hydraulic fluid within all or part of the hydraulic machine 21, 23. This is called complete or partial scanning of the hydraulic machine 21, 23. Regular self-maintenance of the hydraulic assistance device 2 is thus advantageously made possible.

Referring to Figure 2a, the hydraulic machine can be a hydraulic power pump 21. In this case, the power pump 21 is connected, for its drive, to a power train 31 of the vehicle. The movable elements of the power pump 21 are then configured so that their movements make it possible to transform the torque supplied by the power unit 31 into a pressure difference between the inlet 210 and the fluid outlet 212 of the power pump 21.

Alternatively, still with reference to FIG. 2a, the hydraulic machine is a hydraulic motor 23. The motor 23 is connected to a wheel 33 of the vehicle. The movable elements of the motor 23 are then configured so that their movements make it possible to transform a pressure difference between the inlet 230 and the outlet 232 of fluid from the engine 23 into a torque transmitted to the wheel 33, when assistance is engaged. The wheel 33 is typically a load wheel not connected to the mechanical transmission of a 4 * 2 vehicle. When the assistance is disengaged and the vehicle is in motion, the motor 23 also being put into service, the mobile elements can be set in motion under the action of the torque exerted by the wheel 33 in rotation. However, there is generally a vehicle speed limit above which a safety module 14 of the hydraulic assistance device 2 automatically deactivates the hydraulic motor 23, to preserve the safety of the motor 23.

With reference to FIG. 2a, the hydraulic assistance device may also include a first hydraulic machine 21, and a second hydraulic machine 23, the inlet 210 of the first machine 21 being placed in fluid communication with the outlet 232 of the second machine 23, and the inlet 230 of the second machine 23 being placed in fluid communication at the outlet 212 of the first machine 21.

Typically, the first machine 21 can be a hydraulic power pump, while the second hydraulic machine 23 can be a hydraulic motor. The hydraulic circuit connecting the power pump 21 to the motor then advantageously comprises a bypass valve 25. The control module is thus configured to control the commissioning and then the deactivation of the first hydraulic machine 21 independently of the commissioning and then the deactivation of the second hydraulic machine 23.

Alternatively, with reference to FIG. 2b, the device 2 is of the “bicycle chain” type. In this case, the first hydraulic machine 21 is connected to the front axle 35 of the vehicle, and the second hydraulic machine 23 is connected to the rear axle 37 of the vehicle. The first machine 21 and the second hydraulic machine 23 can then be configured to alternately provide the function of power pump or motor, according to the needs in additional traction required by one or the other of the axles 35, 37. The module 11 is then configured to implement the commissioning and / or deactivation of the machines 21, 23 simultaneously.

Different embodiments of a self-maintenance system 1 of a hydraulic assistance device of a vehicle will now be described, with reference to Figures 1a to 1f.

A hydraulic assistance device 2 generally comprises a reservoir 12 and a booster pump 10, the booster pump 10 comprising: - a fluid inlet 100 placed in fluid communication with the tank 12, and - a fluid outlet 102 brought into operation fluid communication with the hydraulic machine 21, 23,

The booster pump 10 can be electric or be connected to the power train 31 of the vehicle. The booster pump 10 is also configured to circulate a hydraulic fluid alternately: - from the reservoir 12 towards the hydraulic machine 21, 23 to put the hydraulic machine 21, 23 into service so as to set in motion the mobile elements of commissioning 211, 231, and to maintain there a sufficient pressure to keep the machine 21,23 in service, and - from the hydraulic machine 21,23 to the reservoir 12 to deactivate the hydraulic machine 21, 23, thus causing a reduction of the pressure inside the hydraulic machine 21, 23 and also setting in motion the mobile elements of commissioning 211, 231.

Typically, with reference to FIGS. 1a, 1d and 1e, the hydraulic machine 23, 21 has a fluid inlet 230, 210 placed in fluid communication with the fluid outlet 102 of the booster pump 10, and a fluid outlet, for example the leakage nozzle 233, 213, placed in fluid communication with the reservoir 12, for example by means of the drain 235, 215. In this case, the control module 11 controls the commissioning of the hydraulic machine 23 by activation of the booster pump 10 which delivers the hydraulic fluid into the hydraulic machine 23. Similarly, the control module 11 controls the deactivation of the hydraulic machine 23 by deactivation of the booster pump 10, which causes the fluid to be discharged from the machine hydraulic 23 to tank 12, via drain 235.

Alternatively, with reference to FIGS. 1c and 1f, the hydraulic machine 23, 21 has a fluid inlet-outlet orifice 230, 210 placed in fluid communication with the fluid outlet 102 of the booster pump 10, the booster pump 10 further operating by counter rotation, that is to say that it is configured to deliver hydraulic fluid from the reservoir 12 to the hydraulic machine 23 and vice versa, via a single fluid communication conduit. The operation of such a booster pump 10 is for example described in patent application FR 3 033 529 in the name of the Applicant. In this case, the control module 11 controls the commissioning of the hydraulic machine 23 by activating the booster pump 10 in a first flow direction, and deactivation by activating the booster pump 10 in a second flow direction. , opposite to the first sense.

Advantageously, with reference to FIGS. 1c to 1f, the booster pump 10 comprises a strainer 101 disposed between the reservoir 12 and the fluid inlet 100 of the booster pump 10, and a main filter 103 disposed between the outlet 102 of the booster pump 10, and the hydraulic assistance circuit 27. The strainer 101 and the main filter 103 filter the fluid coming from the reservoir 12, so as to preserve the hydraulic assistance device 2 from ingestion of particulate pollution. The strainer 101 and the main filter 103 are particularly useful when the hydraulic fluid is used and / or has been subjected to high temperatures.

However, the strainer 101 and the main filter 103 tend to become clogged after a certain time of operation of the hydraulic assistance device 2. The operation of the control module 11 of the self-maintenance system 1 then makes it possible, in addition to sweeping the hydraulic machine 21, 23, to unclog the strainer 101 and / or the main filter 103.

In one embodiment of the self-maintenance system 1 illustrated in FIG. 1c, it is the commissioning and the successive deactivation of the hydraulic machine 21, 23, by successive activation of the booster pump 10 in two directions. opposite flow, which ensures circulation of the hydraulic fluid through the strainer 101 successively in two opposite directions of circulation. When the hydraulic machine 21, 23 is deactivated, the reverse flow of hydraulic fluid makes it possible to unclog the strainer 101 by releasing the impurities it has accumulated in the tank.

In another embodiment illustrated in FIG. 1 d, the booster pump 10 operates conventionally, and the self-maintenance system 1 also comprises a vacuum valve 104 controlled by the control module 11. The valve of vacuum 24 allows to drain all or part of the hydraulic assistance circuit 27, preferably by being connected to the high pressure branch of the hydraulic assistance circuit 27 most likely (ie as illustrated in Figure 1d, in operation before), and / or the independent movable elements 211. To do this, the vacuum valve 104 is movable between a passing position and an insulating position, on command of the control module 11. In this case, the control module 11 controls the commissioning of the hydraulic machine 21, 23 by activation of the booster pump 10 which delivers the hydraulic fluid into the hydraulic machine 21, 23, the vacuum valve 104 being insulating. Similarly, the control module 11 controls the deactivation of the hydraulic machine 21, 23 by deactivation of the booster pump 10 and controls the vacuum valve 104 in pass-through mode, which causes the fluid to be discharged from the hydraulic machine 23, 21 to the reservoir 12, via the drain 215 and the fluid circuit 29, both connected to the strainer 101. The return flow of hydraulic fluid makes it possible to unclog the strainer 101 by releasing the impurities it has accumulated in the reservoir . Alternatively, the booster pump 10 is counter-rotating, and the commissioning as well as the successive deactivation of the hydraulic machine 21, 23, by successive activation of the booster pump 10 in two opposite flow directions, ensures circulation. hydraulic fluid through the strainer 101 and the main filter 103 successively in two opposite directions of circulation.

In an alternative embodiment illustrated in FIG. 1e, the self-maintenance system 1 comprises, in addition to the vacuum valve 104, a low pressure selector 270 (or “reverse shuttle valve”, in English terminology) connecting the two lines of the hydraulic assistance circuit 27 to the booster line. This makes it possible to force-feed the line of the hydraulic assistance circuit 27 which always has the lowest pressure. The selector 270 leaves the line of lower pressure permanently open with the booster line. Such a selector 270 is for example described in application FR 3 033 529 in the name of the Applicant, and will not be described in more detail here. Thus, the control module 11 controls the commissioning of the hydraulic machine 21, 23 by activation of the booster pump 10 which delivers the hydraulic fluid into the hydraulic machine 21, 23, the vacuum valve being insulating. Likewise, the control module 11 controls the deactivation of the hydraulic machine 21, 23 by deactivation of the booster pump 10 and controls the vacuum valve 104 in pass-through mode. On the one hand, this results in a discharge of the fluid from the high pressure line of the hydraulic assistance circuit 27 and of the hydraulic machine 21, 23 to the reservoir 12, via the fluid circuit 29 and the drain 215 respectively, both connected strainer 101. On the other hand, this causes the fluid to be evacuated from the low pressure line of the hydraulic assistance circuit 27 to the reservoir 12, via the main filter 103. Clogging of the main filter 103 and of the strainer 101 is then advantageously obtained by these flow returns. Alternatively, the booster pump 10 is counter-rotating, and the commissioning as well as the successive deactivation of the hydraulic machine 21, 23, by successive activation of the booster pump 10 in two opposite flow directions, ensures circulation. hydraulic fluid through the strainer 101 and the main filter 103 successively in two opposite directions of circulation.

In an embodiment illustrated in FIG. 1 f, the self-maintenance system 1 comprises, in addition to the low pressure selector 270, a secondary filter 105 disposed between the main filter 103 and the outlet 102 of the booster pump 10. In parallel to the secondary filter 105 there is a bypass valve 107. In addition, the fluid circuit 29 for evacuating the independent mobile elements 211 is connected to the outlet of the main filter 103. Thus, when the control module 11 controls the commissioning of the hydraulic machine 21, 23 by activation of the booster pump 10 which delivers the hydraulic fluid into the hydraulic machine 21, 23, the flow passes through the valve 107. Then, when the control module 11 deactivates the pump booster 10, the fluid flows back through the fluid circuit 29 and the low pressure line via the selector 270 through the main filter 103 which then discharges its impurities into the secondary filter 105. Alternatively, the pump booster 10 is counter-rotating, and the commissioning as well as the successive deactivation of the hydraulic machine 21, 23, by successive activation of the booster pump 10 in two opposite flow directions, ensures circulation of the hydraulic fluid through the main filter 103 successively in two opposite directions of circulation, with retention of impurities on return by the secondary filter 105.

In any event, in a system 1 configured to ensure continuous self-maintenance of the hydraulic assistance device 2, the control module 11 controls the booster pump 10 and / or the vacuum valve 104 preferably independently of '' a command to engage or disengage the traction assistance of the vehicle. This allows fluid sweeping of all or part of the hydraulic machine 21, 23 and / or unclogging of the strainer 101 and the main filter 103 which are regular, even if assistance is not otherwise required. In addition, for rapid commissioning and deactivation of the hydraulic assistance, it is preferable for the self-maintenance system 1 to include the vacuum valve 104 and / or the counter-rotation booster pump 10. .

In a first embodiment, with reference to FIGS. 1b and 1c to 1f, the mobile elements for putting into service 211 are independent, for example constitute a disc clutch 211, making it possible to engage or disengage the machine 21 from its shaft training (not shown).

The control module 11 is then configured to control the commissioning and then the deactivation of the hydraulic machine 21: - the vehicle being in motion, the sweeping being ensured by the circulation of the hydraulic fluid during the transmission of the movements of the engine torque of the powertrain 31 or of the wheel 33 to the movable elements of the hydraulic machine 21 in service, or - the vehicle being stopped, the sweeping being partially ensured by the only movements of the movable elements of commissioning 211 during the successive commissioning and deactivation of the hydraulic machine 21.

The control module 11 controls the commissioning and / or deactivation of the hydraulic machine 21 in particular independently of an engagement and / or disengagement control of the assistance. This allows partial or complete fluidic sweeping of the hydraulic machine 21, even if assistance is not otherwise required.

In a second embodiment, with reference to FIGS. 1a and 1c to 1f, the mobile commissioning elements 231 are dependent, for example comprise retractable radial pistons 231.

The control module 11 is then configured to control the commissioning and then the deactivation of the hydraulic machine 23: - the vehicle being in motion, the sweeping being ensured by the circulation of the hydraulic fluid during the transmission of the movements of the engine torque of the powertrain 31 or of the wheel 33 to the mobile elements of the hydraulic machine 23 in service, or - the vehicle being stopped, the sweeping being ensured by the movements of the mobile commissioning elements 231 during the commissioning and successive deactivation of the hydraulic machine 23.

In the same way as in the first embodiment, the control module 11 controls the commissioning and / or deactivation of the hydraulic machine 23 in particular independently of an engagement and / or disengagement control of assistance. This allows a more complete fluidic sweep of the hydraulic machine 23, in particular if assistance is required, and that the machine performs a full revolution.

In any event, with reference to FIG. 1b, the control module 11 can advantageously include an automaton 13 configured to automatically implement a self-maintenance process E of a hydraulic assistance device 2.

In addition, still with reference to FIG. 1b, the control module 11 may include a module 15 for estimating the level of wear of the hydraulic fluid. This module 15 can for example measure the intensity of the current consumed by the booster pump 10. The wear of the hydraulic fluid is in fact directly correlated to the power necessary for the pressurization of the hydraulic assistance circuit 27. Alternatively, this module 15 can estimate the level of wear of the hydraulic fluid from the aging state of the latter. The aging state of a hydraulic fluid is characterized by several parameters, including the shearing of the fluid, the oxidation of the fluid, and its particulate contamination. Knowledge of all of these parameters, alone or in combination, and their evolution during the operation of the hydraulic assistance device 2, makes it possible in particular to estimate the viscosity of the hydraulic fluid as a function of its temperature. The viscosity of the hydraulic fluid can also be determined directly by sensors configured for this purpose. In any event, the control module 11 is then configured to receive information relating to the state of wear of the hydraulic fluid.

With reference to FIG. 3, a self-maintenance method E of a hydraulic assistance device 2 of a vehicle will now be described, the self-maintenance method E being implemented by an auto system. maintenance 1 according to any one of the previously described embodiments.

Such a method E comprises the steps consisting in: - putting into service E1 the hydraulic machine 21, 23 for a determined period, then - deactivating E2 the hydraulic machine 21, 23 at the end of said period.

This ensures a sweep of all (complete sweep) or part (partial sweep) of the hydraulic machine 21, 23 by setting in motion the mobile elements to force the circulation of hydraulic fluid, the steps of putting into service E1 and of deactivation E2 being further implemented independently of an engagement and / or disengagement command from the assistance. This ensures regular self-maintenance of the hydraulic assistance device 2, even if assistance is not otherwise required, especially if it is rarely required.

Advantageously, the deactivation step E2 can also be implemented by the security module 14 in order to preserve the safety of the hydraulic machine 21, 23 when the vehicle reaches excessively high speeds.

Even more advantageously, the alternation of the steps of putting into service E1 and deactivation E2 is repeated successively at a given frequency, for example ten times in succession, so as to homogenize the sweeping of the hydraulic machine 21, 23. This alternation can be pre-registered by a user or the manufacturer.

The duration of the commissioning step E1 can be pre-recorded by the manufacturer of the self-maintenance system 1. Alternatively, in the case where the hydraulic machine 23 is connected to a vehicle wheel 33, the hydraulic machine 23 is put into service for a period corresponding to one wheel revolution 23.

Advantageously, the method E is implemented at a given rate, said rate being able to be functional and / or temporal, for example once every month of operation of the vehicle. By functional cadence, it is understood that the method E is implemented at a cadence which depends on the way in which the hydraulic assistance assistance device 2 is used, for example each time the vehicle has traveled a given distance, when that the vehicle reaches a defined use rate or load rate, or when pressure thresholds are reached in the hydraulic assistance circuit 27.

Advantageously, method E is implemented from a given wear level of the fluid

In a first embodiment of method E, with reference to FIG. 4a, assistance is not otherwise required.

In this case, if the vehicle is moving, then the method is implemented for a given range of vehicle speed, for example the vehicle speed being between 0 and 40 km / h. Above a certain vehicle speed level, putting the hydraulic machine into operation on a wheel can damage the machine.

Alternatively, method E can be implemented while the vehicle is stationary, typically at a road light, preferably each time the vehicle is started. This has the advantage of not interfering with the handling of the vehicle. In this case, if the mobile commissioning elements 211 are independent, then the scanning is only partial.

Preferably, the commissioning step E1 is implemented over a period corresponding to a complete rotation of a hydraulic machine 21, 23 of the vehicle, which makes it possible to move all the parts, and to completely renew the hydraulic fluid contained in the cylinders of the machine 21, 23, but also to circulate the hydraulic fluid in the pipes more completely. In particular if a rotation of a machine 21, 23 corresponds to one revolution of the wheel 33, the duration will correspond to one complete rotation of a wheel 33.

In a second embodiment of method E, still with reference to FIG. 4a, assistance is also required.

In this case, if the vehicle is in motion, the method E is not implemented, and the sweeping is ensured by the nominal operation of the hydraulic assistance device 2.

Alternatively, method E can be implemented while the vehicle is stationary, typically at a road light, preferably each time the vehicle is started. In this case, if the mobile commissioning elements 211 are independent, then the scanning is only partial.

In a third embodiment of method E, with reference to FIG. 4b, the assistance device comprises a reservoir 12, a booster pump, preferably with counter-rotation 10 and a set of filters, for example a strainer 101 and a main filter 103, as previously described. In this embodiment, in addition to sweeping the hydraulic machine, unclogging of the filters 101, 103 is advantageously obtained.

The method E then comprises the steps consisting in putting into service E1 the hydraulic machine 21, 23 for a determined period, for example by activating the booster pump 10, and in deactivating E2 the hydraulic machine 21, 23, at the end of the commissioning step E1, so as to circulate hydraulic fluid through the filters 101, 103 successively in two opposite directions of circulation. As previously described, deactivation E2 can be implemented by deactivation of the booster pump 10 and reflux of the hydraulic fluid to the reservoir 12, or by activation of the booster pump 10 in the opposite direction, if the latter is to contra-rotation. In addition, as previously described, the steps of commissioning E1 and deactivation 2 are implemented independently of an engagement command and / or disengagement of the assistance.

Advantageously, method E can then be implemented, the assistance being required elsewhere. In this case, if the vehicle is in motion, the deactivation step E2 momentarily cuts off the assistance. The method E then provides for a return to service step E3 consecutive to the deactivation step E2, so as to ensure the safety of the vehicle. Preferably, the deactivation step E2 is implemented over a period corresponding to a wheel rotation 33 of the vehicle. In particular if a rotation of a machine 21, 23 corresponds to one revolution of the wheel 23, the duration will correspond to one complete rotation of a wheel 23.

Method E allows the parts of the hydraulic assistance device 2 to be moved in regular motion, even if it is not in use, which avoids having wear or corrosion localized at the points of contact of immobile parts, it avoids having stationary hydraulic fluid which could receive repeated thermal cycles, and it avoids having sedimentation or polymerization of the hydraulic fluid. Also, it allows unclogging filters 101, 103. By its effects, it keeps the hydraulic assistance device 2 operational longer, between two intervals for draining the hydraulic fluid. It can also allow you to space out the emptying dates, and therefore reduce the cost of operating the system.

The self-maintenance system 1 can be used for the benefit of any hydraulic traction assistance device, in particular to transform a 4x2 vehicle into a 4x4 vehicle, or to assist the carrying wheels of a vehicle, for example wheels. truck steering, truck or trailer carrying axles, construction or agricultural machine carrying axles, temporary low-speed hydraulic transmissions for service or work vehicles, known as "creep drives", or vehicles or convertible road / rail vehicles.

Claims (13)

1. Self-maintenance method (E) of a hydraulic assistance device (2) of a vehicle, said device (2) comprising: • a hydraulic machine (21, 23), • a tank (12) , • a filter (101, 103), • a booster pump (10) comprising: o a fluid inlet (100) placed in fluid communication with the reservoir (12), and o a fluid outlet (102) fluid communication with the hydraulic machine (21, 23), the device (2) being configured to circulate a hydraulic fluid alternately: • from the reservoir (12) towards the hydraulic machine (21, 23), by action of the pump booster (10), to put the hydraulic machine into service (21, 23) and thus engage the hydraulic assistance, and • from the hydraulic machine (21, 23) to the tank (12) to deactivate the hydraulic machine (21, 23) and thus disengage the hydraulic assistance, the engagement and disengagement of the assistance being controllable on command, the method (E) comprising the steps consisting in: • putting into service (E1) the hydraulic machine (23) for a determined duration, and • deactivating (E2) the hydraulic machine (23), at the end of the commissioning step (E1), so as to circulate hydraulic fluid through the filter (101, 103) successively in two opposite directions of circulation, the steps of commissioning (E1) and deactivation (E2) being implemented independently of an engagement and / or disengagement assistance order. 2. Method (E) according to claim 1, in which the method (E) is implemented for a given range of vehicle speed, for example the vehicle speed being between 0 and 40 km / h. 3. Method (E) according to one of claims 1 or 2, wherein the alternation of the steps of commissioning (E1) and deactivation (E2) is repeated successively at a given frequency, for example ten times in succession . 4. Method (E) according to one of claims 1 to 3, in which the assistance is engaged, the method (E) being then alternately implemented: • the vehicle being in motion, the assistance then being partly disengaged during the deactivation step (E2), or • the vehicle being stopped. 5. Method (E) according to one of claims 1 to 3, wherein the assistance is disengaged, the method being alternately implemented the vehicle being in motion, or the vehicle being stopped. 6. Method (E) according to one of claims 1 to 5, wherein the method (E) is implemented each time the vehicle is started. 7. Method (E) according to one of claims 1 to 6, wherein the method (E) is implemented at a given rate, said rate can be • functional, for example each time the vehicle has traveled a given distance, and / or • time, for example once every month of vehicle operation. 8. Method (E) according to one of claims 1 to 7, wherein the method (E) is implemented from a given level of wear of the hydraulic fluid. 9. Self-maintenance system (1) of a hydraulic assistance device (2) of a vehicle, said device (2) comprising: • a hydraulic machine (21, 23), • a tank (12) , • a filter (101, 103), • a booster pump (10), said booster pump (10) comprising o a fluid inlet (100) placed in fluid communication with the reservoir (12), and o an outlet of fluid (102) placed in fluid communication with the hydraulic machine (21, 23), the device (2) being configured to circulate a hydraulic fluid alternately: • from the reservoir (12) to the hydraulic machine (21, 23) by action of the booster pump (10), to put into service the hydraulic machine (21, 23) and thus engage the hydraulic assistance, and • from the hydraulic machine (21, 23) to the tank (12) to deactivate the hydraulic machine (21, 23) and thus disengage the hydraulic assistance, the engagement and disengagement of the ass istance being controllable on command, said system (2) comprising a control module (11) configured to implement a method (E) according to one of claims 1 to 8. 10. Self-maintenance system (1) according to claim 9, comprising a strainer (101) disposed between the reservoir (12) and the fluid inlet (100) of the Gave pump (10), and a filter. main (103) disposed between the fluid outlet (102) of the booster pump (10) and the hydraulic machine (230), the strainer (101) and the main filter (103) being configured to preserve the assistance device hydraulic (2) ingestion of particulate pollution. 11. Self-maintenance system (1) according to claim 10, comprising a secondary filter (105) and a bypass valve (107), disposed between the main filter (103) and the fluid outlet (102) of the booster pump (10), the secondary filter (105) being configured to discharge impurities from the main filter (103) during the reflux of hydraulic fluid from the hydraulic machine (21, 23). 12. Self-maintenance system (1) according to one of claims 9 to 11, further comprising a vacuum valve (104) controlled by the control module (11), and configured to promote the reflux of hydraulic fluid from the hydraulic machine (21, 23). 13. Vehicle comprising a hydraulic assistance device (2) and a self-maintenance system (1) according to one of claims 9 to 12.