CN111417803A

CN111417803A - Filter for dredging inlet

Info

Publication number: CN111417803A
Application number: CN201880077461.5A
Authority: CN
Inventors: 巴斯蒂安·克莱皮特; 克里斯多夫·古祖
Original assignee: Poclain Hydraulics Industrie
Current assignee: Poclain Hydraulics Industrie
Priority date: 2017-10-09
Filing date: 2018-10-08
Publication date: 2020-07-14
Also published as: FR3072148B1; FR3072148A1; EP3695142A1; WO2019072740A1

Abstract

The invention relates to a method (E) for self-maintenance of a hydraulic auxiliary device (2) of a vehicle, said device (2) comprising: hydraulic mechanisms (21, 23); a reservoir (12); filters (101, 103); and a booster pump (10), said method (E) comprising the steps of: activating (E1) the hydraulic machine (23) during a determined period, and deactivating (E2) the hydraulic machine (23) at the end of the activation step (E1) so as to circulate hydraulic fluid through the filter (101, 103) in two opposite circulation directions in succession, the steps of activating (E1) and deactivating (E2) being carried out independently of the command for activating and/or deactivating the assistance.

Description

Filter for dredging inlet

Technical Field

The invention relates to a self-maintenance system and a self-maintenance method for a hydraulic auxiliary device of a vehicle.

The invention is more particularly directed to self-maintenance of hydraulic auxiliary devices that are less used and/or have lost their hydraulic fluid.

Background

For the purpose of proposing additional drives for one or more wheels of the vehicle, many hydraulic auxiliary devices for vehicles with traction or temporary hydraulic change have been proposed.

These devices typically employ at least two hydraulic machines that are placed in fluid communication and configured to convert the pressure difference between their inlets and their outlets into drive torque, and vice versa.

Typically, such devices comprise a hydraulic pump, a so-called power pump, coupled to the powertrain of the vehicle, said power pump outputting into one or more hydraulic motors coupled to the non-driven wheels. It is thus possible to change from propulsion of a 4x2 type vehicle to propulsion of a 4x4 type, for example in an environment where the vehicle is at risk of skidding.

Alternatively, the assistance comprises a first hydraulic mechanism coupled to a front axle of the vehicle and a second hydraulic mechanism coupled to a rear axle of the vehicle. The two mechanisms may alternately function as a power pump or a hydraulic motor, depending on the need for additional drive of one or the other of the shafts. This type of device is commonly referred to as "chain drive" and also makes it possible to convert a 4x2 carrier into a 4x4 carrier.

In any case, such a system is releasable so as to be able to enable or disable the assistance according to the user's command and/or the vehicle's driving conditions (for example at a given speed threshold or at a certain slip threshold). Furthermore, these devices are controllable on command by an automatic machine or by a user, in order to monitor at all times the assistance provided to the wheels.

Thus, for example, an auxiliary system that would only be activated to avoid skidding may remain inactive for a very long time. For example, a vehicle given such a system will only activate assistance in the presence of snow. It is therefore possible that in some countries assistance is never enabled for a large part of the year.

The hydraulic machines of such systems usually comprise an assembly of movable parts which are in relative movement with respect to each other under the action of a hydraulic fluid circulating within the hydraulic machine. However, in order to ensure the correct operation of such a mechanism, it is necessary to activate the movement of the movable part periodically, in order to avoid the occurrence of wear or corrosion at the level of the contact points, or deposits in different locations, in particular in the bottom and in the filter. When the vehicle receives vibrations from driving, contact of the immovable parts may cause local abrasion. Deposits can lead to some aggregation, adhesion of parts or clogging of the strainers, which risks damaging the surfaces when the mechanism is started again after a long period of inactivity, and significantly shortens their life.

In addition, the higher operating temperatures of such mechanisms can lead to premature aging of the operating fluid by heating the stagnant deposits at certain particularly hot localized locations. A portion of the fluid that remains immobile in this part of the system will be heated periodically and may then deteriorate locally. Such degraded fluid may coalesce and create a blockage, or travel through the system on first activation and be placed on a coarse filter or small mechanism. This is particularly problematic when the fluid circuit of the auxiliary device is equipped with a filtration system aimed at preventing impurities from being ingested by the components of the device. Typically, a strainer for filtration is usually imparted to the feed pump of such a circuit at the point where hydraulic fluid is drawn from the reservoir. Fouling of the strainer can make the auxiliary system unusable due to the fact that: the feed pump will no longer be able to suck through the strainer and thus no longer be able to generate the pressure required for activation. This significantly shortens the usage time between two discharges of the system.

In addition to shortening the life of the hydraulic auxiliary device, the aforementioned drawbacks require regular maintenance by specialists. Such maintenance can become expensive and time consuming for the user.

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

Disclosure of Invention

It is an object of the present invention to provide continuous self-maintenance of hydraulic auxiliary devices of a vehicle without changing the structure of the devices.

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

Another object of the invention is to increase the time interval between two discharges of the hydraulic auxiliary device separating the vehicles.

The invention proposes in particular a self-maintenance system of a hydraulic auxiliary device of a vehicle, said device comprising:

a hydraulic mechanism for the hydraulic motor to be operated,

the flow rate of the gas flowing through the gas reservoir,

the number of filters is one of the filters,

a feed pump comprising:

an omicron fluid inlet disposed in fluid communication with the reservoir, and

a fluid outlet disposed in fluid communication with the hydraulic machine,

the device is configured to alternately circulate hydraulic fluid:

by activating the feed pump from the reservoir to the hydraulic machine to activate the hydraulic machine and thus enable hydraulic assistance, and

from the hydraulic machine to the reservoir, to deactivate the hydraulic machine and thus to release the hydraulic assistance, the activation and release of assistance being controllable on command,

the method comprises the steps of:

starting the hydraulic machine for a certain period of time and then

Deactivating the hydraulic machine at the end of the activation step, in order to circulate hydraulic fluid through the filter in two opposite circulation directions one after the other,

the steps of activating and deactivating are performed independently of the command to activate and/or deactivate assistance.

Due to this self-maintenance method, the filter of the hydraulic auxiliary device is periodically unblocked by the successive activation and deactivation of the hydraulic means. The intermittent activation is also independent of commands to enable and/or disable hydraulic assist. Thus, continuous self-maintenance of the hydraulic assistance system is possible, even if the system is not used (checked) regularly. Such continuous self-maintenance includes maintaining the integrity of the hydraulic fluid and the quality of the lubrication, as well as periodically unblocking the filter. This self-maintenance is therefore different from the periodic maintenance operations performed by professionals, which involve the replacement of the hydraulic fluid and, where appropriate, the filter of the hydraulic auxiliary system. Furthermore, such a system provides the advantage of not changing the existing hydraulic assist structure, while significantly increasing the life.

The method according to the invention may further comprise the following features taken alone or in combination:

it is implemented for a given range of vehicle speeds, for example between 0 and 40km/h,

the alternation of the steps of activation and deactivation is repeated successively at a given frequency, for example ten times in succession,

-said assistance is enabled, said method then being carried out alternately in:

o in the state in which the vehicle is in motion, then the assistance is partially released in the step of deactivation, or

O in the state where the vehicle is stopped.

-the assistance is deactivated, the method being carried out alternately with the vehicle in a state of movement or with the vehicle in a state of stop,

it is carried out each time the vehicle is activated, and

it is implemented at a given rate, said rate being

Functional, e.g. whenever the vehicle has traveled a given distance, and/or

Temporal, e.g. once a month of operation of the vehicle.

It is carried out starting from a given loss level of hydraulic fluid.

The invention also relates to a system for self-maintenance of a hydraulic auxiliary device of a vehicle, said device comprising:

a hydraulic mechanism for the hydraulic motor to be operated,

the flow rate of the gas flowing through the gas reservoir,

the number of filters is one of the filters,

a feed pump comprising:

an omicron fluid inlet disposed in fluid communication with the reservoir, and

a fluid outlet disposed in fluid communication with the hydraulic machine,

the device is configured to alternately circulate hydraulic fluid:

from the hydraulic machine to the reservoir to deactivate the hydraulic machine and thus to release the hydraulic assistance, the activation and release of assistance being controllable on command.

The system includes a control module configured to implement the method as previously described.

The system according to the invention may further comprise the following features taken alone or in combination:

it comprises a coarse filter arranged between the reservoir and a fluid inlet of the feed pump, and a main filter arranged between a fluid outlet of the feed pump and the hydraulic means, the coarse filter and the main filter being configured to keep the hydraulic auxiliary device free from ingestion of particulate contaminants,

it comprises a bypass valve arranged between the main filter and the fluid outlet of the feed pump and a secondary filter configured to discharge impurities of the main filter during the return flow of hydraulic fluid from the hydraulic machine, and

it further comprises a vacuum valve commanded by the control module and configured to promote the return flow of hydraulic fluid from the hydraulic machine.

The invention finally relates to a vehicle comprising a self-maintenance system as described previously and a releasable hydraulic auxiliary device.

Drawings

Other characteristics, objects and advantages of the invention will become apparent upon reading the following detailed description and reference to the attached drawings, given by way of non-limiting example, and in which:

figures 1a to 1f schematically show different embodiments of a self-maintenance system of a hydraulic auxiliary device of a vehicle,

figures 2a and 2b schematically show different embodiments of the hydraulic assistance device of the vehicle,

fig. 3 shows the different steps of the self-maintenance method of the hydraulic auxiliary device of the vehicle, and

fig. 4a and 4b show functional diagrams of different embodiments of a method of self-maintenance of a hydraulic auxiliary device of a vehicle.

Detailed Description

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

In the remainder of the text, the term "self-maintenance" is understood to mean that all actions are carried out automatically by the system 1 as described, for the purpose of ensuring continuous availability of the functions of the hydraulic auxiliary devices 2 of the vehicle. As will be explained in more detail, the self-maintenance of the hydraulic assistance device 2 comprises the periodic decontamination of the different elements of the device 2, such as the

filters

101, 103 or the areas where deposits are present, by circulating hydraulic fluid within the device 2. Self-maintenance also includes renewal and regular homogenization of the hydraulic fluid by stirring and mixing, with the aim of avoiding fluid stagnation, in particular in the portion of the elements of the device 2 close to the thermal elements of the vehicle.

With reference to fig. 1a to 1f, 2a and 2b, the hydraulic assistance device 2 of the vehicle comprises

hydraulic mechanisms

21, 23.

The

hydraulic machine

21, 23 comprises a

fluid inlet

210, 230 and a

fluid outlet

212, 232 as well as mechanical elements movable under the influence of the hydraulic fluid circulating in the

hydraulic machine

21, 23. The

fluid inlets

210, 230 and

outlets

212, 232 are generally disposed in fluid communication with the hydraulic auxiliary circuit 27. Such a

mechanism

21, 23 is then configured to convert the pressure difference between the

fluid inlet

210, 230 and the

fluid outlet

212, 232 into a driving torque and vice versa, the conversion being effected by the movement of the movable elements of the

hydraulic mechanism

21, 23. This conversion further makes it possible to provide the hydraulic assistance function of the device 2.

The

hydraulic machines

21, 23 are further configured to be alternately activated or deactivated, which activation and deactivation provides for the activation and deactivation of the hydraulic assistance, respectively. In this connection, the

hydraulic machines

21, 23 comprise an activating

movable element

211, 231, which is also movable under the influence of the hydraulic fluid circulating in the

hydraulic machines

21, 23. By way of non-limiting example, such

movable elements

211, 231 may be clutches 211 with discs or pawls, for example of the same type as state-of-the-art gearboxes. In this case, the actuation movable elements 211 are coupled to a fluid circuit 29 different from the hydraulic auxiliary circuit 27 and their movement is independent of the other movable elements of the hydraulic machine 21. These elements are referred to as "independently" actuating movable elements 211. Alternatively, such elements may be radial pistons 231 which are released from their cams by retraction of the pistons 231. In this case, the actuation movable element 231 is directly coupled to the hydraulic auxiliary circuit 27. Their movement depends on the other movable elements of the hydraulic machine, or even the same element 231. These elements are referred to as "slave" actuating movable elements 231. The activation and deactivation of

such mechanisms

21, 23 is described, for example, in patent applications FR 2996267 and FR 3033529 in the name of the applicant and will therefore not be further detailed herein.

The

hydraulic machines

21, 23 are generally provided with a

casing drain

215, 235 that collects the internal leakages of all the components of the

machines

21, 23 subjected to pressure and sends them back to the oil reservoir 12. More specifically, the

hydraulic machines

21, 23 may be provided with leakage nozzles 213, 233 aimed at renewing the oil and cooling certain internal components, which are coupled to discharge

pipes

215, 235, through which excess hydraulic fluid can be discharged towards the reservoir 12.

Still referring to fig. 1a to 1f, 2a and 2b, the vehicle to which such a hydraulic auxiliary device 2 is assigned comprises a self-maintenance system 1 for the device 2. The system 1 comprises in particular a control module 11 configured to command hydraulic assistance. More precisely, the control module 11 is configured to receive commands to activate or deactivate hydraulic assistance and to send corresponding commands to activate or deactivate the

hydraulic machines

21, 23.

The activation and deactivation of the auxiliary is controllable by command. In this regard, commands to activate or deactivate hydraulic assist may be sent directly to the control module 11 by a user. Alternatively, such commands may be sent by the robot 13 of the vehicle according to the driving conditions. Typically, the robot 13 requires hydraulic assistance when a skid is detected, for example when the vehicle is dealing with a snow or sand surface. In the same way, the robot 13 switches off the hydraulic assistance when the vehicle obtains a speed greater than the level allowed by the

hydraulic machines

21, 23.

The control module 11 is further configured to command the activation of the

hydraulic machines

21, 23 for a certain period of time and then to deactivate the

hydraulic machines

21, 23 at the end of this certain activation period, said command being accordingly independent of the activation or deactivation command of the auxiliary. More precisely, the control module 11 is configured to control the operation of the hydraulic assistance device 2 for self-maintenance purposes, alternately in response to an activation or deactivation command or according to its own initiative in the absence of receiving an activation and/or deactivation command. In particular, activating the

hydraulic machines

21, 23 and then deactivating the

hydraulic machines

21, 23 for a determined period of time ensures that the movable elements of the

hydraulic machines

21, 23 are moved in order to force hydraulic fluid to circulate in all or a part of the

hydraulic machines

21, 23. This is referred to as a full or partial flushing of the

hydraulic machines

21, 23. Regular self-maintenance of the hydraulic assistance device 2 is thus advantageously possible.

Referring to fig. 2a, the hydraulic mechanism may be a hydraulic power pump 21. In this case, the power pump 21 is coupled (for its driving) to the powertrain 31 of the vehicle. The movable elements of the power pump 21 are then configured such that their movement makes it possible to convert the torque supplied by the powertrain 31 into a pressure difference between the fluid inlet 210 and the outlet 212 of the power pump 21.

Alternatively, still referring to fig. 2a, the hydraulic machine is a hydraulic motor 23. The motor 23 is coupled to the wheels 33 of the vehicle. The movable elements of the motor 23 are then configured so that their movement makes it possible to convert the pressure difference between the fluid inlet 230 and the outlet 232 of the motor 23 into a torque transmitted to the wheels 33 when the assistance is activated. The wheels 33 are typically the supporting wheels of a mechanical transmission not coupled to a 4x2 vehicle. When the assistance is released and the vehicle is in motion, the motor 23 is also activated and the movable element can move under the effect of the torque exerted by the rotating wheel 33. However, there is typically a vehicle speed limit above which the safety module 14 of the hydraulic assist device 2 automatically deactivates the hydraulic motor 23 to maintain the safety of the motor 23.

Referring to fig. 2a, the hydraulic assistance device may further comprise a first hydraulic machine 21 and a second hydraulic machine 23, the inlet 210 of the first machine 21 being arranged in fluid communication with the outlet 232 of the second machine 23, and the inlet 230 of the second machine 23 being arranged in fluid communication with the outlet 212 of the first machine 21.

Typically, the first mechanism 21 may be a hydraulic power pump, and the second hydraulic mechanism 23 may be a hydraulic motor. The hydraulic circuit linking the power pump 21 to the motor then advantageously comprises a bypass valve 25. The control module is thus configured to command activation and then deactivation of the first hydraulic machine 21 independently of activation and then deactivation of the second hydraulic machine 23.

Alternatively, with reference to fig. 2b, the device 2 is of the "chain drive" type. In this case, the first hydraulic machine 21 is coupled to the front axle 35 of the vehicle, and the second hydraulic machine 23 is coupled to the rear axle 37 of the vehicle. The first and second

hydraulic mechanisms

21, 23 may then be configured to alternately provide a powered pump or motor function depending on the need for additional drive by one or the other of the shafts 35, 37. The control module 11 is then configured to simultaneously effect activation and/or deactivation of the

mechanisms

21, 23.

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

The hydraulic auxiliary device 2 generally comprises a reservoir 12 and a feed pump 10, the feed pump 10 comprising:

a fluid inlet 100 disposed in fluid communication with the reservoir 12, an

A fluid outlet 102, which is arranged in fluid communication with the

hydraulic machines

21, 23,

the feed pump 10 may be electric or coupled to a powertrain 31 of the vehicle. The charge pump 10 is furthermore configured to circulate alternately hydraulic fluid:

from the reservoir 12 to the

hydraulic machines

21, 23 to activate the

hydraulic machines

21, 23, in order to displace the activating

movable elements

211, 231 therein and to maintain sufficient pressure therein to maintain the

machines

21, 23 in operation, and

from the

hydraulic machine

21, 23 to the reservoir 12 to deactivate the

hydraulic machine

21, 23, resulting in a reduction of the pressure in the

hydraulic machine

21, 23 and also in a movement of the activating

movable element

211, 231.

Typically, referring to fig. 1a, 1d and 1e, the

hydraulic machines

23, 21 are provided with:

fluid inlets

230, 210 positioned in fluid communication with the fluid outlet 102 of the charge pump 10; and fluid outlets, such as leak nozzles 233, 213, disposed in fluid communication with the reservoir 12, such as by way of

drain pipes

235, 215. In this case, the control module 11 commands the activation of the hydraulic machine 23 by activating the feed pump 10 which outputs hydraulic fluid into the hydraulic machine 23. In the same way, the control module 11 commands deactivation of the hydraulic machine 23 by deactivating the feed pump 10, which results in fluid being discharged from the hydraulic machine 23 to the reservoir 12 via the discharge pipe 235.

Alternatively, with reference to fig. 1c and 1f, the

hydraulic mechanism

23, 21 is provided with a fluid inlet-

outlet opening

230, 210 which is placed in fluid communication with the fluid outlet 102 of the feed pump 10, the feed pump 10 furthermore being operated by counter-rotation, i.e. it is configured to output hydraulic fluid from the reservoir 12 to the hydraulic mechanism 23 and vice versa through a single fluid flow conduit. The operation of such a feed pump 10 is described, for example, in patent application FR 3033529 in the name of the applicant. In this case, the control module 11 commands the activation of the hydraulic machine 23 by activating the feed pump 10 in a first direction of output and deactivates by activating the feed pump 10 in a second direction of output opposite to the first direction.

Advantageously, with reference to fig. 1c to 1f, the feed pump 10 comprises a coarse filter 101 arranged between the reservoir 12 and the fluid inlet 100 of the feed pump 10, and a main filter 103 arranged between the outlet 102 of the feed pump 10 and the hydraulic auxiliary circuit 27. The coarse filter 101 and the main filter 103 filter the fluid from the reservoir 12 in order to keep the hydraulic auxiliary device 2 free from ingestion of particulate contaminants. The coarse filter 101 and the main filter 103 are particularly useful when the hydraulic fluid has been lost and/or subjected to high temperatures.

However, after the hydraulic assist apparatus 2 has been operating for a certain amount of time, the coarse filter 101 and the main filter 103 are prone to becoming clogged. The operation of the control module 11 of the self-maintenance system 1 then makes it possible to unclog the coarse filter 101 and/or the main filter 103 in addition to flushing the

hydraulic machines

21, 23.

In the embodiment of the self-maintenance system 1 shown in fig. 1c, the activation and subsequent deactivation of the

hydraulic machines

21, 23 by activating the feed pump 10 successively in two opposite output directions provides for the circulation of hydraulic fluid through the coarse filter 101 successively in two opposite circulation directions. The reverse flow of hydraulic fluid makes it possible to unclog the strainer 101 by releasing the impurities it has accumulated into the reservoir when the hydraulic means 21, 23 are deactivated.

In another embodiment, shown in fig. 1d, the feed pump 10 operates conventionally, and the self-maintenance system 1 further comprises a vacuum valve 104 commanded by the control module 11. The vacuum valve 24 is used to vent all or a portion of the hydraulic auxiliary circuit 27, preferably through a high pressure branch (i.e., when driving forward as shown in fig. 1 d) and/or a separate movable element 211 coupled to the most likely hydraulic auxiliary circuit 27. To this end, the vacuum valve 104 is movable between a passage position and an isolation position upon command of the control module 11. In this case, the control module 11 commands the activation of the

hydraulic machines

21, 23 by activating the feed pump 10 which outputs hydraulic fluid into the

hydraulic machines

21, 23, the vacuum valve 104 being isolated. In the same way, the control module 11 commands the deactivation of the

hydraulic machines

21, 23 by deactivating the feed pump 10 and commands the vacuum valve 104 in the passage mode, which results in the fluid being discharged from the

hydraulic machines

23, 21 towards the reservoir 12 via the discharge pipe 215 and the fluid circuit 29 (both coupled to the coarse filter 101). The return flow of hydraulic fluid makes it possible to unclog the strainer 101 by releasing the impurities it has accumulated into the reservoir. Alternatively, the feed pump 10 is of the counter-rotating type, and the activation and subsequent deactivation of the

hydraulic machines

21, 23 by activating the feed pump 10 in two opposite output directions in succession achieves circulation of the hydraulic fluid through the coarse filter 101 and the main filter 103 in two opposite circulation directions in succession.

In an alternative embodiment shown in fig. 1e, the self-maintenance system 1 comprises, in addition to the vacuum valve 104, a low pressure selector switch 270 (or "shuttle valve") which couples the two lines of the hydraulic auxiliary circuit 27 to the supply line. This makes it possible to supply the line of the hydraulic auxiliary circuit 27 which always has the lowest pressure. The selector switch 270 causes the lowest pressure line to be permanently open to the supply line. Such a selector switch 270 is for example described in application FR 3033529 in the name of the applicant and will therefore not be further detailed herein. The control module 11 thus commands the activation of the

hydraulic machines

21, 23 by activating the feed pump 10 which outputs hydraulic fluid into the

hydraulic machines

21, 23, the vacuum valves being isolated. In the same way, the control module 11 commands the deactivation of the

hydraulic machines

21, 23 by deactivating the feed pump 10 and commands the vacuum valve 104 in the passage mode. On the one hand, this results in fluid being discharged from the high-pressure line of the hydraulic auxiliary circuit 27 and from the

hydraulic machines

21, 23 via the fluid circuit 29 and the discharge pipe 215 (both coupled to the strainer 101) respectively, towards the reservoir 12. On the other hand, this results in fluid being discharged from the low-pressure line of the hydraulic auxiliary circuit 27 towards the reservoir 12 via the main filter 103. The opening of the main filter 103 and the coarse filter 101 is then advantageously obtained by these return flows. Alternatively, the feed pump 10 is of the counter-rotating type, and the activation and subsequent deactivation of the

hydraulic machines

In the embodiment shown in fig. 1f, the self-maintenance system 1 comprises, in addition to the low-pressure selector switch 270, a secondary filter 105 arranged between the main filter 103 and the outlet 102 of the feed pump 10. Parallel to the secondary filter 105 is a bypass valve 107. Furthermore, the fluid circuit 29 for putting the separate movable element 211 in vacuum is coupled to the outlet of the main filter 103. Thus, when the control module 11 commands the activation of the

hydraulic machines

21, 23 by activating the feed pump 10 which outputs hydraulic fluid into the

hydraulic machines

21, 23, the fluid passes through the valve 107. Then, when the control module 11 deactivates the charge pump 10, fluid flows from the fluid circuit 29 and the low pressure line back through the primary filter 103 via the selector switch 270, which then drains its impurities into the secondary filter 105. Alternatively, the feed pump 10 is of the counter-rotating type, and activating and then deactivating the

hydraulic machines

21, 23 by activating the feed pump 10 in two opposite output directions in succession achieves circulation of the hydraulic fluid through the main filter 103 in two opposite circulation directions in succession, with the returned impurities being retained by the secondary filter 105.

In any case, in a system 1 configured to provide continuous self-maintenance of the hydraulic assistance device 2, the control module 11 preferably commands the feed pump 10 and/or the vacuum valve 104 independently of the activation or deactivation command of the traction assistance of the vehicle. This allows the fluid to flush all or part of the

hydraulic machines

21, 23 and/or to unclog the coarse filter 101 and the main filter 103 (which are regular), even if assistance is no longer required. Furthermore, for the hydraulic assisted activation and rapid deactivation, it is preferred that the self-maintenance system 1 comprises a vacuum valve 104 and/or a feed pump 10 of the counter-rotating type.

In a first embodiment, with reference to fig. 1b and 1c to 1f, the actuation mobile element 211 is independent, for example constituting a disk clutch 211, making it possible to engage or disengage the mechanism 21 from its drive shaft (not shown).

The control module 11 is then configured to command the hydraulic machine 21 to be activated and then deactivated:

the vehicle is in motion, providing flushing by circulation of hydraulic fluid when transmitting the movement of the drive torque of the drive train 31 or wheels 33 to the elements of the hydraulic machine 21 that have been activated, or

Vehicle stop, flushing being provided partially by the mere movement of said activating movable element 211, upon the successive activation and deactivation of the hydraulic machine 21.

The control module 11 commands the activation and/or deactivation of the hydraulic machine 21, in particular independently of the command to activate and/or deactivate assistance. This allows a partial or complete flushing of the hydraulic machine 21 even in the case that assistance is no longer required.

In a second embodiment, with reference to fig. 1a and 1c to 1f, said activating movable element 231 is subordinate and comprises, for example, a retractable radial piston 231.

The control module 11 is then configured to command the hydraulic machine 23 to be activated and then deactivated:

the vehicle is in motion, providing flushing by circulation of hydraulic fluid when transmitting the movement of the driving torque of the drive train 31 or wheels 33 to the movable element of the hydraulic machine 23 that has been activated, or

Vehicle stop, flushing being provided by the movement of said activating movable element 231 upon the successive activation and deactivation of the hydraulic machine 23.

In the same way as in the first embodiment, the control module 11 commands the activation and/or deactivation of the hydraulic machine 23, in particular independently of the command to activate and/or deactivate assistance. This allows a more complete flushing of the hydraulic machine 23, in particular in case assistance is required and the machine performs a complete rotation.

In any case, with reference to fig. 1b, the control module 11 may advantageously comprise an automaton 13 configured to automatically implement the self-maintenance method E of the hydraulic assistance device 2.

Furthermore, still referring to fig. 1b, the control module 11 may comprise a module 15 for estimating the level of loss of hydraulic fluid. The module 15 may, for example, measure the amperage of the current drawn by the feed pump 10. This is because the loss of hydraulic fluid is directly related to the power required to pressurize the hydraulic auxiliary circuit 27. Alternatively, the module 15 may estimate the loss level of the hydraulic fluid based on an aging condition of the hydraulic fluid. The aging condition of hydraulic fluids is characterized by several parameters, including the shear of the fluid, the oxidation of the fluid, and particulate contamination thereof. Knowing all these parameters (alone or in combination) and their variation 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 may also be determined directly by a sensor configured for this purpose. In any case, the control module 11 is always configured to receive an item of information relating to a condition of depletion of the hydraulic fluid.

With reference to fig. 3, a self-maintenance method E of a hydraulic auxiliary device 2 of a vehicle will now be described, which is implemented by the self-maintenance system 1 as claimed in any one of the preceding embodiments.

This method E comprises the steps consisting in:

-activating (E1) the

hydraulic machine

21, 23 for a determined period of time, and then

-deactivating (E2) the

hydraulic machine

21, 23 at the end of the time period.

This ensures that all (full flush) or part (partial flush) of the

hydraulic machines

21, 23 is flushed by moving the movable element to force the circulation of hydraulic fluid, the steps of activation (E1) and deactivation (E2) also being carried out independently of the command to activate and/or deactivate assistance. This enables regular self-maintenance of the hydraulic assistance device 2 even in cases where assistance is no longer needed, in particular in cases where it is seldom needed.

Advantageously, the step of deactivating (E2) may also be carried out by the safety module 14 when the vehicle reaches an excessively high speed, for the purpose of maintaining the safety of the

hydraulic machines

21, 23.

More advantageously, the alternation of the steps of activation (E1) and deactivation (E2) is repeated in succession at a given frequency, for example ten times in succession, in order to homogenize the flushing of the hydraulic means 21, 23. This alternation may be preset by the user or the manufacturer.

The duration of the step of starting (E1) may be preset by the manufacturer of the self-maintenance system 1. Alternatively, if the hydraulic machine 23 is coupled to the vehicle wheel 33, the hydraulic machine 23 is activated in a time period corresponding to one wheel revolution 23.

Advantageously, method E is carried out at a given rate, which is functional and/or temporal, for example once a month of operation of the vehicle. The term "functional rate" is understood to mean that method E is carried out at a rate that depends on the way in which hydraulic assistance device 2 is used, for example each time the vehicle travels a given distance, when the vehicle reaches a given rate of use or load, or when a pressure threshold is reached in hydraulic assistance circuit 27.

Advantageously, method E is implemented based on a given loss level of the fluid.

In the first embodiment of method E, referring to fig. 4a, no further assistance is required.

In this case, if the vehicle is in motion, the method is implemented for a given range of vehicle speeds, for example between 0 and 40km/h for the vehicle speed. After exceeding a certain level of vehicle speed, activating the hydraulic mechanism on the wheels may cause said mechanism to deteriorate.

Alternatively, method E may be implemented during vehicle stop, typically at a traffic light, preferably each time the vehicle is started. This has the advantage that it does not interfere with the driving of the vehicle. In this case, the flushing is only partial if the actuation movable element 211 is independent.

Preferably, the step of activating (E1) is carried out within a time period corresponding to a complete rotation of the

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 and also to circulate the hydraulic fluid more completely in the conduits. In particular, if one rotation of the

mechanism

21, 23 corresponds to one revolution of the wheel 33, this time period will correspond to one complete rotation of the wheel 33.

In a second embodiment of method E, still referring to fig. 4a, assistance is also required.

In this case, if the vehicle is in motion, method E is not implemented and the flushing is provided by the nominal operation of the hydraulic auxiliary device 2.

Alternatively, method E may be implemented during vehicle stop, typically at a traffic light, preferably each time the vehicle is started. In this case, the flushing is only partial if the actuation movable element 211 is independent.

In a third embodiment of method E, with reference to fig. 4b, the auxiliary devices comprise a reservoir 12, a feed pump (preferably of the counter-rotating type) 10 and a set of filters, for example a coarse filter 101 and a main filter 103, as previously described. In this embodiment, in addition to the flushing hydraulic means, a dredging of the

filters

101, 103 is advantageously obtained.

Method E then comprises the steps consisting in: starting (E1) the

hydraulic machines

21, 23 for a certain period of time, for example by activating the feed pump 10; and deactivating (E2) the

hydraulic machines

21, 23 at the end of the step of activating (E1) so as to circulate the hydraulic fluid through the

filters

101, 103 in two opposite circulation directions one after the other. As previously described, deactivation (E2) may be implemented by deactivating the charge pump 10 and returning hydraulic fluid to the reservoir 12 or by activating the charge pump 10 in the opposite direction if it is of the counter-rotating type. Furthermore, as previously described, the steps of activating (E1) and deactivating (2) are carried out independently of the command to activate and/or deactivate assistance.

Advantageously, method E can then be carried out without assistance. In this case, if the vehicle is in motion, the step of deactivating (E2) temporarily cuts off the assistance. Method E then takes action to perform the step of activating again (E3) after the step of deactivating (E2) in order to ensure the safety of the vehicle. Preferably, the step of deactivating (E2) is carried out within a time period corresponding to one rotation of the wheel 33 of the vehicle. In particular, if one rotation of the

mechanism

21, 23 corresponds to one revolution of the wheel 23, this time period will correspond to one complete rotation of the wheel 23.

This method E allows the parts of the hydraulic assistance device 2 to be moved periodically (even without using it), which prevents wear or corrosion located at the contact points of the immobile parts, avoids the presence of immobile hydraulic fluid that may be subjected to repeated thermal cycles, and prevents the settling or polymerization of the hydraulic fluid. Furthermore, it allows to unclog the

filters

101, 103. By its effect it is possible to keep the hydraulic auxiliary device 2 working for a longer time between two intervals of discharge of hydraulic fluid. It also makes it possible to space the emission dates apart and therefore to reduce the operating costs of the system.

The self-maintenance system 1 can be used to advantage with any hydraulically assisted towing device, in particular to convert a 4x2 vehicle into a 4x4 vehicle, or the supporting wheels of an auxiliary vehicle such as the driving wheels of a truck, the supporting axles of a truck or trailer, the supporting axles of a construction site or agricultural machine, the low-speed temporary hydraulic transmission of a service or work vehicle (named under the name "crawling driving") or the supporting axles of a road/rail convertible vehicle or machine.

Claims

1. A self-maintenance method (E) of a hydraulic auxiliary device (2) of a vehicle, said device (2) comprising:

a hydraulic mechanism (21, 23),

a reservoir (12),

a filter (101, 103),

a feed pump (10) comprising:

a fluid inlet (100) disposed in fluid communication with the reservoir (12), an

A fluid outlet (102) arranged in fluid communication with the hydraulic machine (21, 23),

the device (2) is configured to alternately circulate the hydraulic fluid:

-from the reservoir (12) to the hydraulic machine (21, 23) by activating the feed pump (10) to activate the hydraulic machine (21, 23) and thus enable hydraulic assistance, and

from the hydraulic machine (21, 23) to the reservoir (12) to deactivate the hydraulic machine (21, 23) and thus release the hydraulic assistance,

the enabling and disabling of assistance is controllable on command,

the method (E) comprises the steps consisting of:

-activating (E1) the hydraulic machine (23) for a determined period of time, and

deactivating (E2) the hydraulic machine (23) at the end of the step of activating (E1),

so as to circulate hydraulic fluid through said filters (101, 103) in two opposite circulation directions in succession,

the steps of activation (E1) and deactivation (E2) are carried out independently of the command to enable and/or disable assistance.

2. A method (E) as claimed in claim 1, wherein said method (E) is implemented for a given range of vehicle speeds, such as vehicle speeds between 0 and 40 km/h.

3. The method (E) according to any one of claims 1 or 2, wherein the alternation of the steps of activation (E1) and deactivation (E2) is repeated successively, for example ten times in succession, at a given frequency.

4. A method (E) as claimed in any one of claims 1 to 3, wherein the assistance is enabled, the method (E) then being carried out alternately:

while the vehicle is in motion, then partially deactivating (E2) or

In a state where the vehicle is stopped.

5. A method (E) as claimed in any one of claims 1 to 3, wherein said assistance is deactivated, said method being carried out alternately with said vehicle in a state of movement or with said vehicle in a state of stop.

6. Method (E) according to any one of claims 1 to 5, wherein said method (E) is carried out each time said vehicle is activated.

7. Method (E) according to any one of claims 1 to 6, wherein said method (E) is carried out at a given rate which is functional, for example each time the vehicle has travelled a given distance, and/or

Temporal, e.g. once a month of operation of the vehicle.

8. A method (E) according to any one of claims 1 to 7, wherein said method (E) is carried out starting from a given loss level of hydraulic fluid.

9. A self-maintenance system (1) of a hydraulic auxiliary device (2) of a vehicle, said device (2) comprising:

a hydraulic mechanism (21, 23),

a reservoir (12),

a filter (101, 103),

-a feed pump (10), the feed pump (10) comprising:

a fluid inlet (100) disposed in fluid communication with the reservoir (12), an

the device (2) is configured to alternately circulate hydraulic fluid:

from the hydraulic machine (21, 23) to the reservoir (12) to deactivate the hydraulic machine (21, 23) and thus to release the hydraulic assistance, the activation and release of assistance being controllable on command,

the system (2) comprises a control module (11) configured to implement the method (E) according to any one of claims 1 to 8.

10. The self-maintenance system (1) as claimed in claim 9, comprising: a coarse filter (101) arranged between the reservoir (12) and a fluid inlet (100) of the feed pump (10), and a main filter (103) arranged between a fluid outlet (102) of the feed pump (10) and the hydraulic mechanism (230), the coarse filter (101) and the main filter (103) being configured to keep the hydraulic auxiliary device (2) free from ingestion of particulate contaminants.

11. The self-maintenance system (1) as claimed in claim 10, comprising: a bypass valve (107) and a secondary filter (105) arranged between the main filter (103) and a fluid outlet (102) of the feed pump (10), the secondary filter (105) being configured to discharge impurities of the main filter (103) during a return flow of hydraulic fluid from the hydraulic machine (21, 23).

12. The self-maintenance system (1) of any one of claims 9 to 11, further comprising: a vacuum valve (104) commanded by the control module (11) and configured to facilitate a return flow of hydraulic fluid from the hydraulic machine (21, 23).

13. Vehicle comprising a self-maintenance system (1) according to any one of claims 9 to 12 and a hydraulic auxiliary device (2).