Locking device for an indirectly electro-hydraulic controlled hydraulic cylinder

Abstract

The invention relates to an electro-hydraulic controlled locking device for a cylinder (1) comprising a safety module (5) having: - two inlets (12, 13) for connection to the hydraulic circuit and at least one outlet (8) for connection to an orifice of a chamber (10, 11) of the cylinder (1), - a hydraulic passage (16, 17) between a first of these two inlets (12, 13) and the at least one outlet (8), designed so that the chamber (10, 11) can only be filled and emptied through this hydraulic passage (16, 17), and - two mechanical sealing devices mounted in series in the hydraulic passage (16, 17) to allow a watertight lock of the chamber (10, 11), characterized in that it comprises: - a control module (6) connected to the two inlets (12, 13) of the safety module (5), and - a flow selector and a solenoid valve (42) whose activation and deactivation allows the control module (6) to be powered or not.Figure for the abridged version: Fig 1.

Description

Title of the invention: Locking device for an indirectly electro-hydraulic controlled hydraulic cylinder. Technical field

[0001] The present invention relates to the technical field of so-called "safety" cylinders. It relates more particularly to a safety and control device for the movement and holding in position of the rod of a single or double-acting hydraulic cylinder.

[0002] The invention also relates to a single or double-acting hydraulic cylinder equipped with such a safety and control device.

[0003] The invention also relates to a hydraulic circuit containing a set of cylinders equipped with such safety devices and allowing their supply and control in a particularly advantageous manner.

[0004] This invention can advantageously be applied to car carriers or other equipment supporting loads by means of single- or double-acting hydraulic cylinders. More generally, it can be applied to any device comprising several hydraulic cylinders that one wishes to supply with hydraulic fluid centrally, while controlling them independently of each other, in a safe manner. Previous technique

[0005] Single- or double-acting hydraulic cylinders are widely used for lifting and holding loads. They are frequently employed in transportation, industry, construction, and in all fields where it is necessary to perform lifting, lowering, and / or holding movements of a load involving significant forces. This is the case, for example, in car carriers, which typically have several movable platforms designed to receive the cars to be transported, and whose position and height are adjustable by means of various actuators, most often double-acting hydraulic cylinders.

[0006] For safety reasons, it is absolutely essential to ensure that the cylinder rod remains in position when its movement is not commanded, and especially when it is supporting a load. Indeed, to guarantee the safety of operators and any equipment that may be below, the height of the load must not change over time without deliberate action by the operator. Therefore, in the absence of a command, the rod of a hydraulic cylinder must be able to be immobilized in both its retracted and extended positions, whether or not it is supporting a load.

[0007] To mitigate a potential risk of failure, prior art has developed safety devices associated with these lifting cylinders, consisting of a hydraulic isolation block, examples of which have been described in patents EP 0935715 or EP 3436706.

[0008] This known safety device is an isolation block, through which one of the cylinder chambers is supplied, comprising two sealing devices of the same type: a primary ball check valve, backed up by a secondary, so-called "safety" ball or conical needle check valve, both of which are mechanical check valves with a shutter. These two successive check valves are arranged in series, each at one of the entrances of an airlock.

[0009] These known devices have several advantages. First, they are safer due to the use of two successive check valves arranged in series. In addition, they allow automatic locking without operator intervention and in any position of the cylinder rod.

[0010] However, it is impossible to pressurize the device without causing a movement of the cylinder rod (retracting or extending depending on the supply side), because the arrival of oil at one of the device's inlets automatically causes the successive opening of the two relevant check valves.

[0011] Furthermore, when the installation includes several cylinders equipped with such safety devices, it is necessary to install a separate hydraulic distributor for each of the safety devices if it is desired to be able to control the movements of the cylinders independently of each other.

[0012] When the cylinders operate in pairs, as is the case for example in the preferred application of a car carrier vehicle, it is necessary to add in the hydraulic circuit components ensuring the synchronization of the movements of the two cylinders, for each of the pairs of cylinders.

[0013] When the installation includes a large number of cylinders (for example, around thirty on a typical car transporter consisting of a tractor and a double-decker trailer), the hydraulic circuit becomes complex and includes numerous hydraulic components (distributors and flow dividers) that must be provided for each cylinder or pair of cylinders. Therefore, if the cylinders are to be controlled in pairs, a specific divider is required for each pair of cylinders, resulting in dense and complex hydraulic connections.

[0014] Finally, direct electrical control of the hydraulic cylinders is not possible, which makes it impossible to automate certain functions of the convoys.

[0015] Known is also patent application GB 634 293 A, which describes a circuit comprising a mechanical check valve and an electro-hydraulic device with two shutters whose opening and closing in both directions are electrically controlled. However, the check valve and the electro-hydraulic device are not They are not arranged in series, but in parallel. Therefore, safety is not optimal and this system does not address the technical problem.

[0016] We also know from document EP 4 077 950, which describes a safety block comprising, in series, a first level of sealing achieved by a ball valve and an electrically actuated valve, allowing the selection of specific cylinders to be controlled. However, it is necessary to use two solenoid valves per cylinder, which implies a significant cost. Furthermore, when a function is activated, the isolation of the unused cylinders relies on only one level of sealing, namely the electrically actuated valve. The risk of unintended activation of unselected cylinders is then greater than in the case of a double seal.Furthermore, the electrical coils used to control the safety valve are quite bulky because the valve's opening direction opposes the supply pressure to a chamber of the cylinder as well as the spring force of the ball valve, requiring significant force to keep the electrically operated valve open. It should also be noted that the design of electrically operated valves demands tight machining tolerances, particularly regarding the coaxial alignment between the valve stem and the axis passing through the center of its seat. The risk of leaks is therefore high, which can cause unintended movement of the cylinders when not under load. Presentation of the invention

[0017] One object of the invention is to propose a new electro-hydraulic controlled locking device to overcome the disadvantages of these previous systems, while retaining their advantages.

[0018] Another object of the invention aims to provide hydraulic cylinders equipped with these new locking and control devices and whose production is technically simple and economical.

[0019] Another object of the invention aims to provide scalable hydraulic circuits or systems in which it is possible to add new functions in a simple and reliable way.

[0020] The aims and objects assigned to the invention are achieved by means of an electro-hydraulically controlled locking device for a hydraulic lifting cylinder comprising a rod, allowing the rod to be held in position by means of locking the hydraulic fluid circulation, the device comprising a safety module intended to be mounted in a hydraulic circuit that supplies fluid to the cylinder, the safety module comprising: - two inlets intended for communication with the hydraulic circuit and at least one each output is intended to be connected to a chamber of the cylinder, - at least one hydraulic passage between at least one of these two inlets and a corresponding outlet, designed so that the cylinder chamber can only be filled and emptied through this hydraulic passage, - at least one mechanical shut-off device mounted in the hydraulic passage to allow a watertight seal of the chamber, said shut-off device being actuated by the direct force of the fluid entering the hydraulic passage through the first of these two inlets to allow the filling of said chamber and which is also actuated by the direct force, or via the action of a control part, of the fluid then entering through the second of these two inlets to allow the emptying of said chamber, characterized in that it comprises: - an electro-hydraulic control module to control the different operating states corresponding to the extension, retraction, holding in position and non-tensioning of the rod, connected to the two inputs of the safety module and to the hydraulic circuit, said control module comprising two sliding pilot members delimiting between them a pilot compartment and each associated with a pilot valve, a first control compartment connected to the hydraulic passage, a second control compartment allowing the supply of hydraulic fluid under high pressure to the safety module and moving the control part in order to empty the chamber, the pilot valves being actuated in their open position by the pilot members allowing the supply of fluid under high pressure to one of the inputs, - a solenoid valve whose activation and deactivation allows the control module to be supplied with high-pressure hydraulic fluid or not, - a flow selector to connect the pilot compartment to one of the control compartments when the latter is supplied with hydraulic fluid under high pressure.

[0021] According to one embodiment, the mechanical shut-off device comprises a primary valve and a secondary valve mounted in series, the control piece being located near the primary valve, this control piece moving towards the primary valve under the pressure of the hydraulic fluid entering through one of the two inlets and causing the opening of said primary valve.

[0022] According to an example embodiment, the security module comprises: - an independent sliding rod, arranged longitudinally and interposed between the primary and secondary valve shutters but not linked to them, and capable of sliding towards each of the shutters so as to press by one of its ends against the shutter located opposite, - guiding elements such as bores and guide supports to guide the neck smoothing of the sliding rod, - the length of the sliding rod being short enough so as not to be in simultaneous contact with the two obturators resting on their respective seats when the two primary and secondary valves are closed, but long enough so that the opening command of the primary valve causes, by the movement of its obturator which pushes the corresponding end of the sliding rod, the sliding of the sliding rod causing the opening of the secondary valve whose obturator is pushed out of its seat by the other end of the sliding rod.

[0023] According to one embodiment, the control module comprises two control outputs each connected to an input of the safety module and two control inputs connected to the hydraulic circuit, one of which leads to the first control compartment and the other leads to the second control compartment, the activation of the solenoid valve and a corresponding active position of the flow selector allowing the pilot compartment and one of the control compartments to be supplied with fluid under high pressure, the other of the control compartments being in low-pressure fluidic communication with a reservoir, the first and second control compartments being able to be simultaneously in low-pressure fluidic communication with the reservoir.

[0024] By way of example, the control module includes: - a bore in which the two sliding piloting elements are arranged relative to each other in a substantially central area, - a high-pressure fluid supply orifice opening into the bore at the interface of the control elements, which are in contact or close to each other when not under load, - the piloting compartment, corresponding to a space located between the two piloting instruments, the volume of which depends on the variable spacing of said piloting instruments, - the first control compartment being delimited by one end of the bore and by one of the piloting devices, one of whose control outputs communicates with the first input of the safety module via the pilot valve, - the second control compartment being delimited by the other end of the bore and by the other pilot element, a second control output of which communicates with the second inlet of the safety module via a check valve, - said pilot valves being mounted in opposition and closed when the pilot elements are not activated by the high-pressure fluid, thus preventing any circulation of fluid through the control module to the safety module, and - the said pilot valves being opened by the action of the pilot devices set apart mutually by filling the cockpit compartment.

[0025] According to one embodiment, the safety and control modules are each integrated into a drilled block made in one piece.

[0026] According to one embodiment, the electro-hydraulically controlled locking device is intended for a double-acting hydraulic cylinder comprising a large chamber and a small chamber, the safety module comprising: - two inputs intended to be connected to the control module, - two outlets intended to be connected, the first to an orifice of the large chamber of the cylinder and the second to an orifice of the small chamber of the cylinder, - two hydraulic passages, the first extending between the first of these two inlets and the outlet, and the second extending between the second of these two inlets and the outlet, said hydraulic passages being designed so that the large chamber and the small chamber can only be filled and emptied through one of these two hydraulic passages, and - a primary valve and a secondary valve placed in series in each of these two hydraulic passages so that the large chamber and the small chamber can be locked in a watertight manner by a primary valve and a secondary valve in series.

[0027] According to another embodiment, the electro-hydraulic controlled locking device is intended for a single-acting hydraulic cylinder comprising a large chamber and a small chamber, characterized in that the safety module comprises: - two inlets intended to be connected to the control module, - an outlet intended to be connected to an orifice of the large chamber of the cylinder, - a hydraulic passage extending between the first of these two inlets and the outlet, said hydraulic passage being arranged so that the large chamber can only be filled and emptied through the hydraulic passage, and - the primary valve and the secondary valve placed in series in the hydraulic passage so that the large chamber can be locked hermetically by the primary and secondary valves.

[0028] The objects assigned to the invention are also reached using a hydraulic cylinder equipped with an electro-hydraulic controlled locking device.

[0029] The objects assigned to the invention are also achieved by means of a hydraulic circuit comprising several hydraulic cylinders, each equipped with an electro-hydraulically controlled locking device and comprising a rod and at least one chamber supplied through a hydraulic passage of the safety module, a hydraulic fluid reservoir, a distribution block, a set of pipes connecting the reservoir to the cylinders, via the distribution block, in order to fill and / or empty the chamber(s) of the cylinders, said hydraulic circuit comprising a pumping device allowing the hydraulic fluid to circulate in the pipes, the distribution block includes a single three-position proportional hydraulic distributor comprising a neutral position interrupting the circulation of the hydraulic fluid to the receivers of the hydraulic circuit, a position connecting the pumping device and the reservoir with the control module of at least one cylinder to cause the extension of the cylinder rod and a position connecting the pumping device and the reservoir with the control module of at least one cylinder to cause the retraction of the cylinder rod, the control module of each of the electro-hydraulic locking and control devices being able to be operated independently of the other devices.

[0030] According to one embodiment of the hydraulic circuit, the cylinders are arranged in several pairs of two cylinders operating in a synchronized manner and in that the hydraulic circuit further comprises a single flow divider, which ensures the synchronization of the movements of each pair of cylinders, each pair of cylinders being able to be controlled independently by means of the corresponding electro-hydraulic controlled locking devices.

[0031] The locking and control device according to the invention has the remarkable advantage that it requires only a single proportional distributor to distribute the entire flow of hydraulic fluid.

[0032] In addition, a single flow divider is used to supply two lines through the whole of a convoy and to allow synchronized piloting of each pair of cylinders.

[0033] The locking and control device also makes it possible to drastically limit the risk of unintentional operation of the cylinders not used by the user.

[0034] It should be noted that only one solenoid valve is required to control a cylinder, which is a very economical solution.

[0035] The invention also makes it possible to design a new hydraulic architecture that minimizes pressure losses. This results in a reduction in fuel or energy consumption and an increase in the range of trains equipped with such a hydraulic architecture. Brief description of the figures

[0036] Other features and advantages of the invention will become apparent from the following detailed description, which is made with reference to the accompanying drawings, in which:

[0037] [Fig. 1] is a general perspective view of an example of a double-acting cylinder associated with an electro-hydraulic controlled locking device according to the invention,

[0038] [Fig.2] is a longitudinal and vertical cross-sectional view of an example embodiment of the electro-hydraulically controlled locking device of the cylinder of [Fig. 1], in a first operating state corresponding to the extension of the rod of said cylinder,

[0039] [Fig. 2a] is an enlargement of [Fig. 2], with a schematic representation of the jack,

[0040] [Fig.2b] is a partial enlargement of [Fig.2a],

[0041] [Fig.2c] is an illustration of the electro-hydraulic controlled locking device draulique of [Fig.2a], with a representation of the directions of hydraulic fluid flow during the extension of the rod,

[0042] [Fig.3] is a hydraulic diagram of the electrically controlled locking device hydraulics of the cylinder of [Fig.2], in its first operating state,

[0043] [Fig.4] is a longitudinal and vertical cross-sectional view of an example embodiment of the electro-hydraulically controlled locking device for a cylinder, in a second operating state corresponding to holding the rod in position without hydraulic pressure in the hydraulic circuit,

[0044] [Fig.5] is a hydraulic diagram of the electrically controlled locking device hydraulics of the cylinder of [Fig.4] in its second operating state,

[0045] [Fig.6] is a longitudinal and vertical cross-sectional view of an example embodiment of the electro-hydraulically controlled locking device of the cylinder of [Fig. 1], in a third operating state corresponding to the retraction of the rod,

[0046] [Fig.6a] is an illustration of the electro-hydraulic controlled locking device draulique of the cylinder in [Fig.6], with a representation of the directions of hydraulic fluid flow during the retraction of the cylinder rod,

[0047] [Fig.7] is a hydraulic diagram of the electrically controlled locking device hydraulics of the cylinder [Fig. 6], during the retraction of the rod,

[0048] [Fig.7a] is a hydraulic diagram of another example of an embodiment of a device electro-hydraulic locking mechanism adapted to a single-acting hydraulic cylinder, during rod retraction,

[0049] [Fig.8] is a hydraulic diagram of the electrically controlled locking device hydraulics of the cylinder of [Fig. 1], in a fourth operating state corresponding to holding the rod with pressure in the hydraulic circuit, and

[0050] [Fig.9] is a hydraulic diagram of another example of an embodiment of the device electro-hydraulic controlled locking of the cylinder of the [Fig.l]. Detailed description of the invention

[0051] Structurally and functionally identical elements present on several distinct figures are assigned the same numeric or alphanumeric reference.

[0052] Fig. 1 is a general perspective view of an example embodiment of a jack 1 double-acting, comprising a barrel 2 and a rod 3. The cylinder 1 is equipped with an electro-hydraulic controlled locking device 4 comprising a safety module 5, an electro-hydraulic control module 6 and a poppet valve 7.

[0053] To avoid any risk of leakage, the safety module 5 is preferably flanged or integrated into the barrel 2 of the cylinder 1. It can also be attached to the latter, and for example screwed to the barrel 2. Advantageously, the safety module 5 and the control module 6 are advantageously each integrated into a part of a drilled block made in one piece fixed to the barrel 2.

[0054] The locking and control device 4 is also connected to the barrel 2 via conduits 8 and 9, enabling fluidic communication with the chambers of the cylinder 1.

[0055] Figure 2 is a longitudinal and vertical cross-sectional view of an example embodiment of the locking and control device 4 and the cylinder 1 in a first operating state. In this first operating state, the cylinder 1 is actuated to generate an extension of the rod 3 of the barrel 2.

[0056] The rod 3 has, in a known manner, at its end located inside the barrel 2, a piston 3a separating the interior space of the barrel 2 and delimiting a large chamber 10 and a small chamber 11. The large chamber 10 and the small chamber 11 communicate respectively with the conduits 8 and 9 via respective orifices 10a and 1ia, provided in the barrel 2.

[0057] The safety module 5 includes two inlets 12 and 13 intended to be connected to the hydraulic circuit and two outlets 14 and 15 intended to be connected respectively to the ports 10a and 1la of the drum 2 via the pipes 8 and 9.

[0058] [Fig.2a] is an enlargement of [Fig.2], with a schematic representation of the cylinder 1 and [Fig.2b] is a partial enlargement of [Fig.2a].

[0059] The safety module 5 also includes and delimits a first hydraulic passage 16 extending between the inlet 12 and the orifice 10a and a second hydraulic passage 17 extending between the inlet 13 and the orifice 11a. These two hydraulic passages 16 and 17 are designed so that the large chamber 10 is filled and emptied only through one 16 of these hydraulic passages 16, 17 and that the small chamber 11 is filled and emptied only through the other 17 of these hydraulic passages 16, 17.

[0060] The safety module 5 includes at least one mechanical shut-off device mounted in each of the hydraulic passages 16 and 17 to allow a watertight locking of the respective chamber 10 and 11 by said corresponding shut-off device.

[0061] Figure 2b is a partial enlargement of Figure 2. Two mechanical shut-off devices are mounted in series and advantageously comprise a primary check valve 18 with a primary obturator 18a and a secondary check valve 19 with ob- Secondary obturator 19a. Obturators 18a and 19a are advantageously balls.

[0062] For the sake of simplification, the secondary check valve 19 with secondary shutter 19a, located closest to the corresponding chamber of the cylinder 1, will be called "secondary valve 19" and the primary check valve 18 with shutter 18a, located on the side of the hydraulic supply circuit, i.e. on the side furthest from the chamber of the cylinder 1, will be called "primary valve 18".

[0063] Fig. 2c is an illustration of the safety module of a locking and control device according to the invention of Fig. 2, with a representation of the directions of flow of the hydraulic fluid when the rod 3 of the cylinder 1 is extended as indicated by an arrow in Fig. 2.

[0064] The primary valve 18 and secondary valve 19 are open under the direct pressure of the fluid entering the hydraulic passage 16 through the inlet 12 to allow the filling of the large chamber 10. The shut-off devices 18 and 19, located in the hydraulic passage 17, are also open, but via the action of a control piece 20. This situation results from the action of the hydraulic fluid entering the safety module 5 through the inlet 12 and passing through the hydraulic passage 16, thus generating the movement of the control piece 20, which opens the primary shut-off valves 18a and 19a in the hydraulic passage 17. This allows the emptying of the large chamber 11 through the hydraulic passage 17, the inlet 13, and the electro-hydraulic control module 6.

[0065] The control piece 20 is advantageously located near the primary valve 18 and moves towards the primary obturator 18a under the pressure of the hydraulic fluid entering through the inlet 12 and thus pushes to cause the obturator 18a to be lifted from its seat 18b.

[0066] The safety module 5 also includes an independent sliding rod 22, arranged longitudinally and interposed between the obturators 18a and 19a of the primary valves 18 and secondary valves 19, but not linked to the latter and capable of sliding towards each of the obturators 18a, 19a so as to come to press by one of its ends against the primary obturator 18a, secondary obturator 19a located opposite said end.

[0067] Advantageously, guide elements are provided, such as a guide support 23 sliding in a bore 23a, to guide the sliding of said sliding rod 22, which is inserted coaxially and fixedly in said guide support 23.

[0068] The length of the sliding rod 22 is sufficiently short so that it cannot be in simultaneous contact with the two obturators 18a and 19a resting on their respective seats 18b, 19b when the two primary valves 18 and secondary valves 19 are closed. Furthermore, the length of the sliding rod 22 is sufficiently long to that the opening command of the primary valve 18 causes, by the movement of its obturator 18a which pushes the corresponding end of the sliding rod 22, the sliding rod 22 towards the secondary valve 19, thus causing the opening of the secondary valve 19 whose obturator 19a is pushed out of its seat 19b by the other end of the sliding rod 22.

[0069] In the examples shown, the guide support 23 is substantially cylindrical and has a diameter advantageously chosen to allow guided sliding of the sliding rod assembly 22 - guide support 23 in the bore 23a, which is also provided to house the shutter 18a and a return spring 25a for said shutter 18a. The shutter 19a is advantageously associated with another additional return spring 25b.

[0070] In order to allow the flow of hydraulic fluid, despite the presence of the sliding rod 22 and its guide support 23 in the bore 23a, one or more longitudinal grooves 24 can advantageously be provided in the walls of the bore 23a or in the guide support 23. An example of such longitudinal grooves is shown for example in [Fig.2a].

[0071] The sliding rod 22 can thus slide freely from one side to the other of the bore 23a without hindering the flow of the hydraulic fluid, and can thus move in the direction of each of the obturators 18a and 19a.

[0072] However, by design, the sliding rod 22 is too short to be in contact simultaneously with the two obturators 18a and 19a when the latter are in contact with their respective seats 18b and 19b, in the closed position of the two primary valves 18 and secondary valves 19. There is therefore a longitudinal play between the rod 22 and the two obturators 18a and 19a in contact with their respective seats 18b and 19b.

[0073] According to one embodiment, the primary valve 18 and the secondary valve 19 are preferably made without a common mode, that is to say they are different from each other and their parts playing a role for sealing are not identical, in order to strengthen safety.

[0074] For example, two balls 16 of different diameters and / or different materials can be used for the obturators 18a, 19a. Similarly, the seats 18b, 19b can be made of different materials, for example, one of steel and the other of bronze. It is also possible to fit one directly into the body of a part of the safety module 5, while the other is located on a separate, separate, attached part. The return springs 24 used can also be different from each other and advantageously have different stiffnesses.

[0075] The control part 20 is therefore capable of causing the primary valve 18 to open. This control part 20 is preferably located near the primary valve 18, on the opposite side of the secondary valve 20. Preferably, it is a mechanical part which moves towards the primary valve 18, in order to move the obturator 18a to cause the primary valve 18 to open.

[0076] The control piece 20 may advantageously include for this purpose a protruding lateral finger 26, which extends towards the primary valve 18 and whose free end 27 is capable of engaging through the seat 18b of this valve, in order to push the obturator 18a out of its seat 18b.

[0077] As shown, the control piece 20 can advantageously be a sliding shuttle serving as a boundary between the two separate hydraulic circuits which independently supply the large chamber 10 and the small chamber 11. The control piece 20 thus has opposing lateral faces 28 and 29, thus locally delimiting these two hydraulic circuits.

[0078] A perimeter seal 30 mounted on this shuttle serves to complete the barrier formed by the shuttle and ensure a seal between the two hydraulic circuits, while allowing longitudinal sliding of the control part 20. This perimeter seal 30 thus ensures that all the hydraulic fluid sent ends up in the corresponding chamber of the cylinder 1 and causes the rod 3 of the cylinder 1 to retract or extend to the expected length. This is particularly important when the cylinder 1 is part of a set of several cylinders 1 that must act symmetrically and synchronously.

[0079] With such an embodiment, the movement of the control part 20 towards the primary valve 18 is caused automatically by the pressure of the hydraulic fluid, as will be explained below, when the operator supplies the cylinder(s) 1 of the hydraulic function to be controlled.

[0080] In the absence of operator command, the control part 20 is preferentially kept away from the primary valve 18 by a return spring 31.

[0081] In the preferred embodiment shown, the shutter devices located on either side of the control part 20 are further twinned, that is to say that their operation is linked to each other and is not independent.

[0082] For this purpose, the safety module 5 comprises only one control piece 20, capable of alternately causing the opening of the primary valve 18 of each of the hydraulic passages 16 and 17.

[0083] This unique control piece 20 is preferably a central sliding shuttle which has on each of its lateral faces 28 and 29 a projecting lateral finger 26, extending towards one of the obturators 18a and 19a. Thus, when this control piece 20 moves towards one of the primary valves 18, the free end 27 of the projecting lateral finger 26 located opposite, pushes the obturator 18a of the primary valve 18 concerned and thus causes it to open.

[0084] As before, the lateral fingers 26 of the control piece 20 are designed to be too short to simultaneously reach the two obturators 18a of the opposing primary valves 18. This ensures longitudinal play, and even in the event of incorrect positioning, the control piece 20 cannot cause the simultaneous opening of the two primary valves 18.

[0085] Advantageously, the control piece 20 can be held in a substantially central position by two opposing return springs 31, each acting on one of the lateral faces 28, 29 of the single control piece 20 to return it to this substantially central position. Similarly, when the single control piece 20 is in this central position, its lateral fingers 26 are too short by design to reach the opposite shutters 18a.

[0086] The electro-hydraulic control module 6 is illustrated in particular in figures 2a, 2c and 3. [Fig.3] is a hydraulic diagram of the locking and control device and of the double-acting cylinder of [Fig.2], in its first operating state corresponding to the extension of the rod 3.

[0087] The electro-hydraulic control module 6 is connected to the hydraulic circuit via input ports opening onto control compartments 39 and 40 and in fluidic communication with the two inlets 12 and 13 of the safety module 5. The control module 6 comprises a first pilot member 35 and a second pilot member 36, movable in a bore 6a formed in a body forming the drilled block integrating the safety module 5 and the control module 6. The pilot members 35 and 36 are each associated with a respective pilot valve 37 and 38, of the type check valves.

[0088] The first pilot member 35 partially delimits, within bore 6a, the first control compartment 39 connected to the hydraulic circuit, and the second pilot member 36 partially delimits, within bore 6a, the second control compartment 40 connected to the hydraulic circuit. The first control compartment 39 has a control output 39a connected to the inlet 12 and consequently to the hydraulic passage 16 of the safety module 5, via the pilot valve 37. The second control compartment 40 has a control output 40a connected to the inlet 13 and consequently to the hydraulic passage 17 of the safety module 5, via the pilot valve 38.

[0089] The first piloting member 35 and the second piloting member 36 have respectively a face 35a and a face 36a opposite each other, which delimit between them a piloting compartment 41 of variable volume and connected to the hydraulic circuit.

[0090] The bore 6a includes, by extension, a high-pressure fluid supply orifice opening into the pilot compartment 4L. The pilot components 35 The pilot valves 35 and 36 are mounted slidingly and sealed within the bore 6a and are in contact or close to each other when not subjected to the high-pressure fluid. The surface area of ​​faces 35a and 36a is advantageously larger than the surface area of ​​the opposing faces 35b and 36b of the respective pilot valves 35 and 36. This ensures that the pilot valves 37 and 38 open when the pilot compartment 41 and one of the pilot valves 37 or 38 are simultaneously subjected to the high-pressure hydraulic fluid. The force exerted on one of the opposing faces 35b or 36b will therefore always be less than that exerted on faces 35 and 36.

[0091] The locking and control device also includes a solenoid valve 42 associated with the control module 6, the activation and deactivation of which allows the control module 6 to be supplied or not with hydraulic fluid and thus to control the different operating states of said control module 6. The operating states correspond to the extension, retraction, holding in position and non-application of the rod 3 of the cylinder 1.

[0092] Activation of the solenoid valve 42 allows the pilot compartment 41 and one of the control compartments 39 and 40 to be supplied with high-pressure hydraulic fluid simultaneously, thus enabling fluid communication between the locking module 5 and the hydraulic circuit via said control compartments 39 and 40.

[0093] The electro-hydraulically controlled locking device 4 also includes a flow selector 43 for connecting the pilot compartment 41 to one of the control compartments 39 or 40 when the latter is supplied with hydraulic fluid under high pressure.

[0094] Activation of the solenoid valve 42, selection of a position of a proportional distributor 45 and a corresponding active position of the flow selector 43 allow the pilot compartment 41 and one of the control compartments 39 and evacuation compartments 40 to be supplied with high-pressure fluid, the other of the control compartments 39 and 40 being in low-pressure fluidic communication with a fluid reservoir 46. In addition, the first and second control compartments 39 and 40 are simultaneously in low-pressure fluidic communication with a fluid reservoir 46, when the cylinder 1 is in an operating state corresponding to holding in position or not being stressed of the rod 3.

[0095] Depending on the operating state of the cylinder 1, the pilot compartment 41 has a volume dependent on the spacing of said first and second piloting elements 35 and 36.

[0096] The pilot valves 37 and 38 are mounted in opposition and are closed when the corresponding pilot members 35 and 36 are not displaced in response to the filling of the pilot compartment 41 by the high-pressure fluid, preventing thus any circulation of fluid through the control module 6 to the safety module 5. The pilot valves 37 and 38 have respective shutters which are lifted from their seats simultaneously by the pilot members 35 and 36 mutually separated by the filling of the pilot compartment 41.

[0097] Thus, in a first operating state illustrated in [Fig. 3], the first control compartment 39 is supplied with fluid under high pressure provided by a pump P associated with a motor M through a position of the proportional distributor 45 and a flow divider 47. The control of the solenoid valve 42 induces the filling of the pilot compartment 41 and consequently the simultaneous opening of the pilot valves 37 and 38, thus allowing the hydraulic passage 16 of the safety module 5 to be supplied. The filling of the pilot compartment 41 and consequently the opening of the pilot valve 38 then simultaneously allows the hydraulic passage 17 of the safety module 5 to be connected to the reservoir 46 via the second control compartment 40, a return line 48 and the proportional distributor 45.The flow selector 43 allows this low-pressure return line 48 to be isolated from the portion of the hydraulic circuit in which the high-pressure fluid circulates. In an example of the device's operation, the high-pressure fluid is at a pressure of approximately 250 bar and the low pressure is at atmospheric pressure.

[0098] By way of example, the flow divider 47 advantageously comprises two lines 47a and 47b, each communicating with a cylinder 1, thus ensuring the synchronization of a pair of cylinders 1 or a succession of pairs of cylinders 1. These supply lines 47a and 47b advantageously have a large diameter and extend almost straight along the vehicle so as to deliver the hydraulic fluid as close as possible to the hydraulic functions to be supplied. Furthermore, this advantageous arrangement drastically limits singular and regular pressure losses in the hydraulic circuit by reducing the number of obstacles such as bends or connections of hoses and tubes, as well as by decreasing their lengths.

[0099] Figure [Fig. 2c] illustrates, with arrows, the schematic operating state shown in the diagram. [Fig.3], the circulation of hydraulic fluid supplying the large chamber 10 via the line 8 and the drainage of the small chamber 11 via the line 9.

[0100] Figure 4 is a longitudinal and vertical cross-sectional view of an example embodiment of the electro-hydraulic controlled locking device 4 and a double-acting cylinder 1 in a second operating state, corresponding to holding the rod 3 in position.

[0101] In this second operating state, neither the pilot compartment 41 nor any of the control compartments 39 and 40 are supplied with a fluid under High pressure. The pilot members 35 and 36 are in near-mutual contact, thus closing the pilot valves 37 and 38. The primary valve 18 and secondary valve 19 in each hydraulic passage 16 and 17 are closed by the return springs 24. The hydraulic fluid contained in the large chamber 10 or the small chamber 11 cannot escape because it also closes the primary valve 18 and / or secondary valve 19. The stem 3 is therefore locked.

[0102] Figure 5 is a hydraulic diagram of the electro-hydraulically controlled locking device 4 in this second operating state. This state corresponds to the neutral position of the proportional distributor 45, which allows all fluid lines to be connected to the reservoir 46 before the solenoid valve 42 is deactivated. Advantageously, this deactivation occurs after a delay relative to the proportional distributor 45 being placed in its neutral position. This allows the pilot compartment 41 to be drained before the solenoid valve 42 is deactivated, which would otherwise prevent the draining of said pilot compartment 4L. This also allows the decompression of all the lines 47a, 47b of the hydraulic circuit, as well as the lines supplying the control compartments 39 and 40.

[0103] The first and second control compartments 39 and 40 are then also in low-pressure communication with the reservoir 46. Furthermore, the control part 20 is not subjected to the high-pressure fluid, and the return springs 31 return it to a central position away from each of the primary valves 18. The flow selector 43 then remains in a neutral position since it is not pushed into an isolation position by a high-pressure fluid. The entire hydraulic circuit is no longer subjected to high hydraulic fluid pressure, and all the valves close, thus locking the cylinder 1 in position.

[0104] The [Fig.6] is a longitudinal and vertical cross-sectional view of an example embodiment of the electro-hydraulic controlled locking device 4 and a double-acting cylinder 1 in a third operating state, corresponding to the retraction of the rod 3 of said cylinder 1.

[0105] Figure 6a illustrates the safety module of a locking and control device according to the invention of Figure 6, showing the direction of hydraulic fluid flow during the retraction of the rod 3. In this operating state, the pilot compartment 41 is again supplied with fluid under high pressure, causing the pilot members 35 and 36 to move and consequently opening the pilot valves 37 and 38.

[0106] Thus, in this third operating state illustrated in [Fig. 6] and 6a, the second control compartment 40 is supplied with fluid under high pressure supplied to through a third position of the proportional distributor 45 and back through flow divider 47 to reunify the hydraulic fluid.

[0107] Filling the pilot compartment 41, and consequently opening the pilot valve 38, allows the hydraulic passage 17 of the safety module 5 to be supplied with high-pressure fluid. Filling the pilot compartment 41 also leads to the simultaneous opening of the pilot valves 37 and 38. This establishes fluid communication between the hydraulic passage 16 of the safety module 5 and the reservoir 46 via the first control compartment 39, the line 47a used as a hydraulic return, and the proportional distributor 45. The flow selector 43 isolates this low-pressure return line 47a from the portion of the hydraulic circuit in which the high-pressure fluid circulates.

[0108] Fig. 7 is a hydraulic diagram of the locking and control device of Fig. 6 or 6a, in its third operating state corresponding to a retraction phase of the rod 3. Reference may be made, for example, to Fig. 6a to better visualize the circulation of the fluid through the safety module 5 to bring the hydraulic fluid into the small chamber 11 and evacuate it from the large chamber 10 to the reservoir 46.

[0109] Figure 7a is a hydraulic diagram of another embodiment of an electro-hydraulic locking device 4 according to the invention. The electro-hydraulic locking device 4 is adapted to a single-acting hydraulic cylinder 1, illustrated during the retraction of the rod 3. The control module 6 remains unchanged in both its structure and its operation.

[0110] In contrast, the safety module 5 has only one hydraulic passage 16 in which the primary valve 18 and the secondary valve 19 are arranged in series. This hydraulic passage 16 allows the large chamber 10 of the cylinder 1 to be filled and emptied. The small chamber 11 is no longer connected to the safety module 5. The seal provided by the piston 3a in the barrel 2 is no longer necessary for the proper functioning of the electro-hydraulic controlled locking device 4.

[0111] The safety module 5 includes a pressurization compartment 17a which replaces the hydraulic passage 17. The pressurization compartment 17a is connected via the inlet 13 to the control output 40a of the control module 6. Thus, when the proportional distributor 45 is in the position in which the supply line is supplied with hydraulic fluid under high pressure and when the solenoid valve 42 is activated, the pilot valve 38 is opened and allows the pressurization compartment 17a to be filled with the hydraulic fluid under high pressure.

[0112] The force then exerted on the lateral face 29 of the control part 20 will generate the opening of the primary valves 18 and 19. The opening of the pilot valve 37, concomitant with the opening of the pilot valve 38, then allows the Hydraulic passage 16 at the pressure of the reservoir 46 and the large chamber 10 to empty. This corresponds to the retraction of the rod 3 due to the load it supports.

[0113] Figure 8 is a hydraulic diagram of the electro-hydraulically controlled locking device 4 according to the invention in a fourth operating state corresponding to a non-energized cylinder 1. This state corresponds to the case in which the proportional valve 45 is in its first or third position and the solenoid valve 42 is deactivated and closed. The pilot compartment 41 is therefore not supplied. The cylinders 1 are thus isolated from the rest of the hydraulic circuit via the solenoid valve 42 and the control valves 37, 38 of the control module 6.

[0114] Figure 9 is a hydraulic diagram of another embodiment of the electro-hydraulically controlled locking device 4 according to the invention. Structural and functional elements identical to those in the other embodiments described above will not be described again hereafter to avoid redundancy. In this embodiment, the safety module 5 and the control module 6 are arranged in a single stage mounted on the cylinder 1. The safety module 5 and the control module 6 are, for example, integrated into a single bore 50 formed in a drilled block. In this embodiment, the safety module 5 is made of parts located on either side of the control module 6.

[0115] The central part of the bore 50 is occupied by the control module 6. On one side, the first control compartment 39 is connected via a first conduit 51 and via the pilot valve 37 to the hydraulic passage 16. The latter includes in series the primary valve 18 and the secondary valve 19 through which it is connected to the large chamber 10. On the other side, the second control compartment 40 is connected via a second conduit 52 and via the pilot valve 38 to the hydraulic passage 17. The latter includes in series the primary valve 18 and the secondary valve 19 through which it is connected to the small chamber 11.

[0116] Between the first control compartment 39 and the hydraulic passage 16, the bore 50 incorporates a first supplementary control system comprising a supplementary compartment 53 and a sliding actuating member 54. The movement of the actuating member 54 is caused by the filling of the supplementary compartment 53 with fluid under high pressure. The stroke of this actuating member 54 allows the primary 18 and secondary 19 valves of the hydraulic passage 16 to be pushed into the open position.

[0117] Between the second control compartment 40 and the hydraulic passage 17, the bore 50 incorporates a second complementary piloting system comprising a supplementary compartment 55 and a sliding actuating member 56. The The positioning of the actuating member 5 is triggered by the filling of the auxiliary compartment 55 with fluid under high pressure. The stroke of this actuating member 56 allows the primary 18 and secondary 19 valves of the hydraulic passage 17 to be pushed into the open position.

[0118] Thus, when the solenoid valve 42 is activated, the high-pressure fluid supplies the pilot chamber 41 and one of the control chambers 39 and 40. The first and third positions of the proportional distributor 45 determine which of the control chambers 39 and 40 will be supplied with the high-pressure fluid. Activation of the solenoid valve 42 also allows the auxiliary chambers 53 and 55 to be supplied with high-pressure fluid. Thus, the auxiliary chamber 53, located, for example, on the side of the control chamber 39, when supplied with high-pressure fluid, will not cause the actuating member 54 to slide, since the first machined conduit 51 already supplies the hydraulic passage 16 with high-pressure fluid. The primary valve 18 and secondary valve 19 are then opened, and the large chamber is supplied

[0119] In contrast, the second control compartment 40, isolated from the high-pressure fluid, is in low-pressure communication with the reservoir 46, and the high-pressure fluid injected into the additional compartment 55 allows the primary valve 18 and secondary valve 19 to be opened via the actuating member 56. The low-pressure fluid can then flow from the small chamber 11 to the reservoir 46 via the hydraulic passage 17 and the second control compartment 40. The rod 3 is then in the exit phase of the barrel 2.

[0120] The embodiment illustrated in [Fig.9] also allows the other operating states to be obtained, namely the holding in position of the rod 3, the retraction phase of the rod 3 and the non-stressing of the cylinder 1.

[0121] The invention therefore also relates to a hydraulic circuit comprising several hydraulic cylinders 1, each equipped with an electro-hydraulically controlled locking device 4 and comprising a rod 3 and two chambers 10 and 11, each supplied through a corresponding hydraulic passage 16 and 17 of the safety module 5. The hydraulic circuit also comprises a hydraulic fluid reservoir 46, a distribution block 45, and a set of pipes connecting the reservoir 46 to the cylinders 1 via the distribution block 45, in order to fill and / or empty each of the chambers 10 and 11. The hydraulic circuit also comprises a pumping device comprising a pump P associated with a motor M for circulating the hydraulic fluid in the pipes. The distribution block comprises a single three-position proportional hydraulic distributor 45.

[0122] These positions include a neutral position interrupting the flow of hydraulic fluid to the receivers of the hydraulic circuit or linking the circuit pressure to the pressure of reservoir 46 thus preventing the pressure from increasing in said hydraulic circuit.

[0123] These positions also include a position connecting the pumping device P, M and the reservoir 46 with the control module 6 of at least one cylinder 1 to cause the rod 3 of the cylinder 1 to extend.

[0124] These positions also include a position connecting the pumping device P, M and the reservoir 46 with the control module 6 of at least one cylinder 1 to cause the retraction of the rod 3.

[0125] The control module 6 of each of the electro-hydraulic locking and control devices 4 can advantageously be controlled independently of the other devices.

[0126] According to one embodiment, the cylinders 1 are arranged in several pairs of two cylinders 1 operating in a synchronized manner, the hydraulic circuit further comprising a single flow divider 47 which ensures the synchronism of the movements of each pair of cylinders 1. Each pair of cylinders 1 can advantageously be controlled independently by means of the corresponding electro-hydraulic locking and control devices 4.

[0127] It is evident that the present description is not limited to the explicitly described examples, but also includes other embodiments. Thus, a described technical feature may be replaced by an equivalent technical feature without departing from the scope of the present invention as defined by the claims.

Claims

Claims

1. Electrohydraulically controlled locking device (4) for a hydraulic lifting cylinder (1) comprising a rod (3), making it possible to hold the rod (3) in position by locking the circulation of the hydraulic fluid, the device comprising a safety module (5) intended to be mounted in a hydraulic circuit which supplies fluid to the cylinder (1), the safety module (5) comprising: - two inlets (12, 13) intended to communicate with the hydraulic circuit and at least one outlet (14, 15) each intended to be connected to a chamber (10, 11) of the cylinder (1), - at least one hydraulic passage (16, 17) between at least one of these two inlets (12, 13) and a corresponding outlet (14, 15), provided so that the chamber (10, 11) of the cylinder (1) can only be filled and emptied through this hydraulic passage (16, 17), - at least one device mechanical closure mounted in the hydraulic passage (16,17) to allow a sealed locking of the chamber (10, 11), said closure device being passed under the direct thrust of the fluid entering the hydraulic passage (16, 17) through the first of these two inlets (12, 13) to allow the filling of said chamber (10, 11) and which is also passed under the direct thrust or via the action of a control part (20), of the fluid then entering through the second of these two inlets (12, 13) to allow the emptying of said chamber (10, 11), characterized in that it comprises:, - an electrohydraulic control module (6) for controlling the different operating states corresponding to the extension, retraction, holding in position and non-stressing of the rod (3), connected to the two inputs (12, 13) of the safety module (5) and to the hydraulic circuit, said control module (6) comprising two sliding control members (35, 36) delimiting between them a control compartment (41) and each associated with a control valve (37, 38), a first control compartment (39) connected to the hydraulic passage (16, 17), a second control compartment (40) making it possible to supply the safety module (5) with high-pressure hydraulic fluid and to move the control part (20) in order to empty the chamber (10, 11), the control valves (37, 38) urged into their open position by the control members (35, 36) making it possible to supply one of the inlets (12, 13) with high pressure fluid, - a solenoid valve (42) whose activation and deactivation allows the control module (6) to be supplied or not with high pressure hydraulic fluid, - a flow selector (43) to connect the control compartment (41) to one of the control compartments (39, 40) when the latter is supplied with high pressure hydraulic fluid.

2. Device according to claim 1, characterized in that the mechanical closure device comprises a primary valve (18) and a secondary valve (19) mounted in series, the control part (20) being located close to the primary valve (18), this control part (20) moving in the direction of the primary valve (18) under the thrust of the hydraulic fluid entering through one of the two inlets (12, 13) and causing the opening of said primary valve (18).

3. Device according to claim 2, characterized in that the safety module (5) comprises: - an independent sliding rod (22), arranged longitudinally and interposed between shutters (18a, 19a) of the primary (18) and secondary (19) valves but not connected to the latter and capable of sliding towards each of the shutters (18a, 19a) so as to come to bear by one of its ends against the shutter (18a or 19a) located opposite, - guide members of the bore (23a) and guide support (23) type to guide the sliding of the sliding rod (22), - the length of the sliding rod (22) being sufficiently short so as not to be able to be in contact simultaneously with the two shutters (18a, 19a) bearing on respective seats (18b, 19b) when the two primary valves (18) and secondary (19) are closed, but long enough so that the opening command of the primary valve (18) causes,by the movement of its shutter (18a) which pushes the corresponding end of the sliding rod (22), the sliding of the sliding rod (22) causing the opening of the secondary valve (19) whose shutter (19a) is pushed out of its seat (19b) by the other end of the sliding rod (22).,

4. Device according to any one of claims 1 to 3, characterized in that the control module (6) comprises two control outputs (39a, 40a) each connected to an input (12, 13) of the safety module (5) and two control inputs connected to the hydraulic circuit one of which opens onto the first control compartment (39) and the other opens onto the second control compartment (40), the activation of the solenoid valve (42) and a corresponding active position of the flow selector (43) making it possible to supply fluid under high pressure to the control compartment (41) and one of the control compartments (39, 40), the other of the compartments of the control compartments (39, 40) being in fluid communication under low pressure with a reservoir (46), the first and second control compartments (39, 40) being able to be simultaneously in fluid communication under low pressure with the reservoir (46).

5. Device according to claim 4, characterized in that the control module (6) comprises: - a bore (6a) in which the two control members (35, 36) are arranged, sliding relative to each other in a substantially central zone, - a high-pressure fluid supply orifice opening into the bore (6a) at the interface of the control members (35, 36) which are in contact or close to each other when not in use, - the control compartment (41) corresponding to a space located between the two control members (35, 36) and the volume of which depends on the variable spacing of said control members (35, 36), - the first control compartment (39) being delimited by one end of the bore (6a) and by one of the control members (35, 36), including a first control output (39a) communicates with the first input (12) of the safety module (5) via the pilot valve (37),- the second control compartment (40) being delimited by the other end of the bore (6a) and by the other control member (36), a second control outlet (40a) of which communicates with the second inlet (13) of the safety module via a non-return valve, - said control valves (37, 38) being mounted in opposition and closed when the control members (35, 36) are not acted upon by the high-pressure fluid, thus preventing any circulation of fluid through the control module (6) to the safety module (5), and - said control valves (37, 38) being opened by the action of the control members (35, 36) spaced apart from each other by the filling of the, pilot compartment (41).

6. Device according to any one of claims 1 to 5, characterized in that the safety (5) and control (6) modules are each integrated into a drilled block made in a single piece.

7. Device according to any one of claims 2 to 6, intended for a double-acting hydraulic cylinder (1) comprising a large chamber (10) and a small chamber (11), characterized in that the safety module (5) comprises: - two inlets (12, 13) intended to be connected to the control module (6), - two outlets (14, 15) intended to be connected for the first (14) to an orifice of the large chamber (10) of the cylinder (1) and for the second (15) to an orifice of the small chamber (11) of the cylinder (1), - two hydraulic passages (16, 17) extending for the first (16) between the first (12) of these two inlets (12, 13) and the outlet (14) and for the second hydraulic passage (17) extending between the second (13) of these two inlets (12, 13) and the outlet (15), said hydraulic passages (16, 17) being provided so that the large chamber (10) and the small chamber (11) can only be filled and emptied through one of these two hydraulic passages (16,17), and - a primary valve (18) and a secondary valve (19) placed in series in each of these two hydraulic passages (16, 17) so that the large chamber (10) and the small chamber (11) can be locked in a sealed manner by a primary valve (18) and a secondary valve (19) in series.,

8. Device according to any one of claims 2 to 6, intended for a single-acting hydraulic cylinder (1) comprising a large chamber (10) and a small chamber (11), characterized in that the safety module (5) comprises: - two inlets (12, 13) intended to be connected to the control module (6), - an outlet (14) intended to be connected to an orifice of the large chamber (10) of the cylinder (1), - a hydraulic passage (16) extending between the first (12) of these two inlets (12, 13) and the outlet (14), said hydraulic passage (16) being provided so that the large chamber (10) can only be filled and emptied through the hydraulic passage (16), and - the primary valve (18) and the secondary valve (19) placed in series in the hydraulic passage (16) so that the large chamber (10) can be sealed by the primary (18) and secondary (19) valves.

9. Hydraulic cylinder (1) characterized in that it is equipped with an electrohydraulically controlled locking device (4) according to any one of claims 1 to 8.

10. Hydraulic circuit comprising several hydraulic cylinders (1) each equipped with an electrohydraulically controlled locking device (4) according to any one of claims 1 to 8 and comprising a rod (3) and at least one chamber (10, 11) supplied through a hydraulic passage (16, 17) of the safety module (5), a reservoir (46) of hydraulic fluid, a distribution block, a set of pipes connecting the reservoir (46) to the cylinders (1), via the distribution block (45), in order to fill and / or empty the chamber(s) (10, 11) of the cylinders (1), said hydraulic circuit comprising a pumping device (P, M) for circulating the hydraulic fluid in the pipes, the distribution block comprising a single proportional hydraulic distributor (45) with three positions including a neutral position interrupting the circulation of the hydraulic fluid to the receivers of the hydraulic circuit,a position putting the pumping device (P, M) and the reservoir (46) in communication with the control module (6) of at least one cylinder (1) to cause the rod (3) of the cylinder (1) to come out and a position putting the pumping device (P, M) and the reservoir (46) in communication with the control module (6) of at least one cylinder (1) to cause the rod (3) of the cylinder (1) to come back in, the control module (6) of each of the electrohydraulic locking and control devices (4) being able to be controlled independently of the other devices.,

11. Hydraulic circuit according to claim 10, characterized in that the cylinders (1) are organized into several pairs of two cylinders (1) operating in a synchronized manner and in that the hydraulic circuit further comprises a single flow divider (47), which ensures the synchronism of the movements of each pair of cylinders (1), each pair of cylinders (1) being able to be controlled independently thanks to the corresponding electrohydraulically controlled locking devices (4).

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