Improved hydraulic valve

Abstract

Hydraulic valve comprising a main body (10) and a valve body (20), the main body (10) comprising a pilot groove (54), the valve body (20) comprising a groove (26) adapted to be in fluidic communication with the pilot groove (54) during the movement of the valve body (20) along the main direction (XX), said valve being characterized in that the valve body (20) comprises a pilot conduit (60), connected on the one hand fluidically to the groove (26), and on the other hand to the proximal cavity (34) of the main body (10) via a check valve (70) allowing fluid flow only from the proximal cavity (34) of the main body to the groove (26), and in that the valve body (20) comprises damping means (9090), connecting the pilot conduit (60) to the proximal cavity (34), said damping means (9090) defining a reduced passage cross-section compared to the pilot conduit (60).Figure for the abridged version: Fig. 1.

Description

Title of the invention: Improved hydraulic valve technical field

[0001] The present invention relates to the field of valves for hydraulic circuits. Previous technique

[0002] Valves are commonly used for controlling hydraulic circuits. Conventionally, valves are controlled by means of electric, hydraulic or pneumatic actuators.

[0003] However, valve control requires specific control means. In the case of valves controlled by hydraulic pressure, it is necessary to provide specific pilot lines with reduced pressures, as the components are generally not designed to withstand the operating pressures of hydraulic circuits, which can reach several hundred bars.

[0004] The present invention thus aims to address at least partially these problems. Description of the invention

[0005] The present invention thus relates to a hydraulic valve comprising a main body and a valve body, the main body comprising a housing, the valve body being mounted movably in translation within said housing of the main body in a principal direction, the main body comprising conduits opening into said housing, the valve body extending in the principal direction, comprising grooves adapted to define a plurality of configurations comprising a first connection configuration of said conduits, and a second connection configuration of said conduits, the valve body being movable relative to the main body in the principal direction, the valve body having a proximal end and a distal end in the principal direction, the proximal end being housed in a proximal cavity of the main body,the proximal end comprising an elastic return means tending to move the valve body in a first direction of movement, the main body comprising a pilot groove, the valve body comprising a groove adapted to be in fluidic communication with the pilot groove during the movement of the valve body along the main direction, said valve being characterized in that, the valve body includes a pilot conduit, connected on one side fluidically to the groove, and on the other side to the proximal cavity of the main body via a check valve allowing fluid flow only from the proximal cavity of the main body to the groove, and in that the valve includes damping means forming a restriction between the pilot groove and the proximal cavity.

[0006] For the purposes of this invention, a check valve is defined as a component that allows fluid flow in one direction and restricts this flow in the other. This restriction may be total or partial. The check valve forces fluid through the damping (restriction) means to dampen the movement of the valve body in one direction while preventing damping in the other. Indeed, when the valve is not actuated by a pressure increase in the pilot groove or pilot chamber, it is the elastic return mechanism (for example, a spring) that induces the valve's movement towards its rest position. The spring does not induce a significant shock in the movement of the valve body.However, if the pilot groove or chamber is subjected to high pressure, this can induce a sudden displacement of the valve body; the invention therefore makes it possible to dampen this displacement, at least over a portion of the trajectory.

[0007] According to one example, the damping means include a damping conduit formed in the valve body, said damping conduit connecting the pilot conduit to the proximal cavity, and having a reduced cross-section compared to the pilot conduit.

[0008] According to one example, the damping means are formed by a calibrated clearance between the main body and the valve body, defining a fluid passage section smaller than the pilot conduit section.

[0009] According to one example, the valve body and the main body are configured so as to define: - a first range of displacement along the main direction in which the throat opens into the proximal cavity, - a second range of displacement along the main direction in which the throat does not open into the proximal cavity, and is connected to the proximal cavity via the pilot conduit and the damping means.

[0010] According to one example, the pilot conduit comprises a transverse portion extending radially with respect to the main direction, and a longitudinal portion extending along the main direction, said longitudinal portion opening at the proximal end of the valve body on one side and into the portion transverse on the other hand, the non-return valve being positioned in the longitudinal portion.

[0011] According to one example, the pilot conduit comprises a transverse portion extending radially with respect to the main direction, and a longitudinal portion extending along the main direction, said longitudinal portion opening into the proximal end of the valve body on one side and into the transverse portion on the other, the check valve being positioned in the longitudinal portion, and in which the damping conduit extends radially with respect to the main direction, and is connected to the longitudinal portion of the pilot conduit between the check valve and the junction of the longitudinal portion and the transverse portion.

[0012] According to an example, the damping means define a section Sa, the longitudinal portion (64) of the pilot conduit (60) has a section SI, such that Sa < S1 / 2.

[0013] According to an example, the non-return valve has a passing section S70 such that S70>Sa.

[0014] According to one example, the non-return valve has a passing section S70 substantially equal to the section of the longitudinal portion of the pilot conduit.

[0015] According to one example, the elastic return means is configured to maintain the valve body in the first configuration, and in which a pressure rise in the proximal cavity tends to move the valve body towards the second configuration.

[0016] According to one example, the main body includes a stop, and a spacer is mounted to bear against said stop, so that the valve body comes to rest against said spacer.

[0017] According to one example, the main body comprises a primary segment and a secondary segment, the secondary segment being brought onto the primary segment so as to define the proximal cavity, the secondary segment having greater toughness than the primary segment.

[0018] The present invention also relates to a hydraulic machine comprising a first assembly and a second assembly movable in rotation relative to each other about a principal axis, the first assembly comprising a shaft, a cylinder block and a plurality of pistons mounted to slide in housings of the cylinder block, and the second assembly comprising a housing and a cam, the cam defining a multi-lobe cam profile, the hydraulic machine comprising a high pressure line and a low pressure line, and a distributor adapted to connect the housings of the cylinder block to high pressure lines and low pressure lines, the hydraulic machine comprising a valve for changing the configuration of the behavior of the hydraulic machine, in which the pilot groove of this valve is connected to a high pressure line of the distributor.

[0019] The proposition "the pilot groove is connected to a high-pressure line of the distributor" means, within the meaning of the invention, that the pilot groove is connected directly or indirectly to a supply line of the hydraulic machine. Those skilled in the art understand that, depending on the application, a supply line can become a discharge line (and therefore be connected to the low-pressure side of the hydraulic circuit in which the hydraulic machine is located), depending on the quadrant in which the hydraulic machine is situated. However, the advantage of the invention is that it can at least withstand piloting by high pressure and dampen the shocks experienced by a spool valve piloted by high pressure.

[0020] The expression "change of configuration of the behavior of the hydraulic machine" means in the sense of the invention that the hydraulic machine goes from one configuration to another, for example: goes from one displacement to another, reverses its direction of rotation, goes from a hydraulically engaged configuration to a disengaged configuration, or goes from a Twinlock mode (registered trademark) to a normal mode (the Twinlock system being described in particular in patent FR2861448).

[0021] The present invention also relates to a hydraulic machine comprising a first assembly and a second assembly movable in rotation relative to each other about a main axis, the first assembly comprising a shaft, a cylinder block and a plurality of pistons mounted to slide in housings of the cylinder block, and the second assembly comprising a casing and a cam, the cam defining a multilobe cam profile, the hydraulic machine comprising a high pressure line and a low pressure line, and a distributor adapted to connect the housings of the cylinder block to high pressure conduits and low pressure conduits, the hydraulic machine comprising a valve as defined above, in which the pilot groove is connected to a high pressure conduit of the distributor, said valve being a valve for changing the configuration of the behavior of the hydraulic machine.

[0022] In particular, according to a particular embodiment of the invention, said valve can control the displacement of the hydraulic machine. Brief description of the drawings

[0023] The invention and its advantages will be better understood upon reading the detailed description below of various embodiments of the invention given by way of non-limiting examples.

[0024] [Fig-1] Fig. 1 is a cross-sectional view of an example of a valve according to one aspect of the invention.

[0025] [Fig.2] Fig.2 is another cross-sectional view of an example of a valve according to an aspect of the invention.

[0026] [Fig. 3] Fig. 3 is another cross-sectional view of an example of a valve according to an aspect of the invention.

[0027] [Fig. 4] Fig. 4 is another cross-sectional view of an example of a valve according to an aspect of the invention.

[0028] [Fig.5] Fig.5 schematically presents an example of a known circuit.

[0029] [Fig.6] Fig.6 schematically presents an example of a circuit implementing the invention.

[0030] [Fig.7] Fig.7 presents an example of a hydraulic machine implementing the invention.

[0031] Throughout all the figures, the common elements are identified by identical numerical references. Description of the implementation methods

[0032] An embodiment of the invention is described with reference to Figures 1 to 4.

[0033] These figures represent a hydraulic valve comprising a main body 10 and a valve body 20.

[0034] The main body 10 defines a housing 30 in which the valve body 20 is positioned. The main body 10 can, for example, be a portion of the housing of another element or component, or be an independent element.

[0035] The main body 10 can for example be a distributor housing for a hydraulic machine such as a hydraulic pump or a hydraulic motor.

[0036] The valve body 20 extends along a main direction XX, and is mounted to slide relative to the main body 10 along said main direction XX.

[0037] In the illustrated example, the main body 10 comprises a primary segment 12 and a secondary segment 14 forming a cover assembled on the primary segment 12.

[0038] A proximal end 22 and a distal end 24 are arbitrarily defined for the valve body 20, these designations being arbitrary and not limiting.

[0039] The proximal end 22 opens into a proximal cavity 34 of the main body 10, said proximal cavity 34 being delimited by the primary segment 12 and the secondary segment 14.

[0040] The main body 10 comprises a plurality of internal conduits opening into the housing 30. In the illustrated example, the main body 10 comprises 4 conduits 42, 44, 46 and 48 opening into the housing 30.

[0041] The valve body 20 comprises a plurality of grooves arranged to define several connection configurations of said conduits.

[0042] In the illustrated example, the valve body 20 comprises two grooves 26 and 28. Groove 26 is adapted to either connect conduits 42 and 44 or isolate conduit 42 from conduit 44. Groove 28 is adapted to either connect conduits 46 and 48 or connect conduits 44, 46, and 48. It is understood that this embodiment is not limiting, and that the present invention applies to any configuration of conduits and grooves arranged in the main body 10 and in the valve body 20.

[0043] The hydraulic valve as proposed includes control means adapted to control the movement of the valve body 20 relative to the main body 10 described below.

[0044] The piloting means as proposed include an elastic return means 50, typically a spring, for example a compression spring, adapted to define a default position for the valve body 20.

[0045] The elastic return means 50 is positioned in the proximal cavity 34, here mounted against a shoulder 15 of the main body 10 on one side, and against a shoulder 25 formed at the proximal end 22 of the valve body 20 on the other. In the illustrated example, a support washer 52 is interposed between the shoulder 25 formed at the proximal end 22 of the valve body 20 and the elastic return means 50. The addition of such a support washer 52 makes it possible in particular to improve the bearing area of ​​the elastic return means 50 on the valve body 20.

[0046] The elastic return means 50 as shown is adapted to maintain the valve body 20 by default in a position against the secondary segment 14 of the main body 10, as shown in particular in [Fig.1].

[0047] The main body 10 also includes a stop 80, here formed in the primary body 12, adapted to limit the displacement of the valve body 20 during compression of the elastic return means 50.

[0048] In the illustrated example, the stop 80 is associated with a spacer 82, against which the valve body 20 comes to rest, in particular via the support washer 52. The support washer 52 and the spacer 82 can in particular be formed in materials suitable to support and / or dampen repeated shocks and forces during the operation of the valve.

[0049] It is thus understood that the elastic return means 50 tends to move and maintain the valve in a first configuration, which is its default configuration.

[0050] The control of the movement of the valve body 20 is achieved via a control of the pressure within the proximal cavity 34.

[0051] A pilot groove 54 is formed in the main body 10. This pilot groove 54 is connected to a fluid supply line.

[0052] The valve body 20 is formed so as to allow fluidic communication between the proximal cavity 34 and the pilot groove 54 which varies according to the position of the valve body 20.

[0053] The valve body 20 includes a pilot conduit 60, fluidically connected to the pilot groove 54 on one side, and on the other side to the proximal cavity 34 of the main body 10 via a check valve 70. The check valve is configured so as to be passing in one direction from the proximal cavity 34 towards the pilot groove 54, and blocking in the opposite direction.

[0054] The pilot conduit 60 as proposed comprises a transverse portion 62 extending radially with respect to the main direction XX, and a longitudinal portion 64 extending along the main direction XX and opening into the proximal end 22 of the valve body 20 on one side and into the transverse portion 62 of the pilot conduit 60 on the other.

[0055] The check valve 70 is positioned in the longitudinal portion 64, typically in a housing formed in the proximal end 22 of the valve body 20 into which the longitudinal portion 64 opens.

[0056] A damping conduit 90 is also formed in the valve body 20. The damping conduit 90 as shown extends radially from the longitudinal portion 64 of the pilot conduit, and opens onto an external radial surface of the valve body 20.

[0057] The damping conduit 90 extends from a section of the longitudinal portion 64 of the pilot conduit 20 located between the check valve 70 and the junction between the longitudinal portion 64 of the pilot conduit 20 with the transverse portion 62 of the pilot conduit 60.

[0058] The damping conduit 90 is formed so as to have a smaller cross-section compared to the pilot conduit 60. More precisely, considering that the damping conduit 90 has a cross-section Sa, and that the longitudinal portion 64 of the pilot conduit 20 has a cross-section SI, the cross-sections are such that Sa < SI, or typically such that Sa < Sl / 2, or such that Sa < Sl / 3, or even such that Sa < Sl / 4. The transverse portion 62 of the pilot conduit 60 typically has a cross-section of the same area as the longitudinal portion 64 of the pilot conduit 20.

[0059] The cross-section of the damping conduit 90 is also typically smaller than the cross-section defined by the check valve 70 in its forward direction. Considering that the check valve 70 in its forward direction has a cross-section S70, then we have typically Sa <s70, ou encore sa<s70 2, 3, 4. le clapet anti-retour 70 est typiquement configuré de manière à présenter une section passage dans son sens passant qui égale sensiblement la si portion longitudinale 64 du conduit pilotage 20.

[0060] For the various conduits, the conduit section typically refers to the average section of the conduit, and does not take into account variations in section at the ends or at the junctions with other conduits.

[0061] The embodiment shown, including a damping conduit, is for illustrative purposes only and is not limiting. The invention as proposed more generally comprises damping means adapted to form a restriction between the pilot groove 54 and the proximal cavity 34.

[0062] The damping conduit 90 as described is an example of an embodiment of such damping means 90.

[0063] The damping means 90 can be formed by any other means allowing a restriction to be defined between the pilot groove 54 and the proximal cavity 34.

[0064] According to one embodiment, the damping means 90 can be formed by a calibrated gap between the main body 10 and the valve body 20, this calibrated gap defining a fluid passage section between the pilot groove 54 and the proximal cavity 34 smaller than the section of the pilot conduit 60. In such an embodiment, the dimensions of the main body 10 and the valve body 20 as well as any sealing means interposed between these two elements are calibrated to define the desired passage section.

[0065] The passage section defined by this calibrated clearance can then have a section Sa such as already defined previously with reference to the damping conduit. The various characteristics and functions described with reference to the damping conduit also apply to any other embodiment of the damping means, particularly in the case where the damping means include such a calibrated clearance.

[0066] Other variants could incorporate a restriction within the non-return valve itself (for example a calibrated conduit) thus forming the damping means 90.

[0067] The valve body 20 is further configured so that, for a first range of movement along the main direction XX, the pilot groove 54 is connected to the proximal cavity 34 without having to go through the pilot conduit 60, and, for a second range of movement along the main direction XX, the pilot groove 54 is connected to the proximal cavity 34 only via the pilot conduit 60.

[0068] In other words, for a displacement of the valve body 20 in a given direction of displacement, a range of displacement is defined for which the displacement is damped, and a range of displacement for which the displacement is not damped.

[0069] In the embodiment shown, this function is ensured by the formation of a groove 26 formed in the valve body 20, into which the transverse portion 62 of the pilot conduit 60 opens. The groove 26 is formed so as to be in fluidic communication with the pilot groove 54 throughout the movement of the valve body 20. On the other hand, the groove 26 is formed so that for the second range of movement of the valve body 20 along the main direction XX, the groove 26 does not open directly into the proximal cavity 34 (it is then connected to the proximal cavity via the pilot conduit 60).

[0070] An example of the operation of the device as presented is now described.

[0071] We consider an initial configuration such as represented in [Fig.1].

[0072] In this figure, as already indicated previously, the valve is in its default position; the elastic return means 50 maintains the valve body 20 in contact with the secondary segment 14 of the main body 10. The pressure applied in the proximal cavity 34 is then insufficient to cause the displacement of the valve body 10.

[0073] Figure 2 represents the displacement of the valve body 10 within the first displacement range mentioned previously. Within this displacement range along the principal axis XX, a pressurized fluid is injected through the pilot groove 54, which raises the pressure within the proximal cavity 34 and displaces the valve body 20 in a direction opposing the force exerted by the return means 50, here in a direction of spring compression.

[0074] As described previously, in this first range of movement, the groove 26 formed in the valve body 20 communicates directly with the proximal cavity 34. The pressure applied via the pilot groove 54 is thus applied directly into the proximal cavity 34.

[0075] Fig. 3 schematically shows the boundary between the first range of displacement and the second range of displacement of the valve body 20 relative to the main body 10.

[0076] This figure schematically shows the position of the valve body 20 relative to the main body 10 from which (or up to which, depending on the direction of movement of the valve body 20 considered) the groove 26 is no longer in direct communication with the proximal cavity 34. In other words, a fluid arriving in the groove 26 via the pilot groove 54 can no longer enter directly into the proximal cavity 34 without passing through the pilot conduit 60.

[0077] Due to the structure of the pilot conduit 60, the pressurized fluid must therefore pass through the damping conduit 90 to reach the proximal cavity 34, the non-return valve 70 being non-passing in this direction of circulation.

[0078] As previously stated, the damping conduit 90 has a reduced cross-section compared to the other portions of the pilot conduit 60. This variation in cross-section results in pressure losses, and thus damping in the establishment of pressure within the proximal cavity 34.

[0079] Fig. 4 schematically shows the valve body 20 in its position against the main body 20, i.e. at the maximum of its displacement along the main direction XX in a direction of compression of the elastic return means 50. The valve body here comes to rest via its support washer 52 against the spacer 82 mounted to bear on the stop 80.

[0080] This figure shows that the pilot groove 54 is always in communication with the pilot conduit 60 via the groove 26. As with [Fig.3], a fluid arriving in the groove 26 via the pilot groove 54 can only enter the proximal cavity 34 by passing through the pilot conduit 60.

[0081] During the movement from the position illustrated in [Fig.3] to the position illustrated in [Fig.4], that is to say during the movement along the second range of movement of the valve body 20, it is therefore understood that the establishment of the pressure in the proximal cavity 34 is done via the pilot conduit 60 and the damping conduit 90.

[0082] This establishment of pressure via the damping conduit 90, which has a reduced cross-section compared to the pilot conduit 60, leads to pressure losses and thus a delay in the establishment of pressure in the proximal cavity 34, which leads to a damping effect on the displacement of the valve body 20 during the movement according to the second range of displacement of the valve body 20, i.e. up to the stop against the spacer 82 or where applicable against the stop 80.

[0083] This damping effect makes it possible, in particular, to use high pressures for valve actuation. Indeed, the damping function allows the use of pressures of several hundred bar, typically on the order of 450 bar or even more, for valve actuation. As mentioned in the introduction, in conventional systems, such pressures are not usable for actuation due to the risk of component degradation.

[0084] The invention as proposed overcomes such constraints, and thus allows the valve to be piloted by means of a high-pressure line, without requiring a dedicated pilot line having a reduced pressure.

[0085] As described with reference to Figures 1 to 4, the damping is achieved for a direction of movement of the valve body 20 corresponding to the direction of compression of the means elastic return 50. Thus, for a direction of movement, the movement of the valve body 20 is initially without damping, then with damping.

[0086] We now describe the reverse direction of movement, that is to say to go from a configuration with the elastic return means 50 compressed as shown in [Fig.4] to the default configuration as shown in [Fig.1].

[0087] To achieve such a displacement of the valve body 20, the pressure applied via the pilot groove 54 is reduced or stopped. The pressure within the proximal cavity 34 is then discharged via the damping conduit 90 and also via the non-return valve 70, which is open in this direction of flow.

[0088] Thus, contrary to the displacement described above, the displacement of the valve body 20 in this direction of movement can be achieved without damping effect due to the passage through the check valve 70 which is typically dimensioned so as to have a passing cross-section equal or substantially equal to the cross-section of the transverse portion 62 and the longitudinal portion 64 of the pilot conduit 60, and which is therefore typically strictly greater than the cross-section of the damping conduit 90. Such a configuration thus makes it possible to ensure a rapid return of the valve to its default configuration under the action of the elastic return means 50.

[0089] The secondary segment 14 is then typically formed in a material suitable to withstand mechanical stresses and to withstand the high pressure within the proximal cavity 34. The secondary segment 14 is thus typically formed of a material having a higher impact resistance (or toughness) than the material from which the primary segment 12 is formed.

[0090] As previously stated, the hydraulic valve as proposed can be piloted via a high-pressure line, and does not require a dedicated intermediate pressure line.

[0091] Figures 5 and 6 schematically illustrate this effect.

[0092] Figure 5 shows an example of a portion of a conventional hydraulic circuit for displacement control of a variable displacement hydraulic motor. In such a hydraulic motor, it is typically possible to supply all or part of the pistons. Such a hydraulic motor is usually referred to as a 2C hydraulic motor.

[0093] The hydraulic motor 100 thus comprises two sub-motors 100A and 100B. It is supplied via a high-pressure inlet line 120 and a low-pressure return line 130. A pilot valve 110 controls the supply to the two sub-motors 100A and 100B and performs a displacement selection function. It can be seen that in a first configuration, corresponding to the configuration shown in [Fig. 5], both sub-motors 100A and 100B are supplied. The displacement is therefore at its maximum. In a second configuration, only one of the sub-motors (here the under motor 100A) is engaged, the displacement is therefore reduced, the other motor is put into recirculation or bypass (according to the usual term in English).

[0094] Conventionally, the piloting of the pilot valve 110 is carried out by a hydraulic control connected to an intermediate pressure line 140.

[0095] Figure 6 shows a similar assembly employing a valve according to the invention.

[0096] This figure shows the high-pressure inlet line 120 and the low-pressure return line 130, as well as the valve 110 which controls the supply to the two sub-motors 100A and 100B and thus performs a displacement selection function. The various ports of this valve 110 are identified by the corresponding reference numerals in the preceding figures.

[0097] The use of the valve as proposed, as a pilot valve 110, allows piloting by means of the high pressure of the hydraulic circuit. The proposed valve is schematically represented here by a restriction 90 mounted in parallel with the check valve 70. The proposed hydraulic control structure eliminates the need for an additional intermediate pressure line 140; a high-pressure line can be used for piloting.

[0098] Figure 7 presents an example of the integration of such a valve into a hydraulic machine structure, which could be, for example, a hydraulic pump or a hydraulic motor.

[0099] This figure shows a hydraulic machine 1, comprising a first assembly and a second assembly that rotate relative to each other about an axis of rotation ZZ which defines an axial direction. In the illustrated example, tapered roller bearings 210 ensure rotation between these two assemblies. The first assembly can be fixed and the second assembly movable, or vice versa. A rotational speed W is defined between the first assembly and the second assembly, this rotational speed corresponding to the rotational speed of the hydraulic machine 1.

[0100] A housing is defined for the hydraulic machine, defining an internal volume in which a shaft 220 extending along an axial direction ZZ and a cylinder block 230 are positioned. The housing may, in particular, be partially formed by elements such as the cam 250 and the distribution cover. The cylinder block 230 comprises a plurality of housings 232 in which pistons 240 are mounted, sliding radially with respect to the axial direction ZZ.

[0101] The hydraulic machine 1 also includes a multilobe cam 250 positioned around the cylinder block 230. The cam 250 defines a plurality of lobes adapted to cooperate with the pistons 240 during the operation of the hydraulic machine 1. The cylinder block 230 is positioned opposite a planar distributor 260 defining fluid supply and discharge conduits linked to the various housings 232 in which the pistons 240 slide.

[0102] For the hydraulic machine 1, a first assembly comprising the cylinder block 230 is defined, and a second assembly comprising the casing and the cam 250. The first assembly and the second assembly are mobile relative to each other in rotation along the axial direction ZZ, one of these assemblies being fixed and the other mobile according to the application considered.

[0103] The hydraulic machine 1 is typically reversible. It can operate as a hydraulic pump or a hydraulic motor depending on its use, the operation of such a hydraulic machine 1 being well known.

[0104] The valve as proposed is integrated here into the hydraulic machine 1, and allows in particular the supply of the distributor 260 to be modulated, which can thus enable a function of selecting the displacement of the hydraulic machine.

[0105] The invention finds particular application in the manufacture of machines and tools such as wood harvesting machines.

[0106] Although the present invention has been described with reference to specific embodiments, it is evident that modifications and changes can be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various embodiments illustrated / mentioned can be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than a restrictive sense.

[0107] It is also evident that all the characteristics described with reference to a process are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a process.

Claims

Demands

1. Hydraulic valve comprising a main body (10) and a valve body (20), the main body (10) comprising a housing, the valve body (20) being mounted movably in translation within said housing of the main body along a principal direction (XX), the main body (10) comprising conduits (42, 44, 46, 48) opening into said housing, the valve body (20) extending along the principal direction (XX), comprising grooves (26, 28) adapted to define a plurality of configurations comprising a first connection configuration of said conduits, and a second connection configuration of said conduits, the valve body (20) being movable relative to the main body along the principal direction (XX), the valve body having a proximal end (22) and a distal end (24) along the principal direction (XX), the proximal end (22) being housed in a proximal cavity (34) of the main body (10),the proximal end (22) comprising an elastic return means (50) tending to move the valve body (20) in a first direction of movement, the main body (10) comprising a pilot groove (54), the valve body (20) comprising a groove (26) adapted to be in fluidic communication with the pilot groove (54) during the movement of the valve body (20) along the main direction (XX), said valve being characterized in that the valve body (20) comprises a pilot conduit (60), connected on the one hand fluidically to the groove (26), and on the other hand to the proximal cavity (34) of the main body (10) via a check valve (70) allowing fluid circulation only from the proximal cavity (34) of the main body to the groove (26), and in that the valve comprises damping means (90) forming a restriction between the pilot groove (54) and the proximal cavity (34).

2. Valve according to claim 1, wherein the damping means (90) comprise a damping conduit formed in the valve body (20), said damping conduit connecting the pilot duct (60) to the proximal cavity (34), and having a reduced cross-section compared to the pilot duct (60).

3. Valve according to claim 1, wherein the damping means (90) are formed by a calibrated clearance between the main body (10) and the valve body (20), defining a fluid passage section smaller than the pilot conduit section (60).

4. Valve according to any one of claims 1 to 3, wherein the valve body (20) and the main body (10) are configured so as to define: - a first range of displacement along the main direction for which the groove (26) opens into the proximal cavity (34), - a second range of displacement along the main direction in which the groove (26) does not open into the proximal cavity (34), and is connected to the proximal cavity (34) via the pilot conduit (60) and the damping means (90).

5. Valve according to any one of claims 1 to 4, wherein the pilot conduit (60) comprises a transverse portion (62) extending radially with respect to the main direction (XX), and a longitudinal portion (64) extending along the main direction (XX), said longitudinal portion (64) opening into the proximal end (22) of the valve body (20) on one side and into the transverse portion (62) on the other, the check valve (70) being positioned in the longitudinal portion (64).

6. Valve according to claim 2, wherein the pilot conduit (60) comprises a transverse portion (62) extending radially with respect to the main direction (XX), and a longitudinal portion (64) extending along the main direction (XX), said longitudinal portion (64) opening into the proximal end (22) of the valve body (20) on one side and into the transverse portion (62) on the other, the check valve (70) being positioned in the longitudinal portion (64), and wherein the damping conduit (90) extends radially with respect to the main direction (XX), and is connected to the longitudinal portion (64) of the pilot conduit (60) between the check valve (70) and the junction of the longitudinal portion (64) and the transverse portion (62).

7. Valve according to any one of claims 1 to 6, wherein the damping means (90) define a section Sa, the portion longitudinal (64) of the pilot conduit (60) has a section SI, such that Sa < Sl / 2.

8. Valve according to claim 7, wherein the check valve (70) has a through section S70 substantially equal to the section of the longitudinal portion (64) of the pilot conduit (60).

9. Valve according to any one of claims 1 to 8, wherein the elastic return means (50) is configured to maintain the valve body (20) in the first configuration, and wherein a pressure rise in the proximal cavity (34) tends to move the valve body (20) towards the second configuration.

10. Hydraulic machine (1) comprising a first assembly and a second assembly movable in rotation with respect to each other about a principal axis (ZZ), the first assembly comprising a shaft (20), a cylinder block (30) and a plurality of pistons (40) mounted to slide in housings (32) of the cylinder block (30), and the second assembly comprising a housing and a cam (50), the cam (50) defining a multilobe cam profile, the hydraulic machine comprising a high pressure line and a low pressure line, and a distributor adapted to connect the housings of the cylinder block to high pressure lines and low pressure lines, the hydraulic machine comprising a valve for changing the configuration of the behavior of the hydraulic machine, in which the pilot groove of this valve is connected to a high pressure line of the distributor.

11. Hydraulic machine (1) comprising a first assembly and a second assembly movable in rotation relative to each other about a principal axis (ZZ), the first assembly comprising a shaft (20), a cylinder block (30) and a plurality of pistons (40) mounted to slide in housings (32) of the cylinder block (30), and the second assembly comprising a housing and a cam (50), the cam (50) defining a multilobe cam profile, the hydraulic machine comprising a high-pressure line and a low-pressure line, and a distributor adapted to connect the housings of the cylinder block to high-pressure lines and low-pressure lines, the hydraulic machine comprising a valve for changing the configuration of the behavior of the hydraulic machine according to one of the preceding claims, wherein the pilot groove of this valve is connected to a high-pressure conduit of the distributor.

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