Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/122—Details or component parts, e.g. valves, sealings or lubrication means
  • F04B1/124—Pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
  • F03C1/00—Reciprocating-piston liquid engines
  • F03C1/02—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders
  • F03C1/06—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis
  • F03C1/0602—Component parts, details
  • F03C1/0605—Adaptations of pistons
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
  • F03C1/00—Reciprocating-piston liquid engines
  • F03C1/02—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders
  • F03C1/06—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis
  • F03C1/0636—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03C—POSITIVE-DISPLACEMENT ENGINES DRIVEN BY LIQUIDS
  • F03C1/00—Reciprocating-piston liquid engines
  • F03C1/02—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders
  • F03C1/06—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis
  • F03C1/0636—Reciprocating-piston liquid engines with multiple-cylinders, characterised by the number or arrangement of cylinders with cylinder axes generally coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F03C1/0644—Component parts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
  • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
  • F04B1/20—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis having rotary cylinder block
  • F04B1/2014—Details or component parts
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/14—Pistons, piston-rods or piston-rod connections
  • F04B53/143—Sealing provided on the piston
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/18—Lubricating

Definitions

• the present invention relates to a hydraulic piston with a depressurized groove in particular intended to receive the sealing device for a piston described in patent No. FR 3 009 037 published on January 29, 2016 and belonging to the applicant.
• the depressurized groove hydraulic piston according to the invention applies primarily to axial piston hydraulic pumps and motors, regardless of their maximum operating pressure. However, this does not exclude the application of said invention to any other type of pump or hydraulic motor comprising one or more pistons.
• the piston which receives the sealing device has a piston head which comprises a fixed skirt. Said piston also comprises on the one hand, a piston bearing face to exert a force on the transmission means and on the other hand, a compression face which opens into the fluid chamber to receive the pressure of a fluid. .
• the sealing device according to patent FR 3 009 037 comprises in particular a sliding skirt of cylindrical shape which is housed with low clearance in the cylinder and which is placed in the extension of the piston head, on the side of the face. compression of said piston, and in the axis of said head.
• the sliding skirt is connected to the piston head by a mechanical inter-skirt connection which allows said sliding skirt to move in longitudinal translation relative to said head.
• the sealing device according to patent FR 3 009 037 also comprises a pressure transmission channel arranged inside the sliding skirt and passing through the latter right through in the axial direction.
• the sealing device according to patent FR 3 009 037 also comprises an extendable continuous segment of continuous annular shape, interposed between the fixed skirt and the sliding skirt, and comprising an internal cylindrical face of the segment subjected to the pressure of the fluid via the pressure transmission channel, an external cylindrical face of the segment able to come into contact with the cylinder, an axial face of the segment on the fixed skirt side maintained in sealed contact with the fixed skirt, and an axial face of a segment on the sliding skirt side maintained in sealed contact with the sliding skirt.
• the sealing device according to patent FR 3009037 comprises a sliding skirt spring which tends to bring the sliding skirt closer to the fixed skirt, and to axially compress the continuous extensible segment.
• the continuous extensible segment must be subjected to a sufficient radial pressure difference between its internal cylindrical face of the segment subjected to the pressure of fluid via the pressure transmission channel, and its segment outer cylindrical face which can come into contact with the cylinder.
• said difference arises from the gap in sealing between that produced by the sliding skirt, which must be high, and that produced by the fixed skirt, which must be low.
• pistons are most often housed in a rotating barrel and are terminated by an articulated shoe which slides on an inclined or tilting plate depending on whether said pump or said motor is fixed or variable displacement.
• each piston is subjected to high radial forces. Indeed, when the tilting plate is strongly inclined and a high pressure prevails in the fluid chamber, the articulated shoe that each said piston has exerts a high radial force on said plate. Said force in return produces equally high radial forces which are exerted by each said piston on the cylinder in which it moves.
• a first radial force appears between said piston and said cylinder at the end of said piston which is positioned opposite the articulated shoe, while a second radial force appears at the end of the cylinder which emerges in the direction of the inclined plateau.
• the fixed skirt of the hydraulic piston must firstly be sufficiently elusive to allow the extendable continuous segment to operate, and secondly, capable of ensuring contact. little energy dissipative between the piston and its cylinder despite the high radial forces produced between these two members, and more particularly, despite the high radial forces occurring at the outlet of the cylinder oriented towards the inclined plate.
• said piston according to the invention makes it possible to implement the sealing device according to patent FR 3 009 037 on the hydraulic pistons of any axial piston pump or motor on the one hand, by bringing together all the conditions necessary for the proper functioning of the extendable continuous segment, and on the other hand, by bringing back to a normal level the energy losses by friction of said pumps or motors when the latter operate at high displacement and high power.
• hydraulic piston with a depressurized groove according to the invention also allows, according to a particular embodiment:
• hydraulic piston with a depressurized groove can be applied, in addition to hydraulic pumps and motors with axial or radial pistons, to any piston of any hydraulic or pneumatic device which can advantageously receive the device.
• 'sealing according to patent FR 3009037 or which can receive, as an alternative to said device, one or more cutting segments or any other sealing means which only works correctly on the condition of being mounted on a piston whose skirt fixed is sufficiently elusive.
• the depressurized groove hydraulic piston according to the present invention can translate in a cylinder, the external cylindrical surface of said piston constituting a fixed skirt while one of the ends of said piston has an axial compression face which forms with the cylinder a fluid chamber of variable volume filled with a working fluid, while the other end of said piston has an axial working face which cooperates with transmission means, said piston comprising:
• Sealing means positioned in the vicinity of the axial compression face, on the fixed skirt or at the end of the latter, said means being able to come into contact with the cylinder;
• At least one axial decompression duct arranged inside the fixed skirt and opening out in the vicinity of the axial working face
• At least one radial decompression duct which places the depressurized radial groove in communication with the axial decompression duct.
• the hydraulic piston with depressurized groove comprises at least one axial decompression groove which opens onto the surface of the fixed skirt and which places the sealing means in communication with the depressurized radial groove, said axial groove possibly being continuous or non-continuous.
• the hydraulic piston with depressurized groove according to the present invention comprises an axial decompression groove which is helical.
• the depressurized groove hydraulic piston comprises a fixed skirt which is hollow and which permanently and tightly accommodates a decompression sleeve, a radial space left between the interior of said skirt and the exterior of said skirt. sleeve forming at least part of the axial decompression duct.
• the depressurized groove hydraulic piston comprises a decompression sleeve which accommodates an internal sleeve lubrication duct which cooperates with an internal piston lubrication duct, the latter opening at the level of the axial working face or in the vicinity of the latter, this to convey part of the working fluid from the fluid chamber to the transmission means.
• the hydraulic piston with depressurized groove comprises sealing means which consist of: • At least one sliding skirt of cylindrical shape, housed with low clearance in the cylinder and placed in the extension and in the axis of the fixed skirt on the side of the axial compression face, said sliding skirt being connected to the fixed skirt by a mechanical inter-skirt connection which allows a displacement in longitudinal translation of said sliding skirt relative to the fixed skirt, the amplitude of said displacement being limited by a sliding skirt stop which is directly or indirectly secured to the mechanical inter-skirt connection ;
• At least one pressure transmission channel arranged inside the sliding skirt and passing right through the latter in the axial direction;
• At least one extensible continuous segment of continuous annular shape interposed between the fixed skirt and the sliding skirt, and having an internal cylindrical face of the segment subjected to the pressure of the working fluid via the pressure transmission channel, an external cylindrical face of segment that can come into contact with the cylinder, an axial face of a segment on the fixed skirt side maintained directly or indirectly in sealed contact with the fixed skirt and an axial face of a segment on the sliding skirt side maintained directly or indirectly in sealed contact with the sliding skirt.
• the depressurized groove hydraulic piston according to the present invention comprises at least one sliding skirt spring which tends to bring the sliding skirt closer to the fixed skirt, and to axially compress the continuous extensible segment.
• the hydraulic piston with depressurized groove comprises a mechanical inter-skirt connection which consists of a double-threaded screw which has a first thread which is screwed into an internal thread made inside the fixed skirt. and which axially plates the decompression sleeve in said skirt by means of a screw shoulder, and a second thread onto which the sliding skirt stopper is screwed.
• the depressurized groove hydraulic piston comprises a sliding skirt spring which is housed in a spring basket which passes through all or part of the sliding skirt, the radial thickness of the latter being provided sufficiently small so that said skirt can accommodate said basket in its center, said basket having, on the one hand, an outer basket flap which bears on the sliding skirt, and on the other hand, an inner basket flap on which rests on one of the ends of the sliding skirt spring, the other end of the latter resting on a spring bearing shoulder arranged or attached to the mechanical inter-skirt connection.
• the depressurized groove hydraulic piston according to the present invention comprises an outer surface of the spring basket which has centering means which radially center said basket in the sliding skirt, while the axial orientation of said basket with respect to said skirt is ensured by the contact between the outer basket flap and said skirt.
• the depressurized groove hydraulic piston according to the present invention comprises a sliding skirt stop which can be supported either on the outer basket flap or on the inner basket flap.
• the hydraulic piston with depressurized groove comprises a mechanical inter-skirt connection which accommodates an internal lubricating connection duct which cooperates with an internal piston lubrication duct, the latter opening at the level of the axial face of the piston. work or in the vicinity of the latter, this to convey a part of the working fluid from the fluid chamber to the transmission means.
• the depressurized groove hydraulic piston according to the present invention comprises an axial length of the depressurized radial groove which is greater than the diameter of the radial decompression duct, so that said groove constitutes a reservoir of working fluid.
• FIG. 1 is Figure 1 is a schematic sectional view of a variable displacement hydraulic pump equipped with depressurized groove hydraulic pistons according to the invention, said pistons being oriented axially.
• FIG. 2 is a schematic sectional view of the hydraulic piston with a depressurized groove according to the invention, the sealing means of which consist of a segment with a section.
• FIG. 3 is a schematic sectional view of the hydraulic piston with depressurized groove according to the invention, a decompression sleeve being screwed directly into the fixed skirt to form with the latter part of the axial decompression duct, while the sealing means consist of a cut segment.
• FIG. 4 is a schematic sectional view of the hydraulic piston with depressurized groove according to the invention, a decompression sleeve being fixed in the fixed skirt by means of a screw to form with said skirt part of the axial decompression duct, while the sealing means consist of a sectional segment.
• FIG. 5 is a schematic sectional view of the hydraulic piston with depressurized groove according to the invention, a decompression sleeve being fixed in the fixed skirt by means of a double-threaded screw to form part of the axial duct with said skirt. decompression, while the sealing means consist of a continuous extensible segment held clamped between a sliding skirt and the fixed skirt by a sliding skirt spring.
• FIG. 6 is a close schematic sectional view of the depressurized groove hydraulic piston according to the invention and according to its variant shown in Figure 5, which illustrates the operation of said piston when the working fluid is admitted into the fluid chamber.
• FIG. 7 is a close schematic sectional view of the hydraulic piston with depressurized groove according to the invention and according to its variant shown in Figure 5, which illustrates the operation of said piston when the working fluid is forced out of the fluid chamber.
• FIG. 8 is a three-dimensional view of the depressurized groove hydraulic piston according to the invention, the sealing means of which consist of an expandable continuous segment held clamped between a sliding skirt and the fixed skirt by a sliding skirt spring.
• FIG. 9 is a cut-away three-dimensional view of the hydraulic piston with depressurized groove according to the invention and according to its variant shown in FIG. 8, which makes it possible in particular to distinguish a decompression sleeve fixed in the fixed skirt by means of a double screw net.
• FIG. 10 is an exploded three-dimensional view of the hydraulic piston with depressurized groove according to the invention and according to the variant shown in Figures 8 and 9, the different components which form said variant can be clearly distinguished.
• Figures 1 to 10 show the depressurized groove hydraulic piston 1 according to the invention, various details of its components, its variants, and its accessories.
• the hydraulic piston with depressurized groove 1 comprises sealing means 8 positioned in the vicinity of the axial compression face 4.
• Said means 8 are arranged or housed either on the fixed skirt 3, or at the end of the latter.
• the sealing means 8 can come into contact with the cylinder 2 and be, for example and as shown in Figures 2 to 4, consist of a segment 38 housed in a throat known per se.
• Said means 8 can also consist of any other sealing device whose operation requires that the fixed skirt 3 is preferably leaky and non-sealed.
• the hydraulic piston with depressurized groove 1 comprises at least one radial depressurized groove 9 opening out at the surface of the fixed skirt 3, said groove 9 being able to be continuous or non-continuous.
• the depressurized radial groove 9 is positioned axially on the fixed skirt 3 so as to never be able to exit from the cylinder 2 whatever the axial position of said skirt 3 with respect to said cylinder 2.
• the hydraulic piston with depressurized groove 1 comprises at least one axial decompression duct 11 arranged inside the fixed skirt 3 and emerging in the vicinity of the axial working face 6.
• the axial decompression duct 11 can open out inside the pump casing 49 of a variable-displacement axial piston hydraulic pump 37, the pressure prevailing in said casing 49 being low compared to that reached inside the fluid chamber 5.
• the hydraulic piston with depressurized groove 1 comprises at least one radial decompression duct 12 which places the radial depressurized groove 9 in communication with the axial duct of decompression 11.
• the hydraulic piston with depressurized groove 1 can comprise at least one axial decompression groove 10 which opens onto the surface of the fixed skirt 3 and which places the means in communication. sealing 8 with the depressurized radial groove 9, said axial groove 10 possibly being continuous or non-continuous.
• the axial decompression groove 10 can be helical to prevent the local lift defect that it produces does not remain oriented on a only angular position with respect to the hydraulic piston with depressurized groove 1 during the displacement stroke of the latter in the cylinder 2.
• the fixed skirt 3 can be hollow and can accommodate in a fixed and sealed manner a decompression sleeve 13, a radial space left between the inside of said skirt 3 and the outside of said sleeve 13 forming at least part of the axial decompression duct 11.
• the decompression sleeve 13 can be held in place inside the skirt 3 by means of at least one sleeve screw 51 as shown in Figure 4, by a clip or by a rivet, or more directly by screwing as shown in Figure 3, by welding, by crimping, or by any fixing means known to those skilled in the art.
• the end of the decompression sleeve 13 which is closest to the axial working face 6 can be planar, conical, spherical, or of any geometry whatsoever, this to form a sealed contact with a additional span fitted inside the fixed skirt 3.
• the decompression sleeve 13 can accommodate an internal sleeve lubrication duct 14 which cooperates with an internal lubrication duct of piston 15, the latter opening at the level of the axial working face 6 or in the vicinity of the latter.
• the sealing means 8 may consist of at least one sliding skirt. 18 of cylindrical shape, housed with small clearance in the cylinder 2 and placed in the extension and in the axis of the fixed skirt 3 on the side of the axial compression face 4.
• the sliding skirt 18 is connected to the fixed skirt 3 by a mechanical inter-skirt connection 19 which allows displacement in longitudinal translation of said sliding skirt 18 relative to the skirt. fixed 3, the amplitude of said displacement being limited by a stop sliding skirt 29 which is directly or indirectly integral with the mechanical inter-skirt connection 19.
• sliding skirt stop 29 can be attached to the inter-skirt mechanical connection 19 by screwing with locking by a lock nut 40 or not, by welding, by crimping, or by any other means of fixing known to those skilled in the art.
• Figure 1 and Figures 5 to 10 further show that according to said particular configuration of the sealing means 8 of the hydraulic piston with depressurized groove 1 according to the invention, at least one extendable continuous segment 21 of continuous annular shape is interposed between the fixed skirt 3 and the sliding skirt 18, and has an internal cylindrical face of segment 22 subjected to the pressure of the working fluid 23 via the pressure transmission channel 20, an external cylindrical face of segment 24 being able to come into contact with the cylinder 2, an axial face of a segment on the fixed skirt side 25 maintained directly or indirectly in sealed contact with the fixed skirt 3 and an axial face of a segment on the sliding skirt side 26 maintained directly or indirectly in sealed contact with the sliding skirt 18.
• the sliding skirt spring 27 can be for example helical, or else consist of a multi-turn wave spring as shown in Figure 1, Figures 5 to 7 and Figures 9 and 10, the latter type of spring having the advantage of an angularly uniform support. These examples being given only by way of nonlimiting, the sliding skirt spring 27 can also be of any type known to those skilled in the art.
• the sealing means 8 consist in particular of an extendable continuous segment 21 interposed between a sliding skirt 18 and the fixed skirt 3 as has just been described, it is noted that the mechanical connection between skirts 19 may consist of a double-threaded screw 30 shown in figure 1, in figures 5 to 7 and in figures 9 and 10.
• the double-threaded screw 30 has a first thread which is screwed into an internal thread formed inside the fixed skirt 3 and which axially plates the decompression sleeve 13 in said skirt 3 via a screw shoulder 31, and a second thread onto which the sliding skirt stop 29 is screwed.
• the screw shoulder 31 can provide a shoulder key socket 41 allowing the tightening of the double screw. thread 30 in the fixed skirt 3.
• a wrench or screwdriver socket can be fitted at the end of the second thread.
• the double-thread screw 30 may have a narrowing of diameter 42 over part of its length as shown in Figures 9 and 10, this to locally reduce the section and give it more elasticity, and in order to prevent any loosening of said screw 30.
• a stop key socket 43 can be provided on the sliding skirt stop 29 which makes it possible to immobilize the latter when it is locked in position by a lock nut 40.
• the sliding skirt spring 27 can be housed in a spring basket 32 which passes through all or part of the sliding skirt 18, the radial thickness of the latter being provided sufficiently small so that said skirt 18 can accommodate said basket 32 at its center.
• the spring basket 32 may have, on the one hand, an outer basket flap 33 which bears on the sliding skirt 18, and on the other hand, an inner basket flap 34 on which rests one of the ends of the sliding skirt spring 27, the other end of the latter resting on a spring bearing shoulder 44 fitted or attached to the inter-skirt mechanical connection 19.
• the spring bearing shoulder 44 can be arranged on the sliding skirt stop 29, the latter being screwed onto the second thread with a screw. double thread 30.
• the spring basket 32 can advantageously be perforated to allow the working fluid 23 to circulate.
• the centering means 39 may for example consist of an elastic ring 28 which encloses a groove arranged on the periphery of the body of the spring basket 32, or else consist of a boss arranged on the periphery of said body.
• sliding skirt stop 29 can be supported either on the outer basket flap 33 or on the inner basket flap as illustrated in Figures 6 and 7.
• the mechanical inter-skirt connection 19 can accommodate an internal lubrication duct 35 which cooperates with an internal lubrication duct of piston 15, the latter opening at the level of the axial working face 6 or in the vicinity of the latter, in order to convey a part of the working fluid 23 from the fluid chamber 5 to the transmission means 7 in order to lubricate the latter.
• the transmission means 7 may for example consist of an articulated shoe 16 sliding on a tilting plate 17 or not.
• the internal lubrication link 35 may be formed of an axial duct and one or more radial ducts.
• the depressurized radial groove 9 constitutes a working fluid reservoir 36 which never empties entirely via the radial decompression duct 12 during the movement of the depressurized groove hydraulic piston 1 according to the invention in the cylinder 2, and under the effect of the acceleration which results from said displacement.
• Figure 1 shows the depressurized groove hydraulic piston 1 according to the invention applied to a variable displacement axial piston hydraulic pump 37 known per se, said pump 37 having a pump casing 49 in which its main components are housed .
• the sealing means 8 can advantageously consist of an extendable continuous segment 21 held clamped between a sliding skirt 18 and the fixed skirt 3 by a spring. sliding skirt 27. It can therefore be seen that said means 8 are here and by way of non-limiting example those provided by the sealing device for a piston described in patent No. FR 3009037 belonging to the applicant.
• the inlet duct 47 is supplied with working fluid 23 at a pressure of ten bars, while the interior of the pump housing 49 is subjected to atmospheric pressure.
• This pressure difference makes it possible in particular to always maintain the hydraulic pistons with depressurized groove 1 pressed against the tilting plate 17, by means of an articulated shoe 16
• any groove made on the surface of the fixed skirt 3 and passing at the level of the said outlet of the cylinder 2 significantly increases the energy loss by friction generated at the interface of the said skirt 3 and of the said cylinder 2, at the level of the said cylinder. outlet.
• the hydraulic piston with depressurized groove 1 also avoids having to resort to an increased clearance between the fixed skirt 3 and the cylinder 2 to depressurize said skirt 3.
• a normal clearance between the fixed skirt 3 and the cylinder 2 can thus be preserved, so that the bearing surface of said skirt 3 on said cylinder 2 remains normally extended and that the pressure exerted on the film of working fluid 23 interposed between said skirt 3 and said cylinder 2 remains sufficiently low.
• the depressurized groove hydraulic piston 1 comprises a depressurized radial groove 9 which opens onto the surface of the fixed skirt 3. This is clearly visible in Figures 1 to 10,
• the depressurized radial groove 9 is axially positioned on the fixed skirt 3 so as to never be able to exit from the cylinder 2 whatever the axial position of said skirt 3 with respect to said cylinder 2. As positioned, the depressurized radial groove 9 does not occupy the place of any bearing surface whatsoever.
• the pressure distribution chamfer 50 allows the working fluid 23 coming from the fluid chamber 5 and passing between the extendable continuous segment 21 and the cylinder 2 to lubricate the outer surface of the fixed skirt 3 lying between said chamfer 50 and the depressurized radial groove 9. This occurs in particular during the phase of suction of the working fluid 23 in the fluid chamber 5 by the hydraulic piston with depressurized groove 1.
• FIG. 6 shows said suction phase. Note in said Figure 6 that the continuous extendable segment 21 is parked during said phase, as illustrated by the dotted arrows. Indeed, the pressure prevailing in the fluid chamber 5 is insufficient for the pressure difference between the internal cylindrical face of segment 22 and the external cylindrical face of segment 24 to significantly inflate said continuous segment 21.
• the spring basket 32 is perforated to better allow the working fluid 23 to circulate not only to communicate the pressure of the fluid chamber 5 to the internal cylindrical face of the segment. 22, but also to ensure the lubrication of the transmission means 7 which we have seen in Figure 1 that they are constituted, according to the non-limiting example of implementation of the hydraulic piston with depressurized groove 1 according to the invention taken here to illustrate its operation, articulated pads 16 cooperating with a tilting plate 17.
• FIG. 5 which gives an overview of the hydraulic piston with depressurized groove 1 according to the invention
• the working fluid 23 passes through the internal piston lubrication duct 15 to reach the articulated shoe 16 and lubricate the contact interface formed by the latter with the tilting plate 17.
• the hydraulic piston with depressurized groove 1 makes it possible, on the one hand, to ensure the correct operation of the sealing device for a piston which is the subject of patent FR 3 009 037 and on the other hand, to avoid any arrangement or arrangement of the fixed skirt 3 which is likely to increase the friction losses generated by said skirt 3 at the level of its contact with the outlet of the cylinder 2.
• the sealing means 8 from patent FR 3 009 037 have been given here only by way of example.
• the hydraulic piston with depressurized groove 1 according to the invention can produce its advantages for the benefit of other said means 8, the operation of which requires that the fixed skirt 3 is preferably leaky and non-sealed, while said skirt 3 remains subjected to forces. important radials.
• the depressurized groove hydraulic piston 1 can deliver all of its advantages if the sealing means 8 are cut segments 38 such as those shown in Figures 2 to 4.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Pistons, Piston Rings, And Cylinders (AREA)
• Details Of Reciprocating Pumps (AREA)
• Reciprocating Pumps (AREA)
• Sealing Devices (AREA)
• Hydraulic Motors (AREA)
• Actuator (AREA)

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Publications (1)

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Family Applications (1)

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Cited By (1)

Citations (8)

• 2020
  • 2020-03-30 FR FR2003152A patent/FR3108690B1/fr active Active
• 2021
  • 2021-03-18 WO PCT/FR2021/000028 patent/WO2021198572A1/fr active Application Filing
  • 2021-03-18 KR KR1020227034285A patent/KR20220160002A/ko unknown
  • 2021-03-18 JP JP2022559340A patent/JP2023519595A/ja active Pending
  • 2021-03-18 CN CN202180023447.9A patent/CN115315576A/zh active Pending
  • 2021-03-18 EP EP21718637.8A patent/EP4127452A1/fr active Pending
  • 2021-03-18 CA CA3171713A patent/CA3171713A1/fr active Pending
  • 2021-03-18 AU AU2021249497A patent/AU2021249497A1/en active Pending

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