Hydraulic percussion device

The invention relates to a hydraulic percussion device intended to be fitted on a base vehicle, the device comprising: a housing comprising a closing plate; a power cell mounted in the housing; and a damper connecting the power cell and the closing plate, the damper comprising a body rigidly connected to the power cell opposite the closing plate; a chamber provided inside the body; and a closing piston which is movable inside the chamber and capable of abutting against the closing plate in order to seal the chamber, the chamber being intended to contain a compressible fluid for damping the movements of the power cell in relation to the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. § 371 of PCT Application No. PCT/EP2016/062796, filed on Jun. 6, 2016, which claims priority to and the benefit of French Application No. 1555321 filed on Jun. 11, 2015, which are incorporated herein by reference in their entirety.

TECHNICAL DOMAIN

The present invention relates to the domain of construction machinery. It concerns a hydraulic percussion device of the “rock breaker” or similar type.

PRIOR ART

As described inFIGS. 1 and 2of the state of the art, hydraulic percussion devices100called “rock breakers” are generally composed of a body containing a power cell140and a housing150, which enables the power cell140to be protected from the abrasive rocks, as well as to mechanically support the assembly in order to be able to hook it onto one end of an arm12of a carrier machine11, for example a hydraulic excavator. The power cell140includes an impact piston180movable in a chamber so as to strike a tool19held in alignment with a lower end of the impact piston180.

The movements of the impact piston180are controlled by two′ opposing annular chambers370,380supplied alternately by fluid under pressure. The power cell140also includes a compression chamber220, containing a compressible gas, disposed above the impact piston180. When the device100is actuated, a first phase consists of moving the impact piston180in the compression chamber220by application of a pressure in the lower annular chamber380, thus compressing the gas in the compression chamber220. A second phase consists of canceling the effect of the pressure in the lower annular chamber380, by supplying the upper annular chamber370with the same pressure. The force then applied to the impact piston180depends on the difference in surface area between the annular chambers370,380and this difference in surface area is small. In a third phase, the compressible gas is expanded, and it violently moves the impact piston180downwards, impacting the tool19with sufficient force to break a rock.

Thus, the pressure of the gas in the compression chamber220is very high. In order to contain this pressure, an upper end of the power cell140is sealed by a cover240secured to the uprights of the power cell140by a series of screws310. This series of screws310, which are disposed annularly, is necessary to maintain a seal of the compression chamber220.

However, this solution is particularly complex to implement because of the high pressures on the cover240. Thus, the thickness of the uprights of the power cell140must therefore be oversized to accommodate the series of screws310. The screws310must be very long and of very high quality. The number of screws310required negatively impacts the weight of the hydraulic percussion device100as well as the time required to assemble the device.

Moreover, the arm12of the carrier machine11is movable so as to move the tool19against a surface S to be destroyed. To that end, the power cell140is mounted in a housing150which is attached to the arm12by a U-shaped attachment plate160. The attachment plate160can be disposed on the side of the housing150, or on a cover200of the housing150as illustrated inFIG. 2. The force of the arm12of the carrier machine11is transmitted to the tool19by bearing means260on the tool19secured in the power cell140;

When the hydraulic percussion device100strikes a surface S to be destroyed, it transmits a compression wave F onto this surface S in the direction of movement of the tool19. This wave F can induce a reflected shockwave R in the opposite direction of the wave F generated by the impact piston180. This reflected shockwave R is transmitted to the entire power cell140by the bearing means260of the tool19. To prevent transmitting said resultant shockwave R to the arm12of the carrier machine11, the power cell140is mounted in the housing150between two suspensions, an upper280and a lower281. The movements of the power cell140relative to the housing150are guided by guide means290disposed along the housing150.

This solution also has a disadvantage related to the upper and lower suspensions280,281. These elastic assemblies must withstand heat, oil and grease, thrust forces from the carrier machine11and the forces induced by the reflected wave R. These are wearing parts that are expensive and have a short working life. Furthermore, wedging must frequently be provided to obtain a specific pre-compression of the upper suspension280to keep the closing plate200closing the housing150.

An object of the invention is to find a solution enabling a power cell140to be installed in a housing150without having to use a complex and costly suspension.

DESCRIPTION OF THE INVENTION

The present invention seeks to resolve this technical problem by a suspension achieved by a closing piston that is movable in a chamber containing a compressible fluid.

To that end, the invention concerns a hydraulic percussion device intended to be installed on a carrier machine, the device comprising:a housing comprising a closing plate,a power cell mounted in the housing comprising an impact piston that is movable in translation, anda damper connecting the power cell and the closing plate in such a way as to transmit the displacement forces applied on the housing to the power cell, the damper comprising:a body rigidly connected to the power cell opposite the closing plate,a chamber provided inside the body, anda closing piston which is movable inside the chamber and capable of abutting against the closing plate in order to seal the chamber,the chamber being intended to contain a compressible fluid capable of damping the movements of the power cell relative to the housing.

Thus, the invention makes it possible to reproduce more simply the role of the cover and suspensions of the prior art by a closing piston that is movable in a chamber containing a compressible fluid. The power cell can thus be made lighter compared to devices of the prior art by reducing the thickness of the uprights of the power cell and eliminating the screws and cover. The damping of the movements of the power cell relative to the housing and of the housing relative to the power cell is also improved, which enables the lower suspension to be eliminated.

The device according to the invention can be integrated in various configurations.

According to a first embodiment, at least one portion of the impact piston is intended to penetrate into the chamber in such a way that, when the chamber contains a compressible fluid, the displacement of the impact piston inside the chamber is capable of compressing the compressible fluid, and the decompression of the compressible fluid is capable of displacing the impact piston. Thus, the damper also serves as actuator for the impact piston. This embodiment makes it possible to eliminate the closing cover of the power cell, thus simplifying and lightening the device.

According to a second embodiment, the power cell is connected to a pressure accumulator comprising a hydraulic circuit and a pneumatic circuit separated by a deformable membrane, the chamber is in pneumatic communication with the pneumatic circuit of the pressure accumulator so that the pressure contained in the hydraulic circuit is transmitted to the chamber by means of said membrane. In this case, the damper also plays the role of pressure accumulator, to withstand the hammer blows or the strong variations in pressure generated by the power cell. This embodiment also makes it possible to eliminate the closing cover of the power cell, thus simplifying and lightening the device.

According to a third embodiment, the power cell being sealed by a cover, the body comprising the chamber is mounted on said cover.

In this embodiment, the damper is hydraulically independent of the moving members of the impact piston. This embodiment makes it possible to limit the pressures on the cover of the actuating chamber.

According to one embodiment, the closing piston comprises:a body, intended to ensure the sealing of the chamber, anda head, intended to ensure that the closing piston is maintained against the closing plate. Advantageously, the body of the closing piston comprises a groove containing a gasket appropriate for the diameter of the chamber and for an expected pressure in the chamber. This embodiment makes it possible to ensure the sealing of the chamber of the damper.

Advantageously, in practice the chamber is intended to contain nitrogen in gaseous form. This embodiment makes it possible to respond effectively to the compression and expansion stresses of the compressible fluid.

According to one embodiment, the device comprises an element for rigidly attaching the housing to the closing plate, the attachment element being intended to attach the housing to a carrier machine. Alternatively, the attachment element is positioned on the housing in an area away from the closing plate.

DETAILED DESCRIPTION OF THE INVENTION

In the description, the hydraulic percussion device10a,10b,10cis described assuming that it is positioned in its most common configuration, namely vertically, i.e. with the tool19oriented vertically in contact with a surface to be destroyed, as illustrated inFIG. 1.

FIG. 3illustrates a hydraulic percussion device10acomprising a housing supporting a power cell14. The power cell14is substantially cylindrical or parallelepiped in shape, sealed by a cover32. The power cell14is mounted inside the housing15between a damper28, guide means29and a stop25. A U-shaped attachment plate16is disposed on the side of the housing15to attach the housing to the arm12of a carrier machine11. As a variant, as described inFIGS. 4 to 7, the attachment plate16can be disposed on the upper part of the housing15.

The housing15comprises a closing plate20aattached to the uprights surrounding the power cell14. The damper28is positioned between said closing plate20aand the cover32of the power cell14. Said damper28comprises a body27rigidly connected to the power cell14opposite the closing plate20a. By “rigidly connected,” it is understood that the body27is attached directly or indirectly to the power cell14. A chamber22is provided inside the body27, and a closing piston30is mounted movable in translation in the chamber22. The body27and the chamber22are preferably cylindrical. The closing piston30is dimensioned to ensure the seal of the chamber22. For example, as illustrated inFIG. 3, the closing piston30can comprise a body44and a head45that are cylindrical. The diameter of the body44is adapted to the diameter of the chamber22so as to ensure the seal of the chamber22. Preferably, the body44comprises a groove containing a gasket43suitable for the diameter of the chamber22.

The chamber22is intended to contain a compressible fluid, for example nitrogen in gaseous form. The head45of the closing piston30is pressed against the closing plate20awhen the chamber22is under pressure. The compressible fluid is intended to dampen the movements of the power cell14relative to the housing15, for example when a reflected shockwave is transmitted to the power cell14by the tool19. The compressible fluid can also dampen the movements of the housing15relative to the power cell14, for example when an abrupt movement of the tool19is controlled by the arm12of a carrier machine11.

In the first embodiment ofFIG. 3, the impact piston18contained in the power cell14is movable in an actuation chamber different from the chamber22of the damper28. In the second embodiment ofFIGS. 4 to 6, the actuation chamber of the impact piston18and the chamber22of the damper28are achieved by a single through-bore in the power cell14. The body23of the power cell14is combined with the body27of the damper28. From bottom to top, the body23of the power cell14contains a portion of the tool19, the impact piston18and a portion of the closing piston30. These two elements are movable in the chamber22and extend longitudinally along the same axis X.

The tool19comprises an upper end intended to receive impacts from the impact piston18. The shockwave is propagated along the body of the tool19down to the lower end intended to come in contact with the surface S to be destroyed. The body of the tool19is preferably cylindrical with a flattened surface in which two retainer keys17are disposed. The retainer keys17are connected to the power cell14in such a way as to limit the rotational and translational movements of the tool19. The retainer keys17also make it possible to maintain the tool19in the power cell14during movements of the hydraulic percussion device10band when the tool19is not in contact with a surface S to be destroyed. The arm12of a carrier machine11can also press down on the tool19. To do this, the arm12moves the housing15, thus causing a movement of the power cell14. Bearing means26on the tool19are also secured in the body23of the power cell14at a beveled surface of the tool19so as to transmit the movements of the power cell14to the tool19.

The impact piston18is movable in the body23of the power cell14by means of two opposing annular chambers37,38alternately supplied by fluid under pressure. The two chambers37,38are controlled by a hydraulic control device41. The power cell14also includes a compression chamber, containing a compressible gas, disposed above the impact piston18. The compression chamber is combined with the chamber22of the damper18. The same compressible gas, for example nitrogen, is used to carry out the function of the compression chamber and the function of the damper18.

When the hydraulic percussion device10bis actuated, a first phase consists of moving the impact piston18in the chamber22by injection of a pressure into the lower annular chamber38, thus compressing the gas in the chamber22. A second phase consists of canceling the effect of the pressure in the lower annular chamber38, by supplying the upper annular chamber37with the same pressure; thus, there is then nearly no force applied to the impact piston18by the annular chambers37,38. In a third phase, the compressible gas is expanded, and it violently moves the impact piston18downwards, impacting the tool19with sufficient force to break a rock.

The damper28comprises a body27combined with the body23of the power cell14and a closing piston30movable in translation in the body23. The closing piston30comprises a body44the diameter of which is adapted to the diameter of the chamber22. Said body44is provided with an annular groove in which a gasket43is inserted, ensuring the seal of the chamber22. The closing piston30comprises a head of one piece with the body44. The head45is intended to come into contact with a closing plate20b. The closing piston30thus makes it possible to effectively seal the chamber22and lock the power cell14in the housing15.

Preferably, the closing piston30is dimensioned in such a way that when the chamber22is under pressure, the pressure of the chamber22on the closing piston30is greater than the force of pressure of the arm12of the carrier machine11on the closing plate, irrespective of the position of the impact piston18.

In the example ofFIGS. 4 to 6, the closing plate20bis formed by the attachment plate16intended to be attached to the arm12of a carrier machine11. The housing15comprises an attachment plate21intended to cooperate with the attachment plate16to attach the hydraulic percussion device10bto the arm12of a carrier machine11. The attachment plate21of the housing15comprises a central recess in which the head45of the closing piston30penetrates in order to enter into contact with the attachment plate16.

To assemble the hydraulic percussion device10b, the tool19, the impact piston18and the closing piston30are inserted successively into the body23of the power cell14. After insertion of the tool19, the retaining keys17are inserted to restrict the rotational and translational movements of the tool19. The impact piston18is moved in the body23abutted against the tool19, so that the chambers37,38can control the movements of the impact piston18. The closing piston30is then inserted into the body23above the impact piston18. The attachment plate21of the housing15is attached to the attachment plate16intended to be attached to the arm12of a carrier machine11. Finally, the gas is then introduced into the chamber22through a fluid intake33, moving the closing piston30against the attachment plate16.

In the example ofFIG. 7, a hydraulic percussion device10ccomprises an upper chamber37to control the impact piston18, said chamber being disposed above the impact piston18in a pressure accumulator51. The pressure accumulator51comprises a pneumatic circuit53disposed above the upper chamber37. The pneumatic circuit53and the upper chamber37are connected by a deformable membrane52in such a way that the variations of pressure of the upper chamber37are absorbed by the pneumatic circuit53by means of the deformable member52. The damper28is disposed on the pressure accumulator51and the chamber22of the damper28is in pneumatic communication with the pneumatic circuit53of the pressure accumulator51by means of a channel54. Thus, the variations in pressure of the upper chamber37are absorbed both by the pneumatic circuit53and by the damper28.

It is clear from the foregoing that the hydraulic percussion devices10a,10b,10caccording to the invention have multiple advantages, particularly in terms of ease of assembly, compensation for manufacturing tolerances, and simplicity related to the elimination of the additional suspension device.