EP1691953B1 - Pressure regulating device for a percussive hydraulic apparatus - Google Patents

Abstract

The device has two parts (17, 18) mounted in a bore of the body, where the part (17) is immovable, and the part (18) is movable in the direction of the part (17) under the action of hydraulic fluid supply pressure. The movement of the part (18) causes deformation of a washer (19) for creating a passage on a drifting circuit which drifts a part of the fluid supply flow towards a hydraulic fluid retaining circuit to adjust inlet pressure.

Description

The present invention relates to a pressure regulating device for hydraulic percussion apparatus.

Hydraulic percussion devices, breaker type, such as the apparatus described in the document WO 00/78510 , are generally equipped with a striking piston driven by a resultant hydraulic forces which pushes it alternately in one direction then in the other, so as to hit a tool in contact with the material to be demolished.

The high power breakers are generally provided with a device for regulating the hydraulic fluid inlet pressure to a predetermined and adjustable value so as to obtain the desired performance.

Indeed, if the flow of hydraulic fluid passing through the apparatus is provided by the hydraulic circuit of the carrier, such as a hydraulic excavator, and depends on it alone, the hydraulic fluid supply pressure, also called pressure input, is determined at the time of the design of the device, to give the piston the desired impact energy.

For economic reasons, low power breakers are generally not equipped with a pressure regulating device.

These devices are often equipped with a nozzle or throttle on the hydraulic return circuit of the breaker, so that the pressure reaches the desired value, or are equipped with a pressure limiter which drifts towards the return circuit a part of the hydraulic fluid flow if the supply pressure exceeds the expected value.

These devices are not satisfactory because the breaker may operate with a flow rate or oil viscosity different from those expected, and cause internal damage to the striking mechanism.

The object of the invention is to provide a pressure regulating device which makes it possible to obtain an inlet pressure of the hydraulic fluid, preset at a certain value. This device must be a simple and economical device that can be applied in particular to low-power breakers and whose structure consists of a set of cylindrical parts fitted into the bore of the body of the breaker.

The device it concerns is of the type comprising a body inside which is formed a bore having several zones of different diameters, in which is mounted a piston having several zones of different diameters, the bore and the piston delimiting several chambers. connected to the hydraulic circuit, to ensure, under the action of a distributor, an alternating movement of the piston, which strikes a tool.

According to the essential characteristic of the invention, in the bore of the body and concentrically to the piston are mounted two axially offset parts and between which is disposed a deformable washer, one of the parts being stationary and the other part being slidably mounted in the bore, and movable towards the immovable part, under the action of the hydraulic fluid supply pressure, which is exerted on the face of the movable piece turned on the opposite side to the immovable part, this movement of the moving part causing a deformation of the spring washer to create a variable section passage on the return circuit of the hydraulic fluid to the reservoir, or a circuit which drifts to the return circuit a portion of the feed rate of the apparatus, so as to regulate the inlet pressure.

When the device is at rest, the elastic washer prohibits any passage with the return circuit of the fluid, and blocks the operation of the breaker. When the supply pressure of the hydraulic fluid is sufficient, the moving part moves, causing a deformation of the spring washer, to create a passage to the return circuit, which has the effect of adjusting the supply pressure to a minimum. limit value.

According to one embodiment of this device, in the immobile part is formed a channel, connected to the high-pressure supply channel of hydraulic fluid, directly or through an internal chamber, or, via the distributor, to a chamber partially delimited by the piston, alternately set at high and at low pressure, this channel opening into the face of the immobile part turned towards the moving part and on which the spring washer rests, while a channel connected to the circuit back to the reservoir opens into an annular volume located on the side of the spring washer opposite that bearing against the immovable part.

When the spring washer is at rest, the two channels opening into the central bore do not communicate. When deformation of the elastic washer, it creates a passage of variable section that ensures the communication of these two channels.

According to another characteristic of the invention, the moving part comprises, on the side of the immovable part, an annular recess delimiting a central nose intended to bear on the part of the elastic washer which is not resting against the part motionless.

According to one possibility, the spring washer has a section of generally rectangular shape, the lower face has, from the outside towards the inside, a bearing heel on the immovable part, and a parallel surface to the heel and recessed from the latter connected by an edge to an inclined surface from outside to inside and from the immovable part to the moving part.

The deformation of the elastic washer is done by tilting around the edge.

According to another possibility, the spring washer has a section of generally rectangular shape, and the portion located radially inwards, of the wall of the immovable part serving as a support for the spring washer, is inclined from the outside towards the inside and in the opposite direction to the moving part.

According to another characteristic of the invention, the stationary part comprises an outer annular flange whose internal diameter is slightly smaller than the outer diameter of the spring washer.

The elastically deformable washer may be made of steel, in particular spring steel.

If for simplicity, it is advantageous that the immovable part is distinct from the body, it is also possible that it is an integral part of the body.

• Figure 1 est une vue en coupe longitudinale d'un appareil hydraulique à percussion équipé d'un premier dispositif.
• Figure 2 est une vue partielle en coupe longitudinale et à échelle agrandie de la partie de l'appareil comportant ce premier dispositif.
• Figure 3 est une vue en coupe transversale et à échelle agrandie d'une rondelle élastique appartenant au dispositif de régulation représenté aux figures 1 et 2.
• Figures 4 à 6, sont trois vues partielles en coupe longitudinale, représentant le dispositif de régulation au cours de trois phases de fonctionnement.
• Figures 7 et 8 sont deux vues partielles en coupe, similaires à figures 4 à 6, représentant un dispositif de régulation équipé d'une autre rondelle, dans deux positions de fonctionnement.
• Figure 9 est une vue partielle en coupe, similaire à figure 7, représentant un autre dispositif, en position non alimentée de l'appareil.
• Figure 10 est une vue en coupe longitudinale, similaire à figure 2, d'un dispositif de régulation associé à un circuit qui dérive une partie du débit d'alimentation de l'appareil.
• Figure 11 est une vue en coupe longitudinale et à échelle agrandie de la partie de l'appareil comportant le dispositif.
• Figures 12 et 13 sont deux vues partielles montrant la position de la rondelle élastique assurant la régulation, respectivement lorsque l'appareil est non alimenté et en période d'alimentation de l'appareil.

In any case the invention will be better understood, with the aid of the description which follows, with reference to the attached schematic drawing showing, by way of non-limiting examples, several pressure regulating devices.

• Figure 1 is a longitudinal sectional view of a percussion hydraulic apparatus equipped with a first device.
• Figure 2 is a partial view in longitudinal section and on an enlarged scale of the part of the apparatus comprising this first device.
• Figure 3 is a cross-sectional view on an enlarged scale of a spring washer belonging to the control device shown in Figures 1 and 2.
• Figures 4 to 6 are three partial views in longitudinal section, showing the control device during three phases of operation.
• Figures 7 and 8 are two partial sectional views, similar to Figures 4 to 6, showing a regulating device equipped with another washer, in two operating positions.
• Figure 9 is a partial sectional view, similar to Figure 7, showing another device in the non-powered position of the apparatus.
• Figure 10 is a longitudinal sectional view, similar to Figure 2, of a control device associated with a circuit which derives a portion of the feed rate of the apparatus.
• Figure 11 is a longitudinal sectional view on an enlarged scale of the part of the apparatus comprising the device.
• Figures 12 and 13 are two partial views showing the position of the elastic washer providing regulation, respectively when the device is not powered and during the power supply of the device.

FIG. 1 very schematically represents a hydraulic percussion apparatus comprising a body 2 in which is formed a central bore 3 in which is mounted a striking piston 4 which is reciprocated, coming to strike the head of a tool 5. In the drawing, the supply of hydraulic fluid under high pressure is marked by the reference A, and the return to the tank is marked by the reference R. The high pressure supply, brings the fluid through a channel 6, which is connected to a hydraulic distributor 7, movement control. The channel 6 also feeds via a channel 8 a hydraulic accumulator 9, and a chamber 10 communicating with the accumulator 9 and located at the end of the body 2 opposite to that traversed by the tool. The conduit 6 also feeds through a channel 12, a chamber 13 for raising the striking piston. A chamber 14 is connected to the distributor 7.

In a manner known per se, the piston 4 has different shoulders along its length, at the different aforementioned chambers. In practice, when the upper chamber 14 is supplied with high pressure fluid by the distributor 7, the piston is propelled downwards for its striking stroke. In the other position of the distributor 7, the upper chamber 14 is connected by channels 15, 16 to the low pressure network R of the installation.

As shown in the drawing, and in particular in FIGS. 1 and 2, the bore 3 in which the piston 4 is housed contains a stationary annular piece 17, partly delimiting the chamber 14. Above the immobile part 17, is disposed a movable part 18, the other end of which delimits part of the chamber 10. The low pressure circuit formed by the channels 15, 16 passes through the two parts 17, 18 which are mounted concentrically to the piston.

Between the two immovable parts 17 and mobile 18 is mounted an elastic washer 19. In the embodiment shown in Figures 1 to 6, the washer 19 is delimited by three perpendicular faces, and a fourth lower face, comprising, of the outside inward, a heel 20, a surface parallel to the heel 20 connected by an edge 22 to an inclined surface 23, in the embodiment shown in the drawing, from bottom to top and from outside to inside .

The elastic washer 19 may be made of different materials, and in particular steel. As shown in Figures 2 to 6, the channel 15 from the distributor 17, is extended by a channel section 24 inside the immovable part 17, and opens into the wall of this part facing upwards, in the zone of the latter between the heel 20 and the edge 22. The return to the reservoir through the channel 16 is above the elastic washer 19, at a recess 25 that includes the movable part 18. device is not supplied with hydraulic fluid under pressure, the parts occupy the position shown in detail in Figures 2 and 4. In this case, the spring washer 19 is flat, it is supported by its heel 20 on the immovable part 17 and the moving part 18 bears on its upper face, so that there is no communication between the channel 15 and the channel 16 back to the tank.

When the apparatus is put into operation, the hydraulic pressure will increase in the accumulator 9 and the chamber 10, tending to move the moving part 18 towards the immobile part 17. When the pressure increases but has not reached a maximum of predetermined value, the washer 19 is deformed, as shown in Figure 5, but not ensuring communication between the channels 15 and 16. When the hydraulic fluid pressure increases, the elastic washer 19 is deformed more and more, under the increasing force of the high pressure exerted on the moving part 18, which locally bears on the upper face of the washer, the position of this support being shifted inwards relative to the position of the heel 20 and the edge 22. This offset support generates an elastic deformation of the shape of the washer 19. The edge 22 bearing against the workpiece 17, as shown in Figure 6, a hydraulic passage 26 is provided between the channels 15 and 16. The evacuation of the apparatus is then released and the breaker can begin to operate normally. The starting pressure is determined by this first level of deformation of the washer. When the pressure increases further, the lifting height of the heel 20 with respect to the immobile part 17 forms a variable throttle 26, the size of which depends on the deformation of the elastic washer 19, therefore on the value of the hydraulic high pressure of the apparatus. During the entire normal operating phase of the percussion apparatus, the pressure drop on the evacuation circuit 15, 16, created by the variable throttle 26 depends on the high pressure, and consequently makes it possible to regulate this pressure at a calculated value.

The geometry of the washer is designed to deform a known value, so as to obtain a hydraulic passage section through the passage 26, corresponding to the pressure drop on the evacuation circuit, necessary to obtain the desired high pressure value.

FIGS. 7 and 8 show an alternative embodiment, in which the elastic washer 19 has no inclined surface 23, this inclined surface being replaced by a slope 27 formed on the end face of the immobile part 17, this slope being tilted from top to bottom and from the outside to the inside. Figure 7 shows the washer when the device is not powered, while Figure 8 shows the device during operation, with care of a hydraulic passage 26 of variable section. In this case, the deformation of the washer is done with support of it on the slope 27.

FIG. 9 represents another embodiment, in which the washer 19 has a rectangular section, the bearing surface 28 of the washer on the immobile part 17, being raised relative to the preceding case, the starting pressure being able to be determined by the value of the clearance between this surface 28 of the support plane of the washer, and the upper end of the slope 27. The operation of the apparatus can be done only when the supply pressure has reached a value sufficient for the deformation of the washer 19 allows the support thereof on the slope 27, after having cleared the bearing surface 28 on the immovable part 17.

Figures 10 to 13 show another embodiment in which the same elements are designated by the same references as before. In this embodiment, the elastic washer 19 is intended to create a variable throttle on a circuit which drifts directly to the return circuit R a portion of the feed rate of the apparatus.

In this case, the channel 15 from the distributor 7 is connected directly to the conduit 16 of low pressure return to the tank. A channel 29, connected to the piston raising chamber 13, opens into the channel 24 formed in the immobile part 17. As an alternative, the channel 24 could be powered directly from the high pressure supply, this is from the channel 6. The channel 24 could also, for a similar result, be connected to the upper chamber 14, then being alternately connected to the low pressure and then to the supply pressure, depending on the position of the distributor 7. In this arrangement, the upper chamber 14 is constantly isolated from the channel 24 and the outlet channel 16, by the washer 19. As shown in particular in Figures 12 and 13, the stationary part 17 comprises a rim 30 enveloping partially the outer diameter of the washer. In the embodiment shown in the drawings, the washer simply has, on its underside, and on the inside, an inclined face 32. At startup, when the supply pressure increases and acts on the moving part 18, the washer 19 deforms gradually, then, when the desired pressure is reached, the deformation of the washer 19 is such that the flange 30 is no longer sealed to the outside diameter of the washer and creates a throttling 26 of variable section, as shown in FIG. 13. This throttling 26 causes a hydraulic flow between the channel 24, and the return channel 16. Part of the flow that would normally go through the striking mechanism, is then diverted directly to the return R. This has to effect of reducing and regulating the supply pressure to a predetermined limit value.

As is apparent from the above, the invention provides a great improvement to the existing technique, providing a pressure regulating device, simple structure, and a very efficient operation, which is particularly interesting for the equipment of hydraulic percussion apparatus to be realized under economic conditions, and whose structure consists of cylindrical pieces nested in the bore of the body.

As goes without saying the invention is not limited to the embodiments of this device described above as examples, it encompasses all variants. Thus, in particular, the shape of the elastic washer could be different or that the immovable part 17 could be an integral part of the body, without departing from the scope of the invention.

Claims (8)

1. Pressure-regulating device for a hydraulic percussion apparatus, comprising a body (2) in the interior of which is arranged a cylinder bore (3) having a plurality of zones of different diameters, in which cylinder (3) bore is mounted a piston (4) having a plurality of zones of different diameters, the cylinder bore (3) and the piston (4) delimiting a plurality of chambers connected to the hydraulic circuit, in order to ensure an alternating movement of the piston according to the action of a distributor, said piston striking a tool, characterised in that two parts (17, 18) offset axially from one another are mounted in the cylinder bore (3) of the body concentrically with the piston, between which parts (17, 18) is arranged a deformable ring (19), one (17) of the parts being fixed and the other part (18) being mounted slidingly in the cylinder bore and being displaceable in the direction of the fixed part under the influence of the hydraulic fluid supply pressure which is exerted on the face of the movable part (18) oriented away from the fixed part (17), this displacement of the movable part (18) causing a deformation of the elastic ring (19) in order to create a passage (26) of variable section in the return circuit (15) of the hydraulic fluid to the reservoir, or in a circuit (29) which diverts a portion of the supply delivery of the apparatus to the return circuit, so as to regulate the inlet pressure.
2. Device according to Claim 1, characterised in that there is formed in the fixed part (17) a passage (24) connected to the high-pressure hydraulic fluid supply passage, directly or via an internal chamber or, by way of the distributor, to a chamber partially delimited by the piston and subjected alternately to high and low pressure, said passage opening in the face of the fixed part (17) oriented towards the movable part (18), on which face the elastic ring (19) rests, while a passage (16) connected to the return circuit (12) to the reservoir opens into an annular volume located on the side of the elastic ring (19) opposite the side which bears against the fixed part (17).
3. Device according to either of claims 1 and 2, characterised in that the movable part (18) has an annular recess (25) oriented towards the fixed part and delimiting a central projection designed to bear against the part of the elastic ring (19) which is not in abutment against the fixed part (17).
4. Device according to any one of claims 1 to 3, characterised in that the elastic ring (19) has a section of generally rectangular shape, the lower face of which includes, from the outside towards the inside, a shoulder (20) for resting on the fixed part (17) and a surface parallel to the shoulder and offset therefrom, which is connected by an edge (22) to a surface (23) inclined from the outside towards the inside and from the fixed part (18) towards the movable part (17).
5. Device according to any one of claims 1 to 3, characterised in that the elastic ring (19) has a section of generally rectangular shape, and the portion (27), located radially inwards, of the wall of the fixed part (17) which serves to support the elastic ring (19) is inclined from the outside towards the inside and in a direction away from the movable part.
6. Device according to any one of claims 1 to 5, characterised in that the fixed part (17) has an outer annular rim (30) the internal diameter of which is slightly smaller than the external diameter of the elastic ring (19).
7. Device according to any one of claims 1 to 6, characterised in that the elastic ring (19), is made of steel, in particular of spring steel.
8. Device according to any one of claims 1 to 7, characterised in that the fixed part (17) forms an integral part of the body (2).

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