EP0070246B1 - Hydraulic percussion device - Google Patents

Abstract

1. A percussion apparatus moved by a pressurised fluid, of the type comprising a mobile striking mass (2) in the form of a piston supplying a series of impacts on a tool (3), this piston being slidably mounted in a cylinder (4) which, provided in the body (5) of the apparatus and including ports (6, 7) connected by ducts (8, 9), serves additionally in the sliding of a distributor (10) connecting the chamber (11) situated above the piston alternately to a high pressure circuit (12), for enabling the piston to descend rapidly, and to a low pressure circuit (13) for effecting the return strocke of this piston, characterised in that it comprises, on the one hand, a non-return valve (22) enabling fluid to pass from the chamber (11) located above the strike piston towards the high pressure circuit (12) and, on the other hand, means ensuring that the distributor (10) is displaced sequentially in such a way that, starting from a position in which the chamber (11) located above the piston is connected to the high pressure (12), the distributor is displaced very rapidly as far as a position in which it interrupts the connection between the said chamber and the high pressure, then at a lower, controlled speed, so as to delay the connecting of the chamber (11) to the low pressure circuit (13), so as to enable the maximum amount of restorative energy to be recovered for the entire duration of the isolation of the chamber located above the piston with respect to the high pressure and low pressure circuits, by compressing the fluid isolated in the chamber for the passage of the latter into the high pressure circuit by means of the non-return valve.

Description

The present invention relates to a percussion device driven by a pressurized fluid such as an incompressible hydraulic fluid.

This device provides, by means of a striking striking mass in the form of a piston, a succession of percussions on a tool. The piston is slidably mounted in a cylinder which, formed in the body of the device and comprising lights, connected by channels, is also used for the sliding of a distributor putting the chamber located above the piston in alternative communication with the high pressure circuit to allow rapid descent of the piston and with a low pressure circuit to allow the return stroke of this piston.

In this embodiment, the distributor is pushed by a spring in the direction of the tool, in accordance with the subject of French patent No 1431835.

However, this device could come in different forms, the dispenser can for example be moved not by the spring, but by pushers driven by hydraulic pressure, in accordance with certificate of addition No 2045289 to French patent No 1431835, or be moved by a central plunger with two opposite rods in accordance with French patent FR-A No 2369908.

The operation of this type of device, whatever the actuation mode of the distributor, proceeds from a basic technique making it possible to put the chamber situated above the piston alternately in relation to the high and the low pressure, a annular section of small surface and antagonistic being constantly maintained at high pressure, so that the resultant of hydraulic forces is oriented alternately in one direction and in the other.

The study of the operation of this device shows that the kinetic energy, stored in the striking piston launched at high speed, transforms, upon impact on the tool, into a compression wave, which will travel l tool at the speed of sound in metal, then transform on contact with the rock into a force likely to fracture it. In fact, only a fraction of this energy is absorbed by the rock, the balance being returned to the tool in the form of a compression wave which returns to the device.

This return compression wave is usually dissipated either in the body of the device via the flange of the tool, or returned to the piston in the form of kinetic energy. In this case, the piston rebounds and pushes the fluid towards the low pressure circuit in the form of a hydraulic pressure wave usually called water hammer in hydraulic installations.

In these cases, not only is this return energy irretrievably lost, but it also induces stresses harmful to the good performance of the equipment, and in particular the rapid wear of the contact flanges between the tool and the body of the device. , the fatigue of the low pressure hose or the heating due to the dissipation of the energy of the return wave.

In addition, it should be noted that, since the compression wave back in the tool is restored to the piston in the form of kinetic energy, the piston is assisted in its return stroke, and the operating parameters are modified in the direction of a decrease in high pressure in proportion to the hardness of the rock, this pressure decrease being detrimental to the efficiency of the device.

The object of the invention is to allow the recovery of the energy contained in the compression wave back in the tool, in order to reuse it later.

To this end, the apparatus which it relates comprises, on the one hand, a non-return valve allowing the passage of fluid from the chamber located above the striking piston towards the high pressure circuit and, on the other hand, means ensuring a sequential movement of the distributor, so that, starting from a position in which the chamber located above the piston is in communication with the high pressure, the distributor moves very quickly to a position in which it cuts the communication between said chamber and the high pressure, then at reduced and controlled speed, so as to delay the communication of the chamber with the low pressure network, in order to allow, throughout the isolation time of the chamber located above the piston vis-à-vis the high pressure and low pressure networks, the maximum recovery of the energy of restitution, by compression of the fluid isolated in the chamber and passage of this latter in the high pressure network by the non-return valve.

• - une moindre usure de la collerette d'appui de l'outil;
• - une meilleure tenue des flexibles basse pression puisque les coups de bélier à ce niveau sont supprimés;
• - pour un débit donné, une augmentation de la fréquence des impacts puisque l'on peut disposer de tout le fluide récupéré en plus du fluide fourni à l'appareil; cette augmentation de fréquence équivaut au raccourcissement de la durée de chaque cycle, et entraîne une modification des paramètres de fonctionnement en sens inverse du sens précédent, c'est-à-dire dans le sens d'une augmentation de la haute pression, donc de l'efficacité de chaque impact proportionnellement à la dureté du rocher;
• - une diminution de l'échauffement habituellement dû à la dissipation de l'énergie de l'onde de retour, ce qui est favorable à la bonne tenue dans le temps des organes de l'appareil;
• - cette amélioration des conditions de fonctionnement permet également une diminution de l'amplitude de recul et des vibrations que doit encaisser le bras-support de l'appareil.

This arrangement has numerous and important advantages, namely:

• - less wear of the tool support flange;
• - better resistance of the low pressure hoses since water hammer at this level is eliminated;
• - for a given flow, an increase in the frequency of impacts since it is possible to have all the recovered fluid in addition to the fluid supplied to the device; this increase in frequency is equivalent to shortening the duration of each cycle, and causes a modification of the operating parameters in the opposite direction to the previous direction, that is to say in the direction of an increase in the high pressure, therefore the effectiveness of each impact in proportion to the hardness of the rock;
• - A reduction in heating usually due to the dissipation of the energy of the return wave, which is favorable to the good resistance over time of the organs of the apparatus;
• - This improvement in operating conditions also allows a reduction in the amplitude of recoil and the vibrations that the support arm of the device must receive.

Advantageously, the traveling time of the striker district between the closure of the communication between the chamber situated above the piston and the high pressure network and the communication of this same chamber with the low pressure network is equal to the time necessary for the most important restitution known according to the hardest rocks.

This feature allows maximum energy recovery, regardless of the nature of the material to be broken with this percussion device.

In accordance with another preferred characteristic of the invention, the distributor undergoes a new acceleration movement as soon as the chamber located above the piston is in communication with the low pressure network, so as to largely release this opening and to allow a free movement of the moving striking mass.

According to one embodiment of the invention, the distributor comprises two parts of different sections, namely a part located on the side of the piston, of section corresponding to the section of the cylinder in which the striking piston is slidably mounted, and a part of larger section located on the side opposite to the piston, this part of larger section being mounted in a cavity which, extending the cylinder, is of section greater than that of the part of large section of the distributor, this part of large section of dispenser can enter a chamber of the same section as it, disposed between the cylinder and the enlarged cavity, the beginning of penetration into this chamber being made when the dispenser arrives in a position in which it closes the communication between the chamber located at above the piston and the high pressure network, the annular volume delimited by the chamber of intermediate section and by the connection between the two sections of the distributor communicating with the chamber located above the piston by at least one calibrated leak orifice.

When the entire large section or flange of the distributor is in the cavity above the cylinder, the distributor is not braked and moves quickly towards the piston.

When the crown corresponding to the connection of the two sections of the distributor closes the annular chamber, there occurs, inside the latter, a compression of the fluid which it contains, resulting in a brutal braking of the movement of the distributor. From this moment, the movement of the distributor can only continue by escaping fluid through the calibrated orifice. It is therefore on the section of the latter that the speed of movement of the distributor depends between the position in which it ensures the separation between the chamber located above the piston and the high pressure network and that where it puts the latter into communication. with the low pressure network.

According to a first possibility, the calibrated orifice allowing the escape of fluid from the annular chamber is formed in the wall externally limiting the latter.

According to another possibility, a channel is formed axially in the distributor, the end of which opens into the crown connecting the zones of different sections of the distributor forms the calibrated orifice ensuring the escape of fluid from the annular chamber.

• Les fig. 1 à 5 sont cinq vues en coupe longitudinale d'une première forme d'exécution de cet appareil au cours de cinq phases de fonctionnement;
• la fig. 6 est une vue partielle en coupe selon la ligne 6-6 de la fig. 1 de la cavité dans laquelle est montée la partie supérieure du distributeur;
• la fig. 7 est une vue en coupe d'une variante de la cavité de la fig. 6;
• la fig. 8 est une vue partielle de cet appareil représentant, en coupe, une variante du dispositif d'échappement du fluide hors de la chambre annulaire;
• les fig. 9, 10 et 11 sont des vues partielles de cet appareil représentant, en coupe, trois formes d'exécution du clapet antiretour situé entre la chambre haute du piston de frappe et le réseau haute pression;
• la fig. 12 est une vue en coupe longitudinale d'une variante d'exécution de l'appareil des fig. 1 à 5;
• la fig. 1 3 est une vue représentant un diagramme de déplacement du distributeur en fonction du temps;
• les fig. 14 et 15 sont deux vues en coupe longitudinale et à échelle agrandie de la partie contenant le distributeur de l'appareil des fig. 1 à 5, au cours de deux phases de fonctionnement;
• les fig. 16 et 17 sont deux vues en coupe longitudinale et à échelle agrandie de la partie contenant le distributeur de l'appareil de la fig. 8 au cours de deux phases de fonctionnement.

In any case, the invention will be clearly understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting examples, several embodiments of an apparatus according to the invention.

• Figs. 1 to 5 are five views in longitudinal section of a first embodiment of this device during five operating phases;
• fig. 6 is a partial sectional view along line 6-6 of FIG. 1 of the cavity in which the upper part of the distributor is mounted;
• fig. 7 is a sectional view of a variant of the cavity of FIG. 6;
• fig. 8 is a partial view of this device representing, in section, a variant of the fluid exhaust device outside the annular chamber;
• fig. 9, 10 and 11 are partial views of this device representing, in section, three embodiments of the non-return valve located between the upper chamber of the striking piston and the high pressure network;
• fig. 12 is a view in longitudinal section of an alternative embodiment of the apparatus of FIGS. 1 to 5;
• fig. 1 3 is a view showing a movement diagram of the dispenser as a function of time;
• fig. 14 and 15 are two views in longitudinal section and on an enlarged scale of the part containing the distributor of the apparatus of FIGS. 1 to 5, during two operating phases;
• fig. 16 and 17 are two views in longitudinal section and on an enlarged scale of the part containing the distributor of the apparatus of FIG. 8 during two operating phases.

The distributor 10 comprises two parts of different sections, namely a lower part 16 of diameter corresponding to that of the cylinder 4 in which the striking piston 2 moves, engaged in the upper end of this cylinder, and an upper part 17 of larger section. This part 17 is housed in a cavity 18 of section substantially greater than its own.

In the embodiment shown in FIG. 6, the increase in section of the cavity 18 relative to that of the dispenser 17 is obtained by providing a lateral recess in the form of a half-moon, while in FIG. 7, the cavity 18 comprises two diametrically opposite recesses, each in the shape of a half-moon.

Part 17 of the dispenser can, however, enter a chamber 19 of section corresponding to its own, the chamber 19 extending the cylinder 4. The dimensions of the chamber 19 and the enlarged part 17 or collar of the distributor are such that the distributor ensures the closure of the passage between the high pressure 12 and the chamber 11 situated above the piston when the collar 17 arrives at the level of chamber 19 and comes close it.

Communication between the annular chamber 19 and the cavity 18 is no longer ensured except through a calibrated orifice 20.

Between the cavity 18 placed in communication with the chamber 11 by the movement of the distributor and the high pressure network 12 is provided a non-return valve designated by the general reference 22, the description of which will be given below. The non-return valve 22 aims to allow the passage of pressurized fluid from the chamber 11 to the high pressure network 12.

• Dans un premier temps, comme montré à la fig. 1, le distributeur 10 se déplace très rapidement de la position dans laquelle l'admission haute pression se produit, vers une position de fermeture de la haute pression correspondant à la fig. 2. Cette phase correspond au déplacement (d0, d1) pendant la période (t0, t1 ) du diagramme de la fig. 13. Ce déplacement rapide est rendu possible du fait que les deux faces de la collerette 17 du distributeur sont maintenues en relation hydraulique par de larges canaux au niveau de la cavité 18. Lorsque la couronne 23 de raccordement des zones de sections différentes du distributeur arrive au niveau de la chambre 19 et vient obturer celle-ci, un certain volume de fluide est comprimé dans ladite chambre, la poursuite du mouvement de déplacement du distributeur ne pouvant être obtenue que par échappement du fluide par l'orifice calibré 20. Par l'ajustement de la section de l'orifice 20, il est possible de contrôler le temps de déplacement du distributeur entre la position qu'il occupe à la fig. 2 et la position qu'il occupe à la fig.4, ces deux positions correspondant, respectivement, à la fermeture de la haute pression et à l'ouverture du réseau basse pression 13.

The operation of this device is as follows:

• At first, as shown in fig. 1, the distributor 10 moves very quickly from the position in which the high pressure intake occurs, to a closed position of the high pressure corresponding to FIG. 2. This phase corresponds to the displacement (d0, d1) during the period (t0, t1) of the diagram in fig. 13. This rapid movement is made possible by the fact that the two faces of the collar 17 of the distributor are maintained in hydraulic relation by wide channels at the level of the cavity 18. When the ring 23 for connecting zones of different sections of the distributor arrives at the level of the chamber 19 and comes to close off the latter, a certain volume of fluid is compressed in the said chamber, the continuation of the movement of movement of the distributor can only be obtained by escaping the fluid through the calibrated orifice 20. By l 'adjustment of the section of the orifice 20, it is possible to control the time of movement of the distributor between the position it occupies in fig. 2 and the position which it occupies in FIG. 4, these two positions corresponding, respectively, to the closing of the high pressure and to the opening of the low pressure network 13.

This travel time during which the chamber 11 will be isolated from both the high pressure 12 and low pressure networks 13 will allow, as shown in FIG. 3, the maximum recovery of the energy of restitution by passage of the compressed fluid by the striking piston 2 from the chamber 11 towards the high pressure network, and more precisely towards the accumulator 24 thereof via the valve. non-return 22. This phase corresponds to the displacement (d1, d2) of the distributor during the period (t1, t2) of the diagram in FIG. 13.

The recovery of restoring energy having been completed, the distributor continues its downward movement to the position shown in FIG. 5. The chamber 11, located above the piston, is gradually brought into contact with the low pressure circuit by the channels 7, 9, allowing the return stroke of the striking piston 2, ensuring the emptying of the fluid contained in this bedroom. This phase results in the displacement (d2, d3) of the distributor, shown in the diagram in FIG. 13.

Fig. 8 shows a variant of the exhaust of the annular chamber 19. In this case, a channel 25 is formed axially in the distributor which opens into the crown 23 connecting its zones of different sections. The function of escaping the fluid through the channel 25 is exactly the same as through the calibrated orifice 20.

According to a first possibility shown in FIGS. 1 to 5 and 8, the non-return valve 22 is returned to its seat, thanks to a central chamber 26 located under the head of the valve, which is connected by a channel 29 to the low pressure network.

In the embodiment shown in FIG. 9, the non-return valve 22 is returned to its seat, thanks to an annular chamber 27 which, resulting from the difference between two diameters 28a and 28b, is connected by a channel 29 to the low pressure network.

In the embodiment shown in FIG. 10, the valve 22 is held in the closed position by the vacuum existing between the high pressure network 12 and the chamber 11 as soon as the direction of circulation of the fluid tends to reverse, because the valve lift is limited by a stop 30 to a reduced game J.

In the embodiment shown in FIG. 11, the valve 22 is returned to the closed position by a spring 32 bearing, on the one hand, on the valve and, on the other hand, on a stop 33 located on the side of the high pressure network.

Fig. 12 of the drawing shows an alternative embodiment of the apparatus of FIGS. 1 to 5, in which the distributor 10 is no longer subjected to the action of a spring 14, but to the action of a central plunger 34 with two opposite rods. In this case, it is not possible to provide the valve return device shown in FIG. 8, any of those shown in FIGS. 9 to 11 can be considered.

In the embodiment shown in Figs. 14 and 15, the distributor 10 has a groove 35 formed between the cylindrical parts 16 and 17. In the body of the cylinder 4 is also formed at least one channel 36 which is broadly dimensioned and which, opening into the cavity in which the cylindrical part 16 slides , communicates with the cavity 18. The channel 36 is also positioned so as to put the annular volume formed by the groove 35 into communication with the low pressure network, as soon as the position of the distributor 10 ensures the communication of the chamber 11 with the low pressure network. This allows a further acceleration of the movement of the dispenser.

In the embodiment shown in Figs. 16 and 17, the fluid escaping from the chamber 18 is produced by a channel 25, as in the case shown in FIG. 8. A groove 37 is formed at the periphery of the chamber 19, and a channel 38 is formed in the distributor, capable of placing the chamber 19 in broad communication with the low pressure network, as soon as the position of the distributor 10 ensures the setting in communication of chamber 11 with the low pressure network.

As is apparent from the above, the invention brings a great improvement to the existing technique by providing a percussion device whose structure is not more complex than that of traditional devices, and which has much higher performance and reliability. to those of the latter.

Claims (8)

1. A percussion apparatus moved by a pressurised fluid, of the type comprising a mobile striking mass (2) in the form of a piston supplying a series of impacts on a tool (3), this piston being slidably mounted in a cylinder (4) which, provided in the body (5) of the apparatus and including ports (6, 7) connected by ducts (8, 9), serves additionally in the sliding of a distributor (10) connecting the chamber (11) situated above the piston alternately to a high pressure circuit (12), for enabling the piston to descend rapidly, and to a low pressure circuit (13) for effecting the return strocke of this piston, characterised in that it comprises, on the one hand, a non-return valve (22) enabling fluid to pass from the chamber (11) located above the strike piston towards the high pressure circuit (12) and, on the other hand, means ensuring that the distributor (10) is displaced sequentially in such a way that, starting from a position in which the chamber (11) located above the piston is connected to the high pressure (12), the distributor is displaced very rapidly as far as a position in which it interrupts the connection between the said chamber and the high pressure, then at a lower, controlled speed, so as to delay the connecting of the chamber (11) to the low pressure circuit (13), so as to enable the maximum amount of restorative energy to be recovered for the entire duration of the isolation of the chamber located above the piston with respect to the high pressure and low pressure circuits, by compressing the fluid isolated in the chamber for the passage of the latter into the high pressure circuit by means of the non-return valve.

2. A percussion apparatus as claimed in Claim 1, characterised in that the time for displacing the distributor (10) between the closure of the connection between the chamber (11) located above the piston and the high pressure circuit (12), and the connecting of this chamber (11) to the low pressure circuit (13), equals the time necessary for the greatest known rebound as a function of the hardest rocks.

3. A percussion apparatus as claimed in any one of Claims 1 or 2, characterised in that the distributor (10) undergoes a further acceleration movement as soon as the chamber (11) located above the piston is connected to the low pressure circuit (13) so as to disengage this aperture to a large extent and to enable mobile striking mass (2) to move freely.

4. A percussion apparatus as claimed in any one of Claims 1 to 3, characterised in that the distributor (10) comprises two parts having different sections, i.e. a part (16) located on the piston side, having a section corresponding to the section of the cylinder (4) in which the strike piston (2) is slidably mounted, and a part (17) of larger section located on the side opposite the piston, this part of larger section being mounted in a cavity (18) which, extending the cylinder, has a larger section than that of the large section part (17) of the distributor, this large section part of the distributor being able to penetrate into a chamber (19) having the same section as itself, arranged between the cylinder (4) and the enlarged cavity (19), penetration into this chamber (19) beginning when the distributor (10) arrives in a position in which it closes the connection between the chamber (11) located above the piston and the high pressure circuit (12), the annular volume delimited by the chamber (19) having an intermediate section and by the connection between the two sections of the distributor, being connected by at least one passage (20) to the chamber (11) located above the piston.

5. A percussion apparatus as claimed in Claim 4, characterised in that the passage (20) enabling fluid to escape from the annular chamber (19) is provided in the wall limiting the latter externally.

6. A percussion apparatus as claimed in all of Claims 3 to 5, characterised in that the distributor (10) has a groove (35) provided between the two cylindrical parts (16) and (17) having different sections, and in that at least one duct (36) opens into the cylinder (4), capable of connecting the annular volume delimited by the groove (35) to the low pressure circuit, as soon as the position of the distributor (10) ensures that the chamber (11) located above the piston is connected to the low pressure circuit.

7. A percussion apparatus as claimed in Claim 4, characterised in that a duct (25) is provided axially in the distributor (10), the end of which, opening into the collar (23) connecting the areas of the distributor with different sections, forms the calibrated aperture ensuring that fluid escapes from the annular chamber.

8. A percussion apparatus as claimed in all of Claims 3, 4 and 7, characterised in that the chamber (19), in which the fluid is compressed during the movement of the distributor, has a peripheral groove (37) which can be connected to the low pressure circuit by a duct (38) provided in the distributor, as soon as the position of the latter ensures that the chamber (11) located above the piston is connected to the low pressure circuit.

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