MXPA96001691A - Procedure and apparatus for the regulation of the hitching race of a percussionmovido device by an incompressible fluid - Google Patents

Abstract

The present invention relates to a device for altering the striking stroke of a percussion machine moved by a pressurized fluid, characterized in that it comprises: a piston located movably in a cylinder and defining an upper chamber and a lower chamber; stroke selector piston to vary the stroke of the piston, a distributor in communication with the upper chamber, the lower chamber and the stroke selector piston, the stroke selector piston is located in the cylinder and has a face clamping fluid pressure , the stroke selector piston has a groove that communicates with the distributor and can be placed in communication with the bottom chamber when the piston approaches the upper chamber.

Description

Procedure and apparatus for regulating the striking stroke of a percussion device moved by an incompressible fluid under pressure The subject of the present invention is a method for automatically regulating the stroke of the striking piston of a percussion apparatus moved by a pressurized incompressible fluid and an apparatus for the application of this method. The percussion devices moved by means of an incompressible fluid under pressure are fed with fluid, in such a way that the resulting hydraulic forces are successively applied on the striking piston, displacing it alternately in one direction and then in the other. In apparatuses of this type, the piston moves alternatively to the interior of an inner diameter or cylinder, in which a chamber is provided on top of the piston, which, delimited by part thereof, is conventionally called: high chamber. When this chamber is supplied with fluid under pressure, the hydraulic force, which is created, allows the piston to describe its striking stroke. At the other end of the inner diameter, in which the piston moves, a second chamber is provided, also delimited on one side by the piston, conventionally called: lower chamber.

The force resulting from the fluid pressure in the lower chamber ensures the displacement of the piston for its return stroke. The overall power of an apparatus is expressed by the product of the value of the striking frequency and the value of the energy per stroke. It is known that, for a given global power, it is preferable to particularize the energy per stroke in relation to the hitting frequency, when the tool of the apparatus encounters a hard terrain, while it is preferable to particularize the hitting frequency in relation to the energy per hit when the tool finds a soft spot. The energy per stroke is the kinetic energy given to the piston, which depends on the stroke of stroke and the feed pressure. To adjust the striking frequency and the energy per stroke appropriate to the hardness of a given terrain, two known solutions are described in the patents EP 0 214 064 and 0 256 955 in the name of the applicant. The patent EP 0 214 064 describes an apparatus that allows to obtain an automatic adaptation of the percussion parameters, thanks to the presence in the cylinder of the apparatus of a channel fed of fluid according to the position of the piston after the impact and the eventual rebound of the piston on the tool. Patent EP 0 256 955 describes an apparatus that allows obtaining the same result, depending on the pressure variations in the upper chamber or the lower chamber, consecutive to the effect of the rebound of the piston on the tool, thanks to the presence of an element hydraulic sensitive to these variations. It is, in fact, in both cases, systems that work well, adapted to high power devices, but which are very expensive and require a large number of circuits, which makes them little compatible for small and medium-sized devices. medium power, such as those used for drilling or demolition. The object of the invention is to provide a method and an apparatus for its application, which allows an automatic adaptation of the frequency and energy per stroke of the piston of a percussion apparatus, which is simple, reliable and compact, to be able to equip particularly the small and medium power devices. For this purpose, the invention is concerned with a method of regulating the striking stroke of a percussion apparatus, moved by an incompressible fluid under pressure, comprising a piston that moves inside a cylinder and delimits therewith a high chamber and a lower chamber sequentially supplied with fluid at high pressure by the action of a distributor linked to a pilot device that allows to vary the stroke of the hitting piston, and comprising a box or slide mounted in a cylinder on one of the face of which a spring acts and from which the other face can be subjected to a fluid pressure, this box or slider comprises a joined throat, on the one hand, to the distributor and, on the other hand, and depending on the axial position of the slide, to one of several channels that open into the cylinder and capable of being placed in communication with the lower chamber at the end of the stroke movement of the hitting piston towards the top, characterized in that it consists, after the rebound phase of the piston following the impact, in determining the eventual existence of an instantaneous flow of fluid flowing from the upper chamber to the high-pressure fluid supply circuit, determined to Starting from the differential pressure between these two circuits later, if a flow rate as such is detected, pressurized fluid feed the pilot device to move the correder a of the latter in a sense of elongation of the stroke of the striking piston. It is, in effect, to act on the pilot device according to the direction and the measurement of the instantaneous flow that leaves the upper chamber at the moment where the position of the distributor corresponds to the rebound phase of the striking piston. If, in a soft ground, the rebound is unimportant, the differential pressure resulting from the instantaneous flow coming out of the upper chamber will be unimportant, and the pilot device will not be actuated, in order to keep the piston from striking a short stroke. On the contrary, if the device works in a hard terrain, the energy of rebound will be important, and the loss of load created by the instantaneous flow of the fluid that leaves the upper chamber will be important, to create a differential pressure that imposes the power of the fluid under pressure of the pilot device, in order to lengthen the stroke of the striking piston. Advantageously, this method consists in carrying out the optional supply of pressurized fluid, from the pilot device, only during the rebound phase of the piston, at the beginning of the movement of the distributor and while the distributor still feeds the high chamber of fluid under pressure.

It is important to perfectly control the moment in which the pilot device must be supplied with fluid under pressure, in order to neutralize the hydraulic information resulting from the sudden stop of the piston after its impact under the tool. According to a characteristic of the invention, an apparatus for the application of this method comprises a drive slide subjected to opposing pressures of the prevailing fluid, respectively, in the upper chamber and in the supply circuit of the high-pressure fluid chamber, this slide opens a supply circuit of the pressurized fluid pilot device, when the difference between the pressure in the upper chamber and the pressure in the supply circuit exceeds a predetermined value. Advantageously, the actuating slide is mounted on a cylinder delimiting with the slide two opposite chambers connected, respectively, to the upper chamber and to the high-pressure fluid supply channel, and into which two channels joined, respectively, connect to each other. a source of fluid under pressure and to the pilot device, these two channels are capable of being put into communication by a throat comprising a drive slide, in a certain axial position thereof. The source of pressurized fluid that supplies the supply of the pilot device through the cylinder of the actuating slide, can be constituted by the high-pressure supply circuit itself, or, by the upper chamber. The cylinder of the drive slide can thus be connected to one or the other of these two pressure sources. Advantageously, in order to master the moment in which the fluid under pressure can be provided to the pilot device, taking into account the operating cycle of the apparatus, the supply conduit of the fluid-pressure pilot device passes through a a sliding device, from which the movement is mechanically connected to the movement of the distributor, and which comprises a throat which, following the position of the slide, allows or allows the passage of fluid under pressure in the direction of the selector slide of the dal stroke hitting piston, belonging to the pilot device. Preferably, the throat of the slide, associated with the distributor, is positioned in such a way that it does not allow the passage of fluid under pressure more than during the beginning of the stroke of the distributor slide, at a moment where the distributor - - still allows the feeding of the high chamber of high pressure fluid. The slide, associated with the distributor, can be either independent of the distributor's career, or be an integral part of it. According to another feature of the invention, this device comprises an output channel, in permanent or momentary communication with the supply circuit of the fluid pressure pilot device, designed to evacuate, in each cycle, a defined amount of fluid, for bringing back the spool of the pilot device in the direction of the decrease in the stroke of the striker piston, when this pilot device is no longer sufficiently supplied with fluid under pressure. In any case, the invention will be well understood with the help of the following description, with reference to the attached schematic drawings, which represent, by way of non-limiting examples, various embodiments of this apparatus: Figure 1 represents a sectional view longitudinal of a first apparatus; Figure 2 represents a longitudinal sectional view of the same apparatus in another operating position; Figure 3 represents a longitudinal sectional view of the same apparatus in another operating position; Figure 4 represents a longitudinal sectional view of a variant of the same apparatus; Figure 5 represents a partial view of a variant of the apparatus of figure 1; Figure 6 represents a longitudinal sectional view of a variant of the apparatus of figure 1. The apparatus, represented in figure 1, is a percussion apparatus comprising a piston 1, which slides in a body 2, and which comes to hammer each cycle a tool 3. A main distributor, mounted on the body 2, comprising a box or slide 4, allows to put the upper chamber 8 provided on top of the piston, alternatively in relation to the supply of high pressure fluid 5, as shown in FIG. 1, or 'with the low pressure circuit 6, as shown in FIG. 2. In addition, the piston 1 forms with the body 2, an annular chamber 9, permanently supplied by the channel 5, so that in each position of the distributor slide, it causes the stroke of stroke of the piston 1, after the ascent stroke. The choice of the small or large striking stroke is established from a piloting device which, according to the position of the selector piston of the stroke 13, can connect the channels 11 and 12 or channels 10 and 12, respectively. channel 12 is attached to a pilot section of main distributor 4, while channels 10 and 11 open into cylinder containing piston 1. According to the invention, the apparatus comprises a box or slider 15 comprising two chambers of opposite pilot: on the one hand the chamber 20 joined by a channel 22 to the supply channel 5 of high pressure fluid and, on the other hand, the chamber 21 joined to the upper chamber 8. The apparatus also comprises a second box or slide 23 from which the movement is mechanically joined to the movement of the slide 4 of the main distributor and which comprises a throat 24 that allows to stop or let the fluid pass between a channel 16 coming from the first slide 15 and a channel 18 that opens into the pilot chamber of the selector slide of the race 13. The pilot circuit of the race selector 13 comprises a channel 14 connected to the high pressure fluid conduit 5, the slide 15, the channel 16, the slide 23 and the channel 18 that ends on a section of the selector slide of course 13. When the terrain, found by the tool- ta, it's soft, piston 1 does not bounce over the tool 3 after the impact, the slide 15 is constantly kept in the low position by the supply pressure coming from the channel 5 and the accumulator 7 by means of the intermediation of the channel 22 and is applied on the largest diameter of the slide, after the annular section This channel is connected to the low pressure circuit 6 by a channel 24. The channel 14, connected to the supply channel 5, no longer communicates with the channel 16. The pilot section of the selector of course 13 is no longer fed and this selector, thanks to the spring 19, remains in a low position, which connects the depilation channel 12 of the distributor 4 with the channel 11 corresponding to the small stroke of the piston 1. Figure 3 represents the position of the moving parts when the terrain, found by the tool, is hard. The striking piston 1 rebounds just after its impact on the tool 3 and rejects the fluid in the channel 17, when the main distributor 4 is still in the position of Figure 1 and begins to move from the position of Figure 1 to the position of Figure 2. The instantaneous flow rate of fluid in channel 17, at the moment of rebound of the piston, creates a loss of load, and then, establishes a differential pressure between the upper chamber 8 and the mouth of the channel 22 in the supply channel 5. Beyond a certain flow rate, this differential pressure is sufficient to lift the slide 15. At this time, the slide 15 communicates channel 14 and channel 16 through the intermediation of a throat 15a. During this communication, the distributor 4 changes position, and the slide 23, attached to this distributor, briefly relieves the channel 16 to the channel 18. The fluid passes successively from the channel 14 to the channel 16, then to the channel 18 , it feeds the piloting section of the selector of the stroke 13, and allows to reject this selector against the action of the spring 19. This selector 13 then communicates the pilot channel 12 of the main distributor 4 with the channel 10 corresponding to the large stroke of piston strike 1. The slide 15 is set in motion only when the instantaneous flow goes from the upper chamber 8 to the channel 5, by the intermediation of the channel 17. When the flow towards the channel 17 is in the direction of filling the upper chamber 8, the slide 15 remains motionless. According to another variant of the invention, the channel 22 can be connected to the channel 17, instead of the channel 5. In fact, the movement of the slide 15 is no longer sensitive to the loss of load due to the instantaneous flow rate. that leaves the upper chamber 8. Figure 3 shows the position of the moving parts when, during the rebound of the piston, the slide 13, from which the movement joins that of the distributor 4, allows the fluid from the channel 16 to pass the channel 18 and the selector 13, at a chosen moment, as a function of the relative position of the groove 24 of this slide and of the mouth of the channels 16 and 18. This slide 23 comprises a central channel 28 that opens into a throat annular, which allows channel 16, channel 18 and through a calibrated orifice to be relieved at the same time, the low pressure circuit 6. During the operation of the apparatus, the movements of the striking piston 1 and distributor 4 remain constantly connected between yes . Thus, in a precise position of the stroke of the piston 1, the slider of the distributor and the slide 23 will thus be in a precise position. By choosing the position of the groove 24 of the slide 23, it is possible to precisely foresee the time lapses of the operating cycle during which the passage of fluid between the channels 16 and 18 is authorized.

The good choice is to establish communication between channels 16 and 18, a few moments after the crash. In effect, at the moment of the piston collision on the tool, the slide 15 has a tendency to get up under the effect of the water hammer due to the sudden stop of the striking piston, then it descends again immediately, if the terrain is soft, but stays up a little longer if the terrain is hard . The slide 23 makes it possible to eliminate the influence of the variations in pressure in the upper chamber 8, and does not let the fluid out, towards the selector 13, more than a little later, at the moment where the lifting of the slide 15 corresponds effectively to the presence of an established flow from the upper chamber 8 to the channel 5, and thus, to a rebound of the piston on a hard ground. When the ground is no longer hard enough to justify the passage of the large stroke of the striking piston, the calibrated orifice contained in the channel 28 evacuated to the low pressure circuit 6, all the fluid coming from the slide 15 and the channel 16. Thus, the channel 18 no longer receives fluid, but instead, evacuated through the channel 28, the fluid contained in the pilot chamber of the slide 13 allows it to be maintained in the small stroke of the striking piston. Figure 4 represents a variant of the invention according to which the ditribuidor 4 and the slide 23 do not form more than one piece. In this variant, the channel 28 is suppressed and replaced by a channel 29 or a channel 30 comprising a calibrated orifice and connecting the channel 18 with the low pressure circuit 6. In this embodiment, if the amount of fluid injected by the channel 16 in the pilot chamber of the slide 13 is greater than the quantity of fluid evacuated by the channel 29 or 30, then the slide 13 is pushed upwards, in order to select the large stroke of the hitting piston . Figure 5 represents another form of embodiment of the invention, in which the slide 15 is constituted by a mouth or valve, which allows the recovery of energy. During the rebound phase of the piston, this valve, specially arranged according to the invention, comprises a groove 15a which allows to connect the channel 14, supplied with high pressure, with the channel 16, at the time of its lifting. On a hard ground, during its rebound phase, the piston 1 expels the fluid contained in the upper chamber 8, directly through the passage 25, then the channel 26 towards the high pressure circuit 5, to lift the valve 15. valve 15 remains raised while the head loss due to the flow between channels 25 and 26 is greater than the value of the supply pressure multiplied by a constant dependent on the sections of the valve. The feed pressure is kept constant on the other hand, the valve 15 then remains open from a foreseen flow rate of evacuation of the upper chamber 8. During the entire duration of the passage of fluid through this valve 15, the throat of the valve sets in communication the channel 14 with the channel 16. Which allows, through the passage of fluid through the slide 23, feed the channel 18 and thus pilot the selector of the race 13 in order to obtain a large stroke of the piston for a hard ground. Figure 6 represents another embodiment of the invention, according to which the channel 14 is replaced by a channel 27 in communication with the upper chamber 8. At the moment where the flow in the channel 27 is in conditions to be established, the chamber High is evidently under pressure. The supply of the fluid can thus be placed in the upper chamber 8 instead of being placed as previously by the arrival channel 5. Like the rest of the above, the invention brings an improvement and a simplification to the current state of the art in the domain of automatic selection of the beating course of these devices. As is evident, the invention is not limited to the only embodiments of this apparatus, described above by way of examples; it covers, on the contrary, all the variants of realization. It is thus particularly that the number of positions of the selector slider 13 could be greater than two, without departing from the scope of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (11)

Claims

1. A method for regulating the striking stroke of a percussion device, moved by means of an incompressible fluid under pressure, comprising a piston that moves inside a cylinder and delimits therewith a high chamber and a lower chamber fed in a manner sequential high-pressure fluid by the action of a distributor uiido a piloting device that allows to vary the stroke of the striking piston, and comprising a slide mounted on a cylinder of which one of the faces can be subjected to a pressure of fluid and comprising a striking device, this slide comprises a throat connected, on the one hand, to the distributor and, on the other hand, and as a function of the axial position of the slide, to one of several channels that open into the cylinder and capable of being put into communication with the lower chamber at the end of the stroke movement of the hitting piston towards the top, characterized in that After the rebound phase of the piston following the impact, determine the possible existence of an instantaneous flow of fluid that leaves the upper chamber to the high-pressure fluid supply circuit, determined from the differential pressure between these two circuits, then, if a flow rate as such is detected, to supply the pilot device with fluid under pressure to displace the slide thereof in a direction of elongation of the stroke of the striking piston.

2. A method according to claim 1, characterized in that it consists in carrying out the optional supply of fluid under pressure of the pilot device, only during the piston rebound phase, at the beginning of the movement of the distributor while the distributor feeds the piston. still the high chamber of high pressure fluid.

3. An apparatus for the application of the method according to any of claims 1 and 2, characterized in that it comprises a drive slide, omitted at the opposing pressures of the prevailing fluid, respectively, in the upper chamber and in the power supply circuit. the high pressure fluid plenum, this slide opens a supply circuit of the pressurized fluid pilot device, when the difference between the pressure in the upper chamber and the pressure in the supply circuit exceeds a predetermined value.

4. An apparatus according to claim 2, characterized in that the drive slide is mounted on a cylinder that delimits with the slide two opposite chambers connected, respectively, to the upper chamber and to the high-pressure fluid supply channel, and in the where two channels connected to a source of fluid under pressure and to the pilot device, respectively, open, these two channels are capable of being put into communication by means of a throat comprising the drive slide, in a certain axial position thereof.

5. The apparatus according to claim 4, characterized in that one of the channels opens into the cylinder of the drive slide that communicates with the supply conduit of the high pressure fluid apparatus.

6. The apparatus according to claim 4, characterized in that one of the channels that opens into the cylinder of the drive slide communicates with the upper chamber.

7. The apparatus according to any of claims 3 to 6, characterized in that the supply conduit of the pressure fluid pilot device passes through a slider device, from which the movement is mechanically linked to the movement of the distributor and which comprises a throat that, immediately after the position of the slide, allows or does not allow the passage of pressurized fluid in the direction of the selector slide of the stroke course, belonging to the piloting device.

8. The apparatus according to claim 7, characterized in that the throat of the slide associated with the distributor is positioned in such a way that it does not allow the passage of fluid under pressure more than during the beginning of the stroke of the distributor slide, to a period in which the distributor still allows the feeding of the high chamber of fluid under pressure.

9. The apparatus according to any of claims 7 and 8, characterized in that the slider associated with the distributor is independent of the distributor slider and linked mechanically to the latter.

10. The apparatus complies with any of claims 7 and 8, characterized in that the slider associated with the distributor, and the slider of the distributor form a single piece.

11. The apparatus according to any d < 2, claims 3 to 10, characterized in that it comprises a channel "2", in permanent or momentary communication with the supply circuit of the fluid pilot device under pressure, designed to evacuate, at each cycle, a defined quantity of fluid, for restoring the spool of the pilot device in the direction of decreasing the stroke of the striker piston, when this piloting device is no longer sufficiently supplied with fluid under pressure.