Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B28/00—Vibration generating arrangements for boreholes or wells, e.g. for stimulating production
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25D—PERCUSSIVE TOOLS
  • B25D9/00—Portable percussive tools with fluid-pressure drive, i.e. driven directly by fluids, e.g. having several percussive tool bits operated simultaneously
  • B25D9/06—Means for driving the impulse member
  • B25D9/12—Means for driving the impulse member comprising a built-in liquid motor, i.e. the tool being driven by hydraulic pressure
  • B25D9/125—Means for driving the impulse member comprising a built-in liquid motor, i.e. the tool being driven by hydraulic pressure driven directly by liquid pressure working with pulses

Definitions

• the invention concerns an impulse generator according to the preamble of claim 1.
• the invention also concerns a hydraulic impulse tool including such an impulse generator and a method for producing impulses.
• the configuration of this wave is i.a. determined by the boundary conditions of the chamber, i.e. its end walls. If the boundary condition is such that an end wall is very rigid, a flow node (no flow variation) and a pressure antinode (maximal varying pressure) will occur at this position. If the boundary condition is non-rigid with respect to the liquid, a flow antinode (maximal varying flow) and a pressure node (no pressure variation) will occur in this position. In the flow antinode, the liquid moves at a maximum, which means that the energy there is bound as kinetic energy. In the pressure antinode, the energy binds as elastic energy.
• the chamber wall is essentially rigid, which in practice will form the above mentioned rigid boundary condition for the liquid, with the forming of said pressure antinode as a consequence.
• the pressure antinode the pressure ideally varies with sine form, over time, i.e. symmetrically around a mean pressure. Maximal pressure variation in this position can thus be between zero and double the mean pressure. In practice the pressure will vary somewhat also at the pressure node side. This variation can, however, be made as small as desired or as small as can be accepted by influencing the height of the resonant peak. This can be achieved by adapting the impedances of the drill string, the resonance chamber and the pump for feeding the resonance chamber.
• the parameters influencing the resonant frequency inside the chamber are essentially: the length of the chamber, the boundary conditions, the density and the compressibility modulus of the liquid and to a certain extent also the cross sectional dimensions of the chamber.
• liquid is fed in/out through inlet/outlet to the chamber, which makes a solution possible, which is economic and realistically handled.
• a solution according to the invention is lenient to the components involved, since at the inlet side there prevails an essentially constant counter pressure that meets the liquid source, which in particular is comprised of one or several pumps . It can therefore be expected that each pump has a relatively low degree of load and thereby a long life time.
• the chamber is adapted such that in operation there is quarter wave resonance or odd multiples of quarter wave resonance.
• the chamber is adapted for a frequency of between about 200 and 1000 Hz. Other frequencies can, however, also be used.
• Shaping the chamber with a linear extension gives possibility of a slender shape which is to be preferred in many applications. Shaping of the chamber with a bent extension makes it, however, possible to limit its total length .
• the chamber being changeable with respect to its shape and in particular length changeable, there is achieved the possibility of controlling the resonant frequency, which can be advantageous in working in different materials etc.
• valve means for controlling the flow in said channel means advantageous adjustments of the configuration of the pulse affecting the impulse piston is possible.
• the pulse can be controlled such that its shape deviates from the otherwise prevailing sine-shape, and for example be formed so as to minimize reflection effects from influenced rock or the like.
• pulse amplitudes can for example be affected, in particular be raised more than what would otherwise be possible when using a system with one resonance chamber.
• Fig. 1 diagrammatically shows a rock breaking tool including an impulse generator according to the invention
• Fig. 2 shows diagrammatically the pressure distribution obtained in a resonance chamber of an impulse generator according to the invention
• Fig. 3 shows diagrammatically a variant of the pressure distribution in an impulse generator according to the invention
• Fig. 4 shows diagrammatically a variant of the pressure distribution in a second impulse generator according to the invention
• Fig. 5 shows diagrammatically a variant of the pressure distribution in a third impulse generator according to the invention .
• reference numeral 1 generally concerns a rock breaking tool which includes a housing 2 for receiving a volume of liquid in a chamber 3, in the one end of which is arranged an impulse piston 4. This lies via a rod shaped portion 5 directly against a rock breaking tool 7 over a drill rod ⁇ .
• the chamber 3 is formed to its shape with a length 1 and a diameter d and is filled with a chosen liquid, whereby when the same liquid is periodically fed in through liquid inlet/outlets 10 from pumping devices 9, the liquid inside the chamber 3 will be put into a state of resonance.
• a pressure node will be present in the area of the inlets/outlets 10 and that a pressure antinode will be present in the area of the impulse piston 4 and acting thereon .
• reference numeral 8 is indicated a source for providing a constant mean pressure inside the chamber 3 around which mean pressure the pressure inside the resonance chamber will fluctuate. This arrangement will also guarantee that possibly leaking liquid is replaced inside the system.
• F indicates a feed force acting on the rock breaking tool 1, for example from a conventional feeder which is arranged on a feeding beam of a drill rig.
• fig. 2 is diagrammatically shown the pressure distribution in resonance of the liquid in the chamber 3 in operation of the device and with periodic input pumping from the pump 9 of liquid through a liquid inlet/outlet 10.
• the pressure distribution is shown with an upper curve 13, illustrating the amplitude over the length of the constituted resonance chamber 3, with a pressure node 12 and a pressure antinode 11. Further, because of the pressure source 8, there prevails a mean pressure Po, around which the pressure varies inside the resonance chamber.
• the greatest pressure amplitude thus occurs in the pressure antinode 11 in the region of the impulse piston 4, onto which the pressure at this end of the resonance chamber is transmitted for further transfer as a pressure tension wave or a stress wave through the rod shaped part thereof and further through the tool.
• the movement of the piston 4 in the axial direction, the length direction of the chamber is small in connection with the transfer of the pressure pulse as a stress wave in the tool.
• the energy is transferred directly as stress wave energy and not as kinetic energy from the impulse piston to the tool.
• Fig. 2 is also placed three diagrams, whereof the right one illustrates the pressure variation in the area of the pressure node 12. As is shown, in practice here prevails a certain smaller pressure variation, which deviates from an ideal case, where the pressure variation should be zero in this position. This minor variation is, however, tolerable and in practice not detrimental for the function of the impulse generator .
• the diagram at the tool end of the resonance chamber 3 illustrates the pressure variation prevailing at the pressure antinode 11. This is thus in this case such that it varies sine-shaped around the mean value Po with the amplitude Po.
• the impulse piston 4 in this example is influenced by pressures between 0 and 2P 0 . It should be observed that other pressure relations between amplitude and P 0 is within a scope of the invention.
• the F-t-diagram at the far left shows the force being transferred over the impulse piston 4 as function of time. The force F varies sine-shaped between 0 and a certain maximum value of F.
• Fig. 3 illustrates an operating example where the frequency has been increased such that three quarter wave resonance prevails inside the resonance chamber 3.
• the pressure variation is illustrated with the curve 14 and it still exist a pressure node 16 in the area of the inlet/outlet 10.
• a pressure antinode 15 in the area of the impulse piston 4.
• a pressure antinode 17 essentially at a third part distance from the input side.
• the two diagrams at the right of Fig. 3 illustrate the pressure distribution at the inlet and at the impulse piston 4.
• the F-t-diagram shows the force distribution which will influence the tool. In this case the impulse frequency will thus be three times as great as according to the operating example in Fig. 2.
• Fig. 4 a variant is shown which differs from the one shown in Fig. 2 by the fact that a rigid intermediate wall 19 has been placed in the position of the impulse piston 4 in Fig. 2.
• the impulse piston 4 has instead been moved to the left, as seen in the Figure and between the impulse piston 4 and the intermediate wall there has been arranged an impulse chamber 20, which in chosen positions is in connection with the part of the resonance chamber 3 that is closest to the intermediate wall 19.
• valve device 21 which is arranged in channel means and is controllable for connection between these chambers or for cutting off the connection between them. Further, the valve device 21 is capable of evacuating the impulse chamber 20.
• the resonance chamber 3 is connected to the impulse chamber 20 during a rising portion of the pressure curve but be cut off slightly after the amplitude peak.
• the pulse shape this way can be controlled into all kinds of configurations. In particular it is often desirable to optimize the shape for minimizing reflections in the tool. Hereby the rising as well as the descending flange can be adapted to come close to this aim.
• Another aspect is the possibility of having a pulse frequency which is lower than the resonance frequency, for the adjustment to different working situations.
• the smaller diagram close to the valve 21 shows an example of a curve shape being formed this way.
• the F-t- diagram shows the shape of the resulting stress wave.
• Fig. 5 shows two resonance chambers 3' and 3" which are separated by a wall 19' but are series connected, and which are mutually interconnected over a channel with a valve 21' , and which each has a pumping device 9' and 9".
• the details 19" and 20' correspond to the details 19 and 20 respectively in Fig. 3.
• the channel between the chambers 3' and 3" is controllable with the valve 21' generally according to what is true for the valve 21 above.
• a more steep pulse is obtained.
• the meaning of the diagrams is easily understood on hand of the description of previously discussed diagrams.
• valves By suitable control of valves, corresponding to 21, 21' and 21", suitable pulse shapes and stress wave shapes can be obtained.
• the valves can be controlled such that they work with controlled opening and closing characteristics respectively in order to thereby obtain desired shapes. Minimizing reflections in the tool is possible to achieve this way.
• a connection between a resonance chamber and an impulse chamber such as in Figs . 4 and 5 can include a plurality of channels with different length and/or areas. By choice of channel or channels, through which connection shall be established, the progressiveness in the pressure increase in the impulse chamber can be controlled and thereby the shape of the stress wave in the tool be controlled such that it gets a desired progressive flank shape. This gives the possibility of increasing the efficiency of the device.
• this can be achieved by, as an example, arranging parallel conduits between the chambers 3 and 20 in Fig. 4, whereby these channels are adapted as is indicate above.
• the channels can be opened/closed with the aid of valves corresponding to the valve 21 in Fig. 24.
• the channels can be adjustable to there lengths. This can be obtained in different ways, for example by telescopingly displaceable U- pipes, displaceable sleeves in a chamber 3 and/or 4 etc.
• the invention can be modified within the scope of the claims.
• the construction of the device can thus be modified further.
• the liquid can be influenced in other ways than through the ones that are shown.
• One example of this is to have a physically moveable wall moving with a certain frequency instead of a pumping arrangement.
• Other types of pumps and valves can also come into question.
• the pressure node can be arranged separate from a wall of the chamber. It is not excluded that the resonance chamber at the same time is fed with/influenced by different frequencies in order to obtain simultaneous resonance at different frequencies in order to achieve a desired effect on the tool.
• the chamber can be made changeable to its shape so that the resonant frequency is controllable. In its simplest way it is made length changeable by having a rear wall displaceable inside a cylindrical tube forming the chamber.
• liquids can be used, in particular is preferred a liquid from the group; water, silicon oil, hydraulic oil, mineral oil.

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• Engineering & Computer Science (AREA)
• Fluid Mechanics (AREA)
• Physics & Mathematics (AREA)
• Mining & Mineral Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Mechanical Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Geochemistry & Mineralogy (AREA)
• Apparatuses For Generation Of Mechanical Vibrations (AREA)
• Percussive Tools And Related Accessories (AREA)
• Earth Drilling (AREA)
• Fluid-Pressure Circuits (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Pyrane Compounds (AREA)
• Particle Formation And Scattering Control In Inkjet Printers (AREA)
• Surgical Instruments (AREA)

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Citations (5)

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• 2005
  • 2005-05-23 SE SE0501151A patent/SE528649C8/sv not_active IP Right Cessation
• 2006
  • 2006-03-20 US US11/918,704 patent/US8770313B2/en not_active Expired - Fee Related
  • 2006-03-20 CA CA2607415A patent/CA2607415C/en not_active Expired - Fee Related
  • 2006-03-20 EP EP06717033A patent/EP1883503B1/en not_active Expired - Lifetime
  • 2006-03-20 AT AT06717033T patent/ATE549130T1/de active
  • 2006-03-20 ES ES06717033T patent/ES2381569T3/es not_active Expired - Lifetime
  • 2006-03-20 CN CN200680017525.XA patent/CN101180162B/zh not_active Expired - Fee Related
  • 2006-03-20 JP JP2008513402A patent/JP5173801B2/ja not_active Expired - Fee Related
  • 2006-03-20 ZA ZA200709290A patent/ZA200709290B/xx unknown
  • 2006-03-20 AU AU2006250106A patent/AU2006250106B2/en not_active Ceased
  • 2006-03-20 WO PCT/SE2006/000348 patent/WO2006126928A1/en not_active Ceased
• 2007
  • 2007-12-21 NO NO20076622A patent/NO326486B1/no not_active IP Right Cessation

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