EP0040026A1 - Machine à piston libre - Google Patents

Machine à piston libre Download PDF

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Publication number
EP0040026A1
EP0040026A1 EP81301919A EP81301919A EP0040026A1 EP 0040026 A1 EP0040026 A1 EP 0040026A1 EP 81301919 A EP81301919 A EP 81301919A EP 81301919 A EP81301919 A EP 81301919A EP 0040026 A1 EP0040026 A1 EP 0040026A1
Authority
EP
European Patent Office
Prior art keywords
piston
pressure
recess
exhaust
supply line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP81301919A
Other languages
German (de)
English (en)
Inventor
Nigel Bruce Cox
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Halco Directional Drilling Products Ltd
Original Assignee
Halco Directional Drilling Products Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Halco Directional Drilling Products Ltd filed Critical Halco Directional Drilling Products Ltd
Publication of EP0040026A1 publication Critical patent/EP0040026A1/fr
Withdrawn legal-status Critical Current

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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
    • E21B4/00—Drives for drilling, used in the borehole
    • E21B4/06—Down-hole impacting means, e.g. hammers
    • E21B4/14—Fluid operated hammers

Definitions

  • THIS INVENTION concerns free piston machines and in particular pressure fluid-powered free piston machines in which a piston is caused to reciprocate by the admission of pressure fluid, e.g. compressed air, alternately to working chambers at opposite ends of a cylinder within which the piston is reciprocable.
  • pressure fluid e.g. compressed air
  • the efficient conversion of the energy content of the pressure fluid into motion of the piston depends critically upon the manner in which the pressure fluid is directed to the working chambers and exhausted therefrom in relation to the motion of the piston.
  • the arrangements adopted for controlling the pressure fluid flows fall, broadly, into two classes: the “valveless” arrangements in which the motion of the piston serves to cover and uncover various static ports and passages to accomplish the required control; and the “valved” arrangements in which a valve mechanism responds to the motion of the piston to switch the pressure fluid supply from one working chamber to the other at appropriate instants in the cycle of reciprocation of the piston.
  • the present invention is concerned with the "valveless" class of machine and has as its objective the provision of improved arrangements for directing the pressure fluid to, and exhausting the spent fluid from, the working chambers of the machine.
  • An object of the present invention is to provide a valveless pressure fluid-powered free piston machine that avoids these disadvantages of the prior art constructions.
  • the present invention provides a valveless pressure fluid-powered free piston machine comprising a piston reciprocable in a cylinder providing power and return working chambers respectively at opposite ends thereof, axially spaced apart pressure and exhaust piston wall ports and associated pressure and exhaust passages in the piston, and cooperative flow passages formed at least partly in the cylinder wall for connecting said pressure and exhaust piston wall ports with the power and relurr.
  • the pressure and exhaust passages in the piston are preferably rectilinear and inclined with respect to the axis of the piston so as to be formable by a simple drilling or like operation followed by surface finishing so as to minimise regions of stress concentration and to enable the available strength of the piston material to be fully realised, while providing flow paths of suitable cross-sectional area for efficient transmission of pressure fluid to the return working chamber, and for the efficient exhaust of spent fluid from the power working chamber.
  • These passages are also preferably disposed within the same portion of the length of the piston to provide a strong and compact piston configuration.
  • the said pressure fluid supply line is arranged within the power working chamber, i.e. the chamber to which pressure fluid is admitted to effect the power stroke of the piston, and admission of pressure fluid to this power working chamber is controlled. by the position of the piston as it affects the position of the pressure recess relative to the said supply line. This arrangement enables the full cross-sectional area of the piston to be exposed to the pressure fluid at the commencement of the power stroke so that the maximum thrust is developed to displace the piston in the power stroke.
  • the pressure recess is formed in the piston and the pressure fluid supply line is fixed to the cylinder or to a component associated therewith, the pressure recess in this case being connected to the said pressure passage in the piston.
  • the pressure recess is formed in the cylinder, e.g. in a headpiece thereof, or in a component associated therewith, and the pressure fluid supply line is fixed to the piston to move therewith, being connected to the said pressure passage in the piston.
  • the piston may have an axial exhaust recess connected to the exhaust passage or passages in the piston.
  • This exhaust recess may be arranged to cooperate with an axial exhaust line, such as a foot valve tube, to control the flow of spent pressure fluid from the return working chamber, or this recess may serve solely for passing spent pressure fluid from the power working chamber to an exhaust outlet, the movement of the piston providing, by other means, control of the flow of spent pressure fluid from the return working chamber.
  • the length and location of the pressure fluid flow path-defining component constituted by the supply line, relative to the piston stroke, will determine the proportion of the power stroke over which pressure fluid may continue to flow from the supply line to the power working chamber.
  • This flow path-defining component may comprise one or more grooves extending along the exterior of the supply line to provide one or more discrete flow paths between the pressure recess in the piston and the power working chamber when the piston is appropriately positioned in the cylinder, but in preferred embodiments the flow path-defining component comprises a suitable length of circumferential relieving of the supply line to provide greatest freedom for symmetrical pressure fluid flow from the pressure recess to the power working chamber.
  • the said cooperative flow passages in the piston and cylinder wall may take various configurations.
  • flats or longitudinal grooves in the piston may cooperate with circumferential relieving of the cylinder wall in appropriate locations therein, or circumferential relieving of discrete areas of the piston may cooperate with suitably positioned longitudinal recesses or grooves formed in the cylinder wall.
  • Other arrangements will be apparent to those skilled in the art.
  • the hammer drill partly illustrated therein comprises a body defining a cylinder 1 within which a piston 2 is recipr ' ocable.
  • the upper end of the body has a tubular spigot 3 adapted for attachment to a drill tube (not shown) by means of which the body may be rotated during a drilling operation and through which compressed air as pressure fluid is supplied to the drill.
  • the pressure fluid flows into the drill by way of a passage 4 in the spigot 3, past a spring-loaded non-return valve 5 to a passage 6 communicating via ports 7 with the bore 8 of a cylinder headpiece 9 carrying an axial pressure fluid supply line 10 that extends into a pressure recess 11 in the adjacent end of the piston 2.
  • the region within the cylinder 1 between the piston 2 and the headpiece 9 constitutes a working chamber 12 to which pressure fluid is admitted to effect the downward or "power" stroke of the piston 2 and for this reason is termed the "power" working chamber herein.
  • the lower end of the piston 2 is formed with an exhaust recess 13 that in the illustrated stroke-end position shown in Figure IA receives a foot valve tube 14 that defines an exhaust line for the outflow of spent pressure fluid and that is secured in the upper end of the shank 15 of a drill bit the head of which is not shown in the drawing.
  • the drill bit shank 15 is secured in a chuck 16 so as to have limited freedom for axial movement relatively to the drill body.
  • bit shank 15 and the chuck 16 have cooperating splines 17 for the transmission of torque from the drill body to the bit, the splines being relieved as at 18 over a length of the bit shank to provide shoulders 19, 20 disposed to engage with a diametrically split combined sealing and retaining ring 21 to limit the axial movement of the bit.
  • the pressure recess 11 in the upper end of the piston 2 is connected by pressure passages 22 to pressure ports 23 in the wall of the piston near to the lower end thereof.
  • the passages 22 may have other configurations if desired.
  • the exhaust recess 13 at the lower end of the piston is connected to exhaust passages 24 that extend obliquely upwardly to exhaust ports 25 in the wall of the piston near to its upper end.
  • exhaust passages 24 that extend obliquely upwardly to exhaust ports 25 in the wall of the piston near to its upper end.
  • the passages 24 are larger in cross-section than the passages 22 because they are required to pass air that has expanded to a lower pressure than the live compressed air to be passed by the passages 22.
  • the upper end of the piston 2 is formed with external flats 26 that in the position of the piston shown cooperate with a circumferential recess 27 formed in the wall of the cylinder and that in turn communicates with the exhaust ports 25 in the piston 2.
  • an exhaust flow path extends from the power working chamber 12 past the flats 26 to the recess 27 and thence via exhaust ports 25 and passages 24 to the exhaust recess 13, and the foot valve tube 14, to an exhaust passage 28 leading to openings (not shown) in the head of the bit.
  • the lower end portion of the piston 2 is formed with external flats 29 that in the illustrated position of the piston overlie a circumferential recess 30 in the wall of the cylinder.
  • the pressure ports 23 in the cylinder are positioned to overlie the recess 30 in this position of the piston so as to provide a flow path for compressed air from the pressure recess 11 via the passages 22 and pressure ports 23 to the return working chamber 31 defined in the lower end of the cylinder 1 between the bottom of the piston and the anvil surface of the bit shank 15.
  • the piston 2 is also formed, below the exhaust ports 25 but above the pressure ports 23, with a by-pass groove 32 the upper end of which breaks into one of the exhaust ports 25 and that is so positioned on the piston that if the bit shank 15 moves to its lowermost permitted position (as can happen under certain drilling conditions), the by-pass groove 32 mates with the recess 30 to provide a flow path between the return working chamber 31 and the exhaust recess 13 so as to prevent live compressed air entering the chamber 31 from being effective to cause a return stroke of the piston.
  • the piston 2 is further formed with a small bore axial passage 33 connecting the recesses 11 and 13 for a purpose that will be explained.
  • the supply line 10 is externally relieved over that part of its length from the headpiece 9 to approximately the position of the upper end face of the piston 2 when the latter is in its normal power stroke-end position within the cylinder, that is, approximately the position illustrated.
  • the pressure recess 11 except for its entrance region, is of larger diameter than the end portion of the supply line 10 and accordingly the external relieving of the supply line and the enlargement of the recess 11 together provide a flow path from the recess 11 to the power working chamber 12 when the piston 2 is at or near the upper end of its permitted travel.
  • Compressed air will continue to be admitted to the working chamber 12 until such time as the flow path from the recess II to the chamber 12 is interrupted by the entry of the full section portion of the supply line 10 into the matching sized entrance to the recess 11 in the piston. Thereafter the air in the chamber 12 will expand to give up energy to the piston 2 until such time as the flats 26 overlap the recess 27 to provide a path to exhaust for the spent air in the chamber 12.
  • the piston 2 delivers a blow on the anvil surface at the upper end of the bit shank 15 and the above- described cycle then repeats.
  • the axial passage 33 in the piston provides for a constant bleed of live compressed air from the recess 11 to the recess 13 and thus to the exhaust system.
  • the pulsating flow of exhausted, spent, air from the exhaust system serves for cooling the bit and for flushing cuttings away from the bit face.
  • the bleed of live air via passage 33 supplements this exhaust flow to enhance the action thereof, while maintaining an adequate flushing function at times when the piston is not reciprocating, as a result of movement of the bit to a position bringing the by-pass groove into register with the recess 30.
  • the piston 2 in this embodiment has no terminal relieving corresponding with the flats 26 and 29 at the upper and lower ends, respectively of the piston of the embodiment of Figures 1 to 4.
  • the cylinder 1 is formed with two sets of longitudinal grooves, for instance, by spark erosion techniques.
  • the cylinder 1 is formed with a set of longitudinal grooves 41, preferably equiangularly spaced about the axis of the cylinder so as to provide symmetry of flow and disposed to provide communication between the working chamber 12 and the exhaust ports 25 during the relevant part of the piston reciprocation cycle, while minimising asymmetry in the stresses in the drill body.
  • a second set of longitudinal grooves 42 is provided lower in the cylinder 1 than the grooves 41 to provide the function of the flats 29 at the lower end of the piston in the embodiment of Figures 1 to 4. As shown in Figure 8, these grooves 42 are similar in configuration and arrangement to the grooves 41 but other configurations and arrangements are possible to meet particular requirements as to air flow and cylinder strength.
  • the piston is formed with a circumferential relieving 43 with which the exhaust ports 25 communicate.
  • the piston is formed with a circumferential relieving 44 with which the pressure ports 23 communicate so as to provide for uninterrupted communication between those pressure ports and the grooves 42 during the relevant portion of the operating cycle.
  • circumferential relieving 43 communicates with a groove 32 to provide the same function as the similar groove in the embodiment of Figures 1 to 4.
  • the pressure fluid supply line 10 is fixed to the piston to reciprocate therewith and to cooperate with a pressure recess lla that is formed in the cylinder headpiece 9; and secondly in that the lower end of the piston 2 is stemmed and extends through a seal ring 50 in the cylinder and from which it is withdrawn at and near the upper stroke-end position to provide for venting of the return working exhaust chamber 31 to an annular exhaust space 51 that communicates with lateral exhaust ports (not shown).
  • the exhaust recess 13 in the piston serves solely for venting the power working chamber 12 to the exhaust port of the machine.
  • the full cross-sectional area of the piston is available for exposure to the pressure fluid to generate the thrust to propel the piston on its power stroke so that conversion of pressure fluid energy into usable piston energy is maximised. It is accordingly possible to design the machine to operate with short strokes and higher than usual operating frequencies to achieve higher overall power outputs than, or conversely to utilise a heavier piston operating at lower impact velocities than usual to obtain the same power output as, conventional machines of corresponding dimensions and subject to the same pressure fluid supply. It has also been mentioned that the passages formed in the piston are susceptible to simple formation techniques that enable an optimum compromise to be obtained between passage cross-section and freedom of flow path, on the one hand, and piston strength on the other hand.
  • the passages in the piston are preferably arranged within the same portion of the length of the piston to provide a compact configuration. This also enables the passages to be located in a piston region of full cross section not weakened by the presence of recesses such as the recesses 11 and 13.
  • the cylinder is not complicated by the need to provide therein ports and blind passages as in many prior art constructions, the only required cylinder passages in the machine of the invention being open to the bore of the cylinder throughout their length and thus being capable of being manufactured by simple machining or other forming techniques and with minimisation of the cylinder strength reduction as the result of the provision of such passages. Complicated cylinder liner systems are not required.
  • machines in accordance with the invention may be constructed with integral or non-detachable headpieces 9 such as illustrated in Figure 9, and/or with non-detachable chucks.
  • the pressure fluid supply line that extends axially in the power working chamber is of simple configuration capable of being manufactured by straightforward machining or equivalent techniques that preserve the strength and avoid the formation of stress raisers in this component, such as are unavoidable in certain prior art constructions with complicated porting of a pressure fluid supply line.
  • the machine of the invention is mechanically simple, comprising a single moving part (the piston) and only few major functional items, viz, the cylinder, the pressure fluid supply line and the exhaust line (foot valve) or other arrangement for venting the return working chamber.

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  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Actuator (AREA)
  • Reciprocating Pumps (AREA)
EP81301919A 1980-05-09 1981-04-30 Machine à piston libre Withdrawn EP0040026A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8015389 1980-05-09
GB8015389 1980-05-09
GB8040286 1980-12-16
GB8040286 1980-12-16

Publications (1)

Publication Number Publication Date
EP0040026A1 true EP0040026A1 (fr) 1981-11-18

Family

ID=26275454

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81301919A Withdrawn EP0040026A1 (fr) 1980-05-09 1981-04-30 Machine à piston libre

Country Status (5)

Country Link
EP (1) EP0040026A1 (fr)
AU (1) AU7025881A (fr)
CA (1) CA1151027A (fr)
ES (1) ES502022A0 (fr)
PT (1) PT73003B (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0081897A1 (fr) * 1981-12-10 1983-06-22 WEAVER & HURT LIMITED Foreuse à percussion
EP0099594A2 (fr) * 1982-07-23 1984-02-01 WEAVER & HURT LIMITED Dispositif pour forer dans la roche
GB2219817A (en) * 1988-06-15 1989-12-20 Abraham Gien Down the hole hammer equipment
EP0564427A1 (fr) * 1992-03-31 1993-10-06 Uniroc Aktiebolag Machine de forage de fond de trou
WO1999057411A1 (fr) 1998-05-04 1999-11-11 Permon S.R.O. Outil de forage pneumatique et submersible
US6386301B1 (en) * 1997-10-01 2002-05-14 Ian Graeme Rear Down-hole hammer
US7272579B1 (en) * 2000-02-17 2007-09-18 Fedbid, Inc. Auction based procurement system
EP1943407A1 (fr) * 2005-11-03 2008-07-16 Rockmore International, Inc. Tete posterieure et ensemble de forage muni d'une tete posterieure
US8046269B2 (en) 2000-02-17 2011-10-25 Fedbid, Inc. Auction based procurement system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB749328A (en) * 1953-05-01 1956-05-23 Hughes Tool Co Fluid actuated reciprocatory prime mover
US3964551A (en) * 1974-09-20 1976-06-22 Reed Tool Company Pneumatic impact drilling tool
US3970153A (en) * 1975-01-13 1976-07-20 Abraham Gien Pneumatic percussion machines
US4030554A (en) * 1975-07-07 1977-06-21 Bakerdrill, Inc. Bore hole airhammer and anvil bit
US4084647A (en) * 1976-07-01 1978-04-18 William Lister Pneumatic percussion hammer
US4146097A (en) * 1972-04-24 1979-03-27 Bakerdrill, Inc. Bore hole air hammer

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB749328A (en) * 1953-05-01 1956-05-23 Hughes Tool Co Fluid actuated reciprocatory prime mover
US4146097A (en) * 1972-04-24 1979-03-27 Bakerdrill, Inc. Bore hole air hammer
US3964551A (en) * 1974-09-20 1976-06-22 Reed Tool Company Pneumatic impact drilling tool
US3970153A (en) * 1975-01-13 1976-07-20 Abraham Gien Pneumatic percussion machines
US4030554A (en) * 1975-07-07 1977-06-21 Bakerdrill, Inc. Bore hole airhammer and anvil bit
US4084647A (en) * 1976-07-01 1978-04-18 William Lister Pneumatic percussion hammer

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0081897A1 (fr) * 1981-12-10 1983-06-22 WEAVER & HURT LIMITED Foreuse à percussion
EP0099594A2 (fr) * 1982-07-23 1984-02-01 WEAVER & HURT LIMITED Dispositif pour forer dans la roche
EP0099594A3 (en) * 1982-07-23 1984-04-25 Weaver & Hurt Limited Rock drills
GB2219817A (en) * 1988-06-15 1989-12-20 Abraham Gien Down the hole hammer equipment
GB2219817B (en) * 1988-06-15 1992-04-01 Abraham Gien Down the hole hammer equipment
EP0564427A1 (fr) * 1992-03-31 1993-10-06 Uniroc Aktiebolag Machine de forage de fond de trou
US6386301B1 (en) * 1997-10-01 2002-05-14 Ian Graeme Rear Down-hole hammer
WO1999057411A1 (fr) 1998-05-04 1999-11-11 Permon S.R.O. Outil de forage pneumatique et submersible
US7272579B1 (en) * 2000-02-17 2007-09-18 Fedbid, Inc. Auction based procurement system
US8046269B2 (en) 2000-02-17 2011-10-25 Fedbid, Inc. Auction based procurement system
EP1943407A1 (fr) * 2005-11-03 2008-07-16 Rockmore International, Inc. Tete posterieure et ensemble de forage muni d'une tete posterieure
EP1943407A4 (fr) * 2005-11-03 2012-01-04 Rockmore International Inc Tete posterieure et ensemble de forage muni d'une tete posterieure

Also Published As

Publication number Publication date
ES8302186A1 (es) 1982-12-16
ES502022A0 (es) 1982-12-16
AU7025881A (en) 1981-11-12
PT73003B (en) 1982-04-30
CA1151027A (fr) 1983-08-02
PT73003A (en) 1981-06-01

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19820205

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Effective date: 19831125

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Inventor name: COX, NIGEL BRUCE