US3167136A

US3167136A - Fluid-actuated drilling tool

Info

Publication number: US3167136A
Application number: US863147A
Authority: US
Inventors: Evin L Cook
Original assignee: Socony Mobil Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1959-12-31
Filing date: 1959-12-31
Publication date: 1965-01-26
Anticipated expiration: 1982-01-26

Description

Jan. 26, 1965 E. L. COOK FLUID-ACTUATED DRILLING TOOL.

2 Sheets-Sheet 1 Filed Dec. 31, 1959 FIG. I.

FIG. 2

EVIN L. COOK INVENTOR.

ATTORNEY Jan. 26, 1965 E. COOK FLUID-ACTUATED DRILLING TOOL 2 Sheets-Sheet 2 Filed D80. 31, 1959 FIG. 4.

FIG. 5.

FIG. 3.

K 0 0 C L m V E ATTORNEY United States Patent 3,167,136 FLUID-AETUATED DRKLLING TGQL Evin L. Cook, Dallas, Tern, assignor to Socony Mohii Gil Company, End, a corporation of New York Filed Dec. 31, 195%", Ser. No. 863,147 it (RC1. 173-73) This invention generally relates to tools employed in the drilling of wells in the earth. Specifically this invention relates to a drilling tool actuatable by a noncompressible fluid.

Various approaches have been taken to the problem of providing effective tools for the drilling of wells, particularly the drilling of oil wells. Presently, the most commonly employed method of drilling wells involves the use of rotary drilling tools wherein a bit, positioned at the lower end of a string of drill pipe, is rotated by a rotary table on a drilling rig located at the surface, and a drilling fluid, such as air, gas, or various kinds of liquid, is pumped downwardly through the drill string and outwardly through passages in the bit for the purpose of cooling the bit and flushing the cuttings from the hole upwardly through the annulus around the string of drill pipe.

Numerous forms of apparatus have been suggested for improving rotary drilling by reciprocating the drill bit to cause it to deliver sharp, percussive blows to the formation as the bit is rotated. Among those tools which have been suggested for reciprocating a rotating bit are tools which involve the principle of using the flowing drilling fluid to reciprocate a hammer element into contact with the upper end of the bit or an anvil connected to the bit. These fluid-actuated drilling tools may be of the type operated by a compressible fluid, such as air or gas, or they may be of the type operated by a substantially noncompressible liquid, such as water or various kinds of drilling mud. In both types of fluid-actuated drilling tools, it is necessary to provide apparatus to perform the functions of bothadmitting the actuating fluid and exhausting the actuating fluid from the tool. These functions of admitting and exhausting the actuating fluid, which may be referred to as valve functions, are not especially critical in the case of air or gas actuated tools in view of the compressibility of the fluid being employed. In other words, where a compressible fluid is being employed to drive the tool, variations in valve timing, spacing, positioning, and clearances can be tolerated without effecting damage to the tool or necessarily making the tool inoperable; whereas similar variations in valving characteristics cannot be tolerated in the case of the use of a noncompressible fluid.

Previously suggested drilling tools actuated by noncompressible fluids have generally been provided with two independent valves, one of which functions as the admitting valve, while the other functions as the exhaust ing valve. A particulaly troublesome problem with such tools has been the correct timing of the two valves in order to avoid unncessarily trapping fluid between the hammer and the anvil which may result in excessive pressures which would blow the seals employed or dampen the stroke of the hammer. The present invention solves the problem of timing independent valve functions by the use of a single valve system which serves the function of both an admitting valve and an exhausting valve. By the employment of a single valve system, the problem of trapping a noncompressible fluid within the tool is thus eliminated.

Itis an object of the present invention to provide a percussive type drilling tool actuatable by a noncompressible fluid wherein admitting an exhausting valve functions are performed by a single valve system. This, and further objects of the invention, will be apparent from a reading of the following specification, taken in conjunction with the accompanying drawings.

In accordance with the invention, a percussive type drilling tool is provided with hammer means which is actuated on both the power and the return stroke by a noncompressible fluid. The hammer means delivers percussive blows to the drill bit by striking the upper end of the bit or the upper end of an anvil connected to the bit. The hammer means is provided with fluid passages therethrough and a unitary valve member which functions at one end as an admitting valve and at the other end as an exhausting valve. The use of a one-piece or unitary valve structure eliminates the problem of timing between an admitting valve and an exhausting valve.

In the drawings: FIGURE 1 is a view in cross section of a drilling tool t constructed in accordance with one embodiment of the invention.

FIGURES 2 through 5 are Views in cross section illustrating a portion of the casing of the tool of FIGURE 1, together with the lower end of the hammer and the upper end of the anvil along with the fluid flow passages and the valve member carried by the hammer. These figures illustrate a complete cycle of operation of the tool, showing the relative positions of the hammer, anvil, and valve member at critical stages during a cycle of operation.

FIGURE 6 is an enlarged view in cross section taken along the line 66 in FIGURE 1.

FIGURE 7 is a view in cross section taken along the line 7-7 of FIGURE 1.

FIGURE 8 is a view in cross section taken along the line 8-8 of FIGURE 1.

FIGURE 9 is a view in cross section of an alternative form of valve.

Referring to FIGURE 1, drill pipe 10 extends from the surface where it is supported and rotated by a rotary table in a drilling rig. Threadedly engaged to the lower end of drill pipe 10 is an elongated, tubular-shaped housing or casing 11. Secured near the lower end of housing 11 and adapted to slide longitudinally relative to the housing is a bit 12 which is threadedly engaged to anvil 13. Hammer 14- is positioned within housing 11 such that it may slide longitudinally relative to the housing in order to deliver hammer-like or percussive blows to the upper end of the anvil to drive the bit into the formation being drilled. The force necessary to drive the hammer on both its power or downward stroke and its return or upward stroke is provided by fluid flow through the tool which is controlled by valve member Zi) carried by hammer 14. Valve member is adapted to slide longitudinally relative to the hammer in order to control the admission and the exhaust of the drilling fluid flowing through the hammer. Valve 20 is a single, unitary structure which performs the functions of both an admitting and an exhaust ing valve. During the power stroke of the hammer, valve member 2t functions to block the flow of drilling fluid through the hammer and thus cause the drilling fluid to force thehammer downwardly into engagement with the upper end of anvil 13. During the return stroke of the hammer, valve member 20 is so positioned that it will permit drilling fluid to flow through and below the hammer to lift the hammer upwardly away from the anvil.

Casing 11 is provided with an internal, longitudinally disposed fluid flow passage which is of substantially the same internal diameter as drill pipe 10. Flow passage 30 terminates at its lower end in a downwardly and outwardly extending internal peripheral shoulder 31 which slopes into a lower straight bore 32, the diameter of which is greater than the diameter of upper fluid flow passage 30. Shoulder 31, as will hereinafter be explained, may serve as an upper stop for hammer 14, that is, it may function to limit the upward movement of the hammer. Extending a through casing ll into bore 32 through shoulder 31 is a bleed port 33, the function of which will be explained in more detail below.

Threadedly engaged into the lower end of easing it is a nut 34 which is formed in two pieces, 35 and 36, shown in FIGURE 8. Nut 34 is provided with a plurality of longitudinally disposed splineways 40, which in the preferred embodiment illustrated are four in number. Positioned within the lower end of casing 11 is anvil 15 which is provided around its external surface with a plurality of longitudinally disposed splineways ll whici are equal in number and so aligned to register with splineways in nut 34. Positioned within splineways at) in the nut and in splineways 41 in the anvil are tubularshaped splines 51 which serve to transfer torque from casing 11 to anvil 13. The splineways in the anvil are somewhat longer than splines 51 in order to permit the anvil to slide longitudinally relative to casing Ill. Downward movement of the anvil is limited by outwardly extending fiange or shoulder 52 which is positioned to strike the upper end of nut 34. Upward movement of the anvil is limited by the engagement of the upper end of bit 12 with the lower end of nut 34. A fluid seal between the external surface of the upper end of the anvil and the internal surface of bore 32 is formed by ring seal which fits in groove 61 around the anvil.

Bit 12 is threadedly engaged to the lower end of anvil 13 and is provided with a plurality of fluid flow passages 65 which interconnect with central fluid flow passage 66 provided through anvil 13. While the anvil and the bit are shown in the preferred embodiment as two separate pieces, it will be recognized that the anvil and the bit may be a one-piece unitary structure. The anvil is secured into operating position within the lower end of casing 11 by first placing the splines 51 within the spline- Ways 4h provided in the two

halves

35 and 36 of nut 34 and assembling the nut and splines around the anvil, securing the two halves of the nut together by means of pins 67 which hold the halves of the nut in alignment and in position around the anvil until the nut is engaged within the lower end of the casing. The anvil is then inserted into the lower end of the casing and the nut is threadedly engaged with the casing as shown in FIGURE 1. Thus, there is provided a bit and anvil assembly which is rotatable by the casing 11 and which may slide longitudinally relative to the casing in response to percussive blows delivered by the hammer it.

The portion of the tool which provides the driving force against the anvil is hammer 14 which is disposed within casing 11 above the anvil. Hammer 14 has an upper neck portion 70 which is of such an outside diameter that it will form a sliding fit within bore 3i Fitted around the neck portion 79 of the hammer are a plurality of ring seals 71 which form a fluid seal between the external surface of the neck portion of the hammer and the surface of bore 30. Seals 71 may be of any material which will satisfactorily form a fluid seal between i the bore and the hammer but will permit the hammer to freely slide within the bore. The external surface of neck portion 70 of the hammer terminates at its lower end in an outwardly and downwardly extending shoulder 72 which may, during operation, engage internal shoulder 31 to limit the upward travel of the hammer within the casing. The annular space which exists around neck portion 70 within bore 32 when the

shoulders

31 and 72 are not in contact, that is, when the hammer is down a short distance, will be referred to as annulus 73. Bleed line 33 provides a vent through the easing into annulus 73 in order that the hammer may squeeze liquid outwardly through the casing on its upward stroke and to prevent the creation of reduced pressure around the hammer on the downward stroke which would hamper the downward or power stroke of the hammer. Below shoulder 72, the hammer is provided with straight external i surface 7d which is of such a diameter as to provide a sliding fit between this portion of the hammer and internal bore 32 to provide means for maintaining the alignment of the hammer within the casing. The hammer is provided around the surface 74 with a plurality of ring seals 74a which function to provide a liquid seal between this portion of the hammer and the internal surface of bore 32. Below straight portion '74 of the hammer is a portion 75 which is of a lesser diameter than the internal diameter of bore 32 in order to provide an annulus around portion of the hammer to permit fluid flow downwardly around the hammer to the lower end of the hammer.

Fluid flow through hammer l4 and valve 2% occurs through a series of fluid flow passages which will be described in detail below. Valve 2%, which is carried by and slidable relative to the hammer, functions in one position to block all fluid flow through the hammer, resulting in the fluid driving the hammer downwardly in its power stroke, and functions in another position to permit fiow through and around the hammer to the bottom of the hammer to lift it upwardly on its return stroke.

The upper end of hammer 14 is provided with a central fluid flow passage or bore which connects at its lower end with bores 86, which in the embodiment illustrated as in FlGUPrE 6, are two in number. Bores 36 comprise longitudinally disposed portions which interconnect with radially extending portions 361). bores 86 are spaced apart from the longitudinal axis of the hammer, as may be best observed in FIGURE 6. Disposed between bores 36 is an upper bore or valve chamber 37 which is adapted to receive the upper or admitting portion of valve 2%. Extending through the hammer connecting into the upper end of chamber S7 is a bleed line which functions to connect chamber 87' to annulus 73 to exhaust and admit fluid into chamber 37 during operation of valve 233. Bore 87 extends downwardly, interconnecting with lower valve chamber 39 which in turn interconnects with straight bore 9t) which opens through the lower end of the hammer. Bore as is of somewhat larger diameter than bore 87 for reasons which will be explained hereinafter. Valve chamber 89 is provided with an upper internal shoulder 91 which functions to limit the upward travel of the valve 29, and with a lower internal shoulder 92 which functions to limit the downward travel of the valve. Leading through the hammer from chamber $9 to the annulus 39 is a bleed port 93 to permit the entry and exit of fluids into the valve chamber during operation of the valve. As may best be seen in FIGURE 7, radially extending flow passages $5 extend through the hammer from bore or chamber 87 to permit fluid to flow from passages 36 through the valve outwardly from the hammer into annulus 89. Leading through the hammer from one of bores 86 into chamber 8% at lower shoulder 92 is a iiuid flow line 96 which serves a valve control function which will be explained hereinafter.

It is to be understood that the actual sizing of bores 86 and how passages $5 may be varied as desired to provide a minimum pressure drop in fluid flowing through the bores and fiow passages. it is not intended that FIG- URE 6 show the exact specific relative sizing for the bores and flow passages, the cross-sectional areas of which should total as near as practicable the cross-sectional area of bore 85.

Valve 20, which is an integral one-piece element, comprises upper admitting portion 1%, central enlarged portion 1M, and a lower exhausting portion M2. The upper portion 1% of the valve is somewhat smaller in diameter than lower portion 1% for reasons which will be explained hereinafter. Central enlarged portion 191 of the valve is provided with an upper shoulder lilla anda lower shoulder ltllb. As may be readily observed Portions 35a of from the drawings, the surface area of shoulder 101a is somewhat greater than the surface area of shoulder ltllb of the valve. The central enlarged portion 101 of the valve fits in sliding but substantially fluid-tight relation within chamber 89 of the hammer, while the admitting or upper portion 1% of the valve is operable within chamber or bore 87 of the hammer, and lower or exhausting portion 102 of the valve slides within bore 90 of the hammer. Upper portion Hill of the valve is provided with a series of interconnecting

fluid ports

103 and 104. When the valve and hammer are in the respective positions illustrated in FIGURES l, 4, and 5, ports 163 of the valve interconnect with fluid flow passages 95 in the hammer, while ports 1M of the valve are interconnected with fluid flow passages 86b of the hammer. Such interconnection permits fluid flow from passages 86 through the valve and outwardly through the hammer into annulus 89 around the hammer. When the valve is in an upward position, as illustrated in FIGURES 2 and3, ports 103 and 194 are raised into chamber 87, thus blocking all fluid flow from passages 36. It will be readily understood from observation of the drawings that various forms of construction for the lower end of the hammer may be employed in order to permit ready installation of the valve within the hammer. The relative sizes of upper portion 1% of the valve and the bore 87 and the lower portion 102 of the valve and bore 9% should be such that the valve will readily slide within the hammer but there will be no appreciable fluid flow through either bore 87 or bore 90 around the valve. Also, the external surface of portion 101 of the valve fits in sliding but substantially fluid-tight relation within chamber 89. In other words, the valve should freely slide within the hammer and fluid flow should occur only through the proper ports as provided. The central bore 65 through anvil 13 is of substantially the same internal diameter as bore 9t? in order that lower portion N2 of the valve will fit in sliding but substantially fluid-tight relationship within the central bore. As will be explained in detail below, lower portion 192 of the valve enters the central bore of the anvil momentarily subsequent to the hammer striking the upper end of the anvil during the power stroke.

A modified form of valve 20 is illustrated in FIGURE 9. In this embodiment of valve 20, the valve is provided with a fluid flow line 1&5 which extends through the body of the valve to provide fluid communication through the valve from below ports 1% and 104 to below enlarged portion 101 through shoulder 10112. Fluid flow line 105 performs a function identical to the function of fluid flow line 96 in the hammer. When desired, valve 20 may be provided with fluid flow line 105 in lieu of providing a fluid flow line 96 .through the hammer.

. Both fluid flow line 96 and flow line 1&5 function to provide fluid pressure from a bore 86 to lower shoulder 1411b within chamber 39. As will be explained hereinafter, this pressure on shoulder 10112 aids to insure complete valve closure on the upstroke of the hammer and valve.

The operation of a drilling rig equipped with the present invention does not differ in any substantial way from the operation of one which is provided with conventional drilling equipment. In drilling with conventional rotary equipment, the functions of the drilling fluid normally include flushing cuttings from the hole, cooling the drill bit, and providing a hydrostatic head in the hole. In the operation of a drilling rig equipped with the present invention, the drilling fluid performs the additional function of eflecting alternating percussive blows against the upper end of the bit as the bit is rotated. By virtue of the operation of the unitary valve employed, the drilling fluid is caused to drive the hammer downwardly into contact with the anvil and also to lift the hammer upwardly away from the anvil. While a detailed description of the complete cycle of operation of the tool of the present invention will begin with the initiation of the power stroke, it is to be understood that the unique features of the tool make it self starting, that is, it will start upon initiation of flow of drilling fluid through it, irrespective of the positions of the hammer and the valve.

A complete cycle of operation of the tool is illustrated in FIGURES 2 through 5 which show the various relative positions of the valve and hammer at different critical steps in the cycle of operation. At all times during the cycle of operation of the tool, upper valve chamber 87 and annulus 73 are at the pressure of the wellbore around casing 11 at the level of bleed line 33. This is true because of the connection of chamber 37 with annulus 73 by line 38 and, in turn, the connection of annulus 73 with the interior of the wellbore around the casing through bleed line 33. The position of the hammer relative to the anvil and the position of the valve relative to the hammer at the initiation of the power or downward stroke of the hammer are illustrated in FIG URE 2. The hammer is at the upper end of its line of travel within the case, and the valve is at its uppermost position within the hammer, that is, upper portion of the valve is retracted into and substantially encased within upper chamber 87. With the valve fully retracted into the hammer, the lower end of the valve is substantially flush with the lower end of the hammer and upper portion 1% of the valve is sufficiently retracted into chamber 87 that only the solid portion of the upper end of the valve below

ports

103 and 104 is exposed to channels 865 within the hammer so that no fluid flow through the hammer can occur. Fluid pressure is exerted through line as to below portion 161 of the valve which. aids in holding the valve in an upward position. With no flow of drilling fluid through the hammer, the full pressure and weight of the column of drilling fluid is exerted against the upper end of the hammer, resulting in the hammer being driven downwardly into contact with the anvil. When the lower end of the hammer strikes the upper end of the anvil, as shown in FIGURE 3, the

anvil and bit are driven downwardly with the bit biting into the face of the formation. During the entire downward or power stroke of the hammer, the lower end of the valve remains flush with the lower end of the hammer and thus drilling fluid which is between the lower end of the hammer and the upper end of the anvil is substantially exhausted downwardly and outwardly through central bore 66 of the anvil. When the lower end of the hammer strikes the upper end of the anvil, delivering the percussive blow to the bit, the valve continues downward movement with lower end 102 of the valve being introduced into the central bore of the anvil until such time as shoulder 10112 of the valve engages internal shoulder 92 'within chamber 89 of the hammer, as shown in FIGURE 4, thus ending the downward movement of the valve and sealing oil the central bore of the anvil to further fluid flow. The downward movement of the valve to itslowermost position is effected very abruptly due to both the momentum of the valve and a diflerenti-al of fluid pressures acting upon the upper and lower ends of the valve. At the moment the lower end of the valve enters the central flow passage of the anvil with the fluid flow or exhaust of the fiuid below the hammer being cut oil, the column of fluid withinthe central passage of the anvil continues downwardly, creating a reduced pressure within the central flow passage of the anvil below the lower end of the valve. At this same time, the upper end of the valve within chamber 87 is subjected to the positive pressure existing around the casing of the tool by virtue of the bleed lines 88 and 33 and annulus 73, as previously described. The presence of the decreased pressure below the lower end of the valve, together with the pressure at the upper end of the valve within chamber 87, assists the momentum of the valve in effecting the sudden movement of the valve to its lowermost position. Pressure within chamits downward movement into the anvil.

. the central bore of the anvil.

her $9 through line 9% will be offset by an increase in pressure within the chamber 89 through line 93 above portion ltll of the valve. This will further aid its downward movement. FIGURE 3 illustrates the relative positions of the valve, hammer, and anvil at the moment the hammer strikes the anvil before the valve begins FIGURE 4 illustrates the hammer still in contact with the anvil but with the valve moved to its downwardmost position relativeto the hammer into the anvil. I

With both the hammer and the valve at their lowermost respective positions, the power stroke of the cycle of operation of the tool is thus completed and the hammer is ready to be returned upwardly to begin another power stroke. The relative positions of the various elements of the apparatus at this stage in the cycle of operation may best be observed by reference to FIG- URES 4 and 7. It will be noted by an examination of these figures that ports N4 of the valve are interconnected with flow passages 35b of the hammer and ports 103 of the valve are interconnected with flow passages 95 of the hammer. Flow passages 95 lead into annulus M which extends to the upper end of the anvil below the lower end of the hammer. Flow of fluid may not occur, however, through the anvil by virtue of the fact that lower portion m2 of the valve is fully introduced into Flow may thus occur through the hammer downwardly to the space between the lower end of the hammer and the anvil. Specifically, the path of flow of the drilling fluid through the hammer at this stage in the cycle of operation is as follows. The drilling fluid flows from the drill pipe into bore 35) of the casing :and from there into bore 35 at the upper end of the hammer. From bore 85, the drilling fluid flows through portions 36a and 86b of the flow passagesfi, from which the fluid flows into valve 2t) through ports 1% and outwardly from the valve through ports M3 into flow channels 5. Prom flow channels 95, the fluid flows into annulus Sit and downwardly around the hammer to between the lower end of the hammer and the upper end of the anvil where the pressure within the drilling fluid is exerted between the upper end of the anvil and the lower end of the hammer. There will, of course, be some flow of drilling fluid through passage 93 into valve chamber 89. Since the drilling fluid cannot go through the anvil by virtue of the downward position of the valve, as shown in FIG- URE 4-, the pressure of the fluid on the lower end of the hammer starts the hammer moving upwardly. The crosssectional area of the lower end of the hammer is greater than the cross-sectional area of the upper end of the hammer, resulting in the upward force on the hammer being greater than the downward force on the hammer causing its movement upwardly. Theupward movement of the hammer continues until the lower end of portion 102 of the valve is withdrawn from the central bore of the anvil. At the moment of withdrawal of the lower end of the valvefrom the central bore of the anvil, the flow of drilling fluid begins through the bore of the anvil, and thus the pressure of the drilling fluid is exerted on the lower end of the lower portion of the valve. With the pressure of the drilling fluid now being exerted upon the lower end of the valve, the valve begins movement upwardly relative to the hammer, which movement is effected due to both momentum of the valve and a differential of pressures acting upon the ends of the valve. It must. be remembered again at this point that upper chamber 87' above the upper end of the valve is connected through to the outside of casing 11, and thus the pressure at the upper end of the valve is lower than the pressure below the valve and the hammer by virtue of both the lower hydrostatic head at the elevation of bleed line 33 and. the loss of pressure in the drilling fluid due to its flowing through the remaining portion of the tool and upwardly around the outer casing of the tool. The

fluid pressure within chamber 89 will be substantially the same as the fluid pressure below the lower end of the hammer and the lower end of the valve. It will be recognized, then, that the fluid pressure acting on shoulder lulu will be canceled by the sum of the fluid pressures acting on shoulder ltllb and a portion of the area on the lower end of the valve. The net pressure eltect causing the valve to move upwardly at this point is, therefore, the differential in the pressure acting on the upper end of the valve in chamber 37 and the pressure acting on an equivalent area on the lower end of the valve, with the pressure on the lower end area being in excess of the pressure on the upper end. At this point, any pressure through line 96 or line 195, if the form of valve in FlGURE 9 is used, will be approximately the same as the pressure being exerted through line 93 and thus will not aflect valve operation at this stage. This upward force on the valve will continue until the valve has been forced into, or the valve is retracted into, the hammer to the point where the ports M93 and N4 in the upper end of the valve are complete- 1y enclosed within chamber 87, and thus fluid once again is prevented from flowing through the hammer. At this point, shoulder llfllla on the valve will be in contact with shoulder 91 within chamber 89, and the lower end of the valve will once again be flush with the lower end of the hammer. The hammer will stop its upward travel because of the cessation of fluid flow through it and reduction in fluid pressure below the hammer so that the valve is in its vfull upward position and the hammer is at the upper end of its return stroke and is in position to once again start a power or downward stroke. With fluid flow completely shut off through passages 86, the hammer will once again begin a downward or power stroke due to the pressure of the drilling fluid on its upper end. During the upward stroke of the valve, any fluid which may be within upper chamber 87 will flow through bleed line 38 into annulus '73 and thence through bleed line 33 to the outside of casing 11. While it would appear from casual observation that as the valve moves upwardly and the ports in the upper end of the valve approach the closed position there might be sufficient throtting of the fluid flow to reduce the fluid pressure below the hammer and lower end of the valve to the point to prevent complete valve closure, it is to be understood that the mass of the valve is sufficient that its upward momentum will carry the valve to the point of complete port closure to put it in the position for the beginning of another cycle of operation. Also, the provision of line 96 through the hammer, or line 105 in the valve, if the form of valve shown in FIGURE 9 is employed, will provide a fluid pressure on shoulder 10112 to supplement momentum in forcing the valve upwardly. This pressure is not cut ofl by. the closure of the valve. It is to be understood that in order to exert this pressure on shoulder 3.011) from passage 86 when the valve is closed, it is necessary only to provide either a line 96 or a valve as shown in FIGURE 9. Both lines are not required. If the valve of FIGURE 9 is used, line 105 will conduct the pressure of the fluid in. passage 86 to shoulder ltllb when the valve is in a closed'positio-n.

If it is not desired to use fluid flow line 96 through the hammer or fluid flow line 105 through the valve, the valve may be rendered operable by forming the enlarged portion 101 of the valve such that fluid flow may occur along the sides of the enlarged portion within lower chamber 89. This may be done by providing longitudinal grooves in the side wall of portion 101 or by making the diameter of portion 101 slightly smaller than the internal diameter of chamber 89. If this form of construction is used for valve Zll, the valve will move more freely within chamber S9, allowing momentum alone to effect the final stage of the upward movement of the valve without the necessity of providing pressure to shoulder lllib through a line, such as

flow line

96 or 105.

With the functions of an admission valve and an exhaust valve being combined into a single, unitary valve structure, the necessity for the correlation of the movements of two or more independent valve systems has thus been eliminated.

While the invention has been described in terms of the specific embodiments disclosed herein, it is understood that other designs will occur to those skilled in the art and it is intended that the invention shall be limited only within the scope of the appended claims.

What is claimed is:

1. In a fluid-actuated percussion drilling tool which includes in combination an outer casing, an anvil slidably secured within the lower end of said casing and adapted to support a drill bit, said anvil having a flow passage to conduct drilling fluid to said bit, and a hammer element slidably positioned within said outer casing above said anvil and adapted to deliver percussive blows to the upper end of said anvil, said hammer element having at least one fluid flow passage to conduct fluid through said element to the lower end thereof and a chamber opening through the lower end of and interconnecting with said flow passage in said element, the improvement which comprises a unitary valve structure slidably positioned within said chamber in said hammer element, said valve structure having an upper solid portion and fluid flow ports adapted to coact at alternate slidable positions with said fluid flow passage within said hammer element to control the flow of drilling fluid through said hammer element, said valve structure being further provided with a lower solid portion extendable below said hammer element at one position of said valve structure to coact with said flow passage in said anvil to control the flow of drilling fluid through said anvil.

2. In a fluid-actuated percussion drill which includes the combination of outer casing means, anvil means slidably secured within the lower end of said outer casing means and adapted to support a drill bit, said anvil means being provided with a flow passage to conduct fluid to said bit, and hammer means slidably positioned within said outer casing means above said anvil means, the lower end of said hammer means being adapted to deliver percussive blows to the upper end of said anvil means, said hammer means being provided with at least one fluid flow passage to conduct fluid through said hammer means to the lower end thereof and with a chamber opening through the lower end of and interconnecting with said flow passage through said hammer means, the improvement which comprises single valve means slidably positioned within said chamber in said hammer means, said valve means being provided at one end with means for effecting at a first position of said valve means flow stoppage through said fluid flow passage in said hammer means to cause fluid pressure above said hammer means to drive said hammer means downwardly into contact with the upper end of said anvil means, said valve means being also provided near said end with means for permitting at a second position of said valve means fluid flow into said flow passage in said hammer means to the lower end thereof to permit fluid pressure to drive said hammer means upwardly, and said valve means being further provided with means at the other end thereof adapted to coact at said second position with said flow passage in said anvil means to stop the flow of fluid through said anvil means while said fluid pressure drives said hammer means through an upward return stroke.

3. In a fluid-actuated percussion drilling tool which includes in combination an outer casing, an anvil slidably secured within the lower end of said casing and adapted to support a drill bit, said anvil having a flow passage to conduct drilling fluid to said bit, and a hammer element slidably positioned within said outer casing above said anvil and adapted to deliver percussive blows to the upper end of said anvil, said hammer element having at least one fluid flow passage to conduit fluid through said element to the lower end thereof and a chamber opening through the lower end of and interconnecting with said flow passage in said element, the improvement which comprises a unitary valve structure slidably positioned within said chamber in said hammer element, said valve structure having an upper solid portion and fluid flow ports adapted to coact at alternate slidable positions of said valve structure with said fluid flow passage within said hammer element to control the flow of drilling fluid through said hammer element, said valve structure being further provided with a lower solid portion adapted to coact with said flow passage in said anvil to control the flow of drilling fluid through said anvil, and said drilling tooling being provided with passage means extending through said hammer element and said outer casing to subject the upper end of said valve structure to the fluid pressure within a borehole surrounding said outer casing during drilling.

4. In a fluid-actuated percussion drilling tool which includes in combination an outer casing, an anvil slidably secured within the lower end of said outer casing and adapted to support a drill bit, said anvil being provided with. a fluid passage to conduct drilling fluid to said drill bit, and a hammer element slidably positioned within said outer casing above said anvil and adapted to deliver percussive blows to the upper end of said anvil, said hammer element being provided with at least one fluid flow passage to conduct fluid through said element to the lower end thereof and a chamber opening through the lower end of and interconnecting with said flow passage in said element, improvement which comprises a single valve structure slidably positioned within said chamber in said hammer element to control flow of fluid through said hammer element in order that said fluid may actuate said hammer element, said valve being provided with ports through the upper portion thereof to permit at a first position of said valve fluid flow through said flow passage in said hammer element and a solid portion below said ports to block at a second position of said valve fluid flow through said hammer element, said valve being provided at the other end thereof with a solid portion adapted at said first position to extend below said hammer to coact with said flow passage in said anvil to control fluid flow through said anvil, and said valve being additionally provided with an enlarged central portion between said upper and lower solid portions for limiting the upward and downward travel of said valve Within said hammer, said enlarged central portion fitting within said chamber in said hammer.

5. The apparatus of claim 4 wherein said hammer ele ment is provided with a fluid flow passage to provide the lower end of the enlarged central portion of said valve with the fluid pressure existing above said hammer element.

6. The apparatus of claim 4 wherein the cross-sectional area of the upper end of said valve is less than the crosssectional area of the lower end of said valve.

7. Apparatus of the character described in claim 4 wherein said valve is further provided with a fluid flow passage opening through the upper solid portion of said valve below said ports and extending to and opening through the bottom of said central enlarged portion.

8. A fluid-actuated percussion drilling tool which comprises in combination an outer casing adapted to be secured to the lower end of a string of drill pipe, said casing having interconnecting upper and lower internal bores, the cross-sectional area of said upper internal bore being less than the cross-sectional area of said lower internal bore, an anvil secured within the lower portion of said lower internal bore and adapted to slide relative to and be rotated by said casing, said anvil being provided with a longitudinal flow passage and bit securing means, a hammer slidably secured within said casing above said anvil and adapted to deliver percussive blows to the upper enemas l 1 end of said anvil responsive to fluid flow through said tool, said hammer having a lower portion fitting Within and spaced apart from said lower bore of said casing and an upper neck portion fitting within said upper bore of said casing, at least one ring fitted around and near the upper end of said lower portion of said hammer, at least one ring seal positioned around the upper external surface of said neck portion of said hammer, said ham- Iner being provided with a central flow passage extending downwardly through said neck portion interconnecting with longitudinal flow passages spaced apart from the longitudinal axis of said hammer and terminating within the lower portion of said hammer below said ring seal around the upper end of said lower portion, said hammer being also provided with radial flow passages below said external seal interconnecting with said longitudinal flow passages, said central flow passage with said longitudinal and radial flow passages providing a path for fluid flow from above said hammer into an annulus between the lower portion of said hammer and said lower bore of said casing, said hammer being further provided with an upper valve chamber positioned above said radial flow passages and an interconnected lower valve chamber positioned below said radially extending flow passages, said lower valve chamber being interconnected with a longitudinal bore provided in said hammer extending through the lower end of said hammer, a bleed port through the wall of the lower portion of said hammer leading into said lower valve chamber, said hammer and said casing being provided with port means interconnecting the upper end of said upper valve chamber and the exterior of said casing above said ring seal around the lower portion of said hammer, and a single valve element having an enlarged central portion positioned within said lower valve chamber in said hammer and solid upper and lower portions adapted to fit within said upper valve chamber within said hammer and through the lower end of said hammer into said longitudinal flow passage in said anvil respectively, the upper end of said upper solid portion of said valve element being provided with a plurality of ports adapted to interconnect said longitudinal flow passages and said radial flow passages in said hammer when said valve is in open position, said valve being adapted to slide longitudinally relative to said hammer to cause fluid to actuate said hammer through both downward and upward strokes.

9. Apparatus of the character described in claim 8 wherein said hammer is provided with a fluid flow passage extending from one of said longitudinal flow passages to the lower end of said lower valve chamber.

10. Apparatus of the character described in claim 8 wherein said valve element is provided with a fluid flow passage extending through the body of said valve element from below said ports in said upper solid section to the lower end of said enlarged central portion.

Zublin May 31, 1932 Pennington Dec. 27, 1932 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 167 ,136 January 26 l96 Evin L. Cook It is hereby eertified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 56, for "particulaly" read particularly column 10, line 15, for "tooling" read tool line 24 after "fluid", first occurrence, insert flow same colum 10, line 32, after "element," insert the column 11, lin 5, after "ring" insert seal Signed and sealed this 6th day of July 1965.

(SEAL) Altest:

ERNEST W. SWIDER EDWARD J. BRENNER A'ttesting Officer Commissioner of Patents