US2742267A - Pilot controls for pneumatic cable-tool drills - Google Patents

Description

April 17, 1955 J. H. MEIER 2, 6

PILOT CONTROLS FOR PNEUMATIC CABLE-TOOL DRILLS Filed Jan. 25, 1952 4 Sheets-Sheet l JOHANN HANS Mama,

INVENTOR.

ATTORNEY April 17, 1956 J. H. MEIER 2,742,267

PILOT CONTROLS FOR PNEUMATIC CABLE-TOOL DRILL-S Filed Jan. 25, 1952 4 Sheets-Sheet 2 l i re i I I 5 l I l 66 I l i i l i l 1 g l 52 I I I y A 3 6 45 4 o 5% 3 1 JOHANN HANsMEIER, j 42 INVENTOR.

ATTORNEY- J. H. MEIER April 17, 1956 PILOT CONTROLS FOR PNEUMATIC CABLE-TOOL DRILLS Filed Jan. 25, 1952 4 Sheets-Sheet 4 JoHANN HANS MEIER,

INVENTOR.

AITORNEY.

. PILOT CONTROLS FOR PNEUMATIC CABLE-TOOLDRILLS Johann Hans Meier, South Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis., a corporation of Delaware Application January 25,1952, Serial No..268,301

8 Claims. (Cl..255-10) -This" invention relates to new and useful improve:

ments in operating'controlsfor pneumatic-type cable- 'bit. The drilling tools at the end of therope are reciprocated up and down by oscillation ofcable-engaging means, suchas a crown sheave, which is slidably mounted 'in the 'mast'and is actuated by a pneumatic cylinder-piston assembly.

. The principalobjects of my inventionare to provide a pilot system for controlling the-intake and exhaust of air (or gas) to and from. the piston chamber such that (1) The intake and exhaust valve system of the cylinder-piston assembly 'has only two controls, both depending, through novel interlocked pilot means, on the motion of the piston.

(2) The controls are greatly simplified by using the position of the exhaust valve as a partial pilot means for actuating the intake valve. t

(3) Cycle time is reduced by automatically exhausting air from the cylinder chamber before the piston reaches the top of the tool-lifting stroke, thuseliminating the last, inefficient part of the expansion portion of the cycle. t a

(4) Fast response of the intake and exhaust valves is obtained.

.(5) The controls are simple andinexpensive to build andoperate.

In addition to the principal objects, above stated, a number of novel and useful details havebeen worked out which will be readily evident as the description progresses.

The invention consists in the novel parts and in the combination and arrangement thereof, which are defined in the appended claims, and of which two embodiments are exemplified in the accompanying drawings which are hereinafter particularly described. and explained.

Figure l is a side elevation of a drill embodying the invention.

Figure 2 is an enlarged partly schematic representa-' tion of the cylinder-piston assembly, the intake and exhaust valves therefor, and the air-pilot controls for said valves, together with the closed pneumatic circuit connecting such elements to each other and to the receivers and air compressor.

Figure 3 is an enlarged vertical sectional view of the intake valve.

Figure 4 is an enlarged vertical section, similar tov the main cylinder chamber and the operation of mean pilot control valves, the exhaust valve, and the intake valve for various positions of the main piston in its operating cycle. l l v Figure 6 is an enlarged partly schematic representationof the cylinder-piston assembly, the intake and exhaust valves therefor, and a second embodiment of the pilot controls for said valves, together with their electrical circuit.

Turning now to Figure l, we see that 11 is the main frame of a drill, supported by creeping traction 12.

The frame 11 supports a mast 14 (called a' derrick in the art), a motor 15, 'a winch 16, a main air compressor 17, and associated driving connections (not numbered).

Fr0m the winch 16, arope 18 runs around spooling sheave 19, thence under fairlead sheave 2i), thence over crown sheave, 21 at the top of the mast 14, thence down to the tools 22. Crown sheave 21 rotates about pin 23 mounted in a crown-sheave frame 24 which is slidably mounted for vertical movement within the upper section 25:; of the mast and is connected to the end of piston rod 26 of cylinder-piston assembly 27. Crown sheave 21, withits actuating cylinder-piston assembly 27, con

stitutes a cable-engaging spudding means for imparting vertical reciprocating motion-to the drilling tools 22.

Turning to Figure 2, cylinder-piston assembly 27 consists of cylinder 28 mounted within section 25b of mast 14, and main piston 29 to which rod 26 is connected. The cylinderpiston assembly 27 is single-acting, the pressure chamber 30 being located below the piston 29. The air in the pressure chamber 30 is controlled through intake valve 32 and exhaust valve 33. Air pressure is supplied to intake valve 32 through main supply line 35 from the high-pressure receiver 36 which in turn is supplied with air pressure by the air compressor]?! through line 37.v Exhaust air is conducted from exhaust valve 33 through-main exhaust line 39 to low-pressurereceiver 40, pressure in which is maintained by auxiliary air compressor 41. Low-pressure receiver 40 is in turn connected through main supply line 42 to the intake of main air compressor 17. Thus it is seen that the air system for actuating cylinder-piston assembly 27 is a' closed system. Upper chamber 31 of cylinder-piston assembly 27 is maintained normally at atmospheric pressure by vent 34. The area of this vent is preferably restricted to permit throttling or bumper action if main piston 29 overspeeds because of too light tools or breakage of the tool line. To dissipate the energy of the tools when'dropping freely from full'stroke without striking the bottom of the well, a shock absorber or resilient bumper 38 is preferably employed at the lower end of and inside the cylinder 28.

The intake valve 32 and the exhaust valve 33 are controlled by the following described automatic air-pilot control mechanism to which the invention is principally lines of the above-described closed circuit for supply ing airto the cylinder-piston assembly 27. To clarify the air'epilot control circuit, the following conventional single lines are used. A single full line represents a pilot line that is always under high pressure. A single line of dashes indicatesa line that is under either high or low pressure depending on the positions of the manual control and air-pilot valves. A single line of dots anddashes indicates apilot line that is always under low pressure.

The supply of air pressure to the lairpilot 'controlsys pressure is supplied to this valve from high-pressure receiver 36 by line 50 to intake port 51 on valve A. When the plunger 54 of main-control valve A is in raised or open (high pressure) position, as shown in Figure 2, air under pressure flows'through port 51, annular recess 55; center port 52; and high-low pressure line 56 to intake port 61 of intake-cutoff-control air-pilot valve B and to intake port 71 of exhaust-cut-otl-control air-pilot valve C. When the plunger, 54 of valve A is in lowered closed position (not shown) it blocks oif intake port 51 and connects center port 52 to exhaust port 53 through annular recess 55, port 53 being, connected by low-pressure line 51' to the low-pressure'receiver 40..

The plunger 54 of manual-control valve A is actuated, through link 46, by operating lever '44 which is pivotally mounted on fulcrum 45' located preferably near the base of the machine.

Main-control valve. A controls. supply of pressure fluid through line 56. to intakc-cutofi-control air-pilot valve B and to exhaust-cutoff control air-pilot valve C, both of which valves are actuated by cam 58 on piston rod. 26.

Intake-cutofi air pilot valve. B is the principal piloting means for controlling the intake valve 32. It is actuated by cam surface 58a of cam 58,, which. bears against roller 60 mounted on the end of plunger 64.. At the start of they up-strokeof the main piston assembly 29, roller 60" bears. against the upper portion. 58a of cam surface 58a, so that the plunger 64 is in open position (shown in Figure 2).. In this position, air under pressure from port 52. of main-control valve A flows through. line 56 to intake port 61 of valve B, thence through annular recess 65, center-port 62, and line 66- tointake port 81 of-airpilot valve D on exhaust valve 33, and thence throughvalve D to intake valve 32- as will be described hereinafter. When the mainpiston 29yrises to the upper portion of-itsstroke, roller 60 bears against the lower portion 58a of cam .surface58a, so that plunger 64' of. valve B is advanced byspring 68 into cut-off position. In. this position, port- 61- is blocked oh by plunger 64, and

ports 62 and63are interconnected through recess 65; so

that line 66- aswellras the recess 65- itself is connected through line. 6710- low pressure' receiver 40; In thisway,

73 are interconnected through recess 75, so that line 76', as well as recess 75; is connected through line 77 to low-pressure receiver 40. In this way any leakage into valve C is conveyed to the low-pressure receiver 40.

Turning now to Figure 4, which is an enlarged view of exhaust'valve 33 and air-pilot control valve D, it will be seen that the exhaust valve is preferably a spring- 7 opened, air-pilot closed valve; in order to drain any leak= any leakage ineither air-pilot valve B or air-pilot valve D is conveyed; to the low-pressure receiver, and-com.- pressed: air inthe pilot: system beyond line. 66 is drained 01f causing intake. valve 321to close. V a

In order to'vary the. length of stroke of the. main piston 29.; by'varying: the cutoli' point at which valve: 8 cuts ofi; air pressure. actuating intake valve 32, air-pilot valveB isslidably mounted on mast 14,. soithat its. verti- V cal position can be. varied. at will. by operating lever 44 which isconnected: to valve. B by link 69. This arrangement permits the operator; to gradually increase the: length, of the main piston stroke as he starts the machine by opening main-control valve A. In this way themachine can be started smoothly, and the number of operating controls is reduced to a minimum. I

Exhaust-cutoif air-pilot. valve C is the piloting, means for controlling the exhaust valve 33. It is actuated by cam surface 58b vof cam 58, which bears against roller 70 mounted on theendof plunger 74 At the bottom-ofthe stroke. of; the mainpiston 29,roller 7t) bears against theupper portion 58b of cam surface 58b, sothat the plunger 74-is advanced to open? position. In; this position, air under pressure from port 52 of. main. control valve A 7 can flow through line 56 to intake port 71 of. valve C, andthence through annular. recess 75,.center port.72, and

line-76. to port 91 of actuating chamber 93v of exhaust valve 33,. When the. main piston 29 rises. above its near.- bottom. positionto. the positionrshownin Figure 2;v roller.

' bears against the. lower. portion 585." of cam surface. 7

age air from main cylinder chamber" 30 to low pressure receiver 40 when machine is at rest. Pilot-air pressure admitted through line 76 (Figure 2) q and port 91 to actuating chamber 93 acts against the lower: face. of plunger 84 and lifts the plunger with stem 94, thus compressing spring 98' and pressing'valve discs 95a and 95b against their seats 96a: and 96b, respectively, and so closing exhaust valve 33. Valve disc 95b is larger than valve disc 95a, and hence any air pressure in main cylinder chamber 30 imposes. a net force on the valve discs, such force. tending to keep exhaust valve 33 closed. Aslong as this net force is greater than the reaction ofcompressed spring. 98;. the valve 33' stays closed, regardless of the pilot-air pressure in actuating chamber 93. There-- fore, even if pilot-air pressure is drained. from actuating chamber 93 once closed, exhaust valve 33 stays closed until the air-pressure in main cylinder chamber 30' drops below the air pressure required to balance the reaction (pre detemined by adjusting screws 99) of spring 98; and once open; exhaust valve 33 stays openuntil pilot-air .presF sure is admitted to actuating chamber 93. Any leakage air in; the compartment for spring. 98! is drained to.theilowpressure line 39 by axial passage 92 in valve stem 94'.

Air-pilot valve D is the auxiliary piloting means: for controlling the intake valve 32. Pl'unger 84 of air pilot valvev D is integral with stem 94 of exhaust valve" 33. When, exhaust. valve 33-is1 inzit's' open position, pilot air pressure at intake port 81'. of air-pilot valve D is'bl'ocked by plunger 84,- andcenter port 82 is connected to exhaust port 83 through annular recess in plunger 84.

When exhaust 'valve- 33" is in; its colsed position, intake port 81 of air-pilot valve D is connected to center port 82 through annular: recess 85 of plunger 84, and exhaust port 83 is blocked.

Turning to Figure 3, which is an enlarged view of intakevalve 32'. andzitsiactuating piston 104; it will be seen that; this valve ispreferably a spring closed pilot'airopened valve; in. order t'opermit building upair pressure at the start of thedrillingoperation: To open the valve,

'pil'ot' valve D- and center port 82 of air-pilot valve D' is connected through line 86 to intake port 101 andactuat ing'chamber 1030f intake valve32. Exhaust'port 83 ofair-pilot valve D" is connected to-low-pressure receiver'40 pilot valve B and air-pilot valve D (which are connected" in series). on control of the intake valve 32 is that the intake valve 32 is closedautomatically byits spring Hi8 whenever pilot air pressure leading into-its chamber 103' is cut off-"and drainedby pilot=valveB When-the'main piston-29 is above a selectedcut-off point determined by the relative position of pilot valve B and cam 58". When main piston'29"isbelow'this predeterminedcutoflf point, pilot valve B. admits pilot air pressure to pilot valve"D';' if then the exhaust valve. 33"is closed (during upstroke), pilot valve transmits this pilot air pressure to intake valve 32' thereby holding the. same open; but'if, however, the ex haust' valve-33' is open (during downstrok'e'), valve D g I v in the entire pilot-air system. Pilot valves B and C are in open position, their ports 61 and 71 respectively being open, but. pilot valve D is closed, its port 81 being blocked off, since exhaust valve 33 is held open by its spring 98.

Accordingly the intake valve 32 is held closedby its .spring 108 and thedifferential action of valve discs 105 a and'105b, and the air in chamber 30 of the cylinder-piston assembly is at the low p'ressureof the low-pressure receiver 40. f i i (2) Start (apward).Piston 29 is still at the bottom of its stroke, but main-control valve A is now open, and, since pilot valves B and C are also open, air pressure through port 91 of pilot valve D lifts plunger 84, so that exhaust valve 33 is closed and at thesame time port 81 of pilot valve D is uncovered permitting air pressure to flow through line 86 to actuating chamber 103 of intake valve 32, thereby opening it and causing pressure to build up in chamber 30, which in turn starts upward motion of main piston 29. V

(3) Early upstroke-(see Figure 2).--In this position of the upstroke main piston 29 ,is above its near-bottom position, but below its cutoff position. As in starting position, main-control valve A and pilot valve B are open, but pilot valve C is now closed, since its plunger 74 has now been returned to closed position by'the lower portion 58b" of cam 58b. Hence air pressure in actuating chamber 93 (Figure 4) of exhaust valve 33 is now low instead of high, but, in spite of this, exhaust valve 33 remains closed and pilot valve D remains open because oftthe remains open. But, since the roller 60 of pilot valve B.

has now passed the c'utofi point on cam 58a, port 61 is blocked Off and actuating chamber 103 of intake valve 32 is now connected, through pilot valves D and B, to lowpressure receiver 40, so that intake valve 32 automatically closes. Exhaust valve 33 remains closed due to internal pressure in the main cylinder chamber 30. 1

(5) Late upstr0ke.Piston 29 is now near the top 0 its stroke. Due to air expansion, pressure in the now sealed ofl main cylinder chamber 30 drops below the preset value necessary to hold the exhaust valve closed. Accordingly the exhaust valve 33 opens and the pressure in the cylinder chamber 30 drops to the low pressure of tank 40. Pilot valve D, also closes, but this does not atiect the intake valve, because pilot air pressure to the intake valve is already cutoff and drained by pilot valve B.

(6) Top and early downstr oke.ln this portion of the cycle, the piston is at the top of its stroke and above intake cutofi in itsdownstroke, the fall of main piston 29 being checked by the low pressure in chamber 30 and in the low-pressure receiver 40 to which it is connected. The amount of low pressure is adjusted to apply an upward force on the main piston 29 of slightly more than one-half, the weight of the piston and its rod 26, crown sheave 21 and frame 24, so. that a slight tension is maintained in rope 18. On the downstroke essentially free fall of the tool occurs. All valves are in the same position as in the previous case.

(7) Mid d0wnstr0ke.- --In this position, the piston 29 is just below intake cutofi position. When the piston passes intake cutofi position, pilot valve B opens, but air pressure supplied by pilot valve B to pilot valve D is blocked at port 81 because the exhaust valve is still open.

(8) Late downstroke.ln this portion of the cycle, the piston 29 is in near-bottom exhaust cutoff (i. e. closing) position, at which point pilot valve C is opened by cam 58b so that air pressure flows through port 91 into actuating chamber 93 of exhaust valve 33, trippingthe exhaust valve into closed position,- and at the same time uncovering port 81 of pilot valve D, so that intake valve 32 is opened, pressure is built up below main piston 29 and a new upstroke commences.

Air pressure in chamber 30 and the points at which the pilotvalves and the intake and exhaust valves are closed, during the above-described operating cycle of piston 29, are shown graphically in Figure 5, which is schematic and not necessarily to scale.

Although the invention has been described as operated by compressed air, other gases, such as steam can be used satisfactorily, and the claims are to be construed to cover such equivalents.

Furthermore, although I prefer, for safety reasons, to employ main control valve A in my air-pilotcontrol circuit, this valve can, if desired, be omitted and the position of pilot valve B below its cutofr point on cam 58a, with the main piston 29 in bottom position, can be relied on to stop reciprocation of the piston. Piston 29 can then be started by merely sliding pilot valve B above its cutofi position.

Furthermore, although pressure fluid is shown in Figure 2 as the medium through which the pilot means (valves B, C, and D) control the master (intake and exhaust) valves, it will readily be seen that, in its broad aspect,

the invention is equally applicable to the employment of other equivalent media, such, for example, as electrical means in which electrical switches are substituted for the pilot valves and serve to control the master valves through electrically-operatedsolenoids. Such an alternative embodiment'is shown in Figure 6.

In Figure 6, which shows the second embodiment of the invention, the electrical pilot control circuit, which is substituted for the pneumatic pilot control circuit of Figure 2, consists of an electrical power source 150, main control switch A',intake cutofl? control switchB', exhaust cutotf control switch C, exhaust-valve actuated switch D, intake valve opening solenoids 103, exhaust valve closing solenoid 193, and the necessary connecting lines as hereinafter described. l

Intake cutoff control switch B consists of a conducting bar 158a, which is connected to main control switch A, and of slidably mounted contactor 164. Conducting bar 15801 is mounted on piston rod 26 and corresponds to cam surface 58a of the first embodiment (Figure 2). Accordingly electrical contact exists between conducting bar 158a and contactor 164 when piston 29 is below its intake cutofi point as predetermined by the setting of slidable contactor 164.

.Exhaust cutoff control switch C consists of a conducting bar 1581; which is connected to main control switch A, and of contactor 174. Conducting bar 158b is mounted on piston rod 26 and corresponds to cam surface58b' of the first embodiment (Figure 2). Accordingly electrical contact exists between conducting bar 158b' and contactor 174 when piston 29 is below its exhaust cutoff point.

Exhaust valve actuated switch D consists of a contactor 184 connected by. line-166 to contactor 164 of switch B, and of contact plate 185 connected by line 186 to intake valve solenoid 203. Contact plate 185 is mounted on stem 194 of exhaust valve 133, so that plate 185 establishes electrical connection with contactor 164 when the exhaust valve is closed andinterrupts this connection when the exhaust valve is open.

Intake valve 132 is spring-closed, solenoid-opened. When electrical potential is applied to the solenoid 203 through line 186, armature 107 connected to valve stem 204 is pulled in, thus opening valve 132 and compressing spring 108. The electrical circuit is closed by line 187 from solenoid 203 to power supply 150.

Exhaust valve 133 is spring-opened, solenoid-closed.

amaze? When electrical potential is applied" to the; solenoid- T93 thren h li e 176 from contactor' fl t-of switch 6'', annata -e 197" eon eetea to valve stemj1-94- is pulled in, thus closing valv' 133=andcornpressing spring 198 The elect'r'ic'a-l circuit isclos'edby line 177 from solenoid 193 to power supply 150:

Operation ofthis electrical-pilot control is analogous te theair-pilot control efjthe first embodiment; At the bottorn'of the stroke, switches B" and C are eresemand since the 'closeds'witcha C holds exhaust valve 133 closed, switch D is also closed. The series=connected switches B and D being closed, the intake valve 132 is held open. Air pressure in main ylinderchamber ae anses inain piston-29 to rise. *When the exhaust cutoff point ispassetl,

switch C opens, but the exhaustvalve i'sfkept elesetr bv the high pressure in main cylinder chamber 30; Whenthe intake cutofiipoint is-p'as'sed, switch B opens; causing V inlet valve 13am close. 'Air in the new=sea1ed= fr main cylinder chamber- 30 expands, and when the air pressure drops below a predetermined" level, exhaust valve 13?: opens, thus opening switch D. Soon thereafter, piston 22? reaches the top of its stroke and begins to fall. When the intak eentet-r point is-passed; switeh efeleses, but current through the intake solenoid 203 still being interrupted at switch D the intake valve remains closed. When the piston passes the exhaust cutoff aint, switch- C closes, thus closing the exhaust'valve. ,This causes switch D'to close, whereupon intake valve 132 o ens;

' Having noW;d'escribed*and illustrated two forms of the a bit; pneumatic spudding meansjhaving a cylinder-piston assembly supporting said bit to" raise and d'r'op saidbit; apiston and a pressure chamber in said cylindefipiston' assembly, said chamber having associated 'withjita fl'uid pressure intake port andan exhaust port; an" intake valve to epenand -elose said 'intake'p'ort; an exhaust valve to open" and close said exhaust port; and means qperative'1veon= nected to said exhaust valve' toopen" and close said exhaust valve; a combination therewith o'f-i meansadapted to-open' and"cl'ose said intake'valve, said last-mentioned means comprising: first and second 'valve controlmeansopcratively connected to saidintalte'valve eaeh having port=closingand port-opening po'si'tions'to efreetelosing and opening of saidintake valve; istem e'sitienres en sivfe means connected to and operatedby said piston to actuate saidfirs't valve control' means to assume a por'tclosing position-When the piston reaches a predetermined intake cut-off position on it's bit-raising stroke; exhaust-v'alve-position responsive means connected to a'nd operated by said exhaust valve to actuate said second control means to assume a port-closing position when said exhaust valve is in open positionand to assume a port-opening position when said exhaust valve is 'in closed position; and interlock means connecting said first and second control means, said interlock means providing for independent operation of said first and second control means with res ect tothelr ortclosing function to cut oil intake of fluid pressure at sa d cut-oil position of the pistonon its bit-raising stroke andto cutoff intake of fluid pressure when the exhaust valve is open on the bit-lowering stroke of the piston, and vidingdependent operation of saidfirst and secondmentrol me'ans with respect to their portopenlngtfunct1on to etlect finid=pressure intake only during the portion of the bit-raising stroke in advance of said cut-off position of the istenand vvhen said exhaust valve is' closed. 2. A- eohtrol for a pn umatic cable-tear drill according to claim 1, further characterized by the fact that the intake valve is a .flHid-PTGSSUIE-Htlifltd' power-opening valve, and" that the interlock between the'first and second control means is a series fluidgp'ressllre circuit;

3, A control, for a pneumatic cable-tool drill according to claim 2, further characterized by the a ct that the first and second control means comprises'fiuid-pressure valves actuated by movement of the piston and by movement ofthe exhaust valve respectively. p v 4 4. A control for' a pneumatic cable-tool drill according to claim '1', further characterized b the fact that the assembly, said chamberh'aving associated with it a fluidpressure intake port'and an exhaust port; an intake valve to open and close sa'id intake port; an exhaust valve to open andclos'e' saidexhaust port; and'm'eans to open and close said intake valve; the combination therewith of: means adapted to' open and lose said exhaust valve, said last mentioned means comprises: first control means 0peratively connectedto'said' exhaust valve having port- I closing and sport-opening positions toeifect closing and opening of said exhaust valve; piston-position responsive means connected toand operated by said piston to actuate said first control means to assume a port-closing position when the piston reaches'aposition in advance of its normal position of reversal from a bit-lowering to a bit-raising stroke; and second fliii'd press ure responsive control means associated with the exhaust valve, said second control means being directly actuatedby fluid pressure in said chamber and including a fluid-pressure operating surface associated with said exhaust valve and dimensioned and biased by the fluid pressure in said chamber to. close said exhaustvalve when pressure in said chamber is above a predetermined value,

7. control for a pneumatic cable-tool drill according to claim '6, further characterized bythe' fact that the first control means comprises a fluid-pressure pilot valve actuated by movement of thepist'o'n.

' 8. A control for a pneumatic cab1e-tooldrill according to claim 6, further characteriied by thefact that the first c'ontrol'means comprises a pilot electrical switch actuated by movement of the piston.

References Cited in the file of this patent- UNITED STATES PATENTS

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