US 2473430 A
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June 14, 1949. s, HQFFAR PISTON COUPLING MECHANISM Filed May 19, 1945 ATTORNEYS INVENTOR. flea/y 5. //0ffar BY Patented June 14, 1949 PISTON COUPLING MECHANISM Henry S. Hofiar, near Sidney,
tion of Wisconsin British Columbia,
assignor, by mesne assignments, to Le Roi Company, Milwaukee, Wis.,
a corpora- Application May 19, 1945, Serial No. 594,653 2 Claims. (01'. 121-9) My invention relates to coupling mechanism, which may be employed, for example, in a rock drill feed arrangement for connecting to the drill a feed piston, movable lengthwise through a cylinder by the application of fluid pressure. My invention is, of course, applicable to fluid piston and cylinder drives used for other purposes.
My Patent No. 2,259,694, issued October 21, 1941, for a Diamond drill feed control, illustrates a representative feed mechanism for moving lengthwise rock drills of the diamond drill type, in which the cylinder housing the fluid actuated piston is located alongside the rotary drill motor. The coupling arrangement disclosed in that patent interconnecting the piston and motor has been found to have certain disadvantages, however, which are overcome by my present invention.
An object of my invention is to provide a short coupling which can directly interconnect drill mechanism, for example, and a feed piston received in a feed cylinder located alongside the drill mechanism. More specifically, the connecting element extends through a slot extending lengthwise of the feed cylinder. In efiecting such connection it is a principal object to provide a simple and effective seal for such slot.
An additional object is to enable such cylinder sealing arrangement to be utilized with a piston subjected to fluid pressure on both sides of it, and which can travel substantially from end to end of the cylinder, so that its effective stroke will be substantially coextensive with the cylinder length. A further object is to construct such a seal so that it may be installed and removed easily and quickly, enabling the piston to be withdrawn from the cylinder for purposes of repacking whenever desired.
Still another object is to provide a novel cylinder assembly and piston guide arrangement which will withstand high cylinder pressures, yet which is extremely simple in construction, dependable and efficient in operatiomand easy to install.
Other features of the embodiment of my invention wihch I now prefer will be discussed in the following detailed description and are shown in the accompanying drawing.
Figure 1 is a side elevation view of drill mechanism incorporating my invention, showing one wall of the cylinder and piston broken away along a diametral longitudinal plane.
Figure 2 is a view taken on line 2,2 of Figure 1, showing the drill mechanism in elevation and the cylinder in transverse section. Figure 3 is a fragmentary transverse sectional view through 2 the cylinder, piston, and coupling, taken on line 33 of Figure 1, and Figure 4 is a transverse sectional view through the cylinder taken on line 4-4 of Figure 1.
Figure 5 is a detail transverse sectional view through the sealing element, near its left end as seen in Figure 1.
It will be evident that a rock drill may be supported alongside a feed cylinder in various ways for movement of the drill relative to the cylinder. In my previous Patent No. 2,259,694, mentioned above, the drill motor was mounted on a saddle embracing the major portion of the periphery of the feed cylinder, as shown best in Figure 4 of that patent. An alternative supporting arrangement, illustrated in the accompanying drawings, also supports the drill from the feed cylinder.
The feed cylinder I may have integral with it the swivel mounting cone I0. Preferably at the side of the feed cylinder remote from this mounting cone is located the rock drill motor 2 which carries the drill rod 20 terminating in the bit 2I, represented as of the diamond type. The drill motor, which customarily is driven by compressed air, although not necessarily so, rotates the drill rod 20 as the motor is fed forward, to the right in Fig. 1. The drill motor 2 may be supported from the feed cylinder I by arched supports 22, each supporting one end of the drill, which straddle the feed cylinder to dispose their ends at its opposite sides, preferably substantially in a diametral plane of such cylinder. Rods I I, extending lengthwise along opposite sides of the cylinder, and carried by ears I2 projecting radially from opposite ends of the cylinder, pass through apertures in the ends of the arched supports 22. These rods serve both as supporting mechanism for mounting the drill motor, and guides for guiding its reciprocation lengthwise of the feed cylinder, substantially from end to end of it.
To effect movement of the drill motor 2, a feed piston 3 is received within the feed cylinder I, and coupled to the drill motor by a connecting plate 30 secured to or integral with the piston. This plate projects from the piston outward through a slot I3 extending lengthwise of the feed cylinder over substantially its entire length, and its outer end is received between projections 23 formed on the body of drill motor 2. Bolts 24 pass through such projections and interconnecting plate 30 to complete the coupling.
The problem of sealing slot I3 in the wall of cylinder I, through which connecting plate 30 projects, is solved very efiectively by my construction, to prevent escape of fluid under pressure within the cylinder spaces at opposite ends of piston 3, whether such fluid be gas or liquid. The sealing means which I employ for this purpose include a metal strip or tape I4, of a width appreciably greater than the width of slot l3, perhaps twice as great; which is disposed Within the cylinder-underlying the slot and in' registry with it. As shown in Figure 5, this strip in relaxed condition preferably is planar, but when it is subjected to the pressure of thefluid within the cylinder it is curved transversely by being pressed tightly against the inner surface of-the-:cylinder wall to conform generally to-the -wall curvature,
and to bridge across slot 13.
Sealing strip l4 does not move lengthwise with piston 3 as it reciprocates withinnthexcylinderr I, but remains stationary, being stretched tightly between the end plates or heads l5 and l 6 of" the cylinder. In order to enable the piston to be re moved from the cylinder and again insertemaat leastone end of slot l3 must be able to be-opened. Such end is shown at the right of Figure 1, closed by a lug ll, which may be formed integral with the cylinder head 16. Strip l4, it will'sbe-noted, is long enough to extendto the inner face of'such head, so that it assists in sealing any. crackbetween the cylinder "wall and the edges ofPthe-sIotclosing lug. This end of the sealingstrip is secured to the lugby-a bolt 18, and its other end is attached to cylinder head "I 5'by a-bolt l3 extending-lengthwise of the cylinder-and. riveted, or otherwise permanently secured, "to such: end" of thestrip.
Because connecting plate 3t 'projects. through slot l3, and strip l4: covers this'slot, it would be supposed that these two elevents would conflict, and that the sealing strip wouldinterferewith reciprocation of the piston lengthwise'. withinnthe feed cylinder. Such conflict is. avoided, however,
by forming a groove Si in one side of the'piston,
extending lengthwise of it, to receive the sealing strip. Such groove is of rectangular cross section, and'its chordwise width is. slightly greater than the-width of the sealing strip,.tocaflord adequate clearance for it. If the depth of this groove were only approximately as great as the thickness of the sealing strip, no opportunitywould be afforded-for securing connecting plate 30 to'the piston.
Insteadof the bottom-of the pistongroove 3| being linear, it is concave lengthwise of piston 3, and the groove ends preferably are spaced slightly from the pistons ends. Thexinner edge of connecting plate 33 has a transverse fiangev 3N T integral with it, so thatsuch plate iss ofaT-bar section. The-width of this flangeis-substantially equal-tothewidth of groove 3|; and its face is convex, coinplemental to the concavity-of therpiston groove. into the piston groove with -its=convex: face. spaced from the bottom of the: groove just=slightly;'rnore thanthethickness of sealing strip l4.-= When in this'position the flange shoulders lie substantially in continuation of the cylindrical-surface. of r the:
piston. With the flange 32: of the. connectingplate thus received in the piston groove 3 l the exposedcorn'ers of such flange are "welded, ebrazed, or'similarly secured to thapistom: so that. the
piston and'connecting plate form anx integral assembly.
Circular: packing cups 32 are secured to each end of piston 3 by'retainer plates-33$ The cylinder assembly is completed by a tie rod' 34- which passes axially through the pistonen'd both-cylinder heads l5 and I6. Nuts threaded on each end of the rod hold the cylinder heads firmly against their respective ends of the cylinder wall.
In assembling the mechanism described the connecting plate 30 will be secured on piston 3, and retainer plates 33 will be fastened to each end of the piston over thersealingcups' 32. The rightrends of sealing-strip .14, bolt l9 having been secured to its left end, will now be passed through the passage formed in the bottom of thetright=end of thecylinder, as'seen in=-Fig. 1,
with its lug. l'l-closing-the: end or slot.- l3. The othercylinder head. l5amaynow-be put in place with .boltl9"and.--rod 34 passing through-their respectiveaperturesin it.
The cylinder. assembly. is securedsfirmly. together bytightening. the nuts on opposite ends of rod 34 to=drawwthe cylinder heads. l5 and-l6 towardeach other; sealing strip 14" may next be ,tensioned the desired amount byscrewingu-p the nutlon bolt l9. This bolt, it willfbe noted, is -.located suflicientl-y. close to the margin oi-cylinder head l5 so. that the sealing strip liesragainst the cylinder wall, and consequently, even before fluid under pressure is-admitted to thecylinder, the sealingstrip. will assumea somewhat. transversely curved shape, .as shown in Figure 4. When. such fluid is supplied to the spaces within the cylinder at each end of. the piston thesealing stripswill be pressed tightly against-thecylinder. walls along the margins -of.s1ot .l 3 and. piston sealing cups-32 will also be flared outwardly against the cylinder walls, to embrace. closelythe strip l4, asshown in Figure 2.
If the pressure. ofrthei fluid-in opposite-ends of the cylinder is. unequahpiston 3 will bedriven away from the high pressure end-and toward the lowpressure end, sliding. along .sealingsstrip 14. Although beyondeach end of-the. piston this'strip ,is curved transversely, the, intermediate portion passing. through .piston groove. 3| beneath the connecting plate flange '32 will be boweddnward lengthwise, but will .beflattransversely, each .section changing its curvatureirom transverse to lengthwise.asithepiston groove 3Lmoves over: the
strip, and resuming its "transverse curvature. as the. piston groove passesbeyond each I such section. The slot l3 will not beseal'edovervsuch intermediate 2 portion, qbutf no fluid. can leak throughitat this point, because a 'sealrisieffected around the-strip at bothendsf of=the pistontby the cups 32, in the manner-shown in s Figure 2 anddiscussed above.
WithEthe cylinder'and .pistonmechanism .completely assembled in" thisvmanner';guides-rods: l I may be'passedr throughitheears l2,.-which maybe formed on the cylinder heads l5=.and'll6, and through-the arcuatesupports-.=22"oi the-drill motor. When tthaprojections 23 0f =thelair motor have been 'secured to the connecting plate '30 by bolts 24 the coupling; and cylinder assembly will becompleted for operation.
l clainr-as myinvention:
1. A pistonpoupling mechanis'm'pomprising a cylinder havingaslot through its wall extending lengthwise thereof, said slot throughout its depth and length being of uniform width, a piston head fitting within said cylinder for reciprocation lengthwise thereof, connecting means carried by said piston head and projecting outwardly therefrom through said cylinder wall slot, a bypass in one side of said piston head of substantially rectangular cross section and concaved lengthwise of the piston head, and a sealing strip within said cylinder having its ends afiixed to the ends of said cylinder and located to cover said cylinder wall slot and extend through said bypass, said strip being normally of substantially rectangular cross section and capable of flexing transversely by virtue of the pressure of motive fluid within said cylinder to conform substantially to the curvature of the cylinder and engage the latter in fluid tight relation therewith.
2. A piston coupling mechanism comprising a cylinder having a slot through its wall extending lengthwise thereof, a piston head fitting within said cylinder for reciprocation lengthwise thereof, connecting means carried by said piston head projecting outwardly therefrom through said cylinder wall slot including a groove in one side of said piston head concaved lengthwise thereof, a sealing strip within said cylinder secured therein against longitudinal movement relative thereto and located to cover said cylinder Wall slot and REFERENCES CITED The following referemces are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 651,862 Kelly June 19, 1900 1,740,714 Rundqulst Dec. 24, 1929 2,038,595 Noble Apr. 28, 1936 2,109,128 Carrillo Feb. 22, 1938 2,154,788 Terry Apr. 18, 1939 2,373,455 Carey Apr. 10, 1945 FOREIGN PATENTS Number Country Date 470,088 Great Britain Aug. 3, 1937