US2180034A - Internal combustion hammer - Google Patents

Description

c. 1.. CHARLES 180,034 A INTERNAL COMBUSTION HAMMER I Nov. 14 19 39.

' Filed latch '15 1937 I 2 Shoots-Sheet 2 Patented Nov. 14, 1939 UNITED STATES.

PATENT OFFICE mama comnus'rron mums Carl L'Charlcs, Wm... n 1., 'a ssignor to Gas Toolv Patents Corporation, a corporation of Delaware Application March 15, 1937, Serial No. 131,352

' 2 Claims. (Gl. 123-7) This invention relates to an internal combustion hammer, and more particularly to an improved lower end construction therefor.

One feature of this invention is that it provides improved cushioning means for the impacts in a hammer in raisedposition; another feature of this invention is that it enables a single cushioning spring to be used; still another feature is that it eliminates clatter, ju p. and excessive vibration when the hammer is raised; another feature is that the speed of the hammer is re-' lower end of the hammer, at right angles to the view in Fig, 1; Fig. 4 is a view of another type of hammer embodying this invention; Fig. 5 is a vertical elevation of the bottom of this hammer, at right angles to the'view in Fig. 4; and Fig. 6 is a detailed view of. the tool holder along the line 6-6 of Fig. 5; Fig. 7 is a side elevational view of the tool holder of Fig. 5.

The hammer is of the internal combustion type wherein a cylinder l0 hasa piston-hammer freely reciprocal therein, the hammer being of the general type shown and described in Mould Patent No. 1,997,072, and other similar patents.

The cylinder Ill and piston II, with associated mechanism to render them operative, form an the downward stroke thereof.

internal combustion engine operating on the two'- stroke-cycle principle; A charge of air and vaporized gasoline, for example, is supplied from the fuel supply unit |2to the chamber ll beneath the piston, where it is partly compressed by Near'the bottom .of the'working stroke of the piston the charge is transferred from the sub-piston compression gases are discharged through the exhaust port I! and the cycle is repeated.

Handles Z0 and 3| are provided to enable the workman to properly manipulate the hammer, to spot the tool on the working point, and to lift the hammer between operations. Starting is accomplished by manually depressing the starting rod 22 .until the-piston is near the lower end of its travel, then releasing it so that the piston springs back and compresses a charge above it in the firing chamber.

Referring more particularly to the lower end of the hammer illustrated in Figs. 1, 2 and 3, the cylinder It has extending downwardly therefrom an anvil housing 28. This anvil housing is concentric with respect to the cylinder, and therefore with respect to the piston-hammer II, .and

a is held thereto by tie rods 21 and 2a. Beneath the anvil housing and fastened thereto by the same tie rods 21 and 28 is a cap or housing 29. This combination provides housing, coaxial with the piston, for the anvil 30, the anvil sleeve bearing 3|, the follower 32, the cushion spring '33, and the split bushing or tool retainer 34.

The anvil comprises amember longitudinally movable in the anvil sleeve bearing 3! and adapted to receive the blow of the piston-hammer andtransmit it to the tool 35. The anvil 30 is a rather close fit in the sleevebearing 3|, preferably with only a'few ten-thousandths of an mushroomed out at the bottom to form a head .38 which abuts a shoulder 31 on the inside of the anvil sleeve bearing 3| to limit the upward movement of the anvil. when the hammer is working the tool 35 is forced upwardly or raised in the '46 The source of current for ignition is here shown as attached to the spark. plug 1 1 and the circuit breaker l8 by leads 2 3- and 24 respectively, brought into one handle of the hammer through the cable 25 from an exter- 'nal source.

inch clearance between it and the bearing. It is is at its upper end'in contact with the head 36 I of the anvil;in turn prevented from further upward movement by the shoulder 31. The sleeve bearing 3| is longitudinally movable in the anvil housing 23, but "upward movement is prevented by a shoulder 38.

. Immediately beneath the sleeve bearing 3| and abutting it is the follower 32. This follower surrounds the upper portion of the tool 35 and is axially movable in the anvil housing .26. It is supported in a raised position against the sleeve bearing by the cushion spring 33, which has its upper end abutting the bottom ofthe follower.

anvil, the follower, and the cushion spring 33.

It will be noted that when the tool is dropped, the follower 32 has a space of about eleven-sixteenths of aninch through which it can move to absorb the impact delivered by the piston-hammer. The spring 33 is, of course, a relatively heavy coil spring arranged to exert about three hundred and sixty-three poun'ds upward pressure when the follower 32 is at its lowermost position. The spring is also so arranged that there is some upward pressure, preferably one hundred pounds or less, when the follower 32 is at its upper position illustrated in the drawings. This pressure can be much less, but is preferably about ninetysix pounds.

It will be noted that when the hammer is in working position with the tool extending or raised therein to the position shown in the drawings, the anvil 30 has a distance of only about one sixteenth of an inch through which it can travel before it strikes the upper surface of the follower 32. This is sufficient play for normal working conditions, so that the follower is not called upon to absorb any substantial impacts except when l the hammer is lifted, yet return of the anvil does not impart undesirable vibration to the hammer,

It will also be noted that the piston return spring assembly, comprising the piston spring l5 and recoil spring I6, is supported at its lower end by the anvil sleeve bearing 3|. This spring combination is under a static compression of from sixty to ninety pounds, preferably about seventy-two pounds, when the piston is down to the point of impact with the anvil. Thus when the piston delivers its blow on the anvil, the piston spring assembly exerts considerable downward pressure on the anvil sleeve bearing which is in turn transmitted to the follower 32.. The blow on the anvil by the piston would also be transmitted to the follower except for the upward force exerted by the tool on the anvil, which is a function of hammer weight and the pressure exerted by the operator. When the hammer is lifted and in non-working position, therefore, the follower 32, when driven downward, is returned by the cushion spring 33, but the return is opposed by the force exerted by the piston spring assembly through the anvil 'sleeve bearing 3|, with the inertia of the piston as a reaction against which the spring assembly works. The opposing forces of the piston spring assembly and the cushion spring tend to keep the anvil sleeve bearing 3| and the follower 32 in contact with'each other, so that vertical reciprocation is as aunit.

It is believed that when the hammer is lifted from working pbsition and the impact of the blows is being absorbed by the cushion spring, that'the sleeve bearing 3| and follower 32 are never in their uppermost position illustrated in the J. mwing, although sometimes at the bottom of their possible travel, but usually floating therebetween. As soon as the hammer is lifted the the follower and housing.

tool drops and the anvil drops with it until it contacts the follower 32, thus lengthening the stroke of the piston about one-sixteenth of an inch. Any further drop of the follower 32 in absorbing the blows causes the anvil to drop still lower in the cylinder and thus give a still longer effective stroke. A lower position of the follower 32, since it results in a similar lower position of the anvil sleeve bearing 3| supporting the springs, also may result in less force in the piston spring assembly returning the piston, when the assembly is near most expanded position, thus resulting in a reduced compression of the charge in the firing chamber. The longer time the exhaust port is open, due to'the fact that the piston travels further down in the cylinder, also seems to result in a loss of some of the fresh charge, It is believed that these factors so alter the working stroke of the piston as to reduce its power. It is also believed that the arrangement described, with opposed springs above and below, keeps the anvil sleeve bearing 3| and follower 32 in contact with each other and prevents impact therebetween; and that the concentric arrangement of the cushion spring 33 with respect to the cylinder prevents any side components of motion being set up which cause binding or other undesirable action in the impact absorbing unit.

The follower 32 is closely fitted in thatpart of the housing 26 in which it travels, and the anvil sleeve bearing 3| has the lower surface thereof ground to make a good fit on the ground upper surface of the follower 32. It will be noted, moreover, that when the follower is in the uppermost position shown in the drawings it is in contact not only with the sleeve bearing but with a shoulder on the housing. Thus when the follower and sleeve bearings move downwardly under the influence of impacts of the piston hammer an annular space exists between the upper surface of the follower and the shoulder, with the housing forming the outer wall thereof and the sleeve bearing the inner wall. Inasmuch as some pressure is created within the housing 29 by the downward movement of the follower, and a vacuum created between the follower and shoulder, some air is believed to enter this annular space. The vacuum, moreover, probably draws oil into the space from the surfaces between the sleeve bearing and housing and between It is believed that when the follower moves upwardly again this mixture of air and oil forms a fluid cushion between the upper surface of the follower and the shoulder of thehousing, so that the last minute movement of the follower is cushioned thereon. The follower has been found in practice to contact the shoulder very lightly on its return, since even after long periods of operation of the hammer neither the shoulder nor follower show any signs of wear which would result from heavy impacts at this point.

Whatever the theoretical explanations of the improved results secured may be, practice has proved that the arrangement shown and described is considerably more effective than any other known bottom arrangement for absorbing impact when the hammer is lifted. When the hammer is lifted the speed drops from a working speed of around 1250 strokes per minute to a speed of 1050; the shocks of the impacts of the piston-hammer are absorbedand cushioned by the lower end in such away that the body structure of the hammer is able to absorb the vibration, without undesired breaking of parts or.

fatigue troubles; and the vibration of the hammer when-lifted is reduced so that it is relatively smooth running and easily handled and spotted by an operator.

In the second or modified form of this invention illustrated herewith in Figs. 4 to 6, a morepowerful hammer particularlydesigned for heavy duty is shown. "Iheparticularhammer illustrated weighs about ninety-four and one-half seven and one-half pounds. 4

much heavier, while it delivers more powerful pounds; and delivers about 1550 blows per minute when working. With the exception of diiferences' in bore and the like, the general operation of the engine portion of the hammer is the same as that described in connection with the form shown in Figs. 1 to 3;

The piston-hammer, is of larger diameter than that previously described, and weighs about A. piston-hammer and 43 are so arranged as to be under .a compression of about 82 pounds when the piston is in contact with the top of the anvil 44. The anvil 44 is longitudinally slidable in an anvil sleeve bearing 45, also longitudinally slidable in the recess 46 provided therefor in the anvil housing 41. A follower or tool guide 48 abuts the lower end of the sleeve bearing. being carried by a tool guide housing 49 rigidly, although removably.attached to the lower end of the anvil housing. The tool guide is s idable in its housing; be n guided therein by contact at its upper end with the inner wall of the housing and at its lower end with a polygonal opening 58 provided therethrough. A cushion spring 5| surrounds the reduced portion of the tool guide, abutting the shoulder 52 on the'tool guide at the upper end thereof and the shoulders 53 on the inner side of the housing at the lower end thereof. Apoly onal opening 54' in the center of the tool guide receives the tool 55 therethrough, the tool being prevented from dropping out of the hammer when it is lifted by engagement of an annular shoulder 56 thereon w th a tool holder 51.

Referring more particularly to F s. 5 and6. it will be seen that the tool holder 51 comprises a yoke member carried at each end thereof by extensions of the tierods 58 and 59. The holder 51 hasa central slot or opening adapted to embrace the tool 55 below the annular shoulder 56. One end of the yoke member. here illustrated on the left side of the hammer. has 'therethrouzh an opening adapted to surround and be rotatably iournalled on the extension of the tie rod 58. The lowermost part of this extension is provided with a head or annular shoulder 60 and the yoke has a reduced opening embracing theextension thereabove. This mounting enables the yoke member to be readily'rotated about the tie rod 58 as an axis, but prevents any possibility of its dropping off of the said rod. A spring 6| may be placed between the yoke member and the bottom of the housing ,49- to yieldingly urge the yoke member against the head 68 and prevent bouncing up and down as a result 'of the vibration of the running hammer.

The other end of the yoke member, here shown 'at the right in the figures,.terminates in a hooked portion adapted to surround the extended portion of the tie rod 58 on the other side of the wardly by a spring 63. wardly extending latch portion 64 adapted to rehammer. A ring 52 is slidably carried by this extended portion,.and yieldingly pressed down- The ring has a downfrom the tool that it may be dropped out of the hammer. A new tool may then be inserted in the opening 54 in the member 48, pushed up wardly therein until the shoulder 56 is abovethe iyoke member, and the yoke member then swung back until its hooked end embraces the extension of the tie rod 59 and its central slot embraces the tool. The latchring 62 may then be permitted to drop until its latch portion holds the hooked end of the yoke in place, whereupon the tool'is held in the hammer for any desired operation;

The lower end assembly of the hammer illustrated in Fig. 4 is to scale, and the preferred embodiment of this invention in all respects. The

tool guide housing has an outer diameter of 4.5

inches at its largest dimension, and an inner diameter serving as a guide for the upper end of the tool guide 48 of 3.625 inches. I The tool guide lying therein has an upper shoulderportion 3.622

inches in diameter and one inch thick from its point of contact with the anvil sleeve-bearing to the shoulder 52. The overall length of the tool inches. The material is of steel; heat treated to a Rockwell hardness of from (3-50 to C-53., Thecushion spring 5| is of seventeen thirty-seconds inch diameter chrome vanadium wire wound right handed in four and three-fourths coils. The metal is treated to a Rockwell hardness ranging from, C-'-42 to 0-44. The spring has athree inch mean diameter, and a three and one-quarter inch free. length after the ends are closed and ground flat the wire not being lessthan five thirty-seconds inch thick "at any point after grinding. This spring, in the initial position shown in the drawings has a force of 327 pounds; were the spring to be compressed to closed or solid position it would have a force of about 980 pounds.' The play or space between the head of the anvil' 44 and the top of the tool guide 48 is three-eighths inch so that when working the tool hasthat distance within which to move and ners. This is necessary in order to avoid fatigue troubles which'would otherwise start at the square T comers.

It is believed that the reasons discussed in connection with the lower end construction of the first hammer described also explain improved opcrating results secured here. Whatever thereasons this lower end construction provides a distinctly better hammer under operating conditions than the cushion mechanisms heretofore used.

Hammers similar in all respects, except that one had the lower end construction 'shown in Mould Patent No. 1,997,0'12-and the other the lower end construction shown in Fig. 4, were'tested side by side. Operating on a tamper on gravel both hamof the wall of the hammer.

mers ran at 1500 strokes per minute when working. The arrangement illustrated herewith caused the hammer on which it was used to run much more smoothly, the absence of excessive vibration being very apparent. Speed tests made on each hammer when picked up proved that the design illustrated herewith slowed up the hammer to 1100 strokes per minute as against the 1200 strokes per minute of the other hammer, with a much more comfortable and easier handling hammer for the operator, The older type hammer produced quite a clatter and frequent jumps when held up, noticeably absent in the hammer constructed as illustrated herewith.

Improved means for locking the spark plug 85 in place is also illustrated herewith. The spark plug has an annular shoulder or ring 66 thereon beneath which a sealing gasket 81 is placed when the spark plug is drawn up against the shoulder Immediately adjacent one side of the spark plug is the bolt 68 and lock nut 59 holding in place a substantially L- shaped bracket member 10 having the extended end thereof pressing against the top of the annular ring 66. It will be noted that this bracket is so constructed and shaped as to be out of contact with the body of the hammer except at one point on the side of the bolt furthest from the spark plug. Drawing up the bolt 68 thus throws considerable locking pressure on the ring 68, preventing the spark plug from vibrating or loosening from its proper position on the body of the hammer.

Considerable trouble has been experienced in keeping a spark plug in place in an internal combustion hammer of the type shown and described here, since the terrific vibration causes the plug to work loose even though it is ordinarily tightened to refusal with a wrench. Various methods of locking the plug in place have heretofore been tried, but in each case that required the setting of the plug at a particular position in order that a piece might engage the hexagonal portion, for example. The present invention enables the plug to be drawn up to refusal in the usual manner, and then the additional locking means applied to insure against its vibrating loose.

The fact that the bracket or looking member 10 bridges the. space on the cylinder wall, rather than contacting it throughout its length, insures a firm frictional locking grip on the spark plug shoulder 66, That is, the bracket contacts the wall of the cylinder at one end and the shoulder of the spark plug at the other end, with the bolt 68 lying therebetween. Drawing up on the bolt thus puts pressure on only two points, and insures the full desired pressure being applied to the shoulder of the spark plug to frictionally lock it in place.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes,'therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

I claim:

1. An internal combustion hammer of the character described, including: a cylinder; a piston-hammer freely reciprocable therein; a tool longitudinally movable in said hammer; an anvil sleeve bearing longitudinally movable in said cylinder; an anvil slidably mounted therein for transmitting the blows of said hammer to said tool when in raised position; a follower for receiving the blows of said hammer when said tool is in lowered position, said follower being in contact with said sleeve bearing but spaced from said anvil when said tool is in raised position; a coil spring between said sleeve bearing and said piston and supported by said sleeve bearing; and a cushion spring exerting an upward force on said follower and sleeve bearing, said spring being coaxial with respect thereto and stifier than said first mentioned spring; said follower comprising an enlarged portion and a reduced portion lying within said cushion spring, said follower being uided at each end thereof.

2. An internal combustion hammer of the character described, including: a cylinder; a pistonhammer freely reciprocal therein; a polygonal tool longitudinally movable in said hammer; an anvil'for transmitting the blows of said hammer to said tool; a follower longitudinally movable for receiving the blows of said hammer when 'said tool is in lowered position, said follower comprising a portion of enlarged diameter and an elongated portion of reduced diameter having a polygonal lower end, the follower having a polygonal opening therethrough adapted to receive said tool; a housing rigidly mounted beneath said cylinder and having a polygonal portion forming a guide for said lower end, whereby the tool projecting through said follower is prevented from turning with respect to said hammer; a spring between said anvil and said piston; and a cushion spring within said housing exerting an CARL L. CHARLES.

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