US1969153A - Percussion tool - Google Patents

Description

Aug. 7, 1934. E. w. ROBERTS PERCUSS ION TOOL 2 Sheets-Sheet 1 Filed Nov. 23.. 1951 E. W. ROBERTS PERCUSSION TOOL Aug. 7, 1934.

2 Sheets-Sheet 2 Filed Nov. 23, 1951 Patented Aug. 7, 1934 UNITED STATES PATENT; QFFHQE i I 1,969,153 I V i h i V PERCUSSION T0 OL Edmund W. Roberts, Cincinnati, Ohio, assignor to Robert D. OConnell and Joseph R. Sweeney, Cincinnati, Ohio, partners doing business as OConnell & Sweeney Application November 23, 1931, Serial No. 576,839

6 Claims.

My invention relates to that type of percussion tool or hammer in which a piston or plunger reciprocates axially in a cylinder, and strikes the 7 end of a drill bit, chiseLtamper or other tool, at

the end of its outward stroke; the plunger functioning as the piston of an explosion engine, and the blow being imparted by the force of an explosion efiected upon the piston.

The internal combustion or explosion engine exemplified is of the two-cycle type, in which an explosion occurs at the beginning of each outward stroke of the piston.

It is the object of my invention toprovide a new and improved percussion tool of simple character and rugged construction and having few parts compactly assembled; further, to provide novel means for imparting the outward stroke of the piston to the tool; and, further, to provide novel means for imparting forceful impact upon the tool.

it is the object of my invention, further, to provide novel means for actuating a ily-wheel by means of a piston and employing the inertia of motion of the fly-wheel for returning the piston during its compression stroke and freeing the fly-wheel connection from the piston at approximately the moment of actuation of the tool for imparting a forceful working stroke to the tool.

It is the object of my invention, further, to provide a novel arrangement of jacket space for the cylinder of an explosion engine, 'a fiy-wheel, a magneto and a fan, the fan having communication with said jacket spacewhich is open to the 7 outside air, and so constructed and arranged in novel manner as to draw the air over the mag- Fig. 1 is a sectional elevation through th axis of the piston and the cylinder taken along the line 11 of Fig. 2. Fig. 2 is a sectional elevation taken along the line 2-2 of Fig. 1, with the exception that about two-thirds of the piston is not in section, and thecrankpin is shown in less advanced position and as if out off close to the crank arm.

Fig. 3 is an end view as seen from the left of Figs. 1 and 2, with the handles or grips removed.

'Fig. 4 is a sectional elevation of t e flywheel casing taken along. the line 44 of'Fig. the flywheel not in section. V

Fig. 5 is a diagrammatic view with the anvil block omitted, it being assumed that the piston acts directly onthe tool-bit, and showing the pi's-' ton, crank, roller and tool-bit in their relations at the end of the compression stroke.

Fig. 6 is a similar view'of the parts, with the crank moved through' an angle of forty-five degree's.

Fig. 7 is a similar view of the parts with the piston in its working stroke, and showing the outer end of the pistonadvanced beyond the broken line, which represents the limit ofworking stroke q of a similar piston coupled journalwise with; the crank. i I

Fig. 8 is a similar view of the parts, showing the piston at the end of its power stroke.

Fig. 9 is a similar View of the parts, showing their relations at the beginning of the return movement of the crank; and,

Fig. 10 is a similar'viewof theparts, showing the crank as having made an' additionaloneeighth revolution, prior to the parts againassuming the relations shown in Fig. 5,

In the drawings, the cylinder is indicated gen erally by the numeral 11. The cylinder has an outer or jacket wall 12, providing an annular space or jacket 13 between the cylinder and'the jacket wall. At'intervals in the jacket space 13 are ribs 14, integral with thecylinder and'the jacketwall, providing longitudinal'air spaces 13' comprising that portion of the jacket space contiguous to the left-hand end of the cylinder.

Bolted to the side of the cylinder uppermost in Fig. I isthe by-pass plate or cover l5, providing a semi-annular space 16 correspondin tothe bypass or transfer port of the average two-cycle engine. Bolted to the 'side' of the by-pass plate; and registering'with the opening 17 providedinthe plate, is the mixing valve 18. The tank 19 bolted to plate 15 provides fuel storage, and'is connected with the gas valve ofthe mixing valve by a tube not shown in the figures.

Within the cylinder 11, and adapted to reciprocate axially therein, is the piston 20. The piston is provided with a longitudinal groove 21, in

1 with which is a guide roller 22, mounted on the threaded pin 23. The pin projects through the q, by-pass plate 15, and is threaded in the wall of cylinder 11. This guide roller orother suitable guiding means-is advisable to prevent the piston from turning on its axis.

Mountedon the side of the cylinder 11, and

held thereto by means of bolts 25,is' the side 1110' plate 24. In the side plate is journalled the crankshaft 26 within the ball bearings 27. The crankshaft comprises the crank arm 28 and the crankpin 29. The crankpin includes the roller 30 mounted on bearing rollers 31 on the rigid part of the crank pin.

In that side of piston 20 nearestthe'side'plate 24 is provided a groove 32'of which the lower portion 32 is a running fit to roller 30. The upper portion is cut away, at the side nearest the cylinder head 53, at an angle of approximately The side of the piston is further cutaway to provide the extensions 33 of groove 32 to clear crank arm 28.

The right-hand end of the piston is provided with a cup-shaped opening 20" to receive the extension 34 of the anvil block 34. The anvil block exemplified is shown-as a: supplemental or auxiliary piston provided with packing. rings for making the outer end of the cylinder airtight against leakage from the pre-compression chamber which is in the cylinder between the anvil block-34 andthepiston 20. A similar opening 34 is provided. in the anvil blockto receive the end of the tool bit 36.. The extreme right hand end of the. anvil' block is provided. with anenlargementl3 5- registering with -a' correspondingly enlarged. bore 35 in the end. of cylinder 11.. The. piston is arranged to strike the anvil block, which transmits the impact to the tool-bit.

Lower cylinder head: 37 is yieldingly attached to the cylinder through themedium or. the springs 38,.the bolts: 39,.and'the hook nuts at Head 37 isprovided. with an opening suitable for the re-- ceptien. of-Qth-e aorta 36. Surrounding tool bit 36, and held loosely in one of the hook nuts 40, is. a tool-retaining link- 41; of. a type. frequently employed on air hammers to retain the tool bit when the hammer is lifted,

Mounted onQthecrankshaft 26, and. fixed thereto, is the flywheel 42. Within the rim of the flywheel is mounted the ring-shaped magnet 43, which is one of the constituent parts of the flywheel magneto. In Fig. 4 are indicated the relative positions of the-magneto coil 44, and the circuit' breaker 45. In thisv figure they are. shown asdetached from the plate 46 (Fig.1) to'wh-ich they are fastened. Since the f unctioningflof' this type of magneto iswell known in the art, further description thereof isunnecessary.

Integral with the-flywheel arethe fan blades 47,. which serve to draw air through the cylinder jacket- 13, and through the compartment surrounding the magneto, and to discharge the air 1 tov the atmosphere. Inaddition tothe cooling air,

exhaust gases.- discharged from the cylinder through exhaust port X,. enter the fan to be dis-- charged therefrom.

7 To guard againstover-heating the magnet 43 and: thereby demagnetizing it,v the magnetis mounted within the. flywheel rim with its outer periphery incontact with ribs 4?? extended f-rom the blades-47. are. provided air spacesbetween the ribs, theinside of thefiywheel-rim, and the outer surface'of the magnet; through which air may be drawn in addition to -that circulating through the- -magneto compartment, Further- I more, less heat will pass by conduction from-the flywheel: rim: to the-magnetthrough the ribs than ifthemagnet were: in contact with the entire inner surface-of the rim.

Partially surrounding the flywheel 42' is an extension 24 of the side'plate 24 comprising a; hood to deflect the gases: leaving the fan. from striking" the operater in the face. The. lower (Fig. 4) is open. Across the opening provided in extension 24 are guard bars 48 and 49.

In the wall of cylinder 11 are provided the ports 0, I and X. Port C provides for ingress of the mixture from the mixing valve 18 into the space: providedibetween the piston 20 and the anvil block 34. It also provides for egress of the mixture from the cylinder to the by-pass 16. Port I provides apassage for the mixture to enter the cylinder from the bypass. Port X provides a: passage way for the egress of the exhaust gases from the cylinder tothe flywheel fan, whence they are"discharged tothe atmosphere. The defle'ct'or 20", integral with piston 20, bars the new mixture. entering port I from passing directly across the end of the piston to port X, and deflects the mixture toward the head of the cylinder.

Bolted to plate 24 is the cover plate 50 provided with an opening 51 surrounding the crankshaft nut 26', and providing a space between the nut and the. plate for the insertion of a suitable starting crank. The same space further pro vides a passage way for air to enter the magneto compartment, the entering airpassingthrough openings 52' provided in the webof the flywheel.

Bolted to the left-handend of the-cylinder 11, is the cylinder head 53' in which is the spark plug54. Attached to head 53 are ears 55 provided with internal. screw threads for the reception. of' the handles. 56. Covering the handles are the grips 57', preferably ofrubber fabric, a heavy steamhose. making a satisfactory grip.

In the operation of the invention, the machine is started in the same manner as any small explosion engine. by spinning the flywheel with a. suitable starting crank. The sequence, of events of the cycle are those of any two-cycle explosion. engine in which the mixture first enters the. crank-case to be discharged therefrom into the bypass with the difference that the functions' of the enclosed crankcase are performed by the space provided between the end of piston. 20 and anvil block 34. Since the functioning of a twocycle. engine is wellknown to the art, no detailed description will be given The adaptation. of the invention to the requiren'ientsv of a. percussion tool is shown in thedirectly by the end-ct the piston 20 The rela tive positions of the piston and. the tool bit are shown tothe same scale in each of the. figures.

In Fig. 5, the roller 3 0 has thrust piston 20 to the limit of the. inner or compression stroke. It will be noted that the innerdead center position ot'the roller has-not been: reached, and that further rotation of. the crankshaft will. not drive the piston further to the left, owing to the conformation of groove: 32.

In: Fig.6 the crankshaft has turned through an angle of 45 after passing the inner dead cen- 1 ter. The piston is shown. as it would follow the roller when impelled: by the. force of an explosion in the cylinder, with the slanting. side of the groove bearing against the roller.. The crankshaft isbeing: driven by the piston, storing up kinetic energy in the flywheel; It should be noted that thepiston has made approximately a half of its normal stroke whil'e'the crankshaft has been making but one-fourth of the half revolution corresponding to the full stroke in one direction of the piston, the piston moving faster than the roller. in the axial direction of the piston.

In Fig.7, the crankshaft is shown as having made a quarter revolution corresponding to a half .stroke of the piston, while the piston has made more than a normal 'full stroketo strike the end of the tool bit. The broken line near the right hand end of the piston indicates what would bee. normal full stroke, that is, the position of that end of the piston had it been reciprocated by the crankshaft with the roller bearing against the right-hand side of the groove.

It should .be noted that if the pistonwere re.- ciprocated by the crankshaft through the medium of the roller in contact with the right-hand side of the cross groove in the piston, the piston would not come into contact withithe end-of the tool bit, or strike the anvil block 34 in the combination illustrated in Figs: 1 and 2. The axial distance between the broken line near the righthandof the piston and that shown by the solid line in Fig. '7 represents the over-run of the piston at the instant of impact. i

In Fig. 8, the crankshaft has made another oneeighth revolution, and the roller is 135 past the inner dead center position. The impact of .the piston under the impelling force of the explosion has driven the tool slightly to the right of the position it normally occupies, as indicated in the previous figures, as shown by the greater distance between the dotted line and the end of the piston as compared with the interval indicated in Fig. 7. The roller is now out of contact with both sides of the groove 32, and the axial movementof the piston is unrestrained by the roller. This freedom of restraint permits the piston to follow through and exert the full force of the explosive impulse upon the end of the tool bit, less only that small proportion of this force required to keep the. flywheel in movement and to compress the mixturein the right hand end of the cylinder.

In Fig. 9 the crankshaft is shownas having made slightly more than a full half turn and the piston has rebounded from the tool bit, to start on its return stroke. Itshould be noted that the right-hand side of groove 32 has not quite come into contact with roller 30. a

In Fig. 10 the crankshaft has made a oneieighth revolution past the outer dead center position of Fig. 9. The roller has entered the lower half.32" of the groove 32, and the piston is now being impelled by'the crankshaft from the energy stored in the flywheel to compress the explosive mixture in the explosion chamber, at the left of the piston. This condition continues until-the relative positions-of the crankshaft and the piston are as in Fig. 5.

My improved device starts readily with the spark at the full advance required for best results at working speed, and throttle control and spark control may be omitted, thus materially simplifying the mechanism.

The apparatus has the peculiar faculty of operating more slowly when not crowded to the work than when the operator thrusts downward on the handles. For example, when the tool is lifted or when it is allowed to run by itself supported on a tamper, it will run at about 400 R. P. M. Crowded to the work it will speed up to .tont'o start-it on the .inward stroke.

instant the piston strikes the tool-bit.

its normal working speedof 1100 R. P. M. or more. In explanation of this it may be stated that in my improved device the return stroke of theme- :ton is-started by its rebound from the tool-bit. Furthermore, the stroke is slightly shorter when the 'tool' is crowded. When idling, the force of the recoil is less, the distance through which the piston must rebound is longer, and thecrankshaft has more work to do in picking up the pie- Hence, more of the energy stored in the flywheel must be expended to return the piston than when the rebound .is more vigorous, as 'when the tool is crowded. The speed of the tool may in consequence be regulated by the pressure on the handles. r

In my improved device, the widenedportion of the cross-groove in the piston provides for the detachment of the piston from the rotating parts at the moment of impact, so that the major porsaid cylinder, of a piston axially reciprocable in' said cylinder, the piston having a groove provided therein within the cylindrical projection-of the inner'face of said cylinder .and intermediate of the ends of said piston, the groove at a right angle to theaxis of the piston andin one'side thereof, said tool-bit slidably mounted at said :other end of the cylinder,the piston operative to move the tool-bit; a crankshaft journalled on the cylinder and radial with relation to said piston, a flywheel on the crankshaft, a crankpin on the crankshaft, and a roller on the crankpin, the roller in the groove, a portion of the groove being a substantiallyrunning fit-to the roller, another portionof the groove being wider'than the diameter of the roller, the sides of said cylinder opposite the respective ends of said groove provided with recesses in which said roller is alternately received, and

the wider portion of the groove so conformed that thepiston may move faster than the roller when impelled by an explosion in the cylinder, and that the piston is free of restraint by the roller at the 2.;1'na percussion tool, the combination of ;a cylindenan explosion chamber at one end of said cylinder, 2. tool-bit slidably mounted at the other end of said cylinder, a piston axially reciprocable in said cylinder, said piston having a groove solely'in one of its sides between its ends within the. cylindrical projection of the inner face of said cylinder atsubstantial right angles to the axis of said piston and extending into said piston substantially to saidaxis, said piston operative to move said tool-bit, a crankshaft journaled on said cylinderradial with relation to said axi i a crankon said'crankshaft' located in said groove adjacent to said axis, and a flywheel on said crankshaft, the wall of said groove toward said explosion chamber having a slanting portion at one of its ends slanting outwardly toward said explosion chamber for widening said end of said groove and acting on said crank during explosion movement of said piston for rotating said crank- Mil shaft, said explosion movement being also the iimpelling stroke of said piston for impelling said tool-bit, the other end of the walls of said groove being substantially right-angular with relation to said axis, said crank having a substantially running fit with said other end of said walls for 7 1 in line with said groove provided with recesses returning -.said .piston into said explosion :chamstant of impact 4 producing benthe walls of said widened end ofsaid-groove soconforni'edthat the pistonmay move .faster in axial direction'than the crank during-such inone of its sides between its ends within the cylindrical projection of the inner face of said cylinder at substantial right angles to the "axis :ofsaid piston and extending into said piston substantially to saidaxis, said piston operative to, move said tool-'b'it,a crankshaft journaled on said cylinder radial with relation to said axis, a crankarm on said crankshaft, a crank on said i crankarm located in said groove adjacent-to said axis, and :aflywheel on said crankshaft, the wall of said groove toward said explosion chamber having a slanting portion at one ,Of its ends slanting outwardly'towa'rd isaid'explosion chamber torn idenin'g .saiden'd of said.- agrdove and acting on 'saidhcrank during explosionmovement o f saidpiston ffor rotating said crankshaft, "said explosion movement :ibeing also vthe impelling' stroke of said piston for impelling :sa'id tool-bit, said piston provided with a recess at theside of said widened end of groove, said 'cran-karm extendingintclsaid 'IEfiESSythG otherzrend otithe j walls of :said :groove'being' substantial-1y i-r'ightangular with relation'to said axis, said crank hav ing -:a substantially running ifit with said other =end o=f said walls for returning saidpiston into said explosion chamber; thewallsio-f said widened I end 'of said groove so contormed that the piston may move faster in axial direction tlranthecrank during such impeding stroke I of said piston, and saidpiston-be-ing tree of "restraint by said crankat the instant of impact producing the putting stroke of thetool-hit.

-4. In :a percussion t col,.1the.comhinatioii of :a cylinder, an explosion'chamber atone lend of said cylinder, .a tool-hitslidahly mountedaa-t the other end of saidcylinder, api-ston =ax-ia1ly'r-e-' l ciproca ble in said cylinder, said piston having a groove solelyin one of its sides between its ends within the cylindrical projection of the inner face of the cylinder at substantial right angles to the axis of said piston and extending into said piston substantially to said axis, said piston operative to move said tool bit, a crankshaft journaled on said cylinder radial with'rel'ation to said axis, a crank on said crankshaft located in said groove adjacent to said axis, the sides of said cylinder between the ends of said piston in which said crank moves beyond the cylindrical projection momma wolf said, piston, anda flywheel on said crankshaft, the, wall :of :said .grooye toward said explosion of said iwidened end of said groove soconformed that the piston may move faster in axial-direc- .tionjzth an the crank duringsuch impelling stroke of saidipiston, and said piston being free of restraint :by said crank'aat the instant of impact producing the [cutting stroke ofthe toolebit.

5 In a percussion tool comprising an explosi'on engine; the "combination oi -.a cylinder, a-piston reciprocable therein :andrarranged to operate a tool; a jacketewallsurrounding said cylinder, a

jacket-space provided between said jacket-wall and said icylin'deig' said .jacketespace having connection with the atmosphere, .3, crank-shaft for said piston journaled on said cylinderrat right angles to the axis of said. piston, any-wheel fixed tosaid crank-shaft, said'fly-wheel locatedisolely .at one side of said "piston, said fly-wheel provided with a fanaspace, an air-conduitbetween :said jacket-space and said fan-space, fan-blades insaid fan-spacefixed to saidfly-wheel andaa magneto incorporated in said fly-wheel at the same .side of said piston, and said ifanebla'des operative to draw air through ssaidvjacketespace and said conduit and'over saidmagneto.

6; In a percussion-tool comprising an explosive engine, the combination of a cylinder, -.a piston reciprocabletherein and arrange'd'to operate a tool, a jacket-wall surronndingrsaid cylinder, at jacket-space provided between said jacket-wall and said cylinder, said jacketspace having connection with the atmosphere,v a crank-.shaftior said piston journaled. on said cylindersati right angles to the. axis of said piston, a fiy-wheel fixed to said crank-shaft, a casing about said :flywheel, said casingland said fly-wheel .havinga fan-space therein,'said casing provided withan air outlet communicating with said fan-space, an airv conduit between said jacket-space ,zanid vsaid fan-space, said fly-wheel and said casing with said fan-space thereinlocated solely at one side of said piston,.fan'-blades in .said fan-space fixed to said fiy-whee'l, and amagneto incorporated'in said fly-wheel .at the same side of. said piston and located in said.v fan-space, and said Lfanblades operative to draw air through said .jaokotspace and through said air conduit over said magneto.

EDMUND ROBERTS.

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