US2677355A

US2677355A - Gas hammer

Info

Publication number: US2677355A
Application number: US175742A
Authority: US
Inventors: Spencer B Maurer; Howard P Ebert
Original assignee: Chicago Pneumatic Tool Co LLC
Current assignee: Chicago Pneumatic Tool Co LLC
Priority date: 1946-08-15
Filing date: 1950-07-25
Publication date: 1954-05-04
Anticipated expiration: 1971-05-04

Description

y 4, 1954 s. B. MAURER ET AL 2,677,355

GAS HAMMER Original Filed Aug. 15, 1946 5 Sheets-Sheet 1 ATi'oRNEY May 4, 1954 s. B. MAURER ET AL GAS HAMMER I5 Sheets-Sheet 2 Original Filed Aug. 15, 1946 ATTORNEY May 4, 1954 s. B. MAURE-R ETAL 2,677,355

GAS HAMMER Original Filed Aug. 15, 1946 3 Sheets-Sheet. 3

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TTORNEY Patented May 4, 1954 land; Ohio", assignors to Chicago 'Pii'e'umaltlo TooHLompany; New York, N. Y., axcorporat'ion New-Jersey" Original: applicationAugust 15,. 1946, SerialNo;

690,654,. now Patent No.- 2,533,481,- dated pecember 12, 1950. Divided and this application- Jiily 25,. 19'5'0,v Serial No. 175,742

1 Claim. 1.

This invention relates generally to percussive tools in which the motivepower isderiired from an integrally formed internal combustion engine, and more particularly to improvements pertain ing to the'driving connection between theengine and' a hammer'assembly of such tools.

This application is a division of our parent application Serial No; 690;654, filed August 15*, 1945, which issued as Patent No. $533,487, on December 12, 1950; Oth'erdivisional applications are as follows: Serial No; 1'03;662; filed July 8, 1949, now Patent 2,609,813, -dated September 9, 1952; Serial No. l76,984,'filedAu'gust l, 1950' (now abandoned), containing claims to a cooling system for a percussive tool internal combustion engine; Serial No.248,076, filed September 19, 1951, containing claims to a handle starter arrangement for a gas hammer.

In the illustrative embodiment of the present invention, a tie tamper is driven by a gasoline powered single cylinder, two cycle, air-cooled engine designed to impart rapid downward blows to a tamping bar mounted vertically in the lowerend of the tool. The engine is mounted directly atop a cast aluminum housing, which is the main body of the tool, and is connected to a hammer assembly which imparts impact blows to the tamping bar. A prime feature of the invention resides in the manner ofconnecting the engine to the hammer assembly, so that in addition to the power transmission means afforded, a convenient arrangement is providedfor the integration of a handle starter arrangement.

The main object of this invention is the provision of an improved arrangement. for connecting an internal combustionengine with a hammer assembly in a portable tie tamper.

A further object is the provision of an arrangement whereby a handle starter means may be arranged in the connection between the engine and hammer assembly.

Other objects and structural details of the invention will be apparentirom the description when read in conjunction'with the accompanying drawings, wherein:

Fig. 1 is a view, in perspective, of the tool of the present invention, shown adapted for the tamping operations with the starter handleflin the lowered position;

Fig. 2 is a longitudinal section'view, the lower part of the tool beingshownin elevation; and

Fig. 3- is a longitudinal section in thesameplane as Fig. 2,v showingaa striking hammer andcage in. lowered or foremost position and: in contact with the working implement. Fig. 4 is a 2 cross section" view'as indicated by thear-rows4 in Fig. 35

Fig. 5 is a' view of the transmissionmechanism shownin relation to the starter handle and shaft with an intervening-"clutch position i or starting operation. Figs. 2, sand are drawn to a larger scale than Fig. 1, while Fig. 5 is further enlarged.

As shown in Fig. 1, the tool of the invention is a portable, unitary structure which may be-rnanipulated by one or two men' by means ofpr-op' erly and conveniently disposed handlesI-Sand M. For purposes of description, the tool may be con sidered as divided into a pluralityof cooperating sections or parts including an" upper portion I 5, a downwardly extending barrel It, andaba-rrel extension or nose I 1. Extension or nose IT-sup ports a working implement I 8'wh'ich; in the pres Referring also ent instance, is atampingbar. to Fig. 3, the inner end of thebar I8- projects into the barrel I6- in position to receiveblow-sof percussionfrom ahammer piston I9: Fhe piston I9 forms part of a free piston type hammer ass-- 26 is reciprocated by power transmission-means connected to the-driving'piston 21 of the internal combustion engine. The transmission means,

hereinafter more fully described; comprises an engine crankshaft 22 driven by the'piston' 21, a-

main crankshaft 23 actuated by the engine crankshaft 22 through pinion and gear means, and a connecting rod 24 between the main crankshaft 23 andthecage 20; Thereciproca't ing action of cage-20 imparts repetitive hammer ing action to the hammer piston I9 as hereinafter described.

The tamping bar isrd'ri'ven in'its working operations by blows percussively imparted bythe striking or hammer piston I9 which is slidin'gly mounted in cage'ZB; Cylindrical cage 20:, which is made from a seamless steel tubing, is provided at its ends with annular enlargements or'

shoulders

44 and 45 which slidingly'ene'agethe inner wall of barrel 16. The mid-portion of thecage 20is of reduced external diameter to provide an annularspace 46 betweenthecage and the barrel, and said portion of reduced diameter is formed with a series ofcircumferentially'spacedportsor openings 41 to cooperate with a ,groovefit in the piston as hereinafter more fully described. The shoulders and 45 are formed withcircumier entially arranged longitudinal recesses 49'' which serveto. connect the annular space 4 5 respectively withtheohamber 52 of the main-crankshaft and the barrel chamber 53. Continuous communication is thus established between the top and bot tom of the cage to minimize pressure fluctuations. The

chambers

52 and 53 may be vented by exhaust ports (not shown) or alternatively may be enclosed from the atmosphere and maintained at any suitable pressure. In any event, the pressure fluctuations in

chambers

52 and 53 are slight, due to the equalizing effect of recesses 49 which transfer air from one chamber to the other and thereby inhibit compression in either chamber as a result of the movements of cage 20 and piston I9. Cage 20 is connected to the connecting rod 24 by means of a wrist pin 55 which is passed through aligned holes in the upper end of the cage and in the lower terminal of the connecting rod. An aluminum head 56 fits snugly within the upper end of cage 20 to form an air-tight closure for a chamber or air pocket 51 which lies above hammer piston IS. The head is transversely bored to receive the wrist pin 55 and is provided at its upper end with a square recess to receive the lower end of the connecting rod. The cage head 56 has a downwardly protruding portion which fills up a considerable part of the air pocket 51. Reciprocating movement is imparted to the cage by the connecting rod 24, and is transmitted through the air pocket 5! to the striking piston I9.

The upper portion I5 of the tool contains the internal combustion engine and controls therefor, including the starting mechanism and flywheel magneto. In the illustrative embodiment the engine is of the two-cycle type. The principal supporting element for the engine is a frame piece or crank case 6I, to which is bolted a cover BI, the frame piece and cover being made of aluminum, and cooperating to form an air-tight crankcase chamber 62 through which the connecting rod 63 passes. The driving piston 2i reciprocates within a cylinder 64 in the cylinder head 65 secured to the frame in conventional manner.

Motion is transmitted from the piston 2I through the engine crankshaft 22 to the main shaft 23. The engine crankshaft 22 is rotatably supported in ball bearing assemblies I6 and 11, the latter being mounted in the frame 6|. The left hand end of the engine crankshaft (as viewed in Fig. 2) extends into the crankcase chamber 62 and has keyed thereto, as at 18, a crank arm I9. Arm 19 has an outwardly projecting stud 8| extending into a cylindrical aperture 82 in the connecting rod 03 and is also formed with a fanshaped counterweight 83. Needle bearings 80 are provided for the easy rotation of the stud 8i within the connecting rod receiving aperture 82.

For effecting return motion of the piston H and thereby of the piston hammer assembly, a fly-wheel 84 is mounted upon the outer end of the engine crankshaft. The kinetic energy stored. in the fiy-wheel 84 on the power stroke of the piston 2 I, in conjunction with the counterweight 83, is sufficient to continue the rotation of the crankshaft 22 and to transmit through the crank arm 19 and connecting rod 63 force for the return stroke of the piston H. The connection between the rod 63 and the crankshaft 22 is such that they are constrained to move in unison, and operation of either element effects a simultaneous operation of the other. Their relationship as driven and driving elements is mutual and reversible.

The engine crankshaft 22 drives the main crankshaft 23 by means of pinion 93 on the engine crankshaft and the gear wheel 94 which is integral with the main crankshaft. Main crankshaft 23 is rotatably mounted in the frame Si by needle bearings 96 and ball thrust bearings 91, and is provided at its forward portion with splines which form a pinion 98 to cooperate with the toothed clutch ring 99, as hereinafter described. The inner face of gear wheel 94 is provided with a stud IOI which projects into the circular aperture I02 in the terminal portion I03 of the cage connecting rod 24, a bushing I04 being disposed between the stud and the rod terminal. Connecting rod 24 is connected at its lower end to the cage 20 by wrist pin 55, as hereinbefore described. It thus may be seen that the reciprocal motion of the engine or driving piston 2| is transmitted through the connecting rod 63 and the crankshaft arm I9 to impart rotary motion to the engine crankshaft 22 and that in operation the engine crankshaft 22 drives the main crankshaft 23. Crankshaft 23, through the cage connecting rod 24, acts as a reciprocating driver for the cage 20.

The toothed clutch ring 99 and rollers I06, as shown in Fig. 5, cooperate to form a clutch mechanism between the starter shaft I01 and the main crankshaft 23. Ring 99 is formed with an axial bore I08 and with a toothed periphery I09 to gear with the splined portion of the main crankshaft 23. The axial bore I08 of the clutch ring 99 is provided with a plurality of spaced slots I I6 (Fig. 5) circumferentially arranged and extending axially from the body of the brazed ring to the outer wall of the clutch ring. Each slot is formed with an adjacent arcuate portion II! the purpose of which will be explained.

The periphery of the central portion I22 of the starter shaft I0! is formed with a plurality of longitudinally extending spaced grooves I29 which serve, in conjunction with the cooperating slots H6 in the bore of the clutch ring 99, as seats for rollers I06 to form a clutch as previously stated. Each peripheral groove has an arcuate portion I30 throughout its length which has the same radius as a roller and forms a shoulder adapted to engage a roller to force it against the arcuate portion II! of the slot H6 when shaft I01 is rotated counter-clockwise (as viewed in Fig. 5) by the rotary thrust of the starter handle I3. One of the rollers I06, which will be at rest upon the upper portion of the starter shaft when the tool is not in operation, will wedge between a shoulder I30 of the starter shaft I07 and an arcuate portion II1 of a slot H6 when the shaft is actuated. In Fig. 5 such engagement is shown in the 10 o'clock position, although in actual operations such engagement or clutching may take place at any point in the upper portion of the shaft. Clutching will not be effected in the lower regions since the rollers will drop by gravity into the slots H6 when the tool is at rest. Motion is imparted to the starter shaft by a sudden downward thrust by the operator of the starter arm I3 whose inner terminal I25 is provided with teeth I32 to engagesplines I33 formed on the forward portion of the starter shaft I01. Such starting motion of the starter shaft is counterclockwise and the clutch ring 99 moves in the same direction at the speed of the starter shaft. Said clutch ring transmits motion at a higher speed to the main crankshaft, thence at a still higher speed to the engine or magneto crankshaft 22. As the engine picks up speed, the clutch ring will overrun the starter shaft and the rollers will be urged by centrifugal force into the slots H6 where they will remain throughout the normal operation of the tool.

In the illustrative embodiment the total gear ratio from the starter shaft I01 to the engine crankshaft 22 is 11.4 to 1. Thus a quarter turn of the starter shaft will turn the engine over approximately three times. A rapid downward thrust of the starter handle 13 through its normal ten inch stroke (approximately one-quarter turn of starter shaft) will produce more than three full revolutions of the engine at a fairly high speed.

The gear ratio between the engine crankshaft 22 and the main crankshaft 23 is about 2.85 to 1. The advantages of using a high speed motor with gear reduction are more power per cubic inch of motor, more cooling air with a smaller fan, better magneto operation (hotter spark) and smoother operation due to larger number of smaller motor impulses and accentuated fiy-wheel effect of the rather heavy magneto rotor.

What is claimed is:

In a portable self-contained percussive tool of the class wherein power is transmitted from an internal combustion engine to a hammer assembly, in combination, a frame piece for the support of said engine, a rotatable crankshaft having a splined portion, a second rotatable crankshaft provided with a splined portion and a toothed flange with a stud projecting from the flange, said toothed flange being adapted to cooperate with the splined portion on the first crankshaft for the mutual transmission of motion, mounting means formed in said frame piece for the support of said rotatable crankshafts, and a connecting rod mounted upon the second crankshaft stud at one end and at the other end to the hammer assembly.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,286,419 Krenzke June 16, 1942 2,323,535 Gorden July 6, 1943 2,333,419 Fitch Nov. 2, 1943 2,533,487 Maurer et a1 Dec. 12, 1950