US743389A - Fluid-pressure-operated tool. - Google Patents

Description

No. 743,389. PATENTED NOV. 3, 1903 N C. H. JOHNSON.

FLUID'PRESSURE DPERATED TOOL. APPLICATION HLLD JAN. 14, 1902. No MODEL.

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-Patented November 3, 19O3`.`

PATlinrr OFFica.

CHARLES HARRIS JOHNSON, OF CHICAGO, ILLINOIS..

FLUID-PRESSAURE-OPERATED TOOL.

,Sl-ECIFICATIGN forming part of Letters Patent No. 7432389, dated November 3, 1903.

Application 'lled January 14, 1902. Serial No. 89,719. (No model.) V

T0 @ZZ whom, it' may concern:

Be it known that I, CHARLES HARRIS J OHN- SON, a citizen of the United States, residing at Ohicago,county of Cook,State of Illinois, have invented a certain new anduseful Improve# ment in Fluid-Pressure-Operated Tools; and I declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use the same, reference being had to the accompanying drawings, which form a part of this specification.

My invention relates in general to {inidpressure operated tools, and more particularly to pneumatic hammers of the valveless type.

In fluid-pressure-operated tools as ordinaf rily constructed the piston delivers a blow upon a snap or the shank of a tool, the initialA propulsion of the piston toward the tool being due to the flow of Huid-pressure from the source of motive-duid supply, while the 'final portion of the stroke is due to the expansion of the fluid within the cylinder after it has been cut 0E from the source of fluid-pressure supply.

Fluid-pressure-operated tools have also been constructed heretofore in which impetus is given to the stroke of the piston by placing in communication with the cylinder a reservoir which has been charged with pressure coincidently with the admission of pressure to the working end of the cylinder from the motive-fluid supply; but it is obvious that in a tool so constructed the time available for charging the reservoir is limited to the time the induction-port remains open to the Working end of the cylinder, and consequently the induction-port must remain open sufficiently long to charge the reservoir as well as the Working end of the cylinder in order to avoid the reduction of the-pressure in the working end of the cylinder at the beginning of the piston-stroke.

The primary object of my invention is to provide a iiuid-pressure-operated tool in whichA the beginning of the stroke of the piston toward the tool is-eected by the admission of pressure from the source of motive Huid, while the continuation of the piston-stroke is eected by connecting the working end of the cylinder with a reservoir which has been charged with pressure from the motive-fluid supply prior to the admission of pressure to the working end of the cylinder.

A further object of my invention is to provide a tool of the class described which will be simple in construction andvefflcient in operation.

My invention, generally stated, consists in providing a pneumatic tool of the type referred to with a reservoir which is charged with pressurefrom the motive-fluid source during the throw of the-piston away from the tool before the admission of pressure to the working end of the cylinder and which dis-V charges into the cylinder after the piston has commenced its stroke toward the tool.

My invention willbe more fully described hereinafter with reference to the accompanying drawings, and in'which the same is illustrated as embodied in a convenient and practical form, and in which- Figure l is a longitudinal section through a tool embodying my invention, showing the piston delivering a blow upon the tool; and Fig. 2 is a similar view showing the piston at the beginning of its stroke toward the tool.

The same reference characters are used in the two figures of the drawings to indicate the same parts. y

Reference -letter A indicates a cylinder within which the piston D reciprocates. A handle B is secured to one end of the cylinder in any suitable manner. In the present instance a flange B overlaps the end of the cylinder and is held in such position by a cap A', which is provided with a screw-threaded tubular portion a in engagement with the interior surface of the end of the cylinder. A ange b', formed on the handle B, is interposed between the head of the cap A and the end of the cylinder A. Any suitable means may be provided for retaining the cap A' from rotation with respect to the handle, such means being shown as consisting in a springactuated bolt b?, engaging with ratchet-teeth on the rim of the cap A.

A throttle-valve B5 is located within a valveseat B6, which is screwed into a tubular extension on the handle B and controls ports b5 through the valve-seat.

B4 indicates a coupling to which a pipe leading from the motive-duid supply is secured.

B3 indicates a reciprocating spindle, which at one end engages the throttle-valve B5 and at its other end is engaged bya hand-operated lever B3, pivotally mounted in the handle B.

b indicates a passage in the handle B, communicating at one end with a passage controlled by the throttle-valve and its other end in register-With a passage (tin the cylinder A.

An annular chamber A3, formed in the cylinder, communicates with the other end ofthe passage a. A chamber A5 is provided in the end of the cylinder opposite to the handle B,

such chamber communicating with the atmosphere through exhaust-ports d5. Y

A ferrule E is fitted within the end of the cylinder adjacent to the chamber A5, in which a die or snap or the shank of a tool F is located.

A chamber A3, preferably annular in form, is provided within the cylinder and serves as a reservoir to be charged with pressure from Ythe motive-fluid source during the stroke of the piston away from the tool and before the admission of pressure to the working end of the cylinder and to be placed in communication with the larger end of the piston to add impetus to its stroke after the supply of motive fluid has been cut oi from the working end of the cylinder. A circular flange 0,3 separates the reservoir A2 from the end of the cylinder Within which the screw-threaded portion ct of the cap Avengages. A second annular partition a3 separates the reservoir A2 from the annular chamber A3, to which the motive fluid is admitted when the throttlevalve is open.

The piston D is of a differential type and is provided with a shoulder CZ', formed between the main portion of the piston and the enlarged end thereof D. The piston is preferably hollow and provided with ports d., extending from the interior thereof to the outer surface and located adjacent to the end of the piston opposite to the enlarged portion D. The reduced portion of the piston D is of such a diameter as to closely fit the inner surface of the portion A4, which extends between the annular chamber A3 and exhaust-chamber A5. The enlarged portion D of thepiston serves to control the admission of fluid-pressure to the reservoir A2 when its shoulder d passes beyond .the partition 0.3 during a stroke away from the tool, and also serves to connect the reservoir with the working end of the cylinder when the end of the enlargement D passes beyond the partition a2 during the stroke of the pistou toward the tool. The length of the enlargement D is slightly greater than the length of the reservoir A3, and consequently the large end of the piston passes beyond the partition a3 during the stroke away from the tool before the shoulder cl passes beyond the partition a3. Consequently it is impossible for motive fluid to be admitted to the Working end of the cylinder when it is being admitted to charge the reservoir A3.

vThe operation of my improved duid-pressure-operated tool is as follows: The handlelever B2 is depressed, as indicated in Fig. 2, which, through the interposed spindle B3, depresses the throttle-valve B5, so that the latter uncovers the ports b5. Motive tluid consequently Hows from the source thereof through the coupling B4, thence through the ports b5 to the passage b, which registers with the passage a, which in turn communicates with the annular chamber A3. The piston D being in the position indicated in Fig. 1, the motive uid is exerted upon the shoulder d and causes the piston to move toward lthe handle, inasmuch as the larger end of the piston and also the cylinder and chamber A2 therein are in communication with the atmosphere through the exhaust-ports d, the chamber A5, and the ports a5. When in the .movement of the piston toward the handle the enlarged portion D passes beyond the partition a3, motive fluid is admitted around the reduced portion of the piston to the reservoir A3, which is charged with motive tluid during the interval when the shoulder d of the piston moves the distance between the partition a3 and the end of the piston-stroke toward the handle. The enlarged portion D being, as above explained, greater in length than the distance between the partitions a2 and a3 when the shoulder d passes the partition4 a3, the end of the enlargement D has passed the partition a3, so that motive fluid cannot be admitted to the working end of the cylinder. The piston continues in its stroke toward the handle B until the ports d register with the annular chatnber A3, as illustrated in Fig. 2, at which time motive Huid is admitted through the ports d to the interior of the piston and thence to the working end of the cylinder. The greater area of the larger end of the piston is consequently subject-ed to pressure and the piston immediately commences its stroke toward the tool. The communication with the motive Huid is cut oit as soon as the ports d pass out of register with the annular chamber A3, which occurs before the enlarged end D of the piston passes beyond the partition a3. As soon as the partition 0,3 is passed the pressure which has been stored in the reservoir, consisting in the chamber A2, discharges into the working end of the cylinder and adds impetus to the stroke ot' the piston. Upon the ports d being uncovered by the chamber A5 the working end of the cylinder exhausts through the ports a5 and the stroke of the piston in the opposite direction-namely, toward the handle-commences by reason of the motive fluid being exerted upon the shoulder CZ'.

From the foregoing description it will be observed that the stroke of the piston toward the tool is commenced by motive fluid admitted through the piston to the working end of the cylinder, While the stroke of the piston during that portion of its travel when the ports d are closed by the restricted interior ICO IIO

surface A4 of the cylinder is effected not merely by the expansion of the motive Huid which has been admitted directly to the working end of the cylinder from the supply, but

also by the expansion intothe cylinder of the motive fluid which has been charged in the reservoir prior tothe admission of the motive fluid from the supply to the cylinder. By connecting the reservoir with the supply during the interval of the time occupied by the enlarged portion of the piston D' passing from the partition d2 to theend of its stroke the reservoir is completely charged directly from the supply, and only discharges into the working end ofthe cylinder after the stroke of the piston toward the tool has commenced by the admission of motive duid through the ports d to the working end of the cylinder. It is also evident that by admitting the motive liuid through the relatively large ports d to the working end of the cylinder the entire expansibility of the fluid is utilized to impart initial movement to the piston and is not diminished by expansion from the working end of the cylinder into the reservoir.

While I have described more or less precisely the details of construction, I do not wish to be understood as limiting myself thereto, as I contemplate changes in form, the proportion of parts, and the substitution of equivalents as circumstances may suggest-or render expedient without departing from the spiritof my invention.J v

Having now fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a fluid-pressure-operated tool, the combination with a cylinder having a supplychamber, of a dierential reciprocating piston in said cylinder, a reservoi-rin direct communication with said cylinder, means controlled by said piston during its stroke away from the tool for connecting said reservoir` with the supply-chamber prior to the admission of pressure to the working end of the cylinder and means controlled by the piston for subsequently connecting the reservoir with the working end of the cylinder.

2. In a duid-pressure-operated tool, the combination with a cylinder having the bore thereof. enlarged to form a reservoir, of a reciprocating piston within said cylinder having an imperforate enlarged portion greaterin length than the length of said reservoir, said enlarged portion of the piston adapted to connect the reservoir with the source of supply during the stroke of the piston away from the tool and prior to the admission of pressure to the working end of the cylinder.

3. In a fluid-pressure-operated tool,the combination with a cylinder having a differential bore, of a differential reciprocating piston within said cylinder, a reservoir, means controlled by said piston for placing said reservoir in communication with the supply of motive iiuid prior to the admission of pressure to the working end of the cylinder and means controlled by the piston for placing said reservoir in direct communication with the working end of the cylinder.

4. In a fluid-pressure-operated tool, the combination with a cylinder having the bore thereof enlarged to form a -supply-chamber `and a reservoir, of an annular partition between said supply-chamber and said reservoir, a reciprocating piston within said cylinder, and an enlargement onsaid piston closely engaging said annular partition and adapted to pass beyond the same during the stroke of the piston away from the tool and thereby connect said reservoir with the supply-chamber prior to the admission of pressure to the working end of the cylinder.

5. In a duid-pressure-operated tool, the com-A n bination with a cylinder having the bore thereof enlarged to form a supply-chamber and a reservoir, of an annular partition between said reservoir and said supply-chamber, ahollow piston within said cylinder having ports leading from its outer surface to the interior thereof, an imperforate enlargement on said piston of a length greater than the length of said reservoir whereby said reservoir is connected with said supply-chamber prior to the admission of pressure from said supply-chamber through the ports and hollow interior of said piston to the working end of the cylinder.

`6. In a iluid-pressure-operated tool, the combination with a cylinder having the bore thereof enlarged to form exhaust and supply chambers and a reservoir, of an annular partition between said exhaust and supply chambers, a second annular partition between said supply-chamber and said reservoir, a hollow differential piston having a reduced portion fitting the bore of the rst partition and an imperforate enlarged portion tting the bore of the latter partition said reduced portion having ports leading to the hollow interior of the piston and said enlarged portion being of a length greater than the length of said reservoir whereby said reservoir is connected with said supply-chamber prior to the admission of pressure from said supply-chamber through the ports and hollow interior of said piston to the working end of the cylinder.

In testimony whereof I sign this specification in the presence of two witnesses. Y CHARLES HARRIS JOHNSON.

Witnesses:

'H. H. VAUGHAN,

GEO. L. WILKINSON.

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