US1126943A - Fluid-operated percussive-tool. - Google Patents

Description

L. BAYLBS.

FLUID OPBRATED PERCUSSIVE TOOL.

APPLICATION FILED JUNE 9, 1914.

Eatemed Feb. 2, i915.

Lewis c. Barnes,

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Specicatonof Letters Patent,

Patentedeb. 2, 19133.`

iApplication iiledJune a, 19111. `Seriallc..$413,926.

' To all whom it may concern .7

Y tain new and useful-Improvement inl.` Operated Percussive .l`ools,.of which the fol-r lowing is a speciicatlon.

This invention relates to fluid operated percussive tools, and more particularly to tools of the type wherein the admission of iiuid is controlled primarily by theH movement of the piston. 'I

The object of this invention is to provide an auxiliary valve for controlling the admission of iiuid to one portion of the cylinder to increase the eiiciency of the piston blow. This, object isv accomplished bythe invention, a practical embodiment of which is shown in the accompanying drawings, in which,

Figures 1 and 2 are 'longitudinal sections showing the pistonand auxiliary valve inI dii'erent positions.

ln the drawings is shown acylinder l which consists of a smaller' forward bore 2 and a' larger rearward bore 3.l In the cylinder 1 is a piston having a head 5 sliding in the rearward bore 3 and a hammer'bar 6 sliding in the forward bore 2, therebeirig a neck 7 between the hammer bar'and the head of the piston. Fluid is admitted constantly to the forward endof bore@ by a passage 8. From the forward end of bore 2,'somewhat rearward of the passage 8, a passage E? leads to the rearward end of the bore 3. From the passage 8 a passage 10 leads rearwardly along the cylinder, this passage having two ports, 11 and v12, open-l ing into the rearward end of bore 2, the forward of these, 11, being so placed as to be uncovered by the hammer bar 6 and allow :duidto pass to the forward end of the bore 3, when the piston is practically at the forward end of stroke, while the rearward port 12'when open admits fluid for a considerable portion oi the piston stroke, To control the port 1&2 a valve 13 is Iprovided which has a head 14 sliding in a valve chest 15 and a. port controlling portion 16 adafpted 'to project into port 12 and close it 'rom communication with passage 10. The inner end'aof the valve chest 15 is connected with the forward end vof bore 3 by a passage 17', while the outer end is connected with the rear lend ofl bore 3 by a pasagev 18. Anexhaustpassage 19 is providedfor both vends of the rear bore 3, it being soplaced as to be kuncovered by the piston near the 'en-d (if the piston stroke. in each direction. p

1n operation, supposing the parts to be in the `positions shown in'iFig. 1, air is being admitted .to the forwardend of bore 2 and lto the rear end'. ofv bore 3 through the passage 9. Allnder such conditions there will be pressure inthe. outerven'd of valve chest 15 and no pressure in the inner end, `the forward end of bore 8 being open to atmosphere through portA 19. The pressure in the rear end ofbore on' the larger area of the p1ston head, willdrivethe piston forwardly against the lpressure on the forward end of the hammerv bar 6, the fluid in the front of bore -3 exhausting for part of the stroke through port 19. As the Ypiston moves ior-l wardly'the hammer bar 6 will cover the pas sage 9 so that the fluid in the rear end of the bore 3 will act expansively to move the piston forward. Further movement of the piston will cause the hammer bar 6 to uncover the port 11. This will admit'air to the forward end ofv bore 3 and at the same time the exhaust port 19 will be uncovered by the rear face 'of the piston head exhausting the rear end of the cylinder and also the youter end of the valve chest 15 through the passage 18. The pressure in the inner end .Y

of the valve chest 15 through-the passage 1'7 and also the pressure on the end of the port controlling portion 16 will move the` valve 13 outwardly opening th port 12. vThis will allow .fluid to enter the front end of the bore 3 for a considerably longer period during the back stroke than during the forward stroke-and thus will produce a full.

backward stroke of the piston, while by reason of the fact that the port 12 is closed during the forward stroke, the piston will strike a much harder blow on account of the absence of a live air cushion in the front end of kbore 3.

lt is to be understood that while the present showing and description disclosesonly one specified modification of the invention, other forms and modifications are included in the spirit and scope of the invention as expressed in the claims.

lVhat I claim is: 1. ln a percussive tool, a cylinder, having a larger rearward portion and a smaller forward portion, a pistn in said cylinder having a head in said rearward cylinder portion and a hammer bar in said-forward cylinder portion,l means for admitting fluid constantly to the forward end of said cylinder', a passage controlled by the piston for admitting Huid to the rearward end of said larger cylinder portion, a passage for admitting fluid to the forward end of said larger'cylinder portion,' a valve 'controlling said passage, and means for moving said valve tu open said passage near the forward end of the piston stroke. i

2. In a percussive tool, a cylinder, a piston having two smaller surfaces for driving it in one dii ction and a larger surface for driving it in the other direction, means for admitting pressure constantly to one of said smaller surfaces, means for admitting fluid intermittently to the other ofsaidsm'aller surfaces comprising a valve, and means Ifor admitting fluid intermittently to said larger surface.

3. In a percussive tool, a cylinder, a piston having a head and a hammer bar, means for admitting fluid to exert a constant pressure on the forward end of said hammer bar,

means controlled by said piston fQr admitvting fluid intermittently to eXert pressure on the rear of said piston head, and means com a prising a valve for admitting fiuid intermittently to exert pressure on the forward face oi said piston head.

4. In a pereussive tool, a cylinder, a piston having a head and a hammer bar, means for 3 exerting a constant fluid pressure on the for Ward end of the hammer bar, means for eX- erting an intermittent fluid pressure on the rearward face of said piston head, and means for exerting an intermittent pressure on the 4 forward face ofsaid piston head comprising a valve.

5. Ina percussive tool, a cylinder, a piston having a head and a hammer bar, means for exerting a constant. fluid pressure on the f forward' end of the hammer bar, means for exerting an intermittent fiuid lpressure on the rearward `face of said piston head, and

p means for exerting an intermittent pressure on the forward face of said piston head. i

In testimony whereof, I have hereunto set my hand.

LEWIS C. BAYLES. Witnesses:

FRED S. OVERTON, OTTO W. HOLMGREN.

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