US1350342A - Valve for percussive tools - Google Patents

Description

W. A. SMITH.

VALV E FOR PERCUSSIVE TOOLS. APPLICATION FILED OCT. 25, 1919.

1 ,350, 342, Patented Aug. 24, 1920.

2 SHEETS-SHEET l. 5 17 1 8 ]6 [21 18 Rama 4 4 w f x fi W. A. SMITH.

VALVE FOR PERCUSSIVE TOOLS.

APPLICATION FILED OCT. 25,1919.

1 ,350, 342. Patented Allg- 24, 1920.

2 SHEETSSHEET 2. 14

INVENTOR.

UNITED STA, EsrAr-ENT OFFICE.

WILLIAM A. smn'n, or EASTON, P NNSYLVANIA, 'ro INGERSOLLPRAND COMPANY, or masnx CITY, NEW JERSEY, A'conrokA'rIoN 01 NEW JERSEY.

vALvL FOR rnnoussrvn mooLs.

To all whom it may concern:

Be it known that I, WILLIAM A. SMITH,

a citizen of the United States, residingat Easton, in the county of Northampton and State of Pennsylvania, have invented a certain new and useful Improvement in Valves for Percussive Tools, of which the following is a specification.

This invention relates to a fluid operated percussive tool, and in particular tov a percussive tool of the diii'erential piston type having a valve for distributing fluid pressure to some parts of the cylinder to operate the piston or hammer.

The objects of the present invention are to provide a differential piston percussive tool with a very simple form of piston having two pressure areas to force it in one direction and one pressure area'to force it in the opposite direction.

. Another object of the invention is to provide a percussive tool of the hammer type with a fluid distributing valve which will control the admission of fluid to one end-of the piston cylinder and will also control the exhaust of a part of the fluid from both ends of the cylinder.

A further object of the invention is to provide a percussive tool with a simple form of valve which may be conveniently located at one side of the cylinder in a compact and easily accessible position.

A further object of the invention is to construct the valve so that it will operate quickly and sensitively in order that the number of blows of the piston may be as great as possible.

With these and other objects in view my invention consists in the features of construction and operation set forth in the following specification.

In the drawings annexed hereto and forming a part of this specification;

igure 1 shows a longitudinal sectionalview ofthe valve and a part of the valve chest and cylinder.

Fig. 2 a longitudinal view of'the complete tool in section with the piston and valve in one operative position.

' Fig. 3, a view similar to Fig. 2 with the piston and valve in another operative position.

Fig. 4, a longitudinal view in section of a slightly modified form of the invention.

Specification of Letters Patent.

Patented Aug. 24, 1920.

Application filed October 25, 1919. Serial No. 838,882.

Figs. 5 and 6, views similar to Fig. 4 with thepiston and valve in different operative POSItlOIlS.

Referring now more particularly to Figs. 1-2-3 of the drawing, the cylinder of the percussive tool is shown at 1, having a large bore 2 and a small bore 3 in which reciprocates a piston 4. Piston 4 is provided with a head 5 adapted to slide in the forward bore 2 of the cylinder and also a shank 6 fitting the small bore 3. Preferably the piston is made with a symmetrical shank 6 extending forwardly from the piston head 5., of the same diameter and length as the shank 6. This forward shank 6 of the piston fits within the chuck 7, in the forward end of which fits the drill steel or other percussive implement 8. The chuck 7 and cylinder 1 are adapted to be held rigidly together by any suitable means not shown.

From the above description-it will be seen that, a construction is'provided which will- .permit the piston 4 to be reversed upon itself when one end becomes damaged or broken.

At the rear end of the cylinderl is provi ed a fluid cavity 9 communicating by a port 10 with an inlet of any type adapted to supply motive fluid to the drill from any suitable source. The cavity 9 is of larger diameter than the small bore 3 so that pressure is continually exerted atia constant pressure against the rear face of the piston shank 6, thus forcing it at all timestoward the forward end of its stroke. the stroke of the piston 4 a conduit 12 is provided which is opened at or near the forspaced somewhat from the head 15 by a- .neck portion 17, and at the rear end of the valve 14 a head 18 is provided slightly smaller in diameter than heads 15 and 16. Extending continuously from end to end of the valve 14 is a leak port 19 which'intercepts a short leak port 20 in the neck por- To reverse tion 21 of the valve 14, which, during the o eration of the tool is continuously supplied with fluid at constant pressure from conduit 22.

With the piston'in the above position as shown in Fig. 2 it is about to start upon its forward stroke and the valve 14 is already moved to its foremost position, enabling fluid pressure to be supplied to port 22 which is in communication with the pressure cavity 9, past the neck 21 of the valve 14 and into the rearward part of the cylinder bore 2 through the port 23. Pressure exerted upon both of the rearward pressure areas of the piston thus forces it forwardl to the position shown in Fig. 3, by whic time the piston has passed the central exhaust port 13, thus allowing the'fluid pressure in rear of the cylinder bore 2 to escape and has opened communication by means of the conduit 12 from the pressure cavit 9 to the forward end of bore 2, so that orward pressure on the rearward face of the shank 6 is resisted by full pressure upon a pressure area on, the front face of the head 5.

During the forward stroke of the piston 4 after passing the central exhaust port 13 pressure in advance of the piston head 5 continues to be exhausted from the forward end of bore 2 through port 24, until this port is overrun by the piston, after which time the ressure begins to build up'in advance 6f the piston head 5. This increased pressure combined with the pressure supplied in advance of the head 15 of valve 14 through the conduit 19 forces the valve 14 to its rearmost position as indicated in Fig. 3. This movement of the valve 14 closes the auxiliary exhaust port 24 near the forward end of the bore 2 and simultaneously closes the admission port 23 at the rear end of bore 2. The-piston 4 is now ready. to make its return stroke which it is enabled to do by means of the pressure in advance of the head supplied through conduit 12. In order to continue the exhaust of fluid pressure from the rear end of bore 2 after the central exhaust port 13 closes another auxiliary exhaust port 26 is provided opened by the rearward movement of the valve 14.

It will be noted that the valve 14 is constantly urged toward its forward position b a constant pressure exerted on this valve. 'I his pressure area is represented by the difference in areas between the rear of head 16 and head 18 of the valve. The valve is enabled to move to its rear position by pressure in advance of the head 15 overcoming this slight forwardly exerted constant pressure. Throughout the operation of the tool fluid passes into the leak port 19 by means of port 20 which is always open to pressure from chamber 9 and conduit 22.

With the valve in the position of Fig. 2,

zming of the valve.

for instance, after port 24 is closed by the' to throw the valve past the port 25 is thus built up due to fluid passing through passa e 19 and to leakage around the valve.

y means of this supply of fluid to both ends of valve 14 the cushioning chamber at the extreme ends of the valve chest is being continually supplied with fluid thus increasing the cushionm of the 'valve at either end of its stroke an aidin materially in its quickness of action am? preventing slam- The above described construction gives a i very quick actin valve, enabling the piston to make a rapi striking blow which will be practically uncushioned until it is about to strike the drill steel 8.

The rearward movement of the valve 14 is begun by means of the leakage mentioned and the pressure supplied through leak port 19 and 1s completed as soon as the valve moves slightly past port 25. As soon as the piston 5 moves rearwardly sufliciently to uncover the central exhaust port 13 the pressure at the forward end of valve 14 drops thus permittin the constant pressure forcing the valve orward to throw the valve forwardly again.

Referring now to Figs. 45 and 6, a differentmethod of operating the valve 14 is shown. This comprises a small conduit 30 extending from a'portion of the small bore 3 of the cylinder 1 at a point overrun by the shank 6 toward the end of the forward stroke of the piston and opening at its other end into the valve chest in advance of the valve head 15 as shown at 31*. With this method of reversing the movement of the valve 14 the pressure is supplied from a constant pressure source comprising one of the cylinder chambers overrun by the piston during a portion of its stroke, and is independent of the amount of fluid cushioned in advance of the piston head 5 at the very end of the piston stroke. Furthermore the position of the orifice 31 of this conduit 30 may be accurately determined so that the valve will be thrown at a definite and accurately determined point in the stroke of the piston while in the modification shown in Figs. 1-2 and 3 the point at which the valve 14 may be thrown might vary due'to the difference in pressure at either end of the valve 14 at different times due to the leako the forward end of the cylinder bore 2.

The valve 14 in this modification of the invention is constantly forced to its forward position in the same manner as the modificaa e of fluid passing the valve heads or out .versing the movement of soon as piston 5 moves tion shown in Figs. 1-2-3, and also 0 erates the auxiliary exhaust ports 23 an; 24 in the same manner.

31 is overrun by the piston shank 6 during the forward stroke of the piston which'occurs toward the end of that stroke, fluid passes through conduit 30 to the port 31 and forces the valve to its rearward position. Almost simultaneously the shank uncovers the rear port of conduit 12 thus rethe piston 5. As far enough on its rear stroke, port 25 is overrun by head 5 so that the fluid supplied through port 12 is augmented by fluid through conduit 30. Continued movement of piston 5 uncovers port 33 which intercepts and forms an additional openingfor conduit 30 so that as soon as this port}- is opened this port may convey fluid to the forward end of bore 2. As soon asthe piston overruns the central exhaust port 13 pressure is exhausted from conduit 30 and'the forward end of the valve chest through port 33, thus enabling the valve 14 to'again move forwardly.

The valve 14 shown in Figs. 4-5 and 6 moreover is made solid, that is, without the provision of the leak port extending from end to end. of the valve.

In other respects the construction and operation of the tool shown in Figs. 15 and 6 is similar in every way to that shown in Figs. 1-2 and 3.

It is to be understood that the present showing and description disclose only one specific embodiment of my present invention, and that other forms and modifications are included within the spirit and scope thereof, as expressed in the appended claims.

' cylinder and a plurality of auxiliary exhaust 1. In a percussive tool, a valve chest, a valve adapted to operate therein, a head at one end of said valve controlling an auxiliary exhaust port, a head intermediate the ends of the valve controlling an admission port and an auxiliary exhaust port, said valve being forced in one direction by constant pressure against one end face and thrown to its opposite position by a fluctuating pressure against an opposite end face.

2. In a percussive tool, a valve chest, a valve adapted to operate therein, a head at one end of said valve controlling an auxiliary exhaust port near one end of the cylinder, a head intermediate the ends of said valve controlling an admission port and an auxiliary exhaust port near the opposite end of said cylinder, said valve being forced in one direction by constant pressure against one end face and thrown to its opposite position As soon as the port ating within said by a fluctuating pressure against an opposite end face.

. 3. In a percussive tool, a cylinder, a piston therein, and a valve chest provided with an admission port intercepting one end of. the cylinder, and a pluralit haust ports from said cylinder, a valve opervalve chest, said valve provided .with a head controlling an auxillary exhaust port and another head controlling an admission port to a cylinder pressure chamber and another auxiliary exhaust port, a third head provided on said valve of smaller diameter than the first mentioned heads, a conduit extending from a constant pressure chamber of said cylinder to one end of the valve, whereby fluld may be supplied to one end of the valve chest to throw the valve in one direction.

4. In a percussive tool, a cylinder, 9. piston therein, and a valve chest provided with an admission port intercepting one end of the cylinder and a plurality of auxiliary exhaust ports from said cylinder, a valve operating within said valve chest, said valve provided with a head controlling an auxiliary exhaust port and another head controlling an admission port to a cylinder pressure chamber and and another auxiliary port,-a third head provided on said valve of smaller diameter than the first mentioned heads, a conduit extending from a constant pressure "chamber of said cylinder and overrun by said piston near one end of its stroke, whereby fluid may be supplied to one end of the valve chest to throw the valve in one direction.

5. In a percussive tool, a cylinder, a piston therein, and a valve chest provided with an admission port'intercepting one end of the ports from said cylinder, a valve operating within said valve chest, said valve provided with a head controlling an auxiliaryexhaust port and another head controlling an admission port to a cylinder pressure chamber and another auxiliary port, a third head provided on said valve of smaller diameter than of auxiliary exthe first mentioned head, a conduit extend- I ing from a constant pressure chamber of said cylinder and overrun by said piston near one end of its stroke, said conduit hav ing a port intercepting and overrun by the piston head to permit an exhaust of fluid.

from the forward bore of the cylinder during a portion of the rearward stroke of the piston, to allow the valve to return to its forward position.

In testimony whereof I have hereunto set my hand.

7 WILLIAM A. SMITH.

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