US2473433A - Pneumatic drilling tool - Google Patents

Description

Jmw M, HQ. A. H. KATTERJOHN PNEUMATIC DRILLING TOOL 2 Sheets-Sheet 1 Filed NOV. 19, 1945 MM K K m M? 7 ATTORNEYS June M, 149. A. H. KATTERJOHN 2,473,433

PNEUMATIC DRILLING TOOL Filed Nov'. 19, 1945 2 Sheets-Sheet 2 INVENTOR.

Ava-(15TH KATTERJOHN BYXWWL A TTORNE Y8 atented June 14, 1949 PNEUMATIC DRILLING TOOL August H- Katterjnhn, Houston, Tex assignor to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application November 19, 1945, Serial No. 629,403

3 Claims. 1.

This invention relates to improvements in pneumatic hammer drills and refers more particularly to fluid distributing valve mechanism for drills of this type.

Heretofore difiiculty has been experienced in valves used to direct motive fluid to reciprocally actuate the piston. The primary difliculty encountered resides in positively holding the valve in its piston retracting position after the piston has been retracted past the main exhaust port as the holding pressure against the tripping face of the valve is then relieved. Holding shoulders have been provided whereby fluid pressure from the main air chamber urges the valve member toward its piston retracting position. However, this expedient has not proven entirely satisfactory in that the fluid pressure exerted against this shoulder is subject to rapid fluctuation due to the operation of the hammer drill.

An object of this invention is to provide a hammer drill in which the valve mechanism is positively held in eitherof its functioning positions.

Another object is to provide a hammer drill in which the valve mechanism is positively held in either of its functioning positions and is ex tremely sensitive or responsive to the action of the motive fluid utilized to trip the valve from one operative position to the other.

A further object is to provide a valve mechanism for hammer drills which assures an increased number of hammer blows per unit of time.

Still another object is to provide a valve mechanism which assures an increased number of hammer blows of great force per unit of time with a minimumconsumption of motive fluid.

Other and further objects of this invention will appear from the following description:

In the accompanying drawings which form a part of the instant specification and are to be read in conjunction therewith wherein like reference numerals are employed to indicate like parts,

Fig. 1 is a top plan view of a drill hammer embodying this invention,

Fig. 2 is a view taken along the line'2-2 in Fig. '1 in the direction of the arrows showing the valve mechanism and piston in a retracted position,

Fig. 3 is a view similar to Fig. 2 but showing the valve mechanism and piston in an advanced position, and

Fig. 4 is a rear end view of the valve bushing taken along the, line 4-4 in Fig. 3.

Referring to the drawings, the invention as illustrated has a cylinder 1 providing a cylindrical chamber 2. A hammer piston 3 is reciprocally mounted within this chamber. The device 2, is provided with a conventional mechanism for imparting an intermittent or step by step rota.- tion of the piston '3" which in the interest of simplicity is not shown in its entirety in the drawing. Such mechanism includes the spiraled rifle bar 4 on which the piston is slidably mounted and ratchet ring 5. The latter is located in the rear end of the cylinder l. The ratchet ring 5 cooperates with ratchet mechanism carried in the head 6 of the rifle bar to limit rotative movement to one direction. While the rifle bar and ratchet play no direct part in the instant invention, it-is believed necesary to show them to lllustrate'relar time positions of the parts.

In order to distributethe motive fluid to the cylinder 2 in such'manner asrtoreciprocate the piston a valve mechanism including a valve chest or case I is placed in the rear or counterbored portion of the cylinder. A valveguide bushing or cap 8 encircles the rifle bar and an automatic valve 9' is mounted between the valve chest and guide bushing. The sleeve portion ll] of the guide bushing serves as a bearing for the rifle bar and its outer periphery provides a bearing surface on which the automatic valve 9 reciprocates.

An internal annular groove H within valve case 1 communicates by a plurality of passageways l2, one of which is shown in dottedlines in Figs. 2 and 3, with the live pressure fluid chamber at the rear end of the valve case, and thus receives live pressure fluid. These passageways I! are of such number and are spaced to register with ports 8a in the valve bushing and best shown in Fig. 4. To complete the passageways communicating with the main air chamber (not shown in the drawing) in the rear end of the casing in back of the ratchet wheel, ports-5a in the ratchet wheel register with ports 8a. An annular recess 8b in the rear face of bushing 8 also communicates with the ports 5a and Ba and forms a part of the main air chamber. The valve chest also has holes l3 communicating between cylinder chamber 2' and groove l 1 adapted, when the valve member 9 is in a rearward or retracted position as shown in Fig. ,2- to receive pressure fluid from groove 1 l whereby the piston is advanced on its power stroke. An annular groove M in valve chest! on the opposite side of groove ll communicates by passages or groove II and chamber l4 when the valve is in its extreme forward position. Still another internal groove I! in the valve case adjacent groove l4 opens into the exhaust passage [8 and exhaust port l9 to relieve fluid pressure from the forward end of chamber 2 on the power stroke of the piston. Groove 9a communicates between grooves l4 and I! when the valve is in the retracted position as shown in Fig. 2, serving with passages l5 and iii to complete this connection. Fluid is then exhausted from the forward portion of cylinder 2 through passages l5 and IE, groove l4, groove 9a, groove ll, passage I8 and exhaust port IS on advancement of the piston.

The valve case adjacent its rear end has a counterbored portion 20 to receive the flanged rear end 2! of valve 9. Communicating with this counterbored portion on opposite sides of flange 21 are passages 22 and 23, leading to an auxiliary exhaust port 25 in the cylinder wall. Passage 22 is a small bleeder passage. The annular projection or sleeve iii of the guide bushing 8 is provided with an intermediate portion of one diameter and a rear portion of somewhat larger diameter. Valve 9 also has corresponding internal surfaces of two different diameters providing an annular shoulder 25 at their junction which may be referred to as a holding shoulder.

To shift valve 9 to its forward position pressure fluid is admitted to the rear face of the flanged end H from chamber 2 through the passage '26 in the cylinder and the port 2'! in the valve case when the piston is in a forward position.

To supply holding pressure fluid to holding shoulder 25 a groove 28 in the periphery of the valve guide bushing 8 communicates with an auxiliary live fluid chamber or reservoir 29 in the form of a relatively large annular recess in the inner surface of the guide bushing through a plurality of relatively short passageways or openings 30. The number and shortness of these passageways permit rapid flow of motive fluid between the live air chamber 29 and the groove 28. The auxiliary live fluid chamber 29 is connected to the groove 81) forming part of the main live fluid space by means of a single relatively long narrow or tortuous passageway 3|. The length and diameter of this passageway prevents the rapid passage of fluid between the chambers thereby substantially reducing fluctuations or pulsations within the auxiliary chamber 29. Thus pressure fluctuations, usually of a rapid character, within the chamber surrounding the ratchet mechanism due to the pulsations produced by the rapid action of the valve and piston are substantially dampened, providing a relatively constant pressure fluid chamber communicating with the holding shoulder.

The main exhaust port 32 is located approximately centrally of chamber 2. Ports 33 and 34 communicate between chamber 2 and passage 26 on transverse planes rearwardly adjacent exhaust 32. The piston head 3 is provided with two spaced annular portions fitting the interior of cylinder chamber 2 and separated by annular groove iii. This groove is wide enough so that in one position it provides communication between port 33 and the m'ain exhaust port 32 to relieve the pressure behind the flanged end 2| of valve 9 and closing off both ends of the cylinder chamber from port 22. Thus no substantial pressure is exerted on the rear face of flange 2! on either piston stroke except for the portion of the power stroke when the ports 33 or 3 are exposed and before the exhaust port 32 is uncovered.

In other words, the holding shoulder is relied upon to maintain the valve in the forward position.

Referring to Fig. 1, the drill casing is seen to comprise the front head 31 and the rear head 38 joined together in a conventional fashion at opposite ends of cylinder l by means of side rods 39. These rods are inserted through apertured lugs 31a and 38a integral of the heads respectively and are held in place by nuts 40. Back head 38 has a manually controlled throttle valve 4| mounted therein to control passage of motive fluid to the device from connection 42 leading from a source of motive fluid.

In operation, power fluid such as compressed air is supplied to the device through the usual valved hose connections communicating with the main live air space in back of the ratchet mechanism. From this space the live air flows through the passageways 5a, 8a and i2 into the groove ll. At all times when the throttle valve is open live air under pressure is also admitted from the chamber formed by groove 812 through the small passageway 35 into the auxiliary live air chamher as, and thence through the plurality of openings 39 into the groove 28. This pressure in groove 23 acts against the shoulder 25 constantly urging valve 9 into a forward position. As heretofore explained the pressure thus applied to shoulder 25 is maintained substantially constant and does not reflect the fluctuation of air pressure within the main air chamber. The character of the relatively long and narrow passageway 2! prevents the transmission or reflection of the rapid fluctuations within the main air chamber to the auxiliary chamber. On the other hand, the number and character of the openings 30 permit a rapid flow of pressure fluid into groove 28 from the auxiliary air chamber. Accordingly the holding shoulder 25 at all times during operation of the device has exerted against it a relatively constant fluid pressure or force urging valve 9 to a forward position.

With the valve and piston in the position illustrated in Fig. 2, live air from the groove 11 will be admitted past the front end of the valve through the openings [3 against the rear face of the piston 3 forcing the piston forward on its power stroke. As the hammer piston advances, the live air follows it along the path just mentioned until the piston reaches the position where port 3:3 is uncovered. At this time live air is admitted through port 32, pasageway 26 and port 2'! into chamber 28. This pressure in chamber 24) exerted against the rear face of the valve flange forces the valve member forwardly in a snap action as the area of the flange is greater than the area of the front face of the valve. Obviously when the piston advances to a position to expose passage the pressure exerted against the rear face of flange 2! is substantially equal to that exerted against the front face of the valve. The flange face havin a greater area valve member 9 is shifted in a snap action to the position illustrated in Fig. 3.

While the valve is changing positions piston 3 completes its forward movement due to its momentum as well as the continued expansion of air behind the piston until the main exhaust port is uncovered. The uncovering of port 32 releases the live air under pressure within the rear portion of the cylinder chamber.

With the valve shifted to its forward position and the pressure Within the rear portion of the cylinder chamber 2 vented through exhaust port 32, the pressure on the rear or flanged end of the valve as well as that on the front end will be substantially relieved by virtue of exhaust port 32 and the auxiliary bleeder passage 22. The valve, however, will continue to remain in its forward position because of the constant pressure exerted against the shoulder 25 on the internal surface of the valve.

With the valve and piston in their forward positions, live air is admitted from groove ll through groove 9a on the periphery of the valve into groove I l, which communicates through passages l and IS with the forward end of cylinder chamber 2 to supply motive power thereto for the piston during the retraction strokes.

As the piston moves rearwardly exhaust port 32 is first closed, but immediately afterward the rearmost portion of the piston that fits the cylinder passes the exhaust port so that the exhaust communicates through groove 35 with port 33 to prevent the building up of pressure in passages 26 and 21 and against the rear face of the valve flange 2!. After the piston covers the port 34 on its return stroke, pressure commences to build up within the rear end of cylinder chamber 2 until it becomes great enough against the front face of valve 9 to move the valve to its rearward position. The piston continuing its rearward travel again uncovers exhaust port 32 releasing the fluid pressure in the forward end of cylinder chamber 2. Any pressure remaining in the forward end of the cylinder chamber 2 when the piston on its next power stroke closes the main exhaust port 32 is exhausted to the atmosphere through ports l5 and IS, the grooves 9a and I! and ports l8 and I9 permitting the piston on its forward stroke to move freely and deliver unrestricted forceful blows to the drill steel with maximum frequency.

Thus it will be seen that the valve 9, moved forward with a snap action by live pressure fluid, remains in that position due to the constant pressure exerted against the holding shoulder 25 when the pressure is removed from the front and rear faces of the valve when the piston uncovers the main exhaust port 32. The valve is held in its forward position until the compressed fluid developed on the return stroke of the piston, exerted against the front face of the flange, is sufficient to overcome the constant pressure against shoulder 25. This build-up of pressure results in the valve moving with a snap action to its extreme rear position. The points at which the valve 9 will shift as compared to the position of the hammer piston 3 on its return stroke may be accurately calculated as the pressure within the auxiliary live air chamber 29 is substantially constant.

From the foregoing it will be seen that by virtue of the construction described, there has been provided a means by which the holding shoulder on the valve is connected to a live air space at the rear of the valve assembly through an intermediate constant pressure reservoir or trap. This eliminates long and numerous passageways between the shoulder and its live air source by providing the relatively large auxiliary air reservoir adjacent the shoulder. The connection between the main and auxiliary air chamhers is a restricted passage which reduces the reflection in the auxiliary chamber of the pressure pulsations or fluctuations in the main chamber. Thus these pressure fluctuations or pulsations are not effective against the holding shoulder within the valve. Instead a relatively constant pressure is applied to the holding shoulder materially 6 increasing the eificiency, utility and rapidity of the device as well as other advantages which are inherent to the construction.

Other objects and advantages of this invention will be apparent to one skilled in the art.

Having described my invention, I claim:

1. In a reciprocable piston type fluid actuated hammer tool having a live fluid chamber from which live fluid is fed alternately to the piston to advance and retract it, a fluid actuated slide valve for controlling the application of said fluid to the piston, said valve having a holding shoulder formed thereon adapted to receive live fluid to urge the valve at all times toward piston retracting position, and means for connecting said live fluid chamber to said shoulder at all times, said means having a passage from said chamber to said shoulder comprising an auxiliary live fluid reservoir intermediate the ends of said passage, the portion of said passage between said chamber and reservoir being relatively small and restricted, and the portion of said passage between said reservoir and shoulder being relatively large for permitting free flow of fluid between said reservoir and said shoulder.

2. In a fluid actuated hammer tool, a body having a cylinder therein, a reciprocable power piston in said cylinder, a valve chest, 2. fluid pressure controlled sleeve valve slidable in said chest, an annular recess having motive fluid supplied thereto, motive fluid conveying passages leading from said recess and controlled by said valve to direct power first to one side of said piston to advance it On its power stroke and then to the other side to retract it, said valve being provided with a holding shoulder adapted to receive live fluid under pressure to urge the valve at all times toward its last mentioned position, and means having a live fluid passage connecting said annular recess with said shoulder, said passage in. cluding an auxiliary live fluid reservoir, a pressure equalizing opening from said annular recess to said auxiliary reservoir, and a plurality of flow openings from said auxiliary reservoir to said holding shoulder.

3. In a reciprocable piston type fluid actuated hammer tool having a live fluid chamber, live fluid conveying passages leading from said chamber to the opposite sides of said piston, a fluid actuated sleeve valve for controlling application of live fluid from said passages alternatively to the opposite sides of said piston to advance and retract it, said valve having a holding shoulder formed thereon adapted to receive live fluid to urge the valve at all times toward piston retracting position, and means for connecting said live fluid chamber to said shoulder at all times, said means having a small passage leading from said chamber to an auxiliary live fluid reservoir and another passage leading from said reservoir to said holding shoulder.

AUGUST H. KATTERJO-HN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,828,491 Curtis Oct. 20, 1931 1,836,688 Smith, Jr Dec. 15, 1931 1,889,423 Smith, Sr Nov. 29, 1932 1,929,419 Gartin Oct. 10, 1933 1,929,457 Tardiff Oct. 10, 1933 1,929,458 Tardiff Oct. 10, 1933 2,017,287 Nell Oct. 15, 1935

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