US1898493A - Fluid pressure tool - Google Patents

Description

-Feb. 2l, 1933. G, M. NELL FLUID PRESSURE TOOL Filed Feb. l, 1929 2 Sheets-Sheet `l 12km/Lm ATTORNEY,

Feb. 2l, 1933. G. M. NELL FLUID PRESSURE TOOL Filed Feb. l, 1929 2 Sheets-Sheet 2 INVENTOR. Gasm/e /M A/@// 24 ,C www A TTORNE Y.

Patented Feb. 21, 1933 UNITED `STATES PATENT OFFICE GUSTAVE MLNELIJ, OF DETROIT', MICHIGAN, ASSIGNOR T0 CHICAGO PNEUMATIC TOOL COMPANY, NEW YORK, N. Y., A CORPORATION OF NEW JERSEY FLUID PRESSURE TooL Application filed February 1, 1929. Serial No. 336,880.

This invention relates to fluid pressure motors of the type embodied in percussive machines generally, of which pneumatic hammers and hammer drills are the more common examples. More particularly it relates to tools and machines using motors in which the distribution of the motive fiuid is controlled by a valve thrown automatically in timed relation with the movements of the piston.

One object of the invention is to provide an improved form of percussive motor having a simple, compact and easily assembled valve structure. Another object is to dispose the valve structure concentric with the main operating parts of the machine thereby to avoid the customary large projection which makes such machines awkward to handle and to operate. Another object is to provide for exact determination of the quantity of motive fluid passing to the ends of the piston chamber. Still another object is to effect accuratelyitimed and positive movement of the valve. Other objects will be apparent from the detailed description which follows.

In order to illustrate the invention one concrete embodiment thereof and certain modified forms of the valve are shown in the accompanying drawings in which:

Fig. 1 is a longitudinal sectional view of a percussive drill; Y

Fig. 2 is a sectional view of a detail of Fig. 1, namely the valve assemblyV and indicating a slight modification of the valve, the section being taken substantially on the line 2-2 of Figs. 3 and 4; l Y Figs. 3 and 4 are respectively left and right end elevational or plan views of the ,valve assembly shown in Fig. 2

Fig. 5 is a sectional view substantially on the line 5--5 of Fig. 2 showing'a modification of the valve; and

Fig. 6 is asectional view similar to Fig. 5 showing the valve of Fig. 1. Y f

In the embodiment of the invention chosen for the purpose of illustration the cylinder 7 of the percussive drill has an atmospheric exhaust'port 8 intermediate its length arranged to be overrun and controlled by the hammer piston 9 which is reciprocated within the piston chamber of the cylinder to impart blows to a suitable working tool such as a drill steel 10. The steel is supported for rotation in the chuck 11 in front head 12 and may be hollow to permit cleansing fluid to be fed thereto through the usual tube 13 extending axially through the drill.

The rearward end of cylinder 7 is counterbored to receive and to support, in line with the piston chamber, a valve assembly which preferably comprises valve case 14, valve lid 15, and valve 36. In the form shown, a ratchet ring 17 is also inserted within the counterbore of cylinder 7 against the valve chest to support the head of a rifle bar 18,the bar portion of which extends through aligned bores v15a and 14a of parts 15 and 14 comprising the valve chest. A back head 19, in which tube' 13 is preferably supported, engages ring 17 to hold the same and the valve assembly in place in the cylinder, .the back headbeing in turn held in place by any suitable means such as the usual side rods or through bolts (not shown).

As indicated, case 14 and lid 15, comprising the valve chest, provide therewithin valve chamber which in the present instance is annular in shape. An annular series of ports 2O open through one kend wall of the valve chamber, namely, through case 14 (Figs. 1, 2, and 4) into the rear end of the piston chamber. A complementary series of ports 21 inthe opposite end wall of the valve chamber, namely lid 15 open into passages 21a which extend radially and then make a right-angular turn in a forward direction and register with connecting passages 21?) in case 14, and 210 in cylinder 7, to enter the piston chamber at the forward end thereof. Ports 2O land 21 are controlled by a suitable valve such as 36, which has end faces 36a and 365 for this purpose, and provide therebetween, within the valve itself, a chamber for pressure huid. The valve is shown as annular in shape and mounted for movement entirely within the confines of case 14. The valve may have a bearing or sliding fit with case 14 either on the inner or. outer peripheral wall of the valve chamber. In Fig. 2, valve 16 slidingly engages only the central boss of case 14, which boss is made hollov7 or perforate by reason of the bore 14a. The valves 26 of Fig. 5 and 36 of Figs. 1 and (S, have a sliding fit or bearing upon both the inner and outer peripheral walls of the valve case 14.

Pressure fiuidis suppliedgto the central chamber of valves 16, 26, or 36 frominlet 22 in the back head 19 which communicates with an annular chamber 22a inthe face of the headV adjacent vring 1,7. j An rannular series of passages 22?) extend through ring 17 and register with similar passages 220 ofcase 14, the latter passages taking av right-angular bend to open into the valve chamber substan-l tially centrally thereof. The motive fluid in the central chamber of the valve is distributedalterna-tely to ports 20 .and 21-at the ends of the valve chamber. depending upon the position of the valve. Means are provided, however, forirestricting the volume of motive fluid :to an amount less than the capacity of the ports at each end ofthe valve chamber. In the formfof the valve shown in Fig. 2, this is accomplished by extending the endfaces almost to the outer wall of the valve chamber but leaving 'a narrow peripheral passage, the extent of which is indicated Aby the space between the two adjacent broken lines shown in Fig. 3. In Fig. 5 the same result is accomplished with valve 26 bythe provision of a series ofnotches 26a in the periphery thereof. Still'another variation is shown in Fig. 6 wherein the passage of motive fiuid through the end ,faces of valve 36is provided for by ay series of ports 36a adjacent the outer edge ofthe same,

The. operation of the tool shown in Fig. 1 is briefly as follows: lith the parts in the position shown, motive fiuid is passing from the central l chamber of the valve through ports 36a in face 162) to ports Y2,1 and thence by passages 21a, 2lb, and v210 to the forward end of the piston chamber to drive piston 9 rearwardly, `the rear end of the pistonv cham-V ber being open to exhaust through port 8, and-`ports 20 'of thel valve chest being sealed by'face 16a of the valve. As the piston'inoves rearwardly, it closes exhaust 8 trapping a quantityof lair in thet piston chamber and compressing the same. Theair thus compressed-acts through ports 20 against face 36a, ofmthe valve, vThen the piston 9 lhas moved far enouglrto uncover port 8 and open the forward end of the piston chamber to atmosphere, there is a suddendrop in pressure in passages 210, 2lb, 210i and port-s 21 with the result .that the valve moves 4quickly to its rearward position closingI ports 21. The motive fluid from the central valve chamber new passes throughz face 36a to ports 2O driving the pist-on forwardly. As central exhaust 8 is closed .by piston 9, pressure begins to build up in passages21c, 2lb, and 21a and this pressure 'becomes effective to shiftfthe valve back to its original position when piston 9 uncovers exhaust 8, as shown in Fig. 1.

rlhe restriction in the movement of motive Huid from the central valve chamber to the end ports, aceo-mplished in any one of the ways indicated in Figs. 2, 5, and .6, is of importance inthe shiftingmovement of the valve since it prevents the passing of motive fluid in sufficient quantity to the exhaust side of the valve to interfere with the movement of the same. The effective pressure for throwing .the valve is increased by enlarging ports 2O and 21 where they open into the valve chamber by flaring or counter-sinking the same as indicated at 20x and 21m, Figs. 1 and 2.y lf desired, the throwing pressuremay also be increased by providing one or more restricted. ports through each of the end faces ofthe valve as indicated at 160 in Fig. 2. Similar ports for the same purpose maybe provided in the modifications of the invention as indicated at 260 and 860 in Figs. 5 and 6 respectively. Alternatively or additionally the outer end faces of the valves may be reduced or cut away toward their periphery, indicatedat 16d (Fig. 2), to .provide annular relief areas supplied from the central chamber ofthe valve. This arrangement minimizes the intensity of the pressure necessary to start the valve od its seat.

To maintain the control parts of the drill so that the communicating passages willialways be in register, long dowel pins 23 are provided which extend through suitable bores therefor in ring 17, lid 15, andease 14 and have their ends received in suitable sockets in cylinder and back head 19 respectively.

While the invention. has Ybeen herein disclosed in what is now considered to be a preferred form with modifications, it is to be understood that the invention is not limited to the specific details thereof but covers all changes, modifications, and adaptations within the scope ofthe appended claims.

I vclaim as my invention:

1. In a. fluid pressure motor, a cylinder having an exhaust port intermediatel its length a piston reciproeable in said cylinder and controlling'said port, a valve chest in line with the piston Achamber and serving as a closure for the latter, said chest vproviding an annular valve chamber and having ports at the ends thereof Vleading to opposite ends ofthe piston chamber,an annular'valve having end faces for controlling the ports in said valve chest and an intermediate reser-v Voir for pressure fluid, and lmeans comprising ports in the end faces of said rvalve restricting the movement of pressure fluid'from said reservoir to each groupfof end portsin said valve chamber to an'amount less than the capacity of each group.

2.. In a fluid pressure motor, a cylinder having anexhaust port intermediate y its length, a piston reciprocable in said cylinder leo and controlling said port, a valve chest in line with the piston chamber and serving as a closure for the latter, said chest providing an annular valve chamber and having ports at the ends thereof leading to opposite ends of the piston chamber, an annular valve having end faces for controlling the ports in said valve chest and an intermediate reservoir for pressure iuid, and means comprising ports in the end faces of said valve restricting the movement of pressure fluid from said reservoir to each group of end ports in said valve chamber to an amount less than the capacity of each group, said valve ports being out of register with said chest ports in all positions of said valve.

3. In a fluid pressure motor, a cylinder having an exhaust port intermediate its length, a piston reciprocable in said cylinder and controlling said port, a valve chest in line With the piston chamber and serving as a closure for said cylinder, said chest providing an annular valve chamber and ports at the opposite ends thereof leading to opposite ends of the piston chamber, an annular valve providing end faces for controlling the ports in said valve chest, and an intermediate reservoir for pressure fluid, said valve having ports out of register With said chest ports but arranged to permit the passing of pressure fluid from said reservoir alternately to eaoh end group of chest ports in less volume than the capacity of each end group, said valve being moved by air compressed by the piston at the end of each stroke and having at least one restricted port through each end face to permit a limited amount of pressure fluid from said reservoir to reach the closed ports and augment the air compressed by the piston.

fl. In a fluid pressure motor having a cylinder and a piston reeiprocable therein, a valve chest providing an annular valve chamber and ports at the opposite ends thereof leading to opposite ends of the piston chamber, and an annular valve having end faces for controlling said ports and providing an intermediate reservoir for pressure fluid, said valve slidably engaging both the inner and outer Walls of said chest and having means for passing pressure luid from said reservoir to said ports in alternation, said last mentioned means being of lower capacity than said-ports.

Signed by me at Detroit, in the county of Wayne, and State of Michigan, this 28th day of January, 1929.

GUSTAVE M. NELL.

Images