US1716049A - Air tool - Google Patents

Description

June 4, 1929. w, GREVE 1,716,049

AIR TOOL Original Filed Jan. 3. 1921 4 Sheets-Sheet l June 4, 1929. L, w, GREVE 1,716,049

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AIR TOOL OriginalFiled Jan. 5. 192] 4 Sheets-Sheet Z5 l vmfi ma w Jim; w y/M,

L. W, GREVE Junei4, 1929.

I 4 Sheets-Sheet 4 AIR TOOL Original Filed Jan. 3. 1921 l llll Patented June 4, 1929.

UNITED SATS LOUIS W. GREVE, OF CLEVELAND, OHIO, ASSIGNOR TO THE CLEVELAND PN RUMATIO v were TOOL COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

AIR TOOL.

Application filed January 3, 1921, Serial No. 434,500; Renewed May 10, 1928.

This invention relates to rotary air tools such as drills of the type wherein power is transmitted to a rotary spindle through reciprocating pistons and a crankshaft geared or otherwise connected to the spindle, and

'in certain respects the present invention is arrangement of valves for supplying to and exhausting motive fluid from the two sets of cylinders Which are arranged in V-formation, and to the means for actuating the valves. Additionally the invention relates to the construction of the crank-shaft including a novel arrangement of eccentric for actuating the valves.

In general it may be stated that the object of the invention is to' increase the efiiciency'of, or power derived from pneumatic tools such as drills, and especially to provide for quick passage of air from the supply to the cylinders.

Briefly stated, the above results are accomplished very successfully by arranging the valve which controls the air for each set of cylinders centrally or between the cylinders, thus providing a substantial equalization and also simplification of the air passageways. Preferably reciprocating valves are employed, and these are actuated through the medium of an eccentric arranged on the crank-shaft between the crankpins, the eccentric being formed by a peculiar and advantageous offsetting of a part of the crank-shaft with reference to the bearing portions and crank pins thereof, the eccentric being preferably counterbalanced near one end of the crankshaft so as to provide for smooth operation.

The invention may be further briefly summarized as consisting in certain novel details of construction, and combinations and arrangements of parts which will be described in the specification and set forth in the appended claims. v

In the accompanying sheets of drawings wherein I have shown an embodiment of my invention which operates with high efficiency, Fig. 1 is a longitudinal sectional View; Fig. 2 is a plan view with a part of the casing removed; Fig. 3 is .a transverse sectional view, the section being taken through one of the cylinders and cooperating piston of one set, and through the centrally disposedvalve correspondingto the other set of cylinders; Fig. 1 is a plan view of the crankshaft removed from the tool; and Fig. 5 is an end view of the same.

Referring now to the drawings, the easing or housing of the tool includes a main casting 10 which forms the principal part ofthe housing, the housing being completed by a removable'cap 11 which is secured in place by bolts 12 and forms part of the crank case, and by a removable endplate 13 which encloses the gearing connecting the rotary spindle to the crank-shaft and constitutes a bearing for the spindle. The housing is provided with a pair of oppositely disposed sockets, 14: and 15 (see Fig. 1) adapted to receive handles, one of which will, as is customary, constitute the air supply or inlet and will be provided with .a

throttle valve. 1

The tool here shown is provided with two sets of cylinders 16, arranged in 'V-formation, there being in this case fourcylinders in all, or two in each set. The cylinders are in this instance arranged ninety, degrees apart. Furthermore, the cylinders of one pair are not directly opposite, buta're slightcisely like the rods-shown in my prior application already referred to, and are connected to the crank-shaft in the manner explained in my prior application; that is to say, each connecting rod is formed in one piece with a continuous ring 21 which surrounds the crank pin of the crank-shaft, there being between each connecting rod ring and the crank pin of the crank-shaft, a

series of balls 21 whose raceways or raceway grooves are formed direct in the ring 21 and direct in the crank-shaft. In other words, separate raceway rings are avoided.

The crank-shaft to which power is transmitted by the connecting rods is shown at 22, this crank-shaft having several of the features of construction which are believed to be novel with me, these features rendering cylinders and midway between them. The

two valve cylinders make the same angle with respect to each other as do the two sets of main cylinders, namely, ninety degrees, and they are slightly staggered in conformityavith the staggering of the two sets of main or power cylinders.

Each valve cylinder has tightly fitted into it a ported bushing 24, (see Fig. 3), and each valve is in the form of a piston 25 which slides back and forth in the bushing, motion being transmitted from the crankshaft to the two valves 25 by connecting rods 26 having integral one-piece rings 27 engaging an eccentric of the crank-shaft to be presently referred to.

Air is supplied through the handle which is connected to the socket to an air receiving chamber 28 of the housing'(see Figs. 1 and 3) and each valve controls the delivery of air from this chamber to the two working cylinders associated with it. WVhile the details of the valve and the precise arrange ment of the ports connecting each valve with the two associated working cylinders are not important to the present invention, in this instance air is delivered to the valve chamber of each valve by a port 29, and is delivered alternately to the two cylinders associated with the valve through ports 30 and 31. The exhaust takes place at the outer end 32 of the valve bushing 24, this end being covered by a perforated cap 33.

' With the valve in the position shown in Fig. 3, air is being delivered from the port 29 by way of the valve to the port 31 which is connected to the workingcylinder behind the valve or beyond the observer. At the same time, air is exhausted from the port 30 direct into the outer end 32 of the valve the port 29 through the valve chamber to the port 30, the port 31 will be brought into communication with the chamber 32 of the valve and the exhaust from this port will take place through the port 32 into the piston valve which is hollow,

to the outer end 32 of the bush-ing 24.

The point to be noted in passing is that the valve is located midway between the two cylinders which it controls, and while the passageways connecting the valve cham her to the two working cylinders may not be precisely the same in length, they are substantially so, but at any rate the necessity for long ports or passageways is with the present arrangement entirely eliminated, and an increase of power decrease in air friction.

Taking up now the crank-shaft 22, it will be observed that this crank-shaft has ing portions 34 and 35 which are supported in ball and ring bearings 36 and 37, which in turn are supported partly by-the housing 10, and by crank case or cap 11. :One end of the crank-shaft, just beyond the bearing 37 has an integral pinion 38 which drives a gear 39 which is fixed to a rotary tool spindle 40, whose axis is at the center of the housing, the axis being in the V between the two sets of cylinders. This tool spindle which provided with the usual tapered socket for a drill or other tool, has a bearing in a bushing 41, mounted in an outstanding boss of the end plate 13. The inner end of the spindle is reduced and has a bearing in the socketed end of a feed screw 42.

Additionally the, crank-shaft 22 has crank arms 43 extending from the bearing portions 34 and 35, and two crank pins 44 which are diametrically opposite, or one hundred and eighty degrees apart. Each crank pin 44 accommodates the rings of two connecting rods which extend to the pistons of two cylinders, one in one set and one in the opposite set, these crank pins each having two ball race grooves 45 precisely" as disclosed in my prior application.

Furthermore, this crank-shaft is provided between the crank pins 44, and about centrally of the shaft lengthwise considered, with an eccentric 46 for actuating the reciprocating. piston valves, this eccentric being engaged by the rings 27 of the two rods 26 which are connected to the valves.

The use of a single eccentric for actuating the two valves controlling theair to both sets of cylinders is rendered possible by reason of the peculiar location of the center of the eccentric 46 with reference to the longitudinal axis of the crank-shaft. It will be observed particularly by reference to Fig.5 that thecenter of the eccentric is offset lateris obtained by the ally with reference to the center line or axis of the crank-shaft, (i. e. the bearing portions thereof) and is also offset angularly or circumferentially a few degrees, the crank arms 47 which connect the eccentric to the crank pins 44 being offset or twisted out of the plane of the crank arms 43. The location of the center of the eccentric with reference to the axis of the crank-shaftand'the disposition of the crank arms 47 relative to the crank arms 43 are readily apparent from Fig. 5.

Inasmuch as the crank-shaft has near the center an offset mass formed by the eccentric and to an extent by the offset crank arms 47, it becomes necessary in order to provide smooth operation and to minimize vibration at high speed, to counterbalance this offset mass, and this I accomplish by the integral counterbalancing weight 48, located adj acent the bearing portion 35 and pinion 38 formed at one end of the crank-shaft.

The design of this crank-shaft 22 with its centrally located eccentric to actuate the valves located centrally with respect to the cylinders of the two sets presented still another problem in the way of minimizing the number of parts and permitting the use of integral or one-piece eccentric and connecting rod rings. In this connection it might be stated that in my prior application it is an important feature of the construction that the connecting rods have integral continuous or onepiece rings which surround the crank pins and are separated therefrom by ball bearings whose race-ways are formed direct in the crank pin and in the connecting rod rings respectively, this being rendered possible only by a construction of the crankshaft such that the rings could be threaded or slipped along the crank-shaft from one end thereof.

This same idea is carried into the present construction and applied to the eccentric straps or rings 27, as well as to the connecting rod rings. That this might be accomplished it became necessary that the eccentric 46 and the annular shoulder 49 (that I prefer to provide at one side of the eccentric) be no greater in diameter than the inside bore of the connecting rod rings. Additionally to accomplish this, still another feature was necessary, that being the provision at the junction of the arm 47 and the end of the eccentric opposite the shoulder 49 of a straight section 50 in line with the axis or center line of the eccentric, and of substantially the width of the eccentric straps or rings 27. To explain this, the connecting rod and eccentric or valve rod rings which engage respectively the two crank pins 44 and the eccentric 46, are all slipped or threaded along the crank-shaft from the end having the bearing portions 34, i. e. the left hand end of the crank-shaft, as the same is Viewed in Fig. 4. The rings of the two connecting rods which engage the crank pins remote from the bearing portion 34 are first slipped along the crank-shaft. Then the rings or straps which engage the eccentric 46 are applied in a similar manner, and finally the rings of the connecting rods which engage the crank pin adjacent the bearing portion 34 are put into place. However, while the connecting rod rings are separated from the crank pins by the sets of ball bearings, the rings or straps which engage the eccentric preferably have a plain fit on the latter, and inasmuch as loose play. between the rings 27 and the eccentric must be reduced to a very small and almost negligible amount, it is essential that in threading the eccentric rings over the crank-shaft that the bore of these rings be brought into direct alignment with the bearing formed by the eccentric 46 before they are slipped onto the eccentric. This is rendered possible by the provision of the straight portion 50 in alignment with the eccentric at the junction of the arm 47 and the end of the eccentric onto which the rings are slipped.

A pneumatic tool constructed as explained above with the supply to and exhaust of air from the two sets of cylinders controlled by valves arranged as described centrally with respect to the cylinders in the two sets, with the two valves actuated by an eccentric located between the crank pins, with the rings which surround the crank pins and eccentric each formed in one piece integral. with the connecting rods and with separate race-way rings eliminated, is not only strong and durable, but by actual. test is found to have higher efliciency than similar tools as heretofore constructed, and this result in the way of increased power I attribute partly to the minimizing of parts and reduction of mechanical friction, but chiefly to the location of the valves with the resulting re duction in the loss of air friction in the passage of the air to the working cylinders, and to the efficient manner in which the valves are actuated by the single eccentric located between the crank pins and offset as described with reference to the axis of the crankshaft.

Having described my invention, I claim:

1. In an air tool, a housing having a plurality of sets of cylinders arranged in V-formation, with opposite cylinders staggered, pistons in the cylinders, valves between the cylinders, a crankshaft having offset crank pin portions and an. eccentric portion between the crank pin portions, a pair of connecting rods having integral rings arranged side by side on each crank pin portion and connected centrally with pistons in opposite cylinders, valve rods having integral rings arranged side by side on the eccentric portion and connected to the valves, the rings of all said connecting rods and valve rods being adapted to be slipped over the crank-shaft endwise thereof.

2. In an air tool, a housing having a plurality of sets of cylinders arranged in V-forn1ation, with opposite cylinders staggered, pistons in the cylinder, valve cylinders between adjacent cylinders of each set, opposite valve cylinders being staggered,

valve pistons in the valve cylinders, a crankshaft having offset crank pin portions and an eccentric portion between the crank pin portions, a'pair of connecting rods having integral rings arranged side by side on each crank pin portion and connected centrally with pistons in opposite cylinders,

-valve rods having integral rings arranged side by side on the eccentric portion and connected to the valve pistons, the rings of all of said connecting rods and valve rods being adapted to he slipped over the crankshaft endwise thereof to their respective positions.

3. In an air tool, a housing having a plurality of sets of cylinders arranged in V-formation, with opposite cylinders staggored, pistons in the cylinders, Valves between the cylinders, a crank-shaft having offset crank pin portions and an eccentric portion, a pair of connecting rods'having integral rings arranged side by side on each crank pin. portion and connected centrally with pistons in opposite cylinders, valve rods having integral rings arranged side by side on the eccentric portion and connected to the Valves, the rings of'all said connecting rods and valve rods being adapted to be slipped over the crank-shaft endwise there of, ball bearing races formed partly in the crank pin portions and partly in the rings, and ball bearings arranged in the races. v

In testimony whereof, I hereunto afiiX my signature.

LOUIS W. GREVE.

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