US1914091A - Fluid motor - Google Patents

Description

June 13, 1933. W T. HAM|LTON ET AL 1,914,091

FLUID MOTOR Filed Sept. 26, 1930 All. n ISMZS 11 24 l INVENTORX mwa-JM ATTORNEYS Patented June 13, 1933 UNITED ys'lATE-s WALTER T. HAMILTON AND GRO'VER F. ILGEN, 0F SPRINGFIELD, OHIO, ASSIGANBS T0 THE AIRETOOL MANUFACTURING COMPANY, F SPRINGFIELD, OHIOLA CORPOBA- 'rIoN 0F omo FLUID xo'ron Application led September 26, 1930. SeriaTNo. 4845625.

vto the rotor shaft, the Vpreferable fluid ybe ing compressed air.

The object is' to provide an improvedv f means for exhausting the motive fluid from the cylinders.

In the accompanying drawing: v Fig. 1 is al view partly in elevation and partly in longitudinal section of a fluid motor constructed in accordance with our improved design.

Figs. 2, 3, 4, 5, 6 and 7 are transverse sections on the lines 2 2, 3 3, 4-'-4,` 5 5., 6 6 and 7 7, respectively, of `F ig.,1, the-v1ew`1n Fig. 5 showing the parts in a different working position.

Referring to the drawing, 1 lrepresents a` cylindrical, hollow shell having a reduced'" diameter hollow hub portion 2 extending concentrically from one end to forni a support for the forward bearing for vthe rotor shaft, there being a bearing bushing 3 inserted in the hub portion 2. .The opposite end 4 of the shell 1 isv open and is interiorly threaded as at 5 for a short distance in the bore 6. Various parts incident to the construction are placedin the bore 6 4and are o therein concentrically held in alignment vwith the forward bearing 3, these parts being a hardened steel wear plate 7 at the forward end of the bore l6, a cylinder 8, a flat, hubbed disk 9 intowhich a rear bearing bushing 10 is pressed, and a threaded hose connection 11 which serves to bind the parts tightly in the shell l.,

The rotor body is indicated at 12 and consists of a cylindrical body portion having shaft extensions at each end,`one being a comparatively long reduced-diameterfextenysion 13, and the other a shorter extension 14, the longer extension 13 projecting ybe-l yond the bearing 'bushing 3 and terminating in a threaded end 13 to which tools of various sorts are to be attached, while the shorter end 14 is journaled in the bearing The rotor 12 revolvesivithin, but. is not in actual contact with the cylinder 8. This cylinderv 8 is constructed along the usual lines, the majorj ortionof the exterior surface being cylin rical and-adapted to closely ft the bore 6 of the shell 1, while the bore 15 of the cylinder is oblong in charac- `ter as seen best 1n Fig. 3. By 'reason of the yconcentric disposal of the parts described the axis of rotation of the rotor coincides with the longitudinal center line of the cylinder 8, and the oblong bore 15 of the cyllnder 1s therefore equally divided on each side of the rotor 'to formchambers.

The rotor body -portion 12 is provided y with a pluralityof equally spaced slots 16 in which blades of the lsame length as the body 12 are ftted,land are adapted to slide freely in a lradial direction and on rapid 'rotation of the rotor these blades tend to follow the contour of the oblong bore 15 of Ithe cylinder. Referring to Fig. 5, in which the revolving parts are shown in a different `working positionas compared to the other views, it will be seen that the opposite blades 17, 17 arey in contact with the bore 15 of the cylinder at diametrically opposite points, and that the rotor hasbeen suiciently rotated to show small spaces 18, 18.

yWhen a fluid under pressure is admitted to these small spaces the rotor is rotated in the direction `of the arrow, the pressure being maintained behind the blades for a suitable length vof time, usually terminating when the 'blades reach the point indicatedfby the character 19. The momentum of the rotor then brings other blades20, 20 in position to'receive an impulse, resulting 'in a very rapid `rotation of the rotor. r

vInasvmuch as each vblade must move vinwardly and outwardly twice in each revo-v lution" of 'the rotor, and as the rotor revolves at very high speeds, anobjectionable vibra-- tion of the motor develops during operation. The vibration may be v'very materially reduced by the employment of blades formed of materials such as aluminum, hard rubber, hard fiber, or bakelite. However, while blades of such light materials as were just 4mentioned are as'certainly. affected by centrifugal forces as av'e metallic blades `of lite the reater friction of the preferred bakelade is such that the outward movements may be comparatively sluggish with the result' that, unless provision is made to preventJ it, the-contour of the oblong bore 1 5 is not closely followed, resulting in an ineflicient operation due to leakage of fluid during the impulse period. Simple and I effective means are described later in the as the time of admission may be obtained in` a variety of ways, the method We prefer to follow being as herewith described, it

y being stated at this time that although the drawing appears to show opposing flows of fluid whereby inefficient operation would result, yet by reason of the high speed of the rotonand the lag in the movements of the lcompressed fluid, impulse and exhaust periods, occu'r at the desired times, this being lespecially true as regards the aid given in causing the blades to follow the contour of the oblong cylinder bore.

Atthe rearward side of each blade, referring to the directionof rotation, through the body portion of the` rotor a series of passages 2l are provided, these being -in a line parallel to the axis of rotation of the rotor. Each of these passages leads into an individual conduit 22 which is drilled in an eccentric, longitudinal location `through the shaft extensionl4 and also through the body portion 12 to a pointjust in advance of the foremost opening 21,- F ig. 1.

The conduits- 22 are'equallyy spaced from each other and are parallel to the longitudinal axis of the rotor, and are plugged at the end of the shaft extension 14. In the shaft extension 14 a series of radial port openings 23 are drilled one for each conduit4 22. lIn the stationary hub 9 of the disk 9 and through the stationary bearing bushing 10 a pair of diametrically opposed elongated orifices 24 are. drilled which are adapted to register with the port openings 23. Air or other fluid under pressure is admitted to the chamber 25 formed in the interior of the hose connection 11 and passes through a conically formed strainer into each of the port openings 24:, and then into the nearest radial port opening23 inthe shaft extensionl 14 agfd then ipto the passage openings 22 to thel outlet ports 2l behind each blade. l

Inasmuch. as two ports 24 are employed and as these are diametrically opposite, itfollows that in the present case where four blades vare used in the rotor, the fluid may flow only to two diametrically opposed series of outlet ports 21 and thus cause an impulse to occur behind two opposite blades,

in this instance, the blades E17 The time of admission and the cut-offI of the fluid to ports and passages described is goverlfed by the size and location of the ports 24 and23. In Fig. 5 the position ,isl shown at the time when the fluid is about to be admitted, while in Figs. 2 and 3, the position at cutoff is shown. A y

As the rotor continues in its rotation a preliminary exhaust port vis opened, this event occurring immediately after the time of cut-off, and shortly thereafter a secondary exhaust port is uncovered;t the object for the plurality of exhaust ports being for the purpose of providing ample .exhaust port area' whereby the speed and power is increased by the elimination of possible back pressure. The preliminary exhaust is afforded by openings 26 cut in the periphery of the Wear plate 7 as seen in Fig. 4. This plate closes` the` forward end of the cylinder 8 except at the notches mentioned, and there are provided exhaust a ertures27 in the forward wall 27 of the s ell 1.

The secondary exhaust occurs when a blade haspassed over a series of openings 28,l Figs. 1 and 3, in the cylinder 8, this series being located at a preferred oint and in a path parallel to the axis of) rotation and on diametrically opposite sides. These openings 28 communicate with a large space 28' between the cylinder 8 and the shell l obtained by removing a portion of the exterior surface ofthe cylinder 8 as bestseen.

in Figs. 3 and 5 and open directly atthe forward end into the exhaust aperture 27' c inthe shell l. In Fig. 3 the blades 20 are approaching the edges 26 where the start of the preliminary exhaust is made, while in Fig. 5 the blades 20 have passed these edges and exhausting of the pressure behind these blades is taking place. It will be noticed in Figs. 3 or 5 that the area of the aperture 27 for the passage of exhaust fluid is approximately equally divided as regards the quantity of fluid that ma escape through the preliminary or secon ary exhausts. In 0rdinary conditions a satisfactory speed and power may be obtained by the use of either of the methods vof exhausting arrangements,

but by the combined arrangement the speed has been increased perhaps thirty per cent, an idle speed approaching twelve thousand revolutions per minute being attained.

At 30 and 30 are shown dowel pins, this or somey other suitable arrangement being necessary to provide that the proper alignment of the stationary parts be maintained while at 31 a small pin is employed to align the bearing bushing 10 and the hub 9', since the supply vports 23 pass through these parts,

the pin 31 projecting into a longitudinal slot cut in the exterior surface of the bushing 10.

Referring to Fig. l, it will be seen that the fluid at ressure in the supply ports 2,4; may travel Iby leakage in both directions along the shaft extension 14, it being impossible to secure a fluid tight joint as the bush- 5 ing 10 also serves as a rear main bearing. This leakage accumulates and tends to exert a pressure on the end of the shaft14 and on that portion of the rotor body indicated at 12', manifesting itself to the extent that o ordinarily the motor would not operate due to the excessive end thrust (to the right) of the rotor. Operation heretofore'has been secured by supplying a ball thrust bearing at the forward end of the rotor, but we have 5 developed an arrangement whereby we not only eliminate the expensive ball thrust bearing, but also eliminate the thrust itself, by means which will now be described.

In Fig. 1, in the bearing bushing 10, a o small radial groove 32 is employed to relieve or vent the pressure occurring at the end of the shaft extension 14, this groove 32 communicating with a longitudinal assage 33 in the bushing, Figs. 2 and 5, w ich 5 in turn communicates with an annular recess 34 in the forward side of the disk 9. Part of the pressure which would accumulate on the end 12 of the rotor also leaks into the recess 34, and since this recess is in communication with the exhaust passageways 28 through the medium of the radial grooves 35 in the forward side of the disk 9, the whole amount of the pressure which would tend to cause end thrust is vented to 5 atmosphere and end thrust is thereby obviated.

In motors of this type it has been the practice to admit fluid under pressure bcneath the blades for the purpose of preventing chattering of the blades both upon the outward and inward movement thereof. In prior constructions the fluid has been admitted to each of the blade slots directly from the passage which supplies the motive 5 fluid for thc working stroke of that blade through a comparatively wide port, as a result of which, when that supply passage passes the exhaust port, the fluid will be rapidly exhausted from beneath the blade 0 and the pressure thereon relieved, allowing the blade to chatter for a portion of its inward movement. To overcome this defect, we have provided anjarrangement whereby the'fluid can exhaust but slowly from the 5 blade slot during the time the passage which ply the fluid to the blade slot at a point in advance of thev beginning fof its working stroke. To ythat end, .instead of supplying the fluid to any one. blade'slot from the passage which furnishes motive fluid for that particular blade, we have arranged to supf 'ply this motive fluid from the' fluid passage immediately in advance of the blade. For example, referring to Fig. 3, the inlet ports have just begun to supply lmotive fluid to the passages 21 to drive the blades 17 which are just starting on their working stroke and it will be noticed that reduced orifices 36 lead from the conduits 22, to the bottom of the slots.beneath the blades 20 which are just about to begin to move into the slots. Pressure will begin tobuild up beneath the blades 20 until by the time they have reached the position -of the blades17 in this figure, a maximum pressure will exist. As soon as the blades 17 have passed the exhaust ports however a reduction in pressure is had in those supply passages which have supplied the slots of the blades 20, but, due to the fact that the fluid beneath the blades can escape but slowly through the reduced orifices by reason of leakage by the blades, a fluid cushion is maintained beneath the blades 20y not only through their entire working stroke but also during the entire inward movement in the slots.

A conicalstrainer 37 formed of perforated sheet metal is employed to prevent ingress of forei matter into the motor proper. This strainer may be a one-piece rolled member or pressed and formed from the flat; in either event, the larger end is forced into an annular recess 37 in the rear of the disk 9, while the smaller end is forced over the hub 9 and crimped into a recess 38 in the outer surface thereof.

Lubrication of the rotative parts is accomplished by feeding" a small amount of lubricant into the motor from a container (not shown), the lubricantl being carried by the fluid medium. Heretofore, the forward main bearing has received but scanty lubricant due to its position and the fact that the lubricant was carried in the fluid stream, resulting in rapid wear or shut-downs to lubricate this bearing. By simple arrangements we are enabled to afford ample lubrication for this bearing, one of the means being a plurality of openings leading from the exterior of the extended hub 2, a single opening 39 on each side of the hub being shown in Fig. 7. These holes are located in the path of the escaping motive fluid which tends to expand immediately on leaving the apertures 26, and aportion of the fluid stream therefore flows forwardly along the hub 2, with the result that a minute ricant then finds its way into the oil rooves 41 in the interior of the bushing 3 t rough openings 42 leading from the circumferential groove 40. i

Another method of lubricating the rear 4end of the forward main bearing is by the `radial grooves 44 which are provided in the rearward side of the wear plate 7, Figs. 4c and 7. These grooves are small half-round grooves leading from those portions of the wear plate which are exposed to the pressure of the fluid, as best seen in Fig. 3, so that during each impulse, a small portion of lubricant is deposited therein and forced by the pressure into an annular space 4:5 directly at the rear of the bushing 3. The rotation of the shaft coupled with the effects of the fluid pressure readily cause the oil to work its way into the bearing bushing 3.

Having thus described our invention, we claim:

1. In a fluid motor, a casing, a cylinder in said casing, a rotor in said cylinder, an elongated exhaust port in an end of said casing leading directly from the interior of said cylinder in an axial direction, an exhaust passage between said cylinder and casing communicating with said port, said exhaust passage extending throughout the major portion of the length of said cylinder, said cylinder having at least one exhaust opening leading to"'"said"passage.

2. In a luid motor for a cutting tool, a cylinder, a rotor in said cylinder, an exhaust port at the tool end of the cylinder leading directly from the interior thereof in an axial direction, a longitudinal exhaust passage in the wall of the cylinder leading to said exl' haust port and said cylinder having at least one exhaust opening leading to said passage, said exhaust passage extending throughout the major portion of the length of the cylinder.

1n testimony whereof, we have hereunto set our hands this 19th day of September,

WALTER T. HAMILTON. GROVER F. LGEN.

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