US2989005A - Fluid apparatus - Google Patents

Description

June 20, 1961 B. G. GARDINEER, JR 2,989,005

FLUID APPARATUS Filed May 28, 1958 FIG.3

INVENTOR BAYARD G.GARDINEER JR.

Y fM/a/M AGENT United States Patent Ofifice 2,989,005 FLUID APPARATUS Bayard G. Gardineer, Jr., Peekskill, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed May 28, 1958, Ser. No. 738,551

2 Claims. ('Cl. 103-161) This invention relates generally to fluid operated apparatus and more specifically to improvements in the structure of fluid pumps and motors wherein the pistons are arranged in a radial array.

An object of the present invention is to provide an improved structure for radial type fluid pumps and motors so as to achieve a minimum moment of inertia in the rotating parts.

A further object is to provide an improved configuration of parts in the aforesaid apparatus so as to improve the life of the apparatus through a reduction in wear. Yet another object to is provide in the aforesaid appa'ratus a fewer number of parts, each of which has a simple easily-fabricated shape so as to reduce the cost of the apparatus.

A final and specific object of the invention is to provide an improved piston and reaction ring structure for a radial piston type fluid pump or motor for the achievement of the" aforementioned objects.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

FIG. 1 is a partial sectional view of the invention taken along the axis of rotation of the device.

FIG. 2 is a transverse sectional view through the rotor, taken along the line 2-2 of FIG. 1.

FIG. 3 is a geometric diagram of the piston travel.

FIG, 4 is a development of the reaction ring showing the wear pattern.

Prior art fluid motors or pumps of the radial piston type characteristically employ pistons radially disposed in a rotor having cylinder bores which receive the pistons and provide expansible fluid chambers which are selectively connected to high and low pressure chambers by rotation of the rotor, whereby the radial movement of the pistons through coaction of the pistons witha reaction ring, which is eccentrically disposed with respect to the axis of rotation of the rotor, either eifects apumping of the fluid, if external rotational power is applied to the rotor, or an auto-rotation of the rotor, if external power in the form of a diiferential fluid pressure is applied thereto. Whereas hydraulic devices have in the past found their'chief utility in slow speed large force applications, their use in high speed applications with rapid accelerations and reversals has required that the rotating parts of pumps and motors, particularly thelatter, be designed with a moment of inertia to permit of high acceleration as well as be designed to have optimum wear characteristics, wear being accentuated by the high operating speeds.

The instant invention seeks to overcome the limitations of the prior art devices by providing an improved piston and reaction ring structure whereby the moment of inertia of the rotating parts is considerably reduced, and the useful life of the parts is prolonged through reduction in wear. To this end, the pistons are formed at their outer end with a planar cut oblique to the axis thereof so as to form a point contact with the cylindrical inner surface of the reaction ring, the point of contact being eccentric with respect to the axis of the piston so as to provide a sort of castoring action as the pistons move with re- Patented June 20, 1961 spect to the reaction ring, so as to distribute the wear over a larger area of the reaction ring.

The preferred construction of a fluid pump or motor embodying the instant invention is shown in the drawings, the description of which will be confined to the use of the apparatus as a fluid motor for lucidity only. With reference to FIG. 1, fluid from an external source of high pressure is connected to either the conduit 10 or conduit 11, depending on the desired direction of rotation, which conduits connect respectively with the chambers 12a and 125 (FIG. 2) formed internally of the tubular spindle 12 by a longitudinal barrier 120 which isolates the two chambers from one another. Communicating with the chambers 12a and 12b and ports 12a, 122, 12 and 12g (not shown) which are so spaced both axially and radially that the fluid in the chambers 12a and 12b is successively connected to the cylindrical bores 13a to 13 inclusive, which bores are radially disposed in rotor '13 which rotates on the tubular spindle 12. Slideably mounted in the cylindrical bores 13a to 13 in fluid confining relationship therewith are the pistons 14 through 21, and 24 through 31 (some of which are hidden in the drawings). Each of these pistons has a substantially cylindrical configuration except for the outer surface thereof which, although planar, is obliquely disposed with respect to the axis of piston so as to provide a single point or small area exemplified by 14a on the piston 14, which point is eccentrically located with respect to the axis of the piston and extends axially beyond any other portion of the piston. Although any surface configuration of the end of the pistons that satisfies the requirement that the point of contact of the piston be oh. the axis of the piston is satisfactory, it has been found that the most practical shape is the planar shape hereinabove described wherein the plane is inclined at an angle of 5 /2 degrees from the perpendicular to the axis where the diameter of the pistons is inches, the diameter of the reaction ring 2 inches and the eccentricity between the reaction ring and the rotor center is .140 inch. The chief advantage of the planar shape over similar functioning configurations is its ease of fabrication and consequent economy. Each of these points on the respective pistons co-acts with a cylindrical inner race 32a of an anti-friction bearing 32, which bearing is eccentrically disposed with respect to the axis of rotation of rotor 13, the orientation of the eccentricity being so disposed with respect to the chambers 12a and 12b and the ports 12d, 12e, 121 and 12g that the pistons will be exposed to the high pressure conduit in their are of travel wherein the clearance between the rotor 13 and the inner race 32a is increasing and to the low pressure conduit when the clearance is decreasing.

The rotor 13 is provided with a plurality of radial slots 13K which engage with a complementarily shaped multi-forked clevis 33 for driving connection therewith. The clevis '33 includes an integral shaft 33a which is journalled in bearings 34a and 34b and suitably sealed against fluid leakage by seals 35a and 35b. A suitable casing 40 mounts and locates the parts in their proper orientation and prevents the loss of fluid from the appa-ratus.

The foregoing description has been somewhat abridged, and the drawings have been simplified for purposes of simplicity. Usually fluid motors of this type employ an odd number of cylinders in any one circular array as well as more than the two circular arrays shown. Such a showing, here, would produce asymmetrical sections and lengthy exposition which is unnecessary to an understanding of the invention.

Referring now to FIG. 2 it will be seen that during a clockwise rotation of rotor 13 through the piston 14 will move from a radial innermost position to a radial outermost position as represented by the pusrtlon of the piston 18. As the rotor 13 rotates the piston 14 and all other pistons in the motor bear on the inner race 32a of the anti-friction bearing whichrotates therewith. The eccentric relationship of the rotor 13 and the inner race 32a, however, causes a secondary relative movement of the pistons relative to the inner race, which relative movement in prior art devices has either occasioned excessive wear or required elaborate auxiliary anti-friction devices to compensate therefor.

As piston 14 is moving radially outward so also is the adjacent piston 15 moving radially outward. Whereas the arcuate distance separating the point of contact of piston 14 with the reaction ring 32:: from the point of contact of piston 15 with the reaction ring 32a is a minimum at approximately the position shown in FIG. 2, this arcuate distance increases to a maximum when the pistons 14 and 15 would occupy the position occupied by the pistons 18 and 19 respectively in FIG. 2. This increase in the arcuate distance requires movement of the pistons 14 and 15 relative to the inner race 32a.

Reference to FIG. 3 will clarify the above relative movement. The are DB in this figure represents the arcuate distance separating the points of contact of two adjacent pistons in any circular array when these pistons occupy their innermost radial positions. The are AB represents the arcuate distance separating the points of contact of these same two adjacent pistons when they occupy their outermost radial positions. The arcs AB and DE obviously have the same radius as they represent a segment of the inner race 32a, and the radial distance AD represents the amount of eccentricity between the axis of rotor 13 and the axis of the inner race 32a. Thus it will be seen that the arcuate separation of two adjacent pistons will increase by the sum of lengths of the arcs AF and GB, or each piston will move with respect to the inner race a distance equal to the arc AF or GB. It is this relative movement that produces wear. However, by providing a point of contact for each piston which is eccentric with respect to the axis of the piston the relative movement of each piston with respect to the inner race, as measured by are AF for example, results in a force component which produces a rotation of the piston on its own axis so as to castor, so to speak, causing the point of contact of each piston to oscillate in a small are thus distributing the wear over a larger area of the inner race.

The initial wear pattern produced by the foregoing action is shown in FIG. 4 by the series of arcuate darkened areas 32b, 32c, 32d which represents the wear marks left by adjacent pistons on the surface of the inner race 32a after a brief interval of operation of the fluid motor. After prolonged operation of the motor the arcuate wear marks 32b, 32c, and 32d merge into a continuous band 32:: forming a wear pattern of substantial area. This merging is probably explainable by differences in the friction force between individual pistons and the reaction ring causing the pistons to creep in gross with respect to the ring, or by shock produced within the motor in its usual application requiring rapid starts, stops, and reversals in rotation.

By virtue of the foregoing structure, the need for elaborate auxiliary anti-friction devices between the pistons and the reaction ring is completely obviated. Not only does this elimination of parts make for a more economical structure, but also it reduces the moment of inertia of the moving parts so as to permit of greater accelerations without deleterious effect.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions andehanges in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a rotary apparatus for operation with fluids, said apparatus comprising a rotatable cylinder block having a plurality of slideable pistons disposed radially therein to define a plurality of variable volume fluid chambers, valve means to expose each of said chambers alternately to high and low pressure conduits during rotation of said cylinder block, and a reaction ring eccentrically disposed with respect to the axis of rotation of said cylinder block and co-acting with said pistons to efiect radial movement thereof in timed relationship with the operation of said valve means; the improvement comprising the said pistons each having a substantially circular cylindrical configuration the elements of the cylindrical surface thereof terminating in at least one surface having a point thereof extending axially beyond all other points in said surface the said point being eccentric to the axis of rotation of said piston, and said reaction ring having a cylindrical inner surface in co-action with each of said points of said plurality of pistons whereby during rotation'of said cylinder block the said pistons are caused to oscillate upon their own respective axes to trace a plurality of contact paths on said reaction ring.

2. The improved structure of claim 1 wherein said one surface of said piston is a planar surface inclined at an angle less than a right angle measured with respect to the axis of rotation of said piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,673,514 Jernberg June 12, 1928 1,895,353 Sturm Jan. 24, 1933 2,292,181 Tucker Aug. 4, 1942 2,359,513 Eden et al. Oct. 3, 1944 2,383,060 Hoifer Aug. 21,1945 2,454,418 Zimmermann Nov. 23, 1948 2,470,220 Mott May 17, 1949 2,481,754 Johnson Sept. 13, 1949 2,736,267 Mosbacher Feb. 28, 1956 FOREIGN PATENTS 7 737,584 Great Britain Sept. 28, 1955

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