US3453936A - Rotor vane - Google Patents

Description

July 8, 1969 P. A. BIEK ETAL ROTOR VANE Filed Oct. 5, 1966 INVENTORS. PAUL A. BIEK MARTIN D HOZA United States Patent 3,453,936 ROTOR VANE Paul A. Biek and Martin D. Hoza, Houston, Tex., assignors to G. W. Murphy Industries, Inc., Houston, Tex., a corporation of Texas Filed Oct. 3, 1966, Ser. No. 583,787 Int. Cl. F01c 1/00, 13/02, 21/12 US. Cl. 91121 3 Claims ABSTRACT OF THE DISCLOSURE Air operated motors for use in portable tools, such as grinders, drills, fastening tools, and the like have been long known. Motors of this type are generally provided with a cylinder mounted within and spaced apart from the walls of a housing to define a fluid exhaust chamber. The cylinder is hollow and formed with fluid inlet and exhaust ports, while a rotor, having a plurality of radially movable vanes, is supported for rotation within the cylinder. The rotor vanes are movable under fluid pressure and contact the cylinder wall to provide motive power in response to pressure being exerted upon them. Prior art motors of the type generally described are taught by the following US. patents: 1,942,784 to F. D. Terrill, 600,343 to Collins, 1,884,584 to Robert E. Cross, 2,159,- 232 to Shaft, 2,222,689 to Schottde, and 2,337,897 to Gaimerson.

When air-operated motors of the type aforementioned are utilized in fluid powered grinding tools, buffing tools and the like, considerable wear takes place on the rotor vanes, and in fact vane replacement is the primary cause of repairs to these motors. Grinding tools and the like are differentiated from other tools employing this same general type of motor in that grinders are not provided with clutches and when operated, run for relatively long periods of time, as opposed to the intermittent running periods for drills and fastening tools; for these latter tools the primary cause of tool breakdown results from clutch and transmission breakdown as opposed to rotor vane deterioration. In operating, considerable heat will be generated by the vane of the motor which causes excessive wear. This undesirable heating accelerates deterioration of the rotor vanes in two ways, as follows: it reduces the lubricating qualities of lubricants located between the vanes and the cylinder wall, and it tends to decompose the vane material.

It was found that, in addition to heating and the consequential problem of heat dissipation, motors constructed in accordance with the prior art teachings were ineflicient in operation when applied to grinding tools. The reason for the foregoing appears to be that the pressure forces exerted on the rotor vanes by the operating fluid, and the centrifugal forces generated by rotation of the rotor were not optimumly distributed over the vanes. Such force distribution patterns results in decreased vane life, and further it requires that the vanes be constructed with sloped side walls in order that they not frictionally engage the cylinder heads during use.

Finally, it was determined that motors when constructed in accordance with the teachings of the prior art and incorporated into grinders tended to accumulate with in their cylinders a quantity of foreign matter that increased uneven deterioration of the rotor vanes. This foreign matter usually comes from two sources as follows: it is composed of particles entrained in the operating fluid and trapped in the cylinder; and it is composed of particles produced by vane wear and likewise trapped in the motor cylinder.

Therefore it is a primary object of this invention to provide a new and improved fluid operated motor for portable grinding tools and the like, that causes the rotor vanes to wear evenly.

It is another object of this invention to provide a new and improved cylinder for air operated motors.

It is the further object of this invention to provide a novel motor for a portable grinding tool that utilizes the operating fluid in such a manner as to provide eflicient cooling of the motor parts, to sweep foreign particles out of the motor cylinder, and to optimumly distribute pressure against centrifugal forces on the rotor vanes.

These and other objects of this invention will become apparent upon a study of the hereinafter described embodiment of the invention taken in conjunction with the drawings, in which:

FIGURE 1 is a side sectional view, having parts broken away of a power tool incorporating the fluid pressure motor of the present invention;

FIGURE 2 is a sectional view the line 2-2 of FIGURE 1;

FIGURE 3 is a perspective view of a motor cylinder used in the tool shown in FIGURE 1;

FIGURE 4 is a plan view of a rotor vane as used in a pricpr art motor showing the deterioration of the vane; an

FIGURE 5 is a view of a rotor vane showing the uniform wear achieved by the motor of the present invention.

A typical grinding tool constructed in accordance with the teaching of this invention is shown in FIGURES l and 2 of the drawings, wherein a motor housing 10 is provided with a chamber 12 having a motor assembly 14 mounted therein.

The motor assembly comprises a cylinder 16, rigidly supported between a pair of cylinder heads 18 and 20. The cylinder heads have mounted therein and support a pair of ball bearing housings 22 and 24 respectively, 'WhlCh rotatably support the usual ball bearings. A rotor 26 having a pair of projecting shaft ends 28 and 29 is mounted for rotation in the cylinder with the shaft ends belng journaled within the bearing housings. The rotor is provided with a plurality of piston blades or vanes 30, slidably mounted in radiating slots 32. The rotor shaft end 29 is formed with gear teeth 34 which engage a plurahty of idler gears 36 that constitute part of the usual and customary transmission assembly for driving a grinding tool or the like.

Prior art motors utilized for grinding tools and the like are provided with a motor cylinder having a plurality of ports communicating with a longitudinally extending fluid entry or fill bore, such as the bore 38 shown in the cylinder 16. The fluid entry ports are usually longitudinally spaced apart along the fill bore. The cylindrical bore 38 communicates with a fluid-fill cavity 40 located in the rear or handle end of the motor housing 10. The fill cavity communicates with the usual throttle and throttle control assembly which is connected to a source of high pressure air or other operating fluid. The fill bore 38 also communicates with a pair of kickout ports 42 and 44 located in the cylinder heads 18 and 20 respectively. The kickout ports cooperate with fill cavities in the rotor slots 32 and are utilized for the purpose of injecting air or other fluid into the cavities to thereby of the motor taken along force the vanes 30 into contact with the inside wall of the cylinder 16.

The prior art cylinders have the same general Wall construction and geometrical configuration as the cylinder 16. They are usually provided with a plurality of exhaust ports, which ports are symmetrically located relative to the cylinders fluid entry ports. The exhaust ports are normally circumferentially displaced from the entry ports in order that motive power fluid will flow in a clockwise direction within the cylinder, expand and thereby exert pressure on the rotor vanes for a specified number of degrees of rotation per revolution, after which the fluid is exhausted.

In directing the power fluid to flow circumferentially the rotor vanes of the prior art have to be provided with sloped edges '52 as shown in FIGURE 4 of the drawings. The rotor vanes employed in prior art motors have their edges angled by a specific angle A in order that as they became unbalanced by the deterioration represented by the unequal sides B and B they would not frictionally engage the cylinder heads 18 and 20. When a cylinder constructed in accordance with this invention is employed in the motor, the rotor vanes do not have to be provided with angled edges as shown in angles A in FIGURE 4 or angles C in FIGURE 5.

The cylinder 16 of the present invention, FIGURE 3, is designed so as to make efiicient use of the motive power fluid to overcome the objectionable features of the prior art motors mentioned infra. Such a cylinder is provided with a plurality of fluid entry ports 46 located either forwardly or rearwardly of the cylinder shown in FIGURES 1 and 3, which ports communicate with the fill bore 38. A plurality of exhaust ports 48 and 50 are grouped together and longitudinally and circumferentially displaced from the fluid entry ports. Power fluid is therefore constrained to travel a longitudinal and circumferential path within the cylinder; it expands and exerts turning pressure on the rotor vanes. The motor casing 10 may also be provided with a plurality of grouped together exhaust ports 56, which may be laterally and circumferentially displaced relative to the cylinder exhaust ports 48 and 50. In this manner, motive power fluid exhausted from the cylinder 16 circulates through an annular passageway 58 created between the outside wall of the cylinder 16 and the inside wall of the motor casing 10, and it may also be made to travel a circumferential and longitudinal path from the ports 48 and 50 to the ports 56 where it is exhausted to the atmosphere.

In operation, motive power fluid is directed into the fill cavity 40 by operation of a throttling valve controlled by a valve operator 60. Fluid is thereby forced into the fill bore 38, the entry ports 46, and the kickout ports 42. Under pressure, the fluid expands within the cylinder and it flows from the forward end of the cylinder rearwardly and in a clockwise direction around the cylinder to the exhaust ports 48 and 50. After being exhausted from the cylinder, the fluid then flows in a counterclockwise direction and forwardly towards the motor casing exhaust ports 56. In this manner, the flow of air is such as to optimumly distribute forces on the vanes 30, and at the same time to efliciently use the fluid as a coolant for the purpose of minimizing wear. For this latter purpose it is to be noted that with a motor cylinder constructed in accordance with this invention the operating fluid always has a lower temperature than the motor parts. The fluid is swept along the surfaces of the cylinder, rotor and vanes and thus is able to maximize its cooling effect on these surfaces and at the same time the fluid is swept circumferentially within and without the cylinder and thus achieves, in addition, whatever cooling effect devices the prior art achieved. Since the flow of fluid is in a constant direction at all times, particles that might have been trapped within the cylinder to cause additional uneven wear on the rotor vanes are constantly swept in one direction and therefore effectively moved out of the cylinder and the motor casing. As shown in FIGURE 5 of the drawings, the wear on the rotor vanes utilized in a motor cylinder of the type taught by this invention is even on both ends.

Although a specific embodiment of our invention has been shown and described, applicants do not intend to be limited thereby. Alternative constructions for the cylinder and placement of inlet and exhaust ports will form a study of this specification occur to those skilled in this art. For example in some cases it may only be desirable to group the inlet ports and the motor casing exhaust ports to achieve the described flow pattern outside of the motor cylinder. Alternatively the inlet ports and cylinder exhaust ports may be grouped and displaced as described whereas the motor casing exhaust ports may be distributed as opposed to grouped.

Having described our invention, we claim:

1. In a pressure fluid operated motor for a grinding tool including a motor housing and a rotor having a plurality of radially movable vane members mounted therein, the improvement which comprises:

a motor cylinder rigidly supported within said motor housing and spaced therefrom to define therewith an annular chamber;

said motor housing having a plurality of exhaust ports communicating with said annular chamber;

said motor cylinder being provided with a longitudinally extending fluid entry bore and a longitudinally extending cylindrical bore, said rotor being mounted for rotation Within said last named bore;

said motor cylinder formed in its cylindrical portion with a plurality of grouped fluid entry ports, said ports communicating wtih said longitudinally extending fluid entry port and said bore; and

said motor cylinder being provided in its cylindrical portion with a plurality of grouped fluid exhaust ports longitudinally and circumferentially displaced from said grouped fluid entry ports and communicating with said rotor bore and said annular chamher.

2. A pressure fluid operated motor according to claim 1 wherein said motor housing exhaust ports are grouped together and are longitudinally and laterally displaced relative to said fluid entry ports.

3. A pressure fluid operated motor according to claim 1 wherein said plurality of cylinder fluid exhaust ports are grouped together and are circumferentially and longitudinally displaced from said cylinder fluid entry ports; and wherein said motor housing fluid exhaust ports are grouped together and are longitudinally and laterally displaced from said group of cylinder exhaust ports.

References Cited UNITED STATES PATENTS 2,857,143 10/1958 Kroeckel et al. 91-121 X 3,190,183 6/1965 Walker et al. 91-121 X 3,307,454 3/1967 Larsson 91-121 3,376,825 4/1968 Burnett 91-140 X 1,147,238 7/1915 Hauer 91-121 X 1,805,023 5/1931 Springsteen 91-140 X 3,241,457 3/1966 Reed 91-138 X 2,159,232 5/1939 Shaif 91-138 X 2,570,009 10/1951 Schmid 91-135 X 2,980,078 4/1961 Conover 91-138 3,238,848 3/1966 Bent 91-138 EVERETTE A. POWELL, ]r., Primary Examiner.

U.S. Cl. X.R. 91-135

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