US3398884A - Armored vane - Google Patents

Description

United States Patent fABSTRACT OF THE DISCLOSURE There is disclosed herein a blade or .vane for a rotary, sliding-vane type pump having anexternal wear resistant armor or jacket disposed to engage the rotor slot at the places of high pressure and great wear wherewith to preserve the bladen The shape, form and substance of the armor and blade, as well as the way in which the armor is secured to the blade, are also disclosed.

Background of the invention (l) The field of our invention is in air or gas pumps having expansi-ble chambers of the rotary type with movable vanes or blades slidably reciprocating in slots in the rotor as induced by the contour of the bore of the pump and rotation of the rotor. Within this field is the area of reducing wear and/or frictional losses between the vanes and rotor slots, as well as between the vanes and the bore. Within this area our invention pertains to armoring or jacketing the vanes or blades for better sliding contact and coaction with the slots in the rotor. a

(2) Our prior Patent No. 3,286,913, issued Nov. 22, 1966, illustrates and describes 'one type of rotary, slidingvane, so-called vacuum, pump wherein the armored vane of our present invention has utility and advantage. Our prior Patent No. 3,191,852, issued June 29, 1965, solved a problem related to our present invention in an environment in which our present invention alsohas utility and advantage. In a sense our present invention comprises-an improvement over our prior patent. Davey Patent No. 3,044,687, issued July 17, l962,-teaches -armoring.lthe sliding vanes of a rotary purnp. -Our invention comprises an improvement upon the teaching of this patent. A particular problem solved by our invention hasbeen that of'attaching and securing metallic armor to a reciprocating pump blade in a practicabe and economical way with permanence of attachment and with correctly located and aligned engagement between the armor and the blade. Another problem has been to armor, or provide a metallic jacket for, a carbon or non-metallic blade and make theexternal surface of .the jacketed blade true an planar throughout the working flank of the blade and in intimate bearing contact with the body of thev blade throughout the jacketed or armored area thereof, Another problem in the prior art was that of providing enough armor without increasing the mass and inertia of the blade deleteriously. Other problems and our solutions will more appear below.

Summary A preferred form and embodiment of our'invention comprises the combination of a carbon blade for a rotary pump and a wear resistant metallic jacket which snugly and truly overlies the trailing or working flank ofthe blade and the leading heel of the blade where wear between the blade and rotor slot is the greatest. This combination is further characterized by the channel shape of the metallic jacket with legs of markedly unequal length; the leg of greater length comprising the external face for the load bearing flank of the blade, and the leg of shorter length joining the base of the channel at the load bearing heel of the blade; the non-metallic body of the blade having recessed, smooth, planar areas engaged by fully 3,398,884 P t nt d ug. 27, 1968 2 the said legs of the jacket respectively in continuous intimate tight contact with the inner faces of said legs; said recesses having depth-substantially equal to the thickness of said legs whereby the external surfaces of'said legs are substantially planar and coincident'with the adjacentexposed unarmored flank surfaces of s'aidy'a'ne s the armored jacket preferably comprising hardened and tempered stainless steel with the shorter leg biased inwardly toward the opposite, root portion of the longer leg so that the free end of '-the shorter leg when assern-bled'with the' vane is resiliently stressed and exerts 'a stout gripping force upon the' vane near the base of the channel of the jacket constraining the whole of the longer leg of the jacket into smooth, tight engagement with the body of the vane and in stressed parallelism with the opposite flank of the vane. As will more fully appear, the root portionof the vane, 'i. e., the radially inward end thereof, is jacketed entirely within the base of the channel, preferably not snugly filling the inner corners thereof, whereas the tip of the vane and a significantly great portion of the body adjacent the tip is not armored and may comprise that portion of the body the vane which is expected to wear away by sliding contact with the bore of the pump during the intended life of the vane. This fulfills one of our objects of providing a desirable very low'friction sliding contact between the non-metallic or carbon body of the vane or blade with the bore of the pump throughout a long useful life while armo'ring those portions of the vane most subject to wear in the rotor for a correspondingly long life therein. A collateral object and advantageis that all the essential and arduous sliding and wearing contacts and engagements between the blade and the pump are between a metallic surface and a carbon, or non-metallic surface.

Others of our objects are accomplished by forming a metallic jacket with one leg ,very much shorter than the other: In this way the weight of the jacket is materially minimized While protective armoring is provided over the critical wearing areas between the blade and rotor slot without deleterious increase in'the mass and inertia of the blade. The long and short leg characteristic of the jacket also permits assembly of the body without harmful deflection of the long leg from its broad, tight load hearing contact and engagement with the loadbearing flank of'the body of the vane, and provides a stout resilient grip between the jacket and the vane. This grip is permanent in the sense of holding the jacket in place throughout the life of the blade, while, however the body of the blade may be slid forcibly out of the jacket by forcible endwise movement.

Brief description ofthe drcirvings FIGURE 1 of the drawings is a fragmentary transverse sectional view'illustrative' of conventional relationship of rotor, bore and blade or vane ina pump in which our of the combination of the body and jacket elements of ourinvention.

FIGURES l0 :and 11 are exaggerated illustrative end views of undesirable results following prior practices of attempting to armor blade bodies with channel-shaped armor. s

Description of the preferred embodiments In the preferred form and embodiment of our invention the armored blade or vane V, FIGS. 1, 6 and 7, has its useful life and being reciprocating in the slot S of a cylindrical rotor R of .a rotary pump P which has a generated bore B inducing reciprocation of the vane in the slot with rotation of the rotor. Rotation of the rotor, counterclockwise as suggested by the arrow at, sweeps the outwardly extended portion of the blade through the working chamber C of the pump against the resistance of the pressure suggested by the arrow p which is built up ahead of the blade compressing the gas or other fluid ahead of the blade and tending to rarify and suck gas or other fluid behind it. Centrifugal force maintains the tip T of the blade in fluid-tight, sealing and sliding contact with the bore B.

These working forces suggested by the arrow p press the trailing flank 10 of the blade forcibly against the trailing wall 11 of the slot S and tend to cant the blade clockwise, as viewed, in the slot against resistance of the heel 12 of the blade in its forcible sliding contact with the leading wall 13 of the slot. Those skilled in the art will understand that many other forces are imposed upon the blades or vanes of rotary pumps, and that the force and consequences mentioned above act more deleteriously as the wearing parts become worn. We have therefore armored the blades or vanes where the Wear tends to be greatest whereby to preserve not merely the armored parts of the blade but also to preserve the walls of the rotor slot by the benefit of reduced friction between the armor and the slot.

In this preferred and illustrative form of our invention and of its environment, the body and bore of the pump, the rotor and the body of the vanes, apart from the armor or jackets therefor, may be made of the materials described in our prior Patent No. 3,191,852, except for the lithium halide impregnation, which we do not necessarily exclude, should an atmospheric condition, or otherwise demand it. For present purposes the blade or vane is made of pure mechanical carbon grade 3310 and-the jacket or armor made of 17-7 PH stainless steel, heat treated after forming for spring temper, resilience and surface hardness to condition TH 1050 with all burrs and sharp edges removed and all outside surfaces polished to about 6 R.M.S. smoothness after heat treating.

The carbon body 15 of the vane V, FIGS. 2 and 3, is shown with its rounded tip T downward, has an octagonally formed root 16, square smooth planar longitudinal ends 17 and smooth planar flank surfaces 18, 19, and 21.

The surfaces 18 and 19 are ultimate exterior surfaces of the vane V, and are not intended to be armored, but rather are intended to lie in planar extensions of the exterior surfaces of armor as shown in FIGURE 7. The surfaces 20 and 21 are recessed or depressed below the adjacent surfaces 19 and 20 respectively for a depth equal to the thickness of the overlying armor or jacket, and are parallel with the surfaces 18 and 19 respectively. The overlying legs of the jacket, see FIGS. 5 and 7, will have substantially continuous, planar, interface contact with the surfaces 20 and 21 whilst the exterior surfaces of the jacket lie in the planes of the surfaces 18 and 19.

As suggested above, the armor for the blade B comprises a spring-tempered, hard-surface sheet of stainless steel 30, FIGS. 4 and 5, which was first theretofore bent and formed into shape with a long leg 31 and a short leg 32 joined to a base 33. As shown in FIG. 5 the legs 31 and 32 are inclined toward each other and have a maximum space between them adjacent the base of the channel equal to the thickness of the root end of the body 15 of the blade between the faces 20 and 21. The legs will join the base of the channel in curves of small radius which however avoid forcible contact with the root of the blade by virtue of the octagonal form 16 thereof so that the middle of the root of the blade may bear firmly against the inside base of the channel of the jacket. The armor or jacket 30, FIGS. 4 and 5, will have been formed and tempered preliminarily to assembly with the body 15 so that the body will require forcible entry into the jacket against the resilient resistance of the latter, see FIG. 8. The jacket will also have been smoothed off in respect to all its external angles, surfaces and corners as by tumbling in a polishing drum, or otherwise, so that the external surfaces 31 and 32, especially, will have a low coefficient of friction for free sliding contact with the slot of the carbon rotor R. The free corners of the legs 30 and 31 such as the corners 34, FIG. 4, are rounded and smoothed to avoid protrusion which might gall the juxtaposed surface of the rotor slot.

Preferably, the long leg 31 of the jacket is curved slightly about an axis lying near the plane of the base and parallel with the channel to be concave toward the leg 32 on a radius about 60 to times longer than the leg 31 as viewed vertically in FIG. 5. The short leg 32 may also be curved on the same large radius, concave toward the long leg. This slight curvature of the legs is related to the thickness of the stock of the jacket mentioned in an illustrative example below. The legs may be formed truly straight and planar, but this small curvature insures a more certain substantially continuous, planar engagement between the inside surface of the leg 31 and the depressed surface 20 of the body of the vane.

As shown in FIGS. 6 and 7 the jacket or armor 30 in its working assembly, coaction and combination with the body 15 is slightly shorter, or narrower, longitudinally than the body by a matter of a few thousands of an inch, shown, however, with exaggeration in FIG. 6. Each of the legs of the jacket are also made a little shorter, vertically as viewed in FIGS. 6 and 7, than the extent of the respective depressed areas 20 and 21 of the body so that small but appreciable gaps 35 lie between the ends of the legs and the shoulder termini of the depressed areas. This insures freedom of assembly and the entrance of the root portion of the body all the way to the bottom of the channel of the jacket, FIG. 7. In FIGS. 6 and 7, the final assembly of the jacket and body elements has been assumed, and the final snug embrace therebetween has been shown in anticipation of our teaching our method of assembling these elements, about to be described with reference to FIGS. 8, 9, l0 and 11.

We found that the attempted assembly of a rectangular vane body, such as the body 25, FIGS. 10 and 11, with and into a channel-shaped jacket having legs of about equal length was extra-ordinarily difiicult, if not impossible, especially Where an essentially frictional grip between the parts was sought and where substantially tight, uniform contact was desired throughout all, or almost all, the area of the body intended to be covered and armored by the jacket.

In FIG. 10 the miserable condition is suggested wherein the portion of the body inserted into the channel of the jacket 26 was just a very little thicker than the idle width of the channel. As a result the legs of the channel are merely splayed apart and rendered useless in or near a rotor slot. In FIG. 11, the consequence is suggested of trying to get an initially bow-legged channel-jacket 27 to embrace the body 25. The grip is all at the ends of the legs. The bulges between the lips and the feet fail to embrace the body uniformly and offer a flabby fatness in the rotor slot of evil consequence. One may imagine a parallel legged channel-jacket just exactly big enough to let a body of exactly the right size enter without distortion or deflection of the legs, but thereupon, by definition, no substantial frictional bond can be developed between the body and the jacket. Such a hypothetical union would invite disaster in a pump.

Our successful solution to this problem included the novel provision of the channel-jacket with one leg markedly shorter than the other, and curving both the legs with a mild bias toward a snug fit. This permits all the stress of spreading the legs to receive and grip the body to be concentrated in (a) the short leg and (b) a correspondingly opposite short portion of the long leg. These short leg lengths thus involved are so proportioned and so preformed as to avoid bowing or splaying, cf. FIGS. and 11, within their own lengths, and, happily, the whole length of the long leg beyond its short upper length is not subjected to distortion, but, on the contrary is firmly encouraged to lie flat and tight against the whole planar surface 20.

In FIGS. 8 and 9 our simple and satisfactory mode of conbining the body with the jacket-armor is illustrated. In FIG. 8 the jacket is shown to have its short leg 32 pried away from the opposite portion of the long leg and stressed from its idle inclination shown in FIG. 5 by forcibly prying the root end of the body, leftwardly as viewed, into the channel while the jacket is supported immovably with its long leg 31 supported throughout its length against deleterious bending, 'and the base of the channel held against leftward motion by the shoulder of the support. Direct or somewhat wiggled prying motion springs the channel resiliently open enough to let the root of the body quickly find the base of the channel, and snap down to fully-engaged and assembled condition shown in FIG. 9. The smooth tumbled and slightly rounded inner edge of the end of the leg 32 aids and lets the root of the body slip home smartly and safely.

In FIG. 9, the small arrows 1 to 7 inclusive suggest by their lengths and direction, the distribution of forces which (a) hold the combined parts together in firm frictional engagement, and (b) hold the legs tightly in contact with the depressed flank areas of the body of the vane.

The following specification of values and dimensions which we have found useful will embellish our teaching 'and air those skilled in the art to understand and enjoy our invention. Given a pure mechanical carbon vane body .760"-.765" long, measured radially of the pump rotor, vertically in FIG. 3, with maximum thickness near its tip T between parallel sides of .1240".1250", and minimum thickness between the depressed areas 20 and 21 of .0988"-.0998" resulted in about .0126"-.0131" depth to the depressed areas whereby to receive the legs of the jacket having thickness of .0120 and .0003".

The jacket for this body is .0990" and .0005", plus twice the thickness of the material, wide across the outside base of the channel, has its long leg .557" long, vertically as viewed in FIG. 5, and its short leg .185 long both measured externally. The gaps 35 between the ends of the legs and the shouldered termini of the areas 20 and 21 are significant 'at about .020-.030" long in the direction of the length of the legs. In its finished, pre-assembled state the inclination of the legs 31 and 32 toward each other is preferably such that the shortest distance from the tip or free-end of the short leg 32 to the long leg 31 is about .0l6"-.0l7" less than the same measurement when the legs are parallel and/or in tight assembled combination with the body 15 of the v'ane V as illustrated in FIGS. 6, 7 and 9.

While we have specifically illustrated and described a useful and preferred form and embodiment of our invention, changes and improvements will occur to those skilled in the art who come to understand its essential principles and accomplishments, so we do not want to be limited to the specifically disclosed form and embodiment nor limited in any other way inconsistent with the progress by which we have promoted the art.

We claim:

1. An armored vane for a rotary pump comprising in combination a metallic, wear-resistant, spring-tempered jacket, and a body having a root and tip at opposite radial ends and having depressed, parallel, planar, flange surfaces on opposite sides extending unequal lengths from said root toward said tip, said jacket being of channel form with parallel legs of unequal lengths substantially corresponding to the lengths of said depressed surfaces respectively, both said legs being in stressed resilient engagement with said body on said opposite, depressed flank surfaces, both said legs having tight, intimate contact with said depressed flank surfaces throughout substantially the whole of the areas common to said legs and said surfaces and said jacket and being held together by stressed frictional engagement therebetween.

2. The combination of claim 1 wherein the free end of the shorter of said legs is disposed opposite a midportion of the longer of said legs, and the maximum resilient grip exerted by the longer leg upon said body is exerted in the midportion of said depressed surface of greater length.

3. The combination of claim 2 wherein said body has a flank surface between said tip and said depressed area of greater length which lies in the plane of the exterior surface of the longer leg of said jacket.

4. The combination of claim 3 wherein said longer leg before being put in stressed assembly with said body was curved on a radius many times its length to be concave facing said shorter leg, and said leg before being put in stressed assembly with said body were inclined toward each other from parallelism to the extent that the free end of the shorter leg was nearer the longer leg by no less than its thickness.

5. The combination of claim 4 wherein said body is made of mechanical carbon and said jacket is made of stainless steel tempered after being formed and stressed within its elastic limit by engagement with said body.

6. The combination of claim 1 wherein said body also comprises unarmored flank surfaces between said tip and the ends of the legs of said jacket, and wherein said legs r are of uniform thickness with their external surfaces parallel to each other and in planar extensions of said unarmored flank surfaces.

7. The combination of claim 6 wherein the body of the vane is made of carbon, the jacket of stainless steel stressed within its elastic limit in said engagement with the body and wherein the trailing flank surface of the vane, in the sense of its disposition in a pump, is largely armored and the leading flank surface apart from the heel is largely unarmored.

8. The combination of claim 1 wherein the thickness of said armor is uniform and no more than about one eighth the thickness of the body of the blade at the root end thereof, the shorter of said legs is not substantially more than about twice as long as the said thickness of the body and the longer leg approaches the tip of the blade and is adapted to comprise the essential surface of the trailing flank of the vane where maximum wear would otherwise take place.

References Cited UNITED STATES PATENTS Re. 24,932 1/1961 Davey 91-119 959,049 5/1910 Boland 230-152 2,969,171 1/1961 Venediger 103-126 3,044,687 '7/1962 Davey 103-216 3,180,564 4/1965 Fuhrmann et al 230-152 3,191,852 6/1965 Kaatz et a1. 230-152 3,194,488 7/ 1965 Fuhrmann 123-8 3,197,125 7/1965 Bachman et al 123-8 3,235,171 2/1966 Frenzel et al. 230- 3,286,913 11/1966 Kaatz et al 230-152 3,300,124 1/1967 Jones 123-8 FOREIGN PATENTS 565,447 11/ 1944 Great Britain.

FRED C. MATTERN, 111., Primary Examiner.

WILBUR J. GOODLIN, Assistant Examiner.

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