US2278131A - Pump - Google Patents

Description

Patented Mar. 31, 1942 UNITED STAT Es PATENT OFFICE This invention relates to pumps` of the so-called vane type.

Several types of rotary pumps employ rotor propelled vanes for the purpose of creating a pumping action in a pump housing having a bore of approximately circular shape. In general these vane type pumps have been of two types, one in which the vanes are formed by a member which extends completely through the rotor which carries the vanes for rotation, the vane member being allowed to slide in the diametrically positioned opening in the rotor so that the projecting ends of the vane will contact the wall of the pump chamber to carry iiuid from an inlet to an outlet and thereby create a pumpingaction. In this so-called through typeof .vane pump, the pump chamber lis so shaped that the ends of each vane are continuously in contact with the Wall of the pump chamber. Another type of vane construction commonly used is that of two short vanes projecting from the openings in the rotor with a spring in thev center ofthe rotor to hold each of the two opposed vanes in contact with the wall of the pump chamber. It is to be noted that in both of the above types the vanes are generally locatedpin pairs diametrically opposed to each other and the vanes are held in openings in the rotor with relatively close clearance so that there is no tendency of the vanes to move circumferentially. It is also a characteristic of the above mentioned vane types of pumps' that the socalled workng'arc between the inlet and outlet ports must be substantially equal to the distance between the vanes carried by the rotor. -For, if

.the distance between vanes should be reduced below the equality, a pressure would be built up lbetween. two vanes during-the working are. Another way of stating this problem is that in the conventional vane type of pump with circular bore with no means of equalizing pressure between vanes only one vane can be pushing 'fluid in the working arc 'at one time since there must be a free passage to the outlet to compensate for differences in volumes enclosed between adjacent vanes during the working arc.

It is also a characteristic of the vane 'types of i pumps above mentioned that the spacing bet'ween the'vanes around the circumference of the rotor is necessarily` equal since, as above outlined, each ci these spaces must bear the same relation to the distance between the inlet and outlet ports. In some instances such a construction has been found responsible for execessive noise produced by the pump since the equal spacing sometimes sets up a resonance with a consequent hum.

In general, the operation of the conventional types of vane pumps has been quite satisfactory; However, since many of the ports require very accurate machining to assure this satisfactory operation, there would be a considerable saving in manufacturing cost if a pump couldbe devised wherein the parts would be both reduced in number and would not require great accuracy in dimensions.

It is therefore a primary object of the present invention to provide an eflicient pump of such simplicity of construction that comparatively few dimensions are required to be held to very close tolerances, thereby avoiding expensive machining operations and effecting material saving in manufacturing cost without reducingthe efficiency of the pump.

It is a further object to make possible the con# struction of a pump with a circular bore having means to compensate yfor difference in iiuid displacements by two or more vanes which may be operating in the working aro at one time, thereby making it unnecessary to maintain any denite relation between the arcuate distance from inlet to outlet and the arcuate distance between vanes.

It is another object to reduce the noise produced by a vane type pump (by a construction wherein the plurality of vanes are unequally spaced around the periphery of the pump rotor.` It is a further object to allow free iiow of iiuid around the surfaces of floating vanes loosely carried in notches in the periphery of a rotor there-K by assuring distribution of iiuid between a plurality of vanes operating in the working are at one time and making possible an increase in the number of vanes and an unequal spacing to reduce noise, such an advantage being accomf plished with a construction employing a minimum of parts, some of which require expensive machining operations in their manufacture.

It is another object to make possible the construction of a pump wherein a plurality of slipper type vanes are loosely carried in notches in the periphery of the pump rotor, the said rotor servi ing primarily to drive the vanes while centrifugal force and fluid pressures existing in the pump chamber are primarily utilized to hold substantially the entire sealing surface of the vanes in continuous contact with the wall oi the pump chamber for producing a pumping action.

It is also an object toprovide a construction for a pump wherein the impelling vanes are made in the form of so-called slippers loosely carried e WY- y in notches in the periphery of the rotor with` notches on the rotor serving only to drive the.

vanes, and the vanes or slippers being of such size and shape as to allow a passage of the fluid to the under side of the slipper members, there-` may be built up between the vanes and the` notches in the rotor.

It is a further object to provide a pump construction employing slipper type vanes of such size and proportions as to be balanced when loosely carried in notches in the periphery of a rotor so that said vanes will efficiently produce a pumping action by being held in sliding contact with the surface of the pump housing while being subjected; vto fluid pressure existing in the pump housing; to the driving force of the rotor; to the centrifugal force created by rotation with the rotor.

`It is another object to make use of appropriately positioned driving contacts between the loosely carried vanes and the driving rotor to make available a component of the driving force in a direction to assist movement of said vanes toward the surface of the pump housing.

It is another object to provide a pump with operating parts which are self compensating for wear.

It is a further object to make available a pump design which can be built around an existing shaft in l,the unit with which it is installed, the operating parts of the pump being carried near the periphery of the rotor shaft. With such a construction it is often possible to dispense with gearing between a thru shaft and the pump by placing the pump directly on the shaft.

The above and other objects of the invention Will appear more fully from the following more detailed description and Iby reference to the drawing forming a part hereof and wherein:`

Fig. 1 is a vertical transverse section taken through the pump housing and rotor.

Fig. 2 is a section taken on the line 2-2 of Fig. 1 and shows the inlet port together with the rotor and housing.

Fig. 3 is a transverse section through a portion of the rotor and housing of a pump of the type herein disclosed, showing the position and construction of a plurality of the vanes or slippers.

Fig. 4 is a section similar to Fig. l but includes resilient means to aid in holding the vanes or slippers in position.

Fig. 5 isanother varied construction showing means to position the slippers by fluid pressure on the opposite side of the rotor.

Fig. 6 is a form of construction which may be employed for positioning the slippers by an inclined edge of the notch on the rotor.

have ldriving means connected thereto for the purpose of actuating the pump. Itis understood that it would be possible to make the rotor I as a separate ring secured to a thru shaft, in which case the pump could be easily adapted for assembly on a shaft available in a motor or other unit without the provision of additional gearing or other driving means.

The rotor I has a plurality of notches 9 in its periphery, preferably spaced at unequal intervals. Slippers I0, which are substantially narrower than the notches 9, are disposed loosely in the notches, and are provided with outer surfaces having a curvature corresponding to the curvature of the chamber 6. The inner surfaces of the slippers have projections II adapted to contact bottom surfaces of the notches to prevent a at surface contact between the inner faces of the slippers and the bottom surfaces of the notches.

An intake port I2 and an outlet port I3 are provided in the vpump body, at substantially diametrically opposite points, the intake port I2 having extensions I4, and the outlet port having extensions I5, all extending-circumferentially of the pump chambers. The intake and outlet extensions I4 and I5 are separated adjacent the point of tangency I6 between the rotor I and the pump chamber 6, as indicated at I1, the arcuate width of said separation being slightly greater than the width of any notch 9. 'Ihe other ends of the extensions II and I5 are separated an arcuate distance greater than the arcuate distance between any two slippers, and this space constitutes the working zone.

As the shaft extension 2 is driven to rotate the rotor I, centrifugal force acts upon the slippers I0 and forces them into contact with the wall of the pump chamber 6,- and they are impelled around the pump chamber by the trailing edges of the notches 9. The slippers are thus caused to move the uid from the intake port I2 to the outlet port I3, and the pressure under which the fluid is placed during movement through the working zone acts on the inner faces of the slippers to augment the action of centrifugal force in holding the slippers in contact with the Wall of the pump chamber.

As will be noted on reference to Figs. l and 3, the slippers I0 are circumferentially long as compared with the greatest radial distance .between the point at which slipper I0 contacts the notch in the rotor and the wall of the Ipump chamber. Such a construction assures that there Will be a sufficient exposed inner surface on each slipper so that the fluid pressure action on the slipper-will always counteract the tendency of the Referring to the drawing, the pump shown in Figs. l and 2 comprises a rotor I, circular in section and having axial shaft extensions 2 and 3.

The shaft extension 2 is rotatably journalled in a bearing 4 inthe pump body 5 which has a circular pumpchamber 6 in which rotor I is mounted. The pump chamber 6 is eccentric with respect to the center of the rotor I and the chamber is closed by a cover plate I provided with a lbearing 8 in which the shaft extension 3 is journalled. The shaft extension 3 extends beyond the end of the bearing 8, and is adapted to driving force ofnotches 9 and as aresult the slippers will be continuously held in sliding surface contact with the pump chamber bore. As a further aid in counteracting this tendency to tilt, the trailing edge of each slipper may be relieved or chamfered, as indicated at I 8 in Fig. 3. Such a change in shape'will tend to set up a counter-clockwise tilting tendency induced by the action of fluid pressure on the inner surface of the slipper, the slipper tending `to tilt about the trailing edge of its contact with the -pump bore. By proper proportioning, the tilting effect of the driving notch can be counteracted to the desired degree. Probably a slight counter-clockwise tilting tendency is desirable to facilitate the entrance of an oil film between the slipper and the bore. The amount of this tendency can be controlled with suitable changes in proportions -by employing the principles above outlined.

Referring to Fig. 3, which illustrates the operation when a plurality of blades are passing simultaneously through the working zone, it may be observed that the slippers -Ia in being loosely mounted in notches 9a in the rotor la, are free tov move away from the trailing edges of their respective notches. The slippers ahead and behind the central slipper in Fig. 3 are free to move away from the driving edges of their respective notches to permit the fluid to pass as the slippers are carried through the working zone. Itis to be noted that this ability of the slippers to by-' pass fluid makes possible the use of ports which are spaced farther apart than the slippers which in turn makes possible unequal spacing of slippers and prevents the occurrence of uniform impulses, the presence of which might otherwise tend to produce a resonance.

It is further to be noted that the ability of adjacent slippers to by-pass fluid to compensate for unequal displacement of fiuid effects .a smooth transfer of pumping load from one slipper to another. Such a controlled and uniformly smooth transfer of. load is a material factor in reducing noise in this type of pump. Considering the slippers shown in the working arc Fig. 3 the central slipper, of the three shown, is near the center of the working arc and therefore is displacing fluid at a greater rate than the other two slippers, both being shown in Fig. 3 as by-passing uid. As

the rotor brings the right hand slipper toward the center it will gradually assume a position in contact with the driving edge of its notch which condition will be effected when the right hand slipper and the central slipper reach a position equally distant from the part of the working arc where there is greatest distance between the rotor and the bore. At such a position both slippers will be momentarily in contact with their not suflicient for this purpose due to a low speed of operatipn of the pump and in cases where very viscous fluids are being pumped.

I have shown in Fig. 5 an alternative construction to that of'Fig. 4 and wherein a push rod 20 is slidably mounted in a bore in the rotor 2l with its opposite ends projecting into substantially opposite notches 22. The ends of the rod lie adjacent the slippers 23 in respective notches 22,

and while one slipper is passing through the intake zone uid pressure in the working zone acts upon the remote end of the rod to force the rod against the opposite slipper and to force it into contact with vthe wall of the pump chamber. The use of a round rod makes possible the use of 1 a round reamed hole in the shaft which is more easily accomplished in manufacture, than other shapes. This construction may be used with pumps having a even number of slippers. The fundamental principle involved in the use of fluid pressure existing on the opposite side of the rotor to assist in positioning a thru type of vane having a length less than the shortest distance `across the bore, is disclosed and claimed in my 4is made by the notch with the edge of the slipper.

In Fig. 6 slipper 25 is shown provided with a trailing edge 2S inclinedat a considerable angle with both the radius of the bore and the radius of the rotor. The'notch 2 in the rotor has the face 28 which contacts the trailing edge 26 of the slipper also inclined at an angle which corresponds to the angle of the edge 26. If it be assumed that the rotor in Fig. 6 is rotating in a counterciockwise direction, it will be apparent that because of the inclination of the contacting surfaces 26 and 28 the rotation of the rotor will produce a componentof force which will push the slipper outwardly to contact the pump chamber.

Another feature of the construction, as shown in Figs. 1 and 3, is the tendency of the slippers to assume such a position relative to the driving edges of the notches that the rear edge surfaces will be inclined relative to a radius of 4the rotor in such direction that an outward componentof the driving force from the rotor tends to force the slipper radially outward. Such an inclined position is shown at 30 in Fig. l.

It is noted that the slippers do not fit in their respective notches with too close dimensions but that the notches are actually very much larger than the width of the slippers. In fact, every precaution is taken to assure that the slippers will started, centrifugal force tends to bring the slippers into contact with the bore, as the slippers are pushed around by the trailing or driving edges of the notches in the rotor. It is characteristic of the pump, herein disclosed, that the slippers or vanes fit loosely in the notches and such contact as occurs between the notches and the slippers is only such as is necessary for driving. As the slippers I0a Fig. 3 are carried thru the working arc they move fiuid from the intake port to the outlet port and whatever pressure is built up in the outlet is transmitted to the space not cause a hum, resonance or musical note.

faces and a minimum of wear results. However any slight wear which does occur is compensated for by movement of the slippers Illa further outward in the notches 9a. l

It has been found necessary to provide unob- I structed passage for fluid to ow to and from the space between the notch and the slipper as their notches prevents them fromI following the bore during the intake arc when there is lno otherwise the dash-pot action of the slippers in fluid pressureunderthem, thereby causing noise and loss of pressure. The slippers are therefore given a wide clearance, circumferentially in the notches, the inner leading edges 29 (Fig. l) are Y chamfered or otherwise formedto permit'oil to flow freely around them. The previously mens tioned projections II (Figs. 1 and 2) are also rality of slippers used. This uneven spacing has been found beneficial in preventing undue noise in the pump since unevenly spaced impulses do It is noted that because of loose slipper construction the relation between the distance between the ends of the ports and the distance betweenv the vanes orslippers need not be accurate as long v previous practice.

Although the principles of the invention have been illustrated by a description of a specific mechanism it is understood that various changes and modifications may be made without departing from the fundamental principles as indicated by the scope of the following claims.

I claim:

1. In a pump, a pump casing having a pump chamber of cylindrical configuration and having an inlet and outlet positioned on ,opposite sides thereof, a rotor mounted for rotation in the pump chamber and having a plurality of notches in the periphery thereof, a vane mounted in each of said notches and having circumferential width and radial depth less than the circumferential width and radial depth of said notches, respectively, whereby said vanes are carried in said notches with freedom of circumferential, tilting and radial movement relative to said rotor, each of said vanes having an outer arcuate surface curved on an arc of substantially the same` radius as said cylindrical chamber and said vanes having greater circumferential width than radial depth whereby fluid pressure admitted at the under side of said vanes through the space between each vane and the respective notch acts on a greater area on said under side than on the front thereof to insuresealing contact of the arcuate outer face of said vanes along a substantial surface area, the maximum distance between two adjacent vanes and between two adjacent notches of said rotor being less than the maximum distance between the inlet and outlet of said pump casing.

2. In a pump, a pump casing having a pump chamber of cylindrical configuration and having an inlet-and outlet positioned on opposite sides thereof, Ya rotor mounted for rotation in theA pump chamber and having a plurality of un` `equally spaced notches in the periphery thereof,

a vane mounted in each of said notches and having circumferential width and radial depth less thanthe circumferential width and radial depth of said notches, respectively, whereby said vanes are carried in said notches with freedom of circumferential, tilting and radial movement relative to said rotor, each of said vanes having an outer arcuate surface curved on an arc of substantially the same radius as said cylindrical chamber andsaid vanes having greater circurnferential widthfthan radial depth whereby' uid pressure admitted at the under side of said vanes through thel space between each vane and the respective notch acts on a greater area on said underside than on the front thereof to insure sealing contact of the arcuate outer faceof said vanes along a'substantial surface area, the maximum distance between two adjacent vanes and v between two adjacent notches of said rotor being `less than the maximum distance between the inlet and outlet of said 'pump casing, the free` dom of circumferential movement and radial tilting of said vanes in said notches permitting of said notches and having circumferential width and radial depth less than the circumferential width and radial depth of said notches, respectively, whereby said vanes are carried in said notches with freedom of circumferential, tilting and radial movement relative to said rotor, each of said vanes having an outer arcuate surface curved on an arc of substantially the same radius as said cylindrical chamber and said vanes having greater .circumferential width than radial depth whereby fluid pressure admitted at the under side of said vanes through the space between each vane and the respective notch acts on agreater area on said under side than on the front thereof to insure sealing contact of the .arcuate outer face of said vanes along a substan tial surface area, the maximum-distance between two adjacent vanes and between two adjacent notches of said rotor beingl no greater than the maximum distance between the inlet and outlet of said pump casing, each of said vanes having the trailing edge of their outer curved portion relieved to increase the tilting effect of the slipper about its trailing edge to insure sealing contact Awith the outer surface thereof with said pump casing.- i

4. In a pump, a body portion formed with a pump chamber wall and a fluid inlet and fluid outlet, a rotor mounted for rotation in said chamber having a plurality of notches cut in the periphery thereof, vanes `of circumferential width substantiallyless than the width of said notches loosely can'ied in said notches with freedom of radial and circumferential movement relative to with the centrifugal force resulting from rotation of said pump to hold said vanes in intimate sealing contact with the inner wall of said chamf ber, said notches being of a size' and spacing such that, the maximum allowed spacing between said vanes is less than the maximum distanc between said inlet and outlet.

5. In a pump, a body portion formed with a pump chamber wall and a fluid inlet and uid outlet, a rotor mrounted for rotation in said chamber having a'plurality of notches cut in the periphery thereof', vanes of circumferential width substantially less than the width of said notches loosely carried in said notches with freedom of `radial and circumferential movement relative to said notches, each of said vanes hav-y ing an outer arcuate surface of a radius substantially equal to the radius of the wall of said pump chamber and adapted to have substantial surface contact with said4 pump chamber wall,

means for admitting the uid pressure in said pump chamber tothe under side of said vanes to cooperate with the centrifugal force resulting from rotation of said pump to hold said vanes in "intimate sealing contact with the inner wall of said chamber, said notches being of a size `and spacing such that the maximum allowed spacing between said vanes is less than the max'- imum distance between said inlet and outlet, and means for preventing said vanes from sticking on their under sides to the bottom of said notches.

6. In a pump. a body portion formed with a pump chamber wall and a nuid inlet and fluid outlet, a rotor mounted for rotation in said chamber having a plurality of notches cut in the periphery thereof, vanes of circumferential widthi substantially less than the width of said notches loosely carried in said notches with freedom of radial and circumferential movement relative to said notches, each of said vanes having an outer arcuateA surface of a radius substantially equal to the radius of the wall of said pump chamberand adapted to have substantial surface contact with said pump chamber wall, means for admitting the nuid pressure in said pump chamber to the under side of said vanes to cooperate with the centrifugal force resulting from rotation of said pump to hold said vanes in intimate sealing contact with the inner wall of said chamber, said notches being of a size and spacing such that the maximum allowed spacing between said vanes is no greater than the maximum l-distance between said inletl and outlet, and means for preventing said vanes from sticking on their under sides to the bottom of said notches comprising relieved portions on the under sides of said vanes.

7. A 'pump of the typeemploying a rotor i mounted eccentric to a substantially circular pump chamber having an inlet and outlet communicating with the walls'of the pump chamber characterized by a pluralityof vanes with maximum. allowed spacing less than the maximum distance between said inlet and outlet each drivfen by contactl with a notch in said rotor but having freedom of movement circumferentially, radially and angularly with respect to said notch and having aconfiguration such as to provide passages to admit fluid under pressure-tothe inner surfaces and around said vanes, each of said vanes having an outer surface of arcuate shape curved on the same radius of curvature as the pump chamber so that said driving contact on said vanes by said notches combined with fluid pressure and centrifugal force position said outer curved surfaces of said vanes in stable equilibrium against the inner surface of tha said pump chamber in spite of the tendency

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