US2423639A - Rotary pump - Google Patents

Description

July 8,1947`. w. czARNEcKl ROTARY PUMP vFiled March 15, 1945' 2 Sheets-Sheet 2 Patented July 8, 1 947 ROTARY PUMP .Walter Czarnecki, Eddington, Pa., assignor'to Eddington Metal Specialty Company, Eddlngton, Pa.,.a partnership Application 'March 15, 1945,V Serial No. 582,837

This invention relates to rotary pumps and is concemed primarily with a rotary pump including movablev vanes as the elements which build up pressure on the fluid; u

The rotarytpump of the typewith `which this invention is concerned and' which' is now meeting with widspread use,'comprises` essentially a casing `orrhousing which provides a substantially cylindrical chamber with which communicates the lnlet and the Outlet. Rotatably mounted in this casing is a rotor which is also substantially cylindricalv in shape. The axis of the rotor is disposed 'eccentrically with respect to .the axis of the Vchamber to establish a crescent shape space between the rotor and the housing, and which i space extends from the inlet to the outlet.

In a more developed pump of this type, springs have-also been employed as means for actuating the vanesr However, any mechanism of this type including springs is rendered highly complex be-l cause of the ve'ry presence of. the springs and ;considerabledifficulty has beenl experienced not only in Originally assembling the pumps but also in servicing them,

- A 'still more refined development embodied in the known art, is the use of end rings which cooperate with the vanes to maintain the outer edges thereof in 'engagement with the wall of the boardedefining the chamber. The use of such end. rings is, doubtlessly, an improvement over earlierpumps of this type, but the presence of the end rings increases the size of the assembly for any given size rotor, and, in addition, considerable difliculty and-inconvenience is experienced in properlyassembling the vanes with respect to the rings in the original production and also in any later service Operations which might be necessary.

-In view of the condition of the art of rotary pumps as above outlined, and' particularly because of the complex nature ofV the efiicient pumps now available, this invention has, as its foremost objective, the provision of a rotary pump of'the -type above set forth, in which the Operating mechanism is highly simplifled, the number of 55 2 Claims. (Cl. 103-135) moving parts maintained 'at' an absolute minimum, and the efiiciency of operation 'kept at a maximum. In attaining this end, the invention achieves the lcomplete elimination of-springs, end rings or other moving parts employed for' actuating thel vanes, which heretofore have been deemed necessary to efllcient operation.

`A further object of the invention is the provision of a rotary pump of the cl' aracter aforesaid in which the rotor and vanes are constructed'so as to supplement the centrifugal force developed by rotation of the rotor, by pressure fluid to' move the vanes outwardly. In order for a pump'of this type to operate with required efliciency, it is necessary that the vanes fit into the rotor slots with a fairly snug fit. When the meeting parts are machined into a smooth condition, a'seal is'efiected which, not only tends to bind the engaging surfaces, but which'also creates a partial vacuum beneath the vanes when the latter tend to move outwardly, and this sealing effect is greatly increased'when the pump is employed ona hydraullc'medium, vsuch as oil, which forms a sealing film betweenv the'surfaces. With this particular condition in mind, the invention has in view, as a further object, the provision of a rotary pump of-the type :above described, which includes means forbreaking the seal between the vanes and the walls of the slot which receive them.

Both the objects of breaking fthis seal,=which impairs the sliding action of the vanes, and that of utilizing fluld pressure, asa supplemental actuating force for moving the vanes outwardly,-are accomplished by'the particular construction of the rotor and vanes which is obtained 'byv'thls invention. f

More in detail, the invention has as its object the provision of a rotary pump of therchar'acter aforesaid, which includes a sliding vane, the forward face of which is'formed with a'slot communicating between the upperand lower edges of the vane. In a preferred embodiment of the invention, two or more of theseslots maybeemploy e;d A and they serve'to break the seal between the faces of the rotor slot'and vane, and' also to bring the fluid under pressure down beneath the inner' edge of thervane, to move it outwardly.

Yet another object of thefinventiomis the provision in a rotary pump of the character aforesaid of a vane having its forward face slotted together with a channel on the inner edge of the vane which establishes' communication between' the u slots.

To the end of rendering the slotsfmore effeci 3 tive, the invention has as 'a further object, the provision of a rotary pump of the type indicated, which includes a rotor formed with slots receiving vanes, with the cylindrical face of the rotor cut away immediately in front of the forward faces of the vanes. Thus, as the rotor is turned, the fluid under pressure is readily admitted to the slots.

Another object of the invention is the provision in a rotary pump of the character aforesaid, of a vane which includes a closed channel extendingupwardly from edge thereof and which communicates with an aperture that opens on to the front face of the vane at, -or immediately adiacent to,` the upper or outer edge thereof. In this form of the invention two or more of lthese closed channels may also be employed and they bottom or inner edge become apparent, and in part be hereinafter` stated as the description of the invention proceeds.

The invention, therefore, comprises a rotary pump including a slotted rotor, together with vanes slidably assembled in the slots. The rotor is designed for rotation in one direction, and the forward face of each vane is formed with a plurality of slots extending from the outer edge of each vane to the inner or bottom edge, and this inner or bottom edge is formed with a channel establishing communication between the several slots.

For-a full and more complete understanding of the invention, reference may be had to the following description and accompanying drawings,

whei'ein:

Flgure l is a section through those parts of a rotary` pump with which this invention is immediately concerned: i

Flgure 2 is another sectional view taken at right angles to the showing of Figure 1; i

Figura 3 is an enlarged detailedperspective of the rotor per se;

Flgure 4 is a detailed cross section through one of the vanes;

Figura 5 is a. detailed perspective of one of the vanes;

Figure 6 is a detailed cross sectional view similar to Flgure 4, of one modification;

Figure 'I is a detailed perspective of the vane, the cross section of which is shown in Figure 6;

Flgure 8 is a cross section through yet another form of vane; and

Flgure 9 is a detailed perspective of the form shown in r'igure 8.

Beferring now to the drawings wherein like reference characters denote corresponding` parts, and first more particularly to Figures 1 and 2, a rotary pump embodying the improvements of this invention is shown as comprising a housing or casing I0, which is formed with a cylindrical bore and a second cylindrical bore |2 that communicates with the bore II. It is important to note that the axes of the bores and |2 do not align, but rather are eccentrie or offset with respect to each other. The end of the bore 2 is closed by a cover".plate |3 which may be secured to the housing in'any preferred manner, such as by screw fastening elements of the type indicated at Il. The cover plate I3 is formed with a cirthe inner or bottom may be connected at'the by a cross' channel formed i on the inner edge of the vane.

Viso

outer end of the shaft 20 is deformed out of a true circle to provide for engagement, by suitable source of power, for rotating the shaft. Such deformation may take the form of the flat indicated at 2 I.

The large ring 22 is tightly fitted in the bore |2 and abuts the shoulder 23 which divides the bores I I and |2. This ring 22 is provided with an opening through which the shaft 20 extends. That portion of the bore |2 between the cover plate |3 and the ring 22, together with these elements. deflne the pressure chamber of the pump which is designated 24. It is notable that the shaft 20 carries a bearing 25 adjacent to the outer end of the bore |I.`

Interposed between the ring 22 and the bearing 25 is a sealing assembly which is no particular part of the invention.` It merely serves to prevent leakage of the hydraulic fluid along the shaft 20. As is clearly shown in Figure 2, the casing |0 is formedtwith a fluid outlet 20 which communicates with the pressure Vchamber 24, and the fiuid inlet indicated at 21 also communicates with the pressure chamber 24, and also with a by-pass channel shown at 123. This `by-pass channel is also not particularly pertinent to the present invention, and is merely illustrated because it is employed in one practical adaptation which bypasses fluid. The present invention is concerned prmarily with what takes place in the action on the fluid between the inlet 21 and outlet 26, within the chamber 24.

Referrlng now more particularly to Figures 2 and 3, `a rotor 29 is shown as being keyedito the shaft 20, as indicated at 30. The rotor 20 is thus drivably mounted on the shaft 20 for rotation onan axis eccentric to the axis of the bore |2. The rotor 29 is provided with a plurality of slots 3| which, it will be noted, are disposed at an angle to any radius of the rotor. This angular disposition of the slots 3| is a feature of particular importance as will be later pointed-out.

At this point it is well to note that a rotary pump of this type will ordinarily be designed for rotation in one direction. This direction may be either clockwise or counterclockwise,` but unless the direction of rotation is determined, the pump is not susceptible of operation in a reverse direction to build up pressure of fluid. In the embodiment of the invention shown in Figures' 2 and 3, the rotor is designed for rotation in a clockwise direction.

Speaking with reference to this direction of rotation, the forward edges of each of the slots 3| are cut away as indicated at-32. This cut away or flat is of great importance, as will later become apparent. I

The number of slots 3| may, of course, vary in accordance with the engineering requirements of any particular installation. The number shown in the drawing is taken purely for' illustrative purposes.

of vane which is provided in accordance with the the vane which is referred to in its entirety by the reference character V comprises a substantally solid block, preferably of metal, having a front face 33 and a rear face 34, a top or outer edge 35, a bottom or inner edge 38 and end walls 31. It will be noted that the top or outer edge 35 is curved to conform to the curvature of 'the bore |2, as the edges 35 of all the vanes V are intended to slidably engage the wall of bore |2.

Extending from the top edge 35 to .the bottom edge 36, and formed in the front face 33 of the vane V, are a pair of channels 36, and it is particularly important to note that the channels 38 are most shallow at the outer edge and deepest at the inner edge, providing in effect tapered or the bore |2 to provide for maximum efllciency in the operation of the pump.

, The angular disposition of the vanes is of particular importance. In many instances it is desirable to employ a rotor of small radius and yet have a comparatively large degree of eccentricity between the rotor and the pressure chamber. This means there is a large space to be spanned by the vane. Not only must the vanes extend completely across the space of eccentricity, but there must be enough of the vanes left in 'the' slots to adequately support them. This fiared channels that enlarge in cross section from the outer edge to the inner edge.

Formed on the bottom or inner edge 36, and extending between the end walls 31, is communicating channel 39 which provides a space for pressure fluid beneath the entire length of the vane V.

Figures 6 and '7 show one modiflcation in the construction of the vanes. In this fon'n the vane is identified by the reference Character V1. This vane V1 includes the same front and rear faces, top and bottom edges and end walls described above in connection with the vane V. However,

three of the channels 38 are illustrated rather than only two. The point of distinction between the forms of invention shown in Figures 4 and 5 on one hand and Figures 6 and 7 on the other is that in Figures 6 and 7 the communicating channel 39 is eliminated and the lower ends of the channels 38 terminate in enlarged recesses 40 which, as is clearly shown in Figure 6, extend be- 'tween the front and rear faces 33 and 34.

The operation of the pump will be` the same re- I gardless of which of the vanes V, V1 or Vz are employed. The shaft 20 will be driven from a suitable source of power and rotates the rotor 29 in a clockwise direction (speaking with reference to showings of the drawings), in that portion of the bore |2 opposite the pressure chamber 24. `VThe outer edges 35.0f the vanes due to their engagement 'with the wall of' bore |2 are forced substantially completely within the slots 3|.

-As these vanes pass the inlet 21 they tend to move outwardly due to the centrifugal force. This tendency is supplemented by the fact that the fiuid under pressure is admitted to the upper extremities of the channels 38 and passes downwardly through these channels beneath the bottom edge 36 and, thus, moves the vanes out to their slots. The tendency of the snug intertting Walls of the vanes and slots to create a`seal or partial vacuum beneath the vanes is destroyed by the presence of these channels 38. Thus, it will be seen that the vanes V at all times completely bridge the space between the rotor and means that there must be a sufiicient distance between the outer and inner edges 'of the vanes to accomplish this end. If the slots were true radial slots, in many instances there would not be suflicient depth in the slots to achieve this end. The angular disposition of the slots provides for adequate extent of the vanes.

While preferred specific embodiments of the invention are hereinbefore set forth, it is to be clearly understood that the invention is not to be limited to the exact constructions illustrated and described because various modifications of the details may be provided in putting the invention into practice within the purview of the appended claims.

What is claimed is:

1. In a rotary pump having a rotor and a casing in which the casing is provided with a substantially enclosed cylindrical chamber with inlet and Outlet connections, means eccentrically mounting the rotor in the cylindrical chamber of the casing, said rotor having a plurality of slots rectangularshape in cross section extending inward from the periphery thereof, said 'slots having parallel sides and said'sides positioned at acute angles to radially extending planes from the center of the rotor with the slots sloping backward from the direction of rotation of the rotor, the peripheral surface of the rotor provided with beveled surfaces adjacent the leading edges of the slots, and a plurality of vanes slidably mounted in said slots, said vanes having arcuate outer ends, longitudinally extending recesses in the inner edges and passages across the leading faces thereof providing continuous communicating means between the periphery of the rotor through the sp'aces provided by the said beveled surfaces and the recesses in the inner edges of the vanes, whereby fluid under pressure in front of the vanes passes inward through the said passages in the vanes building up pressure behind the vanes for forcing the vanes outward accentuating the centrifugal force in the rotor.

2. In a rotary pump having a rotor and a casing in which the casing is provided with a substantially enclosed cylindrical chamber with inlet an'd Outlet connections, means eccentrically mounting the rotor in the cylindrical chamber of the casing, said rotor having a plurality of slots rectangular-shape in cross section .extending in- Ward from the periphery thereof, said slots having parallel sides and said sides positioned at acute angles to radially extending planes from the center of the rotor, with the 'slots sloping backward from the direction of rotation of the rotor, the peripheral surface of the rotor provided with beveled surfaces adjacent the leading edges of the slots, and a pluralit-y of vanes slidably mounted in said slots, said vanes having arcuate outer ends, longitudinally extending recesses in the inner edges and passages across the leading faces thereof providing continuous com-

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