Rotary pump

March 7, 1939.

R. DEMING

ROTARY PUMP Filed Dec. 11, 1934

2,149,337

Sheets-Sheet 1

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March 7, 1939. r deming 2,149,337

ROTARY PUMP Filed Dec. 11, 1934 2 Sheets-Sheet 2

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Patented Mar. 7, 1939

2,149,337

UNITED STATES PATENT OFFICE 2,149,337 ROTARY PUMP Robert Deming, Norwood, Ohio, assignor to Deming Rotary Pump Company, Cincinnati, Ohio, a corporation of Ohio ~

Application December 11, 1934, Serial No. 756,989 12 Claims. (CL 103—136)

This Invention relates to fluid pressure or vacuum pumps of the rotary piston type and has for its object to provide a pump in which the leakage of the fluid being pumped past relatively 5 moving parts of the pump is reduced to a minimum, and in which the pressure in the high pressure side of the pump chamber is utilized to maintain a fluid-tight engagement between the vanes which act as pistons or sealing members 10 and the relatively movable parts with which they engage, so as to reduce leakage past sUch pistons or sealing members from the high pressure side to the low pressure side of the pump chamber.

A further object of the invention is to provide 15 a pump in which the relatively movable parts are provided with sealing grooves so disposed as to effectively check flow of the fluid being pumped between the relatively movable contacting surfaces of the pump elements. /

A further object is to so conduct, apply and utilize the normal forces generated by the pumping operation as to make the sealing provisions more effective.

With the above and other objects in view, the ” invention may be said to comprise the pump as illustrated in the accompanying drawings hereinafter described and particularly set forth in the appended claims, together with such variations and modifications thereof as will be apparent to 30 one skilled in the art to which the invention appertains.

Reference should be had to the accompanying drawings forming a part of this specification, In which:

. 35 Figure 1 is a transverse section through a rotary pump embodying the invention, a section being taken at right angles to the axis of the pump and through the body of the rotor;

Fig. 2 is a perspective view of the body portion ₄₀ of a pump vane;

Fig. 3 is a perspective view of a sealing shoe with a convex working face for engagement interiorly with a cylindrical surface;

Fig. 4 is a perspective view of a sealing shoe 45 with a concave working face for engagement exteriorly with a cylindrical surface;

Fig. 5 is a diagrammatic view showing the pressures exerted upon the shoes;

Fig. 6 is a diagrammatic view showing the ₅₀ pressures exerted upon the vane;

Fig. 7 is a sectional view showing a pump with a one-piece vane;

Fig· 8 is a perspective view of the one-piece vane shown in Fig. 7;

_M Fig. 9 is a diagrammatic, view showing the effect of centrifugal force on a vane disposed at an angle to the radius;

Fig. 10 is a view similar to Fig. 9 showing the vane oppositely inclined; and

Fig. 11 is a sectional view showing a multivane 5 pump embodying the invention.

An important feature of the present invention is the provision of an effective seal between relatively sliding parts of a rotary pump such as a sliding vane or an oscillatable shoe, and the parts 10 with which the vane or shoe has sliding contact.

In the following description, it is to be understood that by “working face” of a vane or shoe, is meant that face of the vane or shoe which engages with a part of the pump which is rela- 15 tively rotatable with respect to the part which carries the vane or shoe.

The faces of the shoe or vane perpendicular to the axis of rotation, are referred to as “end faces”. ₂₀

The faces of the vane or shoe opposite the working face, are referred to as “bottom faces”.

The side of the shoe or vane disposed transversely to the direction of. rotation and which receives the initial pressure from the fluid being ₂₅pumped, is referred to as “the high pressure side or face”, and the corresponding side of the recess in which the shoe or vane is mounted is referred to as “the high pressure side or face”. The face of a shoe or recess opposite the high pressure side 30 or face is referred to as “the low pressure face or side”. Grooves, channels, recesses, or spaces provided for the purpose of applying and directing pressure^ forces are sometimes referred to herein as “pressure pockets”. _3g

In Figure 1 of the drawings, there is shown a pump housing I enclosing a cylindrical chamber in which there is mounted a rotor 2, the axis 3 of which is disposed eccentrically with respect to the cylindrical housing, the rotor 2 being of ₄₀cylindrical form and of smaller diameter than the chamber in which it is mounted. The rotor is positioned with its periphery in contact with the chamber wall along a longitudinal tangent line to provide a seal between the inlet and outlet ₄₅ports. The rotor 2 has a longitudinal slot 4 in which is slidably mounted the body portion 5 of a sealing vane, the working face of which is provided with an oscillatable shoe 6 having an arcuate convex bottom or seating face 7 which fits _Knin an arcuate recess in the body portion 5.

The shoe t has a convex working face 8, the radius of which corresponds to that of the cylindrical chamber, and which contacts with the wall of the cylindrical chamber. The bottom _w

9,148,887 or seating face 7 of the shoe 6 is of shorter radius than the working face 8 and intersects the working face at opposite sides of the shoe. ,

During operation of the pump the vane con- sisting of the slidable body portion 5 and oscillatable shoe 6 is pressed outwardly towards the cylindrical· wall of the pump chamber, to maintain the working face 8 of the shoe in contact throughout its width and length with the cy₁₀ lindrical wall of the chamber. The vane pro-, vides a partition moving with the rotor to force fluid from the inlet to the outlet of the pump.

In order to provide a more effective seal between the rotor and the chamber wall along the .- line of contact between the rotor and wall, an oscillatable shoe 9 is mounted in a recess in the hanging and this shoe has an arcuate convex bottom or seating face 10 which fits in an arcuate recess in the housing wall, and an arcuate 2o concave working face 11 of the same radius as the rotor which bears against the surface of the rotor. The bottom or seating face J 0 is a shorter radius than the working face i I and intersects the working face at opposite sides of the shoe. 25 The shoe S maintains contact with the rotor to provide a more effective seal between the inlet and outlet.

As shown in Fig. 2 pf the drawings, the body portion 5 of the vane has parallel longitudinal „₀ grooves ί 2 on its low pressure face and longitudinal channels 14 on the high pressure, face thereof. On the high pressure side there is at least one passage 15 which opens at one end to the shoe seating recess and at its opposite end to the bottom of the vane. The passage 15 is intersected by the channels 14 which provide pressure pockets along the high pressure face of the vane for fluid under pressure which acts to press the vane toward the low pressure wall of its recess Or Slot so that the sealing grooves 12 are effective to prevent leakage of fluid from the . bottom of the recess through the space between the low pressure wall of the vane and the adjacent wall of the recess. The ends of the body portion 5 of the vane are provided with diagonal ⁴⁵ grooves or channels i6 which serve to retard leakage past the ends of the vane. The diagonal' - channels 15 also receive fluid under pressure which exerts a force on the vane toward the low _r pressure wall. The grooves or channels 16 aid ' in scavenging to the high pressure side the space between the bottom of the vane and the bottom . of the slot 4 when the vane is retreating into the slot.

As shown in Fig. 3 of the drawings, the shoe ⁵⁵ 6 has longitudinal channels 17 on the high pressure side of its working face 8 a,nd longitudinal channels 18 on the high pressure side of its seating face 7. The channels 17 and 18 are inter₆₀ sected by at least one channel 19 intermediate the.ends of the shoe and disposed at right angles to the channels 17 and 18. The channel 19 is open to the high pressure side of the vane and registers with the passage 15 of the body por₆₅ tion 5 of the Vane to deliver fluid under pressure to-the channels 14 and to the bottom of the slot 4. The grooves or channels 17 and 18 provide pressure, pockets on the high pressure side of the shoe, and the channel 19, which opens to the 70 interior of the pump chamber on the pressure side of the. vane supplies fluid under pressure to these grooves of channels as well as to the passage 15 which conducts fluid under pressure to the channel 14 on the high pressure face of the 75 body portion of the vane and to'the bottom of the slot 4. The shoe 6 also has longitudinal sealing grooves 20 on the low pressure side of the working face 8 and similar grooves 2 i on the low pressure side of the bottom or seating face 7. One or both end faces of the shoe 6 may be pro- 5 vided with transverse sealing grooves 22 to impede the flow between the end face of the shoe and the end walls of the pump chamber. .

Referring to Fig. 4 of the drawings, the shoe 9 has longitudinal channels 24 forming pressure 10 pockets on the high pressure side of its working face II and longitudinal channels 25 forming pressure pockets on the seating face 10 thereof. Channels 24 and 25 are intersected, by at least one channel 26 intermediate the ends of the 15 shoe which extends substantially at right angles to the grooves or channels 24 and 25. The channel 26 opens to the high pressure side of the shoe 9, and conducts fluid under pressure to the pressure pockets formed by /the channels 24 and 20 25. The shoe 9 has longitudinal sealing grooves 27 on the low pressure side of its working face and similar sealing grooves 28 on the low pressure side of its seating face 10.

During operation of the pump fluid/under 25 pressure will be admitted through the channel 19 to the pressure pocket channels IT and 18 of the shoe 6 and through the channel 26 into the pressure pocket channels .24 and 25 of the shoe 9, and the fluid under. pressure in these 30 pockets will exert a thrust on the shoes 6 and 9, pressing them toward the low pressure sides of their recesses. The conductor channels 89 and 26 provide direct passages for fluid to the pressure pockets on the high pressure sides of the 35 shoes so that the fluid in the pockets is subjected . to the pressure of the fluid being pumped at each instant of the pumping cycle.

In Fig. 5 of the drawings, the arrows 29 and 80 indicate the forces applied by the fluid under 40 pressure to the shoes 6 and 9. The force of the fluid under pressure indicated by'the arrows 29. is outwardly of the center of curvature 31 of the bottom or seating face 7 of the shoe 6 and tends to rotate the shoe in a direction to move the 45 leading edge of the shoe inwardly, opposing the frictional drag exerted on the working fa.ce 8. Similarly the fluid pressure on the shoe 9, indicated by the arrows 30, is outwardly of the center of curvature 32 of the bottom or seating ₅θ .face 10 and tends to rotate the shoe in a direction to move the high pressure side thereof into the shoe recess. These forces are transmitted to the faces of the shoes in which the sealing grooves are located, as indicated by the arrows 37, 38, 39 55 and 40, the pressure on the shoes being commensurate with the pressure under which the vane is working. It should be noted that the low pressure side of the sealing shoe 6 is wedgeshaped so that the shoe Is pressed against the 60 wall of the housing, as indicated by the arrows 38, and against the recess wall, as indicated by the arrows 37, so that the sealing grooves in these _vspaces can effectively impede the leakage of fluid past the shoe. Similarly, the low pressure side 65 of the shoe 9 is, wedge-shaped, so' that the surfaces in which the sealing grooves are located are pressed against the rotor anti the recess wall, as indicated by th,e arrows 39 and 40.

It will be observed that the high pressure side 70 of the recess in which the shoe 9 is mounted,•opens to the pump chamber at or near the line where the rotor 2 contacts with the wall of the housing, so that as the shoe 8 comes into contact with the shoe 9 the working faces of both sub- 75

2,149,337 stantially coincide with the contact line and since the fluid pressure acting on the two shoes tends to move the high pressure side of the shoe 6 inwardly and the high pressure side of the shoe 9 . 5 outwardly, a clearance is provided between the opposed sharp edges of the shoes and there is no interference to the passage in the shoe 6 past the shoe 9.

Figure 6 of the drawings Illustrates diagram10 matically the forces acting upon a vane. The arrow 42 represehts the direction and amount of pressure due to the film of fluid between the face of the rotor chamber and the face of the vane. The arrow 43 represents the force due to the 15 working pressure against the bottom of thevane of the fluid admitted to the bottom of the slot 4. _r The forces 42 and 43 are normally equal and opposed and are equalized. The arrow 44 represents the force of a spring commensurate with 20 operating conditions, such a spring being used where the speed of rotation and delivery pressure and physical properties of fluid being pumped are such that a force, in addition to the centrifugal force and that of fluid pressure is desirable. 25 The arrow 45 represents the added force en, countered when; the vane is receding into its slot and scavenging the chamber at the bottom of the slot. This force is a valuable factor as it adds to the pressure making the seal at the 30 working face of the vane during a portion of rotation in which the fluid is being compressed or delivered.

It will be noted that the vane of the present invention adds to the. efficiency and capacity of 35 the pump, since it acts as a piston pump, causing the fluid which has filled the chamber at the bottom of the slot 4 during the outward movement of the vane to be discharged against a higher pressure at the delivery side of the vane 40 during the retreating movement of the vane.

The arrow 46 represents a force due to friction. The arrow 4 Ί represents a force at the point of application due to the pressure of the load. The arrow 48 represents the resultant of 46 and 47 45 at its point of application.

In the usual vane pump the force 48 is opposed by a force, indicated by the arrow 49, at a fulcrum point formed by the edge of the slot 4 on the low pressure side thereof. A force, indicated by the 50 arrow 50, is also exerted against the bottom comer of the vane on the high pressure side _ thereof. The forces 48 and 50 balanced again. the fulcrum point 40 tend to cant the vane in its slot, creating localized pressures, at the-points of 55 application of the forces 49 and 60, which are the cause of rapid wear of the vane and slot and quick ' deterioration In efficiency of operation.

The present invention provides means for more advantageously distributing the forces acting on 60 the vane so as to increase the efficiency and reduce wear on the sliding parts. The arrow 51 represents the force exerted on the vane by the fluid under pressure in the pressure pocket channels 14. The , pressure, indicated by the arrow 65 51, is more than sufficient to eliminate the pressure 80 of the bottom comer of the vane against the high pressure wall, and distributes the pressure of the vane over the low pressure wall of the slot so as to eliminate the fulcrumlng pressure 70 indicated by th® arrow 48. The wear is thusdistributed over the surfaces of the vane and slot walls and the force balancing the pressures 51 and 40 may be represented by the arrow 52 a substantial distance inwardly of the point about 75 which the vane would normally fulcrum.

The arrow 53 represents the resultant of forces indicated by the arrows 42, 43, 44 and 45 acting longitudinally of the vane. The center of weight of the vane is indicated at 54 and the arrow 55 represents the centrifugal force derived there- 5 from, and, this force is also exerted radially. Variations, in dimensions and speed of rotation alter the force 55.

The principle of the present invention is applicable to pumps operating at high speed or 10 at low speed, and for pumping gases or liquids. Obviously, the forces 42, 43, 44 and 45 may be controlled to meet the requirement , of the individual pump to provide, in conjunction with the centrifugal force, the radial pressure desired. 15

In Figs. 7 and 8 of the drawings, there is here shown a rotary pump employing a one-piece vane. This pump has a housing 70 and a rotor 71 within the housing which carries a sliding vane 72 mounted in a slot 73'in the rotor. The 20 vane 72 has a convex working face 74 which is provided with longitudinal sealing grooves 76 on the low pressure face thereof and with pressure pocket channels 77 extending longitudinally of the high pressure face near the bottom 25 thereof. A passage 78 adjacent the high pressure face of the vane extends from the working face 74 to the bottom of the vane and intersects each of the channels 77. The upper end of the passage 78 has a lateral opening 79 to the high 30 pressure face of the vane so that fluid under pressure passes through the passage 78 to each of the pressure pocket channels 77 and to the space at the bottom of the slot between the bottom of the slot and the bottom face of the vane 35 so that, during operation of the pump, lateral pressure is applied to the high pressure face of the vane near the bottom edge thereof, and radial pressure is also applied to the bottom face of the vane to force the same outwardly against 40 the wall of the pump chamber. Diagonal grooves 80 are provided on the ends of the vane to impede leakage of fluid past the ends of the vane between the ends of the vane and the end walls of the pump chamber, the grooves 00 also serv- 45 mg to apply an additional lateral thrust to the vane and to facilitate the escape of fluid from the bottom of the slot'during the receding movement of the vane to the high pressure side.

_ In some pumps it may: be desirable to modify the action of centrifugal force Upon the vane by disposing the slots, in which the varies slide at an angle to the radius. If it is desired to reduce the high frictional resistance due to the load or speed of rotation, or both, the vane may be placed 55 as shown diagrammatically in Fig. 9, with its working face advanced relative to the direction °i “^ta«^on· The force 05 representing the thrust of the fluid being pumped in a direction perpendicular to a radius is shown resolved into its eo components, 86 and 87, component 86 being perpendicular to the vane, and component .87 acting inwardly in a direction of movement of the vane. The centrifugal force 55 at the center of. weight 54 is shown resolved into its compo- «5 nents 88 and 80, component 88 acting perpendicular to the vane, and component 89 acting outwardly. , , ⁶ ·

The components 87 and 80 act in the same line but in opposite directions. They must be 70 subtracted, and the resultant outward force which causes frictional resistance is reduced, as desired, by the degree of the angle at which the vane is placed, Also, it is obvious that a resultant of forces 86 and 88 may be found per- 75

3,149,887 ments and provided with a face engaging the surface of a relatively rotatable element, and substantially conforming to said surface to maintain a seal between high pressure and low pressure portions of the pump chamber, said sealing mem- 5 ber and said recess in which it is mounted being shaped to provide spaced pressure pockets between the member and its recess at the high pressure and under sides of said member, said sealing member and its recess having bearing surfaces 10 extending the full length of said member and in sliding and sealing engagement on the low pressure side thereof, said sealing member having a passage for fluid under pressure opening at one end to the pump chamber on the high pressure 15 side of said member and communicating with said pockets to maintain a fluid pressure therein substantially the same as in the high pressure portion of the pump chamber to press said member against the relatively rotatable element and 20 against the low pressure side of its recess.

2. In a pump of the rotary piston type having relatively rotatable elements forming walls of the pump chamber, and a movable sealing member having a sliding fit in a recess of one of said 25 elements and provided with a face engaging the surface of a relatively rotatable element and substantially conforming to said surface to maintain · a seal between high pressure and low pressure portions of the pump chamber, said member hav- 30 ing parallel sealing grooved (extending throughout its length in the face thereof which engages the relatively rotatable element and also in the face thereof which engages the wail of the recess on the-low pressure side, said sealing mem- 35 ber and said recess in which it is mounted being shaped to provide spaced pressure pockets between the member and its recess at the high pressure and under sides of; said member, said sealing member and its recess having bearing surfaces 40 extending the full length of said member and in sliding and sealing engagement on the low pressure side thereof, said sealing member having a passage for fluid under pressure opening at one end to the pump chamber on the high pressure 45 side of said member and communicating with said pockets to maintain a fluid pressure therein substantially the same as in the high pressure portion of the pump chamber to press said member against the relatively rotatable element and 50 against the low pressure side of its recess.

3. A pump of the rotary piston type having relatively rotatable elements forming walls of the pump chamber, a member slidably mounted in a recess of one element and engaging the surface 55 of a relatively rotatable element and substan-* tially conforming to said surface to maintain a * seal between high pressure and low pressure portions of the pump chamber, said member having sealing grooves in the faces thereof which engage 60 the relatively rotatable element and the wall of the recess on the low pressure side, said member having longitudinal channels in the face thereof which, engages the recess wall, on the high pressure side and a passage communicating with said 65 channels and opening to the pump chamber on the high pressure side of said member. ·

4. A pump of the rotary piston type having relatively rotatable elements forming walls of a pump; chamber, one of said elements having a 70 slot, vane in said slot for maintaining a seal between high pressure andlow pressure portions of the pump chamber, said vane comprising a body portion slidable in said slot and having an arcuate recess and a shoe having an arcuate face 7«· pendicular to the radius and that it will be less than the corresponding resultant on the radial vane illustrated in Fig. 6. Since this force perpendicular to the radius is a measure of the 5 torque, it is apparent that less power will be required to operate a pump having its vane or vanes inclined as shown in Fig. 9. , ' The force 88 is added to the force 5β which holds the vane against the low pressure wall of 10 its recess surface to surface, due to the fact that the center of weight is transferred from a position on the high pressure side to a position on the low pressure side of a radial line passing through the fulcrum O.

In Fig. 10 of the drawings the angularity of the vane is the reverse of that shown in Fig. 9, the thrust of the fluid being pumped which is indicated by the arrow 85» being resolved into components 86» and 87» and the centrifugal force 20 at the center of weight indicated by the arrow 55 being resolved into components 88» and 89». In this case the components 87» and 89» in the direction of movement of the vane are not opposed as in Fig. 9 but act in the same direction 25 and their resultant is their sum instead of their difference.

It is to be understood that the pressure pockets at the high pressure sides of the vane and shoe and the passages for conducting fluid from 30 the pump chamber to such pockets may be formed in various ways, it being essential only that such pockets and passages be so disposed as to cause the fluid to exert an effective pressure against the grooved sealing faces.

₃₅ In Fig. 11 of the drawings there is shown a multi-vane pump having a casing 92 with a cylindrical chamber 93, a rotor 94 disposed eccentrically of the chamber and having a series of vanes 95 which are mounted in slots 96 in the 40 rotor which are disposed, at an angle to radii of the rotor. The casing and vane are provided with shoes 97 and 98 which may be of the same construction as the shoes 6 and 9 previously described. The shoe 98 may be wider than the .r vane in which case the rotor has recesses 99 at ^J the high pressure sides of its slots to accommodate the shoes. The vanes 95 have their inner ends tapered, providing an Inclined face 8 CO which is subjected to fluid pressure which, acts to press the vane against the low pressure wall ^s of its slot. The inclined face 100 provides a • pressure pocket on the high pressure side of the vane which Is in communication at all times with the bottom of the slot to which fluid under pres55 sure is conducted by channels or passages as in the modifications previously described.

' It will be apparent that the present invention provides a simple construction in which the various forces acting on the. vanes and shoes θθ are advantageously distributed to lessen sliding friction and wear on the parts and to provide an effective seal. - >

Furthermore, it is to be understood that the particular form of apparatus shown and de05' scribed, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in 70 the appended claims.