US2852183A

US2852183A - Rotary multi-vane positive displacement pump

Info

Publication number: US2852183A
Application number: US526032A
Authority: US
Inventors: Edward C Breinig; Edward V Manning
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1955-08-02
Filing date: 1955-08-02
Publication date: 1958-09-16
Anticipated expiration: 1975-09-16

Description

P 1958 E. c. BREINIG ET AL 2,852,183 I ROTARY MULTI-VANE POSITIVE DISPLACEMENT PUMP Filed Aug. 2, 1955 3 Sheets-Sheet 1 FIG. 1

INVENTORS EDWARD C. BRE/N/G E DWA/PD l/ MANN/N6 AITO Q/VE Y Sept, 16,.1958 E. c. BREINIG ETAL ,3

- ROTARY MULTI-VANE POSITIVE DISPLACEMENT PUMP Filed Aug. 2, 1955 5 Sheets-Sheet 2 FIG. 3

OUT

IN VEN TORS EDWARD C. BRE/N/G EDWARD 1 MANN/N6 Mme/mew P 6, 1958 E. c. BREIN'IG .ETAL 2,852,183

ROTARY MULTI-VANE POSITIVE DISPLACEMENT PUMP Filed Aug. 2, 1955 3 Sheets-Sheet 3 FIG. 4

IN VEN TORS EDWARD CBQE/N/G EDMMRD l4 MANN/N6 Unite 2,852,183 RQTARY MULTLVANEfiPQSI -IIYE'. DISPLACEMENT 2 Claims. Cl; 230-152 invention relates to an improved rotary multivane posinveidisplacement pump and more: particularly to a novel means and arrangement for precompressing a gaseousrmedium, such as air, within a cavity in the housingzof'thezpump toa pressure'approaching a value equal to-the' outlet line pressure and including the further feature' ofproviding' positive-vane sealing bet-'weenthe pump inlet: and outlet ports;

Conventionalimultiwane pumps of this general type consistessentially of acentrally'located radially slotted rotor tittedw with slidingvanes whichmake contact with an? internal eccentric housing cavity In such: pumps ofconventional design, the charge of gaseous'medium or air trapped between the vanes at' thezin'stanttof inlet cut- :ofi remains at. substantially the same low inlet: pressure the instant of dischargeopeningz. At. the instant: of discharge opening, the trapped charge of gaseonsmedium or an, 111' a very short amount of time; must, in; such a conventional type pump without built-.in.precompression, havens pressure increasedto the relatively hi'ghtdischarge pressure; Thisraise inpressure-i's. accomplished chiefly by the reverse flow of previously dischargedi gaseous.;me'- drum. or air with only a small gain: inpressureresulting fnomr the vane movement.

One method which has been used'in-an attempt to preventithis. reverse flow is the utilization: of a: reed-type valvevor, a spring bias valve in the discharge port; These valves are intended to seal cit the reverse flow and. to prevent the release of thergaseouslmedium or air to be discharged from. the pump cavity until some predetermined. amount of. pressure increase has occurred. The major disadvantage, relative to the use of such valves, is the difi'iculty in constructing, valves ofv sufliciently high response rates so as to be suitable for use withhigh .speed multievane pumps. In addition, any valveswhich might be employed must necessarily utilize moving parts whichv are subjected to breakage or wear during operation,

object'of the invention is to avoid the disadvantages.

incident to the use-of such valves by the provision oof'ta rotary multi-vane positive displacementpump in which the vane elements cooperate in. a non-symmetrical pump cavity so as tovadiabatically compress a gaseous medium or air drawn through an inlet into such cavity to a pressure value sufficiently great as to prevent a back rush of such gaseous medium upon the vane elements opening the cavity to an' outlet conduit; leading from the cavity; Another object of'the invention isto provide a novel rotary multi-vane" positive displacement pump having a pump cavity of such design that the vane elements cooperate to precompress the gaseous medium or air therein prior to'its discharge so'as'to' approach or'attain apressure substantially equalt-o the discharge line pressure;

Another object; of the inventionis to provide a novel rotary multi-vane positive displacement pump in which thevanes are arranged tocooperate in a pump cavity of non-symmetrical contour and in which the cavity is so designed as to progressively decrease in volume from the tates Patent" M 2, inlet to the outlet so as to-provide; precompression upon rotation of the pump and are ratio that will'provide maximum efficiency under preselected operating condi tions or within a preselected range of conditions.

Another objectof'the invention is to provide a novel rotary multi-vane positive displacement pump in which the vanes acting under centrifugal force aresoarra iged as to provide during rotation of theipump positive vane sealing between inlet and outlet ports of. the pump,,at least one vane being in contact with the-cavity contour to prevent air flow between the portsat all times so as Y batically compressing-a gaseous medihm,. sucli as air,,' andcontrolling the release of saidcompressed mediiim through an exhaust conduit without the use of'. spring biased valve means having wearingypar-ts. which may readily become worn in operations Afurther objectof the invention is to provide a corn.- pact ain pump of great efliciency in comparison. to. size and of such simplicity,- intconstr-uctionras to adapt it for manufacture and installation. atlow cost.

Other objects and advantages ,of this invention are set forth in the following. description, taken. with. the HQCQIII: panying drawings; and the novel features thereof are pointed". out: in the: appended claims The disclosure, however, is. illustrative only and We may make changes in detail, especially inmattersofshape, size and arrangement of parts within the principle of theiinvention-to the full extent indicated by the broad: and-general, meanings of the terms in which the appended=claims are expressed;

In the accompanying drawings which form a part of this specification, like characters of reference indicate like parts in the several: views wherein:

Figure. 1 is a: fragmentary side'view, ,partiai1y in-sec; tion, of a rotarymulti-vane'positive displacement pump embodying the novel features ofthepresent invent on;

Figure 2 is' a sectional end view of Figure l taken along the lines 2-2 andrshowing the relationship of the rotor and vane assembly'inthe pump cavity;

Figure 3 is-a diagrammaticview illustrating (the manner in which the gaseous medium or'air. entering; through the pump inlet is entrapped between vanesof: theepump, at substantially the same pressureasthat entering. the v inlet port of the pump;

Figure'4 is-a diagrammatic view/illustratingrthe manner in which the air entrapped in the: pump cavity: may be: compressed between the pump vanes and the decreasing contour of the pump chamber, andlalsoshowingbyfdotted lines that there is providedza minimum of. at least one; vane in: contact with the cavity contour betweens the; inlet: and outlet ports at all. times-L so as to prevent lea-leageofi the relatively high pressure air from the discharge.port back to the inlet port;

Figure 5 is an enlarged perspective "view of arpump,

vane.

Referring to the drawing ofvFigure 1, there is shown a rotary air pump including a power unit- 10-and-a pump ing; assembly 11 constructed and arranged to bernounted and driven by the power unit 10.v v I In the present invention the power unit 10 comprises an electric motor 12 suitably mounted and enclosed within a hollow housing or casing 13, an end wall 14 closing one end of the housin'g13; while the air pump unitlll is suitably fastened to an opposite end wall 15 or housing 13 by'bolts 16.

The pump assembly 11 comprises a casing 17 and a head wall 18. Head wall 18 is secured to the casing 17 and the end wall 15 of the casing 13 by the bolts 16 which pass through tubular openings in the head 18 and casing 17 and screw-threadedly engaged in the wall 15.

Motor 12 is provided with a shaft 21 rotatably mounted in bearings 23 and 25 carried by the end wall 15 and the head 18, respectively. Secured to the shaft 21 by keys 27 for rotation therewith is a cylindrical rotor member 28. End plates 29 and 30 are provided in the end wall 15 and head 18, respectively to sealingly engage the side of the rotor member 28 and

rotor vanes

32, 33 and 34 slidably mounted therein, as best shown in Figure 2.

The rotor 28 has formed therein suitable

longitudinal slots

36, 37 and 38 each extending, as indicated in Figure 3, tangent to a circle Z having a common center to that of the rotor 28 and, as shown in Figure 2, in spaced relation to and in a plane at one side of the. shaft 21 and center of rotation of the member 28. 'Slidably mounted in the

slots

36, 37 and 38 and extending from the rotor member 28 at an acute angle to the circumferential surface thereof and in a direction corresponding to the direction of rotation of member 28 are the

vanes

32, 33 and 34, respectively. The outer edges of the vanes make contact with a profile of a pump cavity or chamber'of oval cross-section formed within the casing 17 and act to seal at all times the pump inlet 40 from the pump outlet 42 so as to prevent back rush of high pressure gaseous medium from the outlet to the inlet through the pump cavity, as shown diagrammatically by Figures 3 and 4. It is to be noted that about one half of rotor is uniformly closely-spaced to one end of the oval-shaped cavity and that a compression chamber of extended crescent crossseetion results.

Further, the profile of the cavity has a predetermined contour so designed as to progressively decrease the volume of a portion 39 of the cavity between the inlet 40 and the outlet 42 so that upon rotation of the element 28 gaseous medium drawn into the portion 39 may be entrapped between

successivevanes

32, 33 and 34 and precompressed prior to release of the gaseous medium through outlet 42. p

The contact between the vanes and the profile of the cavity within the casing 17 is maintained by the radial component of the centrifugal force acting on the vanes during rotation of the rotor element 28 so as to maintain the outer edges of the vanes in contacting relation with the profile of the cavity Without excessive friction and load at high speeds of rotation, as distinguished from vanes of the true radially extending type in which the centrifugal force applied at high speeds may cause an excessive Wear, friction and load to be applied to the outer edges of the vanes increasing with the speed of rotation.

Thus, as the shaft 21 is rotated, gaseous medium such as air may be drawn into the pump cavity and between the vanes, such as 32 and 33, through the pump inlet port, indicated in Figure 2 by the numeral 40, and thereby precompressed and finally delivered to the pump outlet port 42 under the compression force thereof. It is to be noted that the inlet and outlet are opposite each other and in alignment. The oval-shaped pump cavity has its major axis at about a forty-five degree angle to this line of alignment.

Referring to the diagrammatic drawing of Figure 3, a charge of air or gaseous medium is entrapped in the portion 39 of the cavity between the

vanes

32 and 33 at substantially the same pressure as that entering the inlet port 40 so as to occupy a volume designated in the drawing of Figure 3 by the letter X. 7

Now referring to the drawing of Figure 4, it will be seen that the gaseous medium or air charge between

vanes

32 and 33, and indicated by the letter Y, has now been rotated to a location just prior to its discharge through outlet port 42 and, because of the predetermined nonsymmetrical profile of the portion 39 of the pump cavity of progressively decreasing volume, the charge of gaseous medium Y has now been compressed between the

vanes

32 and 33 with a consequent increase in pressure. Theoretically, the charge between the

vanes

32 and 33 has been precompressed adiabatically in accordance with a predetermined relationship.

Again referring to the schematic drawing of Figure 4, it can be seen that the relationship of the distance between the inlet port 40 and the outlet port 42 and the distance between any two vanes (indicated by dotted lines in Figure 4) is arranged to provide a minimum of at least one vane in contact with the contour of the pump cavity between the

ports

40 and 42 at all times. The importance of this feature is to prevent a direct leak of relatively high pressure air from the discharge port 42 back to the inlet port 40 without the necessity of maintaining any rubbing contact by the rotor 28 and the nonsymmetrical cavity surface and, further, without the necessity of maintaining even a critically close clearance between the surfaces of the rotor and housing cavity.

Under our present invention, the gaseous medium or air is squeezed or compressed between vanes of the rotor moving in the portion 39 of the pump cavity prior to the discharge of the air or gaseous medium through the exhaust conduit 42. This is shown by Figures 3 and 4 wherein the air or gaseous medium between the

vanes

32 and 33 of the rotor 28 is shown in the process of being compressed. Since the volume of the portion 39 of the pump cavity progressively decreases in volume from the inlet 40 to the outlet 42, it will be seen that prior to release, the pressure of the gaseous medium or air compressed through the above means is increased to such a degree that upon release of the same, as shown in Figure 4, by the dotted line vane 33, there is no backing up or back rush of air, instead the compressed gaseous medium carried in the cavity space 39 separating the

vanes

32 and 33 passes directly out the exhaust conduit 42 under the compression force thereof. 7

Through the use of built-in precompression in a pump of the type described herein, there is provided a pump with relatively constant input torque or power requirements so as to make these pumps ideally suited for use with various driving means, particularly when used under a wide range of operating conditions.

There may be further provided in the subject pump a vane structure and arrangement such as disclosed and claimed in a copending application Serial No. 525,846, filed August 2, 1955, by Walter L. Cable and assigned to Bendix Aviation Corporation, assignee of the present application.

As described in the last-mentioned application, the

vanes

32, 33 and 34 are formed of carbon or other suitable material and, as shown in Figure 5, have provided a series of longitudinal holes 50 having openings 52 in the bottom surface of the vane facing the inner end 1 of the rotor slot in which the vane is slidably fitted, as

indicated in Figure 2, with a close tolerance between the surfaces of the slot and vane to maintain a minimum leakage path between the slot and vane surfaces.

Upon rotation of the rotor 28, each of the vanes 32,

'- 33 and 34 is forced outwardly into contacting relation with the inner surface of the pump housing causing an increase in the volume of the space at the bottom of the slot between the end of the vane and the inner end of the slot as the vane under centrifugal force moves to its outermost position, as indicated in Figure 4 for example tion, a suction would be created under the vane which would tend to retard a conventional solid type vane from moving out and properly contacting the inner pump housing surface. Such lack of proper contact of the solid type vane would result in a loss in pumping or volumetric eiiiciency due to leakage in the pumped air between the vane tip and the profile of the pump cavity in the pump housing.

However, by designing a relief section or volume into the vane by the provision of the holes 50, this suction effect can be minimized. Thus, in effect, the volume built into the vane acts as a variable rate spring which can adjust itself to particular inlet and outlet conditions of operation. This phenomena is particularly efiective under low flow conditions in which high pump suction is desired, since it allows a greater efliciency of operation under such conditions than that achieved in a pump of the aforenoted type having conventional type vanes lacking the relief section or excess volume provision.

The advantages of the arrangement with the vane structure illustrated at Figure 5 resides in the fact that such vane structure in minimizing the suction effect on the vanes gives to the pump (1) a much higher flow characteristic under particular operation conditions, (2) a higher pump suction under no flow conditions, and (3) less vane wear due to the decrease in weight obtained by including the relief section or excess volume in the vane itself.

From the foregoing, it will be seen that there has been provided a simple, eflicient and improved rotary multivane positive displacement pump so arranged as to adiabatically compress a gaseous medium such as air therein and without use of spring biased valve means having wearing parts that may become worn in operation.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

l. A rotary multi-vane positive displacement gas pump comprised of a housing having a central smooth-walled cavity of oval cross section, a cylindrical rotor member rotatably mounted in said cavity; said cylindrical rotor member and said oval-shaped cavity being constructed and arranged so that about one half of the cylindrical surface of said rotor member is uniformly closely-spaced to the surface of one end of said oval-shaped cavity and so that an extended crescent-like compression chamber is formed; an inlet opening into one end of said compression chamber; an outlet opposite said inlet opening and connected, adjacent but spaced from the other end of said chamber, to the space between said rotor member and the surface of said cavity where closely-spaced; three equispaced longitudinal slots in said rotor member; each of said slots extending tangentially to a circle having a center common to said rotor; and three vanes slidably mounted in said slots and extending from the rotor member at an acute angle to the circumferential surface of the rotor member and in a direction corresponding to the direction of rotation of the member, said vanes being free to slide inwardly and under centrifugal force; whereby, upon rotation of said member, the edge surfaces of said vanes, under centrifugal force acting upon said vanes, continuously contact the surface of the cavity and hence continuously seal the outlet from the inlet after compressing gas in said crescent-like chamber.

2. A rotary multi-vane positive displacement gas pump comprised of a housing having an inlet, a smooth-walled central cavity, and an outlet; a cylindrical rotor member rotatably mounted in said cavity; said inlet and said outlet being opposite each other and in alignment; said rotor member having its axis of rotation perpendicular to the line of alignment between said inlet and said outlet; said central cavity being of oval cross section and having its major axis at about a forty-five degree angle to the line of alignment between said inlet and said outlet; said cylindrical rotor member and said oval-shaped cavity being constructed and arranged so that about one half of the cylindrical surface of said rotor member is uniformly closely-spaced to the surface of one end of said ovalshaped cavity and so that an extended crescent-like compression chamber is formed; said inlet being connected to one end of said chamber; said outlet opening into the the space between said rotor and the surface of said cavity where closely-spaced and adjacent to, but spaced from, the other end of said chamber; three equi-spaced longitudinal slots in said rotor member; each of said slots extending tangentially to a circle having a center common to said rotor; and three vanes slidably mounted in said slots and extending from the rotor member at an acute angle to the circumferential surface of the rotor member and in a direction corresponding to the direction of rotation of the member, said vanes being free to slide inwardly and under centrifugal force; whereby, upon rotation of said member, the edge surfaces of said vanes, under centrifugal force acting upon said vanes, continuously contact the surface of the cavity and hence continuously seal the outlet from the inlet after compressing gas in said crescent-like chamber.

References Cited in the file of this patent UNITED STATES PATENTS 1,651,336 Wissler Nov. 29, 1927 1,722,616 Williams July 30, 1929 1,897,547 Buenger Feb. 14, 1933 1,984,365 English Dec. 18, 1934 2,057,381 Kenney et al. Oct. 13, 1936 2,094,323 Kenney et al Sept. 28, 1937 FOREIGN PATENTS 310,980 Germany Feb. 13, 1939 555,113 France Mar. 16, 1923 919,280 France Nov. 18, 1946