US2703675A - Rotary pump - Google Patents

Description

March 8, 1955 J. P. JOHNSON 2,703,675

ROTARY PUMP Filed Dec. 14, 1950 2 Sheets-Sheet 1 INVENTOR. JAM Es P. Jol-1 NsoN,

? TORAZEYS.

March 8, 1955 J. P. JOHNSON ROTARY PUMP Filed Dec. 14, 195o 2 Sheets-Sheet 2 106 107 115 114 102 darf-- Y H6 126 124 123 "J la M5 134- I- 41.9131 12T- d u 137 hln I 40 *I* ,T146 f 128-L 1 uw nu 'hh 125` l. 1.1 121 i E hlm' 121 120 112/ INVENTOR. JAM E5 P. JOH NSON ATTORNEYS.

United States Patent O" ROTARY PUMP James P. Johnson, Shaker Heights, Ohio Application December 14, 1950, Serial No. 200,724

2 Claims. (Cl. 230-176) The present invention relates generally, as indicated, to a rotary pump and is capable of high speed operation for pumping fluids such as dry air or other gases which do not lubricate the pump parts, such operation of the present pump being attained Without necessity of applying oil or grease to the pump parts or of using lubricant-irnpregnated parts.

Accordingly, one principal object of this invention is to provide a simple form of rotary pump which is designed for high speed operation but yet has relatively large slowly moving displacement cavity-forming members whereby the relatively rapidly moving surfaces of the pump parts may be out of sliding contact with each other so as not to generate excessive frictional heat.

nor to require lubrication.

Another object of this invention is to provide a rotary pump in which a high speed rotor is supported out of contact with the surrounding casing and has therein a relatively large transversely reciprocating piston which is reciprocated a relatively short distance only once for each revolution of the rotor thereby effecting a substantial reduction in the speed of relative sliding as compared with the tip speed of vanes as in an ordinary vane type pump.

Another object of this invention is to provide a pump in which the piston is made of carbon, graphite or like self-lubricating material which may be closely, slidably fitted with metal parts without requiring lubrication of the sliding surfaces.

Other objects and advantages will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

Fig. 1 is a longitudinal cross section view of one form of pump taken substantially along the line 1-1, Fig. 2;

Fig. 2 is a transverse cross section view taken substantially along the line 2 2, Fig. 1,

Fig. 3 is a cross section view similar to Fig. l except illustrating a modication, the section of Fig. 3 having been taken substantially along the line 3-3, Fig. 4; and

Fig. 4 is a transverse cross section view of the Fig. 3 modification, such section having been substantially along the line 4-4, Fig. 3.

Referring now more specifically to the drawing and first to the form of the invention illustrated in Figs. l and 2, the pump therein shown comprises a casing 1 and a coverplate 2 defining therebetween a cylindrical pump chamber 4 which includes a cylindrical wall 5 and parallel end walls 6 and 7. The cylindrical wall 5 of said chamber 4 is recessed as at 8 and 9 at circumferentially spaced points for communication with the intake and discharge ports 10 and 11 respectively.

Said casing 1 is additionally formed with a bearing housing or extension 12 providing a mounting flange 13 for the pump, said extension being counterbored to receive ball or like anti-friction bearings 14-14 therein. The outer races of said bearings 14-14 are clamped in place with a spacer 15 therebetween by means of a ring 16 which has threaded engagement in the outer end of said extension 12. The inner races of said bearings more particularly to a pump which' 14--14 are similarly clamped with a spacer 17 therebetween as by means of a nut 18 threaded onto the end of the rotor drive shaft 19.

'I'he coverplate 2 also has a bearing housing or extension 20 which is disposed eccentrically with respect to the extension 12 and mounting bearings 21-21 therein with spacers 23 and 24 disposed between the outer and inner races and respectively held in place by endplate 25 which is secured to the end of said extension 20 with screws 26 and by a snap ring 27 engaged in a groove around the coupling member end portion 28.

The rotor drive shaft 19 has pinned thereto at 30 a splined drive member 31 and integral with said shaft 19 is a cylindrical rotor 32, said rotor 32 being formed with a cylindrical outer surface in close proximity to the cylindrical wall 5 but out of contact therewith and opposite end walls held in spaced relation to the walls 6 and 7 by means of a washer 34 interposed between said rotor and the inner race of the adjacent bearing 14. Therefore, the bearings 14-14 not only serve to rotatably support the rotor 32 in the pump casing 1 but additionally serve to support said rotor completely out of sliding or rubbing contact with the pump chamber walls 5, 6 and 7 whereby said rotor may be driven at any desired high speed and the pump may be employed for pumping fluids of the character indicated which do not have lubricating properties. Such high speed operation does not therefore result in generation of excessive frictional heat and, moreover, because of the relatively large areas of the rotor 32 which are in close proximity to the pump casing wall 5 there is no objectionable bypass of fluid during the operation of the pump at such high speeds.

Said rotor 32 is formed with a rectangular cross section opening 35 transversely therethrough, the opposite ends of said opening being adapted to successively pass the recesses 8 and 9 during rotation of said rotor. Sa'id rotor is provided with an axial opening 36 through which the coupling member end portion 28 and the washer 37 on the latter extend.

Transversely slidably fitted within opening 35 in said rotor 32 is a piston 38 of cross section complementary with the cross section of the opening 35, said piston preferably being made from a block of carbon or like non-metallic material which does not require lubrication for sliding with respect to the rotor 32. Said rotor 32 is preferably made of steel or like metal. As best shown in Fig. 2, said piston 38 has opposed cylindrical faces which are preferably of radius equal to that of rotor 32 but spaced apart a distance less than the diameter of rotor 32 so as to be capable-of transverse sliding as aforesaid. Said piston 38 in addition is formed with a rectangular cross section opening 39 extending axially therethrough.

The coupling end portion member 28 has an integral tongue 40 thereon of rectangular cross section extending into the opening 39 of said piston 38 and arranged to slide transversely in such opening 39 along a path angularly related (perpendicular as shown herein) to the path of sliding of the piston 38 in said rotor 32. Accordingly, the tongue 40 is non-rotatable with respect to the piston 38 and similarly the piston 38 is non-rotatable with respect to the rotor 32.

It will now be evident from Fig. 2 that when the rotor 32 is rotated in the direction of the arrow, fluid will be drawn through port 10 and recess 8 into the displacement cavity formed between the lefthand end of piston 38 and the portion of the rectangular opening 35 between the end of said piston and the cylindrical wall 5 of the pump chamber 4 and similarly fluid from the displacement cavity at the righthand end of said piston 38 will be discharged through the recess 9 and port 11. In the case of compressible fluids recess 9 will preferably be of less circumferential extent than recess 8 whereby the uid will be precompressed to the desired extent before being discharged into the recess 9 and port 11. In Fig. 2 the rotor 32 is shown with piston 38 in its mid-position, the piston 38 moving toward the right as the rotor turns in a clockwise direction to cause displacement of fluid in the manner aforesaid.

The opening 35 in rotor 32 is of relatively large size so as to effect a comparatively large displacement. However, the remaining cylindrical lands between the opposite ends of such opening extend circumferentially nearly 90 whereby, even though a substantial clearance of several thousandths of an inch, for example, is provided between the outer surface of rotor 32 and cylindrical wall 5, no appreciable leakage or bypass will occur. Such efficient operation is attributed to the relatively large areas of the cylindrical lands of the rotor 32 as compared with ordinary vane type pumps wherein the vanes and casing have only a line contact or, at the most, a very narrow surface contact with each other. The substantial clearance provides in the present construction avoids generation of excessive frictional heat and eliminates the necessity of lubrication when fluids such as dry air and other gases are pumped. The clearance between the end walls of rotor 32 and t'ne end walls 6 and 7 of the pump chamber 4 may be any desired amount so long as a substantial axial overlap is maintained between the rotor 32 and the recesses 8 and 9 as best shown in Fig. l.

The present improvements provide a pump which is of simple construction with only three closely fitted sliding parts, viz. the sliding of piston 38 in rotor 32 and on the coupling member tongue 40. Said piston 38 is the intermediate one of such parts and the making of said one part of carbon or like material takes care of all of the sliding friction in the pump. The bearings 14--14 and 21-21 provide a sturdy, accurate support for the rotor 32 and for the coupling member 40 so that there is no binding of these parts and so that the rotor 32 is held out of contact with the pump chamber walls 5, 6 and 7.

A pump constructed in accordance with this invention may be operated at high speeds and in one example, the pump chamber wall was made approximately 6" in diameter and the opening 35 in the rotor was approximately 4 square, and there was provided a 1/2 eccentricity between the axes of the coupling member 40 and the rotor 32. With this particular pump, there was but two inches of sliding movement of the piston 38 in the rotor 32 for each full revolution of the rotor whereas in a vane type pump of comparable size and operated at a speed of 4,000 R. P. M., for example, the speed of sliding of the vane tips along the pump chamber wall is in excess of 6,000 feet per minute thereby generating substantial frictional heat and requiring lubrication By way of comparison, the piston 38 in the foregoing example has an average speed of sliding of only about 666 feet per minute when the rotor is rotated at 4,000 R. P. M. This particular pump was designed to supply dry air at relatively low pressures of 5 to 25 pounds per square inch 'and at a rate in excess of 60 cubic feet per minute for inating rescue pontoons and the like.

Although the pump illustrated in Figs. l and 2 does not utilize the movement of the tongue 40 in the opening 39 for displacement of fluid, such may be done if desired as shown in the modification illustrated in Figs. 3 and 4. In such modification the parts of the pump which are the same or equivalent to the parts 1 to 40 illustrated in Figs. l and 2 are-numbered 101 to 140 respectively to avoid a detail repetition of the construction of the Figs. 3 and 4 pump.

In order to provide such additional displacement, openings 141 may be drilled through the opposite sides of piston 138, such openings leading into the ends of opening 139 in the piston 138. The rotor 132 may be provided with relatively narrow grooves 142 which communicate the openings 141 successively with the recesses 108 and 109 and ports 110 and 111 during rotation of said rotor by way of openings 143 and circumferentially extending narrow grooves 144 around the cylindrical lands of the rotor 132. Since the grooves 144 are relatively narrow, there still will not be any appreciable bypass of uid around the rotor because the reduced portions of the lands are restricted to the area between the opposite edges of Such grooves 144 and the opening 135 through the rotor 132.

In order to increase the displacement of the tongue 140 so as to approach that of piston 138, the opening 139 is in the form of a cross in cross-section and the tongue 140 also is of cross shape provided with lateral extensions or ribs 145 slidably engaged with the opposed walls of the lateral extensions of opening 139. Communication between the two sets of three chambers thus formed between the ribs 145 and tongues 140 and the opening 139 is afforded through one or more slots 146 formed in the ends of the tongue 140.

A further difference in the pump illustrated in Figs. 3 and 4 is the equal circumferential extent of the recesses 108 and 109. A still further difference resides in the provision of a plate 147, to the inner face 106 of which the adjacent ends of the tongue 140 and ribs 145 and of the piston 138 are relatively closely fitted (but out of contact) whereby again, as in Figs. 1 and 2, high speed rubbing or sliding contact is avoided. The holes 148 through piston 138 are merely for the purpose of reducing the weight of said piston 138. Any desired clearance may be provided between wall 107 and the adjacent rotor end wall and also between plate 147 and the other end of said rotor.

Because the operation of the pump illustrated in Figs. 3 and 4 is generally the same as that of the pump illustrated in Figs. 1 and 2 repetition thereof is not deemed necessary.

lthough the pumps herein illustrated do not include mechanism for varying the eccentricity between the rotors and coupling members and thereby varying the displacement, it will be apparent to those skilled in the art to include such mechanism if desired. Examples of a few of the many different ways of rendering pumps of the general type herein disclosed variable in displacement, may be found in my copending applications Serial No. 56,489, now Patent No. 2,537,349, and Serial No. 56,490, now Patent No. 2,574,921, both filed on October 26, 1948, and application Serial No. l05,l35, now Patent No. 2,684,038, filed on July 16, 1949.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

I'therefore particularly point out and distinctly claim as my invention:

1. In a rotary pump, the combination of a casing providing a cylindrical chamber having intake and discharge ports leading thereinto, said chamber having an interior cylindrical surface connecting radially extending end surfaces, a rotor with a cylindrical outer surface connecting radially extending end surfaces and having a shaft in said casing, anti-friction radial and axial thrust bearing means mounted within said casing and on said shaft and supporting said rotor for high speed rotation about the axis of said chamber and maintaining said outer cylindrical surface and said end surfaces of said rotor in close proximity to, but out of Contact with, said corresponding cylindrical and end surfaces of said chamber, said rotor being formed with an opening therethrough extending transversely to the rotational axis of said rotor and of uniform cross-sectional size and said rotor also having an axially extending opening at one end which opens into said transverse opening, a piston of complementary cross-sectional size and shape mounted in and slidable in said transverse opening along a path transverse to the rotational axis of said rotor and formed with a radially and axially extending opening, and means journalled in said casing also for high speed rotation about an axis parallel to and eccentric to the axis of said rotor and having a portion thereof of smaller radial extent than the radial extent of said radially and axially extending opening in said piston and extending into and slidable within the radially and axially extending opening in said piston along a path angularly related to the path of sliding of said piston in said rotor, the opposite ends of said piston forming with said rotor and casing displacement cavities which successively communicate with said intake and discharge ports during rotation of said rotor, the radially extending end surfaces of the rotor extending radially inward of said transverse opening, the transverse opening in said rotor extending axially a distance less than the distance between said radially extending end surfaces on said rotor whereby said piston is prevented from contacting said radially extending end surfaces of said chamber.

2. A rotary pump according to claim l further characterized in that said piston is of a material having a relatively low coefficient of friction compared to that of said rotor.

(References on following page) References Cited in the le of this patent UNITED STATES PATENTS Gerleman Aug. 23, 1923 Westman et al Apr. 12, 1932 5 Appel Apr. 12, 1932 Waite July 12, 1932 Waite Oct. 29, 1935 FOREIGN PATENTS

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