US3410477A

US3410477A - Vacuum pump

Info

Publication number: US3410477A
Application number: US702132A
Authority: US
Inventors: Hartley Ezra Dale
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-01-31
Filing date: 1968-01-31
Publication date: 1968-11-12
Anticipated expiration: 1985-11-12

Description

Nov. 12, 1968 E. D. HARTLEY VACUUM PUMP Original Filed July 25, 1966 5 Sheets-Sheet l E. DALE HazrLEs rroewEs/.sz

Nov. 12, 1968 E, D. HARTLr-:Y

VACUUM PUMP e. n m n ,o D. E

Original Filed July 25, 1966 104] gl Z a/M, 747, JM

Nov. 12, 1968 E. D. HARTLEY VACUUM PUMP 5 Sheets-Sheet 3 Original Filed July 25, 1966 am i 5| 5| mm m @y Z i #from/sys.

United States Patent C 3,410,477 VACUUM PUMP Ezra Dale Hartley, 2700 .lalmia Drive,

Los Angeles, Calif. 90046 Continuation of application Ser. No. 567,632, July 25, 1966. This application Jan. 31, 1968, Ser. No. 702,132 11 Claims. (Cl. 230-185) ABSTRACT F THE DISCLOSURE A double chambered vacuum pump, a piston in each chamber, the pistons being joined to move in unison, an eccentrically mounted means between the pistons for rollably reciprocating the pistons within their respectivechambers and limiting piston rotation, passageways formed in the pump body for intercommunicating the chambers whereby to permit selective operation in parallel, twostage or independent modes, and check valves in the inlet and outlet openings of each chamber including th1n metallic members movable between open and closed positions and having closure peripheries which are large relative to their distance of movement between open and closed positions.

This application is a continuation of application Ser. No. 567,632, tiled I uly 25, 1966, now abandoned.

In a preferred form of the invention hereinaftery illustrated and described in detail, there is provided an elongated body formed to have a cylindrical chamber at either end of the body, the chambers being coaxially aligned; a piston assembly including two pistons, one in each of the cylindrical chambers, the piston assembly including mean xedly connecting the pistons together so that they move in unison within their respective chambers; and means located between the pistons for reciprocatingly moving the piston assembly during operation. In addition, the present invention provides inlet and discharge openings in each of the chambers, each such opening including a valve having a closure member movable between open and closed positions in timed relation with the movement of the piston assembly. Each of the inlet valves desirably comprises a thin annular closure member made of thin sheet metal or other material desirably having slight exibility, the inlet closure member being adapted to sealingly close an annular inlet opening. When the closure member is moved to its open position, such movement takes place in a direction parallel to the axis of the closure member, and through a very short distance relative to the diameter of the closure member, means being provided in the body of the pump for limiting movement in the opening direction. Each of the closure members for the discharge openings is similarly made of material such as thin sheet metal having no more than slight ilexibility and in its closed position sealingly closing a circular discharge opening. The inlet and discharge valves are thus effectively check valves.

The piston assembly in accordance with the present invention provides two pistons spaced relatively far apart and coaxially aligned. The construction in accordance with the invention in this respect thus provides a piston assembly having remarkably high longitudinal stability, being substantially equivalent to the stability of a conventional single piston with an extremely long skirt within the cylinder. Longitudinal stability of the piston assembly is further enhanced in accordance with the present invention by providing means for driving the piston assembly in the form of a shaft mounted for rotation about an axis perpendicular to the axis of the pump body proper, and an eccentric member mounted upon the shaft and adapted to rollingly engage the opposed inner faces of the two 3,410,477 Patented Nov. 12, 1968 pistons making up the piston assembly. Thus the construction of the present invention eliminates the use of bell cranks, piston rods and similar elements which coutribute to wear on the piston and cylinder by reason of the eccentric components of the forces resulting in such elements.

As stated, the pump in accordance with the present invention has two separate cylindrical chambers, and may thus be used as a two-stage vacuum pump by interconnecting the discharge opening of one of the chambers with the inlet opening of the other chamber, since the intake stroke in one chamber occurs at the same time as the discharge stroke in the other. Such interconnection may be desirably made by a channel formed integrally within the pump body and extending longitudinally thereof.

In another mode of operation, there is no uid interconnection between the two pump chambers, and the device then functions as two separate pumps. In a third mode of operation the two inlets are in fluid communication with one another, as are the two outlets, so the pump then has substantially double capacity, and the two halves operate in phase relation.

Accordingly, it is a principle object of the present invention to provide and disclose novel improvements in vacuum pumps. More specically, other objects of the invention are to disclose' such a pump including a hollow body provided with two longitudinally spaced, coaxially aligned chambers, each having a piston sealingly mounted therein, the two pistons being xedly joined together to form a piston assembly; to provide in such a pump means for reciprocatingly moving the piston assembly in the form of an eccentrically rotatable drive element between the two pistons of the assembly; to provide in such a pump valve means for inlet and discharge openings including closure members made of thin sheet material having at most slight ilexibility and movable normal to their major dimensions through only very short` distances between open and closed positions; and for other and additional objects and purposes as will be understood from a reading of the following description of a prefferred embodiment of the invention, taken in connection with the accompanying drawings in which r,

FIG. 1 is a top plan view of one form of pump in accordance with the present invention.

FIG. 2 is a side elevational view of the pump.

FIG. 3 is a vertical sectional view taken on line III-III of FIG. 1.

FIG. 4 is a perspective view of the piston assembly.

FIG. 5 is an enlarged perspective view of the guide pad of the piston assembly.

FIG. `6 is a perspective view of the lower face of the valve plate.

FIG. 7 is a sectional view of the upper part of the pump, taken on line VII-VII of FIG. 1.

FIG. 8 is an exploded view in perspective of one end of the pump, showing the details of the inlet and discharge valves.

FIG. 9 is a side elevational View of the piston assembly and the eccentric driving cam, with parts broken away and other parts shown in section.

FIGS. 10, 11 and 12 show, in diagrammatic form, three modes of operation of the present pump, the modes being designated as parallel, two-stage and independent respectively.

The general appearance of the present pump is seen in FIGS. 1 and 2, and its internal construction and operation will be understood by reference to FIG. 3. Thus the pump includes a body indicated generally at 20 having a generally cylindrical interior and provided at its opposite ends with upper and lower covers indicated generally at 22 and 24 respectively, the covers being retained in assembled relation with body 20 by screws 26. Each of the covers is internally configured to provide uid communication with the interior of the body through suitable valve means to Ibe later described in detail, and each of the covers is provided with a pair of internally threaded bosses for attachment thereto of external conduits or tubing. Thus, upper cover 22 includes

bosses

27 and 28, while lower cover 24 includes

bosses

29 and 30 for this purpose, the conduits being fragmentarily shown in dotted outline at 31.

Centrally of the length of body is a shaft indicated generally at 40, rotatable about an axis disposed diametrically of the cylinder, the shaft being journaled in opposite wall portions of the body by

bearings

41 and 42, the latter bearing being held in position by retaining plate 43 attached to the pump body by means 44.

The interior of the cylindrical body 20 provides a pair of axially spaced chambers, and within each chamber there is mounted a piston, the two pistons being connected together in the form of a piston assembly. With reference to FIG. 4, the piston assembly is indicated generally at 50, and includes upper and lower pistons indicated generally at 52 and l54 respectively. The two pistons are spaced apart by a set of spacer rods 56 extending longitudinally of the piston assembly, the pistons proper being assembled to opposite ends of the spacer rods 56 by fastening means 57.

Piston assembly 50 is mounted within body 20 to form therein a pair of axially spaced upper and lower chambers respectively indicated generally at 60 and 62. It will be noted, in FIG. 3, that piston assembly 50 is shown in its lowermost position, the upper cylindrical chamber 60 being therefore at its maximum instantaneous volume and the lower chamber 62 being at its minimum. The respective chambers are defined by cylindrical sleeves or liners indicated generally at 61 and 63, and each of the pistons is provided with one or more piston rings in slidable contact with the inner cylindrical surfaces of the sleeves. In a preferred construction there is provided a resilient O-ring 64 received in an annular groove of the piston serving to bias outwardly the piston ring 65. The ring is desirably made of Teon or similar self-lubricating material and configured at its mating ends (see FIG. 7) with

parallel tongues

66 and 67 to permit a certain amount of expansion and contraction of the ring during operation within its mounting groove 68.

Means are provided on drive shaft for reciprocatingly driving piston assembly longitudinally of body 20, and thereby cyclically varying the volumes of chambers and 62. As shown in FIGS. 3 and 9, such means include a camming assembly indicated generally at and comprising an inner lobe 72 fixed to shaft 40 and having a cylindrical periphery eccentric to the axis of the shaft. Rotatably mounted on the periphery is an annular cam indicated generally at 74 and having a cylindrical periphery 76 concentric with that of lobe 72, and hence eccentric to shaft 40. Needle bearings 77 facilitate free rotation 0f cam 74 on lobe 72.

The cam periphery 76 is engageable with the inner faces of the two

pistons

52 and 54, desirably -by rolling contact with

wear pads

80 and 81 respectively, recessed into such inner faces. The diameter of cam periphery 76 is less than the distance between the wear pad surfaces engageable therewith by a small amount, approximately 0.001 inch, so the cam does not contact both pads simultaneously. This clearance insures that the cam never is frictionally rubbed on one pad by reason of rotation imparted to the cam by its contact with the other pad. lPads 80 and 81 are desirably made of a material having some resiliency, such as a phenolic resin, to minimize mechanical shock during reversal at either end of the stroke of the piston assembly. The wear pads may be easily replaced when worn. Means may be incorporated in at least one of the wear pads to prevent rotation of the piston assembly about its own axis during operation. As seen in the lower portion ot FIGS. 3 and 4, as well as in the enlarged showing of FIG. 5, wear pad -81 is provided with a recessed guide track 82, adapted to contact the cam periphery 76, the track 82 being here shown as laterally defined by a pair of inclined shoulders 83 and `84, shaped to fit correspondingly beveled edges 85 and 86 of cam 74. Wear pad A81 is maintained in position within its recess in piston 54 by suitable indexing means such as pin 87 engaging a bore 88 in the wear pad, the lower end of the pin being driven into a bore 89 formed in piston 54.

From the foregoing description, it will now be understood that rotation of shalft 40 and its lobe 70 by a suitable motor or other drive means, not shown, rwill cammingly drive the piston assembly 50l reciprocatingly within the cylindrical body 20 and thereby cyclically vary the volumes of

chambers

60 and 62; .and it will be noticed that the volume variations of the two chambers will tbe displaced from one another by 180 in phase.

AValve means are provided in accordance with the present invention, in conjunction with the

cover members

22 and 24 at each end of the cylindrical body 20. The valve :assemblies at each end of the body are identical to one another and the upper such assembly will be described by reference to FIGS. 6, 7 and 8.

With reference first to FIGS. 7 and 8, the inlet Valve includes an inlet closure member indicated generally at 90 and comprising an annualar washer of thin sheet material such as spring steel, having a central bore 91. The outer annular marginal portion of washer 90 is received loosely in an annular space defined by a counterbore 92 in the upper portion o-f liner 61 and the lower annular face 93 of a valve plate indicated generally at 94. In turn, the face 93 of the valve plate rests upon the upper annular rim 9S of the liner 61. The inner annular portion of washer 90, immediately outwardly of central bore 91, is space-d slightly below an annular portion of a downwardly facing shoulder 97 of a central collar indicated generally at 98 yformed in valve plate 94, the shoulder `97 being coplanar with face 93. Inlet fluid communication downwardly through valve plate 94 is provided by :a number of apertures 99 formed in the annular web 100 of the valve plate, outwardly of collar 98.

It is to be observed that the depth of counterlbore 92 is substantially greater than the thickness of washer 90. For

example, the latter member may be made of spring steel having a thickness of about 0.003 to 0.004 inch, while the depth of the counterbore 92 may illustratively be in the-range of about 0020-0030 inch. Keeping in mind that the central annular shoulder 97 of the valve plate is coplanar with the outer annular face 93, it will be seen that the washer closure member 90 is permitted to move upwardly and downwardly within counterbore 92 in respo'nse to dilerences of pressure on oposite sides of the washer resulting from piston movement within chamber 60. lWhen the washer 90 is in its lower position, as seen in'FIG. 7, the inlet valve is open, permitting fluid ow from above valve plate 94 downwardly through the openin'g's 99 in the valve plate, and continuing downwardly through the annular space between the inner shoulder 97 off the valve plate andthe annular portion of the washer aligned therewith. In the closed position of the inlet valve, the washer 90 is caused by differential uid pressure to move upwardly from its position seen in FIG. 7, so that its outer annular marginal portion seals against shoulder 97. The washer itself is of such light weight that it moves Very rapidly to one or the other of its two positions under the influence of differential fluid pressure across it. Furthermore, the lightness of the washer makes its operation virtually independent of gravity. Good sealing characteristics of the inlet valve may be impaired if the washer is permitted to dish ex cessively upwardly when in closed position. Hence the lower face of valve plate 94 (see FIG. 6) is desirably provided with an annular rib -101 to prevent such excessive dishing, the lower face of rib 101 being spaced above the plane of face 93 and shoulder 97 by a small amount, desirably 0.005 inch or so.

Valve plate 94 serves also `as a mounting for the outlet or discharge valve in accordance with the present invention, comprising a disc indicated generally at 104 and desirably made of lightweight spring steel similar to that of washer 90 previously described. In its closed position as seen in FIG. 7, disc 104 seals with a shoulder 105 dening the lower extent of a counterbore 106 formed in valve plate 94 in vertical alignment with bore 107 in cover 22. The disc 104 may be lightly biased into that position by a resilient member indicated generally at 108 received in a central bore '109 in boss 110 of the cover member 22. When the discharge valve is opened by differential fluid pressure rforcing the disc upwardly against the light force of spring 108, `uid flow takes place around the periphery of the disc, between the disc and the shoulder 105.

vMeans are provided for hermetically sealing the cover 22 to body 20 and to the operative portions of the valve assembly just described. Thus, valve plate 94 may be provided with a bevel 112 for receiving therein an O- ring 114, and the upper face of collar 98 of the valve plate may #be provided with a ygroove 116 for receiving therein an O-rin1g 118, both rings sealing with the lower face of cover 22.

As previously mentioned, and as clearly appears in FIG. 3, the lower part of the present pump includes a valve assembly exactly identical to the valve assembly heretofore described in connection with FIG. 7, reversed as to orientation and cooperating with lower cover 24.

Inward and outward flow of fluid during operation of the present pump in one mode will be understood by further consideration of FIG. 7. Thus, 4boss 27 is provided with an internally threaded bore 120 constituting the inlet port for the upper pump, in communication near its lower end with a passageway 122 leading to an annular recess 124 formed in the lower face of cover 22 in alignment with the annular space immediately above web 100 of valve plate 94, thereby forming an annular distribution chamber for incoming uid above the web. Incoming uid is thus conducted through the web openings 99 to the upper face of inlet closure member 90 and, when the latter member is opened, the uid passes through bore 91 into chamber 60. This tiuid movement, it will be readily understood, takes place during downward movement of the piston 52, the discharge closure member 104 being then maintained in its closed position. When piston 52 begins its upward movement, inlet closure member 90 is moved upwardly into its closed position, sealing with face 93 and shoulder 97 as previously explained, and simultaneously discharge valve closure member 104 is raised upwardly, permitting iluid ow into the bore 107 and thence outwardly through passageway 130 to the internally threaded bore 132 of boss 28, constituting the discharge port for the upper pump.

The body of the present pump is desirably provided with integrally formed means for uid communication between ends of the pump. In the present embodiment of the invention, with continued reference to FIG. 7, the body is provided with a pair of longitudinally extending

channels

140 and 142, here shown as being diametrically opposite one another and communicating at their upper ends through

openings

141 and 143 in the cover with the inlet and discharge

ports

120 and 132 respectively. Suitable sealing means such as O-

rings

144 and 145 provide a hermetic seal around the junction of the

channels

140, 142 and the

respective bores

141, 143. Keeping the foregoing in mind, and with reference now to the diagrammatic showing of FIG. 10, it will be seen that fluid entering through inlet port 120 will divide, part of such uid entering the upper chamber 60 while the remaining part will move downwardly through channel 140 to lower inlet port 150 through bore 151 corresponding to bore 141 previously mentioned. Since port 150 is closed by plug means 152, such tluid will then pass into the lower pump chamber 62 during upward piston movement, constituting the intake stroke for the lower chamber. After passing through the lower pump chamber 62 (shown at minimum volume in FIG. l0) such iluid will proceed to lower discharge port 154 and will then move upwardly through bore 153 and channel 142, since port 154 is closed by plug means 156. Continuing upwardly, such fluid enters upper discharge port 132 and may be conducted therefrom to a conduit or the like or may be exhausted to atmosphere. If discharge to atmosphere is permitted, then it may be desirable to eliminate plug 156, to open the port 154 to atmosphere, in which case channel 142 and cover bores 143 and 153 are not needed.

The mode of operation just described may be referred to as parallel operation, and permits the present pump to be advantageously used to provide substantially twice the evacuating capacity of either pump section alone. Furthermore, as above mentioned, the operating cycles of the upper and lower pump sections are displaced from one another by 180 in phase, whereby pulsing in connected conduits is substantially reduced.

The present pump is readily adapted for use as a two-stage vacuum pump, to be now described in connection with FIG. l1. It will here be noted that 1) the lower cover 24 is assembled to body 20, rotated 180 from its position shown in FIG. 10, so that lower inlet port 150 in boss 29 is longitudinally aligned with upper discharge port 132 of boss 28; and (2) the bore 141 is omitted or plugged olf, so that there is no uid communication from inlet port into channel 140, and that channel may itself be eliminated. Consequently, all incoming uid in inlet port 120 enters the upper pump chamber 60 and is discharged therefrom into discharge port 132. Since that port is closed by plug means 162, the uid proceeds downwardly through bore 143, channel 142 and bore 151 into lower inlet port 150, the latter being plugged by plug means 163. This fluid hence becomes the inlet uid for the pumping action of the lower section of the present pump, such iiuid then being discharged through lower discharge port 154, either to atmosphere or into a suitable conduit as may be desired. It will be noted that bore 153, previously referred to in connection with FIG. 10 in the base of boss 30, is not shown in the FIG. 11 mode of operation, being plugged off or otherwise eliminated.

A third mode of operation of the present pump is illustrated in FIG. 12, constituting essentially two separate pumps. Thus it will be noted that the

covers

22 and 24 are not provided with any of `the

bores

141, 143, 151, 153 heretofore described, and accordingly longitudinal channels and 142 are closed off from fluid flow. In the upper pump section as seen in FIG. 12, fluid entering inlet port 120 is pumped lin chamber 60 and then discharged through discharge port 132; and in the lower pump section uid entering inlet port is pumped in chamber 62 and then discharged through discharge port 154. No interconnection between the two fluids exists, and two completely separate fluids may accordingly be pumped in the mode shown in FIG. 12.

There is accordingly provided in the present invention a pump of unusual economy in terms of space and weight, and providing, moreover, for great stability of operation resulting from the comparatively large effective length of the piston `assembly with its driving means housed within the assembly, thereby eliminating the use of bell cranks and crank shaft and the resulting force vectors transverse to the piston axis, causing wear, as in conventional constructions. The symmetry of the construction makes for ease and economy of manufacture and servicing.

The valve construction as such affords substantial advantages in that, for example, the annular inlet closure member presents a comparatively large area to incoming fluid, which itself is normally under very low pressure in evacuating a vessel. The light weight and large area of this closure member combine to insure its very rapid movement between open and closed positions, with virtually complete elimination of back-flow, Also, small movement of the closure members provides comparatively large areas for iuid movement, by reason of the fact that the edges of bore 91 and of disc 94 are very long relative to their thickness. For example, the inlet closure member or washer 90, with an outside diameter of about 1% inches, may have a bore diameter of 3A inch or thereabouts; and the diameter of disc 94 may be about the same as that of bore 91 or a little less, say Sys inch.

Modifications and changes from the illustrative embodiment of the invention hereinabove illustrated and described may be -made without departing from the spirit of the invention, and all such modifications and changes are intended to be embraced within the scope of the appended claims.

1. A pump comprising:

an elongated body including a pair of coaxially aligned,

axially spaced cylindrical chambers;

a piston assembly including axially spaced pistons sealingly sldable in the chambers and spacer means lixed to the pistons and extending therebetween, each piston including an inner face directed away from its respective chamber, one of said inner faces having formed therein a recessed guide track;

means for reciprocatingly driving the piston assembly longitudinally of the body including a shaft mounted for rotation about an axis transverse to the axis of the chambers Vand a roller rotatably mounted on the shaft having a cylindrical periphery eccentric to the shaft axis and rollably contacting, successively, one or the other of said piston faces, the roller being continuously received in said guide track, whereby to limit rotation of the piston assembly about its own axis;

and inlet and discharge openings communicating with each chamber, each opening provided with check valve means.

2. The invention as defined in claim 1 wherein said inlet openings are annular and lie in planes normal to the body axis and the inlet check valve means includes thin sheet closure members movable between closed positions wherein each sealingly covers its inlet opening and an open position spaced from said inlet opening toward the respective piston, and including means limiting movement of the closure members toward their open positions.

3. The invention as defined in claim 2 wherein each of the discharge check valve means comprises a thin sheet disc closure member movable axially between a closed position sealingly closing its discharge opening and relatively close to its respective piston, and an open position relatively distant from its respective piston.

4. The invention as defined in claim 3, including resilient means biasing said discharge closure member toward its closed position.

5. A pump comprising:

an elongated body including two variable volume chambers in longitudinally spaced relation;

Van actuating assembly movable longitudinally within the body and including spaced members each forming a wall of one of the two chambers and provided with two surfaces facing one another and disposed in spaced parallel planes transverse to the direction of assembly movement;

and means for reciprocatingly driving the actuating assembly longitudinally of the body including a shaft mounted for rotation about an axis transverse to the direction of assembly movement and a roller rotatably mounted on the shaft having a circular periphery eccentric to the shaft axis and rollably contacting, successively, one or the other of said surfaces.

6. The invention as defined in claim 5 wherein one of said surfaces is bounded laterally of the path of rolling contact of the periphery thereon by spaced shoulders deiining a guide path for the roller.

7. A pump comprising:

an actuating assembly movable longitudinally within the body and including spaced pistons sealingly slidable in the chambers and provided with two surfaces facing one another and disposed in spaced parallel planes transverse to the direction of assembly movement;

8. The invention as defined in claim 7 wherein one of said surfaces is bounded laterally of the path of rolling contact of the periphery thereon by spaced shoulders defining a guide path for the roller.

9. In a pump including a body having two longitudinally spaced variable volume chambers and an actuating assembly movable longitudinally within the body including spaced members each forming a wall of one of the two chambers and two surfaces facing one another and disposed in spaced parallel planes transverse to the direction of assembly movement, the provision of:

means for reciprocatingly driving the actuating assembly longitudinally of the body including a shaft mounted for rotation about an axis transverse to the direction of assembly movement and a roller rotatably mounted on the shaft having a circular periphery eccentric to the shaft axis and rollably contacting, successively, one or the other of said surfaces.

10. The invention as defined in claim 9 wherein said surfaces are spaced apart by a distance slightly greater than the periphery diameter whereby the roller periphery is not in contact with both of said surfaces simultaneously.

11. The invention as defined in claim 9 wherein one of said surfaces is bounded laterally of the path of rolling contact of the periphery thereon by spaced shoulders deining a guide path for the roller.

References Cited UNITED STATES PATENTS 1,116,998 11/1914 Compton 230-185 X 1,474,769 11/1923 Dunning 230-185 X 1,652,565 12/1927 Dunning 230-185 1,842,027 1/1932 John 230-185 2,246,932 6/1941 Collins 230-40 2,404,079 7/ 1946 Maniscalco et al 230-185 FRED C. MATTERN, JR., Primary Examiner W. I. KRAUSS, Assistant Examiner