US3078807A - Dual-action displacement pump - Google Patents

Description

Feb. 26, 1963 T. F. THOMPSON DUAL-ACTION DISPLACEMENT PUMP 3 Sheets-Sheet 1 Filed Oct. 16, 1958 INVENTOR.

m WP w Theodore E Thompson ATTORNEYS Feb. 26, 1963 T- F. THOMPSON 3,078,807

DUAL-ACTION DISPLACEMENT PUMP Filed Oct. 16, 1958 Y s Sheets-Sheet 2 INVENTOR.

Theodore E Thompson ATTORNEYS Feb. 26, 1963 T. F. THOMPSON 3,078,307

DUAL-ACTION DISPLACEMENT PUMP Filed Oct. 16, 1958 s Sheets-Sheet :5

INVENTOR.

Theodore E Thompson MMH H BY ATTORNEYS United States Patent 3,078,807 DUAL-ACTION DESPLACEMENT PUMP Theodore F. Thompson, Davenport, Iowa, assignor of one-half to William D. Hewit, Denver, Qolo. Filed Oct. 16, 1958, Ser. No. 767,649 2 Claims. (Cl. 103126) This invention relates to pumps and more particularly it relates to rotary positive displacement pumps of high capacity and high pressure.

It is an important object of the invention to provide a simplified rotary double displacement pump having a minimum of wear surfaces and a minimum of moving parts.

It is a further object of the invention to provide a double displacement rotary pump of high capacity and capable of producing high pressures with a minimum expenditure of power.

It is a further object of the invention to provide a rotary displacement pump in which two interconnected rotors alternately increase and decrease the pumping volume of interconnected chambers in which they operate, with a minimum of back flow and with a positive fluid displacement so as to provide an essentially non-pulsating pump.

It is another object of the invention to provide a rotary pump in which at least two rotors mounted in the pump operate conjointly, rolling on each other and each rolling on the surface of its enclosing pump chambers with a minimum of slippage.

Another object of the invention is to provide a double rotor, a rotary pump in which the rotors are mounted on eccentric shafts so that once in each revolution each rotor provides a complete seal from the inlet and outlet for its enclosingchamber, and the inlet is sealed from the outlet.

A. still further object of the invention is to provide a rotary pump which includes a double rotor arrangement mounted in a housing so that one rotor provides a seal for the opposite roller while both simultaneously displace liquid from the inlet to the outlet in an overlapping discharge whereby to provide a double non-pulsating displacement of fluids through the pump.

These and other objects and advantages of the invention may be readily ascertained by referring to the following description and appended drawings in which:

FIG. 1 is an end elevational view of a pump according to the invention;

FIG. 2 is a cross-sectional view of the pump illustrated in FIG. 1 taken along section line 22;

FIG. 3 is a partial sectional view of the pump of the invention illustrating one position of the pump rotors;

FIGS. 4, 5 and 6 are essentially schematic drawings. illustrating sequential steps of operation of the pump;

FIG. 7 is an end elevation of a pump of the invention illustrating the gear mounting of dual rotors of the in vention;

FIG. 8 is a cross-sectional view of one form of rotor for use in one form ofthe pumpof the. invention;

FIG. 9 is a cross-sectional, lengthwise view through a modified roller of the. invention; and

FIG. 10 is a cross-sectional view of a pump of the invention illustrating a further modification thereof.

In general, the displacement pump of the invention includes a hollow housing having two essentially cylindrical chambers of equal diameter, overlapped and interconnected in the general shape of a figure eight, with an upper and lower bight on the plane of symmetry. A roller is. provided in each chamber, with the diameter of the roller slightly smaller than the diameter of the chamber. The rollers are; mounted on eccentric shafts which are positioned and so interconnected that rotation of the shafts maintains the two rollers incontinuous engagement with each other and each roller in continuous engagement with the wall of its enclosing chamber. Each roller is so proportioned as to bridge the gap at the intersection of the two chambers, and the bridging occurs alternately at degrees apart. The rollers are freely rotatably mounted on the eccentric shafts so that each roller, being in contact with the housing, merely rolls on the inner surface of the housing and rolls on each other. This rolling is essentially without slipping due to the fact that each roller is freely rotatable on the shaft and is not rotatably driven. A perfectly smooth housing and roller surface is not essential, the criterion being that the surface of each roller meshes or aligns with and seals against thesurfaoe of its chamber and the surface of the opposite roller throughout each revolution. The rollers mounted on the eccentric shafts must be of such a size and the eccentricity must be great enough to move the rollers into and out of the area of chamber overlap to alternately increase and decrease the volume of the space in each chamber. This increase of volume occurs alternately at the inlet and the outlet at essentially 180 degrees of rotation whereby each roller provides suction intake and pressure outlet on-a 180 degrees cycle with the cycles of the rollers substantially overlapped to produce a non-pulsating pumping ac tion. Since each roller is of a smaller diameter than the chamber in which it operates, a volume or space remains between the roller and the surface of the chamber. The operation of the eccentric shafts is such as to move the tangential contact of the rollers alternately into and out of the confines of the chambers so that there is an alternate in-' creasing and decreasing volume in the opposite chambers at 180 degrees apart which produces the effective pumping action.

In the pump illustrated in FIGS. 1 through 3 for purposes of detailed description, a hollow housing 1 is provided with end plates 2 and 3 for enclosing intersecting cylindrical chambers 6 and 7. A foot 2a mounted on the end plate 2 and the foot 3a mounted on end plate 3 are arranged to be attached to a base member by means of bolts or the like through holes 4 and 5 in the feet. This arrangement provides means for anchoring the pump in operation position. The end plates are secured to the housing 1 by means of bolts 8 or other suitable means for securing the parts together. The joints between the housng 1 and the end plates 2 and 3 must be tight to provide an essentially fluid tight connection, and for this purpose various sealing mechanisms well known in the art may be used. Also, since this is a high pressure pump, a plurality of bolts are preferably provided around the periphery of the chambers to provide a tight enclosure capable of withstand'ng the fluid pressures which the pump is capable of producing.

A boss 10 mounted on the end plate 3' and a boss 11- mounted on the end plate 2 provide means for journaling shafts in the pump. The bosses are substantially of figure 8 shape extending across both chambers for supporting the shafts. Each shaft must include a seal, and-since this is a common feature for pump shafts, no specific illustration is deemed necessary.

The cylindrical chambers 6 and 7 illustrated inthe pump intersect in such a manner as to provide anoverlapped area, for example as illustrated in FIGURE 3,. the area oneither side of a plane 12 passing through the intersection of the two cylindrical chambers. A sealin'g member 14' is mounted in the upper intersection and ex-.

tends. the length of the chambers, and a'sealng member 15 is mounted at the lower intersection and, also, extends the length of the two cylindrical chambers. Each ofthe sealing members includes a flattened surface at about the intersection which is a predetermined distance between the intersections and in effect cuts off the point of the bightof'each intersection. The seal member 14 includes a flattened area 16 while the sealing member 15 includes the flattened area 17 facing the area 16. An upper port 20 extends through the end plate 2 above and adjacent the intersection of the cylindrical chambers and a passage 22 in the housing body communicates therewith. A plurality of small bores 23 extend through the sealing member 14 through the flattened area 16 and interconnect the passageway 22 with the interior of the pump housing. In a similar manner a passageway 25 in the lower portion of the housing interconnects with the port 21 through the end plate 2 and with a plurality of bores 24 through the sealing member 15 and the area 17. One of these passages provides an inlet for the pump while the opposite passageway provides an outlet, depending on the rotation of the rotors in the pump.

A shaft is journaled for rotation concentrically with the chamber 6, and a shaft 31 is journaled concentrically in chamber 7. An eccentric member 32 is mounted on the shaft 30 for conjoint rotation therewith, and an eccentric member 33 is rigidly mounted on the shaft 31 for conjoint rotation therewith. The shafts 30 and 31 are geared together, by means of gears 35 and 36 mounted on the ends of the shafts which extend through the boss 11. The shafts rotate in opposite directions and must be so geared together with a minimum of play and the eccentrics must be securely fastened to the shafts so that the zenith of each of the eccentrics is exactly 180 de ees of rotation apart. Furthermore, the shafts are so geared together by spur gears 35 and 36, FIG. 7, that they rotate in opposite directions at substantially the same speed. A cylindrical rotor 40 is freely, rotatably mounted on the eccentric 32, and a cylindrical rotor 41 is freely, rotatably mounted on the eccentric 33. Each rotor is essentially the same length as the housing 1 so that the ends of the rotors seal against the end plates 2 and 3 of the pump.

One form of the rotor is illustrated in FIG. 8 wherein the cylindrical rotor body 44, which is normally made of a rigid material such as steel or the like, is mounted on roller bearings 45 on the eccentric 32. This mounting permits the member 44 to freely rotate on the eccentric. The resilient covering 46 is bonded or otherwise secured to the exterior surface of the cylindrical member 44 forming a covering or sheath on the roller. The parts are dimensioned so that the exterior surface of the resilient material 46 is in contact and slightly compressed on the inner surface of the cylindrical chamber 6. The free rotation of the rotor on the eccentric permits it to roll on the surface essentially without slipping. In a similar manner, the opposite rotor is in contact with the surface of the chamber 7. The two rotors are in contact and they are compressed so that the two cylinders ride on one another also essentially without slipping and without slippage on the chamber walls. The resilient material covering the roller is slightly compressible at its contact points, and under normal operating conditions there is only an insignificant leakage at such contact points. The compression, also, provides a right frictional engagement between the rotor members which prevents back-leaking from outlet to inlet.

The shaft 30 extends through the boss 11 and provides means for mounting a pulley for driving the pump, including a key way 50 cut in the shaft. Suitable packing and bearings must, of course, be provided to prevent fluid leaking and to provide efiicient rotation. Such packing and bearing assemblies may be essentially known types.

The diameter of each rotor is slightly less than the diameter of the chamber in which it is mounted so that there is a space or a volume between the exterior surface of the rotor and the surface of the chamber. This volume represents the volume of displaced liquid moved from the inlet to the outlet of the pump. As explained below, the operation of the pump provides a positive displacement of the fluid from the inlet to the outlet. Both rotors provide the pumping action so the pump, as illustrated, has a dual displacement of fluid for each revolution.

In one very effective size, a pump is provided in which the chambers have 3.89 inch diameter, and the axes of the cylinders are mounted 3.4687 inches apart. This provides an overlap area between the cylinders so that there is in effect a figure 8 chamber in the pump. The cylindrical chambers are provided with parallel axes. The bight at the intersection of the cylinders is fitted with a seal member, as explained above, and bores through the sealing members provide the inlet and the outlet openings for the pump. The housing is 2.27 inches in Width, however, the length or the width of the housing may be varied as this measurement determines the capacity of the same diameter pumps. A 0.669 inch shaft is journaled for concentric rotation in each chamber and a one and a quarter inch diameter member is mounted 0.215 inch off center or concentricity forming the eccentric member on the shaft. This provides a throw of 0.215 inch for each rotor. A 3.520 inch external diameter roller or rotor is mounted on roller bearings mounted on each eccentric. The roller is covered with a soft durometer rubber sheath which permits the rollers to be squeezed against the surfaces and against each other. The compression of the rubber sheath is about one-thirty-second of an inch on each side. With the pumps of this dimension and with the shafts operating at about 600 r.p.m. the pump delivers five gallons per minute at about 900 lbs. pressure. Higher pressure and capacity may be achieved by increasing the pump speed.

The operation of the pump is more readily understood by referring to FIGS. 3 through 6 which illustrate various positions of the rollers during movement. It is essential in the consideration of the operation of the pump to note that each eccentric rotates freely in the rollers, and the rollers merely roll around the inner surfaces of the chambers and roll against each other essentially without lost motion between the rollers or between the housing or casing. In FIG. 3 the rollers are shown in the extreme left position or nine oclock position where the roller 41 is contacting the housing. In this position the roller 40 is also in the nine oclock position tangentially contacting roller 41. This leaves a maximum space between the housing and the roller 40. Also, in this position the roller 40 contacts both sealing member 15 and sealing member 14 completely sealing chamber 6 from the inlet and outlet ports. Rotor 41 on the other hand is not in contact with either sealing member. According to the rotation of the shafts as indicated by the arrows, sealing member 14 is the inlet and the other sealing member 15 is the outlet. In this position the space in chamber 7 adjacent to inlet is increasing in size while the space adjacent to the outlet 15 in the chamber 7 is decreasing.

In the position illustrated in FIG. 4, the shafts have turned 45 degrees in the indicated direction and the rollers also have moved essentially 45 degrees. In this position the roller 40 is still substantially in contact with the inlet sealing member 14, but it is no longer in contact with sealing member 15. The volume between the roller 40 and the casing chamber 6 has been opened to the outlet 15. As the roller 41 has moved 45 degrees downwardly the volume in this chamber adjacent to the outlet has been decreased, thus forcing the liquid out the outlet. Simultaneously, the roller 40 has moved up providing communication for the space in chamber 6 with the outlet. Since that roller 40 has moved around 45 degrees, the space in chamber 6 has been decreased and the pressure created by decreasing volume is now released through the outlet 15. It is to be noted that the roller 41 was discharging continuously while at some point in the 45 degrees rotation, the movement of roller 40 opened the outlet to the volume of roller 40 providing in effect a continuous discharge without pulsation. Simultaneously with the action at the discharge, the inlet volume of chamber 7 has increased due to the movement of the roller 41, thereby increasing the suction on the inlet and drawing in more fluid. Since the roller 40 is essentially still in contact with the sealing member 14 during this rotation. The movement of the roller is essentially all discharge.

Further rotation of the shafts, to the position illustated in FIG. 5, where the zenith of the eccentric 33 is vertically downward and the zenith of the eccentric 32 is vertically upward, moves the rollers to a position where the inlet olume ofroller 41 and minor inlet v um of 40 substantially equals the outlet volume of roller 40 and the small outlet volume of roller 41. In this position'the tangentialcontact between the two rollers is substantially along the Plane of symmetry llthrough the chambers. Also, in this position the roller 40 is now o of .wntact with the s alina ember 14 h inlet volume of roller 40 is increasing thereby causing a suction while the inlet volume of roller 41 is approaching maximum due to the movement of the roller 41 upwardly towards the sealing member 14. The roller 40 is displacing liquid from the space in the chamber toward the outlet 15, and the roller 41 is completing its discharge.

Further movement of the shafts causes a displacement movement of the rollers to the position indicated in FIG. 6, where the rotor 41 is now in sealing contact with the outlet sealing member 15 and the inlet volume of the chamber 7 is approaching maximum volume. Simultaneously the discharge volume of chamber 6 is decreasing, displacing the fluid through the outlet sealing member 15. It is to be noted in this position that the rotor 41 has extended to right past the plane of symmetry 12 so that the volume in chamber 6 is approaching its minimum while the volume in chamber 7 is approaching a maximum. Continued rotation of the shafts will move the rotor 41 to the position where it contacts both the sealing members 14 and 15, completely sealing the chamber 7 from both the inlet and the outlet opening, which is exactly 180 degrees from position as illustrated in FIG. 3. In this position the volume in chamber 7 is at a maximum while the volume in chamber 6 is at a minimum. Further rotation of the shafts continues the displacement of the fluid at the outlet volume from chamber 6 and before it is completely discharged the space of chamber 7 opens up to the outlet forming a continuous discharge. Simultaneously, the inlet volume of chamber 6 opens up prior to the closing of the inlet of 7 forming a continuous inlet.

A modified roller is illustrated in FIG. 9 wherein a roller body 50 is arranged for mounting on the bearing set mounted on the eccentric of the shafts, and the body of the roller 50 is slightly smaller than the width of the housing so that the roller body does not contact the end plates of the pump. A resilient sheath 52 is sealed to the exterior surface of the body 50 and the diameter of the resilient body is slightly larger than the theoretical diameter of the rollers if they exactly fit the housing. This is essentially the same arrangement as the rollers described in FIG. 8 to provide the compression between each roller and its housing and roller on roller to prevent back-leaking of fluid. A metal disc insert 53 is sealed in the rubber with a bearing surface 54 in position to contact the end plates of the pump. The disc 53 may be a steel member having a hardened face 54 or it may be a hardened steel member providing a wearing surface for the roller against the end plates. The wearing face 54 of the disc 53 extends slightly beyond the disc surface 55 forming a shallow recess 56 which may act as a grease ring for holding a body of lubricating grease. The grease also acts as a seal against the end plates of the pump. With the use of the seal ring 53 the distance between the bearing face 54 on the one end and the opposite bearing face on the other seal ring on the other end of the roller may be made slightly larger than the distance between the end plates of the pump, thereby causing the resilient covering to exert a spring like pressure on the disc against the end plate forming a tight seal to prevent 6 leaking andback flow of fluid from the pressure side of the pump.

In the modification illustrated in FIG. 10, a housing 1 is provided with end plates 60 and 61. The endplate 60 is provided with a foot 60a, and the end plate 61 is provided with its foot 61a for securing the pump to a base member. In this instance the end plate .60 includes an enclosed boss 63 having a bearing cavity 64 therein for journaling a shaft 65 therein by means of roller bearings 66. The end plate 60 includes two such bosses, one for each shaft, providing a sealed bearing for each shaft and thereby reducing the possibility of leakage. A.boss is provided for the opposite ends of the shafts in end plate 61 to provide a gear mount for both shafts and a drive end 68 on the shaft 65. Gears 69 are mounted on the shafts to provide conjoint rotation and the shafts, as explained above. The shaft 68 may be provided with a key way 70 for keying a drive pulley thereto.

An additional modification is provided in that the inlet is interconnected with a passage 76 which extends through the housing 1 essentially in the bight between the two chambers. Instead of communicating with bores (as shown in FIG. 2) through the sealing projections 77 and 88 of housing 1, a bypass or passage way around each of the sealing members is provided. Thus a passage 78 in end plate 60 and a similar passage 79 in end plate 61 provides an inlet. The passages 78 and 79 communicate with the pump interior adjacent to the sealing member 77 and when either roller is in sealing position against the sealing member 77 either or both of the inlet or outlet passages are completely closed from the space in the chamber. In a similar manner an outlet 80 communicates with a passage way 81 in the housing 1. A passage 82 in the end plate 60 and a passage 83 in end plate 61 provide communication with the interior of the pump around a sealing member 88. In this manner the inlet end outlet is provided for the pump without requiring the small bores through the sealing members as illustrated for the sealing members 14 and 15. Such passage ways around the sealing members are satisfactory for short length cylindrical pumps, but as the cylindrical rollers and chambers are elongated it is preferable to have the communication through the sealing member. This provides for a uniform pressure along the length of the rotor, and a greater volume may be passed.

While the invention has been illustrated by reference to specific embodiments, there is no intent to limit the scope or concept to the precise details so set forth, except as defined in the following claims.

I claim:

1. In a positive displacement pump having a housing including a pair of hollow cylindrical chambers of the same diameter partially overlapping along a chord which is substantially less than the maximum diameter of said chambers, and a pair of end walls enclosing the chambers, the improvement which comprises, a rigid cylindrical roller substantially smaller in diameter than its enclosing chamber mounted in each chamber, a shaft concentrically mounted through each chamber, a cylindrical member eccentrically and rigidly secured to each said shaft, a bearing set mounted on each said cylindrical member, one of said rollers mounted on each bearing set so as to be freely rotatable thereon, a resilient material covering of substantial thickness secured to the periphery of each roller, the peripheral diameter of each resilient covering being less than the diameter of the chambers but great enough for one covering to contact both wall ends at the intersection of the chambers and bear against the other roller which is bearing against its chambers wall at a point of intersection of a line through both shafts and the chamber wall, a sealing member mounted at each intersection of the chambers walls and positioned to seal the resilient covering when the covering is bearing against it, each sealing member including a planar surface perpendicular to a plane through the intersection of the chambers and the edges of said surfaces providing the seal for each roller, inlet means including a plurality of small bores extending from end wall to end Wall across one said surface, outlet means including a plurality of small bores extending from end wall to end wall across the other said surface, a circular gear mounted on each shaft protruding beyond the side wall of the chamber and intermeshed together for conjoint rotation of said shafts, and means for rotating at least one of said shafts.

2. A positive displacement pump according to claim 11 in which each of said small bores of each of said inlet and outlet extends through the seal means and cornmunicates with an inlet and outlet passageway in the pump housing respectively.

References Cited in the file of this patent UNITED STATES PATENTS Holly July 6, Schmidt July 29, Jaworowski Dec. 22, Lindberg Dec. 28, Brown Jan. 19, Barker Oct. 19,

FOREIGN PATENTS Germany Feb. 19, Germany Oct. 28, Germany Feb. 8, Germany Sept. 21,

Claims (1)

1. IN A POSITIVE DISPLACEMENT PUMP HAVING A HOUSING INCLUDING A PAIR OF HOLLOW CYLINDRICAL CHAMBERS OF THE SAME DIAMETER PARTIALLY OVERLAPPING ALONG A CHORD WHICH IS SUBSTANTIALLY LESS THAN THE MAXIMUM DIAMETER OF SAID CHAMBERS, AND A PAIR OF END WALLS ENCLOSING THE CHAMBERS, THE IMPROVEMENT WHICH COMPRISES, A RIGID CYLINDRICAL ROLLER SUBSTANTIALLY SMALLER IN DIAMETER THAN ITS ENCLOSING CHAMBER MOUNTED IN EACH CHAMBER, A SHAFT CONCENTRICALLY MOUNTED THROUGH EACH CHAMBER, A CYLINDRICAL MEMBER ECCENTRICALLY AND RIGIDLY SECURED TO EACH SAID SHAFT, A BEARING SET MOUNTED ON EACH SAID CYLINDRICAL MEMBER, ONE OF SAID ROLLERS MOUNTED ON EACH BEARING SET SO TO BE FREELY ROTATABLE THEREON, A RESILIENT MATERIAL COVERING OF SUBSTANTIAL THICKNESS SECURED TO THE PERIPHERY OF EACH ROLLER, THE PERIPHERAL DIAMETER OF EACH RESILIENT COVERING BEING LESS THAN THE DIAMETER OF THE CHAMBERS BUT GREAT ENOUGH FOR ONE COVERING TO CONTACT BOTH WALL ENDS AT THE INTERSECTION OF THE CHAMBERS AND BEAR AGAINST THE OTHER ROLLER WHICH IS BEARING AGAINST ITS CHAMBER''S WALL AT A POINT OF INTERSECTION OF A LINE THROUGH BOTH SHAFTS AND THE CHAMBER WALL, A SEALING MEMBER MOUNTED AT EACH INTERSECTION OF THE CHAMBERS WALLS AND POSITIONED TO SEAL THE RESILIENT COVERING WHEN THE COVERING IS BEARING AGAINST IT, EACH SEALING MEMBER INCLUDING A PLANAR SURFACE PERPENDICULAR TO A PLANE THROUGH THE INTERSECTION OF THE CHAMBERS AND THE EDGES OF SAID SURFACES PROVIDING THE SEAL FOR EACH ROLLER, INLET MEANS INCLUDING A PLURALITY OF SMALL BORES EXTENDING FROM END WALL TO END WALL ACROSS ONE SAID SURFACE, OUTLET MEANS INCLUDING A PLURALITY OF SMALL BORES EXTENDING FROM END WALL TO END WALL ACROSS THE OTHER SAID SURFACE, A CIRCULAR GEAR MOUNTED ON EACH SHAFT PROTRUDING BEYOND THE SIDE WALL OF THE CHAMBER AND INTERMESHED TOGETHER FOR CONJOINT ROTATION OF SAID SHAFTS, AND MEANS FOR ROTATING AT LEAST ONE OF SAID SHAFTS.

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