US20170030368A1

US20170030368A1 - Monoblock axial pump

Info

Publication number: US20170030368A1
Application number: US14/813,090
Authority: US
Inventors: John McIntyre
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-07-29
Filing date: 2015-07-29
Publication date: 2017-02-02

Abstract

A pump device includes an axially rotating tube having an internal impeller affixed. Each opposite end of the tube has an inlet and outlet so that a powering means to axially engage the tube results in moving of a fluid. The supports or monoblocks at each end of the tube provide for sealing of the fluid passing through the tube and bearing support for the rotating tube. Quick pump disassembly and assembly and the feature of simple interchangeability of impeller types result in a variety of fluids to be pumped and fast and easy pump maintenance.

Description

FIELD OF THE INVENTION

The invention is in the field of pumps, and more particularly axial flow pumps of the type having a fixed impeller within an axially rotating tube having inlet and outlet openings at opposite ends.

BACKGROUND OF THE INVENTION AND DESCRIPTION OF RELATED ART

The term “pump” is used herein to refer to a device comprising a rotating tube having a fixed impeller secured therein. As a powering means causes the tube to rotate, an inlet and outlet stream results within the tube to cause intake, compression, and the exhaust of a fluid medium such as a gas, a liquid, or combination thereof. Further, the term “pump” embraces a reverse operation in which fluid drives an impeller rather than the impeller driving the fluid, i.e., in reverse operation most every pump is effectively a motor. The term “monoblock” is used herein to refer to the unitized, or one piece, construction of the member that holds the rotating tube, incorporates the tube seal, and provides a bearing surface for the rotating tube while also providing the means for expeditious serviceability.
An example of an axial flow pump is shown in U.S. Pat. No. 3,163,120 to J. A. Richards. The Richards patent and present commercially available axial flow pumps differ from the invention being they all have in common impellers driven independently of the housings encapsulating them. It is relatively easy to seal tubing and piping that are not rotating with an impeller fixed therein. In comparison to the invention, disassembly time for maintenance is longer and therefore changing impellers for various applications and cleaning has associated labor and time penalties and therefore limiting applications.
An example of an axial pump with a rotating housing and impeller configuration is shown in U.S. Pat. No. 3,655,294 to Thatcher. The Thatcher patent shows an axially rotating ductwork with a substantially developed impeller, connected to ductwork for support. The patent does not fully address the difficulties of dissembling the rotating ductwork and impeller for maintenance and the complexity in sealing the rotating ductwork.

BRIEF SUMMARY OF THE INVENTION

The present invention comprises a pump structure benefiting from the variety of impeller types and exploits the potential of an axially rotating tube pump design. The rotating tube has bearing and seal surfaces and includes the means to secure an impeller. Impellers not requiring powering means associated with shafts and the streamlining as a result can be beneficial to flow characteristics. The invention advances this concept further to provide the means for quick pump disassembly and provide the means to have the rotating tube adaptable to a variety of impellers. The invention creates a new range of applications for the field of axial flow pumps.
In the illustrative embodiment, the rotating tube fits into two opposing monoblocks. The monoblocks provide both a bearing for the rotating tube and seal the rotating tube to allow the pumping of compressed gases or liquids through the tube all the while maintaining a leak free environment.
In a further illustrative embodiment, the opposing monoblocks provide both the structure for the tube during rotation and also allow for quick disassembly of the rotating tube and impeller and general maintenance.
In another illustrative embodiment, the rotating tube both affixes the impeller and allows the impeller to be easily removed from the tube for cleaning or substitution.
In accordance with a preferred embodiment hereafter described, the rotating tube is secured by the opposing monoblocks that also provide the rotary seals of the rotating tube and the tube bearing surfaces. The features of the invention also provide the means to disconnect the rotating tube from the structure easily and dependent upon scale of the invention, without tools and quickly. Moreover, due to these features, impellers can be also cleaned and/or switched easily creating new opportunities for axial flow pumps. As will be understood from the following specification, the pump of the present invention can be scaled to various capacities with pump components being constructed using materials or combination of materials including a hard dense plastic such as UHMWPE (Ultra-high-molecular-weight polyethylene) or softer easier to machine but possessing higher chemical resistance PTFE (Polytetrafluoroethylene), composites, ceramics, and/or metals.
These and other features and advantages of the invention will become apparent from the detailed description below, in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the pump assembly.

FIGS. 2A-2C are front and side plan views of the monoblock rotating tube supports.

FIGS. 3A-3D are perspective and sectional views of the tube and impeller options.

For purposes of clarity and brevity, like elements and components will bear the same designations and numbering throughout the Figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the complete pump assembly is shown having a base (1) with pockets (2) that accommodate a monoblock (3) at each end of the rotating tube (4). The rotating tube (4) provides housing for an impeller and is equipped with a gear (5) mated to the motor gear (6) of the motor (7). Each monoblock (3) is drilled and tapped for a tube fitting (8) with tubing (9) fitted thereon. Also each monoblock (3) has a seal (10), shown with the o-ring (36) component, for the rotating tube and an internal bearing surface for the rotating tube (4). The motor (7) provides powering means causing the rotating tube (4) to rotate, an inlet and outlet stream result as indicated by directional arrows. Note the rotating tube (4) member referred to for the purposes recited could also be a cylinder, hollow rod or similar structure member. Furthermore, the pump base (1) with similar shaped monoblock pockets (2) aligned at close tolerances is provided for a slide-in fit insertion to hold monoblocks (3). This fit is referred also as a transition fit or location fit for when it is desirable that a piece to be held precisely, yet not so tightly that it cannot be disassembled. Appropriately, this fit will not alter the correct positioning of the two monoblocks with rotating tube inserted therein to allow alignment of the all the bearing surfaces.
The rotating tube (4) must move freely without any binding from misalignment to assure maximum life of seal and bearing surfaces. When the monoblocks (3) are removed from the pump base (1), the rotating tube (4) can be simply grasped and pulled out to remove from the monoblocks (3) or in the case of assembling the pump can be reinserted (pushed-in) into each monoblock (3) with the monoblocks (3) then put back into the pump base (1). Since both monoblocks (3) are a duplicate of each other and with the rotating tube (4) once inserted, the assembly remains in perpendicular alignment and having said location and fit feature in the pump base (1) assures this alignment will not alter when the monoblocks (3) are set into the pump base pockets (2). After inserting the monoblocks (3) and rotating tube assembly (4) into the pump base pockets (2), the rotating tube gear (5) and motor gear (6) location needs to be checked and adjusted if necessary to assure the correct meshing of the gears. Under normal conditions, once the initial setup of the motor is performed, no further adjustment should be required. Rotating tube (4) drive means can also be friction drive, pulley arrangement or other gearing configurations such as a worm gear. When the invention is scaled-up, e.g. a large increase in motor horsepower as compared to a laboratory or metering pump application, then a method to lock the monoblocks (3) into the pump base (1) is warranted. The powering means of an electric motor can be substituted with a gasoline, diesel or natural gas motor for the industrial version of the invention. These powering means are pertinent to disaster relief and remote locations without electricity for water transferring.
Referring now to FIGS. 2A-2C, three embodiments are shown of the monoblocks from side and front views. All three embodiments are drilled and tapped (11) for a tube fitting that provides a connection for either inlet or outlet tubing.
In FIG. 2A, the monoblock (3) is shown specifically fabricated from a single piece of plastic material. For example, a rectangular piece of PTFE is machined to provide an integral bearing surface (12) for the rotating tube and a groove (13) is machined to have an o-ring compressed therein to create an elastomeric energized seal for the rotating tube. Since this seal configuration is in the absence of pressure assistance, the o-ring or a spring must be positioned in the groove to cause circumferential pressure on the rotating tube outside diameter to effect a seal (10). Also note the internal bushing (14) also provides a stop (15) to prevent lateral travel of rotating tube because of the smaller diameter provision for the tube fitting. An undercut (16) is made between the internal bushing (14) and the seal lip (17) to allow flexing of the material once energized by the o-ring or spring to effect sealing of the rotating shaft.
Selection of the monoblock (3) construction material is based on several factors such as economy, the fluid or gas being pumped, and whether or not to use a material that will be sacrificial, specifically the seal and bearing surfaces. In a one-piece monolithic monoblock, the term “sacrificial” relates to using a material that is the wearing component of the pump. For instance, a monoblock (3) made entirely of PTFE and a rotating tube made of type 316 stainless steel will allow the pumping of the majority of chemicals on the condition that the tube fittings and the tubing are also made of similar materials. Relatively inexpensive and easy to machine, a PTFE monoblock (3) will after a period of time have both its seal and bushing wear to a point where the monoblock will require replacement. Substituting UHMWPE for a PTFE monoblock (3) is feasible and it should wear longer but the fluids and or gases are limited as compared to using PTFE and is harder to machine. A stainless steel monoblock will last even longer but will be more expensive to machine than a plastic monoblock (3) and will require the additions of a commercial seal and bearing or bushing.
In addition, larger capacity pumps may require additional seal and bearings components such as bronze bushings, ball bearings and seals such as standard radial and mechanical seals. Also, the monoblock structure can be a variety of geometric shapes such as cylindrical. With miniature pump versions, another means to secure the monoblock to the pump base would be provide a location or dowel pin and accompanying hole in either the monoblock or the pump base instead of incorporating pump base pockets (2).
Shown in FIG. 2B is a monoblock (3) machined with pockets for off the shelf components such as a bushing or bearing and a radial seal. The figure illustrates a bushing or bearing pocket (18) and a pocket for a seal (19). Unlike the seal and bushing being machined from a single piece of plastic to comprise a monoblock (3), the positioning of the pocket for a seal (19) and bearing pocket (18) are reversed. This component placement is a traditional arrangement in pump design which protects the bearing from contact with the liquid or gas being pumped or compressed which does not matter in the unitary construction version of the monoblock (3). An optional void (20) cavity machined between the pocket for a seal (19) and drilled and tapped (11) provision for a tube fitting can be utilized if the type of seal used requires any flow pressure to enhance sealing of the radial surfaces. High operating pressures are possible with this embodiment.
FIG. 2C illustrates a method to produce a groove (13) for an o-ring to energize the seal for the rotating tube in a monoblock (3). Shown is a rotary shaft seal pocket (21) comprised of a path (22) machined with a round or ball burr-like cutter (23) to provide a round contour to fit and locate an o-ring to energize a radial seal for a shaft. The plunge entry and exiting point of the ball cutter (23) is indicated by (25). The seal pocket (21) will conform to fit an oversized o-ring that will uniformly deliver pressure or energize the rotary seal to effectively seal a rotating tube or a shaft for other applications requiring rotary seals. In the event that an o-ring has to be removed from the o-ring groove (13) the entry point (25) provides an access port for o-ring removal lessening damage potential. Again, the undercut (16) is made between the internal bushing (14) and the seal lip (17) to allow flexing of the material once energized by the o-ring or spring to effect sealing of the rotating shaft independent of the bushing. The term “energized” refers to either a compressed o-ring or spring that exert force upon its encapsulation to effect sealing contact with a radial shaft or in case of the invention, the rotating tube.
Referring to FIG. 3A, the term “impeller” for the purposes recited could be from a variety of impeller members such as but not limited to a screw-type impeller, propeller, auger, barrel-type, helical (24) or spiral (28) all within the scope of the invention and all are applicable as to be fixed in the rotating tube (4). The helical impeller (24) example of the fixed impeller screws itself into inlet fluid stream and pushes it to the outlet to increase suction at the inlet, as the abovementioned impeller types.
Under normal conditions, providing there is a stop to affix the impeller (24) inside the rotating tube (4), the impeller will lodge itself utilizing the impeller's own force in a fluid stream to hold it in place. One simple method to provide the stop is to fabricate a protrusion (27) into the rotating tube (4). Another method to provide a stop for the impeller is to indent a slight deformation in the rotating tube, as long as the rotating tube remains straight, that will cause the impeller to lodge itself with no further travel up to that stop. It is imperative to design the stop as to prevent the impeller traveling into the monoblock under operating conditions. To remove the impeller from the tube, being careful not to damage the rotating tube ends (29), tap on a soft or wooden surface and the impeller should fall out if not frozen which would then require a drift to dislodge it.
FIG. 3B shows additional features of the impeller and rotating tube. When using a heavy wall tube or machined cylinder for a rotating tube member to house an impeller, the rotating tube (4) and impeller (24) can be manufactured with a matching taper (30) to allow the impeller to lodge itself inside the tapered bore of the rotating member utilizing the impeller's own twisting force in a fluid stream to hold it in place. However, this feature would not work by itself in retaining an impeller under the circumstances of reversing the direction of pump flow. It is essential to have highly polished surfaces (31) on every rotating tube (4) outside diameter that are in contact with the bearing surfaces and seal. The polished ends (29) of the rotating tube will also have a smooth polished rounded edge (32) as not tear or scratch the seal lip upon insertion of the rotating tube into each monoblock. An optional thrust washer (33) may be placed at one or both ends of the rotating tube (4) to act as an alternative to monoblock wear and even though carefully fitted, it will not be a leak proof seal. The washer (33) would have the same outside diameter as the rotating tube (4) and be flat and parallel and can be made from a variety of materials such as PTFE graphite composite. The monoblock can easily accommodate the washer because it is the same outside diameter as the rotating tube. For standardizing the pump components, the rotating tube used with the washer provision can be produced slightly shorter to specifically compensate for the washer thickness.
FIG. 3C illustrates the impeller option to form integral indentations (34) on the outside diameter of rotating tube (4) that provide the physical impression of impeller vanes (35) located on the inside diameter of the rotating tube (4) wall. This provides the same propulsion effect as having an independent impeller. Likewise, a metal or plastic rotating tube and impeller combination (37) could be molded or cast with the facsimile of the abovementioned indentations as a one-piece unit. Furthermore, this rotating tube and impeller combination (37) would have a greater potential for variations such as larger vanes (38) because of not being limited by a press on impeller of the abovementioned integral indentations (34) into a metal rotating tube (4). If this rotating tube was made a plastic such as from PTFE, then stainless steel bushings could provide the tube bearing support. In addition, these bushings could also be an integral member machined in a stainless steel monoblock with only a commercially available rotary shaft seal being required for rotating tube sealing.
FIG. 3D shows the rotating tube (4) having both the highly polished surfaces (31) and grooves (39) that act as an impeller creating sealing action by controlling pump leakage of fluid by centrifugal force. The centrifugal pressure keeps in liquids moving through the rotating tube and lessens or eliminates leakage out of the monoblock while the tube is rotating. The tube highly polished surfaces (31) make contact with the monoblock bearing surfaces as previously disclosed. Alternatively, the grooves as shown could be a spiral or helical groove configuration.
It will finally be understood that the disclosed embodiments represent presently preferred forms of the invention, but are intended to be explanatory rather than limiting of the invention. Reasonable variation and modification of the invention as disclosed in the foregoing disclosure and drawings are possible without departing from the scope of invention. The scope of the invention is defined by the following claims.

Claims

What is claimed:

1. A pump comprising:

the rotating tube having the internal impeller,

the monoblock supporting each end of the rotating tube,

the monoblock providing sealing and bearing surfaces with the rotating tube,

the monoblock providing connections for inlet or outlet tubing,

the monoblock secured to the pump base, and

the motor providing axial rotation of the tube.

2. As defined in claim 1, wherein the preferred means to secure each monoblock is the pocket in the pump base having the slide-in fit maintaining the alignment of the rotating tube.

3. As defined in claim 1, wherein the monoblock provides for pullout release and push-in insertion of the rotating tube.

4. As defined in claim 1, wherein the monoblock having the rotary shaft seal pocket comprised of the path machined with the ball cutter to provide a round contour to fit and locate an o-ring to energize the radial seal for the rotating tube.

5. As defined in claim 1, wherein the rotating tube wall having integral indentations to provide impeller vanes to provide the same effect as an impeller.

6. As defined in claim 1, wherein the molded or cast metal or plastic axially rotating tube with tubing wall having integral indentations or vanes to provide the same effect as having a separate impeller.

7. As defined in claim 1, wherein the rotating tube and impeller having the matching taper to provide the impeller to become fixed inside the rotating tube during pumping rotation.

8. As defined in claim 1, wherein the monoblock integral bearing surface for the rotating tube is substituted with a bronze type bushing, ball or roller bearing.

9. As defined in claim 1, wherein the monoblock integral seal for the rotating tube is substituted with a radial seal or mechanical seal.

10. As defined in claim 1, wherein the monoblock is made from PTFE or UHMWPE.

11. As defined in claim 1, wherein the rotating tube having grooves at or near the rotating tube bearing surfaces provides the impeller creating sealing action by controlling leaking of fluid by centrifugal force.

12. (canceled)

13. A pump component comprising the rotating tube providing the same effect as having a separate impeller thereby:

the tube wall with integral indentations to provide impeller vanes or

the tube of molded or cast metal or plastic having integral indentations or vanes.

14. (canceled)

15. A pump component comprising the rotating tube having grooves at or near the rotating tube bearing surfaces provides the impeller creating sealing action by controlling leakage of fluid by centrifugal force.