GB2426552A

GB2426552A - Sinusoidal rotary pump

Info

Publication number: GB2426552A
Application number: GB0510502A
Authority: GB
Inventors: David John Clements
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-05-24
Filing date: 2005-05-24
Publication date: 2006-11-29
Also published as: GB0510502D0

Abstract

A sinusoidal rotary pump features a hollow housing 1 of cylindrical shape, with a plurality of internal projections 5 directed towards a central axis of the housing 1, and accommodating a shaft (fig.2A) which also has projections (13,fig.2A), interstitial to those of the housing. The shaft has some degree of freedom of rotary motion around a central axis. Under operation of the pump, the shaft rotates sinusoidally, and is aided by at least one non-return valve arrangement 2 or similar, to pump fluid in, through and out of the housing. Also disclosed is an associated transmission device which converts rotary drive into sinusoidal motion, powering the action of the pump.

Description

A Positive Displacement Centrifugal Pump. The Positive Displacement Centrifugal Pump combines the attributes of both centrifugal and positive displacement pump mechanisms in such a way as to enhance the performance characteristics of each whilst minimizing the operational limitations of both. The result is a smaller and lighter working unit capable of delivering a substantially higher through-flow into a moderate restraining pressure than is achievable with piston or centrifugal pump types. The centrifugal pump is a simple device consisting of a radially-vaned rotor enclosed in a casing which allows entry of the pumped fluid into the enclosure at the centerline of vane rotation, from whence it is thrown by the rotating vane under the influence of the centrifugal force so produced, to emerge at an exit port located on the outer periphery of the enclosure. There are no control valves and the output fluid velocity is essentially dependant on the strength of the centrifugal force and to the restrictions imposed on the output, most significantly by back-pressure. This can cause the output flow to stall completely at relatively low pressure levels.Though simple and compact, the pump is only capable of delivering high volumes of output flow at very low pressure In contrast the piston pump, by virtue of one-way valves in line with inlet and outlet fluid flow paths and the constantly changing contained cylinder volume produced by the reciprocating piston, is capable of delivering predictable flow at pressures limited only by the power of the motor which drives it and its own robustness. However, the contained volume of the piston and cylinder, (and thus its delivery capacity), represents a relatively small fraction of the pump assembly mass and overall size since the pump requires connection rods, crankshaft, flywheel, counter-weighting and mounting castings etc. in order to operate.In terms of its mass and volume therefore, the piston pump has the capability of delivering only a modest rate of output flow at a relatively high pressure. The Positive Displacement Centrifugal Pump contains the essential features of both pump types within a single rotating cylinder of which a substantial portion of its contained volume is dedicated to the fluid which is to be forcefully passed through it. This is achieved by ensuring that the component which produces the enclosed volume changes, acts on fluid contained in enclosures both sides of it, in contrast to the piston type pump which acts on fluid on one side only. Because all of the moving components it contains, including the pumped fluid, rotate at the same mean rate as the containing cylinder, it serves as its own vibration-damping flywheel. Efficient fluid ingestion is ensured by the combination of simultaneous centrifugal effects and the increasing volume of the chamber into which it passes via a one-way valve.As the rotating cycle progresses, this chamber reduces in volume, forcing its contents under pressure via a one-way outlet valve into a discharge port. Fluid discharge is further enhanced by centrifugal effects due to the outlet port being located near the outer periphery of the rotating cylinder. The process is repeated at multiple chambers within the drum as rotation progresses, each one normally completing two full cycles per drum revolution. In applications where the fluid is to be discharged at low pressure, possibly to atmosphere, the centrifugal effect of the pump is dominant and both input and output valves may remain open throughout a major part of each operating cycle. Under such circumstances the pump will deliver a substantially higher flow rate than the product of swept volume and cyclic frequency would otherwise dictate for each completed revolution of the cylinder. In applications where the fluid is being discharged into an increasing back-pressure environment, (as is the case when charging a fluid reservoir), when ihe receiving vessel is empty and the output back-pressure is insignificant, the centrifugal effect will dominate and outflow will be at a maximum. As the fluid level in the reservoir increases, so too does the back-pressure acting at the pump output. This causes the contribution of centrifugal forces upon the flow rate to diminish. As reservoir filling continues, there comes a point when centrifugal effects alone will not support pump outflow and at this stage and beyond, the pump delivery rate will be a direct function of swept volume and positive displacement only. However centrifugal effects will still continue to aid fluid ingestion and discharge, thus enhancing pump efficiency.The maximum back-pressure level against which the pump remains capable of operating will therefore be limited only by its robustness and the power of the driving source. When compared to conventional reciprocating piston and centrifugal pump types, the Positive Displacement Centrifugal Pump is therefore capable of delivering a combination of a vastly increased fluid flow rate and at higher pressure than a conventional unit of similar weight and volume. Such advantages render the design highly suited to a range of gas and liquid pumping applications, as summarized below a). As a means of delivering compressed air in very large quantities and at moderate pressure into an inherently leaky environment such as that required of the lifting fans in hovercraft etc. The units currently employed for this task are usually based on a combination of the principles of operation of the centrifugal fan and the aircraft propeller These are generally relatively inefficient and commonly consume more power in lifting the vessel than is required to propel it.Weight and the space occupied by the pumping mechanism is also of great significance in such applications. Here further advantage is to be gained by use of the compact Positive Displacement Centrifugal Pump design. b). As a means of jetting water in large quantities at moderate pressure in applications such as water craft propulsion and mobile or portable applications where the weight and size of the pump unit is required to be as small as possible for a given output requirement. c). As a means of pumping bulk liquids into tanks, reservoirs and along pipelines. The Positive Displacement Centrifugal Pump is comprised of the following major parts 1. The Drum Cylinder and Primary Drive Coupling. 2. The Rotor Assembly and Secondary Drive Shaft. 3. The Transmission System (linking primary and secondary drive connection points). 4. A Motive Power Source (applied to the primary drive). 1. The Drum Cylinder and Primary Drive Coupling. The arrangement of this assembly is shown at Figure 1. In the example shown, the cylindrical casing (1) is divided internally into 3 regularly spaced wedge shaped segments (5), both flat sides of each are fitted with a one-way flap valve or similar (2). Each valve allows fluid flow to occur into the body of each segment but prevents flow occurring in the opposite direction. The downstream chamber of each valve links directly to a flow-outlet bore (3) which extends via a cylinder-sealing end-plate (6) when assembled, to emerge at through-hole (9) in one end plate. Both end plates (6) and (10) are secured by bolts through holes (7) or (12) into threaded holes (4) in the cylinder rim. Connection to the primary drive source is made via a gearwheel or chain and sprocket linkage fixed to end plate (10). Bearing bushes (8) and (11) accommodate the ends of shaft (14) of the rotor assembly shown at Figure 2. 2. The Rotor Assembly and Secondary Drive Shaft. The arrangement is shown at Figures 2A and 2B. The assembly is dimensioned to fit snugly between the wedge shaped segments (5) of the drum cylinder, except that a rotational gap is formed between each of the wedge shaped segments (5) and (13) when the rotor assembly is inserted. For example, should all 6 of the wedge shaped segments have an included radial angle of 35 degrees, there would be a mean radial separation between each wedge segment of 25 degrees. In the example, it is therefore possible to move the rotor shaft relative to the drum cylinder back and forth through 50 degrees of rotation. According to the pump design, such relative movement, or stroke, will be used to provide positive fluid displacement. With reference to Figures 2A and 2B, shaft end (14) has a large diameter internal bore which extends along most of the shaft length, the open end of which serves as the fluid inlet point of the pump (15). Radial bores, of which (21) is an example, intersect the shaft bore extending it into the body of each wedge shaped segment (13). Figure 2B shows the arrangement more clearly. Shaft bore (a) extends through radial bore (b) to cross-bore (c) into one-way valve pockets (d) of rotor segment (e). At Figure 2A, both flat side faces of each wedge segment are fitted with one-way valves (16). These allow free flow of fluid through the internal passages to emerge from each segment (13) but prevent flow in the reverse direction. The location of bearing bushes (8) and (11) when the pump unit is fully assembled, is shown at (22). 3. The Transmission System. The general arrangement is shown at Figure 3. The purpose of the transmission system is to provide two separate but interconnected output drive sources which are synchronous at each completed revolution, but whose rate of advance, one to the other within a single revolution varies in a sinusoidal manner. Bearing blocks (25) and motive power source (23) are rigidly secured to a fixed base. Rotating shafts (26) and (29) are aligned to be parallel to each other but offset one from the other. The individual shafts arc connected by a pair of universal joints (27) and (28), and these are therefore retained at a fixed angle relative to the alignment of the shafts. The yokes at the junction of universal joints (27) and (28) are rotationally aligned at 90 degrees one to the other.The extent of angular misalignment between the universal joint pair and the shafts (26) and (29) determines the magnitude of the sinusoidal variation which results within a single revolution of the transmission system. When arrangements are made to vary this offset whilst the pump is operating, it provides a means of changing the pump stroke and thus the output delivery. Sprocket (24) is directly coupled to the motive power source and linked by a chain to a similar sprocket fixed to the cylinder barrel (1) This constitutes the Primary Drive. Sprocket (30) is similarly linked to a sprocket fixed to the Rotor Assembly shaft which constitutes the Secondary Drive. Gear wheels may be substituted as a means of transmission, but it is essential with either method, that the same gear ratio is employed for both primary and secondary drive paths. 4. The Positive Displacement Centrifugal Pump - Complete Assembly. Figure 4 shows the complete assembly of an in-line pump configuration, where inlet and outflow fluid paths are on the same axis. Where the application permits, outflow could be alternatively routed through the outer face, much like the configuration of the conventional centrifugal pump. The chassis unit (32) encloses the Transmission Unit and provides a rigid mounting for the main bearing blocks (37) to which all rotating pump components are secured. It also serves as a mounting for the motive power source (23) which is directly coupled to the transmission system and the primary drive path via a chain or gearwheel linkage (35).The secondary drive of the transmission system is similarly linked by chain or gearwheel (33) to the rotor shaft. According to the pump design it is essential that the gear ratios of the primary and secondary drive systems are identical. The nature of the transmission system is to produce two complete cycles of lag and lead at the secondary drive per complete revolution of the primary drive shaft. Depending upon the particular application, a common gear ratio of other than 1 to 1 may be advantageous to optimize the centrifugal and positive displacement characteristics of the pump mechanism.The correct timing of transmission linkages is essential in order to ensure that the centralized positions of wedge shaped segments (13) between those of the cylinder drum (5), coincides with a zero lag or lead point of the transmission system rotation cycle. The fluid inlet point is shown at (36). With the in-line configuration the cylinder drum (31 ), is connected to the cone nozzle (34) which directs the pump output to the discharge point (38). When motive power is applied, the transmission system produces rotation of both drum and rotor shaft at the same average rotational rate, but that motion which is applied to the rotor shaft lags and leads the drum in a cyclic manner within each completed revolution. This causes the wedge shaped segments of the rotor to oscillate back and forth between the adjacent cylinder drum segments. Fach internal chamber so formed, therefore changes volume in a cyclic fashion as the drum turns, half of the chambers decreasing in volume as the other half increase and vice versa. As each chamber increases its void volume, a partial vacuum is created which causes the one-way valve associated with the rotor segment to open, drawing fluid into the void from the input point. Inflow is assisted by the centrifugal effect of the rotating body.At this time, each of the one-way valves associated with the drum segments are reverse-biased and therefore remain firmly closed. As the rotation cycle continues, the void volume of the sample chamber reaches a maximum and then begins to decrease which causes a positive pressure to be created. The one-way valve associated with the rotor segment now closes preventing reverse flow. Simultaneously, the drum segment valve, now forward-biased opens causing pressurized fluid to be ejected at the output point of the pump. The efficient ejection is further assisted by centrifugal effects within the pump body. The process is continuously repeated at all voids between cylinder drum and rotor segments, half of the void number discharging fluid as the other half ingest it. In applications where very large quantities of air outflow is required at relatively low pressure, output one-way valves may be relocated outside the cylinder drum confines in order to maximize the contained volume and hence the pump capacity. Internal volume can be further increased by replacing the segment mounted rotor valves with a sleeve valve arrangement incorporated within the rotor shaft.

Claims

Claims.

1. A rotary pump which is suitable for pumping either gasses or homogenous liquids and combines the high volume delivery characteristic of the centrifugal pump with the high pressure capability of the positive displacement type of pump, within a single compact casing.

2. A fluid pump which according to claim 1 incorporates a means by which a rotating drum with internal interlaced and sealing vanes which are alternately fixed to the drum, or form part of a separately driven rotor shaft, are caused to oscillate relative to each other whilst both continuously revolve in the same direction.

3. According to the foregoing claims, a fluid pump which incorporates a dual outputdrive transmission system to provide the means by which the same average rotation rate of drum and rotor is achieved at the two outputs, which is also coincident with a cyclic lag and lead (stroke) feature of one drive path relative to the other.

4. A fluid pump in accordance with the foregoing claims which incorporates two rigidly connected universal joints, the outer ends of each being connected to offset but parallel transmission shafts, the universal joints being mutually orientated such as to accentuate a lead and lag cyclic effect when rotated, one shaft relative to the other.

5. A fluid pump in accordance with the claim 4, whereby the extent of offset between parallel input and output shafts determines the magnitude of cyclic lead and lag variation within a single rotation, which property can be used as a means of pump fluid output control.

6. A fluid pump in accordance with the foregoing claims, which by virtue of the continuous rotation of all components associated with the production of pressurised fluid flow, uses centrifugal force to enhance fluid induction and output flow, thereby improving efficiency.

7. A fluid pump in accordance with the foregoing claims, in which enclosures formed within the rotating pump casing are caused to cyclically increase and diminish their contained volume, thereby in conjunction with suitably placed one-way valves, provide positive fluid displacement.

8. A fluid pump in accordance with the foregoing claims, which by virtue of the continuous rotation of all components associated with pumping the fluid, provides its own vibration-damping momentum, eliminating the need for a flywheel.

9. A fluid pump in accordance with the foregoing claims, the structure of which allows for a larger portion of its contained volume to be devoted to fluid pumping than is practical with common forms of moderate pressure, high flow-rate pumps, thereby providing size and space benefits.

10. A fluid pump in accordance with the foregoing claims, which has a suitable structure, mechanical linkage and principle of operation, to allow it to be adapted by the use of suitable mechanically operated control valves, into a positive displacement, low pressure, high through-flow, pressure-to-rotary-motion energyconverter suitable for hydro-electric applications such as tidal barriers, locks and weirs etc.

11. A fluid pump in accordance with the foregoing claims, which has a suitable structure and motive characteristics, to allow the design to be adapted as a compact rotary internal combustion engine.