AU597111B2

AU597111B2 - Improvements in reversible displacement pumps

Info

Publication number: AU597111B2
Application number: AU79252/87A
Authority: AU
Inventors: Thomas Evans Ellis
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-09-30
Filing date: 1987-09-30
Publication date: 1990-05-24
Anticipated expiration: 2007-09-30
Also published as: AU7925287A

Description

I

1- COMMONWEALTH OF AUISTRALIA om1 'DOLLAHS PATENTS ACT 1952-62 TE DOLLAR COMPLETE SPECIFICATION 'O RIGUNALE r'AM P TD VALUE O F FOR OFFICE USE: 57 Application Number: Lodged: Class mnt. Class Complete Specification Lodged: Accepted: Published: Prlqrity: Related Airt:

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LODGED AT SUB-OFFICE 3 0 S EP 1987 1 Adelaide TO BE COMPLETED BY APPLICANT Naeappat THOMA,13 EVANS ELLIS 0 Address, of Applicant: Actual Inventor: P.O. Box 13, Forest Range, State of South Australia, Commonwealth of Australia THOMAS EVANS ELLIS Care of R.K. MADDERN

ASSOCIATES,

345 King William Street, Adelaide, S.A. 5000.

Address for Service: Complete Specification for the Invention entitled:, "IMPROVEMENTS IN REVERSIBLE 'YJSPLACEMENT

PUMPS"

The following staternJOnt Is a full description of this Invention, incQ Iding the, best method of performing It known to me.

A

This invention relates to improvements in reversible variable capacity positive displacement pumps or the type described in my now expired Australian patent 447808.

In that patent specification there was disclosed a pump wherein the plurality of circumferentially spaced arms were driven within a cylindrical housing, and between adjacent arms there were arranged flaps which pivoted about axial pivots to vary the displacement volume between the flaps and the inner surface of the housing, the degree of pivoting being controlled by eccentricity of a ring coupled to those flaps by respective links. Each link was pivoted at its radially outer end to a respective flap, and all but one was pivoted to a ring, the one which was not pivoted being an extension of the ring fixed with respect to the ring. Although searches have been made, the Applicant knows of no other prior art pump which utilises that principle.

Pumps made in accordance with that pa.tent have proved particularly successful technically for pumping mary materials which are otherwise difficult to pump, and very efficient in that the horse power requirement for pumping a volume at a rate was less than with most other pumps, for example, about half that required for a centrifugal pump wherein a great deal of "2VS fluid friction is devsloped.

4* The main object of this invention is to provide improvements in such pumps so that they can be manufactured for relatively low cost, and in an embodiment of this invention, improvements 30 comprise a part-circular recess in each respective circumferentially spaced rotor arm, a part-circular lobe on one A end of each flap pivotally engaging a respective part-circular arm recess to constrain the flap to pivotal movement, a partcircular recess ini each respective said flap, and a partcircular lobe on each coupling means pivotally engaging a respective said flap recess, the cross-sectional shape of each respective arm, and of each respective flap being constant throughout its length.

-2- I 7 S 1 With this invention, the rotor arms, flaps, links and inner member, can all be merely lengths of constant section extrusions, although use can alternatively be made of injection moulded parts, which can be of metal or plastics material.

An embodiment of the invention is described hereunder in detail with reference to, and is illustrated in the accompanying drawings, in which: FIG. 1 is a central plan section through a pump, FIG. 2 is a cross-section taken on line 2-2 of FIG. 1 (also showing the sectional plane of FIG. and FIG. 3 is a diagrammatic representation which illustrates an automatic pressure control means.

In this embodiient, a pump 10 has a cylindrical casing 11 with I a generally cylindrical surface 12 except at the location of the ports 13 and 14. Four rotor arms 15 extend from a driven rotor 16 in an axial direction, and are driven for rotation by a driving shaft 17. The outer surfaces 18 of the arns 15 are circularly curved so that the arms 15 make a circumferential i| .seal with the cylindrical surface 12 of the cylindrical casing 2i 11.

Between each pair of adjacent arms 15 there is provided a respective flap 21, each flap 21 having a part-circular section lobe 22 at one end which is pivoted in a part-circularl recess 23 in a respective arm 15, and the other end has a curved surface 24 which is curved cylindrically with respect to the central cylindrical axis of lobe 22 and which bears against a complementary curved surface 25 of an adjacent arm 15. Since this is a wearing part, the end may comprise an adjustable extension which is readily adjusted by slackening clamping screws and sliding outwardly before reclamping. This is not illustrated.

-3- -3 There is provided a freely rotating inner member 28 which however has projecting from part of it a lug 29 which terminates at its end in a circular lobe 30 in one of the flaps 21. The axis of rotation of rotor 16 is designated A, and this is eccentric with respect to the axis of rotation B of the inner member 28, B being a central axis of a secondary shaft 33. The secondary shaft B is movable in a slot 34 in an end plate 35 of the casing 11, and it can be clamped in position, for example, by a nut. However, in the embodiment described, its location is controlled by a lever arm 3.6 pivoted to casing 11 at 37, to vary the degree and direction of eccentricity. As j shown in FIG. 3, lever arm 36 is controlled by an hydraulic cylinder 38 co-acting against spring 39. As pressure from pump 11 expands the piston/cylinder assembly 38, eccentricity reduces and flow reduces as pressure increases.

Referring back to FIG, 1, links 41 join. the inner member 28 to respective ones of the three remaining flaps 21, and upon rotation these links pivot with respect, to inner member 28 and also with respect to flaps 21. Each link 41 has a constant cross-sectional shape and terminates at its ends in circular lobes 42 and 43 and these engage respective recessea in the flaps 21 and tha inner member 28.

The function of the pump is similar to what was described in said patent 447808. Furthermore the efficiency which can be £achieved is similar to that which cL~n be achieved by a pump as described in that patent specification, However, the cost of the pump is very considerably reduced owing to the ability to use constant section members which can be extruded or produced by injection moulding, particularly for the links 41 and the flaps 21, Other elements of the pump can also be produced in this manner, the necessary design changes having been made by thi~s invention.

(1 -4-

Claims

1. Improvements in a pump comprising a driven rotor on a driving shaft and having a plurality of axially extending and circumferentially spaced rotor arms thereon slidably and sealably engaging a cylindrical inner surface of a casing, flaps pivoted each at one end to a r-spective said rotor arm and slidably engaging a curved surface of an adjacent said arm, so that, upon rotation of said rotor, flap movement varies displacement volume between that flap and said cylindrical inner surface, an inner member rotatable about an eccentric secondary shaft parallel to the driving shaft, and links coupling all but one of respective said flaps to the inner member, the improvements comprising a part-circular recess in each respective said circumferentially spaced rotor arm, a part- circular lobe on one end of each said flap pivotally engaging a respective said part-circular arm recess to constrain the flap to pivotal movement, a part-circular recess in each respective said flap, and a part-circular lobe on each of said coupling links pivotally engaging a respective said flap recess, the cross-sectional shape of each respective flap, of each respective arm, of said inner member, and of the coupli, links all being constant throughout their respective lengths.

2. Improvements according to claim 1 further comprising a lug extending outwardly from the inner member in a radial direction and terminating in a part-circular lobe which engages the said recess of said one flap.

3. Improvements according to claim 1 wherein each of said coupling links comprises a part-circular lobe at each respective end, one lobe of each link engaging the said part- circular recess of a flap and the other lobe of that link engaging a similar part-circular recess in the inner member. 4 cn f I ;-a 6 ~I, r I ,-7 -i I i i

4. Improvements according to any preceding claim wherein said casing comprises an end plate having guide surfaces therein which guide the secondary shaft for movement, and means for effecting said secondary shaft movement, said guide surfaces constraining movement of the secondary shaft to control the degree of eccentricity of said secondary shaft with respect to said driving shaft.

Improvements according to claim 4 wherein said eccentricity control means comprises a lever arpm pivoted with respect to said casing and movable by an hydraulic cylinder acting against a spring in such a way that increase of pressure from the pump when applied to the hydraulic cylinder reduces eccentricity and thereby reduces flow.

6. A pump substantially as described in the specification with respect to and as illustrated in the accompanying drawings. t t t 4, 4, 4 Dated this llth day of January THOMAS EVANS ELLIS, By his Patent Attorneys, R.K. MADDERJ ASSOCIATES

1990. p 1t44I £11 4 4 I f jC .c d r 1 h A r