WO1999024716A1

WO1999024716A1 - Pump

Info

Publication number: WO1999024716A1
Application number: PCT/NZ1998/000164
Authority: WO
Inventors: Michael John Triezenberg
Original assignee: Jenkins, Graeme, Reid
Priority date: 1997-11-10
Filing date: 1998-11-10
Publication date: 1999-05-20
Also published as: AU1265299A

Abstract

A rotary pump has a chamber with a cross section defined by a pair of intersecting arcs which create a pair of cusps; a sun rotor (32) sweeps the cusps and has a pair of arcuate recesses (40) in the circumference which accommodate a pair of planet rotors (18, 20). The assembly is driven by an epicyclic gear train. The gears have adjustment to advance or retard the drive in order to fill and empty the working spaces (42) of the pump efficiently. The planet rotor shape is adapted for sealing in the cusp zone. The pump parts are reduced in volume so as to give a working space which is 60-70 % of the chamber volume. Versions with 2 and 3 planet rotors are described. Use as a hydraulic motor.

Description

PUMP

This invention concerns pumps which are modifiable for use as motors .

Much of the world's electricity is used to pump water and this pump is suited to this purpose. Those skilled in the art will recognise its various uses including a general purpose fluid pump. In this specification we describe the pump as a blower for an i.c motor. Vehicle exhaust Emission Standards call for control of the air input at induction. This pump has a positive displacement action and delivers about 1 bar.

Superchargers with positive displacement action are easily damaged by solid contaminants. The present type of pump is not so vulnerable but maximising its operation is difficult.

US 3 363 606 describes an i.c. rotary motor utilising a chamber with a cross-section featuring six intersecting arcs arranged around a series of associated nodes . A primary rotor defines a pair of diametrical recesses for a pair of bar-shaped orbital rotors. The rotors are driven by the compression and working phases of the primary rotor, assisted by the orbital rotors. The problems of a corresponding pump design are somewhat different. US 3 330 215 YAMANE is a pump in which two crescent shaped rotors revolve in the paired recesses of a biflabellate central rotor. The sun rotor rotates in a chamber of elliptical section with one extensive node which houses the pump ports. While the theory of operation is clear it is not clear whether such a pump can be made to run.

If an i.c engine as above is used as the pattern for a pump, the rotors may be driven by a train of spur gears receiving power from the pump shaft . Even though the planet motion is simple the efficiency of the pump is spoiled by poor timing . This lost motion causes failure to maintain compression and release it at the precise moment in the pump cycle. It is not possible to look inside the pump to check the operation visually.

This invention addresses this and other transmission problems .

This invention provides a pump comprising a chamber with a cross section defined by a pair of intersecting arcs, said intersection creating a pair of cusps; a sun rotor centrally mounted in_ the pump chamber capable of sweeping the cusps; at least two arcuate pockets in the circumference of the sun rotor,- a planet rotor mounted for rotation in each pocket serving to sweep both the pocket and the chamber wall inlet and outlet means in the chamber wall and drive means which impart a planet motion to the planet rotors, and rotation to the sun rotor.

In this specification "cusp" means a symmetrical peak formed by two like intersecting curves and variations thereof for example a flat peak an arcuate peak and a convex peak .

The invention also provides a pump wherein the chamber contains three rotors disposed mutually at 120 °. When a triple rotor pump conveys fluid, smooth pulsation free fluid flow is obtained.

The pump may instead be used as a hydraulic motor because there is no lockup position. The intake is always allowing reaction against the rotors and producing leverage through the components to the input sha t . Such pumps may be made of traditional pump metals namely alloy steels such as stainless steels, bronze and titanium. The pump is capable of operating as a motor with a supply cf waste gas such as steam or hydrogen sulphide or nitrogen.

The invention also provides a pump wherein the chamber contains two sets of rotors but one set suffices.

According to a further feature of the invention the drive from the sun rotor shaft to the planet rotors is via a gear train the rotational position of which is jig set to control backlash and then attached to he pump as a uni . The teeth of all the gears may be shallow in order to control lost motion more efficiently.

The pinion may be of soft material and the meshing gearwheel may be of hard material .

The drive means may have a drive member which supports mutually parallel planet rotor shafts, one for each rotor which extend through the chamber in order to engage and drive an epicyclic gear train assembly: the gear train assembly is coupled to the sun rotor which is coupled to the assembly and projects into the chamber and in use the assembly rotates the planet rotors en the planet rotor shafts .

The assembly may have a gear train outside the chamber in which in use rotates both the sun rotor and the planet rotors inside the chamber and an adjuster mounted on a pinion supporting member of the assembly which supporting member is rotatable axially to advance or retard the rotation of a pinion by about a tooth whereby opening and closing of the chamber by the planet rotors is facilitated.

The supporting member may be a shaft and face mount for the pinion and the pinion has concentric slots to take fasteners .

The housing preferably contains an annulus with a circular seal which retains the oil in the part of the housing which contains the gear train. The seal contacts the end wall of the housing and prevents the oil escaping into the chamber. The train is lubricated by a splash.

The leading edges of the rotors may have replaceable tips. The gear train may rotate in a drive housing adjacent the chamber and clockwise/anticlockwise adjustment of the drive is achievable from outside the housing.

The housing may have a wall which supports a gear train idler pinion and the wall defines an aperture close to the axis of rotation of the pinion, through which an adjuster extends which advances or retards the gearwheel .

The wall supports the gear train assembly and is presentable to the chamber in a pre-timed condition within the housing for coupling to the planet rotor shafts.

The inlets may be supplied through an inlet manifold and the outlets discharge into an outlet manifold, the manifolds imposing different standing wavelengths on the gas flows .

The housing wall may have a central oil collecting sump and a plurality of oil grooves radiating from the sump beyond the pumping of the gears in the train. As the cusps are placed closer together and the size of the rotors are reduced the working volume of the pump may be increased. The volume occupied by the working parts may therefore be reduced to 60-70 percent of the chamber volume .

The inlets may be paired and separate outlets provided or both may be paired. The manifold into which they discharge or enter may be external i.e as a bolt on moulding or casting or within a jacket surrounding the chamber. The inlets and outlets may have a leading edge and a trailing edge in relation to the sweep of the rotors and the leading edge may have a profile which exposes the outlets and inlets progressively.

The planet rotor shape is a feature of the invention. The planet rotor is polygonal in section being defined by a pair of mutually opposite convex sides and a pair of mutually opposite concave sides , each concave side being the product of two equal intersecting arcs which intersection creates a raised portion which seals against the cusp when the ends of the rotor sweep the chamber wall on both sides of the cusp, the radii of the arcs lying on opposite sides of the axis joining the pair of cusps.

One embodiment of the invention is now described with reference to the accompanying drawings in which FIG 1 is a plan of the planetary motion of the rotors within the chamber.

FIG 2 is a plan of the drive to a rotor

FIG 3-10 are plans of the rotor positions showing the progression of the motion of the rotors.

FIG 11 is a plan of a version with three planetary rotors .

Fig 12 is a diagrammatic section through the train and through the housing showing the manner o f adjusting the gear train;

Fig 13 is a diagram of the slotted pinion and mount

Fig 14 is a diagram of the inlet/outlet manifolds

Fig 15 is a diagrammatic clcse up of the planet rotor overlying the ports .

Referring to FIG 1 the metal pump housing 2 has a waisted chamber 4 the section of which is defined by two compoud arcs 8. The wall 6 has a pair of diametrically opposed cusps 10, which are modified by two arcuate zones 12 which give a near elliptical shape on the axis lying at 90° to the cusps 10. Radii data is as follows: Rl R2 R3 R4 llx 6x llx/2 6x

A central drive shaft 14 has a V-pulley 16. A pair of planet rotors 18,20 are mounted on planet rotary plate 22. Plate 22 is rotated by a shaft coupler. The planet rotors extend through the chamber and end in stub shafts which project into planet spur gears 28. The pair of spur gears 28 turn in ball bearings diametrically located in the sun rotary plate 30. The sun rotary plate 30 is a running fit between the cusps 8. The chamber wall 6 is machined to permit the circular , rolling motion of the sun rotor 32 and planet rotors to sweep the wall and maintain a clearance of 0.002 in.

In Figs 1 the triple contact between the planet rotor and the cusp zone can be seen. The concave face of the planet rotor overlies the peak of the cusp. This feature ensures that air from the working space is vented efficiently and not added and subtracted to the working volume as in the close prior art .

In Fig 3 the planetary spur gears 28 are shown in train with the sun spur gear 34 via idler pinions 36. The sun spur gear 34 is stationary and mounted in end plate 38. The train maintains a 1:1 ratio. A seal plate 40 sits between the end plate 38 and the sun rotor plate 30. The sun rotor 32 is biflabellate (double fan shaped) in section and rotates with the sun rotary plate. The sun rotor has a pair of arcuate recesses 40 (best seen in Figs 3-10) which are swept by the planetary rotors as the latter rotate. In doing so each creates a pocket 42 in which air can be inducted and compressed.

Wall 4 in the arcuate zone 12 has a row of outlets 44 and a row of inlets 46. All the ports are tapered for the initial 8 degrees of rotor advance in order to allow gradual pressure change. In Fig 15 the outlets which discharge air at 1 bar are shown discharging half the output in to a short manifold 48 and a long manifold 50 which join at a connector plate 52.

The planet rotor shape is seen close up in FIG 15. The peak 10 of the rotor is slightly concave and the concave face of the rotor describes two equal intersecting arcs which produce a small prominence 58 which corresponds to the peak concavity. The rotor body overlies and seals the ports 44 and 46. The radii of the arcs lie on opposite sides of axis A

OPERATION The rotation of the sun and planet rotors is seen beginning in Fig 3 where the sun rotor spans the cusps and the planet rotors divide the inlet side and outlet side into halves, with the lower rotor ready to complete an expulsion, and the upper rotor inducing a charge. As the sun rotor progresses anti clockwise through 45 degrees, the inlet space enlarges drawing in more gas while the lower rotor expels the last of the gas.

A further 45 degrees brings the pump to Fig 5 condition where a portion of the chamber contents is trapped by rotor . This is temporary and the portion rejoins the main charge as the sun rotor progresses.

In Fig 6 the rotor progresses toward the position in Fig 7 wherein the positions of Fig 3 reappear. Likewise the positions of 8 9 and 10 repeat those of 4 5 and 6. The motion of the rotors sweeps gas through the pump continuously. A 11 pump has a volume cf 21/rev. The pump operates without peripheral rotor seals. The clearance at design temperature is 0.002 in. For this reason the inlet σas is filtered to manufacturers soecification .

The assembly of Fig 12 is prepared for operation by using a set up jig. This has three radial bores to view the three rotors and a thimble adjuster to adjust gear rotation. The gears namely pinion, idler and spur are of like diameter all with shallow teeth. Timing is set up on the back side of the tooth for the pumping motion. Overrun turns the same gearwheel on the front side of the tooth As it is not possible to see through the chamber wall adjusting the drive to exactly match rotations of the rotors is difficult. The housing is detachable from the chamber exposing the end wall of the chamber and the rotor shaf s. The gear train is mounted on stub shafts 26 and end wall 38. The train can be rotated at will so that the drive to the two planet rotors is pre-timed. When the housing is offered up, the coupling does not disturb the setup. Final adjustment is made via the eccentric pin 54.

As a blower the device delivers 1-2 bar at 4000rpm attaining a steady 60-90 degrees C. As a vacuum pump, the assembly pulls 25in Hg at 1500 rpm.

We have found the advantages of the above embodiment to be

1. the parts are conveniently made as NC components or parted from extrusions .

2. the pump expands uniformly preserving design clearances .

3. the pump sweeps twice its internal volume per revolution

Claims

1 A pump comprising a chamber with a cross section defined by a pair of intersecting substantially elliptical arcs, said intersection creating a pair of cusps; a sun rotor centrally mounted in the pump chamber capable of sweeping the cusps; at least two arcuate pockets in the circumference of the sun rotor; a planet rotor mounted for rotation in each pocket serving to sweep both the pocket and the chamber wall; inlet and outlet means in the chamber wall and drive means which impart a planet motion to the planet rotors and rotation to the sun rotor.

2 A pump as claimed in claim 1 wherein the sun rotor defines three equi spaced arcuate pockets

3 A pump as claimed in any one of claims 1-3 wherein the drive means has a drive member which supports mutually parallel planet rotor shafts, one for each rotor which extend throuσh the chamber in order to engage and drive an epicyclic gear train assembly: the gear train assembly is coupled to the sun rotor which is mounted on the assembly and projects into the chamber and in use the assembly rotates the planet rotors on the planet rotor shafts .

4 A pump as claimed in claim 4 wherein the assembly has a gear train outside the chamber which in use rotates both the sun rotor and the planet rotors inside the chamber and an adjuster mounted on a pinion supporting member of the assembly which supporting member is rotatable axially to advance or retard the rotation of a pinion by about a tooth whereby opening and closing of the chamber by the planet rotors is facilitated

5 A pump as claimed in claim 5 wherein the supporting member is a shaft and face mount for the pinion and the pinion has concentric slots to take fasteners.

6 A pump as claimed in any one of the preceding claims wherein the leading edges of the rotors have replaceable tips .

7 A pump as claimed in any one of the preceding claims wherein the gear train rotates in a drive housing adjacent the chamber and clockwise/anticlockwise adjustment of the drive is achievable from outside the housing . 8 A pump as claimed in any one of claims 8 wherein the housing has a wall which supports a gear train idler pinion and the wall defines an aperture close to the axis of rotation of the gearwheel, through which an adjuster extends in order to advance and retard the rotation of the gearwheel.

9 A pump as claimed in claims 9-11 wherein the wall supports the gear train assembly and is presentable to the chamber in a pre-timed condition within the housing for coupling to the planet rotor shafts.

10 A pump as claimed in any one of claims 1 wherein the inlets are supplied through an inlet manifold and the outlets discharge into an outlet manifold, the manifolds imposing different standing wavelengths on the gas flows.

11 A pump as claimed in claim 9 or 10 wherein the housing wall has a central oil collecting sump and a plurality of oil grooves radiating from the sump beyond the pumping of the gears in the train.

12 A pump as claimed in any one of the preceding claims where the intersecting arcs which define the cross- section decreases in radius in the zone of the intersection.

13 A pump as claimed in any one of the preceding claims wherein the planet rotors are quadrilateral in section being defined by a pair of concave arcs and a pair of mutually opposite convex arcs.

14 A pump as claimed in claim 14 wherein a side of the each planet rotor sweeps the intersection zone at three axes simultaneously on one of the concave arcs defining said side as the planet rotor sweeps the intersection.

15 A pump as claimed in any one of the preceding claims wherein the inlets and outlets have a leading edge and a trailing edge in relation to the sweep of the rotors and the leading edge has a profile which exposes the outlets and inlets progressively.

16 A pump as claimed in claim 15 wherein the initial 5- 10 deg of rotation give progressive fluid transfer.

17 A pump as claimed in any one of the preceding claims wherein the rotors are diminished in volume in order to maintain 60-70 percent of the chamber volume as working space .

18 A pump as claimed in any one of the preceding claims wherein the planet rotor is polygonal in section being defined by a pair of mutually opposite convex sides and a pair of mutually opposite concave sides , each concave side being the product of two equal intersecting arcs which intersection creates a raised portion which seals against the cusp when the ends of the rotor sweep the chamber wall on both sides of the cusp, the radii of the arcs lying on opposite sides of the axis joining the pair of cusps .