Fluid pump comprising a conical body precessed about its apex by a driver connected by a drive shaft to a boss eccentrically carried by a drive plate such that a rotating pump chamber is formed by a flexible membrane attached to the conical body

Abstract

A fluid pump comprising a conical body having an apex, a base and defining a lateral surface between the apex and base; a mating surface defined by a pump plate; a flexible membrane having a first face comprising a first part which is attached to at least a portion of the lateral surface of the conical body and a second part which is free, and having a second, opposite face secured around its periphery to the mating surface; and a driver adapted to drive the conical body; wherein the mating surface includes a fluid inlet port and a fluid outlet port, the fluid inlet port being spaced from the fluid outlet port; the driver includes a drive shaft and a drive plate carried by the distal end of the drive shaft, wherein the drive plate is inclined with respect to a plane normal to a longitudinal axis of the drive shaft such that the drive plate drives the conical body to precess about its apex in use such that at any given time the flexible membrane defines a contact portion in contact with the mating surface where the lateral surface of the conical body is adjacent to the mating surface, and defines a non-contact portion which is spaced from the mating surface; a pump chamber is defined by a cavity formed between the non-contact portion of the flexible membrane and the mating surface; the pump chamber rotates about an axis of the mating surface as the conical body precesses about its apex; and fluid is drawn into the pump chamber as it passes the fluid inlet port and the fluid is urged out of the pump chamber as it passes the fluid outlet port.

Claims

1. A fluid pump comprising a conical body having an apex and a base, wherein the conical body further defines a lateral surface between the apex and base; a mating surface defined by a pump plate; a flexible membrane having a first face comprising a first part which is attached to at least a portion of the lateral surface of the conical body and a second part which is free, and having a second, opposite face secured around its periphery to the mating surface; and a driver adapted to drive the conical body; wherein the mating surface includes a fluid inlet port and a fluid outlet port, the fluid inlet port being spaced from the fluid outlet port; the driver includes a drive shaft that is rotatable about a longitudinal axis, a drive plate carried eccentrically by a distal end of the drive shaft, and a rotational coupling comprising a first coupling element and a second coupling element, with the first coupling element being rotatable relative to the second coupling element, wherein the drive plate includes a first planar surface which is parallel to a plane normal to the longitudinal axis of the drive shaft and an opposed second planar surface which is inclined with respect to the plane normal to the longitudinal axis of the drive shaft, wherein the first planar surface has projecting from it a boss which is eccentrically carried by the first planar surface and wherein the boss connects the drive plate to the drive shaft, and the opposed second planar surface faces the conical body, the first coupling element of the rotational coupling being in contact with the opposed second planar surface of the drive plate and the second coupling element of the rotational coupling being in contact with the base of the conical body, whereby the drive plate rotates relative to the base of the conical body and the driver drives the conical body to precess about its apex in use such that at any given time the flexible membrane defines a contact portion in contact with the mating surface where the lateral surface of the conical body is adjacent to the mating surface, and defines a non-contact portion which is spaced from the mating surface; a pump chamber is defined by a cavity formed between the non-contact portion of the flexible membrane and the mating surface; the pump chamber rotates about an axis of the mating surface as the conical body precesses about its apex; and fluid is drawn into the pump chamber as it passes the fluid inlet port and the fluid is urged out of the pump chamber as it passes the fluid outlet port.

2. A fluid pump according to claim 1, wherein the pump further includes a barrier located between the fluid inlet port and the fluid outlet port, wherein the barrier is adapted to provide a one-way flow from the fluid inlet port to the fluid outlet port.

3. A fluid pump according to claim 2, wherein the barrier is a radial barrier and fluidly separates the fluid inlet port from the fluid outlet port along a radius of a circle defined by the precession of the conical body about its apex.

4. A fluid pump according to claim 1, wherein the flexible membrane is an elastomer.

5. A fluid pump according to claim 4, wherein the flexible membrane is a thermoplastic elastomer.

6. A fluid pump according to claim 1, wherein the mating surface is substantially planar.

7. A fluid pump according to claim 1, wherein the mating surface comprises a resiliently deformable material.

8. A fluid pump according to claim 7, wherein the resiliently deformable material is an elastomer.

9. A fluid pump according to claim 8, wherein the mating surface and the flexible membrane are independently formed from the same elastomeric material.

10. A fluid pump according to claim 1, wherein an external cone angle defined between the lateral surface of the conical body and a plane normal to the axis of the conical body is from 1 to 45.

11. A fluid pump according to claim 10, wherein the external cone angle is from 1 to 20.

12. A fluid pump according to claim 1, wherein the driver includes an electric motor.

13. A fluid pump according to claim 1, wherein the an angle of incline of the opposed second planar surface of the drive plate is substantially equal to an external cone angle defined between the lateral surface of the conical body and a plane normal to the axis of the conical body.

Description

(1) An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

(2) FIG. 1 is an exploded perspective view of a fluid pump according to a first embodiment of the invention;

(3) FIG. 2 is an exploded perspective view of the conical body shown in FIG. 1; and

(4) FIG. 3 is a side elevational view of the conical body, bearing and drive plate of the pump shown in FIG. 1.

(5) For the avoidance of doubt, the skilled person will appreciate that in this specification, the terms up, down, front, rear, upper, lower, width, etc. refer to the orientation of the components as found in the example when configured for normal use as shown in the Figures.

(6) FIG. 1 shows a fluid pump 2 according to the invention. A pump plate formed from an end plate 4 and an end plate elastomeric layer 6, the end plate elastomeric layer 6 being adhered to the end plate 4 and defining the mating surface 8. The elastomeric layer is formed from a silicone polymer. The end plate 4 further defines a pair of apertures 10, 12 into which are secured by any suitable means an inlet port 14 and an outlet port 16. The end plate elastomeric layer 6 includes corresponding apertures 18, 20.

(7) A conical body 22, 26 both defines a pump chamber and drives it between the inlet port 14 and the outlet port 16. This is described in more detail below. The conical body 22, 26 has an external cone angle of 2.5. Thus, it has an internal cone angle of 175. It will be appreciated that the cone angles may be selected according to the desired flow rate and pumping pressure of the pump. The conical body 22, 26 is formed as a two-part component, wherein the first part 22 of the conical body (from the apex to a point between the apex and the base) is formed from a relatively hard polymeric material, such as nylon, and a second part 26 of the conical body (a frustoconical section from the first part to the base of the conical body) is formed from aluminium. The conical body defines a boss 24 projecting axially rearwards. The aluminium outer ring 26 (the second part of the conical body) defines an aperture which locates the ring over an axially inner portion of the boss 24.

(8) As shown in FIG. 2, the first part 22 of the conical body defines a radial slot 23 and the aluminium outer ring 26 defines a corresponding radial slot 27.

(9) A flexible membrane 28 has a first face 29 with a first part 29a adhered to the first part 22 of the conical body 22, 26, and a second face 31 that is secured to the end plate elastomeric layer 6 around its peripheral edge. A second part 29b of the first face 29 of the flexible membrane 28 is not secured to the aluminium outer ring 26. The flexible membrane 28 is also formed from a silicone polymer and is secured to the end plate elastomeric layer 6 via a combination of an adhesive and a securing frame 30.

(10) In an alternative embodiment, the flexible membrane may be attached to the conical body via a mechanical fixing, for example, the flexible membrane may be trapped between first and second portions of the conical body, or the flexible membrane may be attached to the conical body via a combination of a chemical adhesive and a mechanical bond, such as a portion of the flexible membrane being secured via a friction fit or interference fit within a corresponding channel defined by the conical body.

(11) The securing frame 30 is formed from aluminium and defines a peripheral portion 32 which surrounds in use the aluminium outer ring 26 of the conical body and which sandwiches the peripheral edge portions of the end plate elastomeric layer 6 and the flexible membrane 28 between it and the end plate 4. The securing frame 30 further defines a tongue 34 which extends from one of the peripheral sides of the frame 30 towards its centre. The tongue 34 prevents a portion of the flexible membrane 28 located adjacent to it from displacement away from the end plate elastomeric layer 6. By clamping a portion of the flexible membrane 28 to the end plate elastomeric layer 6, a fluid seal between the membrane 28 and the elastomeric layer 6 is formed which provides a radial barrier. The radial barrier is located between the inlet port 14 and the outlet port 16.

(12) The tongue is sized and shaped to fit within the radial slots 23, 27 formed in the first part 22 of the conical body and the outer ring 26 as the conical body precesses about its apex.

(13) As can be seen in FIG. 3, the conical body 22, 26 is driven to precess about its apex by an inclined drive plate 36 formed from brass. The drive plate 36 is inclined with respect to plane A by 2.5 such that the conical body 22, 26 is arranged to have one side parallel to the end plate 4 and an opposite side which is inclined by 5 to the end plate 4. The drive plate 36 includes a drive plate boss 38 which extends axially away from the conical body 22, 26. Located between the drive plate 36 and the outer ring 26 is a bearing 40 including two spaced plates separated by a plurality of ball bearings which allows the drive plate 36 to rotate relative to the outer ring 26 of the conical body 22, 26. The bearing 40 is located around the boss 24 of the conical body 22, 26.

(14) In an alternative embodiment, the drive plate and bearing may be located within a cup-shaped element or the cup-shaped element may have an inclined or angled base which forms the inclined drive plate and the bearing may be located within the inclined cup-shaped element.

(15) As can be seen from FIGS. 1 and 3, the drive plate boss 38 is located off-centre with respect to the rear of the drive plate 36, with centerline 39a of drive plate boss 38 being spaced from centerline 39b of drive plate 36. This results in an eccentric arrangement between the bearing 40 and the drive plate 36. This eccentric arrangement of the relatively heavy brass material has the effect of counterbalancing the motion of the conical body 22, 26.

(16) A pump housing 42 is provided which houses the pump assembly components and to which the end plate 4 is secured via screws 44. A second bearing 46 is provided between the rear of the drive plate and the pump housing 42 such that the drive plate 36 is able to rotate relative to the pump housing 42. The second bearing 46 is located in position via the drive plate boss 38.

(17) An electric motor 48, which is housed in a motor housing 50 is arranged to rotate the drive plate 36. The electric motor 48 includes a drive shaft 49 defining a longitudinal axis 3, which drive shaft 49 passes through a drive shaft aperture 52 defined by the pump housing 42 and is secured to the drive plate 36, as illustrated by the dashed longitudinal axis line 3.

(18) In use, the electric motor drives the drive plate 36 to rotate. The rotation of the drive plate 36 is transferred via the bearing 40 to the conical body 22, 26. The rotation of the drive plate 36 via the bearing 40 results in the precession of the conical body 22, 26 about its apex. It will be noted that the conical body 22, 26 does not rotate. This will be understood by the fact that the tongue 34 enters and exits the radial slots 23, 27 on each complete rotation of the drive plate 36.

(19) At any given time, a portion of the conical body 22, 26 is arranged to be parallel to the end plate 4 and urges a corresponding portion of the flexible membrane 28 into sealing engagement with the end plate elastomeric layer 6. At the same time, a second portion of the conical body 22, 26 is inclined away from the end plate 4 and this urges a corresponding portion of the flexible membrane 28 away from the end plate elastomeric layer 6. The gap between the spaced apart portions of the flexible membrane 28 and the end plate elastomeric layer 6 defines a cavity which forms a pump chamber. The pump chamber is closed on one hand by the barrier defined by the tongue urging the flexible membrane 28 into sealing engagement with the end plate elastomeric layer 6, and on the other hand by the portion of the conical body 22, 26 which also urges the flexible membrane 28 into sealing engagement with the end plate elastomeric layer 6. The precession of the conical body 22, 26 causes the pump chamber to rotate about an axis defined by the apex of the conical body 22, 26. As the chamber passes the inlet port 14, the action of the flexible membrane 28 being urged away from the end plate elastomeric layer 6 generates a partial vacuum within the pump chamber and this draws fluid into the chamber from the inlet port 14. The barrier prevents fluid being drawn from the outlet port 16. The precession of the conical body 22, 26 pushes the pump chamber around its circular path until it reaches the outlet port. As the contact portion of the conical body 22, 26 approaches the barrier, the pressure within the chamber increases and the fluid held within the chamber is expelled through the outlet port 16. The cycle is then repeated.