WO2000014408A1

WO2000014408A1 - Electromagnetic pump

Info

Publication number: WO2000014408A1
Application number: PCT/GB1999/002810
Authority: WO
Inventors: Stephen Anthony Brown
Original assignee: Stephen Anthony Brown
Priority date: 1998-09-08
Filing date: 1999-09-08
Publication date: 2000-03-16
Also published as: AU5750499A; GB9819534D0

Abstract

A fluid displacer comprises a generally tubular conduit (2) for a fluid (3) and at least one generally annular electromagnetic drive coil (4) surrounds the conduit. At least one fluid mover in a form of two aperture discs (7) is provided, the discs supporting a permanent magnet (5) between them. A resilient disc (1) is secured to the outer face of disc (7) at the downstream end of the fluid mover and can flex away from apertures (8) in the disc (7) to allow fluid to pass through the disc on the return stroke of the fluid mover, but seals those apertures in the drive direction of the fluid mover.

Description

ELECTROMAGNETIC PUMP

The present invention is an electromagnetic displacer for fluids. Thus it may take the form of a fluid pump, by means of which a fluid is transferred along a fluid conduit, or of a drive motor for a vehicle or vessel, which effects linear movement of the latter over or through a fluid by moving the fluid continuously through the displacer. The invention will be described with reference to^' its use as a fluid pump but is equally applicable to its operation as a drive motor.

Most currently available fluid pumps are designed to perform specific fluid-transfer functions. It is usually important for the particular pumping function to be operated to maximum efficiency and this requirement tends to lead to the design of pumps suitable for performing a very restricted range of functions. This lack of versatility may often mean that, when the flow rate or other requirements of a given pumping operation are changed, it is necessary to remove the pump and replace it with a pump which is better adapted to the requirements of the new operation. Thus there is a longstanding need for a pump having a greater versatility, that is, one with a good range of operating characteristics and which can more readily be adjusted to meet a range of different operating requirements .

With such requirements in mind, it has been proposed to provide a pump in which the pumping stroke is powered electromagnetically and the return stroke of the magnetic core is achieved by means of a return spring. Pumps of this type tend to be noisy in operation as a consequence of the impact of the magnetic core and of the valve upon closing against one end of the enclosed pump.

One proposal for reducing such noise is described in United States Patent Specification No 4252505. However the pump described in that specification, which pump is electromagnetically powered, retains the disadvantageous feature of prior fluid pumps that it is of mechanically complex design and inflexible in use.

Thus there remains a real need for a fluid displacer which is of relatively simple design and which is more versatile in use and in its operating conditions. It is an object of the present invention to provide a fluid displacer which is better able to meet those requirements than many currently available fluid displacers.

The fluid displacer according to the present invention comprises a generally tubular conduit for the fluid, at least one generally annular electromagnetic drive surrounding that conduit, at least one fluid mover disposed for axial movement within said generally tubular conduit and supporting a permanent magnetic core, and at least one flow biasing element within said conduit .

In operation of the fluid displacer, the reciprocal movement of the fluid mover within the conduit is effected solely by alternating the field operated by the annular electromagnetic drive, which in turn drives the permanent magnetic core in alternating directions. In combination with the flow biasing element, this produces a flow of the fluid in the conduit in the single direction determined by that element. The fact that the reversal of the movement of the fluid mover is effected electromagnetically gives the beneficial result that the impact noise which is common in operation of many other types of fluid pumps is completely avoided.

The generally tubular fluid conduit will usually be of rotationally uniform cross-section but this is not an essential characteristic of the conduit and the cross-section may be of different shape if circumstances require it. The fluid conduit is surrounded by a generally annular electromagnetic drive. That drive may be mounted directly upon the external surface of the fluid conduit or may be spaced outwardly from the conduit. A single such electromagnetic drive will suffice for many purposes but it is particularly preferred to provide at least two such drives, spaced apart in the direction of the length of the fluid conduit. The two or more such drives may be activated similarly and at the same time or in the same drive direction in sequence (to produce a longer drive stroke) or in alternating sequence to give a desired reciprocating pumping action.

Within the fluid conduit is disposed the fluid mover or movers, which in turn support a permanent magnetic core. By way of example, the fluid mover may simply comprise a pair or more of apertured discs, spaced apart in the direction of the length of the conduit and supporting between them the permanent magnetic core, for example an elongate permanent magnet disposed along the axis of the condui .

Cooperating with the fluid mover is a flow biasing element, also disposed within the conduit, to allow the flow of fluid in one direction in response to movement of the fluid mover in that direction and discouraging or preferably preventing flow of fluid in the reverse direction. Typically, the flow biasing element is a one-way valve, which may be mounted independently of the fluid mover but may advantageously be mounted upon the fluid mover to move with the latter within the fluid conduit . The fluid biasing element may be a conventional spring-biased valve but in a particularly preferred form the use of such a mechanical means as a spring is avoided by forming the fluid biasing element in a generally flat shape, for example a disc, of a flexible material, more preferably a resilient flexible material; such a flexible disc may be mounted directly upon the fluid mover, to cover one or more apertures in the latter when it is moving in the fluid- moving direction. If desired, in particular where the fluid displacer is to perform a relatively heavy duty, for example where the fluid output pressure is to be significantly higher than the fluid inlet pressure, an additional fluid biasing element, for example a valve, may advantageously be provided. That additional valve may be disposed at a fixed position within the fluid conduit, to permit fluid flow in the same direction as the first fluid biasing element but provide additional resistance to reverse fluid flow, or indeed reverse movement of the fluid mover when the electromagnetic drive is switched off.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, which illustrate one preferred embodiment of the fluid displacer according to the present invention and wherein: -

Fig. 1 is a longitudinal sectional view of the fluid displacer; and

Fig. 2 is an elevation of a support disc from the fluid displacer of Fig. 1.

The illustrated fluid displacer comprises a uniformly tubular conduit 2 through which fluid 3 is to be driven in the direction indicated by the arrow 6. In this form of the invention, the conduit 2 is encircled by two electromagnetic drive coils 4, 4, spaced apart by a short distance along the length of the conduit .

Within the conduit 2 is disposed a fluid mover in the form of two apertured discs 7, 7, which support between them, along the axis of the conduit, a permanent magnet 5. Secured to the outer face of the disc 7 at the downstream end of the fluid mover is a flexible-, resilient disc 1, which by flexing away from the apertures 8 in the disc allows fluid to pass through the disc on the return stroke of the fluid mover but seals those apertures in the drive direction of the fluid mover. Thus by controlled reciprocative activation of the drive coils 4, the fluid mover in turn moves in the drive and recovery directions along the conduit 2, thereby moving fluid in the direction of the arrow 6.

Operation of the electromagnetic drive coils in the desired sequence may advantageously be achieved by means of a controller (not shown) , by means of which the polarity of the electromagnets may be changed and the frequency and pattern of the changes may be set. The controller may also determine the level of electromagnetic power applied. In these ways, the performance of the fluid displacer, in particular its pumping characteristics, may be modified as desired. For example, the fluid flow rate and the flow pressure may be modified in this way.

Furthermore, the fluid drive characteristics of the unit may be modified by increasing the number of drive coils 4 and/or by varying their relative spacing apart .

Two or more of the fluid displacers according to the present invention may be used together. For example, interconnected in series, they may combine to produce a higher-pressure driving force. Linked together in parallel, but operating out of phase, they may produce greater and/or smoother fluid flow rates .

In yet another form of the present invention, the fluid displacer may be installed in or on a vehicle or vessel suspended in the fluid, to drive the vehicle or vessel through the fluid, in the manner of a drive motor, by virtue of the same relative movement of the fluid through the fluid conduit.

Claims

₁. A fluid displacer comprising a generally tubular conduit for a fluid, at least one generally annular electromagnetic drive surrounding that conduit, at least one fluid mover disposed for axial movement within said generally tubular conduit and supporting a permanent magnetic core, and at least one flow biasing element within said conduit.

2. A fluid displacer according to claim 1, wherein the generally tubular fluid conduit is of rotationally uniform cross-section.

3. A fluid displacer according to claim 1 or 2 , wherein the generally annular electromagnetic drive is mounted directly upon the external surface of the fluid conduit .

4. A fluid displacer according to any one of the preceding claims, wherein the generally annular electromagnetic drive is spaced outwardly from the conduit .

5. A fluid displacer according to any one of the preceding claims, comprising at least two said generally annular electromagnetic drives, spaced apart in the direction of the length of the fluid conduit .

6. A fluid displacer according to claim 5, wherein the two or more said drives are activated similarly and at the same time .

7. A fluid displacer according to claim 5, wherein the two or more said drives are activated in the same drive direction in sequence .

8. A fluid displacer according to claim 5, wherein the two or more said drives are activated in alternating sequence to give a desired reciprocating pumping action.

9. A fluid displacer according to any one of the preceding claims, wherein the fluid mover comprises a pair or more of apertured discs, spaced apart in the direction of the length of the conduit and supporting between them the permanent magnetic core .

10. A fluid displacer according to any one of the preceding claims, wherein the or each flow biasing element is a one-way valve .

11. A fluid displacer according to claim 10, wherein the or each fluid biasing element is a spring-biased valve.

12. A fluid displacer according to any one of the preceding claims, wherein the or each said flow biasing element is mounted independently of the fluid mover.

13. A fluid displacer according to any one of claims 1 to 10, wherein the or each flow biasing element is mounted upon the fluid mover to move with the latter within the fluid conduit.

14. A fluid displacer according to any one of the preceding claims, wherein the or each fluid biasing element is formed in a generally flat shape.

15. A fluid displacer according to claim 14, wherein the or each fluid biasing element is formed of a resilient flexible material .

16. A fluid displacer substantially as hereinbefore described with reference to the accompanying drawings .