GB2234787A

GB2234787A - Linearly operating pump comprising spiral formations

Info

Publication number: GB2234787A
Application number: GB8913236A
Authority: GB
Inventors: Alexander Grant
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-06-08
Filing date: 1989-06-08
Publication date: 1991-02-13
Anticipated expiration: 2009-06-08
Also published as: GB8913236D0; GB2234787B

Abstract

A linearly operating pump comprises a first, stationery plate and a second movable plate each having an identical, raised, right-angled spiral formation (14, 20) upstanding therefrom. The plates are assembled facing one another with their spirals (14, 20) rotated through 180 degrees relative to one another such that they are interleaved. The topmost surfaces of the spirals (14, 20) are adapted for sliding, sealing contact with the plates and their walls for sliding, sealing contact with one another. The thickness of the walls is equal to half the spacing between corresponding walls of successive turns, and one or more inlet/outlet ports (22, 24) are formed in at least one of the plates adjacent the centre of its spiral. Cyclical, linear movements of the second plate in the directions A, B, C and D causes fluid to be admitted at (26, 28), compressed, and discharged at ports (22, 24). Reversal of the motion causes the device to operate as a vacuum pump. The device is particularly suited to be driven by linear electric motors and is thus suited to microprocessor control. <IMAGE>

Description

'LINEARLY OPERATING PUMP" The present invention relates to a pump for pumping liquids and/or gases, and which may be used to pump the working fluid from a low pressure state to a higher pressure state (ie acting as a compressor pump) or vice versa (ie acting as a vacuum pump).

It is an object of the invention to provide a pump which is particularly simple in construction. Further objects are to provide a pump which does not require any rotary motion, which utilises purely linear actuating means, and which is susceptible of electronic control.

Accordingly, the present invention provides a pump comprising a first, stationary base plate having a planar surface and having a first raised right-angled spiral formation upstanding therefrom; a second, movable plate having a planar surface with a second, right-angled spiral formation substantially identical to said first spiral formation, but rotated through 180 degrees with respect thereto; said first and second plates being arranged with their planar surfaces facing one another such that their respective spiral formations are interleaved with one another, the topmost surfaces thereof being in sliding, sealing contact with the planar surfaces of the respective plates and the walls thereof being adapted for sliding, sealing contact with one another; drive means adapted to move said second plate bi-directionally along first and second axes parallel to the sides of said spiral formations; and at least one inlet/outlet port extending through at least one of said plates to communicate with the interior volume defined between the spiral formations adjacent the centre thereof; and wherein said spiral formations comprise at least one and a quarter turns, the thickness of the walls thereof being equal to half the spacing between corresponding walls of successive turns.

The drive means is preferably adapted to move the second plate in steps, corresponding to the thickness of the spiral walls, one cycle comprising a first step in a first direction along said first axis, a second step in a first direction along said second axis, a third step along said first axis in a direction opposite to that of the first step, and a fourth step along said second axis in a direction opposite to that of the second step, such that any point on the movable plate describes the locus of a rectangle during one cycle, the baseplate returning to its starting position after one cycle.

Preferably, the drive means comprises linear, electric actuating devices. Preferably also, said actuating devices are controlled by a microprocessor or other electronic logic means.

Preferably also, all interengaging corners of the spiral formations are radiused.

Preferably also, said at least one inlet/outlet port is located at a position such that it is not completely closed until the volume of any enclosed space with which it communicates is reduced substantially to zero.

Preferably also, said at least one inlet/outlet port is located at the inside of the angle between the innermost and next-to-innermost limbs of the first spiral formation.

Preferably also, a second inlet/outlet port is provided adjacent the free end of the innermost limb of the first spiral formation.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic side view of a pumping mechanism embodying the present invention; Fig. 2 is a section on line X-X of Fig. 1; Fig. 3 is an enlarged detail view of the central portion of the mechanism as seen in Fig. 2; Fig. 4 is a schematic plan view of the mechanism of Fig. 1; Figs. 5A, 5B, 5C and 5D are a sequence of schematic sectional views illustrating one cycle of operation of the mechanism of Figs. 1 to 4; and Figs. 6A, 6B, 6C ariba 6D are a further sequence of schematic sectional views illustrating one cycle of operation of an alternative embodiment of the invention.

Referring now to Figs. 1 and 2 of the drawings, a pump mechanism embodying the invention comprises a base plate 10 having a planar top surface 12 upon which is machined or otherwise formed a first raised, right-angled spiral formation 14, and a sealing face plate 16 having a planar bottom surface 18 upon which is machined or otherwise formed a second raised right-angled spiral formation 20 substantially identical to the first.

In this example the spirals 14 and 20 each comprise one and a quarter turns (ie five sides), the second spiral 20 being rotated through 180 degrees with respect to the first such that when the base plate 10 and face plate 16 are assembled together the walls of the spirals 14 and 20 interleave with one another as shown. The base plate 10 is fixed in position and the face plate 16 is movable in a plane parallel thereto, the top surfaces of the spirals 14 and 20 being in sliding and sealing engagement with the respective planar surfaces 18 and 12, and the faces of the various walls of the spirals 14 and 20 being adapted for sliding and sealing engagement with one another. The thickness T of the walls of the spirals 14 and 20 correspond to half the spacing S between corresponding walls of successive turns, and the corners thereof are radiused as shown.Ports 22 and 24, which extend through the base plate 10, are formed at points adjacent the centre of the first spiral 14. These will be discussed in more detail below.

As will presently be described in detail, the pump operates by cyclic, linear movements of the face plate 16 such that the working fluid (which, depending upon the application and the construction of the pump, may be gas, liquid or a mixture thereof) may be admitted to, undergo volumetric change within, or be discharged from chambers of continuously varying size and shape formed between the parts of the pump. The required movements may be performed by a variety of actuating mechanisms, however the pump is particularly well suited to actuation by linear electric motors under microprocessor or other electronic control.

The use of magnetic reluctance actuating devices is particularly preferred. Operation of the pump requires bidirectional movement of the face plate 16 along first and second axes parallel to the walls of the spirals 14 and 20, as indicated by arrows F and G in Fig. 4. Block 26 represents control circuitry for controlling the various movements.

Figs. 5A to 5D illustrate the operation of the pump as a compressor during one cycle. In Fig. 5A, fluid is admitted to the mechanism at 26 and 28, whilst the central volume 30 is either empty or filled with fluid from a previous cycle. A first movement in the direction of arrow A, to the position shown in Fig. 5B, closes off the inlets 26 and 28, sealing off the fluid admitted thereby at low pressure, and discharging any fluid in volume 30 through the central port 24. A second movement in the direction of arrow B, to the position shown in Fig. 5C, re-opens the central ports 22 and 24, and reduces the enclosed volume by 37%.A third movement in the direction of arrow C, to the position shown in Fig. 5D, reduces the trapped volume by a further 50%, and also re-opens the inlets 26 and 28 to begin admitting fluid for the next cycle. A fourth movement in the direction of arrow D returns the mechanism to its starting position as in Fig. 5A, reducing the trapped volume by a further 50%, closing central port 22, and admitting further fluid at 26 and 28. The next movement in direction A reduces the trapped volume to zero and discharges any remaining fluid while trapping the newly admitted fluid for the next cycle.

The number and position of the central ports 22 and 24 may vary depending upon the specific application for which the pump is intended. Since liquids may be regarded as incompressible, when the pump is being used for pumping liquids a discharge port must be provided to communicate with any closed chamber which is reduced in volume during a movement of the pump. In the present example this condition is satisfied by the provision of the port 22 adjacent the apex of the radiused end of the innermost limb 30 (see Fig. 3) of the first spiral 14, and the second port 24 at the point where the inner surface of the next-toinnermost limb 32 is tangent to the radiused corner between that limb and the innermost limb 30. These locations also ensure that the ports 22 and 24 do not become completely closed until any closed volume with which they communicate is reduced substantially to zero.Where compressible gases are to be pumped, however, only one, central port such as 24 need be used.

The pump may also operate as a vacuum pump by simply reversing the direction of movement, as may be seen by considering the cycle in the order Fig. 5B, Fig. 5A, Fig.

5D, Fig. 5C.

More than one and a quarter spiral turns may be used, such embodiments being suitable for pumping gases, but not liquids (unless more ports are added at other locations), since the operation of the pump involves volumes being sealed off and reduced while still relatively remote from the centre of the pump. Figs. 6A to 6D illustrate an embodiment having one and a half turns (ie six sides to each spiral). In these figures the fixed spiral is designated 34, the moving spiral 36, the central ports 38 and 40, the outer ports 42 and 44, and the successive movements J, K, L, M.

In this case the newly admitted fluid of one cycle is compressed while fluid from the previous cycle is still being compressed/discharged (ie during movement K from Fig.

6B to Fig. 6C). This overlap between successive cycles increases as the number of turns is increased.

The one and a quarter turn pump will require nonreturn valves (not shown) at its central ports 22 and 24, at least when pumping liquids, however gas pumps will not require such valves except for the most demanding applications. It will also be appreciated that the height of the spiral formations may be varied according to the volumetric requirement of the pump.

Claims

1. A pump comprising a first, stationary base plate having a planar surface and having a first raised right-angled spiral formation upstanding therefrom; a second moveable plate having a planar surface with a second, right-angled spiral formation substantially indentical to said first spiral formation, but rotated through 180 degrees with respect thereto; said first and second plates being arranged with their planar surfaces facing one another such that their respective spiral formations are interleaved with one another, the topmost surfaces thereof being in sliding, sealing contact with the planar surfaces of the respective plates and the walls thereof being adapted for sliding, sealing contact with one another; drive means adapted to move said second plate bi-directionally along first and second axes parallel to the sides of said spiral formations; and at least one inlet/outlet port extending through at least one of said plates to communicate with the interior volume defined between the spiral formations adjacent the centre thereof; and wherein said spiral formations comprise at least one and a quarter turns, the thickness of the walls thereof being equal to half the spacing between corresponding walls of successive turns.

2. A pump as claimed in claim 1 wherein the drive means moves the second plate in steps, corresponding to the thickness of the spiral walls, one cycle comprising a first step in a first direction along said first axis, a second step in a first direction along said second axis, a third step along said first axis in a direction opposite to that of the first step, and a fourth step along said second axis in a direction opposite to that of the second step, such that any point on the movable plate describes the locus of a rectangle during one cycle, the baseplate returning to its starting position after one cycle.

3. A pump as claimed in any preceding claim wherein the drive means comprises linear, electric actuating devices.

4. A pump as claimed in claim 3 wherein the actuating devices are controlled by a microprocessor or other electronic logic means.

5. A pump as claimed in any preceding claim wherein at least some of the interengaging corners of the spiral formations are radiused.

,~.

6. A pump as claimed in any preceding claim wherein said at least one inlet/outlet port is located at a position such that it is not completely closed until the volume of any enclosed space with which it communicates is reduced substantially to zero.

7. A pump as claimed in claim 6 wherein said at least one inlet/outlet port is located at the inside of the angle between the innermost and next-to-innermost limbs of the first spiral formation.

8. A pump as claimed in any preceding claim wherein a second inlet/outlet port is provided adjacent the free end of the innermost limb of the first spiral formation.

9. A pump substantially as hereinbefore described with reference to Figures 1 to 5.

10. A pump substantially as hereinbefore described with reference to Figure 6.