WO1998026178A1

WO1998026178A1 - Diaphragm

Info

Publication number: WO1998026178A1
Application number: PCT/GB1997/003381
Authority: WO
Inventors: Mark Richard Hesketh
Original assignee: Poss Limited
Priority date: 1996-12-09
Filing date: 1997-12-05
Publication date: 1998-06-18
Also published as: AU5403998A; GB9625541D0

Abstract

A diaphragm having a flexible material, Substrate 2, to provide the diaphragm's partition function, made of material dependent upon the usage of the diaphragm, for example Butyl having low gas permeability being suitable for vacuum tube pump applications and the Blocks 1 made of magnetically responsive media, for example a soft magnetic metal allow such as a Nickel/Iron of 50/50 composition attached to the Substrate 2 by techniques such as adhesives or hot in-process bonding, when subject to a remotely applied magnetic field may respond both flexibly and with strong reaction to the magnetic field.

Description

Diaphragm

This invention relates to a diaphragm.

Diaphragms are well known components used as flexible partitions, particularly for pumps and valves. A special type of diaphragm is known which is responsive to an applied magnetic field. However, the flexibility of said diaphragms is usually limited by the means of achieving magnetic response, for example where the diaphragm is compounded with magnetically responsive filler, this addition, usually a metal alloy, increases the stiffness of the diaphragm. Further addition of filler only serves to counter-act the increased availability of magnetic response with a decrease in flexibility.

Another example of diaphragm which is magnetically responsive is one that is actuated by discrete attachment to solenoids, however the area of attachment to said solenoids has movement restricted solely to that defined by the solenoids. The limitation of the flexible response of magnetically responsive diaphragms has prevented their use for such applications as tube pumps. The invention claimed here-in provides a magnetically responsive diaphragm whose flexibility is not restricted by the means of achieving magnetic response.

For the present invention the prior art of the applicant Mark Hesketh, UK Patent Application No GB 9625541.9, 9 December 1996, describes a diaphragm which is constructed of Blocks which are comprised, at least of, a potting material, such as Room Temperature Vulcanising (RTV) Silicone and a magnetically responsive filler, such as Iron Oxide, the said Blocks are attached to a substrate of flexible material, such as Room Temperature Vulcanising (RTV) Silicone, but are not restrictively attached to one another, the diaphragm so formed responds flexibly to a remotely applied magnetic field.

In summary the present invention provides a diaphragm comprised of a flexible material integral with spaced blocks of a magnetically responsive material. The invention will now be described by way of example with reference to the accompanying drawings in which :-

Figure 1 illustrates the diaphragm configured as a tubular diaphragm in side view.

Figure 2 illustrates the diaphragm configured as a tubular diaphragm in cross sectional end view.

Figure 3 illustrates the diaphragm configured as a tubular diaphragm in part view in at rest and expanded states.

Referring to the drawing Figure 1., the diaphragm has been configured as a tube and is shown in side view. The flexible material providing the partition function of the diaphragm is illustrated as Substrate 2. The selection of Substrate 2 material depends upon the usage of the diaphragm, for example Butyl is suitable for vacuum tube pump applications because of the low gas permeability of this elastomer. The Blocks 1 are made of magnetically responsive media, for example from a soft magnetic metal alloy such as a Nickel/Iron of 50/50 composition which may be attached to the Substrate 2 by techniques such as adhesives or hot in-process bonding. The Diaphragm flexibility arises because Substrate 2 is not wholly attached to the Blocks 1but there is an area between the Blocks 1 which allows the Substrate 2 to flex unimpeded because of non- attachment over this area to the Blocks 1.

Figure 2 illustrates the diaphragm configured as a tube in cross sectional view. The substrate 2 provides the sealing, flexible surface of the diaphragm. Another method of manufacture of the diaphragm is to produce the Blocks 1 from a mould tool with cavities to match the Blocks 1 using a premix of a potting material and magnetically responsive material, for example Room Temperature Vulcanising (RTV) Silicone mixed with Iron powder, and then the flexible material is cast over the Blocks 1 , again such as a Room Temperature Vulcanising (RTV) Silicone, to form the substrate 2.

Figure 3 illustrates the diaphragm in part view. This shows how the influence of a remotely applied magnetic field causes the diaphragm to extend circumferentially in the direction of Arrow 4 and shows how the Substrate 2 between the Blocks 1 locally expands to enable flexure of the Diaphragm. The Void 3 enables substantial volume of the Blocks 1 to be presented to the applied magnetic field and hence maximise their magnetic response, whilst also allowing a significant area of the Substrate 2 to react flexibly. This is also illustrated by the changed shape of the diaphragm in the extended position following Arrow 4. The Void 3 may be formed at diaphragm manufacture, for example, by including this feature in the mould tooling should the Blocks 1 be made by moulding or alternatively if the Blocks 1 are made directly from the magnetically responsive media attached to the Substrate 2 then they may be machined, pressed or by similar production techniques formed to this shape.

What I claim as my invention is:

1. A diaphragm comprised of a flexible material integral with spaced blocks of a magnetically responsive material.

2. A diaphragm as claimed in Claim Iwherein the space between the magnetically responsive blocks has a localised void allowing there to be a greater area of flexible material between the blocks.

3. A diaphragm as claimed in Claim Iwherein the magnetically responsive blocks are formed wholly from a magnetically responsive material.

4. A diaphragm as claimed in Claim Iwherein the magnetically responsive blocks are formed from a mix of potting material and a magnetically responsive material.

5. A diaphragm as claimed in any one of Claims 1to 4 wherein the magnetically responsive blocks are adhered to the flexible material.

6. A diaphragm as claimed in any one of Claims 1to 4 wherein the magnetically responsive blocks are hot bonded to the flexible material.

AMENDED CLAIMS

[received by the International Bureau on 20 May 1998 (20.05.98)- original claims 1-6 amended; (1 page)

What I claim as my invention is:

1. A diaphragm comprised of an elastomer integral with spaced blocks of a soft magnetic material.

2. A diaphragm as claimed in Claim Iwherein the space between the soft magnetic blocks has a localised void allowing there to be a greater area of elastomer between the blocks.

3. A diaphragm as claimed in Claim Iwherein the soft magnetic blocks are formed wholly from a soft magnetic material.

4. A diaphragm as claimed in Claim Iwherein the soft magnetic blocks are formed from a mix of potting material and a soft magnetic material.

5. A diaphragm as claimed in any one of Claims 1to 4 wherein the soft magnetic blocks are adhered to the elastomer.

6. A diaphragm as claimed in any one of Claims 1to 4 wherein the soft magnetic blocks are hot bonded to the elastomer.

Claims

STATEMENT UNDER ARTICLE 19

Claims 1 to 6 have been amended by a common change, alteπng the words "magnetically responsive" to "soft magnetic" and the descπptive 'flexible matenal" to "elastomer"

Soft magnetic media of "Nickel/Iron of 50/50 composition" and elastomer of "Butyl" are written as examples of matenal for use in the descnption of PCT/GB 97/03381 and so the descπptive is not at vanance with the claims

Why "magnetically responsive" to "soft magnetic" ?: Refemng to the sole "X" category document, US 3 733616 A (WILLIS F) 22 May 1973, cited in the PCT International Search Report of 25/03/1998, a full review of the descnption and claims qualifies the necessity for magnetic polaπty of the reactive surfaces, in this instance the "shell" and "bag' , and for all possible vanants within the scope of the document This invention demands repulsion of the "bag" from it's rest condition which cannot be achieved by a "soft magnetic" matenal because by definition it need not retain remnant field and so cannot have reverse polaπty to the exciting field

This requirement for magnetic poles is wπtten in the relevant claims 1 , 3-5, either directly or by implication in stating permanent magnets"

Because of the need for magnetic polaπty there is no reference to sort magnetic matenal elsewhere within the body of the descnption However the wording "discrete magnetisable elements such as ferromagnetic filings" column 4, line 6 to7, is ambiguous in this context because soft magnetism does exist within the range of ferromagnetic mateπals , but the 3M "Plastiform" subsequently identified for use, has only been available with permanently magnetisable filler, confirmed directly by 3M to the author, and so the phrase "discrete magnetisable" was just for reference to a flexible media that retains magnetic polaπty, not a soft magnetic media.

The words "magnetically responsive" are inclusive of soft and permanently magnetized media and so the claim is now specific to just "soft magnetic"

Why "flexible material" to "elastomer" ?: This change also addresses the issue of oπginality and inventive step although it narrows the inventive field The said diaphragm may be flexed from it's static condition by an applied magnetic field, irrespective of polaπty, then with field removed returns to static condition because of the restrtutional force of the elastomer Those practiced in the art will recognize this action Although not stated within PCT/GB 97/03381 , I wish by way of illustration of the inventive step with this diaphragm, to draw attention of the reader to other applications by the author, USA Application Number 08/870,156 "Flexible Tube Pump" dated 06/12/97(US) and GB Application Number GB9613429 1 "Flexible Tube Pump" dated 26/06/96(UK) wherein such a diaphragm, in tubular format, is exploited by using magnetic field to attract the diaphragm and then the inherent pull of the elastomeπc substrate of the diaphragm to restore to static state

It is the author's wish that following these modified claims and statement then letter patent may consequentially be granted for the Diaphragm invention per PCT/GB 97/03381