GB2422900A - Actuator device - Google Patents

Actuator device Download PDF

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Publication number
GB2422900A
GB2422900A GB0501252A GB0501252A GB2422900A GB 2422900 A GB2422900 A GB 2422900A GB 0501252 A GB0501252 A GB 0501252A GB 0501252 A GB0501252 A GB 0501252A GB 2422900 A GB2422900 A GB 2422900A
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United Kingdom
Prior art keywords
swelling
linked
concentration
cross
branched
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB0501252A
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GB0501252D0 (en
Inventor
Mark Christopher Turpin
Janet Marie Turpin
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Individual
Original Assignee
Individual
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Filing date
Publication date
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Priority to GB0501252A priority Critical patent/GB2422900A/en
Publication of GB0501252D0 publication Critical patent/GB0501252D0/en
Publication of GB2422900A publication Critical patent/GB2422900A/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K31/00—Actuating devices; Operating means; Releasing devices
    • F16K31/001—Actuating devices; Operating means; Releasing devices actuated by volume variations caused by an element soluble in a fluid or swelling in contact with a fluid
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00—Investigating materials by mechanical methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment

Abstract

This invention relates to the actuation of switches and valves as a result of changes in the concentration of one liquid dispersed in another. The invention makes use of the well-documented propensity of certain cross-linked, branched or otherwise molecularly entangled polymers to swell, reversibly and without dissolution, in certain solvents. If the cross-linked polymer is exposed to a swelling solvent in combination with other solvents, which have reduced swelling properties with respect to the particular polymer, then the degree of swelling observed is markedly dependant on the concentration of the swelling solvent in the mixture. The swelling of the polymer is used to mechanically actuate switches or valves either directly or through the use of a multi-layer construct. The invention is particularly apposite to the control of methanol concentration in direct methanol fuel cell systems.

Description

Actuator Device This invention relates to a mechanical actuator which is
triggered by the measurement of concentration of one miscible liquid dispersed in another. The invention is particularly apposite to actuators which are triggered by a preset level of methanol concentration in water, but is equally applicable to other liquid mixtures.
The applications for concentration triggered actuators are many fold. Of particular relevance to this invention is the need for a low cost mechanism to control the concentration of a methanol solution in water. Such control is desirable in direct methanol fuel cell systems whereby the fuel cell must be supplied with methanol/water mixtures maintained at an optimal concentration. The operation of the fuel cell continually depletes the methanol concentration in the recirculated fuel and there is need for a simple mechanism to replenish methanol from a storage tank. The nature of the direct methanol fuel cell system means that the replenishment device should be simple, preferably require no electrical connection and be of low cost. Such demands, if met, would allow the control mechanism to be incorporated into a disposable fuel cartridge, greatly enhancing the utility of direct methanol fuel cell systems.
This patent seeks to address this problem through the use of a mechanical concentration sensor that is able to actuate a variety of switch or valve mechanisms.
There are two distinct classes of actuator, both of which can be produced with this invention. They are:- a) Actutors whereby the outcome of actuation is electrical switching b) Actuators whereby the outcome of actuation is mechanical operation of a component such as opening or closing a valve.
Conventional concentration dependent actuator systems rely on a sensor yielding an electronic output, which is in some way proportional to the solvent concentration. The sensor output is used by a process control system to electronically actuate valves etc., for the purpose of process control. Such control algorithms are expensive to implement and are unsuitable for systems constrained by cost or size limitations.
Page 1 ofX This invention utilises volumetric swelling of a cross-linked, branched or entangled polymer, in a compatible solvent species to effect mechanical actuation of a device or component. The invention eliminates the need for electronic process control, or indeed any electrical connection whatsoever, and therefore substantially reduces the cost and complexity of the control system.
The device utilises the well documented propensity of certain crosslinked, branched or otherwise molecularly entangled polymers, to swell in solvent media. The swelling phenomenon is the result of solvation of the polymer molecules, which are unable to dissolve due to the presence of a chemical or entanglement network structure. The degree of swelling is normally described using the Flory-Rhener equation, Eqn 1.
-[ln(I--v2)+v2 +Zv] 1/i(v2113-0 5v2) Eqn I Where n is the mean molecular weight between cross- linkages or entanglements in the polymer, V2 is the volume fraction of polymer in the swollen mass, V1 is the molar volume of the solvent, and x is the polymer-solvent interaction term.
The Flory Rhener equation is of low practical utility as it tends to offer predictive accuracy only when the polymer is loosely cross-linked and the solvent exhibits no site specific interactions with the polymer backbone. The important feature of the equation is the observation that the solvent term, XV22, is by far the largest parameter in most polymer swelling systems. This means that the interaction of the polymer with the solvent is key to determination of the degree of swelling.
When the solvent which interacts with the polymer is a binary mixture of two liquids, one of which is a good solvent for the polymer and one of which is a less effective solvent, the degree of swelling exhibited by the polymer is significantly dependent on the mixed solvent composition. This forms the theoretical basis for the actuator system in this disclosure. In simplest form, a polymer having a high degree of swelling in one component of a liquid mixture (A for example) is allowed to contact the mixture and exhibit swelling to a degree which is markedly dependent on the concentration of A. This swelling is used to operate a mechanical switch or actuator at a pre-determined concentration of A contained in the liquid mixture.
Page 2 of 8 In a more complex embodiment of this invention, a polymer, that exhibits significant swelling in one component of a liquid mixture, is constrained by an elastic material which is inert to all components in the mixture. On exposure to the liquid mixture, the swelling polymer will expand to a degree dependent on the concentration of the swelling component in the liquid mixture. Such swelling can be made to exhibit as bending or stretching of the non-swelling material, and this behaviour can be used as the trigger for a mechanical actuator. A good example would be the use of a laminate of a swelling and non-swelling polymer. This will operate in a similar fashion to a bimetallic strip used for temperature sensing. The bimetallic strip bends in response to increasing temperature due to the effect of differential expansion of the two components. In this invention, the strip is comprised of a solvent swelling and non- swelling material and exhibits bending in response to swelling solvent concentration.
There are a number of options for the implementations of this concept. A number of preferred embodiments will now be described by way of example of practical mechanism, by which the invention might find application as an actuator. The examples presented are in no way intended to describe all possible implementations of the invention but are merely demonstrative of the range of implementations. It is intended that the preferred embodiments should be indicative of application rather than in any way restrictive. The embodiments will be described by reference to the following diagrams Figure 1 A perspective view of a sensor strip element as produced Figure 2 A perspective view of a sensor strip element on exposure to the swelling solvent Figure 3 A perspective view of an electrical switch mechanism utilizing this invention Figure 4 A perspective view of an electrical switch mechanism utilizing this invention Figure 5 A perspective view of a normally open valve actuator based on this invention.
Figure 6 A perspective view of a normally open valve actuator based on this invention.
Page 3 of 8 Figure 7 A perspective view of a normally closed valve actuator based on this invention.
Figure 8 A perspective view of a normally closed valve actuator based on this invention.
Figure 9 A perspective view of a normally open valve actuator based on this invention.
Preferred Embodiment Example I A bi-polymer strip is produced from two polymer materials bonded together, Figure 1.
The strip is composed of a thin film, 1, of an elastic material that is resistant to swelling in any component of the liquid mixture. The inert strip is bonded to a film of a cross-linked, branched or entangled polymer, 3, that swells significantly in one component of the liquid mixture. The two strips are bonded together using a thin film of adhesive, 2, that is inert to the solvent mixture.
On exposure to the swelling agent, the swellable layer swells to a degree which is dependent upon the swelling agent solution composition. The lack of similar swelling in the inert layer results in progressive bending of the composite strut, with larger curvature resulting from a higher concentration of swelling agent. A representation of the strut after exposure to swelling agent solution is shown in figure 2. The curvature of the strut can be used to mechanically actuate a valve or micro-switch at a predetermined concentration. For efficacious operation, the strut should be manufactured to be a thin as is feasible, ideally less than 10mm and most ideally less than 1mm.
Preferred Embodiment Example 2 Figure 3 shows a strut as described in embodiment 1, used to actuate an electronic switch. The embodiment comprises a rigid strut, 8, holding electrical connections to a magnetically activated switch or relay, commonly described as a reed relay, 9.
Opposed to the rigid strut is a composite strut of the type described in embodiment 1, composed of an inert layer, 4, bonded via a solvent inert adhesive, 5, to a cross-linked, branched or molecularly entangled polymer material, 6. The polymer material, 6, is Page 4 of 8 selected such that it exhibits swelling in the solvent of interest, but is inert to other components in the mixture. Both the rigid strut (8) and the composite strut (4,5,6) are fixed at one end to a rigid block containing electrical connections. The free end of the composite strut bears a small magnet, 7, that is able to actuate the reed switch at close proximity. The arrangement is such, that when the unit is exposed to a low or zero concentration of the solvent of interest, the composite strut is straight and the magnet (7) is maintained at sufficient distance from the reed switch (9) for the latter to remain open. This is shown in perspective in Figure 3.
On exposure to a higher concentration of the solvent of interest, the composite strut bends due to swelling of the cross-linked, branched or molecularly entangled polymer (6). This action brings the magnet into closer proximity to the reed switch, until, at some pre-determined concentration of the solvent of interest, the reed switch is activated. This condition is shown in perspective view in Figure 4.
The output from the reed switch is a simple on/off electrical connection and can be used via a suitable power relay to switch valves, pumps or other appliances, based on the liquid concentration.
Preferred Embodiment Example 3 Figure 5 shows a device constructed from the strip described in preferred embodiment I, to allow the bending of the strip to mechanically actuate a valve. The device comprises a rigid strut, 14, carrying a pipe, 20 through which a liquid is delivered. Opposed to the rigid strut, is a composite strut of the type described in preferred embodiment example 1. The strut is composed of an inert layer of elastic material, 16, to which a thin film of a cross-linked, branched or molecularly entangled polymer, 18, is attached via an inert adhesive, 17. The cross-linked, branched or entangled polymer is selected such that the material exhibits swelling in one of the components that make up the liquid within which the device is immersed.
One end of both the rigid strut (14) and the composite strut (16, 17, 18) are held in a block, 21. The other end of the composite strut bears a plug suitable to effect closure of the open end of the pipe,19.
The pipe 20 delivers the agent that is responsible for the swelling of the cross-linked, branched or entangled polymer making up layer 18 in the composite strut. The pressure within the pipe is such that, whilst the end of the pipe (19) is open, the Page 5 of 8 swelling agent flows through the pipe and mixes with the liquids within which the device is immersed. As the concentration of the swelling agent (within the bulk of the liquid within which the device is immersed) increases, the composite strut exhibits increasing curvature due to the progressive swelling of layer 18. At some point the plug (15) is brought into contact with the open pipe (19) and the flow within the pipe is stopped, Figure 6. The device has effectively allowed the concentration of the swelling agent from pipe 20 to increase to a pre-set level and has then constricted the flow.
If some external process causes the concentration of the swelling agent to decline, the swelling of layer 18 will also be reduced and the valve will gradually open. In this way the valve represents a purely mechanical mechanism for controlling the concentration of one liquid dispersed in another.
The action of the valve can be reversed such that the valve is open when the swelling agent concentration is high and closed when it is low, by the simple expedient of inverting the composite strut. In this way the valve should be closed when the composite strut is straight and opens as the swelling agent causes the composite strut to bend away from the rigid strut. This mode of operation is shown in Figures 7 and 8.
The device can be conveniently constructed with a reversible composite strut to allow either mode of operation.
Preferred Embodiment Example 4 Figure 9 shows an embodiment of this invention suitable for attachment to a feed pipe that is freely suspended in a liquid mixture. The device is intended to control the delivery of a fluid from the pipe, 27, into a bulk liquid container or tank. The device comprises a stiff box frame, 22, containing a helical spring, 23, that is restrained by a filament of a cross-linked, branched or molecularly entangled polymer. One end of the spring is restrained by the box frame (22) whilst the other bears a ball bearing, 25, that is maintained fractionally short of seating against a seal face, 26, on the outfall from the pipe, 27, by the polymeric filament, 24.
On exposure to a liquid containing a concentration of a swelling agent for the polymeric filament (24), the filament is able to swell and lengthen, allowing the ball to seal the out flow from the pipe (27) by the action of the spring (23). As the concentration of swelling agent in the liquid is reduced by some external mechanism, Page 6 of 8 the contraction of the filament (24) will again allow the pipe outfall seal (26) to open and liquid from the pipe (27) to flow.
If the pipe (27) delivers the swelling agent into a second liquid, which is not a swelling agent for the polymeric filament, the device will act to control the concentration of swelling agent within a tank or bulk liquid container.
Page 7 of 8

Claims (5)

  1. Claims I claim 1. A mechanical actuator triggered by the concentration of
    one component within a liquid mixture, whereby actuation is the result of the solvent swelling phenomenon observed in certain cross-linked, branched or entangled polymers when exposed to certain liquids.
  2. 2. An electrical actuator triggered by the concentration of one component within a liquid mixture, whereby actuation is the result of the solvent swelling phenomenon observed in certain cross-linked, branched or entangled polymers when exposed to certain liquids.
  3. 3. The use of a construct having at least two layers, one of which is a cross- linked, branched or entangled polymer and one of which is inert to solvents, such that the swelling of the cross-linked, branched or entangled polymer, is converted to force or motion by the restraint of the inert layer and thereby causes actuation of a mechanical switch or valve.
  4. 4. The use of a construct having at least two layers, one of which is a cross- linked, branched or entangled polymer and one of which is inert to solvents, such that the swelling of the cross-linked, branched or entangled polymer, is converted to force or motion by the restraint of the inert layer and thereby causes actuation of an electrical switch.
  5. 5. A device according to claims 3 and 4, whereby the construct is a duplex layer structure of a cross-linked, branched or entangled polymer bonded or otherwise affixed to a substrate which is inert to solvents, and which actuates a mechanical or electrical switch or valve by bending when exposed to a sufficient concentration of certain liquids that cause the cross-linked, branched or molecularly entangled polymer to swell.
    Page 8 of 8
GB0501252A 2005-01-21 2005-01-21 Actuator device Withdrawn GB2422900A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0501252A GB2422900A (en) 2005-01-21 2005-01-21 Actuator device

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Application Number Priority Date Filing Date Title
GB0501252A GB2422900A (en) 2005-01-21 2005-01-21 Actuator device

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GB2422900A true GB2422900A (en) 2006-08-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105782459A (en) * 2014-12-19 2016-07-20 昆达电脑科技(昆山)有限公司 Valve realizing automatic opening and closing based on humidity

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0365011A2 (en) * 1988-10-21 1990-04-25 Canon Kabushiki Kaisha A polymer gel manufacturing method, a polymer gel and an actuator employing the same
US5250167A (en) * 1992-06-22 1993-10-05 The United States Of America As Represented By The United States Department Of Energy Electrically controlled polymeric gel actuators
JPH05340786A (en) * 1992-06-11 1993-12-21 Fuji Electric Co Ltd Liquid level detecting switch
JPH0714480A (en) * 1993-04-30 1995-01-17 Kurabe Ind Co Ltd Moisture detecting switch
US6475750B1 (en) * 1999-05-11 2002-11-05 M-Biotech, Inc. Glucose biosensor
DE10157317A1 (en) * 2001-11-23 2003-06-05 Gesim Ges Fuer Silizium Mikros A base element used for a microfluid processor in cell biology, comprises an actuator based on a swellable polymer network having volume phase transition behavior and an interface arranged close to the actuator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0365011A2 (en) * 1988-10-21 1990-04-25 Canon Kabushiki Kaisha A polymer gel manufacturing method, a polymer gel and an actuator employing the same
JPH05340786A (en) * 1992-06-11 1993-12-21 Fuji Electric Co Ltd Liquid level detecting switch
US5250167A (en) * 1992-06-22 1993-10-05 The United States Of America As Represented By The United States Department Of Energy Electrically controlled polymeric gel actuators
JPH0714480A (en) * 1993-04-30 1995-01-17 Kurabe Ind Co Ltd Moisture detecting switch
US6475750B1 (en) * 1999-05-11 2002-11-05 M-Biotech, Inc. Glucose biosensor
DE10157317A1 (en) * 2001-11-23 2003-06-05 Gesim Ges Fuer Silizium Mikros A base element used for a microfluid processor in cell biology, comprises an actuator based on a swellable polymer network having volume phase transition behavior and an interface arranged close to the actuator

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BASHIR et al; micromechanical cantilever as an ultrasensitive pH microsensor, Applied Physics Letters, 81, 2002, 3091-3093 *
Rock et al; A dynamic model of liner actuator based on polymer hydrogel *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105782459A (en) * 2014-12-19 2016-07-20 昆达电脑科技(昆山)有限公司 Valve realizing automatic opening and closing based on humidity

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Publication number Publication date
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