Patent Description:
Binary actuator valves suitable for use in fluid control systems are known. A good example of a significant development can be found in <CIT>. <FIG> of this document is replicated in the present application as <FIG> for ease of reference.

With reference, therefore, to <FIG> of the present <CIT> teaches an electromagnetic valve comprising a yoke <NUM>. A magnet 30a, 30b is provided having pole pieces 50a, 50b defining a gap <NUM>. A flexure assembly <NUM> has one end attached to the yoke <NUM>, such that part of the flexure assembly extends into the gap. The flexure assembly <NUM> has at least one resilient portion formed of a resilient material and at least one magnetisable portion, wherein the part of the flexure assembly <NUM> that extends into the gap is movable between the pole pieces through an intermediate position towards which it is resiliently biased such that a resilient mechanical force is generated by deflecting the resilient portion from an undeflected position. A means <NUM> is provided for polarising the magnetisable portion of the flexure assembly <NUM> so that the part of the flexure assembly <NUM> that is movable between the pole pieces is attracted towards a pole piece by a magnetic force, thereby defining a valve state. The magnetisable portion and the resilient portion of the flexure assembly are configured such that the magnetic force defining the valve state is greater than the resilient mechanical force.

<CIT> teaches several different forms of flexure assembly.

<CIT> also specifically teaches that such valves can be used in vehicle braking systems - in which fast switching times are required with large pressure differentials across the valve.

If there is no electrical power provided to the coil of the valve of <CIT>, then the state of the valve can be unpredictable or, at least, dependent on the state of the valve immediately prior to termination of the supply of electrical power. In particular, the flexure assembly <NUM> may be retained in a position such that it abuts a particular pole piece 50a,50b (e.g. if the flexure assembly <NUM> was abutting that pole piece 50a,50b when electrical power was lost) or may return to the intermediate position (e.g. if the flexure assembly <NUM> had not reached a position close enough to a pole piece 50a,50b to ensure that the elastic flexure force of the flexure assembly <NUM> could be overcome by the magnetic force and air pressure force) - see figures 2A-2D of <CIT>, for example).

Therefore, the valve of <CIT> has no failsafe state. This can pose problems when used in brake systems in which safe operation of valves often dictates that there is a failsafe state. As a result, the valve of <CIT> may not be suitable for certain applications and/or may require additional components to be provided in the braking system in order to provide a failsafe operation for a part of the brake system including the valve.

<CIT> discloses a valve having a sealed seat and a magnetisable closure body provided in a cylindrical base body. The measurements of the closure body are greater than that of an axial discharge opening of the seat. A coil produces magnetic field in the base body, where the field acts on the closure body. An interior of the base body includes elastic attachment elements, where the closure body is fastened and movably mounted at the attachment elements. The attachment elements pass from a mechanical stable form into another mechanical stable form by preset force effect.

There is a need, therefore, alleviate one or more problems associated with the prior art.

Document <CIT> discloses an electromagnetic flexure valve according to the preamble of claim <NUM>.

Accordingly, an aspect provides an electromagnetic flexure valve including: a first pole piece and a second pole piece; a flexure assembly a portion of which is configured for movement between a first state adjacent the first pole piece and a second state adjacent the second pole piece; a coil configured to receive electrical power from a power supply and to actuate the flexure assembly between the first and second states; and a biasing configuration, including an electromagnet and second magnet, configured to bias the flexure assembly into the first or the second state when the coil is not powered and irrespective of the current state of the flexure assembly such that a failsafe mode is provided wherein the biasing configuration is configured such that the electromagnet and second magnet apply a substantially balanced magnetic force on the flexure assembly when electrical power is provided to the electromagnet and when electrical power ceases to be provided to the electromagnet the magnetic force of the second magnet moves the flexure assembly towards the second magnet or retains the flexure assembly in a position biased towards the second magnet.

The biasing configuration may include a predetermined bend or curve along a length of the flexure assembly.

The predetermined bend or curve along a length of the flexure assembly may be towards a proximal end of the flexure assembly relative to the first and second pole pieces.

The predetermined bend or curve along a length of the flexure assembly may be adjacent the first and second pole pieces.

The flexure assembly may include a plurality of layers.

The at least one layer of the plurality of layers may be a pre-stressed layer.

Embodiments of the invention are described, by way of example only, with reference to the accompanying drawings, in which:.

Embodiments may include a valve <NUM> - see <FIG>, <FIG>, and <FIG>. The valve <NUM> is an electromagnetic flexure valve <NUM>. The valve <NUM> includes a flexure assembly <NUM> may be held within a yoke <NUM> at a proximal end <NUM> of the flexure assembly <NUM>. The proximal end <NUM> of the flexure assembly <NUM> may be secured a main portion of the yoke <NUM>, from which two adjacent arm portions may extend. A distal end <NUM> of the flexure assembly <NUM> may extend to be located between the two adjacent arm portions of the yoke <NUM>.

A first of the two adjacent arm portions of the yoke <NUM> may carry a first tubular member <NUM> (which may be formed of a non-magnetic material). An end of the first tubular member <NUM> may be located in the region of the distal end <NUM> of the flexure assembly <NUM>. The first of the two adjacent arm portions of the yoke <NUM> may further carry a first pole piece 50a which may be formed from bright mild steel, for example. The first pole piece 50a may include a portion which is located between the end of the first tubular member <NUM> and the distal end <NUM> of the flexure assembly <NUM>. The first pole piece 50a may define an aperture therethrough which leads to a passage defined by the first tubular member <NUM>.

The first pole piece 50a may include a seal member <NUM> (such as a rubber O-ring) adjacent the aperture and around the aperture, at a face of the first pole piece 50a closest to the flexure assembly <NUM>.

The first of the two adjacent arm portions of the yoke <NUM> may carry a first magnet 30a (which may be a permanent magnet) which may be a strong magnet such as a Neodymium-iron-boron (NdFeB) magnet. The first magnet 30a may be located adjacent the first pole piece 50a and may be located between the first pole piece 50a and the first of the two adjacent arm portions of the yoke <NUM>.

In some embodiments, the first of the two adjacent arm portions of the yoke <NUM> includes a first packer <NUM>. The first packer <NUM> may be located between, for example, the first magnet 30a and the first of the two adjacent arm portions of the yoke <NUM>. A first surface of the first packer <NUM> may correspond with an adjacent surface of the first magnet 30a and a second surface (opposing the first surface across a depth of the first packer <NUM>) may correspond to a curved surface of the first of the two adjacent arm portions of the yoke <NUM>. The first packer <NUM> may, therefore, allow an angle between a longitudinal axis of the first tubular member <NUM> and the first of the two adjacent arm portions of the yoke <NUM> to be adjusted (e.g. to ensure a good seal between the flexure assembly <NUM> and the first pole piece 50a in use).

The first pole piece 50a, first magnet 30a, and first packer <NUM> (if provided) may be generally annular in form such that they may fit around a portion of a length of the first tubular member <NUM>.

The arrangement may be replicated for the second of the two adjacent arm portions of the yoke <NUM>, with the same (but opposing) arrangement of a second pole piece 50b (which may include a seal <NUM>), a second tubular member <NUM>, a second magnet 30b, and a second packer <NUM>. The description in relation to the elements carried by the first of the two adjacent arm portions of the yoke <NUM> should, therefore, be considered as equally applicable to the second of the two adjacent arm portions of the yoke <NUM>.

In some embodiments, the proximal end <NUM> of the flexure assembly <NUM> is clamped by the yoke <NUM> and may be clamped between the first and second arm portions thereof, with the distal end <NUM> extending therefrom in a cantilevered manner.

The yoke <NUM> may be further configured to house a coil <NUM> between the first and second adjacent arm portions of the yoke <NUM> towards the proximal end <NUM> of the flexure assembly <NUM> (relative to the position of the first and second pole pieces 50a,50b along the flexure assembly <NUM>). The coil <NUM> may extend around the flexure assembly <NUM>.

The flexure assembly <NUM> could take any of the general forms disclosed in <CIT>, for example. Indeed, the valve <NUM> could be a valve <NUM> generally in accordance with the teachings of <CIT>.

The operation of the valve will be understood from the teachings of <CIT>, for example. In particular, the flexure assembly <NUM> may be actuated by passing electric power (i.e. a current) through the coil <NUM> to attract the flexure assembly <NUM> to a particular one of the pole pieces 50a,50b. Abutment of the flexure assembly <NUM> with the first pole piece 50a may be considered to be (a first flexure assembly state and) a first valve state and abutment of the flexure assembly <NUM> with the second pole piece 50b may be considered to be (a second flexure assembly state and) a second valve state.

In accordance with embodiments, however, unlike the valves of <CIT>, a failsafe mode may be provided. In accordance with this failsafe mode, the flexure assembly <NUM> - even in the absence of electric power provided to the coil <NUM> may be configured to adopt a predetermined state (i.e. a single one of the first and second states). Therefore, in some embodiments, the valve <NUM> may be a monostable valve <NUM> (the valve of <CIT> may be viewed as a bistable valve, for example).

Accordingly, in the failsafe mode, the predetermined state may be the first or the second valve state (as described above) depending on the desired operation (and so design) of the valve <NUM>.

The failsafe mode may be achieved in a number of different manners (e.g. using a biasing configuration).

In some embodiments (such as that depicted in <FIG>) one of the first and the second magnets 30a,30b is not a permanent magnet as described above but is an electromagnet. In such embodiments, the other of the first and second magnets 30a,30b would remain a permanent magnet. Whilst the electromagnet could be the first or the second magnet 30a,30b, these embodiments will be described with the first magnet 30a being the electromagnet 30a' (again, see <FIG>, for example) for the sake of simplicity and it will be appreciated that this description will apply equally if the second magnet 30b were the electromagnet.

In some such embodiments, therefore, the first magnet 30a is an electromagnet (so herein the first electromagnet 30a'). The first electromagnet 30a' may be configured to receive electrical power from a power supply <NUM> - see <FIG>, for example. The power supply <NUM> may include a power controller <NUM> which is configured to regulate the electrical power provided to the first electromagnet 30a'.

The power controller <NUM> may control the electrical power supplied to the first electromagnet 30a' such that the magnetic flux of the first electromagnet is substantially equal in magnitude (but opposite in direction) to the magnetic flux of the second magnet 30b. In other words, the control may be such that a magnetic force applied to the flexure assembly <NUM> is substantially balanced (i.e. equal and opposite from the second magnet 30b and the first electromagnet 30a'). The power controller <NUM> may be configured to, for example, provide pulse width modulated electric current to the first electromagnet 30a' (or some other pulsed current arrangement).

The power controller <NUM> may be communicatively coupled to one or more sensors <NUM> (such as Hall Effect sensors) to in order to control the electrical power delivered to the first electromagnet 30a' to seek to match the magnitude of the flux of the first electromagnet 30a' and the second magnet 30b. The one or more sensors <NUM> may be provided as part of the power supply <NUM> or as part of the valve <NUM>.

The power supply <NUM> may include one or more batteries <NUM> and/or one or more electrical generators <NUM> (e.g. an alternator) which may form part of a vehicle and/or vehicle trailer. The vehicle may be a vehicle with one or more ground engaging wheels for example (such as a truck). The power controller <NUM> may be configured to control (e.g. regulate) the electrical power provided by the one or more batteries <NUM> and/or electrical generators <NUM> in order to provide the required electrical power to the first electromagnet 30a'. The power supply <NUM> may also provide (through another controller) electrical power to the coil <NUM> which actuates the valve <NUM> between the first and second states - as such the coil <NUM> may be connected in electrical communication with the one or more batteries <NUM> and/or the one or more electrical generators <NUM>.

During normal operation of the valve <NUM>, therefore, the first electromagnet 30a' may be powered by the power supply <NUM>. The valve <NUM> can then operate in the manner generally described in <CIT>.

If electrical power to the first electromagnet 30a' is lost (i.e. not provided), then the magnetic attractive force on the flexure assembly <NUM> in the direction of the second pole piece 50b will be higher than that in the direction of the first pole piece 50a. Therefore, the first flexure assembly <NUM> will move towards or be retained in the second state. The second state is, therefore, in this configuration the failsafe mode. The opposite failsafe mode (i.e. the first state) could be achieved in the same manner but with the second magnet 30b as the electromagnet (and so being a second electromagnet 30b' - see <FIG>, for example).

In some such embodiments, the electromagnet 30a',30b' may be provided as a coil through which the power supply <NUM> is configured to provide electrical cu rrent.

In some embodiments, the electromagnet 30a',30b' may be integrally formed with the first or second packer <NUM>,<NUM> as the case may be.

In some examples, which are not part of the present invention, both first and second magnets 30a,30b are provided as permanent magnets but one is weaker (i.e. provides less magnetic flux) than the other. The weaker of the first and second magnets 30a,30b may be supplemented by an electromagnet (which might, therefore, be referred to as a first or second supplemental electromagnet, as the case may be) - to balance, during normal operation, the magnetic forces on the flexure assembly <NUM> when in the intermediate state (i.e. between the first and second states and without activation of the coil <NUM>).

In some embodiments, the electromagnet may be provided as part of the first or second pole piece 50a,50b.

In some embodiments, the electromagnet may be provided in series with the first or second adjacent arm portions of the yoke <NUM> (and could form part of the yoke <NUM>, for example).

In some examples, which are not part of the present invention, the electromagnet may not be provided; however, the magnets 30a,30b may be mismatched such that one of the first and second magnets 30a,30b imparts a stronger magnetic attractive force on the flexure assembly <NUM> than the other when in the intermediate state (i.e. between the first and second states and without activation of the coil <NUM>). This imbalance means that the flexure assembly <NUM> is biased towards either the first or the second pole piece 50a,50b (i.e. the pole piece 50a,50b associated with the one of the first and second magnets 30a,30b which imparts the stronger magnetic attractive force on the flexure assembly <NUM> than the other. During normal use, this imbalance may be counterbalanced by the provision of an electrical biasing current through the coil <NUM> such that the imbalance is effectively reduced or substantially eliminated. In such embodiments, an electrical switching current may be added to the electrical biasing current to achieve switching of the valve <NUM> between the first and second states as described herein elsewhere. To achieve this, the valve <NUM> may include an electrical biasing circuit <NUM> - see <FIG>.

Accordingly, the flexure assembly <NUM> is biased into a failsafe mode by the use of the electromagnet or coil <NUM> such that there is an imbalance in the magnetic forces applied to the flexure assembly <NUM> in favour of the failsafe mode if electrical power to the electromagnet is discontinued (even if there is no electrical power provided to the coil <NUM>) or if there is no electrical power provided to the coil <NUM> (and there is no electromagnet).

In some embodiments, the flexure assembly <NUM> may be mechanically formed to favour the failsafe mode (which, again, could be the first or the second state).

This may be achieved by the provision of a predetermined bend or curve <NUM> to a part of the flexure assembly <NUM> - see <FIG>. The predetermined bend may be configured to cause the distal end <NUM> of the flexure assembly <NUM> to favour the failsafe mode. In some embodiments, the predetermined bend or curve <NUM> is located towards the proximal end <NUM> (relative to the location of the first and second pole pieces 50a,50b). In some embodiments, the predetermined bend or curve <NUM> is located away from portions of the flexure assembly <NUM> which are configured to contact the pole pieces 50a,50b to form a seal therewith (e.g. with the seal members <NUM>) - to reduce the impact of the predetermined bend or curve <NUM> on the seal with the pole pieces 50a,50b.

In some embodiments, the predetermined bend or curve <NUM> may include a curve <NUM> (see <FIG>, for example) along a length of the flexure assembly <NUM> which is configured to contact the pole pieces 50a,50b to provide the seals therewith. In some such embodiments, however, the first and second pole pieces 50a,50b may be correspondingly shaped and/or a deformable seal <NUM> may be provided which is configured to conform to the curve <NUM>. In some embodiments, this may mean that the first and second pole piece 50a,50b are each configured to contact a respective one of a convex or a concave flexure assembly <NUM>. In some embodiments, the predetermined curve of the flexure assembly <NUM> between the pole pieces 50a,50b may change as the flexure assembly <NUM> moves between the first and second states - e.g. with the surface thereof adjacent the first pole piece 50a changing from a convex towards a concave surface (or vice versa) as the flexure assembly <NUM> moves towards the second pole piece 50b.

The flexure assembly <NUM> could include a laminated section in which multiple layers <NUM>,<NUM> of material are provided to form the flexure assembly <NUM> - see <FIG> as an example. Such arrangements may be generally in the form of the "fingers" of <CIT>, for example. In some embodiments, the layers <NUM>,<NUM> of material may be secured to each other at discrete positions along their length or substantially continuously along their length. The layers <NUM>,<NUM> of material may have different properties so as to provide a bias of the flexure assembly <NUM> towards the first or second state. In some embodiments, one of the layers <NUM>,<NUM> is stressed when secured to another of the layers <NUM>,<NUM> so as to provide the predetermined bend in the flexure assembly <NUM> or otherwise provide the bias towards the first or second positions. This may generally be referred to, for example, as a pre-stressed layer <NUM>,<NUM>.

In some embodiments, the failsafe mode of operation may be achieved through electrical control of the operation of the coil <NUM>. In such embodiments, the valve <NUM> may have magnets 30a,30b which are balanced.

However, the coil <NUM> may be coupled in electrical communication with a failsafe circuit <NUM>. The failsafe circuit <NUM> may include a power detection circuit <NUM> which is configured to detect a loss of the electrical power supply (e.g. from the power supply <NUM> which may power the coil <NUM> in normal operation). The failsafe circuit <NUM> may further include a power storage system <NUM> which is configured to provide electrical power to the coil <NUM>. The power storage system <NUM> may be substantially independent of the power supply <NUM> such that a loss of power from the power supply <NUM> does not result in loss of electrical power from the power storage system <NUM> other than by discharge to the coil <NUM> - as described below.

The power detection circuit <NUM> may be further configured, on detection of a loss of electrical power, to trigger the discharge of the power storage system <NUM> to the coil <NUM>. This discharge may cause, for example, the flexure assembly <NUM> to be moved to, or retained in, a one of the first and second states (as required), in generally the same manner as the coil <NUM> is used to switch the state of the flexure assembly <NUM> during normal operation. In other words, the discharge through the coil <NUM> may provide a magnetic flux which forces the flexure assembly <NUM> to adopt one of the first and second states (predetermined by direction of discharge through the coil <NUM>).

The power storage system <NUM> may be a temporary power storage system <NUM> which is configured to charge using electrical power from, for example, the power supply <NUM>. This charging may be substantially continuous. The power storage system <NUM> could, therefore, include a battery and/or a capacitor, for example. The power storage system <NUM> may be configured such that the discharge of electrical power to the coil <NUM> is sufficient, when triggered, to switch the flexure assembly <NUM> from the first to the second state (or vice versa). A switch device <NUM> (of the failsafe circuit <NUM>) may be provided in electrical communication between the power storage system <NUM> and the coil <NUM>, the switch device <NUM> may be configured to control the electrical communication between the power storage system <NUM> and the coil <NUM>, and so may be communicatively couple to the power detection circuit <NUM> (which is configured to cause actuation of the switch device <NUM>). The switch device <NUM> may be configured, on actuation, to provide electrical power to the coil <NUM> in a series of pulses, for example (such as in a pulse width modulated manner).

In some embodiments, all of the components of the failsafe circuit <NUM> may be configured to be powered by the power storage system <NUM> of the failsafe circuit <NUM> if the supply of electrical power from the power supply <NUM> ceases. In embodiments all of the components of the failsafe circuit <NUM> are configured to be powered by the power storage system <NUM> of the failsafe circuit <NUM>, sufficiently to achieve the failsafe mode (i.e. in a worst case scenario to switch state of the flexure assembly <NUM> if it is not already in the failsafe mode), if the supply of electrical power from the power supply <NUM> ceases. Accordingly, the failsafe circuit <NUM> may provide an electrical failsafe operation for the valve <NUM>. The failsafe circuit <NUM> may form part of the valve <NUM>.

As will be appreciated, therefore, in some embodiments, the flexure assembly <NUM> is biased towards a failsafe mode. This enables some embodiments to be more readily used in certain safety critical valves <NUM> of, for example, a vehicle brake system, than some previous valves. In addition, the failsafe mode of operation being integral to the operation of the valve <NUM> may enable one or more other components to be omitted from a brake system - components which might otherwise provide a failsafe mode, for example.

Whatever mechanism is provided in accordance with embodiments to achieve the biasing of the flexure assembly <NUM>, that mechanism is a biasing configuration. The biasing configuration including an electromagnet may, therefore, also include a predetermined bend in the flexure assembly <NUM> and/or the provision of a failsafe circuit <NUM>. appreciated that multiple such biasing configurations may be provided (e.g. to provide backup failsafe configurations should one fail).

Claim 1:
An electromagnetic flexure valve (<NUM>) including:
a first pole piece (50a) and a second pole piece (50b);
a flexure assembly (<NUM>) a portion of which is configured for movement between a first state adjacent the first pole piece (50a) and a second state adjacent the second pole piece (50b);
a coil (<NUM>) configured to receive electrical power from a power supply (<NUM>) and to actuate the flexure assembly (<NUM>) between the first and second states; and
characterised by a biasing configuration, including an electromagnet (30a') and second magnet (30b), configured to bias the flexure assembly (<NUM>) into the first or the second state when the coil (<NUM>) is not powered by the power supply (<NUM>) and irrespective of the current state of the flexure assembly (<NUM>) such that a failsafe mode is provided wherein the biasing configuration is configured such that the electromagnet (30a') and second magnet (30b) apply a substantially balanced magnetic force on the flexure assembly (<NUM>) when electrical power is provided to the electromagnet (30a') and when electrical power ceases to be provided to the electromagnet (30a') the magnetic force of the second magnet (30b) moves the flexure assembly (<NUM>) towards the second magnet (30b) or retains the flexure assembly (<NUM>) in a position biased towards the second magnet (30b).