GB2603541A - A pyrotechnic electrical interrupter - Google Patents

Abstract

An electrical interrupter 100 comprises a movable conductor 106 arranged between a first conductor 102 with a first contact 102a and a second conductor 104 with a second contact 104a. The movable conductor comprises a rim (108, figure 3) having third and fourth contacts (108a,b) which respectively engage the first and second contacts, a body portion (110), an inner surface 112 which defines the volume of the movable conductor, and an outer surface 114. The inner surface of the body portion partially defines a first cavity (124, figure 1B) and the outer surface of the body partially defines a second cavity (126). When ignited, a pyrotechnic charge 116 releases gas into the first cavity to displace the movable conductor and open the conduction path. The movable conductor may be hemispherical, or dome shaped. The third and fourth contacts may be arranged on the inner surface of the rim and may be press fit onto the first and second contacts. The volume of the first cavity may be less than that of the second cavity. The second cavity may comprise recesses (128, figure 6B) formed in the housing 118, the recesses being aligned with the first and second conductors and act as channels for the gases to flow through and stretch an electrical arc.

Description

A Pyrotechnic Electrical Interrupter

Field

This relates to opening, or interrupting, a current conduction path. In particular, this relates to an electrical intermpter including a pyrotechnic actuator arranged to open a current conduction path, and a method for operating such a device.

Background

Current conduction paths can be opened by breaking a continuous conductor which defines the current conduction path. One approach is to use an electrical interrupter comprising an actuator, in some examples a pyrotechnic based actuator, to break the continuous conductor.

It is desirable to provide an improved apparatus for opening a current conduction path, is particularly in high current applications (which typically employ large conductors that require a large amount of force to break them). Such an improved apparatus is desirable for applications which require reliable and rapid opening of a current conduction path, for example batteries in electric vehicles or electrical overload mechanisms for industrial processes requiring high current ratings.

Summary

In a first aspect, a device is provided as defined in the appended independent apparatus claim, with optional features defined in the dependent claims appended thereto. In a second aspect, a method of operating the device of the first aspect is provided as defined in the appended independent method claim.

Described herein is an electrical interrupter, comprising three conducting components: a first conductor comprising a first contact portion; a second conductor comprising a second contact portion; and a moveable conductor arranged between the first and second conductors to define a current conduction path through (or along) the current conducting components. The first and second conductors are here provided as fixed conductors. The moveable conductor' has an inner surface defining a volume of the moveable conductor and an outer surface. The moveable conductor comprises: a rim portion, the rim portion having a third contact portion and a fourth contact portion, wherein the third contact portion is configured to be in electrical contact with the first contact portion and the fourth contact portion is configured to be in electrical contact with the second contact portion; and a body portion, the inner surface of the body portion at least in part defining a first cavity and the outer surface of the body portion partially defining a second cavity. The electrical interrupter further comprises a pyrotechnic charge arranged, upon ignition, to release gas into the first cavity to displace the moveable conductor into, or in a direction towards, the second cavity and thereby to open the current conduction path.

Optionally, the first and second contact portions are arranged in direct electrical and physical contact with the third and fourth contact portions. Optionally, the third and fourth contact portions are retained in physical contact with the first and second contact portions by interference fit or press fit (i.e. retained by frictional forces arising from pressure between the respective contacting surfaces of the conducting components). In other words, the moveable conductor is retained between the first and the second conductors by a press or interference fit interface between the first and third contact portions, and between the second and fourth contact portions. Alternatively', the third and fourth contact portions are not in direct physical contact with the first and second contact portions, but the moveable conductor may instead be retained with solder or with electrically conductive adhesive.

Previous pyrotechnic charge/actuator based devices have relied on a linear arrangement to break a single, or continuous, conductor. For example, a linear displacement of an actuated piston would cut the conductor into two segments under a wedge type action to interrupt the current. This arrangement may be suitable for some low current applications. However, for higher current applications, the conductor to be broken is typically thicker or wider, and therefore high forces. can be required in order to break the conductor.

By exerting pressure directly on the moveable conductor in order to displace it, the pyrotechnic charge can directly act to open the current conduction path, without the need for an intermediary or secondary component, such as a piston. A simpler, cheaper, device may therefore be provided, which operates by direct action of gas pressure. By inserting and retaining the moveable conductor between the first and second conductors with a temporary joint or join, such as a press fit, sufficient electrical contact can be maintained to provide a current conduction path through the device in general use. .At the same time, relatively quick and easy opening of the current conduction path may be achieved once the pyrotechnic charge is actuated or ignited without requiring large forces to be applied (since the temporary press fit join may be broken or overcome with less force than is required to physically break a continuous conductor). Smaller actuators or charges may therefore be used, facilitating the provision of smaller and cheaper devices.

Optionally, the third and fourth contact portions are arranged on the inner surface of the rim portion of the moveable conductor, and the first and second conductors are shaped such that the first and second contact portions correspond to the inner surface of the rim portion. For example, the shapes of the first and second contact portions correspond to the shape of the inner surface of the rim portion at the third and fourth contact portions, such that the respective contact portions can be arranged in physical contact with one another. By using conductors with corresponding shapes or geometries, a good electrical and physical contact may be achieved.

is In some examples, the conductors are mating components or have mating geometries at the respective contact portions, which can facilitate a press or interference fit to retain the moveable conductor between the first and second conductors. The first and second conductors can be thicker than the moveable conductor, so washing the moveable conductor around the outside of the first and second conductors (such that the first and second conductors contact the inner surface of the moveable conductor) may reduce the risk of deforming the moveable conductor during assembly (as compared to arrangements in which the first and second conductors contact the outer surface of the movable conductor, for example). The press or interference fit interface can be designed to have an electrical resistance at the contact point which is at or below a predetermined value, which value can be dependent on the current and voltage requirements of the device. Moreover, by arranging the first and second conductors against the inner surface of the moveable conductor, the radial expansion of the moveable conductor may rapidly separate it from the first and second conductors, allowing for quick and reliable opening of the current conduction path.

In some examples, the inner surface of the moveable conductor is at least partially carved. The moveable conductor maybe any suitable shape, with regular or irregular curvature. For example, the moveable conductor could be a cylinder, or have a semicircular cross section. Optionally, the body portion of the moveable conductor is substantially hemispherical (i.e. half a sphere, or otherwise shaped like a dome). The inner and/or the outer surfaces of the body portion can be (substantially) -4 -hemispherical. With a hemispherical inner cavity, there can be a uniform pressure distribution on the inner surface of the moveable conductor from the pyrotechnically generated gas released by ignition of the charge, with no singularities or discontinuities. Use of hemispherical inner surface can therefore reduce the risk of fracture of the moveable conductor during operation (fractures concentrate at areas of high stress), but any other geometry of body portion maybe used.

In some examples, the rim portion oftne moveable conductor is cylindrical. This shape can facilitate good, uniform, contact with the contact portions of the first and second conductors. This shape can also make the first and second conductors easier to manufacture than if the rim portion was irregularly curved, for example. The rim portion is configured to be substantially continuous with the body portion; optionally, the outer surface is continuous at the meeting or join of the rim portion and the body portion. In some examples, the moveable conductor is formed as an integral is component. In other examples. the rim and body portions may be separate components joined by any suitable means, which arrangement may simplify manufacture of the moveable conductor.

Optionally, a volume of the first cavity is less than a volume of the second cavity, optionally wherein the volume of the second cavity is equal to or more than X times the volume of the first cavity, where X can any suitable number or value greater than 1. Optionally X is equal to 3. By configuring the cavities such that there is a volume ratio between the first and second cavities, a corresponding pressure ratio is provided, reducing the pressure exerted by the gas from the (pyrotechnic) charge on the walls of the housing in the second cavity. A thinner housing may therefore be provided, which can facilitate provision of a smaller, cheaper, device.

In sonic examples, an optional locking mechanism is provided, which is configured to retain the moveable conductor between the first and second conductors. The locking 30 mechanism can minimise or prevent rotation and/or translation of the moveable conductor, depending on its configuration. The locking mechanism can thus help to prevent accidental displacement of the conductor as a result of one or more physical orations or shocks experienced by the device. The device may therefore be operated or actuated only by ignition of the pyrotechnic charge, for example in response to an ignition signal. A more robust device may therefore be provided, which can be deployed in adverse operational environments. -5 -

Optionally, the locking mechanism comprises at least one protrusion and at least one corresponding receiving portion configured to receive the protrusion. The protrusion can be a prong or tine, or other extension. The receiving portion can be a recess or depression, or an aperture or window (or cut out), as appropriate to the geometry of the device. In some examples, the at least one protrusion extends from either: the moveable contact, or from at least one of the first and second conductors. The at least one corresponding receiving portion is formed in the other of the moveable contact or the at least one of the first and second conductors. Optionally, the protrusion (or the receiving portion) extend from (or are formed in) the first and/or second contact portions of the first and/or second conductors. Optionally, the protrusion (or the receiving portion) extend from (or are formed in) the rim portion of the moveable conductor. By positioning part of the locking mechanism in the rim portion of the moveable contact, the locking mechanism can form the last poi nt of electrical contact between the moveable and fixed conductors during operation of the device; the position of the electric arc formed during separation of the conducting components may therefore be reliably ascertained and arc suppression mechanisms suitably placed.

In some examples, the device comprises a housing arranged to retain the first and second conductors and to enclose the moveable conductor, the (inner face(s) or wall of the) housing partially defining the second cavity. The first and second contact portions are exposed by, or protrude from, the housing to facilitate electrical contact with the moveable conductor. Exposing only part of the first and second conductors in this way may improve electrical isolation of the rest of the first and second conductors from the moveable conductor, and from each other. In some examples, the second cavity comprises recesses formed in the housing, the recesses aligned with the first and second conductor portions. When the device is ignited or actuated, air and/or gas released by the pyrotechnic charge is directed into these recesses, increasing the length of the arc generated at the ends of the first and second conductor portions. In particular, pushing the air in which the arc has formed into the recesses elongates the arc; the arc can therefore be suppressed without increasing the spatial separation between the conductors themselves, removing the need for a large device housing. A more compact device may therefore be provided.

In some examples, one or more protruding features are provided, which extend into the second cavity. These features can be formed from (or integral to) the housing, or can be otherwise joined to the housing, e.g, by adhesive or mechanical fastening(s). The protruding features are configured to arrest/retard the moveable conductor as it is displaced by the gas from the ignited pyrotechnic charge, thereby lessening the impact force of the moveable conductor when it hits the housing at the bottom of the second cavity. The protruding features can additionally or alternatively, depending on their geometry, retain the moveable conductor in its displaced position (optionally retaining the moveable conductor at the base of the second cavity); this can prevent the moveable conductor returning to (or making) electrical contact with the fixed conductors. A safer, orientation independent, device may therefore be provided.

Optionally, the housing is formed from a first portion and a second portion, the first portion arranged to retain the first and second conductors and the pyrotechnic charge, and the second portion at least partially defining the second cavity, wherein the first and second portions of the housing are connectable with a threaded joint. A threaded joint or threaded connection provides a releasable closing mechanism, allowing easy assembly of the housing without the need for additional components. Optionally, surfaces of the first and second portions of the housing are configured to engage to form a ratchet mechanism, the ratchet. mechanism configured to prevent undoing of the threaded joint This ratchet mechanism can provide a tamper proof device with a permanent connection, without the need for specific fastenings or other components.

Easier device assembly may therefore be facilitated.

Also described herein is another example electrical interrupter. The electrical interrupter device of this additional example does not require use of the form of current conduction path opening or interruption described above; rather, any suitable arrangement of conductor(s) may be provided, and any suitable design or method for breaking or separating the conductor(s) may be used to interrupt the current conduction path.

The electrical interrupter comprises: at least one conductor defining a current conduction path through the interrupter, a pyrotechnic charge configured to interrupt the current conduction path upon ignition, and a housing configured to at least partially enclose the at least one conductor and the pyrotechnic charge. The housing comprises: a first portion having a first surface, the first surface comprising a first plurality of asymmetric teeth; and a second portion having a second surface, the second surface comprising a second plurality of asymmetric teeth. One of the first and second portions comprises a threaded element and the other of the first and second portions is configured to engage the threaded element (to form a threaded connection upon rotation of one of the components in a First direction). Moreover, upon rotation of the one of the first and second portions in the first direction, the first and second pluralities of asymmetric teeth are configured to engage to form a ratchet mechanism. The ratchet mechanism is configured to allow further rotation in the first direction to form the threaded connection between the first and second portions, and to prevent rotation in a second direction opposite the first direction, Optionally, the first surface is bisected by one or more openings, such that the first plurality of asymmetric teeth are formed in two or more separate segments. This segmented or bisected series of teeth can facilitate flexibility of the housing structure during joining of the first and second portions, and can allow for easier assembly. Stress build up within the housing structure during operation of the device can also be is reduced by the use of such openings, or cut outs.

In another aspect, a method of opening a current conduction path is provided. As described herein, the method comprises: igniting a pyrotechnic charge to cause a release of gas; and exerting, by the release of gas, pressure on a moveable conductor arranged between and in electrical contact with a first conductor and a second conductor to define a current conduction path. The moveable conductor has an inner surface defining a volume of the moveable conductor and an outer surface. The moveable conductor comprises: a rim portion having a third contact portion and a fourth contact portion, wherein the third contact portion is configured to be in electrical contact with a first contact portion of the first conductor and wherein the fourth contact portion is configured to be in electrical contact with a second contact portion of the second conductor, and a body portion, the inner surface of the body portion at least in part defining a first cavity and the outer surface of the body portion partially defining a second cavity. The pyrotechnic charge releases the gas into the first 3(1 cavity during performance of the method, thereby displacing, by the exerted pressure, the moveable conductor into the second cavity to open the current conduction path.

A system is provided, which comprises an electrical interrupter as described with reference to any example above, and a controller arranged to provide a signal to the pyrotechnic charge to cause ignition of the charge and actuation or operation of the device. A vehicle is provided comprising an electrical interrupter as described with -8 -reference to any example hove, and/or the system. Optionally, the vehicle is an electric vehicle.

It will be understood that any of the features described above with reference to the device of the first aspect may be provided in any suitable combination. Moreover, any such features maybe combined with any features of the method of the second aspect, or vice-versa, as appropriate.

Brief Description of the Drawings

The following description is with reference to the following Figures: Figure 1 illustrates an example electrical interrupter device, where the device is in a closed position and a current conduction path is defined through the device: Figure 1A illustrates a cross section of the device, and Figure iB illustrates a perspective view of the device; is Figures 2A to 21) schematically illustrate side views of example arrangements of the conducting components defining or forming the current conduction path through the device; Figures 3A to 3D schematically illustrate side views of other example arrangements of the conducting components defining or forming the current conduction path through the device; Figure 4A further illustrates a perspective view of the specific conductor arrangement shown in Figure 31), and Figure 413 illustrates an alternative perspective view of the fixed conductors of that arrangement; Figure 5A illustrates a perspective view of a locking mechanism, here implemented with the specific conductor arrangement shown in Figure 3D, and Figures 5B and 5C schematically illustrate other, alternative, locking mechanisms; Figure 6 illustrates a ratchet mechanism formed by first and second portions of a housing of the electrical interrupter: Figure 6A illustrates a perspective view of a first portion of the housing, and Figure 6B illustrates a perspective view of a second portion of the housing; Figures 7A and 7B illustrate a vehicle comprising an electrical interrupter device and Figure 8 illustrates a method of opening a current conduction path using an electrical interrupter as described herein,

Detailed Description -9 -

With reference to Figures IA and 113, an electrical interrupter device too (such as an isolator, disconnector or other form of electrical interrupter) for opening a current conduction path is described.

Device 100 comprises a first conductor 1.02, a second conductor 104 and a moveable conductor 108 arranged between and electrically connected or coupled to (in electrical contact with) the first and second conductors to define a current conduction path through the device 100. In particular, a first contact portion 102a of the first conductor 102 and a second contact portion 104,a of the second conductor are configured to be in electrical contact with a third contact portion 108a and a fourth contact portion 1.08b of the movable conductor 106, respectively, in order to define the current conduction path.

Device 100 further comprises a pyrotechnic Charge n6 which is arranged, upon ignition, to move or displace the movable conductor 108 in a first direction 132 to open the current conduction path and prevent electrical current flowing through the device too. A housing n8 (shown as comprising portions 118a and n8b) is also provided to enclose the pyrotechnic charge n6 and the moveable conductor 106. The housing is also here arranged to retain the first and second conductors such that the first and second contact portionsia2a,104a are exposed by, or protrude/extend from, the housing. In some examples, housing portion n8a can be moulded over the first and second conductors. The first and second conductors are isolated and electrically insulated from one another by the housing, and the respective contact portions 102a, 104a are accessible through the housing to facilitate electrical contact with the moveable conductor 106.

The movable cond uctor 106 is arranged to form an open three-dimensional shape into which the pyrotechnic charge 116 can be at least partially inserted or placed (through an open face of the moveable conductor). The pyrotechnic charge is retained in the first cavity 124 by the housing il8, to which the charge 166 is connected or coupled. In some examples, the charge can be inserted into and retained by, or within, the housing 118a. The moveable conductor has an inner surface 1.12 (that defines an internal volume of the movable conductor, such that the pyrotechnic charge is placed partially within the volume of the moveable conductor) and an outer surface 114. In some examples, the housing 118a is also configured to extend into the inner volume of the moveable -10 -conductor to reduce the volume of the first cavity 124; in this way, high pressures may be generated within the first cavity for a relatively small charge.

The inner surface and/or outer surface may be a single continuous surface, or may comprise one or more faces, depending on the particular geometry or shape of the moveable conductor. The inner and outer surfaces maybe the same shape (but With different dimensions, according to the thickness of the moveable conductor), or maybe different shapes or geometries.

Iv In the examples described herein, the movable conductor 106 comprises a rim portion 108 proximate the open part (or open face) of the moveable conductor, and a body portion 110 coupled to, or formed integral with, the rim portion w8. The rim portion comprises the third contact portion 108a and the fourth contact portion tab, and is the portion of the moveable conductor m6 which contacts (either directly, or via one or more intermediate components or materials) the first and second conductors 102, 104. When the device is in use, electrical current passes from one of the third and fourth contact portions 108a, tab to the other (depending on the electrical connection of the device to an external circuit), the current passing around the rim portion 108 and from the rim portion through the body portion BD of the moveable conductor 106 to define the current conduction path through the device. 100.

In some examples, a small amount of electrically conductive adhesive or solder can be used to electrically connect the respective conducting components (conductors 102, 104, and 106) in the current conduction path. In other examples, the first and second contact portions are arranged in direct electrical and physical contact with the third and fourth contact portions. For example, the interface between the third and fourth contact portions 108a, 108b and the first and second contact portions to2a, 104.b can be a press fit or interference fit interface. In other words, the physical fit between the moveable conductor to6 and the first and second conductors 102, 104 is sufficiently close or tight that the moveable conductor is held in physical and electrical contact between the first and second conductors by the pressure (and resulting frictional force) experienced between the respective surfaces of the contact portions 102a, 108a and 104a, 1.08b. By retaining the moveable conductor through the use of press or interference fit, a smaller pyrotechnic charge may be used as compared to devices that employ a continuous conductor or a more permanent join (such as a weld), since less force is required to break or open the temporary current conduction path. A cheaper and more compact device may therefore be provided. Moreover, a press fit interface may allow for a device which is quicker and easier to assemble, further reducing manufacturing costs.

The inner surface 112 of the body portion no of the movable conductor 106 at least in part defines a first cavity 124, into which the pyrotechnic charge no is arranged to release gas upon ignition in order to displace the movable conductor in the first direction 132. The rest of first cavity 124 can be defined by the pyrotechnic charge and one or more portions n8a of the housing 118, and by any other suitable components.

The device 100 is arranged such that the gases emitted from the pyrotechnic charge n6 are substantially contained within the first cavity 124 until the pressure increase within the first cavity 124 is such that the moveable conductor 106 begins to be pushed away from the first and second conductors 102, 104, For example, the pressure exerted by the gas from the pyrotechnic charge can cause the moveable conductor to expand /5 radially outward and be forced away from the first and second conductors, breaking or overcoming the press fit interface between the conducting components. The moveable conductor will be then accelerated relatively quickly, due to its small mass and the high pressures, and the lack of any frictional resistance, providing rapid actuation and opening of the current conduction path.

In some examples, the press or interference fit between the contacting portions of the respective conductors can act as a seal, but optionally one or more seals or seal rings 134 can be used to minimise or prevent the flow or air or other gases (i.e. fluid flow) into and out of the first cavity 124. For example, seal rings 134 can be provided between the moveable conductor and the housing portion 1181), and between the two housing portions n8a, n8b. The seal rings 134 are optionally retained by the housing, in cavities or recesses configured to hold the seal rings. It will be understood that, during normal operation of the device 100, a pressure differential between the first and second cavities should be reduced or minimised to help prevent deformation of the moveable conductor 106 in response to such a pressure differential. The expansion of the moveable conductor can then reliably occur in an activated or actuated state of the device, where the current conduction path is desired to be broken. The expansion of the moveable conductor allows some gas to escape the first cavity through narrow gaps, but increased pressure is maintained within the first cavity and the full release of gas does not occur until the moveable conductor begins to move in direction 132, opening the first cavity 124.

The miter surface 114 of the moveable conductor at least partly defines a second cavity 126, towards or into which the movable conductor is configured Lobe displaced by the pressure exerted on the movable conductor from the released gas. The second cavity 126 is further defined by one or more portions 11.8b of the housing n8. Optionally, the second cavity maybe sealed by one or seals or seal rings 134, in order to prevent high pressure, high temperature gases from leaking out of the device 100. In optional examples, the second cavity can comprise one or more vents or other outgassing features in the housing portion n8b configured to allow the high pressure gas to be ro expelled. The vents can extend partially or fully though housing 118b; where a portion of the housing is retained at the end of a vent, the high pressure gas can break or rupture the portion of housing at the end of the vent to allow the gas to be expelled.

The second cavity is defined partly by the moveable conductor in normal operation of the device (i.e. when the moveable conductor is positioned such that the device is in closed position and a current conduction path is defined). However, it will be understood that as the moveable conductor moves, the boundary of the second ccuity will change accordingly. Therefore, references to the moveable: conductor being in the second cavity are references to the moveable conductor being in, or occupying, space defined as being within the second cavity during normal operation, before any displacement of the moveable conductor occurred. Once the movable conductor is 'within' the second cavity, the moveable conductor is no longer in physical or electrical contact with the fixed first and second conductors 102,104 and the current conduction path may be broken. By providing the current conduction path via the rim portion of the moveable conductor, rather than via the body portion, it will be understood that only a relatively small displacement of the moveable conductor is required to break the electrical and physical contact with the first and second conductors. A rapid opening of the conduction path may therefore be provided.

The inner walls or surfaces of housing portion n8b, winch (along with the outer surface of moveable conductor) define the second cavity 126, may comprise one or more protruding features 130 extending into the second. cavity. These features 1:10 may be formed integral with the housing, or can he inserted into the second cavity 126 during manufacture of the device 100. In implementations where the device 100 is reusable (subject to re-insertion of a moveable conductor and replacement of the charge 116), these protruding features 130 may be sacrificial; in these examples, the protruding features may be replaced when the device 100 is reset. The protruding features may be rigid, particularly when integral with the housing, or may be deformable, optionally resiliently deformable (by form and/or by material). For example, the protruding features 130 may be formed as cantilevered springs which are configured to deform as the moveable conductor 106 travels in direction 132 but to resist deformation in a direction opposite the first direction (due to their chamfered shape), thereby preventing return of the moveable conductor.

The protruding features 130 can retard or arrest the movement of the moveable conductor 106, and can retain the moveable conductor:too at the base of the cavity 126, thereby preventing the moveable conductor 106 returning to electrical contact with the first and second conductors 102, 104. A safer, orientation independent, device may therefore be provided. Moreover, by retarding passage of the moveable conductor 106 through the second cavity, the protruding features can lessen the impact force of the is moveable conductor hitting the base of the second cavity 126; since the housing 1181) does not have to withstand high impact forces, a thinner, lighter housing may be used, facilitating provision of a lighter, smaller and cheaper (since less material is required to manufacture the housing) device ma In some examples, a volume WO of the first cavity 124 is less than a volume MO of the second cavity 126. Since the released gas cannot expand until the moveable conductor begins to move, having a first cavity with a relatively small volume can allow high pressures to be obtained for a relatively small pyrotechnic charge. Optionally, the volume of the second cavity 126 is more than two times the volume of the first cavity 124, optionally more than three times the volume of the first cavity 124, optionally more than four times the volume of the first cavity 124. By implementing a device with such a volume ratio between the two cavities, the pressure (P2) in the second cavity upon displacement of the moveable conductor:too is correspondingly reduced by the same ratio as compared to the pressure (P1) in the first cavity (PAT, = P0,72). Therefore, the 3o housing 118 may be provided with relatively thinner walls in the second housing portion itSb, since it is not necessary for the housing to withstand the high forces exerted by the high pressure gas in the first cavity (i.e. those exerted on the moveable conductor). A smaller, thinner housing may therefore be provided, facilitating a cheaper, lighter-weight, and smaller device.

-14 -As the contact portions 108a, ro8b of the moveable conductor 106 separate from the contact portions to2a, 104a of the first and second conductors, an electric arc (or arc discharge) is formed in the air between the separating conductors. The rapid acceleration of the moveable conductor 106 can elongate the arc quickly, allowing for the device to be use for electrical interruption in high current applications. In some examples, the second cavity 126 may additionally comprise recesses or depressions 128 formed in the housing 148b. Since the electric arc is reliably generated at the last point of electrical contact between separating conductors, i.e. between the respective contact portions, the recesses 128 can be formed in the housing at the appropriate location to facilitate extinguishing of the arc; in the examples described herein, the recesses are aligned with the third and fourth contact portions 108a, tab along the first direction 132 (i.e. along the direction of motion of the moveable conductor 106).

The position of the recesses 128, aligned with the separating conductors, causes air or other gas to be directed out of the first cavity 124 upon displacement of the moveable conductor and into the recess or depression, elongating the arc. By stretching the arc into the recess 128 through the movement of the air/gas, the arc resistance can be increased, which causes a corresponding increase in arc voltage and a decrease in arc current (since electrical arcs exhibit negative resistance). By using depressions or recesses 128 in the cavity 126 to stretch or elongate the arc in this way, sufficient spatial separation can be provided to quickly increase the arc resistance, without the need for a large physical separation between the respective conductors along the first direction 132. A smaller, safer, device may therefore be provided, which facilitates the effective extinguishing of electric arcs. Moreover, the recesses 128 can provide spatial separation between walls of the housing to contain the arc and avoid burnout of the housing portion 118b.

Arc interruption or extinguishing can be further improved through the use of arc extinguishing media. This may be of particular benefit in high current applications. In some examples, arc extinguishing media maybe provided to fill some, or all, of the void within the first cavity 124 (not shown) into which the gas is released by the pyrotechnic actuator; a pressure is then either increased within the remainder of the first ea-vity 124 due to activation/ignition of the pyrotechnic charge 116, or the pressure from the released gas is transmitted via (propagated through) the media to the moveable conductor (i.e. as a shock wave). As the moveable conductor 106 is displaced by (i.e. in response to) the increased pressure within the cavity 124 caused by the ignition of the pyrotechnic charge 116, the media is correspondingly displaced from the first cavity and into the second cavity 126. The media may therefore be pushed into the recesses 128 with the air/gas as the moveable conductor is displaced, and may further help suppress arc formation. The use of such an arc extinguishing media may thereby facilitate the provision of a safer electrical interruption device.

In this group of embodiments, the arc extinguishing media comprises silica. The silica media can be provided in any suitable form, for example as a liquid, powder or other solid, or as a thick, viscous, semi-solid liquid. For example, the silica may be provided as silica gel. However, it will be understood that the are extinguishing media can comprise silica in any suitable form. Alternatively, any other suitable arc extinguishing media may be used.

With reference to Figures 2,3 and 4, example arrangements of the conductors or is conducting components of the device 100 will now be described. These conductors define the current conduction path through device loth In these examples, the third and fourth contact portions 108a, ro8b are arranged opposite one another, on opposite sides of the rim 108, This symmetrical arrangement can facilitate improved retention of the moveable conductor. The arrangement may also facilitate a more even distribution of electrical current flow around the rim 108 of the moveable conductor, and prevent areas of high current, which areas may overheat. However, any suitable location for the contact portions can be used, depending on the application of the device.

In Figure 2 (Figures 2A to 2D), a side view of a moveable conductor having a rectangular cross section is shown. The body portion 110 of the moveable conductor may be cylindrical, or it may be an elongated cubic shape, or a cube (not shown), as appropriate. The rim portion 108 is configured to extend around the entire circumference or perimeter of the body portion 110, and will be understood to be pa formed with an appropriate geometry for the geometry of the body portion no, In Figures 2A and 2C, the third and fourth contact portions 108, 108b are formed on the outside surface 114 of the rim portion 108. In these examples, the moveable conductor may not be retained by press fit, since it will be understood that in such circumstances the radial expansion of the moveable conductor 166 upon ignition of the pyrotechnic charge would increase, not overcome, the force of the press fit. Instead, the moveable conductor may be in any other appropriate form of electrical contact with the first and second conductors, and retained by any suitable mechanism (such as by the locking mechanism described further with reference to Figure 5). In Figures 213 and 2D, the third and fourth contact portions 108, to8b are formed on the inside surface (not visible) of the rim portion 108; dashed lines show the location of the first and second contact portions 102a, 1.04a within the first cavity defined by the inner surface of the moveable conductor. In these examples, radial expansion of the moveable conductor 106 may overcome any press fit interface, allowing the moveable conductor to be rapidly accelerated towards the second cavity.

In Figure 3 (Figures 3A to 3D), a side view of a moveable conductor having a semicircular cross-section is shown. The body portion no of the moveable conductor may be hemispherical (half a sphere), or it may be comprise semi-circular end portions connected by one or more faces, as appropriate. The rim portion 108 is configured to /5 extend around the entire circumference or perimeter of the body portion a, and will be understood to be formed with an appropriate geometry for the geometry of the body portion no. In Figures 3A and 3C, the third and fourth contact portions 108, 108b are formed on the outside surface 114 of the rim portion -1,08. In these examples, the moveable conductor may not be retained by press fit, since it will be understood that in such circumstances the radial expansion of the moveable conductor lob upon ignition of the pyrotechnic charge would increase, not overcome, the force of the press fit. Instead, the moveable conductor may be in any other appropriate form of electrical contact with the first and second conductors, and retained by any suitable mechanism (such as by the locking mechanism o described further with reference to Figure 5). In Figures 313 and 31), the third and fourth contact portions 108, ito8b are formed on the inside surface (not visible) of the rim portion 108; dashed lines show the location of the first and second contact portions 102a, lima within the first cavity defined by the inner surface of the moveable conductor. In these examples, radial expansion of the moveable conductor 106 may overcome any press fit interface, allowing the moveable conductor to be rapidly accelerated towards the second cavity.

In all of these exam-pies the first arid second conductors 102, 104 can be generally bent or straight, as appropriate for the size and shape and intended orientation of the device 100. However, it will be understood that, regardless of the position of the first and second contact portions 102a, 104a, at least the first and second contact portions of the first and second conductors 102, 104 are shaped to correspond to the inner surface of (the rim portion of) the moveable conductor, where appropriate. By having corresponding (optionally mating) geometries, good electrical and physical contact may be provided, and a press fit interface may be formed between the mating components. Where the contact portions are on the outer surface of (the rim portion of) the moveable conductor, any other suitable mechanism for providing electrical contact between the conducting components may be provided.

One specific arrangement of conducting components is discussed in more detail with reference to Figures 4A and 4B of the application. in this example arrangement, the moveable conductor 106 comprises a hemispherical body portion 110 and a cylindrical rim portion 108 disposed around the circumference of the hemisphere. The outer surface of the rim portion io8 is substantially continuous with the outer surface of body portion 112, and these portions may be formed integral to one another, such that the moveable conductor is a single component. In other examples, the body portion and the rim portion may be formed separately and joined by any suitable means (weld, solder, braze, conductive adhesive, etc.).

A cylindrical rim provides a uniform surface for contact with the first and second conductor portions 102a, 102b, and can facilitate good electrical and physical contact between the corresponding surfaces. A uniform shape may also be easier to manufacture than more irregular shapes. The first and second conductors are here shaped such that the first and second contact portions correspond (or conform) to the inner surface 112 of the moveable conductor (i.e., the first and second contact portions 102a, 104a have a convex cylindrical shape to conform to the concave cylindrical shape of the inner surface), though in the examples discussed with reference to Figures 2A, 2C, 3A and 3C, the conductors can be shaped to correspond to the outer surface 114 of the rim portion. in examples where the moveable conductor is retained between the 3o first and second conductors by press fit, the first and second conductors and the moveable conductor can be manufactured as mating parts in order to achieve the desired press fit or interference fit interface between the components.

The body portion no of this example is shaped like a dome, or half of a sphere and has a semi-circular cross section. Both the inner and outer surfaces are shown as hemispherical, and the moveable conductor has a uniform thickness, but it will be -18 -understood that the thickness of the moveable conductor to6 may vary across the body portion no such that one of the surfaces may not be hemispherical. The thickness of the moveable conductor, and any variations in thickness, may be designed or determined in dependence on an application for the device 100, such as an intended current rating.

The use of a body portion 110 with a hemispherical inner surface 112 can facilitate effective and efficient displacement of the moveable conductor, since the pressure distribution along the inner surface 112 (resulting from the release of gas from the iv pyrotechnic charge n6) is uniform, with no singularities or discontinuities. The moveable conductor to6 is therefore unlikely to fracture before the pressures builds up within the cavity 124 and overcomes the press-fit or interference fit interface with the first and second conductors. In other examples, the inner surface 112 of the moveable conductor may be curved, but not necessarily hemispherical. For example, the is moveable conductor may have irregular curves, or may be cylindrical. Tt will be understood that moveable conductors with more irregular geometries, such as a cylinder, may in some cases fracture before the frictional forces at the press-fit interface are overcome (due to high stresses and high pressure concentrations in certain areas of the shape, for example, the corners); however, depending on the size of the pyrotechnic charge n6 and the thickness of the moveable conductorit6, any suitable geometry may be used. The size and shape (geometry) of the moveable conductor may be dependent on the particular application of the device too.

with further reference to Figure 4B, the housing n8a can be configured to retain the first and second conductors. in retaining the conductors 102, 104, the housing 118a can partially enclose the conductors. However, in order to facilitate electrical connection between the conductors 102, 104 and the moveable conductor to6, the first and second contact portionsto2a, to4a can protrude from or be exposed by the housing n8a. The housing n8a is formed of an insulating material, optionally plastic, so by enclosing the 3o conductors in this way, electrical contact between the respective conductors is limited to the defined contact portions; the third and fourth contact portions 108a, 108b are in electrical contact with the rim portion 108, and the rest of rim portionto8 is insulated from the first and second conductors. This provides a reliable position for arc formation when device too is ignited or activated, i.e, the arc is consistently and repeatedly generated at the contact portions. The end of the housing n8a proximate the first cavity 124 may also be tapered to facilitate ease of assembly; in this example, the first and second conductors 102, 104 are exposed through this tapered end portion, and are also correspondingly tapered.

In the example shown in Figure 411, at least part of the housing is arranged to mate with the rim portion 108 of the moveable conductor, and the first and second conductor portions 102a, 104a are exposed through the mating part of the housing and inset or arranged flush with the housing. By providing a mating housing 118a, configured to mate with the rim portion 108, the press fit can be strengthened; this arrangement can therefore further retain the moveable conductor between the first and second conductors 102, 104. For example, the housing portion n8a can be formed as a cap component containing or retaining the pyrotechnic charge, and the moveable conductor can be press fit onto the cap to define or form the current conduction path in the cap n8a; the cap can be then be fit or joined to the housing portion n8b to define the second cavity and enclose the electrical interruption mechanism.

In some examples, the device 100 may comprise an additional locking mechanism configured to physically retain the moveable conductor in electrical and physical contact with the first and/or second conductors. The locking mechanism is in addition to the press fit or interference fit interface (or other electrical contact mechanism) between the respective conductors, and can act as an anti--vibration feature. The use of the locking mechanism can further reduce accidental breaking of the current conduction path in environments or operating conditions where the device may experience, or be subject to, vibrations and/or shocks. Depending on the configuration of the locking mechani.sm, the locking mechanism can also minimise or prevent rotation or loosening of the moveable conductor relative to the first and second conductors. A safer, more robust device may therefore be provided.

With reference to Figures 5A and 513, the locking mechanism can in some examples comprise at least one protrusion 120 and at least one corresponding receiving portion 122 configured to receive the protrusion. The receiving portion 122 can be a window or aperture formed in the fixed first and/or second conductors 104, 106, or in the moveable conductor 106. The receiving portion may alternatively be a recess or depression formed in the fixed first and/or second conductors 104, 106, or in the moveable conductor -J.06. The protrusion(s) 120 can be formed in the other of the move-able conductor 106 or the first and/or second conductors 104, mo, such that each protrusion 120 is received by a corresponding receiving portion 122. The protrusions -20 -can have a thickness less than a thickness of the conductor on which they are formed, or from which they extend or protrude, to facilitate rapid separation of the conducting components (i.e. the protrusion(s) can be configured to bend or deform as the moveable conductor moves under the high pressures exerted by the released gas). Various example arrangements are shown in Figures 5A and 5B, but the locking mechanism is not limited to these arrangements.

In some examples (see Figure 5A), wrongs or protrusions 120 are formed on the moveable conductor 106, extending from the rim portion 108 of the moveable contact.

ro The protrusions are received within corresponding apertures 122 in the first and second conductors 102, 104, and can be pushed into the apertures or receiving portion during assembly of the device. The protrusions 120 are bendable or deformable under the pressures exerted by the pyrotechnic charge n6, such that the protrusions 120 bend as the moveable conductor 106 is displaced in direction 132 into or towards the second cavity 126, As the moveable conductor moves, the protrusions 120 are released from the receiving portions or apertures 122, hut the protrusions can remain in electrical contact with the first and second contact portions 102a, naLra as the moveable conductor 106 moves. The protrusions 120 (whether formed on the moveable conductor or the fixed first and second conductors) may thus form the last point of electrical contact between the respective conductors as the device 100 is operated. The electric arc formed on breaking of the current conduction path is therefore formed at the tip of the protrusion(s) 120, and the protrusions can provide a reliable location for arc formation, allowing for the appropriate placement of arc suppression features (such as recesses 128).

With reference to Figures 6A and 6B, the housing portions n8a and n8b may be joined by a threaded joint or a threaded connection. T he two interfaces 150 of the threaded connection are shown in these Figures, but the threads themselves are not represented. One of the first 11.8a and second 118b portions comprises a threaded element, and the 3o other of the first and second portions is configured to engage the threaded element (upon rotation of one of the first and second portions in a first direction of rotation). This arrangement provides for a device 100 which is easily 'assembled, without the need for additional fasteners.

As the housing portions n8a and n8b are rotated to engage the threaded connection, respective first and second surfaces of the first n8a and second n8b portions of the housing may be configured to engage to form a ratchet mechanism, the ratchet mechanism configured to prevent undoing of the threaded joint or connection. The use of a ratchet mechanism allows for a tamper proof device, which can be easily assembled (since the device can be closed in a non-releasable manner without use of additional fastening or joining components). in the examples shown with reference to Figures 6A and 6B, the first and second surfaces extend perpendicular to the threaded interface 150, but any other suitable arrangement may be provided. For example, the surfaces may be disposed parallel to the interface 150 in any suitable arrangement.

In some examples, the ratchet mechanism is formed by two corresponding series of asymmetric teeth, arranged to interlock or engage one another (one set of teeth takes the place of a pawl in a standard ratchet). In particular, the first surface of the first portion 118a of the housing comprises a first plurality of asymmetric teeth 200, and the second surface of the second portion ni8b comprises a second plurality of asymmetric teeth 202. Upon rotation of one of the first and second housing portions in the first direction of rotation, the first and second pluralities of asymmetric teeth are configured to engage to form a ratchet mechanism, the ratchet mechanism configured to allow further rotation in the first direction to form the threaded connection between the first and second portions, and to prevent rotation in a second direction opposite the first direction of rotation. With particular reference to Figure 6B, the second surface may be bisected by one or more openings 204, such that the second plurality of asymmetric teeth are formed in two or more separate segments 206. This arrangement can allow for flexibility of the housing during assembly, providing stress relief which can minimise or prevent breaking of the housing structure during assembly and operation of the device.

With reference to Figure 7, example uses of an electrical interrupter too (as provided above are described. In the example of Figure 7A, device 100 is incorporated within a powertrain 720. In particular, powertrain 720 can be a powertrain for a vehicle 700; in regard to a vehicle (e.g. a motor vehicle, a ship or boat, or a plane, etc.), a powertrain encompasses the main components that generate power and deliver it to the road surface, water, or air. This includes the engine, transmission, drive shafts, arid the drive wheels (or other drive mechanism, such as a propeller). In an electric or hybrid vehicle, the powertrain 720 also includes battery 730 and an electric motor, for example. Device 100 may be connected, via the first and second conductors 102, 104, to an electrical circuit 750 within vehicle 700. which electrical circuit may optionally include the battery 730. Alternatively, in the example of Figure 713, device 700 is employed for another use within vehicle 700, which maybe an electrical vehicle.

In both Figure 7A and 78, a signal may be provided to pyrotechnic charge 116 from a remote controller, or a remote power distribution unit, 710 within the vehicle 700. Such a signal maybe issued in response to an external event. For example, when the device 100 is connected to a battery 730 installed in the vehicle 700, an ignition signal may be sent to ignite the pyrotechnic charge rib in response to a collision of the vehicle; the subsequent release of gas into the first cavity 124 can displace the moveable conductor rob in order to open the electrical circuit 750 (by breaking the current conduction path through the device) and prevent the flow of current through the battery 730. Such an arrangement can improve safety in the event of a collision. Alternatively, device 100 and remote controller 710 can form a system which can be deployed in any other application where breaking of a circuit is required, such as in response to an overcurrent condition.

With reference to Figure 8, a method 800 for opening a current conduction path defined within an electrical interrupter (for example, the device 100 provided above) is described.

At step 810, the method comprises igniting a pyrotechnic charge 116 to cause a release of gas; optionally, the ignition of the pyrotechnic charge is in response to an external control signal indicative of a collision or other event requiring interruption of the current conduction path (in order to break the electrical circuit which the device is located on).

At step 820, the gas which is released from the pyrotechnic charge exerts a pressure on a moveable conductor rob arranged between and in electrical contact with a first conductor 102 and a second conductor 104 to define the current conduction path. The 3o pressure can cause the moveable conductor to expand. and be forced away from the first and second conductors. The moveable conductor has an inner surface 112 defining a volume of the moveable conductor and an outer surface 11.4. The moveable conductor further comprises a rim portion 108 having a third contact portion 108a and a fourth contact portion 1081), wherein the third contact portion is configured to be in electrical contact with a first contact portion 1.02a of the first conductor and wherein the fourth contact portion is configured to be in electrical contact with a second contact portion -23 - -lima of the second conductor. The moveable conductor further comprises a body portion no, the inner surface of the body portion at least in part defining a first cavity 124 and the outer surface of the body portion partially defining a second cavity -126.

The pyrotechnic charge is arranged to release the gas into the first. cavity 124 upon ignition. In other words, step 810 can comprise causing a release of gas into a first cavity-at least partly defined by an inner surface of a moveable conductor, and step 820 can comprise exerting (by the released gas) a pressure on the inner surface of the moveable conductor. The pressure which builds within the first cavity in response to the released gas at step 820 acts to displace (step 830) the moveable conductor in a direction into the second cavity to open the current conduction path (step 840). The displacement is in dependence on (i.e. caused by) the exerted pressure, which pressure is sufficient to overcome the forces retaining the moveable conductor between the first and second conductor.

It is noted herein that while the above describes various examples of the electrical interrupter device, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims (18)

1. Claims An electrical interrupter 000 comprising a first conductor (102) comprising a first contact portion (1025); a second conductor (104) comprising a second contact portion (1.04a); a moveable conductor (106) arranged between the first and second conductors to define a current conduction path, the moveable conductor having an inner surface (112) defining a volume of the moveable conductor and an outer surface (114), the moveable conductor comprising: a rim portion (t08) having a third contact portion (108a) and a fourth contact portion (108b), wherein the third contact portion is configured to be in electrical contact with the first contact portion and the fourth contact portion is configured to be in electrical contact with the second contact portion, and a body portion (no), the inner surface of the body portion at least in part defining a first cavity (124) and the outer surface of the body portion partially defining a second cavity (126); and the electrical interrupter further comprising a pyrotechnic charge (16) arranged, upon ignition, to release gas into the first cavity to displace the moveable conductor into the second cavity and thereby to open the current conduction path.
2. 2. The electrical interrupter of claim 1, wherein the first and second contact portions are arranged in direct electrical and physical contact with the third and fourth contact portions,
3. 3. The electrical interrupter of claim 2, wherein the third and fourth contact portions are retained in physical contact with the first and second contact portions by press fit.
4. 4. The electrical interrupter of any of claims it to 3, wherein the third and fourth 3o contact portions are arranged on the inner surface of the rim portion of the moveable conductor, and wherein the first and second conductors are shaped such that the first and second contact portions correspond to the inner surface of the rim portion of the moveable conductor.
5. 5. The electrical interrupter of the any preceding claim, wherein the inner surface of the moveable conductor is curved.-25 - 6.
6. The electrical interrupter of claim 5, wherein the body portion of the moveable conductor is substantially hemispherical.
7. The electrical interrupter of claim 5 or claim 6, wherein the rim portion is
8. 8. The electrical interrupter of any preceding claim, wherein a volume of the first cavity is less than a volume of the second cavity, optionally wherein the volume of the iv second cavity is more than three times the volume of the first cavity.
9. 9. The electrical interrupter of any preceding claim, further comprising a locking mechanism configured to retain the moveable conductor between the first and second conductors.to.
10. The electrical interrupter of claim 9, wherein the locking echanism comprises at least one protrusion (120) and at least one corresponding receiving portion (122) configured to receive the protrusion, the at least one protrusion extending from the rim portion of the moveable contact or from at least one of the first and second conductors, and the at least one corresponding receiving portion formed in the other of the rim portion of the moveable contact or the at least one of the first and second conductors.
11. The electrical interrupter of any preceding claim, further compfising a housing (u18) arranged to retain the first and second conductors and to enclose the moveable conductor, the housing partially defining the second cavity, wherein the first and second contact portions are exposed by or protrude from the housing.
12. 12. The electrical interrupter of claim IL wherein the second cavity comprises recesses (128) formed in the housing, the recesses aligned with the first and second conductor portions.
13. 13. The electrical interrupter of claim it o 9 wherein the housing is formed from a first portion (118a) and a second portion (118b), the first portion arranged to retain the first and second conductors and the pyrotechnic charge, and the second portion at least partially defining the second cavity, wherein the first and second portions of the housing are connectable with a threaded joint.
14. 14. The electrical interrupter of claim 13, wherein surfaces of the first and second portions of the housing are configured to engage to form a ratchet mechanism, the ratchet mechanism configured to prevent undoing of the threaded joint.
15. 15. The electrical interrupter of any preceding claim, further comprising one or more protruding, -features (130) which extend into the second cavity.
16. 16. A ssistem comprising: the device (100) of any preceding claim; and a controller (710) configured to provide an ignition signal to the pyrotechnic charge n6.
17. 17. A vehicle (700) comprising the device (100) of any one of claims Ito 15 or the system of claim 16, optionally, wherein the vehicle is an electric vehicle.
18. 18. A method (800) of opening a current conduction path, the method comprising: igniting (810) a pyrotechnic charge (.16) to cause a release of gas; exerting (820), by the release of gas, pressure on a moveable conductor (106) arranged between and in electrical contact with a first conductor 102 and a second conductor 104 to define a current conduction path, the moveable conductor having an inner surface (112) defining a volume of the moveable conductor and an outer surface (n4), the moveable conductor comprising: a rim portion (i08) having a third contact portion (108a) and a fourth contact portion (108b), wherein the third contact portion is configured to be in electrical contact with a first contact portion 102a of the first conductor and wherein the fourth contact portion is configured to be in electrical contact with a second contact portion 10.4a of the second conductor, and a body portion (no), the inner surface of the body portion at least in part defining a first cavity (124) and the outer surface of the body portion partially defining a second cavity (126), wherein the pyrotechnic charge releases the gas into the first cavity; displacing (830), by the exerted pressure, the moveable conductor into the second cavity to open (840) the current conduction path.