Switch for disconnecting an electrical circuit

Abstract

Disclosed herein is a switch comprising a cam rotatable around a first axis, the cam rotatable in a first direction between an on and an off position and in a second direction between the off and the on position. The cam comprises an axial cam portion and a transverse cam portion, the transverse cam portion comprising a protrusion extending along a direction perpendicular to the first axis and two detents arranged asymmetrically either side of the protrusion, wherein the two detents are arranged at an angle, ϴ, with respect to each other. The switch further comprises one or more biasing members configured to exert a force on the transverse cam portion. The axial cam portion is configured: upon rotation of the cam in the first direction, to cause opening of a current conduction path through the switch; and upon rotation of the cam in the second direction, to cause closing of a current conduction path through the switch. A method of operating the switch is also described.

Description

[0001] Switch for disconnecting an electrical circuit

[0002] Field

[0003] This relates to a switch for disconnecting an electrical circuit. In particular, this relates to a switch for disconnecting an electrical circuit with a manual independent breaking mechanism.

[0004] Background

[0005] Manual switches can be either independent of a user input (i.e. the user has no control over the movement during the actual switching operation) or dependent, where the speed of the switching operation is controlled entirely by user input with no lag or independent motion (i.e. the speed of making / breaking the circuit mirrors the speed of actuation by the user). Other switches may be semi-independent, where part of the movement of the switching components is controlled by a user then there is a sudden, uncontrolled, switching operation.

[0006] Typically, manual independent switches can provide rapid make and break operations, and semi-independent switches can provide either a rapid make or a rapid break operation, depending on the design of the device. However, since the actual make / break operation of a manual independent switch is completely independent of user control, the operation is quicker than with a dependent or semi-independent switch. This is important at high current applications, where rapid opening of a conduction path can be necessary to reduce or minimise arcing within the device. For this reason, dependent and semi-independent devices, which are often simpler and more compact than manual independent devices, are typically only used for lower current applications.

[0007] There is a need for a simpler and smaller switch which is suitable for use at all current ratings, and which has a reduced manufacturing / assembly cost and complexity as compared to other known manual independent switch mechanisms. One such switch is described in UK patent publication GB2608869, the knob of which is configured to rotate a total of 110 degrees, with a 55 degree toggle point for both making and breaking operations; the contacts only begin to move after this toggle point is reached, giving both independent making and breaking operations.

[0008] However, there is also a requirement under the IEC 60947-3 (2020, edition 4.0) standard that the strength of actuator test is passed. In other words, under application of a test force, the actuator mechanism is not able to move to a break (or open) position when the contacts are welded together. Some existing designs with independent breaking provide a safety angle of 20 degrees, meaning that the handle or actuating knob of the switch can be turned 70 degrees when the contacts are welded; this safety margin of 20 degrees can be insufficient to withstand the strength of actuator test force on the knob.

[0009] There is consequently a need for alternative switches with an independent breaking operation, which have reduced manufacturing / assembly cost and complexity as compared to other known manual independent switch mechanisms, and which can also withstand the strength of actuator test (both for direct actuation of the switch and for actuation by an extended shaft, i.e. when the switch is located within a panel or enclosure).

[0010] Summary

[0011] Provided herein is a switch for disconnecting or connecting an electrical circuit in accordance with claim 1, and a method of operating said switch.

[0012] Disclosed herein is a switch comprising a cam rotatable around a first axis, the cam rotatable in a first direction between an on and an off position and in a second direction between the off and the on position. The cam comprises an axial cam portion and a transverse cam portion, the transverse cam portion comprising a protrusion extending along a direction perpendicular to the first axis and two detents arranged asymmetrically either side of the protrusion, wherein the two detents are arranged at an angle, e, with respect to each other. The switch further comprises one or more biasing members configured to exert a force on the transverse cam portion. The axial cam portion is configured: upon rotation of the cam in the first direction, to cause opening of a current conduction path through the switch; and upon rotation of the cam in the second direction, to cause closing of a current conduction path through the switch. In this way, the electrical circuit is disconnected (breaking operation) or connected (making operation).

[0013] The detents of the transverse cam portion provide (or form) first and second stop positions. These are stable positions corresponding to an on state and on off state of the switch. The protrusion of the transverse cam portion provides a toggle point of the switch, before which point rotation of the cam is driven by a user and after which point rotation of the cam is driven by the biasing members and is user independent. Optionally, the switch further comprises a cam follower coupled to the one or more biasing members, wherein a toggle point of the switch occurs when the protrusion of the transverse cam portion aligns with an opposing protrusion of the cam follower.

[0014] By providing asymmetrical detents, the toggle point is reached at different degrees of rotating during the making and breaking operations. This can allow the switch to provide an independent making or breaking operation, as desired, with the other operation being semi-independent. A switch with an independent breaking operation, which has reduced manufacturing / assembly cost and complexity as compared to other known manual independent switch mechanisms, and which can also withstand the strength of actuator test, can therefore be provided.

[0015] In some examples, the one or more biasing members comprise one or more springs.

[0016] In some examples, rotation of the cam towards the toggle point is caused by a user rotation of the cam, and wherein said user rotation of the cam causes the transverse cam portion to compress the one or more biasing members, wherein maximum compression of the one or more biasing members occurs at the toggle point.

[0017] Optionally, after the toggle point, the one or more biasing members are configured to act on the transverse cam portion to cause independent rotation of the cam, wherein the independent rotation of the cam occurs until the protrusion of the cam follower aligns with and is received by one of the two detents of the transverse cam portion. In this way, the switch can provide an independent making or breaking operation, as desired, with the other operation being semi-independent.

[0018] In some implementations, when the cam is rotated in the first direction (towards the off position, i.e. a breaking operation), the toggle point is reached after a first angle of rotation, a. Optionally, when the cam is rotated in the second direction (toward the on position, i.e. a making operation), the toggle point is reached after a second angle of rotation, b. Optionally, the first angle of rotation is less than the second angle of rotation. By providing asymmetrical detents, with a smaller dependent degree of rotation during a breaking operation, the switch can provide an independent breaking operation, as desired, with the making operation being semi-independent. A switch with an independent breaking operation, which has reduced manufacturing / assembly cost and complexity as compared to other known manual independent switch mechanisms, and which can also withstand the strength of actuator test, can therefore be provided. In some specific examples, the first angle of rotation, a, is between 20 and 40 degrees. In some more specific examples, the first angle of rotation is between 25 and 35 degrees. Optionally, the first angle of rotation 30 is degrees. This can increase the speed of a breaking operation by reducing the amount of user input or control required, allowing for a rapid independent breaking operation.

[0019] In some specific examples, the second angle of rotation, b, is between 50 and 70 degrees. In some more specific examples, the second angle of rotation is between 55 and 65 degrees. Optionally, the second angle of rotation 60 is degrees. This can increase the amount of user input or control required, providing a semi-independent making operation.

[0020] In some specific examples, the angle between the two detents is between 70 degrees and 110 degrees. In some more specific examples, the angle is between 80 and 100 degrees. In some more specific examples, the angle is between 85 and 95 degrees. Optionally the angle is 90 degrees. The angle between the two detents can equal the total angle of rotation of the cam.

[0021] In some examples, the protrusion of the transverse cam portion comprises a first edge with a linear profile and a second edge with a curved profile.

[0022] The cam can be arranged such that the angle between the detent proximate to the first (linear) edge of the protrusion and the protrusion (the breaking toggle angle) is the first angle of rotation. This arrangement controls the breaking (off) operation in an independent manner.

[0023] The cam can be arranged such that the angle between the detent proximate to the second (curved) edge of the protrusion and the protrusion (the making toggle angle) is the second angle of rotation. This arrangement controls the making (on) operation in a semi-independent manner, while also increasing the operating torque to switch on the switch. Increasing the operating torque can reduce accidental opening of the switch. The use of a second, curved, edge in the transverse cam portion can also reduce a number of oscillations experienced during the semi-independent operation, whilst preventing the operating torque from being too high (the normal reaction between the cam and the cam follower interfaces passes away from a centre of the cam, resulting in a mechanical advantage in terms of improved moving arm

[0024] characteristics). Optionally, the detent proximate to the first edge of the protrusion has an internal angle of between 120 and 140 degrees. Optionally the detent proximate to the first edge of the protrusion has an internal angle of between 125 and 135 degrees.

[0025] Optionally the detent proximate to the first edge of the protrusion has an internal angle of 130 degrees. This angle can act to control the torque required at an actuating handle or knob during a closing or making operation.

[0026] Optionally, the detent proximate to the second edge of the protrusion has an internal angle of between 120 and 140 degrees, optionally an internal angle of between 125 and 135 degrees, optionally an internal angle of 130 degrees.

[0027] Optionally, the internal angles of the first and second detents are equal. This can improve the stability of the switch by improving engagement of the cam and the cam follower.

[0028] In some examples, the cam has a second protrusion arranged opposite the first protrusion, and a further two detents arranged asymmetrically either side of the second protrusion, wherein the further two detents are arranged at the angle, e, with respect to each other. In some other examples, the cam has third and fourth protrusions similarly arranged. Optionally, the cam can be symmetric around a line of symmetry passing though the first axis of rotation and the detent proximate to the first edge of the protrusion.

[0029] In some examples the switch further comprises a bridge cam contacting the axial cam portion of the cam, wherein rotation of the axial cam portion causes rotation of the bridge cam around the first axis, and wherein the rotation of the bridge cam is configured to open and close the current conduction path through the switch.

[0030] Optionally, the switch comprises one or more fixed contacts and a bridge that is axially displaceable along the first axis in response to rotation of the bridge cam, wherein the bridge comprises one or more moveable contacts. The bridge is configured to bring the one or more moveable contacts into and out of contact with the one or more fixed contacts of the switch to close and open the current conduction path, respectively.

[0031] In some examples the switch further comprises a knob configured for engagement by a user, wherein rotation of the knob around the first axis by a user causes rotation of the cam around the first axis. Also disclosed herein is a system comprising a switch as described herein and an electrical circuit configured to be electrically coupled to one or more fixed contacts of the switch.

[0032] Also disclosed herein is a method for operating the swich to open and close a current conduction path, the method comprising: rotating, by a user, the cam about the first axis from a first stop position to a toggle point; exerting a force on the transverse cam portion of the cam by the one or more biasing members; rotating, by the one or more biasing members, the cam about the first axis from the toggle point to a second stop position; and causing, by the rotation of the cam, the axial cam portion to open or close the current conduction path through the switch.

[0033] The first and second stop positions are provided by the detents of the transverse cam portion. The toggle point is provided by the protrusion of the transverse cam portion.

[0034] List of Figures

[0035] The detailed description is with reference to the following figures.

[0036] FIG. 1A illustrates a perspective view of an interior of an example switch as described herein, the switch being in a break (or off) position, FIG. IB illustrates a perspective view of an interior of an example switch in a toggle position of a break to make operation, and FIG. 1C illustrates a perspective view of the switch of FIG. IB in a make (or on) position.

[0037] FIG. 2A illustrates a top view of an example transverse cam portion of a cam for use with a switch as described herein, for example the switch of FIG. 1A, the cam in an on position.

[0038] FIG. 2B illustrates a top view of the transverse cam portion of FIG. 2A at a toggle point;

[0039] FIG. 3A illustrates a top view of the transverse cam portion of the cam of FIG. 2A and FIG. 2B.

[0040] FIG. 3B illustrates a schematic view of the transverse cam portion of FIG. 3A.

[0041] FIG. 4 shows an example flowchart of a method for operating a switch as described herein to open and close a current conduction path.

[0042] Like reference numerals refer to like features. Detailed description

[0043] With reference to FIG. 1A, IB, and 1C, a switch 100 is described for connection to an external electrical circuit. Switch 100 can be a disconnect device, an isolator switch, or any other form of device for opening and closing a current conduction path defined through the switch to make / break the electrical circuit.

[0044] The switch 100 comprises a first cam 106 (also referred to herein as a knob cam 106), which is configured to rotate around a first axis 130 in response to engagement by a user. The switch 100 further comprises a second cam 102 which contacts the first cam 106 such that rotation of the first cam causes rotation of the second cam. Second cam 102 is also configured to rotate around the first axis 130. The first and second cams are aligned along the first axis and share the same axis of rotation. The second cam 102 (also referred to more generally as cam 102) can be rotated about the first axis 130 in any suitable manner. In some implementations, the cam 102 may be directly actuated by a user (e.g. a knob or handle may be formed as part of cam 102) or actuated by a knob / handle otherwise coupled to the cam 102.

[0045] In FIGS. 1A, IB and 1C, a second cam 102 as described in UK patent publication GB2608869 is shown, but it is understood that this is for illustrative purposes only. Said second cam 102 can be replaced with the second cam 102 described herein and shown in FIG. 2A and FIG. 3A.

[0046] Second cam 102 comprises an axial cam portion configured, upon rotation of the second cam, to cause opening and closing of a current conduction path through the switch. Second cam 102 also comprises a transverse cam portion. The transverse cam portion (see FIG. 2A, FIG. 3A) comprises a protrusion extending along a direction 140 perpendicular to the first axis 130 and two detents 122a, 122b arranged asymmetrically either side of the protrusion, wherein the two detents are arranged at an angle, e, with respect to each other. The transverse cam portion of the cam 102 described herein is provided with a unique shape, with symmetry about two planes separated from one another by 90 degrees (as discussed below with reference to FIG.

[0047] 3A). The particular geometry of this transverse cam portion allows for implementation of a small and compact switch 100 with an independent make or break operation, which switch is suitable for both low and high current applications. The switch may also be less complex than previous devices of similar functionality.

[0048] The manual part of the make / break operation of switch 100 is provided by user engagement. In the example of FIG. 1A, the switch 100 comprises a knob 104 that may be directly engaged by the user. For example, the knob may be mounted on a front of the switch, external to a housing (not shown) of the switch. In some examples, the first / knob cam 106 can be rigidly coupled to the knob 104, such that both the knob 104 and knob cam 106 rotate together; the knob 104 is directly engaged by the user, and the knob cam 106 is therefore indirectly engageable by the user (via the knob). However, alternative arrangements are possible. For example, the knob cam 106 and knob 104 may be formed as a single integral component, in which arrangement the knob cam 106 is considered to be directly engaged by a user. In other examples, one or more further components may be disposed between the knob cam 106 and another component which is engaged by the user to operate the switch 100. In other examples, the knob 104 can be formed or coupled directly with the cam 102 (and there is no first cam 106).

[0049] The cam 102 is configured to be rotatable, at least partially in response to engagement by a user, by an operating angle around the first axis 130, rotating between an "on" (make) position and an "off" (break) position. In the on position, a current conduction path is defined through the switch 100. In the off position (the position shown in FIG. 1A), no current conduction path is defined through the switch. The specifics of the make / break operation of the switch 100 are discussed in more detail below, with reference to FIGS. IB, 1C.

[0050] The operating angle (through which the cam 102 rotates) comprises an initial portion, corresponding to an angle of rotation that is performed, or controlled, by direct engagement / rotation by a user. In other words, the initial portion is the angle through which a user input controls the rotation of the cam 102. Rotation of the cam 102 through the initial portion continues until a "toggle point" of the switch 100 is reached. The toggle point is defined by the geometry of the transverse cam portion of the cam 102, and is discussed below in more detail with reference to FIG. 2A, FIG. 2B and FIG. 3A. After the toggle point, the second cam 102 rotates independently of user control to provide the independent part of the make / break operation. The degree of rotation in the initial portion is different depending on a direction of rotation of the second cam 102 around the first axis 130, due to the asymmetric nature of the detents (discussed below). In other words, the degree of rotation which is user controlled is different in a make operation to in a break operation.

[0051] To provide the user independent rotation of the second cam, switch 100 comprises one or more biasing members 112, which are configured to exert a force on the transverse cam portion of the second cam 102. The force exerted by the one or more biasing members can, depending on the angular position of the second cam, cause the second cam to rotate around the first axis 130 independent of any user input. In the specific example shown in FIG. 1A, the one or more biasing members 112 are portrayed as six springs, arranged on opposing sides of the switch 100. Providing biasing member(s) opposite each other may facilitate improved rotation of the second cam, but it will be understood that only one biasing member may be required to provide the desired independent rotation of the second cam 102 by acting / exerting a force on the transverse cam portion of the second cam 102. For example, only one spring or one set of springs may be provided, and / or any other biasing member may be used in addition to or in place of the springs shown in FIG. 1A. For example, a flexible arm or leaf spring may be used and / or a rubber or elastic members arranged under compression, as appropriate, in order that a force may be exerted by the biasing member(s) on the transverse portion of the second cam.

[0052] In some examples, the one or more biasing members are coupled or connected to a cam follower 110, such that force exerted on the second cam 102 by the biasing members 112 is exerted via or through the cam follower 110. The cam follower 110 is configured to contact the transverse cam portion of the second cam, such that the transverse cam portion urges or pushes the cam follower 110 in a (generally) linear direction along axis 150 perpendicular to the first axis 130 as the second cam 102 rotates under manual operation (see FIG. IB). In other words, the cam follower can follow the motion of the transverse cam portion. However, the cam follower is also configured to contact the transverse cam portion and exert a force on said transverse cam portion in order to cause rotation of the second cam, thereby providing the independent rotation of the second cam 102. The interaction of the transverse cam portion and the cam follower is described below in more detail with reference to FIG.

[0053] 2A, FIG. 2B.

[0054] With further reference to FIG. IB and FIG. 2A, the cam follower 110 comprises one or more protrusions 110a extending along an axis 150 perpendicular to the first axis 130 of the cam 102. The one or more protrusions 110a are configured to contact the transverse cam portion of cam 102. During rotation of second cam 102, cam follower 110 is linearly displaced along the axis 150 by the shape of the transverse cam portion. The axial displacement of the cam follower 110 is facilitated by the use of the biasing members, where said axial displacement in direction 150a of FIG. IB along the axis 150 causes the one or more biasing members 112 to compress against one or more fixed supports (not shown) of switch 100. The compressed biasing members 112 correspondingly exert a force on the transverse cam portion in direction 150b along axis 150 (where direction 150b is opposite direction 150a), as shown in FIG. 1C. In other words, 150a is the direction of compression of the biasing members, and direction 150b is the direction of the biasing force applied by the biasing members.

[0055] With reference to FIG. 3A, the transverse cam portion of first / knob cam 102 comprises a protrusion 120 extending along a direction 140 perpendicular to the first axis 130, and two detents 122a, 122b arranged asymmetrically either side of the protrusion. The protrusion 120 provides or defines the "toggle point" of the switch (see FIG. 2B). The detents 122a, 122b of the transverse cam portion provide (or form) first and second stop positions. These are stable positions corresponding to an on state and on off state of the switch. The two detents are arranged at an angle (0) with respect to each other, where Q = a + b. In some specific examples, the angle between the two detents is between 70 degrees and 110 degrees. In some more specific examples, the angle is between 80 and 100 degrees. In some more specific examples, the angle is between 85 and 95 degrees. Optionally the angle is 90 degrees. The angle between the two detents can equal the total or overall angle of rotation of the cam.

[0056] In FIG. 2A, FIG. 2B and FIG. 3A, the transverse cam portion is shown as having four protrusions 120, with four detents, each detent arranged between respective protrusions. The use of multiple protrusions can enable cam 102 to be operated in a robust manner whether rotating clockwise or anti-clockwise around the first axis of rotation 130. Moreover, allowing for the application of force from biasing members 112 arranged on either side of the transverse cam portion can assist in rotation of the second cam 102 as energy is released from each of the biasing members 112.

[0057] The transverse cam portion of this particular example is arranged such that there is symmetry about two planes 160a, 160b separated from one another by 90 degrees. However, it will be understood that these additional protrusions are optional. The transverse cam portion may provide the functionality described herein with a single protrusion 120 and set of detents 122a, 122b. In particular, the arrangement of the detents 122a, 122b and protrusion 120 of the transverse cam portion is such that the cam 102 can rotate about the first axis 130 between the first and second (stable) stop positions defined by the engagement of the cam follower 110 with the detents, which can facilitate provision of manual independent make or break operation of the switch in a robust and durable manner.

[0058] As is further shown in FIGS. 2A, 2B, 3A, the protrusion(s) 120 of the transverse cam portion of the second cam 102 are arranged such that each protrusion of the transverse cam portion comprises a first edge 124b with a linear profile and a second edge 124a with a curved profile. This curved profile can also be called herein a fillet. As shown in FIG. 3B, the curve or fillet has a radius R. This radius R can be predetermined or optimised for a given application. The curved profile of the second edge 124a extends from the detent 122a to the tip of the protrusion 120. This curved engagement surface of the transverse cam portion enables a more efficient transfer of force between the transverse cam portion of cam 102 and the protrusion 110a of cam follower 110, thus reducing the torque required to rotate the second cam 102 under manual user engagement. The linear profile of the first edge 124b extends from detent 122b to the tip of the protrusion 120.

[0059] The tip of the protrusion is the trigger or toggle point, and the protrusion itself can also be called a "spring charge cam", since it acts to charge or bias the biasing members 112. This can be seen in FIG. 2B, where upon rotation in direction 126 from the on position of FIG. 2A, the protrusion 120 of cam 102 engages with protrusion 110a of the cam follower. This engagement causes the biasing members 112 to be compressed, thereby driving apart the cam followers 110 such that the distance between the protrusions 110a is increased (see FIG. 2B in comparison to FIG. 2A). This compression acts to apply an urging or biasing force on cam 102 after the toggle point of FIG. 2B, causing continued rotation of the cam 102 in the first direction 126 towards the off position (the stable position of detent 122a). The toggle point of FIG.

[0060] 2B is reached after a first angle of rotation, a, from the position of FIG. 2A in which the cam followers 110 engage with the detent 122b (see FIG. 3A). In an opposite direction of rotation 128, the toggle point of FIG. 2B is reached after a second angle of rotation, b, from the position in which the cam follower 110 engages with the detent 122a (not shown). As discussed above, the total or overall angle of rotation of the cam, Q, can be defined as Q = a + b.

[0061] In some examples, the detent 122b proximate to the first edge of the protrusion has an internal angle of between 120 and 140 degrees. This detent can also be called a "side cam". Optionally the detent proximate to the first edge of the protrusion has an internal angle (see angle c in FIG. 3B) of between 125 and 135 degrees. Optionally the detent proximate to the first edge of the protrusion has an internal angle of 130 degrees. In this particular example, as shown in FIG. 3B, the internal angle of each detent is equal, c. By having the same internal angle in each detent, the cam follower 110 is configured to be stable in each position of the cam 102, thereby avoiding any rattling or movement of the cam follower 110 during operation. This internal angle c can be predetermined or optimised for a given application. This internal angle can act to control the torque required to be input at the actuating handle or knob 104 during a closing or making operation. In particular, as the internal angle is increased, the moment arm vector is nearer the centre of rotation of cam 102, which increases the input torque required to rotate the cam. However, this torque has to be balanced with the ability to compress the biasing members 112 on either side of the cam 102. It has been found that an internal angle c of 130 degrees can balance the torque and compression of springs, reducing the effort required by the user to turn the cam 102 whilst also providing a smooth transition when turning the switch 100 from off to on. However, the skilled person will understand that other internal angles can be used instead.

[0062] Switch 100 is configured such that the axial cam portion (not shown), upon rotation of the second cam, causes opening and closing of the current conduction path through the switch.

[0063] The second cam 102 may be configured in any suitable manner to cause opening and closing of the current conduction path. However, in the specific example described with reference to FIG. 1A, switch 100 further comprises an optional cam 108 (which may also be referred to herein as a bridge cam 108). The bridge cam 108 is aligned with the second cam 102 along the first axis 130 and configured to contact the axial cam portion of the second cam, such that rotation of the axial cam portion (when the second cam 102 rotates) causes rotation of the bridge cam around the first axis 108. The second cam is in this example disposed between the first cam and the bridge cam, and can provide a linkage between the rotation input by the user and rotation of the bridge cam. The rotation of the bridge cam is configured in any suitable manner to open and close the current conduction path through the switch 100.

[0064] With further reference to FIG. 1A, switch 100 can optionally comprise a bridge 114 that is axially displaceable along the first axis 130 in response to rotation of the bridge cam, wherein the bridge comprises (or carries) one or more moveable contacts 116. The bridge is configured to bring the one or more moveable contacts 116 into contact with one or more fixed contacts 118 of the switch when the first cam 106 is in the "on" position to close the current conduction path (make operation). Similarly, the bridge is configured to move in an opposite direction to separate the moveable contact(s) 116 from the fixed contact(s) during a break operation to open the current conduction path. An electrical circuit is configured to be electrically coupled to the one or more fixed contacts 118 of the switch. These contacts are separate conducting components of the switch, arranged to define a current conduction path by way of electrical contact between the one or more moveable contacts 116 and the one or more fixed contacts 118 and the electrical circuit. Although FIG. 1A displays an example switch 100 comprising a bridge cam 108 and bridge 114, it will be appreciated that rotation of second cam 102 may cause opening and closing of a current conduction path through a switch in any suitable manner. In particular, it will be understood that the axial portion of the second cam can be configured to open and / or close the current conduction path in any other suitable manner.

[0065] With reference to FIGS. 1A, IB, 1C, the cam 102 can be rotated in a first direction 126 from an on position (FIG. 1C) to an off position (FIG. 1A) and in a second direction 128 from an off position (FIG. 1A) to an on position (FIG. 1C). The axial cam portion is configured, upon rotation of the cam 102 in the first direction 126, to cause opening of a current conduction path through the switch. In an off position, the cam 102 is stable and the cam follower 110 is received by the detent 122a of FIG. 3A. The axial cam portion is configured, upon rotation of the cam 102 in the second direction 128, to cause closing of the switch (making of a current conduction path through the switch). In an on position, the cam 102 is stable and the cam follower 110 is received by the detent 122b of FIG. 3A. In other words, the cam 102 is at the position shown in FIG. 2A.

[0066] When the cam 102 is rotated in the first direction 126 (from the on position of FIG. 1C and FIG. 2A and towards the off position, i.e. a breaking operation), the toggle point (shown in FIG. 2B) is reached after a first angle of rotation, a, from the detent 122b (i.e. the angle between the detent 122b and the protrusion 120). When the cam 102 is rotated in the second direction 128 (from the off position and toward the on position, i.e. a making operation), the toggle point is reached after a second angle of rotation, b, from the detent 122a (i.e. the angle between the detent 122a and the protrusion 120). The first angle of rotation is less than the second angle of rotation. These angles are shown in FIG. 3A. By providing asymmetrical protrusions and detents, with a smaller dependent degree of rotation during a breaking operation, the switch can provide an independent breaking operation, as desired, with the making operation being semi-independent. A switch with an independent breaking operation, which has reduced manufacturing / assembly cost and complexity as compared to other known manual independent switch mechanisms, and which can also withstand the strength of actuator test, can therefore be provided. In some specific examples, the first angle of rotation, a, is between 20 and 40 degrees. In some more specific examples, the first angle of rotation is between 25 and 35 degrees. Optionally, as in the example of FIG. 3A, FIG. 3B, the first angle of rotation 30 is degrees. This can increase the speed of a breaking operation by reducing the amount of user input or control required, allowing for a rapid independent breaking operation. In some specific examples, the second angle of rotation, b, is between 50 and 70 degrees. In some more specific examples, the second angle of rotation is between 55 and 65 degrees. Optionally, as in the example of FIG. 3A, FIG. 3B, the second angle of rotation 60 is degrees. This can increase the amount of user input or control required to actuate the cam 102, providing a semiindependent making operation.

[0067] The overall angle of rotation of the cam 102, Q, is in this example 90 degrees. By arranging the detents 122 of the transverse cam portion of second cam 102 at an angle of 90 degrees, as is illustrated in FIG. 3A, in combination with the toggle points described herein, a safety angle of 45 degrees is provided when the contacts are in a weld state (compared to e.g. 20 degrees for some existing designs). Therefore, independent breaking can be provided in combination with a dependent making operation whilst at the same time providing a safer and more resilient switch.

[0068] FIG. 1A illustrates switch 100 in an open, "break" position, where no current conduction path is defined. With reference to FIGS. IB and 1C, a "make" operation of the switch 100 is described in more detail. In the example of FIG. IB, 1C, the bridge 114 has a different configuration than in the switch of FIG. 1. It will be understood that the underlying operation applies to both bridges, and any suitable bridge configuration may be used for switch 100.

[0069] As a first step, a user rotates the cam 102 (via knob 104, or first cam 106 or otherwise) from the open, off, position of FIG. 1A. At the position of FIG. 1A, the second cam 102 is in a stable stop position, and can be considered to be at 0 degrees of rotation with the protrusion 110a of the cam follower 110 being received by detent 122a. The second cam 102 rotates from the stable position of FIG. 1A in direction 128 to a "toggle point", shown in FIG. IB (as discussed above, the cam 102 shown in FIG. IB is not that described herein, but the cam as described in UK patent publication GB2608869 is shown instead, for illustrative purposes only). At this point, the one or more movable contacts 116 are not contacting the one or more fixed contacts 118, and thus the switch 100 is open with no current flowing through the switch 100. The "toggle point" or toggle position of the switch 100 is an unstable point in the rotation of the second cam 102, which occurs when the protrusion 120 of the transverse cam portion aligns with an opposing protrusion 110a of the cam follower 110. The toggle point occurs both during rotation of cam 102 from the on position to the off position, and during rotation of the cam 102 from the off position to the on position.

[0070] In other words, cam 102 is configured to rotate by the angle Q around the protrusion 120 during each make and break operation. With reference to FIG. 3A, the rotation of the second cam 102 from the stable "off" position at detent 122a to the unstable toggle position is equal to a rotation of the second rotation angle, b. The second rotation angle shown in the particular example of FIG. 3A, for illustrative purposes, is 60 degrees, but the angle may be adjusted depending on the particular application in which the second cam 102 is being implemented.

[0071] At the toggle point of FIG. IB, the one or more movable contacts 116 are not contacting the one or more fixed contacts 118, and thus the switch 100 is open with no current flowing through the switch 100. Although not shown here in detail, rotation of the second cam causes engagement of the axial cam portion, which in turn causes rotation of the bridge cam 108 and a corresponding axial displacement of bridge 114. Axial displacement of the bridge brings the one or more moveable contacts 116 into electrical contact with the one or more fixed contacts 118.

[0072] In this particular example, switch 100 is configured with a rotational offset between the second cam 102 and the bridge cam 108. However, it will be appreciated that delay of the actuation of the bridge may be achieved by other means than by configuring cams 102 and 108 with a rotational offset. For example, cams 102 and 108 may be coupled to each other, and a horizontal cam section may be utilised such that the bridge 114 is not axially displaced until after the toggle point is reached.

[0073] Due to the rotational offset, the bridge cam 108 may not begin to rotate at the time the second cam 102 does. In other words, there is a rotational lag between the second cam 102 and the bridge cam 108. In this specific example the rotational offset is configured such that, up to and at the toggle point of the second cam 102 when rotating in the second direction 128, there has been no corresponding rotation of the bridge cam 108. In other words, manual rotation of the second cam to the toggle point does not cause any rotation in the bridge cam; it is only after the toggle point that the bridge cam begins to move, during the independent rotation of the second cam 102. In this way, no movement towards a make / break operation occurs until the independent portion of the rotation of the second cam 102. The user / manual rotation of the first cam 106 has no effect on the bridge cam, or on any other mechanism to open / close the current conduction path.

[0074] After the toggle point, the bridge cam 108 begins to rotate in response to the user independent rotation of the second cam 102 and bridge 114 is axially displaced. In this way, only after the toggle point of cam 102 is reached does the axial displacement of bridge 114 begin, whereupon the independent rotation of the second cam 102 drives or causes the one or more moveable contacts 116 to move towards the one or more fixed contacts 118 (make operation).

[0075] Rotation of the cam 102 towards the toggle point is caused by a user rotation of the knob 104 (in other words, user input is required to compress the biasing members / springs 112). As such, the one or more biasing members 112 are configured to be compressed during rotation of second cam 102 towards the toggle point, with a maximum compression at the toggle point. In operation, the transverse cam portion is configured to compress the one or more biasing members during the manual portion of the operation (i.e. during user rotation of the cam 102 through the initial portion of the operating angle, between FIGS. 1A and IB. A maximum displacement of the cam follower 110, and thus maximum compression of the biasing members, occurs when the protrusions 110a of cam follower 110 align with and oppose the protrusions 120 of the transverse cam portion of second cam 102; in other words, the tips of protrusions 110a, 120 make contact with one another (and axis 150 and direction 140 are parallel to one another, in particular coincident with one another). In this example the maximum compression of the one or more biasing members 112 occurs when cam 102 is at the toggle point (see FIG. IB). The compression of the biasing member(s) provides the independent rotation of the second cam 102 after the toggle point.

[0076] At the toggle point, the second cam 102 is in an unstable position, and able to rotate in either direction around the first axis 130. However, because rotation to the toggle point is user controlled, the user's continued input up to the toggle point can determine the subsequent, independent, direction of rotation of the second cam 102 in the second direction 128 (from off to on). In particular, after the toggle point is reached, the force exerted by the (now fully compressed) one or more biasing members 112 acts on the transverse cam portion of cam 102, causing independent rotation of cam 102 in a same direction 128 as the user was (indirectly) manually rotating the second cam. The one or more biasing members 112 begin to decompress when acting on the second cam 102, applying a continued force to cause the continued independent rotation of the cam 102.

[0077] FIG. 1C displays the switch 100 in the subsequent "on", or make, position, at which the second cam is in the stable stop position provided by detent 122b of FIG. 3A. In this example the second cam 102 has rotated a further 30 degrees from the position of FIG. IB, which rotation is driven by the force applied by the one or more biasing members. In particular, after the toggle point the biasing member(s) 112 are configured to act on the transverse cam portion to independently drive or rotate the second cam 102 about the first axis 130 without input or control by a user.

[0078] Rotation of the second cam 102 occurs until the protrusion 110a of the cam follower 110 aligns with and is received by detent 122b. With reference to FIG. 3A, the second cam has now rotated a total of 90 degrees and ends the rotation in a stable position, with the protrusion 110a of the cam follower 110 being received by detent 122b (i.e. the detent the other side of the protrusion 120 from the detent 122a which receives the cam follower 110 in the position of FIG. 1A). At this point, the second cam 102 is in a stable position, and the make (or switch on) operation is complete. In this stable position of FIG. 1C, it will be understood that a force may still be exerted by the one or more biasing members 112. In other words, the biasing members may still be partially compressed by the shape of the transverse cam portion. This partial compression may assist to reduce or minimise chances of the second cam 102 rotating from the stable position. In other examples, the biasing members may be fully uncompressed and no force may be exerted on the second cam 102 in the stable on / off position.

[0079] As can be seen in FIG. 1C, in the make position the one or more movable contacts 116 are brought into electrical contact with the one or more fixed contacts 118, and thus the switch 100 is closed and current can flow through the switch 100.

[0080] The synchronicity of rotation between the second cam 102 and the knob 104 or knob cam 106 described above means that, during the independent rotation of the second cam, independent rotation of the first / knob cam also occurs, leading to a snapping effect of the user engagement portion that allows a user to understand that a make / break operation is occurring. If the user does not rotate the second cam 102 sufficiently far, i.e. the toggle point is not properly reached, the knob 104 and / or knob cam 106 can rotate back in the opposite direction (towards the previous stable position) and the user will understand that the switching operation has not been successful. In other words, the rotation of the knob cam 106 and / or knob 104 between the positions of FIG. IB and FIG. 1C is driven by the independent rotation of the second cam 102.

[0081] In this way, the second cam 102 has been rotated from the off position of FIG. 1A to the toggle position of FIG. IB by manual operation of the user (rotation through the initial portion of the operating angle), and from the position of FIG. IB to the on position of FIG. 1C by independent rotation of cam 102 caused by forces exerted by the one or more biasing members 112 (rotation through the remainder of the operating angle is independent of user engagement or actuation). In this way, a semi-independent making operation is provided.

[0082] In an opposite operation, the second cam 102 is rotated in the first direction 126, i.e. from the on position of FIG. 1C towards the off position of FIG. 1A. With reference to FIG. 3A, the rotation of the second cam 102 from the stable "on" position at detent 122b to the unstable toggle position is equal to a rotation of the first rotation angle, a. The first rotation angle shown in the particular example of FIG. 3A, for illustrative purposes, is 30 degrees, but the angle may be adjusted depending on the particular application in which the second cam 102 is being implemented.

[0083] At the toggle point, the one or more movable contacts 116 are contacting the one or more fixed contacts 118, and thus the switch 100 is closed with current flowing through the switch 100. In other words, and similarly to the operation described above, the axial cam portion and bridge portion are configured such that the breaking operation does not begin until after the toggle point is reached during rotation in the first direction 126. After the toggle point of the second cam 102 is reached when rotating from the on position towards the off position during a break operation, the axial displacement of bridge 114 causes the one or more moveable contacts 116 to move away from the one or more fixed contacts 118, thus breaking the electrical contact between the contacts and opening the current conduction path (break operation). The speed of separation, driven by the independent rotation of the second cam 102, assists in providing rapid making / breaking of the circuit, reducing the risk of arcing between the fixed and moveable conductors during the operation. In this way, the speed of breaking is user independent and so can be better controlled. By allowing rapid breaking, independent of user input, arcing may be reduced. Rotation of the cam 102 in the first direction 126 towards the toggle point is caused by a user rotation of the knob 104 (in other words, user input is required to compress the biasing members / springs 112). As such, the one or more biasing members 112 are configured to be compressed during rotation of second cam 102 towards the toggle point, with a maximum compression at the toggle point. In this example the maximum compression of the one or more biasing members 112 occurs when cam 102 is at the toggle point (as in FIG. IB).

[0084] After the toggle point is reached, the force exerted by the (now fully compressed) one or more biasing members 112 acts on the transverse cam portion of cam 102, causing independent rotation of cam 102 in a same direction 128 as the user was (indirectly) manually rotating the second cam. The one or more biasing members 112 begin to decompress when acting on the second cam 102, applying a continued force to cause the continued independent rotation of the cam 102. The compression of the biasing member(s) thus provides the independent rotation of the second cam 102 in the first direction 126 after the toggle point. The second cam 102 rotates until the "off" or break position is reached, in which the second cam is in the stable stop position provided by detent 122a of FIG. 3A. In this example the second cam 102 has rotated a further 60 degrees from the toggle point, which rotation is driven by the force applied by the one or more biasing members. In particular, after the toggle point the biasing member(s) 112 are configured to act on the transverse cam portion to independently drive or rotate the second cam 102 about the first axis 130 without input or control by a user. This provides a rapid and reliable breaking operation.

[0085] Rotation of the second cam 102 occurs until the protrusion 110a of the cam follower 110 aligns with and is received by detent 122a in the off position. With reference to FIGS. 2, 3, the second cam has now rotated a total of 90 degrees and ends the rotation in a stable position, with the protrusion 110a of the cam follower 110 being received by detent 122a (i.e. the detent the other side of the protrusion 120 from the detent 122b which receives the cam follower 110 in the position of FIG. 1C). At this point, the second cam 102 is in a stable position, as shown in FIG. 1A, and the break operation is complete. In this stable position, it will be understood that a force may still be exerted by the one or more biasing members 112. In other words, the biasing members may still be partially compressed by the shape of the transverse cam portion. This partial compression may assist to reduce or minimise chances of the second cam 102 rotating from the stable position. In other examples, the biasing members may be fully uncompressed and no force may be exerted on the second cam 102 in the stable on / off position. FIG 4 displays a flowchart illustrating an example method 400 for operating switch 100 to open and close a current conduction path. This flowchart illustrates an overview of the methods of operating a switch, such as switch 100 described previously, to open and close a current conduction path.

[0086] In step 4.1, a user rotates the cam 102 around a first axis from a first stop position to a toggle point. The rotation may be by indirect engagement of the cam 102 by the user. The operating angle may be between 70 and 110 degrees, between 80 and 100 degrees, and optionally may be 90 degrees. The first axis is the axis of rotation 130 as described above in relation to FIG. 1A.

[0087] In step 4.2, in response to the rotation of the cam 102, a force is exerted on the transverse cam portion of the cam by the one or more biasing members 112. The one or more biasing members 112 may comprise one or more springs, however any other biasing member may be used in addition to or in place of the spring(s).

[0088] In step 4.3, the second cam is rotated about the first axis by the one or more biasing members. The cam is rotated from the toggle position to a second stop position. This is a user independent portion of the make / break operation.

[0089] In step 4.4, the axial cam portion is caused, by the rotation of the second cam, to open or close the current conduction path through the switch. As described in relation to FIG. 1, the switch may optionally include a bridge comprising one or more movable contacts that are axially displaced to make / break electrical contact with one or more fixed contacts and thus open and close the current conduction path through the switch. The bridge may optionally be displaced or moved by a bridge cam disposed between the bridge and the second cam.

[0090] It is noted herein that while the above describes various examples of the switch, 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. List of reference numerals

[0091] 100 switch

[0092] 102 second cam, or cam

[0093] 104 knob

[0094] 106 first cam or knob cam

[0095] 108 bridge cam

[0096] 110 cam follower

[0097] 110a protrusion of cam follower

[0098] 112 biasing member

[0099] 114 bridge

[0100] 116 moveable contacts

[0101] 118 fixed contacts

[0102] 120 protrusion of cam

[0103] 122a detent, off position

[0104] 122b detent, on position

[0105] 124a second edge of protrusion, curved profile

[0106] 124b first edge of protrusion, linear profile

[0107] 126 first direction of rotation around first axis of rotation 128 second direction of rotation around first axis of rotation 130 first axis of rotation

[0108] 140 direction along which protrusion extends

[0109] 150 linear axis along which the cam follower moves

[0110] 150a direction of compression of biasing members

[0111] 150b direction of biasing force from biasing members

[0112] 160a plane of symmetry

[0113] 160b plane of symmetry

[0114] a first angle of rotation

[0115] b second angle of rotation

[0116] c internal angle of detent

[0117] Q total angle of rotation

[0118] R Radius of curve or fillet

Claims

- 22 - Claims1. A switch (100) comprising:a cam (102) rotatable around a first axis (130), the cam rotatable in a first direction (126) between an on and an off position and in a second direction (128) between the off and the on position, wherein:the cam (102) comprises an axial cam portion and a transverse cam portion, the transverse cam portion comprising a protrusion (120) extending along a direction (140) perpendicular to the first axis and two detents (122a, 122b) arranged asymmetrically either side of the protrusion (120), wherein the two detents (122a, 122b) are arranged at an angle, e, with respect to each other; andone or more biasing members (112) configured to exert a force on the transverse cam portion;wherein the axial cam portion is configured:upon rotation of the cam in the first direction (126), to cause opening of a current conduction path through the switch (100); andupon rotation of the cam in the second direction (128), to cause closing of a current conduction path through the switch (100).

2. The switch (100) of claim 1, further comprising a cam follower (110) coupled to the one or more biasing members (112), wherein a toggle point of the switch occurs when the protrusion (120) of the transverse cam portion aligns with an opposing protrusion (110a) of the cam follower, optionally wherein the one or more biasing members (112) comprise one or more springs.

3. The switch (100) of claim 2, wherein rotation of the cam (102) towards the toggle point is caused by a user rotation of the cam (102), and wherein said user rotation of the cam (102) causes the transverse cam portion to compress the one or more biasing members (112), wherein maximum compression of the one or more biasing members occurs at the toggle point.

4. The switch (100) of claim 2 or claim 3, wherein, after the toggle point, the one or more biasing members (112) are configured to act on the transverse cam portion to cause independent rotation of the cam (102), wherein the independent rotation of the cam occurs until the protrusion (110a) of the cam follower (110) aligns with and is received by one of the two detents (122a, 122b) of the transverse cam portion.

5. The switch (100) of any of claims 2 to 4, wherein:when the cam (102) is rotated in the first direction (126), the toggle point is reached after a first angle of rotation, a; andwhen the cam (102) is rotated in the second direction (128), the toggle point is reached after a second angle of rotation, b, wherein the first angle of rotation is less than the second angle of rotation.

6. The switch (100) of clam 5, wherein :the first angle of rotation, a, is between 20 and 40 degrees, optionally wherein the first angle of rotation is between 25 and 35 degrees, optionally wherein the first angle of rotation 30 is degrees; andthe second angle of rotation, b, is between 50 and 70 degrees, optionally wherein the second angle of rotation is between 55 and 65 degrees, optionally wherein the second angle of rotation 60 is degrees.

7. The switch (100) of any preceding claim, wherein the angle, Q, between the two detents is between 70 degrees and 110 degrees, optionally wherein the angle is between 80 and 100 degrees, optionally wherein the angle is 90 degrees.

8. The switch (100) of any preceding claim, wherein the protrusion (120) of the transverse cam portion comprises a first edge (124b) with a linear profile and a second edge (124a) with a curved profile.

9. The switch (100) of claim 8, wherein the detent (122b) proximate to the first edge (124b) of the protrusion (120) has an internal angle of between 120 and 140 degrees, optionally an internal angle of between 125 and 135 degrees, optionally an internal angle of 130 degrees.

10. The switch (100) of any preceding claim, wherein the cam (102) has a second protrusion arranged opposite the first protrusion (120), and a further two detents arranged asymmetrically either side of the second protrusion, wherein the further two detents are arranged at the angle, e, with respect to each other.

11. The switch (100) of any preceding claim, further comprising a bridge cam (108) contacting the axial cam portion of the cam (102),wherein rotation of the axial cam portion causes rotation of the bridge cam (108) around the first axis after a first rotational offset,and wherein the rotation of the bridge cam (108) is configured to open and close the current conduction path through the switch (100).

12. The switch (100) of claim 11, further comprising:one or more fixed contacts (118); anda bridge (114) that is axially displaceable along the first axis (130) in response to rotation of the bridge cam (108), wherein the bridge (114) comprises one or more moveable contacts (116),wherein the bridge (114) is configured to bring the one or more moveable contacts (116) into and out of contact with the one or more fixed contacts (118) of the switch (100) to close and open the current conduction path, respectively.

13. The switch (100) of any preceding claim, further comprising a knob (104) configured for engagement by a user, wherein rotation of the knob (104) around the first axis (130) by a user causes rotation of the cam (102) around the first axis (130).

14. A system comprising:the switch (100) of any preceding claim; andan electrical circuit configured to be electrically coupled to one or more fixed contacts of the switch.

15. A method (400) for operating a switch (100) of any of claims 1 to 13 to open and close a current conduction path, the method comprising:rotating (4.1), by a user, the cam (102) about the first axis (130) from a first stop position to a toggle point;exerting (4.2) a force on the transverse cam portion of the cam (102) by the one or more biasing members (112);rotating (4.3), by the one or more biasing members (112), the cam (102) about the first axis from the toggle position to a second stop position; and causing (4.4), by the rotation of the cam (102), the axial cam portion to open or close the current conduction path through the switch (100).

Images