GB2419236A

GB2419236A - An indicator for distinguishing between states of an electromechanical device

Info

Publication number: GB2419236A
Application number: GB0515539A
Authority: GB
Inventors: Patrick Ward; Peter Hicks
Original assignee: Tripco Ltd
Current assignee: Tripco Ltd
Priority date: 2004-10-08
Filing date: 2005-07-28
Publication date: 2006-04-19
Also published as: GB0515539D0; IES20040685A2

Abstract

An indicator for distinguishing between first and second positions of a movable mechanical component of an electromechanical device is disclosed. The indicator comprises a flag 30 coupled to or forming part of the mechanical component so as to move with the component, and at least one optical component 20. The flag 30 is substantially more visible via the optical component 20 when the mechanical component is in its first position than when it is in its second position. The flag 30 is visible via the optical component 20 by reflection at least at one face 26 of the optical component 20.

Description

24 1 9236 An indicator for distinguishing between states of an

electromechanical device This invention relates to an indicator for distinguishing between first and second positions of a movable mechanical component of an electromechanical device.

Circuit breakers, contactors and residual current devices comprise a switching means to open and close at least one set of contacts so as to switch a load current on or off, with the contacts being moved from an open position to a closed position or vice versa as necessary to achieve the desired function.

It is generally considered advantageous, and in some cases a requirement, that such products be provided with means to clearly indicate the closed and open states of the contacts, in particular if the contacts weld together due to excessive heating and thereby prevent correct opening of the contacts the indicator should indicate that the contacts are in the closed position.

Over many years, various techniques have been used for the indicator, with varying degrees of success. One common method is to use a transparent or semitransparent window through which a flag appears when the contacts are in the closed state and which disappears when the contacts are in the open state.

The flag either forms parts of, or is directly or indirectly coupled to, the moving contact(s) so that it can be used as an indicator of the contact states. The flag, or at least that portion of the flag which is intended to be viewed, usually has a distinctive colour, such as red, so as to enhance its contrast and visibility within the window and indicate danger when the contacts are in the closed position.

The effectiveness of this simple arrangement can be seriously undermined if, for example, the flag remains partially visible when the contacts move to the open state, or if the flag is not clearly visible when the contacts are in the closed state.

This lack of clarity regarding the two states can leave users unclear as to the true position of the contacts and thereby constitute a risk of misinforming or misleading users as to the actual position of the contacts.

Figures la and lb, and Figures 2a and 2b, are examples of

typical prior art techniques using a flag window.

Referring first to Figures la and lb, a flag 10 is mounted on the same carrier as, or is mechanically coupled to, the movable contact (not shown) of a circuit breaker such that the flag pivots between first and second positions in synchronism with the movement of the movable contact into and out of contact with a fixed contact (also not shown). In Figure la, where the contacts are closed, the viewing surface 12 of the flag 10, typically being coloured red, is located close to and within the aperture of a window 14 in the exterior wall 16 of the circuit breaker housing to so that the flag is readily visible to external viewers through the window. In figure lb, where the contacts are open, the flag 10 has pivoted to a second position away from the window 14 so that the surface 12 is not visible to external viewers, or is at least substantially less visible.

The arrangement of Figure 1 can be effective in providing clear indication of the two states of the circuit breaker.

However, in cases where there are serious space constraints, it may prove impossible to pivot the flag over a sufficiently wide arc to position it sufficiently close to and sufficiently away from the window aperture in the closed and open states respectively of the contacts, thereby resulting in lack of certainty as to the true position of the contacts.

In the arrangement of Figures 2a and 2b, the viewing surface 12 of the flag 10 moves linearly towards and away from the window 14 in a direction normal thereto. When the contacts are in the closed state, the surface 12 is positioned close to the window 14, thereby making it clearly visible. When the contacts are in the open state, the surface 12 is positioned away from the window, reducing its visibility.

One problem with the arrangement of Figure 2 is that the surface 12 needs to be able to move over a considerable distance relative to the window 14 to ensure that it ceases to be visible when the contacts are in the open state and be clearly visible when the contacts are in the closed state.

However, the flag movement may be constrained due to space restrictions or to the limited movement of the moving contacts if the flag is directly or indirectly coupled to the moving contacts, resulting in the flag being partially visible when the contacts are open or not being clearly visible when the contacts are closed.

Another problem related to Figures 1 and 2 is that the visibility of the flag is directly related to the area of the window 12, the area of the viewing surface 12 of the flag, and the portion of the viewing surface 12 that is positioned over the window aperture. All of these need to be reasonably large for effective visibility of the flag. The problems of Figures 1 and 2 can be compounded due to factors associated with the window itself, for example in relation to shape, size, depth, transparency, etc. In some cases, for example where flag size or window size is severely constrained, manufacturers have resorted to designing windows as concave/convex lenses to achieve a magnifying effect, but the effectiveness of these techniques usually leaves a lot to be desired.

It is therefore an object of this invention to demonstrate an improved indicator in which these disadvantages are avoided or mitigated.

Accordingly, the present invention provides an indicator for distinguishing between first and second positions of a movable mechanical component of an electromechanical device, the indicator comprising a flag coupled to or forming part of the mechanical component so as to move with the component, and at least one optical component, the flag being substantially more visible via the optical component when the mechanical component is in its first position than when it is in its second position, wherein the flag is visible via the optical component by reflection at least at one face of the optical component.

"FlagH means any member which can be selectively made visible via the optical component by movement relative to the optical component, and does not imply any particular shape or colour of the member.

An advantage of the invention is that in the arrangements of Figures l and 2, the viewer sees the actual flag through the window whereas in the invention the viewer sees a reflection of the flag. Using a reflection of the flag provides considerably more options with regard to the indicator design.

Preferably, the optical component comprises a solid body and the flag is visible through the optical component by internal reflection at the said at least one face.

More preferably, the optical component has a polygonal cross- section, wherein the flag is brought adjacent to a first side of the polygon in the first position of the mechanical component, and wherein the flag is visible through a second side of the polygon after internal reflection at a third side of the polygon.

Most preferably, the polygon is a right-angled isosceles triangle with internal reflection occurring at the hypotenuse.

In one embodiment the electromechanical device is contained in a housing and the optical component is set in an opening in the housing.

In another embodiment the electromechanical device has fixed and movable contacts contained within a housing and a reset button outside the housing, the optical component being incorporated into the reset button and the flag being movable with the movable contact such that when the movable contact is closed against the fixed contact the flag is visible through the optical component.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures l and 2, previously described, are schematic diagrams of prior art indicators used in circuit breakers and other electromechanical devices.

Figures 3(a) to 3(c) are schematic diagrams illustrating the principle of operation of the embodiments of the invention.

Figures 4(a) and 4(b) are schematic diagrams illustrating a first embodiment of the invention.

Figure 5 is a schematic diagram illustrating a second embodiment of the invention.

Figure 6 is a schematic diagram illustrating a third embodiment of the invention.

In the various figures of the drawings the same or equivalent parts have been given the same reference numerals.

The embodiments use the internal reflection of light in a transparent optical component whose cross-section is a right- angled isosceles triangle. Referring to Figure 3a, the optical component 20 has two equal short faces 22 and 24 at right angles to one another and a sloped face or hypotenuse 26 at 45 to each of the faces 22, 24. Light entering the component 20 normal to the face 22, indicated by the dashed line, will leave the component normal to the face 24 after total internal reflection at the hypotenuse 26. If desired, the hypotenuse 26 may be silvered.

Thus a coloured flag 30 located close to the face 22, Figure 3b, will be visible through the face 24, whereas when the flag is removed from adjacent the face 22, Figure 3c, it will no longer be visible at the face 24. It will be seen that the flag 30 is brought close to and removed from the face 22 by sideways movement substantially parallel to the face 22, as indicated by the double-headed arrow in Figure 3c. This has the advantage that only a short movement, equal to the length of the face 22, is required to completely remove the flag from the face 22 and, because it is located to the side of the face 22, render it substantially invisible to an external viewer.

The visibility of the flag in the viewing face 24 of the optical component 20 will be determined by a number of factors, including the proximity and location of the flag in relation to the light input face 22, the colour and brightness of the flag, the material and transparency of the optical component, the smoothness of the surfaces of the optical component, and the accuracy of the 45 angle of the sloped face 26, etc. As indicated above, the key difference between the arrangement of Figure 3 and those of Figures 1 and 2 is that in the latter the viewer sees the actual flag through the window whereas in Figure 3 the viewer sees a reflection of the flag. Using reflected light for the indicator frees up the options with regard to the indicator design, as demonstrated in the following embodiments.

Figures 4a and 4b show a first embodiment of flag indicator according to the invention, in this case fitted to a circuit breaker comprising fixed and movable contacts 32, 34 respectively contained within a housing of which one external wall is seen at 16 (the other components of the circuit breaker are not shown, but they may be of conventional construction and operation). The optical component 20 is fitted into an opening in the external wall 16 with the face 24 parallel to the wall 16 and the face 22 inside the housing and normal to the wall 16. The flag 30 is mounted on a contact carrier 36 for the movable contact 34, so that when the contacts are open, Figure 4a, the flag 30 is positioned to the side of the face 22, and is thus not visible through the face 24, while when the contacts are closed, Figure 4b, the major part of the area of the face 22 is covered by the flag resulting in good visibility of the flag through the viewing face 24. As noted above, a relatively small sideways displacement of the flag 30 results in a very significant change in the visibility of the flag 30 through the viewing face 24. In addition, the size of the flag 30 and optical component 20 can be substantially reduced in comparison to the arrangements of Figures 1 and 2.

The embodiment of Figure 5 shows how the viewing area or visibility of the flag 30 can be increased by the use of two back-to-back components 20. In this arrangement, the light input faces 22 of the components 20 oppose one another across a narrow gap, and the flag 30 (in this case having both opposite surfaces coloured) is inserted in the gap between the faces 22 in the closed condition of the contacts 32, 34. Thus a reflection of the flag will be seen in the viewing faces 24 of both components 20. The two components could be combined or manufactured as a single part provided the gap between the faces 22 is present.

It will be understood that although the embodiments of Figures 4 and 5 show the flag 30 directly mounted on the contact carrier 36, the flag could be alternatively be directly or indirectly mechanically coupled to the contact carrier, e.g. via a lever or gearing arrangement, so as to move simultaneously with the latter but not necessarily in the same direction or by the same amount. The particular arrangement chosen will depend upon circumstances.

Figure 6 shows a further embodiment of circuit breaker incorporating the invention. In this embodiment, two optical components 20 are incorporated into a reset button 40, with a space between the face 22 of each optical component 20 and the core 42 of the reset button. The reset button is connected through the exterior wall 16 of the breaker housing to a ferromagnetic plunger 44 within the housing, and a coil 46 is wound round the plunger. A biasing spring 48 positioned between the reset button 40 and the wall 16 biases the reset button way from the housing into the position shown in Figure 6. A moving contact carrier 50 supports and electrically connects together two movable contacts 34. The movable contacts 34 are positioned above two fixed contacts 32.

Figure 6 shows the contact breaker with the contacts open, the contact carrier being biased away from the fixed contacts 32 by a spring (not shown).

The moving contact carrier 50 also carries a permanent magnet 52 which is held in position by a retainer. Two arms 54 extend from the moving contact carrier 50 alongside the plunger 44 and through the exterior wall 16 of the housing.

Each arm is provided with a stop 56 so as to limit the upward travel of the moving contact carrier 50 by the stops 56 coming to rest on the outside surface of the wall 16, whilst the free ends of the arms 54 extend to form flags 30 which are positioned above and substantially outside the gaps between each optical component 20 and the reset button core 42 when the contacts are in the open position as shown. Each optical component has its viewing face 24 flush with the reset button surface.

When the reset button 40 is pressed sufficiently towards the moving contact carrier 50, against the bias of the spring 48, the air gap between the ferromagnetic plunger 44 and the permanent magnet 52 will be reduced to such an extent that the moving contact carrier will become magnetically entrained with the plunger. Then, when the reset button 40 is released, the spring 48 will bring the moving contact carrier 50, against its own spring bias, towards the fixed contacts 32 until the contacts 34 coming to rest on the fixed contacts. This completes an electrical circuit between the two fixed contacts 32. The flags 30 extending from the moving contact carrier will at this point be positioned within the respective gaps between each optical component 20 and the reset button core 42 and will therefore become visible within the viewing face 24 of each optical component.

When a current of sufficient magnitude and direction is passed through the coil 46, the magnetic field of the permanent magnet 52 will be weakened to the extent that the permanent magnet can no longer remain entrained to the plunger 44, at which point the moving contact carrier 50 will be released to move back to the contacts-open condition seen in Figure 6. At the same time the reset button 40 will move to its initial position and the flags will move out of the gaps in front of the faces 22 of the optical components and will no longer be visible in the viewing faces 24.

The arrangement of Figure 6 has the advantages of incorporating the optical component into the reset button and obviating the need for separate optical component and reset button, and incorporating the flag into the moving contact carrier and obviating the need for a separate flag. In addition, because the flag forms part of the moving contact carrier, the flag provides a true indication of the open and closed states of the contacts.

The embodiment of Figure 6 can be readily modified or varied without departing from the invention. For example, one of the flags 30 and one of the optical components 20 could be omitted so as to make the arrangement more compact. Alternatively, the two optical components could be replaced by an annular optical component having the cross-section shown. Also, although the arrangement of Figure 6 shows a single pole circuit breaker application, the arrangement could also be configured for a multipole circuit breaker.

The foregoing has described embodiments where the optical component is a right-angled isosceles triangle. However, other polygonal shapes are possible, as are other kinds of optical component such as mirrors. Furthermore, more than one optical component may be used. The particular arrangement chosen will depend on circumstances.

The invention is not limited to the embodiments described herein which may be modified or varied without departing from the scope of the invention.

Claims

Claims: 1. An indicator for distinguishing between first and second

positions of a movable mechanical component of an electromechanical device, the indicator comprising a flag coupled to or forming part of the mechanical component so as to move with the component, and at least one optical component, the flag being substantially more visible via the optical component when the mechanical component is in its first position than when it is in its second position, wherein the flag is visible via the optical component by reflection at least at one face of the optical component.
2. An indicator as claimed in claim 1 wherein said flag comprises a member which can be selectively made visible via the optical component by movement relative to the optical component.
3. An indicator as claimed in claim 1 or 2 wherein the optical component comprises a solid body and the flag is visible through the optical component by internal reflection at the said at least one face.
4. An indicator as claimed in claim 3 wherein the optical component has a polygonal cross-section, wherein the flag is brought adjacent to a first side of the polygon in the first position of the mechanical component, and wherein the flag is visible through a second side of the polygon after internal reflection at a third side of the polygon.
5. An indicator as claimed in claim 4 wherein the polygon is a rightangled isosceles triangle with internal reflection occurring at the hypotenuse.
6. An indicator as claimed in any previous claim in which the electromechanical device is contained in a housing and the optical component is set in an opening in the housing.
7. An indicator as claimed in claims 1 to 5 in which the electrical switching device has fixed and movable contacts contained within a housing and a reset button outside the housing, the optical component being incorporated into the reset button and the flag being movable with the movable contact such that when the movable contact is closed against the fixed contact the flag is visible through the optical component. ,
8. An indicator substantially as hereinbefore described with reference to.

and or as shown in Figures 3(a), 3(b), 3(c), 4(a) and 4(b); Figures 3(a), 3(b), 3(c) and 5; or Figures 3(a), 3(b), 3(c) and 6.

7. An indicator as claimed in claims 1 to 5 in which the electromechanical device has fixed and movable contacts contained within a housing and a reset button outside the housing, the optical component being incorporated into the reset button and the flag being movable with the movable contact such that when the movable contact is closed against the fixed contact the flag is visible through the optical component.

8. An indicator substantially as hereinbefore described with reference to and or as shown in Figures 3(a), 3(b), 3(c), 4(a) and 4(b); Figures 3(a), 3(b), 3(c) and 5; or Figures 3(a), 3(b), 3(c) and 6. lo

Amendments to the claims have been filed as follows: Claims: An indicator for distinguishing between open and closed states of the contacts of an electrical switching device, the indicator comprising a flag coupled to or forming part of a movable contact of the switching device, and at least one optical component, the flag being substantially more visible via the optical component when the switching device is in one state than when it is in the other state, wherein the flag is visible via the optical component by reflection at least at one face of the optical component.

2. An indicator as claimed in claim 1 wherein said flag comprises a member which can be selectively made visible via the optical component by movement relative to the optical ', component. 0, .

3. An indicator as claimed in claim 1 or 2 wherein the, optical component comprises a solid body and the flag is visible through the optical component by internal reflection at the said at least one face.

4. An indicator as claimed in claim 3 wherein the optical component has a polygonal cross-section, wherein the flag is brought adjacent to a first face of the polygon in the first position of the mechanical component, and wherein the flag is visible through a second face of the polygon after internal reflection at a third face of the polygon.

5. An indicator as claimed in claim 4 wherein the polygon is a rightangled isosceles triangle with internal reflection occurring at the hypotenuse. lo

6. An indicator as claimed in any previous claim in which the electrical switching device is contained in a housing and the optical component is set in an opening in the housing.