GB2232817A

GB2232817A - Switch guard

Info

Publication number: GB2232817A
Application number: GB8913404A
Authority: GB
Inventors: Graham Furness
Original assignee: STC PLC
Current assignee: STC PLC
Priority date: 1989-06-10
Filing date: 1989-06-10
Publication date: 1990-12-19
Also published as: GB8913404D0

Abstract

A guard (4) for a toggle switch operating lever (3) envelopes the lever (3) and prevents inadvertent operation thereof whilst permitting access to the lever for deliberate operation. The guard (4) may be comprised by a resilient metal or plastics element in a generally n-shaped cross-section. Portions (11) and (15) of the element provide a covering envelope whereas the remaining portion serves for mounting purposes. When the lever 3 is moved to the operating position (indicated dotted lines) it is latched e.g. in an aperture in portion (11) following deflection of the portions (11) and (15). <IMAGE>

Description

SWITCH GUARD.

This invention relates to a switch guard and in particular to a guard for a toggle switch which prevents accidental operation of the switch.

According to the present invention there is provided a guard for a toggle switch which in use envelopes an operating lever and operating zone of the switch in such a manner as to prevent inadvertent operation of the lever whilst permitting access for deliberate lever operation.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which Fig. 1 illustrated a side view of a toggle switch mounted to a panel; Fig. 2 illustrates a side view of a toggle switch mounted to a panel and with a guard according to the present invention; Fig. 3 illustrates a side view of the guard on an enlarged scale; Fig. 4 illustrates the shape of a flat element prior to folding to form a guard; Fig. 5 illustrates a view of the guard looking in direction C on Fig. 3; Fig. 6 illustrates a view of the guard looking in direction D on Fig. 3, and Fig. 7 illustrates a side view of part of the toggle switch of Fig. 2 together with the guard and indicates the movement of the guard when the operating lever is actuated.

Certain telecommunications equipments include units which plug into racks provided therefor. These units have a front face which directly comprises part of a front face of the equipment when the units are plugged in to the rack, rather than the front face of the equipment being comprised by the door of a cabinet which houses the plug in units and racks. In a particular application, a power on/off switch is required to be provided at the front face of the unit so that the power can be switched off while the unit is being inserted or removed, in order to prevent damage to components of the unit.

It has been found that, particularly in the case of such plug-in units which are disposed at a relatively low level in the equipment, there is a possibility that a toggle switch, used as a power on/off switch, can be accidentally operated by personnel or equipment passing the unit and the operation of the unit thus curtailed.

Such inadvertent operation can be prevented by employing a switch without any protruding operation parts, such as a switch which requires a key to be inserted to operate it. Such switches are however more expensive than simple toggle-type switches and have the additional disadvantage that a separate key is required to operate them. The invention proposes the provision if a shroud or guard at a toggle switch which prevents inadvertent operation thereof. The guard is basically required to prevent accidental movement of the operating lever. Access to the switch operating lever must, however, be possible in order to actuate the operating lever when such is necessary.

In Fig. 1 there is illustrated a side view of a toggle switch 1 mounted to a panel 2. In the "up" position A of the operating lever 3 the power may be switched off, whereas in the "down" position B of the lever 3 the power may be switched on. Fig. 2 illustrates the same toggle switch but provided with a guard 4. The guard 4 is generally n-shaped in a side view (Fig. 3) and may be formed by bending a flat metal element 5 (Fig. 4) to this shape. Fig. 5 illustrates a view of the guard 4 as seen in the direction of arrow C on Fig. 3 and Fig. 6 illustrates a view of the guard as seen in the direction of arrow D on Fig. 3. The guard has an aperture 6 to accommodate the threaded portion 7 of the toggle switch and a projection 8 for engagement with a slot of the portion 7 for alignment purposes.The toggle switch 1 s secured to panel 2 by clamping the latter between nut 9 and ring 10. When a guard 4 is used it is disposed with its portion containing aperture 6 arranged between the panel 2 and the ring 10 as indicated in Fig.

2. As will be apparent from Fig. 2, in the "up" position (off) of the operating lever the latter is free of the engaging portion 22 of the guard. This portion has a slot 12 in the version illustrated which engages the top of the operating lever when the latter is in the "down" position (on), thus locking it in position.

The material and shape of the guard is preferably selected to provide a degree of resilience and thus positive latching of the operating lever in the slot 12. To move the lever to the power on (down) position with the guard in place it is merely necessary to operate the lever from the side. There is sufficient space between the lever and the guard at the side to insert a finger for this purpose. When such movement of the lever is caused, the guard is deflected upwards and outwards by the end of the lever as indicated by the dotted lines in Fig. 7 until the end of the lever enters the slot 12 where it is then locked (in position B) by the guard returning to its initial configuration. The lever cannot be accidentally knocked out of this locked position by the passage of personnel or equipment.To switch the power off it is necessary to pull the engaging portion 11 of the guard away from the panel and to push the operating lever upwards at the same time.

Whereas the illustrated embodiment has a slot 12 for engagement of the operating lever, alternatively the lower edge of the engaging portion 11 may simply abut the upper edge of the lever on the down position thereof to lock it in place. The lower edge of the engaging portion may be provided with a cut-out to located the lever in this abutment-type version.

As indicated in Fig. 4 the guard tapers over approximately two-thirds of its overall length and is bent about the fold lines 13. The rate and nature of this taper determines the rate and nature of the difference between the upwards and outwards (vertical and horizontal) movement of the guard when the operating lever is in moved downwards and thus the amount of force required to operate the switch. The angle between the portion 14 of the guard clamped to the panel 2 and the cover portion 15 is approximately 900 in the rest & position (switched off). The angle between the cover portion 15 and the engaging portion 11 may be of the order of 750 in the rest position.The angle of the engaging portion is such that it is quite free of the operating lever in the unlocked position but engages the operating lever with either its lower edge or a mating aperture in the locked position. This angle is also related (complementary) to the switch operating angle, that is the angle between the "on" and "off" positions.

Preferably all edges and ends of the guard are rounded as indicated in Fig. 5 to obviate injury to personnel operating or merely passing the equipment. Typically the guard may be manufactured from chrome steel.

As will be appreciated from the drawings and particularly with reference to Fig. 7, the operating lever 3 is covered by the guard 4 from two directions (arrows E and F) and is able to lock the operating lever 3 in one operating position (B) i.e. the guard envelopes the operating switch lever and operating zone such as to prevent inadvertent operation of the lever but such as to permit access for deliberate operation of the lever, and such as to lock the operating lever in one position.

Whereas the guard is disposed to lock the toggle switch with its lever in the "down" position in the drawings, by attaching the guard in the inverted position, the lever can be locked in the "up" position.

The security level provided by the guard is only intended to prevent inadvertent or accidental operation of the switch.

Whilst a specific application of a toggle switch and guard therefor has been described above, there may be other applications where such a guard arrangement is desirable for a toggle switch to prevent inadvertent operation thereof. The invention provides a particularly cheap and effective means for achieving this. The guard will also provide a degree of protection against physical damage to the switch itself, particularly the operating lever. Whereas the guard described above is formed by bending a sheet metal element, alternatively it can be made of a suitable resilient plastics material such as a polyamide, moulded to the n-shaped cross-section.

Claims

CLAIMS.

1. A guard for a toggle switch which in use envelopes an operating lever and operating zone of the switch in such a manner as to prevent inadvertent operation of the lever whilst permitting access for deliberate lever operation.

2. A guard as claimed in claim 1 and including means serving to lock the lever in one position.

3. A guard as claimed in claim 1 and comprising a three-sided element which is generally n-shaped in cross-section, two of said sides providing an envelope for the operating lever and the third side serving for guard mounting purposes.

4. A guard as claim in claim 3 wherein said two sides providing the envelope are contiguous.

5. A guard as claimed in claim 4 wherein said two sides providing the envelope comprise one side substantially perpendicular to the third side and a second side disposed at an acute angle to the one side, the second side being provided with means serving to lock the lever in the one operating position.

6. A guard as claimed in claim 5 wherein said locking means comprises an aperture in the second side.

7. A guard as claimed in claim 5 wherein said locking means comprises a recess at an edge of the second side furthest from the one side.

8. A guard as claimed in any one of claims 3 to 7 and formed from a sheet metal element bent to the n-shaped cross-section.

9. A guard as claimed in any one of claims 3 to 7 and formed for a resilient plastics material moulded to the n-shaped cross-section.

10. A guard as claimed in claim 8 wherein the sheet metal element tapers in width over the said two sides in the direction away from the third side.

11. A guard as claimed in any on of claims 3 to 10 wherein the third side includes an aperture for use in mounting the guard.

12. A guard for a toggle switch substantially as herein described with reference to Figs. 2 to 7 of the accompanying drawings.

Amendments to the claims have been filed as follows

13. A guard in combination with a toggle switch, which guard envelopes an operating lever and operating zone of the switch in such a manner as to prevent inadvertant operation of the lever whilst permitting access for deliberate lever operation, and which guard includes means engaging the lever and serving to lock it in one switching position, and wherein a two-stage operation is required to attain another switching position, namely a stage in which the guard is disengaged from the lever and a stage in which the lever is moved into the other position.