GB2106322A - Electric tilt switch - Google Patents

Abstract

A tilt switch comprises a fixed contact (12), a movable contact (14) biassed towards the fixed contact (12), actuating means (16), and rolling means (20) positioned on a guide path (19) and movable, by tilting of the switch between a first position in what it holds the movable contact (14) out of engagement with the fixed contact (12) and at least one other position in which it permits the movable contact (14) to engage the fixed contact (12). <IMAGE>

Description

SPECIFICATION Tilt switch The present invention relates to tilt switches and has particular application to a tilt switch for controlling illumination of chest deep freezers when the lid of the chest freezer is opened.

With chest deep freezers, it is a common practice to provide a gravity operating switch which is mounted on the lid of the chest freezer and is used to control the operation of an illuminating lamp, also positioned on the lid. At the present time these switches have employed mercury as the control means but with present day accent on safety, such a switch can be dangerous if broken since mercury is a toxic substance.

The present invention seeks to provide a tilt switch which is, in its particular embodiments, particularly adapted for use in chest freezers which has a simple design and which is devoid of toxic materials which could contaminate the contents of the freezer.

According to the invention, there is provided, a tilt switch comprising a fixed contact, a movable contact biassed towards the fixed contact actuating means on the movable contact and rolling means positioned on a guide path and movable by tilting of the switch from a first position in which it holds the movable contact out of engagement with the fixed contact and at least one other position in which it permits the movable contact to engage the fixed contact.

Preferably the guide path is provided, at the first position of the rolling means with an aperture through which an operating member for the movable contact protrudes and which is pushed downwardly into the aperture by the rolling means in the first position so as to hold the movable contact out of engagement with the fixed contact.

The rolling means may comprise any form of rolling device such as a roller, a ball or a dumb-bell shape device. The guide path may suitably be a flat "U" shaped element along which the rolling means rolls.

The orientation of the switch may be such that the ball or roller is positioned over the aperture when it is desired to extinguish the light and, in a chest freezer, this would be the horizontal position. If the path runs on both sides of the aperture, the rolling means can move in two directions away from the aperture so that the switch can be orientated in one of two ways. If however, the provision of the guide path is of dishshape and the rolling means is a ball, the rolling means may move in any direction and the orientation of the switch becomes immaterial provided that it is set-up so that in the nonoperative position the ball is seated over the aperture.

Suitably the switch may be combined with a lamp housing so that the lamp holder of the lamp which it controls is in fact part of the unit and thus it is only necessary to provide a single attachment for the whole of the illuminating arrangement for the chest freezer. Also if it is desired to orientate the lamp to any side of the switch, this can be readily achieved by placing the switch in the appropriate alignment, so that with the ball and dish arrangement, the switch will still work on tilting of the freezerjid whatever is the orientation of the switch thereon.

The invention will now be described, in greater detail, with reference to the drawings, in which: Figure 1 is a sectional view through one form of tilt switch in accordance with the invention; Figure 2 is a view of a combined lamp and switch unit taken on the line Il-Il of Figure 1.

Referring to the drawings, one form of tilt switch in accordance with the invention is shown which is particularly adapted for attachment to the lid of a deep freeze chest. To this end, the switch comprises a housing 1 which contains the switch elements indicated generally by 2, a holder for a lamp bulb indicated generally at 3 and a socket arrangement for the supply of electricity, generally indicated at 4. Considering the general set up of the arrangement, electricity is fed in through the socket 4 and passes, on the live side, through the switch 2 to the illuminating bulb 6 and returns via a return wire to the socket 4.

As shown in the drawings, the bulb 6 is of a standard miniature edison screw type in which live contact is made to the tip 8 of the bulb base 9 in while return is provided through the screw threads 10 of the bulb base. It will of course be appreciated that other forms of lamp can be used such as miniature bayonet types or full size ES or bayonet types. The switch itself suitably comprises a fixed contact 1 2 and a movable contact 14 positioned vertically one above the other, the moving contact being carried by a springy strip 1 5, for example of phosphor bronze, which biasses the contacts 12, 1 4 into their closed position.The phosphor bronze strip has bent a projecting portion 1 6 adjacent the end carrying the moving contact 14 and this portion 16, when the contacts are engaged, extends upwardly into a control chamber 1 7 through an aperture 18. When the projection 1 6 is fully extended through the aperture 18, the switch contacts 12 and 14 are closed while when the projection 16 is, as shown in Figure 1,pushed downwardly so as not to protrude from the aperture 18 at all, the contacts 12 and 14 are maintained in the open circuit position.

The control chamber 17 has a lower wall 19 which extends in an inclined plane upwardly from the central aperture 1 8 and forms a guide path.

Guided on this guide path is a roller 20, suitably of steel or a sufficiently heavy material. This roller 20 in the horizontal position of the switch shown, rests over the aperture 18 causing disengagement of the contacts 12 and 14. The roller 20 is maintained in its proper orientation by means of the side walls 22 of the chamber 17.

When the switch is tilted either to right or left as seen in the drawings, the roller 20 will roll along the inclined surface 19, for example as shown in chain lines in Figure 1 , so that the projection 1 6 can protrude through the aperture 18, the phosphor bronze strip 1 5 is released, and the contacts 12 and 14 will close under the action of the spring force. Because the inclined surface 19 is on both sides of the aperture 18, the switch will operate by tilting it either to left or right in Figure 1 the left or right orientation of the switch as compared to the light bulb 6 is non-critical.

Attachment of the unit of the freezer lid may be carried out in the usual way by fastening means not shown. For this purpose a spacing means 24 is provided.

In a modification of the above described tilt switch, the aperture 1 8 in the control chamber 17 is surrounded by the inclined surfaces on all sides so as to form a dish like or saucer like structure.

Instead of the roller 20, a ball is provided. In these circumstances the switch will operate if tilted in any direction from its non-operative position and thus total freedom of orientation will result.

It will be appreciated that various modifications may be made to the above described embodiment without departing from the scope of the invention.

For example, the roller 20 may be replaced not only by a ball but any other suitable rolling device, such as a dumb-bell formation. While the direct control of the moving contact by the rolling member is desirable, it is possible for the control, to be actuated through some form of linkage.

It will be seen that the above described embodiments provide a tilt switch which is particularly suited to use on the lids of chest freezers and can have different orientations as well as being of simple design and free of toxic materials.

Claims (10)

1. A tilt switch comprising a fixed contact, a movable contact biased towards the fixed contact actuating means on the movable contact and rolling means positioned on a guide path and movable by tilting of the switch between a first position in which it holds the movable contact out of engagement with the fixed contact and at least one other position in which it permits the movable contact to engage the fixed contact.

2. A switch as claimed in claim 1 , wherein at the said first position of the rolling means the guide path is provided with an aperture through which an operating member for the movable contact protrudes, the operating member being pushed back through the aperture by the rolling means in the said first position to hold the movable contact out of engagement with the fixed contact.

3. A switch as claimed in claim 1 or 2, wherein the rolling means comprises a roller.

4. A switch as claimed in claim 1 or 2, wherein the rolling means comprises a ball.

5. A switch as claimed in claim 1 or 2, whereing the rolling means comprises a dumb-bell shaped element.

6. A switch as claimed in any one of claims 1 to 5, wherein the guide path comprises a "flattened U" shaped element along which the rolling means rolls.

7. A switch as claimed in any one of claims 1 to 6, wherein at least two said other positions are provided, one on either side of the said aperture.

8. A switch as claimed in claim 2 or any one of claims 3 to 6 when appendent directly or indirectly thereto, wherein, the guide path is in the form of a dish, the centre of which is provided with the aperture and the outer parts of which provide said other positions.

9. A switch unit as claimed in any one of claims 1 to 8, wherein the switch is combined with a lamp housing, housing a lamp controlled by the switch.

10. A tilt switch substantially as described herein with reference to the drawings.