GB2170955A - Magnetically operable switch capsule - Google Patents

Abstract

A switch capsule has two outer flat sheets (1,2) between which is mounted a magnetic material disc (6) supported by a resilient diaphragm (3) which urges the disc when at rest against one sheet. When a coil (not shown) is energised the disc is attracted so as to move towards the other sheet. In one form the sheets which may be circular or rectangular and the diaphragm are of electrically conductive material, the sheets having extensions to provide switch terminals. In another form a contact set controlled by the disc is wholly inside the capsule. The coil may be mounted on a horseshoe shaped magnetic circuit. The coil can be a flat insulating strip carrying conductive tracks in which case it has substantial self- capacitance which reduces back e.m.f. generated when the coil is de-energised. <IMAGE>

Description

SPECIFICATION Relay The present invention relates to electrical switch capsules which are magnetically operable, and to relays using such capsules.

According to the invention, there is provided a magnetically-operable switch capsule, which includes first and second substantially parallel sheets forming closures for the capsule, and a flat member of magnetic material mounted beneath the plates and carried by a resilient diaphragm, wherein in the rest condition the flat member is urged towards the inner face of the first of said sheets by the diaphragm, wherein when set to its operated condition in response to the application of a magnetic force the flat member is moved into engagement with the inner face of the second of said sheets, and wherein when the magnetic force is removed the flat member is reset to its rest condition by the diaphragm, the movement of the flat member controlling the capsule's electrical contacts.

Embodiments of the invention will now be described with reference to the accompanying drawings, in which Figure 1 is a cross-section of a capsule embodying the invention.

Figure 2 is a view from above the capsule of Fig. 1, with its top plate removed.

Figure 3 is a view similar to Fig. 2 of a capsule embodying the invention which is rectangular.

Figure 4 shows in section an alternative form of capsule which embodies the invention, with an electro-magnetic drive or motor unit.

Figure 5 shows schematically another relay embodying the invention, with a capsule of the Fig. 1 type shown in section.

Figure 6 is a top plan view of the relay of Fig. 5.

Figure 7 explains schematically the magnetic circuit of the relay of Fig. 5.

The first type of capsule to be described herein, see Figs. 1 and 2, is intended for use in a relay for switching currents of up to 25 Amps, especially for automotive applications.

The capsule includes as enclosures two flat metallic but non-magnetic sheets 1 and 2, and a third non-magnetic metallic sheet 3. This sheet 3 is resilient and is made of electrically conductive material, such as copper. To provide its resilience it is corrugated, e.g. with circular corrugations (not shown). Alternatively it may have straight corrugations as indicated at 4, with corners removed as indicated at 5.

Secured to the upper surface of the sheet 3, which is in effect a cruciform diaphragm in the device shown in Figs. 1 and 2, there is a flat disc 6 of ferro-magnetic material. Thus this disc is trapped between the sheets 1 and 3, but is free to move downwards against the resilience of the diaphragm formed by the sheet 3 when subjected to a magnetic force.

The capsule is sealed by a cylindrical member 7 which is of an electrically non-conductive and also non-magnetic material. The sheets 1 and 2 have extensions as shown to the right, one of which only appears in Fig. 2.

The underside of the sheet 3 and the upper face of the sheet 2 can be plated with electrical contact material if this is desired.

In use the capsule of Figs. 1 and 2 is mounted to a source of magnetic force, e.g.

such as shown in Fig. 4 or Fig. 5 below.

When the source is de-energised the capsule is in the condition shown in Fig. 1, in which it is held by the corrugated diaphragm 3. On energisation of the magnetic source the disc 6 is attracted downwards until the lower face of the sheet 3 engages the inner face of the sheet 2. In this condition the capsule is in its operated state in which a circuit exists between the switch pins formed by the extensions on the two plates 1, 2. When the magnetic source is de-energised, the influence of the diaphragm 3 manifests itself to cause the disc 6 to be restored to its position shown in Fig. 1 in which the circuit is broken. As already indicated, this capsule can handle relatively high currents, such as 25 Amps.

Although the capsule of Figs. 1 and 2 is circular, it will be appreciated that other shapes are possible, and Fig. 3 shows a plan view of a rectangular capsule with its upper sheet removed. Here we see a rectangular flat member 10 of ferro-magnetic material held in place by a sheet of thin resilient metal, e.g.

copper. This sheet acts as a diaphragm, and has two end portions 11, 12 each of which is corrugated in the interests of resilience. The flat member 10 is, as shown, flanked by slots 13, 14. Each of the closure sheets or plates has an extension from one edge to act as a switch pin, and one such extension is shown at 15. The frame 16, like the circular frame of Figs. 1 and 2 is of electrically insulating and non-magnetic material.

This capsule operates in the same way as does the capsule of Figs. 1 and 2.

Fig. 4 shows a capsule which is somewhat different from the capsules described above, fitted to a drive or motor unit. This capsule has one of its contacts 20 on the inner face of the lower closure sheet 21, and the other contact 22 mounted on the magnetic material disc 23.

The drive unit includes a horseshoe shaped or U-shaped member 24 of iron rod, 5mm in diameter, one end of which is aligned with an edge region of the disc 23. The other end has a pole-piece 25 rivetted to it and aligned with most of the diameter of the disc 23. This rod 23 carries an energising winding 26.

The device shown in Figs. 5 and 6 uses a capsule 30 which is similar to the capsule shown in Figs. 1 and 2, but it can also use a capsule such as that used in the relay of Fig.

4. The ends of the closure plates thus form the switch pins, e.g. as shown at 30a, Fig. 6.

The motor unit includes a rod-like portion 31 which carries a plastics bobbin 32 on which the coil 33 is wound. This portion 31 has a disc-like pole-piece 34 on its upper end, and its lower end is connected via yoke 35 to a ring 36 which provides the other pole-piece.

Both of these pole-pieces are substantially parallel to the disc 37 of the capsule 30.

When the coil is energised, flux flows along the paths indicated schematically in Fig. 7 to attract the disc.

In this device the coil can be wound from wire or from an insulated conductor foil, e.g.

copper or aluminium on Mylar (Registered Trade Mark). In this case the foil width is the same as the inside of the bobbin, and the foil thickness is in the region of a few microns.

Such a winding has a high self-capacitance, which reduces the relatively large back e.m.f.

otherwise generated on de-energisation.

The portion 35 can be, if desired, integral with a cylindrical can which thus virtually seals the coil.

Claims (12)

1. A magnetically-operable switch capsule, which includes first and second substantially parallel sheets forming closures for the capsule, and a flat member of magnetic material mounted beneath the plates and carried by a resilient diaphragm, wherein in the rest condition the flat member is urged towards the inner face of the first of said sheets by the diaphragm, wherein when set to its operated condition in response to the application of a magnetic force the flat member is moved into engagement with the inner face of the second of said sheets, and wherein when the magnetic force is removed the flat member is reset to its rest condition by the diaphragm, the movement of the flat member controlling the capsule's electrical contacts.

2. A switch capsule as claimed in claim 1, wherein the capsule and the flat member are circular, and the diaphragm is circular or of cruciform plan and is corrugated in the regions thereof outside the periphery of the flat member.

3. A switch capsule as claimed in claim 1, wherein the capsule and the flat member are rectangular, and the diaphragm consists of two corrugated regions at opposed edges of the flat member.

4. A switch capsule a claimed in claim 1, 2 or 3, wherein the flat sheets and the diaphragm are of non-magnetic but electrically conductive material, and wherein the flat sheets provide the contacts of the switch capsule.

5. A switch capsule as claimed in claim 1, 2 or 3, wherein the flat member carries one of the switch contacts while the other contact is on one of the flat sheets so as to be inside the capsule.

6. A relay which includes a capsule as claimed in any one of claims 1 to 5, and a horseshoe type magnetic circuit which carries an energising coil, the capsule being adjacent the two ends of the magnetic circuit.

7. A relay as claimed in claim 6, and wherein one end of the magnetic circuit is adjacent the outer face of the second plate and in alignment with an edge of the flat member, the other end of the circuit being a flat strip aligned adjacent to the outer face of the second plate and with a major portion of the axis of the flat member.

8. A relay as claimed in claim 6, wherein one leg of the horseshoe carries a disc-like pole-piece and the other end of the horseshoe is magnetic coupled to a ring-like pole piece concentric with the disc-like pole-piece, and wherein the pole-pieces are adjacent to the outer face of the second sheet and aligned with the major portion at least of the area of the flat member.

9. A relay as claimed in claim 6, 7 or 8, and wherein the coil is wound with a flat strip of insulating material which carries conductive tracks.

10. A magnetically-operable switch capsule, substantially as described with reference to Figs. 1 and 2, Fig. 3 or Fig. 4 of the accompanying drawings.

11. An electro-magnetic relay substantially as described with reference to Fig. 4, or Figs.

5, 6 and 7 of the accompanying drawings.

CLAIMS New claims or amendments to claims filed on 7th May 1985.

12. A magnetically-operable switch capsule, which includes first and second substantially parallel sheets forming closures for the capsule, said sheets being of a non-magnetic material, and a flat member of magnetic material mounted between the plates and carried by a resilient diaphragm of a metallic but nonmagnetic material, wherein in the rest condition of the capsule the flat member is urged towards the inner face of the first of said sheets by the diaphragm, wherein when the capsule is set to its operated condition in response to the application of a magnetic force the flat member is moved towards the inner face of the second of said two sheets, which movement is effected against the resilience of the diaphragm, wherein when the magnetic force is removed the flat member is restored to its rest position by the resilience of the diaphragm, and wherein the movement of the flat member control the engaged or non-engaged condition of the capsule's electrical contacts.