GB2066591A

GB2066591A - Electrical connector shell and method of making same

Info

Publication number: GB2066591A
Application number: GB804109A
Authority: GB
Original assignee: Bunker Ramo Corp
Current assignee: Bunker Ramo Corp
Priority date: 1979-12-13
Filing date: 1980-12-15
Publication date: 1981-07-08
Also published as: GB2066591B

Abstract

A contact or earthing strip (30) is positioned around a connector shell (10) and secured thereon, preferably by means of lugs (20) spun over to retain the strip and force it into a V- shaped groove (28) which may be provided in the base of the second shoulder. In described embodiments, the lugs are aligned with associated keys (14). In a modification the strip (30) may be slid lengthwise around the shell into a dovetail groove (Fig. 6 not shown) with overhanging edges (42 figure 7, not shown) which trap the edges of the strip (30), the strip being fed in through a slot (50 fig. 5, not shown). When fully in the groove the edges (42) of the groove can be spun over onto the edges of the strip. The strip may be located in a thinwalled keyway section of the shell without the need for soldering or welding. <IMAGE>

Description

SPECIFICATION Electrical connector shell and method of making same This invention relates to the manufacture of shells for use in two-part electrical connectors.

There is frequently a requirement with such connectors to maintain good electrical contact between the shell of the plug of the connector and the receptacle receiving the plug, for example to meet radio frequency interference specifications. It has previously been proposed to employ a length of contact strip, known as earthing (or grounding) strip, having resilient protrusions or fingers. The length of strip can be wound around and attached to the plug shell, the attachment being achieved by soldering or welding at a plurality of positions around the shell to ensure that it is mechanically secured to the shell and that good electrical conductivity is maintained between the shell and the strip. This is a tedious and unsatisfactory operation.

It has also been proposed in British Patent 1,340,378 to use a contact strip having a crosssection based on an L-shape, with one leg of the L forming a base portion of tlle contact strip closely conforming to a peripheral surface of the connector shell and the other leg of the L being constituted by a plurality of discrete fingers which are radially directed in an annular recess in the shell and the tips of the fingers engaging against an inwardly facing cylindrical surface of the shell.

This enables the contact strip to be pushed in place radially inwardly around the shell, the resilience of the fingers then latching the strip in place. The contact elements are provided by a second set of fingers extending from the other edge of the base portion at an acture angle to the base portion. This has a number of disadvantages including in particular the need for a relatively thick shell to accommodate the radial leg of the contact strip.

With a view to reducing the overall size of the connector we have proposed including the contact or grounding strip on the keyway portion of the shell. Essentially therefore the strip must be accommodated in the wall thickness of the thinnest part of the shell.

The present invention is defined in the appended claims to which reference should now be made.

The invention will be described in more detail, by way of example, with reference to the drawings, in which: Figure 1 is a side view of the plug shell of a connector embodying the invention; Figure 2 is a detailed sectional view through the shell wall showing the earthing strip wound around the shell but not secured to it; Figure 3 is a view similar to Figure 2 showing the earthing strip secured on the shell; Figure 4 is a view similar to Figure 3 of a modification of the connector shell; Figure 5 is a side view of the plug shell of another connector made in accordance with this invention; Figure 6 is a sectional view through the shell wall showing the contact strip around the shell; Figure 7 is a detail of the sectional view of Figure 6; Figure 8 is a detail showing the feed-in slot for the contact strip;; Figure 9 is a diagrammatic axial view showing the contact strip being fed into its groove in the shell; and Figure 10 indicates the spinning over of the groove edges to secure the strip.

As seen in Figure 1 the connector shell 10 illustrated has a generally cylindrical portion 12 and is indeed as a whole of cylindrical shape. At its free end the shell carries keys 14 which engage in keyways on a corresponding receptacle and at the other end a screw thread 1 6 permits the attachment of a clamping ring (not shown).

Preferably the connector is a multi-pin connector.

Immediately behind the keys 14 are shoulder portions in the form of lugs 20. There is one lug behind each key, there being five keys in the example shown. Each lug 20 is of the same circumferential extent as its associated key 14, and has a radial height which is not greater than the height of the key. Between the lugs 20 and the keys 14 there is a groove 22. The lugs 20 together constitute a first shoulder means.

Axially-spaced from the lugs 20 along the cylindrical portion 12 is a second, continuous shoulder 24 which forms part of a flange 26 which has a locating function in use of the connector.

The base of the shoulder 24 is undercut by a V-shaped groove 28 extending around the shell.

A length of earthing (or grounding) strip 30 is placed around the cylindrical portion 12. A first edge 32 of the strip abuts the lugs 20, while the second edge 34 of the strip 30 engaged in the V-shaped groove 28 of the shoulder 24, as seen in Figure 2. The strip 30 is then retained on the shell by deforming the lugs 20 over the first edge 32 of the strip, this tending to force the second edge 34 into the V-shaped groove 28 where it bites into the sloping side of the groove to ensure good mechanical retention and electrical contact, as seen in Figure 3. The two ends of the length of strip 30 are arranged to be contiguous and to be located in the region of the widest (in the circumferential direction) one of the lugs 20, so that this lug holds down both the ends of the strip.

This is the lug which is in line with the major polarising key. A single blob of solder may if desired be added at this point to assist both mechanical securement against rotational movement of the strip and also electrical conduction.

It will be seen that the groove 22 enables the lug 20 which is formed integrally with the shell 10 to be deformed over the edge 32 of the strip 30.

The deformation may be made by any suitable operation, e.g. by being spun over. The groove 22 is wide enough to receive the spinning tool. The strip 30 can be retained on the shell 10 by very simple means, for example a rubber band, while the spinning operation takes place, which greatly facilitates manufacture of the shell.

It will be seen from Figure 3 that in the assembled condition the lugs 20 deformed over the edge 32 of the strip 30 both retain the edge 32 against radially outward movement and also retain the other edge 34 in the groove 28 to inhibit radially outward movement of that edge.

Since the lugs 20 are axially aligned with the associated keys 14 the lugs 20 can be of a radial height which is adequate when they are deformed to ensure retention of the strip without interfering with the function of the keys.

In an alternative embodiment the first shoulder means is constituted not by distinct lugs 20 but rather by a continuous shoulder of height and axial extent corresponding to that shown for the shell of the connector at the portion carrying the keys 14.

This shoulder can then be deformed over the strip by being spun over. The arrangement is such that the shoulder does not interfere with the connector engagement.

The earthing strip 30 illustrated is of a type having resilient fingers 36 which protrube radially and are axially directed. The fingers make good electrical contact with a receptacle all around the connector and thus ensure minimal electrical noise and that no inductive loop is formed at the connection. The strip 30 is preferably of irregular shape along its edge 34 which engages in the groove 28, such as the scalloped shape shown at 38. The corners of the scallops then bite into the groove wall and this provides a resistance to rotary movement of the strip on the shell. The cutouts forming the scallops 38 may be of other shapes, e.g. a more rectangular shape than that shown. Additionally, if desired to improve the electrical contact between the strip 30 and the shell 10, solder may be applied around the shell to fill the groove 28.

A modification is shown in Figure 4. In this the contact strip or spring 30 is located around the cylindrical portion 12 at a point intermediate the length of the keys 14. Thus the keys are broken such that each key 14 comprises two key portions which are in line but axially displaced.

It should be noted that the constructions illustrated can be used with stainless steel connector shells.

The systems illustrated facilitate the secure attachment of the earthing strip to the shell and enable the strip to be located in a thin-walled section of the shell, while providing a high degree of repeatability for use as a production process.

An alternative embodiment of the invention is illustrated in Figures 5 to 10. Corresponding parts bear the same reference numerals.

Referring to Figures 5 and 6, the connector shell 10 illustrated has a generally cylindrical portion 12 and is indeed as a whole of cylindrical shape. At its free end the shell carries keys 14 which engage in keyways on a corresponding receptacle and at the other end a screw thread 1 6 permits the attachment of a coupling ring (not shown). Preferably the connector is a multi-pin connector.

A length of earthing (or grounding) contact strip or spring 30 is located around the cylindrical portion 12 at a point intermediate the length of the keys. Thus the keys are broken such that each key 14 comprises two key portions which are in line but axially displaced. As shown in Figure 7, the contact strip 30 illustrated is of a.type having resilient fingers 36 protruding radially from the central region of the strip section and being axially directed. The fingers make good electrical contact with a receptacle all around the shell and thus ensure minimal electrical noise and that no inductive loop is formed at the connection.

The manner of securing the contact strip 30 will now be described with reference to Figures 7 to 10. The strip 30 is received in a dovetail shaped groove 40, that is a groove which has angled corners or overhangs 42 at its two edges forming recesses 44. Once the strip 30 is in the groove 40 it is too wide to escape in the radial direction. To insert the strip in the groove a feed slot or groove 50 (Figure 8) is formed at right angles to the groove 40 at one position around the shell and of the same depth as the groove 40. This then enables a length of strip 30 to be fed lengthwise into the groove 40 through the slot 50 and slid around the shell, as indicated in Figure 9, until it is fully located within the groove 40.For security one or both of the edges or overhangs 42 of the groove 40 can be deformed e.g. spun over the edges of the strip so as positively to trap the edges of the contact strip 30, as indicated in Figure 10.

The edges of the strip can be irregular, e.g.

scalloped, to further improve the resistance to rotation of the strip on the shell.

Normally the length of strip 30 is slid round so that the ends of the strip are located in line with the largest of the keys 14 (the major polarising key).

As shown in Figures 5 and 6, the contact strip 30 is located at an intermediate portion of the keys. Alternatively, the keys can be to one side only of the strip as indicated in Figure 7.

The construction illustrated can again be used with stainless steel connector shells.

It will be seen that the resultant assembly is achieved without the need for soldering or welding and within a very thin wall thickness.

Claims

1. A connector shell for a two-part electrical connector carrying a length of strip such as contact or earthing strip around the shell, in which first and second longitudinal edges of the strip are restrained against outward displacement by portions of the shell material formed integrally with the shell and which abut the outer surface of the strip at the edges thereof.

2. A connector shell according to claim 1, in which one or both edges of the strip are received in a respective V-shaped recess in the shell.

3. A connector shell for a two-part electrical connector including first and second axiallyspaced shoulder means having a generally cylindrical portion between them, the second shoulder means being provided with a recess opening towards the cylindrical portion, a length of strip such as contact or earthing strip around the shell with first and second edges of the strip abutting the first and second shoulder means respectively, and the first shoulder means being deformed over the first edge of the strip both to retain the latter against radially outward movement and to urge the second edge of the strip into a recess in the second shoulder means which retains the second edge of the strip against radially outward movement.

4. A connector shell according to claim 3, in which the first shoulder means is comprised of a plurality of circumferentially-spaced lugs.

5. A connector shell according to claim 4, in which the shell comprises a key portion adjacent the end of the shell and having one or more axially-orientated keys thereon, and the or each lug is axially aligned with an associated key.

6. A connector shell according to claim 5, in which the strip is located at a position intermediate the length of the keys.

7. A connector shell according to any of claims 3 to 6, in which the recess in the second shoulder means co-operates with the second edge of the strip by means of a corner engaging an oblique wall.

8. A connector shell according to any of claims 3 to 7, in which the recess in the second shoulder means comprises a groove of at least partially V-section.

9. A connector shell according to any of claims 3 to 8, in which the second edge of the strip is of irregular form.

1 0. A connector shell for a two-part electrical connector including first and second axiallyspaced shoulder means having a generally cylindrical portion between them, a key portion adjacent a first end of the shell and having one or more axially-oriented keys thereon, and a length of strip such as contact or earthing strip around the shell with first and second edges of the strip abutting the first and second shoulder means respectively, wherein the first shoulder means comprises one or more lugs each axially aligned with an associated key and each being deformed over the first edge of the strip to retain the latter.

11. A connector shell according to claim 10, in which the strip is located at a position intermediate the length of the keys.

12. A method of making a connector shell for a two-part electrical connector, comprising the steps of providing a shell member having first and second axially-spaced shoulder means having a generally cylindrical portion between them; forming on said second shoulder means a recess opening towards the cylindrical portion; positioning a length of strip such as contact or earthing strip around the shell with first and second edges of the strip abutting the first and second shoulder means respectively; and deforming the first shoulder means over the first edge of the strip both to retain the latter against radially outward movement and to urge the second edge of the strip into a recess in the second shoulder means which retains the second edge of the strip against radially outward movement.

13. A method according to claim 12, in which the shell member is formed with a key portion adjacent the end of the shell and having one or more axially-oriented keys thereon, the or each lug being axially aligned with an associated key.

14. A method of making a connector shell for a two-part electrical connector, comprising the steps of providing a shell member having first and second axially-spaced shoulder means having a generally cylindrical portion between them, the shell member having a key portion adjacent a first end of the shell member and with one or more axially-oriented keys thereon, and the first shoulder means comprising one or more lugs each axially aligned with an associated key; positioning a length of strip such as contact or earthing strip around the shell with first and second edges of the strip abutting the first and second shoulder means respectively; and deforming the lugs over the first edge of the strip to retain the latter.

1 5. A connector shell made by the method of claim 12, 13 or 14.

1 6. A method of assembling a length of strip on a connector shell for a two-part electrical connector, comprising the steps of providing a connector shell including a generally cylindrical portion having an overhung peripheral groove therein and feeding a length of strip such as contact strip lengthwise into the groove and around the shell such that the edges of the strip are retained against outward displacement by the edges of the groove.

1 7. A connector shell assembly made by the method of claim 1 6.

1 8. A connector shell substantially as herein described with reference to Figures 1 to 4 of the drawings.

1 9. A method of making a connector shell, substantially as herein described with reference to Figures 1 to 4 of the drawings.

20. A connector shell substantially as herein described with reference to Figures 5 to 10 of the drawings.

21. A method of making a connector shell, substantially as herein described with reference to Figures 5 to 10 of the drawings.