GB2134333A - Environmental sealing of electrical connectors - Google Patents

Abstract

An electrical connector in the form of a two-part coupling comprises a connector block (2, 3 or 4) with a plurality of contacts (6) arranged over a face thereof for mating with contacts of the other coupling part and a shell (1) in which the connector block is fitted. The connector block (2, 3 or 4) is provided with a pre-formed resilient 'O' ring (12) located in a peripheral groove (10) in the connector block (2, 3 or 4) and which makes engagement with an adjacent wall surface of the shell (1) to locate and seal the connector block in the shell. <IMAGE>

Description

SPECIFICATION Improvements relating to electrical connectors The present invention relates to electrical connectors in the form oftwo-partcouplings. In particular the invention relates to electrical connectors, for exam- ple so-called miniature electrical connectors, in which one or each coupling part comprises a connector block with a plurality of contacts, for example socket contacts, arranged over a face thereof for mating with respective contacts, for example pin contacts, of the other coupling part, each connector block being fitted into its own carrier or so-called shell. Advantageously, when the coupling is made the two shells abut each other around a continuous joint to form a housing enclosing the connector blocks.

It is known to fix and seal the connector blocks in their respective shells by the use of a sealing compound which, prior to the fitting of the block into its shell, is provided as a bead around the entire periphery of the block at a distance from the contact carrying face so that when the block is pushed into its shell, the sealing compound seals with a continuous seal with an adjacent wall surface of the shell. Advantageously a seal is also provided between the co-operating surfaces of the shells so that when the coupling is made the contact carrying faces of the two connector blocks are contained within a moisture proof compartment within the shells.

One problem encountered with the use of seals made by sealing compounds is that it is difficult to remove the connector blocks from their shells when in service. Another problem is that when the connector blocks are fitted into their shells the sealing compound becomes smeared over the connector blocks and the adjacent wall surfaces of the shells and this must be carefully removed, e.g. by solvent, before the connector blocks can be replaced or new ones fitted. The removal and replacement of the connector blocks is therefore messy and time consuming.

A further problem concerns the fit or registration of the connector blocks within the shells which must be strictly maintained to ensure correct mating of the connector contacts and allowing for practicable tolerances of the dimensions of shell and block.

Correct registration can be achieved by making the block oversize in local areas and cutting these areas whilst jigged for correct registration during the assembly process. Alternatively, correct registration can be achieved by making the block undersize and jigging whilst the sealing compound is cured to set and maintain the jigged dimensions. A block that is cut to size during the assembly process may be difficult to remove for replacement purposes. Jigs and fixtures for these purposes are costly in particular if designed to be used in the confined space of a connector in-situ. The use of jigs in some in-situ applications may be impracticable.

The object of the present invention is to obviate the aforesaid problems.

According to the present invention the connector block of the or each coupling part is provided with a preformed resilient member, e.g. an '0' ring, located in a peripheral groove in the connector block and which makes engagement with an adjacent wall surface of the shell to locate and seal the connector block in the shell.

The present invention is particularly advantageous in the case where a connector block is itself made in two parts with a peripheral split line between the two parts so that the connector block has a front part containing the contact carrying face and a rear part.

The two parts are normally secured to each other by adhesive. In this case the peripheral groove is conveniently formed by providing a peripherally extending step on the rear part at the split line so that the groove is defined by the two surfaces of the step and the face of the front part at the split line.

Thus when the connector block is fitted to the shell and the resilient member is under some small compression, the resilient member is preventing ingress of moisture to the split line.

Advantageously the connector block locates in the shell through ribs which extend rearwardly from the front face, i.e. the contact face, of the connector block but which stop short of the groove locating the resilient member. The ribs are accurately dimensioned to provide a close fit but not a force fit within the shells to permit ready removal of the connector blocks from and replacement in the shells.

It is desirable to make the shell and connector block to dimensions having practicable tolerances.

Hence the aforementioned close fit may on worst combinations of tolerance provide an unacceptable location of the block within the shell if the block is unrestrained to take up any position permitted by the tolerances. The effect of the resilient member being under some small compression is to locate the block more or less central within the aperature of the shell defined by the surfaces of the shell with which the resilient member is in contact. This is advantageous in minimising the effect of the tolerances.

One two-part coupling in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 shows a view on the contact carrying face of one part of the coupling looking in the direction of arrow A of Figure 2, Figure 2 is a section on the line B-B of Figure 3, Figure 3 shows a view of the opposite face of the same part of the coupling shown in Figure 1 and looking in the direction of arrow C of Figure 2, and Figure 4 is a detail of the part in circle D of Figure 1.

Referring now to the drawing the coupling part shown has a shell 1 containing three connector blocks referenced 2,3 and 4. Each of the connector blocks carries a plurality of contacts which are either pins or sockets. Assuming that these are socket contacts, the other coupling part will have the same arrangement of connector blocks in its shell these connector blocks having pin contacts so that when the two part coupling is made each pin contact engages in a respective socket contact. In Figure 1 the contacts of the connector blocks 2,3 and 4 have been referenced 5, 6 and 7 respectively.

The three connector blocks 2, 3 and 4 are fitted into the shell 1 in identical manner and it will suffice therefore to describe in detail the fitting of the connector block 2. The connector block 2 has separately formed front and rear parts 8 and 9 (Figure 2) with a split line between them at 10, the parts 8 and 9 being secured together by adhesive.

The rear part 9 is preformed with a peripheral step which with the adjacent face of the front part 8 defines a peripheral groove locating an '0' sealing ring 12.

The connector block 2 is fitted into the shell 1 by pushing it in the direction of arrow C (Figure 2) into its aperture in the shell 1 until it comes up against shoulder 13. The sealing ring forms a continuous peripheral seal with the wall surface 14 of the aperture.

To enable accurate location of the connector block 2 in its aperture, it is provided with ribs 15 which are accurately dimensioned to provide a close fit but not a force fit in the aperture.

The connector blocks 2, 3 and 4 are clamped in the shell 1 by a clamping member 17 which is secured to the shell 1 by screws 18.

When the coupling is made the shell 1 makes a continuous seal with the shell of the other coupling part. These seal joints are at surface 20 surrounding connector blocks 2 and 3 and at surface 21 surround ing connector block 4. An '0' ring sealing member is provided between these surfaces so that the front parts of the connector blocks including the split lines 10 are contained in moisture proof compartments defined between these sealing members and the sealing rings 12.

To seal against ingress of moisture to the contacts at the rear of the connector block where the contact terminations and connecting wires protrude can be achieved in known manner by the use of a sealing sheet or so-called grommet. This is secured to the rear of the connector block by adhesive and provides a flexible envelope punctured by holes through which the wires or terminations pass. These holes are of a size and configuration to grip the wire or termination around one or more circumferences along their length and thereby seal against the ingress of moisture.

Claims (6)

1. A coupling part of an electrical connector in the form of a two-part coupling, said coupling part comprising a connector block, a plurality of contacts arranged over a face thereof for mating with con tacts of the other coupling part and a shell in which the connector block is fitted, characterised in that the connector block is provided with a pre-formed resilient member located in a peripheral groove in the connector block and which makes engagement with an adjacent wall surface of the shell to locate I and seal the connector block in the shell.

2. A coupling part according to claim 1,wherein said preformed resilient member comprises an 'O' ring.

3. Acoupling part according to claim 1 or 2, wherein the connector block is in two parts with a peripheral split line so that the connector block has a front part containing the contact carrying face and a rear part and wherein the peripheral groove is located at said split line.

4. A coupling part according to claim 3, wherein said peripheral groove is formed by providing a peripherally extending step on the rear part at the split line so that the groove is defined by the two surfaces of the step and the face of the front part at the split line.

5. A coupling part according to any one of claims 1 to 4, wherein the connector block has ribs which extend rearwardly from the front face of the connector block and stop short of the peripheral groove, said ribs being a close fit, but not a force fit in the shell.

6. A coupling part of an electrical connector substantially as hereinbefore described with reference to the accompanying drawings.