GB2326538A - Bayonet connector - Google Patents

Description

CONNECTOR This invention relates to a connector.

Conventional plug/socket connectors rely on resilient conductive tongues in the socket, which bear on the conductive zones of the plug, to hold the plug in the socket. This provides a limited resistance to pulling of the plug out of the socket but in some situations the plug can be accidentally pulled out of socket - especially if the lead connected to the plug is tugged.

One approach to solving this problem is to use a threaded sleeve which surrounds the body of the plug and can be screwed to the socket (once the plug has been plugged into place) to hold the plug captive between the sleeve and the socket.

However, this arrangement is cumbersome to use, especially in confined spaces, and requires the extra component of the sleeve.

Another approach is to use a bayonet fixing (see figure 1), where pins 90 on the plug are twisted into slots 91 on the socket and held in place in notches 92 by means of a spring inside the socket. This solution is easier to use but requires extra space (because of the need to provide for extra axial movement of the plug into the slots 91 and beyond its "in use" position in notches 92), and requires the additional component of the spring to be provided.

According to the present invention there is provided a plug/socket electrical connector comprising: a first connector body having a radially inwardly directed lip extending from its mating end; and a second connector body having a radially outwardly directed lip extending from its mating end; the lips being arranged to interlock, to hold the connector bodies in their connected configuration, when the connector bodies are mutually rotated about the plug/socket axis.

Each connector preferably has at least two such lips, most preferably exactly two.

The lips are preferably symmetrically disposed about the plug/socket axis, suitably so that the plug can be inserted and locked in the socket in more than one rotational orientation. The lips of the first connector body are preferably spaced apart circumferentially to allow the lips of the second connector body to pass between them when the plug is inserted in the socket.

The mating end of one of the connector bodies preferably presents a surface for abutting the lip(s) of the other of the connector bodies when the connectors are engaged, to limit insertion of the plug into the socket.

The or each lip of the first connector body is preferably connected to the first connector body by an axially-extending wall. This preferably spaces the or each such lip from the mating end of the first connector body, suitably leaving a channel between the lip and the mating end. This channel is suitably dimensioned to receive (preferably snugly) the lip(s) of the second connector body when the lips are interlocked.

The plug/socket connector preferably has a snap-fit action when the connectors are mutually rotated to the position where the lips interlock. This action is preferably provided by means of resilient deformation of one or more of the lips, or of the said axially extending wall. This deformation is most preferably in a radial direction or an axial direction. The action is preferably provided by the camming of one or more of the lips against a corresponding camming surface of the opposite connector body.

The or each camming surface is preferably shaped so as to cause radial displacement of the or each lip of the first connector body when the first connector body is rotated out of locking engagement with the second connector body.

Preferably the first connector body is a plug body and the second connector body is a socket body. Alternatively, the second connector body is a plug body and the first connector body is a socket body. To allow for the mutual rotation of the. connector bodies when the plug is inserted in the socket there is preferably a single terminal extending from the plug body. The terminal is preferably substantially symmetrical about the plug/socket axis.

The individual connector bodies themselves constitute further aspects of the present invention.

The present invention will now be described by way of example, with reference to the accompanying drawings, in which: figure 2 is a drawing of an electrical connector comprising a plug and a socket; figure 3 is a view from the mating end of the plug; figure 4 is a view from the mating end of the socket.

Figures 2, 3 and 4 show a male/female connector for electrical signals. The male plug 1 of the connector comprises a single elongate pin 2 and a housing 3. The pin has two electrical contact regions 4,5 separated by an insulator 6. The housing 3 is made of insulating material and protects an inner volume 7 where the conductive wires of cable 8 are terminated and connected to the pin. The plug has a flat abutment surface 9, perpendicular to the axis of the pin, provided by a flange 10 at the base of the pin and a flat region 11 of the housing, which surrounds the flange 10.

A locking structure is borne by housing 3. Extending axially (i.e. along the axis of the pin 2) from the flat region are two spacing walls 12. The inner surfaces 13 3 of the spacing walls lie on a circle about the axis of the pin 2. Two locking walls 14 extend radially inwardly from the distal ends of the spacing walls. The inner surfaces 15 of the locking walls are straight and parallel to each other, spaced equally on either side of the pin. The spacing walls 12 are of equal heights above the abutment surface 9, so that a similar channel is defined between the bottom surface 16 of each locking wall 14 and the abutment surface 9.

The female socket 40 of the connector comprises a housing 17 which provides a passage 18 for receiving the terminal 2 of the plug 1. Conductive spring fingers 19 (only one of which is shown) are provided along the passage to make contact with the contact regions of the pin 2. On the base of the housing are solder tabs 41 (only one of which is shown) which allow the fingers to be connected to a circuit board.

Around the open end of the passage 18 a second locking structure is provided. This comprises a pair of segmental end walls 20 which have flat end surfaces 21, outer surfaces 22 which lie on a circle about the axis of the passage, and rear surfaces 23.

Between the end walls (and in their plane) the outer rim of the housing 17 is made up of two flat surfaces 24 which are straight and parallel to each other, spaced equally on either side of the passage 18. Behind the rear surfaces 23 is a radial surface which has two camming regions each comprising a portion 25 generally flush with one of the surfaces 24 which curves smoothly into a flat portion 26 perpendicular to the surfaces 24. There are abrupt corners 27 between the camming regions. Thus the radial spacing of the camming surface from the socket axis is slightly larger at the curved zones 25a than in the portions 25 and 26 and significantly larger at the corners 27.

The spacings of the surfaces 15, the surfaces 24 and the flat portions 26 are generally equal, with the spacing between the surfaces 15 being slightly larger than that between the surfaces 24,to allow the locking structure of the plug to fit snugly on the locking structure of the socket.

The operation of the connector will now be described. First, the pin 2 is fully inserted axially into the passage 18, so that the spring fingers 19 9 of the socket make contact with respective contact regions 4,5 of the plug and the abutment surface 9 of the plug abuts the end surfaces 21 of the socket. To allow the pin to be fully inserted the plug and socket must be mutually rotationally aligned, with the inner surfaces 15 of the plug parallel with the flat surfaces 24 of the socket, so that the locking structure.

of the socket can pass between the surfaces 15. At this stage the pin is retained in the passage somewhat by the spring fingers, as in the prior connectors discussed in the preamble.

The plug is then twisted about its axis 90" clockwise relative to the socket (as indicated by the arrow 42 in figure 4, from an "unlocked" position to a "locked" position. As the plug is twisted the locking walls 14 and the end walls 20 are moved into an overlapping relationship, with the bottom surfaces 16 of the locking walls 14 abutting the rear surfaces 23 of the end walls 20 and the end walls 20 lying between the locking walls 14 and the abutment surface 9. To ensure a secure fit, the spacing between the bottom surface 16 and the abutment surface 9 matches the thickness of the end walls 20, and the radius of the inner surfaces 13 of the spacing walls matches the radius of the outer surfaces 22 of the end walls 20. With the locking walls 13 and the end walls 20 overlapped in this way the plug is held in place and cannot be removed from its connected position in the socket without first being twisted. Since it is difficult to twist the plug by means of the cable 8 (because the cable 8 will often tend to coil up rather then transmit torque to the plug) this provides a significant increase in security.

To further increase security the connector also has means to resist rotation of the plug between the locked and unlocked positions. The inner surfaces 14 of the plug to remain in contact with the camming region of the socket as the plug is turned. To achieve this the spacing walls 11 are somewhat resilient and deform outwards beyond their normal positions as the plug is twisted, biasing the locking walls 14 inwards as they ride over the curved zones 25a. As the plug is twisted further relative to the socket in the locking direction the spacing walls 11, and thus the inner surfaces 15 which they carry spring back as the flat of the inner surface 14 meets the flat portion 26 in the 90" (locked) position. The maximum deformation of the walls 11 is when the locking walls 14 sit on the curved zones 25a, in approximately the 45" position. Movement of the plug beyond the 90" position is resisted by the corners 27: the radial spacing of these corners from the plug axis is sufficiently great that the walls 11 cannot deform sufficiently to allow the walls 14 to ride over those corners.

This arrangement produces an action whereby the plug snaps into place inthe locked position with the inner surface 14 biased against the flat portion 26.

Movement from the locking position - in either direction - is resisted by the bias of the walls 11. (Alternative constructions could have rigid walls 11 but the camming surface resiliently deformable inwards beyond the position illustrated in the figures, or a combination between the two is possible).

The housings of the plug and socket may suitably be made of nylon, ABS or other materials, preferably insulating materials. The plug/socket connector is preferably for a standard plug/socket size: for example, 2.5mm phono jack, 3.5mm phono jack or 0.25" phono jack.

The present invention may include any novel feature or combination of features disclosed herein either explicitly or implicitly or any generalisation thereof irrespective of whether or not it relates to the presently claimed invention or mitigates any or all of the problems addressed. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims (12)

1. A plug/socket electrical connector comprising: a first connector body having a radially inwardly directed lip extending from its mating end; and a second connector body having a radially outwardly directed lip extending from its mating end; the lips being arranged to interlock, to hold the connector bodies in their connected configuration, when the connector bodies are mutually rotated about the plug/socket axis.

2. A plug/socket connector as claimed in claim 1, wherein the first connector body has two radially inwardly directed lips extending from its mating end and the second connector body has two radially outwardly directed lips extending from its mating end.

3. A plug/socket connector as claimed in claim 2, wherein the lips are symmetrically disposed about the plug/socket axis.

4. A plug/socket connector as claimed in claim 2 or 3, wherein the lips of the first connector body are spaced apart circumferentially to allow the lips of the second connector body to pass between them when the plug is inserted in the socket.

5. A plug/socket connector as claimed in any preceding claim, wherein the or each lip of the first connector body is resiliently displaceable radially.

6. A plug/socket connector as claimed in any preceding claim, wherein the or each lip of the first connector body is connected to the first connector body by a resilient axially-extending wall.

7. A plug/socket connector as claimed in claim 5 or 6, wherein the second connector body includes a camming surface for camming against the or each deformable lip.

8. A plug/socket connector as claimed in claim 7, wherein the camming surface is shaped so as to cause radial displacement of the or each lip of the first connector body when the first connector body is rotated out of locking engagement with the second connector body.

9. A plug/socket connector as claimed in claim 8, wherein the or each lip of the first connector is resiliently biased against said radial displacement.

10. A plug/socket connector as claimed in an preceding claim, having a single terminal extending from one of the connector bodies and a single socket in the other of the connector bodies.

11. A plug/socket connector as claimed in claim 10, wherein the terminal is substantially symmetrical about the plug/socket axis.

12. A connector substantially as herein described with reference to figures 2 to 4 of the accompanying drawings.