GB2156171A - Electrical connector - Google Patents

Abstract

A cartridge fuse holder of the bayonet type comprises an outer insulating housing member 1, including a contact 12 having a tag 13 and also a connector 16 with tags 17. An inner insulating cap 3 having a connector 4 fits into the housing member 1 in a telescopic relationship, the two being held together mechanically by a bayonet connection comprising pins 20 and slots 21 and being spring loaded in relation to one another by a spring 6. The connector 4 is fitted with a soft metal shim 10 which receives one end of a fuse 14, which is biased by a spring 11 against the contact 12. The connector 4 engages the connector 16 over an annular zone 16A so that a circuit is established between the tags 13 and 17 through the fuse 14. The cap 3 is capable of axial movement in relation to the connector 4 which is limited by a shoulder 7 so that the cap can move against the effect of the spring 6 without moving the connector 4 and thus without interrupting the circuit through the contact zone 16A. <IMAGE>

Description

SPECIFICATION Electrical connector This invention relates to electrical connectors, particularly those ofthe bayonet type. As is well known,thetwo parts of such aconnectorfittogether in telescopic relationship and one part has radially extending pins or similar projections which engage in slots in the other part.Each slot has an open-ended axially-extending portion terminating in a transverse portion so that when the two parts are fitted together, the pins enterthe open ends ofthe slots and then, as a result of a small degree of relative rotation move into the transverse portions ofthe slots to hold the two parts together. Forthis purpose,thetwo parts ofthe connection need to be relatively spring loaded so that the pins enterthe slots against the spring force and after movement into the transverse portions ofthe slots, are forced against the sides ofthe slots by the spring pressure so as to make the required electrical connection between the pins and the sides ofthe slots.

This type of connection has been known for many years and in the great majority of cases is entirely satisfactory. As just explained, the electrical connection is made as a result ofthe spring pressure urging the pins of one memberagainstthesidesofthe transverse portions ofthe slots ofthe other member, and this spring pressure is essential in order to maintain the connection. If, however, when the connection is made and a circuit is completed, relative axial pressure is exerted on thetwo parts ofthe connection,thespring pressure is overcome and the pins move awayfrom the sides ofthe transverse portions ofthe slots to interruptthe circuit.This may occur quite accidentally and for only a very short period oftime, but in certain types of circuit, particu- larly electronic circuits, any interruption can be undesirable and ought to be avoided.

The problem arises most frequently in fuse holders, e.g. holdersforelectrical fuse links ofthe miniature cartridge type where one end of the fuse is held in a cap which is connected to the remainder of the holder by a bayonet connection in the mannerjust described.

The fuse holder will normally be mounted in a panel with the cap projecting slightly so that it is particularly vulnerable to the application of accidental pressure which may interruptthe circuit even if only momentarily. Similar problems arise with othertypes of connector both ofthe bayonet type and of the screw type, and the invention is applicable broadly to any connector ofthis type, butfor simplicity will be described in relation to its application to a bayonet type fuse holder.

The invention is based on the idea of separating the mechanical connection from the electrical connection and providing a pair of spring loaded electrical connection members, one in each part ofthe connectorso that even if the two parts of the mechanical connection are inadvertently displaced in relation to one another, the circuit is not interrupted.It will be understood that such an arrangement is also useful with a screw connection, since it permits the connection to become partly unscrewed for example as the result of vibration, without separating the connection members. For this purpose, according to the inven- tion, an electrical connectorcomprisestwo insulating housing members, each carrying a respective electrical connection member and which fit together in a telescopic relationship and are held together mechanically by a bayonet or screw connection, being spring loaded in relation to one another so as to be capable of relative axial movement, and one of the housing members is also spring loaded in relation to the respective electrical connection member and is capable of limited axial movement in relation to it so that the housing member can move without moving the electrical connection member and thus without interrupting the circuit between the two connection members.

Consequently, the connection can be made between the two insulating housing members in the usual way, but if, when the connection has been made, there is inadvertent axial movement between the two insulating members, the provision for relative axial movement between one ofthe insulating members and one ofthe electrical connectors, means that the movement of the insulating member is not transmitted to the electrical connector and the circuit is not interrupted.

Preferably, a single spring provides the springloading between the two insulating housing members and between one ofthe housing members and the respective electrical connection member. This is conveniently in the form of a helical spring, but other forms of spring are possible, such as spring wshers or even members of elastomeric material. When the connector is in the form of a fuse holder, the normal spring loading of the fuse itself is required in addition to that necessaryforthe operation of the bayonet connection.

In the application of the invention to a holderfor a cartridge fuse, one end ofthefuse is held in a connection memberwhich is capable of limited sliding movementwithin an insulating cap and is controlled by a spring which biases it into a position in which it extends outwardly from the cap. The cap co-operates with a tubular insulating housing forthe fuse provided with a contact for engagement with the corresponding end of the fuse. When the fuse, held by the connector in the insulating cap is inserted into the housing, the connection member in the cap abuts against a fixed contact within the housing, constituting the second of the two connection members, and further pressure on the cap then causes relative sliding movement between the cap and the connector against the effect of the spring. A bayonet or screw connection between the cap and the insulating housing is then made in the usual way, the spring bias serving both to hold the connector member in engagement with the fixed contact and to control the mechanical connection. Once the connection has been made. the spring bias holds the connectorfirmly in engagementwith thefixed contact and any inadvertent pressure on the cap, leading to relative movement ofthe two parts ofthe mechanical connec ion does not affect the engagement between the connector and the fixed contact in any way and no interruption of the circuit occurs. As mentioned above, the normal spring loading for the fuse itself is also required and this can be provided at either end of the fuse.Preferably the additional spring is provided in the cap, extending through an opening in the end of theslidableconnectorwhich receives the end ofthe fuse. The end ofthe spring remote from the fuse may abut either against the interior of the insulating cap or may be secured to the connector itself.

An example of a fuse holder constructed in this way will now be described in more detail, with reference to the accompanying drawings, in which: Figure 1 is an axial sectional view ofthe fuse holder with a cap secured in position to an insulating housing; Figure 2 is an underneath plan view; and Figure 3 is an end view as seen from the left in Figure 1 and 2.

As best seen in Figure 1, the main components of the fuse holder comprise a tubular insulating body 1 which is open at the left hand end where it isformed with an enlarged flange 2, an insulating cap 3 which fits into the open end ofthe body 1 and an electrical connector4which forms an insertwithinthe cap 3 and is capable of limited sliding movement in relation to the cap. The connector4 is biased to the right as seen in the drawing, by means of a spring 6 which acts between the interiorofthe cap 3 and the left hand end ofthe connector 4.Movement ofthe connector4 to the right underthe action ofthe spring 6 is restricted by co-operating shoulders7 on the cap3 and the connector 4 respectively and movement of the con necAjQrtothe leftagainstthe effectofthespring 6 is limited by abutment of a shoulder8 on the connector with the end of the cap 3.

The interiorofthe connector4 is fitted with a soft metal shim 10so that the cap ofthe fuse, shown in dotted lines as 14, forms a tight sliding fit within the connector4.ln use,oneendofthefuseisfittedwithin the shim 10 where it engages the end of a spring 11, the other end of which abutsthe interior ofthe cap 3.

With the fuse held in this way, it is inserted within the insulating body 1 until the cap atthefurtherend engages a fixed contact 12 provided with a connecting tag 13. Further movement ofthe cap 3to the right compresses the spring 11 until the right hand end 15 of the connector 4 engages a contact ring 16 which is fixed within the housing 1 and includes a pair of connecting tags 17.

Itwill thus be understood that the electrical connection is made between the end ofthe connector4and the contact ring 16, along an annular zone indicated by a dotted line 16A, and that the contact pressure is maintained bythespring 6which also controls the bayonet connection. Forthe purposes of this mechanical connection,the cap 3 has a pair of pins 20, only the lower of which is seen in Figure land the body 1 has corresponding bayonet slots, the transverse portions ofwhich are seen at 21, the axial portions being shown as 22 in Figure 3.The cap 3 is controlled by a screw driverslot23 and when the cap has been inserted sufficiently farto make the electrical contact already described, further pressure bringsthe pins 20 into line with thetransverse portions 21 ofthe bayonet slots so that the cap 3 can be turned by a screw driver to completethe mechanical connection.

The body 1 is formed with an external screw thread 25 for a fixing ring 26, so that when the fuse holder is fitted in an opening in a panel the flange 2 engages the front ofthe panel and the ring 26 is screwed up against the rearofthe panel. The connecting tags 13 and 17 are then accessible at the rear.

If, when in the engaged position illustrated, the cap 3 is subjected to inadvertent mechanical pressure, this will move the pins 20 away from thesides of the transverse portions 21 of the bayonet slots, but since these are insulating parts performing only a mechanical function, this does not affectthe electrical circuit in any way. Inward movement of the cap 3 results in separation of the shoulders 7 on the cap and the connector4 respectively, butthe degree of relative sliding movement which is possible and the pressure exerted bythespring 6 meansthatthe movement of the cap does not affecttheconnector4in anyway which remains firmly pressed againstthe contact ring 16 by means of the spring 6.In addition, of course, the fuse is pressed againstthe contact 12 by the spring 11 and the cap at its left hand end remains in contact with the shim 10. As already explained,the spring 11 may befitted at the right hand end so asto bias a movable contact, equivalent to the contact 12 into engagement with the cap of the fuse.

If the invention is applied toforms of connector otherthan fuse holders, any equivalent of the spring 11 is not required and a single spring 6which has the dual function of maintaining the electrical contact (between 4 and 16 in the example illustrated) and of controlling the operation of the bayonet connection between the insulating parts is all that is required. If a connection is to be made in thiswaywithoutthe intervention of a fuse, a connection tag will need to be provided directly to the connector so that the circuit will extend from this tag, through the connector4to the ring 16 and thence to one ofthetags 17.

Connection will be made when the connector4 abuts the ring 16 under pressure exerted by the spring 6 and will not be interrupted by inadvertent pressure on the cap3.

Itwill be understood thatthe connection between the cap 3 and the tubular body 1 can equally well be a screw connection and that the modification involves no alteration to any ofthe other components ofthe construction. When the cap 1 has been screwed into position until theconnector4engagesthe ring 16, further rotation will merely compressthe spring 6.

Accordingly, if the cap is inavertently unscrewed, as the result of vibration for example, anyfurther rotation which has been applied will have to be removed before the circuit is broken.

Claims (1)

1. An electrical connectorcomprisingtwo insulating housing members, each carrying a respective electrical connection member and which fit together in a telescopic relationship and are held together mechanically by a bayonet or screw connection, being spring loaded in relation to one another so as to be capable of relative axial movement, and in which one of the housing members is also spring loaded in relation to the respective electrical connection member and is capable of limited axial movement in relation to it so that the housing member can move without moving the electrical connection member and thus without interrupting the circuit between the two connection members.

2. An electrical connector according to claim 1, in which a single spring provides the spring-loading between the two insulating housing members and between one of the housing members and the respective electrical connection member.

3. An electrical connector according to claim 2, in which the spring is a helical spring.

4. An electrical connector according to any one of the preceding claims in the form of a cartridge fuse holder having a loading spring for the fuse at one end and in which the electrical connection member capable of relative axial movement is shaped to hold one end of a fuse and is movable within a housing member in the form of a cap, from which it projects, the co-operating housing member being tubular and including a contact for engagement with the other end of a fuse held bythecapand afixedcontactfor engagement with the projecting portion of the connecting member in the cap, and constituting the second connection member.

5. A cartridge fuse holder according to claim 4, in which the loading spring forthe fuse is provided in the cap and extends through an opening in the electrical connection member holding the end of the fuse.

6. Acartridgefuse holderofthe bayonettype, substantially as described and as illustrated with reference to the accompanying drawings.

Amendmentstothe claims have been filed, and have the following effect: Claim 1 above has been textually amended.

Atextuallyamended claim has been filed as follows:

1. An electrical connector comprising two insulating housing members which fit together in a telescopic relationship, are held together mechanically by a bayonet or screw connection and carry respective electrical connection members which engage one anotherto form a direct electrical connection, the housing members being spring loaded in relation to one anotherso as to be capable of relative axial movement, and in which one of the housing members is also spring loaded in relation to the respective electrical connection member and is capable of limited axial movement in relation to itso that the housing member can move without moving the electrical connection member and thus without interrupting the circuit between the two connection members.