EP0247814A2

EP0247814A2 - Electrical connectors

Info

Publication number: EP0247814A2
Application number: EP87304599A
Authority: EP
Inventors: Ronald Chard; Donald Leonard Watson
Original assignee: FKI Electrical Components Ltd
Current assignee: TEC Electrical Components Ltd
Priority date: 1986-05-28
Filing date: 1987-05-22
Publication date: 1987-12-02
Also published as: EP0247814A3; GB8612963D0

Abstract

A knurled coupling nut 7 houses a dielectric insert 2A which can rotate relative to the nut 7 against a torque restraint provided by leaf springs 11 co-operating with outwardly facing gear teeth 13 on the insert 2A.

The springs 11 fit into different cavities 12 in which, in the assembled condition, the base of each cavity is provided by the gear teeth 13 and the opposite face of each cavity is provided by the inner surface of the coupling nut. The front wall to each cavity is provided by a locating washer 14, the washer 14 having a plurality of evenly spaced lugs 14A, and tapered side walls of those lugs 14A provide side walls to the cavities 12.

In the position shown, one apex of the spring would engage the teeth 13 to provide a ratchet mechanism for the coupling nut. In an alternative arrangement one or more of the springs 11 may be reversed so that apices of that spring engage different teeth 13 of the ratchet to provide a different ratchet torque.

Description

The present invention relates to electrical connectors and to a method of assembling such connectors.
This invention is particularly, although no exclusively, with cylindrical electrical connectors, and more particularly with electrical connectors in which a plurality of electrical contacts are supported in an insulating insert assembly, the insert assembly being fixed in a substantially cylindrical shall. Such connectors are described, for example, in British Standard Specification No. BS9522, and are commonly, but not exclusively, used in the aerospace industry. A typical connector assembly includes a fixed connector whose insulating insert supports a plurality of pin type female contacts and a free connector whose insulating insert supports a plurality of pin type male contacts. The fixed and free connectors may rapidly connect and disconnect by means of a knurled coupling nut and, once connected, should remain connected under adverse environmental conditions which may include extreme temperature variations and high vibration. Various forms of ratchet type anti-decoupling mechanisms have been proposed in order to maintain a pair of connectors together under adverse conditions. British Patent No. 1585438, for example, discloses a connector in which the other surface of the cylindrical shell is provided with an annular shoulder having a number of outwardly extending gear teeth which contact a plurality of substantially straight leaf springs assembled to the inner surface of the coupling nut. Each spring lies tangential to the shoulder and has a central inwardly directed projecting member which engages the gear teeth. British Patent No. GB 2042822B discloses a substantially similar arrangement in which the spring and the projecting member are of a plastics material. such arrangements have a number of practical disadvantages. First, the arrangements disclosed in the above numbered patent specifications require the springs first to be assembled to an inner surface of the coupling nut before the cylindrical shell is inserted into the nut and the projecting members engage the gear teeth. Supporting the springs during this assembly procedure is a delicate and time consuming operation, particularly when assembling small connectors. Second, a connector of a given size is generally suitable for use with only one design of spring, and there is no flexibility for varying the ratchet torque. Third, the spring projecting members, whether of metal or plastics material, are prone to wear if the connector is coupled and decoupled many times while in service and finally, the arrangements illustrated require precisely defined cavities or holes to be formed in an inner surface of an unthreaded portion of the coupling nut into which a spring or a spring fixing pin must be inserted in order that the spring may be properly positioned to engage the gear teeth. If the nut is of a metal material, as is commonly the case, the forming of such cavities or holes, in addition to the aforementioned assembly procedure, is likely to be a time consuming and costly process, particularly when manufacturing small connector assemblies.
According to one aspect of the present invention an electrical connector includes a first and second housing each supporting an insert portion including a plurality of electrical contacts, the housings being arranged to threadably engage each other whereby relative rotational movement in a first direction of one housing relative to another housing is arranged to cause relative translational movement of the insert portions to connect the electrical contacts, the connector being characterised in that a rotation inhibiting assembly is provided between one insert portion and the housing which supports that insert portion in order to inhibit relative rotation between that insert portion and the housing, the assembly including at least one sprung element which has been located in one of at least two positions on one of the insert portion and housing in one of which positions at least the sprung element is arranged to co-operate with a series of teeth located on the other of the insert portion and housing, in order to vary the force which inhibits relative rotation between the insert portion and housing. With such an electrical connector the torque of the rotation inhibiting assembly can be varied either during assembly of the connector by selecting the position of the sprung element or, alternatively or additionally, the torque can be altered on an already assembled electrical connector by selecting a different position for a sprung element. The sprung element may be arranged to co-operate with the teeth in at least two positions with the force which inhibits relative rotational movement between the insert portion and housing varying in dependence upon the position of the sprung element.
The selection of the position of the sprung element may be achieved by altering the orientation of the sprung element on the insert portion or housing on which it is located. In one orientation of the sprung element, more teeth may be engaged by the sprung element than at another orientation of the sprung element.
Movement in one rotational direction of the sprung element relative to the insert portion or housing on which it is located may be prevented or limited by abutment of one end of the sprung element with a portion of the insert portion or housing on which it is located and movement in the other rotational direction of the sprung element relative to the insert portion or housing on which it is located may be prevented or limited by abutment of the other end of the sprung element with a different portion of the insert portion or housing on which it is located.
The sprung element may be held in place by being located in a cavity defined between the teeth, circumferentially spaced portions on the insert portion or housing on which it is located and axially spaced portions on either side of the sprung element.
The connector may include a plurality of sprung elements, and the sprung elements may be substantially equally circumferentially spaced from each other.
According to another aspect of the present invention a method of assembling an electrical connector as herein referred to may comprise selecting one of at least two possible positions of the sprung element in one of which positions at least the sprung element co-operates with the teeth.
According to a further aspect of the present invention an electrical connector includes a first and second housing each supporting an insert portion including a plurality of electrical contacts, the housings being arranged to threadably engage each other whereby relative rotational movement in a first direction of one housing relative to another housing is arranged to cause relative translational movement of the insert portions to connect the electrical contacts, the connector being characterised in that a rotation inhibiting assembly is provided between one insert portion and the housing which supports that insert portion in order to inhibit relative rotation between that insert portion and the housing, the assembly including at least one sprung element located on one of the insert portion and housing arranged to co-operate with a series of teeth located on the other of the insert portion and housing, to inhibit relative rotation between the insert portion and housing, movement in one rotational direction of the sprung element relative to the insert portion or housing on which it is located being prevented or limited by abutment of one end of the sprung element with a portion of the insert portion or housing on which it is located and movement in the other rotational direction of the sprung element relative to the insert portion or housing on which it is located being prevented or limited by abutment of the other end of the sprung element with a different portion of the insert portion or housing on which it is located. The sprung element may be held in place by being located in a cavity defined between the series of teeth, circumferentially spaced portions on the insert portion or housing on which it is located and axially spaced portions on either side of the sprung element.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which:-

Figure 1 is a perspective view of a connector assembly showing fixed and free connectors,
Figure 2 is an exploded perspective view of a multiple spring free connector according to one embodiment of the invention,
Figure 3 is a diametric part-sectional view of a four spring free connector according to an embodiment of the invention.
Figure 4 is a rear end view of the connector of Figure 3 with a rear support washer and a retaining clip removed.

Figure 1 shows a typical connector assembly in which a fixed connector 1 includes a dielectric insert 2 supporting a plurality of cylindrical female contacts 3. Referring to Figure 2, a free connector 1A includes a substantially cylindrical shell 4 which encloses a dielectric insert 2A supporting a plurality of mating pin type male contacts 3A. Each insert and its pin contacts is supported in the associated connector by means such as are described, for example, in our pending European Patent Application No. 85303548.3. The free connector is provided with splines 5 locating with grooves 6 in the fixed connector to ensure alignment of the male and female contacts when the fixed and free connectors are assembled together, and a knurled coupling nut 7 encircling the free connector shell 4 may be screwed and tightened on to external threads 8 on the fixed connector when the two connectors are assembled, in known manner.
The knurled coupling nut 7, when assembled, surrounds the substantially cylindrical shell 4 and the inner surface of the front portion of the nut is internally threaded for screwing to the externally threaded end region 8 of the fixed connector 1.
A plurality of substantially gull wing shaped, or w-shaped, leaf springs 11 are inserted into cavities 12 lying in an annular cylindrical space between the inner surface of a rear, unthreaded, region of the coupling nut 7 and a ring of radially outwardly facing gear teeth 13 on a raised shoulder in the central region of the outer surface of the cylindrical shell 4. The leaf springs 11 fit loosely into the cavities 12 if inserted before the coupling nut 7 is assembled around the cylindrical shell, as is shown in Figure 2. Figures 3 and 4 shown an assembled free connector having four springs 11 in associated cavities 12. It will be appreciated that the number of springs and cavities provided may vary from two to any desirable number, and the cavities 12 are preferably evenly spaced around the cylindrical shell.
The base of each cavity is provided by the gear teeth 13 and the opposite face of each cavity is provided by the inner surface of the coupling nut. The front wall to each cavity is provided by a locating washer 14 resting in a recess in the coupling nut 7, as is shown in Figure 3. A plurality of evenly spaced lugs 14A, Figure 4, with appropriately tapered side walls are provided on the rearward facing surface of the locating washer 14 such that the lugs 14A extend rearward of the gear teeth 13 and the tapered side walls provide side walls to the cavities 12.
When the component parts of a free connector are assembled together the coupling nut 7 is first placed around the shell 4 and its associated insert 2A such that the gear teeth 13 align with the required position for the springs 11 as is shown in Figure 3.
The locating washer 14 is then inserted around the shell and into the nut from the rear of the connector. One or more locating protrusions (not shown) extend frontwards of the locating washer into suitably positioned recesses (not shown) in the unthreaded interior of the nut such that, when inserted, the locating washer cannot rotate relative to the nut. The springs 11 are then inserted into the cavities 12 formed by the gear teeth, the side walls of the rearward facing lugs 14A the rearward facing portions of the locating washer lying between the protrusions, and the inner surface of the shell 4. The springs are dimensioned such that, as shown at 11 in Figure 4, one apex of the spring engages the teeth 13 to provide a ratchet mechanism for the coupling nut. Alternatively, a spring may be designed such that two apices engage the teeth, as is shown at 11R in Figure 4. The spring and washer geometry may be so chosen that the springs may be reversible and one or more of the springs may have the apices engaging the teeth or vice-versa. Alternatively, the geometry may be such that in the "normal" position with one apex engaging the teeth, a reversed spring may not physically engage the teeth, but may be stored in its cavity to be re-reversed and increase the overall torque of the ratchet mechanism.
When the springs have been inserted into their associated cavities, a retention washer or a rear support washer 15 and a retaining lock ring or clip 16, Figures 2 and 3, are assembled to the rear of the connector to close the cavities after the springs have been inserted. The washer 15 is a tight fit in the open rear end of the coupling nut 7 and the lock ring is located in a groove of the insert 2A (not shown).
It will be appreciated that the present invention provides a great deal more flexibility in choice of ratchet torque than has hitherto been achievable in providing the option of reversible springs. Additionally, while it may be necessary to provide a metal rather than a plastics coupling nut, the locating washer may conveniently comprise a low cost plastics moulding. A range of locating washers, having different lug geometries, may be provided for a shell of a particular size, thereby providing a choice in the number of spring cavities for a given coupling nut design. The coupling nut remains essentially cylindrical, without requiring precisely machined cavities for spring supports, since the necessary precision will occur in the plastics moulding. A further advantage of the present invention lies in using an apex of a w-shaped or gull-wing shaped leaf spring to engage the gear teeth. The leaf spring would normally be formed of a spring steel material, which is mechanically hard and wear resistant while resilient to the passage of gear teeth. Such a spring is likely to provide improved wear resistance compared with the spring designs disclosed in the aforementioned prior art.
Alternative embodiments of the invention will be apparent to those skilled in the art. For example, if disassembling the connector is unlikely to be required in service, the lock ring or clip 16 may be dispensed with and the rear portion of the coupling nut may be swaged or otherwise formed over the rear support washer 15. The rear support washer may alternatively be fixed to the coupling nut by means of suitable screw thread or glue.
In a further alternative embodiment, the side walls of each cavity may, instead of being provided by the spaced lugs 14A of the separate locating washer 14, be provided by machining out a portion of the coupling.

Claims

1. An electrical connector including a first and a second housing each supporting an insert portion including a plurality of electrical contacts (3,3A), the housings being arranged to threadably engage each other whereby relative rotational movement in a first direction of one housing relative to another housing is arranged to cause relative translational movement of the insert portions to connect the electrical contacts, characterised in that a rotation inhibiting assembly is provided between one insert portion (4) and the housing (7) which supports that insert portion (4) in order to inhibit relative rotation between that insert portion and housing, the assembly including at least one sprung element (11) which has been located in one of at least two positions on one of the insert portion (4) and housing (7) in one of which positions at least the sprung element (11) is arranged to co-operate with a series of teeth (13) located on the other of the insert portion and housing, in order to inhibit relative rotation between the insert portion (4) and housing (7).

2. A connector as claimed in Claim 1 in which the sprung element is arranged to co-operate with the series of teeth (13) in at least two positions with the force which inhibits relative rotational movement between the insert portion and housing varying in dependence upon the position of the sprung element (11).

3. A connector as claimed in Claim 1 or 2 in which the selection of the position of the sprung element (11) is achieved by altering the orientation of the sprung element (11) on the insert portion (4) or housing (7) on which it is located.

4. A connector as claimed in Claim 3 in which, in one orientation of the sprung element (11), more teeth (13) are engaged by the sprung element (11) than at another orientation of the sprung element (11).

5. A connector as claimed in any preceding claim in which movement in one rotational direction of the sprung element (11) relative to the insert portion or housing on which it is located is prevented or limited by abutment of one end of the sprung element (11) with a portion (14A) of the insert portion or housing (7) on which it is located and movement in the other rotational direction of the sprung element relative to the insert portion (4) or housing (7) on which it is located is prevented or limited by abutment of the other end of the sprung element with a different portion (14A) of the insert portion (4) or housing (7) on which it is located.

6. A connector as claimed in any preceding claim in which the sprung element (11) is held in place by being located in a cavity (12) defined between the series of teeth (13), circumferentially spaced portions (14,15) on the insert portion (4) or housing (7) on which it is located and axially spaced portions (14A) on either side of the sprung element (11).

7. A connector as claimed in any preceding claim including a plurality of sprung elements (11).

8. A connector as claimed in Claim 7 in which the sprung elements (11) are substantially equally circumferentially spaced from each other.

9. A method of assembling an electrical connector as claimed in any preceding claim comprising selecting one of at least two possible positions of the sprung element (11) in one of which positions at least the sprung element co-operates with the ratchet.

10. An electrical connector including a first and a second housing each supporting an insert portion incuding a plurality of electrical contacts (3,3A), the housings being arranged to threadably engage each other whereby relative rotational movement in a first direction of one housing relative to another housing is arranged to cause relative translational movement of the insert portions to connect the electrical contacts, characterised in that a rotation inhibiting assembly is provided between one insert portion (4) and the housing (7) which supports that insert portion (4) in order to inhibit relative rotation between that insert portion (4) and housing (7), the assembly including at least one sprung element (11) located on one of the insert portion (4) and housing (7) arranged to co-operate with a series of teeth (13) located on the other of the insert portion (4) and housing (7) to inhibit relative rotation between the insert portion (4) and housing (7), movement in one rotational direction of the sprung element (11) relative to the insert portion (4) or housing (7) on which it is located being prevented or limited by abutment of one end of the sprung element (11) with a portion (14A) of the insert portion (4) or housing (7) on which it is located and movement in the other rotational direction of the sprung element (11) relative to the insert portion (4) or housing (7) on which it is located being prevented or limited by abutment of the other end of the sprung element (11) with a different portion (14A) of the insert portion (4) or housing (7) on which it is located.

11. A connector as claimed in Claim 10 in which the sprung element (11) is held in place by being located in a cavity (12) defined between the series of teeth, circumferentially spaced portions (14A) on the insert portion (4) or housing (7) in which it is located and axially spaced portions (14,15) on either side of the sprung element (11).