GB2091049A - Electrical connector - Google Patents

Abstract

An electrical connector (10) for receiving a printed circuit board (40) and for establishing connection between the board and wiring (28) includes a contact member (20), having contacts (44) for establishing connection to the printed circuit board (40), and includes contact retention tabs (30) for preventing tension applied to wires (28) from causing the contact member (30) from becoming separated from the connector body (12). Preferably, the contact retention tabs (30) become wedged into a side (34) of a barrier wall (16) when upward force is applied, but the force causing the tabs to become wedged may also be supplied by a clamping plate (24) for clampingly retaining the wire (28), or by the wire (28) itself. <IMAGE>

Description

SPECIFICATION Electrical connector with contact retention tabs This invention is in the field of electrical connectors. In particular, this application relates to a structure for a contact of an electrical connector which is retained in a connector body by means which are not subject to elastic cold flow of the material of the connector body.

In many practical applications for electrical connectors, an electrical conductor such as a wire is first fastened to the connector, and the wire is then positioned in a desired path, and may be combined with other such conductors or wires in a cable or harness, the cable or harness then being bent into position to follow a desired path. In the process of positioning a routing wire and wire harnesses, considerable tension may be placed on the individual wires, particularly if much force is needed to bend or stretch the wire or harness into position, either for causing it to follow a desired path, or for aligning it to connect it with some other device.The tension applied to such wire and conductors during such manual operations not only tends to damage contacts of the electrical connector, either by bending them, or by causing them to become physically separated from the connector body, but also, the remaining stresses in the wire cause slow plastic cold flow of the material of the connector body from around the embedded nut conventionally used to retain the contact and wire, causing at least partial separation of the contact from the connector body.

The illustrated embodiment of the invention is an electrical connector for receiving a printed circuit board, and allowing connection between the printed circuit board and other devices. Connectors such as illustrated are often used in the field of machine tool controls, where the printed circuit board contains the machine control logic and devices for interfacing between the machine control logic and the controlled devices, such as power relays and contactors, and solenoid valves. Therefore, both due to the current required by such devices and due to the need to maintain consistency in wire sizes, contact fastening means, and wire insulation resistant to heat and oil throughout a machine tool, comparatively large and therefore stiff wires must be connected to the printed circuit board.More than one such a wire may need to be connected to a given contact, and the electrical connection to the printed circuit board should be provided with fastening means which operate in the same general fashion as fastening means provided on conventional power relays, contactors, and valve solenoids.

In accordance with general practice in such connectors, a plastic connector body is molded around a nut, a contact member is placed on top of the nut, a wire retaining plate is placed on top of the contact member, and a screw is threaded into the nut, retaining the contact, the plate, and a wire end placed between the contact and the plate.

The comparatively large and stiff wires connected to the printed circuit board connector and then bundled together into a cable harness, and placed in a cable trough. The contacts in such electrical connectors are often bent and damaged by forces applied to such wires in connecting them, or bending them together into a cable harness, and bending the harness to follow a predetermined path in the cable trough. The damage is either a pulling out of the nut from its encapsulating material, a bending ofthe contact itself, or residual stresses in the wires which cause the cold flow of plastic material from around the embedded nut, freeing the contact from the connector body.

While the instant invention is, of course, not limited in application to such an electrical connector as is illustrated, the problem of bending and damage to electrical contacts, and of separation of contacts from a connector body due to cold flow, may be solved by providing tabs on the electrical contacts which engage barrier strips of the connector body separating the electrical connectors, which avoid the necessity for an embedded nut or other means subject to plastic cold flow to retain the contact.

Therefore, it is a primary object of the invention to provide a structure for a contact for an electrical connector which retains the connector to a connector body. It is a feature of the invention that tabs are provided on the contact which engage sides of barrier strips between contacts of the connector, to retain the contact in the connector body. It is an advantage of the invention that such a retention means may be provided which is not subject failure due to significant plastic cold flow of the connector body, without interfering with the connection of a wire to the contact, and without additional parts.

FIG. is a partial perspective view of an electrical connector according to the invention.

FIG. 2 is a side sectional view taken along line 2-2 in FIG. 1.

FIG. 3 is a perspective view of a contact member as shown in FIG. 2.

FIG. 4 is a side sectional view of an electrical connector as shown in FIG. 1, having a contact which is provided with a wire wrap pin.

FIG. 5 is a perspective view of the contact shown in FIG. 4.

FIG. 1 shows a partial perspective view of an electrical connector according to the invention. It should be noted that, while only fou r sections of such a connector are illustrated, as many sections as desired may be provided. Also, for purposes of clarity and simplicity, repetition of similar elements in the illustration has been avoided wherever possible.

As shown in FIG. la a connector 10 having a body 12 is provided with conventional mounting provisions 14, for attaching the connector 10 to a support surface. Connector body 12 also includes a plurality of conventional barrier walls 16, defining a plurality of channels 18, each channel 18 containing, in the preferred embodiment, a contact member 20, a screw member 22, and a clamping plate member 24, for retaining an end 26 of a wire 28 to contact member 20. Each contact member 20 is provided with two retention tabs 30. As shown in the orientation of FIG. 1, tabs 30 are bent upwardly from the body 32 of contact member 20, and have a lateral extent greater than that of body 32 of contact member 20.It should be noted that the invention is not limited to being mounted in the position shown, and that references to direction are for clarity of explanation only, and are not intended as limits on the scope of the invention. As will be apparent when a retension tab 30 is forced towards body 32 of contact member 20, tab 30 will be become wedged into a side 34 of a barrier wall 16, retaining contact member 20 in connector body 12. Therefore, retention tabs 30 will become wedged in barrier walls 16 whenever an outward force is applied to contact member 20.

As shown in FIG. 2, tabs 30 then retain one end of a contact member 20 in connector body 12, the opposite end of connector body 20, in the illustrated embodiment of the invention, being provided with resilient latching members 36, which engage shoulder 38 of connector body 12. As will be apparent, tabs such as tabs 30 could be used for advantage at more than one location, replacing member 36, if desired. The primary function of latching members 36 and shoulders 38 is to retain contact member 20 against being pushed from connector body 12 by insertion of a printed circuit board 40 into pocket 42 to make contact with wiping contacts 44 of contact member 20, printed circuit board 40 being resilient retained between contacts 44 and wall portion 45 of connector body 12.As also shown in FIG. 2, connector body 12 includes a pocket 46 for receiving a threaded portion 48 of screw member 22, and a pocket 50 forslidably retaining a nut 52 from rotation. As shown, screw 22 threadably engages nut 52. Rotation of screw 22 will force clamping plate member 24 onto wire end 26, clampingly retaining wire end 26 between clamping plate member 24 and body 32 of contact member 20. Screw 22 passes through an aperture 54 in body 32 of contact member 20, to engage nut 52. Nut 52, being slidably restained from rotation rather than embedded in connector body 12, is not relied on to keep contact member 20 assembled to connector body 12. Therefore, continued strain on contact member 20 and screw member 22 cannot cause cold flow of the material of connector body 12 from around an embedded nut, allowing contact member 20 to bend or become separated from connector body 12.

As will be apparent, in assembling such a connector 10, a nut 52 is first placed in a pocket 50, and a contact member 20 is disposed in a channel 18 with wiping contacts 44 disposed in pocket 42, and latched by latching members 36 against shoulder 38.

A clamping plate member 24 is disposed about threaded portion 48 of screw 22, and screw 22 is passed through aperture 54 and threadably inserted into nut 52. Thus, nut 52 serves no contact member retaining function, the contact being retained by retention tabs 30 and latching members 36. Thereafter, in use, a wire end 26 may be placed between clamping plate member 24 and body 32 of contact member 20, and screw 22 is further rotated to clampingly retain wire end 26. As shown, clamping member 24 may be provided with one or more indentations 56, forming protrusions 58 on a surface 60 of clamping plate member 24 adjacent body 32 of contact member 20. Such protrusions have been found to be useful in retaining a wire such as wire 26 to a contact member 20, but are not necessary to practice the invention.

It will be further obvious that retention tabs 30 may be positioned upon body 32 of contact member 20, so as to be actuated directly by clamping plate member 24, rather than by upward strain on contact member 20. This positioning, while useful to produce the advantages of the invention, is undesirable in the illustrated embodiment, for the reason that the space between threaded portion 48 of screw member 22 and side 34 of barrier wall 16 is adequate to receive a single wire end 26 of the maximum expected diameter. Placing retention tabs according to the invention where they would be actuated directly by clamping plate member 24 may interfere with the insertion of a wire end such as wire end 26 between body 32 of contact member 20 and clamping plate member 24. Also, retention tabs 30 may be positioned so as to be actuated by the act of connecting a wire end 26.A wire end 26, being relatively rigid may bear upon a retention tab 30 located sufficiently close to clamping plate member 24, and act to force a retention tab 30 into a barrier 16.

FIG. 4 shows an alternate embodiment of the invention, differing only in that contact member 20 is provided with a wire wrap pin 62. As will be apparent, it is often desirable to connect both heavy gauge wire for control purposes and much smaller gauge wire for logic purposes to the same electrical connector and contact member. Provisions of these two types of fastening means is useful, for instance, in providing an external visual indication that some logic function is occurring, or providing a logic feedback signal verifying that some intended control output has been actuated, or for providing logic level interconnection between logic elements on different printed circuit boards 40.

As shown in FIG. 5, a contact member 20a is identical to contact member 20, having body 32, retention tabs 30, latching members 36, wiping contacts 44, and an aperture 56, with the addition of a tapered portion 64 joining body 32 of contact member 20a and wire wrap pin 62. Tapered portion 64 is provided both for rigidity, and for ease in insertion of contact member 20a in channel 18, with wire wrap pin 62 passing through aperture 66 in connector body 12.

As will be apparent, it will be obvious to one skilled in the art that numerous modifications and variations of the disclosed embodiment of the invention may be made without departing from the spirit and scope of the invention.

Claims (5)

1. An electrical connector, comprising: a connector block body having a plurity of barrier walls protruding therefrom and forming a plurality of channels therebetween.

at least one contact member disposed in one said channel and having a first portion attached to said connector block body adjacent a first end of said channel; said contact member including clamping means for clampingly retaining a portion of a wire end against a surface of said contact member; said clamping means including a screw member, a clamping plate member and a nut member; said contact member defining a first aperture therethrough intermediate said first portion and said second portion; said connector block body defining a recess in at least one said channel adapted to slideably receive said nut member and restrain said nut member from rotation;; said screw member having a threaded shaft portion disposed through said first aperture and threadably engaging said nut member, said nut being disposed in said recess, said clamping plate member being disposed about said threaded shaft portion between a head of said screw and said contact member, and adapted to clampingly retain said portion of said wire end between said clamping plate member and said contact member; said second portion of said contact member including retention tab means for engaging said barrier walls adjacent one said channel to retain said second portion of said contact member to said connector block body.

2. An electrical connector according to claim 1, wherein, said connector block body defines a plurality of second apertures, each said aperture being formed therethrough adjacent a first end of one said channel; said first portion of said contact member including wiping contact means adapted to protrude through one said second aperture and adapted to cooperate with a wall of said body to make electrical contact with a printed circuit board inserted between said wiping contact means and said wall; said first portion having latching arms adapted to cooperate with a shoulder of said first aperture, said first aperture having said shoulder formed in said body adjacent said first end of said channel for latchably attaching said first portion to said connector body block.

3. an electrical connector according to claim 2 wherein; said connector block body defines a plurality of third apertures therethrough, each said aperture being defined by said body adjacent said second end of one said channel, said contact number including a third portion substantially perpendicular to said second portion and protruding through said third aperture, a port of said third portion being a wire wrap pin protruding from said third aperture.

4. An electrical connector substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

5. An electrical connector substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.