GB2294817A

GB2294817A - Electrical terminal and connector assembly

Info

Publication number: GB2294817A
Application number: GB9522057A
Authority: GB
Inventors: Bruce Sidney Coolbear
Original assignee: Whitaker LLC
Current assignee: Whitaker LLC
Priority date: 1994-11-01
Filing date: 1995-10-27
Publication date: 1996-05-08
Anticipated expiration: 2015-10-27
Also published as: GB2294817B; GB9522057D0

Abstract

An electrical connector assembly 2 comprises an insulating housing 4 defining a cavity 68 and an electrical terminal 6 mounted in the cavity. The terminal includes an anvil plate 14 secured against one wall 72 of the cavity, and a contact spring 16 connected to the anvil plate by a bight 18, 26 proximate to an opposite wall 70 of the cavity. Each contact spring finger 32 has an abutment section 36 extending forwardly at a first obtuse angle from the bight 18, 26 and a wire core gripping section 38 with free end 40 extending from the abutment section 36 at a second obtuse angle with respect to the abutment section 36 towards the anvil plate. When an end portion E of a wire core is forced between the free end 40 and the anvil plate 14 the abutment portion 36 is driven against an abutment 70 on the opposite wall 70 of the cavity 56 whereby a rear corner of the free end 40 bites into the core end portion E at an optimum angle to ensure the retention of the core end portion E in the terminal 6. The spring fingers can be relatively weak springs so that the contact spring 16 can be dimensioned for reception in a relatively small cavity. <IMAGE>

Description

AN ELECTRICAL CONNECTOR ASSEMBLY AND AN ELECTRICAL TERMINAL THEREFOR This invention relates to an electrical connector assembly and to an electrical terminal therefor. The invention concerns, in particular, an electrical connector assembly of the type which comprises an insulating housing containing an electrical terminal into which the bared end portion of the core of an insulating wire can be forced so as to be firmly gripped by the terminal, no skill, therefore being required in order to connect the wire core to the terminal.

There is disclosed, for example, in GB-A-2251738 such a connector assembly in which the terminal comprises an anvil in the form of a flat plate at one end of a frame of the terminal, and a rectilinear spring finger supported by the other end of the frame. A wire core can be forced between a free end of the spring finger and the anvil so that a corner of the free end bites into the wire core thereby preventing withdrawal of the wire core from the terminal. A contact tail projects from the frame for insertion in a hole in a printed circuit board. A similar connector assembly is disclosed in US 4,978,315. In this known assembly, a rectilinear spring finger extends from a bight connected to a flat arm of the terminal, which arm lies against a flat internal wall of the housing of the assembly.The flat wall is opposite to a further flat internal wall of the housing against which the anvil of the terminal lies. GB-A-2204748 discloses an electrical terminal in which a rectilinear spring finger extends from either end of a flat plate which is engaged against one wall of a metal frame of the terminal. A corner of a free end of each spring finger engages an opposite wall of the metal frame. A wire core can be inserted from each end of the metal frame so as to be forced between a respective one of the spring fingers and said opposite wall of the frame.

In such known assemblies it is essential for the secure retention of the wire core in the terminal that the, or each, spring finger should be stiffly resilient.

The terminal should, therefore, be of relatively large dimensions. Also the necessary stiffness of the spring finger requires the wire core insertion force to be correspondingly high throughout wire core insertion.

The present invention is intended to provide an electrical connector assembly of the type mentioned above, in which the size of the terminal is reduced thereby effecting a saving in the housing dimensions and thus a saving in the housing material. The invention is, therefore, especially applicable to the case where, as is sometimes required, the terminal is to receive a plurality of wire cores in side-by-side relationship.

According to one aspect of the invention, an electrical connector assembly comprises an insulating housing defining a cavity, an electrical terminal mounted in the cavity and including an anvil on one wall of the cavity, a mating portion exposed for mating with a complimentary mating member, and a contact spring comprising at least one spring finger connected to the anvil at a position proximate to an opposite wall of the cavity by way of a rearward bight, the or each spring finger having an abutment section extending forwardly and being inclined towards the anvil, and a wire core gripping section extending from the abutment section at an obtuse angle with respect thereto in a direction towards the anvil and having a free end proximate to the anvil, an abutment on said opposite wall of the cavity projecting towards the abutment section for engaging it when a wire core is forced in a forward direction between the free end of the core gripping section and the anvil so that the abutment section is moved towards the abutment; whereby a corner of the free end of the core gripping section is urged against the wire core to grip it.

By virtue of the back up provided by the abutment on the opposite wall of the cavity, the force with which the corner of the core gripping section is urged against the wire core is augmented, so that the, or each, spring finger can be a relatively weak spring and, therefore, of relatively small dimensions. Also, the wire core insertion force is low until the abutment section engages the abutment. At the same time, the obtuse angle at which the core gripping section extends from the abutment section can readily be so determined that the corner of the free end of the core gripping section makes an optimum angle, for example, of 300 with respect to the wire core when it is urged thereagainst.

Preferably the abutment section and the core gripping section are rectilinear, the abutment section being angled by about 260 with respect to the anvil and the core gripping section being angled by about 600 with respect to the anvil. The length of the abutment section may be 2.3 times the length of the core gripping section.

According to a further aspect of the invention, a stamped and formed electrical terminal for gripping a wire core, comprises an anvil plate and a contact spring connected to a rear edge of the anvil plate and extending thereover towards a forward end of the anvil plate, the contact spring comprising at least one spring finger located above the anvil plate, and having a first rectilinear section extending obliquely towards the forward end of the anvil plate at a first angle and a second rectilinear section, which is substantially shorter than the first section, extending from the first section towards the anvil plate at a second angle which is substantially greater than the first angle, the second section having a wire core gripping flat free end proximate to the anvil plate.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is an exploded isometric view of an electrical pin connector assembly; Figures 2 and 3 are enlarged isometric views of an electrical pin terminal of the assembly; Figures 4 and 5 are an enlarged front end view and an enlarged rear end view, respectively, of the pin terminal; Figure 6 is an underplan view of the pin terminal; Figure 7 is an enlarged side view of the pin terminal with part removed; Figure 8 is an enlarged end view of an insulating housing of the assembly showing the housing mounted to a panel which is shown in section; Figure 9 is an enlarged side view of the housing; Figure 10 is an enlarged plan view of the housing showing a back plate and wires assembled thereto; ; Figure 11 is a fragmentary sectional view of the connector assembly showing a pin terminal positioned in the housing and a wire positioned for insertion into the housing; Figure 12 is a similar view to that of Figure 11 but showing the wire connected to the pin terminal; Figure 13 is an exploded isometric view of an electrical socket terminal assembly for mating with the pin terminal assembly of Figures 1 to 12; Figure 14 is a side view, partly in section, of a socket terminal of the socket connector assembly; and Figure 15 is an isometric view of the socket terminal.

As shown in Figure 1, an electrical pin terminal assembly 2, comprises an insulating housing 4, electrical pin terminal 6 for connection to bared end portions E of the electrically conductive cores C of insulated electrical wires W1, and an insulating back plate 8.

As best seen in Figures 2 to 7, each terminal 6, which has been stamped and formed from a single piece of sheet metal stock, comprises a rearward wire connecting portion 10, and a forward mating portion in the form of a circular cross section, rolled up pin 12. The wire connecting portion 10 comprises an anvil in the form of a flat base plate 14 having outer edge portions 15 which lie laterally beyond the pin 12 on each side thereof, and a contact spring 16 connected to the rear edge 17 of the base plate 14 by way of a bight 18, centrally of the edge 17. The base plate 14 has forward edges 19 on each side of the pin 12. The bight 18 is substantially narrower than the contact spring 16 and the base plate 14, to provide a wire core receiving opening 20 on each side of the bight 18.Each opening 20 is defined by the edge 17 of the plate 14, an edge 22 of the contact spring 16 projecting laterally from the bight 18 and a lateral edge 24 of the bight 18, as best seen in Figure 5. The contact spring 16 comprises a bight 26 which extends from the bight 18 smoothly arcuately to its junction with a flat roof portion 28 of the contact spring 16, which portion is parallel with the base 14. From the forward edge 30 of the roof portion 28 there extends a pair of wire core gripping spring fingers 32 spaced laterally of the edge 30 and projecting forwardly of the terminal 6.As best seen in Figure 7, each finger 32 has a rear pivot section 34 extending from the edge 30 and being inclined with respect to the base plate 14 by an angle of about 100, a rectilinear intermediate abutment section 36 extending obliquely from the pivot section 34 and being inclined by an angle of about 260 with respect to the base plate 14, and a forward, free ended, wire core gripping rectilinear section 38 extending from the section 36 at an obtuse angle with respect thereto and being inclined at about an angle of 600 with respect to the plate 14. The section 38 has a flat free end 40 which is perpendicular to the plane of the section 38 and is proximate to the base plate 14, but is spaced therefrom. The radii of the bights 18 and 26 are substantially equal.The length of the section 36 is about 3.2 times the length of the section 34 and about 2.3 times the length of the section 38.

The pin 12 was rolled up during a progressive die forming operation from a part of the blank from which the terminal was formed, which part extended from the base plate 14. As indicated in Figure 6, a strip of terminals 6 connected in side by side strip fashion by slugs 42 (shown in broken lines) of the sheet metal stock from which the terminals 6 were formed, was produced by a die forming operation to provide the terminals 6. The pin 12 has a forwardly tapered ramp 43 towards its free end.

The housing 4 will now be described with particular reference to Figures 2 and 8 to 11. The housing 4 has a terminal receiving face 44, a mating face 46 opposite thereto, opposite side walls 48 and opposite end walls 50.

The terminal receiving face 44 is surrounded by a skirt 52 having four latching openings 54 therethrough. The housing 4 defines two pairs of terminal receiving cavities 56, each pair opening at one end into the terminal receiving face 44 and debouching at its other end into a respective further cavity 58 in a hood 59. Each cavity 58 opens into the mating face 46. A latching opening 60 in each side wall 48 each communicates with a respective cavity 58. For latching the housing 4 into an opening in a mounting panel P (Figure 8) the side walls 48 have latch arms 62 and panel abutments 64, the end walls having panel receiving grooves 66. As best seen in Figures 1 and 11, each cavity 56, which is of generally rectangular cross section, has a first pair of opposite side walls 68 having base plate guide slots 69 with flared entry mouths 71.

Each guide slot 69 terminates in a forward stop shoulder 73. Each cavity 56 also has a second pair of opposite side walls 70 and 72, respectively. The wall 72 is flat, whilst the wall 70 has extending forwardly from the terminal receiving face 44, a relieved portion in the form of rabbet 74 from which extends forwardly a ramp 76 inclined forwardly towards the opposite wall 72. The ramp 76 defines an abutment edge 78 projecting towards the wall 72. The wall 70 has a portion 80 extending forwardly from the abutment edge 78 parallel to the wall 72. A pin guide ramp 82 adjoins the forward end of the wall 80.

The back plate 8 will now be described with particular reference to Figures 1, 10 and 11. The back plate 8 which is elongate and is of generally rectangular cross section comprises opposed projections 84 for reception in recesses 86 in the skirt 52 of the housing 4, and latch members 88 for latching engagement in the latching openings 54 in the skirt 52. The plate 8 has four pairs of wire receiving through holes 90, the holes 90 of each pair being spaced from each other transversely of the length of the plate 8. As best seen in Figure 11, each hole 90 has a flared wire guiding mouth 92 opening forwardly into insulation receiving section 94, which in turn opens into a core receiving section 96 of smaller cross section than the section 92. Sections 94 and 96 define an insulation abutment shoulder 98.

In order to prepare the connector assembly 2 for use, each terminal 6 is severed from the carrier strip 42 and is inserted into a respective cavity 56 of the housing 4 by way of its mating face 44, with the pin 12 leading so that as shown in Figure 11, the pin 12, the ramp 43 of which is guided by ramp 82 in the cavity 56, projects into the respective cavity 58. During the insertion of the terminal 6, the edge portions 15 of the base plate 14 enter the guide slots 69 of the walls 68 guided by the mouths 71 of the slots 69. The edge portions 15 slide along the slots 69 until the forward edges 19 of the edge portions 15 engage the stop shoulders 73. Thus in the fully inserted position of the terminal 6, the base plate 14 is secured flat against a cavity wall 72.The roof portion 28 of the contact spring 16 and the pivot sections 34 of the spring fingers 32 lie in the rabbet 74 with the abutment sections 36 of the fingers 32 spaced from the abutment edge 78 of the ramp 76.

When the terminals have been inserted into the cavities 56 as described above, the back plate 8 is latched into the skirt 52 so that the holes of each pair of holes 90 are aligned with respective wire core receiving openings 20 of a respective one of the terminals 6. The connector assembly 2 is now ready for shipment to the end user.

The end user assembles the wires W1 to the assembly 2 by inserting the stripped end portion E of each core C of each wire W1 through a respective one of the holes 90 of the back plate 8, whereby each core end portion E is passed through a respective core receiving opening 20 of a terminal 6 until the insulating jacket J of the wire W1, bottoms on a respective stop shoulder 98 as shown in Figure 12. During the insertion of each core end portion E, the core end portion E slides along the base plate 14 of the terminal 6 so that the free end of the core portion E engages against the inner surface of the core gripping section 38 of the respective spring finger 32 thereby displacing the finger 32 about the pivot section 34 thereof so that the abutment section 36 of the finger 32 moves towards, and engages against, the abutment edge 78 thereabove. When a core end portion E has thus been forced between the free end 40 of a section 38 of a finger 32 and the base plate 14, as shown in Figure 12, the inner corner of the flat free end 40 of the core gripping portion 38 of the finger 32 bites into the surface of the core end portion E.By virtue of the angle of attack of the section 38, the free end 40 makes an angle of about 30 degrees with respect to the longitudinal axis of the core end portion E. This angle is optimum to ensure that the wire W1 cannot be withdrawn from the terminal 6. Since the spring finger 32 is compressed between the cavity wall 70 and the core end portion E, said corner of the free end 40 is firmly pressed into a core end portion E despite the fact that the spring finger 32 is a relatively weak spring because there is no room in the housing for larger dimensioned contact springs. No skill on the part of the end user is required for connecting the wires to the terminals, since all that the end user need do in order to ensure effective connection is to insert the wires into the holes 90 until the jackets J bottom on the stop shoulders 98.Especially since the spring fingers 32 exert a relatively low spring force against the inserted core end portions, until the abutment sections 36 strike the abutment edges 78, the wire insertion force is correspondingly low for the greater part of the wire insertion time. The wire retention force is, however, high, relative to the stiffness of the spring fingers 32.

A socket connector assembly 100 for mating with the pin connector assembly 2 will now be described with reference to Figures 13 to 15, in which parts which are identical with corresponding parts described above with reference to Figures 1 to 12, bear the same reference numerals as those corresponding parts, but with the addition of a prime symbol. Said identical parts will not be further described here. Terminals 102 of the assembly 100 are identical with the terminals 6 excepting that instead of the pins 12 the terminals 102 have sockets 106 which have been rolled up in a manner similar to that described above reference to the pins 12. Each socket 106 has a flared pin guiding mouth 108.The housing 104 of the assembly 100 is identical with the housing 4 excepting that instead of the hood 59, the housing 104 has two forward projections 110 in each of which is a cavity 112 (indicated in broken lines) corresponding to a respective cavity 58 of the housing 4, for receiving two of the sockets 106. The projections 110 have mating faces 114 and external latch members 116.When the terminals 102 and the back plate 8' have been assembled to the housing 104 in the manner described above with reference to Figures 1 to 13, and wires W2 have been inserted through the holes 90' of the back plate 8' to connect the cores of the wires W2 to the wire connecting portions 10' of the terminals 102, the connector assemblies 2 and 100 can be mated by inserting the projections 110 of the housing 104 into respective cavities 58 of the housing 4, so that the pins 12 are mated with the sockets 106. The housings 4 and 104 are retained in mating relationship by the engagement of the latch members 116 in the latching openings 60 of the housing 4. Each pair of wires W1 is thereby connected to a corresponding pair of the wires W2.

The assemblies 2 and 100 are especially useful for industrial lighting installations, for example, where skilled labour is not available for connecting the wires to the terminals.

Claims

1. An electrical connector assembly comprising an insulating housing defining a cavity, and an electrical terminal mounted in the cavity and including an anvil on one wall of the cavity, a mating portion exposed for mating with complimentary mating member, and a contact spring comprising at least one spring finger connected to the anvil at a position proximate to an opposite wall of the cavity by way of a rearward bight, the, or each, spring finger having an abutment section extending forwardly and being inclined toward the anvil, and a wire core gripping section extending from the abutment section at an obtuse angle with respect thereto in a direction towards the anvil and having a free end proximate to the anvil, an abutment on said opposite wall of the cavity projecting towards the abutment section for engaging it when a wire core is forced in a forward direction between the free end of the core gripping section and the anvil so that the abutment section is moved towards the abutment; whereby a corner of said free end is urged against the wire core to grip it.

2. An assembly as claimed in claim 1, wherein the abutment section and the wire core gripping section are rectilinear.

3. An assembly as claimed in claim 1 or 2, wherein said obtuse angle is such that the free end of the core gripping section is angled by about 300 with respect to the wire core when said free end is urged thereagainst.

4. An assembly as claimed in claim 1, 2 or 3, wherein the abutment section is angled by about 260 with respect to the anvil, and said core gripping section is angled by about 60 with respect to the anvil.

5. An assembly as claimed in any one of the proceeding claims, wherein the abutment section is substantially longer than the core gripping section.

6. An assembly as claimed in any one of the proceeding claims, wherein the length of the abutment section is about 2.3 times the length of the core gripping section.

7. An assembly as claimed in any one of the proceeding claims, wherein the abutment section is connected to the bight by way of a pivot section about which the spring finger pivots as the wire core is forced between the free end of the core gripping section and the anvil.

8. An assembly as claimed in any one of the proceeding claims, wherein the anvil is a flat plate, the contact spring comprising a pair of said spring fingers, the bight being connected to one end of the anvil by way of a further bight, the bights and the anvil defining a pair of wire core receiving openings each aligned with the wire core gripping section of a respective one of the spring fingers, the mating portion of the terminal projecting from the forward end of the anvil towards a mating face of the housing.

9. An assembly as claimed in any one of the proceeding claims, wherein opposed side walls of the cavity, which are adjacent to said one wall and said opposite wall are each formed with a guide slot proximate to said one wall of the cavity, the guide slot having a guiding mouth opening into open end of the housing, the anvil having lateral edge portions each slideably received in a respective one of said guide slots, to locate the anvil against said one wall of the cavity, said lateral edge portions engaging stops limiting the insertion of the terminal into the cavity.

10. A stamped and formed electrical terminal for gripping a wire core, the terminal comprising an anvil plate, a contact spring connected to a rear edge of the anvil plate extending thereover towards a forward end of the anvil plate, the contact spring comprising at least one spring finger located above the anvil plate and having a first rectilinear section extending obliquely towards the forward end of the anvil plate at a first angle and a second rectilinear section which is substantially shorter than the first section extending from the first section towards the anvil plate at a second angle which is substantially greater than the first angle, the second section having a wire core gripping free end proximate to the anvil plate.

11. A terminal as claimed in claim 9, wherein the magnitude of the second angle is about 2.3 times that of the first angle, the length of the first section being about 2.3 times the length of the second section.

12. A terminal as claimed in claim 10 or 11, wherein the contact spring has first and second spring fingers spaced from each other in coplanar relationship, the anvil plate and the contact spring cooperating to define wire core receiving openings each aligned with the second section of a respective one of the spring fingers, a mating portion in the form of a pin or a socket being connected to the forward end of the anvil plate.

13. An electrical connector assembly substantially as hereinbefore described with reference to the accompanying drawings.

14. An electrical terminal substantially as hereinbefore described with reference to the accompanying drawings.