WO1982000547A1

WO1982000547A1 - One-piece electrical push-in type connector

Info

Publication number: WO1982000547A1
Application number: PCT/US1981/001003
Authority: WO
Inventors: Mining & Mfg Co Minnesota; B Wenderoth
Original assignee: Minnesota Mining & Mfg
Priority date: 1980-08-04
Filing date: 1981-07-27
Publication date: 1982-02-18
Also published as: ES8204885A1; ES504494A0; BR8108730A; JPS57501152A; EP0046042A1; KR830006836A

Abstract

A one-piece electrical push-in type connector (12) for joining conductors used for general power supply currents. The connector comprises a connector manufactured from a single piece of sheet metal of uniform thickness having a plurality of push-in contact locations each formed from a unitary cut in the metal where electrical conductors may be pushed in in a predetermined direction as particularly determined by a housing (15) receiving the connector. The unitary cut provides two opposing contact portions at each push-in contact location, of which one contact portion is a spring tongue (23) which, with a conductor (21) being inserted, extends obliquely and abuts the conductor at an acute angle to retain the conductor.

Description

^Qne-Piece Electrical Push-In Type Connector

Technical Field

The invention relates to a one-piece electrical push-in type connector which is adapted to be manufactured from a unitary cut of sheet metal of uniform thickness and is particularly suited for general power supply currents. In one aspect, the connector comprises a plurality of push-in clamping locations where electrical conductors may be pushed-in in a predetermined direction as particularly determined by a housing receiving the connector, and safely contacted. Two opposing contact portions are provided at each push-in clamping location, of which the one contact portion is designed as a spring tongue which, with a conductor being inserted and viewed in the push-in direction, extends obliquely from its base portion towards the conductor and abuts the conductor at an acute pitch angle.

Background Art

One-piece push-in type connectors of the kind described which are to be used particularly for general alternating supply line current, for instance household supply current of 110 or 220 volts, do not always ensure a sufficient contact force and sufficiently low transition resistances for general power supply operation for a sufficient length of- time under the varying load and environmental conditions encountered. In practice, therefore, most push-in connectors are formed of several parts wherein the contact portion is manufactured from a sufficiently thick and well-conducting material to provide the necessary conductance, and the spring tongue portion is formed from a thin and less well conducting spring material to maintain electrical contact with the contact portion. The manufacture of multipart push-in connectors of that kind is substantially more expensive than with one-piece connectors which can be made from a unitary cut

OMPI^' of sheet metal of uniform thickness by stamping and bending. However, the extra expense was tolerated because it was believed that only in this way could the desired features be amalgamated satisfactorily. 5 Insofar as one-piece push-in connectors for general supply current, for instance household power distribution of 110 or 220 volts alterating voltage, had become known, they -represent unsatisfactory compromises between the requirement to keep the thickness of the sheet

1 metal cut so large that there is a strength and dimensional stability present at the push-in clamping locations to maintain sufficient contact and clamping forces, and to keep the sheet metal thin enough that the spring tongues are elastically deformable within a range

15 of deflection necessary for the function of the push-in connector, without facing the danger of premature spring fatigue or even permanent deformation. When meeting the first-mentioned requirement of good dimensional stability by selecting a sufficiently thick sheet material, the

20 spring tongues are, unless they shall not be impracticably long, so stiff that they are permanently deformed upon the pushing-in of a conductor, so that a multiple use of the connector is impossible (USA Letters Patent No. 4,084,876). When meeting the second-mentioned requirement

25 for sufficiently large elastic deformability of selecting a correspondingly thin sheet material, the unitary push-in connector, has too little dimensional stability as a whole, and additional measures are necessary to back-up the contact forces. Examples of these additional measures

30. include installation in an exactly surrounding and a sufficiently strong housing, reinforcing by integrally shaped holding webs which extend over other portions, or using additional rigid frame bodies (German publication No. 1,285,589). Measures of that kind require an

35 additional expense in the manufacture, and a multipart construction. Moreover, the known reusable one-piece push-in connectors (German publication No. 1,285,589) have the disadvantage that a conductor once clamped can be removed again only after lifting the spring tongue off. Without 5 that manipulation, an effort to again withdraw the once pushed-in connector, will increase the angle between the spring tongue and the conductor and concurrently buckle u and permanently deform the spring tongue so that the connector will no longer be suitable for reuse.

10 The present invention starts from the object to provide a push-in connector which can be manufactured in simple manner from a one-piece cut of sheet metal of uniform thickness, which is suitable for multiple uses or conductor sizes, and which can be readily designed so that

15 for loosening an inserted conductor, no manipulations are necessary at the push-in connector.

Disclosure of the Invention

In the push-in connector according to the present invention, the opposing contact portions extend 0 from the closed frame surrounding the contact portions; thus, just the base portion of the spring tongue with which the spring tongue merges into the remaining part of the push-in connector, is supported with a high strength and dimensional stability. Therefore, the danger is 5 greatly reduced that upon pulling at an inserted conductor, the spring tongue is buckled up and permanently deformed; thus, the resistivity against unintentional withdrawing is increased, and yet a configuration can be obtained by using sufficiently small pitch angles with Q which it is ensured with a high degree of safety that an inserted conductor can be again withdrawn by pulling and simultaneous turning, without the danger existing to make thereby the push-in connector unsuited for a reuse because of a permanent deformation of the contact portions, particularly the spring tongue. Accordingly, an advantageous further development of the invention is characterized in that the distance between the contact portions is dimensioned so that, within a predetermined range of conductor cross-sectional sizes, a pitch angle is obtained at which an inserted conductor can be withdrawn again by pulling and simultaneous turning without permanently deforming the connector.

Multipart push-in connectors are described as having a sufficiently flat pitch of the spring tongue at the inserted connector, to permit the inserted conductor to be again withdrawn by pulling and simultaneous turning without causing bulging and permanent deformation of the spring tongue (German disclosure letter 2,317,040); however, that concept concerns embodiments in which the spring tongues are separate structural parts riveted or screwed to a thick and rigid plate which forms the other contact portion; this results in a very rigid anchoring of the base portions of the spring tongues over a large area so that the spring tongues are resistive against bulging. With a one-piece push-in connector in which the spring tongues are simply portions of a piece of sheet metal of uniform thickness, a comparably rigid anchoring of the spring tongues did not appear feasible.

In most cases and particularly if the push-in connector is to be designed only for a definite conductor cross-section or a narrowly limited range of conductor cross-sections, the range of the elastic deformability of the spring tongue will be sufficiently large to compensate for tolerances of the push-in direction and the conductor cross-section. Then, it is to the purpose to design the other contact portion as a support portion as strong as possible at a section of the inner border and thus arrive at a high total strength against the spring and contact forces applied; this embodiment therefore will be preferable in general. In the case of more rigid requirements with respect to the applicable range of conductor cross-sections, it will, however, be to the purpose to design both contact portions as spring tongues so that the elastic deformabilities of the two spring tongues are additive. It should be further mentioned tha with the push-in connector according to the invention, the contact portions, more precisely the areas thereof which abut at the inserted conductor, are located oppositely and adjacently already in the sheet metal cμt so that the sheet metal cut and the conductor formed therefrom can be designed with very small dimensions and thus a high resistivity against undesirable deformation. This is made possible by the feature that the contact portions are limited by portions of one and the same closed-in-itself inner frame border.

It goes without saying that in other respects, the shape and the dimensions of the frame can be selected at will within wide limits, depending on the particular requirements with respect to structure and strength. However, since portions located far' outwards do not contribute much to the total strength of the push-in connector, it will generally be possible to obtain the essential advantages of the push-in connector according to the invention already with a relatively narrow frame, i.e. with small dimensions.

Brief Description of the Drawings

The invention will be described in the following by way of examples in connection with the drawings.

Figure 1 is a diagrammatic (partly broken away view) of a push-in connector taken in the direction of the arrow A of Figure 2;

Figure 2 is a diagrammatic sectional view according to the line 2-2 of Figure 1;

Figure 3 is a diagrammatic plan view of a connector element showing another embodiment;

Figure 4 is a diagrammatic sectional view of the connector element of Figure 3 with the housing parts added; Figure 5 is a transverse sectional view of another connector embodiment taken along the line 5-5 of Figure 6;

Figure 6 is a diagrammatic sectional view along the line 6-6 of Figure 5;

Figure 7 is a transverse diagrammatic sectional view of another embodiment taken along the line 7-7 of Figure 8;

Figure 8 is a diagrammatic sectional view taken along the line 8-8 of Fig. 7;

Figure 9 is a transverse diagrammatic sectional view of a further embodiment of the present invention taken along the line 9-9 of Fig. 10;

Figure 10 is a diagrammatic sectional view taken along the line 10-10 of Fig. 9.

Detailed Description (Including Best Mode)

In the drawings the connectors are illustrated diagrammatically; particularly, the thickness of the sheet metal cuts has been illustrated enlarged in the interest of clarity.

Figs. 1 and 2 illustrate a particularly simple one-piece push-in connector 11 which consists of a unitary sheet metal contact element 12 of uniform thickness. In the push-in connector, a plurality, in this case four, push-in clamping locations are provided where electrical conductors may be pushed in and safely contacted.

The push-in direction is determined by a housing 15, more precisely by push-in and guiding openings 16, 17, 18 and 19 provided therein for receiving the base conductors. Of course, an insulation 20, if any, has been removed sufficiently far from the conductor 21 ends to permit the conductor to be inserted. The push-in openings each have an entrance section 16a, the cross-section of which corresponds to that of the conductor 21 including the insulation 20. The conductor is freed from the insulation 20 so far that the condition illustrated in

"BϋlE3_

OMPI broken lines Fig. 2 will result upon insertion, in which the insulation 20 extends into the entrance section 18a. In this manner, complete safety covering is obtained. At each push-in clamping location the one contact portion at 5 each clamping location is designed as a spring tongue 23, 24, 25 and 26 which furnishes the necessary contact force. In the embodiment illustrated, the other contact portion is formed by a common support portion 30 having a marginal portion 31 adjacent the free border of the support portion 10 30 which is bent to facilitate a uniform bending of the marginal portion which forms an axial support surface and a short current path between conductors in the connector. The contact support portion 30 has a strength and rigidity as high as possible. It is located opposite the free end 15 of the spring tongues 23, 24, 25 and 26 and at a distance so that the conductor can be pushed into the insertion openings 16, 17, 18 and 19 only while pushing away the spring tongue and thus lifting the free edge of a spring tongue engaging the conductor 21 a distance equal to about ^0 half the diameter of the conductor 21 and through an angle as will be described. Fig. 2 illustrates in broken lines that as the spring tongue firmly abuts the conductor 21 under spring tension, and extends, as viewed in the push-in direction, obliquely towards the conductor 21, it 25 engages the conductor at an acute pitch angle 32. Due to the acute pitch angle, the effect of a barb is obtained and that with an effort to again withdraw the conductor once inserted, opposite to the push-in direction, the spring tongue digs into the conductor 21 so that it is 3. forcibly entrained in the withdrawing direction. It will be appreciated that this retracting force may result in the upwards bulging and permanent deformation of the spring tongue. This deformation is less likely the more strongly the spring tongue is anchored at its base portion 5 in the remainder of the push-in connector 11, and the smaller the pitch angle chosen. However, a very small pitch angle can be attained only with a relatively large

OMPI" deflection of the spring tongue if the necessary tolerances are met. It is very difficult, if not even impossible, to achieve the necessary high contact forces in common with a large range of elastic deformability of 5 the spring tongue, with the relatively short lengths of the spring tongues achievable with a single cut in a single piece of sheet metal. In the construction here described, multiple spring tongues and the support are all formed by a common cut in the contact element 12. When 10 separate cuts for each tongue and support are made as illustrated in Figs. 5 and 6 the element is not as compact but when the push-in clamping or contact locations are formed by a single endless cut in the sheet metal and surrounded by a frame which is closed in itself, the base

15 portions of the spring tongue are anchored so strongly that a range of practicable acute pitch angles can be readily found in which sufficiently high contact forces are produced and the conductor is securely held in place but yet can be again removed by pulling and turning

2Q without there being a danger that the spring tongue is bulged outwards and permanently deformed. Essentially, the magnitude of the pitch angle 31 depends upon the distance between the areas of the contact portions designed for engagement at the conductor 21. That

25 distance has to be dimensioned so that for a predetermined range of conductor cross-sections, a relatively small pitch angle 31 of e.g. 30 to 35 degrees is obtained upon insertion of the conductor 21 in the given push-in direction (relative to the push-in connector 11) . The

30. exact value depends upon the magnitude, the kind of material, and the thickness of the sheet metal cut, and upon the other constructional features of the push-in connector. For an embodiment once selected, the optimum pitch angle can be easily evaluated by a few simple 5 experiments. Preferably, the pitch angle 31 is selected so that, with the conductor materials used, the inserted conductor 21 can be again withdrawn by pulling oppositely to the push-in direction and simultaneous turning.

In the connector of this invention, the number of the push-in clamping locations limited by a common interior border depends upon the requirements with respec to contact force and current load in the particular case of application. With the same structural features in other respects, the rigidity is somewhat smaller than with embodiments having only a single spring tongue per cutout. In any case, however, additional rigidifying measures can be applied. For instance, in this embodiment, Figs. 1 and 2, the marginal portion 31 adjacent to the free border of the support portion 30 is bent off. In order to facilitate a uniform bending of such a marginal portion forming the short support surface, the marginal portion is separated by short cuts 33 and 34 at the ends of its length taken transverse of the spring tongues.

For further rigidifying, bending lines and/or beads and/or embossments may be provided. In this embodiment, the contact element 12 is further rigidified by bending lines 35, 36 and beads 37, 38. The beads are provided so that they may also serve as an installation aid; according to Fig. 2, the contact element 12 has its beads snapped into corresponding grooves of a housing 15. Of the housing, only the base portion 15 is illustrated; which is provided with the push-in openings 16, 17, 18, 19. The contact element 12 has a further bent portion to form an abutment 40 which is engaged by the end on a conductor 21 inserted in the connecter 11. A lid (not shown) may be snapped over the open end and have its border received in grooves 44 and 45. The lid 48 consists of a sufficiently yieldable material, e.g. polyethylene to permit insertion but may be rigid enough to serve as an abutment.

In the embodiment according to Figs. 1 and 2 the starting angle 41 of the spring tongues is obtained in that the spring tongues are bent out, by the starting angle 41, from a surrounding area of the contact element

OMPΪ 12, in this case the central portion between the marginal portions bent off at lines 35 and 36. The tongues are then bent, upon insertion of the conductors 21 to the pitch angle 32. The described starting position of the spring tongue oblique with respect to the push-in direction 12, results in the further advantage that it can easily be achieved, by suitably selecting the starting angle 41, that the contact zones between the inserted conductor 21 and the contact portions (support portion 31 and the spring tongue 23) are disposed in a plane 50 oblique to the conductor 21 and the clamping forces are not as great as when both the support and tongue are inclined to the conductor 21. In contrast thereto, the conductor 21 is subjected to a bending force if a distance exists between the contact zones in the direction of the conductor (the push-in direction); such bending force normally is undesirable, at least already because it does not contribute to the contact force.

A particularly suitable spring material for the contact element 12 is spring brass, particularly a copper-beryllium-alloy having, for instance, about 2 to 7% by weight beryllium. Also laminates of steel and non-ferrous metal are very suitable because they make possible, depending upon the composition selected, to meet even very different requirements in respect of the spring properties.

The push-in connector may additionally comprise at least one connecting or contacting means of conventional design, for instance a screw connection, a soldering tag, and the like. Thereby, the push-in connector can be connected more easily to already present installations, or to an electricity supply line of larger cross-section.

The electrical contact may be even improved, and its load capability increased, if in at least one contact portion (in the case illustrated, of the spring tongue and/or the support portion), a profile is provided, e.g. a recess or shaping, which is adapted to the cross-sectiona shape of the conductor to be inserted. In the embodiment according to Figs. 1 and 2, the spring tongue 23 has such a recess 51 which in the case illustrated is adapted to the cross-sectional shape of the conductor 21. However, the recess may also be, for instance, a V-shaped notch or the like.

A corresponding adjustment at the support portion of a push-in connector having spring tongues may increase support and contact. For example the support surface 31 may be provided with an arcuate profile to contact a greater amount of the conductor opposite the spring tongue.

Figs. 3 and 4 illustrate an embodiment wherein a contact element 60 has three clamping locations each having a spring tongue 61, 62, 63. This push-in connector is bent off along a bending line 65 which extends substantially between the contact portions of the clamping locations, and thus is rigidified. The structure has a short current path between conductors along the bend line. A marginal portion 66 of the support portion 67 is separated by cuts 68, 69, and not also bent off. In dashed lines, it is indicated how the spring tongue 62 is lifted by a conductor 21 inserted in the direction of the arrow from the initial position at the starting angle 71 into the clamping position having the^' more acute pitch wangle 72. Again, the conductor is directionally guided by a housing opening 75. By the bending-off, it is achieved that the contact points of the support portion 67 and the spring tongue 62 at the conductor 21 illustrated in dashed lines, are disposed oppositely in a common radial plane 80 of the conductor. A lid 81 is detachably secured to the housing 82 by a border fitting into grooves and by lugs 84, 85 which co-act holdingly with bent-off marginal portions 86, 87 of the contact element 60 and the bottom of the trough-like housing base portion 82.

OMPI Figs. 5 and 6 illustrate an embodiment of a push-in connector 100 in which two rows of push-in clamping locations 101, 102, and 104, 105, respectively, are arranged on both sides of a bending line 106. 5 Thereby, the advantages obtainable by the inclined arrangement, particularly with a view to the desired smallness of the pitch angle 107, can be combined, in a compact construction, with the advantages with respect to strength which are obtainable by the bending. In the

10 embodiment illustrated, the contact portions are arranged and designed with a mirror symmetry with respect to the bending line. As may be seen from Fig. 6, the support portions have bent-off marginal sections. Furthermore, it is provided in this embodiment that the contact element

15 HO is held in the base portion 111 of the housing even without the co-operation of the lid 112. To that end, holes 114, 115 are provided in bent-off marginal sections 116, 117, the holes co-operating snappingly with projections on the inner side of the housing base portion 0 111. The bottom of the base portion 111 serves as an abutment for the inserted conductors. In this case, the lid 112 determines the push-in direction. The lid is provided with guiding push-in openings 119, 120, 121, 122. An inserted conductor 125 is illustrated in the push-in

25 opening 119, which conductor lifts the associated spring tongue 126 off from the starting angle 107 into the pitch angle 127.

Figs. 7 and 8 illustrate an embodiment of a push-in connector 150, having a contact element 151 in

30. which, similar as according to Figs. 5 and 6, a central bending line 156 is provided; however, only two push-in clamping locations 157, 158 are provided. Also in this embodiment, the lid 160 of the housing 161 again serves as an abutment for the inserted conductors 165. The contact

35 element 151 has short bent-off marginal sections 166, 167, with which the contact element fits into recesses at the edge of the housing base portion 161; the lid 160 holds

-gU£E

OMPI the contact element 151 in position, serves to guide conductors and thus determines the push-in direction 169. The spring tongues, 170, 171 are bent in the area of their free ends and have recesses there, which correspond to the cross-sectional shape of the conductors to be inserted. As can be recognized in the exemplary spring tongue 170, the recesses are designed as rectangular openings 172, 174 which have two transverse edges 175, 176 engaging the conductor 165. Thereby, it is prevented at an even 0 greater certainty that an inserted conductor is bulged and permanently deformed upon its being pulled and turned out. Figs. 9 and 10^""illustrate an embodiment in which both contact portions are designed as spring tongues. The push-in connector 180 illustrated has two clamping 5 locations 181, 182 arranged side-by-side, each having a common interior frame border 184 and 185, respectively, in a common one-piece contact element 186. In each clamping location, the contact portions are formed by two oppositely arranged spring tongues 187, 188 and 190 and 0 191, respectively.. The clamping location 181 is illustrated with a conductor 195 inserted. The push-in connector is bent off about a central bending line 196 extending between the contact portions, in such a manner that the spring tongues are disposed in the starting position (without a conductor 195 being inserted) at a desired starting angle with respect to the push-in direction, indicated by the arrow, determined by a housing 197. By the inserted conductor 195, the spring tongues are lifted off into the pitch angles. In order to obtain - a symmetrical force distribution, and engagement of the clamping forces in a common radial plane 198 of the conductor 195, the spring tongues 187, 188, or 190 or 191, respectively, are arranged symmetrically with respect to the central bending line 196 and with respect to the push-in direction (Fig. 10), and identically designed, whereby they extend under substantially identical pitch angles and under oppositely equal inclined positions with respect to an inserted conductor 195. This is illustrated in Fig. 10. This structure affords a longer current path between conductors than in the other embodiments described but adequate where the improved clamping is desirable. Having specifically described several embodiments of the present invention, it will be understood that other modifications of the shape, size or configuration of the contact elements may be made by those skilled in the art after reading this description without departing from the spirit or scope of the present invention as claimed in the appended claims.

OMPI

Claims

1. A one-piece electrical push-in type connector which is adapted to be manufactured from a one-piece cut of sheet metal of uniform thickness, and is particularly suited for general power supply current, the connector comprising a plurality of contact locations where electrical conductors may be pushed-in in a predetermined direction as particularly determined by a housing receiving the connector, and safely contacted, two opposed contact portions being provided at each contact location, of which the one contact portion is designed as^' a spring tongue which, with a conductor being inserted as viewed in the push-in direction, extends obliquely from its base portion towards the conductor and abuts the conductor at an acute pitch angle, characterized in that the two opposing contact portions are formed by a single endless cut within a piece of sheet metal to define in one piece cooperating contact portions which cooperate to grasp and electrically contact a conductor and' resist removal.

2. A connector according to claim 1, characterized in that the distance between the contact portions is dimensioned so that, within a predetermined range of conductor cross-sectional sizes, an acute pitch angle is obtained to the axis of the conductor at which an inserted conductor can be withdrawn again by pulling and simultaneous turning, without causing permanent deformation of the contact elements.

3. A connector according to claim 2, characterized in that the contact portion other than said spring tongue is provided in said cut of sheet metal to form a support portion of a strength as high as possible opposite said spring tongue.

OMP-I

4. A connector according to claim 3, characterized in that a marginal portion of said support portion, adjacent to the free edge of said support portion is bent affording an increased support surface.

5. A connector according to claim 3 or 4, characterized in that the support portion, adjacent the free edge thereof, is formed with cut edges transverse to the remainder of the support portion which edges extend transverse to the spring tongue.

6. A connector according to claim 1 or 2, characterized in that both contact portions are designed as spring tongues.

7. A connector according to claim 6, characterized in that the spring tongues of one and the same push-in clamping location are arranged symmetrically with respect to the push-in direction.

8. A connector according to claim 6, characterized in that the spring tongues of one contact are identical and extend towards an inserted conductor under substantially the same pitch angles and in oppositely equal inclined positions.

9. A connector according to claim 1, characterized in that in at least one of the contact portions belonging to one and the same clamping location has a profile in the free edge adapted to the cross-sectional shape of the conductor to be inserted.

10. A connector in accordance with claim 1, characterized in that the contact areas between the inserted conductor and the contact portions are disposed substantially in a common radial plane of the conductor.

OMPI

11. A connector in accordance with claim 1, characterized in that the contact element is bent-off along a bending line substantially extending between the contact portions of the push-in clamping location.

.

12. A connector in accordance with claim 11, characterized in that push-in clamping locations are arranged on both sides of a bending line through said contact element.

13. A connector in accordance with claim 1, which is arranged in a predetermined installation positio in a housing determining the push-in direction, characterized in that in the predetermined installation position, the spring tongue is inclined with respect to the push-in direction by an acute starting angle when a conductor is not inserted, the starting angle being large than the pitch angle.

14. A connector according to claim 1 or 2, characterized in that the spring tongue has a wider base portion than the spring tongue contact portion disposed near the face end.

15. A connector in accordance with claim 1, characterized in that it comprises additionally at least one connecting terminal means of conventional design.

16. A connector in accordance with claim 1, characterized in that it consists of one of spring brass, copper-beryllium alloy, or a laminate of steel and non-ferrous metal.

OMPI ,