US3622956A

US3622956A - Electrical connector

Info

Publication number: US3622956A
Application number: US856325A
Authority: US
Inventors: Alfred M Zak
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-09-09
Filing date: 1969-09-09
Publication date: 1971-11-23
Anticipated expiration: 1988-11-23
Also published as: GB1289034A; DE2044506B2; JPS5122628B1; DE2044506A1; CA919792A

Abstract

An electrical connector adapted to be telescopically engaged with a blade-type contact. The connector has a base formed with a spring flange along each longitudinal side thereof. The flanges are formed as inverted U-shaped channels each having a free lower contact edge. Each channel is relieved at its opposite ends preferably along axially inclined planes so that the top bight portion is substantially shorter in length than the contact edges whereby to impart substantial flexibility to the portions of the flanges provided with the contact edges.

Description

United States Patent 2,579,739 l2/l95l Hayes lnventor Alfred M. Zak

6110 Casmere Ave., Detroit, Mich. 48212 Appl. No. 856,325 Filed Sept. 9, 1969 Patented Nov. 23, 1971- ELECTRICAL CONNECTOR 13 Claims, 14 Drawing Figs.

US. Cl 339/258 S Int. Cl l-l0lr 13/12 Field of Search 339/256,

References Cited- UNITED STATES PATENTS 2,825,883 3/l958 Batcheller 339/258 S FOREIGN PATENTS 391,823 9/1965 Switzerland 339/258 S Primary Examiner-Joseph H. McGlynn Attorney-Barnes, Kisselle, Raisch & Choate ABSTRACT: An electrical connector adapted to be telescopically engaged with a blade-type contact. The connector has a base formed with a spring flange along each longitudinal side thereof. The flanges are formed as inverted U-shaped channels each having a free lower contact edge. Each channel is relieved at its opposite ends preferably along axially inclined planes so that the top bight portion is substantially shorter in length than the contact edges whereby to impart substantial flexibility to the portions of the flanges provided with the contact edges.

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INVIJNIUR. ALFRED M. 'ZAK ELECTRICAL CONNECTOR This invention relates to an electrical connector and more specifically to a connector of the type adapted to be telescopically engaged with a blade-type contact.

Connectors of the above-described type are conventionally formed with a base which serves as a support for the telescopically engaged blade contact and with a pair of spring flanges formed as inverted U-shaped channels having a free lower contact edge which extends lengthwise of the connector generally parallel to the base and spaced therefrom a distance less than the thickness of the blade Contact with which the connector is adapted to be telescopically engaged. Connectors of this type are in most instances of very small size and as conventionally constructed some of the dimensions must be held to very close tolerances. For example, with some conventionally constructed connectors of this type a variation of only 0.005 inch in the spacing between the free Contact edge of each flange and the base can result in a difference of about to pounds of force required to telescopically engage a contact blade with the connector. Accordingly, in order to insure good contact with such connectors as conventionally constructed the dimensional tolerances have to be held within very close limits and the insertion forces required are relatively high.

The primary object of this invention resides in the provision of a connector of the type described which is designed so that the dimensional tolerances can be relatively wide while the insertion forces can be accurately held to relatively low values.

More specifically, the connector of this invention is constructed so that the spring flanges are substantially more flexible than is the case with such connectors of conventional construction. The greater flexibility of the spring flanges not only results in the ability to increase the dimensional tolerances and reduce the required insertion forces, but also enables the contact edges of the two spring flanges to align themselves more readily into line contact with the inserted blade Contact.

A further object of the invention is to relieve the spring flanges of connectors of this type in a manner to impart substantially greater flexibility to the spring flanges without significantly weakening the connector as a whole.

Other features and objects of the invention will become apparent from the following description and drawings, in which:

FIG. 1 is a fragmentary vertical sectional view through a terminal block or housing in which a connector of the present invention is retained.

FIG. 2 is a top view of the connector shown in FIG. 1.

FIG. 3 is a fragmentary front end view of the assembly shown in FIG. 1.

FIG. 4 is a fragmentary end view, partly in section, of the connector and terminal block on an enlarged scale.

FIG. 5 is a sectional view along the line 5-5 of FIG. 4.

FIG. 6 is a plan view of the sheet metal blank used for fonning the preferred form of connector shown in FIGS. 1 through FIGS. 7 through 14 illustrate various modifications relating to the manner in which the spring flanges of the connector are relieved.

In FIG. 1 a tenninal block or housing formed of an electrical insulating material is designated 10. Block 10 is formed with a cavity 12 in which the connector 14 of the present invention is located. Connector 14 has a front portion 16 adapted to be telescopically engaged with blade-type Contact 18 and a rear portion 20 adapted to be crimped or otherwise secured to a conductor 22. Front portion 16 of connector 14 is formed with a generally flat base 24 from the central portion of which a spring tab 26 is struck downwardly. When connector 14 is inserted in cavity 12 from the rear open end 13 thereof tab 26 is adapted to engage with a shoulder 28 in cavity 12 to prevent retraction of the connector from within the cavity.

As is shown in FIGS. 3 and 4, along each side of base 24 front portion 16 of the connector 14 is formed with a pair of spring flanges 30. Each spring flange 30 is shaped as an inverted U channel having an inner sidewall 32, and outer sidewall 34 and a top wall defined by an arcuate bight portion 36 Sidewall 34 is integrally connected with base 24 by a longitudinally extending bent comer portion 38. The lower portion if inner sidewall 32 terminates in a generally straight contact edge 40 which ideally extends parallel to base 24 and which in'its free state is spaced above base 24 a distance less than the thickness of blade 18. In order to facilitate insertion of blade 18 between contact edges 40 and base 24 the leading end of blade 18 is tapered as at 42 and the leading end of each contact edge 40 is curved upwardly as at 44.

Each channel or flange is relieved in the manner illustrated in FIGS. 1, 2 and 4. The relieving of these channels is preferably accomplished by forming the blank from which the connector: is fabricated with notched portions in which the finished connector appear as cutaway portions 46.

The blank 48 utilized in forming the connector shown in FIGS. 1 through 5 is illustrated in FIG. 6. The cutaway portions 46 are defined by notches which are located laterally inwardly from the opposite side edges 50 of the blank. When blank 48 is formed into connector 14, the side edges 50 of the blank define the contact edges 40 of the connector. Each notch or cutaway portion 46 is defined by a pair of converging straight edges 52 which are interconnected by an arcuate edge 54. Notches 46 are located in two laterally opposed wing sections 56 of the blank such that, when the wing sections are fonned into the inverted channels 30, the cutaway portions 46 are not symmetrically disposed relative to the vertical axes of channels 30. Thus, as shown clearly in FIGS. 4 and 5, the cutaway portion 46 on each inner sidewall 32 extends circumferentially from point 58 (at the leading end of curved edge 44), around bight portion 36 and down to point 60 on outer sidewall 34. Cutaway portions 46 are located such that a line extending through

points

58, 60 on each channel 30 is inclined downwardly and laterally outwardly at an angle of about 30 to the horizontal.

In addition, it will be observed that the straight edges 52 of cutaway portions 46 inthe formed connector incline upwardly from the opposite ends of channels 30 and inwardly toward the axially central portion of each channel. The arcuate portion 54 of each cutaway portion 46 is located generally at the tie section designated 62. Tie sections 62 represent the sections of bight portions 36 having a minimum length. As is clearly seen in FIG. 4, tie sections 62 are displaced circumferentially about 30 outwardly from the topmost portion of bight portion 36. Thus, each spring flange or channel 30 is relieved a maximum extent at section 62 which lies at that portion of the channel which is subjected to the greatest degree of flexing when the contact edge 40 is shifted vertically upwardly by reason of insertion of blade 18 into the front end of the connector.

The angular offset of about 30 of the section 62 of maximum relief on each channel from the topmost portion of the channel not only results in a minimum length of the bight portion 36 where maximum flexing occurs but also enables obtaining a maximum relief of each spring flange without weakening the curved leading edge portion 44 of the contact edge 40. While it is not essential that the cutaway portions 46 at the rear ends of channels 30 be circumferentially offset in the manner illustrated in FIG. 4 since the rear ends of the contact edges 40 are not curved, nevertheless it is preferred to angularly offset cutaway portions 46 at the front and rear ends of channels 30 to the same degree in order to simplify that tooling required for fonning the blank.

The shape of cutaway portions 46 resulting from the configuration of the notches defined by

edges

52, 54 represents a preferred embodiment of the invention. As shown in FIG. 5, by shaping the cutaway portions 46 in this manner the edges 52 of notches 46 at the front end of the connector incline upwardly in a rearwardly direction. These inclined edges facilitate insertion of the connector in cavity 12 from the rear end thereof. In other words, when the connector 14 is inserted in cavity 12 from the open rear end 13 of the cavity the edges 52 at the leading end of the connector eliminate the necessity of arcuate axial alignment of the connectors with openings 13. Inclined edges 52 serve as cams when they engage the comer portion 64 of housing 10 and thus properly align the connectors with openings I3. This feature is highly desirable when it is considered that the vertical dimension of opening 13, neglecting tapered slot 65 for accommodating tab 26, may be as small as about 0. I50 inch and the height of front portion 16 of the connector may be as much as about 0. I40 inch. It will be observed that at the front end of block 10 the opening 66 through which blade 18 is inserted is defined by a pair of opposed lip portions 68 against the inner faces of which the front end of the connector is adapted to abut to limit the forward movement of the connector within the terminal block.

By relieving the spring flanges in the manner illustrated (that is, by the formation of the cutaway portions 46) a highly improved connector structure is produced. The inner sidewalls 32 of channels 30 are rendered substantially more flexible than they would be if not relieved in the manner illustrated. The increased flexibility of these flange portions is extremely desirable since it enables the connector to be designed with greater dimensional tolerances while permitting substantially less insertion forces. As a matter of fact, in a connector of one particular size it has been determined that the provision of the cutaway portions 46 enables the dimensional tolerances of the connector to be increased by I percent while reducing the insertion forces from about 6 pounds down to I lto 3 pounds as compared with a connector formed of the same material and to the same configuration without the cutaway portions 46.-In addition, it will be observed that by shortening the length of the tie section 62 of the channels the inner sidewall 32 is rendered substantially more flexible in a longitudinal as well as radial direction. This enables the contact edge 40 to align itself quite readily into line contact with top surface of the blade contact 18. This is an important feature of the invention since it is extremely difficult to form these connectors such that the contact edge 40 is in accurate parallelism with base 24. If contact edges 40 are not parallel to base 24 and the inner sidewalls of the channels are relatively rigid the contact edges 40 may contact the top surface of blade 18 through only a small portion of their length thus resulting in poor contact between the blade and the connector.

The extent to which the length of the bight portion at the tie section 62 is diminished in relation to the length of the sidewalls of channels 30 is determined largely by the thickness of the material from which the connector is formed in relation to the insertion force desired. For example, with relatively thin materials (brass having a thickness of about 0.0125 inch) insertion forces of about 1.5 to 3 pounds have been obtained where the length of the tie portion is about 0. I50 inch and the length of the channels is about 0.300 inch. With thicker material (brass having a thickness of 0.018 inch) insertion forces of about 3 to 6 pounds have been obtained where the length of the tie portion is only about 0. I00 inch and the length of the channels is about 0.300 inch.

In FIGS. 7 through I4 there is illustrated various configurations for the cutaway portions on the two channels. In FIG. 7 the blank is formed with notches or cutaway portions 70 of semicircular shape. When the blank is formed into the connector, the cutaway portions 70 have the appearance shown in FIG. 8. As viewed in side elevation the semicircular edge 72 presents inclined edges 74 on the inner and outer sidewalls of the channels which are slightly upwardly concave. In FIG. 9 the cutaway portion 76 is defined by an angular edge 78 connected by an are 80 with a straight edge 82 extending perpendicular to the longitudinal axis of the connector. The notch is completed by a straight edge 84 extending axially of the connector. When the blank of FIG. 9 is shaped into a connector the cutaway portion 76 has the appearance shown in FIG. wherein the straight edge 78 inclines upwardly in a slightly convex manner and the curved edge 80 merges with the straight edge 82 at the circumferentially offset tie section 86.

The cutaway portion 88 of the blank shown in FIG. 11 is defined by an arcuate edge 90 and perpendicularly related

straight edges

92, 94. When the blank of FIG. II is formed into a connector these edges present the configuration illustrated in FIG. 12. In the blank illustrated in FIG. 13 the eutaway portion 96 is defined by two axially extending

straight edges

98, 100 interconnected by a transverse straight edge I02 and the present the configuration shown in FIG. 14 when the blank is formed into a connector. While in the embodiments illustrated in FIGS. 9 through 14 the inner sidewall of each channel is perhaps more flexible than is the case of the connector as illustrated in FIGS. 1 through 8, nevertheless the terminal as a whole is probably slightly weaker. In each embodiment however the bight portion of the channel has its minimum length at the section thereof displaced circumferentially outward of the topmost portion of the bight portion so that it corresponds in location with the point of maximum flexing of the flange when the contact edge is displaced vertically by inserting a blade contact into the connector.

Electrical testing of connectors of this invention has disclosed that the tie portion of the spring channels of the connector can be reduced to a length of one-half or one-third the overall length of the spring channels without appreciably increasing the electrical resistance of the connector. For example, at a current of 20 amperes a connector of the present invention showed an increase in the voltage drop across the connector of only I or 2 millivolts over a conventional connector of the same type but not relieved at the opposite end portions of the channels. A millivolt drop in this range is substantially less than occurs when the spring channels of the connector are relieved as by cutting away the axially central portion of the channel as distinguished from the axially opposite end portions of the channels. When a connector of this type is relieved at the axially central portion so as to provide a tie section at each end having a length of about 0.075 inch the electrical resistance of the connector is substantially greater than a connector having a single axially central tie section of 0. l 50 inch. Furthermore, the utilization of a central tie section results in a connector which is substantially stronger than one having a plurality of spaced individual tie sections whose combined length is equal to the length of the single central tie portion. X

I claim:

1. An electrical connector having a front portion adapted to be telescopically engaged with a blade-type contact and a rear conductor-engaging portion, said front portion having a base forming a support for the blade contact and having a pair of transversely spaced spring flanges extending lengthwise of the base at each side thereof, each of said flanges comprising an inverted generally U-shaped channel with transversely spaced inner and outer sidewalls connected by a curved bight portion which forms the top wall of each channel, each outer sidewall being integrally connected with said base along its lower edge, each inner sidewall having a free lower edge which is spaced above said base a distance less than the thickness of the blade contact to be used therewith and which forms a straight bladecontacting edge, each of said inverted channels being relieved at the opposite ends thereof by a cutaway portion, each cutaway portion being defined by a line which extends axially inwardly from the adjacent end of the inner wall, then around said top wall and then axially outwardly on the outer sidewall to the adjacent end thereof such that the length of the bight portion of each channel is substantially less than the length of the lower portions of said inner and outer sidewalls.

2. A connector as called for in claim I where in the length of said bight portion adjacent the upper end of each inverted channels is not greater than about half the length of the lower portion of the inner and outer sidewalls.

3. A connector as called for in claim 1 wherein the cutaway portion of the outer sidewall of each channel terminates circumferentially at a lower level than the cutaway portion on the inner sidewall of each channel.

- 4. A connector as called for in claim 1 wherein each cutaway portion is defined by edges at the front and rear ends of the inner and outer sidewalls of the channels which incline upwardly and axially inwardly toward the axially central portion ofeach channel.

5. A connector as called for in claim 1 wherein the front end portions of said blade-contacting edges incline upwardly to the leading end thereof to facilitate insertion of the blade between said blade-contacting edges and said base.

6. A connector as called for in claim 5 wherein the cutaway portion at the front end of each channel extends circumferentially upwardly from a point above the leading end of said blade-contacting edge on said inner sidewall, around said bight portion and downwardly around the outer sidewall of each channel to a point at a level substantially below the leading end of said blade-contacting edge.

7. A connector as called for in claim 6 wherein the relieved cutaway portions at the front and rear ends of the channels are generally of similar shape, size and circumferential location.

8. A connector as ,called for in claim 6 wherein said two points are located circumferentially around each channel such that a straight line passing therethrough inclines downwardly in a laterally outward direction at an angle of at least about 30 to the horizontal.

9. A connector as called for in claim 1 wherein the cutaway portions at the opposite end of each channel extend circumferentially upwardly from a point above said blade-contacting edge on the inner sidewall, around said bight portion and downwardly around the outer sidewall of each channel to a point at a level substantially below said point on said inner sidewall.

10. A connector as called for in claim 4 wherein said lastmentioned point is disposed at a level below said blade-contacting edge.

11. A connector as called for in claim 9 wherein the eutaway portion on the inner sidewall at the front end of each channel is defined by an edge which inclines upwardly and axially inwardly toward the axially central portion of each channel.

12. A connector as called for in claim 9 wherein each cutaway portion is defined by edges at the front and rear ends of the inner and outer sidewalls of the channels which incline upwardly and axially inwardly toward the axially central portion of each channel.

13. A connector as called for in claim 12 wherein the bight portion has a longitudinally extending section of minimum length which extends along a line displaced circumferentially of the topmost portion of the bight portion towards the outer sidewall.

Claims

2. A connector as called for in claim 1 where in the length of said bight portion adjacent the upper end of each inverted channels is not greater than about half the length of the lower portions of the inner and outer sidewalls.

4. A connector as called for in claim 1 wherein each cutaway portion is defined by edges at the front and rear ends of the inner and outer sidewalls of the channels which incline upwardly and axially inwardly toward the axially central portion of each channel.

8. A connector as called for in claim 6 wherein said two points are located circumferentially around each channel such that a straight line passing therethrough inclines downwardly in a laterally outward direction at an angle of at least about 30* to the horizontal.

9. A connector as called for in claim 1 wherein the cutaway portions at the opposite ends of each channel extend circumferentially upwardly from a point above said blade-contacting edge on the inner sidewall, around said bight portion and downwardly around the outer sidewall of each channel to a point at a level substantially below said point on said inner sidewall.

10. A connector as called for in claim 4 wherein said last-mentioneD point is disposed at a level below said blade-contacting edge.

11. A connector as called for in claim 9 wherein the cutaway portion on the inner sidewall at the front end of each channel is defined by an edge which inclines upwardly and axially inwardly toward the axially central portion of each channel.