US3482207A

US3482207A - Electric terminal

Info

Publication number: US3482207A
Application number: US719479A
Authority: US
Inventors: Thomas M Cairns
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1968-04-08
Filing date: 1968-04-08
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02
Also published as: GB1185009A; DE1916614A1

Description

Dec. 2, 1969 T. M. cAIRNs 3,482207 EEEEEEEEEEEEEE AL United States Patent O 3,482,207 ELECTRIC TERMINAI..

Thomas M. Cairns, Detroit, Mich., assignor to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Apr. 8, 1968, Ser. No. 719,479 Int. Cl. H01r 13/24 U.S. Cl. 339-258 3 Claims ABSTRACT OF THE DISCLOSURE An electric terminal formed from a thin metal sheet has an annular body portion of a first outside diameter and an annular depressed portion of a second outside diameter. The second diameter is less than the first diameter but more than the first diameter minus two thicknesses of the metal sheet utilized to form the terminal. A slit runs along the axial length of both portions of the terminal so that the terminal may fiare outwardly when coupled with a mating terminal.

BACKGROUND OF THE INVENTION A great variety of electric terminals are available in today's market for a wide variety of applications. When a plurality of such terminals of the female type are associated with a terminal block to form a connector, an important criteria which each of such terminals must meet is that only a certain force must be required to insert a mating terminal theren. A further requirement is that when mated, the terminals must have a prescribed area of electrical contact therebetween to insure the electrical characterisics of the circuit path formed through the mated terminals. Another requirement is that the terminals must cooperate as above described after repeated couplings and uncouplings thereof.

The electric terminal of this invention is one that fulfills all of the needs set forth above. More particularly, the terminal provides a prescribed, available area of electrical contact when mated. The insertion pressure required for terminal mating does not exceed a predetermined level and is Constant after the terminal has been inserted a minimum distance. Also, the terminal can be repeatedly mated without adversely affecting the electrical characteristics of the connection made therewith.

SUMMARY OF THE INVENTION This invention relates to an electric terminal and, more particularly, to an electric terminal both wherein a predetermined contact area is guaranteed between itself and a mating terminal and wherein the mating force does not exceed a predetermined level.

An electric terminal Constructed in accordance with the teachings of this invention is formed of a thin metal sheet and has an annular body portion of a first outside diameter. The terminal also has an annular depressed portion having a uniform outside diameter over at least a fixed length. The outside diameter of the annular depressed portion is less than the first diameter but more than the first diameter less two thicknesses of the metal sheet forming the terminal. A slit runs along the axial length of both the body portion and the depressed portion of the terminal.

The terminal so formed is a female terminal and the internal surface area of the annular depressed portion thereof provides the electrical contact surface area for the terminal to be mated therewith. The contact surface is of prescribed area to insure prescribed electrical characteristics for the electric connection formed by the terminal. The requirement that the annular depressed portion of the terminal have an outside diameter less than 3i,482,207 Patented Dec. 2, 1969 the outside diameter of the body portion of the terminal but more than the outside diameter of the body portion less two thicknesses of the metal forming the terminal insures two Characteristics of the terminal. First, the force required for mating the terminal is not extremely high and secondly, suflicient gripping pressure is applied by the terminal to insure retenton of the terminal mated therewith during utilization of the electrical connection.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic drawing of the female terminal of this invention shown in conjunction with a mating terminal.

FIGURE 2 is a schematic drawing showing the terminal of this invention in a mated position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Construction In FIGURE 1 there is seen a female terminal, generally designated by the numeral 10, and a male terminal, generally designated by the numeral 12. The female terminal 10 is formed in accordance with the teachings of this invention. The male terminal 12, of standard construction, has a rounded nose 14 on the leading portion thereof and wire gripping elements 16 on the rear portion thereof. The wire gripping elements 16 are folded over to connect the terminal 12 to bared wire when the wire is inserted in a receiving Opening 18 of the terminal. The male terminal may have a recess 20 about the circumference thereof for a purpose fully described in my copending application Ser. No. 692,822, filed Dec. 22, 1967, and assigned to the same assignee as this application. The terminal 12 may be formed of a thin, electrically conductive sheet material such as a .012 inch thick sheet of SAE CA260 brass.

The female terminal 10, as shown in FIGURE 1, is also manufactured from a thin, electrically conductive sheet material such as the mentioned brass material. The female terminal 10 has wire gripping elements 22 on the rear portion thereof for the purpose of engaging bared wire when the wire is inserted within a wire receiving opening 24 of the terminal 10. The terminal 10 may also have a recess 26 about the circumference thereof for the purpose described in my mentioned copending application.

The female terminal of this invention is Constructed so as to receive a mating terminal in such a manner that a guaranteed area of electrical contact is formed between the two terminals. In order to accomplish this function, the leading portion of the female terminal is of unique construction.

With specific reference to FIGURE 1, the leading portion of the female terminal 10 is of generally annular construction. As previously mentioned the terminal is formed from a thin metal sheet of electrically conductive material. The entry portion of the terminal is formed as a bell-mouth 30. The terminal 10 also has a main body portion 32 which has a predetermined outside diameter. A slot 34 is formed after the main body portion of the terminal for a purpose to be described subsequently. The slot 34 extends along the axis of the terminal for a small distance and extends around the circumference of the terminal a distance of not more than of arc. The slot 34 separates the elastic, leading portion of the terminal from the static, rear portion of the terminal.

An annular depressed portion 36 of the female terminal 10 is shown intermediate the main body portion 32 and the bell-mouth 30. The depresed portion 36 extends along the axial length of the terminal 10 for a distance d and may be formed in the terminal by a rolling Operation. The diameter on the outside surface of the annular depressed portion 36 of the terminal is controlled so that it is less than the predetermined outside diameter of the body portion 32 but more than the predetermned outside diameter of the body portion less two metal thicknesses of the material utilized to form the terminal. The criticalness of this dimension will be explained in the Operation portion of this specification.

A slit 38 runs along the axial length of the leading portion of the terminal 10 from the bell-mouth 30 to the slot 34. Similarly, a slit 40 extends from the slot 34 to the wire receiving opening 24 in the rear portion of the terminal 10. The slits 38 and 40 are formed as a result of the rolling of the terminal and have as opposing surfaces thereof the opposite lateral edges of the metal blank utilized to form the terminal.

Operation The Operation of the electric terminal constructed in accordance with the teachings of this invention will be described with reference to FIGURE 2 of the drawings. FIGURE 2 shows the female terminal of this invention in an assembled Condition With a suitable mating terminal.

In assembling the terminal, the nose 14 of the terminal 12 is brought into engagement with the bell-mouth 30 of the terminal 10 and pressure is applied to move the terminal 12 axially into the terminal 10. A fully inserted condition is achieved when the nose 14 of the terminal 12 proceeds significantly beyond the end of the annular depressed portion 36 of the female terminal 10. During vuthe insertion of the terminal 12, the slit 38 opens up uniformly along its length.

As was previously described, the outside diameter of the depressed annular portion 36 of the female terminal 10 is less than the predetermined, outside diameter of the main body portion 32 of the terminal. However, the outside diameter of the depressed portion is more than the predetermined, outside diameter of the main body portion less two thicknesses of the metal utilized to form the terminal. The diameter of the depressed portion 36 is so controlled to insure that the force required to mate the terminals 10 and 12 does not exceed a predetermined limit. More particularly, depression of the annular portion 36 significantly beyond that described, namely, two metal thicknesses, substantially increases the insertion pressure required to mate the terminal well above a normal insertion force range of 1 to 3 pounds of force. This increased insertion force is the result of the increased pressure applied to the contact surface area of the terminal 10 by the interior surface area of the depressed portion 36 of the terminal 12. This increased pressure means that the terminals cannot be easily uncoupled after they are once mated.

The length of the dimension d of the annular depressed portion 36 of the female terminal 10 controls the electrical contact area between the terminals 10 and 12. More particularly, as seen in FIGURE 2, the internal surface area of the depressed portion 36 is in physical engagement with a contact surface area 42 of the terminal 12 to provide the electrical junction area between the terminals. Once the terminal 12 is inserted to a position where the nose 14 passes beyond the depressed portion 36, further insertion of the terminal 12 does not increase the amount of electrical junction area between the terminals nor does it increase the insertion force. The controlled junction area thus permits a predetermined electrical characteristic for the electrical junction between the two terminals.

The axial slot 34 in female terminal 10 permits the leading portion of the terminal to be elastic and to open freely along the slit 38, the slit 38 Opening uniformly -from front to rear as the nose 14 of the terminal 12 proceeds into the terminal 10. The exact location of the slot 34 between the recess 26 and the depressed portion 36 controls the maximum amount of insertion force required to insert the terminal 12. More particularly, as the slot 34 is moved to the rear or left, as viewed in FIGURE 2, the amount of metal which must be separated as the terminal 12 is inserted is increased and, therefore, the insertion force is increased. Therefore, the exact position of the slot 34 gives an accurate control as to the amount of insertion force necessary to insert and mate the terminals.

As previously mentioned, the slot 34 allows the slit 38 along the length of the leading portion of the female terminal 10 to open uniformly upon insertion of the terminal 12 therein. Such a uniform Opening of the slit 38 permits uniform and accurate contacting of the internal surface area of the depressed portion 36 of the terminal 10 and the contact surface area 42 of the terminal 12. The internal surface area of the depressed portion 36 of the terminal 10 and the contact surface area 42 of the terminal 12 form parallel contact surfaces and such uniformity in contact insures that the electrical junction formed between the two terminals is of a prescribed quality.

In a typical construction of the terminal 12 utilizing .012 inch thick SAE CA260 brass sheet, the O.D. of the main body portion 32 was .150 to .146 inch and the O.D. of the depressed portion was .126 to .122 inch. The length d of the depressed portion was .120 inch and the slot 34 was .04 inch wide and the leading edge thereof was located .240 inch from the bell-mouth 30. This terminal construction had an average insertion force for terminal mating of two pounds of force.

There has been disclosed herein a terminal of such construction that'no more than a controlled, predetermined maximum insertion effort is required to insert a mating terminal therewithin. The terminal is also of such construction that a uniform quality junction is consistently formed between mated terminals. Further, the construction is relatively inexpensive to manufacture and of Superior value in forming electrical connectors.

The invention disclosed iwill have many modifications which will be apparent to those skilled in the art in view of the teachings of this specification.

What is claimed is:

1. In an electric terminal formed from a thin metal sheet: a substantially annular body portion of a first outside diameter; an annular depressed portion coaxial with said body portion, said annular depressed portion having a uniform outside diameter over at least a fixed length which diameter is less than said first diameter but more than said first diameter less two thicknesses of the metal sheet forming the terminal; and a slit running along the length of both said body portion and said annular portion.

2. In an annular, electric terminal formed from a thin metal sheet: an entry portion; a body portion of a first outside diameter; a depressed portion interconnecting said body and entry portions, lsaid depressed portion having a uniform outside diameter over at least a fixed length which diameter is less than said first diameter but more than said first diameter minus two thicknesses of the metal sheet forming the terminal; and a slit running the axial length of at least said body portion and said depressed portion of said terminal.

3. The electric terminal as defined in claim 2 further including a slot in said body portion of said terminal, said slot both extending across and along the axis of said body portion and intersecting said slit.

References Cited UNITED STATES PATENTS 2,269,605 l/l942 Smith. 2,8l0,893 10/1957 Nijand 339-9 FOREIGN PATENTS 992,456 7/ 1951 France.

MARVIN A. CHAMPION, Primary Examiner JOSEPH H. MCGLYNN, Assistant Examiner