US3818569A

US3818569A - Releasing tool for multiple contact

Info

Publication number: US3818569A
Application number: US00285983A
Authority: US
Inventors: R Kinkaid; J Asick
Original assignee: AMP Inc
Current assignee: TE Connectivity Corp
Priority date: 1970-11-25
Filing date: 1972-09-05
Publication date: 1974-06-25
Anticipated expiration: 1991-06-25
Also published as: NL148198B; AU460179B2; US3705376A; BE775679A; NL7115437A; AU3477571A; AT318045B; DE2156326C3; DE2156326B2; DE2156326A1; FR2115996A5; GB1309198A

Abstract

A tool for releasing an electrical contact of a connector assembly including a contact body having a crimped wire barrel portion and a channel portion with a finger-like spring mounted on the channel portion. An opening near a free end of the spring is located opposite one end of the channel permitting insertion of a conductive post through the opening and into the channel. The spring is appropriately biased to bite the post along one edge of the opening while releasing the post by use of a tool which applies a force at the end of the spring in the direction of the channel.

Description

United States Patent [191 Kinkaid et al. v

RELEASING TOOL FOR MULTIPLE CONTACT Inventors: Robert John Kinkaid, New

Cumberland; John Carl Asick, Harrisburg, both of Pa.

Assignee: AMP Incorporated, Harrisburg, Pa. Filed: Sept. 5, 1972 Appl. No.: 285,983

Related US. Application Data Division of Ser. No. 92,742, Nov. 25, 1970, Pat. No. 3,705,376.

US. Cl. 29/203 H Int. Cl B25b 27/02 Field of Search 29/203 H, 206 R, 203 HC,

[451 June 25, 1974 3,377,689 4/1968 Kimmett... 29/203 H 3,600,784 8/1971 Propst 29/203 H Primary Examiner-Thomas H. Eager Attorney, Agent, or Firm--Gera1d K. Kita [57] ABSTRACT A tool for releasing an electrical contact of a connector assembly including a contact body having a crimped wire barrel portion and a channel portion with a finger-like spring mounted on the channel portion. An opening near a free end of the spring is located opposite one end of the channel permitting insertion of a conductive post through the opening and into the channel, The spring is appropriately biased to bite the post along one edge of the opening while releasing the post by use of a tool which applies a force at the end of the spring in the direction of the channel.

3 Claims, 10 Drawing Figures PATENTEDJUN25I974 3.818.569

' SHEET u (If 4 RES g 0.5 TEST CURRENT. AMPE SINHOITHW EIONViSlSi-JH NOILVNIWHHJ.

9 I T lNElO saaalsacl-Ellsla HHPLVHEIdIWBL This is a division of application Ser. No. 92,742, filed Nov. 25, 1970 and now U.S. Pat. No. 3,705,376.

BACKGROUND OF THE INVENTION This invention relates to connectors and, more particularly, to connectors of the spring contact type for releasably receiving conductive posts.

Various connectors of the spring contact type have been proposed, but many spring contacts will not readily release a mating conductive post. In many instances, the connector must be destroyed to break the electrical connection. In other instances, rather complicated tools must be employed to break the connection.

The nature of the electrical contact between the connector and the conductive post is also a source of some difficulty in the spring contact prior art.- For example, the spring contact disclosed in U.S. Pat. No. 1,240,186 Fahnestock does not provide an elongated conductive channel to assure substantial contact with a conductive post. Furthennore, the spring contact of Fahnestock is examplary of prior art which is characterized by an undesirable increase in resistance with temperature.

In certain cases, the prior art spring contacts have precluded the stacking of contacts on a single conductive post. The spring contact disclosed in U.S. Pat. No. 2,617,844 Sanda is illustrative.

SUMMARY OF THE INVENTION In accordance with one important aspect of the invention, a tool for releasing a contact connector of the spring contact type is provided which will readily release the contact from a conductive post. Accordingly, the spring contact comprises a conductive channel adapted to receive a conductive post and further comprises a spring having an opening located at the end of the channel. The spring is appropriately biased to a position characterized by misalignment between an edge of the opening and one side of the channel so as to bite one side of the conductive post at the edge of the opening upon insertion of the post into the channel through the opening. By applying a force at the end of the spring adjacent the opening, the conductive post is released by the spring.

In accordance with another important aspect of the invention, proper contact is made between the channel and the conductive post. In this connection, the spring of the connector comprises a fixed portion extending along the channel and a flexible portion including the opening near the spring end which is free to move about a fulcrum at the end of the channel. Upon insertion of the conductive post into the channel through the opening in the spring, contact is made between the post and the channel at the side of the channel opposite the edge of the opening and adjacent the fulcrum of the spring. Another area of contact between the channel and the post is located at the other end of the channel and on the side of the post which the edge of the opening bites.

In accordance with a further important aspect, a tool is provided for the release of a conductive post from the connector. Such a tool may comprise hook means for engaging the free end of the spring and an actuated member for applying an axially compressive force on the connector. As an axially compressive force is applied to the connector, the free end of the spring pivots about the fulcrum forcing the end of the spring away from the conductive post to release the bite.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of a connector embodying the invention;

FIG. 2 is a perspective view of the connector shown in FIG. '1;

FIG. 3 is a side view of the connector shown in FIG. 2 in combination with a conductive post, the contact being shown in partial cross-section;

FIG. 4 is a side view'of a pair of the connectors shown in FIG. 2 stacked on the conductive posts;

FIG. 5 is a perspective view of a tool releasing a conductive post from the spring contact of FIG. 2;

FIGS. 6 and 7 depict sequential steps in the operation of the tool shown in FIG. 5;

FIG. 8 is a side view of a pair of modified connectors embodying the invention which are stacked on a conductive post;

FIG. 9 is a sectional view of one of the connectors shown in FIG. 8; and

FIG. 10 is a graph depicting connector characteristics as a function of current.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 is an exploded view of a connector of the spring contact type comprising a body 10 and spring 11. As shown, the body includes a channel portion 12 for receiving a conductive post, a transition portion 14, and a wire barrel portion 15 axially offset from the channel portion 12 for receiving a wire. The body 10 also includes cars 13 which are adapted to bend over a fixed portion 11a of the spring 11.

The spring also includes an arched portion 11b and a locking portion llc. An opening 16 is provided in the locking portion llc which is partially aligned with the channel when the connector is assembled as shown in FIG. 2. The locking portion 11 of the spring also includes a dish 17 which strengthens the spring 11 and, as will be subsequently explained, optimizes the bite of the locking portion llc on the post.

Note that each of the ears 13 is precreased. Therefore, when the ears are bent over the fixed portion of the spring, the resulting bend across the fixed portion llc will be uniform, right-angled and not radiused. This type of bend will not buckle the spring. The wire barrel 15 is bent or crimped over the connecting wire 18 in a substantially conventional manner.

FIG. 3 shows the connector in place on a post 19. The arched portion 11b of the spring extends around the corner, or fulcrum point 20 external to the channel. An edge 21 of the opening 16 is biased to a position of slight misalignment with one side of the channel before the post 19 is inserted. When the post 19 is inserted into the channel through the opening 16 as shown in FIG. 3, the spring 11 bites, that is, bears against, the post 19 at the edge 21 in the dish 17.

Note that the angle of bite for the spring at the edge 21 is reduced and thereby optimized by the dish 17. Furthermore, the dish 17 forms radiased corners which fit into frictional engagement with the comers of the post 19 and improve the holding ability of the connector.

The electrical contact between the post 19 and the channel occurs in three different areas. One area 22 is adjacent the fulcrum 20. The other area 23, is on the opposite side of the channel adjacent the transition portion 14. The pressure exerted by the spring holding the post 19 against the two areas of the channel provides ample electrical contact between the post 19 and the channel. There is also electrical contact through the spring member.

Referring again to FIG. 3, it will be noted that, when the connector is in place on the post 19, there is a gap 24 between the spring 11 and the portion of the body which forms the channel 12. This gap is important because the spring can be depressed through this gap to release the bite or pressure on the post. Note further that, if the tip of the spring is pushed upwardly or in the direction of the channel portion 12, that is, fulcrumed about the comer 20, the spring pressure is released. In this embodiment of the invention, it is particularly convenient to apply pressure to the wire barrel and to the tip of the spring 11 to increase the arch in the arched portion 11c and release the pressure on the post 19. In this manner there is provided a connector which is truly a zero force connector when it is applied. However, after it is applied to the post 19 and the spring bites, the connector cannot be pulled off. It has been found that the wire 18 will pull out the wire barrel 15 before the connector will pull off the post.

FIG. 4 shows two connectors on the post 19. In use, it is commonly necessary to stack two or more connectors'on a post in this manner and the connector of this invention is a particularly convenient way of doing so.

FIG. 5 shows a tool for releasing the spring. The tool includes a channel portion which receives the connector and post and books 26 which hold the end of the spring 11. A spring-loaded plunger 27 is moved toward the hook by hand operation of the handle 28 thereby applying an axially compressive component of force on the connector as a force is applied to the free end of the spring 11 directed toward the channel 12. FIG. 6 shows the plunger 27 in the position before pressure is applied by the operator. FIG. 7 shows that the hooks 26 which extend perpendicular to the axis of the channel 12 and plunger 27 have been movedcloser to each other to further arch the edge 21 of spring 11 away from the post 19 thereby further pivoting the spring around the fulcrum 20 to release the pressure between the post 19 and the body 10. The actual movement of the plunger 27 is very slight as is apparent from an inspection of FIGS. 6 and 7 but is sufiicient for releasing the spring from the post.

One particularly useful modification of the tool has an overcenter lever which pushes the plunger 27 forward. With this modification the operator need not maintain the pressure on the plunger 27 while pulling the connector from the post 19.

FIGS. 8 and 9 show a modified connector embodying the invention. In this modification the wire barrel 15 is on the same side as the fixed spring portion 110. A hole 29 has also been provided in the transition portion. The post extends through this hole. This modification is particularly useful where the connectors are applied by an automated machine. Note that it is not necessary to reverse or rotate two adjacent, stacked connectors by 180 with respect to one another. In this modification of the invention, an ear 30 is provided for exerting pressure to release the spring 11. If pressure were applied between the tip of the spring 11 and the wire barrel 15, as in the embodiment of FIG. 2, the spring would kink. This is avoided by applying pressure between the car 30 and the tip of the spring 11 to release the bite on the post 19.

FIG. 9 shows the spring 11 in its relaxed position before the post is inserted for the first time. Note the misalignment between the edge 21 and the side of the channel 12. After the post 19 is inserted into the channel 12 through the opening 16, the spring 11 will be bent to a position shown in FIG. 8 while the memory of the spring holds the edge 21 against the post 19.

' In one actual embodiment of the invention, the' spring 1 1 comprisedstainless steel having a modulus of elasticity of 28 X 10 lbs. The body comprised phosphor bronze although other materials are suitable for use. Other suitable materials include soft copper, grade C copper or any other good conductive material. In one embodiment, the connector of FIGS. 1-4 comprises a body in which the channel portion 12 has a square cross-section 0.028 i- 0.001 inches on a side. The square cross-section of the post 19 is 0.025 t 0.001 inches on a side. In the modification of FIGS. 8 and 9, one actual embodiment has a channel 12 with a rectangular cross-section, 0.034 t 0.002 by 0.067 t 0.002. The post in this embodiment is 0.031 t 0.001 by 0.062 0.001 inches.

The connector of the present invention exhibits a re- 'sistance versus current characteristic. Normally, as the current through a connector increases, the resistance increases. This causes the temperature to increase and the voltage drop across the connector to increase.

However, the connectorofthe present invention exhibits a negative resistance characteristic. As heat is generated in the connector by increased current, the body 10 expands faster than the spring 11 due to the different coefficient of expansion between spring and body. In the embodiment previously described, the coefficient of expansion of stainless steel is lessthan that of a phosphor bronze body. Asthe body 10 expands, the fulcrum point or corner 20 engages the spring 11 with increased pressure to increase the bias on the spring 11. The increased bias on the spring improves the contact between the post 19 and the body 10.

This characteristic is demonstrated by the graph of FIG. 10 which contains two plots. The first is a plot of termination resistance in milliohms as a function of current. The Xs are average values of tests on five samples. The bars above and below the Xs represent the maximum and minimum resistance exhibited for each of the five samples. Note that as the current increased from 0.5 amps to 3.5 amps; there was a decrease in average termination resistance from 1.00 to 0.95 milliohms. This is about 6 percent decrease in resistance.

The other plot in FIG. 10 is a plot of temperature as a function of current. The temperature indicated on the ordinate is the difference between ambient temperature and the temperature of the transition portion 14 of the connector. This is usually considered a hot spot in connectors. Note that there is approximately a 10 increase in temperature. This represents approximately a 50 percent rise in temperature while the contact actually exhibited a 6 percent decrease in resistance. The foregoing test demonstrates that within the parameters of the connector design there is a decreasing resistance instead of the normal increasing resistance with increased current.

Various modifications of the disclosed embodiments of the invention may be made without departing from the scope of the appended claims.

What is claimed is:

1. A tool for use in releasing a conductive post from a connector of the type comprising a conductive channel portion adapted to receive the post and a spring having an end fixed with respect to said channel and a free end having an opening located at one end of the channel, the free end of the spring being biased about a fulcrum so as to bite the post with an edge of the opening and lock the post in place, said tool comprismg:

a connector receiving section including means for engaging said connector at the extremity of said free 6 end;

a depressible plunger cooperating with said connector receiving section for engaging said connector nearer said fixed end of said spring than said free end, said plunger applying a substantially axially compressive component of force along said channel so as to pivot said free end of said spring about said fulcrum thereby releasing the bite on said post.

located in said channel of said tool.

Claims

1. A tool for use in releasing a conductive post from a connector of the type comprising a conductive channel portion adapted to receive the post and a spring having an end fixed with respect to said channel and a free end having an opening located at one end of the channel, the free end of the spring being biased about a fulcrum so as to bite the post with an edge of the opening and lock the post in place, said tool comprising: a connector receiving section including means for engaging said connector at the extremity of said free end; a depressible plunger cooperating with said connector receiving section for engaging said connector nearer said fixed end of said spring than said free end, said plunger applying a substantially axially compressive component of force along said channel so as to pivot said free end of said spring about said fulcrum thereby releasing the bite on said post.

2. The tool of claim 1 wherein said connector receiving section forms a channel for receiving said conNector.

3. The tool of claim 2 wherein said means for engaging said spring comprises at least one hook projecting substantially perpendicular to the axis of a connector located in said channel of said tool.