GB2089143A - A socket contact with low insertion forces - Google Patents

Abstract

A socket contact (10) is substantially cylindrical and has one end (12) which is adapted to be connected to an electrical conductor, the other end (14) having a cavity (22), for mating with a connector pin, and a slot (16) along part of its length. The slot (16) houses a plunger (18) which is held by a pair of resilient C-rings (26 and 28). The plunger (18) provides a substantially even force on the pin, as well as a gradual low insertion force for the pin. <IMAGE>

Description

SPECIFICATION A socket contact with low insertion forces This invention relates to improved electrical socket contacts. More particularly, it relates to an improved socket contact, especially adapted for high power applications where low insertion forces, excellent mechanical durability and a high surface area of contact are important. Electrical power connectors utilizing pins and sockets normally include ancillary apparatus or methods for ensuring electrical integrity between the pin and socket. This is very important in high current carrying connectors, such as railroad connectors, because poor intimate mechanical contact will cause an increase in constricton resistance, thus producing additional heat within the connector, which could cause damage as well as inefficiency.

Examples of such connectors are the split pin, whereby the actual diameter of the pin is slightly larger than the actual diameter of the socket. However, when the pin is inserted into the socket, the pin compresses somewhat, being permitted to do so by the splitting, and the spring action is formed to insure electrical integrity of the socket. Obviously, this technique requires a very high insertion force which is undesirable. Other types of spring members have also been utilized, such as that described in U.S. Patent 3,453,587, assigned to Multi-Lam AG.

The Multi-Lam patent utilizes a band within the socket contact, which provides spring forces on the pin. Obviously, use of this technique results in a very small surface area in contact between the pin and socket, poor mechanical durability and contact weariness due to the high insertion forces.

One solution to this problem of high insertion forces is shown in U.S. Patent 2,988,723, previously assigned to the Pyle-National Company, now assigned to Akzona Incorporated, applicant of the present invention. This patent teaches the use of a temperature responsive material inserted between the pin and the socket with a C-clamp for holding the temperature responsive material in place about the socket. When the pin is inserted into the socket, there are no extraordinary insertion forces but only the normal insertion forces. However, during operation, the connection begins to heat up, and the material which is utilized thermally expands, causing an increase in actual contact and thus a decrease in electrical contact resistance for the termination.

It is one object of this invention to provide a socket contact with low pin insertion forces.

It is another object of this invention to provide a socket contact with a substantially even load distribution between pin and socket contact in a mated condition.

It is another object of an embodiment of this invention to provide a socket contact which will permit relative ease of insertion and withdrawal of a connector utilizing more than one socket contact.

According to the invention, there is provided a socket for an electrical connector, comprising an elongate substantially cylindrically shaped member, including one end adapted to be connected to an electrical conductor, and the other end having a pin receiving barrel member, the barrel member including a cavity therein and having an elongate slot along a portion thereof, wherein a plunger is received in a portion of the said slot, a part of the plunger extending into the said cavity prior to the insertion of a corresponding connector pin into the cavity, and wherein at least two spring members contact the plunger, whereby low insertion forces are capable of being provided on the pin during the insertion into the socket, and substantially balanced forces are capable of being provided on the pin after it is inserted into the socket.

The invention also provides a socket for an electrical connector comprising an elongate substantially barrel-shaped member including one end adapted to be connected to an electrical conductor, and the other end having a pin receiving barrel member, the barrel member including a cavity therein and having an elongate slot along a portion thereof, wherein a plunger is received in a portion of the said slot, a part of the plunger extending into the said cavity prior to the insertion of a corresponding pin into the cavity, and wherein at least two C-clamp shaped spring members are attached to the plunger and surround the socket, whereby low insertion forces are capable of being placed on the pin by a first spring member as it is inserted into the socket and a substantially balanced force is capable of being provided on the pin by all the srping members after the pin is fully inserted into the socket.

The invention, together with further objects and advantages thereof, may be better understood by referring to the following description, of an example of a socket according to the invention, in conjunction with the accompanying drawings, in which: Figure 1 is a perspective view of a socket contact according to the invention.

Figure 2 is a cross-sectional view of the socket contact of Figure 1, showing a corresponding pin contact being partially inserted into the socket.

Figure 3 is a cross-sectional view of the socket contact of Figure 1, showing a pin contact fully inserted into the socket.

Figure 4 is an end view of a plunger of the socket contact of Figures 1 to 3.

Referring now more particularly to Figure 1,there is provided a socket contact 10 being constructed in a barrel shaped form with afar end 12 adapted to be connected to an electrical wire or cable, and the other end 14 being a hollow cylindrical barrel shaped member adapted to receive a corresponding pin contact, as shown in Figures 2 and 3. The hollow cylindrical barrel portion 14, which includes opening 15, is broken or slit longitudinally, as indicated by 16.

This slot permits the plunger 18 to rise as the pin is inserted into the socket. A polyethersulphone plunger 18 is received in slot 16, and its lower portion 20 protrudes into cavity 22 before pin 24 is inserted into the socket, as shown in Figure 2. Snap C-rings 26 and 28 are wrapped about the outer barrel surface 30 of the socket and secure the plunger 18 in slot 16.

These snap rings 26 and 28 are maintained within grooves 32 and 34 of the plunger 18 by means of projections 36 and 38, which protrude from the top surface of the grooves 32 and 34 of the plunger. The projections 36 and 38 are received in slots 42 and 44 of each snap ring. The snap rings include slits (not shown) which enable one to assemble the snap rings to the socket easily, and provide for a spring action with the snap rings on the plunger. The snap rings are normally made of a metal, such as berrylium copper, which will deform and then restore back to its original shape as a pin is inserted into the socket as shown in Figures 2 and 3. These snap rings, thus, will provide spring pressure down on the plunger.

The plunger snap ring assembly is received within groove 46 of the socket, and each snap ring abuts against shoulders 48 and 50 of the groove so that they do not slide away easily from the socket assembly.

Referring now to Figure 2, it can be seen that as the pin 24 is inserted into the socket, the sloped portion 54 of its tapered nose 52 will come in contact with the sloped portion 56 of plunger 18, causing the end of the plunger 18 to rise from its seated position within the socket at one end. This expands snap ring 26, while snap ring 28 remains relatively unexpanded during this early stage of pin insertion. Thus, as the pin moves to the positon shown in Figure 2 during the early insertion stage, the only substantial force on the pin is that of the snap ring 26, and not that of snap ring 28. Furthermore, since the plunger is normally made of a plastic material, and in the preferred embodiment, polyethersulfone, having a very low coefficient of friction with respect to a metal pin contact, the frictional insertion forces are also kept at a minimum.Also, as can be seen in Figures 2 and 3, there is an opening 46 between shoulder 48 and end 58, thus providing a gap for airto escape from the cavity 22 of the connector to outside of the socket. Thus, as the pin is inserted into the socket, air will escape, further reducing air pressure insertion forces and thus the overall insertion forces are in the socket. Furthermore, as th pin contact is withdrawn, air is permitted to seep into the socket so that a vacuum is not created in the socket, thus making for ease of exit of the pin. When the pin is fully inserted in the socket as shown in Figure 3, the snap C-rings 26 and 28 exert equilibrium and well distributed forces on the pin, so that the electrical contact is evenly distributed through the pin and socket mating surface areas. This reduces the contact resistance in the connected assembly, thus alleviating the heating problems which have occurred in the prior art. The plunger 18 is made of a material, such as polyethersulfone, which is resistant to high temperature as well as low temperature, so it can be seen that there is provided a socket which has very low insertion forces, but provides a well distributed equilibrium of forces on the pin after full insertion of the pin.

From the foregoing description of the illustrated embodiment of the invention, it will be apparent that many modifications may be made therein. It will be understood, therefore, that this embodiment of the invention is intended as an examplification of the invention only, and that the invention is not limited thereto.

Claims (12)

1. A socket for an electrical connector, comprising an elongate substantially cylindrically shaped member, including one end adapted to be connected to an electrical conducto, and the other end having a pin receiving barrel member, the barrel member including a cavity therein and having an elongate slot along a portion thereof, wherein a plunger is received in a portion of the said slot, a part of the plunger extending into the said cavity prior to the insertion of a corresponding connector pin into the cavity, and wherein at least two spring members contact the plunger, whereby low insertion forces are capable of being provided on the pin during the insertion into the socket, and substantially balanced forces are capable of being provided on the pin after it is inserted into the socket.

2. A socket according to claim 1, wherein two spring members contact the plunger.

3. A socket according to claim 2, wherein a first of the spring members is arranged to provide low initial insertion forces on the said pin, and the first and second spring members together are arranged to provide higher substantially balanced forces on the pin.

4. A socket according to any preceding claim, wherein the plunger contacts the spring members on the outside of the socket, and is arranged to contact the pin on the inside of the cavity of the socket.

5. A socket according to any preceding claim, further comprising a recess for retaining the spring members and plunger assembly in the socket.

6. A socket according to any preceding claim, wherein the spring members are snap-rings.

7. A socket according to claim 6, further comprising grooves in the plunger for receiving the snaprings.

8. A socket according to claim 6 or 7, further including means for holding the snap-rings to the plunger.

9. A socket according to any preceding claim, wherein the plunger is made of a material having a low coefficient of friction, and thermal stability.

10. A socket according to any preceding claim, further comprising air-release means in the socket which are capable of further lowering insertion forces on the pin.

11. A socket for an electrical connector comprising an elongate substantially barrel-shaped member including one end adapted to be connected to an electrical conductor, and the other end having a pin receiving barrel member, the barrel memberinclud- ing a cavity therein and having an elongate slot along a portion thereof, wherein a plunger is received in a porton of the said slot, a part of the plunger extending into the said cavity prior to the insertion of a correspondng pin into the cavity, and wherein at least two C-clamp shaped spring members are attached to the plunger and surround the socket, whereby low insertion forces are capable of being placed on the pin by a first spring member as it is inserted into the socket and a substantially balanced force is capable of being provided on the pin by all the spring members after the pin is fully inserted into the socket.

12. A socket for an electrical connector, substantially as herein described with reference to the accompanying drawings.