1. Field of the Invention
This invention is related to electrical connectors and to strain reliefs for securing wires to the connector housing and preventing forces or vibrations on the wires from damaging the terminals or the contact interface between mating terminals.
2. Description of the Prior Art
Strain reliefs are commonly employed on electrical connectors to prevent damage to terminals and the contact interface between mating terminals. The simplest form of damage to terminals is the potential damage to a wire termination due to tension applied to the wire. A crimped termination can be damaged in this way and even if the damage is not visually noticeable, the gas tight connection between a terminal and a wire can be adversely affected. Oxides can form and eventually the contact between the terminal and the wire can deteriorate causing an increase in contact resistance and potentially even an open circuit, especially where tension is repeatedly applied to the termination.
Even where there is no physical damage to the termination between the wire and the contact terminal, vibration transmitted through the wires to the terminals can cause the mating interface between spring loaded mating contact terminals to be unstable or to degrade over time. Vibration can cause the contact point between mating terminals to shift slightly from a point where good metal to metal contact is obtained to a location where oxides have built up. Fretting corrosion can also result. For these and other reasons it is important that a strain relief be provided to isolate external forces from terminals and terminations.
Conventional strain reliefs are located on the rear of electrical connectors. In different applications the same connector may be used in some applications where the wires should exit to the side while in other applications the wires may exit to the rear of the connector. Therefore some conventional electrical connector strain reliefs have provided means for securing wires to the stain relief in at least three orientations. U.S. Pat. No. 4,080,035 is one example of an electrical connector in which cable ties can be used to secure wires to the strain relief.
U.S. Pat. No. 5,211,706 is another example of a prior art connector in which the wires can exit either to one side of the strain relief or through the rear of the strain relief housing. That strain relief comprises a top and bottom housing with one molded cable tie loop on the bottom half and another on the top half. For applications in which the wire is to exit through the rear a cable tie is inserted around the wires through the loop in the top housing half. For side entry applications, the cable tie is inserted through a loop adjacent the side of the bottom half.
A common problem with these and other prior art multi-exit strain reliefs is the relative size of the strain relief. In some cases, the strain relief occupies as much space as the connector itself. The strain relief may be wider than the connector or it can be longer than the connector. In each case large strain reliefs cannot be used in applications where space is at a premium, which is generally the case where side exit connectors are used.