Contamination resistant push button switch

摘要

A switch suitable for use in contaminated environments provides for internal support of the operator allowing an oversized opening in the housing of the switch through which the operator extends. In this way contamination on the outer surface of the operator may be accommodated without a jamming of the operator in the retracted position.

主权项

1. An electrical switch comprising:
a housing providing an opening therein; electrical contacts held within the housing and communicating with conductors extending from the electrical contacts through the housing to connect to an external device; a switch operator shaft communicating with the electrical contacts for opening and closing the electrical contacts; a support structure positioned within the housing supporting the switch operator shaft with respect to the housing to be movable along an axis to project through the opening in the housing in an extended state and to retract at least in part into the housing in a retracted state, the support structure removed from the opening, the latter of which provides no support of the switch operator shaft; wherein the switch operator shaft has an outwardly exposed first radial extent about the axis smaller than the opening in the housing and that passes through the opening with movement of the switch operator shaft so that there is no contact between radially outer exposed surfaces of the switch operator shaft and either of the opening in the housing or other structure stationary with respect to the housing, when the switch operator shaft is in a retracted position and wherein a rear end of the switch operator shaft provides a radially extending collar of diameter greater than the first radial extent about the axis, the collar positioned within the opening and substantially filling the diameter of the opening when the switch operator shaft is in a fully extended position and retracting inside the housing, not filling the opening when the operator shaft is in the retracted position; wherein all radial outer surfaces of the switch operator shaft including the collar are removed from contact with the opening or other structure stationary with respect to the housing when the switch operator shaft is in the retracted position; and wherein the switch operator shaft includes an axial bore and wherein the support structure is a pillar extending along the axis and fitting slidably within the axial bore.