Electricity: circuit makers and breakers – Cam operates contact or microswitch – Peripheral cam
Patent
1998-01-08
1999-11-02
Friedhofer, Michael A.
Electricity: circuit makers and breakers
Cam operates contact or microswitch
Peripheral cam
200 17R, 200 4307, 200 6162, H01H 2700
Patent
active
059775009
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to switch assemblies used especially but not exclusively in machinery guards enclosing kinetic machinery.
2. Description of Related Art
Known switch assemblies comprise a switch adapted to be fitted to an enclosure and an actuator adapted to be fitted to a door, gate or protective cover of the enclosure and insertable into the switch. When the enclosure is closed by the door, gate or protective cover, the actuator is inserted into the switch which enables the energisation of a machine within the enclosure as the result of the switch turning on an electrical power supply.
Switches of this type have a housing in which are situated normally-open contacts, one set fixed, the other movable and carried by an axially-movable push rod spring-loaded to maintain the sets of contacts apart and the power supply consequently OFF.
The axially-movable push rod bears against a rotatable, can of a cam arrangement normally disposed to secure the push rod in a power supply OFF position but which is operable by the actuator to cause cam rotation and axial movement of the push rod to a power supply ON position.
BRIEF SUMMARY OF THE INVENTION
These known switches suffer from the disadvantage that should the enclosure and door become misaligned slightly the actuator is not able to enter the switch housing to operate the contacts when the door is closed.
It is an object of the present invention to provide a switch assembly in which such disadvantage is obviated or mitigated.
According to the present invention there is provided a switch comprising a housing containing electrical contacts movable from a power supply OFF position to a power supply ON position and a control mechanism operatively coupled to the contacts, the contacts being operable by an actuator of predetermined configuration engaging with the control mechanism to change the status of the contacts, characterised in that the control mechanism is moveable relative to the actuator in a direction transverse to the direction of insertion of the actuator to facilitate operative engagement therewith.
Hence if the actuator and control mechanism are misaligned, the control mechanism is moveable into alignment.
The control mechanism may be moveable along a predetermined axis and is conveniently biased to a predetermined position.
Preferably the control mechanism is biased to said predetermined position by means of compression springs located at each side thereof.
The control mechanism may be slidably mounted on a shaft.
Preferably the control mechanism has at least one entry port which is shaped to guide the actuator into operative engagement with the mechanism. The entry port may have a ramped guide surface around its periphery.
Preferably the guide surface is a raised profile defined on a casing in which the entry port is formed, which casing houses the control mechanism and is moveable with the control mechanism.
The control mechanism may comprise an actuating cam adapted to be rotated about a predetermined axis by the actuator in order to operate the contacts.
The actuating cam is preferably rotatably mounted on said shaft.
The control mechanism may have a locking member engageable with the actuating cam to prevent rotation thereof except when the actuator is inserted. dr
BRIEF DESCRIPTION OF THE DRAWINGS
A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which;
FIG. 1 is a front view of the switch with face plate removed to show a contact block and control mechanism with enclosure partially removed;
FIG. 2 is a partial sectional side view on the line II--II of FIG. 1; and
FIG. 3 is a view of an end face of an enclosure for the control device.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, the switch assembly comprises a switch A which contains an electrical contact arrangement B, an operating cam arrangement C, a connecting rod arrangement D, a solenoid operated lock E, and a
E. J. A. Engineering Limited
Friedhofer Michael A.
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