Resettable switching device
AssigneeTripco Limited
InventorPatrick Ward
Life of this patent
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Abstract
A resettable switching device, e.g. a relay, comprises a fixed contact (18) and a movable contact (28). A solenoid (12) is fixed relative to the fixed contact and a ferromagnetic plunger (20) carries the movable contact. A spring (24) biases the plunger away from the fixed contact so the device is normally open. When the device is set a further ferromagnetic element, e.g. a plunger (22), holds the first plunger (20) in a closed-contact position by magnetic attraction against the action of the spring (24). When a predetermined current condition exists in the solenoid the magnetic attraction between the element and plunger is reduced below the level necessary to hold the plunger so that the movable contact disengages the fixed contact.
Claims13
A resettable switching device comprising a solenoid for mounting with its axis substantially perpendicular to a circuit board, a movable contact closure member having a pair of arms which extend along opposite sides of the solenoid, each arm being arranged to bring a movable contact into engagement with at least one respective contact fixed to the circuit board adjacent to the solenoid, a first ferromagnetic element, a resilient biasing means for biasing the contact closure member towards a first position wherein the movable contacts do not engage the fixed contacts, and a second ferromagnetic element for drawing the first element to and holding it in a second position by magnetic attraction against the action of the resilient bias, the movable contact engaging the fixed contact in the second position of the first element, wherein when a predetermined current condition exists in the solenoid the magnetic attraction between the second element and the first element is reduced below the level necessary to hold the first element in the second position so that the first element is released by the second element and moves towards the first position under the action of the resilient bias and the movable contact disengages the fixed contact, wherein one end of the solenoid is fixedly mountable to the circuit board, the movable contact closure member is disposed at the opposite end of the solenoid to the said one end, and the movable contact closure member includes the first ferromagnetic element.
Dependencies are inferred from the claim text.