Seismic initiator for earthquake shutoff valves and the like
AssigneePaul D. Engdahl
InventorsPaul D. Engdahl, Roger P. Engdahl
Life of this patent
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Abstract
An acceleration-responsive magnetic device for closing a valve or operating a switch or the like in response to a disturbance such as an earthquake. A pendulum operates to increase the length of a magnetic path, releasing a magnetic element to perform the desired actuation.
Claims9
A seismic initiating device for holding a movable first magnetic element in a first position and releasing it to a second position upon receiving a predetermined magnitude and duration of acceleration, comprising:
- a pendulum having a mass and a connection therefrom to a second magnetic element, said second element being disposed in a rest position near said first element to hold it by magnetic attraction in said first position when said acceleration is absent;
- inertial forces on said mass causing angular displacement of said pendulum, said displacement moving said second element away from said first element and reducing said attraction to release said first element to said second position,
- said connection being constructed to permit a substantial initial displacement of said mass before said second element begins to move.
A seismic sensing device and initiator for holding a first magnetic element of a first predetermined diameter in a first position and effecting its release to a second position upon receiving a predetermined magnitude of acceleration, comprising
- a pendulum containing a second magnetic element of a second predetermined diameter and disposed to attract said first magnetic element to hold it in said first position in the absence of acceleration,
- said pendulum swinging in response to said acceleration to acquire a displacement from said first magnetic element to effect said release,
- said first and second diameters being substantially unequal whereby said displacement must exceed a predetermined initial magnitude before said release is effected, and
- means confining said pendulum to limit its angular displacement to insure its automatic return to said first position when said acceleration ceases.
Dependencies are inferred from the claim text.