Removable magnetic zero/span actuator for a transmitter
AssigneeElsag International N.V.
InventorsJerome S. Alden, Victor J. Budan, Harold W. Thompson
Life of this patent
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Abstract
A magnetic actuator for adjusting the zero and span settings of a transmitter used in industrial process control systems. The actuator has a single magnet in a housing. The actuator is removable from the transmitter. When the actuator is unactuated the magnet is in a null position wherein it does not actuate either the zero or span setting reed switches. The magnet can be moved to either a first position wherein it actuates the zero setting reed switch or a second position wherein it actuates the span setting reed switch. The actuator applies a torque in the proper direction to return the magnet to the null position when the torque applied to move the magnet to either the first or second position is removed.
Claims20
An actuator external to a housing for magnetically actuating either a first or a second magnetically actuable switch internal to said housing;
- said actuator comprising:
- a. a single magnet mounted on a carrier which moves in response to a torque applied to said carrier;
- b. means connected to said carrier for applying said torque in either a first direction or a second direction to cause said carrier to move said magnet from a first position occupied by said carrier wherein said magnet cannot actuate either of said switches when said torque is not applied to said torque applying means to either a second position, which is not electrically connected to said first position, wherein said magnet is over said first switch to thereby actuate only said first switch or a third position, which is not electrically connected to said first position, wherein said magnet is over said second switch to thereby actuate only said second switch, said carrier moving from said first position to said second position in response to said first direction torque applied to said torque applying means, said carrier moving from said first position to said third position in response to said second direction torque applied to said torque applying means;
- c. means mounted on said carrier for returning said carrier to said first position from said second position when said first direction torque applied to said torque applying means is removed from said torque applying means and for returning said carrier to said first position from said third position when said second direction torque applied to said torque applying means is removed from said torque applying means;
- and
- d. an enclosure adapted for removable mounting to said housing, said enclosure containing said carrier and said means connected to said carrier for applying said torque, said enclosure including means for accessing said means connected to said carrier for applying said torque from outside of said enclosure.
An instrument comprising:
- a. a housing having first and second magnetically actuable switches internal to said housing;
- b. an actuator external to said housing for magnetically actuating either said first or said second magnetically actuable switch;
- said actuator comprising:
- i. a single magnet mounted on a carrier which moves in response to a torque applied to said carrier;
- ii. means connected to said carrier for applying said torque in either a first direction or a second direction to cause said carrier to move said magnet from a first position occupied by said carrier wherein said magnet cannot actuate either of said switches when said torque is not applied to said torque applying means to either a second position, which is not electrically connected to said first position, wherein said magnet is over said first switch to thereby actuate only said first switch or a third position, which is not electrically connected to said first position, wherein said magnet is over said second switch to thereby actuate only said second switch, said carrier moving from said first position to said second position in response to said first direction torque applied to said torque applying means, said carrier moving from said first position to said third position in response to said second direction torque applied to said torque applying means;
- iii. means mounted on said carrier for returning said carrier to said first position from said second position when said first direction torque applied to said torque applying means is removed from said torque applying means and for returning said carrier to said first position from said third position when said second direction torque applied to said torque applying means is removed from said torque applying means;
- and
- c. an enclosure removably mounted on said instrument housing, said enclosure containing said carrier and said means connected to said carrier for applying said torque, said enclosure including means for accessing said means connected to said carrier for applying said torque from outside of said enclosure.
Dependencies are inferred from the claim text.