Inductive proximity switch exhibiting magnetic field immunity
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
H02H-003/08
H01H-035/00
출원번호
US-0133755
(1987-12-16)
발명자
/ 주소
Groves, John P.
Lazzaro, Joseph
Nadolski, Gregory L.
Van Zeeland, Donald L.
출원인 / 주소
Eaton Corporation
대리인 / 주소
Lewis, J. G.
인용정보
피인용 횟수 :
5인용 특허 :
7
초록▼
A proximity switch assembly (10) for signaling the location of a movable member (36) at either of opposite end limits of movement relative to a stationary frame (44, 46) includes a compact elongate housing (58) adapted to be mounted on the frame to extend along the path of movement of a power driven
A proximity switch assembly (10) for signaling the location of a movable member (36) at either of opposite end limits of movement relative to a stationary frame (44, 46) includes a compact elongate housing (58) adapted to be mounted on the frame to extend along the path of movement of a power driven member (32), such as the piston rod of a hydraulic cylinder, which shifts the movable member between its end limits. The proximity switch is fixedly mounted in the housing and carries a switch actuating member (68) mounted for sliding movement over a relatively short distance sufficient to move an actuating target (74) into and out of actuating proximity of an air core proximity sensing coil (120) within the housing. Lost motion abutment shoulders (70, 72) on the switch actuation member and power driven member (54) move into engagement with each other as a power driven member approaches each end of its stroke.
대표청구항▼
1. A proximity switch for use with a power actuated device including a member mounted for movement between predetermined limits of travel, said switch comprising: means operative to change conductive state in response to a control signal; an air coil; means operative to electrically energize sa
1. A proximity switch for use with a power actuated device including a member mounted for movement between predetermined limits of travel, said switch comprising: means operative to change conductive state in response to a control signal; an air coil; means operative to electrically energize said air coil to establish a flux field having a characteristic amplitude thereabout entirely within the atmosphere surrounding said air coil, said atmosphere comprising a substantially air filled void without ferrous material components; target means displaceable between a position remote from said air coil and a sensed position adjacent said air coil to effect a change in said characteristic amplitude; circuit means operative to generate said control signal as a function of said change in characteristic amplitude; means for interconnecting said member and target means to effect a lost motion therebetween whereby said target means transitions between said remove and sensed positions only as said member alternately approaches said predetermined limits of travel; and means operative to shield said field from external sources of electromagnetic energy. 2. The switch of claim 1, wherein said shield means comprises a metallic housing substantially enclosing said air coil. 3. The switch of claim 2, wherein said interconnecting means carries said target means substantially within said housing. 4. The switch of claim 1, wherein said shield means comprises a metallic liner disposed within a nonmetallic housing, said liner and target means coacting to substantially enclose said inductive element. 5. The switch of claim 1, wherein said target means is constructed of ferrous material. 6. The switch of claim 1, wherein the dimensional spacing of said member limits of travel substantially exceeds the dimensional spacing of said target means remote and sensed positions. 7. The switch of claim 1, further comprising means for selectively varying said characteristic amplitude independent of the position of said target means. 8. The switch of claim 2, wherein said air coil is generally disposed about a principle axis and said target means comprises a generally planar ferrous metal member displaceable along said axis. 9. The switch of claim 8, wherein said coil and target member are generally dimensionally coextensive on respective planes normal to said axis. 10. A proximity switch for use with a power actuated device including a member mounted for movement between predetermined limits of travel, said switch comprising: means operative to change conductive state in response to a control signal; an air coil; means operative to electrically energize said air coil to establish a flux field having a characteristic amplitude thereabout entirely within the atmosphere surrounding said air coil said atmosphere comprising a substantially air filled void without ferrous material components; target means displaceable between a position remote from said air coil and a sensed position adjacent said air coil to effect a change in said characteristic amplitude; circuit means operative to generate said control signal as a function of said change in characteristic amplitude; means for interconnecting said member and target means to effect a lost motion therebetween whereby said target means transitions between said remote and sensed positions only as said member alternately approaches said predetermined limits of travel; and means operative to sense current flowing through said means operative to change conductive state when in a closed state and to generate an overload current condition signal when said sensed current exceeds a predetermined level, said overload current condition signal being operative to change said conductive state changing means to an open state. 11. The switch of claim 10, further comprising means operative to generate a user sensible signal in response to said overload current condition signal. 12. The switch of claim 1, further comprising means operative to generate a user sensible signal as a function of the conductive state of said means operative to change conductive state. 13. In combination: a power actuated device including a rigid member mounted within a fixed frame for movement along a fixed path relative to said frame between a first end limit of travel and a second end limit of travel, power actuated means for driving said rigid member in either direction from one of said end limits to the other; and a proximity switch for signaling the arrival of said member at either of said end limits, said switch comprising, means operative to change conductive state in response to a control signal, an air coil, means operative to electrically energize said air coil to establish a flux field having a characteristic amplitude thereabout entirely within the atmosphere surrounding said air coil, said atmosphere comprising a substantially air filled void without ferrous material components, target means displaceable between a position remote from said air coil and a sensed position adjacent said air coil to effect a change in said characteristic amplitude, circuit means operative to generate said control signal as a function of said change in characteristic amplitude, means for interconnecting said member and target means to effect a lost motion therebetween whereby said target means transitions between said remote and sensed positions only as said member alternately approaches said first and second end limits of travel, and means operative to shield said field from external sources of electromagnetic energy. 14. The combination of claim 13, wherein said power actuated device comprises a fluid driven cylinder. 15. The combination of claim 14, wherein said fluid driven cylinder comprises a hydraulic cylinder. 16. The combination of claim 14, wherein said fluid driven cylinder comprises a pneumatic cylinder. 17. In combination: a power actuated device including a rigid member mounted within a fixed frame for movement along a fixed path relative to said frame between a first end limit of travel and a second end limit of travel, power actuated means for driving said rigid member in either direction from one of said end limits to the other; and a proximity switch for signaling the arrival of said member at either of said end limits, said switch comprising, means operative to change conductive state in response to a control signal, a housing fixedly mounted upon said frame in surrounding relationship to a slot extending through said frame along said fixed path, an air coil fixedly mounted in said housing, means operative to electrically energize said air coil to establish a flux field having a characteristic amplitude thereabout entirely within the atmosphere surrounding said air coil within said housing, said atmosphere comprising a substantially air filled void without ferrous metal components, a proximity switch target member mounted in said housing for sliding movement parallel to said path between a first position wherein said target member is within actuating proximity of said air coil and a second position wherein said target member is out of actuating proximity to said air coil by effecting changes in said characteristic amplitude, circuit means operative to generate said control signal as a function of said change in characteristic amplitude, first abutment means on said rigid member, second abutment means on said target member, one of said abutment means comprising means on one of said members defining an elongate recess terminating at opposite ends in abutment shoulders normal to said fixed path and the other of said abutment means comprising a projection on the other of said members projecting from said other of said members normal to said fixed path through said slot in said frame into the recess of said one of said members between said abutment shoulders, said shoulders being spaced from each other by a distance such that upon movement of said rigid member to said first end limit one of said shoulders engages said projection and pushes said target member into said first position and upon movement of said rigid member to said second end limit the other of said shoulders engages said projection and pushes said target member into said second position, and means operative to shield said field from external sources of electromagnetic energy. 18. The combination of claim 17, wherein said power actuated device comprises a double-acting fluid driven cylinder.
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