Claims
- 1. A proximity switch for starting and stopping electric pump motors comprising;
- a casing having a transverse wall to partially establish and separate a sealed inner chamber and a downwardly opening outer cylindrical chamber;
- an hermetically sealed, cylindrical reservoir in said inner chamber overlying said outer chamber and in coaxial alignment therewith, said reservoir being partially filled by conductive liquid and spaced from said outer chamber by an electrically insulating transverse dividing wall;
- an annular magnetic float having an axial central opening and normally supported on said conductive liquid;
- a first electrode on the cylindrical inner surface of said reservoir near the lower end thereof and thus normally contacting said conductive liquid;
- a second depending post-like electrode in said reservoir and having a contact portion normally positioned above the level of said conductive liquid and having a transverse dimension to fit within the central opening of said annular magnetic float;
- a magnetic actuating member supported for linear movement along the axis of said outer chamber between a lower switch-opening position spaced from said magnetic float and an upper switch-closing position in which said float is magnetically attracted to said actuator and in which said float and said actuator are magnetically retained against opposite sides of said transverse dividing wall to displace said conductive liquid upwardly in said reservoir to submerge the contact portion of said second electrode and thereby establish circuit continuity between said electrodes; and
- means to move said magnetic actuating member between said lower and upper positions in response to independent external liquid level variations and by magnetic attraction thereof with said magnetic float in the region of said upper position, whereby movement of such magnetic attraction will effect an essentially instantaneous displacement of said magnetic float.
- 2. The apparatus recited in claim 1 wherein said casing comprises molded non-magnetic impervious material having said transverse dividing wall as an integral portion thereof.
- 3. The apparatus recited in claim 1 wherein said actuating member moving means comprises a vertically movable linear member having an upper end to which said actuating member is fixed and extending downwardly out of said outer chamber, and float means supported on the portion of said linear member extending from said outer chamber.
- 4. The apparatus recited in claim 1 wherein said actuating member moving means comprises yieldable means supporting said actuator under a biasing force in a direction tending to move the actuator to said upper position.
- 5. The apparatus recited in claim 4 wherein said actuating member moving means further comprises a flexible line and a displacement weight supported by said line externally of said outer chamber, said yieldable means having a biasing force less than the gravitational force on said line and said displacement weight in air but more than the gravitational force thereof when submerged in water.
- 6. The apparatus recited in claim 4 wherein said actuating member moving means comprises a rod and wherein the biasing force of said yieldable means counterbalances the weight of said rod, thereby to enable snap-action movement of said actuator to said upper switch closing position.
- 7. A proximity switch comprising:
- a casing of molded non-magnetic impervious material comprising a dome-like body portion and a base portion sealed to said body portion, said base portion having an upstanding formation with an integral transverse wall portion, said transverse wall portion defining with said body portion an hermetically sealed inner chamber and with said upstanding formation, a downwardly opening outer chamber;
- a reservoir in said inner chamber in a position overlying said outer chamber and containing conductive liquid, said base portion having an integral upstanding wall portion to establish said outer chamber and said reservoir;
- a first electrode normally contacting said conductive liquid;
- a second electrode in said reservoir and having a contact portion normally positioned above the level of said conductive liquid;
- a magnetic float normally supported on said conductive liquid; and
- a magnetic actuating member supported for movement in said outer chamber between a normal lower position spaced from said magnetic float and an upper switch closing position in which said float is magnetically attracted to said actuator to displace said conductive liquid upwardly in said reservoir to submerge the contact portion of said second electrode and thereby establish circuit continuity between said electrodes.
- 8. The apparatus recited in claim 7 wherein said transverse wall portion is centrally disposed in said upstanding formation thereby to establish the bottom of said reservoir and the top of said outer chamber.
- 9. The apparatus recited in claim 7 wherein said reservoir depends within said outer chamber from said transverse wall portion and including a cup-shaped member for supporting said magnetic actuator.
- 10. The apparatus recited in claim 9 wherein said cup-shaped member is formed with an upper peripheral lip having a sealing means for engaging said transverse wall portion at the top of said outer chamber.
- 11. A proximity switch comprising:
- a casing having a transverse wall separating inner and outer chambers, said outer chamber having a generally central axis parallel with a normally vertical axis of said casing;
- a mercury switch capsule in said inner chamber, said capsule comprising a cylindrical shell of electrically conductive material having an axis aligned with the central axis of said outer chamber and partially filled with mercury, a magnetic float normally supported on the mercury, said magnetic float having a central axial opening and a cylindrical outer peripheral surface defining with said shell an annular clearance dimensioned to allow relative axial movement of said float and said shell but to impede passage of mercury between said float and said shell, a depending electrode supported on the axis of said shell to be aligned with said central axial opening and electrically insulated from said shell, the lower end of said depending electrode being normally spaced above the level of mercury in said capsule; and
- a magnetic actuating member supported for movement along the axis of said outer chamber between a lower switch-opening position spaced from said magnetic float and an upper switch-closing position in which said float is magnetically attracted to said actuator and in which said float and said actuator are magnetically retained against opposite sides of said transverse dividing wall to displace said mercury upwardly within said central float opening to submerge the lower end of said depending electrode and establish circuit continuity between said depending electrode and said shell.
- 12. The apparatus recited in claim 11 wherein said float is formed having an upper end shaped to define a concavity concentric with said central axial opening.
- 13. The apparatus recited in claim 12 wherein said concavity is of semi-spherical configuration.
- 14. The apparatus recited in claim 11 wherein said float has a lower end formed with depending leg-like protrusions to allow free flow of mercury under said lower end.
- 15. The apparatus recited in claim 11 wherein said magnetic float is formed of unmagnetized low-reluctance material and said actuating member is a magnet, and including a member of low-reluctance material fixed to said transverse wall between said actuator and said capsule.
- 16. The apparatus recited in claim 15 wherein said member of low-reluctance material comprises a disc in said inner chamber under said capsule.
- 17. The apparatus recited in claim 11 including means to move said magnetic actuating member between said lower and upper positions in response to independent external liquid level variations and by magnetic attraction thereof against said transverse wall to affect an essentially instantaneous displacement of said magnetic float.
- 18. The apparatus recited in claim 17 wherein said actuating member moving means comprises yieldable means supporting said actuator under a biasing force in a direction tending to move the actuator to said upper position, a flexible line depending from said actuator and a displacement weight supported by said line externally of said outer chamber, said yieldable means having a biasing force less than the gravitational force on said line and said displacement weight in air but more than the gravitational force thereof when submerged in water.
- 19. The apparatus recited in claim 17 wherein said magnetic float is formed of unmagnetized low-reluctance material and said actuating member is a magnet and including a disc of low-reluctance material under said capsule and aligned with the central axis of said outer chamber.
- 20. A mercury switch comprising:
- an hermetically sealed cylindrical shell of non-magnetic, conductive material containing mercury, an axial electrode supported by and electrically insulated from said shell, said axial electrode being concentric with said shell and extending downwardly to a contact end normally spaced above the level of mercury contained in said shell, an annular float normally buoyed by the mercury and having a central axial opening to receive said axial electrode, said float having an outer cylindrical surface defining with said shell an annular clearance dimensioned to allow relative axial movement of said float and said shell but to impede passage of mercury between said float and said shell, said float being formed of magnetic material; and
- actuating means spaced axially under said shell and operable to submerge said float by magnetic attraction to displace the mercury upwardly through said central axial opening into contact with the contact end of said axial electrode.
- 21. The apparatus recited in claim 20 wherein one of said float and said actuating means is a permanent magnet.
- 22. The apparatus recited in claim 21 wherein the other of said float and said actuating means is formed of unmagnetized low-reluctance material.
- 23. The apparatus recited in claim 20 wherein said float is formed of unmagnetized low-reluctance material and said actuator is an axially displaceable permanent magnet.
- 24. The apparatus recited in claim 21 including a transverse wall of non-magnetic, non-conductive material between said permanent magnet and said shell.
- 25. The apparatus recited in claim 24 including a member of magnetic material fixed in said wall and axially aligned with said shell and said actuator.
- 26. The apparatus recited in claim 20 wherein the dimensions of said float and said central opening, the quantity of mercury in said cylindrical shell and the position of said contact end of said axial electrode are related to develop a vertical displacement of mercury within said central axial opening sufficient to position the contact end of said axial electrode above the level of the mercury when said annular float is buoyed by the mercury and to displace the mercury upwardly through said central opening to a level above the contact end of said axial electrode when said shell is tilted to approximately 25.degree. from vertical.
- 27. The apparatus recited in claim 20 wherein the annular float is provided with an upper end shaped to define a concavity concentric with said central axial opening.
- 28. The apparatus recited in claim 27 wherein said concavity is of semi-spherical configuration.
- 29. The apparatus recited in claim 28 wherein said float has a lower end formed with depending leg-like protrusions to allow free flow of mercury under said lower end.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-in-Part of Copending Application Ser. No. 558,940, filed Mar. 17, 1975 now abandoned and entitled Liquid Level Responsive Proximity Switch.
US Referenced Citations (7)
Foreign Referenced Citations (2)
Number |
Date |
Country |
443289 |
Apr 1927 |
DE2 |
669932 |
Apr 1952 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
558940 |
Mar 1975 |
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