Precision level measurement and control apparatus |
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| 申请号 | US3729667D | 申请日 | 1971-06-17 | 公开(公告)号 | US3729667A | 公开(公告)日 | 1973-04-24 |
| 申请人 | FIC IND INC; | 发明人 | TAYLOR W; | ||||
| 摘要 | The present system includes a plummet or weight which moves in response to gravity to come to rest on the top of the material, in the case of a granular or particulate solid, whose level is being measured, or to determine the upper surface, in the case of a liquid, whose level is being monitored. The plummet is connected to a support menas, such as a perforated tape, which in turn is coupled to drive a counter device. When the plummet stops moving downward the level can be read as a function of shaft position such as by a counter device, a shaft motion transmitter, pulser, or shaft encoder. In addition the support means is coupled to a take-up means which lifts the plummet upward in accordance with a periodic energization of the take-up means. The energization of the take-up means is controlled by a logic circuit which determines the period for the take-up action and the gravity probe. | ||||||
| 权利要求 | 1. A system for monitoring a level of material held in a receptacle comprising in combination: probe means; flexible support means comprising a perforated tape connected to support said probe means and formed to engage readout means; readout means engaged with said perForated tape driven directly in response to said probe means moving downwardly and upwardly in said receptable; take-up means coupled to said flexible support means and adapted to move said flexible support means in a first direction in said receptacle and alternatively to move said flexible support means in a second direction in said receptacle; brake means coupled to said take-up means to hold said take-up means stationary when said brake means is activated; and control circuit means for raising said probe means and lowering said probe means for level monitoring including first control circuit means including a first switching means connected thereto coupled to said take-up means and said brake means to enable said take-up means to move said flexible support means in a first direction until said first switching means is turned on responsive to a level condition to energize said first switching means which terminates the movement of said take-up means in said first direction whereby said readout means will make available the value of the level of the material being monitored when said probe is not moving in either said first or said second directions, and second control circuit means including a second switching means coupled to said take-up means and said brake means to enable said take-up means to move said flexible support means and said probe means in a second direction for a predetermined time until said second switching means is turned on thereby enabling the termination of the movement of said take-up means in said second direction and reversing the movement to a movement in said first direction. 2. A system for monitoring the level of material according to claim 1 wherein said flexible support means includes electrically conductive means and wherein said probe means is an electrically conductive means and is electrically connected to said flexible support means and wherein said take-up means includes means connecting said flexible support means to said first and second control circuit means. 3. A system for monitoring the level of material held in said receptacle according the claim 2 wherein said first switching means comprises a silicon controlled rectifier whose anode is connected to a first potential and whose control element is connected to said flexible support means and whose cathode is connected to said first switching means and wherein said housing means is connected to said first potential whereby when said probe means comes in contact with a conductive liquid said silicon controlled rectifier will be biased for conduction thereby energizing said first switching means. 4. A system for monitoring a level of material according to claim 3 wherein said first switching means is normally open and wherein said second control circuit includes a first capacitor connected through said last mentioned normally open circuit on one side and through a Zener diode and a second silicon controlled rectifier on said other side and wherein the anode of said last mentioned silicon controlled rectifier is connected to said second switching means whereby when said first switching means is energized said first capacitor commences to charge until such time as there is sufficient charge developed thereacross to cause a second silicon controlled rectifier to conduct by virtue of bias through said Zener diode, thereby energizing said second switching means. 5. A system for monitoring the level of material according to claim 4 wherein said take-up means includes a motor having at least first and second windings and a capacitor, said capacitor being connected to said first winding causing said motor to rotate in such a manner as to drive said probe downward and said capacitor connected to said second winding causing said motor to drive so as to pull said probe upward and wherein there is circuitry connected to said first and second windings including switching closures associated with said first and second switching means such that when neither switching means is energized said motor will be driving said probe downward and when said first switching means is energized certain of said switching closures associated therewith will be open and certain others will be closed to terminate said downward movement and simultaneously cause said brake means to hold said take-up means stationary and whereby when said second switching means becomes energized certain of said other switching closures will be open and certain of said other switching closures will be closed causing said motor to rotate so as to pull said flexible support means and said probe upwards. 6. A system for monitoring the level of material according to claim 1 wherein said first control circuit includes a first capacitor whose charge circuit passes through the normally closed closures of said second switching means and wherein said first switching means comprises a first silicon controlled rectifier connected to said first capacitor and to said first switching means such that when there is a sufficient charge developed on said capacitor said first silicon controlled rectifier will conduct thereby energizing said first switching means and wherein said second control circuit includes a second capacitor connected through the normally open closures of said first switching means and wherein said second switching means comprises a second silicon controlled rectifier connected to said second capacitor and further connected to said second circuit such that when said first switching means is energized thereby closing the said normally opened closures associated therewith said second capacitor will commence having a charge developed thereon and when said charge is sufficiently great said second silicon controlled rectifier will commence to conduct thereby energizing said second switching means which in turn causes said first mentioned normally closed closures to be open thereby de-energizing said first switching means. 7. A system for monitoring the level of materials according to claim 6 wherein said take-up means includes a motor having at least first and second windings and a capacitor, said capacitor connected with said first winding driving said motor in a direction to lower said probe and said capacitor connected to said second winding driving said motor in a direction to lift said probe and wherein there is circuitry connected to said first and second windings including normally closed closures of said first switching means whereby while said first capacitor is being charged said take-up means will rotate in a direction to lift said probe and whereupon the energization of said first switching means will open said last mentioned normally closed contacts permitting said take-up means to lower said probe by the force of gravity for as long a period of time as it takes to energize said second switching means. 8. A system for monitoring the level of materials according to claim 1 wherein said probe means includes a plunger means having a permanent magnet in the upper portion thereof and wherein said probe means further includes first and second reed switches disposed such that when said plunger comes in contact with the material to be monitored said plunger will advance into said probe in proximity of said first reed switch thereby closing the contacts of said first reed switch to activate said first switching means and whereby if the level of said material increases said plunger will advance further into said probe to close the contacts of said second reed switch thereby activating said second control circuit. 9. A system for monitoring the level of material according to claim 8 wherein said first switching means comprises a first silicon controlled rectifier whose control element and anode element are connected across said first reed switch and whose cathode is connected to said first switching means whereby when said first reed switch is closed said first silicon controlleD rectifier conducts thereby energizing said first switching means and whereby said second switching means comprises a second silicon controlled rectifier whose control element and anode are connected across said second reed switch and whose cathode is connected to said second switching means whereby when said second reed switch is closed said second silicon controlled rectifier conducts thereby energizing said second switching means. 10. A system for monitoring the level of material according to claim 9 wherein said take-up means includes a motor having first and second windings and a capacitor wherein said capacitor connected to said first winding will cause said take-up means to rotate in one direction and said capacitor connected to said second winding will cause said take-up means to rotate in a second direction and wherein there is circuitry connected to said first and second windings including normally open and normally closed closures of said first and second switching means such that when either switching means is energized said capacitor connected to said first winding of said motor will be energized to drive said probe downward and whereby when said first switching means is energized the movement of said take-up means downward will be terminated and said brake means will hold said take-up means stationary and whereby when said second switching means is energized said capacitor connected to said second winding will be energized to cause said motor to move upward and said brake means will be released to permit said movement. |
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