ELECTRICAL SIGNAL GENERATOR AND LIQUID LEVEL INDICATOR

• US 3,646,293 A
• Filed: 04/06/1970
• Issued: 02/29/1972
• Est. Priority Date: 04/06/1970
• Status: Expired due to Term

• Current Assignee: William A. Howard
• Original Assignee: William A. Howard
• Inventors: Howard, William A.
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US05/025,818
• Time in Patent Office: 694 Days
• Field of Search: 200/84C,81.9M 335/207,211,301 73/313,314,308 29/607 315/5.35
• US Class Current: 200/84.00C
• CPC Class Codes: G01F 23/70 for sensing changes in level only at discrete points
• CPC Class Codes: H01H 36/02 actuated by movement of a float carrying a magnet
• CPC Class Codes: Y10T 29/49075 including permanent magnet or core

Abstract

One or more magnetically operable switches are each actuated a plurality of times by a series of actuating magnets moved past the switch or switches. The switches generate signals indicative of the movement of the magnets. A surface of each magnet that moves past the switch or switches includes a north and south pole portion, and like poles of successive magnets are adjacent each other to open the switches as well as close them under magnetic force. At each end of the series of switch-actuating magnets there is a magnet of lesser strength that constrains the field of each end magnet to a zone substantially equal to that of the intermediate magnets and prevents premature actuation of a switch as the magnets approach. A preferred circuit produces a separate electrical pulse each time a switch is opened and each time it is closed. In a particular application of the mechanism, the magnets are carried by a float in a liquid-containing vessel past stationary switches as the liquid level changes. Pulses produced by the switches indicate the position of the float.

Claims

1. A method o producing a plurality of electrical pulses from a magnetic switch including the steps of providing an aligned finite series of adjacent magnetic fields, each of a substantially equal first magnitude, with similar poles of the adjacent fields adjacent to each other, providing a magnetic field of smaller magnitude at each opposite end of the series with the polarity of each smaller magnitude field that is adjacent an end field of the series being the same as that at the adjacent end of the series, providing a magnetically operable switch having contact elements that can be magnetically moved together and apart by a magnetic field or fields, moving the series past the switch at a distance close enough that said series of magnetic fields of a first magnitude successively causes the switch to close and open and far enough away that the magnetic fields of smaller magnitude will not actuate the switches.

2. The method as set forth in claim 1 wherein a second magnetically operable switch is spaced from the first-mentioned magnetic switch along the path of movement of the series of magnetic fields, and including the step of closing said first-mentioned magnetically operable switch a number of times equal to the number of magnetic fields of said first magnitude in said series in response to movement of the series past said first-mentioned magnetic switch, each closing being in response to a finite distance of travel of the series, equal for each field, and therefore moving the series past said second magnetically operable switch and closing said second switch a number of times, the first closing thereof being in response to a distance of travel of the series after the last closing of said first-mentioned magnetically operable switch equal to said finite distance of travel.

3. A method of controlling magnetic fields of a series of magnetic fields of sufficient strength to actuate a reed switch when moved therepast along a predetermined path, including the steps of limiting the extent of the magnetic field at each end of the series in a direction along said predetermined path by applying a biasing magnetic field at each end of the series, with a like polarity opposing the the end polarity of the series and of insufficient strength to actuate the reed switch when moved therepast with said series but of sufficient strength to confiNe the effective extent of each field at the end of said series, in a direction along said path away from said series, to the distance the field extends along said path inwardly of the end of said series.

4. A method of producing digital output signals indicative of a change in liquid level in a vessel in response to movement of a float supported by liquid in the vessel, including the steps of providing a magnetically operable switch at a predetermined position, carrying a series of magnets for movement by said float past said switch and aligned in series in the direction of movement of the magnets, changing the level of liquid in the vessel, thereby moving the float relative to the vessel and the series of magnets past said switch, and producing an electrical signal each time one of said series of magnets moves past the switch, whereby a single switch indicates a plurality of incremental changes in the level in the vessel.

5. The method as set forth in claim 4 wherein a second magnetically operable switch is spaced from the said first-mentioned magnetic switch along the path of movement of the series of magnets, and including the step of first opening and closing the said first-mentioned magnetically operable switch a number of times equal to the number of magnets in said series in response to movement of the series past said first-mentioned magnetic switch, each actuation being in response to a finite distance of travel of the series, equal for each magnet, and thereafter moving the series past said second magnetically operable switch and opening and closing said second switch, the first actuation thereof being in response to a distance of travel of the series after the last actuation of said first-mentioned magnetically operable switch equal to said finite distance of travel.

6. A method of producing digital output signals indicative of a change in liquid level in a vessel in response to movement of a float supported by liquid in the vessel, including the steps of providing a plurality of magnetically actuatable switches at predetermined spaced positions, carrying a series of magnets for movement by said float past said switch and aligned in series in the direction of movement of the magnets, limiting the extent of the field of the magnet at each end of the series in a direction along the direction of movement of the magnets by applying a magnet field at each end of the series with a like polarity opposing the end polarity of the series and of insufficient strength to actuate said switches but of sufficient strength to limit the effective extent of the field of the adjacent end magnet of the series in a direction along the path of movement away from said series of magnets to the distance the field extends along the path of movement inwardly of the series, changing the level of liquid in the vessel, thereby moving the float and the series of magnets relative to the vessel and past said switches, producing at least one electrical signal each time one of said series of magnets moves past a switch, said switches being spaced relative to the dimension of the series of magnets considered in the direction of movement such that the first signal produced by a successive switch follows the last signal produced by the preceding switch in response to an increment of float movement equal to the increments that create successive signals from an individual switch.

7. The method as set forth in claim 6 including the steps of providing an electrical signal each time the float approaches an upper and lower limit of travel.

8. The method as set forth in claim 6 including the step of producing two electrical signals each time one of said series of magnets moves past a switch, one when the switch closes and one when it opens.

9. A liquid level indicator for use with a liquid-containing vessel, comprising a magnetically operable switch adapted to be fixed at a predetermined location with respect to a vessel for containing liquid and adapted to form a part of an electriC circuit whereby actuation of the switch will produce an electrical signal, a float adapted to be located within a liquid-containing vessel, movable with a change of liquid level past said switch, means to guide said float along a vertical path closely adjacent to said switch, and a plurality of similar switch-actuating magnets secured to and carried by the float for movement relative to said switch, said magnets being arranged one above another with surfaces that form magnetic pole portions aligned vertically and with like poles of each successive magnet adjacent, and of sufficient magnetic strength to actuate said switch when moved therepast.

10. A liquid level indicator as set forth in claim 9 including a second magnetically operable switch spaced a predetermined vertical distance from said first-mentioned magnetically operable switch along the path of said float provided by said guide means, said second switch being of identical construction to the first-mentioned switch and spaced therefrom such that the distance between corresponding parts of the successive switches along said path is equal to the height of the arrangement of said magnets.

11. A liquid level indicator as set forth in claim 10 including circuit means connected to said switch to produce a signal in response to a closing of the switch and a signal in response to the opening of the switch.

12. A liquid level indicator as set forth in claim 10 including an additional magnet above and below said plurality of switch-actuating magnets with surfaces that include magnetic pole portions aligned vertically with the similar surfaces of said switch-actuating magnets and with a like pole opposing the adjacent end pole of said plurality of switch-actuating magnets, said additional magnets having insufficient magnetic strength to actuate said switches but sufficient magnetic strength to limit the effective extent of the field of the adjacent end magnet of said plurality of switch-actuating magnets in a direction vertically inwardly of the arrangement thereof so that the field extends outward from each end of the arrangement substantially no further than it extends inward.

13. A liquid level indicator as set forth in claim 12 including a nonmagnetic spacer, thin with respect to the switch-actuating magnets, between each switch-actuating magnet and the next.

14. A liquid level indicator as set forth in claim 13 wherein all of the said magnets are annular and encircle said switches as they are moved adjacent said switches along said vertical path.

15. Apparatus for producing electrical signals in response to the movement of a member past a plurality of switches, comprising:

a plurality of magnetically operable switches spaced along a path of movement of a member, said switches being similar in construction each to the others, each having two contact elements extending in opposite directions from an area of mutual overlap, which elements can be magnetically moved together and apart as each becomes oppositely or similarly polarized relative to the other by a magnetic field or fields;

a plurality of switch-actuating magnets carried by said member, arranged in a series with surface portions of each magnet aligned with surface portions of the others in a direction along said path of movement of said member, which surface portions of each magnet include north and south polarities, the like polarities of adjacent magnets being adjacent each other and the switch-actuating magnets being of sufficient magnetic strength to actuate said switches when said member is moved along said path; and

an additional magnet above and below said switch-actuating magnets with surface portions that include north and south magnetic pole portions aligned with said surface portions of the switch-actuating magnets and with a like pole opposing the adjacent end pole of said plurality of switch-actuating magnets, said additional magnets having insufficient magnetic strength to actuate said switches when said member moves along its path, but sufficient magnetic strength to limit the effective extent of the field of the adjacent end magnet of said plurality of switch-actuating magnets outwardly from the end so that the field extends beyond the end of the aligned switch-actuating magnets substantially no further than it extends inward;

said magnetically operable switches being spaced each from the next a distance between corresponding parts thereof substantially equal to the distance that the switch-actuating magnets extend along said path.

16. Apparatus for indicating relative movement between magnets and switches, comprising:

a plurality of similar magnets each constructed with a north and south pole located in or along a common real or imaginary surface, said surfaces of all said magnets being arranged in a succession, at least one of the poles of each magnet being adjacent a like pole of a successive magnet, a plurality of magnetically operable switches arranged in a succession capable of being successively traversed by or of successively traversing said magnets, means for connecting said switches to an electrical circuit that is responsive to operation of said switches, and means to effect relative movement between said magnets as a group and said switches as a group.

17. Apparatus as set forth in claim 16 wherein said switches are spaced apart successively a distance such that only one switch is operated at a time by said magnets.