US3571668A

US3571668A - Three-position solenoid actuated switch

Info

Publication number: US3571668A
Application number: US876512A
Authority: US
Inventors: Frank E Gray
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-11-13
Filing date: 1969-11-13
Publication date: 1971-03-23
Anticipated expiration: 1988-03-23

Abstract

A solenoid switch having first and second closed positions with an open position therebetween. A center-tapped coil is wound about a core capable of conducting a magnetic field. Direct current of one polarity is applied between the center tap and one coil end; direct current of the same polarity is applied between the center tap and opposite end. A three-position reed switch having a permanent magnet attached thereto is positioned adjacent the core. By the expedient of providing a reference impedance in series with the direct current between the center tap and one end of the coil and a comparison impedance between the center tap and the other end of the coil, the reed switch can be moved to any of its three positions.

Description

United States Patent [72] Inventor Frank E. Gray 2070 Lathan St. #10, Mountain View, Calif. 94040 [21] Appl. No. 876,512 [22] Filed Nov. 13, 1969 [45] Patented Mar. 23, 1971 [54] THREE-POSITION SOLENOID ACTUATED SWITCH 10 Claims, 3 Drawing Figs.

[52] U.S. Cl 317/150, 335/78, 310/674 [51] Int. Cl ..l-l0lh 51/22 [50] Field oi'Search 317/150, 123; 335/78, 177, 179, 153, 205; 310/674; 307/115, 116, 117, 125, 143

[56] References Cited UNITED STATES PATENTS 3,043,932 7/1962 Morris 317/150 Attorney-Townsend & Townsend ABSTRACT: A solenoid switch having first and second closed positions with an open position therebetween. A centertapped coil is wound about a core capable of conducting a magnetic field. Direct current of one polarity is applied between the center tap and one coil end; direct current of the same polarity is applied between the center tap and opposite end. A three-position reed switch having a permanent magnet attached thereto is positioned adjacent the core. By the expedient of providing a reference impedance in series with the direct current between the center tap and one end of the coil and a comparison impedance between the center tap and the other end of the coil, the reed switch can be moved to any of its three positions.

PATENTEU MR2 319m SHEET 1 BF 2 INVENTOR.

FRANK ELLIS GRAY FlG 2 ATTORNEYS THREE-PDSETEON SDLENOHD ACTHJA'EED SWllTClii This invention relates to solenoid switches and in particular to a solenoid switch having first and second closed positions with an open position therebetween.

Solenoid switches are frequently used in dual combinations to provide adjustment or positioning of thermostatic or rotary devices. For example, in many thermostat devices, one solenoid is used to actuate a heater when temperatures are too cool; another solenoid is sued to actuate a cooler or air conditioner when temperatures are too warm. As another example, in many rotary devices, one solenoid system is used to actuate rotation in one direction; another solenoid system is used to actuate rotation in an opposite direction.

In such dual solenoid systems, two disadvantages occur. First, there is a duplicity of coils, magnetically moved members and electrical contacts. Secondly, there is an ever present danger that paired solenoids will either be inadvertently actuated, lock, or jam to cause their connected devices to work in opposition to one another. In the case of a heater and air conditioner controlled by such dual solenoids, both the heater and air conditioner can be caused to work at the same time. in the case of a rotary control, the dual solenoids can malfunction to signal for rotation in both directions at the same time. Unfortunately, providing such systems with fail-safe connections to prevent such inadvertent opposing actuation, complicates such dual solenoid switch systems to the point where they are not practical.

Accordingly, an object of this is to provide a three-position solenoid switch having first and second electrically closed positions with a neutral position therebetween. A centertapped coil is wound about a core capable of conducting a magnetic field. By the expedient of serially connecting variable impedances in direct current circuits of opposite polarity between the center tap and each of the core a North-South polarity to a South-North polarity. A A reed switch is placed adjacent the core and the deflected reed of the switch provided with a magnet which can be repelled and attracted relative to the magnetic field emanating from the conductive core. When either the North-South or South-North magnetic field predominates, the reed is deflected to one of two closed positions; when the fields balance, the reed assumes a neutral position therebetween.

An advantage of this single solenoid switch is that it can be used to supplant conventional dual solenoid systems.

A further advantage of this switch is that as only one reed switch is used, the possibility of the dual functions of the control being actuated in opposition to one another is eliminated.

An additional object of this invention is to disclose a solenoid having two coil segments for producing opposing magnetic fields and a reed switch which is responsive to the predominating magnetic field only.

An advantage of these opposing magnetic fields is that the intensity of the magnetic fields produced by the coil segments are effectively compared, and the reed switch actuated by the predominating magnetic field only.

A further advantage of this invention is that even though the respective current flow in the coil segments vary considerably, the reed switch will only respond to the predominating magnetic field.

A further object of this invention is to disclose in combination with the three-position solenoid switch, a control for positioning rotary devices, which control does not include expensive master and slave armatures.

Other objects, features and advantages of this invention will become more apparent after referring to the following specification and attached drawings in which:

lFlG. i is a schematic view of the solenoid switch of this invention illustrating the placement of the center-tapped coil relative to an actuated reed switch;

H6. 2 is a schematic wiring diagram similar to HO. 1 illustrating a preferred winding of the coil segments for actuating the reed switch; and,

lF-lG. 23 illustrates the use of the three-position solenoid switch of this invention for the control of a rotating television antenna.

With reference to FIG. ll, core A is shown having a centertapped coil B wound thereabout. Direct current sources C of the same polarity provide opposing coil currents between each of the coil ends and an intermediate center tap. Connected in series with the direct current sources C are two variable impedances D.

As can be seen, when the impedance D and the current source C connected between one coil end and center tap varies with respect to the other impedance D and the other current source C connected between the other coil end and center tap, core A will receive magnetic fields of opposite polarities and differentintensities. For example, where the respective current sources C are of equivalent outputs and the left-hand impedance D is lower than the right-hand impedance D, center-tapped coil B will induce in core A a South- North polarity; alternately, where the right-hand impedance is less than the left-hand impedance, center-tapped coil B will induce in the core A a North-South polarity.

The magnetic field within core A operates to position reed switch E adjacent the end of the core. The central reed 16 of reed switch E has affixed to the end thereof a small permanent magnet F having a polarity aligned parallel to the longitudinal axis of the core. When the core is of a South-North polarity, the South-North position of the magnet F on reed switch E causes the switch to close toward core A connecting the input of the reed switch to output number 1. Alternatively, when the North-South polarity of core A predominates, magnet F on reed switch E will be repelled away from core A, connecting the input of the reed switch to-output number 2. As is apparent, where the respective magnetic fields of core A cancel one another, magnet F will neither be attracted nor repelled and reed switch E will assume a neutral position between the respective outputs causing an open circuit.

Core A is typically constructed of a material which will not retain magnetic polarity. Moreover, the core is either of laminated soft iron construction or alternately of powdered iron construction so as to provide a barrier against generation of heat inducing eddy currents therein. I Coil B has a helical winding of conventional insulated copper wire. This wire, wound from one end of core A to the opposite end of core A, is maintained equidistant with respect to the central axis of the core. At the approximate center of coil B, the coil is center tapped.

Regarding power supplies C, it is essential in the practice of this invention that power supplied to the coil be a direct current. Moreover, the magnetic field produced by the current between the center tap of the coil and one of its ends must always be opposite to the magnetic field produced by the current between the center tap and the other coil end.

Voltage supplies C used for this purpose can be virtually any type of DC power supply. As here illustrated, they are in the form of batteries. Alternately, a conventional DC power supply or supplies can be used.

impedances D can be of any variety. As shown in the schematic of FIG. 1, the impedances are produced by variable resistors or pots. Alternately, virtually any type of electrical resistance which will produce a variable impedance can be utilized. Typically, one or more of these resistors is connected so as to be operatively changed in impedance by the changing state of a control apparatus. Such connections, being well understood, are not shown in FlG. 1.

Reed switch E is of conventional configuration. Typically, four dielectric wafers 12 are maintained and clamped in coaxial relation on a shaft M with three metallic reeds l6 captured therebetween. As here shown, each of the metallic reeds 16 consists of a nonmagnetic elastic material and extends outwardly from the wafers l2 to a position where the ends of each reed 16 are aligned coaxially to the longitudinal axis of core A.

The ends of the respective reeds in are provided with electrical contacts. Typically, the two reeds 16 of switch E have copper coated wafers 20 attached thereto. These wafers are attached to their respective reeds so as to face inwardly and towards the central reed l6.

Central reed 16 has permanent magnet F attached thereto with its North-South field being substantially parallel to the axis of the core. This magnet, usually of an iron nickel alloy, is dipped in copper and thereafter silver tipped so as to provide an electrical contacting surface of high conductance.

The electrical switching connections of the solenoid are made through contact between the individual reeds. Typically, central reed 116 is connected to the input of the solenoid. The two outside reeds are connected to the respective outputs of the solenoid. As here shown, the outside reed 16 nearest core A is connected to output l. The outside reed furthest removed from core A is connected to output 2. Deflection of central reed 116 by the magnetic field of core A towards core A will cause a closed circuit between the input and output 1. Conversely, deflection of central reed l6 away from core A will cause a closed circuit between the input and output 2. Where the respective magnetic fields of core A are balanced and no magnetic field exists, central reed 16 will be in the neutral, undetlected position and the circuits between the input and outputs ii and 2 will be open.

The configuration of the coil B on core A as illustrated in FIG. ll has one disadvantage. It will. be noted that the righthand segment of coil B between the center tap and end is closer to reed switch E than the left-hand segment of coil B between the center tap and its respective end. Such a closer proximity of the right-hand segment of the coil to reed switch E permits the magnetic field generated therein to be conducted along a shorter segment of core A and to be communicated to reed switch E with fewer losses. As is apparent, this effect can be compensated for by reducing the number of winds on the right-hand segment relative to the number of winds on the left-hand segment of coil B. This reduction in the number of windings, however, has the disadvantage in that each switch produced according to this invention will require individual adjustment of its center tap.

Referring to FIG. 2, a configuration of the coil which does not require individual adjustment of its center tap is illustrated. Coil B, illustrated in FIG. 2 comprises two

helical windings

25 and 26. Typically, the two strands of the windings are simultaneously wound in side-by-side relation from one end of core A to the opposite end of core A. Both strands are given an equal number of windings about the core. Winding 25 is connected to first impedance D at one end of the paired windings.

At the opposite end of the paired windings, winding 25 is connected to ground. Winding 26 is connected to second impedance D at an end of the coil opposite to the point of connection between winding 25 and the first impedance D. At the opposite end, winding 26 is connected to ground. Thus it will be seen that winding 25 produces a magnetic field which opposes the magnetic field produced by winding 26.

The advantage of coil B, can be readily understood. Each winding 25 and 26 will extend over the same length of core A. Furthermore, core A will be required to conduct the magnetic field of each coil the same distance to reed switch E. Thus, no individual balancing of the coil length between the center tap and each of the coil ends is required in the embodiment of this solenoid as illustrated in FIG. 2..

it will be noted that the embodiment illustrated in FIG. 2 utilized only one direct current source C. As is apparent, this invention can utilize either a single current source or paired current sourcesone source connected to each coil segment.

The utility of the apparatus herein illustrated is believed apparent. One use of the solenoid herein illustrated has been found in the control of the rotation of a directional television antenna, as illustrated in FIG. 3. 3.

Referring to FIG. 3, a solenoid switch comprising a core A, center-tapped coil B and direct current power supplies C is shown connected in combination with a counterwound motor G to effect remote directional control of a television antenna 30. The directional control of antenna 30 is effected by the impedances Di and D2 connected across the center-tapped coil B.

The impedance D1 is connected in series with DC power supply C and the right-hand segment of center-tapped coil B. Positioning of the variable resistance of coil D1 permits the right-hand segment of coil B to have a reference magnetic field imparted thereto.

Impedance D2 is connected to and varied by the rotation of shaft 35 of counterwound motor G. As shaft 35 of counterwound motor G moves with the rotation of antenna 3b, impedance D2 will vary.

To effect rotation of counterwound motor G. the motor is connected to an alternating current source 40. Typically, one line of the alternating current source 410 is connected directly to one winding of counterwound motor G. The remaining line of the alternating current source is connected to the central reed 16 of reed switch E.

The operation of the antenna rotating circuit illustrated in FIG. 3 can be readily understood. Typically, impedance D1 is varied so as to unbalance the magnetic field generated through coil B. Thereafter, reed switch E will be deflected to connect the alternating current of AC power supply 40 through one winding or the other winding of counterwound motor G. When central reed 16 of reed switch E is deflected away from core A, the upper winding of counterwound motor G will be actuated causing antenna 30 to rotate in a counterclockwise direction. Alternately, when central reed lb of reed switch E is deflected towards core A, the lower winding of counterwound motor G will be actuated, causing counterwound motor G to rotate antenna 30 in a clockwise direction. As is apparent, a television viewer can effect remote rotation of the antenna 30 by positioning impedance Dl until counterwound motor G causes impedance D2 to match impedance D1, deflecting reed switch E to the neutral position.

It will be apparent, that positioning of antenna 30 could be provided by one or more impedances DI. For example, individual impedance D1 could be connected to a television channel selector. In each position of the television channel selector, the individual impedances D1 could be tuned for the optimum antenna position. With such an arrangement, when the channel selector was moved, the antenna 30 would be caused to rotate to the optimum pretuned position for each channel, thus effecting automatic antenna rotation without individual adjustment of the antenna by the viewer.

In the construction of this switch, it is important that it be isolated from ambient magnetic fields which could position the reed switch inadvertently. As the construction of such magnetic shielding is well understood, it will not be described herein.

Other applications in which the apparatus of this invention could be useful are believed apparent. For instance, in a thermostatic control wherein both an air conditioner and a heater are controlled, the solenoid could be of great use. In one position between the input and one of the outputs, the solenoid could actuate the air conditioner. In another position between the input and the remaining output the solenoid could actuate a heater. In the neutral position neither the air conditioner nor the heater would be actuated and the temperature would be the desired temperature. Changes in the desired temperature, of course, could be effected by varying one of the impedances. Likewise, while several embodiments of this invention have been shown and described, it will be apparent that other adaptations and modifications of this device can be made without departing from the true spirit and scope of this invention.

1 claim:

1. In a control system having a first impedance for indicating a desired controlled state and a second impedance for indicating the actual state of said system, the combination with said first and second impedances comprising: first and second coil segments wound about a common axis for inducing magnetic fields upon current flowing therethrough; at least one direct current supply means; a switch adjacent one end of said coil segments having a moving member thereof emanating a magnetic field polarized in axial alignment substantially parallel to the axial alignment of the fields of said coil segments,

said moving member being movable towards and away from said coil segments between at least two positions for said switch; connecting means for connecting one output of said direct current supply means for connecting one output of said direct current supply means to one end of said coil segments and the other output of said direct current generating means to the opposite end of said coil segments, each said connections to each said segments being in series with one of said impedances to produce opposing magnetic fields in said coil segments responsive to variations in said impedances, whereby said deflectable member of said switch will be positioned responsive to the predominating magnetic field of said coil segments.

2. The invention of claim 1 and wherein said switch comprises a reed switch having a deflectable reed; said reed having a permanent magnet attached thereto, which magnet emanates a magnetic field polarized axially to the axial length of said coil segments.

3. The invention of claim 1 and wherein said movable member is movable to an open position between said two closed positions.

4. The invention of claim 1 and wherein said coil segments are wound in helically side-by-side relation.

5. The invention of claim 1 and wherein said coil segments are wound about a core for conducting the magnetic field produced by said coil segments.

6. in combination: first and second coil segments wound about an axis for inducing magnetic fields polarized along said axis; at least one direct current generating means; first means connecting said direct current generating means to one coil segment for providing a magnetic field of a first polarity, and

second means connecting said direct current generating means to the other segment of said coil for providing a magnetic field of reverse polarity; a switch positioned in the magnetic fields of said coil segments, said switch including a movable member having motion towards and away from at least one electrically closed position positioned on either side of said deflectable member; a permanent magnet on said movable member of said switch having its North-South field axis aligned substantially parallel to the magnetic fields of said coil; a reference impedance connected in series with said connecting means and direct current generating means for producing a first current flow in one of said coil segments; and a comparison impedance connected in series with said connecting means and said direct current generating means for producing a second current flow in the other of said coil segments whereby said movable member of said switch will be deflected towards and away from said coil by the predominating magnetic field generated in said coil by said first and second currents.

7. The combination of claim 6 and wherein said switch is movable between an open position and two closed positions.

8. The invention of claim 6 and wherein said coil segments are provided from a single coil center-tapped.

9. The invention of claim 6 and wherein said switch comprises a reed switch having a deflectable reed with said magnet attached thereto.

10. The invention of claim 6 and wherein said coil segments are wound about a core for conducting the magnetic fields produced in said coil segments.

Claims

1. In a control system having a first impedance for indicating a desired controlled state and a second impedance for indicating the actual state of said system, the combination with said first and second impedances comprising: first and second coil segments wound about a common axis for inducing magnetic fields upon current flowing therethrough; at least one direct current supply means; a switch adjacent one end of said coil segments having a moving member thereof emanating a magnetic field polarized in axial alignment substantially parallel to the axial alignment of the fields of said coil segments, said moving member being movable towards and away from said coil segments between at least two positions for said switch; connecting means for connecting one output of said direct current supply means for connecting one output of said direct current supply means to one end of said coil segments and the other output of said direct current generating means to the opposite end of said coil segments, each said connections to each said segments being in series with one of said impedances to produce opposing magnetic fields in said coil segments responsive to variations in said impedances, whereby said deflectable member of said switch will be positioned responsive to the predominating magnetic field of said coil segments.

6. In combination: first and second coil segments wound about an axis for inducing magnetic fields polarized along said axis; at least one direct current generating means; first means connecting said direct current generating means to one coil segment for providing a magnetic field of a first polarity, and second means connecting said direct current gEnerating means to the other segment of said coil for providing a magnetic field of reverse polarity; a switch positioned in the magnetic fields of said coil segments, said switch including a movable member having motion towards and away from at least one electrically closed position positioned on either side of said deflectable member; a permanent magnet on said movable member of said switch having its North-South field axis aligned substantially parallel to the magnetic fields of said coil; a reference impedance connected in series with said connecting means and direct current generating means for producing a first current flow in one of said coil segments; and a comparison impedance connected in series with said connecting means and said direct current generating means for producing a second current flow in the other of said coil segments whereby said movable member of said switch will be deflected towards and away from said coil by the predominating magnetic field generated in said coil by said first and second currents.