US3423704A

US3423704A - Electrical switching device using constricted fluid conducting path

Info

Publication number: US3423704A
Application number: US590988A
Authority: US
Inventors: Richard Brander
Original assignee: Beltone Electronics Corp
Current assignee: Beltone Electronics Corp
Priority date: 1966-10-31
Filing date: 1966-10-31
Publication date: 1969-01-21
Anticipated expiration: 1986-01-21

Description

Jan. 21, 1969 R. BRANDER 3,423,704 ELECTRICAL SWITCHING DEVICE USING CONSTRICTED FLUID CONDUCTING PATH Filed Oct. 31, 1966 I ,1 20 l l R/CHARD BRANDER BY v i h M) ATTORNEYS United States Patent ELECTRICAL SWITCHING DEVICE USING CON- STRICTED FLUID CONDUCTING PATH Richard Brander, Chicago, Ill., assignor to Beltone Electronics Corporation, a corporation of Illinois Filed Oct. 31, 1966, Ser. No. 590,988

US. Cl. 33547 8 Claims Int. Cl. H01h 29/00 ABSTRACT OF THE DISCLOSURE A switch comprising a rigid non-conducting envelope having a plurality of spaced-apart electrical terminals extending through its walls and an electrically conductive, non-wetting fluid partially filling its interior and in contact with said terminals. A rigid, electrically insulated actuating member is pivotally mounted within the envelope such that in one position a passage is provided for the fluid to form an electrically conductive path between the terminals and in another position the passage is constricted between the actuating member and the envelope to separate the fluid in non-contacting segments to break the electrically conductive path between the terminals.

This invention relates to an electrical switching arrangement wherein electrical connections are established through electrical conductive non-wetting fluids such as mercury.

US. Patent No. 3,177,327, which issued to Erwin M. Weiss on Apr. 6, 1965, discloses a fluid switch construction employing a sealed, deformable container partially filled with an electrically conductive, non-wetting fluid. When the vessel is deformed to constrict a fluid-holding passage between the terminals of the switch, the fluid physically separates to open the electrical circuit path.

The operation of the Weiss invention is based upon the interaction between surface tension forces and internal pressure forces within the deformable container and possesses numerous significant advantages. Undesirable contact openings and closures due to contact bounce (resulting from the elastic collision which takes place between the contacts in a mechanical switching device) are eliminated. Furthermore, the sealed fluid switch described in the above patent does not suffer from the effects of contact deterioration or the formation of contaminating films between the contacts. Moreover, the usual necessity for supplying substantial contact pressure in order to minimize contact resistance is eliminated.

Through extended use, the deformable portions of these prior fluid switches are subject to wear. In addition, a substantial portion of the energy which is required to actuate such a switch is consumed by the deformation of the vessel rather than by the actual separation of the mercury. Also in many applications it is desirable to have a switch which is hermetically sealed to prevent the passage of gaseous contaminants.

It is accordingly an object of the present invention to provide a fluid switch having the above numerated advantages but which does not require the deformation of the fluid container.

It is a further object of the invention to provide a fluid switch which requires the application of very little actuating energy in order to accomplish switching.

It is a further object of this invention to provide a fluid switch which can be operated in any position and which can be hermetically sealed against environmental contamination.

It is a still further object of the invention to provide a highly reliable fluid switch of exceedingly simple con- 3,423,704 Patented Jan. 21, 1969 ICC struction which is substantially free from the contact bounce effect.

In a principle aspect, the present invention takes the form of a fluid switch which includes a pair of electrically conductive contact terminals which are spaced apart within a passage defined by a hollow, rigid, electrically insulated envelope. According to a feature of the invention, a rigid, electrically insulated, actuating member is movably mounted within the passage and the passage is at least partially filled with an electrically conductive, non-wetting fluid. As contemplated by the invention, means are employed for moving the actuating member to constrict a portion of the passage such that the fluid separates into non-contacting physical segments thereby breaking the electrically conductive path through the fluid between the terminals.

In a preferred embodiment of the invention, the actuating member is constructed of magnetic material which may be coated with insulation and which is mounted within the passage for pivotal movement. An applied magnetic field may then be employed to accomplished switching.

These and other objects, features and advantages of the invention will become more apparent through a consideration of the following detailed description. In the course of this description, reference will frequently be made to the attached drawings in which:

FIGURE 1 is a top plan view of a single-pole, doublethrow switch cartridge embodying the principles of the invention;

FIGURE 2 is a side cross-sectional view of the switch cartridge taken substantially along the line 2-2 of FIG- URE l and showing an externally mounted, movable permanent magnet for actuating the switch cartridge; and

FIGURE 3 shows a side cross-sectional view of a second switch cartridge which embodies the principles of the invention and which is actuated by an associated electromagnet.

The top view of a switch cartridge employing the principles of the invention is shown in FIGURE 1. The cartridge includes a rigid envelope indicated generally at 11, three

electrical conductors

13, 15 and 17 which pass through the container, and a movable actuating member indicated generally at 19. The actuating member 19 includes

indentations

18 and 20 at its ends.

As most clearly seen in FIGURE 2, the floor of the vessel 11 is provided with a pair of raised

ribs

21 and 22 which extend into the interior hollow portion of the container 11 from the floor 23 of container 11. The

conductors

13, 15 and 17 are in the shape of strips and rest against the floor 23 of the container 11. With actuating member 19 in the position shown in FIGURE 2, the

strips

13 and 15 are electrically connected through the non-wetting electrically conductive fluid segment 25A. The strip 17 is in electrical contact with the fluid segment 25B. Fluid segments 25A and 25B partially fill the container 11. The remainder of the interior hollow portion of the container 11 (for example the region shown at 28) may be evacuated, gas-filled, or filled with a non-conductive liquid which is not miscible with mercury. The container 11 may be hermetically sealed to protect against atmospheric contamination.

The actuating member 19, which is coated with an insulating film indicated generally at 29, serves to make and break connections through the fluid 25. The member 19 conforms closely to each of the four side walls of the container 11 except for the passages provided by

indentations

18 and 20 as shown in FIGURE 1. Surface tension forces prevent the passage of the fluid 25 through the narrow gaps between member 19 and the inner walls of container 11 except at the passages provided by indentations 3 18 and 20. As seen in FIGURE 2, the bottom surface 30 of the actuating member 19 is substantially flat while the top surface comprises two

bevelled surfaces

31 and 32, the planes of which are at an angle to one another and which intersect along the fulcrum line 33.

The switch cartridge shown in FIGURE 2 is actuated by a pivotally mounted permanent magnet shown generally at 35 which rotates about fulcrum wire 38. In the position shown, the permanent magnet 35 has been rotated in a counterclockwise fashion about the fulcrum wire 38 to place the left-hand pole piece 39 in a position closely adjacent to the left-hand end 40 of the actuating member 19, causing the member 19 to pivotally rotate about the fulcrum line 33 such that bevelled surface 31 is flush against the inner surface of the roof 42 of the vessel 11. In this position, the bottom surface 30 of member 19 is spaced apart from the rib 21 to open a passage between the

conductors

13 and 15. Since this passage is filled with mercury segment 25A, a current carrying path is provided between conductors 13 and as illustrated by the dotted line 50. The rib 22 is in a position of engagement (or near engagement) with the bottom surface 30 of the actuating member 19 causing the mercury to separate into the spaced apart physical segments A and 25B. Accordingly, the circuit path which might otherwise exist between

conductors

15 and 17 is broken.

Downward movement of the right hand pole member 55 of magnet 35 causes the actuating member 19 to pivot in a counterclockwise fashion about fulcrum line 33 such that bevelled surface 32 is moved to a position of engagement with the inner surface 42 of the vessel 11. In this position, as will be readily understood, the fluid

passage connecting conductors

13 and 15 is constricted to separate the mercury and a fluid path is created between

conductors

15 and 17. It thus may be seen that an arrangement shown in FIGURES 1 and 2 constitutes a single pole, double throw, fluid switch.

The magnetic actuating member 19 need not be securely fixed at any point to the container 11, the magnetic attraction from the movable magnet 35 and the floating action contributed by the mercury segments 25A and 25B being sufficient to hold the actuating element in an upward position. If desired, of course, the actuating element 19 could be supported by a transverse fulcrum pin which engages with both the side walls of the container 11 and the magnetic actuating member 19.

FIGURE 3 of the drawings shows a further embodiment of the invention in which projecting

ribs

60 and 61 are included along the bottom surface 63 of an actuating member shown generally at 67. As before, the upper surface of the actuating member 67 is composed of two

bevelled walls

31 and 32 lying in planes at an angle to one another which intersect along a fulcrum line 33. Other portions of the arrangement shown in FIGURE 3 which are identical in placement and function to like elements in the cartridge shown in FIGURES 1 and 2 have been designated by the same numbers used earlier.

The switching arrangement shown in FIGURE 3 is actuated by a pair of magnetizing

windings

70 and 71. The magnetizing winding 70 is wound on a core 72 and is connected in series with a switch 74 across the terminals of the battery 75 while the winding 51, which is also wound on core 72, is connected in a series of a switch 78 across terminals of a battery 80. A permanent magnet 82 is positioned between

windings

70 and 71 against core 72. When the switch 74 is closed, current flowing in the winding 70 induces a strong magnetic field within the left hand side of core member 72 causing the actuating member 67 to rotate pivotally about the fulcrum line 33 to the position shown in FIGURE 3. In this position, a passage filled with the conductive fluid segment 25A exists between

conductors

13 and 15, electrically connecting these conductors. The ri-b member 61 constricts the passage between conductors 16 and 17, separating the mercury fluid into the two physically separated segments 25A and 25B as shown thereby breaking the circuit connection between

conductors

15 and 17.

When the switch 74 is opened, removing the applied magnetic field, the weaker magnetic field contributed by the permanent magnet 82 holds the actuating member 67 in the position shown. Thus, the arrangement of FIGURE 3 operates as a pulse operated latching switch which may be pulsed to cause switching but which does not require continued energization to maintain a switched condition.

It is to be understood that the embodiments of the invention which have been described are merely illustrative of applications of principles of the invention. Numerous modifications maye be made by those skilled in the art without departing from the true spirit and scope of the invention.

What is claimed is:

1. An electrical switch comprising, in combination, a rigid, non-conducting, sealed envelope, a pair of spacedapart, electrically conductive contact terminals passing through the walls of said envelope, an electrically conductive, non-wetting fluid partially filling the interior of said sealed envelope and electrically contacting said contact terminals, a rigid, electrically insulated actuating member completely enclosed within said sealed envelope, said actuating member being pivotally mounted for movement into either one of two positions within said envelope such that in one position a passage is formed in which the fluid forms an electrically conductive path between said contact terminals, and such that in another position the passage is constricted between the actuating member and a portion of said envelope to cause the fluid to separate into non-contacting physical segments to break the electrically conductive path, and means located outside of said sealed envelope and mechanically independent of said actuating member for causing said actuating member to be pivotally moved within said envelope between two said positions.

2. An electrical fluid switch as set forth in claim 1 wherein said actuating member is composed at least partially of magnetic material and wherein said means for moving said actuating member comprise means for subjecting said actuating member to a magnetic field.

3. A combination as set forth in claim 1 including a raised rib projecting from one interior wall of said envelope and positioned for cooperation with said movable actuating member to constrict said passage.

4. A fluid switch as set forth in claim 1 including a raised rib projecting from said actuating member and positioned for cooperation with an interior wall of said envelope to constrict said passage.

5. An electrical fluid switch as set forth in claim 2 wherein said means for subjecting said actuating member to a magnetic field comprises an electro-magnet positioned outside said envelope.

6. A single-pole, double throw switch comprising in combination, a rigid, non-conducting sealed envelope, first, second, and third spaced-apart electrically conductive contact terminals passing through the walls of said envelope, an electrically conductive, non wetting fluid partially filling the interior of said sealed envelope and electrically contacting said contact terminals, a rigid, electrically insulated actuating member completely enclosed within said sealed envelope, said actuating member being pivotally mounted for movement into either one of two positions within said envelope such that in one position a passage from the first contact terminal to the second contact terminal is constricted between the actuating member and a portion of the envelope to cause the fluid to separate into non-contacting physical segments for breaking the electrical conductive path therebetween while an electrical conductive path exists between the second and third contact terminals, and in a second position a passage from the second contact terminal to the third contact terminal is so constricted for breaking the electrical conductive path therebetween while an electrical conductive path exists between the first and second contact terminals, and means located outside of said sealed envelope and mechanically independent of said actuating member for causing said actuating member to be pivotally moved within said envelope between the two said positions.

7. An arrangement as set forth in claim 6 wherein said actuating member is at least partially composed of magnetic material and wherein said means for moving said actuating member comprises means for subjecting said member to a magnetic field.

8. An arrangement as set forth in claim 7 wherein said means for subjecting said member to a magnetic field comprises first and second electromagnets, said first electromagnet being positioned to pivot said member in a first sense when energized and said second electromagnet being positioned to pivot said member in the opposite sense when energized.

References Cited UNITED STATES PATENTS 2,750,466 6/1956 Patterson 200152.9 3,142,736 7/1964 Mitchell 335-52 3,198,911 8/1965 Mitchell 335-52 BERNARD A. GILHEANY, Primary Examiner.

HAROLD BROOME, Assistant Examiner.

US. Cl. X.R. 200-152