LINEAR PUSH PLUNGER ELECTRICAL SWITCH WITH TUBULAR SHROUD ARC PREVENTION MEANS
United States Patent 3699276
An insulated body defines a longitudinal cavity about an axis. A contact carrier moves axially within said cavity in the manner of a piston and defines compartments at opposite sides thereof. The carrier is electrically conductive and has contacts diametrically positioned. In each compartment there are two fixed contacts aligned with the movable contacts and actuating means is operatively connected to the contact carrier. This operating means includes springs at each side of the carriers and insulating members that shroud the springs as contact separation takes place in either direction.
US Patent References:
Brake switch
Earlywine, Jr. et al. - October 1968 - 3408464
Ignition system
King - March 1937 - 2072112
Contact device for electric circuits
Rosen - April 1953 - 2634341
Plunger operated brake type switch
Long - May 1964 - 3134004
Brake switch
Earlywine, Jr. et al. - October 1968 - 3408464
Ignition system
King - March 1937 - 2072112
Contact device for electric circuits
Rosen - April 1953 - 2634341
Plunger operated brake type switch
Long - May 1964 - 3134004
Application Number:
05/131370
Publication Date:
10/17/1972
Filing Date:
04/05/1971
View Patent Images:
Export Citation:
Assignee:
Appleton Electric Company (Chicago, IL)
Primary Class:
Other Classes:
218/60, 200/508, 200/534
International Classes:
H01H13/02; H01H33/91; H01H33/88; H01H15/10; H01H33/06
Field of Search:
200/16A,19A,30,82B,82D,148A,15G,159R,165
Primary Examiner:
Scott J. R.
Claims:
I claim
1. In a compact electrical switch comprising a tubular housing of insulating material and defining an internal cavity having a longitudinal axis, two fixed contacts at opposite sides of said axis respectively and facing one end of said cavity, a moving contact bridge between said contacts and said end and movable in an axial direction in said cavity, said bridge having contacts thereon aligned with and bearing against the respective fixed contacts, and switch actuator means operatively associated with said bridge for moving said bridge in an axial direction to move the bridge contacts away from the fixed contacts, the improvement wherein said actuator means comprises:
2. In a compact electrical switch comprising a tubular housing of insulating material and defining an internal cavity having a longitudinal axis, two fixed contacts at opposite sides of said axis respectively and facing one end of said cavity, a contact bridge between said fixed contacts and said end and movable in an axial direction in said cavity, said bridge having contacts on one side thereof, aligned with and bearing against the respective fixed contacts, means including a spring extending along said axis and having one end bearing against said one side of the bridge and a second end bearing against said housing at the other end of the cavity to resiliently urge said bridge contacts away from said fixed contacts, a portion of said spring being diametrically between the fixed contacts, and a switch actuator device operatively associated with said bridge for moving said bridge in an axial direction toward said one end of said cavity to move the bridge contacts away from the fixed contacts, the improvement comprising:
3. In a switch as set forth in claim 2, wherein said bridge contacts are electrically connected to each other, and said means extending along said axis includes a pressure member of insulating material, said pressure member being between the spring and the bridge with one end thereof being in contact with the bridge, the other end of the pressure member having a skirt defining a cavity into which an end part of the spring extends, said skirt forming said insulating shroud.
4. In a switch as set forth in claim 3, wherein said actuator device includes an axially positioned plunger having an end adjacent the other side of the bridge, said end having a cavity therein with a skirt therearound, said plunger being movable axially, an axially positioned spring bearing against the other side of the bridge and extending into said plunger cavity and bearing against the plunger, said switch including a second pair of fixed contacts spaced from said other side of the bridge, and a second pair of bridge contacts on said other side of the bridge.
5. In a switch as set forth in claim 2, wherein said actuator device includes an axially positioned plunger having an end adjacent the other side of the bridge, said end having a cavity therein with a skirt therearound, said plunger being movable axially, an axially positioned spring bearing against the other side of the bridge and extending into said plunger cavity and bearing against the plunger, said switch including a second pair of fixed contacts spaced from said other side of the bridge, and a second pair of bridge contacts on said other side of the bridge.
6. In a compact electrical switch comprising a tubular housing and defining an internal cavity having a longitudinal axis, a first pair of fixed contacts one location along said axis, a second pair of fixed contacts at another location along said axis, a bridge positioned between said two pairs of fixed contacts and having contacts thereon electrically connected to each other, said bridge being movable between a first position at which the bridge contacts are against one pair of fixed contacts and form an electrical circuit therebetween and a second position at which the bridge contacts are against the other pair of fixed contacts and form an electrical circuit therebetween, and actuating means bearing against the bridge for moving the bridge from said first to said second position and from said second position to said first position, said actuating means including two springs, one of said springs having at least a portion thereof at one side of said bridge and between said one pair of contacts, the other of said springs having at least a portion thereof at the other side of the bridge and between said other pair of contacts, the improvement wherein said actuating means includes:
1. In a compact electrical switch comprising a tubular housing of insulating material and defining an internal cavity having a longitudinal axis, two fixed contacts at opposite sides of said axis respectively and facing one end of said cavity, a moving contact bridge between said contacts and said end and movable in an axial direction in said cavity, said bridge having contacts thereon aligned with and bearing against the respective fixed contacts, and switch actuator means operatively associated with said bridge for moving said bridge in an axial direction to move the bridge contacts away from the fixed contacts, the improvement wherein said actuator means comprises:
2. In a compact electrical switch comprising a tubular housing of insulating material and defining an internal cavity having a longitudinal axis, two fixed contacts at opposite sides of said axis respectively and facing one end of said cavity, a contact bridge between said fixed contacts and said end and movable in an axial direction in said cavity, said bridge having contacts on one side thereof, aligned with and bearing against the respective fixed contacts, means including a spring extending along said axis and having one end bearing against said one side of the bridge and a second end bearing against said housing at the other end of the cavity to resiliently urge said bridge contacts away from said fixed contacts, a portion of said spring being diametrically between the fixed contacts, and a switch actuator device operatively associated with said bridge for moving said bridge in an axial direction toward said one end of said cavity to move the bridge contacts away from the fixed contacts, the improvement comprising:
3. In a switch as set forth in claim 2, wherein said bridge contacts are electrically connected to each other, and said means extending along said axis includes a pressure member of insulating material, said pressure member being between the spring and the bridge with one end thereof being in contact with the bridge, the other end of the pressure member having a skirt defining a cavity into which an end part of the spring extends, said skirt forming said insulating shroud.
4. In a switch as set forth in claim 3, wherein said actuator device includes an axially positioned plunger having an end adjacent the other side of the bridge, said end having a cavity therein with a skirt therearound, said plunger being movable axially, an axially positioned spring bearing against the other side of the bridge and extending into said plunger cavity and bearing against the plunger, said switch including a second pair of fixed contacts spaced from said other side of the bridge, and a second pair of bridge contacts on said other side of the bridge.
5. In a switch as set forth in claim 2, wherein said actuator device includes an axially positioned plunger having an end adjacent the other side of the bridge, said end having a cavity therein with a skirt therearound, said plunger being movable axially, an axially positioned spring bearing against the other side of the bridge and extending into said plunger cavity and bearing against the plunger, said switch including a second pair of fixed contacts spaced from said other side of the bridge, and a second pair of bridge contacts on said other side of the bridge.
6. In a compact electrical switch comprising a tubular housing and defining an internal cavity having a longitudinal axis, a first pair of fixed contacts one location along said axis, a second pair of fixed contacts at another location along said axis, a bridge positioned between said two pairs of fixed contacts and having contacts thereon electrically connected to each other, said bridge being movable between a first position at which the bridge contacts are against one pair of fixed contacts and form an electrical circuit therebetween and a second position at which the bridge contacts are against the other pair of fixed contacts and form an electrical circuit therebetween, and actuating means bearing against the bridge for moving the bridge from said first to said second position and from said second position to said first position, said actuating means including two springs, one of said springs having at least a portion thereof at one side of said bridge and between said one pair of contacts, the other of said springs having at least a portion thereof at the other side of the bridge and between said other pair of contacts, the improvement wherein said actuating means includes:
Description:
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to switches that are classified as the "heavy duty" type. For example, the standards of the Underwriters Laboratories state that at 110-120 volts A.C. a switch must be able to handle normal current of 6.0 amps and a current inrush of 60 amps (with proportionately lower amperage ratings at higher voltage ratings) to be classified as a heavy duty switch. When handling this type of load, there is a tendency for an arc to establish between the fixed and movable contacts as contact separation occurs. This has necessitated a spacing of parts in a manner such that a permanent arc does not occur between two metal components within the switch. The result has been that heavy duty switches conventionally are rather bulky. When considering a conventional switch box, for example, it has been possible only to put a single heavy duty switch in any transverse plane of the box. There are many applications in which it would be very desirable to get more switches in a single box.
The principal object of the present invention is to achieve a reduction in size of an electrical switch within the heavy duty category so as to make available the ability to get more switches into a particular volume. Thus, for example, it is possible to put two of the switches of the present invention side by side within the transverse plane of the conventional switch box. Size reduction is, in part, achieved by providing a relatively long path between contacts of opposite polarity as the contacts separate while still maintaining the advantages of spring mounting of the contact carrier so as to insure good contact seating.
Further objects and advantages will become apparent from the following description.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal section through an embodiment of the invention;
FIG. 2 is a transverse section taken at line 2--2 of FIG. 1;
FIG. 3 is a transverse section taken at line 3--3 of FIG. 1;
FIG. 4 is a partial section viewed as in FIG. 1, but illustrating one stage of the switch operation;
FIG. 5 is another partial section viewed the same as FIG. 1, but illustrating another stage in the switch operation;
FIG. 6 is a partial section as seen at line 6--6 of FIG. 3; and
FIG. 7 is a view of an alternative movable contact.
DESCRIPTION OF SPECIFIC EMBODIMENTS
The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.
The switch body is defined by an insulating housing 10 threaded to a metal housing 11. There is an enclosed internal cavity 12 which, for all practical purposes, is defined by the insulated housing 10. Molded into the base end 13 of the insulated housing are a pair of electrical conductors which at the cavity end define fixed contacts 14 and 15. These conductive members are internally threaded to receive screws 16 and 17 for attaching wires to be in electrical connection with the respective contacts. In an axial plane 90° from that of the diametrically opposed contacts 14 and 15 are a pair of conductive posts 20 and 21. These posts are embedded in portions 22 and 23 of the material from which the housing 10 is formed. The screws 24 and 25 threaded into the top of posts 20 and 21 hold contact arms 26 and 27 thereon. At the ends of arms 26 and 27 are contacts 28 and 29. At the external end of posts 20 and 21 are screws such as 30 for attaching wires.
An electrically conductive contact bridge or carrier 33 extends transversely to the axis of cavity 12 and divides that cavity into two chambers 34 and 35. At the end of one of these chambers are the fixed contacts 28 and 29, while at the end of the other chamber are fixed contacts 14 and 15. The periphery 36 of the carrier is immediately adjacent the internal wall 37 of the housing that defines cavity 12 with only a relatively small space therebetween. Thus, as the carrier 33 moves in an axial direction within the cavity it functions as a piston. For example, as it moves downwardly in FIG. 1 it compresses the air (fluid) in chamber 35 and decreases the air pressure in chamber 34. Movable contacts 38 and 39 are diametrically opposed on carrier 33. The carrier 33 provides an electrical connection between the two contacts 38, 39.
The operating apparatus for the switch comprises an external plunger 41 coupled to an internal plunger 42. Plunger 42 is of an insulating material and defines an internal chamber 43 in the end facing carrier 33 with the walls thereabout being a skirt forming a shroud. A second insulating plunger 44 (serving as a pressure member) has a stud 45 which projects through carrier 33 and an internal chamber 46 on the opposite end and facing end wall 13 of the housing thus, the wall of the plunger 44 about the chamber 46 is a skirt forming a shroud. A spring 47 has one end in chamber 43 and abutting the insulated plunger 42 with the other end slipped over stud 45 and abutting carrier 33. A second spring 48 abuts end 13 of the housing, extends within chamber 46 and abuts the insulated plunger 44. The spring 48 is stronger than the spring 47. However, the two springs permit the carrier 33 to float so as to insure a good electrical connection between the movable contacts and the fixed contacts which the movable contacts are against.
The contacts 28 and 29 would function as normally closed contacts, and the contacts 14 and 15 would function as normally open contacts. Thus, in the absence of disturbing forces, the movable contacts 38, 39 are against fixed contacts 28, 29, as illustrated in FIG. 1.
To initiate a switching operation, the plunger 41 is pushed axially in an inward direction. During the first stage of this movement the spring 47 collapses (it being weaker than the spring 48). Thus, the insulated plunger 42 moves down so that its end contacts the carrier plate 33, as illustrated in FIG. 4. In this position the insulated plunger 42 serves as a shroud for spring 47 and increases the effective distance in air between the contacts 28 and 29. Thus, as the movable contacts separate, and if an arc develops, that arc will not bridge the space between the contacts 28, 29, which would be an extremely undesirable condition. Furthermore, as the carrier 33 moves downwardly from the FIG. 4 position the air in chamber 35 is compressed (by the piston action) and flows about the periphery 36 of the carrier. This periphery is immediately adjacent the contacts 38, 39 so that the comparatively cool air from chamber 35 that is pumped about the periphery of the carrier serves to cool arcs that may exist between the movable contacts and the fixed contacts thereby aiding in extinguishing those arcs.
FIG. 5 illustrates the position of the carrier 33 when it is serving to establish electrical contact between the two fixed contacts 14 and 15. This condition will be stable so long as the plunger 41 remains pushed in as far as it will go. Again, the springs 47, 48 permit the carrier to float so that good electrical contact is established between the two movable contacts and the two respective fixed contacts. If plunger 41 now is released, carrier 33 will commence to move upwardly from the FIG. 5 position. Again, the insulated plunger 44 serves as a shroud for the spring 48 at the time of initial separation and thus increases the effective distance between the diametrically opposed contacts so that an arc will not jump between them. At the same time, the carrier 33 serves as a piston to compress the air in chamber 34 so that it flows about the periphery of the carrier and across the contacts to aid in extinguishing any arcs.
FIG. 7 illustrates an alternative embodiment in which there is a carrier 33' having its periphery 36' in contact with wall 37' to more effectively serve as a piston. In this embodiment there is an opening 50 axially through the movable contact 38' to serve as fluid communication between the chambers 34 and 35. Thus, as the carrier 33' is moved axially, as indicated by arrow 51, the air is pumped across the carrier through the opening 50 to aid in extinguishing the arc.
The present invention relates to switches that are classified as the "heavy duty" type. For example, the standards of the Underwriters Laboratories state that at 110-120 volts A.C. a switch must be able to handle normal current of 6.0 amps and a current inrush of 60 amps (with proportionately lower amperage ratings at higher voltage ratings) to be classified as a heavy duty switch. When handling this type of load, there is a tendency for an arc to establish between the fixed and movable contacts as contact separation occurs. This has necessitated a spacing of parts in a manner such that a permanent arc does not occur between two metal components within the switch. The result has been that heavy duty switches conventionally are rather bulky. When considering a conventional switch box, for example, it has been possible only to put a single heavy duty switch in any transverse plane of the box. There are many applications in which it would be very desirable to get more switches in a single box.
The principal object of the present invention is to achieve a reduction in size of an electrical switch within the heavy duty category so as to make available the ability to get more switches into a particular volume. Thus, for example, it is possible to put two of the switches of the present invention side by side within the transverse plane of the conventional switch box. Size reduction is, in part, achieved by providing a relatively long path between contacts of opposite polarity as the contacts separate while still maintaining the advantages of spring mounting of the contact carrier so as to insure good contact seating.
Further objects and advantages will become apparent from the following description.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a longitudinal section through an embodiment of the invention;
FIG. 2 is a transverse section taken at line 2--2 of FIG. 1;
FIG. 3 is a transverse section taken at line 3--3 of FIG. 1;
FIG. 4 is a partial section viewed as in FIG. 1, but illustrating one stage of the switch operation;
FIG. 5 is another partial section viewed the same as FIG. 1, but illustrating another stage in the switch operation;
FIG. 6 is a partial section as seen at line 6--6 of FIG. 3; and
FIG. 7 is a view of an alternative movable contact.
DESCRIPTION OF SPECIFIC EMBODIMENTS
The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose, as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.
The switch body is defined by an insulating housing 10 threaded to a metal housing 11. There is an enclosed internal cavity 12 which, for all practical purposes, is defined by the insulated housing 10. Molded into the base end 13 of the insulated housing are a pair of electrical conductors which at the cavity end define fixed contacts 14 and 15. These conductive members are internally threaded to receive screws 16 and 17 for attaching wires to be in electrical connection with the respective contacts. In an axial plane 90° from that of the diametrically opposed contacts 14 and 15 are a pair of conductive posts 20 and 21. These posts are embedded in portions 22 and 23 of the material from which the housing 10 is formed. The screws 24 and 25 threaded into the top of posts 20 and 21 hold contact arms 26 and 27 thereon. At the ends of arms 26 and 27 are contacts 28 and 29. At the external end of posts 20 and 21 are screws such as 30 for attaching wires.
An electrically conductive contact bridge or carrier 33 extends transversely to the axis of cavity 12 and divides that cavity into two chambers 34 and 35. At the end of one of these chambers are the fixed contacts 28 and 29, while at the end of the other chamber are fixed contacts 14 and 15. The periphery 36 of the carrier is immediately adjacent the internal wall 37 of the housing that defines cavity 12 with only a relatively small space therebetween. Thus, as the carrier 33 moves in an axial direction within the cavity it functions as a piston. For example, as it moves downwardly in FIG. 1 it compresses the air (fluid) in chamber 35 and decreases the air pressure in chamber 34. Movable contacts 38 and 39 are diametrically opposed on carrier 33. The carrier 33 provides an electrical connection between the two contacts 38, 39.
The operating apparatus for the switch comprises an external plunger 41 coupled to an internal plunger 42. Plunger 42 is of an insulating material and defines an internal chamber 43 in the end facing carrier 33 with the walls thereabout being a skirt forming a shroud. A second insulating plunger 44 (serving as a pressure member) has a stud 45 which projects through carrier 33 and an internal chamber 46 on the opposite end and facing end wall 13 of the housing thus, the wall of the plunger 44 about the chamber 46 is a skirt forming a shroud. A spring 47 has one end in chamber 43 and abutting the insulated plunger 42 with the other end slipped over stud 45 and abutting carrier 33. A second spring 48 abuts end 13 of the housing, extends within chamber 46 and abuts the insulated plunger 44. The spring 48 is stronger than the spring 47. However, the two springs permit the carrier 33 to float so as to insure a good electrical connection between the movable contacts and the fixed contacts which the movable contacts are against.
The contacts 28 and 29 would function as normally closed contacts, and the contacts 14 and 15 would function as normally open contacts. Thus, in the absence of disturbing forces, the movable contacts 38, 39 are against fixed contacts 28, 29, as illustrated in FIG. 1.
To initiate a switching operation, the plunger 41 is pushed axially in an inward direction. During the first stage of this movement the spring 47 collapses (it being weaker than the spring 48). Thus, the insulated plunger 42 moves down so that its end contacts the carrier plate 33, as illustrated in FIG. 4. In this position the insulated plunger 42 serves as a shroud for spring 47 and increases the effective distance in air between the contacts 28 and 29. Thus, as the movable contacts separate, and if an arc develops, that arc will not bridge the space between the contacts 28, 29, which would be an extremely undesirable condition. Furthermore, as the carrier 33 moves downwardly from the FIG. 4 position the air in chamber 35 is compressed (by the piston action) and flows about the periphery 36 of the carrier. This periphery is immediately adjacent the contacts 38, 39 so that the comparatively cool air from chamber 35 that is pumped about the periphery of the carrier serves to cool arcs that may exist between the movable contacts and the fixed contacts thereby aiding in extinguishing those arcs.
FIG. 5 illustrates the position of the carrier 33 when it is serving to establish electrical contact between the two fixed contacts 14 and 15. This condition will be stable so long as the plunger 41 remains pushed in as far as it will go. Again, the springs 47, 48 permit the carrier to float so that good electrical contact is established between the two movable contacts and the two respective fixed contacts. If plunger 41 now is released, carrier 33 will commence to move upwardly from the FIG. 5 position. Again, the insulated plunger 44 serves as a shroud for the spring 48 at the time of initial separation and thus increases the effective distance between the diametrically opposed contacts so that an arc will not jump between them. At the same time, the carrier 33 serves as a piston to compress the air in chamber 34 so that it flows about the periphery of the carrier and across the contacts to aid in extinguishing any arcs.
FIG. 7 illustrates an alternative embodiment in which there is a carrier 33' having its periphery 36' in contact with wall 37' to more effectively serve as a piston. In this embodiment there is an opening 50 axially through the movable contact 38' to serve as fluid communication between the chambers 34 and 35. Thus, as the carrier 33' is moved axially, as indicated by arrow 51, the air is pumped across the carrier through the opening 50 to aid in extinguishing the arc.