US3327262A

US3327262A - Sealed switches

Info

Publication number: US3327262A
Application number: US528240A
Authority: US
Inventors: James A Bongard; Merle R Swinehart
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1966-02-17
Filing date: 1966-02-17
Publication date: 1967-06-20
Anticipated expiration: 1984-06-20
Also published as: NL132202C; NL6701124A; GB1160341A; FR1509435A; CH464318A; DE1589566B1; SE327238B

Description

June 1967 J. A. BONGARD ETAL 3,32

SEALED SWITCHES Filed Feb. 17, 1966 2 Sheets-Sheet 1 qaaqrn nnmrumummL 16 /a la l sa 26 5 1: 20? d 34 20 20a 20 20 22 Id 14b S @tm ui June 1967 A. BONGARD ETAL 3, 7,2 2

SEALED SWITCHES Filed Feb. 17, 1966 2 Sheets-Sheet 2 I United States Patent 9 3,327,262 SEALED WITCHES James A. Bongard, Milwaukee, and Merle R. Swinehart, Brookfield, Wis., assignors to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Filed Feb. 17, 1966, Ser. No. 528,240 9 Claims. (Cl. 335-454) This invention relates to sealed switches which are actuatable by application of an externally applied magnetic field.

The use of sealed switches of the socalled reed type has become quite prevelant for applications involving relatively low power requirements where arcing does not occur. Few, if any, in comparable configurations and sizes, have been devised for service requiring relatively high power. In the latter type of service most of the available forms of sealed reed switches have not proven satisfactory because of contact welding, contact sticking and contact resistance problems.

It is a primary object of the present invention to provide improved forms of sealed switches of the same general configurations and sizes, but which afford repeated satisfactory operations under relatively high power conditions.

Another object is to provide improved switches of the foregoing type wherein a compound movable armature and spring contact assembly of novel form is used to provide improved operation, inhibition of welding and improved contact engagement force.

A further more specific object is to provide in such assembly a novel form of spring contact member which serves as the support and pivot hinge for the movable armature, return spring for the armature, a primary current conductor in the switch, movable electrical contact, and as a contact force spring.

Still another specific object is to provide the mating areas of the armature and stationary magnetic members with surfaces which inhibit erosion due to mechanical action and electrical arcing.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawings illustrate preferred embodiments of the invention which will now be described in detail, it being understood that these embodiments are susceptible of modifications in respect of details without departing from the scope of the appended claims.

In the drawings:

FIGURE 1 is a side view, several times actual size, of

a switch constructed in accordance with the invention with a portion of the glass casing broken away;

FIG. 2 is a top view of the switch of FIG. 1 with another portion of the glass casing broken away;

FIG. 3 is a cross sectioned view taken along the line 33 of FIG. 1;

FIG. 4 is a fragmentary view, to still larger scale of the switch as viewed in FIG. 1, but in an intermediate operating position;

FIG. 5 is a view like FIG. 4, but showing certain switch parts in the closed circuit operating position;

FIG. 6 is a perspective view of the circuit making and breaking parts of the switch;

FIG. 7 is a side view, several times actual size, of a modified form of switch constructed in accordance with the invention; and

FIG. 8 is a fragmentary sectional view to still larger scale of the switch of FIG. 7.

As shown in FIGS. 1 to 5,- a switch in one preferred form of the present invention provides normally open contacts for circuit commutation upon application of an operating magnetic field. More particularly, it comprises Patented June 20, 1967 a cylindrical glass envelope or casing 10 which is sealed and fused at opposite ends to

terminal members

12 and 14 which are preferably made of magnet material. The

central portions

12a and 14a of the

members

12 and 14 to which the casing is sealed are preferably of circular cross section and the

ends

12b and 14b which extend outwardly of easing 1-0 beyond the ends of

portions

12a and 14a are preferably of a flat, spade-like form. The opposite ends and 14c of

members

12 and 14 which lie within casing 10 are also preferably of the flattened rectangular cross section.

A combination stator and contact support member 16, which is preferably formed of soft magnetic material is preferably welded to the lower surface of the portion 120 of terminal member 12. A silver alloy contact 18 is welded to the upper surface of member 16, and member 16 adjacent its free end on its upper surface is provided with a tungsten carbide surfacing or coating 16a which is deposited by known methods.

The portion 14c of member 14 on its upper surface has secured thereto the portion 20a a combination contact and spring member 2t). A rivet 22 penetrating alined openings in portions and 26a of

members

14 and 20 is used as the preferred way of effecting securement, but welding may also be used.

Member 20 is preferably formed from a low electrical resistivity spring metal such as a prehardened, silver magnesium-nickel alloy. Member 20 preferably is of a thin, rectangular cross section and has a relatively long portion 2012, an hour-glass shaped portions 20c (as seen in FIG. 2), and a contact portion 20d which overlies the stationary contact 18 and an angled up tip end portion Zoe. Near the point where the

portions

20b and 20c merge, a rivet 24 penetrates alined openings in a member 20 and in an armature member 26 which is preferably formed of the same material as member 16. As thus secured to contact spring member 20, armature 26 is afforded a semi-floating type support. On its lower surface, adjacent its left-hand end, armature 26 is provided with a tungsten carbide coating 26a.

Before member 20 is secured to member 14, and member 26 is secured to member 20, member 20 is put in a suitable fixture and subjected to a prebending at 200 of 26 by application of mechanical force.

The bending at 20c imparts a shallow longitudinal inverted V-shape such that when member 20 is attached to member 26 by member 24, member 20 bears against the left-hand end of member 26 with a predetermined degree of force, and as will hereinafter be apparent, this determines the amount of contact force between the portion 20d and contact 18 when the armature 26 seals against the stator 16.

The portion 20c provides a volume of high thermal conductivitiy materal and also provides an area on the contact surface from which an arc will not be initiated when the switch is caused to open a circuit. This extended volume provides the necessary thermal capacity to permit the switches to interrupt (on an emergency basis) the inrush current of an AC. inductive load whose steady state current would fall within the rating of the switch.

Member 20 is subjected to another prebending operation at 2% preferably after assembly to

members

14 and 26. The bending at 20g causes the movable assembly to bear against the glass housing with a predetermined degree of force at 10b after the switch unit is assembled and sealed. This form and the portion 20b of member 20 between the

rivets

22 and 24, contributes a portion of the mechanical force that is tending to open the switch when it is in its sealed position shown in FIG. 5, and it contributes all of the mechanical force that tends to open the switch when it is in its intermediate position shown in FIG. 4.

Casing is made from a preform (not shown) cut from cylindrical glass tubing. An inward indentation 10b is formed by first suitably heating the preform in the region where the indentation is desired, and then by pressing the softened glass inwardly a desired amount with a punch which in one preferred form is of triangular cross section.

The sub-assemblies shown in FIG. 6 are suitably positioned relative to each other and the longitudinal axis of the glass preform, within the latter, so that (1)

areas

16a and 26a overlie each other by a predetermined amount, (2) portion 200 of member bears against the inner tip of indentation 10b such that the plane established by area 26a has a predetermined angular relationship to the plane established by area 16a and (3) the referenced areas are spaced apart by a predetermined amount.

The glass casing preform is then suitably heated near its ends, in successive steps, to cause the glass to soften and shrink into sealed relation with the

portions

12a and 14a of

terminal members

12 and 14. During a portion of the foregoing heating and sealing operations the interior of the casing is subjected to the flow of a suitable gas under somewhat higher than atmospheric pressure. In completed state, the interior of the glass casing 10 will preferably have a fill containing a high percentage of such gas under slightly lower than atmospheric pressure. Nitrogen is preferred as a fill when a switch unit is to be used for general alternating current applications. In other applications inert gases, and possibly even hydrogen or ammonia fills may be preferred.

When not subjected to a magnetic field, the components of the switch assume the normal positions depicted therefore in FIG. 1 such that the portion 20c bears against the end of indentation 10b and portion 20d is separated from contact 18 'by a smaller distance than area 26a is separated from 16a. Now if the switch is subjected to a magnetic field of sufficient magnitude along the longitudinal axis of the assembly, armature 26 will be caused to move toward stator 16 and will seat its tungsten carbide coated area 26a against corresponding area 16a of stator 16. During the transition period contact portion 20d first engages with contact 18, as shown in FIG. 4, and as armature 26 continues to move toward stator 16, the portion of member 20 that extends to the left of rivet 24 will be bent upward away from armature 26. This bending plus the added travel of the parts that are riveted together by rivet 24 results in relative motion between items 1-8 and 20d and results in a sliding contact.

When armature 26 seats against stator 16 the latter and member 20 assume the positions depicted in FIG. 5. Contact portion 20d of member 20 will then seat against contact 18 under a certain degree of force as determined by the aforementioned prebending imparted to the portion 200, and the amount of opposite bending in portion 200 imparted by seating armature 26 against stator 16 as best shown in FIG. 5.

When an operating magnetic field is removed the return spring force built up in portion 20b of member 20 tends to move armature 26 upwardly out of engagement from stator 16. The stressed spring force built up in portion 200 also causes the left end of armature 26 to move up rapidly and impart a hammer blow against the lower surface of portion 20d of member 20. This hammer blow action helps to break small "welds that may occur between portion 20d and contact 18. After portion 20d breaks free of cont-act 18 member 20 moves itself and armature 26 to their normal positions depicted in FIG. 1 by the remaining stored energy in spring portion 20b of member 20.

It will be noted that spring contact member 20, and the manner in which armature 26 is suspended therefrom provides a number of important advantages. The semifloating suspension afforded by the single point, attachment of armature 26 to member 20 facilitates better sealing alinement of the armature with stator 16. It also en- 4 hances the hammer blow action on contact portion 20d to break welds.

Spring contact member 20 is a rnulti-purpose element serving a number of important functions. It provides the aforementioned semi-floating support and hinge for armature 26 relative to terminal 14 and stator 16. The portion 2%, due to its prebending, affords return spring action for itself and armature 26. The entire spring contact member serves as the primary current conductor between terminal 14 and contact 18. The portion 20d serves as the movable contact, and portion 20c serves as the contact engagement force producing means.

The tungsten carbide coated

tips

16a and 26a of

members

16 and 26 minimizes material erosion due to mechanical wear. They provide a relatively low contact resistance between

members

16 and 26 thereby enhancing their ability to act as the primary current conductor if the contact bounces open after the armature 26 is seated on the stator 16. They inhibit Welding between such members if the armature should also bounce open while it is acting as the primary current conductor in a high power circuit.

Other conductive hard metals may be used in the place of tungsten carbide for the

coatings

16a and 26a on

members

16 and 26. Such metals have been classified as carbides, nitrides, borides and silicides of transition metals of the fourth, fifth and sixth groups of the periodic table which have conductivities in the metallic range. Tungsten carbide, zirconium nitride, titanium 'boride and molybdenum silicide are examples.

The switch constructed in accordance with FIGS. 7 and 8 provide both normally open and normally closed contacts for circuit commutation upon application of an operating magnetic field. As shown, this switch comprises a glass envelope or casing 30,

stationary terminals

32, 34 and 36, stator 38, stationary contact 40, spring contact member 42, a second shorter spring contact member 44 and armature 46.

Terminals

32 and 34 are sealed through the same end of casing 30 and are arranged in parallel relation to each other. Stator 38 is secured to the upper side of terminal 34 and stationary contact 40 is secured to the upper surface of stator 38.

Spring contact member 42 and armature 46 are attached together by a rivet 48 and member 42 is secured to the upper surface of terminal 36 by a rivet 50. Member 42 is substantially the same as member 26 aforedescribed in connection with FIGS. 1 to 6, but does not have the up-turned end extending beyond its contact tip portion 42d. The short spring contact member 44 is secured to terminal 32 by a rivet 52 and the contact portion 44a overlies both contact portion 42d of contact 42 and stationary contact 40. Spring contact member 44 is prebent at 44b to provide a shallow V-shaped arch to determine the contact force between member 44 and spring contact member 42 in the normal position depicted in FIG. 7. The indentation 30a in casing 30 provides a stop abutment for

members

44 and 42 in the normal position.

Upon application of an operating magnetic field,

members

42 and 46 move as aforedescribed to engage contact portion 42d with contact 40 and tip 46a with tip 38a of stator 38.

When the magnetic field is removed, return spring portion 42b and contact spring portion 42c cause movement of armature 46 away from stator 38 and the energy being stored in this moving member due to the accelerating forces acting on it will cause the left-hand end of armature 46 to impart a hammer blow against contact portion 42d to drive it upwardly. Continued upward movement of

members

42 and 46 results in engagement of contact portion 42d with contact portion 44a and continued move ment of the two members into engagement withthe indentation 30b.

In the normal or deenergized position of the switch of FIGS. 7 and 8 spring contact member 44 will be stressed, but not sufficiently to counteract the upward bias thereagainst imparted by spring contact member 42. However,

this stressed condition of member 44 helps to insure maintenance of force engagement between

contact portions

42d and 44a in the normal position of the switch.

We claim:

1. In a sealed switch for operation by an externally applied magnetic field, in combination, a tubular envelope formed of non-magnetic material, terminals extending through the ends of said envelope and being hermetically sealed to and supported by the latter, each of said termin-als having a portion thereof interiorally of said envelope formed of magnetic material, an electrical contact formed of a good electrical conducting material secured to said portion of said one of said terminals, a thin, flexible spring member formed of good electrical conducting material connected at one end to said portion of the other of said terminals, and an elongated flat member formed of magnetic material which is substantially.

parallel and contiguous with said spring member over a major portion of the length of the latter, said elongated flat member being connected at a single point to said spring member and one end thereof overlying said portion of said one of said terminals.

2. The combination according to claim 1 wherein said last specified member formed of magnetic material has its other end spaced apart from the adjacent end of said other terminal member an amount which insures against contact while maintaining the magnetic air gap small therebetween in any operating condition of the switch.

3. The combintion according to claim 1 wherein said envelope has an inward, transversely extending indentation and wherein said spring contact member is pre-bent to be positively biased into engagement with said indentation upon removal of an operating magnetic field.

4. The combination according to claim 1 wherein said spring contact member is secured to said other terminal and said last specified member formed of magnetic material by rivets.

5. The combination according to claim 4 wherein said spring contact member is pre-bent between its rivet connection with said last specified member formed of magnetic material and its portion overlying said contact to provide a contact force spring port-ion which normally engages said one end of said last specified member.

6. The combination according to claim 1 wherein the opposing surfaces of said portion of said one of said terminals and the last specified member formed of magnetic material are coated with a conductive hard metal material to provide resistance to mechanical erosion and welding therebetween.

7. The combination according to claim 1 together with a third terminal extending through and sealed to said envelope at the same end as said one of said terminals and in spaced apart parallel relation to such terminal member, and together with a second thin, flexible spring contact member secured to said third terminal interiorly of said envelope and having a portion overlying both said contact and the portion of the first mentioned spring contact member which overlies said contact, said first spring contact member being biased into engagement with said second spring contact member in the absence of an operating magnetic field.

8. In a sealed switch for operation by an externally applied magnetic field, in combination, a one-piece tubular glass envelope, terminals formed of magnetic material extending through the ends of said envelope and being hermetically sealed to and supported by the latter, an electrical contact formed of a good electrical conducting material secured to one of said terminals within said envelope in spaced relation to the inner end of said one terminal member, said envelope having an indentation formed to overlie said one of said terminals, a thin flexible spring cont-act member formed of good electrical conducting material secured at one end to the other terminal adjacent the innermost end thereof within said envelope and pre-bent adjacent its point of securement with said other terminal to be positively biased into engagement with said indentation, an elongated flat member formed of magnetic material secured to and supported by said spring contact member and adjacent one end overlying the portion of said one of said terminals between the innermost end of the latter and said electrical contact and extending along the major portion of the length of said spring contact member, said spring contact member also being pre-bent between the point at which the last specified member formed of magnetic material is attached and the end of the latter member closest to said electrical contact to be positively biased into engagement with such end.

9. The combination according to claim 8 wherein said spring contact member is formed of a prehardened silvermagnesium nickel alloy and the opposing portions of said one of said terminal member and saidlast specified member formed of magnetic material are both coated with a conductive hard metal material.

References Cited UNITED STATES PATENTS 2,037,535 4/ 1936 Rankin 20087 2,187,379 1/1940 Hensel 200166 3,146,327 8/1964 Ohki et a1 20087 X 3,147,538 9/1964 Perkins 20087 X 3,171,190 3/1965 Zimmer 20087 X 3,240,897 3/1966 Anderson et al 20087 BERNARD A. GILHEANY, Primary Examiner. J. J. BAKER, R. N. ENVALL, 111., Assistant Examiners.

Claims

1. IN A SEALED SWITCH FOR OPERATION BY AN EXTERNALLY APPLIED MAGNETIC FIELD, IN COMBINATION, A TUBULAR ENVELOPE FORMED OF NON-MAGNETIC MATERIAL, TERMINALS EXTENDING THROUGH THE ENDS OF SAID ENVELOPE AND BEING HERMETICALLY SEALED TO AND SUPPORTED BY THE LATTER, EACH OF SAID TERMINALS HAVING A PORTION THEREOF INTERIORALLY OF SAID ENVELOPE FORMED OF MAGNETIC MATERIAL, AN ELECTRICAL CONTACT FORMED OF A GOOD ELECTRICAL CONDUCTING MATERIAL SECURED TO SAID PORTION OF SAID ONE OF SAID TERMINALS, A THIN, FLEXIBLE SPRING MEMBER FORMED OF GOOD ELECTRICAL CONDUCTING MATERIAL CONNECTED AT ONE END TO SAID PORTION OF THE OTHER OF SAID TERMINALS, AND AN ELONGATED FLAT MEMBER FORMED OF MAGNETIC MATERIAL WHICH IS SUBSTANTIALLY PARALLEL AND CONTIGUOUS WITH SAID SPRING MEMBER OVER A MAJOR PORTION OF THE LENGTH OF THE LATTER, SAID ELONGATED FLAT MEMBER BEING CONNECTED AT A SINGLE POINT TO SAID SPRING MEMBER AND ONE END THEREOF OVERLYING SAID PORTION OF SAID ONE OF SAID TERMINALS.