US3030465A - Switch - Google Patents

Description

.April 17, 1962v J. o. ROE-SER 3,030,465

SWITCH Filed Aug. 30, 1960 IN VEN TOR.

John 0. oeser United! States AParent O 3,030,465 SWITCH John 0. Roeser, Park Ridge, Ill.

Filed Aug. 30, 1960, Ser. No. 52,947 16 Claims. (Cl. 200-67) This invention relates in general to switches, and more particularly relates to a rugged, low travel, electrical switch, wherein the contacts are encapsulated in a hermetically sealed enclosure.

The exigencies of modern-day aircraft and spacecraft have demanded the development of extremely rugged and compact electrical switching devices. These switching devices must withstand extremes in vibration and shock resistance, must be operable over a wide range of ambient temperatures, and must provide the utmost in vreliability under these extreme conditions. Therefore, it is a general object of this invention to provide a small compact electrical switch of the hermetic type which is exceedingly rugged and has extremely high vshock and vibration resistance.

Another object of this invention is to provide a reliable electrical switch device of the above type wherein the contact mechanism is encapsulated in a chamber which is evacuated, there `being a true hermetic type seal which has a leak-rate of under *6 cc. per second.

It is another object of this invention to provide an electrical switch having the above characteristics which requires only a very low travel of the actuator member to actuate the switch blade while still maintaining the desired characteristics of high vibration and shock resistance. Y

It is another object of this invention to provide a switch of the snap action type, which has a large overcentering movement of the contact actuator assembly to get positive controlled vibration resistance switching` action.

It is another object of this invention to provide a switch of the aforestated type which has no dead-centering characteristics, is positive in operation, is easy to assemble,

and is otherwise well ladapted for the purposes for which it was designed. p

The novel features that are characteristic of the inven- 'tion are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, may =best be understood by the following description of a specific 'embodiment when read in connection with the ac- FIG. 5 is a partial sectional view taken along line 5-5 'l FIG. 7 is a view of the flexible insulator means prior l to its assembly to the apparatus; and

FIG. 8 is an enlarged partial sectional view of the 'upper portion of the actuator assembly shown in FIG. 2.

As shown in the drawings, the switch device 10 essentially comprises a very rugged cast base 12 and -a cover 14 which defines an internal sealed chamber 16. The base is preferably made of steel and it has beenfound Aconvenient to cast the base by the so-called investment casting method so as to get `an extremely strong and rugged component. The cover 14 is preferably formed of steel and fits into a suitable groove in the base 12 and is braised or soldered to the base to provide a rugged leak-proof seal for chamber 16. An evacuation outlet tube 18 is fixed in a suitable bore in the base 12 to provide a means of evacuating the chamber after assembly and then pinching off the tube in the usual manner to completely seal the chamber.

The base 12 is formed with a plurality of spaced `aligned transverse apertures which are adapted to receive terminal pins 26, 28 and 30. Each pin is preferably made of an electrically conducting metal, and has an angularly offset -depending portion 26A, 28A and 30A respectively each of which is drilled and tapped to receive suitable terminal screws in the bores 26B, 28B, 30B. The terminal pin bores in the 'base 12 are sealed by a compression glass seal 26C, 28C, 30C respectively, said seal being exceedingly rugged in structure and serves to electrically insulate the respective terminal pins from the steel base. It will be noted that the base 12 is also formed with a pair of spaced cross Ibores 32 which serve as mounting holes to mount the switch unit in position for its desired application.

The terminal pins 26, 28 and 30 may be respectively ydesignated as the normally open and normally closed and common terminal pins. A movable contact assembly 34 is mounted on the common terminal 30 for coaction with the ixed terminals. More particularly, an elongated perforate member 36 is iixedly attached to the terminal 30 at one end and is preferably made of a thin springy metal. As best shown in FIG. 3, a portion of the member 36 is blanked out at 38 to define a central tongue portion 30 having a wide base portion and a relatively narrow free end portion. The `blanked out portions 38 of member 36 is formed in a somewhat U-shaped configuration, the amount removed at the base being considerably thicker than the arms, and in addition to the tongue portion provides a pair of narrow curved arm portions 42 and 44 which terminate in a pair of iingers 46 and 48 at the free end of member 36 (the curve is only in side elevational view-see FIGS. 2 and 6). It is to be noted that the blanked out U-shaped aperture 38 does not extend completely to the free end of member 36. The fingers 46-48 are further formed in a manner to provide V-shaped notches as best shown in FIGS. 4 and 6, for pivotal receipt of the contact carrying member later to be described. A shallow U-shaped aperture 50 formed in the free end of member 36 denes the upright finger portions 46-48 of the curved arm portions 42 and 44, but it should be noted that a small portion of the metal intermediate, the base of the U-shaped aperture 50 and the furthest extent of the blanked out portion 38 remains after the blanking out procedure, so that the two arms 42-44 and fingers 46-48 will always operate simultaneously. While there are two arms and fingers, they are actually integrally connected at both ends. The interconnection of the two arms and lingers provides vibrational stability, a very important feature in the instant switch.

As shown in FIG. 6, the member 36 has arm portions 52 and 54 which are relatively straight adjacent to the common terminal pin 30, but are canted or offset slightly upwardly from the horizontal from the point of attachment of the member to pin 30. At the outer extent of straight portions of 52 and 54, the arms are respectively engaged at points 56 by the operating means which will be later described. See the point marked X in FIG. 3.) The arms then are reversely offset downwardly and near Athe end thereof are sharply reversely curvedi upwardly substantially thicker stiffening or rigidifying member 5'8, which is integrally joined thereto. As shown, member 58 extends substantially along the entire length of the 'tongue portion, terminatingjust short of the free end thereof, and the function of member 58 is to stabilize the tongue to afford vibration resistance.

A U-shaped contact carrying movable blade member 6@ is mounted for pivotal coaction with member 36, the lfree arms 62 and 64 of said member 66 being inserted fin the V-shaped notches in the fingers 46-418. The movable contact 66 mounted on member 66 has a very slightly raised central portion or nib 66a on each face thereof and is biased into engagement with the lower iixed contact 74 by spring member 68. The spring member 68 Iis mounted at one end thereof in an aperture 70 formed Vnear the base of the U in member 6i) with'its other end being firmly xed in aperture 72 on the free end of tongue member 40. The arms 62-64 and the fingers 464478 are separated just sufficiently to receive the spring member 68 which passes therebetween, the spring `in addition to providing the biasing force for the movable contact assembly serves to locate the contact carrying member 66 relative to member 36. As will be apparent, the contact 66 is biased toward engagement with the lower iixed contact 74 and is movable to engagement with the upper iixed contact 76. Each of the fixed contacts 7'2-74 is preferably made of a silver brass laminate, the silver portions being adapted to come in contact with the movable contact.

It should be noted that the movable Contact has 'a sliding or wiping action on each actuation thereof by the operator means, and which is later described. When the pivot point of the arms 62-64, in the notches on the fingers 46-48, passes through center, the movable contact 66 slides to the left as viewed in FIG. 6, to provide the very desirable wiping contact action. Also the characteristics of the arrangement shown is such that the pivotal connection point of the iingers 46-48 and arms 67;-64 are forced, by reaction force, to a considerable over-center position, which provides a very stable vibration resistance assembly. Stated another way, the arrangement of the pivot point in the midpoint of the spring causes the lingers t6-48 to pass considerably over the dead-center point after the switch has actuated in either direction. This over travel of the pivot point is caused by the reaction force of the movable contact engaging the fixed contacts. It will also be apparent that there is no dead centering of the movable contact 66 since the movable contact is always biased by the spring 68.

Low travel operator means 7S, in the form of an actuator assembly is best shown in FIGS. l and 2. The actuator assembly essentially comprises an internal elongated lever means 80, a cross pin member 96 and an outside lever 98. These three components present a generally U-shaped force transmitting configuration, with the U being turned on its side, members S0 and 9S forming the two arms of the U, the free ends of the two arms of the U essentially being the points of application of force and transmission of force to the contact assembly. The internal lever 8G is formed with a notch at one end to form short stubby leg portions S2-S4. The other end of the lever 80 is necked down at S6 and has a slight cant or olfset in horizontal view (see FIG. 2) from the major plane of member 80. A bore 88 is formed in the end surface to mount Ithe ycross link cylindrical pin member 96 which is irmiy xed therein.

A pair of glass bead members 92-94 are fused to the metal and thereby attached to the short stubbing arms 82-84 of the inner lever means 80 in depending relation. The glass beads serve the dual function of being a force transmitting member and the providing of electrical insulation between the lever Si) and the member 36. The beads 92-94 impinge upon the respective arm portions at points S6 as aforestated. As shown in FIG, 5, the

operator lever Sti is formed with a central aperture which serves as 'a weight reducing means for the lever;

Central cross pin member 96 is firmly xed to members 80 and 98, a bellows means 110 being interposed between the upper lever 93 and the housing to provide a exible seal. The lever 98 is mounted on the outside of the bellows 110 and terminates in a pair of upstanding tabs 100 which mount a miniature ball-bearing roller mechanism 102. An over-travel preventing means for the actuating mechanism in the form of an elongated member 104, having depending tabs 106 and an adjustable screw 108 prevents damage to the internal structure of the switch. The tabs 106 bottom on the top of the casing prevent more than the selectively adjustable amount of travel desired for actuation. It will be appreciated that the outside lever member 98 is made of thinner gage material than member 104 and hence is somewhat exible such that a severe force applied to member 162 at the end of thejlev'er will cause member 95S to flex but will not cause further actuation of the interior lever 80.

The bellows 110 as aforementioned provides a -exible yseal for the operator means and further tends to dampen any vibrations that thesomewhat elongated lever means might normally be subject to when the entire switch 10 is in turn subjected to shock or to severe vibrations. More particularly, the bellows 110 is sealed to the upper portion fof the housing at 112 and is fixed to the lever member 98 at 114. The interior of the bellows is preferably potted with a silicone rubber compound 116. More particularly, the silicone rubber compound is compounded by using a silicone rubber polymer which has a rather pasty, dry consistency, much like window putty. Into this material, by the use of rotating cylinders, is inserted a socalled blowing agent which is a dry powdery chemical which sublimes on the application of slight heat to produce a gas. Just a few percent of blowing agent is used, and the dry pasty material is packed into the bellows cavity with a small spatula and then the whole assembly is put into the oven at a temperature of about 250 F. The heating causes the blowing agent to sublime and thereby provide small gas pockets within the silicone rubber compound. The net effect is to force the silicone into the crevices of the bellows, for intimate contact therewith except for the areas wherein the compressed air is greater than the force of the gas generated by the subliming material. The silicone rubber occupies most all of the crevices and provides a Vgood vibrational dampening effect. When the utmost in vibrational resistance is desired for the switch, an additional pad of this silicone rubber compound is foamed in place (at 128) beneath the iiexible arm portions of member 36 to provide additional vibrational dampening characteristics. However, the additional pad of material 128 is not found to be necessary for vibration resistance when the switch is subjected to forces under 50 gravities with 0 to 2,000 cycles per second vibration, the actuator being within .005 inch of the trip point, since the described switch structure without such additional material 12.8 serves to provide that function.

As can be best seen in FIG. 2, a flexible supplementary insulator means 118 (shown in its preassembled form in FIG. 7) is bent into a U-shaped form and is interposed, at the upper portion thereof, between the lever 3i), and the fixed contact and the movable contact assembly. The member 118 at one end is provided with a truncated corner 120 so as not to cover up the evacuation tube 18. Bores 124 and 126 in member 118 respectively receive the terminal pins 26 and 23 during the assembly operation and the end of member 118 is reduced at its other end at 122 so as to not interfere with the depending glass bead members 92 and 94 when nally assembled.

From the foregoing description it will be apparent that a low travel, rugged, hermetically sealed switch is provided which is extremely vibration resistant and adapted for applications requiring a high degree of shock. The

switch has been found to operate very well over wide range of ambient temperatures and tests have indicated that it will have a long, trouble-free field life.

Having thus described a single embodiment of the low travel, rugged, hermetically sealed switch, it is to be understood that the illustrated form was selected to facilitate the disclosure of the invention rather than to limit the number of forms the invention may assume. Various modifications, adaptations and alterations may be applied to the specific form shown to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention, and all such modifications, adaptations and alterations are contemplated and may come Within the scope of the appended claims.

What is claimed as the invention is:

l. A hermetic switch comprising housing means defining a sealed chamber having first, second, and third electrical terminal means sealingly extending therethrough, first and second fixed contact means mounted on said first and second terminal means within said chamber,

lmovable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a U-shaped relatively.

said elongated member and to bias the movable Contact.

against said first fixed contact means, and operator means sealingly extendingv through said housing means and engageable with said flexible portions of said elongated member and operable to move said free end to cause movement of said movable Contact from said first to saidy second fixed terminal means.

2. A hermetic switch comprising housing means defining a sealed chamber having first, second and third electrical terminal means sealingly extending therethrough, first and second fixed contact means mounted on said first and second terminal means within said chamber, movable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a relatively rigid member carrying the movable contact, a second member having a relatively flexible portion and a relatively rigid portion, fixed at one end to said third terminal means and having a free end spaced therefrom, said free end being configured for pivotal engagement of said contact carrying member, spring means engageable with said contact carrying member at one end and with said relatively rigid portion of said second member at the other end to maintain the pivotal connection therebetween and to bias the movable contact against one of saidfirst and second fixed contact means, and operator means sealingly extending through said housing means and engageable with said flexible portion of said second member and operable to move said free end thereof to cause movement of said movable contact from its said first to its said second position.

3. A switch comprising metalic housing means defining a chamber having first, second, and third electrical terminal means electrically insulatingly extending therethrough, first and second terminal means within said chamber, movable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a movable relatively rigid member carrying a movable contact, a second member having a relatively flexible portion and a relatively rigid portion, fixed at one end to said third terminal means and having a free end spaced therefrom, said free end being configured for pivotal engagement 6 with said contact carrying member, spring means engageable with said contact carrying member at one end and with said relatively rigid portion of said second member at the other end to maintain the pivotal connection therebetween and to bias the movable contact against said first fixed contact means, operator means including a metallic actuator means extending through said housing means and engageable with said flexible portion of said second member and operable to move said free end thereof to cause movement of said movable contact from said first to said second fixed terminal means, said operator means including first insulation means operably interposed between said actuator means and said flexible portion of said second member and flexible second insulation means interposed between said actuator means and said second fixed contact means, said contact carrying member and said spring means. p

4. The switch set forth in claim l wherein the operator means comprises a generally U-shaped member and flexiblebellows on said housingjmeans, one arm of the U- .shaped member being disposed outside of the housing means for engagement on the free end thereof and the other arm beingdisposed within the sealed chamber for engagement with the movable contact means adjacent the free end thereof, the flexible bellows engaging the 'bail portion of the U-shaped member which extends therethrough to thereby mount the operator means on said housing means so that the free ends inside and outside the housing means are in substantial alignment with each other.

5. The switch set forth in claim 4 wherein the bellows is substantially filled with flexible plastic foamed material to increase the vibrational resistance thereof.

6. The switch set forth in claim l wherein first, second and third terminal means extend through a single wall of said housing means to respectively mount said first and second fixed contacts means and said movable contact means.

7. The switch set forth in claim 1 wherein the elongated perforate member is of relatively thin spring material having a short tongue portion blanked out of the central portion thereof to define a pair of spaced flexible arm portions, said flexible arm portions each having a first portion extending below the major plane of said perforate member and a second portion extending above said major plane.

8. The switch set forth in claim 7 wherein said second portion of each of said arms are formed into a finger having a V-shaped configuration generally normal to the major plane of said perforate member at the free end thereof to provide coacting pivotal surfaces for said contact carrying member.

9. The switch set forth in claim 8 wherein said tongue portion is rigidified to provide a support for a portion of said biasing means not subject to vibration.

10. The switch set forth in claim 9 wherein said contact carrying member is bifurcated to form spaced legs having end portions coacting with said V-shaped configurations of said fingers, the biasing means being in the form of a coiled spring confined between the leg portions of said contact carrying member and extending between the fingers at the free ends of said perforate member for attachment to the end of said rigidified tongue member.

11. A hermetic switch comprising housing means defining a sealed chamber having first, second, and third electrical terminal means sealingly extending therethrough, first and second fixed contact means mounted on said first and second terminal means within said chamber, movable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a U-shaped relatively rigid contact carrying member, an elongated perforate member having relatively flexible portions and a relatively rigid portion fixed at one end to said third terminal means and having a free end spaced therefrom,

said free end being configured for pivotal action with said Contact carrying member, biasing means engaging said contact carrying member at one end and said relatively rigid portion of said elongated member at the other end to maintain the pivotal connection between said U-shaped member and said elongated member, to provide positive snap action over centering and to bias the movable contact against said first fixed contact means, and operator means sealingly extending through said housing means and engageable with said flexible portions of said elongated member and operable to move said free end to cause movement of said movable contact from said first to said second fixed terminal means, said biasing means and said U-sahped member upon engagement of said movable contact with said first and second fixed terminal means causing said free end to move by reaction force to a stable vibration resistant over center position.

12. A hermetic switch comprising housing means defining a sealed chamber having first, second and third electrical terminal means sealingly extending therethrough, first and secondfixed contact means mounted on said first and second terminal means within said chamber, movable contact means having a first position and movable to a second position relative to said first and second xed contact means and comprising a LJ- shaped relatively rigid contact carrying member, an e'longated perforate member having relatively fiexible portions and a relatively rigid portion fixed at one end to said third terminal means and having a free end spaced therefrom, said free end being configured for pivotal engagement of said U-shaped member, spring means fixed to said U- shaped member at one end and to said relatively rigid portion of said elongated member at the other end to maintain the pivotal connection between said U-shaped member and said elongated member and to bias the movable contact against said first fixed contact means, and operator means sealingly extending through said housing means and engageable with said flexible portions of said elongated mem-ber and operable to move said free end to cause movement of said movable contact from said first to said second xed terminal means, said operator means comprising an elongated lever means mounted for movement within said chamber and having an at-rest position in engagement with said housing means to provide strong vibration resistance thereto.

13. The switch set forth in claim 12 wherein said operator means further includes iiexible bellows means sealingly mounting said elongated lever means, said spring means through said U-shaped member and flexible portion of said elongated perforate member biasing said lever means toward engagement with said housing means.

14. The switch set forth in claim 13 wherein said operator means further includes second lever means exterior of said housing means associated with the lever means interiorly of said housing means said second lever means including adjustable over travel permitting means.

15. A switch comprising a generally rectilinear housing means having a relatively greater length than depth or height defining a chamber having first, second, and third electrical terminal means extending therethrough, said third terminal being spaced by mounted adjacent one end of said chamber, first and second fixed contact means mounted o n said first and second terminal means within said chamber and adjacent the other end thereof, movable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a U-shaped relatively rigid contact carrying member, an elongated perforate member having relatively flexible arm portions and a relatively rigid central tongue portion fixed at one end to said third terminal means, said arms being connected at a free end spaced from said fixed end for movement in the area intermediate the ends of said chamber, said free end being configured for pivtol engagement of said U-shaped member, spring means fixed to said U-shaped member at one end and to said relativelyk rigid central tongue portion of said elongated member at the other end to maintain the pivotal connection between said U-shaped member and said elongated member and to bias the movable contact against said first fixed contact means, and operator means extending through said housing means and engageable with said flexible arm portions of said elongated member and operable to move said `free end to cause movement of said movable contact from said first to said second fixed terminal means.

16. A hermetic switch comprising housing means defining a sealed chamber having first, second, and third electrical terminal means sealingly extending therethrough, first and second fixedk contact means mounted on said first and second terminal means within said chamber, movable contact means having a first position and movable to a second position relative to said first and second fixed contact means and comprising a relatively -rigid member carrying the movable contact, a second member having relatively flexible spaced arm portions and a relatively rigid tongue portion fixed at one end to said third terminal means, said second member having a free endy spaced` from said fixed end, said free end being characterized as presenting substantially short spaced fingers disposed at substantially right angles to said arm portions said fingers being connected together at the base thereof to define a U-shaped notch, said fingers being configured for pivotal engagement of said contact carrying member, spring means engageable with said contact carrying member at one end and with said relatively rigid tongue portion of said second member at the other end, said spring means extending through said U-shaped notch to maintain the pivotal connection between said rigid member and second member and to bias the movable contact against one of said first and second fixed contact means, and operator means sealingly extending through said housing means and engageable with said flexible arm portions of said second member and operable to move said free end thereof to cause movement of said movable contact from its said first to its said second position.

References Cited in the file of this patent UNITED STATES PATENTS 2,415,546 Willman Feb. 1l, 1947 2,483,685 Willman Oct. 4, 1949 2,505,605 Coake Apr. 25,

2,794,889 Bachman June 4, 1957 FOREIGN PATENTS 514,386 Italy Feb. 9, 1955 540,179 Canada Apr. 30, 1957

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