US3244849A

US3244849A - Hermetically sealed switching device with bellows

Info

Publication number: US3244849A
Application number: US361466A
Authority: US
Inventors: Ravret Pierre; Miachon Louis
Original assignee: Compagnie Electro Mecanique SA
Current assignee: Compagnie Electro Mecanique SA
Priority date: 1963-04-22
Filing date: 1964-04-21
Publication date: 1966-04-05
Anticipated expiration: 1983-04-05
Also published as: FR1362586A; ES298809A1; DE1465366A1; GB1067693A; BE646109A; DE1465366B2

Description

April 1966 P. RAVRET ETAL 3,244,849

HERMETICALLY SEALED SWITCHING DEVICE WITH BELLOWS Filed April 21, 1964 2 Sheets-Sheet 1 lnre alone Pity-re Quay-4i Laulk' e- 40;

April 5, 1966 P. RAVRET ETAL 3,244,849

HERMETICALLY SEALED SWITCHING DEVICE WITH BELLOWS Filed April 21, 1964 2 Sheets-Sheet 2 United States Patent 6 12 Claims. (or. 200-168) The present invention, which is due to Mr. Louis Miachon and to Mr. Pierre Ravret, relates to an electric switch enclosed in an envelope which hermetically seals it from theam bient medium, the temperature and/or pressure of which are likely to vary between very wide limits, and this switch is materially actuated from the outsideby way of an elastic deformation of the said envelope. By switch is meant any device intended to establish and/or break one ormore electric circuits, that is tosay, it also includes a reversing switch, a circuit breaker, a change-over switch, etc.

One disadvantage of previously known constructions ofthis type ist'hat the envelope may undergo, in its elastic part, deformations which modify the characteristics of the apparatus when the said temperature and pressure variations are large.

This disadvantage is obviated in the apparatus accordingwto the invention, which for this purpose is characterised in that the electric switch is enclosed in a substan-. tially. cylindrical bellows comprising an upper end member, and of which the opposite end is closed by an insulating base supporting the said electric switch, the upper end member and the said opposite end of the bellows beingheld fast in relation to one another, the lateral wall being. resilient and pleated,,the folds being symmetrical in relation tothe axis of the bellows, and the switch beingoperated with the aid of two actuating members so disposed as to control one another through one of the folds of the bellows,.one of the said actuating members being outside and the other inside the said bellows.

By way of non-limiting example, there is hereinafter described a hermetic switching device according to the invention in which the switch proper is a miniature quickbreakreversing switch.

FIGURE 1 illustrates a section through the apparatus along a vertical plane extending along the axis of the bellows.

FIGURE 2 illustrates .a portion of the actuating memher outside the bellows.

FIGURE 3 illustrates a variant of the connection between the bellows and the base.

In these figures, 1 denotes a cylindrical insulating'base, for example of ceramic material, to the metallized pe riphery of which there is soldered at 2 theedge of a rigid cylindrical casing 3. The said casing may consist of stainless steel. A lbellows 4 of substantially cylindrical form is welded or solderedlat Sto thefinner surface of the'peripheral wall of the casing 3; The material of which the said bellows consists may be, for example, an iron-chromium compound or any other product having high characteristics of elasticity and resistance to oxidation in considerable temperature and pressure ranges, for example -100 C. to +600 C., and from to 3.10 Pascal.

The end member 4a of the bellows is welded or soldered to a ring or transverse member 7, for example in its central region 6. The said ring is made fast with the end 3a of the casing .3 by three screws or connecting means 8 disposed at 120 apart around the axis XY of the device. This arrangement maintains the end memice her of the bellows and the opposite extremity of the latter at a constant distance apart.

Approximately the upper half of the bellows 4 can 'be inscribedwithin a cylindrical surface whose diameter is smaller than that of a cylindrical surface corresponding to the lower half of the bellows, so that there exists an annular space between the said upper half of the bellows and the inner surface of the peripheral wall Olf the casing i3. Disposed in this space is the skirt 9a of a hollow cylindrical push member 9, of.which the upper endcomprises an external extension 9b forming a control button, which extends through the end 3a of the casing 3. The said push member 9 is formed with holes for the free passage of the screws 8 and of the corresponding portions of the ring 7. It bears against a crescent-shaped-rnernlber 10 (shownin plan view in FIGURE 2) which is inserted in the centre fold 4b of the bellows 4.

The assembly comprising the push member 9 and the member 16 forms the outer actuating member of a switch. The inner actuating member of the switch is formed of a push member 11 extended by a rod 12 which directly actuates. the movable portion of the switch proper. The said push member may be made fast with the bellowsof at least a part of the inner surface of the centre fold.

The utilisation of this centre fold for effecting the connection of the t-wo actuating members substantially equa-lizes the stresses on the metal of the bellows in the different folds. The connection could also be effected by means of a fold other than the centre fold.

The switch proper is a reversing switch of known construction including a resilient blade. One end 14aof the said blade 14 is fixed into the end of an output terminal 13, while the other end 14b carries a contact stud 15 cooperating with

counter contacts

16 and 17 respectively' disposed at the end of other output terminals 18, 19. These terminals are passed through the base 1 in fluid-tight manner by the following means:

The

terminals

13, 18, 19, are hollow metal pins which have substantially the same expansion coefiicient as the base 1 to which they are welded or soldered in hermetic fashion at 20, 21 and 22 respectively; They are each traversed by a conductor respectively designated with the

numerals

23, 24, 25, having good electrical conductivity, for example of copper, of which the outer end serves as a connecting means.

The inner end of the conductor 23 is electrically connected in any appropriate manner to the end 14a of the blade 14. The inner ends of the conductors 14 and 25 may form the-

fixed contacts

16, 17, either by themselves or in association with contactmembers made ofa material possessing particular electrical and mechanical characteristics, such asgold, for example. These

conductors

24 and 25 are hermetically welded at Z6; Z7, to'the pins 18, 19.

The inner end of the pin 13 is formed with an aperture 28 which provides communication between the interior of the device and the exterior by way of the clearance between the conductor 23 and the longitu dinal aperture of the pin. When the fitting of the various parts of the device has been completed, including the welding of the pins 18" and 19, the aforesaid clearance and the said aperture 28 are utilised to fill the interior of the bellows 4 with a gas having appropriate physical and chemical characteristics; The conductor 23 is thereafter hermetically welded to the pin 13 at 29.

In its central region, the blade 14 is traversed by the rod 12. The displacement of the latter along the axis XY causes a change in the camber of the blade 14 and consequently the sudden movement of the contact stud 15 from the contact 16 to the contact 17 or vice versa.

Patented Apr... 5, 19.66

The displacement of the rod 12 results either from a force being applied to the button 912 or from the force of a return spring 30 disposed between the push rod 12 and the base 1. It is limited in one direction by the base 1 and in the other direction by the end 3a of the jacket 3, whereby unnecessary deformations of the bellows 4 are avoided.

Owing to the fact that the ends of the said bellows are maintained at a fixed distance and the folds are symmetrical in relation to the axis XY, the theoretical component along the axis XY of the geometrical sum of the forces emanating from the external and internal pressures is zero. Under these conditions, the folds do not undergo any appreciable deformation when the ternperature and/ or the pressure of the ambient media vary. Consequently, the force to be exerted on the button 9b or the force of the return spring 30, which are both directed along XY, are independent of the said variations.

Many constructional variations are possible. For example, as is shown in FIGURE 3, the end of the bellows 4 may be reinforced and directly soldered at 31 to the base 1, the end of the casing 3 then being welded at 32 to the said end of the bellows. The end 4a of the bellows may be maintained in contact with the fixed member 7 by an appropriate pressure exerted within the bellows.

Likewise, and in accordance with the conditions of use of the device, the switch may be of a different type, the metallic parts forming the electric contacts proper may have any appropriate form, etc.

What we claim is:

1. A hermetically sealed switching device comprising, in combination, substantially cylindrical bellows having a closed end, an opposite open end, and a plurality of corrugations between said ends; closure means extending transversely to said open end of said bellows fluid tightly connected thereto for closing the same; rigid connecting means interconnecting said closure means and said closed end of said bellows for maintaing said opposite end of said bellows spaced a fixed distance from said closed end thereof; switch means supported in the interior of said bellows on said closure means; and a pair of actuating means for actuating said switch means, one of said actuating means being located outside of said bellows and having a free actuating end and engaging at the other end thereof to the outer surface of one corrugation of said bellows, and the other actuating means being located in the interior of said bellows and engaging at one end thereof to the inner surface of said one corrugation and being connected at the other end thereof to said switch means.

2. A hermetically sealed switching device as set forth in claim 1, wherein said actuating means are arranged coaxially with said bellows.

3. A hermetically sealed switching device as set forth in claim 1, wherein said rigid connecting means comprise casing means completely covering said bellows, said opposite ends of said bellows being fixed to said casing means.

4. A hermetically sealed switching device as set forth in claim 1, wherein said casing means are constructed to form a guide for said one actuating means.

5. A hermetically sealed switching device as set forth in claim 3, wherein said bellows and said casing means are formed from metal.

6. A hermetically sealed switching device as set forth in claim 5, wherein said casing means comprise a cupshaped member having a transverse end wall at one end,

said closure means being in the form of a substantially plate-shaped member extending transversely through the other end of said cup-shaped member and being fluid tightly connected thereto, and said one actuating means having an operating portion projecting through a central opening in said transverse end wall to the outside of the casing means.

7. A hermetically sealed switching device as set forth in claim 6, wherein said casing means comprise further a transverse member extending spaced from and substantially parallel to said transverse end wall of said cupshaped member forming part of said casing means, and connecting means connecting said transverse member to said transverse end wall, said one actuating means comprise a second cup-shaped member having at one end thereof a transverse wall located between said transverse end wall and said transverse member of said casing means and being formed with openings through which said connecting means extend, said operating portion of said one actuating means projecting from said transverse wall of said second cup-shaped member through said central opening in said transverse end Wall and said closed end of said bellows abutting against said tansverse member.

8. A hermetically sealed switching device as set forth in claim 7, wherein said closed end of said bellows is fixedly held on said transverse member of said casing means by internal pressure in said bellows.

9. A hermetically sealed switching device as set forth in claim 7, wherein said closed end of said bellows is bonded at a central portion thereof to said transverse member of said casing means.

10. A hermetically sealed switching device as set forth in claim 7, wherein said one actuating means comprises further as second transverse member fixed to the other end of said second cup-shaped member and'engaging with an inner portion thereof said one corrugation.

11. A hermetically sealed switching device as set forth in claim 1, wherein said closure means comprises a substantially plate-shaped member of insulating material and wherein said switch means comprise at least two terminal members, each terminal member including a hollow pin extending through said plate-shaped member and having an expansion coefficient substantially equal to that of said plate-shaped member and being fluid tightly joined to the latter, and an electric conductor extending through the interior of said hollow pin fluid tightly welded thereto at least at the outer end of the latter.

12. A hermetically sealed switching device as set forth in claim 11, wherein one of said pins is formed with an aperture communicating with the interior of said bellows and wherein the conductor in said one hollow pin has at least between said aperture and said outer end of said pin a diameter smaller than the inner diameter of said hollow pin so as to form an annular passage between said conductor and said one pin so that the interior of said bellows may be filled with a gas of desired composi tion and pressure through said annular passage before said conductor is fluid tightly welded to the outer end of said one pin.

References Cited by the Examiner UNITED STATES PATENTS 1,706,523 3/1929 Churcher 200-168 3,038,980 6/1962 Lee 200-144 3,174,019 3/1965 Jansson 200-144 KATHLEEN H. CLAFFY, Primary Examiner,

H. O. JONES, Assistant Examiner,