US3223806A

US3223806A - Thermally controlled electrical switch having motion-amplifying lever means

Info

Publication number: US3223806A
Application number: US395260A
Authority: US
Inventors: Moro Antonio
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-05-29
Filing date: 1964-09-09
Publication date: 1965-12-14
Anticipated expiration: 1982-12-14
Also published as: ES346690A2; US3453581A; US3221126A; DE1465558A1; FR93768E; GB1134289A; GB1035515A; GB1070875A

Description

A. MORO TROLLED ELEG N-AMPLIFYING Dec. 14, 1965 THERMALLY CON TRICAL SWITCH HAVING MOTIO LEVER MEANS Filed Sept. 9, 1964 MF L "mum M Inventor )4/vr0/v/0 Moleo A ttorriey United States Patent 3,223,806 THERMALLY CONTROLLED ELECTRICAL SWITCH HAVING MOTION-AMPLIFYING LEVER MEANS Antonio Moro, Piazza Po 6, Milan, Italy Filed Sept. 9, 1964, Ser. No. 395,260 Claims priority, application Italy, Sept. 10, 1963, 18,556/ 63 4 Claims. (Cl. 200138) This invention relates to thermally controlled electrical switches and is an improvement in or modification of the invention disclosed in the specification of co-pending patent application Serial No. 279,104.

The said specification describes a thermally controlled electrical switch with a metallic housing for automatically closing and opening an electrical circuit in accordance with predetermined limits of temperature of the medium surrounding the thermal element of the switch, the said limits being adjustable from the exterior of the housing.

One object of the present invention is to render the adjustment of the switch more accurate and reliable.

In accordance with the present invention there is provided a thermally controlled electrical switch having a metallic housing, the switch being of the type in which a movable contact is subjected to the opposing actions of resilient means and of a bimetallic member in the form of a curved disc disposed on the base of the housing and adapted to reverse its curvature at predetermined limits of temperature of the said medium, and in which a movable contact is carried by an arm, disposed along the axis of the housing, of a bent lever the other arm of which extends parallel to the disc and is connected at one end to a fixed point, within the said housing, about which it can turn under the action of the disc and the said resilient means, whereby there is imparted to the movable contact a displacement greater than the movement of the disc so as to move it into and out of engagement with the fixed contact to close and open a circuit in which the switch is included, the fixed contact being carried, within the housing and facing the movable contact, by the free end of a supporting strip the other end of which is fixed to a metallic sector located between the insulating cover of the housing and an insulating ring bearing on a shoulder of th housing, and is electrically connected to a terminal carried by the cover.

An embodiment of the by way of example with drawing, in which:

FIG. 1 is an axial section of a switch according to the invention, taken on the plane of movement of the movable contact of the switch, and

FIG. 2 is a transverse section of IIII of FIG. 1.

The switch illustrated comprises a cylindrical metallic housing C in the base of which is located a bimetallic plate B of disc form associated with a flat spring M and a right angle lever L carrying the movable contact, and a cap or cover 1 of plastic insulating material carrying terminals 2 and closing the open end of the housing C, the cover 1 being clamped against an annular shoulder 7 within the housing with interposed rings of insulating material, by upsetting the upper rim of the housing.

invention will now be described reference to the accompanying the switch on the line The

terminals

2, 2" of the switch are of the fiat plug type, arranged at the centres of recesses 2 formed in the cap and adapted to receive socket sleeves. Such terminals are practicable and easy to use, and the walls of the recesses ensure complete electrical insulation, against the exterior.

On the lower ends 3, 3" of the terminals 2', 2" springs 4', 4" are threaded in electrical contact with those lower ends. The spring 4' establishes metallic continuity and hence electrical continuity between the terminal 2' and a movable contact 5 via a sector 6 and a flexible metallic strip 7 clamped between the sector 6 and the insulating ring 7'.

The spring 4" establishes metallic and hence electrical continuity between the terminal 2" and a normally fixed adjustable contact 8 via a sector 9 and a support in the form of a bent flexible strip 10 on which the contact 8 is fixed.

The movable contact 5 is fixed to the free end of the long arm, extending parallel to the axis of the housing C, of the lever L, the said long arm being straight. The normally fixed adjustable contact 8 carried by the end of the flexible strip 10 is disposed exactly facing the movable contact 5. It is fixed on the strip 10 together with a laterally extending projection 13 and an insulating plate 14 which covers the projection 13 on the side thereof nearest the wall of the housing C.

Parallel to a screw V provided for adjustment of the spring M (as described in the above-mentioned specification) there is provided for adjustment of the contact 8 a screw 11 which is screwed into the housing C and the inner end 12 of which bears against the insulating plate 14 and thus acts through it on the projection 13 to adjust the position of the contact 8 according to the extent to which the screw 11 is screwed into the housing C, the position of the contact 8 being maintained by the resilience of the strip 10.

A switch according to the invention as above described presents important advantages: in fact, it enables the cover or cap 1 to be made completely independent of the movable contact 5, and any deformation thereof has no effect on the position of the contact itself, which may further be put into the operating position before the cap is applied and consequently may be inspected before the switch is closed. The form of the terminals is also advantageous, permitting more rapid and certain connection of the cables of the electrical circuit.

What I claim is:

1. In a thermally controlled electrical switch having a metallic housing and a cover of insulating material, a movable contact, a bimetallic plate disposed in the base of the housing and adapted to reverse its curvature at predetermined limits of temperature of the medium surrounding the plate, an arm carying the movable contact, means for transmitting motions of the bimetallic plate to the arm thereby to multiply the motion of the bimetallic plate, and a fixed contact; the improvement comprising terminals carried by the cover, flexible conductors leading to the contacts, and spiral spring means in electrical contact at one end with the terminals and at the other end with said flexible conductors.

2. Structure as claimed in claim 1, and a screw adjustable in the housing by screwing it from the exterior thereof, said flexible conductorleading to said fixed contact being bent in such a manner that its end bears resiliently on the end of said screw thereby to permit positioning of the fixed contact relative to the movable contact.

3. Structure as claimed in claim 2, and a second screw side by side with said first-named screw and acting against said movable contact to adjust the rest position of said movable contact.

4. Structure as claimed in claim 1, in which said terminals are in the form of flat plugs, and peripheral insulating and protecting walls formed integrally with the cover and surrounding said plugs.

References Cited by the Examiner UNITED STATES PATENTS 1,522,786 1/ 1925 MacNeil 200-113 2,722,666 11/ 1955 Hodgkins 339-256 2,750,475 6/1956 Clason 200-139 2,751,464 6/1956 Short et al. 200-139 3,015,687 1/1962 Ruscito 339-198 FOREIGN PATENTS 596,423 7/1959 Italy.

ROBERT K. SCI-IAEFER, Acting Primary Examiner. BERNARD A. GILHEANY, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,223,806 December 14, 1965 Antonio Moro It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the grant, line 3, after "Italy," insert assignor to Soc. per Azioni Fratelli Borletti, of Milan, Italy, a company of Italy, line 12 for "Antonio Moro, his heirs" read Soc. per Azioni Fratelli Borletti, its successors in the heading to the printed specification, line 5, for "Antonio Moro, Piazza Po 6, Milan, Italy" read Antonio Moro, Milan, Italy, assignor to Soc. per Azioni Fratelli Borletti, Milan Italy, a company of Italy Signed and sealed this 31st day of January 1967.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer

Claims

1. IN A THERMALLY CONTROLLED ELECTRICAL SWITCH HAVING A METALLIC HOUSING AND A COVER OF INSULATING MATERIAL, A MOVABLE CONTACT, A BIMETALLIC PLATE DISPOSED IN THE BASE OF THE HOUSING AND ADAPTED TO REVERSE ITS CURVATURE AT PREDETERMINED LIMITS OF TEMPERATURE OFF THE MEDIUM SURROUNDING THE PLATE, AN ARM CARRYING THE MOVABLE CONTACT, MEANS FOR TRANSMITTING MOTIONS OF THE BIMETALLIC PLATE TO THE ARM THEREBY TO MULTIPLY THE MOTION OF THE BIMETALLIC PLATE, AND A FIXED CONTACT; THE IMPROVEMENT COMPRISING TERMINALS CARRIED BY THE COVER, FLEXIBLE CONDUCTORS LEADING TO THE CONTACTS, AND SPIRAL SPRING MEANS IN ELECTRICAL CONTACT AT ONE END WITH THE TERMINALS AND AT THE OTHER END WITH SAID FLEXIBLE CONDUCTORS.