US2606062A

US2606062A - Ambient temperature compensating means for automatic circuit breakers

Info

Publication number: US2606062A
Application number: US43824A
Authority: US
Inventors: Besag Ernst; Hill Walter Edward; Wintle Thomas Daniel Guy
Original assignee: JA Crabtree and Co Ltd
Current assignee: JA Crabtree and Co Ltd
Priority date: 1947-08-14
Filing date: 1948-08-12
Publication date: 1952-08-05
Anticipated expiration: 1969-08-05
Also published as: BE484373A; US2523897A; GB624598A; DE896677C; FR970308A

Description

Aug. 5, 1952 E. BESAG ET AL 2,606,062

AMBIENT TEMPERATURE COMPENSATING MEANS FOR AUTOMATIC CIRCUIT BREAKERS Filed Aug. 12, 1948 2 SHEETS-SHEET l lrmen! (5W ufazam 744222 Mam TIME 5 C M 1 (5MALA/UZL/ Attor'neyi Aug. 5, 1952 E. BESAG AL 2,606,062

AMBIENT TEMPERATURE c ENSATING MEANS FOR AUTOMATIC CIRCUIT BREAKERS 2 SHEETS--SHEET 2 Aug 12 W lllumm 'i fi 5M 9 y I I Attorney;

Patented Aug. 5, 1952 AMBIENT TEMPERATURE COMPENSAT- ING MEANS FOR AUTOMATIC CIRCUIT BREAKERS Ernst Besag and Walter Edward Hill, Streetly,

and Thomas Daniel Guy Wintle, Walsall, Eng- 7 land, assignors to' J. A. Crabtrce & Co. Limited, Walsall, S-tafiordshire, England, a British com- Application August 12, 1948, Serial No. 43,824

- In Great Britain August 14, 1947 This invention relates to improvementsin the trip mechanism of automatic circuit breakers and similar electrical switchgear, and is particularly '1 Claims. (Cl. 297-45) concerned with mechanism, operated by thermal release overload devices, and which provides ambient temperature compensation, for use with motor protective switches.

According to this invention, a rotationally adjustable member is formed with a cam adapted for adjusting the ambient temperature compensating means which is engageable by the trip mechanism upon the occurrence of overload conditions. Such ambient temperature compensating means may be in the form of a bimetallic blade adapted to be rocked in see-saw fashion upon the stem of an adjusting screw, so that the gap between the blade and the trip mechanism may be varied.

In order to enable the invention to be readily understood, reference will now be made to the accompanying drawings illustrating, by way of example, one construction for carrying the invention into efiect, in which drawings:

Figure 1 is a perspective view of a casing for the ambient temperature compensating means of our present invention, showing the same mounted on the end of an overload box. p

Figure 2 is a plan view of the device shown in Figure 1, the cover of the casing having been removed to disclose the interior mechanism.

Figures 3 and 4 are sectional views on the lines I1'IIII and IV-IV, respectively; of Figure 2, with the cover mounted in position.

Figure 5 is a sectional view on the line V-V of Figure 3.

Figure 6 is a sectional view on the line VI-VI of Figure 4.

Referring to the drawings, a cap or sleeve (1 is rotationally adjustable on a boss b upstanding from an insulating box casing c secured to a back plate I by bolts 2, which casing houses thermal overload release devices (not shown), which devices are operative to actuate a trip bar m. For a more complete understanding of the construction and operation of the present invention, reference is made to our Patents 2,523,897 of September 26, 1950', relating to Thermal Overload Release Device for Automatic Circuit Breakers, and 2,527,907 of October 31, 1950, relating to Automatic Circuit Breaker Having Thermal Overload Release Units, in which patents there is an adequate disclosure of thermal overload release devices, particularly trip bars and their associated mechanisms corresponding to the trip bar m of the present invention. The

cap a is formed on its upper surface with a cam d engageable by one end of a bimetallic blade e which serves as a means for compensating for ambient temperature, and around said cap is arranged a part cylindrical metal clip or'sleeve having graduations or markings thereon which co-operate with a fixed pointer g on the cover h of the casing c for indicating the setting ofthe device.

Inside the cap a, a bow-shaped blade spring i is provided, which spring is disposed parallel to the axis of the boss I) in a narrow slot 7c in the latter. For the purpose of locating the spring i, its inwardly extending ends are engaged in recesses k in the ends of the boss I). The spring i acts for taking up tolerances'between the cap a and its bearing on boss b, and for frictionally retaining the cam d in any desired position.

A small outwardly-projecting stop c on the boss b, has abutting engagement with a complementary inwardly-projecting luga on the cap a for the purpose of limiting rotational adjustment of the latter in either direction of rotation.

The end of the bimetallic blade e remote from the cam, is adjustable in relation to the trip bar m, and for this purpose, said blade is acted upon between its ends by any suitable adjusting means. According to one example, a screw n, seated by spring pressure in a semi-cylindrical threaded groove 0 in the casing c, is operated so that a shoulder 11. thereon is pressed against the face of the blade e so that the gap as between the end of said blade and the end oftrip bar m may be varied. ,1

For imparting guidance to screw 11, areduced stem n on said screw may extend freely through an opening in the blade 6 and into an opening 0 in the casing c. The screw n, which may be held in the threaded groove 0 of the casing c by a spring blade p of right-angled shape, extends through an opening in the longer arm p of said spring blade the other spring arm p of said spring blade being engaged beneath a shoulder c of the casing c for stressing said spring. The downward thrust exerted by the spring blade p on the screw 11. not only serves to keep said screw seated in the semi-cylindrical threaded groove 0, but also serves to maintain said screw in its various positions of adjustment. The kerfed, outer end of screw n is accessible through an opening h in the cover h, this opening being closed by a spring clip 1' when adjustment has been efiected. The clip 1', which prevents unauthorized access to the adjusting screw n, is bent to extend over the opening h in the end of the casing, one end of said clip being engageable in a groove 3 in the bottom of the casing c, and the other end having a small circular opening which is pressed over a stud t on the top of; the cover It for retaining the latter in place.

After initial adjustment of the bimetallic blade c has been effected in the factory by turning the screw n, subsequent adjustment may be made by rotating the knurled cap a and cam 1' o as to rock the blade e upon the stem n for variation of the gap :0.

Having thus described our invention, we claim:

1. An ambient temperature compensating means for automatic circuit breakers of the thermal overload release type which include trip mechanism and a trip bar for actuating said mechanism, said compensating means comprising an elongated bimetallic blade; a casing enclosing said ambient temperature compensating means;

said casing having an opening through a wall thereof and having a threaded, substantially semi-cylin rical groove on. a p t h r of n alignment with said opening; a screw in threaded engagement with said groove and passing transversely through an opening in the intermediate portion of said blade; means operatively engaging said screw to retain said screw in engage,- ment with said groove, said screw constituting a pivotal mounting for said blade and having a shoulder thereon engageable with said blade whereby rotation of; said screw will move said blade laterally to Very the position of its pivotal mounting, one end of said blade being normally spaced from an end of the trip bar of the circuit breaker but engageable by said end of said trip bar upon the occurrence oi overload conditions; and adjusting means en agin he othe end o said blade to rock the same about said screw to vary the spacing between the first-mentioned end of said blade and said one end of said trip bar independently of the position of the pivotal mounting of said blade.

2. An ambient temperature compensating means as defined'in claim 1 in which the casing is provided with a second opening in axial alinement with the first-mentioned opening, and in which an end of said screw enters said second opening whereby said screw is guided in its axial movements.

3. An ambient temperature compensating means as defined in claim 1 in which the casing is provided with a second opening of lesser diameter than that of said first-mentioned opening and in axial alinement therewith, and in which said screw has a reduced terminal portion which enterssaid second opening wherebysaid screw is guided in its axial movements.

4. An ambient temperature compensating means for automatic circuit breakers of the thermal overload release type which include trip mechanism and a trip bar for actuating such mechanism, said compensating means comprise ing an elongated, bimetallic blade; a casing en closin said ambi n t mperatu e c mp nsatin mea aid casing havin a p i g thr u h a wall thereoi and having a threaded, semi-cylindrioal groove on a portion the in align ment with said opening; a screw in threaded engagement with said groove and passing transversely through an opening in the intermediate portion of said blade, said screw constituting a pivotal mounting for said blade and having a shoulder thereon engageable with said blade whereby rotation of said screw will move said blade laterally to vary the position of its pivotal mounting, one end of said blade being normally spaced from an end of the trip bar of the circuit breaker but engageable by said end of said trip bar upon the occurrence of overload conditions; adjusting means engaging the other end of said blade to, reel; the same about said screw to vary the spacing between said first-mentioned end of said blade and said end of said trip bar independently of the position of the pivotal mounting of said blade; and an L-shaped spring having an aperture in one arm thereof through which said screw passes and the other arm of which resiliently engages. s id cas n o keep a d sc contact wi h the semiyl ndrical threa ed groo e in sa easing:

5-. an ambient empera ure compensating m ans r aut mat circui breaker oi h t ermal ove load. release type hich inohldes. trip mechanism a a p ba f r actuatin sllol mechanism said ompensa ing means oom ing an elong ted! bimeta lic blade pivotally m unted. intermed ate its e ds, ne end f sai bla e be ng normall spaced irom an. end o th t ip bar o he circui breaker but eneag ble y sa end o sai rip ar pon th o eno of overload conditions; a casing enclosing said ambient tempera re compe sa ing me ns; a boss project ng i wardly oi s d ca ing; a cap r tatab y moun ed sa d bo s; and a cam on said cap and rotatable therewith, saidocam ene s ng e h r endo s id lade to roc the l de about its piv ta moun ng to vary h spacing between, the fi -m n ioned nd oi said b a e nd s id end of s id r p b n 6. An ambient temperature compensating means s d fin d in cla m in wh h apo n is p s t ed on the casin and i wh ch e cap s p d d w th markings, coop ration b e n said pointer and markings indicating the position o a d am An ambi nt. emp a ure comp nsa in means as defined inrclairn 5 in which a bow, shaped pr ng is. dispo ed par l el to he s of the boss in a narrow slot in said boss and has its intermediate bowed por ion ir oti idllv engag ng t e in er r o sa d cap:

ERNST BESAG. WALTER EDWARD HILL. THOMAS DANIEL GUY R FERENCES CI ED The following references are of record in the file of this patent:

UNITED STATES. PA'I'ENTS Fet e s-so-rms-o-f-s Sept 8, 1 .2