US2703350A - Manually operated switch with trip-free overload - Google Patents

Description

March l, 1955 T. F. RoslNG 2,703,350

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lao J ZZ 98 l IOZ 2,4 94 H4 2,6 78 40 80 76 H0 H6 @www United States Patent MANUALLY GPERATED SWITCH WITH TRIP-FREE OVERLOAD Theodore F. Rosing, Whitefish Bay, Wis., assignor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware Application October 18, 1952, Serial No. 315,540 16 Claims. (Cl. 20D-116) This invention relates to electric circuit controlling mechanisms, particularly manually operated switches of the trip-free overload type especially adapted for use as a motor starter for polyphase alternating current motors.

Three pole starter ,switches of this type which are presently available are unnecessarily large, heavy, and 4expensive when used for controlling motors of low ratings.

lt is an object of this invention, therefore, to provide a three pole starter which is small, compact, light in weight, and inexpensive.

Another .object of this invention is to provide a three pole starter which may be made in sub-assemblies including pivots and when assembled is held in place by only two screws without the need of peening over the ends of such pivots.

These objects are accomplished by using a moulded insulating casing for supporting the contact assemblies arranged atly against the insides thereof, the thermal responsive overload elements with their coils outside the casing and removable without disturbing the contact assemblies, and the contact operating sub-assembly. This sub-assembly has a frame supporting the pivoted operating handle and the overload operating latch associated therewith, and the pivoted overload levers. The frame also has a cam slot for the latch pin. A contact carrier having spring biased contacts ts over the frame and tension springs react between such carrier and the overload levers to urge suchcarrier to open position upon release of the latch. This sub-assembly fits into the casing so that the pivot for the handle, the overload levers and their pivot, and the latch cam pin are held in place by the casing. A pair of screws holds the frame in place within the casing. The use of a single latch for controlling both normal and overload release, and the use of one pair of tension springs to normally urge the starter open upon manual operation or upon overload conditions, lessen weight, space required, cost, and simplify assembly. The case also has slide openings in slide arcing shields on the contact carrier to provide separate chambers for each set of contacts thus permitting the contacts for each pole to be placed nearer together and conserve space without damaging arcing therebetween.

The novel features, which are considered characteristic of the invention, 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, will best be understood from the following description of a specic embodiment when read in connection with the accompanying drawings, in which:

Fig. l is a top plan View of a starter embodying the present invention with the operating handle shown in On position;

2 is a sectional view taken on the line 2-*2 of 1g. F I igl. 3 is a sectional View taken on the line 3-3 of 4 is a sectional view taken on the line 4*-4 of Fig, 5 is a bottom plan View of the case for such starter with only the fixed Contact assemblies in place; and FFigi 6 is a sectional view taken on the line 6 6 of The electric circuit control mechanism illustrated in the drawings is a three pole starter rated at approximately one horsepower three phase on 110 through 550 volts. Completely assembled it yis approximately 2% inches wide, 31A; inches long, and 2% inches high. It is thus relatively small for its rating. The starter has a casing 10 moulded from insulating material with a solid top and open bottom. The top has a slot 12 through which the reice operating handle projects. At the line end (left as viewed in Fig. l) there are seats `and .holes in which are mounted line terminals 14. At the load end (right as so viewed) there is a seat and a hole in which is mounted a center load terminal 16 and seats in which are mounted terminal plates 1.8 constituting terminals for the heaters and the load. There are pockets 20 in the casing with openings (seeFig. 6) leading to the interior thereof for mounting the thermal element assemblies. At the line end the casing has two spaced projections having inner openings 22 in which arcing shields on the contact carrier operate.

A feature of this invention as the manner in which the contact assemblies are mounted to conserve space and simplify assembly. Each of. the six fixed contacts are mounted on separate contact assemblies so shaped that they are flatly held against the interior of the casing by the respective terminals. The upper ixed contact as sem'blies 24 are held in place as shown by the terminals 14. The contact assemblies 26 for the outer lower xed contacts are held in place by the terminals 28 for the heater and tongues 30 on such assemblies fitting in grooves in such casing. These assemblies have a vertical leg (see Figs. 5 and 6) tlushly recessed in the Wall of the casing to conserve space. The contact assembly 32 for the center lower fixed contact is held at the load end by the terminal 16 and at its other end by a tongue 34 fitting in a groove in the casing. The tongue end of this assembly is not folded into place until the contact operating sub-assembly is installed. All of the terminals and the terminal plates are threaded to receive binding head screws 36 by which the line, the load and the heater coils are properly connected.

Both the outer line terminals 14, with the starter On, are connected to the outer load terminals by heater coils 38 of thermal overload element assemblies of the self-soldering type. Such assemblies are of well known design and are shown and described in Patent No. 2,261,632 issued November 4, 1941, for Electric Circuit Mechanism. The ratchets 40 of these assemblies are within the casing 1t) where they can be engaged by the contact operating sub-assembly. The barrels 42 thereof extend upward into the pockets 20 where friction plates 44 are seated to engage and hold the assemblies in place. Heater coils 38 loosely encircle the barrels 42 and are held in place in such pockets by the binding screws 36 of terminals 28 and terminal plate 18. It is only necessary to remove such screws to change coils. When an overload occurs the eutectic solder in either or both of the assemblies will soften permitting the ratchet wheel 40 to rotate and the overload mechanism to trip the starter Oil.

The casing may be fitted with the contact assemblies and overload assemblies to form a sub-unit into which the contact operating sub-assembly is inserted. This latter sub-assembly has a U-shaped frame 46 with outturned feet 48 at the upper ends of its legs adapted to threadedly receive screws 50 by which this sub-assembly is held in the casing. An operating handle 52 is pivoted in such frame by pivot 54, the ends of which extend beyond the frame to be held in place by the walls of the casing. This handle is connected to a channel shaped link 56 by a pin 58. This link is positioned between the legs of such frame and the opstanding arms on a latch 60 to which it is pivoted by latch pin 62 to move the pivoted end of such latch vertically as said handle is moved from Off to On. The latch pin 62 extends through camming slots 64 in the frame 46. These slots have On slopes slanting slightly toward the line end, inter-mediate slopes slanting toward the load end, and Off slopes slanting about 45 toward the load end. In Fig. 2 the operating handle 52 is shown On and the latch pin 62 is in the On slopes of slots 64 with the latch 60 moved forward toward the line end. The slight slant of this slope cooperates with the various biasing springs to frictionally hold the lever in On against accidental displacement. When the operating handle is moved clockwise as so viewed the latch 60 will be moved towardv the load end by the intermediate slope. During such movement some of the slack will be taken up without opening the contacts. However, as the latch pin enters the Off slope the pitch of such slope will cooperate with the various biasing springs to cause a rapid movement of the latch to O. The latch has a tongue 66 which cooperates with the contact carrier as hereinafter explained. A tension spring 69 extends between the latch 60 and the operating handle 52 to resiliently urge the latch into engagement with the contact carrier.

The trip-free overload operates when there is an overload in either of the two outside branches of the threephase circuit through the starter by suddenly breaking the connection between the latch tongue 66 and the contact carrier even if the operating lever be manually held On. This mechanism includes two overload levers 70 pivoted on the outside of frame 46 by pivot 72 which extends beyond the sides of such frame. Both levers are the same except for being right and left handed. The pivot 72 extends into an elongated closed end bearing 74 to provide suicient bearing area and hold the pin in place. On their outer faces there is an anchor 76 for a contact carrier tension spring 78 which normally urges the contact carrier Off. A pawl 80 is seated in a pocket on such face and normally engages the ratchet 40 to hold 'I the overload levers in the locked position shown in Fig. 2. The inside faces of the levers 70 are cut away to form an operating space for the ends of latch pin 62 to hold it from displacement and to provide an abutment 32 by which the latch pin 62 may effect a reset. The inside faces also have an inwardly projecting pin 84 which over lies the latch 60 to knock such latch out of engagement with the contact carrier upon release of either of the levers 70. In order to lessen operating friction there is a small bearing pad 86 around the pin 72 and a thin arcuate ridge 88 at the outer edge of such lever which provide relatively small bearing areas. As shown in Fig. 3 the outer surface of the overload levers 70 is in sliding contact with a portion 90 on the easing 10 to hold such overload levers on pin 72 without riveting it. These levers in turn hold the latch pin 62 in place (see Fig. 6) without riveting it. The pins 54 and 58 are held against longitudinal displacement by the inner surfaces of the narrower upper chamber of the casing 10. Thus all the pins are held properly assembled without riveting them. This facilitates assembly and repair and cuts costs.

The movable contacts are carried on a contact carrier 92 which reciprocates within a lower chamber of the casing 10. This carrier has a wall 94 the ends of which are guided by the inner surfaces of such housing. A hori- Zontal plate 96 projects forwardly from wall 94 and its forward edge engages the inner surface of the casing at the line end when the starter is Closed. The plate 96 has notches 98 in which are mounted movable contact assemblies 100 held in place and provided with uniform contact pressure by compression springs 102 fitted within such notches. Whenever the contact carrier 92 is Closed these springs compress as is shown in Fig. 2 to maintain Cil positive uniform engagement between the contacts. A

novel characteristic of this invention is the use of arcing shields 104 projecting forwardly from the wall 94 and slidablein the openings 22. Each pair of contacts operates in its own compartment and is separated from each other by a wall of insulation eliminating the possibility of arcing between the lines and such separated contacts. On the rear of wall 94 there is a projecting nose 1.06 which has a groove 108 on the underside for receiving the latch tongue 66. When the tongue 66 is in groove 108, movement of the operating handle 52 will slide the carrier 92 back and forth from Open to Closed. A pair of side bars 110 extend rearwardly from the wall 94 to a rear wall 112. Small cleats 114 provide eyes to which the tension springs 78 are attached. These springs extend between such cleats and anchors 76 on the overload levers, and in addition to normally urging the carrier Open, they also perform the additional function of swinging the overload levers into the tripped position shown in Fig. 4 when the thermal elements release.

To assemble the contact operating sub-assembly the operating handle 52 is pinned to the link 56 and the tension spring 68 hooked to the operating handle and to the latch 60. The operating handle and latch are then slid intothe frame 46 and the pivot 54 inserted. Then the latch 60 and link 56 are properly alined with the slot 64 and the latch pin 62 inserted. The overload levers 70 are kthen mounted on the pin 72. The contact carrier 92 with the contact assemblies 100 and tension springs 78 in place is then slid over the bottom of frame 46 and the spring 78 hooked to the anchors 76 to hold the contact carrier in OE position. While in this position the sub-assemb1y is inserted as a unit into the casing from the bottom. The top of the operating handle 52 will project through the slot 12 and the fastening screws 50 are threaded into the feet 48 to hold the entire unit assembled. As previously pointed out, the various pins and pivots are held against longitudinal displacement without the necessity of peening over their ends. An insulating plate 116 is seated on the bottom of the frame 46 to insulate the center lower xed contact assembly 32 from such frame when such assembly is bent over such plate with the tongue 34 seated as shown. A bottom i8 is secured to the casing 10 by rivets 120 or other fastening devices to hold all the lower xed contact assem blies with their tongues properly seated.

When assembled as previously described, the starter switch will be in the overload released position shown in Fig. 4 with the switch open but the handle 52 On. ln such position the abutment 82 on the overload levers 79 is in engagement with the latch pin 62. As the operating handle 52 is swung to Off position, forcing the latch pin 62 downwardly, the overload levers 70 are swung clockwise, as viewed, to the position shown in Fig. 2. The pawls 80 will engage the ratchets 40 and hold the overload levers 70 in such position (provided the solder in the thermal heating element is then solid). As the latch pin 62 is moved downwardly in the cam slots 64 it will also be moved to the right as viewed, pulling the latch 60 with it. At this time the contact carrier 92 will be restrained from rearward movement by the vertical leg of the center lower fixed contact assembly 32 and as a consequence the latch 60 will be moved rearwardly with respect to such contact carrier and the tongue 66 will slip into the groove 108. The starter is then Off and latched for overload release. When the operating lever 52 is swung from Off to On the latch pin 62 will tirst ride along the steep slopes of the slots 64 rapidly forcing the contact carrier toward On position. At the end of the steep slopes the resistance to movement of the contact carrier is abruptly lessened and the switch will close with a quick action. Slight rearward slopes on the slots 64 help keep the pin 62 in the fully On position shown in Fig. 2. To manually open the starter switch, the operating lever 52 is flicked to the Off position. As the latch pin 62 moves downward along the intermediate slopes of slots 64 the carrier 92 is moved rearwardly enough to take up some of the slack between it and the Contact assemblies 100. However, as such pin enters the steep slopes of slots 64, the tension in the carrier springs 78 will be strong enough to cause a quick sliding of the pin down to the lower position with a snap opening of the contacts. With the starter in the On position current flows through the two outer lines of the three-phase system, the two outer bridging contacts, and the heater coils to the load. lf there is an overload in one or both of these lines the entectic solder in the affected thermal element or elements will soften permitting one or both ratches 40 to turn under the influence of the power in one or both of the springs 70 letting one or both of the overload levers 70 swing rapidly to the position shown in Fig. 4. During such movement the knock-out pin 84 on the released overload lever will strike against the latch 60 and knock the tongue 66 out of the groove 108, permitting the carrier 92 to move rearwardly and disengage the contacts.

Although there is shown and described a specific starter switch, many modifications thereof are possible. The invention is not to be restricted except so far as is necessitated by the prior art andthe spirit of the appended claims.

l claim:

1. In a circuit controller, a fixed contact, a contact i carrier movable back and forth with respect to said fixed contact and having a contact engageable and disengageable with said ixed contact to open and close the circuit, spring means for biasing said carrier for circuit opening movement, a latch normally engaged with said carrier to mechanically restrain said opening movement, and an overload responsive assembly having a lever strikable against said latch upon occurrence of overload condi tions to disengage said latch from said carrier, said lever being connected to said spring means to supply force to cause said lever to strike said latch and bring about said disengagement.

2. A circuit controller as claimed in claim l in which there is a cam with which said latch is operably associated to move said latch and said carrier back and forth to open and close the circuit, and an operating handle associated with said latch to move said latch relative to said cam.

3. A circuit controller as claimed in claim 2 in which said cam has three portions defining for saidlatch and carrier hold in Contact engaging position, slow movement toward contact disengaging position, and rapid movement toward the latter position, respectively.

4. A circuit controller as claimed in claim 2 in which said overload lever has a part operatively associable with said latch and said operating handle to reset said lever as said handle is moved to contact disengaging position after overload release.

5. A three pole starter having a moulded insulating casing with a closed top having a slot for an operating handle, three upper fixed Contact assemblies including contacts. mounted flatly against the inside surfaces of said casing and having one end thereof held by line terminals, line terminals secured to said assemblies and leading to the outside of said casing, three lower fixed contact: assemblies including contacts mounted ilatly against the inside of said casing, two of said lower assemblies hav ing portions seated in recesses in the inner sides of said casing, heater coil terminals securing one end of each of said two assemblies and leading to the outside of said casing, the other of said lower assemblies being connected to a load terminal, a load terminal secured to said one of said assemblies and leading to the outside of said casing, pockets in the top of said casing, an overload responsive assembly carried by said casing and having heater coils mounted in said pockets and removable without disturbiing said contact assemblies, and a movable contact operating sub-assembly including contacts alined with the contacts of said other contact assemblies fitted within said casing from the bottom thereof having an operating handle projecting through said slot, said subassembly being held in place byy a fastening device extending through said top into engagement with said subassembly.

6. A three pole starter as claimed in claim 5 in which said lower fixed contact assemblies have tongues fitting in grooves in said casing to fix the position of the end of said assemblies remote from said terminals.

7. A three pole starter as claimed in claim 5 in which said casing has slide openings between said contact assemblies and said sub-assembly has a movable contact carrier having arcing shields slidable in said openings to form separate chambers for each set of contacts.

8. A three pole starter as claimed in claim 5 in which said sub-assembly includes: a pivot for said operating handle the ends of which cooperate with said casing to prevent longitudinal displacement of said pivot; latch pin the ends of which are engaged by overload levers to prevent longitudinal displacement of such latch pin; an overload pin; and overload levers mounted on said overload pin and having end enclosed bearings holding said pin against longitudinal displacement; said levers having sliding contact with said casing to prevent removal thereof from said pin when said sub-assembly is in said casing.

9. In a three pole starter having a moulded insulatingcasing provided with three upper and three lower fixed contacts arranged in three sets adapted to be engaged and bridged by movable contacts to close each circuit between each set of contacts, a sub-assembly for operating said movable contacts comprising a metal frame adapted to be held within said casing by two screws threaded therein from outside said casing, an operating handle pivoted to said frame, a movable contact carrier slidable relative to said frame and carrying bridging contacts engageable with and disengageable from said fixed contacts, a latch engaging abutment on said carrier, a carrier latch having a portion normally biased into engagement with said abutment to transmit back and forth motion of said latch to said carrier, a latch pin for said latch, said frame having a cam which said latch pin engages to move said latch back and forth to open and close said contacts, a link connecting said latch pin and said operating handle whereby swinging of said handle causes said latch pin to move relative to said cam and Said latch to move back and forth, an overload lever pivoted to said frame and normally held in locked position, a tension spring between said overload lever and said carrier to urge said carrier to starter Off position, said lever having a latch engaging peg adapted to strike and disengage said latch from said carrier upon release of said lever by an overload responsive element, and an overload responsive element carried by said casing and normally holding said overload lever in locked position.

10. A three pole starter as claimed in claim 9 in which: a pivot for said operating handle extends beyond said frame and is held in place by said casing; said overload lever holds said latch pin in place; a pivot for said overload lever fits in an enclosed end bearing in said lever and is held in place thereby; and said casing holds said overload lever in place on said pivot whereby said pivots and pin are held in place without peening the ends thereof.

ll. A three pole starter as claimed in claim 9 in which said casing has a pocket in the top thereof and said overload responsive element includes a heater coil positioned in said pocket.

l2. The combination with a movable switch element biased toward circuit opening position, of a pivoted operating handle movable from Off to On for operating said switch element, a latch normally biased into engagement with said switch element and connected with said handle, a cam operably associated with said latch to cause said latch to move said switch element as said latch is moved by said handle, and an overload device responsive to strike against said latch upon occurrence of overload conditionsv to disengage said latch from said switch element and permit said element to move to circuit open position Without moving said handle.

13. The combination claimed in claim 12 in which said overload is resettable by said handle as said handle is. moved to Ofi.

14. The combination claimed in claim l2 in which there is a spring for biasing both said switch element and said overload device.

l5. In a three pole starter having a moulded insulating casing provided with upper and lower fixed contacts arranged in three sets adapted to be engaged by bridging contacts to close the circuit between each set, a sub-assembly for operating said bridging contacts insertible in said casing as a unit and comprising a metal frame having spaced legs with feet on the upper ends thereof, said feet being held by screws threaded therein from outside said casing, au operating handle positioned between said legs, a. pivot for said handle loosely mounted in said legs with the ends thereof projecting beyond said legs so as to be restrained by said casing from displacement, a movable contact carrier slidable within said casing and having spring anchors on opposite sides of said frame, said carrier having bridging contacts engageable with and disengageable from said fixed contacts, a latch engaging abutment on said carrier in alinement with the central part of said frame, a carrier latch mounted between said legs and having a portion normally biased into engagement with said abutment, camming slots in said legs, a latch pin slidable in said slots and pivotally mounting said latch, a link mounted betweensaid legs on said latch pin and pivoted to said operating handle whereby swinging of said handle causes said latch pin to move up and down in said camming slots and said latch to move back and forth to operate said bridging contacts, an overload lever pivot carried by said legs, an overload lever pivotally mounted on each end of said pivot outside of said legs, a tension spring between each of said overload levers and said carrier to urge said carrier to starter Off and bias said levers for latch disengagement, said levers having a latch engaging peg adapted to strike and disengage said latch from said carrier upon release of both or one of said levers, said levers having portions overlying -said latch pin to prevent displacement thereof, said levers having portions loosely engageable with said casing to hold said levers on said overload pivot, and overload responsive elements carried by said casing and normally holding said overload levers in locked position.

16. A three pole starter as claimed in claim l5 in which said overload levers have abutments engageable by said latch pin whereby said latch pin resets said overload levers as said handle is moved from On to Off after an emergency release of an overload lever.

References Cited in the tile of this patent UNITED STATES PATENTS 2,265,004 Pierce et al. Dec. 2, 1941 2,361,848 Johnson Oct. 31, 1944 2,367,382 Taylor Jan. 16, 1945

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