Abstract:
A molded case circuit breaker includes first and second pairs of separable electrical connectors disposed in adjacent poles of the circuit breaker and spaced apart by a spacing less than the spacing between externally extending electrical terminals for making external electrical connections to the same adjacent poles of the circuit breaker. The closer spacing is achieved by a plurality of integrally formed, molded projections formed in the base of the molded case of the circuit breaker for positioning movable portions of the lower electrical contacts spaced apart in the base by the above closer spacing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The invention disclosed herein relates to molded case circuit breakers. The inventions disclosed in the following four commonly assigned U.S. patent applications also relates to molded case circuit breakers: U.S. patent application Ser. Nos. 440,680; 440,681; 440,682; and 440,683, all of which were filed on Nov. 10, 1982. In addition, commonly assigned U.S. patent application Ser. No. 450,857 filed on Dec. 17, 1982 also relates to molded case circuit breakers. 
     The following six commonly assigned U.S. patent applications were all filed in the U.S. Patent and Trademark Office on Dec. 19, 1983 and relate to molded case circuit breakers: Ser. No. 562,647 filed by Alfred E. Maier and entitled Molded Case Circuit Breaker With An Apertured Molded Cross Bar For Supporting A Movable Electrical Contract Arm; Ser. No. 562,643 filed by Robert H. Flick and Walter K. Huffman and entitled Molded Case Circuit Breaker With Movable Upper Electrical Contact Positioned By Tension Springs; Ser. No. 562,648 filed by Robert H. Flick and Walter K. Huffman and entitled Molded Case Circuit Breaker With Improved Operating Mechanism; Ser. No. 562,664 filed by Alfred A. Maier and entitled Molded Case Circuit Breaker With Adjustable Stationary Lower Electrical Contact; Ser. No. 562,602 filed by Robert H. Flick and Walter K. Huffman and entitled Molded Case Circuit Breaker With Movable Lower Electrical Contact; and Ser. No. 562,603 filed by Robert H. Flick and Walter K. Huffman and entitled Molded Case Circuit Breaker With Movable Upper Electrical Contact Positioned By Torsion Springs. 
     Finally, the following five commonly assigned U.S. patent applications were filed in the U.S. Patent and Trademark Office on Jan. 9, 1984 the same day as this patent application and relate to molded case circuit breakers: Ser. No. 569,059 filed by Alfred E. Maier and entitled Molded Case Circuit Breaker With With Cross Bar Stop Molded In Base Of Case; Ser. No. 569,058 filed by Dante Bagalini and entitled Molded Case Circuit Breaker With Resettable Combined Undervoltage And Manual Trip Mechanism; Ser. No. 569,056 filed by Kurt A. Grunert and Joseph F. Changle and entitled Molded Case Circuit Breaker With Handle Lock; Ser. No. 569,055 filed by Joseph J. Matsko, Kurt A. Grunert and Bruce R. Terhorst and entitled Solenoid Operator Circuit For Molded Case Circuit Breaker; and Ser. No. 569,054 filed by Kurt A. Grunert and Walter K. Huffman and entitled Molded Case Circuit Breaker With Single Solenoid Operator For Rectilinear Handle Movement. 
     BACKGROUND OF THE INVENTION 
     A. Field of the Invention 
     The device of the present invention generally relates to molded case circuit breakers and, more particularly, to structural components thereof configured to provide dimensionally small, sturdy and effective electrical circuit breakers. 
     B. Description of the Prior Art 
     Circuit breakers and, more particularly molded case circuit breakers are old and well known in the prior art. Examples of such devices are diclosed in U.S. Pat. Nos. 2,186,251; 2,492,009; 3,239,638; 3,525,959; 3,590,325; 3,614,685; 3,775,713; 3,783,423; 3,805,199; 3,815,059; 3,863,042; 3,959,695; 4,077,025; 4,166,205; 4,258,403; and 4,295,025. In general, prior art molded case circuit breakers have been provided with movable contact arrangements and operating mechanisms designed to provide protection for an electrical circuit or system against electrical faults, specifically, electrical overload conditions, low level short circuit or fault current conditions, and, in some cases, high level short circuit or fault current conditions. Prior art devices have utilized an operating mechanism having a trip mechanism for controlling the movement of an over-center toggle mechanism to separate a pair of electrical contacts upon an overload condition or upon a short circuit or fault current condition. Such trip mechanisms have included a bimetal movable in response to an overload condition to rotate a trip bar, resulting in the movement of the over-center toggle mechanism to open a pair of electrical circuit breaker contacts. Such prior art devices have also utilized an armature movable in response to the flow of short circuit or fault current to similarly rotate the trip bar to cause the pair of contacts to separate. At least some prior art devices use blow-apart contacts to rapidly interrupt the flow of high level short circuit or fault currents. In the design of small molded case polyphase circuit breakers, it is often desirable to have adjacent pole mechanisms spaced closer than adjacent external electrical terminals. Among other advantages, the closer spacing of adjacent pole mechanisms enables thicker and stronger molded case walls to be used. Generally, to achieve the closer spacing of adjacent pole mechanisms, prior art devices used relatively wide lower electrical contacts to compensate for contact misalignment or used separate spacers for shifting the lower electrical contact carriers or used angularly disposed external electrical terminals to compensate for the contact misalignment. 
     While many prior art devices have provided adequate protection against fault conditions in an electrical circuit, a need exists for dimensionally small molded case circuit breakers capable of fast, effective and reliable operation and, more specifically, for components thereof that provide closer spacing between adjacent pole mechanisms than between adjacent electrical terminals without resorting to the disadvantageous measures referred to hereinabove. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new and improved circuit breaker. 
     Another object of the present invention is to provide a new and improved molded case circuit breaker having components that effectively and inexpensively achieve closer spacing between adjacent pole mechanisms than between adjacent electrical terminals. 
     Briefly, the present invention relates to a molded case circuit breaker having a plurality of integrally formed molded projections formed in the base of the molded case of the circuit breaker for positioning components of adjacent lower electrical contacts in adjacent poles of phases of the circuit breaker spaced apart by a distance less than the distance between adjacent externally extending electrical terminals of the same adjacent poles of the circuit breaker. Each lower electrical contact includes a first rotatable pin movable both rotatably and laterally with respect to a lower, formed stationary member. The integrally formed molded projections each include a tapered or sloped upper surface for contacting the rotatable pin and for laterally shifting the rotatable pin with respect to the lower formed stationary member to achieve the closer spacing referred to above. Each rotatable pin is laterally held in position in each pole of the circuit breaker by its engagement with elongated vertically extending surfaces of the molded projections and/or contacting portions of the lower formed stationary members of the lower electrical contacts. In this manner, the base portion of the molded case of the circuit breaker may be made with thicker and stronger molded case walls. In addition, arc plates of greater cross sectional plate area may be used in an electrical arc chute and a larger arc extinguishing area may be provided in each pole of the circuit breaker. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects and advantages and novel features of the present invention will become apparent from the following detailed description of the preferred and alternative embodiments of a molded case circuit breaker illustrated in the accompanying drawing wherein: 
     FIG. 1 is an enlarged, cross sectional view of a molded case circuit breaker according to the teachings of this invention, depicting the device in its CLOSED and BLOWN-OPEN positions; 
     FIG. 2 is an enlarged, fragmentary, cross sectional view depicting the bottom cover or base of the device of FIG. 1; and 
     FIG. 3 is an enlarged, plan sectional view of the device of FIG. 2 taken along line 3--3 of FIG. 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is an improved molded case circuit breaker 30 (FIG. 1) of the type which includes upper and lower electrical contacts 52, 50, an arc chute 54, a slot motor 56, an operating mechanism 58 for moving the contacts 50, 52, and a trip unit 82 for initiating operation of the operating mechanism 58. A detailed description of such a circuit breaker 30 can be found from page 7, line 30 to page 27, line 26 of U.S. patent application Ser. No. 562,643, filed Dec. 19, 1983, which description is incorporated hereinto by reference. 
     In the present circuit breaker 30, the base 34 includes a plurality of integrally formed, molded projections 410, 412, 414 and 416, (FIGS. 2 and 3) each having a tapered or sloped upper surface 418 for properly and accurately positioning each rotatable pin 78 of each lower electrical contact 50 in each of the three poles or phases of the circuit breaker 30 to achieve closer spacing between adjacent pole mechanisms than the spacing between adjacent terminals 38A, B and C. More specifically, the spacing between the center lines of adjacent line terminals 38A, B and C (FIG. 3) is greater than the spacing between the center lines of adjacent pairs of contacts 50 and 52 disposed in adjacent poles of the circuit breaker 30. This closer spacing of adjacent pairs of the contacts 50 and 52 is inexpensively achieved and accurately determined and maintained by the engagement of the molded projections 410, 412, 414 and 416 with the rotatable pins 78 disposed in each pole of the circuit breaker 30. Since each rotatable pin 78 is capable of being shifted or moved laterally with respect to the contacting portions 62E and 62F, the contact arms 66, fixedly secured on the rotatable pins 78, in adjacent poles of the circuit breaker 30 may be spaced closer together than the corresponding line terminals 38, thereby to properly align each contact arm 66 with its associated and similarly closely spaced upper movable contact arm 308. Adjacent upper electrical contacts 52 are mounted in the cross bar 84 (FIG. 1) at the same relatively close spacing as compared to the spacing between adjacent line terminals 38. Sufficient clearance must be provided between the contact arms 66 and their respective contacting portions 62E and 62F in order to achieve the desired amount of lateral shift or movement of the rotatable pins 78 and the contact arms 66 in the outer poles of the circuit breaker 30 in the direction of the center pole of the circuit breaker 30. 
     When the lower electrical contact 50 associated with the outer pole of the circuit breaker 30 corresponding to the line terminal 38A is inserted in the base 34, the outward end of the rotatable pin 78 engages the tapered surface 418 of the molded projection 410 to gradually laterally shift or move the rotatable pin 78 by a predetermined desired amount along the tapered upper surface 418 in the direction of the center pole of the circuit breaker 30. When fully seated within that pole of the circuit breaker 30, the rotatable pin 78 is held against both a vertically extending surface of the molded projection 410 and the contact arm 66 is positioned against the contacting portion 62E thereby to retain the contact arm 66 laterally shifted in the direction of the center pole of the circuit breaker 30. 
     The molded projections 412 and 414 are symmetrical about the center line of the center pole mechanism of the circuit breaker 30 and their vertically extending surfaces bear against opposite longitudinal ends of the rotatable pin 78 to maintain the movable contact arm 66 positioned on the center line of the center pole mechanism and out of contact with the contacting portions 62E and 62F. 
     The molded projection 416 in the outer pole of the circuit breaker 30 associated with the line terminal 38C laterally shifts or moves the rotatable pin 78 toward the center pole of the circuit breaker 30. This lateral shifting is achieved in the same manner as described hereinabove with respect to the molded projection 410. However, the contact arm 66 in the pole of the circuit breaker 30 associated with the line terminal 38C is retained in position by the engagement of one longitudinal end of the rotatable pin 78 with a vertically extending surface of the molded projection 416 and by the engagement of the contact arm 66 with the contacting portion 62F. 
     To maintain proper alignment between respective pairs of electrical contacts 50 and 52 in each pole of the circuit breaker 30, the apertures 62B formed in the stationary member 62 of each lower electrical contact 50 are oblong to accommodate the closer spacings between adjacent compression springs 70 in adjacent poles of the circuit breaker 30 and to enable a particular lower electrical contact 50 to be used in any one of the poles of the circuit breaker 50. 
     In a specific embodiment of the present invention, adjacent pole mechanisms or pairs of electrical contacts 50 and 52 are spaced apart by approximately 1.328 inches while the spacing between adjacent line terminals 38 is approximately 1.375 inches. Thus, while the center lines of the line terminal 38B and of its associated pair of electrical contacts 50 and 52 are coincident, the center line of the line terminal 38A (FIG. 3) is located approximately 0.047 inch to the left or outwardly of the center line of its associated pair of electrical contacts 50 and 52. Correspondingly, the center line of the line terminal 38C is located approximately 0.047 inch to the right or outwardly of the center line of its associated pair of electrical contacts 50 and 52. In the same specific embodiment, the angle of the sloped or tapered upper surfaces 418 is approximately forty-five degrees. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, if desired, an additional molded projection of desired thicknesses may be integrally formed on each inner surface of the outer pole portions of the base 34 to properly locate or position the rotatable pins 78 in the outer poles. Such molded projections would be configured to contact the longitudinal ends of the rotatable pins 78 opposite to the ends contacted by the molded projections 410 and 416. Thus, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described hereinabove.