MXPA99010724A - Circuit switch mechanism for a girato contact system - Google Patents

Abstract

A rotary contact circuit breaker employs a crank to gather a switching mechanism to the rotating contact pole structure. The use of a crank allows the pole structure and the mechanism to be optimized individually without affecting the performance of the other. In particular, the crank allows a mechanism that is capable of achieving maximum torque delivery to the po

Description

CIRCU ITO SWITCH MECHANISM FOR A SWIVEL CONTACT SYSTEM Field of the Invention The present invention relates to a mechanism for molded case circuit breaker capable of changing a rotating contact structure between on, off and off positions. BACKGROUND OF THE INVENTION The present invention is directed to a molded case circuit breaker having a mechanism for changing a rotary contact system between on, off and off positions. The Patent of the United States of North America Number of Series 5, 281, 776 ('776) discloses a molded case circuit breaker having a lever-type mechanism for switching a rotary contact system. This mechanism uses a lower articulated mechanism that attaches directly to a motor shaft that extends through and rotates the contact system, as shown in Figure 1. A crank attached to the same activation bolt is used to activate another bolt that also extends through the contact system. As the drive shaft passes through the contact system, the optimal positioning of this shaft may not be possible, which may result in geometric constraints on how much force can be transferred from the switching mechanism to the rotor. This generally limits the level of performance that a circuit breaker utilizes the switching mechanism of the United States Patent Serial No. 5,281, 776 can achieve. Therefore, it is desirable to optimize the switching mechanism to transmit a greater amount of force to a rotating contact system. It is also considered desirable in conjunction with the improved switching mechanism to describe an interface between the mechanism and the contact system that allows flexibility in the positioning and design of the mechanism. Brief Description of the Invention In accordance with the present invention there is provided a circuit breaker mechanism comprising a side structure having a cradle attached thereto. An articulated connection consisting of an upper joint having first and second ends is joined to the cradle and a lower joint joined to the second end of the upper joint by means of a spring screw. A crank member attached to the lateral structure is attached to the lower joint. The crank provides the output torque generated by the mechanism. Also in accordance with the present invention, a circuit breaker utilizing the switching mechanism is provided if the present invention has a base, cover and handle operatively connected to a crank. This is the preferred embodiment, a pair of opposite side structures are attached to the base and each provides a quantity of cradle that moves between a disengaged and latching position. An articulated connection consisting of a top joint having first and second ends is attached to said cradle proximate the first end of the upper joint. The second end of the upper joint joins the first end of the lower joint. The lower joint has a second end that joins the crank. The handle is pivotally attached to the opposite side structures and has a first end attached to the lower link and a second end coupled to the activation pin. The activation pin extends through a rotor assembly. The rotor assembly is movable between a closed and open position. Brief Description of the Drawings Other advantages and aspects will be more apparent from the following description of an illustrative embodiment of the invention, provided as a non-restrictive example only and represented in the accompanying drawings, in which: Figure 1 , is a sectional view of a prior art mechanism in the closed position. Figure 2 is a top perspective view of a circuit breaker in accordance with the present invention. Figure 3 is a front plan view of the elements of the present invention as illustrated in Figure 2 in the position C ER RA DA.

Figure 4 is a front plan view of elements of present invention as illustrated in Figure 2 in ABI ERTA position. Figure 5 is a front plan view of elements of present invention as illustrated in Figure 2 in ECTADA DESCON position. Description of Preferred Modality. Referring now to Figure 2, circuit breaker 10 in accordance with present invention is comprised of a base 22 and a cover 24. Housed within base 22 and cover 24 are three poles 14C, 14L, 14R corresponding to each to a respective phase in an electrical circuit. Each pole 14C, 14L, 14R contains a rotary contact assembly 16C, 16L, 16R, respectively capable of carrying and interrupting electric current. A motor shaft 18 connects three poles 14C, 14L, 14R. In addition, center pole 14C is mounted by a mechanism assembly 12. mechanism 12 connects poles 14C, 14L, 14R via motor shaft 18. poles 14C, 14L, 14R are operable to move between three open positions, closed, or disconnected in response to operation of mechanism 12. As seen in Figure 3, each pole 14 is formed of a rotor 60 which houses a contact arm 26 and a pair of movable contacts 28, 28 '. movable contacts 28, 28 'are coupled with pair of stationary contacts 30, 30' when mechanism is in CLOSED position shown. stationary contacts 30, 30 'are attached or welded to a load securing flange 32 and a line holding band 34, respectively. crank 62 connects mechanism 12 to rotor assembly 16C. crank 62 rotates around bolt 61 which is assembled in side structures 13. It should be noted that rotor assemblies 16R, 16L can be identical to rotor assembly 16C. operation of rotor assembly 16C operates substantially same as described in copending U.S. Patent Application Serial No. 09/087, 038 filed May 29, 1998, which is incorporated herein by reference . mechanism 12 consists of a lower link 38 connected to crank 62 by a connector pin 39. opposite end of lower link 38 of crank is connected to an upper link 40 by a spring screw 48. upper link 40 a in turn is connected to cradle 42 by bolt 56 to which a bolt mechanism (not shown) is attached. mechanism spring 50 is connected between spring screw 48 and a bolt 52 on handle 46. mechanism 12 is prevented from having additional rotation in a counter-clockwise direction when bolt 58 attached to upper joint 40 it contacts cradle 42. amount of torque that can be generated by mechanism 12 is determined by amount of force F transferred from mechanism spring 50 through lower link 38 and moment arm. moment arm shown in Figure 3 as perpendicular distance d. perpendicular distance d is length of a line perpendicular to pivot of crank 61 to line of action of force F. Since torsion is product of force F multiplied by distance d, it must be apparent that for a given mechanism, greater distance d, greater torque generated. This distance d and efore torsion will be maximized when distance d coincides with connecting bolt 39. In present invention, bolt 39 only connects lower articulation 38 to crank 62. It should be noted that in art mechanisms above, bolt 39 was also activation bolt that extends through and connects all rotors. components of rotor assembly 16C generally do not allow activation bolt to be placed in this optimum position. For example, as shown in Figure 3, if the bolt 39 is used as the driving shaft to connect all the rotor assemblies, then it would be necessary to pass directly through the contact arm 26. Thus, if a configuration of optimized mechanism, the lower link 38 has to be decoupled from the motor shaft and the rotor assembly 16C. The present invention achieves all this by attaching the lower link 38 to a crank 62 which in turn transmits the force to the motor shaft 18. The motor shaft 18 can then be placed anywhere on the rotor without affecting the amount of torque the mechanism can create. By using the crank 62, the rotor assembly 16C or the mechanism assembly 12 can be optimized without compromising the performance of the other, thus allowing a maximum amount of flexibility in the design of the circuit breaker while keeping the subassemblies optimized. With reference to Figure 4, under a normal switching operation, the handle 46 is rotated counterclockwise to switch the circuit breaker 10 from ON to OFF. As the handle 46 is rotated, the line of action of the spring 50 will move from the right side to the left side of the pivot 56 this movement "over-centers" the mechanism 12 and the force stored in the spring causes the mechanism 12 to open the assemblies of rotor 16C, 16R, 16L. This opening movement separates the movable contacts 28, 28 'from the stationary contacts 30. 30' thus preventing any current flow through the circuit breaker 10. When a circuit breaker disconnection unit detects an abnormal condition (not shown) ), the closing mechanism (not shown) is released allowing the cradle 42 to rotate in a clockwise direction. The disconnecting and closing unit are similar to that of U.S. Patent Serial Number 4, 789, 848 which is incorporated herein by reference. The resulting movement of the cradle 42 causes the rotor assembly 16C via the upper link 40 and the lower link 38 to rotate separating the movable contacts 28, 28 'from the stationary contacts 30, 30'. The separation of the contacts stops the flow of current through the circuit breaker 10. Although a preferred embodiment of this invention has been described, many variations and modifications will now be apparent to those skilled in the art and it is therefore preferred that the present invention is limited not by the specific disclosure of the present but only by the following claims.

Claims (20)

1. CLAIMS 1. A mechanism for a multi-pole circuit breaker comprising: at least one side structure; a cradle joined to said lateral structure, such a cradle is movable between a closed and disconnected position; an articulated connection formed by an upper joint member having first and second ends and which is rotatably joined at said first end to said cradle and a lower joint having first and second ends, said first end of the joint bottom is secured to said second upper link end by a spring screw; a crank member that is rotatably joined to said lateral structure and having first and second ends, said first end of the crank is rotatably connected to said second end of the lower articulation; at least one rotatable contact assembly mounted for rotation proximate said crank.
2. 2. The mechanism of claim 1, further comprising: a handle lever attached for rotation to such a side structure; a spring attached between said articulated connection spring screw and such handle lever.
3. 3. The mechanism of claim 2, wherein said contact assembly further comprises: a rotor movable between an open and closed position and having first and second opposite side faces; a contact arm having first and second ends, said contact arm is mounted for rotation in said rotor; and at least one contact mounted on said contact arm at one of said ends.
4. 4. The mechanism of claim 3 wherein: said crank is attached to said lateral structure by a pivot; said crank is connected to said lower link by a pin, and said first end of the crank is arranged so that a line between the center of said crank pin and the center of said pin is perpendicular to a line of force created by said spring and transmitted through said lower articulation when said rotor is in the closed position.
5. The mechanism of claim 4, wherein: said rotor assembly has a first hole extending through said first and second side faces of the rotor.
6. The mechanism of claim 5, further comprising: a drive shaft extending through said hole of the rotating contact assembly and coupled to said second end of the crank.
7. The mechanism of claim 6, wherein: said at least one side structure consists of first and second parallel side structures, said side structures being positioned on either side of such a rotor assembly; such crank is attached to said first side structure.
8. 8. The mechanism of claim 7, further comprising: a second crank connected to said second lateral structure; a second top joint attached to said cradle; a second lower joint having first and second ends with such first end attached to said upper joint, said second end of the lower joint being attached to said second handle.
9. The mechanism of claim 8 wherein: said second crank consists of first and second ends wherein said first end is joined to the second lower link and said second end of the crank is coupled to said motor shaft.
10. 10. A multi-pole circuit breaker comprising: a base; a first side structure mounted to said base; a cradle joined for rotation to such a lateral structure, said cradle is movable between closed and disconnected positions; an articulated connection formed by an upper articulation member having first and second ends and which is rotatably connected to said first end of said cradle and a lower articulation member having first and second ends, said first end being secured to said second end of the upper joint by means of a spring screw; a crank member that is rotatably joined to one of said lateral structures and having first and second ends, said first end of the crank being rotatably connected to said second end of the lower articulation; a first rotary contact assembly mounted for rotation within said base next to said crank. eleven .
11. The circuit breaker of claim 10, further comprising: a second side structure opposite said first side structure, said second side structure being joined to said first side structure by a bolt; a handle lever attached for rotation to each of said side structures; a spring attached between such a spring screw of the articulated connection and said handle lever.
12. The circuit breaker of claim 1, wherein said contact assembly further comprises: a moving rotor between the open and closed position and having first and second opposite side faces; a contact arm having first and second ends, said contact arm is mounted for rotation to such a rotor; and, at least one contact mounted to said contact arm at one of said ends.
13. The circuit breaker of claim 12, wherein: said handle is attached to said side structure by means of a pivot; said handle is connected to said lower joint by means of a bolt, and said first end of the handle is configured so that a line between the center of said pivot of the handle and the center of said bolt is perpendicular to a line of force created by said spring and transmitted through said lower articulation when said rotor is in the closed position.
14. 14. The circuit breaker of claim 13, wherein: said rotor assembly has a first hole extending through said first and second side faces of the rotor.
15. 15. The circuit breaker of claim 14, further comprising: a drive shaft extending through said hole of the rotating contact assembly and coupled to said second end of the crank.
16. 16. The circuit breaker of claim 15, further comprising: a second rotating contact assembly adjacent and spaced from said first contact assembly within said base, said second rotary contact assembly having a first orifice extending therethrough; said secondary contact assembly is arranged in such a way that such a motor shaft extends through the first hole of the second contact assembly.
17. The circuit breaker of claim 16, further comprising: a third rotational contact assembly adjacent and spaced from said first contact assembly opposite said second contact assembly within said base, said third contact assembly having a first Hole extending through said third contact assembly is arranged such that said motor shaft extends through the first hole of said second contact assembly.
18. 18. The circuit breaker of claim 17, wherein: said first contact assembly further comprises a rotor having first and second opposing side faces, said first hole of the first contact assembly extending through said first and second side faces of the first contact assembly.
19. 19. The circuit breaker of claim 16, wherein: said second contact assembly additionally comprises a rotor having first and second opposed side faces, said first hole of the second contact assembly extending through said first and second ones. side faces of the second contact assembly. The circuit breaker of claim 18, wherein: said third contact assembly further comprises a rotor having first and second opposed side faces, said first hole of said third contact assembly extending through said first and second side faces of the third contact assembly.