CIRCUIT BREAKER

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from Japanese Patent Application No.2011-237327 filed on October 28, 2011, the entire subject matter of which is incorporated herein by reference.

TECHNICAL FIELD

[0002] The present invention relates to a circuit breaker used as a molded-circuit breaker or earth-leakage circuit breaker, etc. Specifically, the present invention relates to a supporting structure of a movable contact terminal.

BACK GROUND

[0003] A circuit breaker not only performs a switching function of opening and closing an electric circuit by operating an operating handle provided in the circuit breaker, but also performs a cutting off (breaking) the electric circuit in order to prevent a burn-out damage of an electric wire or a loaded device caused by an over current. For example, the cutting off of the electric circuit is defined as "rated short-circuit breaking capacity" in the Japanese Industrial Standard (JIS) C8201-2-1. It is known that some manufacturer provides various products so that an appropriate circuit breaker having an appropriate value can be selected based on a circumstance of the electric circuit such as a distance from a transformer, a thickness of a wire, and the like.

[0004] However, when the electric current is cut off, an arc occurs between a pair of contacts, that is, a movable contact and a fixed contact. In order to extinguish the arc quickly, it is desirable to increase an arc voltage for maintaining the arc itself. Therefore, when including two sets of a pair of contacts (so called, a single-pole double-break circuit), the arc voltage becomes double, and it is suitable for a product with a high breaking capacity. It is known that an example of the single-pole double-break circuit includes a power source side fixed contact terminal and a load side fixed contact terminal including, respectively, a fixed contact which configures a pair with respective movable contacts, are arranged at a point symmetric position with respect to a rotation center of a rotating movable contact terminal provided with two movable contacts at both ends thereof (see, for example, JP-A-H06-52777 (lines 14 to 34 on the right column of page 4) and JP-A-2005-310780 (lines 16 to 29 of page 8))

[0005] With respect to the "point symmetric position", the movable contact terminal is provided at the center consistently, because it is essential to realize the single-pole double-break. If the center of the movable contact terminal is dislocated, the balance of contact pressure between the power source side and the load side is lost, and then increasing of a temperature or a faulty breaking may be caused. With respect to above matter, both of JP-A-H06-52777 and JP-A-2005-310780 is described based on an electromagnetic repulsive force of the movable contact terminal. However, for example, it is estimated that a spindle 39 is received in a notch 40 consistently in JP-A-H06-52777, and that a roller 151 is moved from an engagement in a maintaining clearance 116 at the time of electromagnetic repulsion to a cam surface 113 when the circuit breaker is in an OFF state in JP-A-2005-310780. Accordingly, it is considered that the center dislocation of the movable contact terminal does not occur specifically when the circuit breaker is in an OFF state. As a result, the losing of the contact-pressure balance as described above may not occur even though the circuit breaker is in an ON state by operating the operating handle.

SUMMARY

[0006] On the other hand, in the JP-A-H06-52777, in case of electromagnetic repulsion, a movable contact terminal (contact bridge 13) interferes with a rod 42 provided in a rotating driving rod 20 in a direction where the movable contact terminal opens. Therefore, it is difficult that a pole opening amount and an arc voltage between the contacts increase. Although this aspect has been improved in JP-A-2005-310780, since the load of a spring 141 is applied to a movable contact through a roller, there is a problem that an important spring force is not efficiently used and the force thereof is small when the circuit breaker is in an ON state. Further, since the roller contacts the cam face, a force or an over travel (OT) amount of the movable contact terminal is easy to vary when a precision level of the cam surface is deteriorated. In addition, in both JP-A-H06-52777 and JP-A-2005-310780, costs are increased according to the additional parts such as the shaft, the rod, a slide pin 131 or the roller.

[0007] The present invention provides a circuit breaker of a single-pole double-break that may not increase a cost or an error and may maintain the contact-pressure balance while directly applying a spring force to a movable contact terminal.

[0008] In view of the above, a circuit breaker of the present invention, comprises: a movable contact terminal, which is rotatable and includes movable contacts in respective ends; a power source side fixed contact terminal and a load side fixed contact terminal, which include fixed contacts that respectively contacts with the movable contacts of the movable contact terminal, and which are configured to generate an electromagnetic repulsive force toward an opening position of the movable contact terminal by flowing current to the movable contacts when short-circuit current occurs; a rotor, which is configured to transfer rotating force to the movable contact terminal; and a contact pressure spring, which is provided to the rotor, and which is configured to apply the contact pressure to the movable contact terminal to press the movable contacts toward the fixed contacts in a closing position of the circuit breaker, wherein the contact pressure spring is configured as a single set of pull springs, in which ends of the one side of two coils are connected to each other at a connecting portion and ends of the other side of the two coils are provided with a hook respectively, wherein the connecting portion of the single set of pull springs is provided to contact with an opposite face opposite to a face, on which the movable contacts of the movable contact terminal are formed, and respective coil portions of the pull springs is provided on respective sides of an axial direction of a rotating shaft of the movable contact terminal across the opposite face, wherein the hook is directly latched to a rib formed on the rotor so that the contact pressure is applied, and wherein at least one pair of the single set of pull springs are provided symmetrically with respect to a rotating shaft center of the movable contact terminal, and wherein the movable contact terminal is fitted with the rotor when the rotor is rotated by an opening-closing mechanism portion of the circuit breaker.

[0009] As described above, the present invention provides a highly reliable circuit breaker having a good cost performance and a high breaking capacity by the single-pole double-break.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed descriptions considered with the reference to the accompanying drawings, wherein:

[0011] FIG. 1 illustrates a perspective view of a single-pole double-break circuit breaker with the cover being removed, according to a first embodiment of the present invention;

FIG. 2 illustrates a sectional side view of the circuit breaker shown in FIG. 1 in an ON state;

FIG. 3 illustrates a sectional side view of the circuit breaker shown in FIG. 1 in an OFF state;

FIG. 4 illustrates a side view illustrating an opening-closing mechanism portion and a double-break unit case in the ON state of FIG. 2;

FIG. 5 illustrates a side view illustrating an opening-closing mechanism portion and a double-break unit case in the OFF state of FIG. 3;

FIG. 6 illustrates an enlarged view of portion A of FIGS. 2 and 3, and FIG. 6A shows an ON state and FIG. 6B shows an OFF state;

FIG. 7 illustrates a view illustrating, as a comparative example, a rotating trajectory of a rotor when a movable contact terminal and a rotor are not fitted with each other;

FIG. 8 illustrates a view illustrating a force of a pull spring in the ON state, FIG. 8A shows a case where the fitting occurs in the present invention, and FIG. 8B shows a case where the fitting does not occur in the comparative example;

FIG. 9 illustrates a view, which is corresponding to FIG. 6, according to a second embodiment of the present invention, and FIG. 9A shows an ON state and FIG. 9B shows an OFF state;

FIG. 10 illustrates a view, which is corresponding to FIG. 6, according to a third embodiment of the present invention, and FIG. 10A shows an ON state and FIG. 10B shows an OFF state; and

FIG. 11 illustrates a plan view of FIG. 10B.

DETAILED DESCRIPTION

[First Embodiment]

[0012] FIGS. 1 to 6 illustrate a single-pole double-break circuit breaker according to a first embodiment of the present invention. Specifically, FIG. 1 is a perspective view where the cover of the circuit breaker is removed, FIG. 2 is a sectional side view of the circuit breaker in an ON state, and FIG. 3 is a sectional side view of the circuit breaker in an OFF state. FIGS. 4 and 5 are side views showing an opening-closing mechanism portion and a double-break unit case of a center pole of FIG. 1. Similar to FIGS. 2 and 3 or FIGS. 4 and 5 show the circuit breaker in an ON state and an OFF state, respectively. FIG. 6 is an enlarged view of a portion A of FIGS. 2 and 3, and , similarly to FIGS. 2 and 3.FIG. 6A shows the circuit breaker in an ON state and FIG. 6B shows the circuit breaker in an OFF state.

[0013] As a comparative example, FIG. 7 illustrates a rotating trajectory of a rotor in which "a fitting of a movable contact terminal and a rotor", which is one of major configuration of the present invention, is not existed. As a comparative example, FIG. 8 illustrates a force of a pull spring depending on whether there exists the "fitting". [0014] In FIG. 1, an insulative case of the single-pole double-break circuit breaker 101 for three poles includes a cover 1 (see FIG. 2) and a base 2. Here, an opening-closing mechanism portion 51 provided with an operating handle 3, double-break unit cases 52 as many as the poles (in this case, three), and an over current tripping device 53 are disposed on the base 2. The operating handle 3 protrudes from a window hole la (see FIG. 2) for a handle of the cover 1 is to be operable into an ON or OFF direction. According to position relationship between the double-break unit case 52 and the over current tripping device 53, a reference numeral "4" indicates a power source side terminal, and a reference numeral "5" indicates a load side terminal, respectively.

[0015] As shown in FIG. 2, the double-break unit case 52 includes a power-source side fixed contact terminal 6 that is extended from the power source side terminal 4 and includes a fixed contact 7 in one end thereof, and a load side fixed contact terminal 12 that is connected to the load side terminal 5 through the over current tripping device 53 and includes a fixed contact 11 in one end thereof. The double-break unit case 52 also includes: a movable contact terminal 9 that includes movable contacts 8 and 10 contacted with or separated from the fixed contacts 7 and 11 in both ends thereof and is supported by a rotor which is a resin molded product, etc; and arc extinguishing devices 14 and 15 that cut out an arc due to separation between the fixed contact 7 and the movable contact 8, and between the movable contact 10 and the fixed contact 11. The rotor 13 rotating within the double-break unit case 52 by a rotating shaft 13a is provided with contact pressure springs 16 and 17 that generate the contact pressure between the fixed contact 7 and the movable contact 8, and between the movable contact 10 and the fixed contact 11, respectively. The rotor 13 is connected through a connecting shaft 18 to rotate the movable contact terminal 9 of each pole according to an operation of the opening-closing mechanism portion 51. That is, the sectional side view of FIG. 2 illustrates a center pole showing a combination with the opening-closing mechanism portion 51.

[0016] Next, a configuration of the opening-closing mechanism portion 51 will be described. As shown in FIG. 1, the opening-closing mechanism portion 51 is configured as a unit by an approximately U-shaped handle arm 20 pivotally supported to a frame 19, which is formed by a pair of frame plates 19A and 19B facing each other, to be freely rotatable, and the operating handle 3 is fixed to the handle arm 20. As shown in FIG. 2, the inside of the opening-closing mechanism portion 51 includes a lever 22 engaged with a latch 21 of the overcurrent tripping device 53 and is pivotally supported to the frame 19 by the rotating shaft 22a, an upper link 23 that is pivotally supported to the lever 22, a lower link 24 that is combined with the upper link 23 through a spring pin 25 to configure a toggle link, and a main spring 26, of which a driven side portion 26a is extended to the spring pin 25 and a driving side portion 26b is extended to the handle arm 20, respectively.

[0017] Hereinafter, a combination and an operation of the opening-closing mechanism portion 51 and the double-break unit case 52 in the circuit breaker 101 will be described with reference to FIGS. 2 through 5. Three double-break unit cases 52 are connected by two pin shafts 27 and fixed to a predetermined position of the base 2 (see FIG. 1). When the connection, the frame plate 19A is disposed between the double-break unit case 52 of a right pole (front in the figure of FIG. 1) and the double-break unit case 52 of a center pole, the frame plate 19B is disposed between the double-break unit case 52 of a left pole (backward in the figure of FIG.1) and the double-break unit case 52 of the center pole, and the pin shaft 27 is passing through plates, so that and the opening-closing mechanism portion 51 is also fixed. In this connection, the connecting shaft 18 that is extended from the rotor 13 of the double-break unit case 52 of the center pole is inserted into the rotor 13 of each of the left pole and the right pole.

[0018] Here, a roller 28 is rotatably provided around the outer circumference of the connecting shaft 18 that is extended from the double-break unit case 52 of the center pole. Meanwhile, a link rotor 30 that rotates using a pin 29 as a rotation center is formed on the double-break unit case 52 of the center pole. The link rotor 30 includes an elongated hole 30a and the roller 28 is engaged with an inner wall of the elongated hole 30a. The roller 28 is enabled to be movable into a lengthwise direction of the elongated hole 30a along the inner wall. The link rotor 30 is rotatably combined with the lower link 24 through the pin 31. Accordingly, the movement of the lower link 24 is transferred to the rotor 13 of each pole through the link rotor 30, the roller 28, and the connecting shaft 18, thereby rotating the movable contact terminal 9 of each pole according to an operation of the opening-closing mechanism portion 51, as described above. The lower link 24, the link rotor 30, and the like of a front side are shown in FIG. 4. However, they are provided also in a backward side, in other words, they are provided at the double-break unit case 52 of the left pole. Therefore, the upper link 23 is provided in an approximately U shape having a connecting portion 23a.

[0019] In an OFF state, when rotating the operating handle 3 clockwise in the figure, the driving side portion 26b rotate with respect to the rotating shaft 20a of the handle arm 20 (see FIG. 1). Due to the rotation, the load direction of the main spring 26 is changed, the spring pin 25 is also moved to operate the lower link 24, and the link rotor 30 is pressed downward. Due to the pressure, the roller 28 rotate and moves within the elongated hole 30a, so that the rotor 13 is rotated clockwise by the connecting shaft 18 within the roller 28. As a result, the fixed contact 7 and the movable contact 8 are contacted with each other, and the movable contact 10 and the fixed contact 11 are contacted with each other. That is, a state is shifted from the OFF state to the ON state.

[0020] In the ON state, when rotating the operating handle 3 counter-clockwise in the figure, contrary to the above description, the lower link 24 moves by moving the spring pin 25 to the left direction, so that the link rotor 30 is pulled upward. Due to the pulling upward, the roller 28 rotates and moves within the elongated hole 30a, so that the rotor 13 rotates counter-clockwise with respect to the connecting shaft 18 within the roller 28. The fixed contact 7 and the movable contact 8 are separated from each other, and the movable contact 10 and the fixed contact 11 are separated from each other. That is, a state is shifted from the ON state to the OFF state.

[0021] In the ON state, when the overcurrent tripping device 53 is operated based on detecting overcurrent and the like, the latch 21 rotates by a movement of a trip bar 32 (see FIG. 1) and the engagement between the latch 21 and the lever 22 is released. Here, as is well known, the lever 22 is consistently pressed to a clockwise direction in the figure by the main spring 26 and thus starts to rotate clockwise around the rotating shaft 22a. Due to the rotation, the driving side portion 26b moves relatively with respect to the spring pin 25. Finally, the upward force starts to press the spring pin 25, and then the lower link 24 is moved. After the movement of the lower link 24, a state is shifted similarly to above-described shift from ON to OFF and is to be in a trip state (not shown).

[0022] Next, it will be described that the fitting between the movable contact terminal 9 and the rotor 13, which is one of the major configurations of the present invention, in the ON state and the OFF state with reference to FIG. 6. Initially, in the ON state of FIG. 6A, a gap B occurs between the movable contact terminal 9 and the rotor 13. This is because that clockwise rotation of the movable contact terminal 9 is blocked by the fixed contacts 7 and 11, while the movable contact terminal 9 is pressed into the clockwise direction in the figure by the contact pressure springs 16 and 17. Therefore, the gap B is generated due to the contact pressure of the contact pressure springs 16 and 17. The contact pressure spring 16 is configured as a single set of pull springs, in which ends of one sides of two coils 16a and 16b (see FIG. 11) configures the contact pressure spring, are connected each other by a U-shaped connecting portion 16c, and hooks 16d and 16e are formed on other sides of the coils 16a and 16b, respectively. The contact pressure spring 16 is arranged to engage the connecting portion 16c with an opposite face 9a opposite to the movable contact 8 of the movable contact terminal 9 and to directly latch the hooks 16d and 16e to a rib 13b formed on the rotor 13 so that the coils 16a and 16b are arranged at both sides in the axial direction of the rotating shaft of the movable contact terminal 9. The contact pressure spring 17 is configured similarly to the contact pressure spring 16, and thus a single set of contact pressure springs 16 and 17 is configured.

[0023] In the present invention, a convex portion 13c is formed on the rotor 13 and a concave portion 9c is formed on the movable contact terminal 9 at a portion of the gap B. Accordingly, in the OFF state of FIG. 6B, the convex portion 13c and the concave portion 9c are fitted with each other so that a position of the movable contact terminal 9 can be normalized without causing a dislocation in left and right directions within the rotor 13. As a result, as shown in FIG. 6A, a state is shifted to the ON state, in which left and right can be balanced, and thus it is possible to prevent a temperature increase according to the stabilization of the contact pressure, and it is possible to stabilize the breaking performance.

[0024] With comparing FIG. 6 with FIG. 7, in which the fitting configuration is not included, the effect according to the configuration of FIG. 6 may be clearly understood. Since the movable contact terminal 9 is initially in floating support, when considering an error of components, an attachment precision, and the like, imbalance of left and right sides (in this example, the movable contact terminal is unbalanced to right in the figure, that is, the power source side) easily occurs as shown in (4) of FIG. 7. When a shift to the ON state is performed in the above state, the movable contact terminal 9 is also positioned in the state dislocated toward the power source side as shown in state (1) of FIG. 7. Therefore, the contact pressure spring 16 causes a state, in which the contact pressure spring 16 is more extended than the contact pressure spring 17, that is, a state in which the gaps B do not match, and a contact-pressure difference between the power source side and the load side occurs. Therefore, the temperature increase may be occurred due to an increase in contact resistance.

[0025] When an operation of shifting to an OFF state, since the aforementioned gap B does not match, load side parts contact each other as shown in state (2), and then, when the power source side contacts as shown in state (3) of FIG. 7, the movable contact 10 and the fixed contact 11 are separated from each other. Accordingly, without improving the imbalance between left and right sides, the state becomes state (4) of FIG. 7. Subsequently, state (3), state (2) and state (1) in this order, and then, state (1), state (2), state (3), and state (4) in this order are repeated.

[0026] A mechanism causing above phenomenon will be described in detail with reference to FIG. 8. In FIG. 8 (FIG. 8 corresponds to state (2) of FIG. 7) in which the OFF operation starts, that is the rotor 13 starts to rotate counter-clockwise according to an operation of the opening-closing mechanism portion 51, in both FIGS. 8A and 8B, a force F' according to a distance from a spring force F resulting from the contact pressure springs 16 and 17 occurs in a fitted portion. According to the force F', a slide direction component Fs resulting from the shape of a concave/convex portion is occurred in FIG. 8A, in which the concave/convex portion is formed. Due to the occurrence of the slide direction component Fs, as described above, the concave/convex portion is certainly fitted and a center position of the movable contact terminal 9 within the rotor 13 is continuously corrected, so that left and right may be balanced. On the other hand, in FIG. 8B, in which the concave/convex portion is not formed, components Fs occurs only slightly in a nearly vertical direction with respect to force F', and thus the correction as in FIG. 8A cannot be expected. Therefore, as described above, an opening-closing operation may be repeated without improving the imbalance between the left and right sides.

[0027] Even in the rotation of only the movable contact terminal 9 by an electromagnetic repulsive force as disclosed in JP-A-H06-52777 or JP-A-2005-310780, the fitting is performed only the concave portion 9c and the convex portion 13c in the present invention, in the rotor 13 rotating subsequently. Therefore, it is unlikely that the balance of the contact pressure is lost due to the abrasion in the opening and closing durability, for example. As described above, since the spring force of the contact pressure springs 16 and 17 is efficiently used as the contact pressure and the separation distance (not shown) in the electromagnetic repulsion of the movable contact terminal 9 increases by directly latching the hook portions 16d, 16e, 17d, and 17d to the rib 13b, it is possible to suppress a cost of the circuit breaker having the high breaking capacity and to further increase the reliability.

[0028]

[Second Embodiment]

FIG. 9 is a view, which is corresponding to FIG. 6, according to a second embodiment of the present invention. As described above, the concave portion 9c is formed on the movable contact terminal 9, and the convex portion 13c is formed on the rotor 13 in the first embodiment. However, a configuration contrary to that of FIG. 6 may be implemented. That is, a convex portion 9d may be formed on the movable contact terminal 9, and a concave portion 13d may formed on the rotor 13 as shown in FIG. 9. Accordingly, the same effect is achieved.

[0029]

[Third Embodiment]
FIG. 10 is a view, which is corresponding to FIG. 6, a third embodiment of the present invention, and FIG. 11 is a plan view of FIG. 10B. Although detailed description is not made in the first embodiment, an arc insulating member 33, which suppresses scattering of an arc toward the rotor 13 or discharges a gas for inducing the arc to the power source side when breaking the overcurrent, is fixed around the movable contacts 8 and 10 of the movable contact terminal 9, as shown even in FIG. 6. Meanwhile, a frame of the circuit breaker is represented by using an Ampere Frame (AF) for indicating the fault withstand rating of the circuit breaker. Generally, the largest rated current is represented by using the AF and various types of rated current products are provided within the AF (for example, in case of 250AF, 125A, 150A, 175A, 200A, 225A, and 250A are provided). Here, in order to achieve the heat generation amount management effect or the current-limiting effect according to the rated current, the plate thickness of the movable contact terminal 9 may be changed.

[0030] Accordingly, in the third embodiment, as shown in FIG. 10 or FIG. 11, a arc insulating member 34 is provided to extend within the rotor 13 according to changes of a plate thickness of the movable contact terminal 9. Therefore, the added width dimension, where the width of the arc insulating member 34 and the width of the movable contact terminal 9 are added, is set to be slightly narrower than the dimension of a clearance 13e of the rotor 13 in each rated current, so that it is possible to promote a part standardization of the rotor 13 and to suppress a dislocation of upward and downward directions in the figure of FIG. 11. Further, it is possible to suppress the scattering of the arc into the rotor 13, and thus the stabilization of the breaking performance can be further promoted. Polyethylene terephthalate, nylon, nylon, and etc., which are described as an insulating material composition or an insulating material molded product for arc extinguishing in Japanese Patent JP-B-3359422, may be suitable as a material for the arc insulating member 33 (34).

WE CLAIM:

1. A circuit breaker, comprising:

a movable contact terminal, which is rotatable and includes movable contacts in respective ends;

a power source side fixed contact terminal and a load side fixed contact terminal, which include fixed contacts that respectively contacts with the movable contacts of the movable contact terminal, and which are configured to generate an electromagnetic repulsive force toward an opening position of the movable contact terminal by flowing current to the movable contacts when short-circuit current occurs;

a rotor, which is configured to transfer rotating force to the movable contact terminal; and

a contact pressure spring, which is provided to the rotor, and which is configured to apply the contact pressure to the movable contact terminal to press the movable contacts toward the fixed contacts in a closing position of the circuit breaker,

wherein the contact pressure spring is configured as a single set of pull springs, in which ends of the one side of two coils are connected to each other at a connecting portion and ends of the other side of the two coils are provided with a hook respectively,

wherein the connecting portion of the single set of pull springs is provided to contact with an opposite face opposite to a face, on which the movable contacts of the movable contact terminal are formed, and respective coil portions of the pull springs is provided on respective sides of an axial direction of a rotating shaft of the movable contact terminal across the opposite face,

wherein the hook is directly latched to a rib formed on the rotor so that the contact pressure is applied, and

wherein at least one pair of the single set of pull springs are provided symmetrically with respect to a rotating shaft center of the movable contact terminal, and

wherein the movable contact terminal is fitted with the rotor when the rotor is rotated by an opening-closing mechanism portion of the circuit breaker.

2. The circuit breaker of claim 1,

wherein the fitting is performed by a convex portion formed on the rotor and a concave portion formed on the movable contact terminal.

3. The circuit breaker of claim 2,

wherein an arc insulating member is provided on the movable contact terminal, and a width of the movable contact terminal including the arc insulating member in the axial direction of the rotating shaft is slightly narrower than a width of a portion of the rotor, at which the movable contact terminal is fitted to the rotor.