JP2004031275A - Double-pole ground fault interrupter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the operational reliability and life of a double-pole ground fault interrupter. <P>SOLUTION: A bimetallic strip 6 is arranged on that side of a moving contact 5 which has a power terminal 3 opposite to a leakage detection mechanism 12. The leakage detection mechanism 12 is thus far from the bimetallic strip 6 to retard an effect of heat generation by the bimetallic strip 6 on electronic parts on a printed board 24. A trip coil 25 is arranged in the lateral middle of a switch mechanism 13, and a load from the trip coil 25 at tripping acts on the middle of a crossbar 17 to prevent damage to the crossbar 17 from a load bias. A plunger 29 of the trip coil 25 turns the crossbar 17 directly to stabilize tripping. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-pole earth leakage circuit breaker with an overload detection function used for OA equipment such as copiers and printers and general household electrical equipment.
[0002]
[Prior art]
7 to 11 show a conventional structure of this type of earth leakage breaker, FIG. 7 is a longitudinal sectional view of the earth leakage breaker, FIG. 8 is a plan view of the earth leakage breaker of FIG. 7 with a cover removed, 9A is a plan view showing a connection state between a bimetal and a load terminal in the earth leakage breaker shown in FIG. 7, FIG. 9B is a side view thereof, and FIG. 10 is a diagram showing an opening / closing mechanism of the earth leakage breaker shown in FIG. FIG. 11 (A) is a front view of a tripping coil in the earth leakage breaker of FIG. 7, and FIG. 11 (B) is a longitudinal sectional view thereof. First, in FIG. 7 and FIG. 8, a right and left two-pole conducting path is formed in parallel in a molded case composed of a case 1 and a cover 2, and each of the conducting paths is a power terminal 3 and a fixed contact from the right end of the drawing. 4, a movable contact 5, a bimetal 6, a lead wire 7, and a load terminal 8. The power terminal 3 and the fixed contact 4 are integrally formed, and the fixed contact 4 has a fixed contact 9. The movable contact 5 having a movable contact 10 at its tip is made of a leaf spring, and the end welded to the bimetal 6 is fastened to the case 1 with a screw 11. As shown in FIG. 9, the lead wire 7 penetrates the electric leakage detection mechanism 12, and both ends are welded to the bimetal 6 and the load terminal 8, respectively.
[0003]
In FIG. 10, the opening / closing mechanism 13 has a U-shaped frame 14 with side plates rising up to the left and right. An opening / closing handle 15 is supported on the upper part of the frame 14 by a pin 16 so as to be rotatable. A crossbar 17 is rotatably connected to the lower end of FIG. 10 (left side in FIG. 10), and is urged clockwise by a torsion spring 18 so as to be maintained in an upright posture. One end of a U-shaped link 19 is connected to the opening / closing handle 15, a claw 20 having an upper plate is connected to the other end, and the other end is slid into an arc-shaped long hole 14 a of the frame 14. Guided as possible. As shown in FIGS. 7 and 8, the opening / closing mechanism 13 is located at substantially the center of the front and rear of the case 1 and is fixed to the left and right centers by screws. It faces the adjusting screw 21 at the upper end.
[0004]
The opening / closing mechanism shown in FIG. 10 is in the OFF state. When the opening / closing handle 15 is rotated rightward from this state, the claw 20 is pushed down via the link 19. At this time, the left end of the claw 20 is locked by the ratchet portion 17a of the cross bar 17, and thus the claw 20 rotates clockwise. On the other hand, in FIG. 7, an operating plate 22 made of an insulator, which is slidably guided up and down in the case 1, is interposed between the claw 20 and the movable contact 5. Then, when the claw 20 rotates clockwise, the movable contact 5 is pushed down via the operation plate 22 and is turned ON as shown in FIG. At this time, when the opening / closing handle 15 rotates clockwise, the spring force from the movable contact 5 acts counterclockwise on the opening / closing handle 15 via the operating plate 22, the claw 20 and the link 19. When it falls to the ON position indicated by the broken line in FIG. 10, the action of this spring force is reversed in the clockwise direction, and the opening / closing handle 15 is held in the ON state.
[0005]
As shown in FIG. 7, the leakage detection mechanism 12 amplifies the zero-phase current transformer 23 that penetrates the lead wire 7 and its secondary output, and a leakage occurs when this secondary output exceeds a certain value. And an electronic circuit for outputting a trip signal when the electronic circuit is judged to be mounted on the printed circuit board 24. The tripping signal is output to the tripping coil 25. As shown in FIGS. 7 and 8, the tripping coil 25 is arranged so as to be offset to one of the left and right sides of the opening / closing mechanism 13. Here, as shown in FIG. 11, the trip coil 25 includes a bobbin 26, a winding 27, a pole piece 28, a plunger 29, a return spring 30, and the like. The pole piece 28 is fixed to a support plate 31 also serving as a yoke. I have. An actuator 32 is rotatably supported on the support plate 31 by a pin 33, and the plunger 29 has a head engaged with the actuator 32. The trip coil 25 is fixed to the case 1 via the support plate 31 with screws. 7 and 8, a protrusion 17 b extending toward the trip coil 25 is formed on one of the left and right sides of the cross bar 17, and the protrusion 17 b faces the upper end of the actuator 32.
[0006]
In the ON state of FIG. 7, when the current flowing through the current path becomes an overload state, the bimetal 6 curved leftward in FIG. 7 rotates the crossbar 17 counterclockwise via the adjustment screw 21. Then, the engagement of the claw 20 is released (see FIG. 10), and the movable contact 5 is released from the pressing-down force and is turned off by its own spring force (trip operation). Further, when a current imbalance occurs in the left and right current paths due to the occurrence of the leakage, a leakage signal is applied from the leakage detection mechanism 12 to the trip coil 25, and the plunger 29 is attracted. Thus, the actuator 32 rotates counterclockwise in FIG. 11B, and the actuator 32 rotates the crossbar 17 counterclockwise via the protrusion 17b. This also causes a trip as described above.
[0007]
[Problems to be solved by the invention]
The above-mentioned conventional earth leakage breaker has the following problems.
{Circle around (1)} The bimetal 6 is disposed on the same load side as the leakage detection mechanism 12 with the movable contact 10 as a boundary. Therefore, it is necessary to minimize the heat generation of the bimetal 6 so that the bimetal 6 and the electronic circuit of the electric leakage detection mechanism 12 are close to each other, and the heat of the bimetal 6 does not cause a failure of the electronic component. For this reason, in the conventional configuration, it is necessary to use an expensive bimetal 6 that is greatly deformed at a low temperature, or to bend the bimetal 6 as shown in FIG. As a result, material costs and processing costs increase. The leakage detection mechanism 12 must be disposed on the load side with the movable contact 10 as a boundary since it is necessary to disconnect the leakage detection mechanism 12 from the power supply after the trip.
{Circle around (2)} The trip coil 25 is biased to the left or right in the case 1 due to space restrictions, and is disposed on the side of the opening / closing mechanism 13. Therefore, a biased load is applied to the crossbar 17 during the trip operation, and the tripping characteristics may become unstable or the crossbar 17 may be damaged.
{Circle around (3)} Since the support plate 31 for holding the trip coil 25 is provided independently, the layout in the narrow case 1 has many restrictions and the number of parts increases.
{Circle around (4)} The bimetal 6 and the terminal 8 are connected via the lead wire 7. For this reason, the amount of heat radiation of the lead wire portion changes depending on the routing of the lead wire 7 and the degree of contact with other components, and as a result, the temperature (deformation amount) of the bimetal 6 connected to the lead wire 7 is not constant and operates. Characteristics are not stable.
(5) If the bimetal 6 is deformed more than necessary by a large current such as an inrush current or a short-circuit current, the bimetal 6 may interfere with other parts and be permanently deformed, or the heat may cause other parts to melt. Occurs.
[0008]
SUMMARY OF THE INVENTION It is an object of the present invention to improve the mutual relationship between components to stabilize operation characteristics and reduce costs.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a movable contact provided with a movable contact on an energizing path from a power supply terminal to a load terminal. The movable contact is opened and closed by operating an opening and closing mechanism. Bipolar earth leakage that causes the opening and closing mechanism to be tripped by the bending of the bimetal forming a part of the current path when current is generated, and by exciting the tripping coil by the leak detection mechanism when leakage occurs, and causing the movable contact to separate. In the circuit breaker, the bimetal is arranged on the power supply terminal side opposite to the leakage detection mechanism with the movable contact as a boundary (claim 1). As a result, the leakage detection mechanism is far from the bimetal, and the electronic component is less susceptible to the heat generated by the bimetal.
[0010]
In claim 1, it is preferable that the trip coil is disposed at the center of the opening and closing mechanism in the left and right directions (claim 2). As a result, the load from the trip coil acts on the center of the crossbar during the trip operation, and the problem due to the bias of the load is eliminated. In this case, if the crossbar of the opening / closing mechanism is directly rotated by the plunger of the trip coil, the operational reliability is further improved (claim 3).
[0011]
In claim 3, the trip coil is preferably supported by a frame of the opening / closing mechanism (claim 4). By using the frame of the opening and closing mechanism for tripping and supporting the coil, the number of components is reduced and the installation space for the tripping coil is also reduced. In this case, it is preferable that the frame is made of a magnetic material, and the yoke of the trip coil is formed integrally with the frame (claim 5), thereby reducing the number of parts.
[0012]
In claim 1, the bimetal and the power supply terminal may be connected via a flexible conductive plate curved in a U-shape (claim 6). Thereby, the heat radiation around the bimetal is constant, and the operation characteristics are stabilized. In this case, it is preferable that the bimetal hits the conductive plate as it bends, and the conductive plate short-circuits a part of the current path of the bimetal. As a result, when the bimetal is bent to some extent, a portion of the current path is short-circuited by the conductive plate to reduce heat generation, thereby preventing interference with other components due to excessive deformation.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is a longitudinal sectional view of an earth leakage breaker, FIG. 2 is a plan view of a state in which a cover thereof is removed, FIG. 3 is a longitudinal sectional view of a main part of an opening / closing mechanism in FIG. 1, and FIG. FIG. 5 is a side view of a bimetal portion in FIG. 1, and FIG. 6 is a side view showing another embodiment of the bimetal portion. Note that the same reference numerals are used for the portions corresponding to the conventional example. 1 and 2, the power supply terminal 3 and the fixed contact 4 are first separated from each other, and a strip-shaped bimetal 6 is connected to an end of the fixed contact 4 on the power supply terminal side by a rivet 34. In addition, the bimetal 6 and the power supply terminal 3 are connected via a flexible conductive plate 35. The conductive plate 35 is made of, for example, a copper thin plate, is bent in a U-shape as shown, and both ends are welded to the power terminal 3 and the bimetal 6.
[0014]
The upper end of the bimetal 6 is connected to the crossbar 17 via an adjustment screw 21, and the crossbar 17 has a Y-shaped front shape. That is, in FIGS. 1 to 4, and particularly in FIG. 4, the crossbar 17 made of a resin molded product has a pair of left and right arms 17 d standing in a Y-shape from both sides of the upper part of the column 17 c, and the left and right arms 17 d are They are connected to each other by a U-shaped frame portion 17e extending toward the opening / closing mechanism 13. The support 17c is provided with a ratchet 17a (FIG. 3). The crossbar 17 is rotatably connected to the frame 14 of the opening / closing mechanism 13 via a pin 36, and is urged in the counterclockwise direction in FIG. 3 by a compression spring 37 inserted between the crossbar 17 and the frame 14. The adjustment screw 21 of the bimetal 6 is screwed into the arm 17d of the crossbar 17.
[0015]
Next, the trip coil 25 is supported by the frame 14 of the opening / closing mechanism 13. That is, in FIGS. 3 and 4, the frame 14 having a U-shaped cross section having left and right side plates is made of a magnetic material (steel plate). The coil holding leg 14a is formed in an L-shape by bending. Therefore, the trip coil 25 is fitted into the coil holding leg 14 a via the concave portion of the bobbin 26 and is supported by the frame 14. The frame 14 made of a magnetic material also serves as a yoke for the trip coil 25. In this case, the conventional pole piece 28 (see FIG. 11) is omitted, and when the trip coil 25 is excited, the plunger 29 is attracted to the coil holding leg 14a. The trip coil 25 supported by the frame 14 is located at the center inside the left and right arm portions 17d in the space above the column 17c of the crossbar 17. Here, a notch 17f is provided from the upper surface in the left and right center portions of the frame portion 17e of the crossbar 17, and the plunger 29 of the trip coil 25 has its head engaged with the notch 17f.
[0016]
1 to 4, the opening / closing handle 15 is rotatably supported on the frame 14 of the opening / closing mechanism 13 via a pin 16 and a latch 38 (FIG. 3) via a pin 39. The opening / closing handle 15 has arms 15a extending downward on both left and right sides, and the upper end of the movable contact 5 (FIG. 1) is rotatably supported by the arms 15a. A shaft 38a projecting right and left in a T-shape is integrally provided at the upper end of the latch 38, and an opening / closing spring 40 composed of a tension spring is hung between the shaft 38a and the movable contact 5. In the ON state of FIG. 1, the latch 38 receives a rotational force counterclockwise about the pin 39 (FIG. 3) as a fulcrum due to the restoring force of the opening / closing spring 40. 17a, and is kept in the illustrated position.
[0017]
The arm 15a of the opening / closing handle 15 and the movable contact 5 constitute a toggle link. In FIG. 1, the movable contact 5 receives a rotational force in the counterclockwise direction with the upper end serving as a fulcrum due to the restoring force of the opening / closing spring 40, is pressed by the fixed contact 4, and is kept in the ON state in the figure. When the opening / closing handle 15 is rotated leftward from this state, the dead point of the toggle link is exceeded, the action of the opening / closing spring 40 on the movable contact 5 is reversed, and the movable contact 5 is separated from the fixed contact 4. (OFF operation).
[0018]
On the other hand, when an overload current flows through the current path, the bimetal 6 that curves rightward in FIG. 1 rotates the crossbar 17 clockwise through the adjustment screw 21. As a result, the latch 38 is unlocked, and rotates counterclockwise about the pin 39 as a fulcrum. As a result, the dead center of the toggle link is exceeded, and the movable contact 5 is separated (trip operation). Also, when a large current such as a short-circuit current flows through the current path, the plunger 29 is instantaneously sucked, and the crossbar 17 is rotated clockwise through the frame 17e. This also releases the latch 38 and trips. In order to re-engage (reset) the latch 38 unlocked by the trip with the ratchet portion 17a of the crossbar 17, the open / close handle 15 is rotated in the OFF direction (counterclockwise in FIG. 3). The lug 38b protruding left and right from the latch 38 is pushed by the arm 15a of the opening / closing handle 15, and the latch 38 is rotated clockwise. As a result, the latch 38 pushes the crossbar 17 against the compression spring 37 to repel the crossbar 17 and engages with the ratchet portion 17a.
[0019]
In the earth leakage breaker shown in FIGS. 1 to 5, the bimetal 6 is disposed on the power supply terminal side opposite to the earth leakage detection mechanism 12 with the movable contact 10 as a boundary. Therefore, the leakage detecting mechanism 12 is far from the bimetal 6, and the electronic components mounted on the printed board 24 are not affected by the heat generated by the bimetal 6. As a result, the operating temperature of the bimetal 6 can be increased as compared with the conventional case, and it is necessary to use an expensive material for the bimetal 6 in order to increase the amount of deformation, or to lengthen the entire length by bending the bimetal 6. There is no.
[0020]
The trip coil 25 supported by the frame 14 of the opening / closing mechanism 13 is located at the center of the space above the crossbar 17, and the plunger 29 is directly engaged with the crossbar 17. As a result, the installation space for the crossbar 17 and the trip coil 25 is shared, so that a load can be applied directly to the center of the crossbar 17 during trip operation, and stable tripping characteristics can be obtained and tripping can be achieved. Parts such as a support plate for the coil 25 and screws for fixing the coil 25 to the case 1 are not required.
[0021]
Further, the distance between the bimetal 6 and the power supply terminal 3 is short, and the bimetal 6 and the power supply terminal 3 are connected via a flexible conductive plate 35 therebetween. Therefore, heat radiation around the bimetal is more constant than in the case of the conventional amorphous lead wire 7 (see FIG. 7), and stable operation characteristics can be obtained.
[0022]
Here, FIG. 6 is a side view of a bimetal portion showing a different embodiment of the conductive plate 35. 6, a protruding portion 35a protruding toward the bimetal 6 is formed in a U-bend portion of the conductive plate 35 by bending. When the bimetal 6 curves rightward in FIG. 6, the bimetal 6 eventually comes into contact with the protrusion 35a as shown by a broken line in FIG. Therefore, after this contact, the area of the bimetal 6 shown in the drawing S is short-circuited by the conductive plate 35, and accordingly, heat generation is reduced and the amount of deformation is suppressed. According to such a conductive plate 35, when the bimetal 6 tries to deform more than necessary due to a large current, the bimetal 6 hits the conductive plate 35, whereby excessive deformation is suppressed, and the bimetal 6 is permanently deformed. Interference with other parts and their melting are prevented.
[0023]
As a means for short-circuiting a part of the bimetal current path with the conductive plate along with the bending of the bimetal, the bimetal-side leg 35b of the conductive plate 35 formed in a U-shape as shown by a broken line in FIG. 6, the contact area between the leg 35b and the bimetal 6 may be expanded downward as the bimetal 6 curves.
[0024]
【The invention's effect】
As described above, according to the present invention, by making the leakage detection mechanism less susceptible to the heat generated by the bimetal, the selection and shape of the bimetal material are simplified, and the material cost and processing cost are reduced. In addition, by applying the load from the trip coil to the center of the crossbar during the trip operation, the life reliability and operating characteristics of the crossbar are improved. Further, by supporting the trip coil on the frame of the opening / closing mechanism, the installation space for the trip coil is reduced and the number of components is reduced. Furthermore, by connecting the bimetal to the terminal via the conductive plate, the heat radiation around the bimetal is constant, and the operating characteristics are stabilized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an earth leakage breaker showing an embodiment of the present invention.
FIG. 2 is a plan view of the earth leakage breaker of FIG. 1 with a cover removed.
FIG. 3 is a longitudinal sectional view of a main part of an opening / closing mechanism and a trip coil in FIG. 1;
FIG. 4 is a perspective view of a main part of FIG. 4;
FIG. 5 is a side view of a bimetal connection portion in FIG. 1;
FIG. 6 is a side view showing a different embodiment of a bimetal connection portion.
FIG. 7 is a longitudinal sectional view of a leakage breaker showing a conventional example.
8 is a plan view of the earth leakage breaker of FIG. 7 with a cover removed.
9A and 9B show a connection state between a bimetal and a load terminal in the earth leakage breaker of FIG. 7, wherein FIG. 9A is a plan view and FIG. 9B is a side view.
FIG. 10 is a side view of the switching mechanism in the earth leakage breaker of FIG. 7;
11 shows a tripping coil in the earth leakage breaker of FIG. 7, (A) is a front view, and (B) is a longitudinal sectional view.
[Explanation of symbols]
REFERENCE SIGNS LIST 3 power terminal 4 fixed contact 5 movable contact 6 bimetal 8 load terminal 10 movable contact 12 leakage detecting mechanism 13 opening and closing mechanism 14 frame 15 opening and closing handle 17 cross bar 23 zero-phase current transformer 24 printed board 25 trip coil 29 plunger 35 Conductive plate 38 Latch 40 Opening / closing spring

Claims (7)

It has a movable contact provided with a movable contact on an energizing path from a power terminal to a load terminal. The movable contact is opened / closed by operating an opening / closing mechanism, and forms a part of the energizing path when an overcurrent occurs. In a two-pole earth leakage breaker that trips the opening / closing mechanism by exciting a tripping coil by an earth leakage detection mechanism when an earth leakage occurs and also when an earth leakage occurs, and the movable contact is opened.
A two-pole earth leakage breaker, wherein the bimetal is arranged on a power supply terminal side opposite to the earth leakage detection mechanism with the movable contact as a boundary. 2. The two-pole earth leakage circuit breaker according to claim 1, wherein said trip coil is arranged at the center of the opening / closing mechanism on the left and right sides. The two-pole earth leakage breaker according to claim 2, wherein the crossbar of the opening / closing mechanism is directly rotated by the plunger of the trip coil. The two-pole earth leakage breaker according to claim 3, wherein the trip coil is supported by a frame of the opening / closing mechanism. 5. The two-pole earth leakage breaker according to claim 4, wherein the frame is made of a magnetic material, and the yoke of the trip coil is formed integrally with the frame. The two-pole earth leakage breaker according to claim 1, wherein the bimetal and the power terminal are connected via a flexible conductive plate curved in a U-shape. The two-pole earth leakage breaker according to claim 6, wherein the bimetal hits the conductive plate as it bends, and the conductive plate short-circuits a part of a current path of the bimetal.

Images