Gas-filling circuit breaker

Abstract: A gas filled circuit breaker comprises a hermetically sealed tank (1) formed by a surrounding wall (1b) filled with an insulating gas, at least one pair of contacts being arranged inside the surrounding wall. Contact operating means include force generating means which generate a force for operating the contacts and are arranged outside the surrounding wall (1b, 1c), and a rotational shaft (2) connected to the force generating means at the outside of the surrounding wall and extending to the inside thereof so that the force is transmitted through the surrounding wall to the inside thereof. Seal means are arranged between the surrounding wall (1b, 1c) and the shaft (2) to keep a hermetic seal therebetween. At least two bearings support the shaft (2) in a rotatable manner. Connecting means (15) for transmitting the force from the shaft (2) to at least one of the contacts to be moved in relation to the other are connected to the shaft (2) between the bearings.

Description: BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT The present invention relates to a gas-filled circuit breaker, particularly to a gas-filled circuit breaker whose driving force for operating contacts is supplied from the outside of the breaker. Generally, a gas-filled circuit breaker has a pair of contacts in a hermetically sealed container filled with an arc-extinguishing gas, and an operating device for driving the pair of contacts to be closed and opened is arranged at the outside of the hermetically sealed container. Therefore, a driving force transmission mechanism between the operating device and movable one of the contacts includes a hermetically sealed connecting mechanism for transmitting the driving force with maintaining the hermetic seal of the container. The conventional hermetically sealed connecting mechanisms includes a rotational seal structure (see Figs. 5a, 6 and 8) or a linear seal structure. The rotational seal as shown in Fig. 5a is disclosed by Publication of Laid-open Japanese Patent Application 61-284014. In Fig. 5a, a hermetically sealed container 1 with an end plate 1b and so forth is filled with the arc-extinguishing gas and receives an interrupter portion 12 including a pair of contacts. A movable part of the interrupter portion 12 is connected through an insulated operating rod 15 to an interior lever 16 fixed to a rotational shaft 2. The rotational shaft 2 extends through a side wall of a case 17 fixed to the end plate 1b with a hermetic seal between the shaft 2 and the side wall, and has an exterior lever 4 at the outside of the case 17. The exterior lever 4 is connected to a driving shaft 18 of an operating device 13 with a dashpot device 10 and a closing spring 11. When the interrupter portion 12 is operated by the operating device 13 to be opened or closed, the rotational shaft 2 is rotated with keeping the hermetic seal of the case 17 and of the hermetically sealed container 1 with a gasket or the like. Rotational seal structures in which the shaft is supported by two bearings, one on each side of the interior lever, are disclosed in US-2 853 584 and FR-B-1 485 270. In the conventional gas-filling circuit breaker including the linear seal structure as disclosed by Publication of Laid-open Japanese Utility Model Application 52-156973, the driving rod 18 is coaxially connected to the insulated operating rod 15 and extends through a wall surface of the case 17 with keeping the hermetic seal between the driving rod 18 and the case 17. OBJECT AND SUMMARY OF THE INVENTION The object of the present invention is to provide a gas-filled circuit breaker in which only a small number of bearings are used, but a reliability of the bearings is high. This object is solved by the circuit breaker set forth in claim 1. In the gas-filling circuit breaker according to the present invention, since the connecting means are connected to the rotational shaft means between the bearings, each of radial loads of the bearings supporting a radial force applied from the moved one of the contacts through the connecting means to the rotational shaft means is smaller than the radial force applied from the moved one of the contacts. Therefore, a reliability of the bearings is improved and a size of the bearings may be small, though the minimum number of the bearings are used. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1a is a partially cross-sectional view showing an embodiment of a gas-filling circuit breaker according to the present invention. Fig. 1b is a cross-sectional view showing an embodiment of a gas-filling circuit breaker according to the present invention. Fig. 2 is a plan view showing a part of the embodiment of Fig. 1a. Fig. 3 is a detailed cross-sectional view showing a part of the embodiment of Fig. 1a. Fig. 4 is a partially cross-sectional view showing a part of another embodiment of a gas-filling circuit breaker according to the present invention. Fig. 5a is a cross-sectional view showing a conventional gas-filling circuit breaker. Fig. 5b is a partially cross-sectional view showing a part of a conventional gas-filling circuit breaker. Fig. 6 is a partially cross-sectional view showing the other embodiment of a gas-filling circuit breaker according to the present invention. Fig. 7 is a partially cross-sectional view showing details of an embodiment of the present invention. Fig. 8 is a partially cross-sectional view showing a part of a conventional gas-filling circuit breaker. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS As shown in Figs. 1a, 1b, 2, and 3, a hermetically sealed container 1 with an end plate 1b and so forth is filled with an arc-extinguishing-and-insulating gas and receives an interruptor device as shown in Fig. 5. A movable part of the interruptor device is supported movably by an insulating tube 19 and is connected to a left end of an insulated operating rod 15. A case lc projects outwardly from the end plate 1b of the hermetically sealed container 1 and has a pair of wall surfaces opposite to each other as shown in Fig. 1a. A rotational shaft 2 extends through the pair of wall surfaces, and hermetic seals in a rotatable manner are formed by gaskets or the like between the rotational shaft 2 and the case 1c. The rotational shaft 2 is fixed to a pair of exterior levers 4a and 4b at the outside of the hermetically sealed container 1 and is fixed to an interior lever 16 at the inside of the case 1c. The exterior levers 4a and 4b are connected to output shafts 5 of an operating device 13 respectively. The interior lever 16 is arranged at a longitudinally central portion of the rotational shaft 2, and distances between the exterior levers 4a, 4b and the longitudinally central portion of the rotational shaft 2 are equal to each other. Gaskets 6 are arranged between the rotational shaft 2 and the wall surfaces of the case 1c, and a pin 20 connects the interior lever 16 to the insulated operating rod 15. An operating force of the operating device 13 is transmitted to the rotational shaft 2 by the output shafts 5 through the exterior levers 4a, 4b mounted on respective longitudinal ends of the rotational shaft 2 so that the rotational shaft 2 is rotated to drive the movable part of the interruptor device through the interior lever 16 and the insulated operating rod 15. Since the interior lever 16 is connected to the rotational shaft 2 between bearings 30, each of radial loads of the bearings 30 supporting a radial force applied from the movable part of the interruptor device through the interior lever 16 and the insulated operating rod 15 to the rotational shaft 2 is smaller than the radial force applied from the movable part of the interruptor device through the interior lever 16 and the insulated operating rod 15 to the rotational shaft 2. Therefore, a reliability of the bearings 30 is improved and a size of the bearings 30 may be small, though the minimum number of the bearings 30 are used. And, a thickness of the wall of the case lc and a diameter of the rotational shaft 2 may be small in comparison with the prior art. In Fig. 4, the rotational shaft 2 is supported on walls opposite to each other in the hermetically sealed container 1 without the case 1. The longitudinal ends of the rotational shaft 2 are rotatably supported on the walls of the hermetically sealed container 1 with the gaskets therebetween and extend to the outside of the hermetically sealed container 1 to be fixed to the exterior levers 4a, 4b connected to the output shaft of the operating device. The rotational shaft 2 is fixed to the interior lever 16 connected to the movable part of the interruptor device at the inside of the hermetically sealed container 1. Since the rotational shaft 2 is driven through both of the longitudinal ends thereof, the diameter of the rotational shaft 2 may be small. As described above, it is important for the rotational shaft 2 to support the interior lever 16 between the bearings 30 on the walls opposite to each other. In Fig. 6, the hermetically sealed container 1 receives the interruptor portion 12 including three pairs of contacts for a three-phase circuit. The interruptor portion 12 may be so-called puffer-type. Right ends of the insulated operating rods 15 for the three pairs of contacts are connected to a common support body 21 through pins. The support body 21 is connected through pins to the rotational shaft 2 at the inside of the hermetically sealed container 1. The rotational shaft 2 is supported in a manner shown in Fig. 4, or alternatively in a manner shown in Fig. 1. Since the rotational shaft 2 supports the interior lever 16 between the bearings 30 to drive the movable parts of the three pairs of contacts and is driven through both of the longitudinal ends thereof, a diameter of the rotational shaft 2 may be small. The present invention may be applied to a gas-filling circuit breaker including a plurality of the hermetically sealed containers 1 each of which receives the pair of contacts and in which a common operating device drives the pairs of contacts to close or open. The output shaft 5 extends among the hermetically sealed containers 1 so that all of the exterior levers 4a, 4b are driven by the output shaft 5. The distances between the exterior levers 4a, 4b and the longitudinally central portion of the rotational shaft 2 may be different from each other and the interior lever 16 may be arranged at a position different from the longitudinally central portion of the rotational shaft 2 in the hermetically sealed containers 1. Fig. 7 shows details of an embodiment of the invention.

Claims: A gas-filled circuit breaker comprising, a hermetically sealed tank (1) formed by a surrounding wall (1b, 1c) filled with an insulating gas, at least one pair of contacts (12) arranged inside the surrounding wall (1b, 1c), and contact operating means including force generating means (10, 11, 13) which generate a force for operating the contacts (12) and are arranged outside the surrounding wall (1b, 1c), rotational shaft means (2) connected to the force generating means (10, 11, 13) at the outside of the surrounding wall (1b, 1c) and extending to the inside of the surrounding wall for transmitting the force through the surrounding wall (1b, 1c) to the inside thereof, hermetic seal means (6) arranged between the surrounding wall (1b, 1c) and the shaft means (2), at least two bearings (30) for supporting the shaft means (2) on said tank (1), and connecting means (15, 16) connected to the shaft means (2) between the bearings (30) for transmitting the force to at least one of the contacts (12) to be moved in relation to the other contact, characterised in that said bearings (30) are located between two points where the shaft means (2) is connected to the force generating means (10, 11, 13). The circuit breaker of claim 1, wherein both ends of the shaft means (2) are connected to the force generating means (10, 11, 13) at the outside of the surrounding wall (1b, 1c). The circuit breaker of claim 1 or 2, wherein the bearings (30) are mounted on the surrounding wall (1b, 1c). The circuit breaker of any of claims 1 to 3, wherein the force generating means (10, 11, 13) include link means (4) mounted on the shaft means (2). The circuit breaker of any of claims 1 to 4, wherein the force generating means includes a rotary actuator connected to the shaft means (2). The circuit breaker of any of claims 1 to 5, including a plurality of pairs of contacts (12).

Inventors: FUKUCHI TETSUO, HOKUTOU HIROMICHI, OHNO MASATOMO, SUZUKI AKIRA, FUKUCHI, TETSUO, HOKUTOU, HIROMICHI, OHNO, MASATOMO, SUZUKI, AKIRA
Applicants: HITACHI LTD, HITACHI, LTD.
Application year: 1991
Main classification: H01H33
IPC codes: H01H33