Double motion circuit breaker

This application claims priority from Indian Patent Application no 3081/mum/2010 filed on 9th November 2010.

FIELD OF THE INVENTION :

The present invention relates to a double motion circuit breaker. More specifically, the present invention relates to a circuit breaker having contacts relatively movable in opposite direction.

BACKGROUND OF THE INVENTION

A conventional circuit breaker consists of a stationary contact and a movable contact. The movable contact moves relative to the stationary contact for facilitating opening and closing of the circuit breaker. The movement of the movable contact is actuated by an operating mechanism of the circuit breaker, which also controls the speed and automatic movement of the movable contact.

In an open position, the contacts of a circuit breaker are separated by a predetermined distance. The movable contact travels the predetermined distance in a direction towards the stationary contact to switch to a closed position. Similarly, to switch to an open position, the movable contact travels the predetermined distance in a direction away from the stationary contact.

The movable contact moves with some contact speed based on the voltage rating of the circuit breaker. This speed requirement decides the operating energy of the mechanism. When the distance between the movable and the stationary contact is large, a significant time is spent in switching the circuit breaker from an open to closed position and vice versa, thereby affecting the efficiency of the operation of the circuit breaker. An increase in speed of the movable contact to travel the predetermined distance in reduced time requires more operating energy of the mechanism. Hence, there is a need for a circuit breaker, in which time taken by contacts in switching from a closed position to an open position and vice versa is significantly less without requiring additional mechanical energy .

OBJECTS OF THE INVENTION

An object of the present invention is to provide a circuit breaker, in which time taken by the contacts in switching from a closed position to an open position and vice versa is significantly less without requiring additional mechanical energy.

Another object of the invention is to provide a circuit breaker which is energy efficient and wherein a faster relative movement of the contacts is achieved with a relatively lesser amount of energy.

DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION

According to the invention, there is provided a double motion circuit breaker comprising a housing enclosing a driving contact and a driven contact disposed in a spaced apart relationship and relatively movable toward and away from each other, the driving contact being actuated by an operating mechanism of the circuit breaker; and

a mechanical linkage coupled to both the driving and driven contacts for guiding and facilitating their relative motion thereof, the mechanical linkage comprising a sprocket wheel rotatably mounted on a shaft fixed to the housing, a chain engaging the sprocket wheel and extending between two ends, one end of the chain being operably coupled to the driving contact and another end being operably coupled to the driven contact; and

a biasing member operably coupled to the sprocket wheel for guiding rotation of the sprocket wheel, the sprocket wheel being rotatable to move the driving and driven contacts away from each other when the biasing member stores energy and being rotatable to bring the driving and driven contacts toward each other when the biasing member releases energy.

Preferably, the one end of the chain is coupled to an insulating nozzle connected to the driving contact.

Preferably, the another end of the chain is coupled to a first horizontal plate fixed to the driven contact.

Preferably, the biasing member comprises a helical spring connected between the first horizontal plate and a second horizontal plate, the second horizontal plate being fixedly disposed in the housing in a space between the sprocket wheel and the first horizontal plate.

Preferably, the biasing member comprises a spiral spring mounted on the shaft carrying the sprocket wheel.

These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,

Fig. l illustrates a double motion circuit breaker having relatively movable contacts in a closed position in accordance with one embodiment of the present invention; Fig.2 illustrates a double motion circuit breaker having relatively movable contacts in an open position in accordance with the one embodiment of the present invention;

Fig.3 illustrates a double motion circuit breaker having relatively movable contacts in a closed position in accordance with another embodiment of the present invention; and

Fig.4 illustrates a double motion circuit breaker having relatively movable contacts in an open position in accordance with the another embodiment of the present invention.

Referring to figures 1-2, a double motion circuit breaker 10 comprises a housing 1 which encloses a driving contact 2 and a driven contact 3 disposed in a spaced apart relationship and relatively movable toward and away from each other. The driving contact 2 and the driven contact 3 are electric contacts which relatively move toward each other to establish an electric connection and relatively move away from each other to break the electric connection established therein. In an exemplary embodiment of the present invention, the double motion circuit breaker 10 is a gas circuit breaker. The motion of the driving contact 2 relative to the driven contact 3 is actuated by an operating mechanism (not shown in the figure) operably coupled to the driving contact 2. The operating mechanism of the circuit breaker provides necessary kinetic energy to the driving contact 2 for moving relative to the driven contact 3.

The driving contact 2 and the driven contact 3 are coupled together by a mechanical linkage which comprises a sprocket wheel 11, a chain 12, a biasing member such as a helical spring 13, and a first horizontal plate 14. The mechanical linkage guides and facilitates the relative motion of the contacts 2 and 3 in opposite directions when the driving contact 2 is actuated by the operating mechanism.

The sprocket wheel 1 1 is rotatably mounted on a shaft 1 11 fixed to the housing 1. The chain 12 engages the sprocket wheel 1 1 and extends between two ends 122 and 123. The one end 122 is coupled to an insulating nozzle 21 of the driving contact 2 and the another end 123 is coupled to the first horizontal plate 14 which is fixedly connected to the driven contact 3. Thus, the ends 122 and 123 of the chain 12 are operably coupled to the contacts 2 and 3 respectively. The ends 122 and 123 of the chain 12 are relatively movable in opposite direction, thereby facilitating the contacts 2 and 3 to be relatively movable in opposite directions.

The motion of the ends 122 and 123 is guided by the motion of the driving contact 2 and rotation of the sprocket wheel 11. The rotation of the sprocket wheel 1 1 is guided by the helical spring 13 operably coupled thereto. The helical spring 13 is connected between the first horizontal plate 14 and a second horizontal plate 15 fixedly disposed in the housing 1 in space between the sprocket wheel 1 1 and the first horizontal plate 14.

The sprocket wheel 1 1 is rotatable in anticlockwise direction to move the driving and driven contacts 2 and 3 away from each other when the helical spring 13 stores energy and is rotatable in clockwise direction to bring the driving and driven contacts 2 and 3 toward each other when the helical spring 13 releases energy. The helical spring 13 compresses and stores potential energy when the driving contact 2 moves downward. The helical spring 13 stretches and releases energy when the driving contact 2 moves upward, thus facilitating downward motion of the driven contact 3.

With reference to the Fig. l, the contacts 2 and 3 are shown in closed position and the helical spring 13 in stretched position. It may be assumed that when the contacts 2 and 3 are in fully closed position, the helical spring 13 is in fully stretched position and does not allow further rotation of the wheel 11 in clockwise direction to move the contacts 2 and 3 toward each other. In such position, the sprocket wheel 1 1 is movable only in anticlockwise direction on downward motion of the driving contact 2.

With reference to the Fig.2, the contacts 2 and 3 are shown in open position and the helical spring 13 in compressed position. It may be assumed that when the contacts 2 and 3 are in fully opened position, the helical spring 13 is in fully compressed position and does not allow further rotation of the wheel 1 1 in anticlockwise direction to move the contacts 2 and 3 away from each other. In such position, the sprocket wheel 11 is movable only in clockwise direction on upward motion of the driving contact 2. Figs. 3 and 4 illustrate a double motion circuit breaker 20 in which the biasing member is a spiral spring 16 mounted on the shaft 1 1 1 carrying the sprocket wheel 11.

The sprocket wheel 1 1 is rotatable in anticlockwise direction to move the driving and driven contacts 2 and 3 away from each other when the spiral spring 16 stores energy and is rotatable in clockwise direction to bring the driving and driven contacts 2 and 3 toward each other when the spiral spring 16 releases energy. The spiral spring 16 compresses and stores potential energy when the driving contact 2 moves downward. The spiral spring 16 stretches and releases energy when the driving contact 2 moves upward, thus facilitating downward motion of the driven contact 3.

With reference to Fig. 3, the contacts 2 and 3 are shown in closed position and the spiral spring 16 in stretched position. In the stretched position, the spiral spring 16 may not allow further rotation of the wheel 1 1 in clockwise direction to move the contacts 2 and 3 toward each other and may only allow rotation of the wheel in anticlockwise direction.

With reference to Fig.4, the contacts 2 and 3 are shown in open position and the spiral spring 16 in stretched position. In the stretched position, the spiral spring 16 may not allow further rotation of the wheel 1 1 in anticlockwise direction to move the contacts 2 and 3 away from each other and may only allow rotation of the wheel in clockwise direction.

In various embodiments of the present invention, operationally, when the operating mechanism actuates the driving contact 2, the contact 2 either moves towards or away from the driven contact 3. The insulating nozzle 21 moves along with the driving contact 2 and either pulls or push the end 122 of the chain 12. The movement of the end 122 rotates the sprocket wheel 1 1 and the end 123 moves in a direction opposite to the direction of motion of the end 122. The horizontal plate 14 moves along with end 123, thereby driving the driven contact 3 in a direction opposite to the motion of the driving contact 2. When the driving contact 2 moves downwards and away from the driven contact 3, the biasing member (13, 16) compresses and stores energy. When the driving contact 2 moves upwards and towards the driven contact 3, the biasing member (13, 16) stretches and releases energy, thereby facilitating downward motion of the driven contact 3 towards the driving contact 2.

In various embodiments of the present invention, the kinetic energy provided by the operating mechanism for moving the driving contact 2 is utilized by the mechanical linkage for moving the driven contact 3 relative to the driving contact 2. Thus, no extra energy is provided to the driven contact 3 for moving relative to the contact 2. The relative motion of the contacts 2 and 3 towards and away from each other reduces the time ordinarily required by circuit contacts to switch from a closed position to an open position and vice versa. Due to relative motion in opposite direction, more distance is travelled in lesser time and with same mechanical energy, thereby increasing efficiency of the operation of the circuit breaker (10, 20).

Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.