CLOSING DEVICE AND CIRCUIT BREAKER WITH CLOSING DEVICE

A Closing Device and a Circuit Breaker with the Closing Device

FIELD OF THE INVENTION

The invention relates to an automatic closing device and a circuit breaker, and more particularly to a new automatic closing device and a Miniature Circuit Breaker (MCB) with the closing device.

BACKGROUND OF THE INVENTION

MCB is used to switch on/off the circuit connection in the normal or abnormal condition respectively. As a terminal protection device, MCBs are widely utilized in distribution system of various buildings. In order to provide electrical protection for terminal devices, MCBs switch off the connection between the terminal devices and the power in the case of abnormity, and reconvey the current into the terminal devices by closing operation until the operation condition is normal. Generally various circuit breakers, such as MCB, RCB (Residual Current Circuit Breaker) etc., reconnect the broken circuit by manual closing operation during the daily utilization. However, with the requirement of higher efficiency, automation system are used more and more commonly in constructions, and the circuit breakers need to be equipped with automatic closing devices which become a part of the automation system and greatly improve the operation efficiency.

As the closing operation is an energy storage process for the MCB and RCB, e.g. the operation of a four-linked-pole action mechanism, a great moment is required during the closing operation. At present, the automatic closing device in the circuit breaker is driven by the electromotor. The great moment acquired by the gear down implements the closing operation of the MCB or RCB. However, shortcomings of an automatic closing device comprising electromotor gears and the controlling system attribute to the complex structure, huge volume and high cost.

SUMMARY OF THE INVENTION

An object of the present invention is to overcome above mentioned shortcomings of prior arts, and provide a new closing device and a circuit breaker with the closing device. Such new closing device takes advantages of simple configuration, convenient operation and low cost.

According to an aspect of the present invention, a closing device is provided. The closing device comprises: a chamber of the closing device, a closing drive mechanism, a volume-variable component, a driver, and a closing handle; in which the closing drive mechanism and volume-closing component are set in the chamber, and the driver is configured in the volume-variable component; the volume-variable component is configured to increase or decrease the volume under the control of the driver; and the closing drive mechanism is configured to transmit the force generated by the increasing volume of the volume-variable component to the closing handle.

According to a preferred embodiment of the present invention, in which the chamber of the closing device is a rigid body; the volume-variable component is outside coated by a flexible film; the driver is made from an electrical heating element; and heated by the electrical heating element, said volume of the volume-variable component increases gradually.

According to another preferred embodiment of the present invention, the volume-variable component imposes action on the closing drive mechanism by a connective plunger; the driver is made from an electrical heating element; and heated by the electrical heating element, said volume of the volume-variable component increases in the direction of the plunger.

According to another preferred embodiment of the present invention, the closing drive mechanism comprises a closing drive channel and a plurality of beads; the closing drive channel is connected to the chamber of the closing device, and the plurality of beads moves from the chamber of the closing device to the closing drive channel during the volume-variable component' volume increasing; and the closing handle is set at the terminal of the closing drive channel apart from the volume-variable component, and said plurality of beads move to the closing handle along the closing drive channel during the volume-variable component's volume further increasing.

According to another preferred embodiment of the present invention, the variable-volume component is made of the paraffin or the memory alloy spring with an extension feature when heated; and the bead is made of steel, iron, ceramic, plastic, glass or resin. According to another aspect of the present invention, a MCB is provided, in which comprises the closing device mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention will be explained in more details in the following description with reference to preferred exemplary embodiments which are illustrated in the drawings, in which:

Fig.1 illustrates a cross-section of MCB according to a preferred embodiment of the present invention; and

Fig.2 illustrates an automatic closing device according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig.1 illustrates a MCB 1 according to a preferred embodiment of the present invention. In particular, a common manual closing MCB 1 is provided shown in Fig.1 , which comprises a closing handle 2, a closing drive channel 3, a plug 4, a column reset extension spring 5, a high heatproof spring film 6, a volume-variable component 7, wirings 8, a heating element 9, a chamber support 10 and a closing drive component 11 . Among the above parts, the chamber support 10 of the automatic closing device used in CBs is a rigid body, and coated by the high heatproof spring film 6, the heating element 9 and the volume-variable component 7 is set at one side of the chamber support 10. The closing drive component 11 is configured at the other side of the chamber support 10. The heating element 9 coated by the spring film 6 is connected with the automation system (not shown in Figures) of constructions. The operation principle of such automatic closing device is described as follows.

After the circuit breaker switches off, the automation system installed in the constructions will detect present electrical condition; send corresponding indications to the circuit breaker when the electrical condition meets the requirement on the safe operation of the terminal device, and input current to the heating element 7 via the wirings 8. Then the powered heating element starts to generate heat so that the temperature of the volume-variable component 7 coated in the high heatproof spring film rises gradually and its volume expands. Such heating element may be configured in the spring film or outside of the film. As long as matching the volume-variable component and assuring good heat-conduction, any one of the configuration means can be utilized in the present embodiment. In a preferred implementation, the volume-variable component 7 is in solid state at normal temperature, but becomes liquid as the temperature rises. What's more, the total volume of such component 7 increases proportionally during the melting period. Consequently, the space occupied by the spring film in the chamber support increases gradually with the increasing volume of the volume-variable component coated by the spring film 6. In particular, the volume-variable component may be made of the paraffin.

The closing drive component 11 lies in the other side of the chamber support, contrary to the region of the spring film, and drives the circuit breaker to perform the closing operation. As shown in figures, the closing drive component 11 comprises a driving channel and a plurality of beads, As the volume-variable component's volume increases, the beads originally staying in the chamber support are gradually pushed into the driving channel 3, and move along the driving channel 3 which matches the closed track of the circuit breaker's handle. In the faraway end of the driving channel, there is a reset spring 5, and the beads' movement to the closing handle need to overcome the elastic force of the reset spring. The closing handle 2 lies at the end of the driving channel. While the beads move to the location of the closing handle with the increase of the volume-variable component's volume, the beads drive the closing handle of the circuit breaker so as to perform closing operation on the circuit breaker 1 .

After detecting the closing operation on the circuit breaker, the construction's automation system switches off the current to the heating element 9, and the volume-variable component 7 becomes solid with the gradual cooling. During the solidification period, the volume occupied by the spring film decreases gradually, and under the action of the column reset spring 5, the solid matter congregates together in the side of the chamber support far away the driving channel. The beads in the driving channel also gradually return to the chamber support space under the action of the spring. In this way, the automatic closing device goes back to the initial state before the operation until the automation system supplies power to the heating element again to perform a new closing operation.

It should be noted that other compounds may also be used to replace the paraffin as long as the volume expansion of the compounds after heated, and the thermal expansion and contraction effect is obvious for such compounds. In particular, the paraffin exhibits a large volume expansion coefficient in the vicinity of its melting temperature. When the pressure is 200MPa, its maximum volume expansion coefficient rate can reach 15%. The expansible compound is not limited to a solid, and the liquid with a larger thermal expansion coefficient can be utilized in the automatic closing device provided in the present invention. In addition, the small beads, transferring the force generated by the volume expansion of the paraffin to the closing handle, can be made of steel, iron, ceramics, plastic, glass or resin and so on, as long as their intensity matching the power transmission requirement.

According to another preferred embodiment of the present invention, a memory alloy spring is provided as the volume expansion component or the length-variable component, which is comprised in the closing device shown in Fig.2.

Between the two implementations shown in Fig.1 and Fig.2, the differences comprise: the extensible elastic component 7' and the plunger 6' manufactured by memory alloy materials, shown in Fig.2, replace respectively the volume-variable component 7 made of the paraffin and the spring film 6 shown in Fig.1 .

Under the thermal action of the heating element, the memory alloy elastic component 7' will be expanded gradually a certain length and drive the connected plunger during the extension of the spring component. The plunger moves in the space of the support, and pushes the small beads into the closing handle's driving channel 3. In accordance with the first embodiment in a similar way, the little beads result in closing operation on the closing handle. When switch off the power to the heating element, the memory alloy elastic component will cool and shrink to its initial length gradually. At the same time, upon the force of reset spring 5, the small beads in the driving channel are pushed back to the support space.

Due to various characteristics of the memory alloy components, the driving equipment for expanding and contracting such alloy components can not only be the heating element, but also electromagnetic equipments or other drivers generating a specific signal.

In an embodiment, PTC components can be used as the heating element 9. While other heating equipments converting the current to thermal energy can also be used in the automatic closing device proposed in the present invention.

The automatic closing device provided in the present invention uses the extension produced in the phase change of materials or the length change produced by the memory alloys, and the small beads convert the volume or length change into a thrust along a specific direction so as to automatically perform the closing operation on the circuit breaker. Compared to the automatic closing devices with the electromotor configuration in prior arts, the automatic closing device takes advantages of small size, relatively low cost and very high reliability. Though the present invention has been described on the basis of some preferred embodiments, those skilled in the art should appreciate that those embodiments should by no means limit the scope of the present invention. Without departing from the spirit and concept of the present invention, any variations and modifications to the embodiments should be within the apprehension of those with ordinary knowledge and skills in the art, and therefore fall in the scope of the present invention which is defined by the accompanied claims.