Patent Description:
Document <CIT> discloses a miniature circuit breaker, comprising: a housing defining an interior space; a control circuit board, disposed in the interior space; an operating mechanism comprising a handle, a latch connected to the handle, a trip bar capable of being locked with or unlocked from the latch, and a contact support frame supporting the latch and the trip bar; a first phase circuit comprising a first wiring terminal, a first stationary contact electrically connected to the first wiring terminal, a first movable contact pivotally connected to the contact support frame, and a second wiring terminal; a second phase circuit comprising a third wiring terminal, a second stationary contact electrically connected to the third wiring terminal, a second movable contact pivotally connected to the contact support frame, and a fourth wiring terminal electrically connected to the second movable contact; a closing actuating mechanism connected to and driving the operating mechanism; a first current detection device, configured to detect a current flowing through the first stationary contact, and electrically connected to the control circuit board; a second current detection device, configured to detect a current flowing through the second wiring terminal and the fourth wiring terminal; and an opening actuating mechanism, electrically connected the control circuit board, and configured to selectively drive the trip bar to be unlocked from the latch based on current information detected by the first current detection device.

Existing miniature circuit breakers (MCB) usually only have short-circuit and overload protection functions, and this kind of conventional MCBs cannot meet use requirements in some scenarios requiring leakage protection or remote operation. A current solution is to connect the MCB to other functional devices (e.g., a remote operating switch, or a residual current operated circuit breaker (RCBO)), etc., so as to form a circuit breaker capable of meeting various functional needs. However, such an assembled circuit breaker usually has a relatively large volume, particularly with a relatively large thickness, and thus cannot meet current miniaturization requirements for electrical elements. In addition, during assembly of said circuit breaker, individual functional devices need to be connected together, and it is necessary to note the wire connection order during the process, and once a wire connection error occurs, there may be an irreparable loss for the entire circuit. This kind of complex assembly procedure is relatively time consuming and laborious.

Therefore, there is a need in the industry for designing a miniature circuit breaker with a simple structure, a small volume and simple wire connection.

The present invention aims to provide a miniature circuit breaker capable of solving at least part of the above-mentioned technical problems.

According to one aspect of the present invention, provided is a miniature circuit breaker, comprising: a housing, defining an interior space; a control circuit board, disposed in the interior space; an operating mechanism comprising a handle, a latch connected to the handle, a trip bar capable of being locked with or unlocked from the latch, and a contact support frame supporting the latch and the trip bar; a first phase circuit comprising a first wiring terminal, a first stationary contact electrically connected to the first wiring terminal, a first movable contact pivotally connected to the contact support frame, and a second wiring terminal; a second phase circuit comprising a third wiring terminal, a second stationary contact electrically connected to the third wiring terminal, a second movable contact pivotally connected to the contact support frame, and a fourth wiring terminal electrically connected to the second movable contact; a closing actuating mechanism, electrically connected to the control circuit board and connected to and driving the operating mechanism; a first current detection device, configured to detect a current flowing through the first stationary contact, and electrically connected to the control circuit board; a second current detection device, configured to detect a current flowing through the second wiring terminal and the fourth wiring terminal, and electrically connected to the control circuit board; and an opening actuating mechanism, electrically connected to the second wiring terminal and the control circuit board, and configured to selectively drive the trip bar to be unlocked from the latch based on current information detected by the first current detection device and the second current detection device.

In some implementations, the first wiring terminal is connected to the first stationary contact by means of a wire, and the first current detection device is a first current transformer sleeved on the wire.

In some implementations, the second wiring terminal is connected to the opening actuating mechanism by means of a wire, the fourth wiring terminal is connected to the second movable contact by means of a wire, and the second current detection device is a second current transformer sleeved on the two wires.

In some implementations, the opening actuating mechanism comprises: an opening armature, movably mounted in the interior space of the housing; and a first opening coil, surrounding the opening armature and electrically connected to the control circuit board; wherein the control circuit board is configured to control the opening armature to move based on current conditions detected by the first current detection device and/or the second current detection device, so as to drive the trip bar to be unlocked from the latch.

In some implementations, the opening actuating mechanism comprises: an opening armature, movably mounted in the interior space of the housing; and a second opening coil, surrounding the opening armature and electrically connected to the second wiring terminal, wherein the second opening coil drives the opening armature to move based on current conditions, so as to drive the trip bar to be unlocked from the latch.

In some implementations, the housing comprises a first half housing and a second half housing disposed opposite to each other, and an intermediate casing located between the first half housing and the second half housing, and the closing actuating mechanism is supported by the intermediate casing and comprises: a closing coil, disposed at the intermediate casing; and a closing armature, movably passing through the closing coil and connected to and driving the handle.

In some implementations, the control circuit board is secured to the intermediate casing at a location adjacent to the first wiring terminal and the first current detection device, and a clearance opening corresponding to the first current detection device is formed in the intermediate casing.

In some implementations, the contact support frame is pivotally mounted on the housing, and the first movable contact and the second movable contact are pivotally mounted on the contact support frame, wherein overtravel of the first movable contact is less than overtravel of the second movable contact, and an arc extinguishing chamber corresponding to the first stationary contact is arranged in the interior space.

In some implementations, the operating mechanism further comprises an indicator plate pivotally mounted on the housing, the indicator plate has an arc-shaped slot, and a connecting pin pivotally connecting the latch to the contact support frame is inserted in the arc-shaped slot and is movable in the arc-shaped slot.

In some implementations, the miniature circuit breaker further comprises a test assembly, and the test assembly comprises: a button, movably mounted at the housing; and a conductive structure, provided on the button and electrically connected to the fourth wiring terminal; and a resistor, electrically connected to the control circuit board and the first wiring terminal; wherein when the button is moving towards the housing, the conductive structure is capable of being electrically connected to the resistor.

Part of the other features and advantages of the present invention would be obvious to those skilled in the art after reading the present application, and the rest will be described in the following specific implementations with reference to the accompanying drawings.

Embodiments of the present invention are described in detail in the following with reference to the accompanying drawings:.

housing; <NUM>. first half housing; <NUM>. second half housing; <NUM>. support wall; <NUM>. pivoting shaft; <NUM>. intermediate casing; <NUM>. first casing portion; <NUM>. recess; <NUM>. second casing portion; <NUM>. operating mechanism; <NUM>. handle; <NUM>. tooth structure; <NUM>. handle torsional spring; <NUM>. orifice; <NUM>. connecting rod; <NUM>. latch; <NUM>. trip bar; <NUM>. trip bar torsional spring; <NUM>. contact support frame; <NUM>. contact support frame torsional spring; <NUM>. first pin; <NUM>. second pin; <NUM>. connecting pin; <NUM>. indicator plate; <NUM>. arc-shaped slot; <NUM>. first phase circuit; <NUM>. first movable contact; <NUM>. first movable contact torsional spring; <NUM>. first arc-shaped segment; <NUM>. first stationary contact; <NUM>. first wiring terminal; <NUM>. wire; <NUM>. second wiring terminal; <NUM>. wire; <NUM>. arc extinguishing chamber; <NUM>. first current transformer; <NUM>. second phase circuit; <NUM>. second movable contact; <NUM>. second movable contact torsional spring; <NUM>. second arc-shaped segment; <NUM>. second stationary contact; <NUM>. third wiring terminal; <NUM>. fourth wiring terminal; <NUM>. wire; <NUM>. closing actuating mechanism; <NUM>. closing coil; <NUM>. closing armature; <NUM>. rack; <NUM>. transmission gear; <NUM>. first gear; <NUM>. second gear; <NUM>. opening actuating mechanism; <NUM>. opening armature; <NUM>. first opening coil; <NUM>. second opening coil; <NUM>. control circuit board; <NUM>. test assembly; <NUM>. button; <NUM>. wire; <NUM>. elastic member; <NUM>. resistor; <NUM>. second current transformer.

A schematic scheme of the miniature circuit breaker disclosed in the present invention is described in detail below with reference to the accompanying drawings. Although the accompanying drawings are provided to present some implementations of the present invention, the accompanying drawings do not need to be drawn according to the size of the specific implementation schemes, and certain features can be enlarged, removed, or locally exploded to better illustrate and explain the disclosure of the present invention. Part of the components in the accompanying drawings can be positionally adjusted according to actual requirements without affecting the technical effect. In the description, the term "in the accompanying drawings" or similar terms do not necessary refer to all of the accompanying drawings or examples.

Some directional terms used in the following to describe the accompanying drawings, such as "in", "out", "upper", and "lower," and other directional terms are construed as having normal meanings thereof and refer to those directions involved when the accompanying drawings are viewed normally. Unless otherwise specified, the directional terms in the description are substantially in accord with conventional directions understood by those skilled in the art.

The terms "first", "first one," "second", "second one" and similar terms used in the present invention do not indicate any sequence, number, or importance in the present invention, and are used only to distinguish one component from other components.

<FIG> show a miniature circuit breaker according to embodiments of the present invention. As shown in <FIG>, the miniature circuit breaker accommodates an operating mechanism, two-phase (1P+N) circuits, and corresponding opening and closing actuating mechanisms, controller, current detection device, etc. in an interior space defined by a single housing <NUM>. In this way, the miniature circuit breaker module shown in <FIG> can realize short circuit, overload, and leakage protection functions and can be operated remotely. The width H of the miniature circuit breaker module is defined as: H ≤ <NUM> millimeters (i.e., less than or equal to <NUM> modulus), thereby achieving a simple structure and greatly reducing the volume. In addition, the miniature circuit breaker has only four wiring terminals, thereby optimizing wire connection operations and ensuring safety.

In the embodiment shown in <FIG> and <FIG>, the housing <NUM> consists of two opposite half housings, i.e., a first half housing <NUM> and a second half housing <NUM> that are detachably connected, and an intermediate casing <NUM> between the two opposite half housings. The first half housing <NUM>, the second half housing <NUM>, and the intermediate casing <NUM> collectively surround and define the interior space of the housing <NUM>, and the intermediate casing <NUM> divides the interior space into two compartments for respective arrangement of the two-phase circuits.

The interior construction of the miniature circuit breaker is described below with reference to the embodiments shown in <FIG>, wherein <FIG> is a schematic view viewed from a first phase (e.g., P phase) circuit, <FIG> is a schematic view viewed from a second phase (e.g., N phase) circuit, and the two circuits are respectively located in the compartments separated by the intermediate casing <NUM>. In the illustrated embodiment, the miniature circuit breaker includes an operating mechanism <NUM>, a first phase circuit <NUM>, a second phase circuit <NUM>, a closing actuating mechanism <NUM>, an opening actuating mechanism <NUM>, and a control circuit board <NUM>. The operating mechanism <NUM> includes a handle <NUM>, and a latch <NUM> and a trip bar <NUM> operable with the handle <NUM>. Referring to <FIG>, the handle <NUM> has an orifice <NUM> through which a shaft rod connected to the housing <NUM> passes, whereby the handle <NUM> is rotatable about the shaft rod. A portion of the handle <NUM> extends out of the housing <NUM> for manual opening and closing operations. A handle torsional spring <NUM> is arranged between the handle <NUM> and the housing <NUM>. The handle torsional spring <NUM> constantly applies, to the handle <NUM>, a force that makes the handle rotate in a first direction (the clockwise direction in <FIG>, and the counterclockwise direction in <FIG>) or have a tendency to rotate in the first direction. Once the handle <NUM> rotates in the first direction, it means that the miniature circuit breaker is opened.

The handle <NUM> is connected to the latch <NUM> by mean of a connecting rod <NUM>, the latch <NUM> is rotatably connected to a contact support frame <NUM> by mean of a connecting pin <NUM>, and the contact support frame <NUM> is rotatably connected to a pivoting shaft <NUM> of the housing <NUM>. A contact support frame spring <NUM> is arranged between the contact support frame <NUM> and a support wall <NUM> formed on the second half housing <NUM> of the housing <NUM>. The contact support frame spring <NUM> constantly applies, to the contact support frame <NUM>, a force that makes the contact support frame rotate in a second direction (the counterclockwise direction in <FIG>, and the clockwise direction in <FIG>) or have a tendency to rotate in the second direction. Once the contact support frame <NUM> rotates in the second direction, it means that the miniature circuit breaker is opened. The trip bar <NUM> is pivotally connected to the contact support frame <NUM>. In the illustrated embodiment, a pivoting axis of the trip bar <NUM> coincides with a pivoting axis of the contact support frame <NUM>. During closing of the miniature circuit breaker, the trip bar <NUM> is constantly locked together with the latch <NUM>. Once a current anomaly occurs in the circuit, e.g., overload, short circuit, or leakage, the trip bar <NUM> is driven by the opening actuating mechanism to be unlocked from latch <NUM>, thereby allowing opening of the miniature circuit breaker. A trip bar torsional spring <NUM> is connected between the contact support frame <NUM> and the trip bar <NUM>, and constantly applies, to the trip bar <NUM>, a force that makes the trip bar rotate in the first direction (the clockwise direction in <FIG>, and the counterclockwise direction in <FIG>) or have a tendency to rotate in the first direction. By means of the trip bar torsional spring <NUM>, the trip bar <NUM> unlocked from the latch <NUM> can be reset and relocked (re-fastened) with the latch <NUM>.

In order to clearly indicate the current opening/closing status of the miniature circuit breaker to the outside, the operating mechanism <NUM> is provided with an indicator plate <NUM>. The indicator plate <NUM> is rotatably connected to the shaft rod arranged at the housing <NUM>, and an arc-shaped slot <NUM> is formed on the body of the indicator plate <NUM>. The connecting pin <NUM> for connecting the latch <NUM> to the contact support frame <NUM> passes through the arc-shaped slot <NUM> and is movable in the arc-shaped slot <NUM>. Therefore, during opening and closing of the miniature circuit breaker, the indicator plate <NUM> is rotated such that different parts thereof are aligned with an opening formed on the housing <NUM>. The different parts can be marked with "open", "on", "close", "off", or other characters, or marked with different colors, such as blue and red, so as to transmit opening and closing status information to the outside.

The closing actuating mechanism <NUM> that drives the action of the operating mechanism <NUM> is mounted in the interior space of the housing <NUM>. Referring to <FIG>, in order to facilitate mounting of the closing actuating mechanism <NUM>, the intermediate casing <NUM> is provided with a recess <NUM>, and the closing actuating mechanism <NUM> is mounted in the recess <NUM>. In the illustrated embodiment, the closing actuating mechanism <NUM> is selected from electromagnetic closing mechanisms, and includes a closing coil <NUM> arranged in the recess and a closing armature <NUM> surrounded by the closing coil <NUM>. The closing armature <NUM> is connected to and drives the handle <NUM> by means of a transmission mechanism, and the closing coil <NUM> is electrically connected to the control circuit board <NUM> mounted on the second half housing <NUM>. The control circuit board <NUM> supplies power to the closing coil <NUM>, so as to drive the closing armature <NUM> to move, e.g., retract into the closing coil <NUM>, thereby driving the handle <NUM> to move.

In an embodiment, the closing armature <NUM> is connected to the handle <NUM> by means of a gear rack transmission mechanism. For example, a rack <NUM> is mounted on the closing armature <NUM>, the handle <NUM> has a tooth structure <NUM> arranged along the circumference thereof, and a transmission gear <NUM> is arranged between the rack <NUM> and the tooth structure <NUM>. The movement of the closing armature <NUM> drives, by means of the gear rack transmission mechanism, the handle <NUM> to rotate in the second direction, and the rotation of the handle <NUM> drives, by means of the connecting rod <NUM>, the latch <NUM>, the trip bar <NUM>, and the contact support frame <NUM> to rotate together. The contact support frame <NUM> rotates in the first direction, thereby driving, by means of a first movable contact torsional spring <NUM>, closing of a first movable contact <NUM> and a first stationary contact <NUM>, and driving, by means of a second movable contact torsional spring <NUM>, closing of a second movable contact <NUM> and a second stationary contact <NUM>.

In an embodiment, the transmission gear <NUM> may be composed of two gears connected together and having different numbers of teeth, i.e., a first gear <NUM> engaging with the rack <NUM> and a second gear <NUM> engaging with the tooth structure of the handle <NUM>. The two-gear structure can reduce a driving force required by the closing actuating mechanism during automatic closing, thereby reducing power consumption of the closing coil.

The two-phase circuits operable by the operating mechanism <NUM> are arranged adjacent to each other in the housing <NUM>. According to the embodiment as shown in <FIG>, the first phase circuit <NUM> may also be referred to as a P phase, and includes the first movable contact <NUM>, the first stationary contact <NUM>, a first wiring terminal <NUM>, and a second wiring terminal <NUM>. The first wiring terminal <NUM> is electrically connected to the first stationary contact <NUM> by means of a wire <NUM> to form a primary circuit. A first current transformer <NUM> is sleeved on the wire <NUM> and is located between the first wiring terminal <NUM> and the first stationary contact <NUM>. The first current transformer <NUM> is electrically connected to the control circuit board <NUM> located in the interior space of the housing <NUM>, thereby sending measured current information of the primary circuit to the control circuit board <NUM>. The control circuit board <NUM> is mounted on the second half housing <NUM> and located between the second half housing <NUM> and the intermediate casing <NUM>, and the intermediate casing <NUM> may be provided with a clearance opening to facilitate mounting of the first current transformer <NUM>. In an embodiment, the intermediate casing <NUM> may consist of a first casing portion <NUM> and a second casing portion <NUM> that are detachably provided, and the first casing portion <NUM> and the second casing portion <NUM> surround and define the clearance opening and the recess <NUM>.

The first movable contact <NUM> is pivotally connected to the contact support frame <NUM>, and the first movable contact torsional spring <NUM> is connected between the contact support frame <NUM> and the first movable contact <NUM>. The first movable contact torsional spring <NUM> applies, to the first movable contact <NUM>, a force that makes the first movable contact rotate in the first direction (the clockwise direction in <FIG>, and the counterclockwise direction in <FIG>) or have a tendency to rotate in the first direction. Once rotating in the first direction, the first movable contact <NUM> approaches and is connected to the first stationary contact <NUM> to achieve closing of the first phase circuit <NUM>.

The opening actuating mechanism <NUM> is arranged between the first movable contact <NUM> and the second wiring terminal <NUM>. According to the embodiments of the present invention, the opening actuating mechanism <NUM> has a dual protection function, i.e., overload protection and short circuit protection. As shown, the opening actuating mechanism <NUM> employs an electromagnetic trip mechanism, wherein a first opening coil <NUM> for overload protection surrounds an opening armature <NUM>, the first opening coil <NUM> is electrically connected to the control circuit board <NUM>, a second opening coil <NUM> for short-circuit protection surrounds the first opening coil <NUM>, and the second opening coil <NUM> is electrically connected to the second wiring terminal <NUM> by means of the wire <NUM>. In this way, once the first current transformer <NUM> detects an overload current, the control circuit board <NUM> supplies power to the first opening coil <NUM>, driving the opening armature <NUM> to move towards the trip bar <NUM> and apply an impact on the trip bar <NUM>, making the trip bar <NUM> unlocked from the latch <NUM>, and thus allowing opening of the first movable contact <NUM> and the first stationary contact <NUM>. Once a loop is short-circuited, for example, the first phase circuit and the second phase circuit form a short circuit connection, a current flowing in the second opening coil <NUM> electrically connected to the second wiring terminal <NUM> makes the second opening coil <NUM> generate a magnetic field sufficient to drive the opening armature <NUM>, such that the opening armature <NUM> moves and applies an impact on the trip bar <NUM>, making the trip bar <NUM> unlocked from the latch <NUM>, and thus allowing opening of the first movable contact <NUM> and the first stationary contact <NUM>.

In an embodiment, two overload current thresholds or threshold ranges are preset, wherein the first threshold or threshold range is less than the second threshold or threshold range. When an overload current detected by the first current transformer <NUM> is less than or equal to the first threshold or within the first threshold range, it means that the overload current is relatively small, in which case the power supply from the control circuit board <NUM> to the first opening coil <NUM> can be delayed for a preset time to realize a delayed opening function. When an overload current detected by the first current transformer <NUM> is equal to or greater than the first threshold or within the second threshold range, it means that the overload current is relatively large, in which case power can be supplied from the control circuit board <NUM> to the first opening coil <NUM> almost immediately to realize a short-time fast opening function. In addition, remote operation opening may be achieved by means of the first opening coil <NUM> and the opening armature <NUM> connected to the control circuit board <NUM>.

An embodiment of the second phase circuit <NUM> (e.g., N phase) is shown in <FIG>. As shown, the second phase circuit <NUM> includes a third wiring terminal <NUM>, the second stationary contact <NUM> electrically connected to the third wiring terminal <NUM>, the second movable contact <NUM>, and a fourth wiring terminal <NUM> electrically connected to the second movable contact <NUM> by means of a wire <NUM>. Similar to the first movable contact, the second movable contact <NUM> is pivotally connected to the contact support frame <NUM>, and the first movable contact and second movable contact are located on two opposite sides of the contact support frame, respectively. The second movable contact torsional spring <NUM> is connected between the second movable contact <NUM> and the contact support frame <NUM> and constantly applies, to the second movable contact <NUM>, a force that makes the second movable contact rotate in the first direction (the clockwise direction in <FIG>, and the counterclockwise direction in <FIG>) or have a tendency to rotate in the first direction. Once rotating in the first direction, the second movable contact <NUM> approaches and is connected to the second stationary contact <NUM> to achieve closing of the second phase circuit <NUM>.

In an embodiment, the opening of the first phase circuit <NUM> and the opening of second phase circuit <NUM> are asynchronous, and by making the overtravel of the first movable contact <NUM> less than the overtravel of the second movable contact <NUM>, the opening of the first movable contact <NUM> and the first stationary contact <NUM> may occur prior to the opening of the second movable contact <NUM> to the second stationary contact <NUM>.

The overtravel of the first movable contact <NUM> being less than the overtravel of the second movable contact <NUM> may be achieved by reasonably designing cooperation relationships between the contact support frame <NUM> with respect to the first movable contact <NUM> and second movable contact <NUM>. In the illustrated embodiment, the contact support frame <NUM> is provided with a first pin <NUM> on a side face where the first movable contact <NUM> is mounted and a second pin <NUM> on a side face where the second movable contact <NUM> is mounted, and an outer diameter of the first pin <NUM> is greater than an outer diameter of the second pin <NUM>. Pivoting axes of the first movable contact <NUM> and the second movable contact <NUM> coincide. The first movable contact <NUM> has a first arc-shaped segment <NUM> extending along an outer circumferential surface of the first pin <NUM>, the second movable contact <NUM> has a second arc-shaped segment <NUM> extending along an outer circumferential surface of the second pin <NUM>, and the arc angle of the first arc-shaped segment <NUM> is substantially the same as the arc angle of the second arc-shaped segment <NUM>. In this way, the overtravel of the first movable contact <NUM> is less than the overtravel of the second movable contact <NUM>, thereby enabling the opening of the first movable contact <NUM> and the first stationary contact <NUM> to occur prior to the opening of the second movable contact <NUM> and the second stationary contact <NUM>.

In addition to the reasonable design of the cooperation relationships of the contact support frame <NUM> with respect to the first movable contact <NUM> and the second movable contact <NUM>, a person skilled in the art could also conceive of other ways to configure the overtravel of the first movable contact <NUM> to be less than the overtravel of the second movable contact <NUM>. For example, in an embodiment not shown, the overtravel of the first movable contact <NUM> being less than the overtravel of the second movable contact <NUM> can be achieved by a design in which the force applied by the first movable contact torsional spring <NUM> to the first movable contact <NUM> is different from the force applied by the second movable contact torsional spring <NUM> to the second movable contact <NUM>.

Since the opening of the second phase circuit <NUM> occurs later than the opening of the first phase circuit <NUM>, an arc extinguishing chamber <NUM> may be arranged for the first phase circuit <NUM> only. As shown in <FIG>, the arc extinguishing chamber <NUM> is arranged directly below the first stationary contact <NUM>. Blocking plates (not shown) extending to the arc extinguishing chamber may be arranged at two opposite sides of the first stationary contact <NUM>, ensuring that an arc is directed towards the arc extinguishing chamber <NUM>.

Referring to <FIG> and <FIG>, the first phase circuit <NUM> and the second phase circuit <NUM> are provided with a second current transformer <NUM> for leakage protection. The wire <NUM> connecting the second wiring terminal <NUM> and the opening actuating mechanism <NUM> and the wire <NUM> connecting the fourth wiring terminal <NUM> and the second movable contact <NUM> both pass through the second current transformer <NUM>. The second current transformer <NUM> is electrically connected to the control circuit board <NUM> to send a signal to the control circuit board <NUM> upon detection of a leakage current, and based on the signal, the control circuit board <NUM> controls the opening actuating mechanism <NUM> to drive the trip bar <NUM> to trip.

The miniature circuit breaker according to this embodiment is further provided with a test assembly <NUM> for leakage tests. As shown in <FIG> and <FIG>, a button <NUM> of the test assembly <NUM> is inserted in an opening of the housing <NUM> and is movable relative to the housing <NUM>, and a conductive structure electrically connected to the fourth wiring terminal <NUM> is provided on a side of the button <NUM> facing the housing <NUM>. A wire <NUM> extends in the interior space of the housing <NUM> and is electrically connected to the control circuit board <NUM>. Moreover, the wire <NUM> is electrically connected to the wire <NUM>/first wiring terminal <NUM>. A resistor <NUM> is provided at an end portion of the wire <NUM> facing the button <NUM>, and the resistor <NUM> is in the interior space of the housing <NUM>, and is spaced apart from the button <NUM> and the conductive mechanism by a specific distance under normal conditions. When being pressed, the button <NUM> drives the conductive mechanism to form a short circuit connection with the resistor <NUM> and the wire <NUM>, and a leakage current would be generated since the conductive mechanism is electrically connected to the fourth wiring terminal <NUM> by means of a wire. When the control circuit board <NUM> detects a leakage signal, the control circuit board <NUM> supplies power the first opening coil <NUM>, driving the opening armature <NUM> to move towards the trip bar <NUM> and apply an impact on the trip bar <NUM>, making the trip bar <NUM> unlocked from the latch <NUM>, allowing the opening of the first movable contact <NUM> and the first stationary contact <NUM>, and thereby completing the leakage test.

In the illustrated embodiment, an elastic member <NUM> (e.g., a torsional spring) is arranged on the housing <NUM> and supports the button <NUM>. The elastic member <NUM> constantly applies, to the button <NUM>, a force that makes the button move in a direction away from the housing <NUM> or have a tendency to move in the direction away from the housing <NUM>. In this way, only when the button <NUM> is pressed toward the interior of the housing <NUM> can the button <NUM> drive the conductive structure to form a short circuit connection with the resistor <NUM> and conduct the circuit. Once the pressing force is withdrawn, the button <NUM> immediately moves away from the resistor under the action of the elastic member <NUM>, thus switching off the circuit. In an embodiment, the function of the conductive structure is achieved by electrically connecting the elastic member <NUM> to the fourth wiring terminal <NUM> by means of a wire.

It should be appreciated that although the description is presented according to each embodiment, each embodiment does not necessarily include only one independent technical solution. The presentation manner of the description is merely for clearness, and those skilled in the art should regard the description as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other implementations comprehensible by those skilled in the art.

Claim 1:
A miniature circuit breaker, comprising
a housing (<NUM>) defining an interior space;
a control circuit board (<NUM>), disposed in the interior space;
an operating mechanism (<NUM>) comprising a handle (<NUM>), a latch (<NUM>) connected to the handle (<NUM>), a trip bar (<NUM>) capable of being locked with or unlocked from the latch (<NUM>), and a contact support frame (<NUM>) supporting the latch (<NUM>) and the trip bar (<NUM>);
a first phase circuit (<NUM>) comprising a first wiring terminal (<NUM>), a first stationary contact (<NUM>) electrically connected to the first wiring terminal (<NUM>), a first movable contact (<NUM>) pivotally connected to the contact support frame (<NUM>), and a second wiring terminal (<NUM>);
a second phase circuit (<NUM>) comprising a third wiring terminal (<NUM>), a second stationary contact (<NUM>) electrically connected to the third wiring terminal (<NUM>), a second movable contact (<NUM>) pivotally connected to the contact support frame (<NUM>), and a fourth wiring terminal (<NUM>) electrically connected to the second movable contact (<NUM>);
a closing actuating mechanism (<NUM>), electrically connected to the control circuit board (<NUM>) and connected to and driving the operating mechanism (<NUM>);
a first current detection device, configured to detect a current flowing through the first stationary contact (<NUM>), and electrically connected to the control circuit board (<NUM>);
a second current detection device, configured to detect a current flowing through the second wiring terminal (<NUM>) and the fourth wiring terminal (<NUM>), and electrically connected to the control circuit board (<NUM>); and
an opening actuating mechanism (<NUM>), electrically connected to the second wiring terminal (<NUM>) and the control circuit board (<NUM>), and configured to selectively drive the trip bar (<NUM>) to be unlocked from the latch (<NUM>) based on current information detected by the first current detection device and the second current detection device.