DESC:Stored Energy Motor Operating Mechanism for Rotary Molded Case Circuit Breaker

Field of the invention

The present invention relates to a motor operating mechanism in a low voltage current limiting circuit breaker for electrical switches and more particularly, to a stored energy motor operating mechanism for a rotary molded case circuit breaker.

Background of the invention

Circuit breakers are designed for use in switchboards, control panels and combination starters in separate enclosures for effective single location distribution and control and safe operation by operators. Typically, a circuit breaker such as a molded case circuit breaker (herein after ‘the MCCB’) serves as a switching device for switching ON/OFF during normal operating conditions for the purpose of operation and maintenance and also, serves as a protecting device during abnormal conditions such as short-circuit, overload and under voltage for tripping/ isolating an electrical circuit by breaking the contacts to interrupt the fault current.

In most common type of installation, the circuit breaker is switched ON and OFF by rotating an operating handle mounted on a panel door of an enclosure. For remote operations as well as high end operations that require an electric supply to be reinstated in a very short span of time ranging in micro seconds or while swapping ends between two supplies, an add-on accessory such as a stored energy electrical operating mechanism (hereinafter referred as “the SE-EOM”) mounted on the MCCB is used.

In manual operation of the SE-EOM, a charging unit, a handle attached to it and a cranking system provided onto the handle allow the operator to drive the MCCB from ON to OFF positions and a manual OFF button allows discharging the energized spring through various linkages mechanically connected. In automatic operation of the SE-EOM, the motor charges the spring and drives the MCCB from ON to OFF positions and a solenoid input from remote location discharges the energized spring through mechanical linkages connected below. Some of the patent publications disclosing the SE-EOM are described below.

In U.S. Patent 6130392, disclosed is a stored energy circuit breaker operator for association with an operating handle of a circuit breaker contains springs that store energy when charged and that release energy when discharged. Energy is stored when a movement translation assembly is moved in a charging direction by an operator gear and stored energy is released when a release apparatus releases the operator gear, causing the movement translation assembly to move in a discharging direction. The circuit breaker operating handle is moved to ON position by the charging movement of the movement translation assembly and as stored energy is released, the discharging movement of the translation assembly moves the operating handle to OFF position. The operator gear is operated via an operator handle, an operator shaft and a pinion gear assembly. The pinion gear assembly has a carrier pivotally associated with the operator shaft and a pinion gear that rotates the operator gear. The operator gear may also be turned by an electric motor and series of gears to accomplish electric operation of the circuit breaker.

Similarly, U.S. Patent 6166343 discloses a unidirectional clutch assembly for use with an operator handle, a pinion shaft assembly, a worm gear assembly and a pinion gear assembly of a stored energy assembly for use with a circuit breaker assembly. The operator handle and pinion shaft assembly include an operator handle having an outer handle hub having a first recess for receiving a first end of the pinion shaft assembly, the worm gear assembly fitting over the pinion shaft assembly and the pinion shaft assembly having a second end for receiving a pinion gear assembly. The unidirectional clutch assembly comprises a first unidirectional clutch structure, wherein the first unidirectional clutch structure fits over the first end of the pinion shaft and the unidirectional clutch structure is fitted into the first recess of the outer handle hub and a second unidirectional clutch structure, wherein the second unidirectional clutch structure fits within the worm gear assembly and over the pinion shaft assembly between the first and second ends of the pinion shaft assembly, wherein the first unidirectional clutch structure and said second unidirectional clutch structure are oriented in the same direction so that they slip unidirectionally in the same direction.

Also, in another U.S. Patent 6192718 it is disclosed that a key lock and locking hasp assembly is used for a stored energy circuit breaker operator assembly. It is provided with an electrical control module for use with a stored energy circuit breaker assembly having a motor for use with a circuit breaker assembly. The circuit breaker assembly provides an electrical signal through electrical contacts for actuating the circuit breaker assembly. The electrical control module comprises a rectifying circuit which receives and rectifies said electrical signal so as to provide a rectified electrical signal, a motor switch circuit connected to the motor, and an electrical signal flow maintenance circuit which is operatively connected to said rectifying circuit, said motor switch circuit and the motor, wherein said electrical signal flow circuit maintenance maintains at least a threshold rectified electrical when the electrical contacts are closed so that said motor switch circuit is on and the motor operates.

Another U.S. Patent 4042896 discloses a manual and motor operated circuit breaker. It is provided with a circuit function which is adapted for either manual or motor driven operation, as desired. Motor driven operation is achieved by the incorporation of a power unit comprising a motor selectively drivingly coupled to the circuit breaker operating mechanism and operating to charge the mechanism spring incident to closing the breaker contacts. Upon completion of a charging function, a closing solenoid is energized to effect release of the stored energy, which powers the breaker contacts to their closed position. Control elements sensitive to the condition of the operating mechanism and the position of the breaker movable contacts function to appropriately condition switching logic in the motor and closing solenoid circuit for sequencing the charging and closing functions in a reliable manner. The control elements further function to selectively position indicator means effective to visually identify the various breaker conditions.

In current scenario, inventions in the art uses portion of stored energy to close the circuit breaker. Thus, energy is wasted in overcoming resistance introduced by components used in the charging systems. Further, if the charging system is manually operated, it can be interrupted or overrun when the charging system is engaged during manual operation of manual charging system. Yet in another scenario, some of the inventions use two springs of different stiffness for charging and discharging mechanism in motor operating system for circuit breaker switching operation.

Accordingly, there is a need to provide a stored energy motor operating mechanism that is capable of operating primarily circuit breakers with a rotary arrangement of operation.

Objects of the invention

An object of the present invention is to provide 90 degree transfer of a rotary motion without the essential use of bevel gearing to ensure operation of a rotary molded case circuit breaker.

Another object of the present invention is to have a multi level rack that ensures transfer of the rotary motion at 90 degree.

Summary of the invention

Accordingly, the present invention provides a stored energy motor operating mechanism for a rotary molded case circuit breaker. The stored energy motor operating mechanism is fixed on a top surface of the rotary molded case circuit breaker device. The stored energy operating mechanism comprises a base, a motor, a drive shaft, a first pinion, a second pinion, a multi level rack, a spring, a pair of support plates, a d-shaft assembly, a solenoid and a latching arrangement. The stored energy operating mechanism is connected to the rotary molded case circuit breaker through the second pinion.

The base includes a plurality of recesses configured thereon. The base houses a pair of support plates therein. The pair of support plates holds the d-shaft assembly and the solenoid. The motor generates a bidirectional rotary motion. The drive shaft receives the bidirectional rotary motion from the motor through a gear train. The first pinion is mounted on the drive shaft. The spring is capable of undergoing compression and expansion during switching ON/OFF condition of the rotary molded case circuit breaker. The latching arrangement comprises a cam mounted on the drive shaft and a latch being maintained in position by the d-shaft assembly.

The multi level rack is operably connected to the latching arrangement at one end and is operably connected to the first pinion at another end. The second pinion at one end meshes with the multi level rack and at another end is coupled to a knob of the rotary molded case circuit breaker causing switching ON and OFF operation thereof.

The multi level rack comprises a first projection and a second projection. The first projection includes a first set of plurality of tooth configured on an end thereof. The second projection includes a second set of plurality of tooth configured on an end thereof.
The first set of plurality of tooth gets coupled with the first pinion for converting the bidirectional rotary motion of the motor into a linear motion. The second set of plurality of tooth meshes with the second pinion for converting the linear motion into the rotary motion. The first set of plurality of tooth and the second set of plurality of tooth are in mutually perpendicular direction and ensure transfer of the rotary motion at 90 degree.

Brief description of the drawings

Other features as well as the advantages of the invention will be clear from the following description.

In the appended drawings:

Figure 1 shows a perspective view of a stored energy motor operating mechanism for a rotary molded case circuit breaker, in accordance with the present invention;

Figure 2 is a perspective view of the stored energy operating mechanism of figure 1 showing various components;

Figure 3 shows a perspective view of a latching arrangement, in accordance with the present invention;

Figure 4 shows a perspective view of a multi level rack, in accordance with the present invention;

Figure 5 shows a perspective view of transfer of a rotary motion, in accordance with the present invention;

Figure 6 shows a front view of a charged spring and a latching at a d-shaft assembly to store energy, in accordance with the present invention, and
Figure 7 shows a front view of a discharged spring and an open latch condition, in accordance with the present invention.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides a stored energy motor operating mechanism (hereinafter “the operating mechanism”) for switching device operations. The operating mechanism is capable of operating primarily circuit breakers with a rotary arrangement of operation. The operating mechanism drives the circuit breaker to one of ON, OFF or RESET state externally or remotely. The operating mechanism comprises a multi level rack that ensures transfer of the rotary motion at 90 degree.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring to figures 1-7, a stored energy motor operating mechanism (150) (hereinafter “the operating mechanism (150)”) for a rotary molded case circuit breaker, in accordance with the present invention is shown. Specifically, figure 1 shows the operating mechanism (150) fixed on a top surface (not numbered) of the rotary molded case circuit breaker (not numbered) by means of four screws (not shown).

The operating mechanism (150) comprises a base (10), a motor (20), a drive shaft (30), a first pinion (40), a second pinion (50), a multi level rack (60), a spring (70), a pair of support plates (80), a d-shaft assembly (90), a solenoid (100) and a latching arrangement (not numbered).

The base (10) comprises a plurality of recesses (not shown) configured thereon. The plurality of recesses facilitates wire routing. The base (10) houses the pair of support plates (80) therein. The pair of support plates (80) holds the d-shaft assembly (90) and the solenoid (100). The base (10) is adapted to take care of most of the electrical systems. The base (10) channelizes an incoming power supply through a logic circuit (not shown) to various electrical components including safety devices.

At the time of charging, power is supplied to the motor (20) that is coupled by a pinion to a gear train (15). In an embodiment, the motor (20) is a primary mover and generates a bidirectional rotary motion that aids to higher mechanical efficiency. The rotational energy generated by the motor (20) is then transmitted to the drive shaft (30) through the gear train (15). The gear train (15) facilitates increase of the torque by reducing the speed. Once the required torque is achieved by reducing the speed of the motor (20), the drive shaft (30) further drives the first pinion (40) to mesh with a first set of plurality tooth (52) of the multi level rack (60).

The first pinion (40) is fixed on the drive shaft (30). The motor (20) transfers power through the gear train (15) that further reduces the speed and continuously increases the torque. This increased torque is further transmitted to the first pinion (40).

The base (10) acts as a guide for the motion of the multi level rack (60). The multi level rack (60) is operably connected to the latching arrangement at one end (not numbered) and is operably connected to the first pinion (40) at another end (not numbered).

The multi level rack (60) comprises a first projection (not numbered) and a second projection (not numbered). The first projection includes the first set of plurality of tooth (52) configured on an end (not numbered) thereof. The second projection includes a second set of plurality of tooth (54) configured on an end (not numbered) thereof.

The plurality of tooth (52, 54) is in mutually perpendicular direction and ensures transfer of the rotary motion at 90 degree along with the charging of the spring (70). The first pinion (40) meshes with the first set of plurality of tooth (52) and converts the rotary motion into a linear motion. Simultaneously, the second set of plurality of tooth (54) meshes with the second pinion (50) and again converts the linear motion into the rotary motion to drive a knob (200) and operates the rotary molded case circuit breaker as shown in Figure 5.

The latching arrangement comprises a cam (104) and a latch (108). The cam (104) is mounted on the drive shaft (30) and stopped thereon by the latch (108). The latch (108) is maintained in a position by the d-shaft assembly (90) and is not allowed to move. This arrangement holds the drive shaft (30) and allows rotation thereof only in one direction. So, once the operating mechanism (150) is latched at the other end, the motor (20) rotates and since both the ends of the drive shaft (30) are locked, the first pinion (40) finally transmits the motion to the multi level rack (60).

The operating mechanism (150) and the rotary molded case circuit breaker are engaged/ connected through the second pinion (50). The second pinion (50) at one end (not numbered) meshes with the multi level rack (60) and at another end (not numbered) is coupled to the knob (200) of the rotary molded case circuit breaker. Thus, the movement of the second pinion (50) causes switching ON and OFF operations of the rotary molded case circuit breaker.

The spring (70) is capable of extension during switching OFF condition of the rotary molded case circuit breaker. During extension, the multi level rack (60) pulls the spring (70) so as to reach charged state. The linear movement of the multi level rack (60) causes extension of the spring (70) and storing of the energy. During an auto mode, the motor (20) charges the spring (70). While discharging physically, the spring (70) pulls the multi level rack (60). The solenoid (100) receives a pulse from the electronic system. The solenoid input from remote location also discharges the energized spring (70) through de-latching the latch (108) from the cam (104) and the d-shaft assembly (90).

The spring (70) is held in a position by combination of the cam (104) and the latch (108) and the d-shaft assembly (90). The latch (108) is maintained in the position by the d-shaft assembly (90). The cam (104) is mounted on the drive shaft (30) and has tendency to rotate back. When the cam (104) meshes with the latch (108), the d-shaft assembly (90) prevents rotation of the latch (108) and also, prevents the spring (70) from moving back.

Referring to figure 7, an opening of the latching arrangement and the switching ON condition of the rotary molded case circuit breaker is shown. The solenoid (100) receives a pulse from the electronic system and pushes the d-shaft assembly (90) causing rotation of the d-shaft assembly (90) in an anti-clockwise direction. When the d-shaft assembly (90) rotates, the latch (108) becomes free to rotate and is pushed by the cam (104). As the d-shaft assembly (90) no longer covers the latch (108), the latch (108) moves back on being pushed by the cam (104) due to release of the energy by the spring (70) that in turn causes the multi level rack (60) to move back causing rotation of the knob (200) resulting in ON condition of the rotary molded case circuit breaker.

During switching OFF condition of the rotary molded case circuit breaker, the pulse is received by the motor (20) to rotate and generate the rotary motion. The rotary motion is then transferred to the drive shaft (30) through the gear train (15). The gear train (15) increases the torque causing the first pinion (40) to rotate and mesh with the multi level rack (60). Then, the multi level rack (60) translates linearly causing extension of the spring (70) and storing of the energy that in turn causes rotation of the knob (200) resulting in OFF condition of the rotary molded case circuit breaker.

Advantages of the invention

1. The operating mechanism (150) is capable of operating primarily circuit breakers with a rotary arrangement of operation.
2. The operating mechanism (150) ensures 90 degree transfer of the rotary motion without the essential use of bevel gearing and also, ensures operation of the rotary molded case circuit breaker.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.

,CLAIMS:We Claim:

1. A stored energy motor operating mechanism (150) for a rotary molded case circuit breaker, the stored energy motor operating mechanism (150) being fixed on a top surface of the rotary molded case circuit breaker, the stored energy operating mechanism (150) comprising:
a base (10) having a plurality of recesses configured thereon, the base (10) being capable of housing a pair of support plates (80) therein, the pair of support plates (80) being capable of holding a d-shaft assembly (90) and a solenoid (100); a motor (20) being capable of generating a bidirectional rotary motion; a drive shaft (30) receiving the bidirectional rotary motion from the motor (20) through a gear train (15); a first pinion (40) being mounted on the drive shaft (30); a second pinion (50); a multi level rack (60); a spring (70) being capable of undergoing extension and contraction during switching ON/OFF condition of the rotary molded case circuit breaker; and a latching arrangement having a cam (104) mounted on the drive shaft (30) and a latch (108) maintained in position by the d-shaft assembly (90),
characterized in that, the multi level rack (60) having
a first projection having a first set of plurality of tooth (52) configured on an end thereof, the first set of plurality of tooth (52) being capable of coupling with the first pinion (40) for converting the bidirectional rotary motion of the motor (20) into a linear motion, and
a second projection having a second set of plurality of tooth (54) configured on an end thereof, the second set of plurality of tooth (54) being capable of meshing with the second pinion (50) for converting the linear motion into the rotary motion,
wherein, the first set of plurality of tooth (52) and the second set of plurality of tooth (54) are in mutually perpendicular direction and ensures transfer of the rotary motion at 90 degree.

2. The stored energy motor operating mechanism (150) as claimed in claim 1 is connected to the rotary molded case circuit breaker through the second pinion (50).

3. The stored energy motor operating mechanism (150) as claimed in claim 1, wherein the multi level rack (60) is operably connected to the latching arrangement at one end and is operably connected to the first pinion (40) at another end.

4. The stored energy motor operating mechanism (150) as claimed in claim 1, wherein the second pinion (50) at one end meshes with the multi level rack (60) and at another end is coupled to a knob (200) of the rotary molded case circuit breaker causing switching ON and OFF operation thereof.