DESC:Stored Energy Motor Operating Mechanism

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 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 of a stored energy motor operating mechanism that is capable of operating circuit breakers to provide reliable latching for next charging operation.

Objects of the invention

An object of the present invention is to provide a reliable latching for next charging operation of a switching device.

Another object of the present invention is to provide a cam ratchet that acts as a natural retarder to the switching device so that an excess energy is used in collisions between a latch and the cam ratchet to facilitate dissipation of the energy.

Summary of the invention
Accordingly, the present invention provides a stored energy motor operating mechanism. The stored energy operating mechanism comprises a motor, a drive shaft, a pinion, a gearing system, a rack, a spring, a pair of support plates, a d-shaft assembly, a solenoid, a latching arrangement and a toggle switch. The stored energy operating mechanism is connected to a switching device through the pinion. The gearing system includes a first intermediate gear, a second intermediate gear, a sun gear/gear train and a pawl.

The pair of support plates holds the d-shaft assembly and the solenoid. The motor is positioned on the pair of support plates. The motor generates a bidirectional rotary motion. The drive shaft receives the bidirectional rotary motion from the motor. The pinion meshes with the rack. The spring undergoes extension and contraction during switching ON/OFF condition of the switching device. The latching arrangement comprises a cam ratchet mounted on the drive shaft and a latch maintained in position by the d-shaft assembly. The cam ratchet is designed in such a way to include twelve surfaces at periphery thereof thereby providing twelve surfaces of locking for the latch. During switching ON condition of the switching device, after the spring gets discharged to dissipate the energy and comes to rest, the cam ratchet gets released and constantly hits the latch to lose the excess energy in collision and thus, acting as a dampener. The toggle switch transfers an incoming power alternatively to the motor while switching OFF and to the solenoid while switching ON the switching device

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 front perspective view of a stored energy motor operating mechanism, in accordance with the present invention;

Figure 2 shows a back perspective view of the stored energy motor operating mechanism of figure 1;

Figure 3 is a perspective view of the stored energy motor operating mechanism showing various components; and

Figure 4 shows a perspective view of a delatching operation, 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. The operating mechanism drives the circuit breaker to one of ON, OFF or RESET state externally or remotely.

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 1-4, a stored energy motor operating mechanism (150) (hereinafter “the operating mechanism (150)”) for a switching device operation in accordance with the present invention is shown. In an embodiment, the switching device is a circuit breaker and more particularly, a molded case circuit breaker (hereinafter “the MCCB”).

The operating mechanism (150) comprises a motor (10), a drive shaft (20), a pinion (30), a gearing system (50), a rack (60), a spring (70), a pair of support plates (80), a d-shaft assembly (90), a solenoid (100), a latching arrangement (not numbered) and a toggle switch (120).

The pair of support plates (80) holds the d-shaft assembly (90) and the solenoid (100). The motor is positioned on the pair of support plates (80). The gearing system (50) starts from a small gear (not numbered) fixed on the motor (10). The gearing system (50) includes a first intermediate gear (34), a second intermediate gear (38), a sun gear/gear train (42) and a pawl (46). The pawl (44) helps in transferring the power.

At the time of charging, power is supplied to the motor (10). In an embodiment, the motor (10) is a primary mover and generates a bidirectional rotary motion that aids to higher mechanical efficiency. The rotational energy generated by the motor (10) is then transmitted to the drive shaft (20) through the intermediate gears (34, 38) which mesh with the sun gear/gear train (42) (hereinafter “the gear train (42)”) and basically reduce RPM and increase torque. Once the required torque is achieved by reducing the speed of the motor (10), the drive shaft (20) further drives the pinion (30) to mesh with the rack (60). The pinion (30) then transfers this energy to epicyclic gears (not shown) through a series of two gears (not shown). This reduced torque is further transmitted through an internal gear (not shown) to the pinion (30).

The rotary motion of the motor (10) is converted to a linear motion by the rack (60) and the pinion (30). The operating mechanism (150) is connected/engaged to the switching device through the pinion (30) and hence, the movement of the pinion (30) causes switching ON and OFF operations of the switching device.

The latching arrangement comprises a cam ratchet/reverse ratchet (104) (hereinafter “the cam ratchet (104)”) and a latch (108). The cam ratchet (104) is mounted on the drive shaft (20) 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 (20) and allows rotation thereof only in one direction. So, once the operating mechanism (150) is latched at the other end, the motor (10) rotates and since both the ends of the drive shaft (20) are locked, the pinion (30) finally transmits the motion to the rack (60).

The arrangement of the cam ratchet (104) and the latch (108) ensures that the operating mechanism (150) latches for the next operation of the switching device without being suspended in an intermediate state. The cam ratchet (104) is designed in such a way to include twelve surfaces (not numbered) at periphery (not numbered) thereof thereby providing twelve surfaces of locking for the latch (108). During switching ON condition of the switching device, after the spring (70) gets discharged to dissipate the energy and comes to rest, the cam ratchet (104) gets released and constantly hits the latch (3) thereby losing an excess energy in collision and thus, acting as a dampener.

The spring (70) is capable of undergoing extension/contraction during switching ON/OFF condition of the switching device. During extension, the rack (60) pulls the spring (70). The linear movement of the rack (60) causes extension of the spring (70) and energy storage. During an auto mode, the motor (10) charges the spring (70). While discharging physically, the solenoid (100) receives a pulse from the electronic system. The solenoid input from a remote location also discharges the energized spring (70) through a mechanical linkage (not numbered) of the d-shaft assembly (90), the cam ratchet (104) and the latch (108).

The spring (70) is held in a position by combination of the cam ratchet (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 ratchet (104) is mounted on the drive shaft (30) and has tendency to rotate back. When the cam ratchet (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. The toggle switch (120) helps in transferring an incoming power alternatively to the motor (10) while switching OFF and to the solenoid (100) while switching ON the switching device.

Referring to figure 4, an opening of the latching arrangement and the switching ON condition of the switching device is shown. The solenoid (100) receives a pulse from the electronic system and pushes a plate (85) on 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 ratchet (104). As the d-shaft assembly (90) no longer covers the latch (108), the latch (108) moves back on being pushed by the cam ratchet (104) due to release of the energy by the spring (70) that in turn causes the rack (60) to move back taking along the knob (200) and resulting in ON condition of the switching device.

During switching OFF condition of the switching device, the pulse is not received by the solenoid (100) causing the motor (10) to rotate and generate the rotary motion. The rotary motion is then transferred to the drive shaft (20) through the intermediate gears (54, 58) that mesh with the gear train (42). The gear train (42) increases the torque causing the pinion (30) to rotate and mesh with the rack (60). Then, the rack (60) rotates linearly causing extension of the spring (70) and energy storage that in turn results in switching OFF of the switching device.
Advantages of the invention

1. The cam ratchet (104) provides reliable latching for next charging operation of the switching device.
2. The cam ratchet (104) acts as a natural retarder to the switching device, so that the excess energy is used in collisions between the cam ratchet (104) and the latch (108) to facilitate dissipation of the energy.

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) comprising:
a pair of support plates (80) being capable of holding a d-shaft assembly (90) and a solenoid (100); a motor (10) positioned on the pair of support plates (80), the motor (10) being capable of generating a bidirectional rotary motion; a drive shaft (20) receiving the bidirectional rotary motion from the motor (10); a gearing system (50) having a first intermediate gear (34), a second intermediate gear (38), a sun gear/gear train (42) and a pawl (46); a pinion (30) being capable of meshing with a rack (60); a spring (70) being capable of undergoing extension and contraction during switching ON/OFF condition of a switching device; a latching arrangement having a cam ratchet (104) mounted on the drive shaft (20) and a latch (108) maintained in position by the d-shaft assembly (90); and a toggle switch (120) transferring an incoming power alternatively to the motor (10) while switching OFF and to the solenoid (100) while switching ON the switching device,
characterized in that, the cam ratchet (104) is designed in such a way to include twelve surfaces at periphery thereof thereby providing twelve surfaces of locking for the latch (104),
wherein, during switching ON condition of the switching device, after the spring (70) gets discharged to dissipate the energy and comes to rest, the cam ratchet (104) gets released and constantly hits the latch (108) thereby losing an excess energy in collision and thus, acting as a dampener.

2. The stored energy motor operating mechanism (150) as claimed in claim 1 is connected to the switching device through the pinion (30).