Claims:1. A self-returning gear assembly, comprising:
a torsion spring held in a fixed support, wherein extended arms (10, 11) of the torsion spring movably held by locking means provided with the fixed support;
a gear having a slot arrangement (3) at its center and C-shaped longitudinal projection at its bottom surface with edges (1, 2) adapted to drive the torsion spring, when said gear is rotated in either direction from a neutral position through an external electrically operated means, wherein the torsion enables automatic returning of the gear to the neutral position;
an output shaft passing through the gear and capable of being rotated in either direction from a neutral position during a manual operation or when rotated by the gear.
2. The assembly as claimed in claim 1, wherein the fixed support acts as a fixed member adapted to provide axial reference to the gear, the output shaft and the torsion spring.

3. The assembly as claimed in claim 2, wherein the torsion spring is held in a circular space (8) provided in the fixed support.

4. The assembly as claimed in claim 3, wherein the gear rests on the fixed support with the C shaped longitudinal projection facing downward.

5. The assembly as claimed in claim 4, wherein the output shaft comprises two flat surfaces (4), a round base (5) and a square sectioned projection (6).

6. The assembly as claimed in claim 5, wherein the flat surfaces (4) adapted to provide positive engagement with the slot arrangement (3) provided at the center of the gear.

7. The assembly as claimed in claim 6, wherein the round base (5) acts as a support and axial reference for the shaft; and the square sectioned projection (6) can be used to connect an output.

8. The assembly as claimed in claim 1, wherein the locking means comprises small grooves (7, 9) formed at edges of a C shaped projection formed at a surface of the fixed support.

9. The assembly as claimed in any of the preceding claim, wherein the gear rotates the output shaft after having been rotated to a predefined angle of rotation.

10. The assembly as claimed in any of the preceding claim, wherein when the torsion spring is driven through the gear in one direction, one arm (10, 11) of the torsion spring moves through one of the edge (1, 2) of the C shaped projection provided at the bottom of the gear while the other arm (10, 11) is held fixed at the locking means provided with the fixed support.

11. The assembly as claimed in claim 10, wherein power stored in the torsion spring when driven by the gear, gives a torque in an opposite direction to the gear, thereby enabling automatic returning of the gear to the neutral position.

12. The assembly as claimed in any of the preceding claim, wherein construction of the slot arrangement (3) enables the rotation of the output shaft for the predefined angle in either direction from the neutral position independent of the gear during the manual operation through the output shaft.
, Description:TECHNICAL FIELD OF THE INVENTION

[001] The present subject matter described herein, in general, relates to a gear system. More particularly, the invention relates to a gear system which rotates from one position to other and then returns back to its original position without any external drive and the system enables the reversal in both the directions - clockwise and anticlockwise. Such mechanisms can be used in Electrical Operating Mechanism for switchgears such as Changeover Switch, MCCB and the like, where there is need to achieve a power driven operation and also a manual operation.

BACKGROUND OF THE INVENTION

[002] Gear is a toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion or change the torque. Wherein torque is a twisting moment created about the axis of an object by the force delivered at a distance from the center of axis. Gears are one of the essential parts used in various drive trains. In switchgears, they form an integral part in various products that require motion or force transfers. Gears are entities that obtain the rotary input from one side and transfer it to another side. Based on its design aspects, torque output of the gear increases or decreases with respect to the input. Spur gears are the widely used type of gear, used to transfer rotary output where the transfer of torque is between axes which are parallel to each other. Spur gears can rotate in clockwise direction as well as in anticlockwise direction. Also, spur gears can be used as drivers and it can also be driven.

[003] General purpose gear trains have rotation of gears in one or both directions of rotation continuously or intermittently. When stopped and restarted the gear starts rotating from the same position as it was left stationary. An idle or neutral position and reversal to such position after achieving the required momentum or drive is not widely used unless otherwise called for. Applications which require such reversal also use power or driver which was primarily used for the forward motion to get back to the intended neutral/idle position. Output shaft connected to the gear train follows its rotational movement and retains the position as per the gear. A torsion spring is a spring that works by torsion or twisting. It is a flexible elastic object that stores mechanical energy when it is twisted. A torsion spring can be used for the reversal of gear to an intended neutral position.
[004] For existing patents related to the automatic reversal of gear in a gear assembly, reference is made to US3739944, entitled “Automatic periodically actuated spray dispenser”. The prior art relates to a spray dispenser which is actuated by a cam driven by a gear train and motor. The actuation occurs through the power delivered by the motor through the gear train while the returning action is achieved by the inherent return spring force of the valve in spray container. The return action is linear which gets converted to rotary motion through the cam attached to the gear. The actuation cycle occurs vice versa.
[005] Reference is further made to US3957562, entitled “Apparatus for printing and applying pressure sensitive labels”. This prior art document relates to a label printing and application system which has an actuator connected to set of gears. When the actuator is pushed manually by the user, the gears connected provides a rotary motion in a particular direction of rotation. The actuator is connected to a spring assembly which provides the reverse movement of actuator and its associated gears (in opposite direction) upon releasing the actuator.
[006] Reference is also made to US 5048151, entitled “Mechanical door check”. The prior art relates to an automatic door closing mechanism wherein a coil spring is used to push the door back to its closed position through a set of gears. It also has a transmission clutch to brake the mechanism during closing operation. The spring gets charged during the opening of door and discharges to close the door.
[007] Reference is made to US 6276664, entitled “Worm driving a servo actuator with spring return and rotary valve employing same”. This prior art document describes a rotary valve operating mechanism wherein a motor connected to a gear train with worm gear is used to operate the closing/opening of the valve. It also houses a torsion spring connected to the said worm gear that stores energy while the motor operated the valve through the gear train. In case of power failure or intentional de-energization of motor, the spring has energy sufficient to return the valve to its initial position.
[008] Reference is even made to EP0882299B1, entitled “Operating device for electric switching device”. The prior art document discloses an operating device for operation of an electric switching device, comprising a drive device and a carrier, which includes a driving part (5, 9)and a driven part (7), whereby the drive device, via the driving part transmits a movement to the driven part, which is in mechanical connection with the electric switching device, characterized in that the driving part comprises an initial position, from which the driving part is moveable in a first direction and in a second direction, and that between the driving part and the driven part the operating device comprises a play, which enables the driving part to return to the initial position after a completed operation, thus enabling a manual operation of the operating device.
[009] Reference is further made to US4205783A, entitled “Independent biasing means for automatic flue damper”. In this prior art document for a vent or flue damper of the type in which the damper is closed by an electrically energized actuator when the furnace is off and the actuator has first biasing means to open the damper when the actuator is deenergized, a second biasing means such as a torsion spring, independent of the first biasing means, is associated directly with the damper shaft and is adapted to always move the damper to an open position in the absence of the actuator.
[0010] However, the existing technologies have the following drawbacks, which has been addressed by the present invention:
• The gear train or the gear connected to the operating/output shaft tends to rotate or driven whenever the shaft is rotated through an external means. Independency is not achieved as both shaft and gear are connected from the driving stage.
• Reversal of the gear requires power from the drive train and the precision of idle/neutral position is to be attained through position sensors or locators.
[0011] Accordingly, there exists a dire need to focus on a gear system which rotates from one position to another and then returns back to its original position without any external drive. The system enables the reversal in both the directions - clockwise and anticlockwise. The angle of rotation in one direction and its reversal can be controlled through its construction. A shaft connected to such gear can be constructed such that it is independent of the connected gear post the reversal of the gear to its neutral position. i.e., the shaft can be rotated separately without rotating the gear for a predefined angle.

SUMMARY OF THE INVENTION

[0012] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[0013] An objective of the present invention is to provide a self-returning gear system wherein reversal of gear to an idle/neutral position can be achieved through an automated spring based mechanism.

[0014] Another objective of the present invention is to achieve an independency of the output shaft with the gear for predefined angle post every operation i.e. independent operation of shaft through an external means is always possible for a predefined angle.

[0015] Another objective of the present invention is to avoid increase in driving torque by automatically disengaging the gear train connected to output shaft post the driving operation.

[0016] Accordingly, in one aspect, the present invention discloses a self-returning gear assembly, comprising:
a torsion spring held in a fixed support, wherein extended arms (10, 11) of the torsion spring movably held by locking means provided with the fixed support;
a gear having a slot arrangement (3) at its center and C-shaped longitudinal projection at its bottom surface with edges (1, 2) adapted to drive the torsion spring, when said gear is rotated in either direction from a neutral position through an external electrically operated means, wherein the torsion enables automatic returning of the gear to the neutral position.
an output shaft passing through the gear and capable of being rotated in either direction from a neutral position during a manual operation or when rotated by the gear.
[0017] In one embodiment of the first aspect, the fixed support acts as a fixed member and provides axial reference to the gear, the output shaft and the torsion spring.

[0018] In one embodiment of the first aspect, the torsion spring is held in a circular space (8) provided in the fixed support.

[0019] In one embodiment of the first aspect, the gear rests on the fixed support with the C shaped longitudinal projection facing downward.

[0020] In one embodiment of the first aspect, the output shaft comprises two flat surfaces (4), a round base (5) and a square sectioned projection (6).

[0021] In one embodiment of the first aspect, the flat surfaces (4) provide positive engagement with the slot arrangement (3) provided at the center of the gear.

[0022] In one embodiment of the first aspect, the round base (5) acts as a support and axial reference for the shaft; and the square sectioned projection (6) can be used to connect an output.

[0023] In one embodiment of the first aspect, the locking means comprises small grooves (7, 9) formed at edges of a C shaped projection formed at a surface of the fixed support.

[0024] In one embodiment of the first aspect, the gear rotates the output shaft after having been rotated to a predefined angle of rotation.

[0025] In one embodiment of the first aspect, when the torsion spring is driven through the gear in one direction, one arm (10, 11) of the torsion spring moves through one of the edge (1, 2) of the C shaped projection provided at the bottom of the gear while the other arm (10, 11) is held fixed at the locking means provided with the fixed support.

[0026] In one embodiment of the first aspect, power stored in the torsion spring when driven by the gear, gives a torque in an opposite direction to the gear, thereby enabling automatic returning of the gear to the neutral position.

[0027] In one embodiment of the first aspect, construction of the slot arrangement (3) enables the rotation of the output shaft for the predefined angle in either direction from the neutral position independent of the gear during the manual operation through the output shaft.

[0028] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0029] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0030] Figure 1 shows the isometric views of a spur gear, according to one embodiment of the present invention.
[0031] Figure 2 shows the output shaft according to one embodiment of the present invention.
[0032] Figure 3 shows the isometric view of the fixed support, according to one embodiment of the present invention.
[0033] Figure 4 shows the torsion spring with extended arms, according to one embodiment of the present invention.
[0034] Figure 5 shows the exploded view of the self-returning gear assembly with all the components, according to one embodiment of the present invention.
[0035] Figure 6 shows the isometric views of the assembly, according to one embodiment of the present invention.
[0036] Figure 7 shows the stable condition or the neutral position of the assembly, according to one embodiment of the present invention.
[0037] Figure 8 shows the operation of the assembly in counter clockwise direction, according to one embodiment of the present invention.
[0038] Figure 9 shows the operation of the assembly in counter clockwise direction when the angle of rotation is 50°, according to one embodiment of the present invention.
[0039] Figure 10 shows the operation of the assembly in clockwise direction, according to one embodiment of the present invention.
[0040] Figure 11 shows the operation of the assembly in clockwise direction when the angle of rotation is 50°, according to one embodiment of the present invention.
[0041] Figure 12 shows the manual operation of the assembly, when the rotation of shaft is in counter clockwise direction, according to one embodiment of the present invention.
[0042] Figure 13 shows the manual operation of the assembly, when the rotation of shaft is in clockwise direction, according to one embodiment of the present invention.

[0043] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0044] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0045] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0046] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0047] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0048] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0049] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0050] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0051] In one implementation, the present invention discloses a self-returning gear assembly comprising a fixed support, a torsion spring, gear and an output shaft. The support holds the torsion spring and acts as the axial reference for the shaft and gear. The axis of rotation of all the components are in line with that of the fixed support. The torsion spring is usually loaded in one direction by moving one end or arm of the spring while the other end/arm is fixed. In this mechanism, both ends can be maintained as fixed member or moving member as per the direction of the rotation. When the gear is rotated in one direction the torsion spring is loaded till a particular angle of rotation by the gear post which the input to the gear gets cut off. Then the power stored in the torsion spring gives the torque in the opposite direction to the gear. This helps in achieving the returning action of the gear. The shaft which passes through the gear is driven by the gear when gear is rotated by external means while it is independent post the returning action is completed. This is achieved by the cut-out portion in the center of the gear which allows the operation of the shaft independent of the spur gear for the predefined angle.

[0052] In one preferred implementation, the present invention discloses the construction of the gear assembly. The essential components of this invention are:
• Gear (as shown in figure 1)
• Output Shaft (as shown in figure 2)
• Fixed support (as shown in figure 3) and
• Torsion spring (as shown in figure 4)

[0053] In the preferred exemplary implementation, the construction shown is for a spur gear system with the output shaft rotating 50° on either direction from the neutral position. The illustration shown is for an electrically operating mechanism for changeover switch-disconnector which has an OFF position at the center and ON1, ON2 positions at 50° in clockwise, anticlockwise directions respectively. In electrical/power operation, the gear is driven by a prime mover (Motor or other electromechanical system) which in turn drives the output shaft. In case of non-availability or failure of power, manual operation is used in which the shaft is driven through a handle manually by the user. The construction described herein can be modified accordingly to suit a variety of applications and the construction shown in figures 1-13 does not limit its application to this system alone.

[0054] Figure 1 shows isometric views of a spur gear with a slot arrangement (3) at the center and projections at the bottom (1 and 2) for axial reference and driving the spring. The construction of the slot arrangement (3) is based on the angle of rotation required for manual operation through the shaft. In this illustration, the angle of the rotation is considered as 50° for one direction and hence the slot has been made with an offset of 50° from the neutral position (0°) of the gear. The spur gear rests on the fixed support with the C shaped projections facing downward. The projections are used to drive the spring arm during the operation as well.

[0055] Figure 2 shows the output shaft. It has a 2 flat surfaces (4), a round base (5) and square sectioned projection (6). The flat surfaces provide positive engagement with the spur gear. The round base acts as the support and axial reference for the shaft. The square section shown for illustration can be used to connect the output.

[0056] Figure 3 shows the isometric view of the fixed support. The support acts as the fixed member providing reference to gear, shaft and spring. The spring is assembled in the circular space (8) with its arms fixed to the locking provisions (7) and (9) in the support.

[0057] Figure 4 shows the torsion spring with extended arms (10) and (11).

[0058] Figure 5 provides the exploded view of the assembly with all the components.

[0059] Figure 6 provides the isometric views of the assembly.

[0060] Figure 7 – 13 explains the operation of the assembly. Figure 7 indicates the stable condition or the neutral position of the assembly. Figure 7 further shows the arms of the spring (10) and (11) constrained with projections of support as well as gear (1), (2), (7) and (9). The edges (7) and (9) of the support are fixed while the edges (1) and (2) are movable i.e. it can rotate and charge the spring through the arms (10) and (11).

[0061] Figure 8 provides an illustration of operation in counter clockwise direction. The gear is rotated by 30° in counter clockwise direction and hence edges (1) and (2) have also rotated 30° with respect to its center while edges (7) and (9) are fixed. Rotation of edge (1) causes arm (10) to rotate while another arm of spring (11) is held by the edge of support (9) in the same position. This causes the spring to charge to certain torque in the counter clockwise direction as per the angle to which it is rotated.

[0062] Figure 9 provides the condition of further rotation in counter clockwise direction. The process as described in figure 8 continues till the condition as shown in figure 9 is attained. In this illustration, the angle of rotation is 50° in counter clockwise direction. At this instance, the gear is ready to drive the shaft through the flat surface thereby delivering the output. During this action, the spring is charged further to a higher torque. Further rotation of the gear transmits the power to the output shaft while charging of the spring continues further in parallel.

[0063] Figure 10 provides the illustration of rotation in clockwise direction. This is similar to the operation as described in figure 8 but in opposite direction. Here, rotation of edge (2) causes arm (11) to rotate while another arm of spring (10) is held by the edge of support (7) in the same position. The spring is charged to certain torque in the clockwise direction by this means.

[0064] Figure 11 provides the condition of further rotation in clockwise direction. This is similar to the operation as described in figure 9 but in opposite direction. In this illustration, the angle of rotation is 50° in clockwise direction. The gear is ready to drive the shaft through the flat surface while the spring is charged further to a higher torque similar to operation in figure 9. Further rotation of the gear transmits the power to the output shaft in clockwise direction while charging of the spring continues further in parallel.

[0065] Figure 12 and figure 13 provide the provision for manual operation. It shows the independency of the shaft with respect to the gear. The slot in the gear allows free movement of the shaft in both the directions up to 50° as the system described herein requires 50° operation. The same can be extended or modified as per the requirements of the system to which it is being applied. Figure 12 shows the rotation of shaft in counter clockwise direction while figure 13 shows the rotation in clockwise direction.

[001] Some of the noteworthy features of the present invention are as follows:
• Gear system can come back to its original position after every operation without external power/drive.
• Torsion spring being used for storing energy in both direction of rotation.
• Dependency of shaft during power operation and independency during manual operation achieved automatically without any external means.

[002] Some of the non-limiting advantages of the present invention are:
• Manual operation using the shaft becomes easy to the user as the entire effort/input is transmitted to the output and is not lost in driving the gear or the gear train (if any) connected to it.
• OFF operation is achieved at a shorter time in power operation compared to ON operation as shaft is ready to engage in ON positions.

[003] Although a self-returning gear assembly have been described in language specific to structural features, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific methods or devices described herein. Rather, the specific features are disclosed as examples of implementations of the self-returning gear assembly that can be used in Electrical Operating Mechanism for switchgears such as Changeover Switch, MCCB and the like, where there is need to achieve a power driven operation and also a manual operation.