FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
Title of the invention - SELF PRESERVING ARRANGEMENT FOR
DIRECT COUPLED DUAL DRIVEN MECHANISM
2. Applicant
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L&T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
This present invention relates to an arrangement for protection from overloading of drive operators of dual driven devices utilized in switching devices and draw-out arrangements. In particular the invention relates to a clutch-less arrangement for preventing mechanical overloading of dual driven remote actuating mechanism of switching devices.
BACKGROUND AND PRIOR ART
Standard mechanisms act on a principle of single drive for a mechanism. There exist critical applications like hospital systems where in case of failure of the drive, the mechanism needs to be operated by an alternate override drive.
Such applications call for a decoupling of the primary driving drive and coupling of the backup drive by a clutch arrangement or simultaneous coupling of both drives.
If both the devices are coupled simultaneously the backup driving device has to be rated in such a way that it is not able to move the mechanism into a position from which the primary driving device is unable to drive the mechanism and vice-versa. Such an exact matching of rating is not possible if one of the driving devices is hand operated where the limiting factor is operator capacity.
If both devices are not to be coupled simultaneously, such an arrangement invariably calls for a clutch type
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interface for the coupling of the mechanism to the two different driving devices. This makes the arrangement bulky and expensive.
Therefore, there is a need for an arrangement in which two driving devices can be coupled to the mechanism simultaneously and be used to drive the mechanism independent of each other where
1) Either of these drive devices should not move the mechanism into a position such that the other driving device is rendered useless in further operations.
2) Either of these drives is not able to move the mechanism such that there is overstressing of the internal components.
Further the need to eliminate clutch arrangement arises from the need for compactness and also reduction of cost of manufacture.
A further advantage gained in a clutch-less arrangement is reduced linkages leading to better statistical reliability.
European patent 0802549A2 teaches a remote operating device for a switch and a means to operate the switch either by in built driver (motor) or externally using a hand operated tool (screw driver). But this doesn't consider the condition of locking possible by rotating the operating shaft by screw driver such that the motor is unable to unlock it or vice versa. Such a condition causes overloading of the motor as well as unnecessary overstressing of the internal components. Also drive
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inertia is a factor to be considered. If the drive inertia is high, the shaft can still end up locked in a position such that neither the primary nor the secondary drive can unlock it. The patent doesn't discuss any solution for the above problems. Present invention is directed towards addressing these issues and provide a solution such that
1) Hand operated tool or an alternate secondary drive can't move the shaft to an extent that motor (primary drive) is unable to unlock it. Also the primary drive should not move the mechanism into position from which the secondary drive or hand operated tool cannot unlock it.
2) During any operation it is not possible to operate the device such that the internal components get overstressed.
3) This is achieved without providing any additional clutch based system.
European patent 0911542A2 describes an arrangement where dual driven mechanisms (motor driven for remote operation and manual driven for local operation) are considered. This patent discusses the use of Manual operation as well as motorized operation but it doesn't consider the possibility of locking it by one of the drivers in a position such that the other is not able to overcome this locking force.
The present inventors have found that two clutch less coupling mechanism and a driven mechanism when integrated in a manner it is not possible for one set of driving device to drive the mechanism into a position from which
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the alternate driving device cannot drive the mechanism thereby rendering the second driving device useless and protects the mechanism from excessive travel.
OBJECTS OF INVENTION
Thus one object of the present invention is to overcome the disadvantages as discussed above.
Another object of the present invention is to provide a clutch-less arrangement for preventing mechanical overloading of dual driven remote actuating mechanism of switching devices.
Yet another object of the present invention is to provide a clutch less arrangement to protect mechanism of switching device from excessive travel and related stresses.
SUMMARY OF INVENTION
Thus according to the basic aspect of the present invention there is provided a clutch less arrangement for preventing mechanical overloading of dual driven remote actuating mechanism of switching devices, said arrangement comprising :
housing;
driving mechanism operatively coupled to a gear system located on a shaft means wherein said shaft means being journalled in holes provided in the housing, said shaft
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allowed to rotate in clockwise or anticlockwise direction;
actuator assembly being operatively fixed with a holding means wherein said holding means being located on the shaft means so as to execute predetermined travel on the shaft means;
wherein said shaft means being designed in a manner to provide the holding means and thereby the actuator assembly with co-operative movements in a predetermined direction thus enabling toggling operation; and
plurality of biasing means operatively located on the shaft adapted to ensure that the holding means execute travel in a predetermined reverse direction.
According to another aspect of the present invention there us provided a clutch less arrangement for preventing mechanical overloading of dual driven remote actuating mechanism of switching devices, said arrangement comprising :
housing;
driving mechanism operatively coupled to a gear system located on a shaft means wherein said shaft means being journalled in holes provided in the housing, said shaft allowed to rotate in clockwise or anticlockwise direction and being extended to meet a manually operated means adapted to choose direction of rotation of the shaft;
actuator assembly being operatively fixed with a holding means wherein said holding means being located on the
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shaft means so as to execute predetermined travel on the shaft means;
wherein said shaft means being designed in a manner to provide the holding means and thereby the actuator assembly with co-operative movements in a predetermined direction thus enabling toggling operation; and
plurality of biasing means operatively located on the shaft adapted to ensure that the holding means execute travel in a predetermined reverse direction.
DETAILED DESCRIPTION OF INVENTION
In the present invention the primary driving mechanism is a motor which is permanently coupled by gear system to the shaft means (hereinafter referred to a shaft) with threads located in the housing for the mechanism such that it can only rotate in its place. All the linear degrees of freedom are constrained.
The assembly of gear and shaft is held together in the housing. The shaft is located in two holes of the housing by means of bearings on both ends so that it is free to rotate.
The gear is operatively engaged with the gear teeth of the motor, which when given a supply such that it rotates in clockwise direction, the shaft rotates in an anticlockwise direction due to the gear coupling. The same is true for anticlockwise rotation of motor assembly and here the shaft rotates in the clockwise direction.
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The extended end of the shaft comprises manual operating handle. Thus both clockwise and anticlockwise operations can be achieved by operating the mechanism with the manual operating handle also.
The holding means comprises a nut operatively engaged on the shaft portion having threaded design. The nut holds the actuator assembly such that the rotation of the shaft causes the nut to be moved along the length of the shaft and the actuator assembly moves along with the nut parallel to the length of the shaft. Clockwise or counter clockwise rotation of the shaft achieves bi-directional travel of the nut and actuator assembly.
The threaded length of the shaft is limited only to the extent of the travel of the nut required for the actuator to complete its intended travel. Thereafter the shaft diameter is reduced to a diameter less than the diameter of the nut threads to generate clearance between shaft and nut so that the nut after completing the intended travel will slip off the threads and not engage in them unless the shaft is rotated in the opposite direction.
The actuator comprises of a slot for accommodating nut engaged with the threaded shaft. When the shaft is rotated in one direction either by the manual operating handle or by the motor assembly, the nut covers a linear path along the shaft.
This causes the knob actuator assembly to move from one end of the housing to the other. Rotation of the shaft in opposite direction causes the knob actuator assembly to retrace its path in the housing. Thus the Knob actuator assembly can trace a linear path derived from the rotation of the shaft. This linear motion of the knob
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actuator can be used to perform the duty of switching 'ON' and switching 'OFF' a toggle operated device.
The shaft has threads up to a limited length and the nut can disengage from these threads so that the travel of the knob actuator is limited to the travel required for operating the toggle operated device.
Further rotation of shaft in the same direction, which otherwise would have caused locking or overstressing of the internal components, will now cause the nut to disengage form the threads thereby not transferring any displacement onto the nut. Thus the components are protected from overstressing.
If the mounting of the device is such that the nut after disengaging from the threads of shaft will always tend to engage with those threads once the shaft is rotated in the opposite direction only then can this arrangement work for complete cycle of operation for switching X0N' and 'OFF' the toggle operated device.
Plurality of biasing means comprising of springs is provided on either side of the actuator assembly in which the nut is located to ensure that the nut engages with the threads of the shaft once the shaft is rotated in the opposite direction. The springs may be selected from compression spring, extension spring and the like. However, the springs described above do not restrict the scope of the invention.
The springs do the function of biasing the assembly of knob actuator with the nut to move in the desired direction on reversal of rotation of shaft. Thus the assembly is not dependant on gravity for achieving its purpose. Hence the device is not constrained in its
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mounting in any specific orientation and the site requirements can be easily met by mounting the device in required orientation.
Thus when the motor is used to operate the device, it can
take the knob actuator assembly to either end of the
desired travel. If the motor continues to run after the
travel is achieved, then also the knob actuator will not
be displaced any further as the shaft and nut are now
disengaged from each other.
Also when the manual operating handle is to be used for the rotation of the shaft, by the same principle the handle cannot displace the nut to an extent as to cause overstressing or locking of the mechanism components.
Thus the present invention allows the mechanism to achieve the required travel of the actuating device and at the same time protects the mechanism from excessive travel by the nut on the threads of the shaft in either direction.
Another Deviation of the same is the replacement of the hand operated tool by means of a secondary drive mechanism in which, the extended end of the shaft has a gear mounted on it and a cooperatively coupled gear system is mounted such that the torque of the secondary drive is also transferred to the shaft thus providing for a primary and backup drive assembly.
BRIEF DESCRIPTION OF ACCOMPANYING FIGURES
Figure 1 illustrates a plan view of the complete arrangement of the present invention.
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Figure 2 illustrates an exploded view of the arrangement of the present invention.
DETAILED DESCRIPTION OF ACCOMPANYING FIGURES
In figures 1 and 2 the plan and exploded views of the arrangement of the present invention is illustrated. The gear (4) and shaft (6) is held together in the housing (7) . Shaft (6) is located in two holes of the housing (7) by means of bearings on both ends so that it is free to rotate.
Gear (4) is engaged with the gear teeth of the motor (3). When the motor (3) is given a supply such that it rotates in clockwise direction, the shaft (6) rotates in an anticlockwise direction due to the gear coupling (4).
The shaft (6) is extended outside the housing (7) and comprises manual operating handle (5).
Nut (2) is located in the rectangular slot provided in the knob actuator (1) and is engaged with shaft (6).
Shaft (6) comprises springs (8) and (9) which bias actuator (1) with nut (2) to move in the desired direction on reversal of rotation of shaft (6).
The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. The springs as herein described do not limit the scope of the present invention. The handle for manually rotating the shaft can be replaced by its technical equivalence and yet the
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invention can be performed. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.
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WE CLAIM
1. A clutch less arrangement for preventing mechanical
overloading of dual driven remote actuating
mechanism of switching devices, said arrangement
comprising :
housing;
driving mechanism operatively coupled to a gear system located on a shaft means wherein said shaft means being journalled in holes provided in the housing, said shaft allowed to rotate in clockwise or anticlockwise direction;
actuator assembly being operatively fixed with a holding means wherein said holding means being located on the shaft means so as to execute predetermined travel on the shaft means;
wherein said shaft means being designed in a manner to provide the holding means and thereby the actuator assembly with co-operative movements in a predetermined direction thus enhancing toggling operation; and
plurality of biasing means operatively located on the shaft adapted to ensure that the holding means execute travel in a predetermined reverse direction.
2. A clutch less arrangement for preventing mechanical
overloading of dual driven remote actuating
mechanism of switching devices, said arrangement
comprising :
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housing;
driving mechanism operatively coupled to a gear system located on a shaft means wherein said shaft means being journalled in holes provided in the housing, said shaft allowed to rotate in clockwise or anticlockwise direction and being extended to meet a manually operated means adapted to choose direction of rotation of the shaft;
actuator assembly being operatively fixed with a holding means wherein said holding means being located on the shaft means so as to execute predetermined travel on the shaft means;
wherein said shaft means being designed in a manner to provide the holding means and thereby the actuator assembly with co-operative movements in a predetermined direction thus enhancing toggling operation; and
plurality of biasing means operatively located on the shaft adapted to ensure that the holding means execute travel in a predetermined reverse direction.
Arrangement as claimed in claims 1 and 2, wherein the shaft comprises threaded portion extending to predetermined length such that it is limited only to the extent of the travel of the holding means so as to perform toggling operation.
Arrangement as claimed in claims 1 to 3, wherein the shaft comprises diameter of multiple dimensions adapted to generate clearance between shaft and
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holding means such that the holding means after completion of intended travel slips off the threaded portion and not engages in them unless the shaft is rotated in the reverse direction.
Arrangement as claimed in claim 4, wherein the shaft diameter being such that during over travel of the motor the knob actuator is restricted from operation.
Arrangement as claimed in claims 1 to 5, wherein the holding means comprises nut.
Arrangement as claimed in claims 1 to 6, wherein the biasing means comprise springs adapted to move the nut and the actuator in the desired direction independent of gravity not constraining in its mounting in any specific orientation.
Arrangement as claimed in claim 2, wherein the manual operating means comprises handle adapted to change rotation direction of the shaft manually.
A clutch less arrangement as herein substantially described and illustrated with reference to the accompanying figures.
d this 13th day of October, 2006.
Ashwini Sandu Of S. Majumdar & Co. Applicant's Agent
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ABSTRACT
TITLE : SELF PRESERVING ARRANGEMENT FOR DIRECT COUPLED DUAL DRIVEN MECHANISM
The present invention relates to a clutch less arrangement for preventing mechanical overloading of dual driven remote actuating mechanism of switching devices. The arrangement comprises housing (7), driving mechanism operatively coupled to a gear system (4) located on a shaft means (6) . Shaft means (6) is journalled in holes provided in the housing (7) and allowed to rotate in clockwise or anticlockwise direction. Actuator assembly (1) is operatively fixed with a holding means (2) wherein said holding means (2) being located on the shaft means (6) so as to execute predetermined travel on the shaft means (6) wherein said shaft means (6) being designed in a manner to provide the holding means (6) and thereby the actuator assembly (1) with co-operative movements in a predetermined direction thus enabling toggling operation. Plurality of biasing means (8,9) operatively located on the shaft adapted to ensure that the holding means (2) execute travel in a predetermined reverse direction.
Figure 1