|Title of Invention||
A VALVE GEAR BOX
|Abstract||A valve gear box comprising a worm gear unit consisting of a quadrant, a worm gear housed inside a casing; a spur gear reduction unit having a spur wheel meshing with a pinion wheel provided with a pinion shaft for engaging with the hand wheel of the said valve; characterised by the shaft of the worm gear extending outwardly, beyond the spur wheel, the hand wheel being detachable and also engageable with the extended portion of the shat of the worm gear.|
|Full Text||AUDCO INDIA LIMITED, MOUNT POONAMALLEE ROADD, N INDIAN MANAPAKKAM, CHENNAI 600 089, TAMIL NA DU,
N- THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS O TO BE PERFORMED
This Invention relates to a valve gear box.
Valve gear boxes are devices used on valves & dampers to reduce the turning effort.The standard valve gear box assembly consists of a basic worm gear assembly having a quadrant and a worm gear. The worm gear assembly with a certain gear ratio and mechanical advantage helps in reducing the turning effort required to operate the valve. Large valves with exorbitantly high turning efforts use an additional spur gear assembly on the input shaft of the basic worm gear to further multiply the mechanical advantage and thereby to reduce the turning effort required. The spur gear consists of a spur wheel and the pinion wheel. The pinion wheel is connected to a pinion shaft which receives the hand wheel used for operation of the valve. The standard worm gear box with spur unit attached will have high gear ratio calling for more number of turns required to operate for one single valve operation.
The turning effort required to open the valve will be maximum for first few degrees of opening until the port breaks open and will reduce drastically thereafter for remaining angle of opening.In the existing system of valve operation using the standard system of worm gear box with a spur unit attached, the operator turns the hand wheel to operate the valve. As the gear ratio is more, the no of hand wheel rotation required to turn the valve obturator through 90 degrees will be more. During the operation, the turning effort exerted by the operator on the hand wheel will be more only for the initial few degrees until the port breaks open and will reduced drastically thereafter.
Disadvantage of the existing system :
The basic purpose of the addition spur reduction attachment in the system is for increasing the mechanical advantage and to reduce the turning effort required at the hand wheel. This situation exists only for a few degrees of valve opening and after the port breaks open, the situation is quite normal to operate the valve without spur 2 gear attachment.
Because of the permanent attachment of the spur existing system and provision for fixation of hand wheel in the existing system and provision for fixation of hand wheel only at the pinion shaft of the spur attachment, the operator continues to operate the valve through the hand wheel attached to to the pinion shaft even after the port break which would require lot of unnecessary time and effort required for operating the valve.
The valve gear box, according to this invention, comprises a worm
gear unit consisting of a quadrant, worm gear housed inside a casing; a spur gear reduction unit having a spur wheel meshing'
with a pinion wheel provided with a pinion shaft for engaging with the hand wheel of the said valve; characterised by the shaft of the
worm gear extending outwardly, beyond the spur wheel, the and wheel being detachable and also engageable with the extended portion of the shaft of the worm gear.
This invention will now be described with reference to accompanying drawings, the single Figure in which illustrates by way of example, and not by way of limitation, one of possible
embodiments of the valve gear box proposed herein.
The worm shaft (4) extends to receive the spur gear reduction
(5). The spur gear reduction unit has a spur wheel (6) which is attached to the pinion wheel (7). The pinion shaft (8) can receive
the hand wheel (9) for operation f can receive the valve.
Further, the worm shaft (4) extends beyond the receive the hand wheel (9).
As explained earlier, the valve would need higher mechanical advantage during initial few degrees of opening and can be operated by fixing the hand wheel on the pinion shaft (8).
After the port breaks open, when the valve is not demanding more torque, the hand wheel could be shifted to the extended portion of the worm input shaft (4), so that the operation of the valve will be quicker and can be operated with nominal turning effort.
The terms and expressions herein are of description and not of limitation, inasmuch as this invention is not confined to the embodiment herein described and illustrated, but various other embodiments are possible without departing from the scope and ambit of this invention.
|Indian Patent Application Number||178/CHE/2007|
|PG Journal Number||34/2011|
|Date of Filing||29-Jan-2007|
|Name of Patentee||AUDCO INDIA LIMITED|
|Applicant Address||AUDCO INDIA LIMITED MOUNT POONAMALEE ROAD MANAPAKKAM CHENNAI 600089.|
|PCT International Classification Number||F16H61/38|
|PCT International Application Number||N/A|
|PCT International Filing date|