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 first pinion wheel provided with a first pinion shaft for engaging with the hand wheel of the said valve; characterised by a second pinion wheel meshing with the spur wheel and provided with a second pinion shaft, the said hand wheel being detachable and also enageable with the second pinion shaft, said first and second pinion wheels having different gear ratios with respect to the spur wheel.

Full Text

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 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 there after 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 rotations required to turn the valve obdurate 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 reduce 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 gear attachment. Because of the permanent attachment of the spur gear 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 the pinion shaft even after the port breaks which would require lot of unnecessary time and effort for operating the valve. The valve gear box, according to this invention, comprises 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 first pinion wheel provided with a first pinion shaft for engaging with the hand wheel of the said valve; characterised by a second pinion wheel meshing with the spur wheel and provided with a second pinion shaft, the said hand wheel being detachable and also engageable with the second pinion shaft, said first and second pinion wheels having different gear ratios with respect to the spur wheel. This Invention will now be described with reference to the accompanying drawings which Illustrate in the single Figure one of possible embodiments of the valve gear box proposed herein. the embodiment will be seen to consist of a worm gear unit involving a quadrant (1) and the worm gear (2) housed inside a casing (3). The worm shaft (4) extends to receive the spur gear reduction unit (5)i 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 of the valve. An additional pinion wheel (10) is provided which also engages with the spur wheel (6). The pinion shafts (8) & (11) are connected to the pinion wheels (7) & (10) respectively. Thus spur gear reduction unit (5) houses a spur wheel (6) engaging with two pinion wheels (7) & (10) to achieve two different sets of gear ratios and mechanical advantage In combination with the basic worm gear (2). Advantage of the invention: As explained earlier, the valve would need higher mechanical advantage during initial few degrees of opening until the valve breaks open and could be operated normally thereafter. During the Initial few degrees of opening, before the valve breaks open, the valve could be operated by fixing the hand wheel on the pinion shaft (8) which would yield a higher gear ratio and mechanical advantage necessary for the purpose. After the port breaks open, when the valve does not demand more torque, the hand wheel could be shifted to the pinion shaft (11) which yields less mechanical advantage and gear ratio, so that operation of the valve will be quicker and can be operated with lesser turning effort. The terms and expressions herein are of description and not of limitation, since 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. , We Claim : 1. 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 first pinion wheel provided with a first pinion shaft for engaging with the hand wheel of the said valve; characterised by a second pinion wheel meshing with the spur wheel and provided with a second pinion shaft, the said hand wheel being detachable and also ageable with the second pinion shaft, said first and second pinion wheels having different gear ratios with respect to the spur wheel. 2. A valve gear box substantially as herein described with reference to, and as illustrated in, the accompanying drawings

Documents:

0186-che-2007 correspondence po.pdf

186-CHE-2007 AMANDED PAGES OF SPECIFICATION 07-10-2009.pdf

186-CHE-2007 EXAMINATION REPORT REPLY RECEIVED 07-10-2009.pdf

186-che-2007-abstract.pdf

186-che-2007-claims.pdf

186-che-2007-correspondnece-others.pdf

186-che-2007-description(complete).pdf

186-che-2007-drawings.pdf

186-che-2007-form 1.pdf

186-che-2007-form 18.pdf

186-che-2007-form 26.pdf