Fluid handling – With lock or seal – Locks against rotary motion
Patent
1993-05-18
1995-07-04
Chambers, A. Michael
Fluid handling
With lock or seal
Locks against rotary motion
251 31, 251 58, 251279, F16K 3500
Patent
active
054291534
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a hydraulic actuator for isolators, in particular for diverter valves or flap isolators (herein both referred to as isolators) used for isolating gases under severe operating conditions of high temperature and/or high pressure.
For many diverter valve or flap isolator applications it is necessary or desirable to use hydraulic actuation systems.
Conventional hydraulic actuation systems usually consist of a hydraulic ram operating a lever which is connected to a shaft to be rotated, to which a valve closure plate is attached. The base end of the ram is pin jointed to an anchor bracket which is normally fixed to some point on the damper or isolator frame. The disadvantage of this arrangement is that differences in temperature between the isolator frame (hot) and the hydraulic ram (cold) causes the effective length of the ram link system and hence the position of the blade to change.
PCT patent application no. PCT/GB89/00593 (publication no. WO 89/11612), corresponding to U.S. Pat. No. 5,109,883 describes and claims an improved hydraulic actuator for overcoming such disadvantages. Specifically, the invention disclosed in WO 89/11612 provides a hydraulic actuator for an isolator, comprising a hydraulic ram one end of which is connected to a lever which is in turn connected to a shaft for a valve plate or other closure, the actuator having a casing which flange mounts on the isolator, and the other end of the said ram being attached to the end of the casing remote from the said flange.
The increasing size of gas turbines creates the need for larger diverter valves for directing the flow of products of combustion to boiler or by pass for combined cycle plant. Larger diverter valves require greater torque. One method of providing this torque is by means of the hydraulic actuator which is the subject of the above-mentioned WO 89/11612.
The operating thrust for this particular actuator is provided by a single hydraulic ram. By the very nature of this arrangement the ram not only transmits the desired torque, but imposes on the overhung shaft a bending moment and also a corresponding radial load upon the bearing.
The present invention overcomes these latter two disadvantages, by providing according to the invention two identical rams operating in opposite directions, wherein the radial laod exerted by the one ram is equal in magnitude but opposite in direction to the other.
Thus the present invention provides a hydraulic actuator for an isolator, comprising a casing having a flange to be mounted to the isolator to be driven, a lever arm assembly connected at each end thereof to a respective one of a pair of identical double acting cylindrical rams, the other ends of the said rams being respectively connected to opposite ends of the casing remote from the said flange, wherein the said identical rams are arranged to operate in opposite directions, the radial load exerted by one ram being equal in magnitude but opposite in direction to the other ram.
The alignment of rams and actuating arm is such that the thrusts for a given direction of rotation are equal and opposite, thus eliminating the bending moment on the shaft.
The general construction of the actuator of the present invention is preferably similar to that described and shown in WO 89/11612 but arranged to house two rams. Any of the features of the actuator described and shown in WO/11612 may be utilized in the present invention, either per se or in an appropriately modified form, for example as follows:
a base end of each hydraulic ram is pin jointed to a respective anchor bracket mounted onto a respective end of the casing remote from the flange;
a rod end of each hydraulic ram is pin jointed to a double ended lever arm which at its center is connected to the isolator shaft;
the hydraulic actuator further comprises a coupling for converting uneven motion of a main shaft to rotary motion of an auxiliary shaft;
more specifically, a tube member is fixed onto the actuator body and on the outside of which bearings are fitted, a tubular aux
REFERENCES:
patent: 1678700 (1928-07-01), McEwan
patent: 2149725 (1939-03-01), Canaris
patent: 2532153 (1950-11-01), Drescher et al.
patent: 2954754 (1960-10-01), Flick
patent: 3237916 (1966-03-01), Bryant
patent: 3765438 (1973-10-01), Di Sciascio
patent: 4202527 (1980-05-01), Price et al.
patent: 4570900 (1986-02-01), Lonardi et al.
patent: 4690168 (1987-09-01), Kihm
patent: 4821998 (1989-04-01), Legille et al.
patent: 5109883 (1992-05-01), Squirrell
Chambers A. Michael
Holler Norbert P.
WES Technology Inc.
LandOfFree
Hydraulic actuator for isolators does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hydraulic actuator for isolators, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hydraulic actuator for isolators will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-754622