Fluid handling – With lock or seal – Locks against rotary motion
Patent
1991-01-14
1992-05-05
Chambers, A. Michael
Fluid handling
With lock or seal
Locks against rotary motion
251 58, F16K 3500
Patent
active
051098830
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a isolators, in particular 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) cause the effective length of the ram link system and hence the position of the blade to change.
The present invention 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 isolator which is the subject of the present invention more particularly has an actuator housed in a casing which flange mounts onto the valve or isolator to be driven. The actuator comprises a conventional hydraulic ram the base end of which is preferably pin jointed to an anchor bracket mounted interiorly of the casing at the end thereof remote from the flange. The rod end of the ram is preferably pin jointed to a lever arm which, when the casing is mounted on the isolator, will be drivingly connected to the isolator shaft.
The advantages of this arrangement are: aligning properties of the isolator shaft bearings. torque is taken on the bearing mounting stools. necessity to locate the anchor point on the isolator frame.
Further features which may advantageously be used together with the hydraulic actuator according to the invention are as follows.
1) Auxiliary drive for devices such as limit switches
Since the blades of large isolators are subject to large loadings and to thermal expansion, the rotation of the input shafts of large isolators is never truly rotary, and they are subject to axial movements as well. With this type of shaft rotation it is virtually impossible to obtain accurate operation of shaft driven devices such as limit switches, deceleration valves and position transmitters.
The construction of the isolator according to the invention facilitates the fitting of a coupling to convert the uneven motion of the main isolator shaft to true rotary motion of an auxiliary shaft. This may be achieved by means of a device which consists of a short length of tube fixed onto the actuator casing and onto the outside diameter of which plain journal bearings are fitted. A tubular shaft which carries the operating cams for various auxiliary devices rotates on these bearings. This shaft is closed at its outboard end, and is driven by a universal joint from the main isolator shaft.
2) Locking pins for locking the isolator blade
Locking pins may be suitably provided to lock the isolator blade in normally three positions, closed, open or intermediate for maintenance. At the closed position it is important that the locking pin locates the isolator shaft and blade exactly in its completely closed position for safety of personnel who may be in the isolated space. It is not possible to achieve this by using a simple pin in a simple hole because the necessary clearances in the holes would allow unacceptable movement of the blade. This is overcome by using a circular pin with an eccentric sleeve.
Such features (1) and (2) may alternatively form independent and separate aspect of the invention.
The invention will be further described, by way of example only, with reference to the accompanying drawings, wherein:
FIG. 1 is a sectional view of a hydraulic actua
REFERENCES:
patent: 2911953 (1959-11-01), Killian
patent: 2954754 (1960-10-01), Flick
patent: 3237916 (1966-03-01), Bryant
patent: 3765438 (1973-10-01), Di Sciascio
patent: 4039419 (1977-08-01), Buse
Chambers A. Michael
Grovak Grossventiltechnik AG
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