HYDRAULIC ACTUATOR FOR ISOLATORS

Abstract: A hydraulic actuator for an isolator, comprising a hydraulic ram (6) one end of which is connected to a lever (2) which is in turn connected to a shaft for a valve plate or other closure, the actuator having a casing (1) which flange mounts on the isolator, and the other end of the ram (6) being attached to the end of the casing (1) remote from the said flange (1a).

Description: "HYDRAULIC ACTUATOR FOR I SOLATORS " This invention relates to a hydraulic isolator 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. 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 actuator which is the subject of the present invention thus has a casing which .flange mounts onto the valve or isolator to be driven. The base end of a conventional hydraulic ram is preferably pin jointed to an anchor bracket mounted onto the end of the casing remote from the flange. The rod end of the ram is preferably pin jointed to a lever arm which, when mounted on the isolator, will be connected to the isolator shaft. The advantages of this arrangement are: - Temperature differential effects are eliminated. - There are no main bearings in the actuator which could inhibit the self aligning properties of the isolator shaft bearings. - No reaction loadings are taken on the frame of the isolator. The reaction torque is taken on the bearing, mounting stools. - The provision of locking pins is facilitated. - Orientation of the actuator is universal and is not dependent on the necessity to locate the anchor point on the isolator frame. - The anchor point does not interfere with any external insulation. 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 rotatio-n of the input shafts of large isolators is never truly rotary, and 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 actuator according to the invention facilitates the fitting of a coupling to convert the uneven motion of the main 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 body 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 3 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 clos-ed 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 aspects of the invention. The invention will be further described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a sectional view of a hydraulic actuator for an isolator, according to the invention; Figure 2 is an orthogonal view of the actuator shown in figure 1; Figure 3a is a sectional view, taken along the line X-X in figure 3b. of a coupling for converting uneven motion of a main isolator shaft to rotary motion of an auxiliary shaft; Figure 3b is an end view of the coupling shown in figure 3a; __-.-- Figure 3c is a perspective view illustrating operation of the coupling shown in figures 3a and 3b; Figure 4a is a side view of a locking pin construction for locking the isolator blade; and Figure 4b is a view taken in the direction of the arrow in figure 4a. Figures 1 and 2 of the drawings show a casing 1, a flange la of which is to be mounted to the isolator to be driven. A lever arm assembly 2 is connected to one end of a conventional hydraulic ram 6 having a cylinder 6a and a rod 6b, the other end (the base end) of the ram being connected to an anchor bracket 3 mounted onto the end of the casing remote from the flange la. The ram 6 is pivotably connected to the anchor bracket 3 by a pin joint 4. The rod end of the ram 6 is connected to the lever arm assembly 2 by another pin joint 4. The other end of the lever arm assembly 2 is keyed to a collar 5 to which is in turn keyed an isolator shaft (not shown), which will carry a flap valve plate (not shown) or other valve closure as appropriate. In operation the ram 6 is hydraulically actuated to pivot the lever arms 2 between the positions shown in solid and broken lines in figure 1, to open and close the isolator by means of the valve closure carried by the isolator shaft, in a conventional manner. However, because the actuator is contained within the casing 1, temperature differential effects between the hot isolator frame and the cold hydraulic ram can be overcome. The other advantages described in detail above can also be obtained. Figure 3 shows a means whereby a coupling is used to convert uneven motion of a main isolator shaft to true rotary motion of an auxiliary shaft. This is achieved by a device which comprises a short length of tube 11 fixed onto the actuator body 12 by means of a mounting flange 13. Onto the outside diameter of the tube 11 are fitted plain journal bearings 14. A tubular output shaft 15 which carries operation cams 16 for various auxiliary shaft driven devices such as limit switches, deceleration valves and position transmitters (not shown) rotates on these bearings 14. The shaft 15 is closed at its outboard end 17, and is driven by a universal/flexible joint 18 from the main isolator (input) shaft 19. In the locking pin construction illustrated in figure 4, there is shown an operating arm 21 in its closed position, a locking tab 22. a locking pin 23 of circular cross-section, and an eccentric locking sleeve 24. Numeral 25 indicates the actuator body. The locking tab 22 secures the eccentric locking sleeve 24 in a locked position by means of a bolt through the body of the actuator 25.

Claims: CLAIMS 1. A hydraulic actuator for an isolator, comprising a hydraulic ram (6) one end of which is connected to a lever (2) which is connected to a shaft for an isolator closure member, characterized by a casing (l) which flange mounts on the isolator, the other end of the ram (6) being attached to the end of the casing (1) remote from the said flange (la). 2. A hydraulic actuator as claimed in claim 1-, characterized in that a base end of the hydraulic ram (6) is pin jointed to an anchor bracket (3) mounted onto the end of the casing (1) remote from the flange * (la). 3. A hydraulic actuator as claimed in claim 1 or 2, characterized in that a rod end (6b) of the hydraulic ram (6) is pin jointed to a lever arm (2) which is connected to the isolator shaft. 4. A hydraulic actuator as claimed in any of claims l to 3, characterized by a coupling (18) for converting uneven motion of a main shaft (19) to rotary motion of an auxiliary shaft (15). 5. A hydraulic actuator as claimed in claim 4, characterized by a tube member (11) fixed onto the actuator body and on the outside of which bearings (14) are fitted, a tubular auxiliary shaft (15) for driving one or more auxiliary devices rotatable on said bearings (14), and a universal joint (18) for driving the auxiliary shaft (15) from the main shaft (19). 6. A hydraulic actuator as claimed in any of claims 1 to 5, characterized by a circular locking pin (23) with an eccentric sleeve (24) for locking an isolator closure member.

Inventors: SQUIRRELL ANTON FREDERICK, SQUIRRELL, ANTON, FREDERICK
Applicants: GROVAG GROSSVENTILTECH, GROVAG GROSSVENTILTECHNIK AG
Application year: 1989
Main classification: F16K31
IPC codes: F15B15, F16K31