Expansible chamber devices – With toothed gear – spline or thread rigid with working member
Reexamination Certificate
2002-04-19
2003-12-23
Look, Edward K. (Department: 3745)
Expansible chamber devices
With toothed gear, spline or thread rigid with working member
C092S013600
Reexamination Certificate
active
06666129
ABSTRACT:
The invention relates an operating device for a rotatable closing element of a valve, in particular a rotating actuator for a disc or throttle valve which can be operated by a pressurized medium, as specified in the preamble of claim 1.
A generic operating device is disclosed in FR-A-2 528 128. In the case of this device the cylindrical housing is in the form of an upper and a lower base and a jacket mounted between these bases, the two cylindrical bases being joined to each other by two stationary longitudinal guides. Each of the latter extends through and guides a piston axially, one which is sealed off from the jacket as it slides. Both the piston and the two cylinder bases are penetrated by a central rotating shaft. Repeated penetration of the piston, first by the longitudinal guides and then by the rotating shaft, necessitates sealing of the piston from a pressurized means chamber formed at all these points of penetration between the piston and the cylinder base next to it and the jacket. A piston shank facing the other cylinder base is provided with two helical guide grooves mounted diametrically opposite each other, grooves which are open in the direction of the projecting cylinder base. The piston shank is connected to one of these projecting cylindrical aprons, one which serves as a stop for the end position of the piston when the interior surface of the adjacent cylinder base is reached. Limitation of the end position in the other direction is ensured by a stop ring mounted in the pressurized medium space and not accessible from the outside in assembly of the operating device.
An operating mechanism with comparable and/or equivalent features is disclosed in DE 297 03 710 U1. This rotating actuator, which is operated in particular with compressed air as pressurized means, is applied by preference for valves in which the closing element may in theory rotate endlessly. Such is the case, for example, with so-called ball and disk valves. In these valves additional measures must be taken to ensure that the rotating actuator involved will be stopped in precisely the angular position required so that adequate sealing is ensured in the seating area. In order to provide a specific prescribed angle of rotation special measures are required for angle of rotation limitation, especially in the area of transformation between linear movement of the piston and rotary movement of the rotating shaft. In the case of the conventional rotating actuator the angle of rotation desired is retained in that a stop segment is mounted on the rotating shaft, at least one fixed stop is in the form of a guide rod, and stop segment and guide rod limit the angle of rotation directly at its exact prescribed value independently of piston stroke.
The conventional rotating actuator presents among others the disadvantage that the stop segment may be adapted to changed angle of rotation relationships only by relatively costly replacement of the segment. Changes in angle of rotation limitation due to wear and tolerances may not be made directly without such replacement. Other conventional rotating actuators either exhibit no features at all as regards angle of rotation limitation and angle of rotation setting (DE 298 14 551 U1; EP 0 622 574 B1) or they do exhibit such features (DE 33 03 872 A1) but are relatively complex in structure and not very maintenance-friendly.
The operating device for a pivotable valve body as disclosed in DE 33 03 872 A1 has a pivotably mounted piston in whose external piston jacket two curving guides in the form of diagonal grooves are incorporated diametrically opposite each other. Driving rollers rotatable about axes fixed in a cylinder wall of the operating devices engage these grooves. A driven shaft for operating the pivotable valve body is connected by force fitting inside the piston to the latter both axially and radially. In this design the piston accordingly executes both a stroke movement against the force of a reset spring and in addition the desired rotary movement of the driven shaft, so that a seal sealing the piston from the cylinder wall must execute this total movement resulting from piston stroke and angle of rotation. A form of movement such as this entails increased sealing wear. In addition, the operating device is not particularly assembly and maintenance friendly because of its complex structure, and especially because of the carrier rollers rigidly mounted internally on the cylinder wall.
Also prescribed for the rotating actuators for disk valves is the requirement that a higher torque than that in the angle of rotation area upstream or downstream be available during introduction of the closing element into or removal from the seating seal. According to the rules of conservation of energy, this means that in the course of drive movement a relatively small angle of rotation of the rotating shaft corresponds to a relatively large axial piston stroke. The helical guide groove is for this reason provided with varying pitches. Printed publication EP-B-0 622 574 B1 explicitly illustrates (
FIG. 3
) and describes a configuration of the guide groove, which, viewed as a whole, is not configured to be symmetrical at all points. As a result, the desired course of torque relative to the central position of the closing element may be changed only in one of the end positions, in the present case during opening and closing of the closing piece. It is also proposed in this connection that different associations be made between linear and rotary movement during opening and closing. This is accomplished in that the curve guide has a curved surface coordinated with the opening and closing movement of the valve (pertinent flank surface of the guide groove) each having a different curve gradient.
In order to make use of the generic operating devices as versatile and flexible as possible without the need for especially costly retrofitting operations, it is desirable for it to be possible to use the rotating actuator in air-opening and thus inevitably spring-closing operation and in air-closing and necessarily spring-opening operation. This requires a precise course of the guide groove or one more or less symmetrical at all points. A guide groove such as this is disclosed in U.S. Pat. No. 2,998,805 (FIG. 8). The guide groove there is exactly point-symmetrical in design, so that the pertinent end position of the closing element (closed position or open position) is approached with the same torque characteristic. The other rotating actuators referred to, because of their given kinematics either do not solve the present problem at all (threaded spindle/threaded nut system in DE 298 14 551 U1) or no specific comments are made regarding this aspect.
The object of this invention is to develop a generic operating device which is of simple design and maintenance-friendly, reliable, and versatile in use and with which a desired angle of rotation may easily be set and retained.
This object is attained by the features disclosed in the descriptive portion of claim 1. Advantageous embodiments of the operating device proposed make up the subjects of the dependent claims.
The two guide grooves, which are bounded on all sides by the piston shank and so are self-contained, as a result of their given point-symmetrical design, permit variable and thus universal use of the operating device. Since the course of torque required in the two end areas of the guide groove may be described, the actuator used may be both air-opening and so necessarily spring-closing and air-closing and so necessarily spring-opening. The two alternative solutions differ only in that the closing element of the valve, rotated 90 degrees relative to the other solution, is connected to the operating device in question as claimed for the invention. In addition, reliable and trouble-free use of the operating device is ensured by the two congruent guide grooves of the piston apron mounted diametrically opposite each other. Limitation of the piston stroke on both sides, on one side by application of the frontal end of the piston sha
Sauer Martin
Schmid Werner
Wengert Holger
Wiedenmann Willi
Leslie Michael
Look Edward K.
Shannon John P.
Tuchenhagen GmbH
Venable LLP
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