Valves and valve actuation – Electrically actuated valve – Including solenoid
Reexamination Certificate
2000-12-15
2002-03-26
Yuen, Henry C. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Including solenoid
C251S235000, C251S344000
Reexamination Certificate
active
06361018
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a coaxial valve for regulating and shutting off the flow of a fluid or gaseous flow medium.
BACKGROUND INFORMATION
There are particularly stringent requirements for valves which are used for regulating and shutting off liquid or gaseous flow media under extreme conditions such as chemical aggressiveness, very high or very low temperatures or very high pressures. Propulsion in aircraft and spacecraft is one field of application of valves used for shutting off a liquid or gaseous medium under extreme conditions. In such applications, the valves are subjected not only to extreme high and low temperatures but also to extreme temperature changes. In the case of valves for liquid and gaseous rocket fuels, there are further parameters such as high mass flow rates, high pressures and short switching times (opening, closing, positioning).
For use in particular in aerospace applications, a coaxial valve is used for shutting off a liquid or gaseous flow medium, comprising a valve housing, a valve sleeve, and a closing body. The valve housing has an inlet and an outlet for the medium to be shut off. The valve sleeve is arranged in the valve housing in an axial direction between an open position and a closed position, whereby the valve sleeve is slidable in a longitudinal direction of the valve housing between the open and closed positions for the purpose of opening or shutting off the flow of the medium. The medium to be shut off flows in the longitudinal direction through the valve sleeve when the valve is open. The closing body is arranged at one end of the valve sleeve coaxially thereto. The valve sleeve rests against the closing body in the closed position so as to provide a seal, and on the other hand, with the valve sleeve in the open position, the valve sleeve is spaced at a distance from the closing body for freeing a valve opening cross section therebetween. Such a coaxial valve further comprises an actuating drive for opening and closing the valve.
Up to now, valves of the above described type comprised a pneumatically operated actuating drive. A pneumatic system such as the actuating drive of a valve has the disadvantage in that it is very complex, is associated with the danger of leakage, and in particular in aerospace applications is problematic in view of the high reliability which is required. Possible leakage is conducted away separately in a connecting line.
Helium is used as a pressure means (control fluid) which is used primarily as a seal gas between the hot and the cold flow (turbine propellant gas/fuel) in the turbopumps and during such use is consumed due to leakage losses. It can thus happen that toward the end of a mission there is no longer any helium left for operating the valves. A further disadvantage is the expenditure in design, weight and cost, required for the helium pipe system and regulating system to which each fuel valve has to be connected. Such systems also pose problems concerning their reliability. Since a compressible gas is used as a pressure medium, the actuation movement of a valve can only be very coarsely influenced from a time-related and kinematic point of view. Only an open position and a closed position are possible, both against an end stop. Defined intermediate positions and precise control movements are practically impossible.
German Utility Model DE 297 06 688 U1 discloses a coaxial valve as mentioned above, further including a transmission part in the form of a lever or an articulated lever which is used as a connection between an actuator and a valve sleeve and which causes displacement of the valve sleeve in the coaxial valve. In this arrangement, the transmission part interacts on one side with the valve sleeve. With such an arrangement there is an inherent danger that due to the one-sided application of force, the valve sleeve may jam in the coaxial valve. This is particularly fatal for applications where maintenance of the coaxial valve is not possible or possible only at considerable expense, such as for example during the extreme conditions mentioned in the introduction.
European Patent Application Publication EP-OS 0 257 906 discloses various embodiments of seat valves in which the axially-movable seat body is driven by an electric motor via a spindle
ut arrangement. The emphasis has been placed on achieving as compact a design of the valve housing as possible. This has been achieved in that the rotor of the electric motor largely makes use of the cross section of the flow channel, with the rotor itself being located in the flow stream of the conveying medium. In this way, the external diameter of the valve housing corresponds approximately to the external diameter of the adjoining pipelines. Such an arrangement is however associated with considerable disadvantages. The units (bearing, rotor, gearing) which are incorporated directly in the flow channel, considerably impair the flow, so that considerable losses in pressure have to be anticipated. Depending on the physical characteristics of the flowing medium, large friction moments act on the rotating rotor, so that an unnecessarily increased amount of power is required to drive it. Aggressive flow media can chemically/physically attack bearings, rotor and gearing, and thus considerably shorten their useful life. Consequently, such a valve design is only suitable for non-aggressive media of low viscosity, where the throughput is relatively small.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a control valve, in particular for cryogenic and aggressive rocket fuels, which is particularly flow-enhancing, relatively simple and compact in design, and which has a drive that is not located in the conveyed flow medium. Furthermore, the drive should be arranged so as to be largely thermally decoupled, and it should consume as little power as possible. In addition, operation of the control valve is to be as troublefree as possible. The invention further aims to avoid the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a coaxial valve for regulating and shutting-off the flow of a liquid or gaseous flow medium. The valve comprises a valve housing with an inlet and an outlet connected by a flow passage for the liquid or gaseous medium, and a valve sleeve that is arranged in the housing (in the flow passage) axially between an open position and a closed position, so as to be slidable in a longitudinal direction between the open position for allowing the medium to flow in the longitudinal direction through the valve sleeve, and the closed position for shutting off the flow of the medium. The valve further comprises a closing body that cooperates with the valve sleeve to selectively achieve the closure seal or the open flow passage through the valve. Particularly, on the one hand the valve sleeve rests against the closing body in the closed position to provide a seal, and on the other hand, when the valve sleeve is in the open position, the sleeve is spaced at a distance away from the closing body so as to free a valve opening cross-section. The present valve further comprises an actuating drive for opening and closing the valve by sliding the valve sleeve selectively in the longitudinal direction between the open position and the closed position and/or to any desired intermediate partial-open position therebetween.
Particularly according to the invention, the actuating drive comprises a rotational electric servomotor including a linear actuator, and a transmission part or mechanism coupled between the linear actuator and the valve sleeve so as to transmit the linear movement of the linear actuator to the valve sleeve. The transmission part or mechanism comprises an adjusting lever embodied as a rocking lever that extends in a direction generally transverse relative to the longitudinal direction of motion of the valve sleeve. A first end of the rocking lever or adjusting lever is a
Bethe Gerd
Roth Martin
Voit Arno
Astrium GmbH
Fasse W. F.
Fasse W. G.
Keasel Eric
Yuen Henry C.
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