Patent Application
20190331238
The present disclosure generally relates to ball valves for flow control or metering as well as valve seat configurations which improve flow performance of the ball valve.
Ball valves are a type of rotary valve that controls or meters liquid or gas fluid flow in a passageway. Two basic designs of ball valves include a floating ball valve and a trunnion mounted ball valve. A ball valve typically includes a valve body which has an internal spherical chamber in communication with an inlet and outlet and is designed to connect two or more sections of tubing together. A ball member is a sphere that is disposed within the internal chamber with a flow port, such as a circular borehole or “V” shaped borehole, which permits the flow of fluid between the upstream inlet and the downstream outlet. The ball member is supported by a concentrically positioned valve stem extends through the valve body such that the ball can be externally rotated by a handle or an actuator.
The lifetime of a valve can be predicated on the quality of the valve seal. Over time, debris can build up in seat pockets which cause the valve to fail prematurely and develop leaks. Knowing this, precision ball valves the components are currently designed to be larger than required to ensure desired flow rates. In addition, current designs are also limited by the valve angle of the rotational actuator. For example, a limited angle torque actuator produces torque through a rotation angle of less than 180°. They are typically used in Industrial or sensitive environments due to their high angular acceleration without torque ripple. Currently, to increase flow rates in ball valves that art; actuated by limited angle torquers (LATs), the entire assembly has to be scaled larger. This adds to the weight, cost, and complexity all while increasing rotational forces and decreasing operation lifetime. Therefore, a need exists for a valve seat to prevent leakage and increase lifetime while improving flow characteristics.
U.S. Pat. No. 4,193,580 A discloses a plug-type valve seal which employs an elongated plug with ellipsoidal or curved opposing ends. The plug surface is sealed by a seat having an elongated closed loop configuration which engages the surface of the plug along a non-circular line or band.
U.S. Pat. No. 7,325,783 B2 discloses a valve seat with for use in a gate operated ball valve. The seat includes stress relief grooves formed in the flanges for reducing stress concentration on the valve seat while the gate is closed. While beneficial for increasing the lifetime of the valve assembly, there still exists a desired for a system and method that increases flow characteristics while increasing overall lifetime of the assembly.
In accordance with one aspect of the disclosure, a valve seal is provided. The valve seal includes a flow passage with a elliptical cross-section in a longitudinal direction, an annular flange in communication with the flow passage; and a hemispherically contoured sealing face opposite the annular flange and in communication with the flow passage.
In accordance with another aspect of the disclosure, a valve system for metering fluid flow is provided. The valve system includes a valve body having a substantially spherical valve chamber in communication with an annular inlet in parallel with and opposite an annular outlet which forms a passageway therethrough, a valve member with a substantially spherical surface configured to rotate perpendicularly to the passageway about a concentric valve shaft, the valve member having a fluid passage therethrough to selectively pass fluid from the inlet to the outlet, and a seat ring having a longitudinal bore with an elliptical cross-section and a sealing face hemispherically contoured to match the substantially spherical valve member surface.
In accordance with a further aspect of the disclosure, a method of manufacturing a valve seat is provided. The method includes the steps of selecting a valve member with a valve port and a valve member having known dimensions capable of a desired flow rate, determining dimensions of an elliptical flow port with a major-axis based on the known dimensions of the valve member and a minor-axis based on the known dimensions of the valve port, determining a profile of a mating surface configured to positively engage a surface of the valve member to form a fluid-tight seal between the elliptical flow port and the valve port, and manufacturing an annular valve seat according to the determined dimensions of the elliptical slow port and the determined profile of the mating surface.
Aspects of the disclosure will now be described in detail with reference to the drawings, wherein like reference numbers refer to like elements throughout, unless specified otherwise.
Referring to
Referring to
In the open position, the valve member 20 is rotated such that the fluid passage 22 is substantially collinear with inlet 16 and outlet 18 to permit a continuous fluid passage through the valve system 10. In a closed position, the valve member 20 is rotated such that the fluid passage 22 does not communicate with the inlet 16 and the outlet 18. In addition, the valve member 20 can be rotated to intermediate rotational positions that correspond to partially open or, equivalently, partially closed rotational positions enabling the valve system 10 to be used for flow control, metering, or throttling. The valve stem 24 may be actuated manually by a handle or wheel, hydraulically, electrically, pneumatically, or the like.
An annular seat ring 28 is mounted in a counterbore 30 of the inlet 16. The seat ring is a tubular member having an inner elliptical surface 32 which defines a longitudinal fluid passage that is parallel and in communication with the inlet passage 16 and the valve member passage 22 when the valve member 20 is rotated to an open position. The seat ring 28 has a downstream face 34 which is configured for sliding engagement with the valve member 20 to provide a fluid-tight seal between the inlet 16 and the valve member passage 22 to prevent fluid leakage debris collection in the valve chamber 14. With the exemplary embodiment of the ball valve as shown in
The seat ring 26 has an annular flange 36 at an upstream end of the tubular member. The flange 36 has an outer diameter surface that registers with an inner diameter surface of the counterbore 30 to form a fluid-tight seal between the inlet 16 and the valve member passage 22. A biasing member 38, such as a spring or other biasing means, is positioned within the counterbore 30 between the flange 34 and a stepped base of the counterbore 34 adjacent to the inlet 16. The biasing member 38 provides a positive sealing force against the seat ring 28 to create a substantially fluid-tight seal through a positive engagement between the contoured sealing face 32 and an external surface 40 of the valve member 20.
The flange 36 has an annular outside diameter that effectively matches the inside diameter of the counterbore 30. By having an annular outside diameter, the seat ring 28 can be used in existing valve systems that have tubular or cylindrical components such as the inlet, outlet, and counterbore. Utilizing the seat ring 28 in an existing valve system can increase the flow rate of fluid passing through the valve by increasing the exposed area to the valve member 20 without increasing the overall size of any of the valve system 10. The biasing member 38 has an effective diameter that corresponds to the diameter of the flat upstream face 42 of the flange 34. The biasing member 38 provides a symmetric loading force circumferentially about the fluid passage 22 in order to provide a positive biasing force longitudinally in the direction of the fluid flow against the surface 40 of the valve member 20. The biasing force can be calculated from the fluid pressure requirements of the valve system 10 in order to maintain a positive sealing force between the hemispherical face 34 and the spherical surface 40 of the valve member 20.
Referring to
In general, the valve system 10 of the present disclosure can find applicability in in various industrial applications such as but not limited to work machines 50 such as those used throughout many industries, including hut not limited to, earth moving, excavation, mining, agricultural, marine, construction, power generation, and other such industries. The present disclosure improves on the ability of the valve system 10 described above, to meter or throttle fuel to an engine 52 of the work machine 50. For example, the valve work machine 50. The single point injection system may include a limited angle torque motor or limited angle torquer (LAT) which acts as the rotational actuator 21. A LAT is capable of intricate annular position, velocity, and acceleration control without torque ripple because of a single phase configuration and the lack of commutation required for angular exclusions greater than 180°. For at least this reason. LATs are used in highly sensitive environments such as industrial, aerospace, semiconductor, medical, and military industries. An elliptical seat ring 28 incorporated into a single point injection system with a LAT can increase overall flow rates and reduce overall size by compensating for the limited annular rotation of the LAT. The elliptical seat ring 28 increases the useful area of flow in the plane of rotation.
Referring to
The illustrated method 400 of making an annular valve seat includes the step of determining the desired flow rate of the fluid metering system 410 based on the application of the system. In the exemplary embodiment of the ball valve for use in a providing metered fuel to a prime mover, this step involves determining the maximum, minimum, and range of fuel flow rates desired for operating the prime mover.
Once the desired specifications of the flow rates are known, a fuel metering system can be selected with the requisite characteristics for the application 420. In the exemplary embodiment of the ball valve, this step involves selecting a ball valve with a valve chamber, inlet, outlet, valve member, and valve port that is capable of providing the maximum, minimum, and intermediate range of fuel flow rates to operate the prime mover.
The valve port shape and dimensions along with the corresponding ball valve member dimensions are determined to accommodate the desired flow rate 430. For throttle control of fuel metering, a v-port or other port shape may be chosen for the valve port, followed by selecting a ball size capable of reliably accommodating the flow rate through the selected valve port size and shape. Next, a valve chamber with a corresponding inlet, outlet, and counterbore is selected based on the determined ball size.
The specifications of the annular seat ring can be determined based on the desired flow rate, valve port shape and size, and the valve member shape and size step 440. In the exemplary embodiment of a ball valve, the minor axis of the elliptical fluid passage is determined based on the maximum dimension of the valve port in the direction of rotation, and the major axis of the elliptical fluid passage is determined based on the maximum dimension of the ball valve member in the direction of rotation axis. The profile of the mating surface of the seat ring is determined based on the shape and size of the valve member 450. For example, the mating surface of the valve seat is a concave hemispherical surface in order to positively engage with the convex spherical surface of the ball valve member. The flange of the seat ring is determined based on the inner diameter of the inlet and corresponding counterbore of the valve chamber 460.
The annular valve seat can be manufactured based on the determined specifications of the minor & major axes of the elliptical fluid passage, the contoured profile of the hemispheric mating surface, and the diameter of the flange 470. The seat ring can be manufactured a number of ways such as subtractive machining, additive manufacturing, injection molding, and the like. The selected material type and manufacturing method can be determined based on operating environments which account for media/fluid type being metered, system operating pressure & temperature, duty cycle, and the like.
Once the seat ring is manufacture according to determined specifications, a biasing spring can be selected according to the counterbore inner diameter and the desired positive sealing force between the seat ring and the valve member 480. For example, a spring with a spring rate can be selected to maintain a positive sealing force between the hemispherical mating surface of the seat ring and the spherical face of the ball valve member while also minimizing frictional forces in order to reduce the required input actuation force to rotate the ball valve member. Finally, the valve system can be assembled with the determined components, i.e. the valve member, valve chamber, and biasing member, along with the seat ring manufactured to desired specifications 490.
Accordingly, by providing the system and method for increasing the maximum flow rate of the valve seat 28, the components of the ball valve system 10 as a whole can be reduced while simultaneously extending the useful lifetime of the valve system 10 and the valve seat 10 by reducing unwanted build up in the valve chamber 14. Further, aspects of the disclosure provide increased performance in the form of accuracy, actuation speed, fuel efficiency, and the like as a result of reducing the overall weight of the valve system 10 and components, i.e. the valve body 12, valve member 20, valve stem 24, trunnion support 26, biasing member 38, and actuator 27.
It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
