Actuated valve system triggered by the failure of a collapsible pin under overpressure condition

An actuated valve system operates (open/close) automatically under overpressure condition. The system includes an on/off valve assembly, a spring actuator assembly configured to actuate the on/off valve assembly to open or close a path for the pressurized fluid, a lock mechanism with one locking yoke and two rotatable locking handles, a collapsible pin type pressure sensing assembly configured to trigger the action of the spring actuator assembly, and a pressure sensing line. The collapsible pin type pressure sensing assembly includes a body, a plunger with two stems, one of which is rigidly connected with the locking yoke, and a collapsible pin, which mechanically fails when the fluid pressure reaches the predetermined level. When the collapsible pin fails, the plunger moves together with the locking yoke, and the locking yoke loses its restriction to the motive element of the spring actuator assembly, and thus trigger the operation of the actuated valve system.

FIELD OF THE INVENTION

The present invention relates generally to pressurized fluid systems and more particularly, but not by way of limitation, to an actuated valve system that can operate (open/close) automatically when the pressure responsive member (collapsible pin) detects the overpressure conditions in a pressurized fluid.

BACKGROUND

Pressurized fluid systems are typically provided with valves that can operate (open/close) under overpressure conditions. In practice, a system including pressure sensor, logic solver and valve with actuator is often used. When the fluid pressure reaches the predetermined level, the sensor will detect the large increase in fluid pressure, and the logic solver will send command to the actuator to open/close the valve after getting the signal from the sensor.

The safety of the pressurized fluid systems protected by pressure sensor, logic solver and valve is threatened when the valve does not open/close as expected, such as when the sensor fails or the transmission of signal between sensor and the logic server fails or the transmission of command between logic server and valve interrupts.

Some other fail-safe valve systems that can also open/close automatically under overpressure condition use a collapsible pin arrangement, such as taught by U.S. Pat. No. 4,724,857 & U.S. Pat. No. 6,666,230 issued to Taylor and U.S. Pat. No. 6,651,686 issued to Scantlin and Cravens. In such systems, the pin is placed under compressive loading along an axial direction of the pin by the pressure of the fluid. A sufficient increase in fluid pressure above a nominal operational level causes the pin to buckle, or collapse, allowing a plunger or other mechanism to move to trigger the operation of the actuated valves.

A valve system can be advantageously configured to open or close in response to the collapse of a collapsible pin. However, system forces can undesirably affect a threshold pressure level at which the pressure responsive member begins to fail. For example, friction forces and fluidic pressure can tend to offset the compressive loading upon a collapsible pin if the pin actuation and the valve are directly coupled.

There is therefore a continued need for improvements in the art to increase the accuracy and repeatability of the protection systems, and it is to such improvements that the present invention is directed.

An actuated valve system is provided to operate (open/close) automatically under overpressure condition. The system includes a spring actuator assembly, an on/off valve assembly, a lock mechanism with one locking yoke and two rotatable locking handles, a collapsible pin type pressure sensing assembly and a pressure sensing line. The function of the pressure sensing line is to connect the upstream of the valve assembly with the body cavity of the collapsible pin type pressure sensing assembly, and in such a way the plunger undertakes the pressure upstream of the valve assembly.

Collapsible pin type pressure sensing assembly is the trigger unit of the whole system, and it mainly includes pin nut, pin cage, collapsible pin, body, and plunger assembly comprised by plunger, stem and locking yoke. The function of the collapsible pin type pressure sensing assembly is designed based on Euler's theory regarding the buckling of slim column subject to compressive force and realized by changing the plunger assembly's working positions.

The plunger of the collapsible pin type pressure sensing assembly bears the force due to the pressure in the upstream pipeline, and the force is transmitted to the collapsible pin by the second plunger stem. When the pressure in upstream pipeline is lower than the predetermined level, the axial force in the collapsible pin is below the threshold buckling value, and thus the collapsible pin is in a stable state, and the plunger assembly is in its first position. In this position, the locking yoke, which is rigidly connected with the first plunger stem, locks the rotatable locking handles, and the rotatable locking handles hold the motive element through the supporting rod of the spring actuator assembly, and the valve assembly is in the usual position.

When the pressure in the upstream pipeline is higher than the predetermined level, the axial force in the collapsible pin is over the threshold buckling value and simultaneously the collapsible pin buckles and loses its load-supporting capability. Due to the loss of the propulsive force from the collapsible pin, the plunger assembly, which is pushed by the pressure inside of the pipeline, moves to its second position. In this process, the locking yoke moves until losing its restriction on the rotatable locking handles, and then the rotatable locking handles releases the supporting rod of spring actuator assembly, and the spring actuator assembly drives the valve assembly to its unusual position, and thus the automatic operation (open/close) of the on/off valve assembly under overpressure condition is realized.

In this application, the collapsible pin type pressure sensing assembly realizes the function of pressure sensor and logic solver, and thus the whole system does not need any sensors and signal transmission, and the design is simple and reliable.

SUMMARY OF THE INVENTION

The present invention comprises a spring actuator assembly, an on/off valve assembly, a lock mechanism with one locking yoke and two rotatable locking handles, a collapsible pin type pressure sensing assembly and a pressure sensing line.

The spring actuator assembly comprises a housing, a supporting rod, a motive element (such as a piston), a motion conversion mechanism and at least one spring. The spring actuator assembly has an unactuated state and an actuated state. In the unactuated state, the spring is in a state of storing potential energy, and the motion of the motive element and motion conversion mechanism is restricted since the supporting rod is held by lock mechanism. When the spring actuator assembly shifts to the actuated state, the spring(s) thrusts the motive element and supporting rod to move linearly, and the motion conversion mechanism changes linear motion into rotary motion, and then the spring actuator assembly drives the coupled on/off valve assembly to a fully-open or fully-closed position.

The function of the pressure sensing line is to connect the upstream pipeline of the on/off valve assembly with the first chamber of body cavity, and in such a way the plunger of the pressure sensing assembly undertakes the pressure in the upstream pipeline of the on/off valve assembly.

The collapsible pin type pressure sensing assembly is the trigger unit of the whole system, and it mainly includes pin nut, pin cage, collapsible pin, body, and plunger assembly comprised by a plunger, a first plunger stem, a second plunger stem and a locking yoke. The function of the collapsible pin type pressure sensing assembly is designed based on Euler's theory regarding the buckling of slim column subject to compressive force and realized by changing the plunger assembly's working positions.

The plunger assembly has a first position and a second position, and the second position of the plunger is longitudinally offset from the first position. Whether the plunger assembly is in the first position or the second position is determined by the collapsible pin. The collapsible pin is installed outside of the body, and its one side is held by the second plunger stem and another side is held by the pin nut. When the collapsible pin buckles, the plunger assembly moves from the first position to the second position.

The plunger of the collapsible pin type pressure sensing assembly bears the force due to the pressure in the upstream pipeline, and the force is transmitted to the collapsible pin by the second plunger stem. When the pressure in upstream pipeline is lower than the predetermined level, the axial force in the collapsible pin is below the threshold buckling value, and thus the collapsible pin is in a stable state, and the propulsive force from the collapsible pin retains the plunger assembly in its first position. In this position, the locking yoke, which is rigidly connected with the first plunger stem, locks the rotatable locking handles, and the rotatable locking handles are not able to rotate and thus hold the supporting rod to restrict it from moving linearly, and then the spring actuator assembly is in the unactuated state and the valve assembly is in the usual position.

When the pressure in the upstream pipeline is greater than the predetermined level, namely when the pressure in the first chamber of body cavity is higher than the predetermined level, the axial force in the collapsible pin is over the threshold buckling value and simultaneously the collapsible pin buckles and loses its load-supporting capability. Due to the loss of the propulsive force from the collapsible pin, the plunger assembly, which is pushed by the pressure inside of the pipeline, moves to its second position. In this process, the locking yoke moves until losing its restriction on the rotatable locking handles, and then the rotatable locking handles rotate and thus release the supporting rod of spring actuator assembly. The spring actuator assembly shifts to the actuated state, and the supporting rod moves linearly due to the thrust force of the spring(s), and the motion conversion mechanism, which is coupled to the stem of the on/off valve assembly, drives the valve to open or close, and thus realize the automatic operation of the valve assembly under overpressure condition.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the presently preferred embodiment of the present invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. An exemplary embodiment of an actuated valve system100of the present invention is shown inFIG. 1.

With reference toFIG. 1, the present invention comprises a collapsible pin type pressure sensing assembly101, which is exposed to the pressure in the upstream pipeline110of the on/off valve assembly111. The on/off valve assembly111is a rotationally actuated valve, such as a ball valve, butterfly valve, plug valve or other quarter turn valve, and the valve stem112of the on/off valve assembly111is coupled with the actuator stem113of the spring actuator assembly102.

The present invention further comprises a spring actuator assembly102which is adapted for engagement with the on/off valve assembly111. The spring actuator assembly102is characterized by an unactuated state as shown inFIG. 4and an actuated state as shown inFIG. 5, and is adapted to shift from its unactuated state to its actuated state when the lock mechanism103releases its restriction on the supporting rod117.

The spring actuator assembly102may include a motive element105, such as a piston or other sliding element, which is movable within a housing115, such as a cylinder, from a first position126, corresponding to the unactuated state, to a second position128, which is longitudinally offset from the first position126in a second direction140and corresponding to the actuated state.

The spring actuator assembly102further includes at least one springs116in order to apply a directional force to the motive element105. If unopposed, the motive element105will move from its unactuated position to its actuated position due to the directional force from the springs116. When the spring actuator assembly102is in the unactuated state, the springs116is in a state of storing potential energy, and the directional force of the springs116is overcome by applying a supporting force, which is provided by the lock mechanism103, against the supporting rod117of the motive element105.

As shown inFIGS. 1, 2, 3, 4, 5, 6 and 7, the lock mechanism103mainly comprises one locking yoke118, which is rigidly connected with the stem119, and two rotatable locking handles120, which are preferably connected with the housing115of spring actuator assembly102by hinges121. The rotatable locking handles120are further equipped with friction-reducing devices122, preferably ball bearings, on the ends to facilitate the relative movement between the rotatable locking handles120and the locking yoke118. One small spring123is connected with two rotatable locking handles120to provide force that folds two rotatable locking handles120in the process of resetting the whole system. The lock mechanism103has an unreleased state as shown inFIG. 4, in which the locking yoke118prevents the rotation of the rotatable locking handles120, and a released state as shown inFIG. 5, in which the locking yoke118permits such rotation, and the lock mechanism103is adapted to shift from its unreleased state to its released state in response to the buckling of the collapsible pin125.

The plunger124of the collapsible pin type pressure sensing assembly101bears the force due to the pressure in the upstream pipeline110, and the force is transmitted to the collapsible pin125by the second plunger stem143, which is connected with the plunger124. When the pressure in upstream pipeline110is lower than the predetermined level, the axial force in the collapsible pin125is below the threshold buckling value, and thus the collapsible pin125is in a stable state, and the plunger124is in its first position126. In this position, the lock mechanism103is in an unreleased state, in such a state the locking yoke118prevents the rotation of rotatable locking handles120, and the rotatable locking handles120is not able to rotate and thus hold the supporting rod117to restrict it from moving linearly, and then the spring actuator assembly102is in the unactuated state and the on/off valve assembly111is in the usual position.

When the pressure in the upstream pipeline110is greater than the predetermined level, namely when the pressure in the first chamber129of body133cavity of the collapsible pin type pressure sensing assembly101is higher than the predetermined level, the axial force in the collapsible pin125is over the threshold buckling value and simultaneously the collapsible pin125buckles and loses its load-supporting capability. Due to the loss of the propulsive force from the collapsible pin125, the plunger124, which is pushed by the pressure inside of the pipeline, moves to its second position128. In this process, the locking yoke118moves until losing its restriction on the rotatable locking handles120, and then the lock mechanism103shifts to its released state, namely the rotatable locking handles120releases the supporting rod117of spring actuator assembly102. The spring actuator assembly102shifts to the actuated state, the directional force of the springs116moves the motive element105and the connected supporting rod117. The movement of the motive element105and supporting rod117of the spring actuator assembly102is a linear translational movement, whereas the on/off valve assembly111is opened or closed by rotational movement of the valve stem112, and thus the spring actuator assembly102further comprises a motion conversion mechanism104to change linear motion into rotary motion. The motion conversion mechanism104may be a scotch-yoke131arrangement, as shown inFIG. 1. The supporting rod117supports a cylindrical roller130which is engaged by a scotch-yoke131as shown. The scotch-yoke131is mounted to the actuator stem113, which in turn is coupled to the valve stem112. Movement of the supporting rod117to the extended position132FIG. 3induces a camming action which rotates the on/off valve assembly111to the desired position.

Other similar mechanism for converting the linear translational movement of the motive element105to a rotary motion which can open, close or otherwise change the positioning of the on/off valve assembly111may also be used.

With reference toFIGS. 1 and 2, the collapsible pin type pressure sensing assembly101comprises a body133, which is characterized by a tubular internal cavity134formed therein, also having a longitudinal axis. The internal cavity134is also preferably cylindrical in shape, and disposed in coaxial relationship with the body133.

As shown inFIGS. 1 and 2, the collapsible pin type pressure sensing assembly101further comprises a plunger assembly106. The plunger assembly106comprises a plunger124, positioned within the internal cavity134of body133, and is movable along the longitudinal axis of the internal cavity134. The plunger124is characterized by a first side135and an opposed second side136.

The plunger124divides the internal cavity134into a first chamber129and a second chamber137, with the first chamber129adjacent the first side135of the plunger124, and the second chamber137adjacent the second side136of the plunger124. The internal cavity134and plunger124are provided with seals not shown in order to maintain substantially fluid-tight separation between the opposed first chamber129and second chamber137.

The present invention further comprises a pressure sensing line138, through which the first chamber129is interconnected with the upstream pipeline110of the on/off valve assembly111, and in such a way the plunger124undertakes the pressure in the upstream pipeline110. The second chamber137is equipped with vent port139to communicate with the atmosphere. As the plunger124moves along the longitudinal axis of the internal cavity134, the volume of one chamber increases, and the volume of its opposed chamber-decreases.

The plunger124is characterized by at least a first position126and a second position128, which is longitudinally offset in a second direction140from the first position126. In the embodiment shown inFIG. 6, the second direction140is on the right side, and it corresponds to the position of the plunger124shown inFIG. 6, in which the volume of the second chamber137has been reduced, and the volume of the first chamber129has been expanded.

The plunger assembly106further comprises a first plunger stem141engaged with the first side135of the plunger124and extending longitudinally through the first chamber129and out of the left end of the body142and then connecting with locking yoke118. Seals not shown are provided to maintain a substantially fluid tightness between the first plunger stem141and the left end of the body142through which it passes.

The plunger assembly106further comprises a second plunger stem143engaged with the second side136of the plunger124and extending longitudinally through the second chamber137and out of the right end of the body144.

As shown inFIGS. 1 and 2, the collapsible pin type pressure sensing assembly101further comprises a pressure responsive member, which is coupled to the plunger assembly106and disposed to oppose longitudinal movement of the plunger124in the second direction140, and configured to mechanically fail in response to the application of a selected force. The pressure responsive member is preferably characterized as a collapsible pin125, although other members can be used such as a shear pin. The second plunger stem143engages one end of the collapsible pin125, thereby coupling the plunger124to the collapsible pin125. A pin nut145of a cage146, holds the another end of the collapsible pin125.

As shown inFIGS. 1 and 2, the plunger124bears the force due to the pressure in the upstream pipeline110, and the force is transmitted to the collapsible pin125by the second plunger stem143. When the pressure in upstream pipeline110is lower than the predetermined level, the axial force in the collapsible pin125is below the threshold buckling value, and thus the collapsible pin125is in a stable state, and the propulsive force from the collapsible pin125retains the plunger assembly106in its first position126. In this position, the lock mechanism103is in the unreleased state, in such a state the locking yoke118, which is rigidly connected with the first plunger stem141prevents the rotation of the rotatable locking handles120, and thus retain the supporting rod117to restrict it from moving linearly, and then the spring actuator assembly102is in the unactuated state and the on/off valve assembly111is in the usual position.

As presented inFIG. 3, at such point that the pressure of the system fluid rises above the predetermined level, namely when the pressure in the first chamber129is higher than the predetermined level, the axial force exerted upon the collapsible pin125via the plunger124and the second plunger stem143exceeds the threshold buckling value and the collapsible pin125starts to buckle, and the thrust force exerted on the plunger assembly106drops off rapidly. Due to the rapid decrease of the propulsive force from the collapsible pin125, the plunger assembly106, which is pushed by the pressure inside of the pipeline, moves to its second position128. In this process, the locking yoke118moves until losing its restriction on the rotatable locking handles120, and then the lock mechanism103shifts to its released state, namely the rotatable locking handles120release the supporting rod117of spring actuator assembly102. The spring actuator assembly102shifts to the actuated state, the supporting rod117moves linearly due to the thrust force of the springs116, and the motion conversion mechanism104, which is coupled to the valve stem112, drives the on/off valve assembly111to open or close, and thus the automatic operation of the on/off valve assembly111under overpressure condition is realized.

After the pressure inside of the pipeline recovers to its normal value, the system may be reset. This is accomplished by returning the motive element105to its original position, and thus let the on/off valve assembly111recover to its initial status. It is contemplated that the returning the motive element105of the spring actuator assembly102of the present invention may include an appropriate mechanism, such as screw-nut arrangement with a handwheel147and a resetting rod149, as presented inFIG. 7, or worm-gear arrangement with handwheel147, etc.

When the motive element105returns to its original position, namely when the on/off valve assembly111recovers to its initial status, there is no thrust force from the supporting rod117acts on the rotatable locking handles120, and these two rotatable locking handles120fold up under the acting force of the small spring123.

After the rotatable locking handles120return to their original position, the plunger assembly106can be reset by pushing the second plunger stem143, and then a new collapsible pin125can be replaced.

In general, on/off valve assembly111such as shown inFIG. 1are not frictionless systems. In order to move the on/off valve assembly111between the open position and the closed position, significant amounts of force may be required to overcome reactive forces, such as stiction force i.e., force resisting initial movement of the valve and function force i.e., force resisting continued movement of the valve after the initial movement. One source of these reactive forces is the seal assemblies used to maintain an adequate seal against the fluid pressure about the valve.

Another source of reactive forces is the pressure of the fluid upon the various surfaces of the valve as the valve is rotated. The valve variably restricts a flow stream of the fluid. The pressure of the fluid varies as the on/off valve assembly111is placed at intermediate positions between the open and closed positions, and this can impart significant resistance to the rotation of the valve. Thus, making the collapsible pin type pressure sensing assembly101initially independent from the spring actuator assembly102advantageously prevents the stiction and friction forces of the on/off valve assembly111from affecting the operation of the collapsible pin type pressure sensing assembly101.

It will now be seen that an advantage of the present invention as embodied herein is the isolation of system forces relating to the activation of the on/off valve assembly111from the compressive forces acting upon the collapsible pin125.

Although various embodiments have been presented herein, it will be understood that numerous changes and modifications are readily contemplated and not listed herein for brevity. For example, it will be understood that any number of different mechanical linkages can be used within the actuator assembly to activate the valve assembly. Moreover, although a rotary activation has been described, such is not necessarily limiting to the scope of the appended claims.

Other pressure responsive members such as a shear pin can readily be used in place of the buckling pin disclosed herein. The use of ball bearings to facilitate the relative movement of the locking yoke118and rotatable locking handles120is preferred, but other configurations such as rollers or bushings can also be employed.

For purposes of the appended claims, mechanical failure will be understood as describing, for example, the buckling of a collapsible pin125such as, the shearing of a shear pin. Other shaft-stem coupling arrangements besides a scotch-yoke131arrangement to generate a torque are readily contemplated and are well within the ability of those skilled in the art to implement, such as configurations using rack-pinion arrangement, belts, chain drives, or linkages.