Patent Grant
7237472
This application claims the benefit under 35 USC §119 of U.S. patent application No. 60/535,555, filed Jan. 9, 2004, the disclosure of which is incorporated herein by reference in its entirety to the extent not inconsistent herewith.
The invention relates to a choke system with a hydraulic actuator, such as is used in an oil or gas wellhead.
A choke valve is a throttling device. It is commonly used as part of an oil or gas field wellhead. It functions to reduce the pressure of the fluid flowing through the valve internals. Choke valves are placed on the production “tree” of an oil or gas wellhead assembly to control the flow of produced fluid from a reservoir into the production flow line. They are used on wellheads located on land and offshore, as well as on wellheads located beneath the surface of the ocean.
In general, chokes involve:
There are four main types of flow trim commonly used in commercial chokes. Each flow trim involves a port-defining member, a movable member for throttling the port, and seal means for implementing a total shut-off. These four types of flow trim can be characterized as follows:
In each of the above, the flow trim is positioned within the choke valve at the intersection of the choke valve's inlet and outlet. In most of the valves, the flow trim includes a stationary tubular cylinder referred to as a “cage”, positioned transverse to the inlet and having its bore axially aligned with the outlet. The cage has restrictive flow ports extending through its sidewall. Fluid enters the cage from the choke valve inlet, passes through the ports and changes direction to leave the cage bore through the valve outlet.
Such a flow trim also includes a tubular throttling sleeve that slides over the cage. The sleeve acts to reduce or increase the area of the ports. An actuator, such as a threaded stem assembly, is provided to bias the sleeve back and forth along the cage. The rate that fluid passes through the flow trim is dependent on the relative position of the sleeve on the cage and the amount of port area that is revealed by the sleeve.
Maintenance on the deep subsea wellhead assemblies cannot be performed manually. An unmanned, remotely operated vehicle, referred to as an “ROV”, is used to approach the wellhead and carry out maintenance functions. To aid in servicing subsea choke valves, choke valves have their internal components, including the flow trim, assembled into a modular sub-assembly. The sub-assembly is referred to as an “insert assembly” and is inserted into the choke valve body and clamped into position.
When the flow trim becomes worn beyond its useful service life due to erosion and corrosion caused by particles and corrosive agents in the produced substances, an ROV is used to approach the choke valve, unclamp the insert assembly from the choke valve body and attach a cable to the insert assembly so that it may be raised to the surface for replacement or repair. The ROV then installs a new insert assembly and clamps it into position. This procedure eliminates the need to raise the whole wellhead assembly to the surface to service a worn choke valve.
In order to efficiently produce a reservoir, it is necessary to monitor the flow rate of the production fluid. This is done to ensure that damage to the formation does not occur and to ensure that well production is maximized. This process has been, historically, accomplished through the installation of pressure and temperature transmitters into the flow lines upstream and downstream of the choke valve. The sensor information is then sent to a remote location for monitoring, so that a choke valve controller can remotely bias the flow trim to affect the desired flow rate. The controller sends electrical signals to means, associated with the choke valve, for adjusting the flow trim.
Choke valves common to oil and gas field use are generally described in U.S. Pat. No. 4,540,022, issued Sep. 10, 1985, to Cove and U.S. Pat. No. 5,431,188, issued Jul. 11, 1995 to Cove. A subsea choke valve is described in U.S. Pat. No. 6,782,949, issued Aug. 31, 2004. All of these patents are assigned to Master Flo Valve Inc., the owner of this application.
Control valves, such as choke valves, are often equipped with a means to provide position control. In the most fundamental form, manual operation by a lever or hand wheel is used. To provide remote control of a valve's position a variety of actuators, including hydraulic actuators, can be used.
U.S. Patent Application published Nov. 4, 2004 as US 2004/02116884 and naming Bodine et al. as inventors, describes known hydraulic actuator control systems for subsea chokes as follows:
In offshore oil and gas production, it is often common for more than one well to be produced through a single flow line. In a typical installation, the products from each individual well flow are combined into a common flow line, which then carries the products to the surface or combines those products with the products of other flow lines. The difficulty in managing a multiple well completion produced through a single flow line is that not all of the wells may be producing at the same pressure conditions or include the same flow constituents (liquids and gases).
For example, if one individual well is producing at a lower pressure than the pressure maintained in the flow line, fluid can back flow from the flow line into that well. Not only is the loss of production fluids undesirable, but the pressure changes and reverse flow conditions within that well may damage the well and/or reservoir. Similarly, if one well is producing at a pressure above the flow line pressure, that well may produce at an undesirable flow rate and pressure, again with the potential to damage other wells and/or the reservoir. Thus, the management of flow rates and pressures is of critical importance in maximizing the production of hydrocarbons from the reservoir.
In one prior art subsea production system, control signals and a hydraulic fluid supply are transmitted along an umbilical from a topside control system to a subsea control module which supplies hydraulic fluid to actuators in the subsea trees, manifolds, valves, choke and other functions. As control valves within the control module receive signals to open or close the choke, the control valves actuate to control the flow of hydraulic fluid to the choke actuator through either hydraulic lines opening or closing. A common choke actuator is a hydraulic stepping actuator, which, depending on the style of actuator and choke being used, may take 100 to 200 steps to close, although systems requiring a smaller, or larger, number of steps are possible. Each step involves the actuator receiving a pulse of hydraulic pressure, which moves the actuator, and then a release of that pressure, which allows a spring to return the actuator to its initial position. In typical systems, where the SCM (subsea control module) is located proximate (e.g., within about 30-feet) to the choke/actuator, about one second is required for the pressure pulse to travel from the control valve in SCM to the actuator and two seconds are required for the spring to return the actuator to its initial position. Thus, with a total of three seconds per step and a total of up to 200 or more steps required to fully actuate the choke, the time required to fully close or open the choke is considerable. The risk of equipment failure is also increased due to the components being actuated hundreds, thousands, or even millions, of times.
In another typical prior art subsea production system, control signals and a hydraulic fluid supply are transmitted along an umbilical from a topside control system directly to a subsea choke, bypassing the subsea control module on an electro hydraulic control system. Operation of a direct hydraulic control system would also be as described above, since no subsea control module is required, and a direct electric (control) system would operate similarly, minus any hydraulic control lines. The choke is opened and also closed via hydraulic signals transmitted through dedicated umbilical lines. Hydraulic signals from the surface control the flow of hydraulic fluid to the choke actuator through either hydraulic opening and closing lines. The common choke actuator is a hydraulic stepping actuator which, depending on the style of actuator and choke being used, may take 100–200 steps to close. Each step involves the actuator receiving a pulse of hydraulic pressure, which moves the actuator, and then a release of that pressure, which allows a spring to return the actuator to its initial position. In typical systems, the time required for the pressure pulse to travel from the surface to the actuator is directly related to the offset distance (umbilical length from surface to choke), water depth and actuating pressure, which can be minutes per step for long offsets. Also, an additional amount of time is required for the spring to return the actuator to its initial position. The time to actuate each step can run into minutes, thus, with a total of up to 200 steps required to fully actuate the choke, the time required to fully close or open the choke is considerable.
In yet a third typical prior art subsea production system, electrical power and a hydraulic fluid supply are transmitted along an umbilical from a topside control system directly to a subsea choke actuator system, bypassing the subsea control module on an electro hydraulic control system. Operation of a direct hydraulic control system would also be as described above, since no subsea control module is required, and a direct electric (control) system would operate similarly, minus any hydraulic control lines. A hydraulic fluid supply is stored local to the choke, such as in accumulator. The choke is opened and also closed via electrical signals transmitted through dedicated umbilical conductors to actuate the open and close functions. The electrical signals are received by a directional control valve that regulates hydraulic flow to the open and close functions of choke actuator. For this instance, hydraulic fluid is supplied to the local choke accumulators, which are refilled by the hydraulic supply along an umbilical. The common choke actuator is a hydraulic stepping actuator which, depending on the style of actuator and choke being used, may take 100 to 200 steps to close. Each step involves the actuator receiving an electrical power pulse, followed by a pulse of hydraulic pressure, which moves the actuator, and then a release of the electrical power that releases the hydraulic pressure, which allows a spring to return the actuator to its initial position. In typical systems, roughly one second is required for the electrical power pulse to travel from the surface to the choke, and then for the pressure pulse to travel from the local choke accumulator to the actuator and roughly two seconds are required for the spring to return the actuator to its initial position. Thus, with a total of three to four seconds per step and a total of up to 200 steps required to fully actuate the choke, the time required to fully close or open the choke is considerable. The power requirements for this type of system are considerable, while the umbilical must have electrical conductors (one for open, one for close) for each choke.
U.S. Pat. No. 6,782,952 issued Aug. 31, 2004, discloses a hydraulic stepping valve actuator for moving the sliding sleeve of a downhole well valve. The system relies on a mechanical locking system to restrain the sleeve at each incremental position. As well, the system does not provide a fast close fail system, which is needed in a production well.
There remains a need in the art for systems and methods for increasing the responsiveness and speed of choke control systems, especially subsea systems.
Broadly stated, the invention provides a choke system with hydraulic controls for a hydraulic actuator. The invention includes a choke equipped with adjustable valve internals, and a hydraulically operated choke actuator operably connected through a stem to the adjustable valve internals such that incremental linear translating movement of the stem in response to incremental displacement of predetermined amounts of hydraulic fluid to or from the choke actuator adjusts the position of the adjustable valve internals. The choke actuator includes a biased piston sealed within a cylinder forming a first chamber and a second chamber on either side of the piston, with the piston being connected to the stem. The hydraulic control system of this invention eliminates excessive lines or solenoid valves and avoids the need for mechanical locking mechanisms. The hydraulic controls include:
Preferably, the choke system includes a fast close system. In one embodiment, the fast close system includes:
In another embodiment, the fast close system includes:
The slave cylinders and the choke actuator may be spring biased. Alternatively, the choke actuator may biased toward the closed position with a further hydraulic cylinder acting onto the choke actuator to function as a spring bias.
Definitions:
As used herein and in the claims, a reference to “a connection”, “connected” or “connect(s)” is a reference to a hydraulic connection unless the context otherwise indicates.
As used herein and in the claims, the word “comprising” is used in its non-limiting sense to mean that items following the word in the sentence are included and that items not specifically mentioned are not excluded. The use of the indefinite article “a” in the claims before an element means that one of the elements is specified, but does not specifically exclude others of the elements being present, unless the context clearly requires that there be one and only one of the elements.
As used herein and in the claims, the terms “up” and “down”; “upper” and “lower”; “upwardly” and “downwardly”; “upstream” and “downstream”; “right” or “left” and other like terms indicating relative positions relative to a given point or element, are used to more clearly describe some embodiments of the invention as they appear in the figures. However, when applied to equipment and methods for use in wells, they may assume a different orientation, as will be evident to those skilled in the art.
In the description that follows, like parts are marked throughout the specification and drawings with the same reference numerals. The figures are not necessarily to scale. Certain features of the invention may be shown exaggerated in scale or in schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. The present invention includes embodiments of different forms. Specific embodiments are shown in the drawings and described in detail herein with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that illustrated and described herein. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce the desired results.
In particular, various embodiments of the present invention provide a number of different methods and apparatus for affecting control of a choke. The concepts of the invention are discussed in the context of a subsea choke but the use of the concepts of the present invention is not limited to subsea chokes specifically or choke assemblies generally. The concepts disclosed herein may find application in other choke assemblies, such as surface chokes, as well as other hydraulically actuated valves, both within oil field technology and other high pressure applications to which the current invention may be applied. Other embodiments of the choke system may include any subsea adjustable components, for example: chokes, downhole or below the mudline/tubing hangers, control valves, etc.
In the context of the following description, the term “choke” is used to refer to the family of valve devices incorporating a fixed or variable orifice having one or more adjustable valve internal parts (valve internals) that is used to control fluid flow rate or downstream system pressure. These devices may also be known as pressure control valves. Chokes are available for both fixed and adjustable modes of operation and can be used for production, drilling, or injection applications. Adjustable chokes enable the fluid flow and pressure parameters to be changed to suit process or production requirements. Types of chokes may include, but are not limited to, flow line chokes (whether stepping type, or infinitely variable type); subsea or surface separator/processing unit chokes (upstream or downstream) that enable smooth flow into or out from the subsea or surface separator/processing unit; subsea or surface chemical injection “metering” chokes, etc.
The hydraulics and controls for the choke system of the present invention are illustrated schematically in multiple embodiments in
In
In
The choke actuator 20 of this invention is preferably a hydraulic linear actuator, of the type commonly used in choke actuation to open, close or modulate the flow trim of a choke. Although not completely shown herein, it will be understood that, in the subsea environment, a subsea control module receives the open, close or fast close signals via one or more umbilical is from a surface control system via an electrical signal input. In
The hydraulic circuit of this invention is shown in the Figures with four exemplary embodiments, each with its own advantages and disadvantages. Hydraulic circuit schematics of the four embodiments are depicted in the
The hydraulic circuits provide choke valve positioning that can be varied by the use of incremental steps. The incremental movement, or steps in either the opening or closing direction is accomplished through the use of one of the two hydraulic slave cylinders 31, 42 which can either add or subtract a fixed volume of hydraulic fluid from the actuator cylinder 20. A series of check valves provides direction for flow in the hydraulic lines, locking of the actuator cylinder 20, and re-filling of the slave cylinders 31, 42 during operation and eliminates excessive lines or solenoid valves from the system.
Each embodiment of
Fluid power, solenoid valves, drain and control are typically external to the system on a control module, but have been included in the schematics for the purposes of explanation.
Operation
Each of the four embodiments is shown with similar mechanisms for the open and close steps. The fundamental difference between the four configurations lies in how to provide the closing force on the top of the actuator piston and how to accomplish the “fast close” function.
In each embodiment, to effect a single step in the open direction on the actuator cylinder 20 solenoid valve 54 is energized. This allows high pressure fluid from supply 27 to push the piston 32 in opening slave cylinder 31 through its travel thereby displacing all the fluid that was in the right chamber 36 of the opening slave cylinder 31 into the lower chamber 25 of the actuator cylinder 20. The added volume moves the piston 21 in the actuator cylinder 20 a proportionate distance. When the solenoid valve 54 is de-energized, the pressure in the opening slave cylinder 31 is released. The spring 40 in the opening slave cylinder 31 then returns the piston 32 to the original position while drawing fluid from the upper chamber 24 of the actuator cylinder 20 and thus resetting for the next open step.
When solenoid valve 56 is in the de-energized state high pressure fluid from the lower chamber 25 of the actuator cylinder 20 is able to overcome the spring force in the closing slave cylinder 42, as shown in
The invention will now be described with reference to each of the
The closing force for the actuator 20 in this configuration is supplied by the spring 26 that acts on the top of the actuator piston 21. Fluid in the upper chamber 24 is used as a reservoir only for the opening slave cylinder 31. In order to activate the “fast close” mode in this configuration both solenoid valves 54 and 56 are energized. This allows reverse flow through the two pilot operated check valves 72, 74 to drain all fluid from the lower chamber 25 of the actuator cylinder 20, allowing the spring 26 to push the piston 21 and thus the choke valve to the full closed position.
The configuration provides a means to produce incremental movement of the actuator cylinder 20 through selective energization of solenoid 54 or 56 (and thus slave cylinders 31 or 42). The extent of the increment movement of the actuator 20 can be controlled through sizing of the swept volume of the slave cylinders 31, 42. Thus, depending on the number of incremental movements desired in order to fully open or fully close the actuator 10, the ratio of the volume of the slave cylinder to the actuator can be adjusted (ex. 1:20 to open/close in 20 increments). The configuration is such that operation of the solenoid valves 54, 56 will result in an incremental movement of the actuator cylinder 20 in either the open or close direction respectively. Through energization of both solenoids 54 and 56 simultaneously, the spring bias actuator 20 closes rapidly (referred to as fast close option). Below, the operation of this embodiment is described in greater detail in three parts—open movement, close movement, and fast close.
Open Movement
Solenoid 54 is energized allowing pressurized fluid from the hydraulic supply 27 to move into the left chamber 38 of the slave cylinder 31. This pressurized fluid acts onto the slave cylinder piston 32 and against the internally biased spring 40. The opening slave cylinder 31 consists of a housing cylinder 34 to contain the fluid pressure, similar to a closed end cylinder. Within the cylinder 34, the piston 32 moves linearly with an adequate sealing membrane (not shown) preventing movement of fluid across the piston 32. The piston 32 is spring biased in the open position (toward the left chamber 38) through the compression spring 40 situated in the right chamber 36. Fluid entering the cylinder 34 forces the spring bias piston 32 within the slave cylinder 31 to stroke through its travel expelling the fluid from the right chamber 36. This controlled volume of fluid is pushed through one way check valve 58 and into the lower chamber 25 of the actuator cylinder 20 resulting in a controlled discrete movement of the actuator piston 21. The purpose of check valve 58 is to allow communication between the opening slave cylinder 31 and the actuator 20, while preventing reverse fluid movement from the actuator 20 to slave cylinder 31 when solenoid 54 is de-energized. This ensures that the actuator 20 remains locked in position without the use of a mechanical locking device, as shown in the prior art. An example of a suitable check valve for this purpose is a Bucher Hydraulics model RKVG-06-Z4, however many other known commercial models will perform the function, as will be readily evident to those skilled in the art. When solenoid 54 is de-energized the opening slave cylinder piston 32 returns to its neutral position through the spring bias. As the cylinder piston 32 moves to the neutral position fluid is drawn into the right chamber 36 of the cylinder 31 through re-fill one way check valve 62. Check valve 62 is in communication with the fluid on the upper chamber 24 of the actuator 20 and the return line 30 to the drain 28. The filling process of the right chamber 36 of the opening slave cylinder 31 prepares the system for the next incremental step.
Closed Movement
Solenoid 56 is energized allowing pressurized fluid from the hydraulic supply 27 to move into the left chamber 50 of the closing slave cylinder 42. The closing slave cylinder 42 consists of a housing cylinder 46 to contain the fluid pressure, similar to a closed end cylinder. Within the cylinder 46 exists the piston 44 with an adequate sealing membrane (not shown) to prevent movement of fluid across the piston 44. The piston 44 is spring biased in the extended position through a compression spring 52 situated between the left chamber 50 between the piston 44 and the cylinder end. Pressurized fluid entering the closing slave cylinder 42 from solenoid valve 56 equalizes the pressure load on the closing slave cylinder piston 44. The spring bias feature within closing slave cylinder 42 forces the piston 44 to stroke through its travel expelling the fluid from the right chamber 48 of the cylinder 46 through one way check valve 60 into the supply line circuit 29. One way check valve 66 prevents movement of the fluid into the actuator 20 while orientation of check valve 60 allows fluid to move into the supply line circuit 29. When solenoid 56 is de-energized communication between the left chamber 50 of the closing slave cylinder 42 and the low pressure return pressure line 30 is restored. The cylinder piston 44 is retracted against spring bias due to the higher pressure in the lower chamber 25 of the actuator 20. This movement of the closing slave cylinder 42 absorbs fluid from the lower chamber 25 of the actuator 20 equal to the swept volume of the closing slave cylinder piston 44. The spring bias on the actuator 20 compensates for this fluid loss by moving the piston 21 in the actuator 20 downwardly proportionally. This results in incremental distinct movement of the actuator 20. When the closing slave cylinder piston 44 fully retracts, the system is set for the next operation.
Fast Close Function
The incorporation of a fast close system can be integrated in the open/close circuits described above. A pilot operated check valve 74 is provided in a line 80 connecting supply line circuit 29 at a point between the solenoids 54, 56 and the slave cylinders 31, 42. Pilot valve 74 is connected to the pilot valve 72 which in turn is located in the fast close line 70 between the upper and lower chambers 24, 25 of the actuator 20. In this way pressure sensed at pilot valve 74 when both solenoids 54, 56 are energized is communicated to the pressure sensing port of the pilot operated check valve 72, which opens direct communication in fast close line 70 between the upper and lower chambers 24, 25 of the actuator 20. The spring bias of the actuator 20 causes a fast close without consumption of additional fluid. An example of a suitable device for the pilot operated check valves would be Bucher Hydraulics model ERVH-1, however many commercial models will perform the function, as well known to those skilled in the art.
This embodiment adds a third solenoid operated control valve 82 (or other directional control valve) for directly activating the “fast close” feature with a single pilot operated check valve 72 in the fast close line 70, thereby eliminating pilot valve 74 from
Open Movement
Solenoid 54 is energized allowing pressurized fluid from the hydraulic supply 27 to move into the left chamber 38 of the opening slave cylinder 31. This pressurized fluid acts onto the slave cylinder piston 32 and against the internally biased spring 40. Fluid entering the left chamber 38 forces the spring bias piston 32 within the slave cylinder 31 to stroke through its travel expelling the fluid from the right chamber 36 of the cylinder 34. This controlled volume of fluid is pushed through check valve 58 and into the lower chamber 25 of the valve actuator 20 resulting in a controlled discrete movement of the actuator piston 21. As for
Closed Movement
Solenoid 56 is energized allowing pressurized fluid from the fluid supply 27 to move into the left chamber 50 of the closing slave cylinder 42. The piston 44 is spring bias in the extended position through the compression spring 52 situated between the left chamber 50. Pressurized fluid entering the slave cylinder 42 from solenoid valve 56 equalizes the pressure load on the slave cylinder piston 44. The spring bias feature within the slave cylinder 42 forces the piston 44 to stroke through its travel expelling the fluid from the right chamber 48 through check valve 60 into the supply line circuit 29. Check valve 66 prevents movement of the fluid into the valve actuator 20 while orientation of check valve 60 allows fluid to move into the supply line circuit 29. When solenoid 56 is de-energized communication between the left chamber 50 of the slave cylinder 42 and the low pressure return pressure line 30 is restored. The cylinder piston 44 is retracted against spring bias due to the higher pressure in the lower chamber 25 of the valve actuator 20. This movement of the slave cylinder 42 absorbs fluid from the lower chamber 25 of the actuator 20 equal to the swept volume of the slave cylinder piston 44. The spring bias on valve actuator 20 compensates for this fluid loss by moving the piston 21 in the valve actuator 20 down proportionally. This results in incremental distinct movement of the valve actuator 20. When the slave cylinder piston 44 fully retracts, the system is set for the next operation.
Fast Close Function
The incorporation of a fast close system can be integrated within the circuit by using the third solenoid operated control valve 82 from the control module 76. The circuit involves connecting this control valve 82 to the pilot operated check valve 72 positioned to enable communication of the upper and lower chambers 24, 25 of the valve actuator 20 through fast close line 70. As pressure is applied to the pilot operated check valve 72 the connection of the fast close line 70 equalizes the pressure across the piston 21 in the valve actuator 20. The spring bias of the valve actuator 20 closes the actuator 20 without consumption of additional fluid.
This embodiment varies considerably from the previous two embodiments in that it uses a dual acting hydraulic cylinder as the actuator 20, which in effect divides the upper chamber 24 of the previous embodiment into two chambers, a middle chamber 86 and an uppermost chamber 88. The uppermost chamber 88 is under supply pressure during all operational periods thus biasing the piston 21 in the closed direction. The open and closed stepping functions are otherwise similar to those of
The “fast close” mechanism for in this schematic is similar to that used in
This embodiment of the invention thus replaces the spring used to bias the actuator in
Open Movement
Operation of open solenoid valve 54 results in pressurized fluid moving into the opening slave cylinder 31. Fluid entering the cylinder 34 forces the spring bias piston 32 within the slave cylinder 31 to stroke through its travel expelling the fluid from the right chamber portion 36 of the cylinder 34. This controlled volume of fluid is pushed through check valve 58 and into the lower chamber 25 of the actuator 20 resulting in a controlled discrete movement of the actuator 20. The effective piston area acted upon by the pressure in lower chamber 25 overcomes the small effective area in uppermost chamber 88 moving the actuator 20 the relative distance of the swept volume of the piston 32 in opening slave cylinder 31.
Closed Movement
Solenoid 56 is energized allowing pressurized fluid from the hydraulic supply 27 to move into the left chamber 50 of the closing slave cylinder 42. Pressurized fluid entering the closing slave cylinder 42 from solenoid valve 56 equalizes the pressure load on the slave cylinder piston 44. The spring bias feature within closing slave cylinder 42 forces the piston 44 to stroke through its travel expelling the fluid from the right chamber 48 of the cylinder 46 through check valve 60 into the supply line 29. Check valve 66 prevents movement of the fluid into the actuator 20 while orientation of check valve 60 allows fluid to move into the supply line circuit 29. When solenoid 56 is de-energized communication between the left chamber 50 of the closing slave cylinder 42 and the low pressure return pressure line 30 is restored. The cylinder piston 44 is retracted against spring bias due to the higher pressure in the lower chamber 25 of the actuator 20. This movement of the slave cylinder 42 absorbs fluid from the lower chamber 25 of the actuator 20 equal to the swept volume of the closing slave cylinder piston 44. The supply pressure acting upon the uppermost chamber 88 compensates for this fluid loss by moving the piston 21 in the actuator 20 downwardly proportionally. This results in incremental distinct movement of the actuator 20. When the closing slave cylinder piston 44 fully retracts, the system is set for the next operation.
Fast Close Function
The incorporation of a fast close system is included within the circuit by using the third solenoid operated control valve 82 from the control module 76. By connecting this solenoid control valve 82 to the pilot operated check valve 72, communication in the fast close line 70 connecting middle and lower chambers 86, 25 is opened, equalizing the pressure in these chambers 86, 25 with the pressure in the return line 30. The supply pressure acting on uppermost chamber 88 forces the actuator 20 to close.
This configuration combines the use of two solenoid valves 54, 56 as shown in
Open Movement
Operation of open solenoid valve 54 results in pressurized fluid moving into the opening slave cylinder 31. Fluid entering the cylinder 34 forces the spring bias piston 32 within the slave cylinder 31 to stroke through its travel expelling the fluid from the right chamber 36. This controlled volume of fluid is pushed through check valve 58 and into the lower chamber 25 of the valve actuator 20 resulting in a controlled discrete movement of the actuator 20. The effective piston area acted upon by the pressure in lower chamber 25 overcomes the small effective area in the uppermost chamber 88 moving the valve actuator 20 the relative distance of the swept volume of the piston 32 in opening slave cylinder 31. Check valve 58 allows communication between the slave cylinder 31 and the valve actuator 20, however prevents fluid movement from the actuator 20 to the slave cylinder 31 when solenoid 54 is de-energized. This ensures the actuator 20 remains locked in position without the use of a mechanical locking device, as mentioned above.
Closed Movement
Solenoid 56 is energized allowing pressurized fluid from the hydraulic supply 27 to move into the left chamber 50 of the closing slave cylinder 42. Pressurized fluid entering the slave cylinder 42 from solenoid valve 56 equalizes the pressure load on the slave cylinder piston 44. The spring bias feature within slave cylinder 42 forces the piston 44 to stroke through its travel expelling the fluid from the right chamber 48 through check valve 60 into the supply line circuit 29. Check valve 66 prevents movement of the fluid into the valve actuator 20 while orientation of check valve 60 allows fluid to move into the supply line circuit 29. When solenoid 56 is de-energized, communication between the left chamber 50 of the slave cylinder 42 and the low pressure return pressure line 30 is restored. The cylinder piston 44 is retracted against the spring bias due to the higher pressure in the lower chamber 25 of the actuator 20. This movement of the slave cylinder piston 44 absorbs fluid from the lower chamber 25 of the actuator 20 equal to the swept volume of the slave cylinder piston 44. The supply pressure 27 acting upon the uppermost chamber 88 of the actuator 20 compensates for this fluid loss by moving the piston 21 in the actuator 20 down proportionally. This results in incremental distinct movement of the actuator 20. When the closing slave cylinder piston 44 fully retracts, the system is set for the next operation.
Fast Close Function
The incorporation of a fast close system can be integrated in the open/close circuits described above. A pilot operated check valve 74 is provided in a line 80 connecting supply line circuit 29 at a point between the solenoids 54, 56 and the slave cylinders 31, 42. Pilot valve 74 is connected to the pilot valve 72 which in turn is located in the fast close line 70 between the middle chamber 86 and the lower chambers 25 of the actuator 20. In this way pressure sensed at pilot valve 74 when both solenoids 54, 56 are energized is communicated to the pressure sensing port of the pilot operated check valve 72. The pressure opens pilot valve 72 and allows communication of the fluid from the lower chambers 25 and the middle chamber 86 of the actuator 20 through connection of the fast close line 70 with the low pressure return line circuit 30. The pressure supply 27 connected directly to the uppermost chamber 88 closes the actuator 20.
Variations/Extensions
The invention extends to variations of these systems which will be evident to those skilled in the art, including without limitation.
A manual override extension, whether it be rotary or hydraulic, may be provided.
All publications mentioned in this specification are indicative of the level of skill in the art of this invention. All publications are herein incorporated by reference to the same extent as if each publication was specifically and individually indicated to be incorporated by reference.
The terms and expressions in this specification are, unless otherwise specifically defined herein, used as terms of description and not of limitation. There is no intention, in using such terms and expressions, of excluding equivalents of the features illustrated and described, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4147325 | McGee | Apr 1979 | A |
| 4540022 | Cove | Sep 1985 | A |
| 4723474 | Flohr | Feb 1988 | A |
| 4774980 | Etheridge | Oct 1988 | A |
| 5074519 | Pettus | Dec 1991 | A |
| 5211241 | Mashaw, Jr. et al. | May 1993 | A |
| 5316084 | Murray et al. | May 1994 | A |
| 5431188 | Cove | Jul 1995 | A |
| 6179052 | Purkis et al. | Jan 2001 | B1 |
| 6327956 | Rink | Dec 2001 | B1 |
| 6422317 | Williamson, Jr. | Jul 2002 | B1 |
| 6450255 | Carmody et al. | Sep 2002 | B2 |
| 6470970 | Purkis et al. | Oct 2002 | B1 |
| 6484800 | Carmody et al. | Nov 2002 | B2 |
| 6543544 | Schultz et al. | Apr 2003 | B2 |
| 6575237 | Purkis et al. | Jun 2003 | B2 |
| 6585051 | Purkis et al. | Jul 2003 | B2 |
| 6585227 | Newport et al. | Jul 2003 | B2 |
| 6612547 | Carmody et al. | Sep 2003 | B2 |
| 6668936 | Williamson, Jr. et al. | Dec 2003 | B2 |
| 6691587 | King | Feb 2004 | B1 |
| 6722439 | Garay et al. | Apr 2004 | B2 |
| 6736213 | Bussear et al. | May 2004 | B2 |
| 6782949 | Cove et al. | Aug 2004 | B2 |
| 6782952 | Garay et al. | Aug 2004 | B2 |
| 7003949 | Fenny et al. | Feb 2006 | B2 |
| 20030048197 | Purkis et al. | Mar 2003 | A1 |
| 20040069491 | Garay et al. | Apr 2004 | A1 |
| 20040216884 | Bodine et al. | Nov 2004 | A1 |
| 20040216888 | Schmidt et al. | Nov 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 2398715 | Aug 2001 | CA |
| 2401888 | Nov 2004 | GB |
| WO 9947788 | Sep 1999 | WO |
| WO 0190532 | Nov 2001 | WO |
| WO 0220941 | Mar 2002 | WO |
| WO 2004033849 | Apr 2004 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20060192160 A1 | Aug 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60535555 | Jan 2004 | US |
