Patent Description:
Power-operated valve actuators convert a driving force such as pneumatic pressure, hydraulic pressure, or electricity into a linear or rotational motion. Such actuators are coupled to the shaft or stem of an associated valve such that the motion generated by the actuator is imparted to the valve's shaft or stem and thus modulates the position of a connected valve member between open and closed positions to control the flow of fluid through a conduit in which the valve is installed.

An electro-hydraulic valve actuator uses two types of driving force - electricity and hydraulic pressure - to generate motion that is imparted to an associated valve. In particular, an electro-hydraulic actuator utilizes electrical energy to pump hydraulic fluid and to control the flow of the hydraulic fluid within a self-contained hydraulic circuit. The hydraulic fluid imparts a force on one or more moveable components within the hydraulic circuit to generate the motion that drives a connected valve. The present invention is related to improved control circuitry to control the flow of hydraulic fluid through the hydraulic circuit.

<CIT> describes an apparatus for continuously controlling the movement and force exerted by a tool throughout a work cycle of the tool. The apparatus comprises a fluid-operated squeeze circuit having means for changing the direction of fluid flow and for varying fluid pressure in response to electrical command signals, fluid-operated squeeze cylinders in fluid communication with said squeeze circuit and operatively coupled to the tool enabling the tool to engage, squeeze and disengage a workpiece during a work cycle in response to the pressure and flow direction of fluid in said squeeze circuit, and an electrical command circuit coupled to said squeeze circuit for establishing the operations of the tool during a work cycle for generating electrical squeeze command and squeeze decompression signals controlling fluid pressure in said squeeze circuit, and generating electrical switching command signals changing fluid flow direction in said squeeze circuit effecting engagement, squeezing and disengagement of a workpiece by the tool.

<CIT> describes a method of regulating the pressure in an accumulator to obtain a pressure therein which lies between two predetermined values using a variable-displacement pump driven by an internal combustion engine to charge the accumulator.

<CIT> describes an electro-hydraulic control device for an hydraulic load which operates in two directions. The device comprises a control valve having a control valve spool arranged to block two load lines when in a neutral position and to alternately connect each load line to an inlet conduit and a return conduit when in two working positions. The control valve comprises a control piston housed in a control cylinder which is in the form of a double-acting cylinder having two feed lines, being arranged to actuate the control valve spool. The control valve comprises electromagnetically actuable pilot control valves being arranged to, feed pressure medium to the control cylinder, two pilot control valves being arranged to connect the two feed lines to the inlet conduit and return conduit of the control cylinder, each of the pilot control valves being operable by respective magnet windings which are controlled by respective switching amplifiers connected to the output of a control amplifier by way of respective threshold value switches.

<CIT> describes an electro-hydraulic valve actuator having a modular manifold assembly with a network of channels that fluidly connect a hydraulic cylinder assembly to a hydraulic power assembly. The hydraulic cylinder assembly includes a piston rod that can directly or indirectly open or close a process valve. The hydraulic power assembly has a main pump and motor, and the manifold assembly includes a main manifold block to which is mounted the hydraulic cylinder assembly and the main pump and motor. The main manifold block has pluggable channel ports that can be unplugged to provide fluid communication with corresponding channel ports of at least one auxiliary manifold block that can be mounted to and integrated with the main manifold block. The at least one auxiliary manifold block has either a second pump and motor or a manual override pump.

<CIT> describes a hydraulic drive for executing a linear movement includes a motor, a pump, a lifting cylinder having the one linearly movable piston and a cylinder housing with at least one first connection and at least one second connection, a spring arranged such that the piston can be extended or retracted when the spring is in the relaxed state, and at least one first valve with which the first connection and the second connection of the cylinder housing can be fluidly connected. At least one second valve connected in parallel with the first valve is further provided, wherein the first valve has a maximum volumetric throughflow which is greater than the maximum volumetric through-flow of the second valve.

<CIT> describes a fault management apparatus for a system that includes at least one electro-mechanical or electro-hydraulic component. An actuator is electrically coupled to the component. A standby power supply stores sufficient electrical energy to energize the valve and/or discharge pump. The actuator can be actuated in a number of different ways. Logic circuitry is programmed to sense the external conditions which require shutdown of the system, using the energy stored in the standby power supply.

<CIT> describes a control system for a combination valve for a hydraulic system which comprises an electronic control module, an electronic system controller, a remote power module, and a solenoid valve. The electronic control module monitors torque output of an internal combustion engine and an electric motor and generator. The electronic system controller is in electrical communication with the electronic control module. The electronic system controller monitors torque demand of a first hydraulic circuit of a hydraulic system and a second hydraulic circuit of the hydraulic system. The remote power module is in electrical communication with the electronic system controller. The solenoid valve is in electrical communication with the remote power module. The solenoid valve connects to a combination valve and has a first open position and a closed position. The combination valve is in fluid communication with a first hydraulic circuit and a second hydraulic circuit.

According to claim <NUM>, there is provided a control circuitry for a system that comprises a hydraulic valve actuator, comprising one or more input channels that are each configured to receive an operational command; one or more user-selectable inputs configured to be representative of a configuration of the valve actuator; a motor output that is configured to cause a motor that is coupled to a hydraulic fluid pump to run; one or more valve outputs that are each configured to control an open or closed state of an associated valve wherein each of the one or more valves is configured to control a flow of hydraulic fluid within the system; and a plurality of physical logic gates configured to be responsive to at least signals received at the one or more input channels and the one or more user-selectable inputs to determine a state of the motor output and the one or more valve outputs. The one or more input channels may include one or more local input channels and one or more remote input channels, and the circuitry may further include a mode selector input channel that is configured to receive a signal that indicates whether the system is controlled via local signals at the one or more local input channels or remote signals at the one or more remote input channels. Such control circuitry may additionally include a multiplexer that is configured to pass the local signals or the remote signals to the plurality of physical logic gates based upon a state of a mode selector signal at the mode selector input channel.

The control circuitry may additionally include one or more system status input channels. The one or more system status input channels may be configured to receive signals that are representative of at least one of an indication that a valve that is coupled to the actuator is open, an indication that the valve that is coupled to the actuator is closed, and an indication that a pressure within a hydraulic chamber of the valve actuator is above a threshold.

One of the user-selectable inputs may be a resistance of a variable resistor. An output of a first one of the physical logic gates may be coupled to an input of a second one of the physical logic gates via a first path through the variable resistor and a second path through a diode, where the first path and the second path are in parallel. Such circuitry may further include a capacitor that is charged by a control voltage via the first path and the second path when an output of the first one of the physical logic gates is in a first state. The capacitor may discharge through the first path and not the second path when the output of the first one of the physical logic gates is in a second state such that the resistance of the variable resistor determines a rate of discharge of the capacitor. The first path may provide a first delay time for a transition of the input of the second one of the physical logic gates to the first state and the second path may provide a second delay time, which is adjustable by a user via the variable resistor, for a transition of the input of the second one of the physical logic gates to the second state.

The one or more user-selectable inputs include one or more inputs configured to indicate whether the valve actuator is configured as double-acting or single-acting. The one or more user-selectable inputs further include one or more inputs configured to indicate whether the single-acting actuator is configured as spring-to-open or spring-to-close. The one or more inputs to indicate whether a single-acting actuator is configured as spring-to-open or spring-to-close may affect the motor output.

An electro-hydraulic valve actuator system may include a hydraulic valve actuator; a hydraulic fluid circuit that includes hydraulic fluid conduit, a hydraulic fluid reservoir, one or more controllable valves that direct flow through the hydraulic fluid conduit, and one or more hydraulic fluid pumps; and the control circuitry as provided above.

<FIG> illustrates an electro-hydraulic actuator system <NUM> that includes an actuator <NUM> that is driven by hydraulic pressure that is conveyed via hydraulic conduit that makes up a hydraulic circuit. The actuator <NUM> in <FIG> is configured for a single-acting (i.e., hydraulic fluid operates to move the actuator and associated valve in a single direction), spring-to-close configuration with an emergency shutdown (ESD) feature and an accumulator <NUM> that may allow the associated valve to be stroked (a limited number of times) without operating the hydraulic pump <NUM> (e.g., upon electrical failure that prevents operation of the pump <NUM>) and/or provide a volume for thermal expansion of hydraulic fluid. The illustrated configuration may be setup for two-wire (open/close (+V) and common), three-wire (open (+V), close (+V), and common), or four-wire (open (+V), close (+V), stop (+V), and common) operation. The actuator <NUM> includes a hydraulic chamber <NUM> that is fluidly coupled to the hydraulic circuit. The hydraulic chamber <NUM> houses a piston <NUM> with each side of the piston <NUM> coupled to a different portion of the hydraulic circuit. The piston <NUM> is coupled to a shaft <NUM> and is configured to move within the chamber <NUM>.

The shaft <NUM> extends from the hydraulic chamber <NUM> to a spring chamber <NUM>. The spring chamber <NUM> houses a spring <NUM> that is disposed between a wall <NUM> of the spring chamber <NUM> and a spring seat <NUM> that is attached to an end of the shaft <NUM>. In this position, the spring <NUM> exerts a force that operates to move the shaft <NUM> in the close direction (toward the right in the view shown in <FIG>). Thus, in the absence of an opposing force operating on the piston <NUM>, the spring <NUM> will move the shaft <NUM> in the close direction.

Between the hydraulic chamber <NUM> and the spring chamber <NUM>, the shaft <NUM> is coupled to a scotch-yoke mechanism <NUM>. The scotch-yoke mechanism <NUM> converts the linear motion of the shaft <NUM> into rotational motion of a connector <NUM>, which is oriented orthogonally to the shaft <NUM> and coupleable to the shaft of an associated valve. For example, when the shaft <NUM> moves in the close direction, the scotch-yoke mechanism <NUM> converts that linear motion into a clockwise rotational motion (from the view in <FIG>) of the connector <NUM>. Likewise, when the shaft <NUM> moves in the open direction, the scotch-yoke mechanism <NUM> converts that linear motion into a counterclockwise rotational motion (from the view in <FIG>) of the connector <NUM>. In a typical configuration, the full linear range of motion of the shaft <NUM> would correspond to a <NUM> degree rotation of the connector <NUM>, which would actuate a quarter-turn valve (e.g., a butterfly or ball valve) between the open and closed positions.

The hydraulic circuit includes a manifold <NUM> that has a first power port P1, a second power port P2 (not used and plugged in the configuration shown in <FIG>), a cylinder port C, a gauge port G, and a reservoir port R. The cylinder port C is coupled by a first line C-<NUM> to a first chamber 102A of the hydraulic cylinder <NUM> as well as to the accumulator <NUM>. A line C-<NUM> is coupled between line C-<NUM> and a manual pump assembly <NUM>. The manual pump assembly <NUM>, which has a suction line R-<NUM> that is connected to a hydraulic fluid reservoir <NUM> (note that while multiple reservoir symbols are shown in <FIG>, they are all representative of a common reservoir <NUM>) and discharges to line C-<NUM>, enables the actuator <NUM> to be operated by manually pumping hydraulic fluid into line C-<NUM> in the event of the failure of the pump <NUM>. For purposes of simplicity, the features of the manual pump assembly <NUM> are not described in detail, but it is important to note that check valves within the assembly <NUM> prevent the flow of hydraulic fluid from the line C-<NUM> to the line R-<NUM> but enable the flow of hydraulic fluid from the line R-<NUM> to the line C-<NUM>. A second chamber 102B of the hydraulic cylinder <NUM> is coupled to the reservoir <NUM> via a line R-<NUM>.

A main pump <NUM> has a suction line R-<NUM> that is connected to the reservoir <NUM> and a discharge line P-<NUM> that is connected to the manifold <NUM> P1 port. Within the manifold, the P1 port is coupled via a line P-<NUM> to a line C-<NUM>, which is in turn coupled to the manifold <NUM> C port. The P-<NUM> line is further connected via two two-way solenoid valves <NUM>, <NUM> operating in parallel to the manifold <NUM> P2 and R ports. The R port is coupled to the reservoir <NUM> via line R-<NUM>. The closing solenoid valve <NUM> is a directional valve that prevents flow from the P1 and C ports to the R port in a de-energized state and permits flow from the P1 and C ports to the R port in an energized state. The ESD solenoid valve <NUM> permits flow from the P1 and C ports to the R port in a de-energized state and prevents flow from the P1 and C ports to the R port in an energized state. Manual control valves <NUM> that are located on the P1 and C port side of each solenoid valve <NUM>, <NUM> enable the rate of flow through each solenoid valve <NUM>, <NUM> to be limited to adjust the opening and closing speed of the valve. The P-<NUM> and C-<NUM> lines, as well as the lines and components that are connected thereto, are protected by a relief valve <NUM> that relieves pressure to the R port (and thus the reservoir <NUM> via the R-<NUM> line) in the event of an over-pressure condition. A check valve <NUM> prevents backflow from any of the connected lines within the manifold <NUM> to the P1 port. A manual valve <NUM> that is positioned between the P1 and C ports and the manual valves <NUM> is useable in conjunction with the manual pump assembly <NUM>. A pressure switch <NUM> that is coupled to the C-<NUM> line is triggered when the pressure in the first chamber 102A and the accumulator <NUM> exceeds a set value. Such pressure is indicated via a pressure gauge <NUM> that is connected to the G port, which is in turn connected to the C-<NUM> line by the G-<NUM> line.

In operation, when an open command is issued to the electro-hydraulic actuator system <NUM>, the ESD solenoid valve <NUM> is energized and the closing solenoid valve <NUM> is de-energized to prevent the flow of hydraulic fluid from the P1 and C ports to the R port and the motor <NUM> is energized to drive the pump <NUM>. Hydraulic fluid from the reservoir <NUM> is thus drawn from the reservoir by the pump <NUM> and transferred to the first chamber 102A. The pressure of the hydraulic fluid within the first chamber 102A operates on the area of the piston <NUM> to generate a force in the open direction, which overcomes the opposing force provided by the spring <NUM> to move the piston <NUM> and the shaft <NUM> in the open direction. As the piston <NUM> moves within the chamber <NUM>, any fluid within the second chamber 102B will be exhausted to the reservoir <NUM>. When the valve reaches the fully open position, an open limit switch that is indicative of an open state of the associated valve (not shown) and that is wired to the control circuitry of the electro-hydraulic actuator system <NUM> indicates that the valve has fully traveled to the desired position. If the electro-hydraulic actuator system <NUM> is configured without the accumulator <NUM>, the open limit switch indication is utilized by the control circuitry to de-energize the motor <NUM> and thus stop the pump <NUM>. However, to ensure that the accumulator <NUM> is fully charged (assuming the accumulator <NUM> is used for a backup source of power to operate the valve in the event of a pump or power failure and not just for thermal compensation), the control circuitry of the electro-hydraulic actuator system <NUM> continues to energize the motor <NUM> until the pressure switch <NUM> indicates that the high pressure limit has been met, at which point the motor <NUM> is de-energized. Note that to maintain the valve in the open position, the ESD solenoid valve <NUM> is continuously maintained in the energized state and the closing solenoid is maintained in the de-energized state.

When a close command is issued to the electro-hydraulic actuator system <NUM>, the closing solenoid <NUM> is energized, which creates a path between the P1 and C ports and the R port and thus couples the first chamber 102A with the reservoir <NUM>. In this state, the force of the spring <NUM> moves the shaft <NUM> in the close direction, exhausting the hydraulic fluid in the first chamber 102A through the manifold <NUM> to the reservoir <NUM>. Note that because the close command is in the spring direction, the motor <NUM> is not energized. When the valve reaches the fully closed position, a closed limit switch that is indicative of a closed state of the associated valve (not shown) and that is wired to the control circuitry of the electro-hydraulic actuator system <NUM> indicates that the valve has fully traveled to the desired position. The closed limit switch indication is utilized by the control circuitry to de-energize the closing solenoid <NUM>. If the accumulator <NUM> is of a type that may be utilized to stroke the valve in the event of a pump or power failure, it will include valving that prevents the fluid in the accumulator <NUM> from draining to the reservoir <NUM>.

While the illustrated electro-hydraulic actuator system <NUM> is shown in a spring-to-close configuration, it can also be configured in a spring-to-open configuration. In a spring-to-open configuration, the spring <NUM> drives the shaft <NUM> in the valve open direction. In such a configuration, it will be understood that the control circuitry must respond differently to open and close commands than in the spring-to-close configuration (e.g., to energize the motor <NUM> in response to a close command and to energize an opening solenoid that is akin to the closing solenoid <NUM> in response to a closing command).

<FIG> illustrates a double-acting configuration of an electro-hydraulic actuator system <NUM>'. The double-acting configuration shown in <FIG> is largely similar to the spring return configuration shown in <FIG> and components that serve similar functions bear the same labels as used in <FIG>. The primary distinction between the configurations of the system <NUM> in <FIG> and <FIG> is the absence of the spring chamber <NUM> from the configuration in <FIG>. In the double-acting configuration shown in <FIG>, the movement of the shaft <NUM> and connector <NUM> is determined according to the balance of pressures of hydraulic fluid operating on each side of the piston <NUM> in the hydraulic chamber <NUM>. Therefore, the hydraulic arrangement and control circuitry must be modified such that hydraulic fluid is delivered to the appropriate chamber 102A, 102B of the hydraulic chamber <NUM> in response to the various operational commands delivered to the system <NUM>'.

Within the manifold <NUM>, the ESD solenoid valve <NUM> is replaced by an opening solenoid valve <NUM>. Both the opening solenoid valve <NUM> and the closing solenoid valve <NUM> are three-way solenoid valves that couple the chambers 102A, 102B to either the reservoir <NUM> or the pump <NUM>'s discharge based upon the electrical state of the solenoid valve <NUM>, <NUM>. A shuttle valve <NUM> prevents backflow from the chamber 102A, 102B that is coupled to the pump <NUM>'s discharge to the reservoir <NUM> through the de-energized solenoid valve <NUM>, <NUM>.

When an open command is issued to the electro-hydraulic actuator system <NUM>', the opening solenoid valve <NUM> is energized, the closing solenoid valve <NUM> is de-energized, and the motor <NUM> is energized to drive the pump <NUM>. In this configuration, the opening solenoid valve <NUM> couples the P1 port to the C1 port and the closing solenoid valve <NUM> couples the C2 port to the R port. The pressure differential across the shuttle valve <NUM> (i.e., the pump <NUM> discharge pressure on the valve <NUM> side as compared to the lower reservoir <NUM> pressure on the valve <NUM> side) prevents backflow from the chamber 102A to the reservoir <NUM> through the valve <NUM>. Hydraulic fluid is drawn from the reservoir <NUM> by the pump <NUM> and transferred to the first chamber 102A. The pressure of the hydraulic fluid within the first chamber 102A operates on the area of the piston <NUM> to generate a force in the open direction. Because the chamber 102B is coupled through the closing solenoid valve <NUM> to the low-pressure reservoir <NUM>, the force on the piston <NUM> in the open direction provided by the hydraulic fluid within the chamber 102A exceeds the force on the piston <NUM> in the closed direction provided by the hydraulic fluid within the chamber 102B, which causes the piston <NUM> to move in the open direction. As the piston <NUM> moves within the chamber <NUM>, any fluid within the second chamber 102B is exhausted to the reservoir <NUM>. When the valve reaches the fully open position, the valve's open limit switch indicates that the valve has fully traveled to the open position. Because the electro-hydraulic actuator system <NUM>' is configured without an accumulator <NUM>, the open limit switch indication is utilized by the control circuitry to de-energize the motor <NUM> and thus stop the pump <NUM> and to de-energize the opening solenoid valve <NUM>. In this state, the chambers 102A, 102B are fluidly coupled to the reservoir <NUM>. As a result, the forces operating on the piston <NUM> in both directions are equal, and the shaft <NUM>, connector <NUM>, and valve are maintained in the open position.

When a closed command is issued to the electro-hydraulic actuator system <NUM>', the closing solenoid valve <NUM> is energized, the opening solenoid valve <NUM> is de-energized, and the motor <NUM> is energized to drive the pump <NUM>. In this configuration, the closing solenoid valve <NUM> couples the P1 port to the C2 port and the closing solenoid valve <NUM> couples the C1 port to the R port. The pressure differential across the shuttle valve <NUM> (i.e., the pump <NUM> discharge pressure on the valve <NUM> side as compared to the lower reservoir <NUM> pressure on the valve <NUM> side) prevents backflow from the chamber 102B to the reservoir <NUM> through the valve <NUM>. Hydraulic fluid is drawn from the reservoir <NUM> by the pump <NUM> and transferred to the second chamber 102B. The pressure of the hydraulic fluid within the second chamber 102B operates on the area of the piston <NUM> to generate a force in the close direction. Because the chamber 102A is coupled through the opening solenoid valve <NUM> to the low-pressure reservoir <NUM>, the force on the piston <NUM> in the close direction provided by the hydraulic fluid within the chamber 102B exceeds the force on the piston <NUM> in the open direction provided by the hydraulic fluid within the chamber 102A, which causes the piston <NUM> to move in the close direction. As the piston <NUM> moves within the chamber <NUM>, any fluid within the first chamber 102A is exhausted to the reservoir <NUM>. When the valve reaches the fully closed position, the valve's closed limit switch indicates that the valve has fully traveled to the closed position. Because the electro-hydraulic actuator system <NUM>' is configured without an accumulator <NUM>, the closed limit switch indication is utilized by the control circuitry to de-energize the motor <NUM> and thus stop the pump <NUM> and to de-energize the closing solenoid valve <NUM>. In this state, the chambers 102A, 102B are fluidly coupled to the reservoir <NUM>. As a result, the forces operating on the piston <NUM> in both directions are equal, and the shaft <NUM>, connector <NUM>, and valve are maintained in the closed position.

<FIG> illustrates a double-acting configuration of an electro-hydraulic actuator system <NUM>" that includes an accumulator <NUM> and an ESD solenoid valve <NUM>. The configuration <NUM>" shown in <FIG> is nearly identical to the configuration <NUM>' shown in <FIG>. However, in addition to the components in the configuration <NUM>', the configuration <NUM>" includes an accumulator <NUM> that is coupled to the P2 port of the manifold <NUM>. The accumulator <NUM> is coupled through a control valve <NUM> (which can be adjusted to alter the opening and closing speed of the associated valve when the accumulator is utilized to stroke the valve) to the lines C-<NUM> and C-<NUM>. In normal operation, the accumulator is isolated from lines C-<NUM> and C-<NUM> by manual three-way valves <NUM> and <NUM>, respectively, which permit flow along lines C-<NUM> and C-<NUM> but prohibit flow from the accumulator <NUM> to lines C-<NUM> and C-<NUM> in normal operation. When the valve <NUM> is opened to permit flow from the accumulator <NUM> to the line C-<NUM>, hydraulic fluid from the accumulator <NUM> enters the chamber 102A and operates on the piston <NUM> to move the piston <NUM> and the shaft <NUM> and connector <NUM> in the open direction, exhausting any fluid from chamber 102B to the reservoir <NUM>. Likewise, when the valve <NUM> is opened to permit flow from the accumulator <NUM> to the line C-<NUM>, hydraulic fluid from the accumulator <NUM> enters the chamber 102B and operates on the piston <NUM> to move the piston <NUM> and the shaft <NUM> and connector <NUM> in the close direction, exhausting any fluid from chamber 102A to the reservoir <NUM>. A manual accumulator isolation valve <NUM> enables the accumulator <NUM> to be isolated from the manifold <NUM> (with a pressure switch <NUM> monitoring the P-<NUM> line pressure on the accumulator <NUM> side of the valve <NUM>). A manual accumulator drain valve <NUM> enables the accumulator <NUM> to be drained.

A three-way ESD solenoid valve <NUM> is coupled to the accumulator <NUM> (assuming the isolation valve <NUM> is in its normal, open state) via line P-<NUM> and P-<NUM>. In normal operation, the ESD solenoid valve <NUM> is energized, which decouples the accumulator <NUM> from the hydraulic chamber <NUM> (unless one of the valves <NUM>, <NUM> is used to stroke the valve via the accumulator). In the event of an emergency shutdown or a loss of power to the system <NUM>", the ESD solenoid valve <NUM> transitions to the de-energized state, which permits fluid flow from the accumulator <NUM> through the ESD solenoid valve <NUM>. In this state, the shuttle valve <NUM> permits flow from the ESD solenoid valve <NUM> to the port C4 but prevents flow from the ESD solenoid valve <NUM> to the port C3. The hydraulic pressure in the accumulator <NUM> thus flows from port C4 through lines C-<NUM> and C-<NUM> to chamber 102B, which again creates a pressure imbalance on the piston <NUM> and moves the piston <NUM> and the shaft <NUM> and connector <NUM> in the close direction to close the valve. Note that while there is a path from port C4 to the reservoir <NUM> through a de-energized closing solenoid valve <NUM>, a plug <NUM> in such path ensures that the hydraulic fluid is directed to the chamber 102B to drive the valve to the closed position. While the illustrated version of the system <NUM>" is configured such that hydraulic fluid from the accumulator <NUM> operates to close the valve when the ESD solenoid valve <NUM> is de-energized, in yet another alternative configuration the system may be configured such that he accumulator <NUM> operates to open the valve when the ESD solenoid valve <NUM> is de-energized.

As can be understood from the different configurations of the electro-hydraulic actuator system <NUM> shown in <FIG>, a number of different variables - spring return or double-acting, inclusion of a failsafe emergency shutdown mechanism, inclusion of an accumulator - impact the operation of the system <NUM> and require that control circuitry is properly configured to match the selected configuration. In addition, in any configuration, commands to the system <NUM> can be configured for two-wire operation (open and ESD signals), three-wire operation (open, close, and ESD signals), and four-wire operation (open, close, stop, and ESD signals), with such operations including maintained or momentary commands (i.e., the command to a particular state may either be maintained as an ON signal or toggled to an ON signal momentarily before transitioning back to an OFF signal). Moreover, alternate configurations having additional controllable instruments (e.g., additional valves and/or pump motors) are possible. The permutations of these various configurations require numerous different wiring arrangements to ensure proper operation for the selected configuration, which in turn makes field modifications to change the configuration difficult for users. Accordingly, the inventors recognized a need to develop standardized control circuitry that functions across different configurations of the electro-hydraulic actuator system <NUM> through simple switch selections and without complex wiring modifications.

<FIG> is a wiring diagram that illustrates the connection of the components of an electro-hydraulic actuator system <NUM> to an example control interface <NUM>. The control interface <NUM> includes input and output channels (which, in the illustrated embodiment, comprise terminal blocks) that are configured to receive and provide signals for controlling the operation of the system <NUM>. In addition, the control interface <NUM> includes multiple user-selectable inputs (e.g., DIP switches SW1-SW4 and timer inputs R2 and R4) that are representative of a configuration of the system <NUM>. In the illustrated embodiment, the pump motor <NUM> is a three-phase AC motor that is powered from terminals L1, L2, and L3. It will be understood that a different type (e.g., single phase or DC) motor may also be used. Terminals L1 and L2 additionally supply terminals H1 and H2 of terminal block P2 of the control interface <NUM>, which are coupled to the primary side of a power supply. Various taps on the secondary side of the power supply provide operating power that is utilized by the control circuitry (e.g., rectified to 12V and 24V DC power). In other embodiments, control circuitry operating power may be separately supplied to the interface <NUM> and not generated from the pump motor supply. For example, 24V DC and/or 12V DC power may be separately supplied to the control interface <NUM>.

The P6 terminal block of the interface <NUM> is utilized to wire the pressure switch <NUM> input and the outputs to the opening solenoid valve <NUM>, the closing solenoid valve <NUM>, and the motor <NUM> contactor. In particular, the motor <NUM> contactor output is wired across terminals <NUM> and <NUM> of the P6 terminal block, the opening solenoid valve <NUM> is wired across terminals <NUM> and <NUM> of the P6 terminal block (with instrument ground wired to terminal <NUM>), the closing solenoid valve <NUM> is wired across terminals <NUM> and <NUM> of the P6 terminal block (with instrument ground wired to terminal <NUM>), and the pressure switch <NUM> input is wired in series with the supply to the motor <NUM> contactor with the feedback wired to terminal <NUM> of the P6 terminal block.

The P8 terminal block of the interface <NUM> receives the remote input commands to the system <NUM>. In particular, terminals <NUM>-<NUM> of the P8 terminal block (i.e., the remote input channels) are configured to receive the remote open, close, and stop commands to the system <NUM>, respectively. The ESD input is wired across terminals <NUM> and <NUM> of the P8 terminal block. Terminals <NUM> and <NUM> of the P8 terminal block receive the 24V DC internal power supply voltage and terminals <NUM> and <NUM> of the P8 terminal block receive the common node voltage of the internal 24V power supply. When terminal <NUM> of the P8 terminal block is coupled to the common node voltage (e.g., via a jumper connected between terminals <NUM> and <NUM> of the P8 terminal block), the open and close commands are enabled for momentary configuration (i.e., a transition from OFF to ON and back to OFF will be registered as a command to go to the particular state).

Referring to <FIG>, the remote open, close, and stop commands can be wired for either internal or external power and in one of two-wire, three-wire, and four-wire configurations. As noted above, the installation of a jumper across terminals <NUM> and <NUM> of the P8 terminal block converts the remote open and close commands to momentary configuration in the three-wire and four-wire configurations. In the two-wire configuration, the remote open contact <NUM> is wired in a maintained arrangement with the open input (terminal <NUM>) energized to indicate a command to open and de-energized to indicate a command to close. For internal power, the internal 24V DC power source is supplied from terminal <NUM> of the P8 terminal block to terminals <NUM> and <NUM> (the close and stop inputs) of the P8 terminal block and also through the remote open contact <NUM> to terminal <NUM> of the P8 terminal block. For external power, an external power source <NUM> is wired between terminals <NUM> and <NUM> of the P8 terminal block in series with the remote open contact <NUM>. The internal 24V DC power source is supplied from terminal <NUM> to terminals <NUM> and <NUM> (the close and stop inputs) of the P8 terminal block.

In the three-wire configuration, the remote open contact <NUM> and the remote close contact <NUM> are wired with the open input (terminal <NUM>) energized to indicate a command to open and the close input (terminal <NUM>) energized to indicate a command to close. For internal power, the internal 24V DC power source is supplied from terminal <NUM> of the P8 terminal block through the remote open contact <NUM> to terminal <NUM> of the P8 terminal block and through the remote close contact <NUM> to terminal <NUM> of the P8 terminal block as well as directly to terminal <NUM> (the stop input) of the P8 terminal block. For external power, an external power source <NUM> supplies power through the remote open contact <NUM> and the remote close contact <NUM> in parallel to terminals <NUM> and <NUM>, respectively, of the P8 terminal block. The internal 24V DC power source is supplied from terminal <NUM> to terminal <NUM> (the stop input) of the P8 terminal block.

In the four-wire configuration, the remote open contact <NUM>, the remote close contact <NUM>, and the remote stop contact <NUM> are wired with the open input (terminal <NUM>) energized to indicate a command to open, the close input (terminal <NUM>) energized to indicate a command to close, and the stop input (terminal <NUM>) de-energized to indicate a command to stop. For internal power, the internal 24V DC power source is supplied from terminal <NUM> of the P8 terminal block through the remote open contact <NUM>, the remote close contact <NUM>, and the remote stop contact <NUM> in parallel to terminals <NUM>, <NUM>, and <NUM>, respectively, of the P8 terminal block. For external power, an external power source <NUM> supplies power through the remote open contact <NUM>, the remote close contact <NUM>, and the remote stop contact <NUM> in parallel to terminals <NUM>, <NUM>, and <NUM>, respectively, of the P8 terminal block.

The ESD contact <NUM> must be made (i.e., closed) to keep the ESD solenoid <NUM> energized. For internal power, the internal 24V DC power source is supplied from terminal <NUM> of the P8 terminal block through the ESD contact <NUM>, and the 24V DC power source common node voltage is wired from terminal <NUM> to terminal <NUM> of the P8 terminal block. For external power, an external power source <NUM> is wired in series with the ESD contact <NUM> across terminals <NUM> and <NUM> of the P8 terminal block.

Returning to <FIG>, the ESD solenoid valve <NUM> is wired across the P10 terminal block and either the P11 or P12 terminal block. When wired across the P10 and P12 terminal blocks, the ESD solenoid valve <NUM> is wired directly in series with the ESD contact <NUM>. When wired across the P10 and P11 terminal blocks, the ESD solenoid valve <NUM> is wired in series with the ESD contact <NUM> as well as a normally open (NO) power failure contact of a local relay having its coil energized by the 24V DC internal power supply voltage. In this configuration, the ESD solenoid valve <NUM> will be de-energized not only when the ESD contact <NUM> is open but also when a failure of the internal 24V DC power supply de-energizes the relay to open the NO power failure contact.

The P4 terminal block receives signals wired through the open limit switch <NUM> and closed limit switch <NUM> that indicate the fully open and fully closed positions, respectively, of the valve that is actuated by the system <NUM>. In particular, the open limit switch <NUM> is wired across terminals <NUM> and <NUM> of the P8 terminal block and the closed limit switch <NUM> is wired across terminals <NUM> and <NUM> of the P4 terminal block. Terminals <NUM> and <NUM> of the P4 terminal block provide internal 24V DC power to the open limit switch <NUM> and the closed limit switch <NUM>, respectively. The return signal from the open limit switch <NUM> is wired to terminal <NUM> of the P4 terminal block, terminal <NUM> of the P7 terminal block, the local close indicator light <NUM>, and to terminal <NUM> of the P7 terminal block, which is referenced to the internal 24V DC power supply common node voltage. The return signal from the closed limit switch <NUM> is wired to terminal <NUM> of the P4 terminal block, terminal <NUM> of the P7 terminal block, the local open indicator light <NUM>, and to terminal <NUM> of the P7 terminal block. When the valve is at either limit, the limit switch will be open, which will cause the opposite indicator light (i.e., the close indicator light <NUM> when the valve reaches the open limit switch <NUM>) to be OFF. When the valve is traveling (i.e., is not in either the fully open or fully closed position), both of the indicator lights <NUM>, <NUM> will be illuminated. The P5 and P9 terminal blocks are used to enable remote monitoring of various components of the system <NUM>, such as limit switch status, pressure switch status, hand/off/auto switch status, etc..

The P7 terminal block additionally provides internal 24V power to the local switch module <NUM>, which is located near the actuator <NUM>, from its terminal <NUM>. The local switch module <NUM> includes a hand/off/auto (HOA) switch <NUM>, a normally-closed stop switch <NUM>, a normally-open close switch <NUM>, and a normally-open open switch <NUM>, which are wired to local mode selector input channels of the P7 terminal block (i.e., terminals <NUM>-<NUM> of the P7 terminal block).

The S1 contact of the HOA switch <NUM> is made when the HOA switch <NUM> is placed in the HAND state, which gives control of the actuator <NUM> to the commands issued via the local switch module <NUM>. The S2 contact of the HOA switch <NUM> is made when the HOA switch <NUM> is placed in the AUTO state, which gives control of the actuator <NUM> to the commands issued via the remote open, close, and stop contacts that are wired to the P8 terminal block. The local stop switch <NUM> is wired in series with the S1 contact of the HOA switch <NUM> across terminals <NUM> and <NUM> of the P7 terminal block. When the HOA switch <NUM> is placed in the HAND state and the stop switch <NUM> is in the normal (i.e., not stop) state, there will be 24V at terminal <NUM> of the P7 terminal block. The S2 contact of the HOA switch <NUM> is wired across terminals <NUM> and <NUM> of the P7 terminal block. When the HOA switch <NUM> is placed in the AUTO state, there will be 24V at terminal <NUM> of the P7 terminal block. The local close switch <NUM> and the local open switch <NUM> are wired in parallel with each other and in series with the S1 contact of the HOA switch <NUM>, to terminals <NUM> and <NUM> of the P7 terminal block, respectively. Thus, when the HOA switch <NUM> is placed in the HAND state and the stop switch <NUM> is in the normal (i.e., not stop) state, selecting the closed switch <NUM> will deliver 24V to terminal <NUM> of the P7 terminal block and selecting the open switch <NUM> will deliver 24V to terminal <NUM> of the P7 terminal block.

The interface <NUM> additionally includes multiple user adjustable inputs. Control knobs R2 and R4 enable the user to modify open and close timers, respectively, as will be described in greater detail below. DIP switches SW1-SW4 enable the user to select whether the system <NUM> is configured for spring return with spring fail closed arrangement (switch SW1), spring return with spring fail open arrangement (switch SW2), accumulator included (switch SW3), and motor action upon ESD (switch SW4). The functions of these switches within the control circuitry will be described below.

<FIG> is a control logic diagram that illustrates example standardized control circuitry <NUM> for an electro-hydraulic actuator system <NUM> in accordance with an aspect of this invention. It is important to note that the control circuitry includes a plurality of physical logic gate components as opposed to a more complex and more expensive microcontroller-based system. While various logic gate components are illustrated as separate components, they may actually be combined within a single component. For example, each separate NOR gate may be a different channel of a four-channel NOR gate, etc. For this reason, extra channels of a multi-channel logic gate component are utilized for a different functionality (e.g., an extra channel of a NOR gate may receive the same input at each of its input ports to change the function of a NOR gate to a NOT gate). It will be understood that the logic functionality may be accomplished in ways other than those shown. While not specifically illustrated in <FIG>, the signals that are wired to the interface <NUM> shown in <FIG> are electrically isolated from corresponding logic signals that are utilized within the control circuitry <NUM>. For example, each input to the interface <NUM> may be wired through an opto-isolator that generates a corresponding digital signal at the control logic voltage level (e.g., 5V DC) for use within the control circuitry <NUM>.

The control circuitry <NUM> includes a multiplexer U15 that is configured to route the appropriate open, close, and stop signals (i.e., either remote or local signals) based upon the signal at its A/B input. More specifically, if the signal at the A/B input of the multiplexer U15 is ON, the multiplexer routes the signals at terminals 1B, 2B, 3B, and 4B to terminals 1Y, 2Y, 3Y, and 4Y, respectively. Conversely, if the signal at the A/B input of the multiplexer U15 is OFF, the multiplexer routes the signals at terminals 1A, 2A, 3A, and 4A to terminals 1Y, 2Y, 3Y, and 4Y, respectively. The signal that is connected to the A/B input of the multiplexer U15 corresponds to the S2 contact of the HOA switch <NUM>. So, when the HOA switch <NUM> is set to the AUTO state, the remote open, close, and stop signals (which correspond to the signals received at terminals <NUM>, <NUM>, and <NUM> of terminal block P8, respectively) are routed to the terminals 1Y, 2Y, and 3Y, respectively, of the multiplexer U15. When the HOA switch is set to the HAND or OFF state, the A/B input to the multiplexer U15 will be in the OFF state and the local open, close, and stop signals (which match the signals received at terminals <NUM>, <NUM>, and <NUM> of terminal block P7, respectively) are routed to the terminals 1Y, 2Y, and 3Y, respectively, of the multiplexer U15. Note that the local stop signal (when in the OFF state) may be indicative of either the local stop switch <NUM> being set to the STOP state or the HOA switch <NUM> being set to the OFF state, which are treated as equivalent inputs by the control circuitry <NUM>. When the HOA switch <NUM> is in the OFF state, the HAND and AUTO signals to the NOR gate U1 are both OFF, which results in the input to the G terminal of the multiplexer U15 being set to ON. When the G terminal of the multiplexer U15 receives an ON signal, the outputs 1Y-4Y are all set to OFF, which is equivalent to the receipt of a local or remote stop command.

When an open command is sent to the system <NUM> (either via the local open switch <NUM> or the remote open contact), the terminal 1Y of the multiplexer U15 is ON. This open signal is routed from the multiplexer U15 to an OR gate U14A and a NOR gate U12C. The ON signal at terminal <NUM> of the OR gate U14A ensures that the output at terminal <NUM> of the OR gate U14A will also be ON, regardless of the state of the signal at terminal <NUM> of the OR gate U14A. The output of the U14A gate is routed to terminal <NUM> of a NAND gate U13A. As is known, the output of a NAND gate will be ON if any of its inputs is OFF and will be OFF only when all of its inputs are ON. When the input at terminal <NUM> of the NAND gate U13A is ON to indicate a command to open the valve and the other inputs to the NAND gate U13A are ON to indicate that the system <NUM> is not being commanded to close (terminal <NUM>), not commanded to stop (terminal <NUM>), and the valve is not open (terminal <NUM>), the output at terminal <NUM> of the NAND gate U13A will be OFF. When the output of the NAND gate U13A at terminal <NUM> is OFF, the opening solenoid valve <NUM> is energized.

The output of the NAND gate U13A at terminal <NUM> is additionally routed to the input terminal <NUM> of a NOR gate U12A, which further receives an input at its terminal <NUM> that is indicative of the momentary configuration of inputs. The NOR gate U12A is configured to seal in an open command when the interface <NUM> is configured for momentary inputs (e.g., when a jumper is installed between terminals <NUM> and <NUM> of the P8 terminal block). More specifically, when the interface <NUM> is configured for momentary inputs, the input at terminal <NUM> of the NOR gate U12A is OFF. Thus, when an open command results in the output at terminal <NUM> of the NAND gate U13A transitioning to OFF (to energize the opening solenoid valve <NUM>) and the interface <NUM> is configured for momentary inputs, the ON output at terminal <NUM> of the NOR gate U12A, which output is configured in an OR arrangement with the open command at the 1Y terminal of the multiplexer U15 via the OR gate U14A, ensures that the open command signal that is routed to input terminal <NUM> of the NAND gate U13A will be maintained in the ON state even after the momentary open input transitions back to the OFF state. This sealed in open command will be maintained until the output of the NAND gate U13A transitions back to the ON state.

Once the output of the NAND gate U13A is in the OFF state to energize the opening solenoid valve <NUM>, it is maintained in that state (thus continuing to energize the opening solenoid valve <NUM>) until one of the inputs to the NAND gate U13A transitions to the OFF state. This can occur when the interface <NUM> is configured for maintained inputs and the open command transitions to OFF (terminal <NUM> of NAND gate U13A transitions to the OFF state), when a closed command is received (i.e., the output 2Y of the multiplexer U15 is ON) (terminal <NUM> of NAND gate U13A transitions to the OFF state), when a stop command is received (i.e., the output 3Y of the multiplexer U15 is OFF) (terminal <NUM> of NAND gate U13A transitions to the OFF state), or when the valve has reached the open limit switch <NUM> for a time set by the R2 open timer (terminal <NUM> of NAND gate U13A transitions to the OFF state). The OPEN LIMIT signal that is wired to both inputs of the OR gate U14D matches the status of the open limit switch <NUM>. As illustrated in <FIG>, the open limit switch <NUM> is wired in the normally closed mode such that the switch <NUM> is closed when the valve is not in the open position and the switch <NUM> is open when the valve is in the open position. When the valve is not in the open position, the inputs to both terminals <NUM> and <NUM> of the OR gate U14D are in the ON state, and, consequently the output at terminal <NUM> is also in the ON state. This ON signal is routed via a low impedance path through diode CR7 and resistor R3 (e.g., a 1KΩ resistor) to terminal <NUM> of the NAND gate U13A. This low impedance path ensures that the transition of the limit switch <NUM> from the open valve position to the not open valve position is quickly communicated to the NAND gate U13A. When the output of the OR gate U14D is in the ON state, the capacitor C23, which receives the logic operating voltage (e.g., 5V) across its plates when the output of the OR gate U14D is ON, is charged. In one embodiment, the capacitor C23 may be a 1000µF capacitor, although it will be understood that other types of capacitors might also be used. The R2 resistor is a user-adjustable potentiometer. In one embodiment, the resistance of the R2 potentiometer may be adjusted up to a maximum value of <NUM> KΩ. The resistor R43 provides a relatively lower level of resistance (e.g., 1KΩ). When the valve reaches the open limit switch and the open limit switch transitions from ON to OFF, the output at terminal <NUM> of the OR gate U14D also transitions to OFF. Because the diode CR7 prevents the capacitor <NUM> from discharging through the low impedance path through R3, C23 discharges through R2 and R43. The voltage at the node <NUM> (which is referenced to the input terminal <NUM> of the NAND gate U13A) thus decays in accordance with the series RC time constant that is set by the capacitance of capacitor C23 and the series resistance of potentiometer R2 and resistor R43. Based on an example C23 capacitance of 1000µF and a R2 and R43 series resistance of between 2KΩ and 21KΩ, the voltage at the input terminal <NUM> of the NAND gate U13A can be configured to decay below the ON detection level of the NAND gate U13A between <NUM> and <NUM> seconds after the open limit switch <NUM> is made by adjusting the potentiometer R2 via the interface <NUM>. This is an important feature as it may be difficult to adjust the valve limit switches to correspond exactly to the valve's stroke. If the opening or closing solenoid valve <NUM>,<NUM> is de-energized exactly when the corresponding limit switch <NUM>, <NUM> indicates that the valve has reached the desired position, the valve may not ever make it to the fully open or closed position if the limit switch is set short of the fully open or closed position. The time delay circuitry <NUM>, <NUM> enables the user to set an additional amount of time that the opening and closing solenoid valves <NUM>, <NUM>, respectively, remain energized following the transition of the open and closed limit switches <NUM>, <NUM> indicating that the corresponding state of the valve has been reached.

While the control circuitry logic has been described with respect to an open command to generate a control signal to energize the opening solenoid valve <NUM>, the logic with respect to a closed command to generate a control signal to energize the closing solenoid valve <NUM> is exactly analogous. The U14A, U12D, U13A, U12A, and U14D logic gates correspond to the U14C, U12C, U13B, U12B, and U14B logic gates. Specifically, the output at terminal <NUM> of the NAND gate U13B transitions to the OFF state to energize the closing solenoid valve when a closed command is received (i.e., terminal 2Y of the multiplexer U15 is ON), the valve is not in the closed position, the valve is not commanded to open, and the valve is not commanded to stop. Once the output of the NAND gate U13B is in the OFF state to energize the closing solenoid valve <NUM>, it is maintained in that state (thus continuing to energize the closing solenoid valve <NUM>) until one of the inputs to the NAND gate U13B transitions to the OFF state. This can occur when the interface <NUM> is configured for maintained inputs and the close command transitions to OFF (terminal <NUM> of NAND gate U13B transitions to the OFF state), when an open command is received (i.e., the output 1Y of the multiplexer U15 is ON) (terminal <NUM> of NAND gate U13B transitions to the OFF state), when a stop command is received (i.e., the output 3Y of the multiplexer U15 is OFF) (terminal <NUM> of NAND gate U13B transitions to the OFF state), or when the valve has reached the closed limit switch <NUM> for a time set by the R4 close timer (terminal <NUM> of NAND gate U13B transitions to the OFF state). The time delay circuitry <NUM> is analogous to the time delay circuitry <NUM>.

<FIG> is a control logic diagram that illustrates example standardized control circuitry <NUM> for controlling the output to run the pump <NUM> motor <NUM>. There are multiple permissives that are required to be maintained to run the pump <NUM> motor <NUM>. The permissives include the pressure switch <NUM> not indicating high pressure (terminal <NUM> of NAND gate U11B), no stop command (i.e., output 3Y of multiplexer U15) (terminal <NUM> of NAND gate U11B), and, if the DIP switch SW4 is enabled to cause the motor <NUM> not to run during an emergency shutdown, the ESD contact <NUM> indicating the normal state (i.e., terminal <NUM> of the P8 terminal block is energized) (terminal <NUM> of NAND gate U11B). If any one of these permissives is lost at any time, the pump <NUM> motor <NUM> will not run. If all of these permissives are made, the output at terminal <NUM> of the NAND gate U11B (which causes the motor <NUM>'s contactor to be energized when the MOTOR signal is in the OFF state) is determined based upon the opening and closing solenoid logic as well as the status of the DIP switches SW1-SW3. The OPEN_SOV and CLOSE_SOV control signals (shown in <FIG>) are wired to the NAND gate U11A.

When the OPEN_SOV control signal is in the OFF state to cause the opening solenoid valve <NUM> to be energized, the output of the NAND gate U11A will be in the ON state (which will result in the motor <NUM> being run if the other motor permissives are met) unless the DIP switch SW2 is set to indicate a spring-to-open configuration of the system <NUM>. If the DIP switch SW2 is set to indicate a spring-to-open configuration of the system <NUM>, the terminal <NUM> input to the NAND gate U11A will remain in the ON state despite the OFF state of the OPEN_SOV signal, and the output to the motor <NUM> contactor will not be energized. Thus, by simply setting the DIP switch SW2, the motor <NUM> will not run when the valve is commanded to the open state. Instead, the opening solenoid valve <NUM> will be energized and the spring <NUM> will drive the valve to the open position without operating the pump <NUM>. Likewise, when the CLOSE_SOV control signal is in the OFF state to cause the closing solenoid valve <NUM> to be energized, the output of the NAND gate U11A will be in the ON state (which will result in the motor <NUM> being run if the other motor permissives are met) unless the DIP switch SW1 is set to indicate a spring-to-close configuration of the system <NUM>. If the DIP switch SW1 is set to indicate a spring-to-close configuration of the system <NUM>, the terminal <NUM> input to the NAND gate U11A will remain in the ON state despite the OFF state of the CLOSE_SOV signal, and the output to the motor <NUM> contactor will not be energized. Thus, by simply setting the DIP switch SW1, the motor <NUM> will not run when the valve is commanded to the close state. Instead, the closing solenoid valve <NUM> will be energized and the spring <NUM> will drive the valve to the closed position without operating the pump <NUM>.

If the system <NUM> does not include an accumulator <NUM> (i.e., DIP switch SW3 is open), the motor <NUM>'s contactor will be de-energized to stop the motor <NUM> at the same time that the opening or closing solenoid valve <NUM>, <NUM> is de-energized. However, if the system does include an accumulator <NUM>, the DIP switch SW3 seals in the MOTOR control signal by routing the OFF signal to the input of the NAND gate U11A (terminals <NUM> and <NUM> of NAND gate U11A) to ensure that the transition to the ON state of either OPEN_SOV or CLOSE_SOV signal in conjunction with the de-energization of the opening or closing solenoid valve <NUM>, <NUM> does not cause the output at terminal <NUM> of the NAND gate U11A to transition to the OFF state to stop the motor <NUM> (i.e., via the MOTOR control signal). In the configuration in which the presence of an accumulator <NUM> is indicated by setting the DIP switch SW3, the MOTOR control signal will only return to the ON state upon loss of one of the permissives described above (i.e., high pressure indication from the pressure switch <NUM>, valve stop command, or ESD command with SW4 set to prevent the motor from running during an ESD trip). In normal operation, this means that the motor <NUM> will continue to run the pump <NUM> until the pressure switch <NUM> indicates high pressure, thus ensuring that the accumulator <NUM> remains fully pressurized and ready to function when needed.

While the outputs to the field devices are not specifically shown, it will be understood that such outputs may follow the states of the OPEN_SOV, CLOSE_SOV, and MOTOR control signals. For example, in one embodiment, when each of the OPEN_SOV, CLOSE_SOV, and MOTOR control signals is OFF, a circuit is completed through the LED portions of a closing solenoid opto-isolator, an opening solenoid opto-isolator, and a motor contactor opto-isolator, respectively. The completion of circuits through the LED portions of such opto-isolators may likewise complete a circuit through the isolated circuit portion of the opto-isolators - e.g., to complete a 24V circuit to energize the opening solenoid valve <NUM>, the closing solenoid valve <NUM>, and the motor <NUM> contactor.

Claim 1:
Control circuitry (<NUM>) for a system (<NUM>, <NUM>', <NUM>") that comprises a hydraulic valve actuator (<NUM>), comprising:
one or more input channels that are each configured to receive an operational command;
one or more user-selectable inputs configured to be representative of a configuration of the valve actuator (<NUM>);
a motor output that is configured to cause a motor (<NUM>) that is coupled to a hydraulic fluid pump (<NUM>) to run;
one or more valve outputs that are each configured to control an open or closed state of an associated valve (<NUM>, <NUM>, <NUM>), wherein each of the one or more valves is configured to control a flow of hydraulic fluid within the system; and
a plurality of physical logic gates (U12C, U12D, U13A, U13B, U14A, U14B, U14C, U14D) configured to be responsive to at least signals received at the one or more input channels and the one or more user-selectable inputs to determine a state of the motor output and the one or more valve outputs;
wherein the one or more user-selectable inputs comprise one or more inputs (SW3) configured to to indicate whether the valve actuator is configured as double-acting or single-acting; and
wherein the one or more user-selectable inputs further comprise one or more inputs (SW1, SW2) configured to to indicate whether the single-acting actuator is configured as spring-to-open or spring-to-close.