A pilot actuator is disclosed for use with a valve. The pilot actuator may have a cage with a base end and a tip end, and a pilot bore formed in the cage. The pilot actuator may also have a supply port, a drain port, a first end port, and a second end port each formed in the cage and intersecting with the pilot bore. The pilot actuator may further have a pilot spool slidingly disposed in the pilot bore and movable to selectively connect the supply port and the drain port with the first and second end ports, a follower separate from the cage and disposed at the tip end of the cage, and at least one spring operatively connecting the follower to the cage and to the pilot spool.

An electronic regulator includes an inlet valve coupled to an inlet port, the inlet port configured to receive a supply pressure, and an exhaust valve coupled to an exhaust port, the exhaust port configured to release a pilot pressure when the exhaust valve is open. The electronic regulator also includes a pilot pressure output pneumatically coupled to the inlet valve and exhaust valve and configured to be coupled to an external process control device to provide the pilot pressure to the external process control device. A setpoint input coupled to both the inlet valve and the exhaust valve receives a setpoint signal indicative of a setpoint value, and the electronic regulator operates the inlet valve and the exhaust valve to control the pilot pressure according to the setpoint value. Further, the electronic regulator includes a vent valve coupled to a venting port and pneumatically coupled to the pilot pressure output. The venting port is configured to release the pilot pressure according to the safety control signal.

Methods and apparatus to bias spool valves using supply pressure are disclosed. An example apparatus includes a housing of a spool valve, the housing including a first port to receive a fluid at a supply pressure. The example apparatus further includes a spool within the housing. A position of the spool is to be selectively controlled via an input force acting on the spool, the position of the spool to define a path of a flow of the fluid through the spool valve from the first port to a second port of the housing. A biasing force is to bias the spool opposite the input force, the biasing force to be generated from the supply pressure applied to an end of the spool.

An oil control valve assembly includes a valve body and a controller coupled to an exterior end of the valve body. The controller includes a solenoid housing attached to the exterior end of the valve body, and defines an interior region. An encapsulated coil assembly is disposed within the interior region of the solenoid housing. A housing seal is disposed within the interior region of the solenoid housing, in sealing engagement with the solenoid housing, the valve body, and the encapsulated coil assembly. The housing seal is operable to seal the interior region of the solenoid housing to prevent fluid communication between the solenoid housing and the valve body. An adapter assembly is coupled to the valve body to reposition a discharge location of a supply port, a control port, and an exhaust port of the valve body along a longitudinal axis of the valve body.

In an electromagnetic proportional control valve system, left and right position control apparatuses 20 and 30 are disposed on the both ends of a main spool in a three position proportional control valve 10 and perform stroke control for the main spool. The left and right position control apparatus respectively comprise position feedback springs 25 and 35, pilot control valves 21 and 31, and proportional solenoids 27 and 37. The pilot spool is moved, for operative control, in response to a compression force of a position feedback spring and an electromagnetic force of the proportional solenoid. In addition, the output pressure is applied to both ends of the pilot spool so that control is performed to generate output pressure with a negative characteristic against the electromagnetic force of the proportional solenoids.

A solenoid valve includes a housing including a channel, a single-acting through hole, a double-acting through hole, a spring biased spool in the channel, a lateral outlet communicating with the double-acting through hole, and a hole element passing through an edge of the channel to communicate with both the double-acting through hole and the channel; a switch on the housing and including an axial tunnel, a shaft in the tunnel, a lateral single-acting hole communicating with the tunnel, a double-acting hole communicating with the tunnel, and a linking hole perpendicular to the tunnel but not communicating therewith; a pilot valve on the switch; a base at a bottom of the housing, and a spring biased check valve at a lower opening of the housing and the base, the check valve communicating with the single-acting through hole.

The externally fitted control device includes an electronic control module (1), a hydraulic control module (2) and a common control enclosure (3). The hydraulic control module (2) has electromagnetic actuators (10) and control pistons (14) which are positioned on top of one another to result in a compact design which is safe to operate and can be manufactured economically.