A piezoelectric ring bender servo valve assembly reduces mechanical wear by removing mechanical components used in prior art servo valves. The assembly does not use torque motor, flapper, and feedback spring. In this manner, no moving parts are required, which reduces maintenance and costs. A pair of piezoelectric ring benders mount adjacently to a pair of nozzles. The piezoelectric ring benders independently regulate the flow of fluid through the nozzles by moving between an open position to enable flowage, and a closed position to restrict flowage. A linear position sensing device measures and provides feedback about the spool position to a valve controller. The valve controller allows the spool valve to move until valve position achieves command position and the force on the spool valve is in equilibrium with pressure difference across spool valve. An H-bridge operable to switch the polarity of a differential pressure applied across to a load.

A pressure compensated solenoid valve with fluid flow force balancing is provided. The solenoid valve includes an armature and a valve plunger arranged to transport hydraulic fluid from a supply end of a valve plunger to an upper end of the armature facilitating a resultant upper fluid force that acts upon the upper end of the armature to balance a resultant lower fluid force that acts on the supply end of the valve plunger. The solenoid valve includes a poppet that is configured as a pressure-relief valve for maintaining a minimum fluid pressure within an actuation fluid gallery. An inlet fluid force of the poppet is balanced by an outlet fluid force of the poppet.

An example valve includes: a housing having a first longitudinal cavity therein; a sleeve disposed, at least partially, in the first longitudinal cavity, where the sleeve has a second longitudinal cavity therein, and includes a first seat formed as a protrusion from an interior peripheral surface of the sleeve; a poppet mounted within the second longitudinal cavity and configured to move axially therein; and a bushing mounted, at least partially, in the second longitudinal cavity, such that the bushing is floating and is allowed to move axially in the second longitudinal cavity, where the bushing is hollow and defines a first port at a distal end of the bushing and defines a second seat at a proximal end of the bushing, and where the sleeve defines a second port and a third port disposed on an exterior peripheral surface of the sleeve.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port and a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal. The servovalve also includes a jet pipe assembly configured to direct fluid to the ends of the spool to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The jet pipe assembly comprises a jet pipe a connector header fluidly connecting the jet pipe to a nozzle. The spool has one or more openings 28 is provided in the spool such that fluid from the supply port flows into the interior of the spool and into the jet pipe.

An example valve includes: a piston movable between a neutral position and an actuated position, wherein in the neutral position: a second port of the valve is fluidly coupled to a first port, and a third port is fluidly decoupled from the second port; a solenoid actuator sleeve movable between an unactuated state and an actuated state, wherein in the actuated state, the solenoid actuator sleeve allows pilot fluid to apply a fluid force on a piston in a distal direction; a first feedback spring; and a second feedback spring disposed in series with the first feedback spring, wherein the first feedback spring and the second feedback spring cooperate to apply a biasing force in a proximal direction on the piston against the fluid force, wherein the piston is configured to move to the actuated position based on a relationship between the fluid force and the biasing force.

An example valve includes: a piston movable between a neutral position and an actuated position, wherein in the neutral position: a second port of the valve is fluidly coupled to a first port, and a third port is fluidly decoupled from the second port; a solenoid actuator sleeve movable between an unactuated state and an actuated state, wherein in the actuated state, the solenoid actuator sleeve allows pilot fluid to apply a fluid force on a piston in a distal direction; a first feedback spring; and a second feedback spring disposed in series with the first feedback spring, wherein the first feedback spring and the second feedback spring cooperate to apply a biasing force in a proximal direction on the piston against the fluid force, wherein the piston is configured to move to the actuated position based on a relationship between the fluid force and the biasing force.

To obtain an electromagnetic actuator capable of improving a thrust force of a movable element. Provided is an electromagnetic actuator, including: a stator, which has a first surface at one end in an axial direction and a second surface at another end in the axial direction, and is made of a soft magnetic material having a tubular space formed in the axial direction; and a movable element, which is disposed in the tubular space, and is configured to move along the axial direction, wherein the stator includes: a coil; a core portion; and a protrusion portion, wherein the movable element includes a movable element core made of a soft magnetic material and a permanent magnet, and wherein at least one of a radially inner side and a radially outer side of the permanent magnet is covered by a movable element core.

An example valve includes: a piston movable between a neutral position and an actuated position, wherein in the neutral position: a second port of the valve is fluidly coupled to a first port, and a third port is fluidly decoupled from the second port; a solenoid actuator sleeve movable between an unactuated state and an actuated state, wherein in the actuated state, the solenoid actuator sleeve allows pilot fluid to apply a fluid force on a piston in a distal direction; a first feedback spring; and a second feedback spring disposed in series with the first feedback spring, wherein the first feedback spring and the second feedback spring cooperate to apply a biasing force in a proximal direction on the piston against the fluid force, wherein the piston is configured to move to the actuated position based on a balance between the fluid force and the biasing force.

A servovalve includes a fluid transfer valve assembly comprising a supply port and a control port, a moveable valve spool arranged to regulate flow of fluid from the supply port to the control port in response to a control signal, and a drive assembly configured to axially move the valve spool relative to the fluid transfer assembly in response to the control signal to regulate the fluid flow. The drive assembly includes a steerable member moveable by an amount determined by the control signal to cause corresponding movement of the valve spool. The drive assembly further includes piezoelectric actuator means configured to move said steerable member in response to the control signal.

A piezoelectric ring bender servo valve assembly reduces mechanical wear by removing mechanical components used in prior art servo valves. The assembly does not use torque motor, flapper, and feedback spring. In this manner, no moving parts are required, which reduces maintenance and costs. A pair of piezoelectric ring benders mount adjacently to a pair of nozzles. The piezoelectric ring benders independently regulate the flow of fluid through the nozzles by moving between an open position to enable flowage, and a closed position to restrict flowage. A linear position sensing device measures and provides feedback about the spool position to a valve controller. The valve controller allows the spool valve to move until valve position achieves command position and the force on the spool valve is in equilibrium with pressure difference across spool valve. An H-bridge operable to switch the polarity of a differential pressure applied across to a load.