Abstract: A torque motor has a mechanical reference member, an armature, and a field assembly. The field assembly includes field pole pieces defining a pole opening, and the armature is mounted to the mechanical reference member for rotation about a motor axis and extends into the pole opening with respective gaps to the field pole pieces. The field assembly is secured to the mechanical reference member and spaced therefrom by elastically deformable flexures, deformed sufficiently to locate the armature at a predetermined position within the pole openings with corresponding lengths of the gaps. During manufacture, a load can be applied to move the field assembly relative to the mechanical reference member against the deformation force of the flexures to locate the pole opening relative to the armature pole piece such that the gaps of desired lengths are formed.

Abstract: A torque motor has a mechanical reference member, an armature, and a field assembly. The field assembly includes field pole pieces defining a pole opening, and the armature is mounted to the mechanical reference member for rotation about a motor axis and extends into the pole opening with respective gaps to the field pole pieces. The field assembly is secured to the mechanical reference member and spaced therefrom by elastically deformable flexures, deformed sufficiently to locate the armature at a predetermined position within the pole openings with corresponding lengths of the gaps. During manufacture, a load can be applied to move the field assembly relative to the mechanical reference member against the deformation force of the flexures to locate the pole opening relative to the armature pole piece such that the gaps of desired lengths are formed.

Abstract: Provided is a servovalve system for regulating fluid flowing within a fluid circuit. The servovalve system comprises a housing, a spool slidably disposed within the housing, a stepper motor operatively connected to the spool, and a controller and a position sensor electronically connected to the stepper motor. The controller generates driver signals representative of a desired amount of stepper motor rotation in order to cause the stepper motor to effectuate spool motion relative to the housing. The position sensor senses an actual amount of stepper motor rotation and generates a quantity of position signals representative thereof. The controller determines a signal ratio of the quantity of the position signals to the quantity of the driver signals and generates a diagnostic signal when the signal ratio reaches a threshold value representative of a predetermined level of mechanical resistance of spool motion relative to the housing.

Abstract: Provided is a servovalve system having a fail safe apparatus adapted for switching the servovalve system between an operating position and a fail safe position. The servovalve system comprises a housing having a housing bore and a housing chamber, a spool moveably disposed within the housing, and a stepper motor connected to the spool and configured to vary the spool position for manipulating the fluid flowing within a fluid circuit when the servovalve system is placed in the operating position. A rotary-linear converter converts rotational motion of the stepper motor into axial motion of the spool. The fail safe apparatus includes a piston slidably sealed within the housing chamber and mechanically coupled to the rotary-linear converter. The piston is operative to move the spool from the operating position to the fail safe position upon a loss of fluid pressure in the housing chamber.

Abstract: Provided is a servovalve system having a fail safe apparatus adapted for switching the servovalve system between an operating position and a fail safe position. The servovalve system comprises a housing having a housing bore and a housing chamber, a spool moveably disposed within the housing, and a stepper motor connected to the spool and configured to vary the spool position for manipulating the fluid flowing within a fluid circuit when the servovalve system is placed in the operating position. A rotary-linear converter converts rotational motion of the stepper motor into axial motion of the spool. The fail safe apparatus includes a piston slidably sealed within the housing chamber and mechanically coupled to the rotary-linear converter. The piston is operative to move the spool from the operating position to the fail safe position upon a loss of fluid pressure in the housing chamber.

Abstract: A rotary two-way servovalve provides a continuously variable orifice size in response to an input rotation while minimizing actuation torque. The valve is comprised of a cylindrical spool which is fitted to and rotates within a bore in a body. Fluid is fed into an axial hole in the spool through an inlet groove and cross holes and is metered out through one of a pair of diametrically opposed metering slots depending upon the angle of rotation. The second slot is provided to balance the pressure forces on the spool. Other features are a pivot which provides the axial location of the spool in the body while also sealing the spool, and a drain hole to prevent pressure from moving the spool axially. The valve is intended to be driven by an electrical rotary actuator such as a step motor, servo motor, or a limited angle torque motor.

Abstract: A rotary two-way servovalve provides a continuously variable orifice size in response to an input rotation while minimizing actuation torque and providing an orifice area, and thus flow, proportional to the input rotational angle. The valve is comprised of a cylindrical spool which is fitted to and rotates within a bore in a body. An axial hole in the spool terminates at one end and is closed at the other end by a plug. An inlet groove at one location along the outside of the spool communicates through radial holes with the axial hole, and this inlet groove is fed fluid under pressure from an inlet hole in the body. A cross hole, which also intersects the axial hole, feeds high pressure fluid to an opposed pair of outlet slots, one of which is positioned to intersect with an outlet port in the body to varying degrees, depending on the angular position of the spool. The second, identical, outlet slot faces the opposite side of the bore so as to balance the side loads on the spool from varying pressures.

Abstract: A control system is provided for a limited angle torque motor used as a rotary position control device. A motor for which the system is intended would consist of a rotor and a stator. The system uses an analog Hall-effect sensor to sense the position of the rotor. Rather than attempting to shield the Hall-effect sensor from the influences of magnetic fields generated by the field windings in the stator during motor operation, the system allows the output signal from the Hall effect sensor to contain elements of both the angular position and the extraneous magnetic field generated by the field windings of the motor. Current feedback from a circuit which independently senses the motor current is then combined with this signal to eliminate the influence of the motor coil magnetic field. The system is applicable to a number of limited angle torque motor designs.

Abstract: A rotary servovalve having a cylindrical spool (18), which rotates through a limited angle, positioned within a housing (16). The spool and housing have transverse holes through both parts with matching position and diameter. The holes in the housing form cylinder ports (21) and (24) for connection to a load. A metering pin (22) is fixed in the opening in the spool and its end surfaces conform to the surface of the spool. These end surfaces block the opposed load ports (21) and (24) when the valve is in the null position. Fluid under pressure and exhaust are applied through the inlet port (20) and return (11) ports to circumferential grooves (23) and (25) on opposite sides of the metering pin, which are narrower than the diameter of the pin. When the spool is rotated, pressure is connected to one of the load ports and return to the opposite port and the resulting flow is proportional to the angle of rotation.

Abstract: An integrated compliance electrohydraulic servovalve system connected to a load such as a simulated living being to provide more realistic movement thereto. The system includes a pressure transducer for sensing the pressure appearing at the output of the electrohydraulic servovalve and which is applied to an actuator connected to the load. The pressure as sensed is developed into a corresponding electrical signal which is used as a feed back signal to the drive motor of the electrohydraulic servovalve. The actuator position signal is also provided and is summed with the position command input signal to provide the command signal which is also summed with the pressure signal prior to application to the drive motor. The utilization of the pressure feed back signal provides compliance to the over all system resulting in a realistic movement of the simulated living being.

Abstract: An integrated compliance electrohydraulic servovalve system connected to a load such as a simulated living being to provide more realistic movement thereto. The system includes a pressure transducer for sensing the pressure appearing at the output of the electrohydraulic servovalve and which is applied to an actuator connected to the load. The pressure as sensed is developed into a corresponding electrical signal which is used as a feed back signal to the drive motor of the electrohydraulic servovalve. The actuator position signal is also provided and is summed with the position command input signal to provide the command signal which is also summed with the pressure signal prior to application to the drive motor. The utilization of the pressure feed back signal provides compliance to the over all system resulting in a realistic movement of the simulated living being.

Abstract: A control valve including a second stage spool for controlling flow of fluid from a source thereof to a load. The valve includes one additional pressure slot and one additional return slot on each side thereof and separated by a land on the spool from the usual pressure and return slots respectively. Each of the spool lands separating the pressure and return slots defines and opening therethrough to interconnect the slots so that upon movement of the spool to connect the source to the load, a greater flow of fluid is provided and would be possible with the same size spool without the additional pressure and return slots.

Abstract: A method of manufacturing a moving coil force motor particularly adapted for utilization with a hydraulic servovalve. The method includes aligning a flexure spring with respect to the permanent magnet structure and thereafter securing the permanent magnet structure and flexure spring within a case for the force motor. Subsequently, the coil structure is aligned with respect to the gap provided in the permanent magnet pole pieces by relatively moving the motorcase with respect to the coil until the appropriate position is attained and thereafter securing the case against further movements.