Abstract: A rotary drive apparatus including a frame having at least three holes; a yoke having a center portion and two side bar portions on opposite sides of the center portion, the center portion having a hole, coils mounted on the side bar portions of the yoke, a collar having a bore and being tightly mounted on the surface of the hole of the yoke, magnetic parameter changing elements being mounted on the surface of the bore of the collar, and a rotor having magnetic poles in the radial direction and being inserted into the bore of the collar with a predetermined clearance. In the apparatus, a first hole of the frame is parallel to a first direction of the apparatus and has a cross-section for tightly receiving the center portion of the yoke, and a second and third holes of the frame are in a second direction perpendicularly intersecting the first direction and being concentric with each other oppositely the first hole, the center portion of the yoke being fit into the first hole.

Abstract: A rotary solenoid actuator for proportionally controlling the flow of fluid, such as air, in a pipe comprises a housing with a rotor rotatably mounted thereon. A stationary coreless coil for generating a magnetic field in response to a control current therethrough is mounted in the housing. A permanent magnet is affixed to a rotatably mounted shaft within the coil, and a return spring is attached to the rotating shaft. Due to low hysteresis in the coreless coil, there is a linear relationship between the control current and the fluid flow.

Abstract: A rotary actuator for driving a fluid control valve comprises a yoke which forms a closed magnetic path an excitation coil which produces a magnetic flux in the yoke, a permanent magnet which is rotatably arranged in a through hole or in a slit formed in the yoke, and a restoring spring which produces a force acting against a rotational torque generated in the magnet by a main magnetic flux which flows through the yoke and the permanent magnet when the excitation coils is energized. Shielding portions are formed on both sides of the ends of the yoke, which ends oppose the permanent magnet, so as to substantially shield the permanent magnet together with the ends of the yoke, whereby a magnetic reluctance of a path of the magnetic flux remains substantially constant irrespective of the rotating position of the permanent magnet with respect to the yoke when the excitation coil is de-energized.

Abstract: A rotation driving device is constructed from a bobbin, a coil wound on the bobbin, a stator inserted in the bobbin, and a permanent magnet arranged inside the stator. The stator consists of a hollow cylindrical body having a first, second, and third recesses. In accordance with the command electrical signal supplied to the coil, the rotation driving device changes the rotational position of the rotor.

Abstract: A valve apparatus of a solenoid drive type having a valve member in a housing defining an inlet port and first and second outlet ports. The valve member connects the inlet port to the second outlet port while closing the first outlet port when no electric current is received by the apparatus. The valve member controls the opening of the first outlet port while maintaining the second outlet port closed when an electric current larger than a predetermined offset value is applied to the apparatus. When the electric current is equal to the offset value, the valve member closes both the first and the second outlet ports.

Abstract: An EGR device for an internal combustion engine, including an EGR valve body in an EGR pipe for changing the opening degree of the EGR pipe for regulating the amount of the recirculated exhaust gas, a diaphragm supported by casing of the EGR valve and connected to the EGR valve body for forming a negative pressure chamber, and a solenoid fixed to a sleeve of one of the casing for driving a spool valve in the direction to the diaphragm when the solenoid is excited. The excitation of the solenoid is controlled by a control circuit in accordance with the running conditions of the internal combustion engine.

Abstract: A rotary solenoid motor adapted for use in a flow control valve apparatus. The solenoid motor having a shaft on which a valve member is connected. A torsion bar is connected between the shaft and a housing for generating a torsional force opposite to an electro-magnetic force. The shaft and the housing has a pair of portions for fixing the torsion bar. Each of the portions forms a regular polygonal cross-sectional shape.

Abstract: An electric actuator including a stationary housing, an output shaft rotatably supported by the housing, an output member mounted on said output shaft, an electric motor secured to the housing, speed reduction gear mechanism for reducing the rotational speed of the electric motor, differential gear mechanism provided between the output shaft and the speed reduction gear mechanism, an electromagnetic brake operatively connected to the differential gear mechanism. The differential gear mechanism includes an output side differential gear secured to the output shaft, and a brake side differential gear rotatable with a brake plate of the electromagnetic clutch.

Abstract: A rotary actuator for imparting a rotational force to a rotary valve member of a multi-way valve device has a cylindrical housing and an electric motor housed therein and being operative to produce a torque corresponding to the input current supplied to the motor. The motor shaft is hollow and rotatably journalled by the end walls of the motor housing. A torsion bar is housed in the shaft and fixed at one end to one end of the shaft. The other end of the torsion bar is fixed to the housing so that, when rotational force is imparted by the motor to the shaft and thus the rotary valve member connected thereto, the torsion bar produces a return force applied to the shaft. The angular position of the other end of the torsion bar about the axis thereof is adjustable within a limited range. The actuator is suited to impart a rotational motion of less than 180.degree. and provides a reduced hysteresis in the rotation characteristics.