Abstract: An electric actuator of the present invention includes a hydraulic fluid supply device and an actuator actuated in response to an input of hydraulic fluid from a variable-volume pump. The hydraulic fluid supply device includes an adjustable-speed motor, the variable-volume pump which is driven by the adjustable-speed motor and ejects hydraulic fluid, an electric motor control unit which controls the adjustable-speed motor so as to achieve an intended rotation speed, and a pump control unit which controls the variable-volume pump so that the ejection volume of the variable-volume pump decreases with an increase in the ejection pressure of the variable-volume pump.

Abstract: An electric actuator of the present invention includes a hydraulic fluid supply device and an actuator actuated in response to an input of hydraulic fluid from a variable-volume pump. The hydraulic fluid supply device includes an adjustable-speed motor, the variable-volume pump which is driven by the adjustable-speed motor and ejects hydraulic fluid, an electric motor control unit which controls the adjustable-speed motor so as to achieve an intended rotation speed, and a pump control unit which controls the variable-volume pump so that the ejection volume of the variable-volume pump decreases with an increase in the ejection pressure of the variable-volume pump.

Abstract: Each permanent magnet formed in an open-letter shape is divided into a plurality of parts, the divided magnets are respectively fitted in open letter-shaped inserting portions, and ribs are respectively provided in dividing portions of the permanent magnets. Accordingly, it is possible to prevent the breakage of pole connecting portions at an outermost periphery of the rotor as adjacent inner peripheral-side permanent magnets directly come into contact with and push the outer peripheral-side permanent magnets. Alternatively, an annular nonmagnetic material is provided on an outer peripheral portion of the rotor so as to cover the open letter-shaped permanent magnets and magnetic material portions inside the open-letter portions, whereby the rotor core is made resistant against breakage, and the flux leakage is minimized.

Abstract: Each permanent magnet formed in an open-letter shape is divided into a plurality of parts, the divided magnets are respectively fitted in open letter-shaped inserting portions, and ribs are respectively provided in dividing portions of the permanent magnets. Accordingly, it is possible to prevent the breakage of pole connecting portions at an outermost periphery of the rotor as adjacent inner peripheral-side permanent magnets directly come into contact with and push the outer peripheral-side permanent magnets. Alternatively, an annular nonmagnetic material is provided on an outer peripheral portion of the rotor so as to cover the open letter-shaped permanent magnets and magnetic material portions inside the open-letter portions, whereby the rotor core is made resistant against breakage, and the flux leakage is minimized.

Abstract: An electromagnetic force motor comprising: a magnetic housing having a housing chamber formed therein; a stationary magnetic member received in the housing chamber in stationary relationship with respect to the magnetic housing; a movable magnetic member received in the housing chamber to be movable with respect to the stationary magnetic member, the stationary magnetic member, and the movable magnetic member forming with a magnetic flux gap to permit a magnetic flux to pass therethrough, the magnetic housing, the stationary magnetic member, and the movable magnetic member each made of a magnetic substance and collectively forming a magnetic circuit unit that is to allow a magnetic flux to pass therethrough; a permanent magnet positioned in the housing chamber and generating a magnetic flux; and an electromagnetic coil positioned in the housing chamber and generating a magnetic flux with an electric current imparted thereto, the magnetic circuit unit partly having a diminished cross-sectional area being small