A servo valve comprises a first spool extending along a first spool axis, a second spool extending along a second spool axis, a first piezoelectric actuator, and a second piezoelectric actuator. The first piezoelectric actuator is operatively connected to the first spool for translating the first spool in response to a voltage applied thereto. The second piezoelectric actuator is operatively connected to the second spool for translating the second spool in response to a voltage applied thereto.

A spool valve including a spool having a plurality of land portions; a sleeve having the spool housed such that the spool is movable in an axial direction and has an input port and an output port and small-diameter portions in the interior of the sleeve. The pressure and flow rate of a fluid passing between the land portions and the small-diameter portions are adjusted by movement of the spool; a plurality of adjustment portions formed as spaces between the small-diameter portions of the sleeve and the land portions of the spool overlapping with each other from a radial direction of the spool; and a guide portion constituted by the small-diameter portion and the land portion which define one of the adjustment portions having a cross-sectional area smaller than each of cross-sectional areas of adjacent two of the adjustment portions having the input port interposed therebetween in the axial direction.

A spool valve including a spool having a plurality of land portions; a sleeve having the spool housed such that the spool is movable in an axial direction and has an input port and an output port and small-diameter portions in the interior of the sleeve. The pressure and flow rate of a fluid passing between the land portions and the small-diameter portions are adjusted by movement of the spool; a plurality of adjustment portions formed as spaces between the small-diameter portions of the sleeve and the land portions of the spool overlapping with each other from a radial direction of the spool; and a guide portion constituted by the small-diameter portion and the land portion which define one of the adjustment portions having a cross-sectional area smaller than each of cross-sectional areas of adjacent two of the adjustment portions having the input port interposed therebetween in the axial direction.

A metering valve has a shutoff position at which it blocks flow from the metering valve outlet line from reaching an outlet to a use. A spool has a first end and a second end. The housing has a first shoulder associated with the first end and a second shoulder associated with the second end. In the shutoff position, the spool has the first end spaced from the first shoulder, and the second end spaced from the second shoulder. A fuel system for a gas turbine engine is also disclosed.

A spool valve for controlling the flow of a fluid into a reciprocating piston cylinder. A spool is slideably inserted into an outer casing, the spool valve having a first and a second non-waisted end portions and having a waisted middle portion. The casing has an intake port and output port for fluids entering and exiting the casing. A first non-waisted end portion covers the intake port during a first valve-closed event as the spool slides in one direction within the casing. The waisted middle portion is sufficiently wide to uncover both the intake port and the output port during a valve-open event as the spool slides in one direction within the casing. A second non-waisted end portion covers the output port during a second valve-closed event as the spool slides in the same one direction within the casing.

A spool valve for controlling the flow of a fluid into a reciprocating piston cylinder. A spool is slideably inserted into an outer casing, the spool valve having a first and a second non-waisted end portions and having a waisted middle portion. The casing has an intake port and output port for fluids entering and exiting the casing. A first non-waisted end portion covers the intake port during a first valve-closed event as the spool slides in one direction within the casing. The waisted middle portion is sufficiently wide to uncover both the intake port and the output port during a valve-open event as the spool slides in one direction within the casing. A second non-waisted end portion covers the output port during a second valve-closed event as the spool slides in the same one direction within the casing.

A controllable gas-storage-form gas supply tube device includes a three way tube having a first opening, a second opening and a third opening; an electric control valve device installed in the three way tube for controlling connections of the three openings; an input tube, a close form air storage tube and a draining tube are connected to the first, second and third openings, respectively. When the electric control valve device is at a first position, the third opening is closed and the first and second openings are communicated so that gas from the input tube flows to the close form air storage tube and is stored therein. When the electric control valve device is at a second position, the first opening is closed, and the second and third openings are communicated so that gas in the close form air storage tube flow to the draining tube.

A hydraulic oil control valve is coaxially disposed with a rotational axis of a valve timing adjustment device. The hydraulic oil control valve includes a sleeve and a spool that is slidably moved in an axial direction within the sleeve in a radial direction. The sleeve includes an inner sleeve disposed radially outside of the spool and an outer sleeve defining an axial hole extending in the axial direction. The inner sleeve is inserted into the axial hole. The outer sleeve is fixed to an end portion of one shaft when an axial force is applied to the outer sleeve in the axial direction. An inner sleeve end portion of the inner sleeve in the axial direction away from the actuator protrudes from the outer sleeve away from the actuator in the axial direction.

A hydraulic oil control valve is coaxially disposed with a rotational axis of a valve timing adjustment device. The hydraulic oil control valve includes a sleeve and a spool that is slidably moved in an axial direction within the sleeve in a radial direction. The sleeve includes an inner sleeve disposed radially outside of the spool and an outer sleeve defining an axial hole extending in the axial direction. The inner sleeve is inserted into the axial hole. The outer sleeve is fixed to an end portion of one shaft when an axial force is applied to the outer sleeve in the axial direction. An inner sleeve end portion of the inner sleeve in the axial direction away from the actuator protrudes from the outer sleeve away from the actuator in the axial direction.

A valve device for controlling a fluid flow, in particular an air flow, having at least one inlet and at least two outlets, at least one of the outlets being fluidically connectable in each case to the inlet via a through-channel of at least one manipulable guide means. The through-channel of the guide means can be changed at least indirectly via a control fluid flow either with regard to at least a section of its internal cross section or can be rotated at least to a limited extent with regard to its orientation with respect to the outlets and the inlet can be rotated at least to a limited extent.