A spool is slidably located in a slide hole of a first housing. A second housing forms a servo chamber that is coaxial with the slide hole. A sleeve is slidably located in the servo chamber. A nut is fixed to a piston that is slidably fitted in the sleeve. An electric motor rotates a screw shaft screwed with the nut. The second housing includes an input port and a drain port. A first pressure chamber communicates with the input port. In a balanced state where forces applied to the sleeve from both sides are balanced, a second pressure chamber is blocked from the input port and the drain port by the piston. From the balanced state, when the piston shifts, the second pressure chamber comes into communication with the input port or the drain port.

A device for controlling the flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device. The device includes an upstream valve casing defining an inlet, a downstream valve casing defining an outlet aperture, and a valve core secured between the upstream valve casing and the downstream valve casing. The upstream valve casing, the downstream valve casing and the valve core are formed as discrete parts. The valve core includes a housing defining a control volume. The valve member is mounted on the housing and positioned on the upstream side of the outlet aperture, the valve member being arranged to move reciprocally to selectively open and close the outlet aperture, thereby controlling flow of the fluid through the outlet aperture.

A device for controlling the flow of a fluid through a conduit from an upstream side of the device to a downstream side of the device. The device includes an upstream valve casing defining an inlet, a downstream valve casing defining an outlet aperture, and a valve core secured between the upstream valve casing and the downstream valve casing. The upstream valve casing, the downstream valve casing and the valve core are formed as discrete parts. The valve core includes a housing defining a control volume. The valve member is mounted on the housing and positioned on the upstream side of the outlet aperture, the valve member being arranged to move reciprocally to selectively open and close the outlet aperture, thereby controlling flow of the fluid through the outlet aperture.

A diagnosis apparatus for a valve system including a control valve, a servo valve for driving the control valve, and at least one servo module for providing a control signal based on an opening degree command value for the control valve to the servo valve is provided with: at least one opening degree detection part configured to detect an actual opening degree of the control valve; and a diagnosis part configured to acquire, from the opening degree detection part, a detected value of the actual opening degree of the control valve while a diagnostic opening degree command value is input to the at least one servo module, and diagnose an abnormality of the valve system on the basis of the detected value. The diagnostic opening degree command value changes in multiple steps between a maximum opening degree and a minimum opening degree through one or more intermediate opening degrees.

A diagnosis apparatus for a valve system including a control valve, a servo valve for driving the control valve, and at least one servo module for providing a control signal based on an opening degree command value for the control valve to the servo valve is provided with: at least one opening degree detection part configured to detect an actual opening degree of the control valve; and a diagnosis part configured to acquire, from the opening degree detection part, a detected value of the actual opening degree of the control valve while a diagnostic opening degree command value is input to the at least one servo module, and diagnose an abnormality of the valve system on the basis of the detected value. The diagnostic opening degree command value changes in multiple steps between a maximum opening degree and a minimum opening degree through one or more intermediate opening degrees.

An example valve includes: a valve body defining a bore, an inlet port, an outlet port, and a signal cavity; a spool movable in the bore to shift between a first position and an intermediate position, where the spool has a first end and a second end, where the outlet port is fluidly connected to the second end, where the valve body defines a spring cavity adjacent the first end of the spool to house a spring, where the first end is subjected to a load-sense pressure signal, and where when the spool is in the first position, the spool disconnects the inlet port from the outlet port and connects the inlet port to the signal cavity; and a valve actuator that, when activated, connects the signal cavity to the second end of the spool to move the spool in the bore from the first position to the intermediate position.

A waterproof cover includes an operation unit for pressing a manual button of a solenoid valve main body. The operation unit includes a flexible cap, a pin guide interposed between the cap and the solenoid valve main body, and an operation pin that is inserted in guide hole of the pin guide so as to be displaced freely. The cap includes a flexible pressing portion for a pressing operation. One end of the operation pin is in contact with or close to the pressing portion, and the other end of the operation pin is in contact with the manual button.

A valve with an internal member is disclosed which allows exhaled carbon dioxide to escape from a breathing circuit when the circuit gas pressure drops below a threshold pressure. The valve operates by occluding one or more ports under a relatively high pressure and opening the one or more ports under a relatively low pressure. The internal member is attached to the body of the valve at two or more locations on the internal member. The internal member moves in a direction perpendicular to the gas flow through the valve.

A pneumatic pressure regulation valve comprising: a valve inlet; a valve outlet; a piston arranged to control gas flow from the inlet to the outlet; a sense line fluidly connecting the inlet to a pressure regulation chamber and with a pressure relief valve connected thereto to limit the pressure in the pressure regulation chamber; wherein the piston is arranged between the pressure regulation chamber and the valve outlet such that the position of the piston is determined by the relative pressures in the regulation chamber and the valve outlet and the position of the piston controls the flow from the valve inlet to the valve outlet; wherein the sense line comprises a flow restriction upstream of the pressure relief valve. The flow restriction addresses instability that can arise from large volumes of connecting tubes or pipes in the sense line.

A system may comprise a sensor configured to measure a characteristic of an engine component. A valve assembly may have an airflow outlet in fluid communication with the engine component. The valve assembly may include a first valve. A first valve control device may be coupled to the first valve and configured to control the first valve based on a measurement by the sensor. A second valve may be in fluidic series with the first valve. A second valve control device may be coupled to the second valve and configured to control the second valve based on the measurement by the sensor.