A bistable hydraulic solenoid valve has a valve spool that transitions between two positions, remaining in one of the two positions under an attractive magnetic force when the solenoids are not energized. The valve spool has a first permanent magnet attached to one end and a second permanent magnet attached to the other end, so that the first permanent magnet faces a first solenoid, and the second permanent magnet faces a second solenoid. The first solenoid is energized to have a first polarity, and the second solenoid is energized to have an opposite polarity to concurrently push and pull the valve spool within the valve body between a first position and a second position, the first position establishing a first flow path and the second position establishing a second flow path through the valve body and valve spool so as to enable flow of hydraulic fluid.

A jet pipe arrangement for a servo valve, the jet pipe arrangement including a jet pipe, at least two receivers in operable communication with the jet pipe. The jet pip arrangement further includes an electromagnet in direct magnetic communication with the jet pipe such that, in use, the jet pipe is movable in response to changes in a magnetic field created by the electromagnet to distribute flow from the jet pipe asymmetrically between the at least two receivers.

To obtain an electromagnetic actuator capable of improving a thrust force of a movable element. Provided is an electromagnetic actuator, including: a stator, which has a first surface at one end in an axial direction and a second surface at another end in the axial direction, and is made of a soft magnetic material having a tubular space formed in the axial direction; and a movable element, which is disposed in the tubular space, and is configured to move along the axial direction, wherein the stator includes: a coil; a core portion; and a protrusion portion, wherein the movable element includes a movable element core made of a soft magnetic material and a permanent magnet, and wherein at least one of a radially inner side and a radially outer side of the permanent magnet is covered by a movable element core.

In a work machine including a solenoid valve that generates a pilot pressure to drive a directional control valve with use of the delivery pressure of a pilot pump as a source pressure, a shut-off valve that shuts off a hydraulic operating fluid from the pilot pump to the solenoid valve, a first sensor that senses the amount of operation of an operation lever, and a second sensor that senses a state amount relating to operation of the solenoid valve, whether or not an abnormality of the second sensor exists is determined on the basis of a sensing signal of the second sensor. When it is determined that the second sensor is abnormal, on the basis of a sensing signal of the first sensor, an opening command is made to the shut-off valve if operation of the operation lever is sensed, and a closing command is made to the shut-off valve if the neutral state of the operation lever is sensed.

The present invention discloses a drive system of a scraper conveyor and a control method. The drive system includes a nose sprocket, a tail sprocket, a nose sprocket drive mechanism, and a tail sprocket drive mechanism, where the nose sprocket drive mechanism is a hydraulic motor I, and the tail sprocket drive mechanism is a hydraulic motor II; and a hydraulic system that drives the hydraulic motor I and a hydraulic system that drives the hydraulic motor II include same hydraulic elements, and both include a three-position four-way solenoid directional valve, a two-position two-way solenoid directional valve, a two-position three-way solenoid directional valve, an accumulator, and an oil supplement valve group. The present invention is applicable to rapid starting and stopping of the scraper conveyor in a heavy load status while adjusting chain tension in real time, thereby resolving a power imbalance problem in a dual-drive system, and has a simple structure and a long service life.

An example valve includes a first port fluidly coupled to a source of fluid, a second port fluidly coupled to an actuator, a third port fluidly coupled to a reservoir, and a fourth port configured to export a load-sense (LS) fluid signal. The valve can operate in: a neutral state, wherein fluid is allowed to flow from the second port to the third port, while the first port and the fourth port are blocked; a first actuated state, wherein fluid flow is throttled from the second port to the third port, while the first port and the fourth port remain blocked; or a second actuated state, wherein fluid flow from the second port to the third port is blocked, while fluid flow is allowed from the first port to the second port and from the second port to the fourth port.

The present invention discloses a drive system of a scraper conveyor and a control method. The drive system includes a nose sprocket, a tail sprocket, a nose sprocket drive mechanism, and a tail sprocket drive mechanism, where the nose sprocket drive mechanism is a hydraulic motor I, and the tail sprocket drive mechanism is a hydraulic motor II; and a hydraulic system that drives the hydraulic motor I and a hydraulic system that drives the hydraulic motor II include same hydraulic elements, and both include a three-position four-way solenoid directional valve, a two-position two-way solenoid directional valve, a two-position three-way solenoid directional valve, an accumulator, and an oil supplement valve group. The present invention is applicable to rapid starting and stopping of the scraper conveyor in a heavy load status while adjusting chain tension in real time, thereby resolving a power imbalance problem in a dual-drive system, and has a simple structure and a long service life.

In a work machine including a solenoid valve that generates a pilot pressure to drive a directional control valve with use of the delivery pressure of a pilot pump as a source pressure, a shut-off valve that shuts off a hydraulic operating fluid from the pilot pump to the solenoid valve, a first sensor that senses the amount of operation of an operation lever, and a second sensor that senses a state amount relating to operation of the solenoid valve, whether or not an abnormality of the second sensor exists is determined on the basis of a sensing signal of the second sensor. When it is determined that the second sensor is abnormal, on the basis of a sensing signal of the first sensor, an opening command is made to the shut-off valve if operation of the operation lever is sensed, and a closing command is made to the shut-off valve if the neutral state of the operation lever is sensed.

A bistable hydraulic solenoid valve has a valve spool that transitions between two positions, remaining in one of the two positions under an attractive magnetic force when the solenoids are not energized. The valve spool has a first permanent magnet attached to one end and a second permanent magnet attached to the other end, so that the first permanent magnet faces a first solenoid, and the second permanent magnet faces a second solenoid. The first solenoid is energized to have a first polarity, and the second solenoid is energized to have an opposite polarity to concurrently push and pull the valve spool within the valve body between a first position and a second position, the first position establishing a first flow path and the second position establishing a second flow path through the valve body and valve spool so as to enable flow of hydraulic fluid.

A servo valve has a movable element disposed inside a body, and a drive unit to slide the movable element in the axial direction. A first elastic portion on one end portion side of the body has a first elastic force to press the movable element toward the drive unit connected to another end portion of the body; a second elastic portion on another end portion side of the body has a second elastic force to press the movable element toward the one end portion side of the body. A connecting portion is connected to the second elastic portion, wherein at a neutral position of the movable element, the connecting portion abuts against an inner peripheral surface of the body and against the movable element. An end of one of the first and second elastic portions is fixed directly to the movable element, and an end of the other of the first and second elastic portions is connected to the connecting portion.