Abstract: An operation lever includes: a pair of rods disposed at point-symmetrical positions with respect to an operation axis; magnets disposed on the respective rods; and a pair of magnetic sensors disposed at line-symmetrical positions with respect to a second straight line perpendicular to a first straight line connecting centers of one of the rods and the other rod, on a plane perpendicular to the operation axis.

Abstract: A hydraulic cylinder spool valve device, which extends and retracts a cylinder rod of a hydraulic cylinder, includes: a first spool valve having a first dead band and a first opening characteristic; a second spool valve having a second dead band and a second opening characteristic; and a controller performing communication with the hydraulic cylinder by using the first spool valve and positioning the second spool of the second spool valve within the second dead band and performing communication with the hydraulic cylinder by using the second spool valve and positioning the first spool of the first spool valve within the first dead band, and adjusting a characteristic of a switching dead band between the first opening characteristic and the second opening characteristic.

Abstract: A filter state estimation system is configured to estimate a state of a filter provided in a hydraulic circuit. The hydraulic circuit includes: the filter; a bypass channel circumventing the filter and through which an oil flows; and a valve provided in the bypass channel and configured to be opened and closed based on a differential pressure. The filter state estimation system includes: a sensor to detect that the valve is in an open state or in a closed state; a temperature sensor to detect a temperature of the oil; and a state estimating unit to estimate a state of the filter based on detection results detected by the sensor and the temperature sensor. The state estimating unit estimates the state of the filter based on the temperature of the oil which is detected by the temperature sensor when the sensor detects that the valve is in the open state.

Abstract: An operation lever includes: a pair of rods disposed at point-symmetrical positions with respect to an operation axis; magnets disposed on the respective rods; and a pair of magnetic sensors disposed at line-symmetrical positions with respect to a second straight line perpendicular to a first straight line connecting centers of one of the rods and the other rod, on a plane perpendicular to the operation axis.

Abstract: A hydraulic cylinder spool valve device, which extends and retracts a cylinder rod of a hydraulic cylinder, includes: a first spool valve having a first dead band and a first opening characteristic; a second spool valve having a second dead band and a second opening characteristic; and a controller performing communication with the hydraulic cylinder by using the first spool valve and positioning the second spool of the second spool valve within the second dead band and performing communication with the hydraulic cylinder by using the second spool valve and positioning the first spool of the first spool valve within the first dead band, and adjusting a characteristic of a switching dead band between the first opening characteristic and the second opening characteristic.

Abstract: A filter state estimation system is configured to estimate a state of a filter provided in a hydraulic circuit. The hydraulic circuit includes: the filter; a bypass channel circumventing the filter and through which an oil flows; and a valve provided in the bypass channel and configured to be opened and closed based on a differential pressure. The filter state estimation system includes: a sensor to detect that the valve is in an open state or in a closed state; a temperature sensor to detect a temperature of the oil; and a state estimating unit to estimate a state of the filter based on detection results detected by the sensor and the temperature sensor. The state estimating unit estimates the state of the filter based on the temperature of the oil which is detected by the temperature sensor when the sensor detects that the valve is in the open state.

Abstract: A stroke detection device for detecting, along a longitudinal direction, a stroke amount of a spool arranged in a valve main body. The stroke detection device includes: a device main body attached to the valve main body; a detection rod extending along the longitudinal direction of the spool, and movably arranged along the longitudinal direction inside the device main body, in a position where a tip end portion faces an end surface of the spool; a stroke detection unit configured to output a detection signal according to the stroke amount of the detection rod with respect to the device main body; and an attracting unit arranged in the tip end portion of the detection rod, the attracting unit being attracted to the end surface of the spool by magnetic force.

Abstract: The hydraulic excavator comprises a revolving frame, a boom, a rotary encoder, and a link member. The revolving frame has a base plate and a first vertical plate and second vertical plate that are opposite each other and rise from the base plate. The boom is rotatably supported by the first vertical plate and the second vertical plate. The rotary encoder is provided at a position that is different from a position of the rotational axis of the boom, and senses the rotational angle of the boom according to the rotation of the boom. The link member transmits displacement of the boom to the rotary encoder.

Abstract: A stroke detection device for detecting, along a longitudinal direction, a stroke amount of a spool arranged in a valve main body. The stroke detection device includes: a device main body attached to the valve main body; a detection rod extending along the longitudinal direction of the spool, and movably arranged along the longitudinal direction inside the device main body, in a position where a tip end portion faces an end surface of the spool; a stroke detection unit configured to output a detection signal according to the stroke amount of the detection rod with respect to the device main body; and an attracting unit arranged in the tip end portion of the detection rod, the attracting unit being attracted to the end surface of the spool by magnetic force.

Abstract: A method for producing a hot dip plated steel sheet, the method controlling a coating weight by injecting a gas toward a surface of a steel sheet from a time when the steel sheet continuously immersed into a plating bath is pulled up from the plating bath to a time when plating metal adhered onto the surface of the steel sheet is solidified, the method includes: setting an oxygen concentration of a bath surface of the plating bath to be more than or equal to 0.05 vol % and less than or equal to 21 vol % when the gas is injected toward the surface of the steel sheet; and setting an oxygen concentration in a space of an end of the steel sheet at a position where the gas collides with the steel sheet pulled up from the plating bath to be more than or equal to 0.05 vol % and less than or equal to 3 vol % when the gas is injected toward the surface of the steel sheet.

Abstract: The hydraulic excavator comprises a revolving frame, a boom, a rotary encoder, and a link member. The revolving frame has a base plate and a first vertical plate and second vertical plate that are opposite each other and rise from the base plate. The boom is rotatably supported by the first vertical plate and the second vertical plate. The rotary encoder is provided at a position that is different from a position of the rotational axis of the boom, and senses the rotational angle of the boom according to the rotation of the boom. The link member transmits displacement of the boom to the rotary encoder.

Abstract: An arithmetic processing portion is configured to perform a correction process for resetting an original position of the stroke position by using at least detection results of a voltage value of a first magnetic force sensor as well as a second magnetic force sensor according to the piston movement, and further not to perform the correction process to reset the original position of the stroke position by using the detection result of the first magnetic force sensor and the second magnetic force sensor right after an abutment when the piston is abutted to the stroke end based on a detection result of a stroke end abutment detecting system.

Abstract: A stroke detection device includes: four rods provided, moveably along respective axial directions, side by side on a same circumference of a device body, the stroke detection device detecting a change in relative positions of the four rods at a time the rods perform a stroke with respect to the device body; a magnet disposed to each of the rods such that a magnetic field is generated between rods adjacent to each other on the circumference and that the magnetic field varies at a time the rods adjacent to each other on the circumference perform a stroke relatively; and magnetic field detection units disposed on at least three positions between the magnets adjacent to each other in the device body, each of the magnetic field detection unit detecting the magnetic field between the magnets and outputting an electric signal in accordance with the detected magnetic field.

Abstract: A hydraulic excavator includes a base body portion, a movable portion, a hydraulic cylinder, a position sensor, a rotary encoder, and a control unit. The rotary encoder includes a light emitting unit, a light receiving unit, and a disk unit having a plurality of transmission portions. The control unit measures the stroke length of the hydraulic cylinder by correcting deviation of the stroke length, which is measured by the position sensor, based on the pulse signal output from the rotary encoder. In this way, there can be obtained a hydraulic excavator capable of precisely measuring a stroke length of a hydraulic cylinder driving a work implement, as well as a method for measuring the stroke of the hydraulic cylinder of the hydraulic excavator.

Abstract: An arithmetic processing portion is configured to perform a correction process for resetting an original position of the stroke position by using at least detection results of a voltage value of a first magnetic force sensor as well as a second magnetic force sensor according to the piston movement, and further not to perform the correction process to reset the original position of the stroke position by using the detection result of the first magnetic force sensor and the second magnetic force sensor right after an abutment when the piston is abutted to the stroke end based on a detection result of a stroke end abutment detecting system.

Abstract: A hydraulic excavator includes a base body portion, a movable portion, a hydraulic cylinder, a position sensor, a rotary encoder, and a control unit. The rotary encoder includes a light emitting unit, a light receiving unit, and a disk unit having a plurality of transmission portions. The control unit measures the stroke length of the hydraulic cylinder by correcting deviation of the stroke length, which is measured by the position sensor, based on the pulse signal output from the rotary encoder. In this way, there can be obtained a hydraulic excavator capable of precisely measuring a stroke length of a hydraulic cylinder driving a work implement, as well as a method for measuring the stroke of the hydraulic cylinder of the hydraulic excavator.

Abstract: A method for producing a hot dip plated steel sheet, the method controlling a coating weight by injecting a gas toward a surface of a steel sheet from a time when the steel sheet continuously immersed into a plating bath is pulled up from the plating bath to a time when plating metal adhered onto the surface of the steel sheet is solidified, the method includes: setting an oxygen concentration of a bath surface of the plating bath to be more than or equal to 0.05 vol % and less than or equal to 21 vol % when the gas is injected toward the surface of the steel sheet; and setting an oxygen concentration in a space of an end of the steel sheet at a position where the gas collides with the steel sheet pulled up from the plating bath to be more than or equal to 0.05 vol % and less than or equal to 3 vol % when the gas is injected toward the surface of the steel sheet.

Abstract: In order to reduce hysteresis and other noise components included in the output signal characteristic of a differential pressure sensor, an elastic reaction member which operates together with a diaphragm provided in a chamber of the differential pressure sensor includes a contact portion which contacts the diaphragm, and a plurality of springs which are arranged symmetrically about the contact portion. Each of the springs is a plate shaped or linear shaped spring which is bent into the form of a letter C, U, J, or V, and has one of its ends fixed to a wall which defines the chamber, while its other end is connected to the contact portion. When the contact portion shifts together with the diaphragm, the deformations of the plurality of springs are mutually balanced, so that rotation and horizontal deviation of the contact portion with respect to the diaphragm is suppressed.

Abstract: A cylinder stroke position measurement device for enabling common use of a rotation sensor unit in measurement of a cylinder stroke position by detecting an amount of rotation of a rotary roller by means of a rotation sensor. A cylinder is provided at its head portion with a base member 300 having an opening accommodating at least a rotary roller and a rotation sensor section. A pressing member, the rotary roller, and the rotation sensor section are held on one side of a sensor holding member, while a coupling member for example is provided on the opposite side of the sensor holding member, thus constituting a rotation sensor unit. The sensor holding member is attached to the base member such that the rotary roller and the rotation sensor section are accommodated in the opening of the base member 300. The rotary roller is pressed by the pressing member against the surface of a rod. The rotation sensor section detects an amount of rotation of the rotary roller.

Abstract: In order to reduce hysteresis and other noise components included in the output signal characteristic of a differential pressure sensor, an elastic reaction member which operates together with a diaphragm provided in a chamber of the differential pressure sensor includes a contact portion which contacts the diaphragm, and a plurality of springs which are arranged symmetrically about the contact portion. Each of the springs is a plate shaped or linear shaped spring which is bent into the form of a letter C, U, J, or V, and has one of its ends fixed to a wall which defines the chamber, while its other end is connected to the contact portion. When the contact portion shifts together with the diaphragm, the deformations of the plurality of springs are mutually balanced, so that rotation and horizontal deviation of the contact portion with respect to the diaphragm is suppressed.