Abstract: A relief valve relieves hydraulic fluid from a first port to a second port, and includes a housing and an adjustment member capable of advancing and retracting; a seat member with a relief passage connecting to the two ports; a relief valve body that is unseated from or seated on the seat member to open or close the relief passage, and that receives pressure of the first port in a direction of opening the relief passage; a first biasing member that biases the relief valve body against the pressure of the first port, with a force adjusted by the adjustment member; a check valve body that opens or closes a check passage connecting to the two ports, and that receives pressure of the second port in a direction of opening the check passage; and a second biasing member that biases the check valve body.

Abstract: Provided is a configuration in which: a spool driven by an electromagnetic proportional solenoid is urged by a spool-returning spring configured to exert urging force in an opposite direction to a driving direction of the electromagnetic proportional solenoid; a mechanical stopper is disposed at the stroke end of the spool; current dither causes a control current to micro-vibrate, the control current driving the electromagnetic proportional solenoid; and the mechanical stopper includes a stopper-urging spring configured to allow the spool to vibrate owing to the current dither even when the spool is in contact with the mechanical stopper. A proportional solenoid control valve with this configuration is capable of reducing hysteresis at the stroke end of the spool by means of the current dither, and controlling the spool in a stable manner over the entire control range including the stroke end of the spool.

Abstract: A solenoid includes: a movable core configured to move in a first space of a main body case in an axial direction to apply a biasing force to a spool; a fixed magnetic pole portion configured to attract the movable core in the axial direction; an adjusting spring configured to apply the biasing force to the movable core; a biasing force adjusting member provided at an opening end portion of a rear case and configured to adjust an axial position thereof to adjust the biasing force; and a degassing plug provided at an opening end portion of the adjusting member and including a degassing passage that allows a second space to communicate with an outside by changing relative positions of the adjusting member and the degassing plug. A sealing portion configured to open or close communication between degassing passages is provided between the adjusting member and the degassing plug.

Abstract: Provided is a configuration in which: a spool driven by an electromagnetic proportional solenoid is urged by a spool-returning spring configured to exert urging force in an opposite direction to a driving direction of the electromagnetic proportional solenoid; a mechanical stopper is disposed at the stroke end of the spool; current dither causes a control current to micro-vibrate, the control current driving the electromagnetic proportional solenoid; and the mechanical stopper includes a stopper-urging spring configured to allow the spool to vibrate owing to the current dither even when the spool is in contact with the mechanical stopper. A proportional solenoid control valve with this configuration is capable of reducing hysteresis at the stroke end of the spool by means of the current dither, and controlling the spool in a stable manner over the entire control range including the stroke end of the spool.

Abstract: A seat block capable of maintaining a well-fitted state of a seat portion in a simple and reliable manner regardless of use conditions. A seat portion base body (43) is provided in a housing (67) provided with a valve passage (66) and allows a piston (28) for opening and closing a valve passage (66) to be pressed on the seat portion base body (43). A spring member (23) applies an elastic force to the seat portion base body (43) such that the elastic mechanism (23) cooperates with the housing (67) to retain the seat portion base body (43).

Abstract: A solenoid includes: a movable core configured to move in a first space of a main body case in an axial direction to apply a biasing force to a spool; a fixed magnetic pole portion configured to attract the movable core in the axial direction; an adjusting spring configured to apply the biasing force to the movable core; a biasing force adjusting member provided at an opening end portion of a rear case and configured to adjust an axial position thereof to adjust the biasing force; and a degassing plug provided at an opening end portion of the adjusting member and including a degassing passage that allows a second space to communicate with an outside by changing relative positions of the adjusting member and the degassing plug. A sealing portion configured to open or close communication between degassing passages is provided between the adjusting member and the degassing plug.

Abstract: A pressure compensated electromagnetic proportional directional flow control valve of the present invention integrally includes: an electromagnetic proportional directional flow control valve configured to be driven by a solenoid; and a pressure compensated valve configured to carry out pressure compensation of a flow rate controlled by the electromagnetic proportional directional flow control valve. A pressure compensation spool moves so as to balance forces of a spring, a first pressure chamber, and a second pressure chamber. With this, the pressure compensation for maintaining a constant pressure difference between an upstream side and a downstream side of a first variable aperture can be carried out, and a surplus liquid of a liquid flowing from a liquid-pressure supply port to a derivation port can flow out from a branch port to outside.

Abstract: A pressure compensated electromagnetic proportional directional flow control valve of the present invention integrally includes: an electromagnetic proportional directional flow control valve configured to be driven by a solenoid; and a pressure compensated valve configured to carry out pressure compensation of a flow rate controlled by the electromagnetic proportional directional flow control valve. A pressure compensation spool moves so as to balance forces of a spring, a first pressure chamber, and a second pressure chamber. With this, the pressure compensation for maintaining a constant pressure difference between an upstream side and a downstream side of a first variable aperture can be carried out, and a surplus liquid of a liquid flowing from a liquid-pressure supply port to a derivation port can flow out from a branch port to outside.

Abstract: A plunger (45) and a piston (46) are displaceably held in a housing (104) for opening and closing a valve path (107) defined in the housing (104), and a single common seat block (44) provided for the plunger (45) and the piston (46) is fixed to the housing (104) and has seat portions (47) each formed from a soft material for respective of the plunger (45) and the piston (46) to be pressed thereon. This arrangement provides a valve device which is simplified in structure and can be manufactured with reduced man-hour.

Abstract: A guide body for an electromagnetic valve device is provided. The device includes a coil assembly surrounding the guide body, a plunger driven by magnetic force and slidably disposed inside the guide body. The guide body slidably guides the plunger in an open/close direction of the valve body along a guide face thereof. The guide body includes a first nonmagnetic section that supports a pole body and a part of the plunger at which the pole body and the plunger oppose each other, a second nonmagnetic section that supports the valve body, and extends at least throughout a sliding range of the valve body, and a magnetic section intermediate the first and second sections so that a portion of the lines of magnetic force passes therethrough. The guide face is formed so as to coaxially support the plunger and the valve body displaceable in the open/close direction.

Abstract: A seat block capable of maintaining a well-fitted state of a seat portion in a simple and reliable manner regardless of use conditions. A seat portion base body (43) is provided in a housing (67) provided with a valve passage (66) and allows a piston (28) for opening and closing a valve passage (66) to be pressed on the seat portion base body (43). A spring member (23) applies an elastic force to the seat portion base body (43) such that the elastic mechanism (23) cooperates with the housing (67) to retain the seat portion base body (43).

Abstract: A guide body for an electromagnetic valve device is provided. The device includes a coil assembly surrounding the guide body, a plunger driven by magnetic force and slidably disposed inside the guide body. The guide body slidably guides the plunger in an open/close direction of the valve body along a guide face thereof. The guide body includes a first nonmagnetic section that supports a pole body and a part of the plunger at which the pole body and the plunger oppose each other, a second nonmagnetic section that supports the valve body, and extends at least throughout a sliding range of the valve body, and a magnetic section intermediate the first and second sections so that a portion of the lines of magnetic force passes therethrough. The guide face is formed so as to coaxially support the plunger and the valve body displaceable in the open/close direction.

Abstract: A plunger (45) and a piston (46) are displaceably held in a housing (104) for opening and closing a valve path (107) defined in the housing (104), and a single common seat block (44) provided for the plunger (45) and the piston (46) is fixed to the housing (104) and has seat portions (47) each formed from a soft material for respective of the plunger (45) and the piston (46) to be pressed thereon. This arrangement provides a valve device which is simplified in structure and can be manufactured with reduced man-hour.