Patent ID: 7104283

Claim:
A normally open hydraulic control valve comprising: a linear solenoid unit; a spool driven by an output force of the linear solenoid unit to move forward; a valve body in which the spool is slidably fitted; and a return spring for biasing the spool in a retreating direction, the valve body including: a supply port leading to a hydraulic pressure source; an output port leading to a hydraulic pressure operating unit; a drain port opened into an oil tank; a reaction force oil chamber for introducing hydraulic pressure, which presses the spool in a direction against a biasing force of the return spring, from the output port; and a damper oil chamber to which one end surface of the spool is faced and which suppresses vibration of the spool, the spool being constructed to provide blockage between the output port and the drain port at a retreat limit of the spool to provide communication between the supply port and the output port, and to provide blockage between the supply port and the output port by advance of the spool to provide communication between the output port and the drain port, wherein a first land portion which slides in the valve body to provide blockage/communication between the supply port and the output port in accordance with advance/retreat of the spool, a second land portion which slides in the valve body to provide communication/blockage between the output port and the drain port in accordance with the advance/retreat of the spool, and a third land portion which has a diameter larger than that of the second land portion and slides in the valve body are formed on the spool in order from a side of the linear solenoid unit, wherein the valve body further includes a reaction force oil chamber to which a border portion of the second and third land portions is faced and which communicates with the output port, and a damper oil chamber adjacent to the reaction force oil chamber with the third land portion therebetween, and wherein a slide gap which leaks and supplies oil from the reaction force oil chamber to the damper oil chamber is provided between the third land portion and the valve body.