Abstract: A spool valve unit includes a sleeve member having a high-pressure port and a low-pressure port, a spool member movably accommodated in the sleeve member in an axial direction, and a spring member for biasing the spool member in a first axial direction. The spool valve unit produces an intermediate fluid pressure to be outputted to an outside of the spool valve unit, when electromagnetic force is applied to the spool member so that the spool member is moved at a high speed between the high-pressure port and the low-pressure port. The spring member is composed of a non-linear spring, a biasing force of which is non-linearly changed with respect to a displacement of the spool member.

Abstract: A current control device includes a target setting unit, a storage unit, an oil pressure ratio calculation unit, a specific current detection unit and a correction unit. The target setting unit adds a dither amplitude to a target current so that the current of the solenoid periodically changes at a dither cycle period longer than a PWM cycle period of the solenoid. The storage unit stores a stroke-current relationship between a stroke of the spool and the current of the solenoid. The oil pressure ratio calculation unit calculates an oil pressure ratio which is a value calculated by dividing an amplitude of the output oil pressure by an average value of the output oil pressure. The specific current detection unit detects a specific current based on the oil pressure ratio. The correction unit corrects the stroke-current relationship based on the specific stroke and the specific current.