Spool valve

A spool valve provided in a valve mechanism included in a hydraulic control that includes a first oil supply source that draws in oil and discharges the oil having a first oil flow characteristic, a second oil supply source that draws in the oil and discharges the oil that has a second oil flow characteristic, a first output side oil passage into which the oil discharged from the first oil supply source flows, the first output side oil passage supplying hydraulic pressure to a controlled object, a second output side oil passage into which the oil discharged from the second oil supply source flows, a first connection oil passage that connects the first output side oil passage and the second output side oil passage to each other, and the valve mechanism provided with a spool hole, the valve mechanism being provided in the first connection oil passage, the spool hole including an input port connected to the second output side oil passage and an output port connected to the first output side oil passage, the spool valve provided in the valve mechanism about a central axis that extends in an axial direction being movable inside the spool hole in the axial direction, the spool valve comprising:

• a valve portion that opens and closes a portion between the input port and the output port;
• and
• a radial-direction-position changing portion provided in an outer lateral surface of the valve portion in a radial direction,
• wherein in a case in which a first value is equivalent to or larger than a threshold, the threshold being larger than 0, the first value being a value obtained by subtracting a value of a first output hydraulic pressure inside a portion of the first output side oil passage to which the first connection oil passage is connected from a value of a second output hydraulic pressure inside a portion of the second output side oil passage to which the first connection oil passage is connected, the portion between the input port and the output port are opened to permit a flow of the oil inside the first connection oil passage from the second output side oil passage to the first output side oil passage,
• wherein in a case in which the first value is smaller than the threshold, the portion between the input port and the output port is closed to block the flow of the oil inside the first connection oil passage from the second output side oil passage to the first output side oil passage, and
• wherein the radial-direction-position changing portion extends in the axial direction, and a position thereof in the radial direction changes inwardly from a first side in the axial direction towards a second side in the axial direction.