US Patent 10400902 Spool valve

The cross-sectional shape of a valve hole is an elongated shape having a long axis and a short axis, and has left and right hole side walls that are parallel to each other, a first hole end wall that connects one ends of the left and right hole side walls, and a second hole end wall that connects the other ends of the left and right hole side walls, and the cross-sectional shape of land portions of a spool is an elongated shape having a long axis and a short axis, and has left and right land side walls that are parallel to each other, a first land end wall that connects one ends of the left and right land side walls, and a second land end wall that connects the other ends of the left and right land side walls.