| 摘要 |
PROBLEM TO BE SOLVED: To prevent defective operation or lock of a spool by providing a motor rotatively driving the spool, a throttle section with variable opening by the rotation of the spool and bearings supporting the spool at two positions apart in the axial direction. SOLUTION: The angle θ between a first flat face 62e and a fourth flat face 62h and the angle θ between a second flat face 62f and a third flat face 62g are set equal to each other, and the relative rotation of a spool 62 to a projection is allowed by the prescribed angle. The relative rotation angle of the spool 62 to the projection is set so that the opening of a throttle section can be changed within the range at least from the required minimum opening to the maximum opening by the relative rotation. The contact position between one of both receiving faces 68c, 68d of a plug and one of the first through fourth flat faces 62e, 62f, 62g, 62h is used as a reference position, and the opening of the throttle section is controlled according to the rotation angle of the spool 62. |
