| 摘要 |
PURPOSE:To improve accuracy of function of a negative pressure actuator by supporting the valve shaft of a throttle valve of suction pipe by means of a bearing comprised of a permanent magnet and magnetic fluid thereby maintaining relative positional relation between the throttle valve and negative pressure port constant and stabilizing low speed rotation. CONSTITUTION:Valve shaft 14 of throttle valve 3 provided in a suction valve 2 is supported by bearings 16a, 16b. The bearing is comprised of permanent ring magnets 19a, 19b, non-magnetic guides 20a, 20b having abrasion resistance and magnetic ring yokes 17a, 17b, 18a, 18b formed with a plurality of labyrinth grooves. Gaps 21a, 21b are provided between the valve shaft 14 and yokes while magnetic fluid 22a, 22b is filled in yoke mount in the gap. By means of a magnetic circuit formed by permanent magnet, magnetic fluid will increase density uniformly between ridge of labyrinth and the outercircumference of valve shaft 14 to form rigid sealing film thus to hold the valve shaft 14 on the center line of yoke and to maintain constant positional relation with negative pressure port. |
