Patent ID: 7942381

Claim:
A solenoid valve comprising: a movable core; a valve element configured to move together with the movable core so as to control fluid communication; a magnetic opposed portion located farther away from the valve element than the movable core and opposed to the movable core, the magnetic opposed portion and the movable core being configured to therebetween define a gap; a nonmagnetic cylindrical portion surrounding radially outside of the gap; a first magnetic cylindrical portion located axially closer to the movable core than the nonmagnetic cylindrical portion; a second magnetic cylindrical portion located around an outer circumferential periphery of the magnetic opposed portion, the magnetic opposed portion being located axially farther away from the first magnetic cylindrical portion than the nonmagnetic cylindrical portion; and a coil located around an outer circumferential periphery of the nonmagnetic cylindrical portion, the coil being configured to generate magnetic attractive force between the magnetic opposed portion and the movable core when being energized, wherein the nonmagnetic cylindrical portion has a thickness t, the magnetic opposed portion has a cross-sectional area S 1 , the magnetic opposed portion and a cylindrical member, which retains the magnetic opposed portion and has the thickness t, have a total cross-sectional area S 2 , the thickness t, the cross-sectional area S 1 , and the total cross-sectional area S 2 satisfy t≦0.6 mm and 0.55≦(S 1 /S 2 ), the first magnetic cylindrical portion has a first outer diameter at a side of the nonmagnetic cylindrical portion, the second magnetic cylindrical portion has a second outer diameter at a side of the nonmagnetic cylindrical portion, the nonmagnetic cylindrical portion has a third outer diameter, and the first outer diameter and the second outer diameter are greater than the third outer diameter.