A solenoid valve comprises a movable core
In view of the foregoing problems, it is an object of the present invention to produce a solenoid valve configured to quickly actuate a valve element when being de-energized. It is another object of the present invention to produce a fuelinjection valve having the solenoid valve.
However, in the present structure, an eddy current may arise in the nonmagnetic portion when the coil is de-energized and magnetic flux quickly reduces in the gap. When an eddy current arises in the non-magnetic portion, which is locatedradially outside the gap, magnetic flux may be induced in the magnetic portion in the vicinity of the gap. Consequently, magnetic attractive force between the stationary core and the movable core may be retained for a long period. Consequently,response of the valve element of the solenoid valve may be impaired when the coil is de-energized.
Alternatively, it is conceivable to provide a nonmagnetic portion, instead of the magnetic throttle, which is formed from the magnetic material. In this case, the nonmagnetic portion is provided between the movable core side magnetic portionand the stationary core side magnetic portion to surround radially outside a gap, which is defined between the movable core and the stationary core. In the present structure, the nonmagnetic portion is capable of restricting the movable core sidemagnetic portion and the stationary core side magnetic portion from magnetically short-circuiting therebetween.
The solenoid valve further comprises a valve element configured to move together with the movable core so as to control fluid communication. The solenoid valve further comprises a second magnetic cylindrical portion located around an outer circumferential periphery of the magnetic opposed portion, the magnetic opposed portion being located axial farther awayfrom the first magnetic cylindrical portion than the nonmagnetic cylindrical portion.
The solenoid valve further comprises a nonmagnetic cylindrical portion surrounding radially outside of the gap. The solenoid valve further comprises a second magnetic cylindrical portion located around an outer circumferential periphery of the magnetic opposed portion, which is located axially farther away from the first magneticcylindrical portion than the nonmagnetic cylindrical portion. The solenoid valve further comprises a coil located around an outer circumferential periphery of the nonmagnetic cylindrical portion, the coil being configured to generate magnetic attractiveforce between the magnetic opposed portion and the movable core when being energized.
The solenoid valve further comprises a valve element configured to move together with the movable core so as to control fluid communication. The solenoid valve further comprises 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 agap.The nonmagnetic cylindrical portion has a thickness less than or equal to 0.6 mm. The nonmagnetic cylindrical portion has at least one recess.
The solenoid valve further comprises a coil located around an outer circumferential periphery of the nonmagnetic cylindrical portion, the coil being configured togenerate magnetic attractive force between the magnetic opposed portion and the movable core when being energized. The nonmagnetic cylindrical portion has a thickness t. The magnetic opposed portion has a cross-sectional area S1. The magnetic opposedportion and a cylindrical member which retains the magnetic opposed portion and has the thickness t, have a total cross-sectional area S2. The thickness t, the cross-sectional area S1, and the total cross-sectional area S2 satisfy t<0.6 mm and0.55<(S1/S2).
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