Solenoid valve

1. A solenoid valve comprising:

a main valve portion containing a valve member for switching a flow path; and

a solenoid operation portion for operating the valve member, the solenoid operation portion containing, inside a magnetic frame, a hollow bobbin having an exciting coil wound therearound; a magnetic plate having an inner hole lying next to an inner hole of the bobbin, disposed on one end side in the axial direction of the bobbin, and magnetically coupled with the magnetic frame; a fixed iron core fixedly disposed inside the inner hole of the bobbin, and magnetically coupled to the magnetic frame; a movable iron core movably provided inside the inner holes of the bobbin and the magnetic plate, and attracted to the fixed iron core by magnetic attraction generated by the flow of electric current through the exciting coil; and an iron core return spring for making the movable iron core return to the initial position separated from the fixed iron core,

wherein the valve member is driven by the movable iron core,

wherein a synthetic resin cap is set with the tip portion of the movable iron core and a sliding portion extending to the position of the magnetic plate is formed at the base end portion of the cap, and

wherein a guiding concave step portion having a depth being equal to or less than one half of the thickness of the magnetic plate is formed on the surface facing the cap in the inner peripheral portion of the magnetic plate, and the movable iron core and the magnetic plate are held in a state to be not in contact with each other by the sliding portion of the cap slidably fitted into the concave step portion.

2. A solenoid valve as claimed in claim 1 , wherein the cap, having an additional function as a spring seat for the iron core return spring, contains a hollow cap main body surrounding the outer periphery of the tip portion of the movable iron core, a flange-shaped spring seat portion extending from the tip portion of the cap main body, and the hollow sliding portion formed at the base end of the cap main body and extending in the direction of the axial line, and wherein the sliding portion is divided into a plurality of constituent parts by cuts in the direction of the axial line and the constituent parts are elastically in contact with the inner peripheral surface of the ring-shaped concave step portion.

3. A solenoid valve as claimed in claim 2 , wherein an annular protruded wall portion is formed on the side face being in contact with the bobbin in the inner peripheral portion of the magnetic plate and the height of the protruded wall portion is equal to or more than the depth of the concave step portion.

4. A solenoid valve as claimed in claim 3 , wherein a flange-shaped large diameter portion is formed at the tip of the movable iron core, an expansion portion is formed at the tip of the inner hole of the cap, and the cap is controlled not to fall off from the movable iron core by the large diameter portion latched to the expanded portion.

5. A solenoid valve as claimed in claim 2 , wherein a flange-shaped large diameter portion is formed at the tip of the movable iron core, an expansion portion is formed at the tip of the inner hole of the cap, and the cap is controlled not to fall off from the movable iron core by the large diameter portion latched to the expanded portion.

6. A solenoid valve as claimed in claim 1 , wherein an annular protruded wall portion is formed on the side face being in contact with the bobbin in the inner peripheral portion of the magnetic plate and the height of the protruded wall portion is equal to or more than the depth of the concave step portion.

7. A solenoid valve as claimed in claim 6 , wherein a flange-shaped large diameter portion is formed at the tip of the movable iron core, an expansion portion is formed at the tip of the inner hole of the cap, and the cap is controlled not to fall off from the movable iron core by the large diameter portion latched to the expanded portion.

8. A solenoid valve as claimed in claim 1 , wherein a flange-shaped large diameter portion is formed at the tip of the movable iron core, an expansion portion is formed at the tip of the inner hole of the cap, and the cap is controlled not to fall off from the movable iron core by the large diameter portion latched to the expanded portion.