| 摘要 |
There are provided a pilot switching valve apparatus capable of preventing malfunction of a switching valve, due to unintentional feeding of a pilot pressure into a valve chest of the switching valve by error, at a low cost with the adoption of a simple configuration, and a method of switching the switching valve. In a valve chest of the pilot switching valve, a positive pressure chamber and a negative pressure chamber are formed on opposite sides of a valve spindle making a reciprocating motion in the valve chest due to repulsion by a return spring, and by connecting a positive pressure source for feeding a positive pilot pressure and a negative pressure source for feeding a negative pilot pressure to the positive pressure chamber, and the negative pressure chamber, respectively, the pilot switching valve has the configuration such that displacement of the valve spindle takes place against the urging of the return spring and connection among respective ports in the pilot switching valve can be switched only when pilot pressures from the positive pressure source and the negative pressure source are fed into the positive pressure chamber, and the negative pressure chamber, respectively.
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