| CPC F16K 15/1826 (2021.08) | 1 Claim |

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1. A check valve device, comprising:
a main valve and a sub-valve provided in series along a flowpath formed in a block;
a primary-side chamber, an intermediate chamber, and a secondary-side chamber forming a section of the flowpath; and
a pilot valve for opening the main valve and the sub-valve, said main valve for connecting and blocking the secondary-side chamber and the intermediate chamber, said main valve comprising:
a cylindrical main valve member configured to be movable in an axial direction in an accommodation hole formed in the block;
a main valve surface formed on an outer circumferential wall of the cylindrical main valve member so as to be able to come into contact with a main valve seat formed circumferentially on an inner circumferential wall of the accommodation hole; and,
a valve closing spring for urging the cylindrical main valve member toward the main valve seat;
said sub-valve for connecting and blocking the primary-side chamber and the intermediate chamber, said sub-valve comprising:
a sub-valve member configured to be movable in the axial direction in a cylindrical hole of the cylindrical main valve member and to face the cylindrical main valve member with a predetermined gap in the axial direction so as to be able to come into contact with the cylindrical main valve member; and,
a sub-valve surface formed on an outer circumferential wall of the sub-valve member so as to be able to come into contact with a sub-valve seat formed circumferentially on the inner circumferential wall of the accommodation hole, and,
said pilot valve comprising a pilot valve member to be inserted into the block to be movable toward the sub-valve member and to face the sub-valve member with a predetermined gap so as to be able to come into contact with the sub-valve member, said pilot valve member being urged away from the sub-valve member by a retraction spring mounted in the accommodation hole and being moved toward the sub-valve member by pressurized fluid supplied to an actuation chamber provided in the block.
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