Valve device

A valve device comprising:

• a spool operable to move in an axial direction of the spool to switch a liquid flow path or adjust a liquid flow rate;
• an operation pin connected to the spool and operable to rotate about a rotation axis of the operation pin as the spool moves in the axial direction;
• and
• an operation shaft operable to be moved along the rotation axis of the operation pin to be switched between a coupled state, in which the operation shaft is coupled by direct engagement to the operation pin and rotates together with the operation pin, and an uncoupled state, in which the operation shaft is not coupled to the operation pin and supports the operation pin such that the operation pin is rotatable, wherein
• the operation pin is operable to be rotated about the rotation axis such that the spool is moved when the operation shaft is rotated about the rotation axis in the coupled state,
• the operation pin includes a first engaging portion operable to engage with the operation shaft, and
• the operation shaft (i) includes a second engaging portion operable to engage with the first engaging portion of the operation pin, (ii) is operable to enter the coupled state when the second engaging portion engages with the first engaging portion, and (iii) is operable to enter the uncoupled state when the second engaging portion does not engage with the first engaging portion.