Control valve and working machine including control valve

A control valve comprising:

• a valve body;
• a spool hole formed in the valve body;
• a spool slidably fitted in the spool hole;
• a pilot chamber into which a pilot fluid to actuate the spool is led;
• a discharge passage to discharge a hydraulic fluid to an outside of the valve body;
• a spiral groove formed in a spiral shape on an outer periphery of the spool;
• at least one axial groove to cause the pilot chamber and the spiral groove to communicate with each other, the axial groove being formed along an axial direction of the spool on an inner surface of the spool hole;
• and
• a circumferential groove formed in a circumferential direction on the inner surface of the spool hole, the circumferential groove communicating with an end portion of the axial groove opposite to an end portion of the axial groove that communicates with the pilot chamber, wherein
• the discharge passage is located opposite to the axial groove with respect to the circumferential groove to be spaced apart from the circumferential groove,
• the pilot chamber is adjacent to the spool hole in the axial direction of the spool, and the axial groove is located above the spool, in a state in which the valve body is installed such that the spool extends in a horizontal direction, and
• the spiral groove is configured such that:
• when the spool is in a neutral position, the spiral groove is located closer to the pilot chamber than the axial groove is to the pilot chamber;
• and
• when the spool is moved by a predetermined amount from the neutral position by the pilot fluid led into the pilot chamber, the spiral groove causes the pilot chamber and the discharge passage to communicate with each other bypassing the axial groove and the circumferential groove and the spiral groove directly communicates with the axial groove and the circumferential groove.