US-12624530-B2 - Control valve and working machine including control valve

US12624530B2US 12624530 B2US12624530 B2US 12624530B2US-12624530-B2

Abstract

The control valve includes 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 to communicate with the discharge passage, the spiral groove being formed in a spiral shape on an outer periphery of the spool; and 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.

Inventors

Hiroshi Horii
Syunsuke Fukuda

Assignees

KUBOTA CORPORATION
KYB CORPORATION

Dates

Publication Date: 20260512
Application Date: 20240612
Priority Date: 20211220

Claims (4)

1 . 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.
2 . The control valve according to claim 1 , wherein the at least one axial groove includes a plurality of axial grooves formed around the spool.
3 . The control valve according to claim 1 , wherein a passage resistance of the spiral groove is larger than a passage resistance of the axial groove.
4 . A working machine comprising the control valve according to claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation application of International Application No. PCT/JP2022/042939, filed on Nov. 21, 2022, which claims the benefit of priority to Japanese Patent Application No. 2021-206180, filed on Dec. 20, 2021. The entire contents of each of these applications are hereby incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control valve and a working machine including the control valve. 2. Description of the Related Art Conventionally, a control valve disclosed in Japanese Unexamined Patent Application Publication No. 2007-255468 is known. The control valve disclosed in Japanese Unexamined Patent Application Publication No. 2007-255468 includes a valve body having formed therein an actuator port to which a hydraulic actuator can be connected and a discharge passage that discharges a hydraulic fluid returning via the actuator port to the outside. A spool hole is formed in the valve body, a spiral groove with a spiral shape is formed on an outer periphery of a spool slidably fitted in the spool hole, a pilot chamber into which a pilot fluid to actuate the spool is led is provided, and the pilot chamber and the discharge passage are configured to communicate with each other via the spiral groove when the spool moves by a predetermined amount from a neutral position with the pilot fluid led into the pilot chamber. Accordingly, the pilot fluid led into the pilot chamber partially leaks to the discharge passage via the spiral groove, and hence air accumulated in the pilot chamber is removed, and switching responsiveness of the spool is improved. SUMMARY OF THE INVENTION In the control valve disclosed in Japanese Unexamined Patent Application Publication No. 2007-255468, it is considered that the air removal amount (the amount of air remaining in the pilot chamber) varies. Specifically, since the spool is rotatable on the axis, for example, when the spool is assembled in, the position of an end portion of the spiral groove near the pilot chamber in the length direction (an inlet-side end portion of the pilot fluid) varies depending on the rotational position of the spool on the axis. Since air is accumulated in an upper portion of the pilot chamber, for example, when the inlet-side end portion of the spiral groove is located at a low position, air is hardly removed. In view of the above problem, an object of the present invention is to provide a control valve capable of stably removing air and a working machine including the control valve. Solution to Problem A control valve according to one aspect of the present invention includes 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 to communicate with the discharge passage, the spiral groove being formed in a spiral shape on an outer periphery of the spool; and 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. The pilot chamber may be adjacent to the spool hole in the axial direction of the spool, and the axial groove may be located above the spool, in a state in which the valve body is installed such that the spool extends in a horizontal direction. The at least one axial groove may include a plurality of axial grooves formed around the spool. A passage resistance of the spiral groove may be larger than a passage resistance of the axial groove. The control valve may include 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. The discharge passage may be located opposite to the axial groove with respect to the circumferential groove to be spaced apart from the circumferential groove, and the spiral groove may cause the circumferential groove and the discharge passage to communicate with each other. The pilot chamber and the discharge passage may be blocked from each other when the spool is in a neutral position, and the pilot chamber and the discharge passage may communicate with each other via the axial groove and the spiral groove when the spool is moved by a predetermined amount from the neutral position with the pilot fluid led into the pilot chamber. A working machine may include the above-described control valve. The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawi