TECHNICAL FIELD

The present invention relates to a control valve.

BACKGROUND ART

A control valve configured to be switched by an action of a pilot pressure and to lead the pilot pressure to another device is known (see WO2012/124386A1). This control valve includes a spool slidably incorporated in a valve housing and a first pilot chamber and a second pilot chamber disposed by facing both ends of the spool, and the spool is moved by an action of a pilot pressure led to either one of the first pilot chamber and the second pilot chamber.

A signal pressure passage configured to lead the pilot pressure of the first pilot chamber or the second pilot chamber as a signal pressure of the other device is formed in the valve housing. A communication groove configured to allow the first pilot chamber and the signal pressure passage to communicate with each other when the pilot pressure is led to the first pilot chamber and the spool is moved and a communication hole configured to allow the second pilot chamber and the signal pressure passage to communicate with each other when the pilot pressure is led to the second pilot chamber and the spool is moved, are formed in the spool. A check valve configured to allow only flow from the second pilot chamber to the signal pressure passage is interposed in the communication hole.

A centering spring configured to apply a spring force to one end portion of the spool is accommodated in the first pilot chamber. A base end portion of a rod extending in the first pilot chamber is screwed and fastened to an opening on the one end portion of the spool. A pair of spring receiving members slidable along an outer periphery of the rod is accommodated in the first pilot chamber, and the centering spring is interposed between the pair of spring receiving members.

SUMMARY OF INVENTION

The check valve described in WO2012/124386A1 can be constituted by a poppet portion configured to move in an axial direction and to open/close the communication hole and a spacer portion configured to regulate a moving amount of the poppet portion in the axial direction. In such configuration, when the pilot pressure is led to the second pilot chamber, the poppet portion is moved until it abuts to the spacer portion, and an open valve state is brought about. On the other hand, when the pilot pressure is led to the first pilot chamber, the poppet portion is seated on a seat portion of the communication hole, and a closed valve state is brought about.

However, in the check valve described in WO2012/124386A1, since the base end portion of the rod is screwed and fastened to the one end portion of the spool, when the pilot pressure is led to the first pilot chamber, there is a concern that a working oil enters into the check valve side from the first pilot chamber through a connection portion (screwed/fastened portion) between the one end portion of the spool and the rod. If the working oil enters into the check valve side, a pressure in a space between a rear surface (a surface on a side opposite to the surface in contact with the poppet portion) of the spacer portion and an end surface of the base end portion of the rod rises.

As a result, the spacer portion moves in the axial direction and presses the poppet portion so as to press the poppet portion onto the seat portion. After that, when the first pilot chamber is connected to a tank, the pressure in the space between the rear surface of the spacer portion and the end surface of the base end portion of the rod goes out to the tank through the connection portion (screwed/fastened portion) between the one end portion of the spool and the rod. However, since it takes time for the pressure in the space between the rear surface of the spacer portion and the end surface of the base end portion to lower to a tank pressure, the pressure remains in the space on the rear surface side of the spacer portion. If the pressure remains in the space on the rear surface side of the spacer portion when the pilot chamber is led to the second pilot chamber, a valve opening operation of the check valve according to the pressure in the second pilot chamber is inhibited, and responsiveness of the check valve is deteriorated, which is a problem.

The present invention has an object to improve responsiveness of a check valve.

According to an aspect of the present invention, a control valve, including: a spool slidably incorporated in a valve housing; a first pilot chamber and a second pilot chamber disposed by facing both ends of the spool; a signal pressure passage formed in the valve housing and configured to lead a pilot pressure of the first pilot chamber or the second pilot chamber to another device other than the control valve as a signal pressure; a communication groove formed in the spool and configured to allow the first pilot chamber and the signal pressure passage to communicate with each other when the spool is at a neutral position; a communication hole formed in the spool and configured to allow the second pilot chamber and the signal pressure passage to communicate with each other; and a check valve interposed in the communication hole and configured to allow only the flow from the second pilot chamber to the signal pressure passage, wherein the communication groove allows the first pilot chamber and the signal pressure passage to communicate with each other when the pilot pressure is led to the first pilot chamber and the spool is moved, while the communication between the first pilot chamber and the signal pressure passage is shut off when the pilot pressure is led to the second pilot chamber and the spool is moved; the check valve comprises: a poppet portion configured to open or close the communication hole; and a spacer portion configured to regulate a movement amount of the poppet portion to an open direction; and the control valve further comprises a movement regulating portion configured to regulate movement of the spacer portion toward the poppet portion.

