Pressure peak reduction valve for excavator and pressure peak reduction system for excavator comprising same

1. A pressure peak reduction valve for an excavator, the pressure peak reduction valve comprising:

a poppet seat which has an inlet port into which hydraulic oil discharged from a hydraulic pump flows and which is formed at an end portion of the poppet seat, and at least one communication hole which communicates with a hydraulic tank and is formed in an outer circumferential surface of the poppet seat;

a main poppet which slides in the poppet seat;

a poppet spring which is provided in the main poppet;

a valve seat which has one end portion inserted into the main poppet so as to be in contact with one end portion of the poppet spring;

a cone which is provided to be inserted into an openable hole formed at the one end portion of the valve seat;

an adjustment screw which is provided in the valve seat;

a cone spring which is provided between the cone and the piston; and

a piston which slides in a direction of pressing the cone spring inside the adjustment screw, when an increase of a pilot pressure is inputted to the adjustment screw.

2. The pressure peak reduction valve of claim 1 , further comprising:

a piston spring which is inserted into the piston; and

a spring seat which supports an end portion of the piston spring.

3. The pressure peak reduction valve of claim 1 , further comprising:

an adjustment nut which is provided on an outer circumferential surface of the adjustment screw.

4. A pressure peak reduction valve for an excavator, the pressure peak reduction valve comprising:

a poppet seat which has an inlet port into which hydraulic oil flows from a hydraulic pump and which is formed at an end portion of the poppet seat, and at least one communication hole which communicates with a hydraulic tank and is formed in an outer circumferential surface of the poppet seat;

a main poppet which opens and closes the inlet port and the communication hole;

a valve seat which allows pressure in a pressure chamber formed in the poppet seat to be maintained to a preset pressure;

a poppet spring which presses the main poppet so as to allow a flow path between the inlet port and the communication hole to be kept closed;

a cone which drains the hydraulic oil in the pressure chamber to the hydraulic tank when the pressure in the pressure chamber is equal to or higher than the preset pressure;

an adjustment screw which has an end portion to which pilot pressure is inputted from the outside;

a cone spring which returns the cone to an original position; and

a piston which slides in a direction of pressing the cone spring inside the adjustment screw by an increase of the pilot pressure is inputted to the adjustment screw.

5. The pressure peak reduction valve of claim 4 , further comprising:

a piston spring which returns the piston, which has slid to press the cone, to an original state.

6. The pressure peak reduction valve of claim 4 , further comprising:

an adjustment nut which prevents rotation of the adjustment screw.

7. The pressure peak reduction valve of claim 4 , wherein the pressure peak reduction valve is included in a pressure peak reduction system for an excavator, the pressure peak reduction system comprising:

the hydraulic pump for an excavator;

a pressure detection unit which detects a discharge pressure of the hydraulic pump;

an operation pressure detection unit which detects an operation of the excavator; and

a control unit which controls the discharge pressure of the hydraulic pump in accordance with the operation detected by the operation pressure detection unit and the discharge pressure detected by the pressure detection unit,

wherein a pump input signal inputted to the hydraulic pump from the control unit is the pilot pressure inputted to the pressure peak reduction valve for an excavator.