Construction machine

1. A construction machine comprising:

an engine generating power;

a pump generating hydraulic pressure by receiving power generated from the engine;

a main control valve receiving signal oil from the pump;

a key switch capable of turning on and off power of an electronic unit;

a battery storing electricity and discharging electricity to the key switch;

an engine control unit that maintains operation of the engine for a predetermined time and then stops operation of the engine when the key switch is switched from an on-state, during which power of the electronic unit capable of being turned on, to an off-state;

a pilot cut-off valve for opening and closing the signal oil according to the state of the key switch;

a pilot cut-off line, branched from a line between an output terminal of the key switch and the engine control unit,

wherein the pilot cut-off line electrically connects the pilot cut-off valve and the output terminal of the key switch; and

wherein the pilot cut-off valve is formed to open and close the signal oil by receiving electricity from the battery through the key switch.

2. The construction machine of claim 1 , further comprising:

an alternator receiving power from the engine to generate electricity; and

wherein the battery stores electricity produced by the alternator.

3. The construction machine of claim 2 , further comprising:

a charging line electrically connecting the battery and the alternator; and

a discharging line electrically connecting the charging line and an input terminal of the key switch to each other.

4. The construction machine of claim 1 ,

wherein the pilot cut-off valve is formed to close the signal oil when the key switch is in an off-state.

5. The construction machine of claim 1 ,

wherein the line between the output terminal of the key switch and the engine control unit is a battery relay connection terminal line extending from the output terminal to the engine control unit.

6. The construction machine of claim 1 ,

wherein the key switch comprises:

an input terminal;

an output terminal; and

a key switch bridge that electrically connects the input terminal and the output terminal in an on-state and breaks electrical connection between the input terminal and the output terminal in an off-state.

7. The construction machine of claim 1 , wherein the pilot cut-off valve reciprocates by a solenoid coil that forms a magnetic field when electricity is applied through the pilot cut-off line, and opens and closes the hydraulic device.

8. The construction machine of claim 7 , further comprising:

a pilot cut-off switch for opening and closing the pilot cut-off line.

9. The construction machine of claim 8 , wherein the pilot cut-off switch comprises:

a first port electrically connected to the output terminal of the key switch;

a second port electrically connected to the solenoid coil; and

a pilot cut-off switch bridge for connecting and disconnecting the first port and the second port.