Construction machine

#1. Field of the Invention

#The present invention relates to a construction machine with a piping structure of pilot pipe.

#2. Description of the Related Art

#FIG. 1 is a diagram showing a hydraulic circuit of a hydraulic excavator according to an embodiment of the present invention;

#FIGS. 2a through 2c show structures of a switching valve according to an embodiment of the present invention, where FIG. 2a is a plan view of the switching valve schematically showing a state that pilot pipes and pressure sensors are provided thereto, FIG. 2b is a front view of the switching valve when it is turned or a side view thereof and FIG. 2c is a cross-sectional view taken along an arrow of FIG. 2b;

#FIGS. 3a through 3c show structures of a switching valve according to another embodiment of the present invention, where FIG. 3a is a plan view of the switching valve schematically showing a state that pilot pipes and pressure sensors are provided thereto, FIG. 3b is a front view of the switching valve when it is turned, and FIG. 3c is a cross-sectional view taken along an arrow of FIG. 3b;

#Now, the present invention will be explained on the basis of embodiments shown in the drawings. These embodiments are only preferred embodiments of the present invention and the present invention is not limited to them.

#FIG. 1 is a diagram showing a hydraulic circuit of hydraulic excavator according to an embodiment of the present invention.

#In FIG. 1, a variable capacity type of hydraulic pump 2 and a pilot pump 3 are operated, respectively, by means of driving of an engine 1 mounted on an upper rotating body of the hydraulic excavator as a construction machine. Pressure oil discharged from the hydraulic pump 2 is supplied to a right traveling direction control valve 4, a bucket direction control valve 6 and a boom direction control valve 7, arranged in a center bypass line LC at left of FIG. 1. At the same time, the pressure oil is also supplied to a left traveling direction control valve 5, a rotating direction control valve 8 and an arm direction control valve 9, arranged in a center bypass line RC at right of FIG. 1.