Sound proof box for an engine-driven work machine

A sound proof box for an engine-driven work machine comprising a base arranging an engine and a work machine main body driven by the engine and an upper portion of which is opened, and a sound proof case for covering the upper side of the base, and a space in the sound proof case being separated into two chambers by a vertically erected partition wall to make one chamber as an engine chamber storing the engine and the work machine main body and to make the other chamber as an air discharging chamber introducing the cooling air from the engine chamber through a communication port provided on the partition wall and discharging to outside of the machine through an air discharging port,

• an upper opening of the base being covered with a component arranging plate at a position at which to place the air discharging chamber, to form a bottom surface of the air discharging chamber by the component arranging plate,
• an inside of the base being separated into an upper stage and a lower stage by a floor plate at a predetermined position in the height direction to make a side of the upper stage of the base which includes the floor plate as an upper stage portion and make a part lower than the floor plate of the base as a lower stage portion,
• a separation wall to divide a space in the upper stage portion in the longitudinal direction being provided at a position below the engine chamber to make the space in the upper stage portion which is a space closer to the air discharging chamber than the separation wall as one space,
• a cooling air introduction port which communicates the engine chamber with the one space being provided between the partition wall and the separation wall,
• a through hole which communicates the one space with a space in the lower stage portion being provided at a bottom portion of the one space at a position below the air discharging chamber, and
• a cooling air intake port which communicates the space in the lower stage portion with the outside of the machine being provided on a lateral wall of the lower stage portion.