Exhaust gas temperature reduction device for an engine of construction equipment

Abstract

Disclosed is a hydraulic circuit for controlling booms of construction equipment, wherein working oil which is relieved from a large chamber of a boom cylinder passes through an orifice so as to prevent the boom from lowering if an overload is applied when the boom is not being operated. The hydraulic circuit for controlling booms of construction equipment includes: a boom cylinder which is connected to a hydraulic pump via a first path and a second path; a boom control valve which is mounted on the path between the hydraulic pump and the boom cylinder; a holding valve which is mounted between the boom control valve and the first path of the boom cylinder and prevents the natural lowering of a boom when the boom control valve is in a neutral position; a port relief valve which is mounted to the first path at the lower side of a holding poppet and relieves working oil when an overload is generated at the first path; and an orifice valve which is mounted at the lower side of the port relief valve, relieves the working oil which passes through the port relief valve when the boom control valve is neutral so as to relieve the working oil through an orifice, and discharges the working oil which passes through the port relief valve to a hydraulic tank at the time of conversion due to boom-up pilot signal pressure which is applied to the boom control valve.

1 . An apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine including a diesel engine and a smoke reduction device connected onto an exhaust pipe of the diesel engine to prevent the discharge of particulate matters, the apparatus comprising:
 a cooling fan provided at one side of an engine room and configured to generate a cooling fan air flow through the inflow of an external air;   a tail pipe including a turbulent flow inlet port and a first guide configured to guide the cooling fan air flow to the inside of the tail pipe, the tail pipe having one end connected to the smoke reduction device and the other end extending to the outside of the engine room to discharge an overheated gas that is discharged during regeneration of the smoke reduction device to the outside; and   a diffuser including an external air inlet port exposed to the outside of the engine room and a second guide positioned adjacent to the external air inlet port to guide the external air introduced into the engine room to the inside of the apparatus, the diffuser being configured to surround an outer circumferential surface of the tail pipe to have a space defined between the tail pipe and the diffuser, whereby the diffuser is prevented from coming into direct contact with the tail pipe.   
     
     
         2 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 1 , wherein the turbulent flow inlet port is arranged in plural numbers at angular intervals of 45° along the circumference of the tail pipe, and the external air inlet port is arranged in plural numbers along the circumference of the diffuser to correspond to the plurality of turbulent flow inlet ports. 
     
     
         3 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 1 , wherein the second guide is formed in plural rows on the diffuser in such a manner as to be spaced apart from the smoke reduction device. 
     
     
         4 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 1 , wherein the first guide is formed in plural rows on the tail pipe in such a manner as to be the smoke reduction device. 
     
     
         5 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 1 , further comprising a connection bracket configured to securely fix a bottom end of the diffuser to the smoke reduction device so as to maintain the space defined between the diffuser and the tail pipe. 
     
     
         6 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 2 , wherein the second guide is formed in plural rows on the diffuser in such a manner as to be spaced apart from the smoke reduction device. 
     
     
         7 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 2 , wherein the first guide is formed in plural rows on the tail pipe in such a manner as to be the smoke reduction device. 
     
     
         8 . The apparatus for reducing a temperature of an exhaust gas for an engine of a construction machine according to  claim 2 , further comprising a connection bracket configured to securely fix a bottom end of the diffuser to the smoke reduction device so as to maintain the space defined between the diffuser and the tail pipe.