Exhaust Gas Purifier of Engine used in Locomotive

Abstract

A exhaust gas cleaning purifier used in an engine of a locomotive, which is arranged between an exhaust pipe of the engine and a silencer connecting to the exhaust pipe, includes a front supply pipe and a back supply pipe configured for supplying secondary air, at least one front catalyst converter for making an oxidation reaction and at least one middle catalyst converter for making an reduction reaction, and at least one back catalyst converter arranged after the silencer and the back supply pipe. The front supply pipe connects with the exhaust terminal of the engine, and the back supply pipe connects with the silencer. The at least one front catalyst converter and the at least one middle catalyst converter are arranged in the silencer and arranged between the front and back supply pipes. A dissipating-heat distance is defined between the front catalyst converter and the middle catalyst converter.

1 . An exhaust gas purifier of engine used in a locomotive, which is arranged between an exhaust pipe of the engine and a silencer connecting to the exhaust pipe, comprising:
 a front supply pipe and a back supply pipe configured for supplying secondary air, the front supply pipe connecting with an exhaust terminal of the engine, and the back supply pipe connecting with the silencer;   at least two catalyst converter in the silencer arranged between the front supply pipe and the back supply pipe, the at least two catalyst converter comprising at least one front catalyst converter for oxidation and at least one middle catalyst converter for reduction, a dissipating-heat distance defined between the front catalyst converter and the middle catalyst converter; and   at least one back catalyst converter arranged in the silencer and after the back supply pipe.   
   
   
       2 . The exhaust gas purifier as claimed in  claim 1 , further comprising a solenoid valve arranged on the back supply pipe and controlled by an actual rotating speed received by an engine control unit, when the actual rotating speed is lower than a predetermined speed of an engine control unit, the solenoid valve opens, and when the actual rotating speed is higher than the predetermined speed, the solenoid valve closes. 
   
   
       3 . The exhaust gas purifier as claimed in  claim 2 , wherein the predetermined speed is higher than an idle speed. 
   
   
       4 . The exhaust gas purifier as claimed in  claim 2 , wherein the back catalyst converter takes the oxidation with the exhaust gas when the solenoid valve opens, and the back catalyst converter takes the reduction with the exhaust gas when the solenoid valve closes. 
   
   
       5 . The exhaust gas purifier as claimed in  claim 1 , further comprising a flow control valve arranged on the back supply pipe and controlled by an actual exhaust temperature of the engine received by an engine control unit, when the actual exhaust temperature is lower than a predetermined temperature of the engine control unit, the flow control valve opens, and when the actual exhaust temperature is higher than the predetermined temperature, the flow control valve closes gradually or closes completely. 
   
   
       6 . The exhaust gas purifier as claimed in  claim 5 , wherein the predetermined temperature is higher than 200° C. 
   
   
       7 . The exhaust gas purifier as claimed in  claim 5 , wherein the back catalyst converter takes the oxidation with the exhaust gas when the flow control valve opens, the back catalyst converter takes the oxidation and the reduction synchronously when the flow control valve closes gradually, and the back catalyst converter takes the reduction reaction with the exhaust gas when the flow control valve closes completely.