Catalyst heating control method of parallel type hybrid vehicle

Abstract

Disclosed herein is a catalyst heating control method for a parallel hybrid vehicle that can generate a predetermined torque required to maintain a stable no-load operation state of an engine when a catalyst is warmed in a cold-start state of the engine while sufficiently reducing the ignition efficiency.

1 . A catalyst heating control method for a parallel hybrid vehicle, comprising the step of compensating a reduced ignition efficiency of the engine with a motor torque. 
   
   
       2 . A catalyst heating control method for a parallel hybrid vehicle, comprising the steps of:
 determining a target catalyst heating ignition efficiency;   calculating a catalyst heating engine torque;   calculating a no-load operation requirement torque of the engine to maintain a stable no-load operation state of the engine;   determining a motor compensation requirement torque; and   controlling a motor using the motor compensation requirement torque to maintain the stable no-load operation state of the engine by supplementing the torque of the engine operated with the target catalyst heating ignition efficiency.   
   
   
       3 . The catalyst heating control method as defined in  claim 2 , wherein the target heating ignition efficiency is set to have a reduced value in proportion to the maximum ignition efficiency where the maximum torque is exhibited. 
   
   
       4 . The catalyst heating control method as defined in  claim 2 , wherein the target heating ignition efficiency is determined by both an rpm of the engine and a charging efficiency after the engine is started. 
   
   
       5 . The catalyst heating control method as defined in  claim 4 , wherein the target heating ignition efficiency is determined by using a control map having the engine rpm and the charging efficiency as independent variables and the target catalyst heating ignition efficiency as a dependent variable. 
   
   
       6 . The catalyst heating control method as defined in  claim 3 , wherein the target catalyst heating ignition efficiency is determined to be within a range from 50% to 70% of the maximum ignition efficiency. 
   
   
       7 . The catalyst heating control method as defined in  claim 2 , wherein the catalyst heating engine torque is determined by both the target catalyst heating ignition efficiency and a charging efficiency of the engine at a given time. 
   
   
       8 . The catalyst heating control method as defined in  claim 7 , wherein the catalyst heating engine torque is determined by using a control map having the target catalyst heating ignition efficiency and the charging efficiency as independent variables and a catalyst heating engine torque as dependent variable. 
   
   
       9 . The catalyst heating control method as defined in  claim 2 , wherein the engine no-load operation requirement torque is determined by both a basic ignition efficiency, which is required to maintain the normal no-load operation state of the engine and a torque of the engine, which is output when operated with the charging efficiency at a given time. 
   
   
       10 . The catalyst heating control method as defined in  claim 9 , wherein the engine no-load operation requirement torque is determined by using a control map having basic ignition efficiency values and charging efficiency values as independent values and engine no-load operation requirement torque values as dependent values. 
   
   
       11 . The catalyst heating control method as defined in  claim 2 , further comprising the step of:
 determining whether the catalyst heating control is necessary using the temperature of cooling water of the engine before the target catalyst heating ignition efficiency is determined and just after the engine is started.   
   
   
       12 . The catalyst heating control method as defined in  claim 11 , wherein an engine no-load operation control is started after the step of  claim 11 . 
   
   
       13 . The catalyst heating control method as defined in  claim 12 , further comprising the steps of:
 calculating an engine rpm difference, which is a difference between a current rpm of the engine and a normal rpm of the engine under no load; and   accumulating an elapsed time after the engine has been started.   
   
   
       14 . The catalyst heating control method as defined in  claim 13 , wherein when the engine rpm difference is a predetermined value or less or when the accumulated elapsed time is a predetermined time or longer, the engine no-load operation control is stopped and the step of determining the target catalyst heating ignition efficiency is conducted. 
   
   
       15 . The catalyst heating control method as defined in  claim 14 , wherein the predetermined rpm difference is 50 rpm and the predetermined elapsed time is 7 seconds. 
   
   
       16 . A vehicle using the catalyst heating control method of  claim 1 . 
   
   
       17 . A vehicle using the catalyst heating control method of  claim 2 .