Electronic engine control device, vehicle equipped with electronic engine control device, and electronic engine control method

Abstract

On the premise that a target torque of an engine is equal to 0, that observed catalyst temperature is in a specified temperature range causing deterioration of the catalyst, and that the engine runs idle without a fuel cut regardless of fulfillment of preset fuel cut conditions, the control procedure of the invention determines whether a predetermined engine stop condition is fulfilled (step S 300 ). Upon fulfillment of the predetermined engine stop condition, the control procedure subsequently determines whether a high load is applied to an exhaust catalyst (step S 320 ). The engine runs idle (step S 310 ) when a high load is applied to the exhaust catalyst. The relatively low-temperature exhaust gas from the engine in the idling state forcibly cools down the exhaust catalyst. This prevents the exhaust catalyst from being kept at high temperature. When a low load is applied to the exhaust catalyst at step S 320 , on the other hand, the engine is stopped (step S 330 ). The stop of the engine cuts off the air flow through the exhaust catalyst. The exhaust catalyst is thus not exposed to the lean exhaust atmosphere and does not significantly deteriorate even at high temperature.

1 . An electronic engine control device that controls an engine, said electronic engine control device comprising: 
 the engine that converts combustion energy produced by combustion of an air fuel mixture or a mixture of the air and a fuel into kinetic energy;    an exhaust catalyst that purifies an exhaust gas from the engine;    a fuel injection unit that injects the fuel into the engine;    a catalyst deterioration control module that controls the fuel injection unit to keep fuel injection and idles the engine regardless of fulfillment of a preset fuel cut condition, when temperature of the exhaust catalyst is in a specified temperature range causing deterioration of the catalyst; and    an engine stop restart control module that stops the engine upon fulfillment of a preset engine stop condition and restarts the engine upon subsequent fulfillment of a preset engine restart condition,    upon fulfillment of the preset engine stop condition during idling of the engine by said catalyst deterioration control module, said engine stop restart control module idling the engine under application of a high load to the exhaust catalyst, while stopping the engine under application of a low load to the exhaust catalyst.    
     
     
         2 . An electronic engine control device that controls an engine, said electronic engine control device comprising: 
 the engine that converts combustion energy produced by combustion of an air fuel mixture or a mixture of the air and a fuel into kinetic energy;    an exhaust catalyst that purifies an exhaust gas from the engine; and    an engine stop restart control module that stops the engine upon fulfillment of a preset engine stop condition and restarts the engine upon subsequent fulfillment of a preset engine restart condition,    upon fulfillment of the preset engine stop condition, said engine stop restart control module idling the engine under application of a high load to the exhaust catalyst, while stopping the engine under application of a low load to the exhaust catalyst.    
     
     
         3 . An electronic engine control device in accordance with  claim 1 , wherein said engine stop restart control module determines a level of load applied to the exhaust catalyst according to thermal energy of the exhaust gas.  
     
     
         4 . An electronic engine control device in accordance with  claim 2 , wherein said engine stop restart control module determines a level of load applied to the exhaust catalyst according to thermal energy of the exhaust gas.  
     
     
         5 . An electronic engine control device in accordance with  claim 3 , wherein said engine stop restart control module integrates the thermal energy of the exhaust gas over a time period to determine the level of load applied to the exhaust catalyst.  
     
     
         6 . An electronic engine control device in accordance with  claim 4 , wherein said engine stop restart control module integrates the thermal energy of the exhaust gas over a time period to determine the level of load applied to the exhaust catalyst.  
     
     
         7 . An electronic engine control device in accordance with  claim 3 , wherein said engine stop restart control module utilizes at least either of a temperature and a flow rate of the exhaust gas as the thermal energy of the exhaust gas.  
     
     
         8 . An electronic engine control device in accordance with  claim 4 , wherein said engine stop restart control module utilizes at least either of a temperature and a flow rate of the exhaust gas as the thermal energy of the exhaust gas.  
     
     
         9 . An electronic engine control device in accordance with  claim 7 , wherein an intake air flow introduced into the engine is set to the flow rate of the exhaust gas.  
     
     
         10 . An electronic engine control device in accordance with  claim 8 , wherein an intake air flow introduced into the engine is set to the flow rate of the exhaust gas.  
     
     
         11 . An electronic engine control device in accordance with  claim 1 , said electronic engine control device further comprising: 
 a three shaft-type power input-output unit that determines a power input from and output to residual one shaft based on powers input from and output to any two shafts among three shafts, that is, an output shaft of the engine, a connection shaft connected to a first motor generator, and a drive shaft of a vehicle connected to a second motor generator,    wherein the engine is idled by setting a rotational resistance of a rotor in the first motor generator to zero for an idle of the connection shaft.    
     
     
         12 . An electronic engine control device in accordance with  claim 2 , said electronic engine control device further comprising: 
 a three shaft-type power input-output unit that determines a power input from and output to residual one shaft based on powers input from and output to any two shafts among three shafts, that is, an output shaft of the engine, a connection shaft connected to a first motor generator, and a drive shaft of a vehicle connected to a second motor generator,    wherein the engine is idled by setting a rotational resistance of a rotor in the first motor generator to zero for an idle of the connection shaft.    
     
     
         13 . An electronic engine control device in accordance with  claim 1 , wherein the preset engine stop condition includes a condition that a current vehicle speed is in a preset engine stop permission vehicle speed range.  
     
     
         14 . A vehicle equipped with an electronic engine control device in accordance with  claim 1 .  
     
     
         15 . An electronic engine control method that controls an engine, said electronic engine control method comprising the steps of: 
 (a) keeping fuel injection and idling the engine regardless of fulfillment of a preset fuel cut condition, when temperature of an exhaust catalyst, which purifies an exhaust gas from the engine, is in a specified temperature range causing deterioration of the catalyst;    (b) upon fulfillment of a preset engine stop condition during idling of the engine in step (a), idling the engine under application of a high load to the exhaust catalyst, while stopping the engine under application of a low load to the exhaust catalyst; and    (c) restarting the engine upon fulfillment of a preset engine restart condition after stop of the engine in step (b).    
     
     
         16 . An electronic engine control method that controls an engine, said electronic engine control method comprising the steps of: 
 (a) upon fulfillment of a preset engine stop condition, idling the engine under application of a high load to an exhaust catalyst, while stopping the engine under application of a low load to the exhaust catalyst; and    (b) restarting the engine upon fulfillment of a preset engine restart condition after stop of the engine in step (a)