Catalyst deterioration detecting apparatus and method for use with vehicles

Abstract

A catalyst deterioration detecting apparatus and method detects a deteriorated functional state of an catalyst provided in an exhaust passage of an internal combustion engine of a vehicle. A controller of the vehicle calculates a required total output that is required for driving the vehicle, and an output adjusting device, such as, for example, an electric motor, cooperates with the engine to provide the required total output. The catalyst is diagnosed so as to determine whether the catalyst is in a deteriorated functional state. During the diagnosis of the catalyst, the controller restricts the output of the engine to be held within a predetermined range, and changes the output of the output adjusting device as needed so as to provide the required total output.

What is claimed is:  
     
         1 . A catalyst deterioration detecting apparatus for detecting a deteriorated functional state of a catalyst provided in an exhaust passage of an internal combustion engine of a vehicle, the vehicle further including an output adjusting device that cooperates with the internal combustion engine to provide a predetermined total output that is required for driving the vehicle, the apparatus comprising: 
 a controller that: 
 performs a diagnostic operation to diagnose the catalyst so as to determine whether the catalyst is in a deteriorated functional state; and  
 during the performance of the diagnostic operation, restricts the output of the internal combustion engine to be held within a predetermined range, and changes the output of the output adjusting device to provide the predetermined total output.  
   
     
     
         2 . The apparatus according to    claim 1   , wherein the controller: 
 detects a plurality of operating conditions of the vehicle; and    initiates the performance of the diagnostic operation when the detected operating conditions of the vehicle are suitable for diagnosing the catalyst.    
     
     
         3 . The apparatus according to    claim 1   , wherein the controller: 
 detects a plurality of operating conditions of the vehicle; and    initiates performance of a compulsory diagnostic operation when the detected operating conditions of the vehicle are not suitable for diagnosing the catalyst;    wherein the controller restricts the output of the internal combustion engine upon initiation of the compulsory diagnostic operation so that the output of the internal combustion engine is held within the predetermined range.    
     
     
         4 . The apparatus according to    claim 3   , wherein the controller initiates the compulsory diagnostic operation under a predetermined condition.  
     
     
         5 . The apparatus according to    claim 1   , wherein the controller controls the output of the internal combustion engine such that an amount of change of the output of the internal combustion engine is smaller than a predetermined maximum value.  
     
     
         6 . The apparatus according to    claim 1   , wherein the controller controls the output of the internal combustion engine such that the output of the internal combustion engine is kept larger than zero, throughout the performance of the diagnostic operation.  
     
     
         7 . The apparatus according to    claim 1   , wherein: 
 the vehicle has a hybrid drive including the internal combustion engine and an electric motor, and the output adjusting device comprises the electric motor;    the controller calculates an output of the internal combustion engine and an output of the electric motor depending upon an operating state of the vehicle; and    during the performance of the diagnostic operation, the controller controls the outputs of the internal combustion engine and of the electric motor, irrespective of the calculated outputs, so as to restrict the output of the internal combustion engine and change the output of the electric motor such that a sum of the restricted output of the internal combustion engine and the changed output of the electric motor is equal to the predetermined total output.    
     
     
         8 . The apparatus according to    claim 7   , wherein the controller: 
 detects a plurality of operating conditions of the vehicle; and    initiates the performance of the diagnostic operation when the detected operating conditions of the vehicle are suitable for diagnosing the catalyst.    
     
     
         9 . The apparatus according to    claim 7   , wherein the controller: 
 detects a plurality of operating conditions of the vehicle; and    initiates performance of a compulsory diagnostic operation when the detected operating conditions of the vehicle are not suitable for diagnosing the catalyst;    wherein the controller restricts the output of the internal combustion engine upon initiation of the compulsory diagnostic operation so that the output of the internal combustion engine is held within the predetermined range.    
     
     
         10 . The apparatus according to    claim 9   , wherein the controller initiates the compulsory diagnostic operation under a predetermined condition.  
     
     
         11 . The apparatus according to    claim 7   , wherein the controller controls the output of the internal combustion engine such that an amount of change of the output of the internal combustion engine is smaller than a predetermined maximum value.  
     
     
         12 . The apparatus according to    claim 7   , wherein the controller controls the output of the internal combustion engine such that the output of the internal combustion engine is kept larger than zero, throughout the performance of the diagnostic operation.  
     
     
         13 . A hybrid vehicle comprising: 
 an internal combustion engine including an exhaust passage having a catalyst therein;    an electric motor, the internal combustion engine and the electric motor coupled to drive wheels of the vehicle by a transmission, the electric motor cooperating with the internal combustion engine to provide a predetermined total output to the drive wheels; and    a controller that: 
 performs a diagnostic operation to diagnose the catalyst so as to determine whether the catalyst is in a deteriorated functional state; and  
 during the performance of the diagnostic operation, restricts the output of the internal combustion engine to be held within a predetermined range, and changes the output of the electric motor to provide the predetermined total output.  
   
     
     
         14 . The hybrid vehicle according to    claim 13   , wherein the controller: 
 detects a plurality of operating conditions of the vehicle; and    initiates the performance of the diagnostic operation when the detected operating conditions of the vehicle are suitable for diagnosing the catalyst.    
     
     
         15 . The hybrid vehicle according to    claim 13   , wherein the controller controls the output of the internal combustion engine such that an amount of change of the output of the internal combustion engine is smaller than a predetermined maximum value.  
     
     
         16 . The hybrid vehicle according to    claim 13   , wherein the controller controls the output of the internal combustion engine such that the output of the internal combustion engine is kept larger than zero, throughout the performance of the diagnostic operation.  
     
     
         17 . A catalyst deterioration detecting method for detecting a deteriorated functional state of a catalyst provided in an exhaust passage of an internal combustion engine of a vehicle, the vehicle including an output adjusting device that cooperates with the internal combustion engine to provide a predetermined total output that is required for driving the vehicle, the method comprising: 
 performing a diagnostic operation to diagnose the catalyst so as to determine whether the catalyst is in a deteriorated functional state; and    during the performance of the diagnostic operation, restricting the output of the internal combustion engine to be held within a predetermined range, and changing the output of the output adjusting device to provide the predetermined total output.    
     
     
         18 . The method according to    claim 17   , further comprising: 
 detecting a plurality of operating conditions of the vehicle; and    initiating the performance of the diagnostic operation when the detected operating conditions of the vehicle are suitable for diagnosing the catalyst.    
     
     
         19 . The method according to    claim 17   , further comprising: 
 detecting a plurality of operating conditions of the vehicle; and    initiating performance of a compulsory diagnostic operation when the detected operating conditions of the vehicle are not suitable for diagnosing the catalyst;    wherein, upon initiation of the compulsory diagnostic operation, the output of the internal combustion engine is restricted so that the output of the internal combustion engine is held within the predetermined range.    
     
     
         20 . The method according to    claim 19   , wherein the compulsory diagnostic operation is initiated under a predetermined condition.  
     
     
         21 . The method according to    claim 17   , wherein the output of the internal combustion engine is controlled such that an amount of change of the output of the internal combustion engine is smaller than a predetermined maximum value.  
     
     
         22 . The method according to    claim 17   , wherein the output of the internal combustion engine is controlled such that the output of the internal combustion engine is kept larger than zero throughout the performance of the diagnostic operation.  
     
     
         23 . The method according to    claim 17   , wherein the vehicle has a hybrid drive including the internal combustion engine and an electric motor, and the output adjusting device comprises the electric motor; and the method further comprises: 
 calculating an output of the internal combustion engine and an output of the electric motor depending upon an operating state of the vehicle; and    during the performance of the diagnostic operation, controlling the outputs of the internal combustion engine and of the electric motor, irrespective of the calculated outputs, so as to restrict the output of the internal combustion engine and changes the output of the electric motor such that a sum of the restricted output of the internal combustion engine and the changed output of the electric motor is equal to the predetermined total output.    
     
     
         24 . The method according to    claim 23   , further comprising: 
 detecting a plurality of operating conditions of the vehicle; and    initiating the performance of the diagnostic operation when the detected operating conditions of the vehicle are suitable for diagnosing the catalyst.    
     
     
         25 . The method according to    claim 23   , further comprising: 
 detecting a plurality of operating conditions of the vehicle; and    initiating performance of a compulsory diagnostic operation when the detected operating conditions of the vehicle are not suitable for diagnosing the catalyst;    wherein, upon initiation of the compulsory diagnostic operation, the output of the internal combustion engine is restricted so that the output of the internal combustion engine is held within the predetermined range.    
     
     
         26 . The method according to    claim 25   , wherein the compulsory diagnostic operation is initiated under a predetermined condition.  
     
     
         27 . The method according to    claim 23   , wherein the output of the internal combustion engine is controlled such that an amount of change of the output of the internal combustion engine is smaller than a predetermined maximum value.  
     
     
         28 . The method according to    claim 23   , wherein the output of the internal combustion engine is controlled such that the output of the internal combustion engine is kept larger than zero, throughout the performance of the diagnostic operation.