Hybrid vehicle thermal management using a bypass path in a catalytic converter unit

Abstract

A hybrid vehicle includes an exhaust gas treatment system having a bypass valve for directing a flow of air or exhaust gas through a bypass path or through a primary catalyst. The hybrid vehicle includes an internal combustion engine and an electric motor, each selectively engageable with a transmission to provide a drive torque. The electric motor spins the internal combustion engine when engaged to provide the drive torque, thereby creating a flow of unheated air from the internal combustion engine that flows through the exhaust gas treatment system. The bypass valve directs the flow of air through the bypass path when the engine is spinning and not fueled to prevent cooling of the primary catalyst. The bypass valve directs the flow of exhaust gas through the primary catalyst when the internal combustion engine is spinning and is being fueled, i.e., running, to treat the flow of exhaust gas.

1 . A method of operating a hybrid vehicle, the method comprising:
 determining if an internal combustion engine is spinning or is not spinning;   determining if the internal combustion engine is being fueled to generate a drive torque when the internal combustion engine is spinning, or is not being fueled when the internal combustion engine is spinning; and   directing a flow of air created by the internal combustion engine through a bypass path that bypasses a primary catalyst to prevent the flow of air from cooling the primary catalyst when the internal combustion engine is spinning and is not being fueled.   
     
     
         2 . A method as set forth in  claim 1  further comprising directing a flow of exhaust gas created by the internal combustion engine through the primary catalyst to treat the flow of exhaust gas when the internal combustion engine is spinning and is being fueled. 
     
     
         3 . A method as set forth in  claim 2  wherein directing the flow of air created by the internal combustion engine through the bypass path is further defined as opening a bypass valve to direct the flow of air created by the internal combustion engine through the bypass path. 
     
     
         4 . A method as set forth in  claim 3  wherein directing the flow of exhaust gas created by the internal combustion engine through the primary catalyst is further defined as closing the bypass valve to direct the flow of exhaust gas created by the internal combustion engine through the primary catalyst. 
     
     
         5 . A method as set forth in  claim 1  further comprising sensing a temperature of the primary catalyst. 
     
     
         6 . A method as set forth in  claim 5  wherein sensing the temperature of the primary catalyst is further defined as sensing the temperature of the primary catalyst when the engine is spinning and is being fueled. 
     
     
         7 . A method as set forth in  claim 6  further comprising determining if the sensed temperature of the primary catalyst is greater than a pre-defined temperature. 
     
     
         8 . A method as set forth in  claim 7  further comprising at least partially opening the bypass valve when the temperature of the primary catalyst is greater than a pre-defined limit to divert at least a portion of the flow of exhaust gas created by the internal combustion engine through the bypass path to prevent the primary catalyst from overheating. 
     
     
         9 . A method as set forth in  claim 8  further comprising treating the flow of exhaust gas diverted through the bypass path when the temperature of the primary catalyst is greater than the pre-defined limit with a second downstream catalyst. 
     
     
         10 . A method as set forth in  claim 1  further comprising closing the bypass valve when the internal combustion engine is not spinning and is not being fueled. 
     
     
         11 . A method as set forth in  claim 1  further comprising selectively generating a drive torque with an electric motor, whereby the electric motor spins the internal combustion engine thereby creating a flow of air from the internal combustion engine that flows through the exhaust gas treatment system. 
     
     
         12 . A method as set forth in  claim 1  further comprising fueling the internal combustion engine to generate a drive torque. 
     
     
         13 . A method of operating a hybrid vehicle, the method comprising:
 determining if an internal combustion engine is spinning or is not spinning;   determining if the internal combustion engine is being fueled to generate a drive torque when the internal combustion engine is spinning, or is not being fueled when the internal combustion engine is spinning;   opening a bypass valve of an exhaust gas treatment system to direct a flow of air created by the internal combustion engine through a bypass path that bypasses a primary catalyst to prevent the flow of air from cooling the primary catalyst when the internal combustion engine is spinning and is not being fueled;   closing the bypass valve to direct a flow of exhaust gas created by the internal combustion engine through the primary catalyst to treat the flow of exhaust gas when the internal combustion engine is spinning and is being fueled;   sensing a temperature of the primary catalyst when the engine is spinning and is being fueled;   determining if the sensed temperature of the primary catalyst is greater than a pre-defined temperature;   at least partially opening the bypass valve when the temperature of the primary catalyst is greater than a pre-defined limit to divert at least a portion of the flow of exhaust gas created by the internal combustion engine through the bypass path to prevent the primary catalyst from overheating when the engine is spinning and is being fueled; and   treating the flow of exhaust gas diverted through the bypass path when the temperature of the primary catalyst is greater than the pre-defined limit with a second downstream catalyst.   
     
     
         14 . A method as set forth in  claim 13  further comprising selectively generating a drive torque with an electric motor, whereby the electric motor spins the internal combustion engine thereby creating a flow of air from the internal combustion engine that flows through the exhaust gas treatment system. 
     
     
         15 . A vehicle comprising:
 a transmission configured for receiving a drive torque and transmitting the drive torque to a drive wheel;   an internal combustion engine coupled to the transmission and configured for selectively supplying the drive torque to the transmission;   an exhaust gas treatment system coupled to the internal combustion engine and configured for treating a flow of exhaust gas created by the internal combustion engine when the internal combustion engine is being fueled;   an electric motor coupled to the transmission and configured for selectively supplying the drive torque to the transmission;   wherein the electric motor spins the internal combustion engine in an un-fueled state thereby creating a flow of unheated air through the exhaust gas treatment system when the electric motor is supplying the drive torque to the transmission;   the exhaust gas treatment system including:
 a primary catalyst; 
 a bypass path defining a fluid flow path that bypasses the primary catalyst; and 
 a bypass valve configured for controlling fluid flow between the primary catalyst and the bypass path; 
 wherein the bypass valve is disposed in an open position to direct air flow through the bypass path when the electric motor is supplying the drive torque to the transmission and spinning the internal combustion engine, and wherein the bypass valve is disposed in a closed position to direct the flow of exhaust gas from the internal combustion engine through the primary catalyst when the internal combustion engine is fueled and supplying the drive torque to the transmission. 
   
     
     
         16 . A vehicle as set forth in  claim 15  wherein the primary catalyst, the bypass path and the bypass valve are all disposed within a catalytic converter unit. 
     
     
         17 . A vehicle as set forth in  claim 16  wherein the catalytic converter unit includes a second downstream catalyst disposed downstream of the primary catalyst. 
     
     
         18 . A vehicle as set forth in  claim 17  wherein the primary catalyst includes a tubular shape disposed annularly about and defining the bypass path, with the bypass path extending along a central opening of the tubular shaped primary catalyst. 
     
     
         19 . A vehicle as set forth in  claim 18  wherein the bypass valve is disposed upstream of the primary catalyst and is configured for opening and closing fluid flow through the central region of the tubular shaped primary catalyst defining the bypass path.