Low emission vehicle

Abstract

A low emission vehicle operates an internal combustion engine with lean air fuel ratios over at least a portion of its operating load range. The vehicle satisfies EURO IV emission requirements with just a three way catalyst and without any NOX storage capability in the exhaust after treatment system. An electronic control unit is programmed to operate the engine such that 80% or less of any tail pipe NOX mass emitted by the vehicle is generated during lean operation of the engine whereby the vehicle satisfies the EURO IV emission requirements.

1 . A vehicle having an internal combustion engine with a direct injection fuel system and an electronic control unit and an exhaust system with a three way catalyst wherein the electronic control unit is programmed to operate the engine with at least lean and stoichiometric air fuel ratios and wherein engine out NOx mass for lean air fuel ratios over the Euro IV drive cycle is 80% or less of the Euro IV standard whereby said vehicle has tail pipe emissions over the Euro IV drive cycle that satisfy the Euro IV requirement.  
     
     
         2 . A vehicle as claimed in  claim 1  wherein said catalyst has a volume of 85% or less engine swept volume (ESV).  
     
     
         3 . A vehicle as claimed in  claim 1  wherein said vehicle is operated with a stoichiometric air fuel ratio for engine loads equivalent to 50 km/h cruise on the vehicle's road load curve.  
     
     
         4 . A vehicle as claimed in  claim 1  wherein said engine is operated under lean steady state conditions with an air fuel ratio of 25:1 or less.  
     
     
         5 . A vehicle as claimed in  claim 1  wherein said engine is operated under lean transient conditions with an air fuel ratio of 20:1 or less.  
     
     
         6 . A vehicle having a lean burn internal combustion engine, an electronic control unit and an exhaust system with a three way catalyst wherein the electronic control unit is programmed to operate the engine over a Euro IV drive cycle such that 80% or less of any tail pipe NOx mass emitted by the vehicle is generated during lean operation of the engine whereby said engine satisfies the Euro IV emissions requirements.  
     
     
         7 . A vehicle as claimed in  claim 6  wherein 20% or less of any tail pipe NOx mass emitted by the vehicle is generated during stoichiometric operation of the vehicle.  
     
     
         8 . A vehicle having an internal combustion engine with a direct injection fuel system and an electronic control unit and an exhaust system with a three way catalyst wherein the electronic control unit is programmed to operate the engine with a lean air fuel ratio for loads having a NOx mass flow rate less than the Euro IV requirement.  
     
     
         9 . A vehicle as claimed in  claim 8  wherein said NOx mass flow rate is 80% or less than the Euro IV requirement.  
     
     
         10 . A vehicle as claimed in  claim 8  wherein said vehicle has tail pipe emissions equal to or less than the Euro IV requirement.  
     
     
         11 . A vehicle as claimed in  claim 1  wherein the lean steady state air fuel ratio is less than 25:1.  
     
     
         12 . A vehicle as claimed in  claim 1  wherein lean steady state air fuel ratios are in the range between 25:1 and 20:1.  
     
     
         13 . A vehicle as claimed in  claim 1  the engine having an exhaust manifold with low thermal inertia.  
     
     
         14 . A vehicle as claimed in  claim 1  wherein said engine utilises an air assisted direct injection fuel delivery system.  
     
     
         15 . A vehicle as claimed in  claim 1  wherein said engine further comprises a spray guided direct injection fuel delivery system.  
     
     
         16 . A vehicle as claimed in  claim 1  wherein said engine is adapted to operate with high sulphur fuel.  
     
     
         17 . A passenger vehicle having an engine equipped with a direct injection fuel system and an exhaust system comprising a catalyst with low NOx conversion efficiency under lean air fuel ratio operating conditions, the catalyst receiving engine out exhaust emissions and outputting treated exhaust emissions, the engine further comprising an electronic control unit for controlling operation of said engine and said electronic control unit adapted to operate said engine with lean air fuel ratios over more than 50% of the MVEG-B drive cycle and satisfying Euro IV emission requirements over said drive cycle.  
     
     
         18 . A passenger vehicle according to  claim 18  wherein the catalyst has near zero percent NOx conversion efficiency under lean air fuel ratio operating conditions.  
     
     
         19 . A passenger vehicle according to  claim 17  wherein the catalyst is a three way catalyst (TWC).  
     
     
         20 . A passenger vehicle according to  claim 17  wherein the vehicle has a fuel consumption in the order of 8 litres per 100 kilometres or less over the drive cycle.  
     
     
         21 . A passenger vehicle according to  claim 20  wherein the fuel consumption is in the order of 7.8 Litres per 100 kilometres or less.  
     
     
         22 . A passenger vehicle according to  claim 17  wherein the direct injection fuel system is a central injection fuel system.  
     
     
         23 . A passenger vehicle according to  claim 17  wherein the direct injection fuel system is a spray guided direct injection fuel system.  
     
     
         24 . A passenger vehicle according to  claim 17  wherein the direct injection fuel system is an air assisted fuel system.  
     
     
         25 . A passenger vehicle according to  claim 24  wherein the air assisted fuel system is a spray guided fuel system.  
     
     
         26 . A passenger vehicle according to  claim 24  wherein the air assisted fuel system is a central injection spray guided fuel system.  
     
     
         27 . A passenger vehicle according to  claim 17  wherein the catalyst has a volume of 110% of engine swept volume or less.  
     
     
         28 . A passenger vehicle according to  claim 27  wherein the catalyst has a volume in the order of 85% of engine swept volume.  
     
     
         29 . A passenger vehicle according to  claim 17  wherein the vehicle is adapted to operate with a lean air fuel ratio under steady state cruise conditions in the order of 50 km/h or less.  
     
     
         30 . A passenger vehicle as claimed in  claim 29  wherein except for overrun cut conditions, the vehicle operates with lean air fuel ratios of 25.0:1 or less.  
     
     
         31 . A passenger vehicle as claimed in  claim 30  wherein said vehicle operates with a lean air fuel ratio in the range of 18.0:1 to 20.0:1 for vehicle speeds in the order of 50 km/h.  
     
     
         32 . A passenger vehicle as claimed in  claim 1  wherein said electronic control unit is adapted to operate said engine with lean air fuel ratios over approximately 70% of the MVEG-B drive cycle.  
     
     
         33 . A passenger vehicle as claimed in  claim 1  wherein the engine is adapted to operate with stoichiometric or rich air fuel ratios when the vehicle speed is greater than 50 km/hr or during transient operating conditions.  
     
     
         34 . A passenger vehicle as claimed in  claim 1  wherein engine out NOx mass for lean air fuel ratios over the Euro IV drive cycle is 80% or less of the Euro IV standard.  
     
     
         35 . A passenger vehicle as claimed in  claim 1  wherein the electronic control unit is programmed to operate the engine with a lean air fuel ratio for loads having a NOx mass flow rate less than the Euro IV requirement.