Fuel management system for very high efficiency flex fuel engines

Abstract

Turbocharged or supercharged spark ignition engine. The engine includes a source of methanol for direct injection of methanol into the engine and for delivering a portion of the methanol to a reformer for generating a hydrogen-rich gas.

1 . A fuel management engine system for a turbo-charged or supercharged spark ignition engine comprising:
 a source of methanol for direct injection into the engine and for delivering a portion of the methanol to a reformer for generating a hydrogen-rich gas at lower engine torque values, wherein the hydrogen-rich gas is introduced into the engine to extend the limit of lean operation,   wherein the engine operates at a substantially stoichiometric fuel/air ratio during part of a drive cycle and at a lean fuel/air ratio during other parts of the drive cycle.   
   
   
       2 . The engine system of  claim 1  where at some time in the drive cycle, the equivalence ratio is less than or equal to 0.5. 
   
   
       3 . The engine system of  claim 1  where at some time in the drive cycle more than 30% of the methanol is reformed into hydrogen-rich gas. 
   
   
       4 . The engine system of  claim 1  where pyrolytic reforming using the heat from the exhaust is used. 
   
   
       5 . The engine system of  claim 1  where hot reformate is introduced into the engine. 
   
   
       6 . The engine system of  claim 5  where the temperature of the reformate that is introduced into the engine is between 300 and 700 degrees C. 
   
   
       7 . The engine system of  claim 5  where hot reformate is only used below a certain level of torque. 
   
   
       8 . The engine system of  claim 1  where a hybrid plasmatron/thermal reformer is used, the plasmatron reformer used during cold start. 
   
   
       9 . The engine system of  claim 1  where the reformer uses pyrolytic reforming. 
   
   
       10 . The engine system of  claim 8  where the plasma heating in the fuel reformer is reduced or eliminated during only part of the reformer operating time. 
   
   
       11 . The engine system of  claim 1  where the reformer is used to provide hydrogen-rich gas to assist in engine cold start. 
   
   
       12 . The engine system of  claim 1  where the compression ratio is at least 11 and preferably 12 or greater. 
   
   
       13 . The engine system of  claim 1  where a three-way catalytic converter is used. 
   
   
       14 . The engine system of  claim 1  where the engine is fueled with hydrogen-rich gas using port fuel injection. 
   
   
       15 . A turbocharged or supercharged, high compression ratio spark ignition engine that:
 uses directly injected methanol as a fuel; and   where the engine operates during part of a drive cycle with heavy EGR enabled by the use addition of hydrogen-rich gas; and   where the engine operates at a substantially stoichiometric fuel/air ratio over substantially all of its driving cycle.   
   
   
       16 . The engine of  claim 15  where the exhaust gas that is recirculated is hot. 
   
   
       17 . The engine of  claim 15  where the reformate is hot. 
   
   
       18 . The engine of  claim 15  where the engine is fueled with hydrogen-rich gas introduced into the inlet manifold. 
   
   
       19 . The engine system of  claim 1  where the engine operates with turbocharging or supercharging at inlet manifold pressures higher than 2 bar and preferably greater than 2.5 bar. 
   
   
       20 . The engine system of  claim 15  where the compression ratio is in the 12-14 range. 
   
   
       21 . The engine system of  claim 1  or  15  where the hot hydrogen-rich gas is preferentially introduced into the region of the spark to minimize the amount of methanol that needs to be reformed. 
   
   
       22 . The engine systems of  claim 1  or  15  where the space velocity through the methanol reformer is reduced resulting in lower hydrogen rich gas throughputs but lower coke formation over the catalyst. 
   
   
       23 . A spark ignition engine that is fueled with methanol where part of the methanol is reformed into hydrogen-rich gas and where hot hydrogen-rich gas is introduced into the engine at low loads so as to enable ultra lean operation and where the engine is operated with a substantially stoichiometric fuel/air ratio at higher loads and uses a three way catalytic converter and where the reformate is not introduced into the engine at higher loads. 
   
   
       24 . The spark ignition engine of  claim 23  where the hydrogen-rich gas is introduced so as to be concentrated near the spark plug. 
   
   
       25 . The spark ignition engine of  claim 23  where the equivalence ratio is 0.5 or less. 
   
   
       26 . The spark ignition engine of  claim 23  where the temperature of the reformate that is introduced into the engine is between 300 and 700 degrees C. 
   
   
       27 . The spark ignition engine of  claim 23  where the reformer is a hybrid plasmatron/thermal reformer and thermal decomposition reforming is used. 
   
   
       28 . The spark ignition engine of  claim 23  where a higher percentage of reformate is used during cold start. 
   
   
       29 . A fuel management system for a spark ignition engine where a fuel is contained in a first tank and methanol is contained in a second tank;
 and where methanol from the second tank is directed to a reformer which produces a reformate that is used together with the fuel from the first tank in the engine at low loads;   and where the engine operates in an ultra lean mode when the reformer is used; and where when the reformer is not used, the engine operates with a mixture of fuels from the first and second tanks and stoichiometric air/fuel ratio and where a three way catalyst is used to control emission when the engine is operated with a stoichiometric air/fuel ratio.   
   
   
       30 . The fuel management system of  claim 29  where the values of engine torque and speed where the reformer is used is determined by a control system which operates with a preset values for this range. 
   
   
       31 . The fuel management system of  claim 29  where the driver determines the engine operation range over which the reformer is used. 
   
   
       32 . The fuel management system of  claim 29  where the engine operation range over which the reformer is used is determined by an optimization of the ratio of efficiency gain to methanol use over a drive cycle. 
   
   
       33 . The fuel management system of  claim 29  where the relative engine air/fuel ratio lambda is two or more when the reformer is used. 
   
   
       34 . The fuel management system of  claim 29  where hot reformate is introduced into the engine. 
   
   
       35 . The fuel management system of  claim 29  where cold reformate is introduced into the engine. 
   
   
       36 . The fuel management system of  claim 29  where the fuel in first tank is gasoline. 
   
   
       37 . The fuel management system of  claim 29  where fuel in the first tank is natural gas. 
   
   
       38 . The fuel management system of  claim 29  where the fuel in the first tank is propane. 
   
   
       39 . The fuel management system of  claim 29  where the engine is operated with heavy EGR when the reformer is used. 
   
   
       40 . The fuel management system of  claim 29  where methanol from the second tank is introduced into the engine. 
   
   
       41 . The fuel management system of  claim 40  where hot reformate is also introduced into the engine at the same time as the methanol. 
   
   
       42 . The fuel management system of  claim 40  where hot reformate is used at low loads. 
   
   
       43 . The fuel management system of  claim 40  where cooled reformate is used at-high loads. 
   
   
       44 . The fuel management system of  claim 40  where the methanol is port fuel injected. 
   
   
       45 . The fuel management system of  claim 40  where the methanol is direct fuel injected. 
   
   
       46 . The fuel management system of  claim 40  where the compression ratio is 12 or greater. 
   
   
       47 . The fuel management system of  claim 40  where the reformer uses thermal decomposition. 
   
   
       48 . The fuel management system of  claim 40  where the methanol is introduced into the engine at higher loads in the minimal amount required in order to prevent knock. 
   
   
       49 . The fuel management system of  claim 48  where the amount of methanol that is directed to the reformer is reduced or eliminated depending upon the amount of methanol in the second tank. 
   
   
       50 . The fuel management system of  claim 48  where the driver can reduce or eliminate the amount of methanol that is directed to the reformer. 
   
   
       51 . The fuel management system of  claim 48  where the engine on which it is employed has a compression ratio of 12 or greater. 
   
   
       52 . The fuel management system of  claim 29  where methanol is introduced into the engine at low loads. 
   
   
       53 . The fuel management system of  claim 29  where the amount of reformer use is determined by the amount of methanol in the second tank. 
   
   
       54 . The fuel management system of  claim 29  where the reformate is introduced into the engine in a stratified way so as to have a higher concentration near the spark plug. 
   
   
       55 . The fuel management system of  claim 29  where the liquid methanol is introduced into the engine in a stratificed way so as to produce a high concentration in the regions away from the spark that are prone to knocking. 
   
   
       56 . The fuel management system of  claim 29  where the driver can change the relative consumption rates of fuel from the first tank and methanol from the second tank. 
   
   
       57 . The fuel management system of  claim 29  where a control system provides a tradeoff of efficiency gain versus methanol consumption. 
   
   
       58 . The fuel management system of  claim 56  where the tradeoff occurs automatically. 
   
   
       59 . The fuel management system of  claim 56  where the tradeoff is determined by the driver.