Abstract:
A recovery system for fuel for motor vehicles includes a canister having an absorbent media such as activated charcoal. The canister includes an inlet in fluid communication with the blow-by vent of an internal combustion engine and an outlet in communication with the air intake manifold of the engine. Control valves may be incorporated into the system to control fluid flows. As a single vaporization temperature fuel or fuel constituent such as ethanol that has mixed with engine oil during startup vaporizes when the oil reaches its vaporization temperature, it is first absorbed in the activated charcoal and then slowly released and burned in the engine. The system has particular applicability to E85 fueled vehicles.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates generally to fuel recovery systems for internal combustion engines and more particularly to a recovery systems for the ethanol constituent of E85 fuel for use with internal combustion engines. 
     2. Description of the Prior Art 
     One of the very first sources of emissions targeted for reduction in internal combustion engines utilized in passenger cars and other motor vehicles was blow-by, i.e., air and unburned fuel that enters the crankcase and is emitted into the atmosphere by a breather vent in a valve cover. 
     Since the early 1960s, positive crankcase ventilation (PCV) systems have been utilized which collect and direct the unburned fuel to the carburetor or intake manifold where it is burned in the cylinders. These systems not only eliminated this source of pollution but also slightly improved fuel economy as they ensured that fuel that was previously lost by dispersal into the atmosphere was burned in the engine. 
     At normal engine operating temperatures, well above the volatilization temperatures of the various fractions of conventional hydrocarbon fuel, i.e., gasoline, fuel in the blow-by moves directly through the PCV system and there is no accumulation of fuel in the crankcase. However, at start-up and in low temperature operating conditions, the fuel will condense in the crankcase. As the engine warms up, this condensed fuel vaporizes and is swept through the PCV system. Because gasoline comprises many different hydrocarbon fractions that vaporize at different temperatures, this vaporization occurs gradually over a period of time. 
     Recently a low emission fuel manufactured from agricultural products, primarily corn, and designated E85 has become available for consumer use in passenger cars. The fuel is nominally 85% ethanol or grain alcohol. When an E85 fueled vehicle is started or operated in a low temperature environment, some of the ethanol enters the crankcase in liquid form and mixes with the engine lubricating oil. As the engine warms up and reaches 78 degrees Celsius (172.4 degrees Fahrenheit) all of the ethanol in the crankcase vaporizes and flows through the PCV system at a very high rate. Even though the oxygen sensor has shut off fuel flow to the cylinders, in extreme cases there may be so much vaporized ethanol flowing through the PCV system that the engine runs rich and exhaust emissions are increased. At the very least, this high momentary flow of vaporized ethanol through the PCV system and engine is difficult for the engine control system to compensate for. Additionally, this event may result in drivability issues. 
     From the foregoing, it is apparent that improvements in fuel systems for vehicles utilizing E85 as fuel are desirable. 
     SUMMARY OF THE INVENTION 
     A fuel recovery system for a single vaporization temperature fuel or fuel constituent such as ethanol of E85 fuel for motor vehicles includes a canister filled with an absorbent media such as activated charcoal. The canister includes an inlet in fluid communication with the crankcase blow-by vent of an internal combustion engine, an outlet in communication with the air intake manifold of the engine and a vent communicating with the atmosphere. Control valves may be incorporated into the system to control fluid flows. As ethanol that has been mixed with engine oil during startup and before the engine reaches operating temperature vaporizes when the oil reaches approximately 78 degrees Celsius, it is first absorbed in the activated charcoal and then slowly released and burned in the engine. The slow release and burning of the ethanol from the canister avoids a brief transient condition that may interfere with engine operation and increase emissions. A passive fuel recovery system is also disclosed. 
     Thus it is an object of the present invention to provide an apparatus for temporarily absorbing fuel such as ethanol from crankcase blow-by of an internal combustion engine. 
     It is a further object of the present invention to provide an apparatus for absorbing fuel such as ethanol from a crankcase of an internal combustion engine having a canister communicating with the blow-by vent of the engine and its intake manifold. 
     It is a still further object of the present invention to provide an apparatus for absorbing fuel such as ethanol from blow-by from a crankcase of an internal combustion engine and providing it to the engine intake manifold over a period of time. 
     It is a still further object of the present invention to provide an apparatus for temporarily absorbing fuel such as ethanol from blow-by from an internal combustion engine having a canister containing activated charcoal. 
     Further objects and advantages of the present invention will become apparent by reference to the following description and appended drawings wherein like reference numbers refer to the same component, element or feature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagrammatic view of a first embodiment of an E85 ethanol or fuel recovery system associated with an internal combustion engine, and 
         FIG. 2  is a diagrammatic view of a second embodiment of an E85 ethanol or fuel recovery system associated with an internal combustion engine. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , a fuel recovery system for an internal combustion engine is illustrated and designated by the reference number  10 . The system  10  is connected to and utilized in conjunction with an internal combustion engine  12  having an engine block  14  defining a plurality of cylinders  16 , a like plurality of pistons  18  connected to a crankshaft  22 , one or two cylinder heads  24 , one or more valve covers  26  and an intake manifold  28 . 
     The fuel recovery system  10  includes an oil separator  32  which may be connected to the interior of one or both of the valve covers  26  by a conduit, pipe or hose  34 . The oil separator  32  includes baffles  36  or other flow interrupting or redirecting structures which collect oil mist or droplets which have been carried by the blow-by flow from within the valve covers  26 . By virtue of its location above the valve covers  26 , oil that collects in the oil separator  32  flows back into the valve covers  26  and the engine  12  by gravity. 
     A second conduit, pipe or hose  38  provides a fluid pathway between the oil separator  32  and a recovery canister  40 . The recovery canister  40  may be any convenient regular or irregular shape such as cylindrical or rectangular and may be fabricated of, for example, a rugged plastic such as acrylonitrile-butadiene-styrene (ABS). The canister  40  is filled with an absorbent of E85 such as activated charcoal  42  or other suitable media. Preferably at the bottom of the canister  40  or, in any event, opposite the second, inlet pipe or hose  38  is an orifice or vent  44  which communicates with the atmosphere. 
     A third conduit, pipe or hose  46  communicates between the interior of the canister  40  and a solenoid control valve  48 . The control valve  48  is opened and closed by signals emanating from an engine control module  50 . The engine control module  50  is typically a microprocessor which includes inputs for signals from various engine and vehicle sensors (not illustrated) and controls various operating conditions and parameters of the engine  12 . For example, an engine temperature sensor  52  may be utilized to provide a data signal to the engine control module  50  regarding the current temperature of the engine  12 . 
     A fourth conduit, pipe or hose  54  provides a fluid pathway between the control valve  48  and the intake manifold  28 . A flow controller  56  which may be either an orifice having a predetermined size and thus flow rate or a second solenoid control valve controls flow from the fourth pipe or hose  54  to the interior of the valve covers  26  of the engine  12 . 
     The operation of the fuel recovery system  10  will now be described. For this description, it will be assumed that the engine  12  is fueled with E85 and is cold and at an ambient temperature which typically will be in the range of 20 degrees to 70 degrees Fahrenheit. Of course, depending upon the climate and season, temperatures may readily be encountered that are outside this range, sometimes substantially. When started in this condition, an engine  12  utilizing E85 fuel will experience blow-by of the fuel into the crankcase  22  and mixing of the E85 fuel and particularly the ethanol with the engine oil. The solenoid control valve  48  will preferably be closed at this time and the flow controller  56 , if it is a valve, will be open. This situation will continue until the engine  12  and, more specifically, the oil have reached a temperature of 78 degrees Celsius (172.4 degrees Fahrenheit). 
     At this point, the ethanol will begin to vaporize rapidly and blow-by containing ethanol will exit the valve covers  26 , enter the oil separator  32  where oil is removed from the blow-by and returned to the engine  12  and enter the recovery canister  40  where the ethanol is absorbed in the activated charcoal  42 . The vent  44  in the canister  40  allows flow of ethanol and air into the canister  40  from the valve covers  26  and exhaust of cleansed air into the atmosphere. Rather quickly, all of the ethanol will vaporize and be absorbed by the activated charcoal  42 , as described. 
     The engine operating temperature and the temperature of the engine oil will continue to rise. At a temperature well above 78 degrees Celsius, for example, 95 to 100 degrees Celsius (203 to 212 degrees Fahrenheit)or higher, the engine control module  50  or other controller will issue a command to open the solenoid control valve  48  and, if the flow controller  56  is a solenoid valve, issue a command to close it. In this operating condition, the partial vacuum in the intake manifold  28  will draw atmospheric air in through the vent  44  of the canister  40  which will absorb and carry with it ethanol from the activated charcoal  42 . This air and ethanol will then flow through the fourth pipe or hose  54 , be drawn into the intake manifold  28  and the cylinders  16  and be burned. 
     Over a period of time of normal driving, substantially all of the ethanol will be purged from the canister  40 . Thus, E85 or any other fuel having substantially a single vaporization temperature, will be absorbed in the activated charcoal  42  and then slowly returned or metered into the blow-by flow to the intake manifold  28  and the cylinders  16  where it is burned. 
     After an additional period of time, the solenoid control valve  48  may be closed and the flow controller  56  may be opened if it is a valve to allow blow-by from the engine  12  to flow directly from the valve covers  26  to the intake manifold  28  in accordance with conventional positive crankcase ventilation practice. 
     Referring now to  FIG. 2 , a second embodiment of the fuel recovery system according to the present invention is illustrated and designated by the reference number  100 . The system  100  is quite similar to the first embodiment system  10  and is typically utilized with an internal combustion engine  12  having components as listed and described in  FIG. 1 . Such description will therefore not be repeated. The system  100  may be fairly described as passive in that it includes a fresh air intake line  102  which communicates with a source of fresh air such as an air inlet duct  104  and the interior of the valve covers  26 . A positive crankcase ventilation (PCV) valve  106  in another one of the valve covers  26  feeds an outlet line or hose  108  which extends between the other one of the valve covers  26  (or the opposite end of the valve cover  26  if there is only one) and a canister  110  containing activated charcoal  112 . From the canister  110 , a return line or hose  116  extends to the intake manifold  28 . 
     The passive fuel recovery system  100  essentially operates continuously in the positive crankcase ventilation circuit of the engine  12 . As such, blow-by from the engine  12  constantly circulates through the line  106  and the activated charcoal  112  in the canister  110 , the flow being established by the partial vacuum in the intake manifold  28  and supplied by the fresh air inlet line  102 . 
     During warm up of the engine  12  utilizing E85 or other fuel having substantially a single vaporization temperature, the relatively sudden and significant flow of, for example, ethanol, will be absorbed in the activated charcoal  112  and then slowly returned or metered to the blow-by flow in the return line  116  to the intake manifold  28  and burned in the cylinders  16  of the engine  12 . 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.