Abstract:
Systems and methods of operation for internal combustion engines which employ molecular sieve technology to provide enhanced oxygen content in the air-fuel mixture during operation.

Description:
TECHNICAL FIELD 
     This disclosure is related generally to the operation of internal combustion (“IC”) engines. More particularly, it relates to systems and methods for increasing the level of oxygen in the air admitted into such engines during their normal operation. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     IC engines have been in widespread use for over a century in various employments, owing to the convenience of their operation and the general availability of fuels upon which they depend. In addition to requiring a fuel, generally a hydrocarbon fuel, IC engines also require a source of oxygen for the fuel&#39;s combustion. Oxygen requirement for combustion of a fuel in an IC engine has come from the ambient air in the engine&#39;s surroundings, which air contains about 21% oxygen and about 78% nitrogen on a mass basis. Preferably, this air is filtered prior to being admitted into the combustion chambers of an IC engine, in order to remove dirt and debris which could otherwise have a detrimental effect on operability over the long term. 
     Many workers have sought over the years to increase performance and/or economy of operation of IC engines, by altering parameters associated with either or both the fuel requirement and the oxygen requirement. Many different fuels and additives including oxygenates and metal alkyls have been incorporated into fuels to enhance engine performance. On-board nitrous oxide tanks have been employed to provide enhanced combustion of fuel and greater performance. Other efforts relating to the non-fuel component of combustion included the creation and deployment of superchargers and turbochargers (hereinafter “forced induction”), for use in aviation. These systems survive to this day and may be found in diesel-driven equipment and performance-oriented automobiles. 
     SUMMARY 
     A system useful for operating an internal combustion engine includes an internal combustion engine having an intake manifold and an exhaust manifold, and an oxygen generator including molecular sieves as a functional component having an oxygen effluent therefrom directed to the intake manifold. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a block schematic view of an IC engine system in accordance with the present disclosure; and 
         FIG. 2  shows a block diagram of a control system useful in accordance with operation of an IC engine according to certain embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, wherein the showings are for the purpose of illustrating certain exemplary embodiments only and not for the purpose of limiting the same,  FIG. 1  illustrates a block schematic view of an IC engine system  10  according to one embodiment of the present disclosure. IC engine  3  has an intake manifold  5  and an exhaust manifold  7 . In one embodiment, the intake manifold  5  includes a throttle body for metering air. There is an air filter  9  for filtering air admitted to the IC engine  3 . An exhaust gas aftertreatment device  11  (e.g. catalytic converter) is attached to the exhaust manifold by means of an exhaust conduit  21  attached to the exhaust manifold  7  for purposes of oxidizing both carbon monoxide and unburned hydrocarbons, and the reduction of nitrogen oxides prior to permitting the exhaust gases to escape into the surroundings. An oxygen generator  13  has an effluent conduit  19  through which air having oxygen levels in excess of that of normal atmospheric air. In one embodiment the effluent may be controllably delivered through a valve  15  to the air intake at point A Such provision enables controlled delivery of an air feed containing super-atmospheric levels of oxygen to the IC engine  3 . In one alternate embodiment, the effluent of the oxygen generator  13  is delivered to the air-intake side of the IC engine at point B, through a valve  17 , the effluent conduit  23  in this alternate embodiment being illustrated by the dashed lines in  FIG. 1 . 
     In preferred embodiments, the oxygen generator  13  employs one or more molecular sieves (including “zeolites”, a.k.a. aluminosilicates) as a functional component in providing oxygen for use as described herein, in some embodiments by pressure swing adsorption. Known devices employing molecular sieves which are suitable for employment in this disclosure include, without limitation: Eclipse, Personal Ambulatory Oxygen System (PAOS) from SeQual Technologies, San Diego, Calif., USA; Perfecto2 Oxygen Concentrators by Invacare, Cleveland, Ohio, USA; EverFlo Oxygen Concentrators from Respironics, Murrysville, Pa., USA; Inogen One Oxygen Therapy System from Inogen, Goleta, Calif., USA; and L-6 Oxygen concentrator from OxLife, Hendersonville, N.C., USA. 
     In the case of motorized vehicles including automobiles, trucks, and the like, the oxygen generator  13  may in one embodiment be located in the engine compartment. In other embodiments, the oxygen generator  13  is remotely located, such as in the trunk area, behind a vehicle&#39;s cab, or any other selected location. The effluent of the oxygen generator  13 , which can often be essentially-pure oxygen, is fed through conventional plumbing or ducting commonly employed in the automotive arts to the air intake for the IC engine  3 , and in preferred embodiments is controllably delivered thereto by means of control valves including by way of example, those such as  15 ,  17 . 
     According to one embodiment, the control valves  15 ,  17  are solenoid-actuated valves. In an alternate embodiment, the control valves  15 ,  17  are vacuum-actuated. In yet other alternate embodiments, the control valves  15 ,  17  are actuated electrically, electromechanically, or using smart materials in mechamatronic devices. Regardless of the motive energy or method used for switching or controlling the valves employed, the control valves  15 ,  17  are preferably of the type which can provide for a wide range of flow rate capabilities of the effluent from the oxygen generator  13 . Such valves are well-known in the automotive arts and are found in exhaust gas recirculation (“EGR”) valves, to cite but one non-limiting example. Additional control over the amount of oxygen provided may be achieved by varying the voltage input to the oxygen generator  13 , such as through a microprocessor of the type commonly employed in automotive applications, wherein signals from various sensors disposed at locations on the IC engine  3  are used to provide input parameters which the microprocessor uses to make decisions concerning supplemental oxygen flow to the intake manifold provided by the oxygen generator  13 . 
     In one embodiment, one or more oxygen sensors are provided in pre-intake or post-combustion locations such as the intake manifold, the conduit  21  or at location C in  FIG. 1 , which is after the exhaust gas aftertreatment device  11 . 
     In accordance with an IC engine system as provided herein, the amounts of nitrogen oxides (NOx) in the exhaust gas may be significantly reduced by providing supplemental oxygen to the intake manifold side of the IC engine  3 . Although not to be construed as limiting the present disclosure in any fashion, it is theorized that a portion of this reduction of NOx may be due to the fact that less nitrogen is present in the intake air when the intake air contains enhanced levels of oxygen, as provided hereby. Additionally, increased thermodynamic efficiency of the IC engine  3  is achieved by increased combustion efficiency. For IC engines being operated using diesel fuel or gasoline as fuel, this means that the production of soot, carbon monoxide (“CO”) and unburned hydrocarbons (“HC”) in the exhaust gas effluent of the engine may be substantially reduced and often eliminated. In some embodiments, the NOx or HC or soot or CO content of the exhaust gas exiting an engine operated according to this disclosure is reduced by at least 50% on a molecular mass basis. In other embodiments the content of more than one of these undesirable gaseous effluent substances is so reduced. In some embodiments, the NOx or HC or soot or CO content of the exhaust gas exiting an engine operated according to this disclosure is substantially eliminated. In other embodiments the content of more than one of these substances is substantially eliminated. These reductions lessen the burden on catalytic converters and other engine exhaust effluent treatment devices and may in some cases even eliminate the need for such exhaust effluent treatment devices as catalytic converters. In embodiments where the burden on a catalytic converter is reduced, the exhaust restriction inherently associated with the use of a catalytic converter can accordingly be lessened, providing increased volumetric efficiency for a given engine. Additionally, cold-start emissions of an IC engine may be significantly reduced through enhancement of the oxygen content of the air intake charge. 
       FIG. 2  shows a block diagram of a control system useful in accordance with operation of an IC engine according to an embodiment of the disclosure.  FIG. 2  illustrates a microprocessor  31 , which controls the valves  15 ,  17 , and in alternate embodiments additionally or independently controls the electrical energy inputted to the oxygen generator  13  via means of a relay or solid-state switch, such as from an electrical storage battery or electrical generation means. Engine sensors  33 ,  35 ,  37 , one or more of which may be present in different embodiments, are employed to provide data to the microprocessor  31  in order to effectuate control over the amount of oxygen from the oxygen generator  13  which is delivered to the air intake side of the IC engine  3 . These sensors  33 ,  35 ,  37  may be sensors including, without limitation, oxygen sensors, mass airflow sensors, manifold absolute pressure sensors, crankshaft position sensors, hydrocarbon sensors, NOx sensors, intake air mass flow sensors, engine r.p.m. sensors, knock sensors, coolant temperature sensors, oil temperature sensors, and external temperature sensors. In one embodiment, the delivery of supplemental oxygen from the oxygen generator  13  is controlled based on data provided by an oxygen sensor disposed in the conduit  21 , to be the presence of a slight excess of oxygen in the engine exhaust effluent at that point, on the order of at least about 0.05% to 1%, or more, on a mass basis. Alternately, such oxygen sensor may be disposed at any location in the exhaust gas stream of the engine  3 . In another embodiment, the delivery of supplemental oxygen from the oxygen generator  13  is controlled based on data provided by a knock sensor disposed in any location in, on, or near the engine block, and the oxygen content of the intake air is adjusted until no knocking is sensed for the operating conditions present at any given point in time. In another embodiment, the delivery of supplemental oxygen from the oxygen generator  13  is controlled in part based on data provided by an oxygen sensor disposed in the intake manifold  5  of the IC engine  3 . In yet another embodiment, the delivery of supplemental oxygen from the oxygen generator  13  is controlled based on data provided by a NOx sensor disposed at any location in the effluent exhaust stream of the IC engine  3 . 
     In one embodiment, in  FIG. 2  the device  39  controls fuel metering, such as by fuel injectors or other fuel delivery devices, in order to adjust fuel consumption based on input gathered from other sensors, including the aforesaid, which may be present. In one embodiment, the fuel delivery is controlled to provide a less-than-stoichiometric amount of fuel to the engine (i.e. lean operation). In another embodiment, the fuel delivery is controlled to provide a stoichiometric amount of fuel to the engine. In yet another embodiment, the fuel delivery is controlled to provide a greater-than-stoichiometric amount of fuel to the engine (i.e. rich operation). 
     In another embodiment, control device  41  present in a system according to the disclosure, which control device  41  is an exhaust gas recirculation valve, is controlled by the microprocessor  31  to result in amounts of exhaust gas recirculation which effect the least amount of NOx in the engine&#39;s exhaust effluent as sensed by a NOx sensor that is disposed at any desired location in the effluent exhaust stream for given operating conditions of the IC engine  3 . 
     A system  10  as provided hereby can be retrofitted to existing engines and motorized vehicles containing same, since the goals of current design of microprocessor-controlled engines is typically in line with that achieved by supplementing the intake air with oxygen according to this disclosure. Thus, for example, a supercharger may be displaced and an oxygen generator  13  substantially substituted in its stead, and the means for controlling the boost pressure on the former supercharger can instead control the valve  15 ,  17 , or in alternate embodiments the operational energy to the oxygen generator  13 , to afford effective control over the oxygen content of the intake charge, thus eliminating the supercharger while retaining the essentially the same benefits thereof without the shortfalls associated with boosted intake pressures. In some embodiments of this disclosure, oxygen from the oxygen generator  13  is delivered only under full-throttle or near full-throttle conditions, such as 80% full-throttle or greater as measured by airflow through a throttle body. 
     The disclosure has described certain preferred embodiments and modifications thereto. Further modifications and alterations may occur to others upon reading and understanding the specification. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.