Abstract:
A non-engine based exhaust component rapid aging system comprises a combustor in fluid communication with an air and a fuel supply; and a first emission analyzer in fluid communication with said combustor, wherein said first emission analyzer and said combustor are further capable of being disposed in fluid communication with an exhaust component; and wherein said non-engine based exhaust component rapid aging system is capable of operation at an air to fuel ratio of about 7 to about 16.  
     The non-engine based rapid aging method comprises combusting fuel with air to produce exhaust gas; controlling a temperature of said exhaust gas; supplying said exhaust gas to said exhaust component; and analyzing a composition of said exhaust gas.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of the filing date of U.S. Provisional application Ser. No. 60/200852, filed May 1, 2000, which is incorporated herein in its entirety. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    Catalytic converter performance in an automobile will deteriorate over time due to such things engine misfire, a faulty oxygen sensor, poisoning, or prolonged high temperature operation. Deterioration of the catalytic converter in turn affects the catalyst&#39;s effectiveness for preventing the emission of undesired exhaust gases such as carbon monoxide (CO), nitrogen oxides (NO x ), and hydrocarbons (HC).  
           [0003]    [0003]FIG. 1 is a sectional view of a catalytic converter illustrating a catalyst-laden substrate wrapped in a support mat and inserted inside a shell. A catalytic converter  10  includes an inlet  30 , an outlet  50 , a shell  12 , a catalyst-laden substrate  14 , and a support mat  16  positioned between shell  12  and catalyst-laden substrate  14 . Each of the inlet port  30  and outlet port  50  is made a form of cone. Support mat  16  is preferably in intimate contact with either catalyst-laden substrate  14  or an inner surface  18  of shell  12 . Alternatively, support mat  16  is in intimate contact with both catalyst-laden substrate  14  and inner surface  18  of shell  12 .  
           [0004]    Shell  12  may be of any geometric configuration that facilitates the intake of exhaust gas through the inlet port  30  that receives an inlet pipe extending from the internal combustion engine, allows the gas to flow through the shell  12  and contact the catalyst-laden substrate  14 , and flow out of the shell  12  through the outlet port  50 .  
           [0005]    Support mat  16 , which is disposed between the catalyst-laden substrate  14  and the shell  12 , insulates the shell  12  from the catalyst-laden substrate  14  when the catalyst-laden substrate  14  reaches its operating temperature.  
           [0006]    The composition of the catalyst is well known in the art and is typically disposed on the substrate  14  by a method well known in the art. Catalyst-laden substrate  14  is placed in the center of catalytic converter  10 . Common catalysts include nitrous oxide catalysts, three-way conversion (TWC) catalysts, or similar compositions that typically comprise noble metals, various metal oxides (e.g., titania, silica, alumina, ceria, tantala, zirconia, etc.) or mixtures and alloys thereof, as well as cordierite, vermiculite, and/or ceramic fiber.  
           [0007]    The catalyst material comprises a multitude of passageways for reacting and converting byproduct exhaust gases. FIG. 2 illustrate a catalyst substrate passage with exhaust gas interaction, prior to aging. In FIG. 2, reference numeral “ 20 ” represents a surface of one of these passageways. The catalyst substrate contains pores  22  within substrate layers to provide sufficient surface areas for exhaust gases from the engine to contact a catalyst  24 . When CO, NO x , and HC contact the catalyst  24 , the molecules are substantially reacted with residual oxygen to produce carbon dioxide (CO 2 ) and nitrogen (N 2 ).  
           [0008]    However as a catalytic converter ages with use, pores  22  begin to collapse thereby causing the catalytic converter to become less efficient in removing the undesired byproducts, i.e., CO, NO., and HC. In FIG. 3, some of the catalyst  24  is shown coalesced into larger particles. When the catalyst  24  coalesces and becomes larger due to aging, the amount of surface area available for catalytic reactions is reduced. Thereby, the efficiency in reducing the output of the byproducts is reduced. Modeling of the efficiency reduction in aging process helps developing exhaust treatment devices such as improved catalysts, catalytic converters, and/or oxygen sensors.  
           [0009]    Further, a recent trend in legislation of automobile exhaust emissions is being focused on reducing emissions throughout the whole term of usage. To meet emission regulations, an automobile must have a catalytic converter which meets a certain requirement. That is, after 100,000 miles of running, the catalytic converter should maintain its performance of removing undesired emission gases in an optimum level which is required in a related regulation.  
           [0010]    Therefore, it is useful to measure the degradation of a catalyst&#39;s performance as it ages. To gauge the aging performance, one method of practice has been to test catalysts by aging the catalysts using road testing with an automobile. However, this method of testing is both costly and time consuming.  
           [0011]    An alternative method has been to modify an engine to artificially age the catalyst in order to avoid the necessity of road testing. As such, attempts have been made to alter the operation of the engine and artificially accelerate the aging process. The purpose of modifying the engine operating conditions is to assure that, after exposure to the accelerated aging, the catalyst reacts to emission gases in a similar manner as the catalysts which have been actually aged on a vehicle.  
           [0012]    To simulate a field aged catalyst, prior methods include placing a catalyst on engine dynamometers and inducing various levels of misfire in order to degrade catalyst performance to the required threshold level. However, under steady state conditions, it is difficult to achieve the necessary temperatures to degrade or age the catalyst to a desired efficiency level within a reasonable time. Also, considerations about the availability of engine dynamometers and other resources required to meet the demand for threshold catalyst hardware with the misfire method may be limited.  
           [0013]    As an alternative method, there has been an oven aging. Catalyst bricks are removed from the converter shell assembly and baked in an oven at temperatures ranging between 1,000 and 1,350° C. for 2-32 hours. After aging, the bricks are recanned and installed onto the vehicle. The vehicle is then usually driven for a few hundred miles to provide for a stabilization or break-in period prior to emission testing. However, it is difficult to determine the appropriate aging time and temperature required to degrade the catalyst performance to a specified level for a given vehicle.  
         SUMMARY OF THE INVENTION  
         [0014]    A non-engine based exhaust component rapid aging system comprises a combustor in fluid communication with an air and a fuel supply; and a first emission analyzer in fluid communication with said combustor, wherein said first emission analyzer and said combustor are further capable of being disposed in fluid communication with an exhaust component; and wherein said non-engine based exhaust component rapid aging system is capable of operation at an air to fuel ratio of about 7 to about 16.  
           [0015]    The non-engine based rapid aging method comprises combusting fuel with air to produce exhaust gas; controlling a temperature of said exhaust gas; supplying said exhaust gas to said exhaust component; and analyzing a composition of said exhaust gas.  
           [0016]    The above-discussed and other features will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    Referring now to the drawings, which are meant to be exemplary, not limiting:  
         [0018]    [0018]FIG. 1 is a sectional view of a catalytic converter;  
         [0019]    [0019]FIG. 2 is an illustration of a catalyst substrate passageway with exhaust gas interaction, prior to aging;  
         [0020]    [0020]FIG. 3 is an illustration of an aged catalyst substrate passageway with exhaust gas interaction;  
         [0021]    [0021]FIG. 4 is a schematic view of one embodiment of the rapid aging system;  
         [0022]    [0022]FIG. 5 is a schematic view of another embodiment of the rapid aging system;  
         [0023]    [0023]FIG. 6 is a perspective view of a stand including a combustor tube installed therein;  
         [0024]    [0024]FIG. 7 is a perspective view of a portion of the combustor as shown in FIG. 6;  
         [0025]    [0025]FIG. 8 is a graphical illustration of one example of the temperature control attainable with the non-engine based system.  
         [0026]    [0026]FIG. 9 is a graphical illustration of the temperature control attainable with the non-engine based system even at variable air to fuel ratios.  
         [0027]    [0027]FIG. 10 is a graphical illustration of stable exhaust temperature (e.g., the temperature control attainable) with the non-engine based system even at variable air to fuel ratios.  
         [0028]    [0028]FIG. 11 is a graphical illustration of an elevated temperature (1,060° C.) test for very rapid aging of a converter catalyst at a constant fuel flow of 0.4 grams/second (variation in the air to fuel ratio is due to the current method of air measurement).  
         [0029]    [0029]FIG. 12 is a graphical illustration of the lack of temperature control with the engine based system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    The catalyst rapid aging system described herein can be used to age a catalyst converter, or other test specimen utilizing a feed stream of gases that are of a similar composition, temperature, and mass flow rate as those of a spark ignition engine such as an automobile engine.  
         [0031]    Referring to FIG. 4, a schematic view of one embodiment of the rapid aging system, connected to a test converter  150  as a test device, is shown.  
         [0032]    The rapid aging system comprises a combustor  120 , a heat exchanger  130 , and a first emission analyzer  160  connected to a line  135  between the heat exchanger and the test converter  150 . Like the line  135 , between components, a connecting line or tube is placed to ensure an operable communication through the system such that the exhaust gas produced in the combustor  120  is supplied to the test converter  150  for aging.  
         [0033]    Following the heat exchanger, a laminar flow element  140  can be connected. The rapid aging system can further comprise an ignition element  122  and a blower  110  before the combustor. Also, the rapid aging system can further include a temperature sensor  162  following the heat exchanger  130 . A second emission analyzer  164  can be included after the test converter  150 .  
         [0034]    The combustor  120  is supplied with air from a blower  110  and fuel  114  to produce exhaust gases. Also as shown, additional air  112  can be supplied to the combustor  120  if desired. An ignition source  122  provides the input of energy to allow combustion of the fuel and air in the combustor  120 . After the air/fuel mixture is combusted, the exhaust gases pass through the heat exchanger  130 . Passing throughout the heat exchanger  130 , the exhaust gas is cooled to a desired temperature. A coolant  132  is used to provide a desired exposure temperature to age the test converter  150 . If desired, a laminar flow element (LFE)  140  can be used to measure the flow of the exhaust gas is provided to the test converter  150  state. After passing through LFE  140  and prior to the exhaust gas entering the converter  150 , the exhaust gas temperature can be measured by the temperature sensor  162  for control of the system. Also, the first emission analyzer  160  can be used to measure the composition of the exhaust gas being admitted to the test converter  150 . As the emission analyzer, a gas sensor such as a wide range air/fuel sensor can be employed. After passing through the test converter  150 , the second emission analyzer  164  can be used to measure the composition of the exhaust gas. Similarly, a wide range air/fuel sensor can be used for the second emission analyzer  164 .  
         [0035]    By using one or more emission analyzers, the system can be controlled so as to accurately provide exhaust gases to age the test converter  150 . By providing an accurate exhaust gas flow to the test converter  150 , an accurate aging analysis of the test converter  150  can be achieved. Alternatively, other devices requiring aging can be aged and tested in place of or along with the test converter  150 . For example, an oxygen sensor can be aged using this system.  
         [0036]    In FIG. 5, another embodiment of the rapid aging system is shown. While only one connecting line is represented as reference numeral “ 235 ” in FIG. 5, a connecting line or tube through which the exhaust gas flows is placed between components. A combustor  220  is fed with supplies of air (A) and fuel (F). After the fuel is combusted in combustor  220 , the exhaust gas is optionally fed to a turbocharger  222  wherein the pressure and amount of exhaust gas finally supplied to a test converter  250  can be adjusted. Additional air can be provided to the turbocharger  222  or a portion of the exhaust gas can be vented from the turbocharger  222 . After the turbocharger  222 , the temperature of the exhaust gas is measured by a temperature sensor  268  for control of the system and particularly for control of a heat exchanger  230 . Also at this stage, a second emission analyzer  264  can be used to determine the exhaust gas composition for control of the system, particularly for the input of air and fuel into the combustor  220 .  
         [0037]    Thereafter, the exhaust gas flow is directed through the heat exchanger  230 . As shown, the heat exchanger  230  is fed with a coolant. By thermal exchange between the coolant and the exhaust gas, the exhaust gas is brought to a desired temperature for exposure to the converter  250  for aging. Optionally, a temperature sensor  262  can be used to measure the temperature of the exhaust gas for control of the system. A first emission analyzer  260  samples the exhaust gas prior to the test converter  250 , for system control, particularly for the input of air and fuel into the combustor  220 . Also, additional exhaust gas or contaminant can be added to the exhaust gas flow by a contaminant supplier  266 . As the contaminant, any contaminants commonly found in exhaust gases can be used, for example, zinc dialkyldithiophosphate (ZDP) which serves as a lubricating additive for corrosion resistance, wear resistance, and antioxidation.  
         [0038]    After treatment by the rapid aging system, the exhaust gas is fed to the test converter  250  for aging thereof. Optionally, an additional emission analyzer (not shown) can measure the exhaust gas composition after passing through the test converter  250  for system control. Alternatively, other devices, such as oxygen sensors requiring aging can be aged and tested in place of or along with the test converter  250 .  
         [0039]    [0039]FIG. 6 is a perspective view illustrating one embodiment of the combustor mounted on a stand. In FIG. 6, reference numeral  300  represents a stand, and reference numeral  320  represents a combustor. The combustor is not limited to a specific structure. The combustor can be made in a simple tubular form as shown in FIG. 6. The non-engine based rapid aging system is highly portable and can be made in a small size. Also, the system is very safe because it is not based on an internal combustion engine with rotating shafts. Simplified structure enables the system to be easily controlled, thus, aging variability can be minimized and aging process can be expedited.  
         [0040]    [0040]FIG. 7 is a perspective view of a portion of the combustor as shown in FIG. 6, and illustrates one embodiment of connecting several suppliers such as blower inlet, fuel inlet, injector power cord, and spark ignition to the combustor  320 .  
         [0041]    Using the system as shown in FIG. 4, rapid aging tests were performed. The test results are graphically illustrated in FIGS.  8 - 11 . In FIG. 8, the non-engine based system illustrated good temperature control, e.g., a temperature variation of about 20° C. or less, with about 110° C. or less preferred, about 5° C. or less more preferred, and a temperature variation of about 2° C. or less especially preferred. In contrast, an engine based test system illustrated a temperature variation of about 40° C., with temperature variations of about 100° C. or greater common. (See FIG. 12). In engine based test systems, and/or to the temperature varies due to the speed or torque control of the dynamometer, to the addition of fuel to maintain a stoichiometric air to fuel ratio. Basically, the engine based test system does not control temperature; the temperature is a function of the system and not controlled. A problem with lack of temperature control is the destruction of the test part, e.g., a catalytic converter, due to melting of the brick under extreme conditions. By controlling the temperature, the non-engine based system is capable of eliminating the failure mode associated with destruction of the test part by excessive heat, and of accelerating aging.  
         [0042]    [0042]FIGS. 9 and 10 further illustrate the ability of the non-engine based rapid aging system to maintain exhaust gas temperature (lines  62  and  72 , respectively), while varying the input fuel, evidenced by the air fuel ratio (lines  60  and  70 , respectively).  
         [0043]    Finally, FIG. 11 illustrates an elevated temperature test (i.e., 1,060° C.) for very rapid aging of a converter catalyst. Beyond further illustrating the ability to maintain the temperature, the graph proves that the non-engine based system can be operated at extreme air to fuel ratios. Engine based aging systems can only operate near stoichiometry. This non-engine based system can operate at rich, namely at an air to fuel ratio of about  10  or less, with about 7 or less, and even about 2 or less possible. (See line  84 ) On the lean side, the air to fuel ratio can reach and exceed about 16, with a ratio of about 17 and greater also possible.  
         [0044]    As described above, the rapid aging system is non-engine based system. By using the non-engine based rapid aging system, the efficiency of a catalytic converter can be projected throughout its lifetime more accurately and consistently as compared with an engine-based system.  
         [0045]    The non-engine based exhaust component rapid aging system provides advantages of simplifying a catalytic converter test (or other exhaust component) and a testing hardware. This is achieved by eliminating the need for spark ignition engine, e.g., automobile engine, which thereby reduces the costs associated with converter aging and testing. Another advantage is the reduction of testing variability due to the improved controllability of the exhaust gas composition. Pressure, mass flow and temperature of the exhaust gas can be controlled as well. The reduction in testing variability provides better data for design of products such as catalytic converters, oxygen sensors, particulate traps, and the like.  
         [0046]    This system allows for a lean air to fuel testing arrangement, which thereby allows for rapid changes between different products for testing and aging. This is achieved by changing the system control program and test sample. Further, unlike engine based aging systems which operate around stoichiometric air to fuel ratios (12 to about 16.7), this non-engine based system is capable of operating at an air to fuel ratio of about 10 or less, with about 7 or less and even about 2 or less possible. Air to fuel ratios exceeding about 15.5 are similarly possible, with ratios of about 17 and even about 18 or greater possible.  
         [0047]    Since the combustor of the rapid aging system can produce temperatures similar to an engine, performance testing and aging can be accomplished. Further, when the optional heat exchanger is employed, aging time can be diminished and better controlled than with an engine based test rig. In addition to temperature control, the system enables contaminant control by allowing the introduction of, or increased concentration of contaminants, e.g., sulfur, nitrogen oxides, and the like, prior to the exhaust component.  
         [0048]    The non-engine based rapid aging system is highly portable and can be made in a small unit. Also, the system is very safe compared with engine-based systems. It is very simple to control the system, thus, aging variability can be minimized and aging process can be expedited.  
         [0049]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.