Abstract:
A method and kit for determining the effectiveness of an exhaust filter. The method may involve exposing an indicator to an exhaust stream of a engine downstream of the exhaust filter, visually comparing the indicator against test samples, and assigning a level of exhaust filter effectiveness based on the comparison. The method may also involve restricting the exhaust stream, diverting a test stream of exhaust from the exhaust stream, and exposing the indicator to the test stream. The kit may include a collector having a housing defining a flow passage configured to transmit a test stream of exhaust from a engine and a restrictor having a orifice plate configured to restrict an exhaust stream from which the test stream is diverted.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to engine exhaust aftertreatment systems and more particularly to testing of exhaust filters. 
       BACKGROUND 
       [0002]    Engine exhaust aftertreatment systems may include filters such a diesel particulate filters (DPFs) to trap particulate matter or soot contained in exhaust. These filters may develop cracks or otherwise fail, reducing their effectiveness. Detecting that a filter failure has occurred may be difficult because the filter may not be visible and any change to the exiting exhaust may be difficult to perceive. 
         [0003]    U.S. Pat. No. 7,334,401 discloses a sensor for sensing the presence of particulates in a gas flow stream. Such a sensor, however, would be too expensive and not robust enough to use in regular field tests. 
       SUMMARY 
       [0004]    The present disclosure provides a method for determining the effectiveness of an exhaust filter. In one aspect, the method includes exposing an indicator to an exhaust stream of a engine downstream of the exhaust filter, visually comparing the indicator against test samples, and assigning a level of exhaust filter effectiveness based on the comparison. 
         [0005]    In another aspect, the method includes restricting the exhaust stream, diverting a test stream of exhaust from the exhaust stream, and exposing the indicator to the test stream 
         [0006]    The present disclosure also provides a kit for determining the effectiveness of an exhaust filter. The kit includes a collector having a housing defining a flow passage configured to transmit a test stream of exhaust from an engine and a restrictor including an orifice plate configured to restrict an exhaust stream from which the test stream is diverted. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a diagrammatic view of a machine including a power system with an aftertreatment system. 
           [0008]      FIG. 2  is a diagrammatic view of the machine from  FIG. 1  in a test mode. 
           [0009]      FIG. 3  is a diagrammatic view of an alternative embodiment of the machine from  FIG. 1  in the test mode. 
           [0010]      FIG. 4  is a diagrammatic view of an alternative embodiment of the machine from  FIG. 1  in the test mode. 
           [0011]      FIG. 5  is a side view of a collector. 
           [0012]      FIG. 6  is a cross-sectional side view of the collector from  FIG. 5 . 
           [0013]      FIG. 7  is a top view of an indicator and a grading sheet. 
           [0014]      FIG. 8  is a side view of a measurement device used as an alternative to the grading sheet. 
           [0015]      FIG. 9  is a flow chart of a testing method. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]      FIG. 1  shows a machine  1  in an operation mode  3 . The machine  1  includes a power system  10 . The machine  1  is shown as a mobile machine but could be stationary. The machine might be a mobile machine, on-highway truck, car, vehicle, off-highway truck, earth moving equipment, tractor, generator, pump, aerospace application, locomotive application, marine application, or any other device or application requiring a power system  10 . 
         [0017]    The power system  10  includes an engine  12  and an aftertreatment system  14  to treat an exhaust stream  16  produced by the engine  12 . The engine  12  may include other features not shown, such as controllers, fuel systems, air systems, cooling systems, peripheries, drivetrain components, turbochargers, exhaust gas recirculation systems, etc. The engine  12  may be any type of engine (internal combustion, gas, diesel, gaseous fuel, natural gas, propane, etc.), may be of any size, with any number of cylinders, and in any configuration (“V,” in-line, radial, etc.). 
         [0018]    The aftertreatment system  14  is configured to remove, collect, or convert undesired constituents from the exhaust stream  16 . The aftertreatment system  14  includes an engine exhaust pipe  18  delivering the exhaust stream  16  to an aftertreatment device  20 . The aftertreatment device  20  includes a center canister  22 , inlet canister  24 , and an outlet canister  26 . The center canister  22  houses an exhaust filter  28 . The inlet canister  24  is upstream of the exhaust filter  28 . The outlet canister  26  is downstream of the exhaust filter  28  and may be adjacent to an outlet of the exhaust filter  28 . 
         [0019]    In one embodiment, where the engine  12  is diesel, the exhaust filter  28  may be a diesel particulate filter (DPF). The exhaust filter  28  is configured to collect particulate matter, soot, ash, or other constituents from the exhaust stream  16 . The filtering is often achieved by forcing the exhaust stream  16  to pass through the walls of the exhaust filter  28 , leaving the particulate matter behind. 
         [0020]    Most exhaust filters  28  are constructed from ceramics such as cordierite, but could also be made from silicone carbide (SiC), metallic fibers, or other materials. The exhaust filters  28  also often have complex honeycomb or other shapes and may have thin walls. Because of the materials and geometries involved, exhaust filters  28  may be susceptible to cracking and damage. 
         [0021]    The center canister  22  may also house a diesel oxidation catalyst (DOC)  30 . The DOC  30  and exhaust filter  28  may be in the same canister, as shown, or separate. The DOC  30  is configured to oxidize Carbon Monoxide (CO) and unburnt hydrocarbons (HC) into Carbon Dioxide (CO2). The aftertreatment system  14  may also include a Selective Catalytic Reduction (SCR) system configured to reduce an amount of NOx in the exhaust stream  16  in the presence of a reductant. The aftertreatment system  14  may also include a Lean Nox Traps (LNTs) system configured to reduce an amount of NOx in the exhaust stream  16 . The aftertreatment system  14  may also include an Ammonia Oxidation Catalyst (AMOX) system configured to reduce an amount of ammonia in the exhaust stream  16 . 
         [0022]    The aftertreatment system  14  may also include a heat source  32  to remove the soot from or regenerate the exhaust filter  28  or thermally manage the components of the aftertreatment system  14 . The heat source  32  may embody a burner, hydrocarbon dosing system to create an exothermic reaction on the DOC  30 , electric heating element, microwave device, or other heat source. The heat source  32  may also embody operating the engine  12  under conditions to generate elevated exhaust stream  16  temperatures. The heat source  32  may also embody a backpressure valve or another controllable restriction in the exhaust to cause elevated exhaust stream  16  temperatures. 
         [0023]    The aftertreatment system  14  may include an exit pipe  34  connected to the outlet canister  26 , delivering the exhaust stream  16  out of the aftertreatment device  20  to an exhaust stack or exhaust pipe  36 . The outlet canister  26  may include a drain plug  38  installed in a drain plug port  40 . The drain plug  38  may be used to remove water that has condensed or liquid that has otherwise collected in the aftertreatment device  20 . 
         [0024]    In the illustrated embodiment, the exhaust stream  16  exits the engine  12 , passes by or through the heat source  32 , passes through the aftertreatment device  20  (including the exhaust filter  28 ), then through the exit pipe  34  and out the exhaust pipe  36 . 
         [0025]      FIG. 2  shows the machine  1  in a test mode  5  and equipped with a test kit  100 . The test kit  100  includes a collector  102  and a restrictor  104 . The collector  102  is fluidly connected to the aftertreatment system  14  downstream of the exhaust filter  28 . In the currently illustrated embodiment, the collector  102  is installed in the drain plug port  40  but could be in another port or anywhere else downstream of the exhaust filter  28 . 
         [0026]    The restrictor  104  is installed to create backpressure in the aftertreatment system  14  by restricting flow of the exhaust stream  16  downstream of the exhaust filter  28  and downstream of the collector  102 . In the currently illustrated embodiment, the restrictor  104  is installed on the end of the exit pipe  34 . 
         [0027]    The collector  102  enables a test stream  106  of exhaust to be diverted or divided from the main exhaust stream  16 . The test stream  106  passes through the collector  102  and may be small in comparison to the main exhaust stream  16 . The backpressure created by the restrictor  104  assists in the creating of the test stream  106 . Therefore, the restrictor  104  may be downstream from where the test stream  106  is diverted. The engine  12  speed may also be increased to a level that will provide the flow and backpressure needed to drive the amount of test stream  106  needed. 
         [0028]    The collector  102  includes an indicator  108  and a housing  110 . The test stream  106  passes through or past the indicator  108 . The appearance, color, or shading of the indicator  108  in turn changes in response to the content of the test stream  106 . 
         [0029]    The housing  110  connects the collector  102  to the aftertreatment system  14 , houses the indicator  108 , and defines a flow path for the test stream  106  to pass through. 
         [0030]    The restrictor  104  may include an orifice plate  112  and a connector  114 . The orifice plate  112  effectively reduces the diameter or size of the conduit that the exhaust stream  16  passes through, creating the backpressure. The connector  114  connects the restrictor  104  to the aftertreatment system  14  and may embody a clamp or another securing method. 
         [0031]      FIGS. 3 and 4  show alternative embodiments of the test kit  100 , involving alternative ways of directing the directing the test stream  106  through the collector  102  via suction. These alternative embodiments may replace the restrictor  104  or may be used in addition to the restrictor  104 . 
         [0032]      FIG. 3  shows the test kit  100  may include a venturi system  160  to pull the test stream  106  through the collector  102 . The venturi system  160  includes a venturi pipe  162  and a suction hose  164 . The venturi pipe  162  includes an inlet end  166 , an outlet end  167 , and a neck down section  168  there between. The neck down section  168  necks down to have a smaller cross-sectional area compared to the inlet end  166  and outlet end  167 , and the venturi pipe  162  may be connected to the exit pipe  34  with connector  114 . 
         [0033]    The venturi pipe  162  may only be installed while the machine  1  is in test mode  5 . The venturi pipe  162  may also be attached to the end of exhaust pipe  36  or elsewhere downstream of the exhaust filter  28 . The venturi pipe  162  could also be equipped permanently on the machine  1 , during both operation and test mode  3 ,  5 . 
         [0034]    The suction hose  164  is fluidly connected at one end to the outlet of the collector  102  downstream of the indicator  108 . The other end of the suction hose  164  is fluidly connected to the neck down section  168  of the venturi pipe  162 . As the exhaust stream  16  passes through the neck down section  168 , the exhaust stream  16  speeds up, causing a low pressure region. This low pressure region will pull the test stream  106  through the collector  102 , through the suction hose  164 , and into the venturi pipe  162 . 
         [0035]      FIG. 4  shows the test kit  100  may include a pump system  170  to pull the test stream  106  through the collector  102 . The pump system  170  includes a pump  172  and a suction hose  174 . The pump  172  includes an inlet manifold  175  and an outlet  176 . 
         [0036]    The suction hose  174  is fluidly connected at one end to the outlet of the collector  102  downstream of the indicator  108 . The other end of the suction hose  174  is fluidly connected to the inlet manifold  175 . The pump  172  has a motor and a suction pump that draws the test stream  106  through the collector  102 , through the suction hose  174 , and into the pump  172  through the inlet manifold  175 . 
         [0037]    Cooler ambient or fresh air  177  may also be drawn into the pump  172  through the inlet manifold  175  to mix with the test stream  106 . This mixture  178  is the drawn through the pump  172  and passes out the outlet  176 . The mixture  178  of fresh air  177  and the test stream  106  will be cooler than the test stream  106  alone, which may be needed if components of the pump  172  are not be able to withstand the high temperatures of the test stream  106 . 
         [0038]    The pump  172  may be electrically driven or powered by an operator or another source. The pump  172  may programmed to run for the desired test time or the ECM or another controller could power and control the pump  172  for the desired test time. 
         [0039]    The indicator  108  may be a thin filter material, paper, or another media that the test stream  106  passes through and changes color or shading as a result of being exposed to particulate matter. In other embodiments, the test stream  106  may impact or pass over the indicator  108 . In some embodiments the indicator  108  may be electrostatic tubing that becomes discolored when exposed to the test stream  106 . The indicator  108  may be easily replaced and may require a new indicator  108  for each test. 
         [0040]    One embodiment of the collector  102  is shown in more detail in  FIGS. 5 and 6 . The housing  110  is shown to include an upstream end  116 , downstream end  118 , and a retaining collar  120 . The upstream end  116  includes an upstream threaded portion  122 , an upstream nut  124 , an upstream flange  126 , and an upstream passage  128 . The upstream threaded portion  122  threads into the drain plug port  40 , or otherwise connects to the aftertreatment system  14 . 
         [0041]    The downstream end  118  includes a downstream threaded portion  130 , a downstream flange  132 , and a downstream passage  134 . The retaining collar  120  includes a retaining ledge  136 , an inner threaded portion  138 , and a collar nut  140 . The indicator  108  is trapped between the upstream flange  126  and the downstream flange  132 . The inner threaded portion  138  of the retaining collar  120  connects the retaining collar  120  to the downstream end  118 . The retaining ledge  136  traps the upstream end  116  between the retaining collar  120  and downstream end  118 . The upstream passage  128  and downstream passage  134  are aligned to form the flow path for the test stream  106 . 
         [0042]    The test stream  106  enters through the upstream passage  128 , passes through the indicator  108 , and exits the collector  102  through the downstream passage  134 . As seen in  FIG. 7 , the indicator  108  includes an exposed portion  142  where the indicator  108  is exposed to the test stream  106 . Particulate matter in the test stream  106  causes a discoloration  144  in the exposed portion  142 . This discoloration  144  may be a degree of shading from white to black or light to dark. 
         [0043]      FIG. 7  also shows a grading sheet  146  that includes test samples  148 . The test samples  148  correspond to levels of discolorations from light to dark.  FIG. 7  shows five levels, but more or fewer may be used. The indicator  108  is assigned a level by comparing the discoloration  144  with the test samples  148 . The test samples  148  may include an opening  150  so that the indicator  108  can be placed under the grading sheet  146  and the discoloration  144  can be visually compared side-by-side to the test samples  148 .  FIG. 7  illustrates graduating degrees of discoloration from light to dark using lines and shading. 
         [0044]      FIG. 8  shows a meter  180  that may be used as a digital alternative to the grading sheet  146 . The meter  180  is a device capable of measuring the reflectance of light or light transmittance or another aspect of the discoloration  144 . The meter  180  may also be able to quantify the discoloration with a digital reading  182 . The reading  182  could then be assigned to a level using a scale of readings with ranges corresponding to different levels. 
         [0045]    The meter  180  may be portable or a desktop unit and may be battery or hard wired. One example of a device that may be suited for or adapted for use as meter  180  is window tint meters. These window tint meters are used to measure the darkness of window tint by measuring the percentage of light transmitted through the window glass. 
       INDUSTRIAL APPLICABILITY 
       [0046]      FIG. 9  illustrates a test method  200  using the test kit  100 . First, in step  202  the exhaust filter  28  is regenerated by removing collected particulate matter. This regeneration may be achieved by manually forcing the power system  10  to enter into a regeneration cycle, activation the heat source  32 , or applying an external heat source to the exhaust filter  28 . This regeneration may require the engine  12  to be ran at a desired speed, such as high idle. 
         [0047]    In other embodiments, the test method  200  may not require a regeneration of the exhaust filter  28  beforehand. Once a soot cake has been deposited inside the exhaust filter  28  filter efficiency may not significantly change with changing levels of soot. Therefore, the amount of soot may not have to be considered and the regeneration may not be necessary to the test method  200 . 
         [0048]    Next, in step  204 , the exhaust pipe  36  is removed. An operator may need to wait for the power system  10  to cool down after step  202  before removing the exhaust pipe  36 . In step  206  the restrictor  104  is installed on to the end of the exit pipe  34 . Steps  204  and  206  may be adapted as needed to accommodate the alternative embodiments of the test kit  100  shown in  FIGS. 3 and 4 . 
         [0049]    In step  208  the engine  12  is ran at high idle or at a predetermined engine test speed for long enough to stabilize the exhaust temperatures, which may take a minimum of 10 minutes. In step  210  the collector  102  is installed. The installation of the collector may be done after shutting the engine  12  off, but should be done quickly enough so that temperatures do not drop significantly. 
         [0050]    Next, in step  212  the test is conducted. During the test, the engine is run for a predetermined test time at the predetermined engine test speed. Regeneration of the exhaust filter  28  may be disabled during the test. In one embodiment, the test time may be 20 minutes and the engine test speed may correspond to high idle, but many other test times and engine test speeds could be used so long as the grading sheet  146  was recalibrated accordingly. The test time and engine test speed may be selected to achieve the desired amount and rate of flow through the collector  102 . The predetermined engine test speed may be constant or varied over the test time in a controlled manner. After the predetermined test time, the collector  102  is removed or the engine  12  is shut down after the test time has elapsed. An operator may need to wait for the aftertreatment system  14  to cool after the engine  12  is shut down before removing the collector  102 . 
         [0051]    Performance of the preceding steps of the test method  200  may be assisted or aided by a test routine in the engine&#39;s  12  electronic control module (ECM). This test routine would control the engine&#39;s  12  operation according to the parameters required by the test method  200  and may reduce the chances of error by an operator or technician. 
         [0052]    In step  214  the indicator  108  is removed from the collector  102  and the discoloration  144  is compared to the grading sheet  146 . The collector  102  may have to be disassembled to remove the indicator  108 . Next, in step  216  an exhaust filter quality level is assigned based on the comparison from step  214 . Steps  214  and  216  may be adapted to account for use the alternate meter  180  for assigning the exhaust filter quality level. 
         [0053]    Based on this quality level, a decision can be made regarding further actions. For instance, if the discoloration  144  is too much and assigned level too high, the exhaust filter  28  may be replaced. The order of some of the steps described above may be rearranged while still achieving the desired result. 
         [0054]    The exhaust filter  28  quality level may relate to a degree of cracking that has occurred in the exhaust filter  28  during operation. This cracking may be a result of stress and weakening of the material from excessive temperature spikes, fast temperature swings causing thermal shocks, vibration causing cyclical failures, or large mechanical impacts. The exhaust filter  28  quality may also relate to other degradations to the exhaust filter  28  that would allow particulate matter to pass through the exhaust filter  28  in higher than anticipated amounts. 
         [0055]    When the exhaust filter  28  is cracked, particulate matter passes through without being collected in the anticipated amounts. The test method  200  described above detects this excess particulate matter based on the amount of discoloration  144  on the indicator  108 . The more particulate matter that makes it past the exhaust filter  28 , the more particulate matter that will be in the test stream  106 , and the more particulate matter that will be deposited on the exposed portion  142  of the indicator  108 , and the darker the shading or discoloration  144  will be. 
         [0056]    The test kit  100  and test method  200  described above allow the exhaust filter  28  to be tested while still installed on the machine  1 . Other tests require the exhaust filter  28  to be removed and often sent away for evaluation, which is time consuming and expensive. The test method  200  is also quick and easy for an operator to perform. The backpressure created by the restrictor  104  helps achieve results in a reduced amount of time. The predetermined test times and engine test speeds may help provide accurate, comparable, and repeatable results in the field. 
         [0057]    The test kit  100  is also inexpensive. The test kit  100  may require no electronics or moving parts. In contrast, other sensors used for these types of tests can be expensive, making them impractical for widespread use. Because of the small test stream  106  of exhaust, the collector  102  may be smaller in size than would otherwise be needed. Because the drain plug port  40  may be used to install the collector  102 , modifications to the machine  1  are minimal to conduct the test. Despite the quick test time and inexpensive hardware, the test method  200  provides a quantifiable indication of the exhaust filter  28  quality or effectiveness. Because of these features, the test kit  100  and test method  200  may be particularly suited for mobile machines  1 , which may require inexpensive hardware, on-machine testing, and fast test times as a large number of field tests may be required. 
         [0058]    Although the embodiments of this disclosure as described herein may be incorporated without departing from the scope of the following claims, it will be apparent to those skilled in the art that various modifications and variations can be made. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.