Abstract:
A system for preventing the cleaning of the diesel particulate filter ( 116 ) comprises an electronic control unit ( 200 ) coupled to a proximity sensor ( 122 ), the electronic control unit ( 200 ) being configured to monitor the proximity sensor ( 122 ) and to determine that there is a predetermined distance between the proximity sensor and an adjacent structure ( 124 ) before the electronic control unit ( 200 ) will regenerate the diesel particulate filter ( 116 ). A method for preventing the cleaning of the diesel particulate filter ( 116 ) comprises the steps of electronically monitoring a proximity sensor to determine a distance from the proximity sensor to an adjacent structure, electronically comparing the distance to a threshold distance, and electronically preventing the cleaning of the diesel particulate filter ( 116 ) when the distances less than the threshold distance.

Description:
FIELD 
       [0001]    The invention relates to diesel particulate filters. More particularly, it relates to systems for preventing the cleaning of a diesel particulate filter. 
       BACKGROUND 
       [0002]    Diesel particulate filters are provided on diesel engines to reduce the emissions of the engines. The diesel particulate filters filter out soot from the exhaust gas exiting the engine. 
         [0003]    Over time, particulate matter (often called “soot”) builds up inside the diesel particulate filters. It must be periodically removed or the diesel particulate filter will be plugged. In order to remove the sort, the diesel particulate filter is operated at an elevated temperature high enough to combust the soot. This cleaning process is commonly called “regeneration”. 
         [0004]    There are a variety of methods for regenerating or cleaning a diesel particulate filter, the most common being injecting fuel into a flow of exhaust gas leading into the diesel particulate filter then using a catalytic converter to oxidize the fuel and heat the exhaust gas, or combusting fuel and adding the hot combustion byproducts to the flow of exhaust gas. 
         [0005]    During normal engine operation the exhaust gas may leave the vehicle at a relatively low temperature, such as 120° F. 
         [0006]    During regeneration, however, the exhaust gas may be raised to a temperature from 600-1200° F. in order to completely combust the soot in the diesel particulate filter. 
         [0007]    There is a risk that the elevated exhaust gas temperature may cause structures adjacent to the exhaust outlet of the vehicle to be damaged. 
         [0008]    What is needed, therefore is a system for preventing the cleaning of a diesel particulate filter of a vehicle when the vehicle is too close to another structure. 
         [0009]    It is an object of this invention to provide such a system. 
       SUMMARY 
       [0010]    In accordance with one arrangement, a vehicle comprises ground engaging structures for moving the vehicle over the ground, a frame coupled to the ground engaging structures, a diesel engine further comprising a diesel particulate filter, wherein the diesel engine is mounted on the frame, an exhaust pipe coupled to and extending from the diesel engine, the exhaust pipe having an outlet configured to released a stream of exhaust gas from the engine into the environment, an electronic control unit (ECU) coupled to the engine to control the regeneration of the diesel particulate filter, and a proximity sensor coupled to the ECU to indicate a distance between the vehicle and an adjacent structure, wherein the ECU is configured to prevent the regeneration of the diesel particulate filter when the proximity sensor indicates the vehicle is within a predetermined range of the adjacent structure. 
         [0011]    In accordance with another arrangement, a system for preventing the cleaning of a diesel particulate filter comprises an electronic control unit; a proximity sensor; a fuel injector coupled to the electronic control unit and coupled to an exhaust gas conduit upstream of the diesel particulate filter; wherein the electronic control unit is configured to read the proximity sensor and to prevent the fuel injector from adding fuel to the exhaust gas conduit until the proximity sensor indicates at least a threshold distance to an adjacent structure. 
         [0012]    The electronic control unit may comprise a digital microprocessor. 
         [0013]    The fuel injector may be configured to inject fuel into a flow of exhaust gas upstream of the diesel particulate filter. 
         [0014]    The proximity sensor may comprise an ultrasonic sensor. 
         [0015]    The electronic control unit may be configured to stop an ongoing diesel particulate filter cleaning process. 
         [0016]    The electronic control unit may be configured to stop the ongoing diesel particulate filter cleaning process by stopping the fuel injector from adding further fuel to the exhaust gas conduit. 
         [0017]    In accordance with another arrangement, an agricultural harvester ( 100  may comprise a self-propelled agricultural harvesting vehicle further comprising a frame, a diesel engine supported on the frame and the system described herein for preventing the cleaning of the diesel particulate filter. 
         [0018]    The proximity sensor may be disposed adjacent to an exhaust pipe disposed to carry exhaust gas from the diesel engine away from the agricultural harvester. 
         [0019]    The proximity sensor may comprise an ultrasonic sensor. 
         [0020]    The proximity sensor may be disposed at a rear of the agricultural harvester. 
         [0021]    In accordance with another arrangement, a method for preventing the cleaning of a diesel particulate filter on an agricultural vehicle having a proximity sensor comprises electronically monitoring the proximity sensor to determine a distance from the proximity sensor to an adjacent structure; electronically comparing the distance to a threshold distance; electronically preventing the cleaning of the diesel particulate filter when the distance is less than the threshold distance. 
         [0022]    The step of electronically preventing the cleaning of the diesel particulate filter ( 116  when the distance is less than the threshold distance may comprise the step of preventing a fuel injector from injecting fuel into a flow of exhaust gas into the diesel particulate filter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]      FIG. 1  shows an agricultural combine having an engine, a diesel particulate filter, and an exhaust gas outlet. 
           [0024]      FIG. 2  is a schematic diagram of the system to control the regeneration of the diesel particulate filter. 
           [0025]      FIG. 3  is a flowchart showing the steps performed by the ECU of the system to prevent the cleaning of the diesel particulate filter. 
           [0026]      FIG. 4  is a flowchart showing the steps performed by the ECU of the system to terminate the cleaning of the diesel particulate filter. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    In the discussion below, the terms “front”, “forward”, “in front of”, and variants thereof refer to the forward direction of travel of the vehicle as it travels through the field harvesting crops. This direction of travel as indicated by the letter “V” in  FIG. 1 . 
         [0028]    In the discussion below, the terms “rear”, “rearward”, “behind”, and variants thereof refer to a direction opposite to the forward direction of travel. 
         [0029]    “Upstream” and “downstream” as those terms are used herein relate to the flow of exhaust gas from the cylinders of the diesel engine  112 . 
         [0030]    Referring now to  FIG. 1 , an agricultural harvester  100  is shown. The agricultural harvester comprises a harvesting head  102  which is mounted on a feederhouse  104  that is supported on the front of a self-propelled agricultural harvesting vehicle  106 . 
         [0031]    The self-propelled agricultural harvesting vehicle  106  is supported on a plurality of wheels  108  that engage the ground and support the agricultural harvester  100  for travel over the ground harvesting crops. The wheels are connected to a frame  110  of the self-propelled agricultural harvesting vehicle  106 . The agricultural harvester  100  travels through the field in the direction “V” as it harvests crop. 
         [0032]    A diesel engine  112  is fixed to the frame  110  and is disposed in an upper rear portion of the self-propelled agricultural harvesting vehicle  106 . 
         [0033]    A diesel particulate filter  116  is disposed to receive gaseous diesel engine combustion byproducts (“engine exhaust” or “exhaust gas”) that exit the diesel engine  112 . The exhaust gas leaving the diesel particulate filter  116  travels through an exhaust pipe  118  and through an aperture  120  in the self-propelled agricultural harvesting vehicle. The outlet of the exhaust pipe  118  extends from the rear of the self-propelled agricultural harvesting vehicle  106  and conveys the exhaust gas away from the agricultural harvester  100 . 
         [0034]    The diesel particulate filter  116  may comprise a catalytic converter (such as a diesel oxidizer catalyst or “DOC”) that is disposed upstream of the diesel particulate filter element in order to oxidize raw fuel in the flow of exhaust gas from the engine to the filter element of the diesel particulate filter  116 . For diesel particulate filters with a catalytic converter, the un-combusted fuel in the exhaust gas flow is oxidized in the catalytic converter with the concomitant release of heat energy, and elevation of the exhaust gas temperature. 
         [0035]    A proximity sensor  122  is disposed adjacent to the exhaust pipe of the diesel engine  112  which (in this case) is at the rear of the self-propelled agricultural harvesting vehicle  106  to sense the proximity of the self-propelled agricultural harvesting vehicle  106  to any adjacent structure  124 . A typical adjacent structure  124  (such as that shown here) is a barn, a shed, hay bales or crop storage bins. 
         [0036]    The proximity sensor  122  may comprise one or more ultrasonic sensor transmitters and receivers. These ultrasonic transmitters and receivers may be pointed in a variety of directions such that they sense the proximity of the self-propelled agricultural harvesting vehicle  106  to a plurality of locations on the adjacent structure  124 . 
         [0037]    In  FIG. 2 , an electronic control unit (ECU)  200  includes a microprocessor  202 , a clock circuit  203 , a RAM or random-access memory  204 , a ROM or read-only memory  206 , and a driver circuit  208 . The microprocessor  202  is configured to execute a series of digital program statements that are stored in read-only memory  206 . The microprocessor  202  is configured to save working values in random-access memory  204  that it calculates as it executes the series of digital program statements. 
         [0038]    In one arrangement, the ECU  200  of  FIG. 2  represents a single ECU. In another arrangement, the ECU  200  of  FIG. 2  represents a plurality of ECUs that are networked together, each of the ECUs in the network providing some of the functions described herein and communicating the results of those functions to others ECUs of the network of ECUs. 
         [0039]    The ECU  200  is coupled to a fuel injector  210 . The fuel injector  210  is disposed to inject fuel into a flow of exhaust gas carried leaving the cylinders of the diesel engine  112  and going to the diesel particulate filter  116 . 
         [0040]    In one arrangement, the fuel injector  210  is disposed to inject fuel into the exhaust gas in the diesel engine  112  itself. 
         [0041]    In another arrangement the fuel injector  210  is disposed to inject fuel into an exhaust gas conduit  214  connecting the diesel engine  112  to the diesel particulate filter  116 . 
         [0042]    In another arrangement, the fuel injector  210  is disposed to inject fuel into the diesel particulate filter  116  either at, or slightly upstream of the working element of the diesel particulate filter  116 . 
         [0043]    All of these arrangements are expressed schematically in  FIG. 2  which shows the fuel injector  210  located between the engine and the DPF. In all of these aforementioned arrangements, the fuel is introduced at a location such that its combustion byproducts can be combined with the existing exhaust gas to elevate the temperature of the combined exhaust gas flow prior to the exhaust gas passing through the diesel particulate filter  116 . 
         [0044]    These different locations are expressed schematically in  FIG. 2  by the fuel injector  210  coupled to the exhaust gas conduit  214 . In another arrangement, the fuel injector  210  comprises a means for combusting the fuel such as a burner, combustor, or oxidizer. 
         [0045]    The ECU  200  is coupled to a pressure sensor  215  that is disposed to sense an exhaust gas pressure drop across at least a portion of the filter element of the diesel particulate filter  116 . 
         [0046]    In  FIG. 3  a flowchart of the process followed by the ECU  200  is shown. This process is defined by a sequence of digital computer instructions stored in the read-only memory  206 . 
         [0047]    In step  300 , the process starts. 
         [0048]    In step  302  the ECU  200  is programmed to read the clock circuit  203  to determine how long the engine has been operating since the last time the diesel particulate filter  116  has been thermally recycled and thus how long soot has been accumulating in the diesel particulate filter  116 . 
         [0049]    In step  304 , the ECU is programmed to read the pressure sensor  215  to determine the degree to which soot has obstructed the diesel particulate filter  116 . The pressure drop across the diesel particulate filter  116  is proportional to the amount of soot contamination of the diesel particulate filter  116 . 
         [0050]    In step  306 , the ECU is programmed to compare the elapsed engine operating time (which the ECU determined in step  302 ) and the degree to which the diesel particulate filter  116  is obstructed (which the ECU determined in step  304  by determining the pressure difference across the diesel particulate filter  116 ) against threshold values of elapsed engine operating time and pressure drop across the diesel particulate filter  116 . 
         [0051]    If the ECU  200  in step  306  determines that neither the elapsed engine operating time (step  302 ) nor the pressure drop across the diesel particulate filter  116  (step  304 ) have reached a predetermined threshold, the ECU  200  the process continues to step  307  and terminates. 
         [0052]    If the ECU  200  in step  306  determines that either the elapsed engine operating time (step  302 ) or the pressure drop across the diesel particulate filter  116  (step  304 ) has reached a predetermined threshold, the ECU  200  branches to step  308 , and reads the proximity sensor  122 . 
         [0053]    After the ECU  200  executes step  308 , it then continues to step  310  in which it compares the distance indicated by the proximity sensor  122  with a threshold distance previously stored in ROM  306 . The threshold distance previously stored in ROM  306  indicates a minimum distance between the agricultural harvester  100  and the adjacent structure  124  within which the ECU  200  will not permit the diesel particulate filter  116  to be thermally recycled. 
         [0054]    If the ECU  200  determines in step  310  that the adjacent structure  124  is too close to the agricultural harvester  100  (i.e. the signal generated by the proximity sensor indicates a distance that is smaller than the threshold distance), the ECU  200  continues to step  307  and terminates. 
         [0055]    Alternatively, if the ECU  200  determines in step  310  that the adjacent structure  124  is sufficiently far from the agricultural harvester  100  (i.e. the signal generated by the proximity sensor indicates a distance that is greater than the threshold distance) then the ECU  200  continues to step  312 . 
         [0056]    In step  312 , the ECU  200  is programmed to command the fuel injector  210  to inject fuel into the exhaust gas produced in the engine before the exhaust gas reaches the diesel particulate filter  116 , at which point the ECU  200  continues to step  307  and terminates. 
         [0057]    The steps illustrated in  FIG. 3  are performed at regularly scheduled intervals by the ECU  200 . 
         [0058]      FIG. 4  illustrates a process performed by ECU  200  whenever the DPF is being cleaned. 
         [0059]    In step  400 , the process starts. 
         [0060]    In step  402 , the ECU  200  reads the proximity sensor  122 . 
         [0061]    In step  404 , the ECU  200  compares the distance indicated by the proximity sensor  122  with a second threshold distance previously stored in ROM  306 . The second threshold distance may be the same as or different from the threshold distance discussed above. 
         [0062]    If the agricultural harvester  100  is within the second threshold distance as determined in step  404 , the ECU  200  continues to step  406  and terminates the DPF cleaning process. In step  406 , the ECU  200  turns the fuel injector  210  off and thereby stops the fuel injector  210  from injecting fuel into the exhaust gas. 
         [0063]    If the agricultural harvester  100  is not within the second threshold distance, the ECU continues to step  408  and terminates the DPF cleaning process. 
         [0064]    ECU  200  is programmed to perform the steps illustrated in  FIG. 4  at regularly scheduled intervals during the DPF cleaning process, and thus to terminate an ongoing DPF cleaning process whenever the agricultural harvester  100  comes too close to the adjacent structure  124 . 
         [0065]    The description and figures herein are provided to illustrate at least one concrete example of how the invention can be practiced. The invention itself, however, is not limited to being practiced in the particular way always described herein. The claims (below) define the invention and encompass more than the specific examples provided herein.