Patent Application
20070289293
An exhaust system 34 receives exhaust gases 36 from the diesel engine 24, treats the exhaust gases 36, and directs them into the atmosphere away from the vehicle 20. More specifically, an exhaust pipe 42 connects at an upstream end to conventional exhaust system hardware (not shown), such as, for example, a turbocharger (not shown), that receives exhaust from exhaust manifolds (not shown) on the engine 24. The exhaust pipe 42 directs the exhaust gases 36 into a diesel oxidation converter 44 (also known as a diesel oxidation catalyst). The diesel oxidation converter 26 treats the exhaust gases 36 in order to reduce the amounts of certain constituents that will be emitted into the atmosphere. Such constituents may be, for example, carbon monoxide (CO) and unburned hydrocarbons (HC). The vehicle and its components discussed above are known to those skilled in the art and so will not be discussed or shown in more detail herein.
A first intermediate pipe 38 connects to the downstream end of the diesel oxidation converter 44 and directs the exhaust gases 36 into a diesel particulate filter 50 (also called a diesel particulate trap). The diesel particulate filter 50 is basically a filter for collecting (i.e., trapping) soot (also called diesel particulate matter) from the exhaust in order to minimize the amount of soot in the exhaust gases 36. Downstream of the diesel particulate filter 50 is a second intermediate pipe 40. The second intermediate pipe 40 directs the exhaust gases 36 into a muffler 46. The muffler directs the exhaust flow into a tailpipe 48, which extends to an open downstream end where the exhaust gases 36 are emitted into the atmosphere away from the vehicle 20.
The exhaust system 34 may also include an upstream pressure sensor 80, which is mounted just prior to exhaust gas entry into the diesel particulate filter 50 in order to measure the pressure in the exhaust gas stream just prior to entry into the filter 50. A downstream pressure sensor 82 may be mounted in the exhaust system 34 just after the exhaust exit from the diesel particulate filter 50 in order to measure the pressure in the exhaust gas stream after exit from the filter 50. Both the upstream and downstream pressure sensors 80, 82 are in communication with the controller 32. The controller 32 may also be in communication with various components of the diesel engine 24 and transmission 26, as is known to those skilled in the art. The controller 32 may also be connected to an indicator light 33 mounted, for example, on an instrument panel (not shown).
The diesel particulate filter 50 will now be discussed in more detail with reference to
The diesel particulate filter 50 includes a first mounting flange 74 on an upstream end and a second mounting flange 76 on a downstream end. Both of the mounting flanges 74, 76 can be attached to either of the first and second intermediate pipes 38, 40. These flanges 74, 76 are also preferably of the type that allow for removal and reinstallation of the diesel particulate filter 50. The mounting flanges 74, 76 may be, for example, a V-bend type of flange. This is just one example, since there are many types of mounting flanges 74, 76 that can be employed to allow for removal, reversal and reinstallation of the diesel particulate filter 50. Moreover, the term mounting flange as used herein is to be interpreted broadly to include many known exhaust pipe joints that can be used to mount the diesel particulate filter 50.
A comparison is made between the soot buildup parameter(s) and predetermined threshold(s) to determine if soot regeneration is required, step 104. If not, then a comparison is made between the ash buildup parameter(s) and predetermined threshold(s) to determine if action needs to be taken due to ash buildup, step 108. If not, then the monitoring continues.
At some point, a determination is made (step 104) that the soot needs to be burned off (i.e., the filter regenerated) in order to avoid clogging the diesel particulate filter 50. The determination of when the regeneration mode will be initiated can be based on one or more of several factors (parameters). For example, the controller 32 may keep track of engine run time, vehicle mileage or fuel consumption since the last regeneration process occurred, and initiate the regeneration process after a predetermined amount of engine run time, vehicle mileage or fuel consumption, as the case may be. For another example, the controller 32 may determine the pressure drop across the particulate filter 50 by calculating the difference in measured pressure between the upstream pressure sensor 80 and the downstream pressure sensor 82, with the regeneration process initiated when a predetermined pressure difference across the particulate filter 50 is reached. Or, the controller 32 may employ a soot regeneration algorithm that estimates an amount of soot buildup based upon some combination of two or more of the previous listed factors, or other factors.
When the determination is made that regeneration of the particulate filter 50 is needed, the controller 32 begins the regeneration process, step 106. The controller 32 will cause the regeneration process to occur by various known means. The particular actions taken by the controller 32 may depend upon the engine and vehicle operating conditions as well as the ambient conditions. The temperature of the diesel particulate filter 50 is raised sufficiently to cause soot to burn off. The controller 32 continues with the process until the desired amount of regeneration is achieved. This may be based, for example, on a predetermined pressure drop across the particulate filter 50 being achieved, a predetermined length of regeneration time, or a soot regeneration algorithm that estimates the amount of soot burn-off achieved.
At some point, a determination is made (step 108) that the ash buildup is sufficient that action needs to be taken. One will note that it is contemplated that the regeneration for soot occurs far more frequently than any action needed to account for ash buildup. For example, soot regeneration may happen as often as every fuel tank fill, while action take for ash buildup may not be required until around 200,000 kilometers of vehicle travel. The determination that action is required for ash buildup may be based on, for example, measuring the pressure drop across the diesel particulate filter 50—in particular if the pressure drop is above a predetermined threshold even after soot regeneration. Examples of other possible determining factors may be reaching a certain mileage with the diesel particulate filter in the same orientation, or an increase in fuel consumption by the diesel engine 24. Or, a combination of two or more of these factors, or others, may be employed to make this determination. The particular factors and thresholds used may depend upon the particular vehicle, engine and exhaust system to which this method is applied.
If the ash buildup requires action, then an indication is provided that diesel particulate filter reversal or replacement is needed, step 110. This indication may be, for example, the light 33 that illuminates on an instrument panel (not shown), or a wireless data transmission to a computer network (not shown) that will email an operator of this need. Of course, other types of indicators that will notify a vehicle operator of the need to take action for ash buildup can also be employed instead, if so desired.
With the wall-flow honeycomb structure of the brick 62 in the filter 50, the ash that builds up will tend to build up near the upstream end 64 of the brick 62. Thus, turning the entire filter 50 (or just the brick 62) around will locate the part of the brick 62 with the most ash buildup (the end that was originally upstream) on the downstream end facing the outlet channel 70. This will allow the built-up ash to be blown out in the exhaust stream 36 as it passes from the brick 62 into the outlet channel 70. As noted above, the first and second mounting flanges 74, 76 can each connect to either the first intermediate pipe 38 or the second intermediate pipe 40, and allow for removal and reinstallation of the diesel particulate filter 50.
Accordingly, a determination is made as to whether reversal is desirable, step 112. If it is not desirable to reverse the filter 50, then the diesel particulate filter 50 is replaced, step 116. If it is desirable to reverse the filer 50, then it is removed from the exhaust system 34, reversed (i.e., rotated 180 degrees from its original orientation), and then reinstalled in the exhaust system 34, step 114. The controller 32 can then be reset and the process starts over again.
Reasons to replace instead of reverse the filter 50 may be, for example, that it has already been reversed previously at least once and, for this particular vehicle, engine and filter combination, it is not desirable to reverse it an additional time. Another reason may be that, for example, this particular filter 50 is clogged, rather than just fully loaded with ash. A fully-loaded filter 50 signifies that it is time to take some action relative to the ash buildup—the engine and exhaust system will still function though somewhat less efficiently. Clogged signifies that the filter 50 is no longer functioning—the engine and exhaust system will run very poorly or maybe not at all for this condition. Of course, where possible, the filter 50 is preferably reversed since this will generally cost significantly less than replacement.
The parameter(s) for ash buildup are monitored, step 202. A comparison is made between the ash buildup parameter(s) and predetermined threshold(s) to determine if action needs to be taken due to ash buildup, step 208. If not, then the monitoring continues. If the ash buildup requires action, then an indication is provided that diesel particulate filter reversal or replacement is needed, step 210. A determination is made as to whether reversal is desirable, step 212. If it is not desirable to reverse the filter 50, then the diesel particulate filter 50 is replaced, step 216. If it is desirable to reverse the filer 50, then it is removed from the exhaust system 34, reversed (i.e., rotated 180 degrees from its original orientation), and then reinstalled in the exhaust system 34, step 214.
For the processes described above, there may be alternative ways to accomplish some of the steps. For example, this process comprehends the technique of servicing a diesel particulate filter 50 that is loaded with ash by reversing it, but reinstalling it on another vehicle. As another alternative, this process can include ash removal before reinstallation. As yet another alternative, this process can include the diesel particulate filter 50 being removed, the housing 52 being opened, the brick 62 removed and reinstalled in the housing 52 in the reverse direction, and then reinstalling the housing 52 in the exhaust system 34 in the same direction. Or, as a further alternative, the housing 52 may remain attached to the exhaust system 34 while being opened, the brick 62 removed, reversed and reinserted, and the housing 52 closed again.
While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.
