Diesel particulate filter unit and regeneration control...

Details Diesel particulate filter unit and regeneration control... Diesel particulate filter unit and regeneration control...

2002-02-15

2003-09-23

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

C060S274000, C060S297000, C060S311000, C060S286000

Reexamination Certificate

active

06622480

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention concerns a continuous regeneration type diesel particulate filer unit for cleaning the exhaust gas by capturing particulate of a diesel engine and a regeneration control method of the same.
The restriction of discharge quantity of particulate (the PM: particulate: referred to as the PM hereinafter) discharged from the diesel engine is reinforced year by year together with NOx, CO and HC or the others. Therefore, a technique for reducing the quantity of the PM discharged outside, by capturing the PM by means of a filter called diesel particulate filer (DPF: Diesel Particulate Filter: referred to as DPF hereinafter) has been developed.
The DPF for capturing the PM includes monolith honeycomb form wall flow type filters made of ceramics, fiber filter type filters made of fiber shape ceramics or metal, or the others. The exhaust emission control device using these DPFs are installed in the middle of the engine exhaust pipe, similarly to the other exhaust emission control devices, for cleaning exhaust gas generated in the engine before discharging.
However, the filter of DPF unit for the PM capture is clogged gradually along with the capture of the PM and the exhaust pressure raises substantially in proportion to the quantity of captured the PM, thus requiring to remove the PM from the filer. Mainly three kinds of method and unit have been developed.
The first of them concerns a regeneration unit and method of the same for using two filters alternately to capture the PM in exhaust gas by one filter and regenerate by burning the captured the PM heating by the other filter through an electric heater or the like.
The second method and unit consists in using a solid filer as filter, disposing an oxidation catalyst upstream the solid filter, and treating the PM captured in the solid filter by a chemical reaction based on the oxidation catalyst.
The third method and unit consists in using a solid filter provided with catalyst and a catalyst additive agent for accelerating the burning of the PM.
Primary clogging factors of these DPF units include, in addition to smog or the like that are unburned components of the fuel and ash of burned lubricant oil.
The lubricant oil is supplied to different parts of an engine and the periphery of piston rings from a lubricant oil reservoir to circulate in the engine, and penetrates into the engine cylinder from the peripheries of piston rings and valves.
When the lubricant oil is exposed to a high temperature in the engine cylinder, calcium, zinc or other ingredients contained in the lubricant oil are not burned and remain as ash, and the ash is contained and borne by the exhaust gas and captured by the filter of a DPF unit.
Moreover, the ash captured by the filter is not burned and not removed by the filter regeneration operation or the others and accumulated in the filter even slightly. Lubricant oil leaks extremely slightly on the order of several tens of litter per ten thousand km of traveling; however, its total amount can not be neglected as the mileage increases. If the mileage attains the order of several ten thousand km or a hundred thousand km, the filter clogging due to the ash deposit and accumulation progresses, affecting the exhaust pressure before and after the filter.
On the other hand, in the DPF unit of the related art, the clogging of filter due to the PM is judged by comparing the exhaust pressure measured before and after the filter and a predetermined exhaust pressure judgment value, and it is so controlled to start the filter regeneration operation, when exhaust pressure, difference pressure, pressure ratio or the others calculated from the measured exhaust pressure exceeds the predetermined judgment value.
However, the PDF unit of the related art has a problem that the exhaust pressure raises gradually along with the increase of mileage, as the filter clogging due to ach generated from the lubricant oil is not considered, making the judgment to start the regeneration operation becomes gradually inappropriate.
Besides, the second and the third units are units for lowering the burning start temperature of the PM by the function of a catalyst such as &ggr; alumina, Pt, zeolite, or the like supported by the filter, and incinerating the PM by the exhaust gas, called “continuous regeneration type DPF”.
In case of the continuous regeneration type DPF, the temperature of exhaust gas flowing in the PDF may be increased to a temperature for activating the catalyst (par example, equal or superior to 250° C.).
The PM cleaning mechanism in the exhaust gas is different according to engine operation areas (torque and engine speed) (C
1
), (C
2
) as shown in FIG.
17
.
First, in the area (C
1
), carbon (C: the PM) is oxidized to carbon dioxide (CO
2
) through a reaction (4CeO
2
+C→2CeO
3
+CO
2
, 2CeO
3
+O
2
→4CeO
2
) by catalytic action of the a filter with catalyst
4
, while in the area (C
2
), carbon (C: the PM) is oxidized to carbon dioxide (CO
2
) through a reaction (C+O
2
→CO
2
).
Then, in the engine operation areas (torque and engine speed) (C
1
), (C
2
) as shown in
FIG. 17
, the PM in the exhaust gas G is cleaned continuously regenerating the filter with catalyst
4
, by cleaning the PM captured by the filter with catalyst
4
. It should be appreciated that though the division between these (C
1
) and (C
2
) is schematically shown in
FIG. 17
, there is not necessarily a clear boundary, but main reaction varies gradually.
However, for the continuous regeneration type DPF unit, in case where the exhaust gas temperature corresponding to the engine operation area (D) in
FIG. 17
is low, the catalyst temperature lowers deteriorating the catalyst activity, and therefore, the aforementioned action does not occur, and the filter can not be regenerated by oxidizing the PM. Consequently, the PM continues to accumulate, clogging the filter.
Especially, during idling or low load driving, and during engine brake operation on a downhill or the others, the fuel burns hardly, and a cool exhaust gas flows into the filter with catalyst, lowering the catalyst temperature and deteriorating the catalyst activity. Moreover, the PM deposits on the filter during the driving period of time where the filter can not be regenerated.
BRIEF SUMMARY OF THE INVENTION
The first object of the present invention is to provide a diesel particulate filer unit (DPF unit) allowing to judge appropriately the start timing of regeneration operation, by estimating the state of accumulation of ash generated from a lubricant oil and correcting or compensating the exhaust pressure judgment value concerning the exhaust pressure used for judging the regeneration start, with the ash accumulated estimation value, and to remove the PM efficiently, all the way preventing the filter from clogging.
The second object of the present invention to provide a DPF unit allowing to remove the PM efficiently all the way preventing securely the filter from clogging, by controlling the engine exhaust gas temperature, through surveillance of the accumulation state of the PM.
The DPF unit for achieving the first object is configured as follows.
1) A DPF unit comprising a filter for capturing particulates in the exhaust gas of a diesel engine, an exhaust pressure sensors disposed in an exhaust passage, and a regeneration control means for starting the regeneration operation of said filter, according to the judgment results based on the comparison between the exhaust pressure measured by the exhaust pressure sensors and a predetermined exhaust pressure judgment value, and regenerating said filter by removing particulates captured by said filter through combustion or chemical reaction by a catalyst, wherein said regeneration control means is configured to estimate the ash accumulated quantity of ash leaked into the exhaust gas and accumulated in said filer and to correct said exhaust pressure judgment value for judging the regeneration operation start based on said ash accumulated estimation value.
Concerning the DPF

Affiliated with

Also associated with

Rating

Diesel particulate filter unit and regeneration control... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Diesel particulate filter unit and regeneration control..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Diesel particulate filter unit and regeneration control... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3067581