JPH0636264Y2 - Filter regeneration controller for diesel exhaust purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exhaust gas purification filter provided in an exhaust system of a diesel engine for repairing particulates in exhaust gas, and more particularly to a regeneration control device for this filter. .

[Conventional technology]

Generally, a diesel exhaust purification filter has a predetermined interval at which the amount of collected particulates is expected to exceed a predetermined value (for example, every predetermined integrated value of engine speed).
In addition, it is regenerated by burning particulates. Specifically, an electric heater is disposed near the filter, and the heater ignites and burns the particulates on the filter. Conventionally, a heater is disclosed in Japanese Patent Laid-Open No. Sho 60-12221.
As disclosed in Japanese Patent Publication No. 6, it is divided into a plurality of heater segments, and these heater segments are
Although the energization start time during one regeneration is different, all heater segments are energized so that all the particulates collected in the entire filter are incinerated during one regeneration (collective regeneration). method).

[Problems to be solved by the device]

By the way, in the above filter, the pressure loss before and after the filter immediately before the filter regeneration time (hereinafter referred to as pressure loss)
Is quite large due to the large amount of particulate collection,
Therefore, the output of the engine tends to decrease and the fuel consumption tends to deteriorate. However, as a countermeasure, if the regeneration interval is set small and the pressure loss immediately before filter regeneration is reduced, the amount of particulate collection that is subject to regeneration will be small, and there is a problem that good particulate combustion propagation cannot be achieved during filter regeneration. is there.

It is an object of the present invention to provide a filter regeneration control device that reduces pressure loss immediately before the filter regeneration time and enables good particulate combustion propagation even during filter regeneration.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, a plurality of regenerating means are dispersedly arranged on the side surface of the filter, and these regenerating means are operated at a predetermined interval so that the exhaust gas in the exhaust gas collected by the filter is removed. In a diesel exhaust purification filter regeneration control device in which particulates are removed to regenerate the filter, a plurality of regeneration means are provided in a first group, a second group, ... Nth group (N
Is a natural number) and the playback means of each group is divided into a first group, then a second group, then ......, then an Nth group, then a first group, and then a second group. Each group is designed to be able to operate repeatedly with an equal interval.

[Action]

After the regeneration means of the first group is activated, the regeneration means of the second group is activated at a constant interval, and the regeneration means at every constant interval are sequentially activated until the Nth group, and then the Nth group. When the above-mentioned reproducing means are activated, the reproducing means of the first group are activated again at the above-mentioned fixed interval.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows an embodiment (exhaust system of an applied engine) of the present invention. In this figure, a filter 13 for collecting particulates (composed of carbon fine particles and liquid HC adsorbed on the carbon solid surface) in the exhaust gas and a muffler 14 are provided in the exhaust passage 12 of the diesel engine 11. It is provided. The exhaust passage 12 branches on the upstream side of the filter 13 into a particulate collection passage 12a and a filter regeneration passage 12b, and the filter regeneration passage 12b is located on the downstream side of the filter 13
When the filter is regenerated, the regeneration exhaust gas is guided from the downstream side of the filter 13 to the upstream side of the filter 13. On the downstream side of the branch portion between the passages 12a and 12b and on the upstream side of the filter 13, the exhaust gas from the engine 11 is cut into the regeneration passage 12b by shutting off the particulate collection passage 12a during filter regeneration. First on-off valve 14 to be guided
And a filter regeneration passage 12b and a collection passage 1
A second opening / closing valve 15 is provided at the confluence with 2a for guiding a part of the exhaust gas that has passed through the filter regeneration passage 12b to the filter 13 as regeneration gas. In addition to the above passage, a passage 12c for guiding the particulate combustion gas to the downstream side of the filter at the time of filter regeneration is provided in the vicinity of the first opening / closing valve 14 and the second opening / closing valve 15, and therefore the valve 14 is The so-called three-way valve and the valve 15 operate as a four-way valve. Both the first and second on-off valves 14 and 15 are controlled by an engine control computer (ECU) 18 via differential pressure actuators 16 and 17, and the ECU 18 operates at a predetermined group reproduction timing described later. Output the valve actuation signal. In the figure, the solid line arrow indicates the exhaust gas flow during normal particulate collection, and the dotted line arrow and the dotted line positions of the valves 14 and 15 indicate the exhaust gas flow and valve operating position during filter regeneration.

Filter 13 collects particulates (honeycomb)
The heater 20 includes a filter 19 and a heater 20 adjacent to the side surface of the honeycomb filter 18 on the muffler side.
Are electrically connected to a battery 22 via a heater relay 21 controlled by the ECU 18. Further, as an input to the ECU 18, an engine speed sensor 23 and an accelerator position sensor 24 are provided for determining the regeneration timing of the filter 13, and the particulate matter is trapped according to the integrated value of the engine speed calculated in the ECU 18. It is roughly estimated whether the collection amount exceeds a predetermined value. It should be noted that a vehicle speed sensor (not shown) or the like may be used for determining the filter regeneration time, and a filter 13 may be provided by a back pressure sensor (not shown).
It is also possible to measure the difference between the front and rear pressures and estimate whether or not the particulate collection amount exceeds a predetermined value.

FIG. 2 is a perspective view showing only the filter 13 alone,
As described above, the heater 20 is a cylindrical honeycomb filter 19
It is provided in the vicinity of the side surface of, and is divided into six in this embodiment. That is, according to the present embodiment, the heater 20 as the regenerating means includes the first to sixth heater segments 20a, 20b, 20c, 20d,
Each of the heater segments 20e and 20f has a fan shape centered on the center point of the end face of the filter 13. Then, each heater segment heats the heater portion positioned corresponding to these downstream sides, and incinerates the particulates collected in the heater portion.

According to the present embodiment, in the regeneration process of the filter 13 configured as described above, each heater segment is composed of, for example, a first group of segments 20a, 20b, 20c and a second group of segments 20d, 20e, 20f. Divided into groups of
The heating is controlled by the ECU 18 so that the filter portion corresponding to the first group and the filter portion corresponding to the second group are not collectively regenerated, but are regenerated at different regeneration times and are alternately regenerated. That is, as the energization interval to the heater, unlike the conventional batch regeneration interval, the energization is made in small increments by the amount divided into each group,
The reproduction interval when focusing on individual groups is the same as the conventional interval. That is, for this purpose, the ECU 18 outputs the operation signal of the on-off valves 14 and 15 when the integrated value of the engine speed reaches half of the value corresponding to the regeneration interval so far, and the , An operation signal is output to the heater relay 21 in order to start energizing the heater segments forming one group, which is half, so that the heater segments of each group are alternately energized at every energizing interval.

FIG. 3 is a method of energizing the partial regeneration filter according to this embodiment,
FIG. 6 is a diagram comparing a transition of back pressure as a representative value of pressure loss and that of a conventional collective regeneration filter.

Referring to FIG. 3, as shown in the ON / OFF state of energization to each heater segment, in the conventional filter, for example, when the engine speed integrated value reaches a predetermined value NEI (in this example, a traveling distance of about 500 km is equivalent). Assuming that), all the divided heater segments are energized to regenerate the filter.
Therefore, immediately before the regeneration time, the amount of particulate collection of the heater portion corresponding to each heater segment becomes large and is in a saturated state or a state close to it,
There are problems such as increased back pressure, reduced output, and deterioration of fuel efficiency.
The average back pressure in this regeneration interval experiment was about 110 mmH.
g, and the regeneration time is about 6 minutes to heat all the heater segments.

On the other hand, in the filter of the present embodiment, the heater segments are divided into two groups as described above, and the regeneration energization timing to each group is shifted. For example, the first group has a mileage of about 250 (NEI / 2), 750. , 1250, ... km, the second group is energized when the mileage is about 500 (NEI), 1000, ... km. That is, in the present embodiment, when attention is paid to each heater segment, the regeneration interval does not change from that of the conventional one, and the energization interval to the filter that does not limit the heater segment is shorter and smaller than the conventional one. Will be done.
Therefore, the back pressure immediately before the regeneration of a certain filter in the present embodiment, the amount of particulates trapped in the filter portion corresponding to the heater segment to be energized (for example, the segments 20a, 20b, 20c) is saturated, or Although the state is close, the amount of particulates in the filter part of other heater segments (for example, segments 20d, 20e, 20f) that are not energized is small, so the back pressure level as a whole becomes smaller than before. 75 mmHg
-Experimental value), problems such as output reduction due to large back pressure, deterioration of fuel consumption, etc. will be resolved. Further, since the amount of particulates to be removed per filter portion corresponding to one heater segment does not change from that of the conventional one,
Good combustion propagation is achieved without impairing the ignitability from the heater to the particulates.

In the above, the embodiment of the present invention has been described by taking the 6 heater segment two division reproduction as an example. However, the present invention is not limited to the two division, and for example, a 6 segment filter is divided into two groups of three, and each filter is divided into three groups. The groups may be sequentially reproduced by shifting the reproduction time, and in that case, the energization interval as a filter is equal to the conventional interval shown in FIG. 3 divided into three. Further, the number of heater segments in one filter is not limited to six.

As described above, according to the present embodiment, conventionally, when a filter composed of, for example, 6 heater segments is regenerated, energization is divided type energization for each segment due to problems such as battery capacity. Therefore, the filter portion of the heater segment that is energized first and the filter portion of the heater segment that is energized last differ in the degree of pressure loss in the surroundings, so the flow velocity of the combustion gas flowing therein is different, and There is a problem such as melting loss and crack generation due to the high gas flow velocity in the corresponding filter portion, and there is a problem such as poor regeneration due to the low gas flow velocity in the filter portion corresponding to the fourth and subsequent energization heater segments. On the other hand, in the present invention, even in the case of division-type energization, the regeneration is a partial regeneration in which the number of target segments is smaller than in the conventional case, so that the heater segment energized first and the heater segment energized last are There is no difference in the gas flow velocity between the two, and the exhaust gas flows through the filter portion of the other heater segment that is not the regeneration target, so problems such as cracking, melting loss, and regeneration failure can be solved. Naturally, as described above, there are no problems such as a decrease in output due to a large pressure loss and deterioration of fuel efficiency.

〔effect〕

As described above, according to the present invention, a plurality of reproducing means dispersedly arranged on the side surface of the filter are divided into a plurality of N groups consisting of a first group, a second group, ... Nth group (N is a natural number). The playback means of each group is divided, and the playback means of the first group, then the second group, then ......, then the Nth group, then the first group, and then the second group are repeatedly operated at equal intervals. . In this case, regarding individual groups, the reproduction processing is performed in each group at an interval N times the above interval. This N times interval is a period in which the particulates are sufficiently collected and good reproduction processing is performed. Therefore, when looking at individual groups, good reproduction processing is performed in each group. On the other hand, looking at the entire group, since the regeneration process is performed in any of the groups at the same interval as described above, the pressure loss is reduced each time, and as a result, the pressure loss does not become extremely high, so the engine output decreases. Not only can it be prevented, but also deterioration of the fuel consumption rate can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an exhaust system to which an embodiment of the present invention is applied, FIG. 2 is a perspective view of a heater and a filter; FIG. 3 is a heater segment energization method of the present invention, and back pressure transition. The model figure compared with the past. 13 ... Filter, 20 ... Heater, 20a, 20b, 20c, 20d, 20e, 20f
… Heater segment.

Claims (1)

[Scope of utility model registration request] 1. A plurality of regenerating means are dispersedly arranged on the side surface of the filter, and these regenerating means are operated at predetermined intervals to remove particulates in the exhaust gas collected by the filter to regenerate the filter. In the diesel exhaust gas purification filter regeneration control device configured as described above, the plurality of regeneration means are divided into a plurality of N groups consisting of a first group, a second group, ... N-th group (N is a natural number), The playback means for each group is the first group, then the second group, then ......, then the Nth.
A filter regeneration control device for diesel exhaust gas purification, which is configured to be repeatedly operated at equal intervals in order of a group, then a first group, and then a second group.