JP2988149B2 - Diesel engine exhaust purification system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus provided in a diesel engine, and more particularly to an exhaust gas purifying apparatus provided with an exhaust gas filter for collecting particulates in exhaust gas.

[0002]

2. Description of the Related Art Generally, since exhaust gas of a diesel engine contains a large amount of exhaust particulates, that is, particulates, a filter for trapping the particulates is provided in an exhaust passage of the engine. When the amount of particulates accumulated inside the filter increases as it is used, the air permeability gradually deteriorates and the engine performance decreases, so the filter is periodically regenerated according to the amount of particulates collected. It is supposed to be.
The filter regeneration means that the filter is heated by filter regeneration heating means such as a gas burner or an electric heater to ignite and burn the particulates, thereby ensuring the air permeability of the filter again.

[0003] In the exhaust gas purifying apparatus as described above, when the filter regeneration process is interrupted, for example, when the engine is stopped, the filter enters an incomplete regeneration state. In such a case, if the regeneration start condition is satisfied again and the filter regeneration process is restarted, there are many cases where there is no particulate already in the vicinity of the regeneration heating means, and as a result, the particulate in the filter is ignited. Can't do it and cause poor reproduction
There is a possibility .

[0004] In response to such a problem, the present applicant first increases the filter differential pressure (pressure loss) predetermined value ΔP as a filter regeneration determination parameter according to the elapsed time from the start of regeneration to the interruption when filter regeneration is interrupted. After the interruption, the regeneration timing is determined based on the new regeneration reference value, and after the particulates are deposited near the heater, the next regeneration after the interruption is completed. A purifying device has been proposed (Japanese Patent Application No. 4-22764).

[0005]

However, in the above-mentioned exhaust gas purifying apparatus, when the regeneration is restarted, the judgment of the regeneration timing depends only on the filter differential pressure, and even this is disposed in front of the filter (or before and after the filter). Because the pressure is determined using a pressure sensor, depending on the quality and reliability of the sensor itself, it may not be possible to collect a sufficient amount of particulates until the next regeneration after the interruption. May not be able to ignite particulates.

The present invention has been made in view of the above problems of the exhaust gas purification apparatus, and has as its object to ensure the next regeneration after the suspension of regeneration.

[0007]

According to the first aspect of the present invention , there is provided:
Exhaust purification device for a diesel engine according includes a filter for collecting particulates in exhaust gas provided in an exhaust passage of a diesel engine, a filter regeneration heating means for regenerating the filter by ignition combustion particulates of the filter Exhaust purifying equipment for diesel engines equipped with
The filter when the regeneration start condition is satisfied.
Activate the regeneration heating means to start regeneration of the filter
Regeneration start control means and the filter regeneration heating means are stopped.
If the filter is stopped and regeneration of the filter is interrupted,
The regeneration of the filter is restarted only if the raw start condition is satisfied.
Do not open, after the filter regeneration heating means has stopped,
Diesel engine has been running for more than a specified period
Sometimes, the filter regeneration heating means is activated to
Resumption control means for resuming reproduction of data
It is characterized by .

[0008] Diesel according to claim 2 according to the present invention
An exhaust gas purification apparatus for an engine according to claim 1.
In the apparatus, the filter regeneration heating means may include the filter.
The power is shared with the diesel engine, and the power is
When the pressure becomes equal to or less than a predetermined value, the operation is stopped.

[0009]

The exhaust gas purification of a diesel engine according to claim 1.
According to the device, when the reproduction start condition is satisfied, the reproduction is started.
The control means activates the filter regeneration heating means to perform the filtration.
Starts regeneration of the filter, but the filter regeneration heating means stops.
If the regeneration of the filter is interrupted by
The stage will only regenerate the filter if the regeneration start condition is satisfied
Without restarting the filter, wait for the filter regeneration heating
When the diesel engine has been running for more than a predetermined period
Activate the filter regeneration heating means to restart the regeneration of the filter.
Open .

[0010] Diesel according to claim 2 according to the present invention
According to the exhaust gas purifying apparatus for an engine, the exhaust gas according to claim 1 is provided.
In the gas purification device, the filter regeneration heating means is in operation.
The voltage of the power supply shared with the diesel engine
Stop when it falls below.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. Referring to FIG. 1 showing a schematic configuration of an exhaust gas purification apparatus according to the present invention, reference numeral 1 denotes an exhaust pipe for guiding exhaust gas from a diesel engine main body E to filters 2 and 3. Filter 2,
3 is configured as a honeycomb filter in which plugs are arranged alternately at the ends of a large number of cells in order to collect the particulates in the exhaust gas. At the time of particulate collection, the exhaust gas has an upstream end. After entering through the opened cell and passing through the partition, the downstream end of the cell exits the filter through the opened cell.

A first exhaust control valve 4 and a second exhaust control valve 5 are provided at a branch portion a of the exhaust pipe 1. For example, when the filter is regenerated, the first exhaust control valve 4 is first connected to the exhaust pipe as shown in FIG. After the filter 1 is closed, the filter 2 is regenerated. After the regeneration of the filter 2, the second exhaust control valve 5 closes the exhaust passage to the filter 3, and the regeneration process of the filter 3 is continuously performed.

In this apparatus, during the regeneration of one of the filters, the collection of the particulates is continued by the remaining filters, and the above-described exhaust control valves 4 and 5 for controlling the exhaust flow correspond. Actuators 6, 7
The operation of the actuators 6 and 7 is controlled by an output from a control circuit (ECU) 8. Electric heaters 9 and 10 are provided at the exhaust upstream end of each of the filters 2 and 3 as filter regeneration heating means, and power from the battery 11 is supplied via a heater relay 12 which is turned on and off by the ECU 8. It has become.

Each of the filters 2 and 3 has an electric air pump 13 as a particulate combustion gas at the time of filter regeneration.
The secondary air supply passage 14 from the air pump communicates with the exhaust passage when the exhaust control valves 4 and 5 shut off the corresponding exhaust passage. The secondary air is supplied to the filters 2 and 3. According to the present embodiment, the electric air pump 13 is configured as a DC motor type air pump to supply the secondary air at a stable flow rate without being affected by the power fluctuation of the battery 11. The potential difference sensor 15 for detecting the inter-voltage VM is connected.

The ECU 8 outputs a duty signal to the power transistor 16 so that the voltage VM between the air pump terminals is feedback-controlled to a constant value. When the filter is regenerated, the secondary air having a stable flow rate regardless of the battery voltage fluctuation. To the filter. In the present embodiment, an opening / closing valve 17 controlled to be opened and closed by the ECU 8 is provided in the secondary air supply passage 14 and is opened a predetermined time after the heater is energized at the time of filter regeneration. Is supplied.

The exhaust pressure upstream of the filter (in the illustrated embodiment, the atmospheric pressure is at the downstream of the filter) in order to detect the filter pressure difference ΔP for determining the filter regeneration time. Therefore, a pressure sensor 18 for detecting the upstream exhaust pressure is equivalent to the differential pressure) is provided,
The output signal is input to the ECU 8.

On the input side of the ECU 8, in addition to the above-described pressure sensor 18, an exhaust gas temperature Tex guided to the filters 2 and 3.
, An engine speed sensor 20 for detecting the engine speed NE, an intake air temperature sensor 21 for detecting the temperature Tin of the intake air taken into the engine E, an intake pressure sensor 22 for detecting the intake pressure Pin, and the like. Connected respectively,
The operating state of the engine E is detected based on output signals from the sensors. In addition, signals from various sensors other than the above-described sensors are input to the ECU 8, but here, only sensors related to the operation of the exhaust gas purification device are shown.

Hereinafter, the operation of the ECU 8 relating to the regeneration of the filter of the exhaust gas purification apparatus described above will be described with reference to the flowcharts shown in FIGS. FIG. 2 shows a pressure sensor 1
8 is a flowchart for explaining the operation of the apparatus for correcting the filter differential pressure ΔP detected by the above-mentioned various sensors to a differential pressure value under standard operating conditions by the various sensors described above, and judging the filter regeneration timing based on the filter differential pressure value ΔPs. And is executed when the engine is operating.

In the following, this routine will be described. First, at step S21, the engine speed NE is detected from the speed sensor 20. Then, at step S22, the intake pressure Pin from the intake pressure sensor 22, and at step S23, the intake temperature sensor 2
1, the intake air temperature Tin, and in step S24, the exhaust gas temperature sensor 1
9, each operating characteristic indicating the current operating state, such as the exhaust temperature Tex, is detected. In the subsequent step S25, the pressure difference ΔP across the filters 2 and 3 is detected by the pressure sensor 18.

In step S26, the differential pressure .DELTA.P is calculated from the operating characteristics determined as described above using, for example, the following equation (1) to calculate the differential pressure .DELTA.Ps under standard operating conditions.
Is performed. ΔPs = ΔP × (Texo / Tex) × (NEo / NE) × (Pino / Pin) × (Tin / Tino) (1) where Texo: reference exhaust temperature (° K) NEo: reference engine speed (rpm) ) Pino: Reference intake pressure Tino: Reference intake temperature (° K) As described above, the differential pressure Δ across the filter under standard operating conditions
After Ps is obtained, next, in step S27, in order to make the value reliable, for example, the differential pressure value calculated this time for the past n-1 pieces of corrected differential pressure data is set as ΔPsn, and their integration is performed. The so-called averaging process (averaging process) is performed by dividing the value by n.

ΔPsave = (ΔPsn + ΔPsn−1 + ΔPsn−2 +... + ΔPs2 + ΔPs1) × (1 / n) (2) where ΔPsave: averaged corrected differential pressure In the step S28 following the step S27, the differential pressure value ΔPsave obtained in this way is compared with a predetermined differential pressure value ΔPa determined as a regeneration judgment reference value. Is determined. If the determination in step S28 is Yes, and it is determined that the particulates have been collected to the extent that regeneration is required, the process proceeds to step S29, in which the filter regeneration processing program stored in another area of the ECU 8 is activated. To start, step S3 in FIG.
It will go to zero.

On the other hand, if the determination in step S28 is No, the exhaust gas purifier does not need to regenerate the filter at present. End the routine.

In this way, if it is determined that it is time to regenerate the filter, the exhaust purifying apparatus first operates the exhaust control valve 4 to regenerate from the filter 2 and then proceeds to energize the heater 9. However, in this embodiment, the voltage V of the battery 11 during the reproduction is sequentially detected as the reproduction stop condition,
If there is a possibility that the battery voltage V may drop so that the starter during or after the regeneration cannot be driven, the filter regeneration is stopped before that.

The flowchart of FIG. 3 following FIG. 2 sets the limit voltage V1 + α at which the starter can be driven at least once to a predetermined value Va, and when the battery voltage V falls below the predetermined value, stops the filter regeneration processing. This is to explain the process of resuming the interrupted playback in the playback interrupted state. Referring to the figure, first, in step S30, the battery voltage V under execution of the filter regeneration process is read, and it is determined whether or not the battery voltage V is equal to or higher than a predetermined value Va.
To continue turning off the battery abnormality lamp, and
Proceeding to 32, the battery voltage check during the regeneration is continued until it is determined that the filter regeneration is completed.

The determination in step S30 is made based on the measured battery voltage after at least a predetermined time (for example, 10 seconds) has passed since the heater was turned on in the filter regeneration process in order to increase its reliability. Is preferred. Therefore, in this case, specifically, a process of determining whether or not a predetermined time has elapsed after the start of energization of the heater prior to step S30 is included.

Next, if the determination in step S30 is No, and the battery voltage V falls below the predetermined value Va, the routine immediately proceeds to step S33 to turn on the battery abnormality lamp, and in step S34, the currently executed filter is executed. The progress of the regeneration processing program, specifically, whether the filter 2 or the filter 3 is currently being reproduced is checked, and the type of the filter being reproduced (the filter 2 or 3) is determined in the ECU 8. It is stored in a memory, preferably a backup RAM.

This is because even if the driver inspects the vehicle (for example, replaces the battery) with the interruption of the filter regeneration described below and the battery terminal is disconnected at that time, the backup RAM is used to determine whether the vehicle is disconnected. By making it clear whether or not the reproduction is interrupted by the filter, the reproduction restart processing after the battery terminal is reconnected is ensured.

Step S3 following step S34
In step 5, a process for stopping the currently executed filter regeneration processing program is performed, and further, a process for returning the position of the exhaust control valve 4 or 5 to the particulate collection position. In the state where the filter regeneration processing has been interrupted as described above, the routine proceeds to step S36. Here, the ECU 8 determines whether the stopped regeneration process is the filter 2 or not.
Read from the backup RAM inside.

If the determination in step S36 is Yes, the routine proceeds to step S37, in which it is determined whether the current operating condition satisfies the condition for restarting the regeneration of the filter 2. In this embodiment, the conditions for resuming the reproduction are as follows:
For example, in addition to the conventional determination of only the differential pressure value before and after the filter, the integrated value of the engine speed after the regeneration was interrupted was also used as a regeneration resuming determination parameter. Sometimes, particulate re-ignition by the heater 9 is ensured.
It should be noted that the reference value of the engine speed integrated value is determined based on the battery voltage V
Is preferably set so as to be able to return to a predetermined value Va or more.

An example of the filter 2 regeneration restart condition is shown below. NE ≠ 0; engine water temperature Thw ≧ 65 ° C .; ΔPsave ≧ ΔPa; engine speed integrated value ΣNE ≧ m As described above, if the regeneration restart condition of the filter 2 is satisfied in step S37, the routine proceeds to step S38.
The filter regeneration processing program of the exhaust gas purification device, which was interrupted in step S1, is started from the beginning (from the filter 2), the battery abnormality lamp that was lit earlier is turned off, and the process returns to step S30 and is restarted. During the reproduction process, the reproduction is continued while checking the battery voltage V. If the determination in step S37 is No, the reproduction interruption is continued until the reproduction restart condition is satisfied.

Returning to step S36, the determination is No here, that is, if the interrupted regeneration is the filter 3, the routine proceeds to step S39, where the routine proceeds to step S3.
Similarly to 7, it is determined whether or not the condition for restarting the reproduction of the filter 3 is satisfied. According to the present embodiment, the condition for restarting the regeneration of the filter 3 is that the regeneration of the filter 2 has already been completed, so that the differential pressure across the filter is excluded and the engine speed integrated value 中断 NE after the interruption and the engine Revolution N
E, the engine water temperature Thw is used as a determination parameter (for example, regeneration is resumed when ΣNE ≧ n; NE ≠ 0; Thw ≧ 65 ° C.).

If the condition for restarting the regeneration of the filter 3 is satisfied in step S39 as described above, the routine then immediately executes the process of starting the regeneration of the filter 3 and turns off the battery abnormality lamp in step S40. Returning to step S30, the reproduction is continued while checking the battery voltage V. On the other hand, in the case of No in step S39, the reproduction interruption is continued until the condition for resuming the reproduction of the filter 3 is satisfied.

As described above, the filter regeneration timing judgment and regeneration suspension / restart operation as one embodiment of the exhaust gas purifying apparatus according to the present invention have been described. According to the present embodiment, the conventional filter differential pressure ΔPsave is used as the regeneration restart parameter. Not only that, but also the operating characteristics such as the engine water temperature Thw, the engine speed NE, and the engine speed integrated value ΣNE are also used as the regeneration start conditions. Therefore, when a certain amount of particulates is collected near the heater, the regeneration is performed. It is possible to restart, and it is possible to ignite the particulates steadily during reproduction.
Regarding the engine speed integrated value, in addition to simply integrating the engine speed NE after the regeneration is interrupted as in the above-described embodiment, the engine load at that time is taken into consideration in the engine speed NE, and for example, FIG. The engine speed NE and load (or accelerator opening A
ccp) The actual engine speed NE may be corrected by the correction coefficient k obtained from the map, and the reproduction start timing may be determined based on the magnitude of the integrated value ΣNE 'of the corrected speed NE'.

In addition, according to the present embodiment, the filter regeneration process is immediately stopped when the battery voltage at that time falls below a predetermined value (starter drive limit voltage + α). In this case, there is no problem that the starter cannot be driven, or even if the engine can be started, power is consumed for the filter regeneration and the starter cannot be driven at the start of the engine operation after the regeneration.

Also, in this embodiment, even if the regeneration is stopped due to the battery voltage, the next regeneration start requires a predetermined amount of engine speed integrated value, that is, a predetermined engine operating period. Charging is performed and the battery voltage can be restored.

[0036]

As described above, the claims according to the present invention are described below.
According to the exhaust gas purification device for a diesel engine described in 1
If the filter regeneration heating means stops, regeneration of the filter
When the reproduction is interrupted, the reproduction resumption control means
Is satisfied, the regeneration of the filter is not restarted.
Diesel engine started after luta regeneration heating means stopped
Filter regeneration heating when operated for more than a predetermined period
Activate the means to restart the regeneration of the filter.
The filter regeneration heating during this predetermined period.
Particulates are reliably collected near the means and
Good ignition of particulates when resuming life
be able to.

The diesel engine according to claim 2
According to the exhaust gas purification device of the present invention, the filter regeneration heating means
The power is shared with the diesel engine, but the power
Stops when the pressure falls below a predetermined value.
In addition, various problems with diesel engines
This can be prevented from occurring .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an exhaust gas purification device according to the present invention.

FIG. 2 is a diagram illustrating a part of a flowchart for instructing a filter regeneration operation of the exhaust gas purification apparatus according to the present invention and explaining a processing part relating to a regeneration timing determination process.

FIG. 3 is a partial flowchart illustrating a processing portion relating to a reproduction suspension / resumption process, following the flowchart of FIG. 2;

FIG. 4 is a diagram showing a map for setting a correction coefficient to an effective engine speed integrated value based on the engine speed and load.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exhaust pipe (exhaust passage) 2, 3 ... Filter 8 ... Control circuit (ECU) 9, 10 ... Heater 11 ... Battery

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-199616 (JP, A) JP-A-5-222917 (JP, A) JP-A-5-231131 (JP, A) JP-A-5-231131 195751 (JP, A) Hira 4-87317 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F01N 3/02 301-341

Claims (2)

(57) [Claims] 1. A diesel engine comprising: a filter provided in an exhaust passage of a diesel engine for collecting particulates in exhaust gas; and filter regeneration heating means for regenerating the filter by igniting and burning the particulates of the filter. In the exhaust gas purifying apparatus, when the regeneration start condition is satisfied, the filter regeneration heating means
To start regeneration of the filter by operating
Control means and the filter regeneration / heating means
If the filter playback is interrupted, the playback start condition
The regeneration of the filter is not resumed just by
After the filter regeneration heating means has stopped,
When the engine has been running for more than a predetermined period of time.
The filter regeneration is restarted by operating the filter regeneration heating means.
And a regeneration restart control means that opens . 2. The filter regeneration heating means according to claim 1 , wherein:
The power is shared with the diesel engine, and the power is
The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein the apparatus stops when the pressure becomes equal to or less than a predetermined value .