JPH07139336A - Exhaust gas purification device - Google Patents

Abstract

PURPOSE:To detect any trouble of a rotational speed sensor without making the structure of an exhaust gas purification device complicated. CONSTITUTION:Any trouble of an engine rotational speed detection means 18 is detected based on the output signal of a pressure detection means or a temperature detection means used for particulate collection, and an alarm is issued at the time of detecting the trouble. Any trouble of a rotational speed detection means 18 is detected based on a generation frequency of an alternator mounted on an engine 20, and then the alarm is generated at the time of detecting the trouble. The trouble of the rotational speed detection means 18 can be detected without increasing any detection means, and then danger of filter damage or trouble of regeneration according to the estimated trouble of a particulate collective quantity can be alarmed.

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 for collecting and regenerating particulate matter (particulates) contained in the exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art In a conventional exhaust gas purifying apparatus, when the amount of collected particulates reaches a certain level, a heater or a blower is energized in a predetermined order to burn the particulates.
Play the filter.

[0003]

If the trapped amount varies in the above filter regeneration, the filter may be melted and the regeneration may be defective. Therefore, the corrected pressure loss obtained by correcting the filter pressure loss by the engine speed and the exhaust temperature. It is preferable to estimate the collected amount of particulates (hereinafter, also simply referred to as collected amount) by using.

However, in this system, when the rotation speed sensor for detecting the engine rotation speed (usually a rotary encoder is adopted because accuracy is required) is inaccurate or erroneously detected, the collected amount is Is inaccurate and causes the above-described filter melting loss or regeneration failure. It should be noted that if the above-mentioned defective reproduction occurs, it is necessary to treat the unburned particulates, which is troublesome.

However, it is not easy to detect a slight deviation of the rotation speed sensor. The present invention has been made in view of the above problems, while avoiding complication of the device configuration,
It is a first object of the present invention to provide an exhaust gas purification device capable of detecting a defect in a rotation speed sensor and issuing an alarm. Further, in order to improve the reliability of the rotation speed sensor, three rotary encoders may be provided and a majority vote may be taken, but it is difficult to adopt because of the increase in space and the complexity of the device configuration.

The present invention has been made in view of the above-mentioned problems, and an exhaust gas purifying apparatus capable of estimating the amount of collected particulates despite a defective rotation speed sensor while avoiding a complicated apparatus configuration. Its second purpose is to provide.

[0007]

An exhaust gas purifying apparatus according to a first aspect of the present invention is a filter arranged in an exhaust passage of a diesel engine, a rotation speed detecting means for detecting a rotation speed of the engine, and the exhaust gas. Temperature detecting means for detecting the exhaust gas temperature in the path, pressure detecting means for detecting the pressure on the upstream side of the filter, and particulates of the filter based on the detected rotational speed, exhaust gas temperature and pressure. A collection amount estimating means for estimating a collection amount, an electric heating means for burning the particulates collected by the filter by heating the filter to regenerate the filter, and introducing regeneration air into the filter. Air supply means, regeneration instruction means for instructing regeneration of the filter when the estimated trapped amount reaches a predetermined level, and a filter issued based on the instruction for regeneration of the filter. Of the rotation speed detection means based on the output signal of the pressure detection means or the temperature detection means, and the energization control means for controlling the energization of the electric heating means and the air supply means in a predetermined order by the input of the data regeneration command. It is characterized in that it is provided with a rotation speed detection means for judging a failure and a warning means for warning a failure of the rotation speed detection means at the time of the failure judgment.

The exhaust gas purifying apparatus of the second invention comprises a filter arranged in the exhaust passage of the diesel engine, a rotation speed detecting means for detecting the rotation speed of the engine, and an exhaust gas temperature in the exhaust passage. Temperature detecting means for detecting the pressure, pressure detecting means for detecting the pressure on the upstream side of the filter, and estimating the particulate collection amount of the filter based on the detected rotational speed, exhaust gas temperature and pressure. A collection amount estimating means, an electric heating means for regenerating the filter by burning the particulates collected by the filter by heating the filter, an air supply means for introducing regeneration air into the filter, Regeneration instruction means for instructing regeneration of the filter when the estimated trapped amount reaches a predetermined level, and input of a filter regeneration command issued on the basis of the filter regeneration instruction. An energization control unit that controls energization to the electric heating unit and the air supply unit in a predetermined order by the rotation speed detection unit that determines a defect in the rotation speed detection unit based on a power generation frequency of an alternator attached to the engine. It is characterized by comprising means failure determination means and warning means for warning the failure of the rotation speed detection means at the time of failure determination.

In a preferred aspect of the first and second aspects of the invention, a counter for accumulating the cumulative engine operating time from the end of the previous filter regeneration is provided, and the regeneration instructing means is the rotation speed detecting means defect determining means. When it is determined that the pressure detecting means is defective, the regeneration of the filter is instructed based on the cumulative engine operating time. First,
In a preferred aspect of the second aspect of the present invention, the collection amount estimating means determines a power generation frequency of an alternator attached to the engine when the pressure detecting means is determined to be defective by the rotation speed detecting means determining means. The trapping amount is estimated based on the exhaust gas temperature and pressure.

[0010]

In the above inventions, the particulate collection amount is estimated based on the corrected pressure loss obtained by correcting the pressure loss of the filter with the engine speed and the exhaust temperature, and based on this estimated collection amount. Determine the playback time. In the first aspect of the present invention, the defect of the rotation speed detecting unit is detected based on the output signal of the pressure detecting unit or the temperature detecting unit used for collecting the particulates, and an alarm is issued when the defect is detected.

According to the second aspect of the present invention, a defect in the rotational speed detecting means is detected based on the power generation frequency of the alternator attached to the engine, and an alarm is issued when the defect is detected. According to both of these inventions, it is possible to detect a defect in the rotation speed detection means without adding any detection means, and it is possible to prevent filter damage due to poor estimation of the amount of collected particulates due to a failure in the rotation speed detection means. It is possible to warn of the danger of defective reproduction.

In the preferred modes of the first and second aspects of the invention, when the pressure detecting means is determined to be defective, the regeneration instructing means determines the accumulated engine operating time from the end of the previous filter regeneration accumulated by the counter. Based on this, the filter regeneration is instructed. In a preferred aspect of the first and second aspects of the invention, when the pressure detecting means is determined to be defective, the collection amount estimating means captures based on the power generation frequency of the alternator attached to the engine and the exhaust temperature and pressure. According to these preferable modes for estimating the collection amount, even if it is determined that the rotation speed detection means is defective, it is possible to instruct the filter regeneration although the accuracy is somewhat sacrificed. -Too much filter collection due to excessive collection amount,
It is possible to prevent defective filter regeneration due to an excessively small amount of collected particulates.

[0013]

【Example】

(Embodiment 1) An embodiment of the exhaust gas purifying apparatus of the present invention is shown in FIG. This exhaust gas purifying apparatus has a filter housing case 1 whose both ends are hermetically sealed, and an upstream pressure sensor for detecting exhaust pressure from the upstream side to the downstream side in the filter housing case 1 (pressure detecting means in the present invention). 7, a temperature sensor (temperature detecting means) 6, a heater (electric heating means) 11, a filter 2, and a downstream pressure sensor (pressure detecting means in the present invention) 17 for detecting filter downstream pressure are arranged in order. The exhaust pipe 3 of the diesel engine 20 is arranged on the upstream end wall of the filter housing case 1, and the air supply pipe 10 is branched from the middle of the exhaust pipe 3. The air pipe 10 has an on-off valve 14
Is connected to the outlet of the blower 13 for supplying air.

On the other hand, the heater 11, the opening / closing valve 14,
The blower (air supply means) 13 is drive-controlled by a controller (collection amount estimation means, regeneration instruction means, energization control means, rotation speed detection means defect determination means in the present invention) 8, and is mounted on the diesel engine 20. The output signal of the rotation speed sensor (rotation speed detection means in the present invention) 18 is output to the controller 8.

The rotation speed sensor 18 is a rotary encoder incorporated in the fuel injection pump in this embodiment. The controller 8 has a microcomputer (not shown) with a built-in A / D converter, processes various data,
The heater 11, the on-off valve 14 and the blower 13 are controlled to perform regeneration, and an abnormality alarm lamp (alarm means) 9 is turned on when an abnormality occurs.

Reference numeral 91 is a reproduction time display lamp.
The filter 2 is a honeycomb ceramic filter (Japanese insulator k
made by k, diameter 5.66 inches x length 6 inches),
It is fired into a cylindrical shape using porous cordierite as a material. The filter 2 has a large number of ventilation holes penetrating both end faces thereof, and one of the adjacent ventilation holes is plugged at the upstream end,
The other one is plugged at the downstream end. The exhaust gas passes through the porous partition wall between the adjacent vent holes, and only the particulates are trapped in the vent holes. Both end faces of the filter 2 face the both end faces of the case 1 with a predetermined distance.

The heater 3 is made of an electrothermal resistor made of a nichrome wire and is arranged in proximity to the end face of the filter 2 which is on the upstream side during regeneration. The operation of this device will be described below. (Particulate collection operation) Diesel engine 20
The exhaust gas discharged from the exhaust gas is introduced into the case 1 through the exhaust pipe 3, particulates in the exhaust gas are collected by the filter 2, and the purified exhaust gas is discharged to the outside from the tail pipe 4.

(Filter Regeneration Operation) Next, the regeneration operation of the filter 2 will be described with reference to the flowcharts of FIGS. It should be noted that in this device, the filter regeneration operation is started by receiving power from an external power source while the engine is stopped and starting it by a manual operation. It is assumed that the opening / closing valve 14 is opened upon start-up, and the opening / closing valve 14 is closed at the end of regeneration.

A filter regeneration discrimination routine (step 200 and steps 100 to 1) executed during engine operation.
FIG. 2 shows a filter regeneration routine consisting of 11) and a filter regeneration execution routine (steps 112 to 116) executed while the engine is stopped. First, the filter regeneration determination routine is started when the engine 20 is started,
After executing a later-described subroutine for determining a failure of the rotation speed sensor 18 in step 200, the pressure sensors 7, 17
Based on the exhaust pressures P1 and P2 detected by the engine speed n, the engine speed n detected by the speed sensor 18, and the exhaust gas temperature T detected by the temperature sensor 6, the particulate collection amount is calculated.

The calculation of the amount G of collected particulates is
This will be described in detail with reference to the subroutine of FIG. First, in step 1001, the exhaust pressures P1 and P2, the rotation speed n, and the exhaust gas temperature T are input. Next, in step 1002, the pressure loss (measured differential pressure) of the filter 2 ΔP = P1−P
In order to eliminate the influence of the number of revolutions N and the exhaust gas temperature T with respect to 2, the correction differential pressure ΔPeqi is calculated by the following correction formula.

ΔPeqi = ΔP × (523 / T) × (2600 / N) The exhaust gas temperature T is an absolute temperature, and the unit of the rotation speed N is r.
pm. That is, the measured differential pressure ΔP is corrected to the corrected differential pressure ΔPeqi when the absolute temperature T is 523 and the rotation speed N is 2600 by the above formula. Therefore, in this embodiment,
The measured differential pressure ΔP is approximated to be inversely proportional to the fluctuation of the exhaust gas temperature T or the rotational speed n. This correction differential pressure ΔP
eqi is calculated every 50 msec.

In the next step 1003, of the correction differential pressures ΔPeqi input every 50 msec in the past, the average value of the immediately preceding 64 calculated values is calculated, and this is set as the average correction differential pressure ΔPeqm. Next, in step 1004, the collection amount G is searched from a table stored in a memory (not shown) incorporated in the microcomputer-type controller 8 and storing the relationship between the average correction differential pressure ΔPeqm and the collection amount G. And then returns to the main routine.

Next, in step 108, it is checked whether or not the searched particulate collection amount G exceeds a predetermined threshold value Gt. If it does not exceed, it returns to step 100, and if it exceeds, it goes to step 111. move on. In step 111, the lamp 91 for instructing filter regeneration is turned on, and the routine ends.

Thereafter, when the driver visually confirms that the lamp 91 for instructing the filter regeneration is turned on and turns on a regeneration switch (not shown) while the engine is stopped, the filter regeneration execution routine is started. In this routine, first, the blower 13 is activated in step 112, then the built-in timer is activated (114), the timer control subroutine is executed, and the heater 11 and the blower 1 are activated at a predetermined timing.
3 is energized (116), the EEPROM described later is reset (118), and the reproduction is ended.

Next, the rotation speed sensor 1 which characterizes the present invention
8 (including failure of the output line from the rotation speed sensor 18 to the controller 8) is determined, and the corresponding subroutine 200 will be described with reference to the flowcharts of FIGS. 4 to 6. Note that this subroutine is executed regularly.
First, the upstream side exhaust gas pressure P1 detected by the pressure sensor 7
Is read (202), and the engine speed N is read from the rotation speed sensor 18 (204).

Next, the maximum value P1max is obtained from the predetermined number of data of P1 within the past T time which has been read and stored.
And the minimum value P1min are extracted (206), and the difference ΔP
Is calculated (208), and it is checked whether the calculated ΔP exceeds 10 mmHg (210). On the other hand, if it exceeds the maximum value Nmax and the minimum value N from the predetermined number of data of N in the time T,
min is extracted (212), and the difference ΔN is calculated (2
14), the calculated ΔN is equal to the predetermined rotation speed difference (here, 100
It is checked whether or not it exceeds 0 rpm (216), and if it is less than that, the process proceeds to step 226.

That is, if the change in the exhaust gas pressure is large but the change in the rotational speed is small, it is determined that the rotational speed sensor 18 is defective. On the other hand, if it exceeds, the routine proceeds to step 218, where it is determined whether or not the pressure P1 for the last 5 seconds is 780 mmHg or more, and if it is less than this, the routine proceeds to step 222.
The exhaust gas pressure of a diesel engine is 780 m.
The presence of mHg or more means operation at a rotation speed exceeding at least the idle rotation speed (here, 500 rpm). If it is above in step 218, it is checked whether the rotation speed N exceeds 500 rpm (220), and if it is below, the routine proceeds to step 226.

That is, the exhaust gas pressure is 780 mmHg
Despite the above, the idle speed (here, 5
It is determined that the rotation speed sensor 18 is defective if the rotation speed is less than or equal to 00 rpm. N is 500 rpm in step 220
If it exceeds, the rotational speed Na of the alternator (not shown) attached to the engine 20 is read in step 222, and the moving average value N of the read alternator rotational speed Na is read.
A mean and the moving average value Nmean of the engine speed N read from the speed sensor 18 are obtained, and it is checked whether the absolute value of the difference between them exceeds a predetermined speed difference ΔNt (224). The rotation speed sensor 18 returns to the main routine as being accurate.

On the other hand, if it exceeds, it is determined that the rotation speed sensor 18 is defective and the routine proceeds to step 226. Therefore, in step 226, an alarm that the rotation speed sensor 18 is defective is output. In this case, the alarm lamp 9 is turned on to give an alarm from the voice ROM IC. Then step 228
Then, the engine cumulative operating time ΣT, which will be described later, is read from the built-in counter, and the read ΣT is the predetermined threshold Σ.
Whether Tt is exceeded or not is checked, and if it is below, it is determined that the regeneration time has not yet been reached, and the process returns to step 202. If it exceeds, it is determined that the regeneration time has been reached, and the process proceeds to step 111.

That is, the average particulate matter discharge amount when the engine is operated for one hour can be regarded as constant when viewed as an average value for an extremely long time, and as a result, the accumulated operating time from the completion of the previous regeneration (here After 10 hours), the regeneration lamp 91 is turned on in step 111 assuming that the particulate collection amount G has reached the threshold value Gt to be regenerated.

Next, a subroutine for calculating the engine cumulative operating time ΣT will be described with reference to FIG. It should be noted that this subroutine is an interrupt routine and is executed immediately after the start of engine operation and every 10 minutes thereafter. First, it is checked whether a flag A described later is 0 (30
2) If it is 1, the process proceeds to step 308. If it is 0, the flag A is set to 1 (304), and the built-in nonvolatile memory (E
The previous engine cumulative operating time ΣT is read from the EPROM), set in a built-in counter (306), and the process returns to the main routine.

In step 308, 10 minutes (1/6 hour) is added to the engine cumulative operating time ΣT set in the counter.
Is added, and it is newly written in the EEPROM (3
10) Return to the main routine. The above E
The EPROM is reset to 0 when the filter regeneration is completed as shown in FIG. (Embodiment 2) Another embodiment will be described with reference to the flowchart of FIG.

This flowchart is based on step 2 of FIG.
28 is replaced, and in this step 228,
In the subroutine for calculating the particulate collection amount G shown in FIG. 3, the engine speed N is replaced with an alternator rotation number Na described later to calculate the particulate collection amount G. However, since the alternator rotation speed Na is k (constant) times the engine rotation speed N, the alternator rotation speed N must be calculated in advance before executing the subroutine of FIG.
a is Na / k.

In this way, the alternator rotation speed N
The particulate collection amount G can be calculated based on a. However, since the alternator rotation speed Na is inferior to the engine rotation speed N output from the engine rotation speed sensor 18 in terms of the SN ratio, the engine rotation speed sensor 18 is used when the engine rotation speed sensor 18 is normal.

Next, a circuit for detecting the alternator rotation speed Na (which is incorporated in the controller 8) will be described with reference to FIG. First, alternator 40
Any one-phase voltage V of the three-phase AC voltage output from 0
After a is divided by the voltage dividing circuit 402 to an appropriate value, the low-pass filter 404 removes high frequency noise. next,
The Schmitt trigger circuit 406 binarizes the counter 40.
8 is input to the count terminal C. The counter 408 is configured to add at the rising edge of the pulse input from the Schmitt trigger circuit 406, the count value is periodically read by the I / O 410 of the controller 8, and then the counter value is counted by the controller 8 through the I / O 410. 408 is reset. The counter 4
The number of bits of 08 is designed with a margin so that overflow does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an exhaust gas purification device of the present invention,

FIG. 2 is a flowchart showing the reproducing operation,

FIG. 3 is a flowchart showing the reproducing operation,

FIG. 4 is a flowchart showing the reproduction operation,

FIG. 5 is a flowchart showing the reproducing operation,

FIG. 6 is a flowchart showing the reproducing operation,

FIG. 7 is a flowchart showing the reproducing operation,

FIG. 8 is a flowchart showing a reproduction operation of another embodiment,

FIG. 9 is a block diagram of a circuit that detects the rotation speed of the alternator.

[Explanation of symbols]

2 is a filter, 6 is a temperature sensor (temperature detecting means), 7,
Reference numeral 17 is a pressure sensor (pressure detection means), 8 is a controller (collection amount detection means, regeneration instruction means, control means, rotation speed detection means defect determination means), 9 is an alarm lamp (warning means), and 11 is a heater ( Electric heating means), 13 is a blower (air supply means), and 18 is a rotation speed sensor (revolution speed detection means).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F01N 9/00 ZAB Z

Claims (4)

[Claims] 1. A filter arranged in an exhaust path of a diesel engine, a rotation speed detecting means for detecting an engine speed of the engine, and a temperature detecting means for detecting an exhaust gas temperature in the exhaust path. Pressure detection means for detecting the pressure on the upstream side of the filter; collection amount estimation means for estimating the particulate collection amount of the filter based on the detected rotation speed, exhaust gas temperature and pressure; An electric heating means for regenerating the filter by burning the particulates collected by the filter by heating the filter, an air supply means for introducing regeneration air into the filter, and the estimated trapping amount to a predetermined level. Regeneration instructing means for instructing regeneration of the filter when reaching, and inputting a filter regeneration command issued based on the instruction of the filter regeneration, the electric heating means, An energization control unit that controls energization to the air supply unit in a predetermined order, and a rotation speed detection unit failure determination that determines a failure of the rotation speed detection unit based on an output signal of the pressure detection unit or the temperature detection unit. An exhaust gas purifying apparatus comprising: a means and a warning means for warning a failure of the rotation speed detection means at the time of the failure determination. 2. A filter arranged in an exhaust path of a diesel engine, a rotational speed detecting means for detecting the rotational speed of the engine, and a temperature detecting means for detecting an exhaust gas temperature in the exhaust path. Pressure detection means for detecting the pressure on the upstream side of the filter; collection amount estimation means for estimating the particulate collection amount of the filter based on the detected rotation speed, exhaust gas temperature and pressure; An electric heating means for regenerating the filter by burning the particulates collected by the filter by heating the filter, an air supply means for introducing regeneration air into the filter, and the estimated trapping amount to a predetermined level. Regeneration instructing means for instructing regeneration of the filter when reaching, and inputting a filter regeneration command issued based on the instruction of the filter regeneration, the electric heating means, Energization control means for controlling the energization of the air supply means in a predetermined order; rotation speed detection means failure determination means for determining a failure of the rotation speed detection means based on the power generation frequency of the alternator attached to the engine; An exhaust gas purifying device, comprising: an alarm unit for alarming a defect of the rotation speed detecting unit when the defect is determined. 3. A counter for accumulating accumulated engine operating time from the end of the previous filter regeneration, wherein the regeneration instruction means is determined to be defective in the pressure detection means by the rotation speed detection means defect determination means. The exhaust gas purifying apparatus according to claim 1 or 2, wherein, in the case of the above, the regeneration of the filter is instructed based on the cumulative engine operating time. 4. The collected amount estimating means, when the rotational speed detecting means defect determining means determines that the pressure detecting means is defective, the power generation frequency of an alternator attached to the engine and the exhaust gas temperature. The exhaust gas purifying apparatus according to claim 1 or 2, wherein the trapping amount is estimated based on the pressure and the pressure.