JPH0586837A - Exhaust deposit purging device for exhaust pressure sensor - Google Patents

Abstract

PURPOSE:To provide a purging device where exhaust deposit separated from a sensor filter is not purged into the suction system of an engine, in a purging device for exhaust deposit attached to the sensor filter for exhaust pressure sensor on the front and rear of a filter in a diesel engine. CONSTITUTION:This exhaust deposit purging device for exhaust pressure sensor supplies pressurized air from a motor-driven air pump 9 as a gas supply source for filter regeneration, at a pressure introduction passage 16 between a sensor filter 20 installed in the pressure introduction passage 16 to an exhaust pressure sensor 18 and the exhaust pressure sensor 18 while switching valves 5, 6 installed in front and rear of a filter 1 are closed, so that the deposit adhering to the sensor filter 20 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification system provided in a diesel engine, an exhaust pressure sensor provided before and after a filter for judging a filter regeneration timing, and an exhaust gas adhering to a pressure introduction passage leading to the exhaust pressure sensor. The present invention relates to a purging device that removes deposits.

[0002]

2. Description of the Related Art For example, since the exhaust gas of a diesel engine contains a large amount of exhaust particulates, that is, particulates, the exhaust system of the engine has a particulate filter (hereinafter referred to as a filter) for collecting the particulates. Called) is installed.

By the way, in this filter, if the amount of particulates accumulated inside the filter increases with use, the air permeability is gradually impaired and the trapping efficiency is also lowered. Must be replayed on a regular basis.

Regarding the determination of the filter regeneration timing, attention is paid to the differential pressure across the filter as a parameter for detecting the amount of collected particulates, and an exhaust pressure sensor for detecting the exhaust pressure before and after the filter is provided before and after the filter. Purification devices are already known.

Further, in Japanese Unexamined Patent Publication No. 61-49116, the exhaust pressure sensor and the exhaust gas are prevented in order to prevent the exhaust pressure from being undetectable due to the adherence of particulates in the exhaust gas around the exhaust pressure sensor of the exhaust gas purification device. There is disclosed a device in which a sensor filter that collects particulates and moisture in exhaust gas is provided in a pressure introduction passage that connects the passages.

[0006]

By the way, in the above device provided with the sensor filter, in order to clean the sensor filter, a suction pipe connecting the sensor filter and the intake pipe is provided, and the sensor filter is provided with a suction pipe. The collected particulates and water are purged to the intake system by the intake negative pressure.

However, when the deposit thus collected by the sensor filter is purged into the intake system of the diesel engine, a deposit is similarly formed on the inner wall of the intake pipe and around the intake valve, which reduces the intake resistance of the engine. There is a risk that the engine operation will be adversely affected.

It is an object of the present invention to provide an exhaust deposit purging device which does not purge the sensor filter deposit into the engine intake system.

[0009]

In order to achieve the above object, an exhaust deposit purging device for an exhaust pressure sensor according to the present invention comprises a filter provided in an exhaust passage of a diesel engine for collecting particulates, and a filter front side. A bypass passage connected to the exhaust passage for bypassing the filter, an on-off valve provided between the exhaust passage portion connected to the bypass passage and the filter for opening and closing the exhaust passage, and a bypass passage between the on-off valve and the filter. A pressure introducing passage connected to the exhaust passage, an exhaust pressure sensor for detecting the exhaust pressure of the filter front portion introduced through the pressure introducing passage, and an exhaust gas provided in the pressure introducing passage for exhausting the exhaust pressure sensor. It has a sensor filter for cleaning and an air supply means for supplying pressurized air to a pressure introducing passage between the exhaust pressure sensor and the sensor filter when the on-off valve is closed.

[0010]

When the on-off valve is closed, the air supply means supplies the pressurized air into the pressure introducing passage between the sensor filter and the exhaust pressure sensor, and the deposit is exhausted due to the difference between the pressure in the exhaust passage upstream of the filter. Purged into the passage.

[0011]

Embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1 showing a schematic configuration of an exhaust deposit purging device (hereinafter, simply referred to as a purging device) according to the present invention, 1 is a filter for collecting particulates, 2 is a particulate matter from the engine body 3 at the time of collecting particulates. Exhaust gas filter 1
The exhaust passage 4 is also a bypass passage for bypassing the exhaust gas from the filter 1 when the filter 1 is regenerated.

Inside the exhaust passage 2 extending in front of and behind the filter 1, the exhaust gas flow for trapping particulates and for regenerating the filter as described above is achieved.
An on-off valve 5 and a second on-off valve 6 are provided, and a bypass valve 7 is provided inside the bypass passage 4.
These valves are operated and controlled by a control circuit (ECU) 8 so as to close the bypass passage 4 and open the exhaust passage 2 at the time of particulate collection, and occupy the positions shown by the solid line in the figure at the time of filter regeneration. It

Between the second on-off valve 6 arranged inside the exhaust passage 2 and the filter 1, secondary air for filter regeneration is supplied to the downstream side of the filter 1 for particulate combustion during filter regeneration. An electric air pump 9 is provided as an air supply means in the present embodiment, which is supplied with power from a battery 11 together with a filter regeneration electric heater 10 arranged on the downstream side of the filter 1.

Regarding these elements for regenerating the filter, 12 is a heater relay that is turned on and off by the control circuit 8, 13 is an air pump filter, and 14 is pressurized air from the electric air pump 9 and is exhausted on the downstream side of the filter. An air inflow path leading to the passage 2 and reference numeral 15 are regenerated gas discharge paths for discharging the regenerated gas passing upstream of the filter 1 into the atmosphere.

In order to detect the particulate trapped state in the filter 1, the first pressure introducing passage 16 is provided in each exhaust passage 2 portion between the filter 1 and the first and second on-off valves 5, 6. And a second pressure introducing passage 17 are connected to the first exhaust pressure sensor 18 (upstream of the filter) and a second exhaust pressure sensor for detecting exhaust pressure (hereinafter referred to as exhaust pressure) in the exhaust passage region. 19 (downstream of the filter) is provided.

Further, in the present embodiment, exhaust pressure sensors 18, 1 for impurities such as water vapor and particulates existing in the exhaust gas are provided in the middle of the first and second pressure introducing passages 16, 17 described above.
The first sensor filter 20 for preventing the adherence of 9 to the detection surface
And a second sensor filter 21 are provided respectively.

In the exhaust gas purification system constructed as described above, according to this embodiment, the first exhaust pressure sensor 18 and the first exhaust pressure sensor 18 are provided.
First pressure introducing passage 16 extending between the sensor filters 20
(Portion) and the air inflow path 1 extending from the electric air pump 9
4 is in communication with another air inflow path 22. A switching valve 23 is provided at a connection portion between the air inflow passage 14 and the air inflow passage 22 for switching the compressed air from the electric air pump 9 to the downstream side of the filter or to the first sensor filter 20. , Its operation is controlled by the control circuit 8.

The first exhaust pressure sensor 1 is provided on the input side of the control circuit 8.
8 and the analog signals from the second exhaust pressure sensor 19, various signals indicating the current operating state of the engine, such as signals indicating the intake air amount and the engine speed, are input. Then, the control circuit 8 controls the engine based on the operating information obtained from these various sensors, and in the case of the filter 1, determines the filter regeneration time and drives the electric air pump 9 and the electric heater 10. The purge processing of the exhaust deposits adhering to the sensor filter, which is a feature of the present invention, is executed.

The operation of the filter regeneration process and the sensor filter purge process in the above-described exhaust gas purification system will be described below with reference to the time chart of heater energization and secondary air supply shown in FIG. 2 and FIG. First exhaust pressure sensor 18
If the differential pressure across the filter, which is determined by the exhaust pressure from the second exhaust pressure sensor 19, exceeds a predetermined value and it is determined that the filter regeneration time has been reached, the control circuit 8 controls each open / close valve, that is, the first open / close valve. The actuators are operated so that the on-off valve 5, the second on-off valve 6 and the bypass valve 7 occupy the positions shown by the solid lines in FIG. 1, and the exhaust gas from the engine body 3 bypasses the filter 1 and the inside of the bypass passage 4. To make it flow.

Further, the control circuit 8 turns on the heater relay 12.
Then, the electric heater 10 is energized to heat the heater, and the electric air pump 9 is activated to supply the secondary air as the filter regeneration gas to the downstream side of the filter (see FIG. 2).
Playback start point). As a result, the particulate flame ignited at the downstream end of the filter is
The secondary air flow propagates to the upstream side of the filter, and the incineration of the particulates trapped by the filter is thereby achieved. The regenerated gas that has passed through the filter is discharged into the atmosphere through the regenerated gas discharge passage 15.

By the way, according to the present embodiment, as shown in FIG. 2, the purging process of the exhaust deposits of the first sensor filter 20 is executed subsequent to the above-mentioned filter regenerating process. This is because when compressed air is supplied to the first sensor filter 20 immediately before the filter regeneration process, the filter 1 itself is cooled by this pressurized air, and the particulates are unlikely to ignite even if regeneration occurs and the heater power is consumed accordingly. Because it will be done.

If the purging process is to be executed in the particulate trapping and concentration, the compressed air must be supplied to the first sensor filter 20 at a pressure sufficient to overcome the pressure inside the exhaust passage 2, and the electric air pump 9 correspondingly. This is also unrealistic, as the load on

Regarding the specific purging process, first, after the filter regeneration is completed, the switching valve 23 is operated (the purge start point in FIG. 2) while maintaining the open / close valve positions shown in FIG. 1, and the electric air pump 9 is operated. The compressed air from is introduced into the air inflow path 22 (Here, since the first opening / closing valve 5 and the second opening / closing valve 6 shut off the exhaust passage 2, the pressure in the exhaust passage 2 part during this time is substantially large. Atmospheric pressure). As a result, the pressurized air that has flowed into the first pressure introduction path 16 through the air inflow path 22 is caused by the pressure difference between the inside of the air flow path (high pressure) and the exhaust path part (atmospheric pressure).
0 flows toward the exhaust passage 2 side, and by this flow, the particulates and the like accumulated on the first sensor filter 20 are dropped to the exhaust passage 2 side, whereby the sensor filter is cleaned and the sensor filter itself. The filtration characteristics of will be restored.

In the illustrated embodiment, the exhaust deposit separated from the first sensor filter 20 flows into the exhaust passage 2 and is then released into the atmosphere through the regeneration gas release passage 15 described above. Although not shown as another embodiment, the switching valve 23 is switched to the first sensor filter 20 side, and at the same time, the regeneration gas discharge passage 15 is closed by an appropriate valve means (not shown), The exhaust deposit discharged from 20 may be collected by the filter 1 (in this case, the second opening / closing valve 6 is opened so that the air passing through the filter 1 can easily flow downstream as it is). Therefore, the bypass passage 4 is not connected to the downstream passage of the filter 1 and is open to the atmosphere).

By the way, in the embodiment described above, the purging process is limited to the first sensor filter 20 which tends to collect a large amount of particulates due to its positional relationship. However, the present invention is not limited to this embodiment, and may be applied to both the two sensor filters 20 and 21 as a matter of course.

FIG. 3 shows a second embodiment of the present invention which is premised on purging both sensor filters. In this figure, the same components as those in the previous embodiment are designated by the same reference numerals.

According to the present embodiment, as is apparent from the drawing, the air flow passage 14 from the electric air pump 9 is constructed so as to be partially shared with the piping of the second exhaust pressure sensor 19 on the filter downstream side. During the regeneration processing period, the sensor filter 21 is purged so that the air always passes through the second sensor filter 21. After the regeneration process, the air flow passage 1 is maintained with each on-off valve maintained in the state of filter regeneration.
4 operates the switching valve 23, and supplies the air from the air pump to the first sensor filter 20 to clean it. In the figure, 24 is a cut valve for stopping the air supply from the electric air pump 9 as required.

As described above with reference to the two embodiments,
Since the air from the electric air pump 9 is supplied between the sensor filter 20 or 21 and the exhaust pressure sensor 18 or 19 at the time of closing the first and second opening / closing valves in common to both of them, the pressure difference causes the air to flow. Flows back inside the sensor filter toward the exhaust passage, and at this time, the sensor filter 2
The exhaust deposit separated from 0 and 21 will flow into the exhaust passage. Therefore, unlike the conventional device for purging the intake system, the deposit is not sucked into the engine body, and the engine operation failure does not occur.

Further, in the above-mentioned embodiment, the electric air pump 9 as the filter regeneration gas supply source is also used as the air supply means to the sensor filter, but it is needless to say that the dedicated air supply means is provided. You can

[0030]

As described above, according to the present invention, when the on-off valve is closed, the air supply means supplies the pressurized air into the pressure introducing passage between the sensor filter and the exhaust pressure sensor, so that the filter upstream. Since the deposit is purged into the exhaust passage due to the difference between the pressure in the exhaust passage and the exhaust passage, the sensor filter can be cleaned without increasing the output of the air supply means, and the exhaust deposit separated from the sensor filter can be sucked in. There is no need to purge the system, and therefore it is possible to reduce the risk of forming a deposit in the intake system and causing engine failure.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exhaust deposit purging device as a first embodiment of the present invention.

FIG. 2 is a time chart diagram for explaining the operation of the purging device shown in FIG.

FIG. 3 is a schematic configuration diagram of an exhaust deposit purging device as a second embodiment of the present invention.

[Explanation of symbols]

 1 ... Filter 2 ... Exhaust passage 3 ... Engine body 4 ... Bypass passage 5, 6 ... Open / close valve 8 ... Control circuit 9 ... Electric air pump 16, 17 ... Pressure introduction passage 18, 19 ... Exhaust pressure sensor 20, 21 ... Sensor filter 22 … Air inlet 23… Switching valve

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 29, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

[0030]

As described above, according to the present invention, when the on-off valve is closed, the air supply means supplies the pressurized air into the pressure introducing passage between the sensor filter and the exhaust pressure sensor, so that the filter upstream. Since the deposit is purged into the exhaust passage due to the difference between the pressure in the exhaust passage and the exhaust passage, the sensor filter can be cleaned without increasing the output of the air supply means, and the exhaust deposit separated from the sensor filter can be sucked in. There is no need to purge the system, and therefore it is possible to reduce the risk of forming a deposit in the intake system and causing engine failure.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Added

[Correction content]

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exhaust deposit purging device as a first embodiment of the present invention.

FIG. 2 is a time chart diagram for explaining the operation of the purging device shown in FIG.

FIG. 3 is a schematic configuration diagram of an exhaust deposit purging device as a second embodiment of the present invention.

[Explanation of Codes] 1 ... Filter 2 ... Exhaust passage 3 ... Engine body 4 ... Bypass passage 5, 6 ... Open / close valve 8 ... Control circuit 9 ... Electric air pump 16, 17 ... Pressure introduction passage 18, 19 ... Exhaust pressure sensor 20, 21 ... Sensor filter 22 ... Air inflow path 23 ... Switching valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location F01N 9/00 Z 7910-3G

Claims (1)

[Claims] 1. A filter provided in an exhaust passage of a diesel engine to collect particulates, a bypass passage connected to an exhaust passage in front of the filter and bypassing the filter, and an exhaust passage portion connected to the bypass passage. An on-off valve provided between the filter and the exhaust passage for opening and closing the exhaust passage, a pressure introduction passage connected to the exhaust passage between the on-off valve and the filter, and a filter front portion introduced through the pressure introduction passage. An exhaust pressure sensor for detecting exhaust pressure, a sensor filter provided in the pressure introducing passage for purifying exhaust gas to the exhaust pressure sensor, and a pressure introducing passage between the exhaust pressure sensor and the sensor filter when the on-off valve is closed. An exhaust deposit purging device for an exhaust pressure sensor, comprising an air supply means for supplying compressed air.