JPH056011B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust purification device for a diesel engine.

In general, diesel engine exhaust purification devices are
If fine particles such as carbon particles decomposed and liberated from fuel in a high-temperature combustion chamber are released into the atmosphere as they are, problems such as air pollution may occur. It attempts to purify exhaust gas by collecting carbon particles and the like. However, when this exhaust purification device is used for a long time and the amount of carbon particles collected increases, the filter member becomes clogged with the carbon particles, and the pressure of the exhaust gas on the upstream side of the filter member increases. This rises and becomes an operating resistance of the engine, resulting in a problem that the engine output decreases.

Therefore, in order to prevent engine output from decreasing, in conventional exhaust purification devices, when the mileage reaches a predetermined distance or when the filter member becomes clogged, the burner device removes the clog. The carbon particles are heated to burn them to eliminate clogging of the filter member (see Japanese Patent Laid-Open No. 71315/1983).

In conventional exhaust purification devices, as mentioned above, the burner device was activated even when the vehicle was stopped when the mileage reached a predetermined distance or when the filter member became clogged. . However, if you do this, the exhaust gas temperature during burner operation will be 600℃.
The heat from the exhaust gas was as high as ~1,000 degrees Celsius, causing problems such as burning dry grass on the road and causing burns to passersby. In addition, when the burner device is installed while the vehicle is stopped, the engine is in the idle region and the rotation speed is low, and the engine is used to operate the air pump that supplies air to the burner device. The problem was that a large air pump was required.

This invention was made in view of the above-mentioned conventional problems, and is applicable to an exhaust purification device having a filter member and a clogging removal means such as a burner device in the exhaust passage, when the engine is stopped in the idle region where the engine speed is low. Provided is an exhaust purification device for a diesel engine that eliminates problems such as dry grass burning and burns to passersby by not activating the clogging removal means at times, and that also allows the air pump to be made smaller. It is intended to.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an exhaust purification device for a diesel engine according to an embodiment of the present invention. In the figure, 1 is a diesel engine, 2 is an intake passage, and 3 is an exhaust passage. A filter member 4 is disposed in the middle of the exhaust passage 3 to collect fine particles such as carbon particles in the exhaust gas. This filter member 4 has honeycomb-shaped passages 4a and 4b formed therein, and one of the adjacent passages 4a and 4b has an opening on the terminal end side and the other opening on the starting end side closed by plugs 4c. has been done. Further, a pair of electrodes 5a, 5b are attached to the filter member 4, and the electrodes 5a, 5b are connected to a clogging detector 6, and the clogging detector 6 is connected to the electrodes 5a, 5b.
When the filter member 4 is energized, clogging of the filter member 4 is detected from the resistance value between the electrodes 5a and 5b.

Further, a burner device (clogging eliminating means) 7 is disposed on the upstream side of the filter member 4 of the exhaust passage 3, and the burner device 7 is equipped with a spark plug 8.
An ignition switch 9 is connected between the spark plug 8 and a power source (not shown). A fuel supply passage 10 and an air supply passage 11 are connected to the burner device 7, and a fuel pump 13 for pumping fuel in the fuel tank 12 to the burner device 7 is connected to the air supply passage 11 in the middle of the fuel supply passage 10.
An air pump 14 for supplying air to the burner device 7 is disposed in the middle of the burner device 7, respectively.

Further, in the figure, 15 is a stop detector that detects the stop state of the vehicle from the engine speed meter, etc.;
generates a drive signal to operate the burner device 7 while receiving the detection signal from the clogging detector 6;
This is a control circuit that stops generating the drive signal while receiving the detection signal from the stop detector 15.

FIG. 2 shows the circuit configuration of the above exhaust purification device,
In the figure, 6, 9, 13, 14, and 15 are the above-mentioned clogging detector, ignition switch, fuel pump, air pump, and stoppage detector. Also, the control circuit 16
, 17 is normally open and the clogging detector 6
This is a gate circuit that allows the detection signal of the stop detector 15 to pass through and is closed while receiving an inverted signal of the detection signal of the stop detector 15, and this gate circuit 17 stops the operation of the burner device 7 when the stop detector 15 detects a stop. Acts as a means for stopping the operation.

Next, the operation will be explained.

During operation of the engine 1, when exhaust gas containing fine particles such as carbon particles is discharged from the combustion chamber, this exhaust gas flows through the exhaust passage 3 and passes through the filter member 4.
Then, the filter member 4 enters a passage 4a which is open on the starting end side. Then these passages 4a
Since the opening on the terminal end side is closed, the exhaust gas passes through the side wall of the passage 4a and enters the adjacent passage 4.
b and is discharged from the filter member 4 through the terminal opening of the passage 4b. At this time, fine particles such as carbon particles in the exhaust gas are collected and removed by the side walls of the passage, thereby purifying the exhaust gas and releasing it into the atmosphere.

Further, if the filter member 4 is clogged with carbon particles collected while purifying the exhaust gas by burning carbon particles, the clogging detector 6 detects the electrode 5a. ，
It is detected from the resistance value between 5b that the filter member 4 is clogged, and a detection signal from the detector 6 is applied to drive circuits 18 to 20 via a gate circuit 17. Then, fuel pump 13 and air pump 1
4 is driven, the ignition switch 9 is turned on, the burner device 7 is activated, and the carbon particles in the filter member 4 are heated and burned.
This eliminates clogging of the filter member 4.

By the way, if the burner device 7 is operated to clear the clogging while the vehicle is stopped,
As mentioned above, there is a risk that the dry grass may catch fire and passersby may be burned, and there is a problem that the air pump 14 and the like become large. However, in this device, when the vehicle is stopped, the stop detector 15 detects that the vehicle is stopped from the speedometer of the engine 1, etc., and the gate circuit 17 detects the stop detector 1.
Since the drive circuits 18 to 20 are closed upon receiving the inverted signal of the detection signal No. 5, the drive circuits 18 to 20 do not receive the output from the clogging detector 6, and the burner device 7 does not operate. Therefore, with this device, the above-mentioned problems such as burning of dry grass and burns of passersby do not occur, and the air pump 14 and the like can be small.

In the above embodiment, the clogging of the filter member was detected using electrical resistance, but the clogging may also be detected from the pressure of exhaust gas, the amount of deposited particulates such as carbon particles, etc. Further, the clogging may be cleared not after the clogging is detected, but when the travel distance reaches a predetermined distance. Furthermore, the clogging eliminating means may be a heater device instead of a burner device.

As described above, according to the present invention, in an exhaust purification device having a clogging eliminating means such as a filter member and a burner device in the exhaust passage, the clogging eliminating means is not activated when the engine is stopped in the idle region where the engine speed is low. As a result, problems such as dry grass burning and passersby being burned can be eliminated, and air pumps and the like can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an exhaust purification device for a diesel engine according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of the device. DESCRIPTION OF SYMBOLS 1... Engine, 3... Exhaust passage, 4... Filter member, 7... Burner device (clogging eliminating means), 15... Stop detector (stop detecting means), 1
7...Gate circuit (operation stopping means).

Claims (1)

[Claims] 1. A filter member disposed in the exhaust passage of the engine to collect fine particles such as carbon particles in the exhaust gas, and a clogging eliminating means that heats the filter member to eliminate the clogging when the filter member becomes clogged. and a stop detection means for detecting a stop state of the vehicle, and an operation stopping means for stopping the operation of the clogging eliminating means when the stop detection means detects a stop and the engine is running. Diesel engine exhaust purification device.