JPS5970826A - Exhaust emission control device for diesel engine - Google Patents

Abstract

PURPOSE:To effectively raise the temperature of a reactor as well as to aim at a complete combustion of particle components, by throttling suction air in a specific cylinder and leading such exhaust gas as being raised in temperature and incresed in uncombustive components into the reactor, while bypassing the reactor to the exhaust gas in remaining cylinders. CONSTITUTION:When loading happens in a filter member 5, a control device 11 operates an on-off valve 7 and leads only the exhaust gas of a specific cylinder 1A into a reactor 4 by the help of an exhaust pressure sensor 12 and a temperature sensor 13, while throttles the quantity of suction air. As a result, in the reactor 4, the filter member 5 gets a temperature rise due to a rise in exhaust temperature and thereby reaction starting in an oxidation catalyzer is accelerated and simultaneously an increase in uncombustive components heightens the oxidation reaction of a catalyzer in consequence whereby reaction heat causes the temperature of the filter member 5 to go up further so that all sticking particles are removed in combustion. At this time, exhaust gas in those of remaining cylinders 1B-1D bypasses the reactor 4, reducing the flow rate of the reactor 4, thus a temperature rise in the filter member 5 takes place in an effective manner.

Description

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

Conventionally, in diesel engines, in order to prevent particulate components such as tarposi particles in exhaust gas from being released into the atmosphere, as shown in Japanese Patent Application Laid-open No. A filter member is disposed in the exhaust passage to collect the above-mentioned gas, a heater is provided upstream of the filter member, and a throttle valve is further provided in the intake passage to perform throttling to increase the exhaust temperature. An exhaust gas purification device for a diesel engine has been proposed in which a filter member is preheated and then particulate components collected on the filter member are burned and removed by a heater.

However, in the above proposed structure, when the temperature of the filter part is low, the temperature of the part of the filter part cannot be sufficiently raised by heating the heater alone, and particulate components cannot be burned and removed. Either the cylinder is closed and throttled to supplementally raise the exhaust temperature and preheat the filter components, or if throttle is applied to all cylinders, it will significantly reduce fj output and have a negative impact on drivability. In addition, since the amount of exhaust gas flowing through the filter components is large, there is a problem that the effect of increasing the temperature of the filter components is low.Moreover, the use of a heater or burner device has the disadvantage of reducing fuel efficiency.On the other hand, particulate matter An exhaust gas purification device is known in which an oxidation catalyst is attached to a filter member that collects components, and this has the advantage of lowering the combustion start temperature of particulate components. Combustion of particulate components is possible depending on the temperature and the reaction heat of the oxidation catalyst, but the exhaust gas temperature in diesel engines is originally low, so even if an oxidation catalyst is attached, the filter components will be damaged. The operating conditions of the IS engine are limited in order to reach the combustion start temperature, and there is a risk that the clogging will not be cleared reliably, resulting in low reliability.

In view of this point, the present invention provides a reactor equipped with a filter member for collecting particulate components in exhaust gas, and an oxidation catalyst integrated with the filter member or provided in the first stream of the filter member. in the exhaust passage, the first exhaust passage always guides the exhaust gas of a specific cylinder to the reactor, and the second exhaust passage leads the exhaust gas before residual gas to the reactor. an exhaust passage; and the second
A bypass passage that branches from the exhaust passage and bypasses the reactor, an on-off valve that opens and closes the bypass passage, a throttle valve provided in the intake passage of a specific cylinder, and a filter that opens and closes when a member of the filter becomes clogged or at a predetermined interval. To provide an exhaust gas purification device for a teasel engine, which is equipped with a control device that operates a valve to guide exhaust gas from the remaining cylinders to a bypass passage, and a control device that operates the throttle valve in the throttle direction, and has a heat source such as a heater. The purpose is to effectively raise the temperature of the filter member by 1 to effectively eliminate clogging of the filter member.

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

In the drawing, 1 is a multi-cylinder diesel engine, and 2 is a system for supplying air to each cylinder 1A to 1D of the engine 1.
(Intake passage 3 is for each cylinder 18 to 1 of the engine 1)
This is an exhaust passage that leads out exhaust gas from D. The exhaust passage 6 is provided with a reactor 4 in which an oxidation catalyst is coated with a filter member 5 for collecting particulate components such as carbon particles in the exhaust gas.

The filter member 5 of the reactor 4 is formed in a honeycomb shape from a porous material such as ceramic, and every other pore along the flow of exhaust gas is closed at one end, and one end is open. Exhaust gas flowing in through the pores passes through a porous, air-permeable partition wall and flows out from the open pores at the other end. The surface of the filter member 50 is coated with an oxidation catalyst made of noble metal or base metal.

The above-mentioned exhaust passage 6 is the upstream part of the reactor 4 or the first passage which always guides exhaust gas from a specific cylinder IA (first cylinder) to the reactor 4.
The exhaust passage 68 leads the exhaust residue from the remaining cylinders 1B to 7D (second to third cylinders) to the reactor 4! The first and second exhaust passages 3a and 3b meet upstream of the reactor 4.

Further, 6 is a bypass passage formed by branching from the second exhaust passage 3b and bypassing the reactor 4;
An on-off valve 7 for opening and closing the bypass passage 6 is disposed at a branching portion between the exhaust passage 6b and the bypass passage 6, and a throttle valve 8 is interposed in the branched intake passage 2d for the specific cylinder 1A in the intake passage 2. It is set up.

On the other hand, 9 is an exhaust gas recirculation passage that recirculates the exhaust gas from the opening/closing valve 7'1 of the second exhaust passage 6b to the branch intake passage 2a of the specific cylinder 1A. A reflux control valve 10 that opens and closes the passage 9 is interposed.

Furthermore, 11 is an on-off valve 7, a throttle valve 8, and a reflux control valve 1.
The control device 11 has an input number 7 and an exhaust passage 6 (upstream of the reactor 4).
A detection signal from the exhaust pressure sensor 12 that detects the exhaust pressure in the first exhaust passage 3a) and a detection signal from the temperature sensor 16 that detects the exhaust gas temperature are respectively input, and control is performed according to the detection signals.

The control device 11 inputs the detection signals of the exhaust pressure sensor 12 and the temperature sensor 16 in a specific operating state of the engine 1, and determines that a state in which the exhaust pressure becomes higher than a predetermined value is the occurrence of clogging. When the exhaust gas temperature, that is, the temperature of the reactor 4, is higher than a predetermined value, the temperature of the reactor 4 is increased in order to burn the particulate components in the reactor 4.

The control device 11 operates the on-off valve 7 to open the second exhaust passage 6b when the exhaust gas temperature is higher than a predetermined value due to clogging.
while closing the bypass passage 6 to open the remaining cylinders 1B to 1D.
The exhaust gas is led to bypass passage B, and reactor 4 has a
Only the exhaust gas from the exhaust passage 3a is introduced, and the throttle valve 8 of the branched intake passage 2a is operated in the throttle direction to reduce the intake air amount of the specific cylinder 1A, and at the same time,
The joint valves 7 and 8 open the recirculation control valve 1U of the exhaust gas recirculation passage 9 to recirculate part of the exhaust gas to the branch intake passage 2a.
．． It is configured to output drive signals to ten actuators.

To explain the operation of the above embodiment, when the filter member 5 of the reactor 4 is clogged, the exhaust pressure sensor 12 detects the clog, and the temperature detected by the temperature sensor 16 is lower than a predetermined value. When high, the control device 11
Only the exhaust gas from the specific cylinder 7A is guided to the reactor 4 by the operation of the on-off valve 7, and the amount of intake air for this specific cylinder 1A is throttled. As a result, the temperature of the exhaust gas from the specific cylinder 1A increases, and at the same time, the amount of unburned components such as HC and Co increases. Further, by opening the recirculation control valve 10, the exhaust gas is recirculated to the specific cylinder 1A, and the amount of unburned components discharged further increases due to a decrease in combustibility.

Therefore, in the reactor 4, the temperature of the filter member 5 rises due to the rise in exhaust gas temperature, and the reaction start time of the oxidation catalyst becomes earlier, and the oxidation reaction of the catalyst increases due to the increase in unburned components, and the reaction heat increases the temperature of the filter member 5. Further, the temperature of the filter member 5 rises, and particulate components adhering to the filter member 5 are burned and removed.

At this time, since the exhaust gas from the remaining cylinders 1B to 1D is bypassed, the flow rate of the exhaust gas flowing through the reactor 4 is small, and the filter member 5 is effectively loaded.

In this way, when the filter member 5 loses its strength and the exhaust pressure decreases, the throttle valve 8 is opened to increase the amount of intake air to the normal state, while the reflux control valve 10 is closed to exhaust the air. Stop the gas reflux, close the on-off valve 7, introduce the exhaust residue from the remaining cylinders 1B to 1D into the reactor 4, collect the particulate components again, and if the clogging occurs, do the same as above. Remove clogging.

The present invention is not limited to the structure of the above embodiment, but includes various modifications. 1j In other words, as the filter member 5 of the reactor 4, a wide area wire mesh may be used instead of porous ceramic, and as a catalyst, in addition to a catalyst integrally coated on the filter member 5, a filter member 5 may be used. A catalyst formed in the shape of a metal wire may be disposed upstream of the member 5.

Further, in addition to using the exhaust pressure sensor 12 described above, the clogging state may be detected by providing an electric pot in the filter member 5 and detecting the change in resistance value due to adhesion of carbon particles or the like. Furthermore, without detecting the actual clogging state of the filter particles 5, the clogging removal operation may be performed at predetermined intervals based on the cumulative operation time or travel distance.

On the other hand, the temperature sensor 16 is [air temperature f! :In addition to the detection, the temperature of the filter of the reactor 4 may also be detected; however, this temperature sensor 16 is not essential. It is also possible to detect clogging and perform the one-sided clogging operation. Also, the exhaust recirculation passage? This is also essential, and when used in combination, it increases the amount of unburned components, increases the oxidation reaction in reactor 4, and increases the reaction temperature more reliably. When the problem is resolved, the output is reduced by restricting the intake air to the specific cylinder 1, but in response to this, the output may be recovered by increasing the fuel injection amount, advancing the injection timing, etc. In response to vibrations caused by torque fluctuations, vibrations may be suppressed by increasing the mass of the flywheel using a known automatic flywheel.

As explained above, according to the present invention, when a filter member is clogged or at a predetermined interval, the temperature of the intake air of a specific cylinder is increased by 1, the exhaust temperature is increased by 1, and the unburned components are increased. While introducing the exhaust gas into the reactor, the remaining cylinder JJ
By bypassing the reactor and allowing the gas to flow, it is possible to effectively raise the temperature of the reactor by 1'', ensure the combustion and removal of particulate components, and increase fuel consumption over a long period of time without reducing fuel efficiency. Good fS suppresses emission of particulate components over a period of time.
○ Has the advantage of being able to control

[Brief explanation of the drawing]

The drawing is a schematic diagram of a tea cell system having a 4JV gas purification device in an embodiment of the present invention.
It is. 1... Teasel engine, 1 person... Specific cylinder,
1B~1D...Remaining cylinders, 2...Intake passage, 2a
...Branch intake passage, 6...Exhaust passage, 6a...
・First exhaust passage, 3b..., second exhaust passage, 4...
...Reactor, 5...Filter member, 6...
・Bypass passage, 7... Opening/closing valve, 8... Throttle valve, 1
1... Warashi device, 12... Exhaust pressure secisor

Claims (1)

[Claims] (1) A diesel engine equipped with a reactor in the exhaust passage that includes a filter member that collects particulate components in exhaust gas and an oxidation catalyst that is integrated with the filter member or provided upstream of the filter member. In an exhaust gas purification device, a first exhaust passage constantly guides exhaust gas of a specific cylinder to a reactor, a second exhaust passage guides exhaust gas of remaining cylinders to the reactor, and a reactor branched from the second exhaust passage. a bypass passage that bypasses the bypass passage, an on-off valve that opens and closes the bypass passage, and a throttle valve provided in the intake passage of a specific cylinder, and when a filter member becomes clogged or at predetermined intervals, the on-off valve is activated to open and close the bypass passage. An exhaust gas purification device for a diesel engine, comprising a control device that guides exhaust gas to a bypass passage and operates the throttle valve in a throttle direction.