JPS6043113A - Device for purifying exhaust gas from diesel engine - Google Patents

Abstract

PURPOSE:To obtain the titled device in which the system is compact and the cost is inexpensive by providing a filter for arresting Diesel particulates at the downstream of a catalyst converter provided with HC control means. CONSTITUTION:In a case where the exhaust air pressure within exhaust pipes 6 and 7 reaches a predetermined value or more, the regeneration of a filter 4 is necessary. Therefore, a throttle valve 2 is closed in a certain quantity to generate HC and supply HC to the catalyst converter. The temperature of exhaust air becomes increased by the reaction heat generated in the catalyst converter, and the Diesel particulates arrested by the filter 4 are burnt. In a case when the temperature of exhaust air does not reach a value required for burning the particulates, the throttle valve 2 is further closed and a large quantity of HC is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for purifying exhaust gas from a Tee Cell engine, and in particular to a device for purifying Tee Cell Hatice 17-1. This invention relates to a type of purification device equipped with a filter for collecting water.

Diesel particulates contained in the exhaust gas of the Tee Cell engine, especially in the flue gas, are fine particles whose main components are unresolved Hc. It is burned, rendered harmless, and released into the atmosphere. However, although the exhaust gas temperature reaches 600° C. or more, it is usually during high-speed driving, and therefore, during medium-low speed driving, the exhaust gas is emitted into the atmosphere without being combusted, polluting the atmosphere. For this reason, recent tea cell engines are equipped with a filter to collect the tea cell hatty key rate. This filter is made of ceramic fibers or metal fibers, and after traveling a certain distance, it becomes clogged with collected diesel particulate matter. For this reason, several techniques have been proposed to purify and regenerate the filter by periodically or by detecting this clogging and burning the collected tea-cervaticulate.

One method is to raise the exhaust gas temperature by providing a throttle valve in the intake pipe of the engine to throttle the intake air, since diesel particulate burns at an exhaust gas temperature of 600° C. or higher, as described above. This method is simple, but unlike gasoline engines, where the throttle valve is completely closed, diesel engines have excess air ratios of 13 or less and produce a large amount of smoke. It can only be used under certain conditions, and its effectiveness is insufficient. Another method is to provide a burner combustion system independent of the exhaust system upstream of the filter, supply fuel and air to this burner as appropriate, and burn the diesel particulates collected by the filter. Although this system is independent and can be used under any operating conditions, it has the disadvantage that the system is complicated and costs are high. Another known method is to attach an electric heater to the filter and heat and burn the diesel particulate, but this method consumes too much power and is not suitable for practical use.

In addition to this, the diesel exhaust gas purification system has a diesel particulate filter and catalytic converter integrated, that is, a diesel particulate filter and a catalytic converter.
Products in which catalytically active components such as T and Pd are calcined are also known. However, in the case of a diesel engine, the s02 in the exhaust gas is changed into SOx by the oxidizing action of the catalyst, and finally becomes H2SO4, which reduces the effectiveness of the catalyst by half. This Saltu-1・
is collected along with the particulate matter rate in the particulate measuring filter in the exhaust gas test method, so in certain operating ranges, the apparent particulate matter rate may actually increase.

An object of the present invention is to provide an improved exhaust gas purification device using a diesel particulate filter.

In the exhaust gas purification device according to the present invention, a catalytic converter as a heat source is provided on the second-stream side of the engine exhaust system, and a diesel particulate filter is provided downstream of the catalytic converter. By supplying a large amount of HC to this catalyst condenser, an oxidation reaction is actively generated to generate heat, and the tea cell particulates collected in the t-refilter are combusted by this heat. The means for supplying a large amount of HC to the catalytic converter is, for example, an intake throttle, a large retardation device, or a combination thereof.

In a preferred embodiment of the invention, a first bypass with a switching valve leading from upstream to downstream of the catalytic converter and a second bypass with switching valve leading from upstream of the catalytic converter to downstream of the filter are provided. . During normal operation, the particulate rate is collected by the filter, and when regenerating the filter, it is passed through the catalytic converter and filter without using the bypass, and when the accelerator is fully opened or when the emergency engine is activated. In this case, the load on the exhaust system is removed through the second bypass to prevent a drop in output or damage to the system.

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 depicts the basic concept of the invention as a block diagram. (The whole is included with engine 1)
(The Hc control device 2 consists of a C control device 2, a catalytic converter 3, a diesel particulate filter 4, a muffler 5, and exhaust pipes 6, 7.8 that connect these.
Any device may be used as long as it can supply a large amount of HC to the engine, for example, as disclosed in the patent application ``Diesel Engine Exhaust Gas Purification Device'' filed by the applicant on August 3, 1981. Intake throttle size or special request
8= A wide retardation device as disclosed in No. 128781 or a combination thereof may be used. The catalytic converter 3 is preferably a carrier made of a noble metal catalyst having good activity against HC, such as Pt, Pd, Rw, Rh, etc., and the carrier is oats for gasoline engines.

Channel monolith or pellet, cut or te.

Since the main purpose is to react to HC, any shape may be used, such as ceramic fluoroum, wire mesh, wall flow monolith, etc. for easel engines. The diesel particulate filter 4 is optimally a wall flow monolith type for collecting diesel particulates, but may also be a ceramic parrot type or a wire mesh type. Muffler 5
and exhaust pipe 6. 'i, 8 is commonly used.

The regeneration of the particulate filter 4 may be carried out periodically every certain travel distance when the filter 4 becomes clogged, but the exhaust pipe 6 on the upstream side of the filter 4 may be regenerated.
Or, by detecting the exhaust gas pressure etc. in the filter 7, it is detected that the filter 4 has become clogged.
These signals may operate the HC' control device 2 to supply a large amount of HC to the catalytic converter 3.

In the catalytic converter 3, the catalyst promotes the oxidation of HC to increase the temperature of the exhaust gas, and burns the waste gas collected by the filter 4. Therefore, it should be noted that the catalytic converter 3 in this invention is mainly used as a heat source for burning diesel particulates. Further, depending on the case, another catalytic converter may be provided upstream of the catalytic converter 3 to preheat the catalytic converter 3.

If the filter 4 becomes clogged, the exhaust gas pressure in the exhaust pipe will increase and the output will decrease. Therefore, as a safety measure to prevent damage to the system during full throttle acceleration, as shown in Figure 2, from the engine 1 Exhaust pipe 6 leading to catalytic converter 3
It is preferable to provide a bypass 11 that communicates with another muffler 10 via a switching valve 9 in the middle of the muffler 10 . In this way, the catalyst connector (
- Since filter 3 and filter 4 can be bypassed,
It is possible to prevent a decrease in output during acceleration with the accelerator fully open, and it is also possible to prevent damage to the device due to an increase in exhaust pressure exceeding the limit. In the case of this system, the system can be further simplified by connecting the outlet of the bypass 11 to the middle of the exhaust pipe 8 leading from the filter 4 to the muffler 5, as shown by the broken line, instead of providing a separate muffler 10.

In addition, as shown in Figure 3, the ・ζ path 1 from the switching valve 9
1) If the outlet is connected in the middle of the exhaust pipe 7 leading from the catalytic converter 3 to the fill 4, and the catalytic converter 3 is bypassed during normal operation, adverse effects such as deterioration of the catalyst and generation of sulfate by the catalyst can be avoided. can be prevented.

Furthermore, as shown in FIG.
It is even better to branch into a bypass 11α and a second muffler 11/l that communicates with another muffler 10 via a second switching valve 12. In this way, during normal operation, the exhaust gas from the engine 1 is passed through the first bypass lla and the tea cell particulate rate is collected by the filter 4, and when the filter 4 is regenerated, the bypass 1] is not used. Particulate matter] is combusted through a regular combustion route leading from the catalytic converter 3 to the filter 4, and during acceleration with the accelerator fully open or in the event of system abnormality, a decrease in output or damage to the system is prevented through the second bypass 11b. Also in the case of this system, if the outlet of the second bypass IIJ is connected to the exhaust pipe 8, the installation of a separate muffler 10 is omitted. Further, another switching valve may be provided at the connection between the bypass lla and the exhaust pipe 7 so that the exhaust gas flows back into the catalytic converter 3 during the bypass.

FIG. 5 shows an embodiment of the present invention embodying the concept shown in FIG. A throttle valve 2 serving as Hc control means is rotatably provided in the intake pipe 14 downstream of the air cleaner 13 of the engine 1.
It is connected to a diaphragm 15 that operates by adjusting the vacuum pressure by a not-shown teat solenoid.

In the middle of the exhaust pipe 6 leading from the engine 1 to the catalytic converter 3, there is connected an exhaust pipe 11 whose inlet is opened and closed by a first switching valve 9, and the first switching valve 9 is operated by a solenoid valve (not shown). It is connected to a diaphragm 16 whose vacuum pressure is controlled.ノ(ino(s11ba)
A first bypass 1 is branched from the intermediate part and connected to an exhaust pipe 7 leading from the catalyst conduit 3 to the filter 4.
1a, and a second pipe 11h, which is connected to the exhaust pipe 8 leading from the filler 4 to the muffler 5, and a second switching valve 12 is provided at the branch part thereof. This switching valve 12 is connected to a membrane diaphragm 17 whose vacuum pressure is controlled by a solenoid valve (not shown).

In this embodiment, the catalytic converter 3 is a wire mesh tights.

The filter 4 is of a wall flow monolith type.

The timing for regeneration of the TAYSEL particulate film 4 is as follows.
It is determined by the control unit of the engine electronic control system based on the signal from the pressure sensor that detects the exhaust gas pressure in the exhaust pipe 6 or 7. As mentioned above, this signal is determined by the tachometer or the odometer. The signal may also be used. Also, the throttle valve 2 and the first. Second
The switching valve 9.120 control is based on signals from the sensor that detects the pressure and temperature of the exhaust gas in the exhaust pipe 6 or 7 and the sensor that detects the accelerator opening. This is done by control signals. That is, when the exhaust pressure in the exhaust pipes 6 and 7 exceeds a certain value, the filter 4 needs to be regenerated, so the throttle valve 2 is closed by a certain amount to generate HC and send it to the catalytic converter 3. The exhaust temperature is increased by the reaction heat and the diesel particulate rate collected in the filter 4 is combusted. However, if the exhaust temperature is not higher than necessary for combustion of the particulate rate, the throttle valve 2 is further closed. generates a large amount of HC. Also, at this time, when I reached a steep slope and tried to overtake, I fully opened the arc cell,
1st. The second switching valve 9.12 is operated to close the combustion route and open the bypass 11h to prevent a decrease in output.

Since the catalytic converter 3 and the filter 4 have almost the same shape, the system can be made more compact by integrating them into a single case 18 via the insulating mantle 19 as shown in FIG. Become a kuto. Of course] When installing a slotted bus between the catalyst inverter 3 and filter 4,
Connect the pipe for pass to the lace part between the two.

As described above, according to the diesel exhaust gas purification device of the present invention, the catalytic converter and the diesel particulate rate collecting film are separated, and the catalytic converter is used as a heat source during filter regeneration. Since it is used as a catalytic converter, it is possible to reduce the size and capacity of the catalytic converter to reduce costs, and to minimize the negative effects of the catalyst such as the production of sulfate. Moreover, even if sulfate is produced, it can be collected because the filter is placed in the latter stage, and the adverse effects of the catalyst can be completely prevented.

However, if a bypass is provided to bypass the catalytic converter, exhaust gas can be passed through the catalytic converter only during filter regeneration, thereby preventing deterioration of the catalytic converter and preventing the generation of sulfate. can. Furthermore, by providing a bypass that can bypass both the catalytic converter and the filter, it is possible to prevent damage to the system due to a decrease in output and a dangerous increase in exhaust pressure during acceleration with the accelerator pedal fully opened, or dangers due to abnormal situations in the system. In addition, compared to other exhaust gas purification devices, it is superior in terms of reliability, durability, stability, price, etc.
When combined with the prior art by the applicant mentioned above, even more precise control becomes possible, and the filter can be regenerated under any operating conditions of the engine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic concept of the diesel exhaust gas purification device according to the present invention, FIGS. 2 to 4 are block diagrams showing the development of the basic concept shown in FIG. 1, and FIG. Fig. 6 is a schematic sectional view of a diesel particulate filter integrated with a catalytic converter used in an embodiment of the invention.

Claims (1)

[Scope of Claims] 1. A filter for collecting diesel particulates provided in the middle of an exhaust pipe from the engine to the muffler; A catalytic converter with high activity against HC provided on the upstream side of the exhaust pipe of the filter; A diesel exhaust gas purification device comprising HC control means 7 capable of supplying a large amount of HC to the catalytic converter. 2.' Claim 1, wherein a bypass with a switching valve is provided in the exhaust pipe so that exhaust gas from the engine can selectively bypass the catalytic converter or the catalytic converter and the filter. TASEL exhaust gas purification device. 3. The diesel engine according to claim 1, wherein the HC control means is an intake throttle device provided in the intake pipe of the engine or a wide retard device for significantly delaying the fuel injection timing. Exhaust gas purification device. 4. The diesel exhaust gas purification device according to claim 1, wherein the catalytic converter and the filter are held within a single case.