JPS6361489B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention uses a filter to collect fine particles mainly composed of carbon in the exhaust gas of a diesel engine.
The present invention also relates to an exhaust gas treatment device for a diesel engine that can purify exhaust gas through combustion treatment.

Conventionally, exhaust gas treatment equipment has been used that uses particulate filters to collect particulates in the exhaust gas. It was uneconomical because it had to be replaced.

Therefore, two filters made of heat-resistant material are equipped with a valve that can switch the flow of exhaust gas to these two filters. An invention disclosed in Japanese Patent Application Laid-open No. 79209/1983 has been made in which the filter is used to alternately burn the collected particles.

That is, to explain the above invention with reference to the schematic side sectional view of FIG. The carbon particles in the exhaust gas E are collected.

In addition, by opening and closing the valve at the rear of the shaft of the switching valve 1, high-temperature gas B containing residual air from burner combustion flows into the other filter 2B side from the flame port 3, removing fine particles such as carbon that were previously collected by the filter 2B. Oxidized combustion is performed, and the particulate combustion gas G is combined with the exhaust gas E from the filter 2A at the rear of the filter 2B.
By discharging it, clean exhaust gas E _c can be obtained.

As described above, the collection of particulates by the two filters 2A, 2B, whose inlet sides are partitioned by the partition wall 6, and the combustion of the collected particulates are performed alternately by switching the switching valve 1, and the filters 2A, 2B The collection and combustion are carried out alternately, and the carbon particulates of the exhaust gas E of the diesel engine are removed to form a clean exhaust gas _Ec , which is discharged to the outside from the exhaust outlet portion 5 as shown by the arrow.

However, if an exhaust pipe, a muffler, etc. (not shown) are installed after the merging section 4 and exhaust outlet section 5 on the outlet side of each of the filters 2A and 2B on the right side of FIG. 1, the exhaust resistance increases and the exhaust pressure rises.

This increase in exhaust pressure changes in relation to the engine speed and load, and this change in exhaust pressure causes a change in the exhaust pressure of the burner combustor, which reduces the amount of air blown by the blower of the Bart combustor. Burner combustion itself deteriorates, and the amount of residual air decreases, and in some cases, carbon is generated in the burner flame, which should be incinerated by filter 2B, but instead burns by filter 2B.
This may cause the filter 2B to become clogged.
Due to excessive clogging, excessive exhaust pressure is applied to the diesel engine, causing a drop in output and promoting the generation of black smoke.
On the contrary, it may promote carbon generation, and the exhaust gas treatment device itself may become a source of abnormality.

On the other hand, similar to the above, Japanese Patent Application Laid-open No. 54 (1983) relates to a diesel engine exhaust gas purifier that collects and processes carbon and other particulates in diesel engine exhaust gas E.
- In the invention of No. 111010, two air-fuel atomizing nozzles and ignition means are required between the converter valve and the two filter members, and the combustion products of the filter during combustion are discharged. There is a problem in that a large fan is required to do this, and the resistance increases accordingly.

Furthermore, the inside of the trapper container provided in the exhaust system of the internal combustion engine is divided into two parts, left and right, and a trapper is placed in each of them, and each trapper can be heated by a heater means, and a trapper is placed in front of these trappers. , Exhaust gas particulate collection in which a plate switching valve is arranged to open one trapper and close the other, and the plate switching valve has a hole that allows a controlled amount of exhaust gas to pass through. An invention related to the device is disclosed in Japanese Patent Application Laid-Open No. 59-92318.

However, the present invention is directed to a case where the amount of air required for combustion in the cylinder is excessive with respect to the amount of fuel, such as when the internal combustion engine has a rated output or less.

In other words, carbon is collected when there is sufficient residual air left in the exhaust gas of the internal combustion engine, and the residual air in the exhaust gas closes the plate material switching valve, and the exhaust gas is released from the hole in the plate material switching valve as carbon combustion air. A small amount of gas is passed through and heated by a heater to promote combustion.

Generally, at the rated output of a diesel engine, the air-fuel ratio is 1.5 to 1.6 times the theoretical air required for fuel combustion, so the above method is possible.

However, in high-output diesel engines that increase air usage efficiency in the combustion chamber, the theoretical air
The air-fuel ratio becomes 1.4 times or less, and there is no exhaust gas with excess air that re-burns the carbon in the filter.The lower the air-fuel ratio, the more carbon is generated, and that carbon is collected in the filter. In addition, the incineration power decreases, the resistance of the filter increases, and the diesel engine is subjected to exhaust braking action, creating a vicious cycle in which more and more carbon is generated.

On the other hand, although not shown in FIG. 1, the combustor for causing the high temperature gas B to flow through the burner flame port 3 into the filter 2A or 2B that has collected carbon in the exhaust gas E is usually a motor. A burner with a driven fan for sucking fresh air, a fuel inlet pipe, and a spark plug is used, but when incinerating the above-mentioned particulates, the temperature of the incineration air is raised from 500°C to 800°C using the burner flame or an electric heater. Since the new air is outside air, extra fuel is consumed to raise the temperature of the air itself, which increases the fuel consumption of the diesel engine as a whole.

Furthermore, in this type of exhaust gas treatment device,
It is known, for example, as disclosed in Japanese Utility Model Publication No. 52-6726, to improve the efficiency of the entire exhaust gas treatment device by providing a heat exchanger on the downstream side of the exhaust gas combustion chamber to preheat the combustion air. However, these devices usually include an air pump for combustion air.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and provides an exhaust gas treatment device that removes particulates from the exhaust gas of a diesel engine and discharges it as clean exhaust gas. The purpose is to improve the combustibility of particulates collected in a gas processing device and to reduce the amount of fuel consumed for combustion of the particulates.

That is, the diesel engine exhaust gas treatment device of the present invention includes two filters for collecting particulates disposed in the exhaust gas passage of the diesel engine, and collects particulates while passing the exhaust gas through one of the two filters. In an exhaust gas treatment device for a diesel engine that can alternately switch between collecting particulate matter and burning the collected particulates, the downstream side of each of these two filters has two filters each having a constriction part at the outlet. A variable plate for ejector effect is formed in the divided chamber and has the effect of sucking out particulate combustion gas from the other outlet by exhaust gas after collecting particulates discharged from one outlet, and is provided at the outlet of the two divided chambers, The case of the two divided chambers on the downstream side of each filter is
forming a double-walled case that can preheat fresh air and introduce the heated air into a particulate combustion combustor;
Furthermore, it is constructed by providing a catalyst in the combustor.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, and the same parts are indicated by the same part numbers in the parts shown in the conventional example in FIG. 1 and the parts shown in each of the drawings below.

First, the embodiment of the present invention shown in FIG. 2 shows an exhaust gas treatment device installed in the exhaust gas passage of a diesel engine, similar to the conventional example shown in FIG. Two filters 2 for collecting particulates in the exhaust gas E via a valve 1
A and 2B are arranged, and the switching valve 1 allows the exhaust gas E to pass through one filter 2A to collect particulates as shown in the figure, and the particulates collected by the other filter 2A to be sent to the flame port. This constitutes an exhaust gas treatment device that can alternately switch between incineration operations using high-temperature gas B from three sources.

Therefore, in the present invention, the portion on the downstream side of each of the filters 2A, 2B, which was the merging portion 4 in the conventional example shown in FIG. Further, an ejector effect variable plate 9 rotatable by a rotary shaft 8 is provided at the outlet thereof.

In the exhaust gas treatment device having the above configuration, while the filter 2A is collecting particulates, a large amount of exhaust gas E from the diesel engine flows out of the lower surface of the ejector effect variable plate 9, and the rear exhaust pipe 1
In this case, the ejector effect variable plate 9 is pushed upward in proportion to the amount of gas passing through the filter 2A, and the ejector effect variable plate 9 incinerates the particulates from the filter 2B. The gas G is sucked out by the exhaust gas E after passing through the filter 2A.

That is, due to the ejector effect caused by overcoming the resistance from the rear exhaust pipe 10 etc. and flowing out of the exhaust gas E from the filter 2A, the rear chamber of the filter 2B becomes a negative pressure, which does not adversely affect burner combustion.
The larger the amount of exhaust gas passing through the filter 2A, the greater the suction effect, which increases the amount of residual air and improves the combustion of carbon particles in the filter 2B.

On the other hand, when the exhaust gas E of the diesel engine is passing through the filter 2B, the ejector effect variable plate 9 is pushed downward in FIG. 2 and stops at a balanced position, causing particulate combustion from the filter 2A. Gas G will be sucked out.

In the above embodiment, the ejector effect variable plate 9 is rotatably attached to the rotating shaft 8 and is moved by the flow of exhaust gas E from the filter 2A or 2B. Attach a lever to the outside of 8, and attach the tip of the lever to 2.
It is also possible to balance the lever to a neutral position using a spring or the like, and the rotation angle of the lever may be adjusted to
It may be automatically adjusted via a variable piston or the like that operates in conjunction with the pressure from the rear chambers A and 2B.

Next, as shown in FIG.
A double wall case 16 is formed as a case for each of the two downstream divided chambers of B, and new air A is introduced between the walls of this double wall case 16 and preheated with exhaust gas E and particulate combustion gas G, An air pipe 11 is provided so as to introduce the heated air Ah into a combustor 15 for particulate incineration, as shown in the side sectional view shown in FIG. 3 and the plan view shown in FIG. 4.

This combustor 15 is provided with a primary ignition plug 14, a fuel valve 13 for injecting fuel, and a catalyst 12, and is preheated in a double-walled case 16 by fuel injection from the fuel valve 13 and ignition of the primary ignition plug 14. heated air
A particulate incineration flame resulting from catalytic combustion using Ah is supplied to the filter 2A or 2B via an incineration flame switching valve 17.

As a result, after the preheated heated air Ah is primarily ignited during the air flow, the high temperature gas B containing excess air is transferred to the filter 2 through continuous combustion by the catalyst 12.
A or 2B can be supplied to incinerate fine particles such as carbon.

Therefore, in a diesel engine to which the exhaust gas treatment device of the present invention is applied, when two filters are used alternately to perform exhaust gas treatment, particulate combustion gas in the exhaust gas discharged from one filter is mixed with the other filter. The exhaust gas from the filter is sucked out by the ejector effect, and the combustion of particulates is improved, so the filter is less clogged, and as a result, the output is maintained at a good level, and the exhaust gas cleaning effect is maintained. I can do it.

In particular, in the present invention, a catalyst is provided in the combustor for particulate combustion, and new preheated air is introduced into the combustor from the double-walled case, so once catalytic combustion has started, the continuous reaction causes combustion. Compared to conventional burner combustors, the range of air-fuel ratios that can be used is expanded, and the combustor itself has the advantage of producing clean combustion gas with excess air that does not generate carbon.

In addition, since preheated fresh air is introduced into the combustor from the double-walled case, the amount of fuel used in the combustor is reduced and the temperature of excess air during combustion of the filter is increased. combustion time is significantly reduced.

Therefore, it is possible to burn particulates in a short period of time, making it possible to reduce the size of the filter for collecting particulates in the exhaust gas from a diesel engine, and to change the filter in a short period of time, thereby reducing the size of expensive filters. It also has the advantage of being able to reduce costs by reducing the size of the device, making the device more compact, and lowering costs.

[Brief explanation of drawings]

FIG. 1 is a plan sectional view of a conventional exhaust gas treatment device for a diesel engine, FIG. 2 is a plan sectional view of an exhaust gas treatment device for a diesel engine according to an embodiment of the present invention, and FIG. 3 is a side sectional view of FIG. 2. FIG. 4 is a plan view of FIG. 2. DESCRIPTION OF SYMBOLS 1...Switching valve, 2A, 2B...Filter, 3...Flare port, 6...Partition wall, 7...Partition wall, 8...Rotating shaft, 9...
Variable plate for ejector effect, 11...Air piping, 12...
Catalyst, 14...Primary ignition plug, 15...Combustor, 16...
Double wall case, E...Exhaust gas, G...Particulate combustion gas, A...New air.

Claims (1)

[Claims] 1. Two filters for collecting particulates are arranged in the exhaust gas passage of a diesel engine, and particulates are collected while passing the exhaust gas through one of the two filters, and the particulates collected by the other filter are collected. In an exhaust gas treatment device for a diesel engine that can alternately switch the combustion operation, each of the downstream sides of these two filters is formed into two divided chambers each having a constriction part at the outlet, and the exhaust gas is discharged from one outlet. A variable plate for ejector effect having the effect of sucking out the other particulate combustion gas by the exhaust gas after collecting particulates is provided at the outlet of the two divided chambers, and the case of each of the two divided chambers on the downstream side of each of the filters is is formed into a double-walled case capable of preheating fresh air and introducing the heated air into a combustor for particulate combustion;
An exhaust gas treatment device for a diesel engine, characterized in that the combustor is provided with a catalyst.