JPH05195750A - Soot removing device for exhaust gas of diesel engine - Google Patents

Abstract

PURPOSE:To easily separate and discharge a great deal of soot contained in exhaust gas of a diesel engine. CONSTITUTION:The exhaust gas from a engine flows into an outer cyclone 3 from an exhaust gas inlet 5 and swirls. Then the exhaust gas passes through a gap S, gap T, and communication path 17 to flow into an inner cyclone 11 and swirls. Further the gas therefrom is passed through an exhaust pipe 21, exhaust chamber 19 inner chamber 19a, and discharge port 23 and flows out. The soot drops off into the cyclones 3, 11 owing to the centrifugal force generated by the swirl motions in the outer and inner cyclones 3, 11 and is accumulated on a soot holding member 25 and retained thereby. The external air led from an outer air inlet 7 intensifies the centrifugal force of the exhaust gas, cools it, and enhances the soot separating efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for removing heavy pollutants such as tar and soot contained in the exhaust gas of a diesel engine.

[0002]

2. Description of the Related Art Since environmental problems have been severely questioned, exhaust gas regulations of vehicles have become a major social problem. In particular, the tar and soot emitted by diesel engine cars, which have been loosely regulated, have reached an unbearable situation.

Pollutants such as tar and soot are the most conspicuous, and they are experienced from the black smoke scattered by large trucks or the trees on the median strips of highways, so no special explanation is required. With respect to passenger cars with gasoline engines, it has been 25 years since the emission regulations were implemented, and various measures have been taken. As a countermeasure against these problems, it is well known that not only the exhaust gas is treated but also the combustion method of the engine itself is improved to restart the engine as a clean engine.

[0004]

In the meantime, similar demands have been made in diesel engine vehicles such as trucks, but in diesel engines that use light oil as the main fuel,
It is difficult to deal with it only by improving the combustion state, and the present condition is that combustion residues such as tar and soot are emitted while being contained in the exhaust gas.

An electrostatic precipitator installed in the exhaust pipe of a diesel engine to adsorb these combustion residues has also been proposed. However, when a 10-ton car travels 1 million km, 0.9 ton of soot dust is generated, so the electrode of the electrostatic precipitator becomes unusable due to the accumulation of soot dust in an extremely short time.
It was not practical because the electrodes were not easy to clean.

Therefore, the present invention is intended to solve the above problems by facilitating the separation and removal of a large amount of soot and dust contained in this type of exhaust gas.

[0007]

In order to achieve the above object, the present invention has the following constitution. That is, the soot-dust removing device for exhaust gas of a diesel engine according to claim 1 is a cyclone-type soot-removing device provided in an exhaust gas flow path of a diesel engine, and is removable at a portion where the soot-dust is accumulated in the cyclone. It is characterized in that a dust container is arranged.

Further, a soot / dust removing device for exhaust gas of a diesel engine according to a second aspect is a cyclone-type soot removing device provided in an exhaust gas passage of a diesel engine, and introduces an outside air together with an exhaust gas introducing port into the cyclone. It is characterized by having a mouth. Further, as illustrated in FIG. 5, the device for removing dust from exhaust gas of a diesel engine according to claim 3 further includes a rotational speed of the diesel engine,
An operating state detecting means for detecting at least one of the intake air amount and the exhaust air amount, and an outside air introduction amount control means for increasing the outside air introduction amount as the detection value detected by the operating state detecting means becomes lower are provided. And

[0009]

According to the first aspect of the present invention, due to the action of the cyclone, soot and dust can be easily separated and removed from the exhaust gas by the centrifugal force, and a large amount can be accumulated in the cyclone, and the soot dust can be stored in the accumulating portion. By arranging the container, accumulated dust can be easily removed only by removing the dust container.

The invention according to claim 2 is provided with an outside air introduction port as well as an exhaust gas introduction port into the cyclone. As a result, the rotation speed in the cyclone is increased, and the separation and removal of soot dust becomes more complete due to the large centrifugal force. Further, since the exhaust gas is cooled by the outside air, the aggregating component such as tar in the high-temperature exhaust gas becomes liquid or solid, and the specific gravity difference with the gas becomes large, so that it can be sufficiently separated in the cyclone. Therefore, the exhaust gas can be further purified.

According to the third aspect of the invention, the outside air introduction amount control means increases the outside air introduction amount as the rotational speed of the diesel engine, the intake air amount, or the exhaust gas amount decreases. In the region where the exhaust gas amount is large, such as when the rotation speed of the diesel engine is high, the exhaust gas alone is sufficient for rotation in the cyclone and the separation effect is sufficient.

If the cross section of the flow path through which the exhaust gas should pass is the same, the obtained flow velocity decreases in proportion to the amount of exhaust gas, and the centrifugal force of the exhaust gas decreases in proportion to the square of this flow velocity. For this reason, in a region where the exhaust gas amount is low, such as when the rotation speed of the diesel engine is low, rotation of the cyclone in the cyclone is insufficient with only the exhaust gas, and the soot and dust cannot be sufficiently separated. Therefore,
The outside air introduction amount control means increases the outside air introduction amount as the rotational speed, the exhaust gas amount, or the intake air amount of the diesel engine decreases. As a result, a sufficient separation effect can be exhibited in all operating conditions of the diesel engine.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. The present invention is not limited to these. As shown in FIG. 1, the soot-dust removing device 1 of the present embodiment is a cyclone-type device that uses a so-called cyclone to capture combustion residual substances such as soot in the exhaust gas of a diesel engine.

First, the structure of the dust removing apparatus 1 will be described with reference to the drawings. FIG. 2 is a sectional view taken along line XX in FIG. 1, and FIG. 3 is a sectional view taken along line ZZ in FIG. 1 [FIG. 3 (a)]. And YY cross section [Fig. 3
(B)] is an explanatory view showing FIG. 4, and FIG. 4 is a cross-sectional view taken along line WW in FIG. 1. The outer cyclone 3 provided in the lower part of the dust removing device 1 has a bottomed cylindrical shape, and the bottom portion 3a can store and store the dust and also serves as a dust storage container. The upper end of the outer cyclone 3 is open, and just below this upper end, an exhaust gas introduction port 5 for introducing exhaust gas from a diesel engine (not shown) into the outer cyclone 3 and an outside air introduction for introducing outside air into the outer cyclone 3 A mouth 7 is provided. As shown in FIG. 2, the axes of the exhaust gas introduction port 5 and the outside air introduction port 7 are parallel to the tangent line of the cross section of the outer cyclone 3, and the outer cyclone 3
The exhaust gas and the outside air introduced into the outer cyclone 3 can be swirled and swirled along the inner wall of the outer cyclone 3.

As shown in FIG. 1, the outer cyclone 3 has:
A funnel-shaped sub-cylinder 9 is inserted downward from the open upper end. The lower end of the sub-cylinder 9 is located near the center of the outer cyclone 3 and slightly above, and opens. Further, a substantially conical inner cyclone 11 having an upper diameter larger than a lower diameter is inserted through the sub-cylinder 9 into the outer cyclone 3. As shown in FIG. 2, a space S through which gas can pass is formed between the sub-cylinder 9 and the inner cyclone 11.

A cylindrical portion 11a is provided above the inner cyclone 11.
Is provided, and an opening 11b is provided at the lower end. The lower part of the inner cyclone 11 is the outer cyclone 3
Cylindrical dust container 13 installed on the bottom 3a of the
It is inserted inside. A conical trapezoidal connecting portion 13 a is provided on the upper portion of the soot and dust storage container 13.
The inner cyclone 11 is detachably fitted into the opening formed in a. The bottom portion 13b of the dust container 13 has a large outer diameter in order to enhance stability when the bottom portion 13b is installed in the outer cyclone 3.

On the other hand, a tubular short cylinder 15 is interposed between the upper end of the outer cyclone 3 and the cylindrical portion 11a of the inner cyclone 11 to connect them together, and the distance between the sub-cylinder 9 and the inner cyclone 11 is increased. Properly hold the sub-cylinder 9 and the inner cyclone 1
It has a function of maintaining the width of the space S formed between the voids 1 and 1. Further, as shown in FIG. 3, an annular space T is formed between the inner cyclone 11 and the short body 15 so that gas can pass therethrough. Further, the short body 15 and the cylindrical portion 11 a of the inner cyclone 11 are communicated with each other via a communication passage 17. As a result, the gas can flow into the inner cyclone 11 from the gap T through the communication passage 17. Moreover, as shown in FIG. 3A, the cylindrical portion 11 of the communication passage 17 is
The axis of the inflow portion 17a into the a is parallel to the tangential line of the cross section of the cylindrical portion 11a, and the gas introduced into the inner cyclone 11 can be swirled and swirled along the inner wall of the inner cyclone 11.

The end of the inner cyclone 11 on the side of the cylindrical portion 11a is open, but at this end, a disc-shaped inner chamber 19a is formed.
The exhaust chamber 19 provided with is connected. An exhaust pipe 21 provided at the center of the lower portion of the exhaust chamber 19 and communicating with the inner chamber 19a is inserted into the cylindrical portion 11a of the inner cyclone 11. Further, the exhaust chamber 19 has a discharge port 23.
Is provided. As a result, the gas can flow out from the inner cyclone 11 to the outside through the exhaust pipe 21, the inner chamber 19a and the discharge port 23.

Therefore, the gas flowing into the outer cyclone 3 from the exhaust gas inlet 5 and the outer air inlet 7 is a space S formed between the sub-cylinder 9 and the inner cyclone 11, and between the inner cyclone 11 and the short cylinder 15. Can flow into the inner cyclone 11 through the gap T and the communication passage 17 formed in the inner side of the inner cyclone 11, and through the exhaust pipe 21, the inner chamber 19a of the exhaust chamber 19 and the discharge port 23.
It can be leaked to the outside.

Further, as shown in FIG. 1, in the outer cyclone 3, the inner cyclone 11 and the soot and dust container 13,
A dust holding material 25 capable of accumulating and holding dust is detachably installed along these inner walls. Furthermore, the outer cyclone 3, the inner cyclone 11 and the dust container 13 are
It can be freely separated from other components. Therefore, the outer cyclone 3, the inner cyclone 11 and the dust container 1
It is also possible to freely attach and detach the soot and dust holding material 25 installed in No. 3 to and from the soot and dust removing device 1.

Next, a case where the soot and dust removing device 1 separates and collects soot and dust from the exhaust gas of a diesel engine will be described. Exhaust gas from the diesel engine flows into the outer cyclone 3 through the exhaust gas inlet 5. The inflowing exhaust gas swirls along the inner wall of the outer cyclone 3 and flows downward. At this time, soot and dust with a large specific gravity in the exhaust gas collide with and adhere to the soot and dust holding material 25 installed in the outer cyclone 3 or fall downward due to the action of centrifugal force accompanying the swirling motion. , Soot holding material 2
5 accumulates and is retained.

Next, the exhaust gas is fed to the sub-cylinder 9 and the internal cyclone 1
1 flows into the space S formed between the inner cyclone 1 and
The gas flows into the cylindrical portion 11a of the inner cyclone 11 through the space T formed between the 1 and the short body 15 and the communication passage 17. Since the axis of the inflow portion 17a of the communication passage 17 into the cylindrical portion 11a is parallel to the tangential line of the cylindrical portion 11a, the exhaust gas flowing into the inner cyclone 11 swirls and flows along the inner wall of the inner cyclone 11. As a result, as in the outer cyclone 3, the dust particles in the exhaust gas are separated from the exhaust gas, and part of them are accumulated and retained on the dust retaining material 25 installed along the inner wall of the inner cyclone 11.
The other part is the opening 11b at the lower end of the inner cyclone 11.
After that, it falls into the dust container 13 and is accumulated and retained on the dust retaining material 25 installed there.

Further, the exhaust gas flows out of the inner cyclone 11 to the outside through the exhaust pipe 21, the inner chamber 19a of the exhaust chamber 19 and the discharge port 23. The outflowing exhaust gas is separated and removed from the dust while passing through the outer cyclone 3 and the inner cyclone 11, so that it is cleaned.
Emission of exhaust gas containing combustion residues such as tar and soot is prevented.

When the exhaust gas guided from the engine is supplied to the exhaust gas introduction port 5, the outside air introduction port 7 which is supplied to substantially the same position as the exhaust gas introduction port 5 is provided to obtain the following effects. For example, when the amount of exhaust gas is small in an engine operating state such as during low-speed rotation, the obtained flow velocity becomes smaller in proportion to the number of revolutions if the cross-section of the flow passage to be passed is the same, and the centrifugal force of the gas body is It decreases in proportion to the square of the flow velocity.

Therefore, for the purpose of compensating for the decrease in the exhaust gas flow rate due to the change in the engine rotation and the like, for example, when the exhaust gas amount is small in the low speed region of the engine rotation, the auxiliary outside air is fanned (shown in the figure) so as to obtain a sufficient flow rate. It is supplied separately). The outside air may be supplied at a predetermined flow rate below a predetermined engine rotation speed and stopped when the predetermined engine rotation speed is exceeded, or continuously or stepwise depending on the level of the engine rotation speed. You may make it decrease. It is also possible to detect the amount of exhaust gas and control the amount of outside air introduced according to this amount, or to detect the amount of intake air instead of the rotational speed and the amount of exhaust gas, and thereby perform the same control as above. Therefore, for example, the outside air is introduced according to the flow rate of the exhaust gas which changes with the change of the engine rotation speed from the low speed region to the high speed region, so that the performance can be made uniform in the entire rotation region of the engine. In addition to using any one of the rotation speed, the amount of exhaust gas, and the amount of intake air as the barometer of the introduced amount of outside air, it is also possible to use these two or three in combination. Further, instead of directly detecting the intake air amount, the product of the rotation speed and the intake pressure may be used.

Further, this outside air has a temperature sufficiently lower than that of the exhaust gas and has an effect of cooling the high temperature exhaust gas.
It condenses polluting elements such as rust and soot, and increases the weight difference from the gas body. It goes without saying that the larger the weight difference and the heavier the residual substance, the easier the separation of the gas and the residual substance. The outside air supply amount may be increased / decreased depending on whether the temperature of the exhaust gas is high or low by detecting the exhaust gas temperature.

As described above, the control for changing the introduced amount of the outside air according to the engine speed, the exhaust gas amount or the intake air amount and the exhaust gas temperature is equipped with an engine rotation sensor and an exhaust gas temperature sensor, and is controlled by a control device such as a microcomputer. Then, it can be performed by adjusting the fan for introducing the outside air and the air volume switching damper according to the rotation speed and the temperature data.

In the soot-dust removing device 1 of this embodiment, the cyclone is arranged in two stages in series and the soot dust left behind in the first stage is further captured in the second stage, but the cyclone is only one stage. But it doesn't matter. It is also possible to improve the efficiency of trapping and separating soot by charging the outside air mixed in the exhaust gas or adding a component that chemically reacts with the soot to agglomerate it.

The dust holding material 25 may be a filter type having air permeability or a non-air permeable type, as long as it can hold the dust. Since the outer cyclone 3, the inner cyclone 11, and the dust container 13 can be freely separated from other components, the dust holding material 25 in which the dust is accumulated is provided.
Can separate the installed external cyclone 3 and the like from other components and remove it from the soot / dust removing device 1. Since the removed dust holding material 25 can be discarded together with the accumulated dust, there is no risk of scattering the dust and contaminating the surroundings with the disposal of the dust.

[0030]

The device for removing dust from exhaust gas of a diesel engine of the present invention can easily separate and remove a large amount of dust contained in the exhaust gas of a diesel engine.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a configuration of a soot and dust removing device of the present embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

3 is a sectional view taken along line ZZ and YY of FIG.

4 is a cross-sectional view taken along the line WW of FIG.

FIG. 5 is a block diagram illustrating the configuration of a device for removing dust and dirt from exhaust gas of a diesel engine according to claim 3;

[Explanation of symbols]

1 ... Dust removal device, 3 ... Outer cyclone, 5 ...
-Exhaust gas inlet, 7 ... Outside air inlet, 11 ... Inner cyclone, 13 ... Soot and dust storage container, 17 ... Communication passage, 25 ... Soot and dust holding material.

Claims (4)

[Claims] 1. A cyclone type dust removing device provided in an exhaust gas flow path of a diesel engine, wherein a removable dust container is arranged in a portion of the cyclone where the dust is accumulated. A device for removing soot and dust from exhaust gas. 2. A cyclone-type dust removing device provided in an exhaust gas flow path of a diesel engine, characterized in that it is provided with an outside air introduction port as well as an exhaust gas introduction port into the cyclone. Removal device. 3. An operating condition detecting means for detecting at least one of a rotational speed, an intake air amount and an exhaust gas amount of a diesel engine, and an outside air introducing amount for increasing an outside air introducing amount as a detection value detected by the operating condition detecting means becomes lower. 3. A device for removing soot and dust in exhaust gas of a diesel engine according to claim 2, further comprising: an amount control means. 4. A cylindrical outer cyclone extending in a vertical direction, an inner cyclone having a lower end portion installed inside the cylindrical outer cyclone smaller than a diameter of the upper end portion, the outer cyclone and the inner cyclone. And a soot and dust holding member that is detachably provided to each of the cyclones and that stores and holds soot and dust.
5. A device for removing soot and dust from exhaust gas of a diesel engine according to any one of 1 to 3.