JPH04370310A - Exhaust gas post-processing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the cost by simplifying the constitution, and burn and remove exhaust gas particulates while improving the fuel consumption. CONSTITUTION:A cylindrical filter 7 is arranged as that the filter straddles an air-intake passage 1 and an exhaust gas passage 5 by making each part of the air-intake passage 1 and the exhaust gas passage 5 mutually close. The filter 7 is rotated in synchronization with the engine speed, and the exhaust gas particulates collected in the exhaust gas passage 5 are introduced into a combustion chamber 4 through the air-intake passage 1 by the sucked air flow to burn and remove the particulates.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust aftertreatment device for an internal combustion engine.

0002

2. Description of the Related Art Conventionally, various collection devices have been proposed for reducing the emission of exhaust particulates from diesel engines into the atmosphere. In order to prevent clogging caused by collected exhaust particulates, these collection devices collect exhaust particulates mainly consisting of carbon and soluble unburned HC (hereinafter referred to as SOF) when predetermined conditions are met. - Burning and removal is done using a heating device such as a heater.

0003

[Problems to be Solved by the Invention] However, in such conventional devices, a heating device such as a burner is required to burn and remove the exhaust particulates, and a sensor and its sensor are required to detect the conditions for burning and removing the exhaust particles. A control device that outputs a control signal by the heating device based on the detection signal is required.
Furthermore, fuel is required for combustion and removal, which increases costs and also worsens the fuel efficiency, which is the biggest advantage of diesel engines.

[0004] Furthermore, in Japanese Unexamined Patent Publication No. 60-8412 and Japanese Utility Model Application No. 63-170150, a cylindrical collection device is rotatably attached to the exhaust passage, and the collection device is rotated during regeneration. It has been proposed that a part of the collection device is located outside the exhaust passage, and clean air is blown onto the collection device from a blower to remove exhaust particulates. However, since these devices are designed to collect a certain amount of exhaust particulates before removing them, the fine exhaust particulates that are easily re-burned immediately after being emitted from the engine may aggregate and cause re-combustion. There is a problem that makes it difficult.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an exhaust after-treatment device that immediately re-combusts fine particulates discharged from an engine without agglomerating them.

[0006]

[Means for Solving the Problems] Accordingly, the present invention provides, in claim 1, a part of an intake passage that guides intake air into a combustion chamber of an engine, and an exhaust passage that discharges exhaust gas from the combustion chamber to the outside. are placed close to each other so that they are approximately parallel to each other and the directions of flow of intake air and exhaust air are opposite to each other, a cylindrical storage part is provided in the parallel part, and a part of the exhaust air is provided on one side of the storage part. The upstream side of the passage and the downstream side of the intake passage communicate with each other, while the other side of the storage part communicates the downstream side of the exhaust passage with the upstream side of the intake passage, and the storage part captures exhaust particulates in the exhaust gas. a rotating device for storing a filter in a cylindrical shape that straddles the exhaust passage and the intake passage, and for rotating the filter in synchronization with engine rotation with a cylindrical axis of the filter as a substantially rotating axis; I decided to set it up.

Further, in claim 2, the filter is constituted by a plurality of filter bodies each having a different mesh size, and the filter bodies are arranged such that the mesh size gradually decreases from the upstream side to the downstream side of the exhaust passage. I decided to do so. Furthermore, in claim 3, the rotation device includes a transmission device that changes the gear ratio between the rotation speed of the filter and the rotation speed of the engine.

[0008]

[Operation] According to claim 1, by rotating the filter, exhaust particulates are collected by the filter, and then the collected exhaust particulates are removed from the filter by the intake air flow and introduced into the combustion chamber. Removed by burning. Further, in claim 2, by arranging a plurality of filter bodies having different mesh sizes so that the mesh sizes gradually become smaller from the upstream side to the downstream side of the exhaust passage, the collection efficiency of exhaust particulates is improved. The filter is designed to suppress intake air resistance and exhaust resistance while increasing the air resistance.

Furthermore, in the third aspect of the present invention, the filter is rotated at an optimum rotational speed depending on the engine rotational speed.

0010

Embodiments Below, embodiments of the present invention will be explained based on the drawings. 1-3 show a first embodiment corresponding to claims 1-2. In FIG. 1, an air cleaner 2 is installed at the upstream side of an intake passage 1 of a diesel engine, and intake air is introduced into a combustion chamber 4 through the air cleaner 2, intake passage 1, and collector 3. . Furthermore, the exhaust gas that has finished combustion in the combustion chamber 4 is discharged into the exhaust passage 5.

A parallel portion is formed by bringing a portion of the exhaust passage 5 close to a portion of the intake passage 1 so that the flow directions of intake air and exhaust air are opposite to each other, and this parallel portion has a cylindrical shape. A storage section 6 is attached. One side wall of the storage section 6 communicates with the upstream side of the exhaust passage 5 and the downstream side of the intake passage 1, while the other side wall of the storage section 6 communicates with the downstream side of the exhaust passage 5 and the upstream side of the intake passage 1. are in communication.

[0012] A cylindrical filter 7 is disposed in the storage portion 6 so as to straddle the intake passage 1 and the exhaust passage 5;
The filter 7 is supported by a support member 8 so as to be freely rotatable about the cylindrical axis of the filter 7 . Further, a pulley 9 is attached to one end of the support member 8. Further, a pulley 10 is provided which rotates in synchronization with the rotation of the camshaft, crankshaft or catcher, in other words, in synchronization with the rotation of the engine.
are connected by.

The filter 7 is formed with a large number of honeycomb-shaped passages 7A made of a porous material such as ceramic. The filter 7 also includes first to third filter bodies 7.
B to 7D are provided substantially perpendicularly to the exhaust flow and at predetermined intervals along the exhaust passage 5. Here, the mesh size of the first filter body 7B is formed larger (coarse) than the mesh size of the second filter body 7C on the downstream side of the exhaust passage, and the mesh size of the second filter body 7C is larger than the mesh size of the third filter body 7D. Largely formed. Therefore, in the filter bodies 7B to 7D, the mesh size becomes smaller toward the downstream side of the exhaust passage, and exhaust particulates having a smaller particle size can be collected toward the downstream side of the exhaust passage. The outermost periphery of the honeycomb-shaped passage 7A is sealed, and the central passage 7A is connected to the intake passage 1 and the exhaust passage 5.
It is sealed to separate them from each other.

Further, the openings of the intake passage 1 and the exhaust passage 5 on the inlet side and the outlet side of the filter 7 are formed approximately semicircularly, as shown in FIG. Furthermore, the opening on the inlet side of the filter 7 and the opening on the outlet side of the filter 7 of the exhaust passage 5 are as follows.
As shown in FIG. 3, they are formed to be shifted by a predetermined angle θ. Here, the predetermined angle θ at which exhaust gas does not flow into the intake passage 1 will be described below.

First, when the engine displacement is set to V (cc), the engine rotational speed is set to NE (ypm), and the cross-sectional area of the exhaust passage side of the filter 7 is set to A, the exhaust flow velocity V (cm/s
c) can be expressed by the following formula. V=NE/60×B/2×1/A=NE×V/(1
20×A) Also, the time TG for the exhaust gas to pass through the filter 7
When the length of the filter 7 is set to Lcm, TG=1
/v=120×A×L/(NE×V)(sec
).

On the other hand, the time TS during which the filter 7 rotates by the predetermined angle θ changes the rotational speed of the filter 7 to NF (rp
m), TS=60/NF×θ/360=θ
/(6×NF). When the filter 7 rotates by the predetermined angle while the exhaust gas passes through the filter 7, the times TG and TS become equal, so TG=T
It becomes S. As a result, from the above calculation formula, 120×A×
L/(NE×V)=θ/(6×NF) is obtained, and from this relational expression, θ=720×L×A×(A/V)×(NF/
NE) is obtained.

[0017] Therefore, the inlet side opening of the exhaust passage;
A predetermined angle θ calculated from the relational expression between the exit side opening and
If there is a misalignment, exhaust gas will not flow into the intake passage. Note that 12 is a combustion injection valve. Next, the effect will be explained.

After combustion, the exhaust gas is discharged into the exhaust passage 5 and introduced into the filter 7 together with fine exhaust particles (mainly composed of carbon and SOF) generated during combustion.
Exhaust particles are collected by the first to third filter bodies 7B to 7D of the filter 7. The filter 7 rotates in synchronization with the rotation of the engine, and the filter 7 located in the exhaust passage 5 is located in the intake passage 1 at the next moment. At this time, since the flow direction of the intake air is opposite to the flow direction of the exhaust gas, the exhaust particulates collected by the filter 7 are blown by the intake air before they aggregate and are drawn into the combustion chamber 4 together with the intake air. After that, the exhaust particulates are burned together with the injected fuel in the next combustion stroke.

As explained above, the intake passage 1 and the exhaust passage 5 are brought close to each other to form the storage section 6.
The filter 7 is housed in the filter 7, and after the filter 7 is rotated to collect the exhaust particulates, the exhaust particulates are removed from the filter 7 by the intake air flow and burned in the combustion chamber 4, which is different from the conventional method. With a simpler configuration, it is possible to reduce the amount of exhaust particulates released into the atmosphere, reduce costs, and improve fuel efficiency.

[0020] Also, the first to third filter bodies 7B to 7D
Since the mesh size is gradually increased from the upstream side of the exhaust gas to the downstream side of the exhaust gas, the particle size of the collected exhaust particulates gradually decreases from the upstream side of the exhaust gas, and the exhaust particulates can be efficiently collected. Even if the efficiency is increased, the exhaust resistance can be suppressed to a smaller value than when the mesh size is finely set. Conversely, in the intake passage 1, the mesh size of the first to third filter bodies 7B to 7D gradually increases from the intake upstream side to the downstream side. Exhaust particulates can be removed satisfactorily from the third filter bodies 7B to 7D.

FIG. 4 shows a second embodiment of the invention corresponding to claims 1-3. In the following embodiments, the same elements as in the first embodiment are denoted by the same reference numerals as in FIG. 1, and the explanation thereof will be omitted. In this embodiment, a variable speed pulley 21 is provided to change the speed ratio between the rotational speed of the filter 7 and the engine rotational speed depending on the engine operating state.

By the way, when the speed ratio NF/NE between the rotational speed NF of the filter 7 and the engine rotational speed NE is changed,
The predetermined angle θ at which exhaust gas does not flow into the intake passage 1 side changes. However, since the mounting positions of the inlet-side opening and the outlet-side opening of the exhaust passage are set at fixed positions, when the predetermined angle θ changes, a predetermined amount of exhaust gas is returned to the intake passage 1 via the filter 7. can reduce NOx.

That is, the exhaust gas flows out from the filter 7 into the exhaust passage 5 on the downstream side, but when the rotational speed of the filter 7 increases, the exhaust gas opens into the intake passage 1 before reaching the outlet side of the filter 7, and the exhaust gas flows into the intake passage 5. It is refluxed to passage 1. Specifically, as the engine rotation speed NE increases, the speed ratio NF/NE increases.
control to increase the exhaust gas recirculation rate. By doing this, when increasing the exhaust gas recirculation rate in the conventional exhaust gas recirculation system, the amount of exhaust particulate emissions increases and there is a limit to reducing NOx, but with this example, the exhaust particulate collection rate increases, Furthermore, since the exhaust particulates are re-burned in the combustion chamber, the exhaust gas recirculation rate can be greatly improved while the emission rate of the exhaust particulates is suppressed to a low level, so that the amount of NOx emissions can be significantly reduced. In addition, with conventional systems, the upper limit of the exhaust recirculation rate is suppressed by the size of the exhaust recirculation passage or the control valve, and the intake passage is narrowed to increase the recirculation rate, but with this system, the pumping loss In contrast, in this embodiment, an exhaust gas recirculation passage and a control valve are not required, so that the amount of exhaust gas recirculation can be significantly increased without deteriorating fuel efficiency.

Note that the predetermined angle θ shown in FIG. 3 may be changed by changing the mounting positions of the inlet side opening and the outlet side opening of the exhaust passage 5. FIG. 5 shows a third embodiment of the invention. In this embodiment, an oxidation catalyst device 31 is interposed in the exhaust passage 5 upstream of the filter 7 to reduce HC. Further, since the oxidation catalyst device 31 upstream of the filter 7 is provided, the temperature of the catalyst is increased and oxidation of HC can be greatly improved.

FIG. 6 shows a fourth embodiment of the invention. In this embodiment, a bypass passage 41 is formed in the intake passage 1 so as to bypass the filter 7, and an on-off valve 42 is interposed in the bypass passage 41. and,
When the engine is in an operating state in which exhaust particulates can be actively burned in the combustion chamber, an on-off valve 42 is closed to guide the exhaust particulates to the combustion chamber 4 through the intake passage 1. In addition, when the engine is operating in a state where combustion of exhaust particulates is insufficient, the on-off valve 4
The intake air introduced into the filter 7 is reduced by opening the valve 2. This allows exhaust particulates to be introduced into the combustion chamber 4 in accordance with the exhaust particulate combustion capacity of the combustion chamber 4, thereby preventing the exhaust particulates from remaining in the exhaust particulate recirculation system more than necessary and increasing. did. Note that exhaust particulates can be reburned more efficiently by controlling the on-off valve to an intermediate opening degree or by providing a plurality of bypass passages for more detailed control.

FIG. 7 shows a fifth embodiment of the present invention. In this embodiment, a compressor 51A of an exhaust turbo supercharger 51 is installed in the intake passage 1 upstream of the filter 7, and a turbine 51B for rotationally driving the compressor 51A is installed in the intake passage 1 downstream of the filter 7. It was designed to be used as an intervention. This makes it possible to recirculate the exhaust gas even if the intake pressure is higher than the exhaust pressure, as long as the sealing performance at the end face of the storage section 6 can be ensured, which is the most distinctive feature compared to the conventional one.

FIG. 8 shows a sixth embodiment of the present invention. In this embodiment, a DC motor 6 is attached to a support member 8 that supports a filter 7.
1 is attached to the DC motor 61, and a rotation speed sensor 62 for detecting the rotation speed of the motor 61 is also attached to the DC motor 61. The control device 63 drives and controls the DC motor 61 based on engine operating conditions such as engine rotational speed, thereby changing and suppressing the rotational speed of the filter 7 according to the engine operating condition. It is something. Thereby, the rotational speed of the filter 7 can be quickly controlled in response to changes in engine operating conditions. Since it is no longer necessary to arrange the filter 7 in parallel to the crankshaft of the engine, etc., there is an effect that the degree of freedom in layout can be greatly improved.

[0028]

Effects of the Invention As explained above, in claim 1, the present invention is characterized in that a part of the exhaust passage and a part of the intake passage are brought close to each other so that the filter straddles the exhaust passage and the intake passage. After the exhaust particulates collected by the filter are introduced into the intake passage, they are burned and removed in the combustion chamber. It is refluxed into the engine combustion chamber and can be easily reburned.

Further, in the second aspect of the present invention, since a plurality of filter bodies are provided, the mesh size of which decreases sequentially from the upstream side of the intake passage to the downstream side, exhaust particulates can be efficiently collected, and the intake air Exhaust particles can be effectively removed from the filter body in the passage by the intake air flow, and the exhaust resistance and exhaust resistance of the filter can be reduced.

Furthermore, in claim 3, since the gear ratio between the rotational speed of the filter and the engine rotational speed can be changed, exhaust particulates can be collected and removed by combustion.
It is possible to significantly increase the exhaust gas recirculation rate, significantly suppress NOx emissions, and prevent deterioration of fuel efficiency during exhaust gas recirculation control.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

[Figure 2] Enlarged view of the main parts of the same as above.

[Figure 3] Cross-sectional view of Figure 2.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

FIG. 5 is a configuration diagram showing a third embodiment of the present invention.

FIG. 6 is a configuration diagram showing a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram showing a fifth embodiment of the present invention.

FIG. 8 is a configuration diagram showing a sixth embodiment of the present invention.

[Explanation of symbols]

1 Intake passage
7D First filter body 5 Exhaust passage
9,10 Pulley 6
Storage part 1
1 Belt 7 Filter 7B First filter body 7C First filter body

Claims (3)

[Claims] Claim 1: A part of the intake passage that guides intake air into the combustion chamber of the engine and a part of the exhaust passage that discharges exhaust gas outward from the combustion chamber are substantially parallel to each other and in the direction of flow of the intake air and exhaust gas. a cylindrical storage part in the parallel part, and one side of the storage part communicating with the upstream side of the exhaust passage and the downstream side of the intake passage, and the other side of the storage part. The downstream side of the exhaust passage and the upstream side of the intake passage are formed in communication with each other, and a cylindrical filter for collecting exhaust particulates in the exhaust gas is placed in the storage part and extends between the exhaust passage and the intake passage. 1. An exhaust after-treatment device for an internal combustion engine, characterized in that the filter is housed in a cylindrical shaft, and is provided with a rotation device that rotates the filter in synchronization with engine rotation using a cylindrical shaft of the filter as a substantially rotation axis. 2. The filter is composed of a plurality of filter bodies each having a different mesh size, and the filter bodies are arranged so that the mesh size gradually decreases from the upstream side to the downstream side of the exhaust passage. The exhaust aftertreatment device for an internal combustion engine according to claim 1. 3. An exhaust gas after-treatment device for an internal combustion engine, wherein the rotating device includes a transmission device that changes a gear ratio between the rotational speed of the filter and the rotational speed of the engine.