JPH0379530B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a particulate purification device for exhaust gas that collects particulates in exhaust gas emitted from internal combustion engines of automobiles and burns them to purify the exhaust gas. .

In order to collect particulates such as carbon particles contained in exhaust gas emitted from internal combustion engines, particulate collection devices incorporating a filter member such as a ceramic honeycomb structure or ceramic foam have been proposed. . In these devices, as fine particles accumulate on the filter member, the ventilation resistance of the filter member increases, leading to a decrease in engine output, and
Accumulated fine particles fall off and reduce filter function.
Therefore, it is necessary to periodically remove the particulates accumulated on the filter member and restore the function of the filter member to the state before collecting the particulates.

As disclosed in JP-A No. 56-92318, as a means for this regeneration, a partition wall is installed at the center of the filter member to divide the whole into two, and the two halves are placed on the exhaust gas inflow side of the filter member. There is a type in which a heating means is provided independently corresponding to each region, and a flow path switching valve is provided on the exhaust gas inflow side of the filter member to alternately switch the inflow of exhaust gas to the two divided portions of the filter member.

This system alternately guides exhaust gas into two divided regions of the filter member, collects particulates in one region of the filter member, and when regenerating this one region, communicates with the region using a flow path switching valve. The side exhaust gas passage is closed and electricity is applied to the heating means installed in that area, and when electricity is applied, the exhaust gas is guided to the other area of the filter member, and particulates are collected in this other area.

With this conventional means, the exhaust gas does not flow into the regeneration side during regeneration, and the heating means is not cooled by the exhaust gas, so heating efficiency is good.

However, on the other hand, since the filter member is divided into two parts, the cross-sectional area of each region becomes small, resulting in a large pressure loss both during particulate collection and during regeneration. In order to reduce the pressure loss, it is possible to increase the size of the filter member and increase the area of each divided region, but this results in an increase in the size of the entire purification device.

An object of the present invention is to provide an exhaust gas particulate purification device for an internal combustion engine in which the heating efficiency of the heating means is good and an increase in pressure loss can be avoided without increasing the size.

Therefore, in the present invention, a single filter member that is not divided is used as a filter member, and only the exhaust gas passage that guides the exhaust gas is divided on the upstream side of the filter member, so that the exhaust gas flow path that flows into the filter member is divided. At the same time, a means for selectively blocking or restricting one of the flow paths is provided, and a heating means is provided independently at a position corresponding to each flow path on the exhaust gas inflow side of the filter member, so that the filter member can be regenerated. The above object is achieved by diffusing the exhaust gas that has flowed into the filter member from one of the flow paths on the exhaust gas outflow side of the filter member.

That is, according to the device of the present invention, when the exhaust gas flows into the end face of the filter member, the inflow area is limited, but after the exhaust gas flows in, it can be diffused throughout the filter member, so that the pressure loss can be extremely small.

Hereinafter, the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a configuration diagram of an exhaust system of an internal combustion engine equipped with an exhaust gas particulate purification device according to the present invention. 1
2 is an internal combustion engine such as a diesel engine, 2 is an exhaust manifold, 3 is an exhaust pipe, and A is a particulate purification device provided in the middle of the exhaust pipe.

The purification device A includes a filter member storage container 4, a particulate collection filter member 5, and electric heaters 6a and 6b as heating means that are brought into close contact with the exhaust gas inflow side (upstream side) end face of the filter member 5. Reference numeral 7 denotes a plate-shaped separation member (hereinafter referred to as a separation plate) that bisects the upstream side of the container 4, which forms an exhaust gas passage that guides exhaust gas to the filter member 5, and divides the exhaust gas flow path that flows into the filter member 5; Reference numeral 8 denotes an exhaust gas flow path switching member (hereinafter referred to as a switching valve) that controls the inflow of exhaust gas into the divided flow paths. 9 is a differential pressure sensor for measuring the differential pressure on the upstream side and downstream side of the filter member 5 to detect pressure loss; 10 is a temperature sensor for detecting the exhaust gas temperature on the downstream side of the filter member 5; 11 is an engine This is a rotation speed sensor that detects the rotation speed of 1. 12 calculates the degree of particulate accumulation on the filter member 5 based on the outputs of the differential pressure sensor 9, temperature sensor 10, and rotation speed sensor 11, and when the degree of accumulation exceeds a predetermined value, electric heaters 6a, 6b are activated.
and a control circuit that generates an output signal for operating the switching valve 8. 13 is batsuteri, 1
4 is a heater operating switch that receives an output signal from the control circuit 12 and supplies electric power from the battery 13 to the electric heaters 6a and 6b; 15 operates the flow path switching valve 8 in response to an output signal from the control circuit 12; It is a valve actuator.

In the above configuration, the switching valve 8 is kept in a neutral state when the filter member 5 collects particulates. Particulates in the exhaust gas discharged through the exhaust manifold pipe 2 and exhaust pipe 3 of the internal combustion engine 1 are collected as they pass through the filter member 5. As the collection progresses, the ventilation resistance of the filter member 5 gradually increases, and this is detected by the differential pressure sensor 9. Since this differential pressure varies greatly depending on the exhaust gas temperature and engine speed, the temperature sensor 10 and engine speed sensor 11 detect each of these, and by removing these influences, the true filter ventilation resistance can be determined. ,
That is, it is possible to know the degree of accumulation of fine particles. When a predetermined level of accumulation is reached, a signal is sent from the control circuit 12 to the valve actuating device 15, and the switching valve 8 is actuated to cut off the flow of exhaust gas to one flow path partitioned by the separator plate 7. . Electric heater 6a (or 6b) in the flow path area where the exhaust gas flow is blocked at the same time
When the heater is energized, the heater becomes red hot and the particulates collected around it are heated and combustion starts, the flame spreads to the downstream side and the collected particulates are burned and purified. When the end of regeneration is confirmed by the temperature sensor 10, the switching valve 8 is switched to guide the exhaust gas flow to another flow path, and the electric heater 6b (or 6a) in that flow path area is energized and generates heat, causing the nearby The collected particulates are ignited, the combustion flame propagates to the downstream side, and the particulates are burned and purified. In addition, when the collected particulates are ignited by the electric heater in one flow path region and burned, the temperature detected by the temperature sensor 10 must be higher than a predetermined value to prevent an abnormally high temperature phenomenon or the flame from being blown out. When the switching valve 8 is reached,
The opening degree is controlled so that a small amount of exhaust gas can enter the one passage, and the one passage is completely shut off when the detected temperature drops to a predetermined value.

FIG. 2 shows a first embodiment of the exhaust gas particulate purification device according to the present invention.

A cylindrical filter member 5 is housed in the cylindrical container 4, and the filter member 5 is elastically supported by a wire net 41 and a seal member 42. The filter member 5 is made of ceramic foam, for example. A separator plate 7 is installed on the exhaust gas inflow side of the container 4, and the exhaust gas flow path to the filter member 5 is divided into a first flow path 40a and a second flow path 40b. A switching valve 8 is rotatably supported at the tip of the separator 7, and by this rotation, the opening, closing, or opening of the flow paths 40a and 40b is controlled.

On the upstream end face of the filter member 5, nichrome wire heaters 6a and 6b are installed in each flow path area, respectively. The heaters 6a, 6b are fixed by ceramic honeycomb bodies 60a, 60b provided to cover them. Ceramic honeycomb body 60
a and 60b serve as a heater holding member and a heat insulator.

In the device of this embodiment, the switching valve 8 is first in the neutral position, and the exhaust gas flows through both flow paths 40a and 40b.
The particles flow into the filter member 5, where the fine particles are collected and flow out from the filter member 5.

When the amount of particles collected by the filter member 5 reaches a predetermined value, the switching valve 8 rotates to close the first flow path 40a. At the same time, the heater 6a is energized, and the particles collected near the end face of the filter member 5 are ignited.
The combustion spreads to the collected fine particles on the downstream side, and mainly the upper half of the filter member 5 is regenerated.
Subsequently, the switching valve 8 rotates to open the first flow path 40a.
while opening the second flow path 40b,
The heater 6b is energized to ignite the particles, and mainly the lower half of the filter member 5 is regenerated, thereby regenerating the entire filter.

However, in the above device, when one of the heaters 6a or 6b is energized, exhaust gas does not flow into the heater that generates heat when it is energized, so it is not cooled by the exhaust gas, and a small amount of thermal energy is used to reliably generate particles. can be ignited. Furthermore, when one exhaust gas flow path, for example, flow path 40a, is closed and particulates are ignited and burned by the heater 6a, exhaust gas flows into the filter member 5 from the other flow path 40b, and this exhaust gas is passed through the filter member 5. As the member 5 flows downstream, it spreads and flows out from the downstream end face of the filter member 5, but immediately after flowing into the filter member 5 from the upstream end face, the heater 6
There is less exhaust gas spreading to the a side, so the heater 6
Immediately after the particulates are ignited by a and start combustion, they are rarely affected by the cooling effect of the exhaust gas.
This prevents the flame from being blown out immediately after the start of combustion. Furthermore, the exhaust gas flows into the filter member 5 from half of the end face of the filter member 5, but after flowing in, it spreads to the downstream side over the entire filter member and flows out, so the filter member 5 has the same cross-sectional area. In this case, the pressure loss is smaller than in the conventional filter in which the entire filter member is divided into two parts and exhaust gas is allowed to flow through only one of them. According to experiments conducted by the inventors, in the above device of the present invention, one of the channels,
For example, if the flow path 40a is completely blocked and the exhaust gas is allowed to flow into the filter member 5 only from the flow path 40b, the pressure loss will be lower than when the exhaust gas is allowed to flow into the filter member 5 from the entire end face of the filter member 5. The increase is about 30% at most. On the other hand, if the entire filter member 5 is divided into two regions and the exhaust gas is allowed to flow into only one region, the pressure loss will be approximately doubled.

FIG. 3 shows a second embodiment of the invention. In this embodiment, a separator plate 70 is provided at an extended position of the separator plate 7 inside the filter member 5 on the upstream side to define a position near the end face on the upstream side. The other structure is the same as the first embodiment. In this embodiment, after the fine particles are ignited by the heater on the side where the flow of exhaust gas is blocked, the propagation of combustion is not affected by the exhaust gas at all due to the separator 70, and blowing out after ignition is more effective. Definitely prevented. In addition, the separator 70 provides a rectifying effect to the exhaust gas flowing in from each flow path, reducing the amount of exhaust gas flowing into the area where particulates are being burned, so the pressure loss is slightly lower than in the first embodiment. However, the flame is more effectively prevented from being blown out on the downstream side of the filter member.

FIG. 4 shows a third embodiment, in which the switching valve 8 is pivotally supported at a position in contact with the end face of the filter member 5, and the switching valve 8 acts as a separator that divides the exhaust gas inflow channel. Also serves as

FIG. 5 shows a fourth embodiment, in which the separator 7
The heaters 6 a and 6 b are embedded inside the filter member 5 , and the rear end thereof extends inside the end face of the filter member 5 in a range near the end face. The distribution of the amount of particles collected in the filter member 5 is greatest at a portion slightly inside the end surface of the filter member 5, and therefore, the amount of particles collected by the heaters 6a,
It becomes easier to ignite the fine particles by 6b.

6 to 8 show a fifth embodiment, in which the device A is installed directly below the exhaust manifold pipe 1. FIG. The switching valve 8 is supported by a rotating shaft 81 along the end face of the filter member 5 on the exhaust gas inflow side and in the diametrical direction of the end face. Electric heaters 6a, 6
b is buried inside the filter member 5 on the end surface side. The container 4 is interposed at the joint between the exhaust manifold pipe 2 and the exhaust pipe 3, and a filter member 5 is accommodated therein while being elastically supported by a cushion/sealing material 44. In this embodiment, the exhaust manifold pipe 2 is used as the installation location for the purification device A, so there is no need to install the device in the middle of the exhaust pipe 3. Furthermore, since the exhaust gas is at a higher temperature than in the exhaust pipe, the heater power for igniting and burning the particulates can be reduced.

FIG. 9 shows a sixth embodiment, in which the filter member 5 is composed of a fine ceramic foam 5a and a coarse ceramic foam 5b, and the ceramic foam 5a is arranged on the exhaust gas inflow side. The fifth embodiment differs from the fifth embodiment in that electric heaters 6a and 6b are installed inside the body 5a, but the rest is substantially the same. Reference numeral 20 indicates an exhaust gas outlet for each cylinder of the internal combustion engine. By making the mesh of the part where the electric heaters 6a and 6b are embedded fine, the amount of particles collected around the heaters increases, and ignition is facilitated.

10 and 11 show a seventh embodiment, in which the device A is provided directly below the exhaust manifold pipe 2 as in the sixth embodiment, but the exhaust gas inflow portion to the filter member 5 is is narrowed to the same extent as the exhaust port 20 of each cylinder, and a switching valve 8 is provided in this portion. This allows the switching valve 8 to be downsized. Note that the exhaust gas division structure is the same as in the second embodiment (FIG. 3).

12 and 13 show an eighth embodiment, in which a device A is installed directly below the exhaust manifold pipe 2, and in the exhaust manifold pipe 2, a switching valve is provided at the exhaust port of each cylinder. be. Separation plates 7 and 70 are provided on the exhaust gas inflow side of the filter member 5, and the exhaust gas inflow area to the filter member 5 is divided into two.
The example shown is a four-cylinder cylinder, with switching valves 8a and 8b at the two exhaust ports leading to one of the inflow areas, and switching valves 8c and 8d at the exhaust ports leading to the other inflow area.
(8d not shown) is provided with a switching valve 8a,
8b is connected to the switching valve 8 by the link mechanism 82.
c and 8d are opened and closed by the link mechanism 83, and when the switching valves 8a and 8b are opened, the switching valves 8c and 8d are opened and closed.
8d is controlled to close. In this way, the switching valve may be installed using the exhaust gas outlet of each cylinder in the exhaust manifold pipe.

In summary, the present invention provides an exhaust gas particulate purification device in which a filter member of a single structure is installed in the exhaust gas passage of an internal combustion engine, and particulates in the exhaust gas collected by the filter member are combusted by a heating means. A flow path switching means is provided for dividing the inflow path of exhaust gas into the filter member and guiding the exhaust gas to each path, and an independent heating means is provided for each flow path area on the upstream end face of the filter member. By blocking or restricting the flow of exhaust gas into the flow path area in which the heating means operates, the heating means is hardly affected by the cooling effect of the exhaust gas, and the particulates collected on the filter member are reliably ignited. I can do it. In particular, in the present invention, the filter member itself is not provided with a partition wall at all, or only a part of the upstream end face is provided with a partition wall, so that when the filter member is regenerated, the exhaust gas flowing into the end face of the filter member from one of the channels Since the gas can diffuse throughout the filter member after entering, the increase in pressure loss is extremely small, and therefore there is no need to increase the size of the purification device in order to avoid an increase in pressure loss.

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a configuration diagram of an exhaust system of an internal combustion engine to which the present invention is applied, FIG. 2 is a sectional view of a particulate purification device, FIG. 3 is a sectional view of the second embodiment, FIGS. 4 and 5 are sectional views of the third and fourth embodiments, respectively, and FIGS. 6 to 8 are sectional views of the fifth embodiment. Figure 6 is a configuration diagram of the exhaust system of an internal combustion engine.
Fig. 7 is a partially sectional front view of the device, Fig. 8 is a sectional view taken along the - line in Fig. 7, Fig. 9 is a sectional view of the sixth embodiment, and Fig. 10 is a part of the seventh embodiment. Cross-sectional front view,
11 is a sectional view taken along the line XI-XI in FIG. 10, FIG. 12 is a partially sectional front view of the eighth embodiment, and FIG. 13 is a sectional view taken along the line -- in FIG. 12. A... Exhaust gas particle purification device, 5... Filter member, 6a, 6b... Heating means, 7, 70... Separation member, 8... Exhaust gas flow path switching member.

Claims (1)

[Scope of Claims] 1. A filter member installed in an exhaust gas passage of an internal combustion engine and having a large number of fine communication holes therein;
an isolation member installed in the exhaust gas passage that guides exhaust gas to the exhaust gas inflow side of the filter member to divide the exhaust gas passage flowing into the filter member; and an isolation member installed in the exhaust gas passage to divide the exhaust gas passage into the divided passage. an exhaust gas flow path switching member that controls the inflow of exhaust gas;
heating means installed independently on the exhaust gas inflow side of the filter member at positions corresponding to the divided flow paths to heat and burn particulates in the exhaust gas collected by the filter member; An exhaust gas particulate purification device for an internal combustion engine, wherein exhaust gas flowing into the filter member from one of the exhaust gas flow paths is diffused on the exhaust gas outflow side of the filter member. 2. The exhaust gas particulate purification device for an internal combustion engine according to claim 1, wherein the end of the isolation member on the filter member side extends to a position near the end face inside the exhaust gas inflow side of the filter member. 3. The separating member is rotatable around the end on the filter side to switch and control the exhaust gas flow path, and the separating member also serves as the exhaust gas flow path switching member. The exhaust gas particulate purification device for an internal combustion engine according to item 1.