JPH0893451A - Exhaust fine particle treating device for internal combustion engine - Google Patents

Abstract

PURPOSE: To improve regenerating performance of an exhaust fine particle treating device for an internal combustion engine by setting a clearance between a thermal insulation sheath inner circumferential surface and a filter outer circumferential surface within a specified length range. CONSTITUTION: The outer side of a filter 104 in which a heater 106 is housed is covered with a thermal insulation sheath 105 at a clearance C, and the clearance C is set to 5 to 15mm. It is thus possible to ensure oxygen for combustion at the time of regeneration of a filter in the clearance C, and also exhaust fine particle stuck on the inner circumferential surface of the thermal insulation sheath 105 is burnt out, and then radiation performance is maintained in good condition so as to improve regenerating performance of the filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust particulate processing apparatus for collecting and burning and removing exhaust particulates contained in the exhaust gas of an internal combustion engine (especially diesel engine), and more particularly to a technique for improving the efficiency of combustion removal. .

[0002]

2. Description of the Related Art A conventional exhaust particulate treatment apparatus of this type has, for example, a structure in which the outer peripheral surface of a filter for collecting exhaust particulate is covered with a hollow cylindrical heat shield sheath having communication holes at both ends. There is something (Japanese Patent Application No. 5-333909)
No.).

[0003]

However, the exhaust particle treating apparatus having the above structure is not provided with a means for supplying combustion air when the exhaust particles are burned and removed by a heating means such as a heater to regenerate the filter. In this case, if the gap between the outer peripheral surface of the filter and the inner peripheral surface of the heat shield is too small, the oxygen in the gap becomes thin, and even if the temperature of the heating means rises sufficiently, the combustion of exhaust particulates does not proceed, while If the gap is too large, the exhaust particulates adhering to the inner peripheral surface of the heat shield cannot be burned out, so that the effect of radiation by the heat shield cannot be sufficiently obtained, and the exhaust particulates deposited on the outer peripheral surface of the filter cannot be obtained. There was a problem that the filter was not burned and the filter could not be fully regenerated.

The present invention has been made in view of the above conventional problems, and an object thereof is to enhance the combustion removal performance of exhaust particulates by appropriately setting the gap between the filter and the heat shield. . Further, another object of the present invention is to increase the effect of radiation by further setting the emissivity of the inner peripheral surface of the heat shield to further enhance the combustion removal efficiency of exhaust particulates.

[0005]

Therefore, the invention according to claim 1 is provided with a filter which is interposed in the exhaust passage of the internal combustion engine and collects fine particles in the exhaust gas, and the exhaust fine particles collected by the filter. In an exhaust particulate treatment apparatus for an internal combustion engine, which is configured to burn and remove by a heating means at a predetermined time, a heat shield covering the outer peripheral surface of the filter with a gap is provided, and inside the heat shield. It is characterized in that the gap between the peripheral surface and the outer peripheral surface of the filter is set within the range of 5 to 15 mm.

The invention according to claim 2 is characterized in that the emissivity of the inner peripheral surface of the heat shield is 0.1 (100 ° C) or less.

[0007]

According to the invention of claim 1, since the gap between the inner peripheral surface of the heat shield and the outer peripheral surface of the filter is 5 mm or more, even if combustion of exhaust particulates by the heating means progresses, combustion occurs in the gap. Oxygen required for completion is secured, and because the gap is within 15 mm, exhaust particulates adhering to the inner peripheral surface of the heat shield are burned off and the radiant heat from the inner peripheral surface of the heat shield is sufficient. Since it can be used, the exhaust particulates deposited on the outer peripheral surface of the filter can be removed by combustion.

Further, by setting the emissivity as in the second aspect of the present invention, the radiation performance of the heat shield is further enhanced, so that the combustion removal performance of exhaust particulates is further improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention. An exhaust particle processing apparatus E according to the present invention is interposed in the exhaust passage of an engine body (not shown). Explaining each component of the exhaust particulate processing apparatus E, the exhaust introduction port 101 at the upstream end will be described.
And a filter case 102 to which the exhaust introduction port 101 is connected
A downstream side exhaust pipe 103 connected to the downstream end of the filter case 102, a filter 104 interposed in the filter case 102 for collecting exhaust particulates in the exhaust, and the filter 10
A hollow cylindrical heat shield sheath 105 that covers the outer peripheral surface of 4 with a gap.
And a heater 106 mounted inside the filter 104, that is, on the upstream side of the exhaust gas, for heating and burning the exhaust particulates, and a heater drive circuit 107 for electrically driving the heater 106.

Here, the gap C between the outer peripheral surface of the filter 104 and the inner peripheral surface of the heat shield 105 is set within the range of 5 to 15 mm. Further, the heater drive circuit 107 includes the heater
A regeneration timer relay 109 for connecting the vehicle-mounted battery 108 to the vehicle-mounted battery 108 for a predetermined time to energize it, and the timer relay 10
It is composed of a reproduction switch 110 for manually turning ON 9 and a reproduction / warning lamp 111 for warning the state of reproduction.

Further, the exhaust introduction port 101 has the heater 10
A pressure sensor 112 for detecting the exhaust pressure is attached to detect the regeneration time of the filter due to heating of 6. Next, the operation will be described. Device E detected by pressure sensor 112
When the exhaust pressure on the upstream side is below a predetermined value, the filter 104
The pressure loss due to is small, and it is judged that the collection amount of exhaust particulate has not reached the time when the filter needs to be regenerated (hereinafter referred to as regeneration time), and the exhaust particulate is continuously collected by the filter 104.

At this time, the exhaust enters the space inside the filter 104 from the exhaust inlet 101, flows out through the filter 104 to the outside, and during that time, the filter 104 collects the exhaust particulates contained in the exhaust. Exhaust gas that has flowed out to the outside of the filter 104 flows out from the downstream open end to the downstream exhaust pipe 103 through a gap with the heat shield 105, and is discharged into the atmosphere through a muffler (not shown).

The device E detected by the pressure sensor 112
When the exhaust pressure on the upstream side exceeds a predetermined value, it is determined that the filter regeneration time has been reached, and regeneration is performed. To regenerate the filter, first stop the engine and then turn on the regeneration switch 110.
It is started by driving the heater driving circuit 107 after turning N. That is, when the regeneration switch 110 is turned on, the regeneration timer relay 109 is activated and the heater 106 is energized for a predetermined time. When the heater 106 is energized and the temperature rises, the filter
The exhaust particles collected in 104 are heated and burned and removed, and the filter 104 is regenerated.

Here, the combustion air (oxygen) is covered by the air existing around the gap between the outer peripheral surface of the filter 104 and the heat shield 105, but if the gap is smaller than 5 mm, combustion occurs. As the above progresses, the oxygen in the gap becomes lean and the combustion does not proceed properly. In addition, the gap is 15
If it is larger than mm, it becomes impossible to burn out exhaust particulates adhering to the inner peripheral surface of the heat shield sheath 105 by the heat of the heater 106,
As a result, the radiant heat on the inner peripheral surface of the heat shield 105 cannot be fully utilized, so that exhaust particulate matter accumulated on the outer peripheral surface of the filter 104 remains unburned.

Therefore, by setting the gap C within the range of 5 to 15 mm, the amount of oxygen in the gap C necessary for completion of combustion is secured (because the gap C is 5 mm or more). At the same time, since the exhaust particulates adhering to the inner peripheral surface of the heat shield 105 can be burnt out (because the gap C is within 15 mm), the radiant performance of the inner peripheral surface can be kept good, and the radiant heat can be reduced. The exhaust particles accumulated on the outer peripheral surface of the filter 104 can be burned out sufficiently by sufficiently utilizing them.

FIG. 4 shows the unburned amount of exhaust particulate matter (PM) when the gap between the filter and the heat shield is changed. As shown in the figure, when the gap is in the range of 5 to 15 mm, it is clear that the amount of unburned exhaust particulate matter can be kept small by the various actions and effects described above. Further, in addition to the setting of the gap C, by setting the emissivity ε of the inner peripheral surface of the heat shield 105 facing the filter 104 to be smaller than 0.1, particularly good radiation performance can be exhibited. FIG. 5 shows the unburned amount of exhaust particulate matter (PM) when the emissivity ε of the inner peripheral surface of the heat shield is changed. As shown in the figure, it can be seen that when the emissivity ε is smaller than 0.1, the unburned amount of exhaust particulate can be further reduced. As a result, as shown in the figure, it is possible to burn out the exhaust particulates deposited on the filter with a heater power that is lower than that of the conventional one, making the device compact,
Power consumption can be reduced.

[0017]

As described above, according to the invention of claim 1, the gap between the inner peripheral surface of the heat shield and the outer peripheral surface of the filter is set to 5 mm.
By setting it to ~ 15 mm, it is possible to secure the oxygen necessary for completing the combustion in the gap even when the combustion of exhaust particulates by the heating means progresses, and the exhaust particulates adhering to the inner peripheral surface of the heat shield. Since the radiant heat of the inner peripheral surface of the heat shield is burned out, the exhaust fine particles deposited on the outer peripheral surface of the filter can be burned and removed satisfactorily.

Further, by setting the emissivity as in the second aspect of the present invention, the radiation performance of the heat shield is further enhanced, so that the combustion removal performance of exhaust particulates is further improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the configuration of an embodiment of the present invention.

FIG. 2 is a front view of a main part of the above embodiment.

FIG. 3 is a side view of the same main part.

FIG. 4 is a diagram showing a change in an unburned amount of exhaust particulate matter when a gap between a filter and a heat shield is changed.

FIG. 5 is a diagram showing changes in the unburned amount of exhaust particulates when the emissivity of the inner peripheral surface of the heat shield is changed. 104 Filter 105 Heat shield 106 Heater 107 Heater drive circuit 112 Pressure sensor

Claims (2)

[Claims] 1. A filter, which is provided in an exhaust passage of an internal combustion engine, for collecting fine particles in exhaust gas, wherein the exhaust fine particles collected by the filter are burned and removed by a heating means at a predetermined time. In an exhaust particulate treatment device for an internal combustion engine configured, a hollow cylindrical heat shield sheath is provided to cover the outer peripheral surface of the filter with a gap, and the gap between the inner peripheral surface of the hollow cylindrical pipe and the outer peripheral surface of the filter is arranged. An exhaust particulate treatment device for an internal combustion engine, characterized by being set within a range of 5 to 15 mm. 2. The hollow cylindrical tube has an emissivity of 0.1 on the inner peripheral surface.
The exhaust particulate treatment system for an internal combustion engine according to claim 1, wherein the temperature is (100 ° C) or less.