JPH018648Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention relates to a burner for regenerating a trap for collecting exhaust particulates used as an exhaust purification device for an internal combustion engine.

<Background technology> Conventionally, as an exhaust purification device for an internal combustion engine, a trap is installed in the middle of an exhaust passage to collect particulates (particulates) whose main component is carbon in the exhaust, and a predetermined amount of particulates are collected in the trap. There is a device in which a burner installed upstream of the trap is activated to heat the exhaust gas when the particles are collected, thereby incinerating the fine particles in the trap and regenerating the trap. issue).

Burners suitable for regenerating traps include those shown in FIGS. 1 and 2. This was previously proposed by the present applicant (Utility Application No. 58-38324, Utility Application No. 58-25026).

To explain this, a trap case 2 is interposed in the middle of an exhaust pipe 1 of a diesel engine, and a honeycomb type trap 4 is installed inside the trap case 2 with a buffer material 3 interposed therebetween. and,
A burner case 5 is interposed upstream of the trap case 2, and a burner 6 is housed within the burner case 5. The burner 6 includes a combustion tube 7 having an open downstream end and a plurality of exhaust inlet holes 7a in the downstream peripheral wall, a closed upstream end connected to the upstream end of the combustion tube 7, and a combustion tube 7 having a closed upstream end. A flame holding tube 10 with an open downstream end, and a reverse flow type evaporator tube having a large number of air-fuel mixture injection holes 9a on the upstream peripheral wall and a combustion leakage hole 9b on the lower surface at an intermediate position within the flame holding tube 10. 9, and a mixture conduit 8 which passes through the burner case 5, the flame holding tube 10, and the peripheral wall of the evaporator tube 9 in this order, is bent in the axial direction of the evaporator tube 9 within the evaporator tube 9, and opens at the end thereof. , an ignition glow plug 11 that passes through the combustion tube 7 and the flame holding tube 10 and faces the downstream side of the air-fuel mixture jet hole 9a and below the combustion leak hole 9b, and the glow plug 11 and the combustion leak hole 9b. A glow cover seal 12 that covers the surrounding area is included.

Incidentally, when the trap 4 is regenerated, fuel is supplied to the mixture conduit 8 from, for example, a fuel injection valve (not shown), and air is also supplied from, for example, an air pump via an on-off valve (both not shown). It is becoming more and more like this.

Here, when playing trap 4,
After the glow plug 11 is energized to raise the temperature to the temperature required for ignition, fuel and air are supplied to the mixture conduit 8.

As a result, the mixture of fuel and air is ejected from the air-fuel mixture conduit 8 into the evaporator cylinder 9 and flows in the opposite direction within the evaporator cylinder 9. At this time, in a diesel engine, the exhaust temperature is low and the evaporation temperature of the light oil that is the fuel is high (requires approximately 300°C or higher), so before ignition, part of the fuel becomes a liquid stream and flows from the fuel leak hole 9b to the glow plug. 11 leaks and ignites, which becomes a spark that ejects from the air-fuel mixture jet hole 9a and ignites most of the air-fuel mixture that reaches the glow plug 11. Then, the flame is fed into the combustion tube 7 while being promoted within the flame holding tube 10. As a result, the exhaust gas flowing in from the many exhaust gas inflow holes 7a of the combustion tube 7 is heated, and the fine particles collected in the trap 4 are combusted by the heated exhaust gas.

After ignition, the flame held by the flame holding tube 10 heats the evaporation tube 9 to promote vaporization of the fuel flowing inside the evaporation tube 9, and the flame held by the flame holding tube 10 heats the evaporation tube 9. Therefore, the part 8a of the air-fuel mixture conduit 8 is heated to promote vaporization of the fuel there, thereby achieving stable combustion. Therefore, after ignition, power supply to the glow plug 11 is stopped.

Then, after a predetermined period of time has elapsed, the supply of fuel and air is stopped to complete the regeneration of the trap 4.

However, in the trap regeneration burner described above, the mixture conduit 8 is passed through the peripheral wall of the flame holding cylinder 10 and the peripheral wall of the evaporator cylinder 9, and is bent in the axial direction of the evaporator cylinder 9 inside the evaporator cylinder 9. Since this configuration is installed in a horizontal position, there are the following problems.

That is, the upstream circumferential wall of the evaporator tube 9 has a penetrating portion for the mixture conduit 8, and since it is not possible to provide the mixture jet hole 9a in this penetrating portion, the mixture jet hole 9a is not connected to the periphery of the evaporator tube 9. Cannot be placed evenly in the direction.
As a result, the amount of air-fuel mixture ejected from the air-fuel mixture outlet 9a becomes uneven, the gas temperature distribution in front of the trap 4 becomes uneven, and there is a problem that the trap 4 cannot be regenerated uniformly.

In addition, a part 8a of the mixture conduit 8 is heated, and the vaporization of the fuel is promoted here. However, when the vaporization of the fuel is promoted, the flame propagation becomes faster, and the mixture is ejected from the evaporator pipe 9a. There is a problem that flame easily enters the evaporator tube 9, increasing the risk of burning out the evaporator tube 9.

<Purpose of the invention> In view of the above-mentioned problems, the present invention aims to improve the installation structure of the air-fuel mixture conduit so that the trap can be regenerated efficiently, and the air-fuel mixture can be ejected from the air-fuel mixture outlet in the evaporator cylinder. The purpose is to prevent flame blowback and burnout of the evaporator tube by specifying the speed and nozzle diameter.

<Configuration of the invention> For this reason, in the present invention, the mixture conduit is passed through the peripheral wall of the flame holding cylinder, bent in the axial direction of the evaporator cylinder, and then exposed to the inside of the evaporator cylinder. The air-fuel mixture jet speed from the hole is set at 10 m/s or more, and the air-fuel mixture jet hole diameter is set at 2.5 mm or less.

<Example> Examples will be described below. In FIG. 3, the same elements as those in FIG. 2 are designated by the same reference numerals.

To explain a different configuration from the embodiment shown in FIG. After being bent in the direction, the upstream closed end wall of the evaporator tube 9 is penetrated, and the end thereof is opened. Therefore, the bent portion 8b of the mixture conduit 8 is located within the flame holding cylinder 10 and is exposed to the flame of the flame holding cylinder 10.
Further, the air-fuel mixture jet holes 9a of the evaporator tube 9 are arranged evenly in the circumferential direction upstream of the fuel leak holes 9b. Further, the air-fuel mixture ejecting speed from the air-fuel mixture jetting hole 9a is set to 10 m/s or more, and the diameter of the air-fuel mixture jetting hole 9a is set to 2.5 mm or less.

According to this configuration, the bent portion 8 of the air-fuel mixture conduit 8
b is located in the flame holding tube 10, so that even at low speeds and low loads when the exhaust temperature is low and the amount of fuel supplied is low, the mixture is ejected from the mixture nozzle 9a of the evaporator tube 9 at the same time as ignition, and the flame holding tube is ejected from the flame holding tube. The bent portion 8b of the air-fuel mixture conduit 8 is heated by the flame held by the evaporator 10, and the vaporization of the fuel is promoted there. Therefore, in addition to the vaporization of the fuel within the evaporator tube 9, sufficient vaporization performance is achieved. is obtained. Incidentally, since the bent portion 8b of the mixture conduit 8 is longer than the portion 8a of the conventional mixture conduit 8 shown in FIG. 2 located within the flame holding cylinder 10, the vaporization of the fuel is further promoted.

Further, by the configuration in which the mixture conduit 8 is bent and then penetrated through the upstream closed end wall of the evaporator tube 9, the evaporator tube 9
Since there is no penetrating portion of the air-fuel mixture conduit 8 in the upstream peripheral wall of the air-fuel mixture, the air-fuel mixture jetting holes 9a can be arranged evenly in this upstream peripheral wall, and there is no unevenness in the amount of air-fuel mixture jetted out. . As a result, trap 4
The previous gas temperature distribution is made uniform, and the trap 4 can be regenerated uniformly under any operating conditions.

Furthermore, as mentioned above, when the vaporization of the fuel is promoted, the flame propagation becomes faster, and the flame easily enters the evaporator tube 9 from the air-fuel mixture jet hole 9a installed in the evaporator tube 9, causing the evaporator tube 9 to burn out. This increases the risk of the air-fuel mixture blowing out from the air-fuel mixture outlet 9a by setting the air-fuel mixture blowing speed from the air-fuel mixture outlet 9a to 10 m/s or more.
By setting the hole diameter of a to 2.5 mm or less, it is possible to prevent the flame from entering the evaporator tube 9 due to the cooling effect of the wall surface even at low speed and high load when the air supply amount from the air pump is at its lowest. The risk of burnout can be avoided.

Here, the air-fuel mixture jet hole diameter (mm) and the air-fuel mixture jet speed (m/s) obtained through experiments by the present inventors.
FIG. 4 shows a graph showing the relationship between the temperature and the temperature inside the evaporator cylinder (°C).

The temperature inside the evaporator cylinder (° C.) was obtained using position A shown in FIG. 5 as the measurement position.

From this graph, the air-fuel mixture injection speed (m/s) is
Set the speed to 10m/s or more, and adjust the mixture nozzle diameter (mm).
By setting it to 2.5 mm or less, the temperature inside the evaporator cylinder (°C) can be kept lower than the upper limit of the material heat resistance temperature (1000°C) of the evaporator cylinder 9 and mixture conduit 8, and it is clear that the above-mentioned effect can be obtained. It is.

If the air-fuel mixture jet hole 9a is set to prevent flame blow-back as described above, the flame will not blow out due to an increase in the air-fuel mixture jet speed even in the engine's maximum operating speed range where the air pump has the largest amount of air. Does not occur.

<Effects of the invention> As explained above, according to the invention, the mixture conduit is made to pass through the inside of the flame holding cylinder, and is made to face the inside of the evaporation cylinder after being bent in the axial direction of the evaporation cylinder, and
The air-fuel mixture injection speed and air-fuel mixture injection hole diameter from the air-fuel mixture injection hole in the evaporator tube are set so as to prevent flame blowback, which promotes fuel vaporization and eliminates variations in the amount of air-fuel mixture ejected. The trap can be regenerated efficiently under any operating conditions. Furthermore, since there is no flame blowback, it is possible to prevent the evaporator cylinder from burning out.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of an exhaust gas purification device equipped with a trap and burner showing the prior art, Fig. 2 is a partially cutaway perspective view of the same burner, and Fig. 3 is an embodiment of the burner according to the present invention. A partially cutaway perspective view showing an example, Fig. 4 is a graph showing the relationship between the air-fuel mixture injection velocity and air-fuel mixture nozzle diameter, and the temperature inside the evaporator cylinder, and Fig. 5 is a measurement of the temperature inside the evaporator cylinder in the same graph as above. FIG. 3 is a longitudinal cross-sectional view of the burner showing its position. DESCRIPTION OF SYMBOLS 1... Exhaust pipe, 4... Trap, 5... Burner case, 6... Burner, 7... Combustion tube, 7a... Exhaust inflow hole, 8... Air mixture conduit, 9... Evaporator tube, 9a... Mixture nozzle, 10... Flame Holding tube, 11...Glow plug.

Claims (1)

[Scope of utility model registration request] A combustion tube disposed upstream of a trap inserted in the exhaust passage to collect particulates in the exhaust gas and having an exhaust inflow hole in the peripheral wall; and a combustion tube located upstream of the combustion tube and opening into the combustion tube. Composed of a flame holding cylinder, a reverse flow type evaporation cylinder located inside the flame holding cylinder and having a mixture jet hole in a peripheral wall, and a mixture conduit that protrudes into the evaporation cylinder and has an open end. In a burner for regenerating a trap for collecting exhaust particulates of an internal combustion engine, the mixture conduit is passed through the peripheral wall of the flame holding cylinder, bent in the axial direction of the evaporator cylinder, and then exposed to the inside of the evaporator cylinder. , a burner for regenerating a trap for collecting exhaust particulates, characterized in that the air-fuel mixture jetting speed from the air-fuel mixture jetting hole of the evaporator cylinder is set to 10 m/s or more, and the diameter of the mixture jetting hole is set to 2.5 mm or less. .