JPS60216019A - Exhaust gas particulate processing device in internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent from a fuel injection valve, etc. from being damaged by burning, by providing, in the vicinity of the fuel injection valve, a selector valve device which communicates between an air supply passage and a mixture supply passage upon operation of a burner while communicates between the air supply passage and an air relieving passage upon resting of the burner. CONSTITUTION:The downstream end of an air supply passage 26 is communicated with a mixture supply passage 23 in the vicinity of the jet port of a fuel injection valve 24, and as well an air relieving passage 29 is communicated with the mixture supply passage 23. An air stream selector valve device 28 closed the air relieving passage 29 upon operation of a burner so that the mixture of fuel and air is fed to the burner through the mixture supply passage 23: Further, it closes the mixture supply passage 29 downstream of the air relieving passage 29 upon resting of the burner so that air passes in the vicinity of the jet port of the fuel injection valve and flows into the air relieving passage 29.

Description

[Detailed description of the invention] Technical fields> This article relates to an exhaust particulate treatment device for an internal combustion engine.

<Prior art> In internal combustion engines such as diesel engines that are equipped with a trap in the exhaust passage to collect particulates such as carbon contained in the exhaust, when the amount of particulates collected in the trap increases, the exhaust pressure increases excessively. , the exhaust particulates collected in the trap are
- The trap was regenerated by heating and burning it.

A conventional example of such an exhaust particulate treatment device is shown in FIG. 1 (see Japanese Patent Application No. 58-8659 and Japanese Patent Application No. 58-8660).
.

That is, a trap case 3 is interposed in the middle of the exhaust pipe 2 of the diesel engine 1, and a trap (not shown) for collecting exhaust particulates is housed in the trap case 3. Further, a burner (not shown) for heating and burning the exhaust particulates collected by the trap is housed in the trap case 3 upstream of the trap.

An opening at the downstream end of the mixture supply passage 4 faces the burner, and a gaseous fuel noise valve 5 is attached to the upstream end of the mixture supply passage 4. Fuel (e.g., light oil, which is the same as engine fuel) is introduced to the fuel injection valve 5 from a fuel tank (not shown) via a fuel supply passage 7 by an electromagnetic fuel pump 6 . Further, in the middle of the air-fuel mixture supply passage 4, an air supply passage 10 is connected to a discharge port of an air pump 8 via an air tyrephragm type three-way valve 9.

The driving section of the three-way valve 9 is configured to be supplied with negative pressure air from a vacuum pump 11 via a solenoid valve 12. When the trap is regenerated, the tortoise valve 12 is opened in response to a signal from the control device 13 to supply negative pressure air to the three-way valve 9.
Air is supplied from the share pump 8 to the mixture supply passage 4 by opening the air supply passage 10 with the three-way valve 9, while at other times, by closing the solenoid valve 12. The air supply passage 10 is closed by the three-way valve 9 to stop the air supply. When this air supply is stopped, the discharge port and suction port of the air pump 8 are communicated with each other.

During trap regeneration, a mixture of fuel injected from the fuel injection valve 5 and air supplied through the air supply passage 10 is supplied to the burner through the mixture supply passage 4, and this mixture is preheated. A glow plug (not shown) is ignited to start the combustion operation of the burner. As a result, the combustion gas and exhaust gas are mixed, and the high-temperature gas flows into the trap to heat and burn the exhaust particulates.

Note that 14 is a pressure control valve.

However, in such a conventional exhaust particulate treatment device, since the nozzle hole of the fuel injection valve 5 is far from the confluence of the air-fuel mixture supply passage 4 and the air supply passage 7, there is Air was not introduced and fuel tended to accumulate near the nozzle holes. In addition, since the downstream end opening of the mixture supply passage 4 faces the burner, high-temperature exhaust gas flows backward through the mixture supply passage 4 when the burner is not in operation, and immediately after the burner has stopped operating, flames are emitted from the burner. In some cases, the mixture entered the air-fuel mixture supply passage 4. The intrusion of these flames or the backflow of high-temperature exhaust gas causes the fuel injection valve 5 to burn out.

This may cause clogging of the nozzle hole, thermal deterioration of a portion of the needle cover, and ignition of fuel accumulated near the nozzle hole, which may also cause burnout of the fuel injector 5, etc. The durability of the 5th grade was reduced.

Furthermore, when the burner is not in operation, air can always flow into the mixture supply passage 4 from the air supply passage 10 to prevent flame intrusion or backflow of high-temperature exhaust gas, but in this case, the glow plugs and burner However, there is a problem in that the ignition performance deteriorates due to excessive cooling.

<Object of the Invention> In view of the current situation, an object of the present invention is to provide an exhaust particulate treatment device that prevents burnout of fuel injection valves and the like while preventing a decrease in the ignition performance of a burner.

<Structure of the Invention> For this reason, the present invention provides a method for connecting the downstream end of the air supply passage to the mixture supply passage near the nozzle hole of the fuel injection valve, and also connecting the air release passage to the mixture supply passage, An air flow switching valve device is provided that closes the air relief passage when the burner is in operation, and closes the mixture supply passage downstream of the air relief passage when the burner is not in operation. When the burner is in operation, a mixture of fuel and air is supplied to the burner through the air-fuel mixture supply passage, while when the burner is not in operation, air is passed through the vicinity of the nozzle hole of the fuel injection valve and flows out into the air relief passage. This is how it was done.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIGS. 2 and 3 show an embodiment of the present invention.

In the figure, a trap case 2 is located in the middle of the exhaust passage 21.
2 is interposed, and this trap case 22 houses a trap (not shown) for collecting exhaust particulates. Further, a burner (not shown) collected by the trap is housed in a trap case 22 upstream of the trap.

A downstream end opening of the mixture supply passage 23 faces the burner, and a fuel injection valve 24 for injecting fuel into the mixture supply passage 23 is attached to the upstream end of the mixture supply passage 23. . Fuel is supplied to the fuel injection valve 24 from, for example, a fuel pump via a fuel supply passage 25. Air is supplied to the mixing supply passage 23 near the nozzle hole of the fuel injection valve 24 as shown in FIG. The downstream end of the passage 26 is connected to the air supply passage 26, and the upstream end of the air supply passage 26 is connected to a discharge port of an air pump 27 driven by the engine. The upstream end of the air relief passage 29 is connected through a chamber of a later-described tire arphragm type switching valve 28 as a valve device, and the downstream end of the air relief passage 2 is connected to the intake passage 31 downstream of the air cleaner 30. is connected to.

Also, as shown in FIG. 3, the diaphragm 2 of the switching valve 28
A rod 28b is attached to one side of the chamber 8&, and a box-shaped valve body 28e is attached to the tip of this rod 28b. A negative pressure passage 32 is connected to the other chamber of the switching valve 28, and a three-way switching valve 33 is interposed in the negative pressure passage 32. The three-way switching valve 33 is switched and controlled by an operating signal from the control device 34, and supplies negative pressure air to the other chamber of the switching valve 28 when the burner is in operation, and supplies negative pressure air to the other chamber of the switching valve 28 when the burner is not in operation. Configured to vent to the atmosphere.

In the switching valve 28, when negative pressure air is supplied at the beginning of burner operation, the valve body 28e moves downward against the biasing force of the spring 28d as shown in FIG. 3, and the air release passage 29 closes. The supply passage 26 is configured to communicate with the burner via the mixture supply passage 23, and a mixture of injected fuel and air from the fuel injection valve 24 is supplied to the burner when the burner is operated. In addition, when the burner is not in operation, the valve body 28C of the switching valve 28 moves upward as shown in FIG. When the burner is not in operation, air is made to flow around the nozzle hole of the fuel injection valve 24 and flow out into the intake passage 31 via the air relief passage 29.

The control device 34 receives a cooling water temperature signal, an engine rotation speed signal, a differential pressure signal across the trap, a trap inlet salinity signal, and an outlet temperature signal, and based on these signals, the control device 34 operates. Determine the regeneration timing of the trap and operate the fuel injection valve 24. It is configured to output an actuation signal to the switching valve 28, 33 and the glow plug.

Incidentally, 35 is a holder for a fuel valve.

In such a configuration, when the burner starts operating, the switching valve 33
Negative pressure air is supplied to the diaphragm type switching valve 28 through the diaphragm type switching valve 28, and the valve body 28c of the switching valve 28 is moved downward as shown in FIG. Accordingly, the air supply passage 26 is connected to the mixture supply passage 23.
Since the fuel injection valve 24 communicates with the burner through the fuel injection valve 24, a mixture of injected fuel and air from the fuel injection valve 24 is supplied to the burner through the mixture supply passage 23. Then, the air-fuel mixture is ignited and combusted by a glow plug preheated in the burner, and the exhaust particulates collected in the exhaust trap are heated and combusted by the mixed gas of the combustion gas and the exhaust gas.

When the burner is not in operation, the negative pressure air of the switching valve 28 is released by the switching valve 33 to move the valve body 28e upward as shown in FIG. At the same time, the mixture supply passage 23 is closed. Then, air is supplied from the air supply passage 26 to the fuel injection valve 2.
The air flows around the nozzle hole 4 and flows out into the air release passage 29. At this time, since the nozzle hole of the fuel injection valve 24 is isolated from the downstream part of the air-fuel mixture supply passage 23 by the valve body 28e, exhaust gas or the flame immediately after the burner operation is stopped does not flow back to the vicinity of the nozzle hole. Also, when the burner is not in operation, the fuel injection valve 24
Since air is made to flow around the nozzle holes, the fuel injection valve 24 and the upstream wall of the air-fuel mixture supply passage 23 are cooled.

Therefore, it is possible to prevent burnout of the fuel injection valve 24 and thermal deterioration of a portion of the shade cover that clogs the nozzle hole portion of the injection valve 24, thereby improving the durability of the fuel injection valve 24.

Further, since air is circulated near the nozzle hole of the fuel injection valve 24, fuel does not accumulate near the nozzle hole, and ignition combustion of the accumulated fuel can be prevented. Further, since the air-fuel mixture supply passage 23 is closed by the valve body 28c when the burner is not in operation, air supply to the burner is stopped and the burner and glow plug are not cooled, thereby preventing deterioration in ignition performance.

FIG. 5 shows another embodiment of the invention.

In this embodiment, an air supply passage 26 is connected to the mixture supply passage 23 near the nozzle hole of the fuel injection valve 24, and an air relief passage 26 is connected to the mixture supply passage 23 downstream of this communication portion.
The upstream ends of 9 are connected in communication. A plate-shaped valve body 3 is provided on the wall of the communication portion between the mixture supply passage 23 and the air relief passage 29.
6 is attached so that it can swing freely, and this switching valve 36 is attached to the link member 3.
7 to the tire-flamm type drive unit 38. When the burner is in operation, the valve body 36 is moved as shown in FIG. The air-fuel mixture supply passage 23 is closed by moving the air-fuel mixture. Here, the valve body 36, the link member 37, and the guiaphragm 38 constitute a switching valve device.

This embodiment also provides the same effects as the embodiments described above.

<Effects of the Invention> As explained above, the present invention supplies a mixture of fuel and air to the burner when the sipana is activated by operating the switching valve device, while supplying air to the fuel injection valve when the burner is not activated. Since the exhaust gas flows around the nozzle hole of the fuel injection valve and flows out to the air relief passage without being supplied to the burner, it prevents the backflow of exhaust gas to the vicinity of the nozzle hole of the fuel injection valve and the intrusion of flame immediately after the burner stops operating. At the same time, the injection hole portion of the fuel injection valve can be cooled. Therefore, burnout of the fuel injection valve, clogging of the injection hole, thermal deterioration of a portion of the needle cover, etc. can be prevented, and the durability of the fuel injection valve can be improved. Furthermore, since the air supply to the burner is stopped when the burner is not in operation, the burner or the glow plug is not cooled and deterioration in ignition performance can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example of an exhaust particulate treatment device, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is an enlarged view of part A in Fig. 2, and Fig. 4 shows the action of the line. Diagram to explain, No. 5
The figure is a sectional view of a main part showing another embodiment of the present invention. 21... Exhaust passage 23... Mixture supply passage 24.
...Fuel injection valve 26...Air supply passage 2B...
Diaphragm type switching valve 29... Air relief passage patent
Applicant Nissan Motor Co., Ltd. Agent Patent Attorney Fujio Sasashima Figure 3 Figure 4 Figure 5 q

Claims (1)

[Claims] a burner provided in the exhaust passage to heat and burn exhaust particulates captured by the trap; a mixture supply passage whose downstream end faces the burner and supplies a mixture to the burner; and an upstream side of the mixture supply passage. An exhaust particulate treatment device for an internal combustion engine, comprising: a fuel injection valve connected to an end of the fuel injection valve for supplying fuel into a mixture supply passage; and an air supply passage supplying combustion air to the mixture supply passage; A downstream end of the supply passage is connected in communication with a mixture supply passage near the nozzle hole of the fuel injection valve, and an air relief passage is connected in communication with the mixture supply passage, and the air relief passage is closed when the burner is operated. 1. An exhaust particulate treatment device for an internal combustion engine, comprising an air flow switching valve device that closes a mixture supply passage downstream of an air relief passage when a burner is not in operation.