JPS58202324A - Exhaust gas purifier of diesel engine - Google Patents

Abstract

PURPOSE:To improve efficiency by feeding the fuel used by a burner device from the pressure chamber of a fuel injection pump so that the blinding of a filter member is dissolved by means of the combustion gas from the burner device as well as the exhaust gas itself. CONSTITUTION:The upstream end of a fuel feed passage 19 of a burner device 13 is connected to a pressure chamber 5 in a fuel injection pump 2. A normally- closed solenoid-type open/close valve 30 which opens or closes the fuel feed passage 19 is arranged in the middle of the fuel feed passage 19. A battery 26 is connected to this open/close valve 30 through a normally-opened swtich 31 controlled by a driving circuit 29, and the switch 31 is closed and the open/ close valve 30 is opened by means of burner device operation signals fed from the driving circuit 29, thereby the fuel in the pressure chamber 5 of the fuel injection pump 2 is fed to the burner device 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust purification device for a diesel engine,
In particular, the present invention relates to an improvement in an exhaust passage in which a filter member for collecting particulates in the exhaust gas and a burner device for eliminating clogging of the filter member are provided.

Generally, the exhaust gas of a diesel engine contains a large amount of particulates such as carbon particles. Conventionally, a filter member formed in a honeycomb shape or the like is disposed in the exhaust passage of an engine as an exhaust purification device that prevents these particulates from being released directly into the atmosphere.

It is well known that the filter member is used to collect particulates in the exhaust gas.

However, in this type of engine, when the engine is operated for a long period of time, the filter member becomes clogged due to the accumulation of particulates, and the exhaust pressure of the engine increases by 1-1, causing a decrease in its output. There is.

When the exhaust temperature is high, the accumulated particulates are naturally combusted by the exhaust gas heating, and the clogging of the filter member is resolved. However, since the exhaust gas temperature varies depending on the engine operating conditions, exhaust heating alone is not enough. It cannot be expected that the clogging will be cleared.

Therefore, conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 49-71315, fuel is ignited and combusted in combustion air on the upstream side of the filter member to generate high-temperature combustion gas. A burner device configured as described above is installed, and the burner device is activated periodically or when the filter member becomes clogged, and the fine particles deposited on the filter member are heated and burned by the high-temperature combustion gas. Accordingly, a filter has been proposed that can reliably eliminate clogging of the filter member.

By the way, there is a demand for the above-mentioned burner device to operate in the shortest possible time to reduce the amount of fuel consumed by the burner device, but the proposed method described in -1- naturally has a limit due to its structure. .

The present invention has been made to meet the above-mentioned requirements.The present invention has been made to meet the above-mentioned requirements.In a diesel engine, there is normally one type of fuel that controls the fuel injection timing by changing the hydraulic pressure of the fuel in accordance with the engine rotation speed in a pressure chamber contained therein. Taking advantage of the fact that the burner device is equipped with an injection pump, the fuel used in the burner device is configured to be fed from the pressure chamber of the fuel injection pump, so that the fuel injection timing can be adjusted to the normal injection timing when the burner device is in operation. The engine exhaust temperature is increased later, and the filter member is unclogged not only by the combustion gas from the burner device, but also by the exhaust itself, thereby improving its efficiency, thereby shortening the operating time of the burner device. This is the purpose.

For this purpose, the configuration of the present invention is to introduce fuel whose hydraulic pressure increases and decreases depending on the increase and decrease of the engine speed into a pressure chamber, and to operate a piston according to the fuel hydraulic pressure in the pressure chamber. A fuel injection pump is provided with a timer mechanism that advances the fuel injection timing when fuel pressure increases due to operation, and a filter member is disposed in the exhaust passage to collect fine particles such as carbon particles in the exhaust gas. and a burner device for eliminating clogging of the filter member is provided in the exhaust passage on the upstream side of the filter member, and a burner device for supplying fuel to the burner device into a pressure chamber in the fuel injection pump. By connecting a fuel supply passage and providing an on-off valve in the fuel supply passage that opens upon receiving a burner device activation signal, when the burner is turned off, the fuel fluid pressure in the pressure chamber of the fuel injection pump is reduced by supplying fuel to the burner device. This is to reduce the fuel injection timing and delay the fuel injection timing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on embodiments shown in the drawings.

1 to 3, 1 is a diesel engine, and the engine 1 is equipped with a distribution type fuel injection pump 2 that injects fuel into each cylinder of the engine 1 driven by the engine 1. .

The fuel injection pump 2 has a built-in timer mechanism 6 that controls fuel injection timing according to the engine speed.

That is, as shown in enlarged detail in FIG. 3, the timer mechanism 3 changes the engine speed by operating a feed pump (not shown) connected to a drive shaft 4 that rotates in synchronization with the engine 1. A pressure chamber 5 (inner pump space) into which fuel is guided, whose hydraulic pressure increases and decreases accordingly, and operates according to the fuel hydraulic pressure in the pressure chamber 5, and when the fuel hydraulic pressure is low, it is activated by the biasing force of the timer spring 6. When the timer piston 7 moves to the right in the figure and the fuel pressure becomes high (the timer piston 7 moves to the left against the biasing force of spring B).

- a roller holder 9 rotatably disposed around the drive shaft 4 and connected to the timer piston 7 via a pin 8; a roller 10 rotatably supported by the roller holder 9; 10. It is equipped with... In addition, a cam disk (both not shown) integrally fixed to a plunger that sucks in, pressure-feeds and distributes fuel is in pressure contact with the rollers 10, 10°, etc. as the engine speed increases. When the fuel pressure in the pressure chamber 5 increases, the timer piston 7 moves to the left in the figure, causing the roller holder 9 to move.
Rotate the roller clockwise to rotate the roller 10°10.
It operates to control the fuel injection timing in a direction that advances the fuel injection timing by relatively changing the contact position between the cam surface and the cam surface of the cam disk.

111''i An exhaust passage for discharging exhaust gas from the engine 1, with an exhaust passage 11 disposed in the middle of the exhaust passage 11.
A honeycomb-shaped filter member 12 is provided to collect fine particles such as carbon particles in the exhaust gas flowing through the exhaust gas.

Further, a burner device 16 is disposed in the exhaust passage 11 on the upstream side of the filter member 12 to eliminate clogging of the filter member 12 due to accumulation of particulates. The burner device 1
3, as shown in enlarged detail in FIG. 2, includes a cylindrical casing 14 with one end closed, and an exhaust passage 11 fitted into the casing 14 with a certain gap 15 between the casing 14 and the casing 14. air having a combustion chamber 16 in communication with the combustion chamber 16 and allowing the wall portion to communicate the gap 15 and the combustion chamber 16;
'・ Supply hole 17, 17. ... is formed with the combustion tube 18.

The casing 1 is placed so that the tip faces the combustion chamber 16.
a fuel supply nozzle 20 provided at the closed end of the fuel supply nozzle 20 and having a fuel supply passage 19 formed therein in the axial direction (lζ);
A pair of casings 14 and combustion cylinders 18 are penetratingly supported by each side wall, and disposed so that their respective tips face each other at a predetermined interval in front of the discharge port 21 at the downstream end of the fuel supply passage 19 of the fuel supply nozzle 20. The spark plug 22 has electrodes 22a, 22a. The gap 15 between the casing 14 and the combustion cylinder 18 is defined by the air supply passage 2.
The spark plug 22 is connected to an air pump 24 through a normally open switch 25, and the spark plug 22 is connected to a battery 26 through a normally open switch 25. The air pump 24 discharges air from the air supply holes 17.17. ...
The air mixture is mixed with air blown into the combustion chamber 16 from the ignition plug 22 and ignited and combusted by discharge ignition by the spark plug 22 to generate high-temperature combustion gas. The clogging of the filter member 12 is eliminated by heating and burning the particulates accumulated on the filter member 12.

On the other hand, inside the filter member 12, there is a pair of electrodes 2 facing each other at a constant interval in the axial direction (exhaust flow direction).
7.27 is buried through the passage wall of the exhaust passage 11,
Each of the electrodes 27Fi is connected to a clogging detector 28 that detects the clogging state of the filter member 12 based on a decrease in the resistance value between the electrodes 27 and 27 due to fine particles (carbon particles) deposited on the filter member 12. The output of the clogging detector 28 is transmitted from the air pump 24. It is input to a drive circuit 29 that drives and controls each of the switch 25 and a drive phase switch 61 of an on-off valve 60, which will be described later.
The drive circuit 29 is activated by the detection signal of the detector 28 to activate the air pump 24, and the switch 25 is closed.
Furthermore, the opening/closing valve 6o is configured to open and thereby control the operation of the burner device 16.

The upstream end of the fuel supply passage 19 of the burner device 16 is connected to the pressure chamber 5 within the fuel injection pump 2. Further, a normally closed electromagnetic on-off valve 60 that opens and closes the fuel supply passage 19 is disposed in the middle of the fuel supply passage 19. A battery 26 is connected via a switch 61.

The burner device operation signal outputted from the drive circuit 29 closes the switch 31 and opens the on-off valve 60, so that fuel in the pressure chamber 5 of the fuel injection pump 2 is supplied to the burner device 16.

In FIG. 2, 62 is a ring-shaped throttle attached to the inner periphery of the combustion tube 18 so as to protrude into the combustion chamber 16, and is connected to the air supply holes 17, 17 . This is to increase the flow velocity of the air blown into the combustion chamber 16 from ... to increase the mixing efficiency with the fuel. Further, 36 is an auxiliary air supply passage formed in the fuel supply nozzle 20 so as to surround the fuel supply passage 19.

Its upstream end opens into the gap 15 between the casing 14 and the combustion cylinder 18, and its downstream end opens into the discharge port 21 at the tip of the nozzle 20. Air is blown out from the discharge port 21 to atomize the fuel. This is to improve mixing efficiency with air, and also to cool the fuel in the fuel supply passage 19 to prevent clogging of the nozzle 2o.

Next, to explain its operation, fine particles such as carbon particles in the exhaust gas flowing through the exhaust passage 11 as the engine 1 operates are collected by the filter member 12, thereby purifying the exhaust gas and releasing it into the atmosphere. Ru. Further, when the filter member 12 is not clogged, the switch 31 is opened and the on-off valve 60 of the fuel supply passage 19 is closed due to the inoperation of the clogging detector 28 and the drive circuit 29 while the engine 1 is operating. As a result, the fuel hydraulic pressure in the pressure chamber 5 of the fuel injection pump 2 increases or decreases in accordance with the engine speed as usual, and the fuel injection timing is controlled by the operation of the timer mechanism 6, so that the engine 1 decreases. During rotation, the fuel injection timing is delayed due to a drop in fuel hydraulic pressure within the pressure chamber 5.

When the engine 1 is running at high speed, as shown in Figure 3+a+,
An operation is performed to advance the fuel injection timing by increasing the fuel hydraulic pressure within the pressure chamber 5.

Then, after a certain period of time has elapsed, the filter member 12 becomes clogged due to the accumulation of the fine particles.

The clogging detector 28 detects the change in the resistance value between the electrodes 27 and 27 and outputs a detection signal, and the drive circuit 29 is activated by this detection signal.
9, the opening/closing valve 60 opens through the closing operation of the sui-nochi 31, and the fuel in the pressure chamber 5 of the fuel injection pump 2 is supplied to the burner device 16, and the air pump 24 is activated to supply combustion air. The spark plug 22 is supplied to the burner device 13 and the spark plug 22 is activated by closing the switch 25, so that the burner device 16 is activated. This burner device 13
The high-temperature combustion gas generated in the combustion chamber 16 is circulated to the filter member 12 on the downstream side and heats and burns the particulates accumulated on the filter member 12, thereby eliminating clogging of the filter member 12. .

In that case, the fuel used in the burner device 16 is extracted from the pressure chamber 5 of the fuel injection pump 2 and fed as described above. As the fuel pressure decreases, the timer mechanism 6 is kept delayed from the injection timing suitable for the engine speed at that time, as shown in FIG. 3) bl. This means that the combustion conditions of the engine 1 deviate from the normal state, resulting in poor combustion efficiency.As a result, the exhaust temperature rises, and the particulates deposited on the fill member 12 are removed by the high temperature exhaust heat. Therefore, due to the synergistic effect with the operation of the burner device 16, the clogging of the filter member 12 can be efficiently cleared (and completed in a short time).

When the filter member 12 is cleared of clogging in this way, the clogging detector 28 stops operating, the burner device 16 stops operating and returns to its original state, and the opening/closing valve 60
Due to the closing operation, the timer mechanism 6 of the fuel injection pump 2 comes to operate normally.

Therefore, since the fuel used in the burner device 16 is supplied from the pressure chamber 5 within the fuel injection pump 2 in this way, it is possible to efficiently eliminate clogging of the filter member 12.

Reliability can be improved by eliminating the need for a dedicated fuel pump for the burner device as in the past;
The fuel system can be simplified.

In the above embodiment, the fuel in the pressure chamber 5 in the fuel injection pump 2 is directly fed to the burner device 13 and discharged from the nozzle 20, but the fuel pressure in the pressure chamber 5 and the burner device If the difference between the fuel discharge pressure and the required fuel discharge pressure in the fuel supply passage 16 is too large, it may be dealt with by providing a pressure reducing regulator in the middle of the fuel supply passage 19.

Further, in the above embodiment, the clogging state of the filter member 12 is detected by a pair of electrodes 27 disposed on the filter member 12.
In this embodiment, the change in the resistance value between 27 and 27 is detected, but the detection may be performed by looking at the increase in exhaust pressure on the upstream side of the filter member. Furthermore, the present invention does not operate the burner device by detecting the clogged state of the filter member as described above (instead of activating the burner device by detecting the clogged state of the filter member), the burner device is activated periodically at a certain operating time of the engine, a certain mileage of the automobile, etc. Of course, the present invention can also be applied to an exhaust gas purification device that is operated.

As explained below, according to the present invention, a diesel engine is equipped with fuel for use in a device for eliminating clogging of a filter member that collects particulates in exhaust gas of a diesel engine. By feeding fuel from the pressure chamber of the fuel injection pump, when the burner is operating, the fuel pressure in the pressure chamber is lowered and the fuel injection timing is delayed compared to normal conditions, resulting in a lower exhaust temperature.
] Since the particulates accumulated on the filter member can be heated not only by the combustion gas from the burner device but also by the exhaust gas itself, the filter member can be efficiently cleared from clogging (and the burner device can be activated). The time can be shortened, and fuel consumption can be reduced accordingly.Also.

Since a dedicated fuel supply mechanism for the burner device is not required, the fuel supply system can also be simplified.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall explanatory view, and FIG. 2 is an enlarged longitudinal cross-sectional view of a burner device. FIGS. 3 (fat and fbl) are explanatory views of the operation of the timer mechanism in the fuel injection pump when the shield device is inactive and in operation, respectively. Diesel engine, 2.Fuel injection pump. 6. Timer mechanism, 5. Pressure chamber, 7. Timer piston % 11. Exhaust passage, 12. Filter member, 1
6 burner device, 19... fuel supply passage, 28... clogging detector, 29... drive circuit, 60... opening/closing valve.

Claims (1)

[Claims] (1) Fuel whose hydraulic pressure increases or decreases depending on the increase or decrease in engine speed is introduced into a pressure chamber, a piston is operated according to the fuel hydraulic pressure in the pressure chamber, and when the fuel hydraulic pressure increases due to the operation of the piston. The fuel injection pump is equipped with a timer mechanism that controls the fuel injection timing in a direction that advances the fuel injection timing, and a filter member that collects fine particles such as carbon particles in the exhaust gas is disposed in the exhaust passage, and the exhaust gas on the upstream side of the filter member is disposed in the exhaust passage. In a diesel engine in which a burner device for eliminating clogging of a filter member is provided in a passage, a fuel supply passage for supplying fuel to the burner device is connected to a power chamber in the fuel injection pump, and a fuel supply passage for supplying fuel to the burner device is connected. An exhaust purification device for a diesel engine, characterized in that a fuel supply passage is provided with an on-off valve that opens in response to a burner device activation signal.