JPS59150921A - Trap regenerating device in exhaust gas purifying device for diesel engine - Google Patents

Abstract

PURPOSE:To provide a trap regenerating device capable of performing sufficient combustion of fine exhaust gas particles by a method wherein a throttling of intake gas is performed in a high speed range of engine and either a secondary fuel injection or both of a secondary fuel injection and a throttling of intake is performed. CONSTITUTION:When a computer 9 judges that the engine is at a high speed range in reference to signals from a load sensor 17 and a rotation sensor 18, the instruction is transmitted to the load change-over valves 6 and 7 to close an intake throttle valve 3 until it shows a desired pressure of an intake pressure sensor 20. When the computer 9 judges that the engine is at a low or medium speed range, fuel is secondary injected into cylinders of intial exhaust stroke through the change-over valves under instruction for the computer to increase temperature in a trap 10 and to combust the exhaust fine particles. When a sensor 11 for exhaust gas temperature detects that a rate of increased temperature is insufficient in the trap 10, the computer 9 produces an instruction to close the intake throttle valve 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an exhaust gas purification device for a diesel engine, and more particularly, it relates to an exhaust gas purification device for a diesel engine, and more particularly to a device for purifying the exhaust gas of a diesel engine. ) t@ Appropriate collection material such as filter element by internal method (
Torasof is a diesel engine exhaust purification device suitable for collecting the collected exhaust particulates in a trap containing a filler, incinerating the collected exhaust particles in all cycles, and completely regenerating the filler.

Regarding a playback device.

Conventional technologyExhaust particulates contained in the exhaust gas of diesel engines are flammable like carbon particles.
# The following methods are conventionally known for incinerating particles to regenerate the collection material, and each method has the following drawbacks. -■ A method of throttling the intake system of a diesel engine to reduce the amount of intake air and raise the temperature of the exhaust gas to burn exhaust particulates. With this method, the exhaust temperature rises sufficiently in the high speed range of the engine, making it possible to incinerate the exhaust particulates, but in the low and medium speed ranges, the exhaust temperature does not rise sufficiently, making it difficult to incinerate the exhaust particulates and regenerate the collection material. becomes impossible.

■ A method in which an electric heater is placed over the entire surface of the filter, and the exhaust gas collected on the surface of the filter is combusted, and the downstream particulates are self-combusted using this as a heat source.

In this method, since the paper heater is attached to the entire surface of the filter, the power consumption is very large, and in order to reduce the power consumption, various measures are required and the cost is also high.

On the other hand, in order to solve the above-mentioned problems, Ippon Yamatojin first developed a multi-cylinder diesel engine with a trap that collects exhaust particulates and burns them in the exhaust pipe. The fuel passages of at least one set of cylinders in which the explosion stroke and exhaust stroke overlap are connected via a communication passage, and a part of the fuel to the explosion cylinder is directly delivered to the exhaust pipe during combustion regeneration of the particulate-trapping drug. into the cylinder, i.e. into the cylinder 2.
We have proposed a trap regeneration device for a diesel engine exhaust purification device that performs secondary injection and thereby causes high-temperature exhaust gas to flow into a particulate collection trap. However, even in such a system that performs two-day in-cylinder injection, regeneration of the filter in the trap is still not sufficient in the low and medium engine speed ranges, regardless of the high speed range of the engine, and countermeasures for this point have been desired.

Purpose of the Invention The present invention has been devised in view of the unresolved problems of the in-cylinder secondary injection method proposed by Gansei Hinimotoyama, and has been devised in view of the problems of the prior art as described above. The reason is that the exhaust gas temperature can be raised to burn the exhaust particulates in the filter without requiring electricity, and the exhaust particulates can be burned sufficiently not only in the high-speed range of the engine but also in the low-to-medium speed range. It is an object of the present invention to provide a trap regeneration device in an exhaust gas purification device for a diesel engine that can be used in a diesel engine.

Structure of the Invention In order to achieve the above object, the present invention includes a valley sensor that detects each of the load, rotation speed, and exhaust temperature, a comviator to which the detection signals of these sensors are input, and the opening and closing of which is controlled by this computer. a secondary fuel injection mechanism that is controlled by the same computer and injects fuel into the cylinder during its exhaust stroke, and an unburned fuel reaction installed in the drag in the control airway. Equipped with a catalyst, it throttles the intake air in the high speed range of the engine, and doubles in the low and medium speed range.
A trap regeneration device in an exhaust purification device for a diesel engine is characterized in that it performs both secondary fuel injection or secondary fuel injection and intake throttling.

Example Embodiments of the present invention will be described below with reference to the drawings.

In Fig. 1, l is the diesel engine body, 2 is the fuel injection pump, and this fuel injection bonder 2 not only supplies fuel to each cylinder as usual, but also supplies secondary fuel during the exhaust stroke of a specific cylinder. The mechanism is described later. Reference numeral 3 designates an intake throttle valve provided in the intake passage, which is opened and closed by a diaphragm 4 for driving the intake throttle 9. This diaphragm 4 is operated by negative pressure from a vacuum pump 5. ing. 6 and 7 are vacuum switching pulse type negative pressure switching valves (abbreviated as vSv) provided in the negative pressure passage 8 that connects the vacuum pump 5 and the diaphragm 4 for driving the nine intake throttle valves. The operation of the diaphragm 4 for driving the nine intake throttle valves is controlled depending on whether negative pressure or atmospheric air is introduced into the intake throttle valve. The negative pressure switching valves 6, 7 are both connected to a combinator 9, and based on commands from the computer 9, switching between the negative pressure and the atmosphere is controlled as described above. The reason why two negative pressure switching valves are provided is not only to simply control the opening and closing of the intake throttle valve 9 valve 3 on and off, but also to freely adjust the degree of opening and closing by controlling the duty ratio of the opening and closing. be. 1o is a trap installed in the exhaust passage, which contains a filter made of foamed sedimic and similar filtrate, and further contains unburned gas (C0) on the surface of this filter.
, 1 (C, etc.) A catalyst for t-reaction combustion is provided. The filter in this trap has a three-dimensional mesh structure, through which the exhaust gas can flow, and exhaust particulates such as carbon contained in the exhaust gas can be collected between the meshes. is now possible. 11
is an exhaust gas temperature sensor provided in the exhaust passage, and its exhaust temperature detection signal is input to the computer 9. 12 is the pie A installed in the exhaust path? The valve is operated by a diaphragm 13 for driving the valve. The diaphragm 13 for moving the Binosos valve is connected to the vacuum pump 5 via a negative pressure switching valve 14, and the negative pressure switching valve 14 is connected to a computer 9 and controlled according to instructions thereof.

15 is a υF air gas pressure sensor installed downstream of the trap 10, which is connected to the computer 9, detects the pressure of exhaust gas, inputs the signal to the computer 9,
The necessity of reproducing 0 is determined. In addition, the judgment of drag regeneration is made by integrating the engine rotation speed.
The computer 9 may issue a command when a certain integrated number of rotations is reached. 16 is an engine cooling water temperature sensor, 17 is a load sensor, 18 is a rotation sensor, 19 is a throttle opening sensor, and 20 is a suction pressure sensor, and the detection signals of these sensors are inputted to the computer 9. ing. 21 is an exhaust gas recirculation valve.

FIG. 2 shows the piping configuration of the secondary fuel injection for sending high-temperature exhaust gas to the trap 1o in this embodiment.
3.S4 fuel injection nozzle 22A.

Fueling 22B, 22C, 22D takes place via fuel passages 23, 25, 27.29'lt in the usual way.

By the way, in the case of a multi-cylinder engine, the explosion stroke and exhaust stroke of one set of cylinders always overlap.

In other words, taking a four-cycle case of a four-cylinder engine as an example, the results are as shown in Table 1 below.

Table 1 In the table above, each letter means the following process.

Pressure...compression, explosion...explosion, exhaust...exhaust, suction...
As is clear from the intake table 1, when the first cylinder (=#1) is in the explosion stroke, the second cylinder (11-2) is in the exhaust stroke,
Similarly, the explosion of the 2nd cylinder and the exhaust of the 4th cylinder, the explosion of the 3rd cylinder (S3) and the exhaust of the 1st cylinder, and the explosion of the 4th cylinder (S4) and the exhaust of the 3rd cylinder overlap, respectively. are doing. Therefore, in this embodiment, the fuel passages of one or more sets of cylinders in which explosion and exhaust overlap are connected to each other via a communication passage. The fuel passage 23 for the 1st cylinder and the fuel passage 25 for the 2nd cylinder are connected to each other, and the fuel passage 27 for the 3rd cylinder and the fuel passage 29 for the 4th cylinder are connected to each other by 24.28't. - connected through. In these communication passages 24 and 28, there are passages from the explosion cylinders (S1 and S4) to the exhaust cylinder (#2).
and (3) check valves 33, 37 are provided which allow fuel flow only in the direction towards the side. Check valve 33, 37
may be a check valve known per se, for example a spring-loaded one-way check valve. Furthermore, switching ff31.35 is provided in these communication passages 24.28. The switching valves 31, 35 are known per se, for example solenoid granger two-way solenoid valves, and are connected to the communication passage 24 based on control numbers from the computer 9.
The opening/closing is controlled at 281°. That is, the switching valve 31
The valve 35 is normally kept in the closed position, and is opened by the computer 9 only when the trap is regenerated. This switching valve 31.
Reference numeral 35 is provided to make the fuel passages of the valley cylinders independent from each other except during trap regeneration, and to allow the original fuel supply to be carried out to the engine.

The operation of this embodiment having the above configuration is as follows.

During engine operation, the computer 9 determines whether or not the trap 10 needs to be regenerated based on the detection result of the exhaust gas pressure sensor 15 installed downstream of the trap 10.

Then, when the time when the drug 10 needs to be regenerated comes, the operation is started.

When the detection signal from the load sensor 17 and the rotation sensor 18, the computer 9, determines that the engine is in the high-speed range, a command of 7 is transmitted to the negative pressure switching valves 6 and 7, and these negative pressure switching valves switch to the atmospheric boat. is closed, the negative pressure from the paquim bong 5 passes through the negative pressure passage 8 and the negative pressure switching valves 6 and 7 and acts on the diaphragm 4 for driving the intake throttle 9 valve, thereby causing the intake throttle multi-valve 3 to be connected to the intake pressure sensor 20. Close until target pressure is reached. Generally, when the intake air is throttled, excessive pressure decreases and the temperature of the exhaust gas increases, so the intake pressure sensor 2
The target pressure of 0 is set to a suction pressure that can obtain the exhaust gas temperature necessary to burn the exhaust particulates in the trap 10. (The fuel temperature of exhaust particulates such as carbon is approximately 6
00°C, but if a catalyst is installed, the combustion temperature will drop even further. ) As a result, the co-air gas flow rate flowing into the trap 10 rises to the exhaust particulate combustion temperature, the particulates collected in the filter are combusted, and the drag function can be regenerated. At this time, the throttle opening sensor 19 detects the throttle opening, and if the opening exceeds the set value (the load is heavy 71ij), the computer 9 commands the bypass via the negative pressure switching valve 14. Negative pressure is introduced into the valve driving diaphragm 13, the bypass valve 12 is opened, and the pressure loss given to the engine 1 by the drag 10 is reduced. In this way, in the high speed range, by throttling the intake air, the temperature of the exhaust gas can be increased and the exhaust particulates in the trap can be combusted.

- When it is determined that the engine is in the low-medium speed range by the detection of the force, load sensor 17, and rotation speed sensor 18, the switching valve 31 and switching valve 3 are
5t - Since the valve is opened, a part of the fuel in the fuel passage 23 to be injected just before the explosion stroke of the #1 cylinder flows into the fuel passage 25 via the communication passage 24 while opening the check valve 33. Secondary injection is also performed into the #2 cylinder from the fuel injection nozzle of the cylinder. At this time, the two cylinders have completed their explosion stroke and are in the beginning of their exhaust stroke, but the fuel injected into the two cylinders comes into contact with the high temperature combustion gas from the explosion stroke that remains in the cylinder, resulting in CO, H,
This generates C and is discharged into the exhaust passage.

In exactly the same way, when the #4 cylinder explodes, part of the fuel for the #4 tank is supplied to the #3 cylinder during the exhaust stroke, resulting in Co, H,
C is generated and discharged into the exhaust passage. And this C
O,HCt--A reaction is caused by the action of the catalyst in the trap 10, and the internal temperature of the trap 10 is raised by the generated heat, thereby incinerating the exhaust particulates collected by the filter. In this case, if the exhaust temperature riser 11 detects that the temperature rise in the trap 10 is insufficient, the computer 9 issues a command to switch the negative pressure switching valves 6 and 7 and Negative pressure is introduced into the intake throttle multiple valve driving diaphragm 4 to control the intake throttle valve 3 in the direction of closing,
It acts to further increase the exhaust gas temperature. In this way, in the engine low and medium speed range, the temperature inside the trap 10 is increased by the reaction heat of the unburned gas generated by the secondary injection of fuel, and if the temperature rise is still insufficient, the intake air is further increased. Throttling can be used to increase exhaust gas temperature and incinerate exhaust particulates within the drag.

Although the above secondary injection of fuel was performed between two sets of cylinders, it is not necessarily performed between two sets of cylinders, and may be performed only between one set of cylinders.

In addition to the above-mentioned combinations of explosion cylinders and exhaust cylinders, possible combinations include 2 cylinders and 4 cylinders, 2 cylinders and 1 cylinder, etc.

Effects of the Invention As explained above, the present invention uses a combination of intake throttle, secondary fuel injection into the cylinder, and catalyst in the drag, so that only the intake throttle is used in the engine high speed range. In the low-to-medium speed range, secondary fuel injection within the cylinder is used, or if this is insufficient, additional intake throttling is applied.
Since the exhaust gas temperature can be raised to a temperature at which fine particles can be combusted, the trap can be regenerated sufficiently in all operating ranges of the engine, reducing longitudinal force consumption and improving durability and safety. According to the present invention, a drag regeneration device for a diesel engine exhaust purification device with excellent performance, relatively simple structure, and low cost can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing the entire embodiment of the present invention, and FIG. 2 is a fuel piping diagram for secondary fuel injection in the same embodiment. DESCRIPTION OF SYMBOLS 1... Diesel engine main body, 2... Fuel injection pump, 3... Intake throttle valve, 9... Computer, 1
゜...Trap, 11...Exhaust temperature sensor, 17...
・Load sensor, 18... Rotation sensor, 2o... Suction pressure sensor, 23.25, 27.29... Fuel passage,
24, 28...Communication path, 31.35...Switching valve,
33.37...Check valve.

Claims (1)

[Scope of Claims] 1. Each sensor that detects each of the load, rotation speed, and exhaust temperature, a computer into which the detection signals of these sensors are input, and an intake throttle p whose opening and closing are controlled by this computer. The engine is equipped with a valve, a secondary fuel injection mechanism whose operation is controlled by the computer and injects fuel into the cylinder during the exhaust stroke of the cylinder, and an unburned gas reaction catalyst installed in a trap in the exhaust path. A trap restriction system in an exhaust purification device for a diesel engine that performs intake throttle υ in the normal speed range and performs secondary fuel injection or both secondary fuel injection and intake throttle in the same medium and low speed range. 2. The formation of the secondary fuel injection mechanism allows fuel to flow only from the explosion cylinder side toward the exhaust cylinder side between the fuel passages of at least one set of cylinders in which the explosion stroke and exhaust stroke overlap. Track regeneration in a diesel engine exhaust purification system according to claim 1, which is connected through a communication passage having a reverse valve and is provided with a valve that opens only during trap regeneration in this communication passage. Device.