JPS59122721A - Filter regenerating device - Google Patents

Abstract

PURPOSE:To perform optimum regenerating treatment, by a method wherein, when hydrocarbon and carbon monoxide are introduced in and regenerated on the upstream side of a carbon particle filter, which carries a catalyst oxide and is mounted in the middle of the exhaust pipe of an engine, an introducing amount and an introducing time are controlled. CONSTITUTION:A filter container 4, catching carbon particle in exhaust gas, is mounted in the middle of an exhaust pipe 3 of a diesel engine 1. The detecting values of an exhaust gas temperature sensor 12, mounted to an exhaust pipe 3 on the upstream side of the filter container 4, and a pulse generator 9 operating in synchronism with rotation of an engine are inputted in a microcomputer 8, the optimum amount of petroleum injected is computed according to the temperature of exhaust gas and the number of revolutions, and an injection valve 5 is opened through a lead wire 14. As a result, the optimum amount of petroleum in a tank 7 is injected to the upstream side of the filter 4 with the aid of a pump 6 to regenerate the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to an apparatus for regenerating a filter that traps carbon particulates contained in diesel engine exhaust gas.

This type of filter includes a ceramic filter with a three-dimensional mesh structure (hereinafter referred to as a frame filter), or a wall-through tights ceramic filter (hereinafter referred to as below) in which plugs are alternately plugged at the inlet and outlet of the exhaust gas of the cell.
There are various types such as \Nicum filter). However, in these filters, when the number of carbon particulate traps increases to a certain extent, the back pressure increases, so in order to avoid this, it is necessary to periodically burn the trapped carbon particulates to regenerate the filter.

As a means of combustion of the carbon particles, there is a method of raising the exhaust gas temperature to 550 to 600° C. or higher, which is the combustion temperature of the carbon particles, that is, a method of raising the exhaust gas temperature by restricting the intake air or the exhaust gas. However, although it is possible to raise the exhaust gas temperature to such a high temperature when the vehicle is running at high speeds, it is not possible when the vehicle is running at low speeds. Another method for burning the carbon particles is to install a heater or burner at the exhaust gas inlet of the filter to ignite the carbon particles and propagate the combustion. However, even with this method, there is a problem in that in order to enable filter regeneration in the entire driving range, the configuration such as control of the exhaust gas flow rate and ignition timing or the ignition system becomes complicated. Furthermore, in any of the above methods, if the amount of captured carbon particles is small, ignition or combustion propagation will not be carried out well, and conversely, if the amount of captured carbon particles is too large, the temperature of the filter material will rise significantly and thermal deterioration will be severe.

Now, in general driving of a vehicle, the exhaust gas temperature is around 250 degrees Celsius, and in order to enable filter regeneration in the entire driving range,
It has been desired to develop a method for burning carbon particles at a temperature higher than that in the past. .

The inventors have already filed a patent application in 1983-21 by deceiving the above-mentioned points.
In No. 0576, a method for regenerating a filter was proposed because it is possible to regenerate the filter in the entire driving range and also performs stable combustion regardless of the amount of captured particulates. That is, in this regeneration method, an oxidation catalyst is provided in the filter, and 500 to 50,000 ppm is applied to the filter.
m hydrocarbons (HC) and carbon oxides (C
1. O) is introduced for 10 seconds to 5 minutes at an exhaust gas temperature of 150° C. or higher to oxidize the oxidation catalyst, and the carbon particles are combusted by the heat generated by this oxidation reaction. It is something that

However, when carrying out the above regeneration method, in order to regenerate the filter material and catalyst in an optimal state without deterioration, it is necessary to adjust the amount and timing of addition of HC and Co, etc. Therefore, it is necessary to select optimal conditions, and it is preferable to select an appropriate time for regeneration.

In view of the above points of the present invention, the purpose of this invention is to provide a device that can regenerate a filter under optimal conditions. IIC and (
or) a supply mechanism for introducing CO, and a control IQ for controlling the amount and time of introduction of He and/or CO.

The present invention will be explained below using illustrated embodiments.

FIG. 1 shows an exhaust gas 1'12.2 according to an embodiment of the present invention.
The outline of the diesel engine of t is shown, and the engine body 1
A filter container 4 is provided in the middle of an exhaust pipe 3 extending from an exhaust manifold 2 .

Inside the filter container 4 there is a diameter 130 mm as a filter phase.
A foam filter with a diameter of 13 meshes (the number of holes in the three-dimensional mesh is 13 holes/inch) with a length of 100 square meters is coated with an I? of 2 g per 1 ton of filter volume. Contains radium (pa).

An injection valve 5 facing into the exhaust pipe 3 is disposed between the engine body 1 and the container 4. This injection valve 5 has the same structure as a conventionally known fuel injection valve, and is adapted to supply light oil into the exhaust pipe 3 by opening the electromagnetic iR valve. In other words, the injection valve 5 has Ponzoro's υ, and the tank 7
The light oil inside is always fed at a constant pressure, and the amount of light oil injected is determined by the time the solenoid valve is opened. However, HC is introduced into the exhaust gas by the light oil.

The control circuit 8 controls the opening time of the electromagnetic pulp, that is,
This is a microconbeater that controls the amount and time of HC introduced into the exhaust gas, and its open time is controlled according to the engine speed and exhaust gas temperature. The pulse generator 9 is attached close to a crankshaft 10 protruding from the engine body 1, generates pulses in response to the rotation of the shaft 10, and outputs the pulses to the control circuit 8 via a lead wire 11. The control circuit 8 learns the engine rotation speed from this pulse. On the other hand, the exhaust gas temperature sensor 12 is installed close to the filter in the filter container 4, detects the exhaust gas temperature, and outputs it to the control circuit 8 via the lead wire 13.

Accordingly, the control circuit 8 calculates the amount of light oil into the exhaust pipe 3 based on the engine speed and exhaust gas temperature. ^Determine the shooting scene and open the injection valve 5 via the lead wire 14.

Next, the results of a filter regeneration experiment conducted using the apparatus of the above embodiment will be described. Note that a program was input into the control circuit 8, ie, the converter, in order to carry out the experiment according to the table procedure shown in (a), (b), (c), and (b) below.

In addition, the vehicle's running time and mother turn were set to 11 degrees.

(a) When the cumulative value of engine rotational speed reaches 10,000 g, prepare to regenerate the filter.

(b) 15 when the exhaust gas temperature is in the range of 250℃ to 450℃
When the injection continues for seconds, light oil is injected according to the main turn of the injection time shown in Fig. 2, and the filter is regenerated. At this time, the injection time is determined based on the exhaust gas temperature 16 seconds after the exhaust gas temperature reaches 250°C.

(c) During filter regeneration, if the exhaust gas temperature reaches 450°C or higher, stop the injection of diesel oil.

(2) After the injection of diesel oil is stopped and regeneration is complete, start integrating the engine speed again. Hereafter, (a), (b)
, (c), ni) are repeated.

However, when the engine is started, the pulse generator 9 operates and starts accumulating the number of rotations, but it was during the first lap of the second cycle of 11 laps that this accumulated value reached 10,000 g. . In other words, the above (a) prepares for regeneration of the filter, but since the exhaust gas temperature did not remain above 250°C for 15 seconds from the 1st to 9th lap of the second cycle, the injection of diesel oil was not possible. It wasn't done. However, when the running/main turn enters the 10th lap, the exhaust gas temperature reaches 320°C, and the control circuit 8 reaches 250°C.
After confirming that the above exhaust gas temperature continued for 15 seconds, light oil was injected from the injection valve 5 for 15 seconds.

At this time, the HC concentration (in terms of Ct) in the exhaust gas during regeneration is:
The concentration ranged from 4,500 to 6,000 ppm, and the temperature inside the filter was a maximum of 560°C.

After the above-mentioned regeneration process is completed, the filter is removed from the container 4 and the number # of the attached carbon particles is measured.
0.16 g/piece, and the captured carbon fine particles were substantially all burned by the above-mentioned regeneration treatment, and
It can be seen that regeneration was carried out at a relatively low temperature without deterioration of the filter material or catalyst. By the way, 1
From the average car water and particulate discharge ax during one lap and the collection efficiency of the filter material, the heavy band of carbon particulates captured by the filter from engine start to regeneration start is approximately 3.
It is estimated that there are 5,117 pieces.

The contents of the programs shown in (a), (b), (c), and (b) above are just examples, such as engine carbon particulate emission characteristics, exhaust gas temperature characteristics, filter material elongation characteristics, etc. Accordingly, the playback timing, playback conditions, etc. may be changed. However, when determining these regeneration conditions and regeneration timing, the following points must be kept in mind.

In other words, the gas temperature (d) has an important effect on the reaction between the injected light oil and the catalyst, and if the injection time of light oil is not controlled by this exhaust gas temperature, complete regeneration of the filter material will not be possible. Figure 3 confirms this, and shows that if the amount of carbon particles captured per filter is 5g, and the HC concentration in the exhaust gas is 500%.
The relationship between the HC injection time and the combustion rate of carbon particles in the case of 0 ppm is shown. As can be seen from this figure, the injection time of abrasive He, which has a high exhaust gas temperature, may be short.

Additionally, the regeneration timing of the filter is closely related to the amount of carbon particles captured; if the amount of captured carbon particles is too large, that is, if the regeneration cycle is too long, the temperature inside the filter will rise significantly due to the heat generated during combustion of the carbon particles. This may cause the filter material or catalyst to deteriorate. Figure 14 shows this, where the exhaust gas temperature is 200°C and the HC concentration in the exhaust gas is 5.
10 shows the relationship between the amount of captured carbon particles and the temperature inside the filter in the case of 000 ppm.

In the above program, diesel oil is not injected when the exhaust gas temperature is 450°C or higher.
This is because at temperatures above 450°C, the carbon particles begin to burn due to the effect of the catalyst supported on the filter, and in fact, HC
There is no need to add
If HC is added to a pigeon house at a temperature of 0°C or higher, the temperature of the filter material will rise significantly and the filter material or catalyst will deteriorate.

In addition, as a means of detecting the amount of captured carbon particles,
In addition to using the integrated value of the engine rotation speed as in the above n1 example, it is also possible to use the mileage of the vehicle, or the magnitude of the pressure loss of exhaust gas due to the filter material. It is not limited to these means.

Further, the hydrocarbon source supplied to the exhaust gas does not necessarily have to be light oil, and may be, for example, methanol, ethanol, etc., and the supply mechanism is not limited to an injection valve.

Furthermore, the HC may be supplied to the exhaust pipe; for example, a hydrocarbon source may be injected into the cylinder immediately after the engine's explosion process, and HC may be supplied to the exhaust pipe. , the hydrocarbon source injected into the cylinder is decomposed by the heat inside the cylinder, resulting in a mixture of CO and HC.

Both CO and HCldl have an angle of I on the fill surface.
Since it reacts with sand and generates heat, the same effect as in the above example can be obtained.

The catalyst provided in the filter may be any catalyst such as Pd, ronium, platinum, or iridium, as long as it promotes the oxidation of IC or CO. Furthermore, it is configured to supply only CO without supplying HC to the exhaust gas. 1. You can.

Needless to say, the present invention can also be applied to a two-cam filter.

As described above, according to this research, the filter regeneration process is
The effect can be obtained that the process can be carried out under optimal conditions with little deterioration of the filter material or the filter material.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing one embodiment of the present invention, Fig. 2 is a graph showing the turn of light oil injection time with respect to exhaust gas temperature, and Fig. 3 is a graph showing HC injection time and carbon oil injection time under various engine conditions. A graph showing the 1JA relationship with the combustion rate of particles,
FIG. 4 is a graph showing the relationship between the amount of captured carbon particles and the temperature inside the filter. 3... 1 drain pipe, 5... Injection valve (supply mechanism),
- Control circuit (control mechanism), 9... pulse generator. Patent issued, applicant: Toyota Motor Corporation, patent attorney: Akira Aoki, patent attorney, Kazuyuki Nishidate, patent attorney, Kyo Nakayama, patent attorney, Akira Yamaguchi (Φ1r2:ζ) :3. ．． ．． ．． :, 2 :': )-, t,; Exhaust gas temperature (℃) 3rd Yi? J 12345 HC injection time (minutes) 吋L 4 'r':;・j 0 5 10 2030 Amount of fine particles (ψ)

Claims (1)

[Claims] 1. A filter supporting an oxidation catalyst and installed in the middle of the exhaust pipe of a diesel engine to capture carbon particles,
The regeneration device includes a temperature detection mechanism installed in the exhaust pipe to detect exhaust gas temperature, and introduces hydrocarbons and (i)-carbon oxide into the engine exhaust system upstream of the filter. and a control mechanism that controls the amount and time of introduction of hydrocarbons and/or carbon oxides. 2. The filter regeneration device according to claim 1, further comprising carbon detection means for detecting the amount of carbon particles captured by the filter. 3. A filter townhouse device according to claim 2, characterized in that the carbon detection means is a means for detecting an integrated value of engine rotational speed. 4. Carbon detection means detects heavy vehicle running p[i Iaf '
! ) The playback device according to claim 2, characterized in that it is a means for knowing cedar. 5 Special nHF (required range 2nd
Filter regeneration device as described in Section 1.