JPH036807Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Conventional technology> In internal combustion engines, especially diesel engines, low
The concentration of particulates (carbon, etc.) emitted at medium speeds and high loads tends to increase as the air-fuel ratio of the air-fuel mixture becomes richer, so there are many particulates under driving conditions in this region, such as when accelerating or climbing hills. is ejected outside the vehicle,
It can easily cause pollution and poor visibility.

Therefore, the particulates contained in the exhaust gas are collected in a trap and re-burned to prevent them from being released into the atmosphere. A conventional example of such an exhaust particulate treatment device is shown in FIG.
(See Publication No. 102408).

That is, a catalyst type trap 3 for collecting exhaust particulates is interposed in the middle of the exhaust passage 2 of the engine 1, and the collected exhaust particulates are combusted by its catalytic action. However, this catalytic action does not work well in all operating ranges, but is activated in high exhaust temperature ranges (engine high load operating ranges), so in low exhaust temperature operating ranges, exhaust gas passes through trap 2. It is made to be discharged without any waste.

That is, a bypass passage 4 that bypasses the trap 3, an exhaust temperature sensor 8 as an exhaust temperature detection means, and a valve device 5 that selectively opens the bypass passage 4 and the exhaust passage 2 in which the trap 3 is interposed.
and a control unit 9 as a valve device control means for controlling the operation of the valve device 5. When the exhaust gas temperature detected by the exhaust gas temperature sensor 8 is below a predetermined value, the control unit 9 controls the operation of the valve device 5. The valve device 5 is actuated by a signal from 9, and the exhaust passage 2 is closed and the bypass passage 4 is opened.

The operation of the valve device 5 is performed by switching the negative pressure path switching valve 6 in response to a signal from the control unit 9 and guiding negative pressure to the diaphragm 7.

<Problems to be solved by the invention> However, as mentioned above, exhaust particulate treatment is carried out by the trap's catalytic action only in the operating range where the exhaust gas temperature is high. In the area,
Exhaust particulates will be emitted into the atmosphere without being treated.

That is, the catalytic action of the trap is e.g.
Since it is activated at temperatures above 400°C, if the exhaust temperature is below this temperature, the trap is bypassed and the exhaust is discharged into the atmosphere. However, as shown in Figure 4, even in the operating range (low-speed, middle-speed, high-load range) where the exhaust temperature is below 400°C, many particulates are contained in the exhaust (the shaded area in Figure 4), and as a result, A large amount of fine particles will be emitted into the atmosphere.

To solve this problem, if the predetermined exhaust temperature (400℃) for opening the bypass passage is set low,
In areas where the trap's catalytic action is insufficient, a large amount of particulates will be collected by the trap, and the collected particulates will not be re-combusted and will accumulate, resulting in an increase in exhaust pressure and a decrease in engine output and fuel efficiency. There is a risk that this could lead to In addition, there is a risk that a large amount of particulates collected in areas where the trap's catalytic action is insufficient may cause damage to the trap due to rapid re-combustion when the catalytic action is activated as the exhaust temperature rises. There is also.

The present invention solves the above-mentioned disadvantages, and even in the region where the trap's catalytic action is not activated (operating region where the exhaust temperature is low), the exhaust particulates can be effectively processed without causing a decrease in engine output or fuel efficiency. The aim is to reduce the amount of exhaust particulates emitted into the atmosphere in all operating ranges.

<Means for Solving the Problems> Therefore, the present invention includes an additive supply means for supplying an additive that promotes the oxidation of exhaust particulates to the intake passage of the engine, and a means for controlling the additive supply means to supply the additive. and an additive control means for controlling the additive supply means according to an output signal from the additive supply means in an operating region where the exhaust gas is discharged bypassing the trap when the exhaust temperature is below a predetermined value. Activate it to supply additives to the engine's intake passage.

<Operation> As a result, in an operating region where the exhaust temperature is low and the trap's catalytic action is insufficient, the exhaust gas is guided to the bypass passage and the additive is supplied to the intake passage of the engine. The supplied additive acts as a catalyst for oxidation of particulates during combustion in the combustion chamber, during the exhaust stroke, and in the exhaust passage, thereby reducing particulates. On the other hand, in a region of high exhaust gas temperature where the trap's catalytic action is activated, the exhaust gas is guided to the trap and particulates are re-burned as in the conventional system.

In this way, exhaust particulates can be effectively reduced not only in the operating range where the trap's catalytic action is activated, but also in other operating ranges, reducing the amount of particulates emitted into the atmosphere in all operating ranges. can be reduced. Furthermore, since exhaust gas is guided to the trap only in the operating range where the trap's catalytic action is activated, an increase in exhaust pressure due to particulate deposition can be prevented, and a decrease in engine output and fuel efficiency can be avoided. Furthermore, since the additive is supplied only to a limited operating range, the amount of additive discharged to the outside can be kept to a very small amount.

<Examples> Examples of the present invention will be described below based on the drawings. Note that the same elements as those in the conventional example are given the same reference numerals and the explanation thereof will be omitted.

In FIG. 1, an injector 12 as an additive supply means is provided in an intake passage 20 of an internal combustion engine 1, and sprays into the intake passage 20 an additive that promotes oxidation of exhaust particles. Additives (e.g. to solvents)
(dissolved Mn compound, etc.) is stored in a tank 13, and pumped to the injector 1 by a pump 14.
2.

Further, in this embodiment, the amount of discharged particulates is detected and the additive is supplied in accordance with the detected amount. Therefore, as a means of detecting particulate emissions,
For example, the fuel injection pump 10 is provided with a fuel injection pump lever opening sensor 11 and an engine rotation speed sensor 15, and the control unit 19 is configured to preset the amount of particulate emissions based on the detected values of both sensors. Let me remember it. As a result, when the outputs of both the sensors 11 and 15 are input to the control unit 19, the amount of particulate emissions corresponding to the detected values is retrieved.

Furthermore, the output of the exhaust gas temperature sensor 8 as exhaust temperature detection means is input to the valve device control means in the control unit 19, and the exhaust temperature detected by the exhaust temperature sensor 8 is set to a predetermined value as in the conventional example. If the value is below the value, the valve device 5 triggers the trap 3.
A bypass passage 4 that bypasses the trap 3 is opened to prevent exhaust gas from passing through the trap 3. As for the exhaust gas temperature detection means, the exhaust temperature according to the operating conditions is preset and stored in the control unit 19 in the same manner as the particulate emission amount detection means, and the exhaust temperature is searched based on the detection result of the operating conditions. You can also do it.

In such a configuration, when the exhaust gas temperature detected by the exhaust gas temperature sensor 8 is below a predetermined value, that is, when the exhaust gas is guided to the bypass passage 4, and when the particulate emissions are searched based on the detection values of both the sensors 11 and 15, When the amount exceeds a predetermined value (the shaded area shown in FIG. 4), the additive control means in the control unit 19 controls the injector 12.
is activated to supply a predetermined amount of additive to the intake passage 20 corresponding to the amount of particulate emissions. The supplied additive enters the combustion chamber of the engine 1 from the intake passage 20,
During combustion in the combustion chamber, during the exhaust stroke, and in the exhaust passage including the bypass passage 4, it acts as a catalyst against the oxidation of exhaust particulates and reduces the particulates.

Figure 2 shows the effect of additives on reducing exhaust particulates. This shows the relationship between the exhaust temperature and the amount of exhaust particulates when the engine is operated at low speed (rotation speed 1600 rpm).The higher the exhaust temperature, the greater the particulate reduction effect of additives, but the effect of trap 3's catalytic action is It can be seen that exhaust particulates can be sufficiently reduced even at temperatures below the activation temperature (for example, 400°C).

Furthermore, as mentioned above, the control unit 19
constitutes particulate discharge amount detection means, and also serves as additive control means and valve device control means.

As explained above, according to this embodiment, in the operating range where the exhaust gas temperature is high, the catalytic action of the trap 3 is activated, so that the exhaust gas is guided to the trap 3 and the catalytic action reduces exhaust particulates.
On the other hand, in an operating range where the exhaust gas temperature is low and the catalytic action of the trap 3 is insufficient, the exhaust gas is guided to the bypass passage 4 as in the conventional example, and if an amount of exhaust particulates exceeding a predetermined value is detected at this time, , an additive corresponding to the amount of particulates is supplied to the intake passage 20 of the engine 1, and the exhaust particulates are reduced by the catalytic action of the additive.

Therefore, it is possible to satisfactorily reduce exhaust particulates in the entire operating range of the engine, and there is no risk of the exhaust particulates accumulating in the trap 3, increasing the exhaust pressure, and reducing the output and fuel efficiency of the engine.

In addition, since the trap 3 and additives are configured to reduce exhaust particulates, the amount of additives used is small compared to the case where exhaust particulates are reduced only by additives, and the tank 13 for additives is small. It is possible to reduce the occurrence of deposits using additives. Furthermore, since the additive is supplied only to a limited operating range, the amount of additive discharged to the outside is very small.

In this embodiment, a particulate emission amount detection means is provided and an additive corresponding to the detected amount is supplied to the intake passage, but a fixed amount of additive is supplied when the bypass passage is opened. It is clear that it is also possible to use the method without providing a particulate emission amount detection means.

<Effects of the invention> As described above, according to the invention, when the exhaust gas temperature is below a predetermined value and the catalytic action of the trap is insufficient, the exhaust gas is guided to the bypass passage that bypasses the trap, and this bypass passage is opened. Additives that promote the oxidation of exhaust particulates are sometimes supplied to the engine's intake passage. On the other hand, in an operating range where the exhaust gas temperature is above a predetermined value and the trap's catalytic action is activated, the exhaust gas is introduced into the trap to burn particulates.

As a result, exhaust particulates can be effectively reduced in the entire operating range of the engine. Further, exhaust particulates are not deposited in the trap, and a decrease in engine output and fuel efficiency due to an increase in exhaust pressure can be prevented. Also,
Since additives are supplied only to a limited operating range, the amount of additives discharged to the outside can be kept to a very small amount.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a graph showing the effect of reducing exhaust particulates by supplying additives, Fig. 3 is a block diagram showing a conventional example, and Fig. 4 is a graph showing exhaust particulates by trapping. It is a graph showing the relationship between the treatment area and the amount of exhaust particulate matter discharged. DESCRIPTION OF SYMBOLS 1... Internal combustion engine, 2... Exhaust passage, 3... Trap, 4... Bypass passage, 5... Valve device, 8...
...Exhaust temperature sensor, 12...Injector, 19
...Control unit, 20...Intake passage.

Claims (1)

[Scope of utility model registration request] A catalyst-type trap that is installed in the exhaust passage of an engine and collects and burns particulates in the exhaust, a bypass passage that bypasses the trap, and an exhaust passage that is equipped with the trap and the bypass passage are selectively selected. a valve device for opening the bypass passage when the exhaust gas temperature is below a predetermined value detected by the exhaust temperature detection means; a valve device control means for controlling the valve device; an additive supply means for supplying an additive that promotes oxidation of exhaust particulates to the intake passage of the engine; An exhaust particulate treatment device for an internal combustion engine, comprising: additive control means for supplying additives.