JPH0330571Y2 - - 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.

<Prior art> There is a conventional example of an exhaust particulate treatment device for an internal combustion engine as shown in Fig.
(See No. 192996).

That is, a trap for collecting exhaust particulates is interposed in the exhaust passage 2 of the diesel engine 1, and a catalyst is attached to the trap to form a catalyst-equipped trap 3. An exhaust bypass passage 4 is formed to bypass the catalyst trap 3. A first on-off valve 5 that opens and closes the exhaust passage 2 and a second on-off valve 6 that opens and closes the exhaust bypass passage 4 are provided at the confluence of the exhaust passage 2 and the exhaust bypass passage 4. These first and second on-off valves 5 and 6 are interlocked and driven to open and close by a diaphragm actuator 7, and when negative pressure air is introduced into the negative pressure chamber 7a, the diaphragm actuator 7 opens and closes the first on-off valve. At the same time as the valve 5 is driven to open, the second on-off valve 6 is driven to close, and when the atmosphere is introduced, the first on-off valve 5 is driven to close and at the same time, the second on-off valve 6 is driven to open. It is composed of

Negative pressure chamber 7a of diaphragm actuator 7
is connected to a discharge port of a vacuum pump 9 via a negative pressure passage 8, and an electromagnetic three-way valve 10 is connected to the negative pressure passage 8.
is interposed. This electromagnetic three-way valve 10 introduces negative pressure into the negative pressure chamber 7a of the diaphragm actuator 7 when energized by the control device 11, and introduces negative pressure into the negative pressure chamber 7a when the energization is stopped. It is configured to introduce

In addition, the flywheel 1a of the diesel engine 1
A rotation speed sensor 12 for detecting the engine rotation speed is provided nearby, and a detection signal Rrev of this rotation speed sensor 12 is input to the control device 11. Further, the control lever of the fuel injection pump 13 is provided with a load sensor 14 that detects engine load by detecting the lever opening degree, and a detection signal V _L of this load sensor 14 is input to the control device 11.

Then, the control device 11 energizes the electromagnetic three-way valve 10 when the exhaust gas temperature determined from the detection signals V _L and _VR (engine speed and engine load) is equal to or higher than a predetermined value that is in the active region of the catalyst. As a result, negative pressure air is supplied to the diaphragm actuator 7 via the electromagnetic three-way valve 10, thereby driving the first on-off valve 5 to open and simultaneously driving the second on-off valve 6 to close.

Therefore, the exhaust bypass passage 4 is closed and the exhaust gas discharged from the engine flows through the trap 3 with a catalyst, and particulates in the exhaust gas are collected by the trap 3 with a catalyst. In this operating region, the amount of exhaust particles emitted from the engine increases as shown in Figure 6.
Collecting exhaust particulates in this area is effective from the viewpoint of preventing environmental pollution. Also, the first
Immediately after the opening/closing valve 5 opens, the exhaust gas temperature exceeds a predetermined value, which is the active region of the catalyst.
The self-combustion of the collected exhaust particles is promoted by the catalytic action, and the catalytic trap 3 is regenerated.

On the other hand, when determining that the exhaust gas temperature is less than the predetermined value, the control device 11 de-energizes the electromagnetic three-way valve 10. As a result, the atmosphere is introduced into the negative pressure chamber 7a of the diaphragm actuator 7 via the electromagnetic three-way valve 10, the first on-off valve 5 is driven to close, and the second on-off valve 5 is driven to close.
The on-off valve 6 is driven to open.

Therefore, the exhaust gas flows through the exhaust bypass passage 4 without passing through the catalyst trap 3 and is released into the atmosphere. At this time, the trap 3 with catalyst does not perform any collection action, but as shown in Figure 6, in the operating range where the engine load and engine speed are low, the amount of exhaust particulate emissions is extremely small, and there is no problem from the perspective of environmental pollution. .

<Problems to be solved by the invention> However, in such a conventional exhaust particulate treatment device, in a low exhaust temperature operation region where the amount of exhaust particulate emissions is small, exhaust particulates are not collected and are collected through the exhaust bypass passage 4. Therefore, even if the amount of exhaust particulate emissions is small, the exhaust bypass passage 4 can be used when low exhaust temperature operation ranges occur frequently, such as during traffic congestion in urban areas. If the total time during which exhaust gas is discharged into the atmosphere increases, or if the number of vehicles equipped with diesel engines increases, the concentration of exhaust particulates in the atmosphere increases, and the impact on environmental pollution cannot be ignored.

In addition, if exhaust particulates are collected by a single trap with a catalyst in the entire operating range of the engine without providing an exhaust bypass passage, if the exhaust gas is continuously operated for a long time in the low exhaust temperature operating range below the catalyst activation temperature, A large amount of exhaust particulates are collected in a trap with a catalyst. This increases the flow path resistance of the catalytic trap, which increases the exhaust pressure and has a greater effect on the output, and there is also the problem that even if the engine suddenly accelerates from this state, the acceleration performance deteriorates significantly.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an exhaust particulate processing device that can collect exhaust particulates in the entire operating range of an engine while suppressing an increase in exhaust pressure.

<Means for solving the problem> For this reason, the present invention, as shown in FIG. 1, includes a trap C with a first catalyst, which is interposed in the exhaust passage B of the engine A and collects particulates in the exhaust gas; an exhaust bypass passage D that bypasses the first catalytic trap C; a second catalytic trap E that is interposed in the exhaust bypass passage D to collect particulates in the exhaust; and an engine operating state that detects the engine operating state. a detecting means F, and one for causing exhaust gas to flow through both the first catalytic trap C and the second catalytic trap E when the engine operating state detecting means detects an operating state in which the exhaust gas temperature is equal to or higher than a predetermined value; , and a valve device G that opens and closes the exhaust passage B and the exhaust bypass passage D so that exhaust gas flows to one of the first catalytic trap C and the second catalytic trap E in other operating conditions. This is how it was done.

<Operation> As a result, exhaust particulates are collected by either the first catalytic trap or the second catalytic trap in all operating ranges, thereby preventing the exhaust particulates from being released into the atmosphere.
In addition, when the exhaust temperature is below a predetermined value, exhaust gas is not allowed to flow through one of the traps with a catalyst, and the trap with a catalyst is maintained in a constantly regenerated state, reducing its flow path resistance. Suppresses exhaust pressure rise.

<Example> An example of the present invention will be described below with reference to FIGS. 2 and 3. Incidentally, the same elements as those in the conventional example are given the same reference numerals as in FIG. 5, and the explanation thereof will be omitted.

In the figure, the exhaust passage 2 of the diesel engine 1 has a first catalytic trap 21 that collects exhaust particulates.
is interposed, and an exhaust bypass passage 22 that bypasses the first catalytic trap 21 is provided.
A trap 23 with a first exhaust catalyst is interposed in the exhaust bypass passage 22 to collect exhaust particulates.

Further, a butterfly-type on-off valve 24 for opening and closing the exhaust passage 2 is installed in the exhaust passage 2 downstream of the first catalytic trap 21 and upstream of the confluence with the exhaust bypass passage 22. . Open/close valve 24
is driven to open and close by a diaphragm actuator 25. Diaphragm actuator 25
Negative pressure is introduced into the negative pressure chamber 25a through the negative pressure passage 8 and the electromagnetic three-way valve 10.

The electromagnetic three-way valve 10 introduces negative pressure into the negative pressure chamber 25a of the diaphragm actuator 25 when energized by the control device 26, and introduces atmospheric air into the negative pressure chamber 25a when the energization is stopped. is configured to do so.

The detection signal Rrev of the rotational speed sensor 12 and the detection signal V _L of the load sensor 14 are input to the control device 26 .

The control device 26 stores a map showing the relationship among engine load, engine rotational speed, and engine exhaust temperature. As shown in FIG. 4, this map is such that the exhaust temperature increases as at least one of the engine rotational speed and the engine load increases.

Then, the control device 26 searches for the exhaust gas temperature from the input detection signal Rrev of the rotational speed sensor 12, the detection signal _VL of the load sensor 14, and the map, and then the exhaust temperature is equal to or higher than a predetermined value that becomes the active region of the catalyst. (for example, 350 to 400°C), and when the temperature is above a predetermined value, energize the electromagnetic three-way valve 10,
The energization is stopped when the value is less than a predetermined value.

Here, the rotational speed sensor 12 and the load sensor 14
The operating state detection means is constituted by the on-off valve 2.
4. The actuator 25 and the control device 26 constitute a valve device.

Next, the operation will be explained based on the flowchart shown in FIG.

The control device 26 receives the detection signal of the rotational speed sensor 12.
After reading Rrev and the detection signal V _L of the load sensor 14 (S1, S2), the exhaust temperature is searched from the map based on these detection signals Rrev, V _L (S3). Then, it is determined whether the exhaust temperature found in S4 is equal to or higher than a predetermined value that is the active region of the catalyst,
If YES, that is, the retrieved exhaust gas temperature is equal to or higher than a predetermined value, the electromagnetic three-way valve 10 is energized. As a result, negative pressure air is supplied to the diaphragm actuator 25 via the electromagnetic three-way valve 10, and the on-off valve 24 is driven to open.

Therefore, since the exhaust gas flows through both the exhaust passage 2 and the exhaust bypass passage 22, the first catalytic trap 21 and the second catalytic trap 23 collect exhaust particulates. At this time, since the exhaust gas temperature has risen above the catalyst activation temperature, self-combustion of the exhaust particulates collected in the first catalytic trap 21 and the second catalytic trap 23 is promoted by the catalytic action, and the Trap 21, 23 with second catalyst
can be regenerated.

On the other hand, when it is determined in S4 that the exhaust gas temperature is less than the predetermined value, the control device 26 de-energizes the electromagnetic three-way valve 10 in S6. This results in
Atmospheric air is introduced into the negative pressure chamber 25a of the diaphragm actuator 25 via the electromagnetic three-way valve 10,
The on-off valve 24 is driven to close.

Therefore, since the exhaust gas flows only through the exhaust bypass passage 22 without passing through the first catalytic trap 21, the exhaust particles are transferred to the second catalytic trap 2.
Collected by 3. Therefore, it is possible to prevent exhaust particulates from being released into the atmosphere in the entire operating range. In this operating range, the exhaust gas temperature has fallen below the catalyst activation temperature, so self-combustion of exhaust particulates does not take place, but in the operating range where the exhaust temperature exceeds the catalyst activation temperature, the second catalytic trap 23 is regenerated. Ru.

Further, since the exhaust gas does not pass through the first catalytic trap 21, the first catalytic trap 21 is maintained in a regenerated state in the operating range. Therefore, the flow path resistance of the first catalytic trap 21 is small, and when the trap accelerates suddenly from this operating range, the on-off valve 21
is opened and the exhaust gas also flows through the first catalytic trap 21, so that the increase in exhaust pressure can be suppressed, the influence on engine output can be reduced, and deterioration of acceleration performance can also be prevented.

<Effects of the invention> As explained above, the present invention has a first
A catalytic trap is interposed, and a second catalytic trap is provided in the exhaust bypass passage that bypasses the first catalytic trap.
A trap with a catalyst is installed, and in the operating range where the exhaust temperature is above a predetermined value, the exhaust gas flows through both the first trap with the catalyst and the trap with the second catalyst, and in other operating ranges, the exhaust flows into one trap with the catalyst. Since the exhaust gas is allowed to flow, exhaust particulates are collected in the entire operating range and can be prevented from dispersing into the atmosphere. In addition, since the other catalytic trap is constantly maintained in a regenerated state throughout the entire operating range, even if sudden acceleration is performed, the flow resistance of the other catalytic trap is small, so exhaust pressure rise can be suppressed, and the exhaust pressure can be suppressed. The influence on engine output can be reduced and deterioration of acceleration performance can be prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a configuration diagram showing an embodiment of the present invention, Fig. 3 is a flowchart of the same as above, and Fig. 4 is the relationship between engine speed, engine load, and exhaust temperature. FIG. 5 is a configuration diagram showing a conventional example of an exhaust particulate treatment device, and FIG. 6 is a diagram showing the relationship between exhaust temperature and exhaust particulate discharge amount. 2... Exhaust passage, 12... Rotation speed sensor, 1
4... Load sensor, 21... Trap with first catalyst, 22... Exhaust bypass passage, 23... Trap with second catalyst, 24... Opening/closing valve, 25... Diaphragm actuator, 26... Control device.

Claims (1)

[Scope of utility model registration request] A trap with a first catalyst installed in an exhaust passage of an engine to collect particulates in the exhaust gas, an exhaust bypass passage that bypasses the first trap with a catalyst, and a trap installed in the exhaust bypass passage to collect particulates in the exhaust gas. a second catalytic trap for collecting gas; an engine operating state detecting means for detecting an engine operating state; and a second catalytic trap for collecting exhaust gas; Exhaust gas flows through both the trap and the second catalytic trap, while in other operating conditions the exhaust gas flows through both the first catalytic trap and the second catalytic trap.
An exhaust particulate treatment device for an internal combustion engine, comprising a valve device that opens and closes the exhaust passage and the exhaust bypass passage so that exhaust gas flows through one of the traps with a catalyst.