JPH09112254A - Exhaust gas purification device for internal combustion engine - Google Patents

Abstract

(57) An object of the present invention is to provide an exhaust gas purification device for an internal combustion engine, which is capable of purifying exhaust gas discharged from a deactivated cylinder during reduced cylinder operation with a simple system. SOLUTION: The present invention relates to a cylinder 1 that is stopped during a reduced cylinder operation.
b, 1c exhaust manifolds 6b, 6c, and the intake manifolds 6a of the cylinders 1a, 1d operating similarly.
By providing a bypass passage 10 that bypasses the collecting portion 6d, the exhaust gas discharged from the idle cylinders 1b and 1c during the cut-off cylinder operation is passed through the bypass passage 10 and the operating cylinders 1a and 1d.
To oxidize the HC component contained in the exhaust gas by utilizing the combustion stroke of the same cylinder, and oxidize the HC component that could not be further oxidized provided in the main exhaust passage 9 connected to the exhaust manifolds 8a and 8d. Oxidized by the catalyst 13 to generate H
This is because C was suppressed from being released into the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for an internal combustion engine which enhances exhaust gas performance during reduced cylinder operation in which some cylinders are deactivated depending on load.

[0002]

2. Description of the Related Art Most automobiles use an internal combustion engine such as a gasoline engine or a diesel engine having a plurality of cylinders as a power source. By the way, in order to effectively use the output of the internal combustion engine, there has been proposed an internal combustion engine in which a part of the cylinders are deactivated at the time of a light load to enable the operation with a small number of cylinders, that is, the reduced cylinder operation.

[0003] In most cases, a method is adopted in which the fuel injection is stopped while the intake / exhaust valve is normally operated because the maximum effect can be obtained with a simple structure. In an internal combustion engine capable of such reduced cylinder operation, the
As disclosed in Japanese Patent Publication No. 37826-, the exhaust gas from a cylinder that is deactivated (deactivated cylinder) during the reduced-cylinder operation is directly discharged to the atmosphere.

[0004]

For this reason, when passing through the cylinder, the HC (such as fuel component adhering to the wall surface of the combustion chamber and lubricating oil component adhering to the cylinder wall surface) contained in the exhaust gas ( Hydrocarbons) have been released into the atmosphere.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal combustion engine capable of purifying the exhaust gas discharged from the cylinder deactivation during a reduced cylinder operation with a simple system. To provide an exhaust emission control device.

[0006]

In order to achieve the above-mentioned object, the invention described in claim 1 comprises a first intake passage for guiding air to a cylinder operating during reduced cylinder operation and a cylinder stopped during reduced cylinder operation. The exhaust gas purifying apparatus is configured by providing the first exhaust passage for leading out the exhaust gas and the bypass passage for introducing the exhaust gas from the first exhaust passage to the first intake passage during the reduced cylinder operation. .

That is, according to the first aspect of the present invention, during the cut-off cylinder operation, the exhaust gas from the cylinder that is idle is bypassed from the first exhaust passage to the first intake passage through the bypass passage and is operating. It is sucked into the cylinder.

Then, the HC component contained in the exhaust gas is burned by the combustion process performed in the same cylinder, and the HC component is oxidized by the oxidation reaction at this time. That is,
Release of HC and the like into the atmosphere is suppressed.

In addition to the above object, the invention according to claim 2 has a structure in which the bypass passage according to claim 1 has a switching valve in order to secure a more stable bypass function.
This switching valve allows the bypass passage to be opened during the reduced cylinder operation and closed during the reduced cylinder operation.

In addition to the above-mentioned object, the invention according to claim 3 further comprises: in a cylinder that is further operating, in order to efficiently oxidize the total amount of exhaust gas from the cylinders that are inactive, the invention according to claim 1 or 2 The first intake passage has a structure having an intake restriction device that restricts the inflow of air into the operating cylinder.

In addition to the above-mentioned object, the invention according to claim 4 further comprises: a post-treatment of oxidizing the HC component which has not been oxidized in the operating cylinder. In addition to the configuration described in 3, the catalyst is provided in the second exhaust passage through which the exhaust gas is discharged from the cylinder operating during the reduced cylinder operation.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on an embodiment shown in FIGS. FIG. 1 shows a schematic configuration of an exhaust emission control device provided in an exhaust system of an engine. In FIG. 1, reference numeral 1 denotes a diesel engine of a plurality of cylinders mounted on a vehicle such as a bus or a truck for traveling (for example, an in-line 4-cylinder engine ( Internal combustion engine).

Each of the first to fourth cylinders 1a to 1d of the diesel engine 1 has a valve operating system (a mechanism having intake / exhaust valves: not shown) together with, for example, an electronically controlled injection amount. Fuel injection valves 2a-2
d is provided.

Each of the fuel injection valves 2a to 2d is connected to a controller 3 (control means) composed of, for example, a microcomputer. The controller 3 is connected to an E / G rotation speed sensor 4 that detects an engine speed and an accelerator opening sensor 5 (which detects an engine load) that detects an accelerator opening.

The controller 3 has a function of controlling each of the fuel injection valves 2a to 2d so as to inject a fuel injection amount corresponding to an engine load determined by an engine speed and an accelerator opening at a predetermined injection timing. It is set.

Further, when the engine load is low (including no load), the controller 3 has, for example, the second cylinder 1b,
The function of stopping the fuel injection of the fuel injection valves 2b and 2c in the third cylinder 1c is set.

As a result, in the second cylinder 1b and the third cylinder 1c, when the load is low, intake / exhaust valves (not shown) normally operate, but fuel injection to the cylinders 1b, 1c is stopped. The system will be used to suspend the cylinder.

That is, when the load is low, a cylinder cutout operation is performed in which some of the cylinders 1a to 1d are deactivated. Meanwhile, the first
The intake manifolds 6a and 6d (both corresponding to the first intake passage) extending from the intake sides of the cylinder 1a and the fourth cylinder 1d (cylinders operating at low load) join each other to form an air cleaner ( (Not shown) is connected to an intake passage 7b.

Intake manifolds 6b and 6c (intake passages) extending from the intake sides of the remaining second cylinder 1b and third cylinder 1c (cylinder that is idle when the load is low), respectively, also join together, and similarly, an air cleaner. It is connected to an intake passage 7a leading to (not shown).

Exhaust manifolds 8a, 8 extending from the exhaust side of the first cylinder 1a and the fourth cylinder 1d, respectively.
d (both correspond to the second exhaust passage) extend from the exhaust side of the remaining second cylinder 1b and the third cylinder 1c, which join each other and are connected to the main exhaust passage 9 open to the atmosphere. Exhaust manifolds 8b, 8c (both are first
(Corresponding to the exhaust passage) merge with each other. The merging portion 8e of the exhaust manifolds 8b and 8c is connected so as to merge with the main exhaust passage 9.

The merging portion 8e and the intake manifold 6
A bypass passage 10 is connected between the a and 6d merging portion 6e so as to communicate the two. Thus, the exhaust gas discharged from the second cylinder 1b and the third cylinder 1c can be guided to the intake side of the first cylinder 1a and the fourth cylinder 1d through the bypass passage 10.

On the inlet side of the bypass passage 10, there is a position A where the inlet of the bypass passage 10 is open and the merging portion 8e is closed.
A first switching valve 11 (corresponding to a switching valve) of, for example, a Solenoid drive type is provided to open / close between the B position where the inlet of the bypass 10 is closed and the merging portion 8e is opened to switch the flow path. Has been.

The first switching valve 11 is connected to the controller 3. The controller 3 has a first switching valve 11
Opening and closing positions of the engine when the engine load is low (including no load)
Is set to the A position, and the function to be set to the B position is set at the time of operation other than low load (during medium / high load), and the bypass passage 10 is opened only at the time of cut-off cylinder operation, and not at the time of cut-off cylinder operation. At this time, the bypass passage 10 is closed.

As a result, the exhaust gas from the cylinders 1b, 1c which are inactive only during the reduced cylinder operation is operated by the operating cylinders 1a, 1c.
The structure is such that it is introduced into the intake manifolds 6a and 6d of 1d.

On the outlet side of the bypass 10, the C position where the outlet of the bypass 10 is open and the merging portion 6e is closed,
For example, a second switching valve 12 of Solenoid drive type (corresponding to an intake air restricting device) that opens and closes between the D position where the outlet of the bypass passage 10 is closed and opens the merging portion 8e is opened. It is provided.

The second switching valve 12 is also connected to the controller 3 in the same manner. In the controller 3, the open / close position of the second switching valve 12 is set to the C position when the engine load is low (including no load), and the D position is set when the engine load is not low (medium / high load). The function defined in 1) is set so that fresh air (air taken in from the air cleaner) does not enter the intake manifolds 6a and 6d only during the reduced cylinder operation.

As a result, the structure is such that fresh air is restricted from flowing into the operating cylinders 1a and 1d only during the reduced cylinder operation. On the other hand, an oxidation catalyst 13 (catalyst) is provided on the downstream side of the merging portion 8f of the exhaust manifolds 8a and 8d,
The exhaust gas is discharged through the exhaust manifolds 8a and 8d to purify the exhaust gas.

By the combined use of the structure for burning (oxidizing) the exhaust gas from the cylinders 1b, 1c which are inactive in the operating cylinders 1a, 1d, and the after-treatment structure for oxidizing the unburned residue by the oxidation catalyst 13, The HC component contained in the exhaust gas from the cylinders 1b and 1c is purified.

The operation of this exhaust purification system is shown in FIG. Next, based on the flowchart shown in FIG.
The operation of the exhaust emission control device will be described.

First, start the diesel engine 1,
Drive a car. At this time, the controller 3
As in step S1, the engine speed output from the E / G speed sensor 4 and the accelerator opening output from the accelerator opening sensor 5 are read to determine the engine load (running state).
Has been detected.

Here, although not shown, a map of the engine load in which the switching regions of the switching valves 11 and 12 are set in the controller 3 [low load region: the switching valves 11 and 12 are opened, load regions other than the low loads are provided. : A map for closing the switching valves 11 and 12 (both with respect to the bypass path 10 side) is stored.

The controller 3 determines the switching timing of the switching valves 11 and 12 from the detected engine load according to this map. Specifically, as shown in step S2, the switching timing is determined depending on whether the engine load is low.

At this time, if the engine load is medium load (or high load), the routine proceeds to step S3, where the first switching valve 11 is operated to the B position and the second switching valve 12 is operated to the D position.
Then, as shown in FIG. 2, the entrance of the bypass passage 10,
Both outlets are blocked.

As a result, all the cylinders 1a-1d are
Fresh air (air taken in from the air cleaner) is introduced through the intake manifolds 6a to 6d. Exhaust gas is led out from all the cylinders 1a to 1d through the exhaust manifolds 8a to 8d.

Next, in step S4, the fuel injection valves 2a to 2d of the first cylinders 1a to 1d inject fuel with an injection amount according to the engine load at an appropriate time under the control of the controller 3. It

As a result, in all cylinders 1a to 1d, intake air,
The compression, combustion (explosion), and exhaust strokes are repeated (all cylinder combustion). The exhaust gas discharged from the first cylinder 1a and the fourth cylinder 1d is discharged to the atmosphere through the oxidation catalyst 13 and the main exhaust passage 9.

The exhaust gas discharged from the second cylinder 1b and the third cylinder 1c merges with the exhaust gas discharged from the oxidation catalyst 13 and is discharged to the atmosphere. On the other hand, if the engine load during traveling is low, steps S2 to S5 are performed.
Proceed to.

Then, the controller 3 stops the fuel injection of the fuel injection valve 2b and the fuel injection valve 2c. As a result, as shown in FIG. 1, the first cylinder 1a and the fourth cylinder 1a
The d-cylinder operation is performed, and only the second cylinder 1b and the third cylinder 1c are deactivated, which is a reduced-cylinder operation (operation in which some cylinders are deactivated).

Next, in step S6, the first switching valve 11 is switched to the A position and the second switching valve 12 is switched to the C position. Then, as shown in FIG. 1, on the exhaust side of the cylinders 1b and 1c, the flow path from the merging portion 8e of the exhaust manifolds 8b and 8c to the atmosphere is closed, and instead, the inlet of the bypass path 10 is opened. The road is switched.

Similarly, on the intake side, the flow path is switched such that the flow path from the intake path 7b to the merging portion 6e of the intake manifolds 6a and 6d is closed and the outlet of the bypass path 10 is opened instead.

As a result, the fresh air (the air taken in from the air cleaner) is introduced only to the cylinders 1b and 1c which are at rest. When fresh air passes through the idle cylinders 1b and 1c, HC (hydrocarbon) such as fuel components adhering to the wall surface of the combustion chamber (not shown) and lubricating oil components adhering to the cylinder wall surface. Is mixed.

The exhaust gas from the deactivated cylinders 1b and 1c is guided to the merging portion 6e of the intake manifolds 6a and 6d through the bypass passage 10 without being released to the atmosphere. Here, since the second switching valve 12 restricts fresh air from being introduced into the merging portion 6e, the deactivated cylinder 1b,
The total amount of exhaust gas from 1c is the intake manifold 6a,
It is directly sucked into the operating cylinders 1a and 1d through 6d.

As a result, the operating cylinders 1a and 1d are subjected to a combustion cycle using the exhaust gas from the deactivated cylinders 1b and 1c as intake air. The HC component contained in the exhaust gas is combusted by the combustion process performed in the operating cylinders 1a and 1d. The HC component is oxidized by the oxidation reaction at this time.

Then, the exhaust gas discharged from the operating cylinders 1a, 1d passes through the exhaust manifolds 8a, 8d,
It is guided to the oxidation catalyst 13. As a result, the remaining HC components are oxidized while passing through the oxidation catalyst 13.

Then, the exhaust gas that has undergone this oxidation treatment is released from the main exhaust passage 9 to the atmosphere. As described above, in the exhaust gas purifying device that uses the exhaust gas from the idle cylinders 1b and 1c as the combustion air of the operating cylinders 1a and 1d during the reduced cylinder operation, the exhaust gas from the idle cylinders 1b and 1c is used as the operating cylinder 1
With a simple system that is introduced into a and 1d, the exhaust gas discharged from the idle cylinders 1b and 1c can be purified.

In particular, the adoption of the structure in which the bypass passage 10 is opened / closed by the first switching valve 11 during the reduced cylinder operation and other than during the reduced cylinder operation,
Contributes to securing a stable bypass function. Moreover, when the second switching valve 12 is configured to restrict the inflow of fresh air into the operating cylinders 1a and 1d during the reduced cylinder operation, the total amount of exhaust gas discharged from the idle cylinders 1b and 1c remains unchanged.
Since it is sucked from 1d, the entire amount of exhaust gas from the deactivated cylinders 1b and 1c can be efficiently oxidized.

In addition, if the exhaust gas discharged from the operating cylinders 1a and 1d is subjected to the oxidation reaction by the oxidation catalyst 13, the HC component which is not oxidized in the operating cylinders 1a and 1d is oxidized, so that it is more excellent. A cleansing effect can be obtained (post-treatment).

Particularly, the exhaust gas discharged from the operating cylinders 1a, 1d is the exhaust gas whose temperature rises (due to heat transfer) when passing through the idle cylinders 1b, 1c.
Since it is the gas burned in d, the temperature is considerably high and the flow rate of the exhaust gas is small, so that sufficient purification can be expected with the oxidation catalyst 13 (because the temperature of the exhaust gas has risen to the activation temperature). Although the present invention is applied to the diesel engine, the present invention is not limited to this, and may be applied to other internal combustion engines, such as a gasoline engine capable of reduced cylinder operation.

[0049]

As described above, according to the invention described in claim 1, it is possible to purify the exhaust gas discharged from the cylinder deactivation during the reduced cylinder operation with a simple system. Play.

According to the second aspect of the present invention, the first aspect is provided.
In addition to the effect of the invention described above, there is an effect that a stable bypass function can be secured. According to the invention of claim 3, in addition to the effect of the invention of claim 1 or 2, in the operating cylinder, the entire amount of the exhaust gas discharged from the idle cylinder can be efficiently oxidized. Has the effect.

According to the invention of claim 4, in addition to the effect of the invention of claim 1, claim 2 or claim 3, the HC component not oxidized in the operating cylinder is subjected to an oxidation treatment (post-treatment). Therefore, it is possible to obtain an excellent purification effect.

Particularly, the exhaust gas from the operating cylinder is a gas after the exhaust gas whose temperature has risen when passing through the idle cylinder is burned in the operating cylinder, and therefore the temperature is considerably high and the flow rate is small, so that the catalyst is used. Sufficient purification can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration of an exhaust gas purification device for an internal combustion engine according to an embodiment of the present invention, together with flows of intake gas and exhaust gas during a reduced cylinder operation.

FIG. 2 is a diagram showing the flow of intake gas and exhaust gas during all-cylinder combustion operation of the exhaust emission control device.

FIG. 3 is a flowchart for explaining control of the reduced-cylinder operation and the all-cylinder combustion operation of the exhaust emission control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diesel engine (internal combustion engine) 1a-1d ... 1st cylinder-4th cylinder 2a-2d ... Fuel injection valve 3 ... Controller (control means) 4 ... E / G rotation speed sensor 5 ... Accelerator opening sensor 6a , 6d ... Intake manifold (first intake passage) 8b, 8c ... Exhaust manifold (first exhaust passage) 8a, 8d ... Exhaust manifold (second exhaust passage) 9 ... Main exhaust passage 10 ... Bypass passage 11 ... First switching valve (Switching valve) 12 ... 2nd switching valve (intake control device) 13 ... Oxidation catalyst (catalyst).

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F01N 3/24 F02D 17/02 R ZAB ZABU F02D 17/02 41/02 325C ZAB F02M 25/07 570N 41/02 325 B01D 53/36 ZAB F02M 25/07 570 103Z (72) Inventor Shigeru Haruto 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Taizo Shimada Tokyo, Minato-ku, Tokyo 5-3, Shiba Mitsubishi Motors Corporation

Claims (4)

[Claims] 1. An internal combustion engine having a plurality of cylinders and performing cylinder cutout operation in which injection of fuel to some cylinders is stopped in accordance with load, in which air is introduced to cylinders operating during cylinder cutout operation. 1 intake passage, a first exhaust passage for leading out exhaust gas from a cylinder that is inactive during reduced-cylinder operation, and a bypass passage for introducing exhaust gas from the first exhaust passage to the first intake passage during reduced-cylinder operation An exhaust gas purification device for an internal combustion engine, comprising: 2. The bypass passage is opened during reduced cylinder operation,
The exhaust emission control device for an internal combustion engine according to claim 1, further comprising a switching valve that is closed except when the reduced-cylinder operation is performed. 3. The exhaust gas of an internal combustion engine according to claim 1 or 2, wherein the first intake passage has an intake restriction device that restricts an inflow of air into a cylinder operating during reduced cylinder operation. Purification device. 4. A second exhaust passage for leading out exhaust gas from a cylinder operating during reduced-cylinder operation, and a catalyst provided in the second exhaust passage. Alternatively, the exhaust gas purification device for an internal combustion engine according to claim 3.