JPH0617676A - Control device for engine - Google Patents

Abstract

PURPOSE:To suppress the temperature rise of catalysts within the objective range while securing the output torque control of an engine. CONSTITUTION:The control device of an engine is provided with at least two exhaust purifying catalysts 11A, 11B arranged in parallel in an exhaust system, a cylinder group consisting of at least two cylinders communicated with the catalysts 11a, 11B respectively, a fuel feed stop means stopping the fuel feed to part of the cylinders, and the first air-fuel ratio control means setting the air-fuel ratio A/F of the fuel fed to the cylinder group including the cylinder stopped with the fuel feed to the lean state when the fuel feed to part of the cylinders is stopped by the fuel feed stop means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device, and more specifically to at least two exhaust purification catalysts provided in parallel in an exhaust system and communicating with each catalyst. The present invention relates to an engine control device including a cylinder group including at least two cylinders.

[0002]

2. Description of the Related Art Generally, in an engine equipped with at least two exhaust purification catalysts arranged in parallel in an exhaust system, for example, means for controlling the output torque of the engine (that is, traction control, etc.) As a case, when stopping the fuel supply to a specific cylinder communicated with the selected catalyst, a cylinder group including the cylinder whose fuel supply is stopped (that is,
When the air-fuel ratio of the operating cylinders in the cylinder group communicating with the same catalyst) is richer than the theoretical air-fuel ratio (A / F = 14.7), unburned fuel and fuel supply are stopped in the catalyst. The catalyst temperature rises due to the reaction with the fresh air discharged from the cylinder. Such an increase in catalyst temperature causes thermal deterioration of the catalyst.

By the way, the temperature of the catalyst connected to the cylinder group including the fuel supply stopped cylinder and the non-fuel supply stopped cylinder tends to increase as the air-fuel ratio becomes richer. this is,
This is because when the air-fuel ratio becomes rich, a large amount of air is contained in the fuel supply stopped cylinder and the unburned gas reacts with air to raise the exhaust gas temperature. Further, the temperature of the catalyst connected to the cylinder group that does not include the fuel supply stopped cylinder tends to become lower as the air-fuel ratio becomes richer. This is because there is no cylinder in which fuel supply is stopped and there is little air that reacts with unburned gas, so the richer the air-fuel ratio, the greater the amount of unburned gas and the lower the exhaust gas temperature. Therefore, in the control by only the partial fuel supply stop, in an engine having a plurality of exhaust systems (i.e., an exhaust system having a plurality of catalysts), the exhaust system during the partial fuel supply stop (i.e., including a fuel supply stopped cylinder is included. (Exhaust system equipped with a catalyst that communicates with the cylinder group)
And an exhaust system in which the partial fuel supply is not stopped (that is, an exhaust system including a catalyst that communicates with a cylinder group that does not include the fuel supply stopped cylinder), due to one of the temperature restrictions as described above. There may be a case where the engine output torque control cannot be executed due to the partial fuel supply stop.

As a conventionally known technique, when the catalyst temperature rises during the partial fuel supply stop, the partial fuel supply stop is stopped to prevent thermal deterioration of the catalyst. (For example, JP-A-60-1
51131).

[0005]

In the case of the above-mentioned known example, since the partial fuel supply stop is stopped, for example, when the traction control is being executed, the slip may be performed before the slip is converged. There is a problem that the traction control cannot be performed.

The present invention has been made in view of the above points, and an object of the present invention is to make it possible to suppress the temperature rise of the catalyst within the target range while ensuring the output torque control of the engine. .

[0007]

According to a first aspect of the present invention, as means for solving the above problems, at least two exhaust purification catalysts are provided in parallel in an exhaust system, and the respective catalysts. In a control device of an engine including a cylinder group including at least two cylinders that are in communication with each other, a fuel supply stopping unit that stops fuel supply to some of these cylinders, and the fuel supply. When the fuel supply to some cylinders is stopped by the stop means, the first air-fuel ratio control means for making the air-fuel ratio of the fuel supplied to the cylinder group including the cylinder for which the fuel supply has been stopped into a lean state is additionally provided. is doing.

According to a second aspect of the present invention, as means for solving the above-mentioned problems, in the engine control device according to the first aspect, the fuel supply stopping means stops the fuel supply to some cylinders. At this time, a second air-fuel ratio control means is provided to make the air-fuel ratio of the fuel supplied to the cylinder group not including the cylinder in which the fuel supply is stopped to be rich.

According to a third aspect of the invention, as means for solving the above-mentioned problems, in the engine control device according to the first or second aspect, the partial fuel supply stop by the fuel supply stop means is executed when a slip occurs. I am trying.

[0010]

According to the first aspect of the invention, the following actions can be obtained by the above means.

That is, when the fuel supply to some of the cylinders is stopped, the air-fuel ratio of the fuel supplied to the cylinder group including the cylinder for which the fuel supply is stopped is made lean. Therefore, the temperature rise of the catalyst communicated with the cylinder group including the cylinder whose fuel supply is stopped is suppressed.

According to the second aspect of the invention, the following actions can be obtained by the above means.

That is, when the fuel supply to some of the cylinders is stopped, the air-fuel ratio of the fuel supplied to the cylinder group including the cylinder for which the fuel supply is stopped is made lean and the fuel supply is stopped. The air-fuel ratio of the fuel supplied to the cylinder group that is not set is made rich. Therefore, the temperature rise of the catalyst communicated with the cylinder group including the cylinder whose fuel supply is stopped is suppressed, and the temperature rise of the catalyst communicated with the cylinder group including the cylinder whose fuel supply is not stopped is suppressed and the engine is Will be maintained.

According to the third aspect of the invention, the following actions can be obtained by the above means.

That is, the partial fuel supply stop is executed by the traction control command when the vehicle slip occurs.

[0016]

According to the invention of claim 1, at least two exhaust gas purification catalysts are provided in parallel in the exhaust system, and at least two catalysts are placed in communication with each catalyst. In an engine control device including a cylinder group including cylinders, a fuel supply stopping means for stopping fuel supply to some of these cylinders, and a fuel supply to some cylinders being stopped by the fuel supply stopping means. And a first air-fuel ratio control means for keeping the air-fuel ratio of the fuel supplied to the cylinder group including the cylinder whose fuel supply is stopped to a lean state, the cylinder including the cylinder whose fuel supply is stopped. Since the temperature rise of the catalyst communicated with the group can be suppressed, there is an excellent effect that the thermal deterioration of the catalyst in the exhaust system can be effectively prevented while controlling the output torque of the engine.

According to the second aspect of the present invention, in the engine control device according to the first aspect, when the fuel supply to the partial cylinders is stopped by the fuel supply stopping means, the cylinders for which the fuel supply is stopped are selected. A second air-fuel ratio control means for changing the air-fuel ratio of the fuel supplied to the cylinder group not included to a rich state is additionally provided to suppress the temperature rise of the catalyst communicated with the cylinder group including the cylinder whose fuel supply is stopped. At the same time, since the temperature rise of the catalyst communicated with the cylinder group including the cylinders in which the fuel supply is not stopped is suppressed and the output of the engine is maintained, while controlling the output torque of the engine,
There is an excellent effect that the thermal deterioration of the catalyst in the exhaust system can be prevented more effectively.

According to the third aspect of the invention, the traction control for eliminating the slip of the automobile is executed by stopping the partial fuel supply, and the thermal deterioration of the catalyst is not deteriorated without impairing the drivability during the traction control. It also has an excellent effect that it can be prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a system to which this embodiment is applied, focusing on a V-type 6 cylinder engine 1.

The engine 1 includes an engine controller (that is, ECU) 2 and a traction controller (that is, ECU).
The intake manifold 5 and the intake port 6 are provided corresponding to each cylinder 4 (4a-4f) of the engine 1.

Each intake port 6 is provided with six fuel injection valves 7 (7a to 7f) which are opened by a valve opening signal from the engine controller 2. An exhaust manifold 9 is provided on the downstream side of a combustion chamber 8 that burns the fuel injected from each fuel injection valve 7.

The exhaust manifold 9 is provided with an O ₂ sensor 10 for detecting the residual oxygen concentration of the exhaust gas and outputting an air-fuel ratio signal A / F. Downstream of this, an O ₂ sensor 10 for exhaust gas purification is attached. Catalyst 11 (11A, 11B)
Is provided. Reference numeral 12 is a secondary catalyst provided on the downstream side of the catalyst 11. That is, in this embodiment, the engine 1 includes two catalysts 11A and 11B provided in parallel in the exhaust system and the catalysts 11A and 11B.
The cylinder groups 4A and 4B are in communication with each other. Here, the cylinder group 4A, 4B
Are constituted by NO1, 3, 5 cylinders 4a-4c and NO2, 4, 6 cylinders 4d-4f, respectively (see FIG. 4).

In the engine block 13 forming the combustion chamber 8, the cooling water temperature Tw in the water jacket 14 is increased.
An engine water temperature sensor 15 that detects the temperature and outputs a cooling water temperature signal is attached.

The engine 1 has a crank angle sensor 1 for outputting an engine speed signal for detecting a crank angle of the crankshaft 16 and calculating an engine speed Ne.
7 is attached.

The traction controller 3 comprises, for example, a microcomputer, and as shown in FIG. 2, the rotation speed Nt ₁ of the drive wheel 19 detected by the drive wheel rotation speed sensor 18 and the driven wheel rotation speed sensor 20. The rotational speed Nt ₂ of the driven wheel 21 detected by the above is obtained, the rotational speed difference ΔNt (= Nt ₁ −Nt ₂ ) between the two wheels is compared with the set shikey value A, and when ΔNt> A, the engine is A fuel cut signal for each cylinder is output to the controller 2.

The engine controller 2 is composed of, for example, a microcomputer. As shown in the functional correspondence diagram of FIG. 3, one of the cylinders 4a to 4f is obtained by receiving a fuel cut signal for each cylinder from the traction controller 3. A fuel supply stop means 21 for outputting a command to stop the fuel supply to a cylinder, and a cylinder group including a cylinder whose fuel supply is stopped when the fuel supply stop means 21 stops the fuel supply to some cylinders. When the fuel supply to some cylinders is stopped by the first air-fuel ratio control means 22 for making the air-fuel ratio of the fuel supplied to 4A or 4B lean, and the fuel supply stopping means 21, the fuel supply is stopped. And a second air-fuel ratio control means 23 for setting the air-fuel ratio of the fuel supplied to the cylinder group 4B or 4A not including the selected cylinder to a rich state. .

Next, the operation of the engine control apparatus according to the embodiment of the present invention will be described with reference to the flow chart shown in FIG.

In step S ₁ , the rotation speeds Nt ₁ and Nt ₂ detected by the drive wheel rotation speed sensor 18 and the driven wheel rotation speed sensor 20 are the traction controller 3.
Entered in. Then, in step S ₂ , the rotation speed difference ΔNt (= Nt ₁ −Nt ₂ ) of both wheels is compared with the set shikey value A. If ΔNt> A, the traction controller 3 performs the process in step S ₃ Then, a cylinder-by-cylinder fuel cut signal (in other words, a torque down command) is output to the engine controller 2.

Thereafter, in step S ₄ , the engine condition (for example, cooling water temperature Tw, air-fuel ratio A
/ F, engine speed Ne, etc.) is the engine controller 2
Entered in.

Based on the engine condition, the traction control pattern (in other words, the torque down pattern) is set in step S ₅ as follows. As the setting of this traction control pattern, the number of cylinders in which fuel supply is stopped (that is, F / C number), the pattern of cylinders in which fuel supply is stopped (that is, F / C pattern), and the air-fuel ratio A / F are set according to the slip degree of the vehicle. But,
As shown in FIGS. 6A to 6C, various patterns are set.

Here, the pattern shown in FIG. 6 (a) is one cylinder F / C (that is, only NO1 cylinder 4a stops the fuel supply), and a cylinder group 4A (that is, a cylinder including a fuel supply stop cylinder). The air-fuel ratio A / F for the group is lean (that is, A / F = 1)
4.7), and the air-fuel ratio A / F for the cylinder group 4B (that is, the cylinder group that does not include the fuel supply stopped cylinder) is rich (that is,
A / F = 12.0). This way,
As shown in FIG. 7, the catalyst 1 communicated with the cylinder group 4A.
The temperature of 1A shows 600 ° C., and the temperature of the catalyst 11B communicating with the cylinder group 4B shows 550 ° C., both of which satisfy the allowable temperature range (that is, 900 ° C. or less).

The pattern shown in FIG. 6B is a 2-cylinder F / C.
(I.e., NO1, No. 3 cylinders 4a, 4b stop fuel supply) and cylinder group 4A (i.e., cylinder group including fuel supply stop cylinders)
Is lean (i.e., A / F = 14.
7), and the air-fuel ratio A / F with respect to the cylinder group 4B (that is, the cylinder group that does not include the fuel supply stopped cylinder) is rich (that is, A / F).
F = 12.0). In this way, FIG.
11A, the catalyst 11A communicated with the cylinder group 4A
Indicates a temperature of 330 ° C., and the temperature of the catalyst 11B communicating with the cylinder group 4B indicates 550 ° C., both of which satisfy the allowable temperature range (that is, 900 ° C. or less).

The pattern shown in FIG. 6C is a three-cylinder F / C.
(That is, NO1, 3, 5 cylinders 4a, 4b, 4c stop fuel supply)
And the air-fuel ratio A / F with respect to the cylinder group 4B (that is, the cylinder group that does not include the fuel supply stopped cylinder) is rich (that is, A / F).
F = 12.0). At this time, the cylinder group 4A
All of the cylinders 4a to 4c are stopped. By doing so, as shown in FIG. 7, the temperature of the catalyst 11A communicated with the cylinder group 4A shows 100 ° C., and the temperature of the catalyst 11B communicated with the cylinder group 4B shows 550 ° C., Both of them satisfy the allowable temperature range (that is, 900 ° C. or less).

The pattern shown in FIG. 6D is a two-cylinder F / C.
(I.e., NO1 and 4 cylinders 4a and 4e are not supplied with fuel), both cylinder groups 4A and 4B are cylinders including fuel supply stopped cylinders, and the air-fuel ratio A / for both cylinder groups 4A and 4B is F is lean (that is, A / F = 14.7). By doing so, as shown in FIG.
The temperatures of the catalysts 11A and 11B, which are in communication with A and 4B, both show 600 ° C., which means that the allowable temperature range (ie,
900 ° C. or less) will be satisfied.

The pattern shown in FIG. 6 (e) is a 3-cylinder F / C.
(That is, the fuel supply to NO1, 4,5 cylinders 4a, 4e, 4c is stopped)
The cylinder groups 4A and 4B are both cylinder groups including the fuel supply stopped cylinder, and the air-fuel ratio A / F for both cylinder groups 4A and 4B is lean (that is, A / F = 14.7). Has been done. By doing so, as shown in FIG. 7, the temperature of the catalyst 11A communicated with the cylinder group 4A is 330 ° C., and the temperature of the catalyst 11B communicated with the cylinder group 4B is 600 ° C. Allowable temperature range (ie 90
0 ° C. or less) will be satisfied.

The pattern shown in FIG. 6F is a four cylinder F / C.
(I.e., NO1, 2, 4, 5 cylinders 4a, 4d, 4e, 4c stop fuel supply), and both cylinder groups 4A, 4B are cylinder groups including fuel supply stop cylinders. 4A, 4B
Is lean (i.e., A / F = 14.
7). By doing so, as shown in FIG. 7, the catalysts 11A, 11 communicated with the cylinder groups 4A, 4B are connected.
Both the temperatures of B show 330 ° C., which satisfies the allowable temperature range (that is, 900 ° C. or less).

The pattern shown in FIG. 6 (g) is a 4-cylinder F / C.
(I.e., NO1, 2, 3, 5 cylinders 4a, 4d, 4b, 4c stop fuel supply), and the air-fuel ratio A / F for the cylinder group 4B (that is, the cylinder group including the fuel supply stopped cylinders) is lean. (Ie A
/F=14.7). At this time, cylinder group 4
All the cylinders 4a-4c of A are stopped. By doing so, as shown in FIG. 7, the temperature of the catalyst 11A communicated with the cylinder group 4A shows 100 ° C., and the temperature of the cylinder group 4B increases.
The temperature of the catalyst 11B communicating with is 550 ° C, and both are within the allowable temperature range (that is, 900 ° C or less).
Will be satisfied.

The pattern shown in FIG. 6C is a five cylinder F / C.
(That is, NO1, 2, 3, 4, 5 cylinders 4a, 4d, 4b, 4e, 4c stop fuel supply), and the air-fuel ratio A for the cylinder group 4B (that is, the cylinder group including the fuel supply stopped cylinders) / F is made lean (that is, A / F = 14.7). At this time, all the cylinders 4a to 4c in the cylinder group 4A are stopped.
By doing so, as shown in FIG. 7, the temperature of the catalyst 11A communicated with the cylinder group 4A shows 100 ° C., and the temperature of the catalyst 11B communicated with the cylinder group 4B shows 330 ° C. Both are within the allowable temperature range (ie 900
Will be satisfied).

As described above, in the case of this embodiment, the catalyst temperature is kept within the allowable temperature range in any traction control pattern, so that thermal deterioration of the catalyst can be effectively prevented. That is, it is possible to effectively prevent thermal deterioration of the catalyst in the exhaust system while controlling the output torque of the engine.

The invention of the present application is not limited to the configuration of the above-mentioned embodiment, and it goes without saying that the design can be appropriately changed without departing from the gist of the invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an engine control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a main configuration of an engine control device according to an embodiment of the present invention.

FIG. 3 is a functional correspondence diagram of the present invention.

FIG. 4 is a cylinder layout diagram of an engine according to an embodiment of the present invention.

FIG. 5 is a flow chart for explaining the operation of the engine control device according to the embodiment of the present invention.

6A to 6H are schematic diagrams showing various traction control patterns in the engine control device of the present invention.

FIG. 7 is a characteristic diagram showing a change in catalyst temperature with respect to an air-fuel ratio in the engine control device according to the embodiment of the present invention.

[Explanation of symbols]

1 is an engine, 2 is an engine controller, 3 is a traction controller, 4 (4a to 4f) is a cylinder, 4A, 4B.
Is a cylinder group, 7 is a fuel injection valve, 10 is an O ₂ sensor,
11A and 11B are catalysts, 15 is an engine water temperature sensor,
Reference numeral 17 is a crank angle sensor, 18 is a drive wheel rotation speed sensor, 20 is a driven wheel rotation speed sensor, 21 is fuel supply stopping means, 22 is first air-fuel ratio control means, 23 is second air-fuel ratio control means, and Tw is cooling water. Temperature, Ne is the engine speed, Nt ₁ is the drive wheel speed, Nt ₂ is the driven wheel speed, A is the set throttle value, and A / F is the air-fuel ratio.

Claims (3)

[Claims] 1. An exhaust system comprising at least two exhaust gas purification catalysts arranged in parallel, and a cylinder group consisting of at least two cylinders in communication with each catalyst. The fuel supply stopping means for stopping the fuel supply to some of these cylinders, and the cylinder for which the fuel supply is stopped when the fuel supply to some cylinders is stopped by the fuel supply stopping means. A control device for an engine, further comprising: a first air-fuel ratio control means for making an air-fuel ratio of fuel supplied to a cylinder group including the lean state. 2. The air-fuel ratio of the fuel supplied to a cylinder group that does not include the cylinder whose fuel supply is stopped is set to a rich state when the fuel supply stopping means stops the fuel supply to some cylinders. The engine control apparatus according to claim 1, further comprising a second air-fuel ratio control means. 3. The engine control device according to claim 1, wherein the partial fuel supply stop by the fuel supply stop means is executed when a slip occurs.