JP7067239B2 - Internal combustion engine control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

For example, Patent Document 1 discloses an internal combustion engine having a filter for collecting particulate matter (hereinafter referred to as PM) in exhaust gas in an exhaust passage. The PM deposited on this filter is burned and regenerated when oxygen is supplied to the filter in a high temperature state by executing a fuel cut during deceleration.

By the way, if PM combustion proceeds excessively during the execution of the fuel cut, the filter may be overheated and damaged. Therefore, in the internal combustion engine described in Patent Document 1, when it is predicted that the filter will be in an excessively high temperature state when the fuel cut is started, the start of the fuel cut is prohibited.

Japanese Unexamined Patent Publication No. 2011-99451

However, if the start of the fuel cut is prohibited as described above, the PM combustion process using the fuel cut cannot be performed, so that the regeneration of the filter may be delayed.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a control device for an internal combustion engine capable of burning and treating accumulated PM while suppressing damage to a filter.

An internal combustion engine control device that solves the above problems is applied to an internal combustion engine provided with a filter that collects particulate matter in the exhaust in the exhaust passage, and when a predetermined fuel cut condition is satisfied, the fuel in the internal combustion engine is satisfied. Executes fuel cut control to stop injection. Then, when it is determined that the temperature of the filter has reached a predetermined temperature during the execution of the fuel cut, this control device executes a process of stopping the running fuel cut.

According to the same configuration, during the execution of the fuel cut, the fuel cut is performed until the temperature of the filter reaches the predetermined temperature, so that the PM deposited on the filter can be burned. When the temperature of the filter reaches the above-mentioned predetermined temperature during the execution of the fuel cut, the running fuel cut is stopped, so that it is possible to suppress the damage of the filter due to the excessive temperature rise due to the combustion of PM. become.

The schematic diagram which shows the internal combustion engine and the control device in 1st Embodiment. The flowchart which shows the procedure of the process which the control device of the same embodiment executes. A timing chart showing the operation of the same embodiment. The flowchart which shows the procedure of the process which a control apparatus executes in 2nd Embodiment. A timing chart showing the operation of the same embodiment. The flowchart which shows the procedure of the process which a control apparatus executes in 3rd Embodiment.

(First Embodiment)
Hereinafter, the first embodiment of the control device for an internal combustion engine will be described with reference to FIGS. 1 to 3.

As shown in FIG. 1, the internal combustion engine 10 is an in-vehicle engine that uses gasoline as fuel, and the fuel injection amount is basically controlled so that the air-fuel ratio of the air-fuel mixture in the fuel chamber becomes the stoichiometric air-fuel ratio. Will be done.

The internal combustion engine 10 includes a plurality of cylinders 11, and each cylinder 11 is provided with a fuel injection valve 12 for injecting fuel and a spark plug (not shown) for generating spark discharge.
The exhaust passage 20 of the internal combustion engine 10 is provided with a well-known three-way catalyst 30 and a filter 40 for collecting particulate matter (PM) in the exhaust in order from the upstream of the exhaust.

Further, the crankshaft of the internal combustion engine 10 is connected to a torque converter 50 provided with a lockup clutch (not shown). The output shaft of the torque converter 50 is connected to the input shaft of the multi-stage automatic transmission 60.

Various controls such as the internal combustion engine 10 and the automatic transmission 60 are executed by the control device 100. The control device 100 includes a central processing unit, a memory, and the like, and the central processing unit executes a program stored in the memory to perform various controls.

In order to perform various controls, the control device 100 refers to the engine rotation speed NE detected by the crank angle sensor 71, the intake air amount GA detected by the air flow meter 72, and the vehicle speed SP detected by the vehicle speed sensor 73. do. Further, the control device 100 is an air-fuel ratio sensor 75 detected by an accelerator pedal operation amount (hereinafter referred to as an accelerator operation amount) ACCP detected by the accelerator sensor 74 and an air-fuel ratio sensor 75 provided upstream of the exhaust of the three-way catalyst 30. See also fuel ratio AF.

As one of various controls, the control device 100 executes fuel cut control for stopping fuel injection in the internal combustion engine 10 when a predetermined fuel cut condition is satisfied. As the fuel cut condition, for example, the condition that the accelerator operation amount ACCP is "0" and the engine rotation speed NE is equal to or higher than the predetermined fuel cut return rotation speed is set. Then, when the fuel cut condition is satisfied, the fuel injection from the fuel injection valve 12 is stopped. Then, when the engine rotation speed NE becomes equal to or lower than the fuel cut return rotation speed during the execution of the fuel cut, the fuel injection is restarted.

Further, the control device 100 performs shift control of the automatic transmission 60 as one of various controls. This shift control is well known, and basically, the indicated value of the shift stage is calculated based on the accelerator operation amount ACCP, the vehicle speed SP, and the like. Then, the hydraulic circuit in the automatic transmission 60 is controlled so that the shift stage of the automatic transmission 60 becomes an instructed value.

Next, a part of the processing executed by the control device 100 will be described with reference to FIG. The process shown in FIG. 2 is realized by the central processing unit executing the program stored in the memory of the control device 100 at predetermined intervals. In the following, the step number is represented by a number prefixed with "S".

When the process shown in FIG. 2 is started, the control device 100 first calculates the fuel cut stop air amount α (S100). This fuel cut stop air amount α has the following values.
That is, when oxygen is supplied to the filter 40 in a high temperature state by executing the fuel cut, the PM deposited on the filter 40 is burned and the filter 40 is regenerated.

Here, if PM is burned during the execution of the fuel cut, the temperature of the filter 40 rises, and the temperature rise allowance of the filter 40 is the total amount of oxygen supplied to the filter 40 during the execution of the fuel cut. The larger the amount, that is, the larger the integrated amount of intake air, the higher the value.

Therefore, whether or not the temperature of the filter 40 has reached a predetermined temperature, more specifically, a stop temperature set to a temperature lower than the temperature at which the filter 40 is melted by a predetermined value during the execution of the fuel cut. The fuel cut stop air amount α is calculated as a threshold value to be compared with the integrated air amount during fuel cut execution. The fuel cut stop air amount α is calculated based on the temperature of the filter 40, the PM accumulation amount of the filter 40, and the intake air amount GA.

More specifically, the higher the temperature of the filter 40 before the start of the fuel cut, the higher the temperature of the filter 40 during the execution of the fuel cut. Therefore, the temperature of the filter 40 even when the integrated air amount after the start of the fuel cut is smaller. Will reach the above stop temperature. Therefore, the higher the temperature of the filter 40 before the start of fuel cut, the smaller the fuel cut stop air amount α is set. Although the control device 100 of the present embodiment calculates the temperature of the filter 40 based on the engine operating state by a well-known method, the temperature of the filter 40 may be actually measured by a sensor.

Further, as the amount of PM deposited before the start of the fuel cut increases, the temperature of the filter 40 during the execution of the fuel cut becomes higher. Therefore, even when the integrated air amount after the start of the fuel cut is smaller, the temperature of the filter 40 is the above-mentioned stop temperature. Will reach. Therefore, the fuel cut stop air amount α is set to be smaller as the PM accumulation amount before the start of the fuel cut is larger. In the control device 100 of the present embodiment, the PM deposit amount is calculated based on the engine operating state by a well-known method.

Further, the smaller the intake air amount GA before the start of the fuel cut, the smaller the amount of heat transferred from the filter 40 to the air passing through the filter 40 during the fuel cut, and the higher the temperature of the filter 40 tends to be. Therefore, the temperature of the filter 40 reaches the stop temperature even when the integrated air amount after the start of the fuel cut is smaller. Therefore, the smaller the intake air amount GA before the start of the fuel cut, the smaller the fuel cut stop air amount α is set.

When the fuel cut stop air amount α is calculated in the above S100, the control device 100 determines whether or not the fuel cut is being executed (S110), and when the fuel cut is not executed (S110: NO), this process is performed. Is closed once.

On the other hand, when the fuel cut is being executed (S110: YES), the control device 100 calculates the integrated air amount SA during the fuel cut execution (S120). This integrated air amount SA is an integrated value of the intake air amount GA from the start of the current fuel cut to the present.

Next, the control device 100 determines whether or not the integrated air amount SA up to now is equal to or greater than the fuel cut stop air amount α (S130). Then, when the integrated air amount SA up to now is less than the fuel cut stop air amount α (S130: NO), the control device 100 repeatedly executes the processes of S120 and S130.

On the other hand, when the integrated air amount SA up to now is equal to or greater than the fuel cut stop air amount α (S130: YES), the control device 100 stops the execution of the fuel cut (S140) and restarts the combustion of the air-fuel mixture. , This process is temporarily terminated. If an affirmative determination is made in S130, the control device 100 resets the integrated air amount SA to "0".

Next, with reference to FIG. 3, the operation of the process shown in FIG. 2 above will be described.
As shown in FIG. 3, when the fuel cut is started (time t1) when the accelerator operation amount ACCP becomes "0", the temperature of the filter 40, the PM accumulation amount, and the intake air immediately before the start of the fuel cut are started. The fuel cut stop air amount α calculated based on the amount GA is held as the fuel cut stop air amount α during fuel cut execution. After the start of the fuel cut, the integrated air amount SA increases with the passage of time, and the PM accumulated by the combustion of the PM in the filter 40 decreases. Further, the temperature of the filter 40 rises with the passage of time due to PM combustion in the filter 40.

Then, when the integrated air amount SA reaches the fuel cut stop air amount α, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut (time t2), and the operation is in progress. Fuel cut is canceled. When the fuel cut is stopped in this way, it becomes difficult for PM combustion in the filter 40 to proceed, so that the temperature of the filter 40 decreases.

According to the present embodiment described above, the following effects can be obtained.
(1) During the execution of the fuel cut, the fuel cut is performed until the temperature of the filter 40 reaches the stop temperature, so that the PM deposited on the filter 40 can be burned. Then, when the temperature of the filter 40 reaches the stop temperature during the execution of the fuel cut, the running fuel cut is stopped, so that the damage of the filter 40 due to the excessive temperature rise due to the combustion of PM is suppressed. Will also be possible.

(Second Embodiment)
Next, a second embodiment of the control device for the internal combustion engine will be described with reference to FIGS. 4 and 5.

In the first embodiment, when the integrated air amount SA reaches the fuel cut stop air amount α, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut, and the execution is performed. I tried to stop the fuel cut inside.

On the other hand, in the present embodiment, when the fuel cut duration TC reaches the fuel cut stop time β described later, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut. Therefore, the fuel cut during execution is stopped, and only this point is different from the first embodiment. Therefore, in the following, the present embodiment will be described with a focus on such differences.

FIG. 4 describes a part of the processing executed by the control device 100. The process shown in FIG. 4 is realized by the central processing unit executing the program stored in the memory of the control device 100 at predetermined intervals.

When the process shown in FIG. 4 is started, the control device 100 first calculates the fuel cut stop time β (S200). This fuel cut stop time β is the following value.
That is, as described above, when PM is burned during the execution of the fuel cut, the temperature of the filter 40 rises, but the temperature rise allowance of the filter 40 is supplied to the filter 40 during the execution of the fuel cut. The higher the total amount of oxygen, that is, the longer the duration of the fuel cut, the higher.

Therefore, in order to determine whether or not the temperature of the filter 40 has reached a predetermined temperature, more specifically, the stop temperature during the execution of the fuel cut, the duration of the executed fuel cut is used. As the threshold value for comparison, the fuel cut stop time β is calculated. This fuel cut stop time β is also calculated based on the temperature of the filter 40, the PM accumulation amount of the filter 40, and the intake air amount GA.

More specifically, the higher the temperature of the filter 40 before the start of the fuel cut, the higher the temperature of the filter 40 during the execution of the fuel cut. Therefore, the temperature of the filter 40 is stopped even when the duration of the fuel cut is shorter. It will reach the temperature. Therefore, the higher the temperature of the filter 40 before the start of fuel cut, the shorter the fuel cut stop time β is set. Although the control device 100 of the present embodiment also calculates the temperature of the filter 40 based on the engine operating state by a well-known method, the temperature of the filter 40 may be actually measured by a sensor.

Further, as the amount of PM deposited before the start of the fuel cut increases, the temperature of the filter 40 during the execution of the fuel cut becomes higher. Therefore, the temperature of the filter 40 reaches the above-mentioned stop temperature even when the duration of the fuel cut is shorter. become. Therefore, the fuel cut stop time β is set to be shorter as the PM accumulation amount before the start of the fuel cut is larger. The control device 100 of the present embodiment also calculates the PM deposit amount based on the engine operating state by a well-known method.

Further, the smaller the intake air amount GA before the start of the fuel cut, the smaller the amount of heat transferred from the filter 40 to the air passing through the filter 40 during the fuel cut, and the higher the temperature of the filter 40 tends to be. Therefore, the temperature of the filter 40 reaches the stop temperature even when the duration of the fuel cut is shorter. Therefore, the fuel cut stop time β is set to be shorter as the intake air amount GA before the start of the fuel cut is smaller.

When the fuel cut stop time β is calculated in S200, the control device 100 determines whether or not the fuel cut is being executed (S210), and when the fuel cut is not executed (S210: NO), the present process is temporarily performed. finish.

On the other hand, when the fuel cut is being executed (S210: YES), the control device 100 measures the duration TC of the fuel cut (S220). This duration TC is the continuous elapsed time from the start of the current fuel cut to the present.

Next, the control device 100 determines whether or not the duration TC up to the present is equal to or longer than the fuel cut stop time β (S230). Then, when the duration TC up to the present is less than the fuel cut stop time β (S230: NO), the control device 100 repeatedly executes the processes of S220 and S230.

On the other hand, when the duration TC up to now is equal to or longer than the fuel cut stop time β (S230: YES), the control device 100 stops the execution of the fuel cut (S240), restarts the combustion of the air-fuel mixture, and the present invention. The process is terminated once. If an affirmative determination is made in S230, the control device 100 resets the duration TC to "0".

Next, with reference to FIG. 5, the operation of the process shown in FIG. 4 above will be described.
As shown in FIG. 5, when the fuel cut is started (time t1) when the accelerator operation amount ACCP becomes “0”, the temperature of the filter 40, the PM accumulation amount, and the intake air immediately before the start of the fuel cut are started. The fuel cut stop time β calculated based on the quantity GA is retained as the fuel cut stop time β during fuel cut execution. After the start of the fuel cut, the duration TC increases with the passage of time, and the PM accumulated by burning the PM in the filter 40 decreases. Further, the temperature of the filter 40 rises with the passage of time due to PM combustion in the filter 40.

Then, when the duration TC reaches the fuel cut stop time β, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut (time t2), and the fuel being executed is being executed. The cut is canceled. When the fuel cut is stopped in this way, it becomes difficult for PM combustion in the filter 40 to proceed, so that the temperature of the filter 40 decreases.

According to the present embodiment described above, the following effects can be obtained.
(1) In the present embodiment as in the first embodiment, the fuel cut is performed until the temperature of the filter 40 reaches the stop temperature during the execution of the fuel cut, so that the PM deposited on the filter 40 is collected. Combustion processing becomes possible. Then, when the temperature of the filter 40 reaches the stop temperature during the execution of the fuel cut, the running fuel cut is stopped, so that the damage of the filter 40 due to the excessive temperature rise due to the combustion of PM is suppressed. Will also be possible.

(Third Embodiment)
Next, a third embodiment of the control device for the internal combustion engine will be described with reference to FIG.
In the first embodiment, when the integrated air amount SA reaches the fuel cut stop air amount α, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut, and the execution is performed. I tried to stop the fuel cut inside.

Here, if the fuel cut is stopped and the combustion of the air-fuel mixture is restarted, an output is generated from the internal combustion engine 10 and the driving force of the wheels increases. Therefore, deceleration when the accelerator operation amount ACCP is "0". The feeling tends to be less. In particular, if the feeling of deceleration immediately after the accelerator operation amount ACCP becomes "0", that is, immediately after the start of deceleration is insufficient, the driver of the vehicle may feel a sense of discomfort.

Therefore, in the present embodiment, when the integrated air amount SA reaches the fuel cut stop air amount α, it is determined that the temperature of the filter 40 has reached the stop temperature during the execution of the fuel cut. Even in this case, the fuel cut during execution is not stopped until a sufficient time has passed to obtain a feeling of deceleration. Hereinafter, the present embodiment will be described with a focus on such differences.

FIG. 6 describes a part of the processing executed by the control device 100. The process shown in FIG. 6 is realized by the central processing unit executing the program stored in the memory of the control device 100 at predetermined intervals. In each process shown in FIG. 6, the same step numbers are assigned to the same processes as those described in the first embodiment.

When the process shown in FIG. 6 is started, the control device 100 first calculates the fuel cut stop air amount α (S100).
Next, the control device 100 calculates the fuel cut continuation request time γ (S300). This fuel cut continuation request time γ is the following value.

That is, in order to determine whether or not the fuel cut has elapsed for a time sufficient for the vehicle driver to be satisfied with the feeling of deceleration due to the fuel cut, the above fuel is used as a threshold value to be compared with the duration TC of the fuel cut. The cut continuation request time γ is calculated. The fuel cut continuation request time γ is calculated based on the engine rotation speed NE and the current shift stage of the automatic transmission 60.

More specifically, the fuel cut continuation request time γ is set to a long time so that a feeling of deceleration can be obtained for a long time as the engine rotation speed NE is higher. In addition, the lower the current shift speed (for example, 1st gear or 2nd gear), the stronger the feeling of deceleration due to the engine brake, but the effect of the engine brake decreases early when the gear ratio is low. Then, there is a risk of giving a sense of discomfort to the vehicle driver. Therefore, the lower the current shift stage and the larger the gear ratio, the longer the fuel cut continuation request time γ is set.

Next, the control device 100 determines whether or not the fuel cut is being executed (S110), and when the fuel cut is not executed (S110: NO), the present process is temporarily terminated.
On the other hand, when the fuel cut is being executed (S110: YES), the control device 100 calculates the integrated air amount SA during the fuel cut execution (S120) and measures the fuel cut duration TC (S310). ). This duration TC is the same time as the duration TC described in the second embodiment.

Next, the control device 100 determines whether or not the integrated air amount SA up to now is equal to or greater than the fuel cut stop air amount α (S130). Then, when the integrated air amount SA up to now is less than the fuel cut stop air amount α (S130: NO), the control device 100 repeatedly executes the processes of S120, S310, and S130.

On the other hand, when the integrated air amount SA up to now is equal to or greater than the fuel cut stop air amount α (S130: YES), the control device 100 determines whether or not the above-mentioned duration TC up to now is equal to or longer than the fuel cut continuation request time γ. (S320).

Then, when the duration TC is less than the fuel cut continuation request time γ (S320: NO), the control device 100 repeatedly executes the processes of S120 and S310 and S130 and S320.

On the other hand, when the duration TC is equal to or longer than the fuel cut continuation request time γ (S320: YES), the control device 100 stops the execution of the fuel cut (S140), restarts the combustion of the air-fuel mixture, and performs this process. It ends once. If an affirmative determination is made in S320, the control device 100 resets both the integrated air amount SA and the duration TC to "0".

In the present embodiment described above, the following effects can be obtained.
(2) Even if the integrated air amount SA reaches the fuel cut stop air amount α, if the duration TC does not reach the fuel cut continuation request time γ, the fuel cut is executed without being stopped. .. Therefore, it becomes easy to obtain a feeling of deceleration due to the fuel cut, and it is possible to reduce the feeling of discomfort given to the vehicle driver.

Incidentally, even in the present embodiment, if the duration TC becomes the fuel cut continuation required time γ or more, the fuel cut during execution is stopped, so that the filter 40 is damaged due to an excessive temperature rise due to the combustion of PM. It is possible to suppress it.

Each of the above embodiments can be modified and implemented as follows. Each of the above embodiments and the following modification examples can be implemented in combination with each other within a technically consistent range.

The fuel cut stop air amount α may be calculated based on at least one of the temperature of the filter 40, the PM accumulation amount of the filter 40, and the intake air amount GA.
The fuel cut stop time β may be calculated based on at least one of the temperature of the filter 40, the PM deposition amount of the filter 40, and the intake air amount GA.

-The calculation of the fuel cut stop time β and the measurement of the duration TC described in the second embodiment are also performed in the first embodiment. Then, when the integrated air amount SA is the fuel cut stop air amount α or more, or when the duration TC is the fuel cut stop time β or more, the running fuel cut is stopped and the combustion of the air-fuel mixture is restarted. You may.

-The calculation of the fuel cut stop time β described in the second embodiment is also performed in the third embodiment. Then, the longer of the calculated fuel cut stop time β and the fuel cut continuation request time γ is selected, and the selected time is compared with the duration TC. Then, when the duration TC is equal to or longer than the above-selected time, the running fuel cut may be stopped and the combustion of the air-fuel mixture may be restarted.

In the third embodiment, the fuel cut continuation request time γ is calculated based on the engine rotation speed NE and the current shift stage of the automatic transmission 60, but the engine rotation speed NE and the current shift stage of the automatic transmission 60 are calculated. The fuel cut continuation request time γ may be calculated based on either one. Further, the fuel cut continuation request time γ may be set to a predetermined fixed value.

In the third embodiment, the fuel cut continuation request time γ is calculated based on the current transmission stage of the automatic transmission 60, but the automatic transmission 60 can continuously change the gear ratio of the continuously variable transmission. In the case of, the current gear ratio of the continuously variable transmission may be applied instead of the gear shift.

10 ... Internal combustion engine, 11 ... Cylinder, 12 ... Fuel injection valve, 20 ... Exhaust passage, 30 ... Three-way catalyst, 40 ... Filter, 50 ... Torque converter, 60 ... Automatic transmission, 71 ... Crank angle sensor, 72 ... Air flow Meter, 73 ... Vehicle speed sensor, 74 ... Accelerator sensor, 75 ... Air-fuel ratio sensor, 100 ... Control device.

Claims (1)

A control device that is applied to an internal combustion engine equipped with a filter that collects particulate matter in the exhaust in the exhaust passage, and executes fuel cut control that stops fuel injection in the internal combustion engine when a predetermined fuel cut condition is satisfied. And
When it is determined that the parameter increasing during the execution of the fuel cut control has reached the threshold value , a process of stopping the running fuel cut is executed .
The threshold is set based on at least one of the temperature of the filter immediately before the start of the fuel cut, the amount of particulate matter deposited on the filter immediately before the start of the fuel cut, and the amount of intake air immediately before the start of the fuel cut. calculate
Internal combustion engine control device.

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