JP2019190358A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine capable of performing combustion treatment of accumulated PM while suppressing damage of a filter.SOLUTION: An internal combustion engine 10 includes a filter 40 for capturing particulate matters in an exhaust gas in an exhaust passage 20. A control device 100 executes fuel cut control for stopping fuel injection in the internal combustion engine 10 when a prescribed fuel cut condition is satisfied. The control device 100 executes a treatment for stopping the fuel cut under execution, when a condition that a temperature of the filter 40 reaches a prescribed temperature during the execution of fuel cut, is determined.SELECTED DRAWING: Figure 1

Description

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

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

  By the way, if the PM combustion proceeds excessively during 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 overheated when the fuel cut is started, the start of the fuel cut is prohibited.

JP 2011-99451 A

However, if the start of the fuel cut is prohibited as described above, the PM combustion process using the fuel cut cannot be performed, and 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 performing combustion treatment of accumulated PM while suppressing damage to a filter.

  A control device for an internal combustion engine that solves the above problem is applied to an internal combustion engine that includes a filter that collects particulate matter in exhaust gas in an exhaust passage, and fuel in the internal combustion engine is satisfied when a predetermined fuel cut condition is satisfied. Fuel cut control for stopping injection is executed. Then, when it is determined that the temperature of the filter has reached a predetermined temperature during execution of fuel cut, the control device executes processing for stopping the fuel cut being executed.

  According to this configuration, during 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 predetermined temperature during the fuel cut, the fuel cut being performed is stopped, so that it is possible to suppress damage to the filter due to an excessive temperature rise caused by PM combustion. become.

The schematic diagram which shows the internal combustion engine and control apparatus in 1st Embodiment. The flowchart which shows the procedure of the process which the control apparatus of the embodiment performs. The timing chart which shows the effect | action of the same embodiment. The flowchart which shows the procedure of the process which a control apparatus performs in 2nd Embodiment. The timing chart which shows the effect | action of the same embodiment. The flowchart which shows the procedure of the process which a control apparatus performs in 3rd Embodiment.

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

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

The internal combustion engine 10 includes a plurality of cylinders 11. Each cylinder 11 is provided with a fuel injection valve 12 that injects fuel and an ignition plug (not shown) that generates spark discharge.
In the exhaust passage 20 of the internal combustion engine 10, a known three-way catalyst 30 and a filter 40 that collects particulate matter (PM) in the exhaust are provided in order from the exhaust upstream.

  The crankshaft of the internal combustion engine 10 is connected to a torque converter 50 that includes a lock-up clutch (not shown). The output shaft of the torque converter 50 is connected to the input shaft of the multistage automatic transmission 60.

  Various controls of 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 performs various controls by causing the central processing unit to execute a program stored in the memory.

  The control device 100 refers to the engine rotational 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 of the vehicle detected by the vehicle speed sensor 73 in order to perform various controls. To do. In addition, the control device 100 detects 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. Reference is also made to the fuel ratio AF and the like.

  As one of the 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, a condition that the accelerator operation amount ACCP is “0” and the engine rotational speed NE is equal to or higher than a predetermined fuel cut return rotational speed is set. When the fuel cut condition is satisfied, the fuel injection from the fuel injection valve 12 is stopped. When the engine speed NE becomes equal to or lower than the fuel cut return rotational speed during the fuel cut, fuel injection is started again.

  In addition, 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, a shift stage instruction value 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 gear position of the automatic transmission 60 becomes the instruction value.

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

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 is the following value.
That is, when oxygen is supplied to the high-temperature filter 40 by executing the fuel cut, the PM deposited on the filter 40 is burned and the filter 40 is regenerated.

  Here, when the PM is burned during the fuel cut, the temperature of the filter 40 rises. The temperature rise of the filter 40 is the total amount of oxygen supplied to the filter 40 during the fuel cut. The higher the value, that is, the higher 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 during the fuel cut, more specifically, a stop temperature set to a temperature lower by a predetermined value than the temperature at which the filter 40 melts. Therefore, the fuel cut stop air amount α is calculated as a threshold value to be compared with the integrated air amount during the fuel cut. 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 starting the fuel cut, the higher the temperature of the filter 40 during 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. Reaches the discontinuation temperature. Therefore, the fuel cut stop air amount α is set to be smaller as the temperature of the filter 40 before the fuel cut starts is higher. In addition, although the control apparatus 100 of this embodiment is calculating the temperature of the filter 40 based on an engine operating state by a known method, you may measure the temperature of the filter 40 with a sensor.

  Further, the greater the amount of PM accumulated before the start of fuel cut, the higher the temperature of the filter 40 during execution of fuel cut. Therefore, the temperature of the filter 40 can be maintained even when the accumulated air amount after the start of fuel cut is smaller. To reach. Therefore, the fuel cut stop air amount α is set to be smaller as the PM accumulation amount before the fuel cut starts is larger. In addition, in the control apparatus 100 of this embodiment, calculation of PM deposition amount based on an engine operation state is performed by a known method.

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

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

  On the other hand, when the fuel cut is being performed (S110: YES), the control device 100 calculates the integrated air amount SA during the fuel cut (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 the present is equal to or greater than the fuel cut stop air amount α (S130). When the integrated air amount SA up to the present is less than the fuel cut suspension air amount α (S130: NO), the control device 100 repeatedly executes the processing 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 fuel cut (S140) and restarts the combustion of the air-fuel mixture. This processing is once terminated. If the determination in step S130 is affirmative, the control device 100 resets the accumulated air amount SA to “0”.

Next, the operation of the process shown in FIG. 2 will be described with reference to FIG.
As shown in FIG. 3, when the fuel cut is started because the accelerator operation amount ACCP becomes “0” (time t1), the temperature of the filter 40 immediately before the start of the fuel cut, the PM accumulation amount, and the intake air 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. Then, after the start of the fuel cut, the accumulated air amount SA increases with the passage of time, and the PM accumulated by the PM burning in the filter 40 decreases. Further, the temperature of the filter 40 rises with time due to PM combustion in the filter 40.

  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 execution of the fuel cut (time t2). The fuel cut is canceled. When the fuel cut is stopped in this way, PM combustion in the filter 40 becomes difficult to proceed, so the temperature of the filter 40 decreases.

According to this embodiment described above, the following effects can be obtained.
(1) While the fuel cut is being performed, 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. During the fuel cut, when the temperature of the filter 40 reaches the above stop temperature, the fuel cut being executed is stopped, so that damage to the filter 40 due to an excessive temperature rise caused by PM combustion is suppressed. Will also be possible.

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

  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 execution of the fuel cut. The fuel cut inside was stopped.

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

  FIG. 4 illustrates a part of the process executed by the control device 100. The processing shown in FIG. 4 is realized by the central processing unit executing a 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 suspension time β (S200). This fuel cut suspension time β is the following value.
That is, as described above, when PM is burned during the fuel cut, the temperature of the filter 40 rises. However, the temperature rise of the filter 40 is supplied to the filter 40 during 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 the predetermined temperature during the fuel cut, and more specifically, whether or not the temperature has reached the stop temperature, The fuel cut suspension time β is calculated as a threshold for comparison. This fuel cut suspension 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 starting the fuel cut, the higher the temperature of the filter 40 during 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 reaches the temperature. Therefore, the fuel cut suspension time β is set to be shorter as the temperature of the filter 40 before the fuel cut starts is higher. In addition, although the control apparatus 100 of this embodiment is also performing the temperature calculation of the filter 40 based on an engine operating state by a known method, you may measure the temperature of the filter 40 with a sensor.

  In addition, since the temperature of the filter 40 during fuel cut increases as the amount of PM accumulated before the start of fuel cut increases, the temperature of the filter 40 reaches the stop temperature even when the duration of fuel cut is shorter. become. Therefore, the fuel cut stop time β is set to be shorter as the PM accumulation amount before the fuel cut starts is larger. In the control device 100 of this embodiment, the calculation of the PM accumulation amount based on the engine operation state is performed by a known method.

  Further, as the intake air amount GA before the start of fuel cut is smaller, the amount of heat transferred from the filter 40 to the air passing through the filter 40 decreases during the fuel cut, and the temperature of the filter 40 tends to increase. Therefore, the temperature of the filter 40 reaches the stop temperature even when the fuel cut duration is shorter. Therefore, the fuel cut stop time β is set to be shorter as the intake air amount GA before the fuel cut starts 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). When the fuel cut is not being executed (S210: NO), this process is temporarily performed. finish.

  On the other hand, when the fuel cut is being executed (S210: YES), the control device 100 measures the fuel cut duration TC (S220). This continuation time TC is a 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 time TC up to the present is equal to or longer than the fuel cut suspension time β (S230). When the duration time TC up to the present time is less than the fuel cut suspension time β (S230: NO), the control device 100 repeatedly executes the processes of S220 and S230.

  On the other hand, when the duration time TC up to now is equal to or longer than the fuel cut stop time β (S230: YES), the control device 100 stops the fuel cut (S240), restarts the combustion of the air-fuel mixture, The process is temporarily terminated. If the determination in step S230 is affirmative, the control device 100 resets the duration TC to “0”.

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

  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 fuel cut (time t2), and the fuel being executed The cut is canceled. When the fuel cut is stopped in this manner, PM combustion in the filter 40 becomes difficult to proceed, so the temperature of the filter 40 decreases.

According to this embodiment described above, the following effects can be obtained.
(1) In the present embodiment as well, in the same manner as in the first embodiment, the fuel cut is performed until the temperature of the filter 40 reaches the stop temperature during execution of the fuel cut. Combustion treatment can be performed. During the fuel cut, when the temperature of the filter 40 reaches the above stop temperature, the fuel cut being executed is stopped, so that damage to the filter 40 due to an excessive temperature rise caused by PM combustion is suppressed. Will also be possible.

(Third embodiment)
Next, a third embodiment of the control device for an 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 execution of the fuel cut. The fuel cut inside was stopped.

  Here, when the fuel cut is stopped and the combustion of the air-fuel mixture is resumed, 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”. There is a tendency to feel less. In particular, if the feeling of deceleration immediately after the accelerator operation amount ACCP becomes “0”, that is, immediately after starting deceleration, the driver of the vehicle may feel uncomfortable.

  Therefore, in this 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 fuel cut. Even in such a case, the fuel cut that is being executed is not stopped until a sufficient time for a feeling of deceleration has elapsed. Hereinafter, this embodiment will be described focusing on such differences.

  FIG. 6 illustrates a part of the processing executed by the control device 100. The processing shown in FIG. 6 is realized by the central processing unit executing a program stored in the memory of the control device 100 at predetermined intervals. In addition, in each process shown in FIG. 6, the same step number is attached | subjected about the same process as the process demonstrated in 1st Embodiment.

When the processing 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 a 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 been performed for a time sufficient for the vehicle driver to satisfy the feeling of deceleration due to the fuel cut, the above fuel is used as a threshold to be compared with the fuel cut duration TC. The cut continuation request time γ is calculated. This fuel cut continuation request time γ is calculated based on the engine speed NE and the current gear position of the automatic transmission 60.

  More specifically, the fuel cut continuation request time γ is set to a longer time so that the feeling of deceleration can be obtained for a longer time as the engine speed NE is higher. Also, the lower the current gear position (for example, 1st gear speed or 2nd gear speed), the greater the gear ratio, the stronger the feeling of deceleration due to engine braking, but the engine braking effect decreases earlier when the gear speed is low. Then, there is a possibility that the vehicle driver may feel uncomfortable. Therefore, the longer the current gear position is and the larger the gear ratio is, the longer the fuel cut continuation request time γ is set.

Next, the control device 100 determines whether or not a fuel cut is being executed (S110), and when the fuel cut is not being executed (S110: NO), this 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 (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 the present is equal to or greater than the fuel cut stop air amount α (S130). When the integrated air amount SA up to now is less than the fuel cut suspension 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 the present is equal to or greater than the fuel cut stop air amount α (S130: YES), the control device 100 determines whether or not the duration TC up to the present is equal to or longer than the fuel cut continuation request time γ. Is determined (S320).

  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, S310, 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 fuel cut (S140), restarts the combustion of the air-fuel mixture, and performs this process. Exit once. If the determination in step S320 is affirmative, 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 operational effects can be obtained.
(2) Even if the integrated air amount SA has reached the fuel cut stop air amount α, if the duration TC has not reached the fuel cut stop request time γ, the fuel cut is executed without being stopped. . Therefore, a feeling of deceleration due to the fuel cut can be easily obtained, and the uncomfortable feeling given to the vehicle driver can be reduced.

  Incidentally, even in the present embodiment, if the duration TC is equal to or longer than the fuel cut continuation request time γ, the fuel cut in progress is stopped, so that the filter 40 is damaged due to an excessive temperature rise caused by PM combustion. It is possible to suppress.

  In addition, each said embodiment can be changed and implemented as follows. The above embodiments and the following modifications 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 suspension time β 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 calculation of the fuel cut suspension time β and the measurement of the duration time TC described in the second embodiment are also performed in the first embodiment. When the accumulated air amount SA is equal to or greater than the fuel cut suspension air amount α or when the duration TC is equal to or greater than the fuel cut suspension time β, the fuel cut that is being performed is stopped and the combustion of the air-fuel mixture is resumed. May be.

  The calculation of the fuel cut suspension time β described in the second embodiment is also performed in the third embodiment. Then, the longer one 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 selected time, the fuel cut being performed may be stopped and the combustion of the air-fuel mixture may be resumed.

  In the third embodiment, the fuel cut continuation request time γ is calculated based on the engine rotational speed NE and the current gear position of the automatic transmission 60. However, the engine speed NE and the current gear position 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 gear position of the automatic transmission 60, but the continuously variable transmission in which the automatic transmission 60 can continuously change the gear ratio. In this case, the current gear ratio of the continuously variable transmission may be applied instead of the gear position.

  DESCRIPTION OF SYMBOLS 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 that includes a filter that collects particulate matter in exhaust gas in an exhaust passage, and that performs fuel cut control that stops fuel injection in the internal combustion engine when a predetermined fuel cut condition is satisfied Because
A control device for an internal combustion engine that executes a process of canceling a fuel cut that is being executed when it is determined that the temperature of the filter has reached a predetermined temperature during the execution of a fuel cut.