Control device for vehicle

Abstract

To prevent excessive rise in a temperature of a filter and prevent repeated change of deceleration in a vehicle.SOLUTION: A control device 100 executes: fuel cut for stopping fuel injection by using a fuel injection valve 22 during deceleration of a vehicle 500; interruption of the fuel cut when a duration from start of the fuel cut becomes longer than an allowable time; and prohibition of start of the fuel cut until a temperature of a filter 34 becomes a determination temperature or lower when frequency of interrupting the fuel cut reaches predetermined frequency within a predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] The internal combustion engine disclosed in Patent Document 1 includes a fuel injection valve and a filter. The fuel injection valve injects fuel to be supplied into a cylinder. The filter is located midway through an exhaust passage. The filter collects particulate matter in the exhaust. When a predetermined execution condition is met, a control device for this internal combustion engine performs a fuel cut to stop fuel injection from the fuel injection valve. When the control device performs the fuel cut, oxygen is supplied to the filter. As a result, the particulate matter accumulated on the filter is burned.

[0003] However, when fuel is cut off, the temperature of the filter rises as particulate matter accumulated on the filter is burned. If the temperature of the filter rises excessively, the filter may be damaged. Therefore, the control device interrupts the fuel cut as necessary to prevent the filter from overheating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-190358 A Summary of the Invention [Problem to be solved by the invention]

[0005] In a technology such as that of Patent Document 1, in which fuel cut is interrupted, fuel injection is resumed and the internal combustion engine outputs torque when fuel cut is interrupted. This causes the deceleration of the vehicle to change during deceleration. If such changes in deceleration are repeated many times, the passengers will feel uncomfortable. On the other hand, if the fuel cut is not interrupted, excessive heating of the filter cannot be avoided. [Means for solving the problem]

[0006] A vehicle control device for solving the above problem is applied to a vehicle equipped with an internal combustion engine having a fuel injection valve that injects fuel to be supplied into a cylinder and a filter that collects particulate matter in the exhaust discharged from the cylinder, and performs a fuel cut to stop fuel injection by the fuel injection valve while the vehicle is decelerating, interrupts the fuel cut if the duration since the start of the fuel cut becomes longer than a predetermined allowable time, and prohibits the start of the fuel cut until the temperature of the filter falls below a predetermined judgment temperature if the number of times the fuel cut is interrupted within a predetermined period of time reaches a predetermined number. Effect of the Invention

[0007] The above technical concept can prevent the filter from overheating and can prevent repeated changes in deceleration in the vehicle. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an internal combustion engine. [Diagram 2] FIG. 2 is a diagram showing an example of a time map. [Diagram 3] FIG. 3 is a flowchart showing the procedure of the flag setting process. [Figure 4] FIG. 4 is a flowchart showing the procedure of the execution process. [Diagram 5] FIG. 5 is a time chart showing an example of changes over time in each parameter related to the interruption of fuel cut. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <Internal combustion engine> An embodiment of a vehicle control device will be described below with reference to the drawings. As shown in Fig. 1, a vehicle 500 includes an internal combustion engine 10. The internal combustion engine 10 is a drive source of the vehicle 500.

[0010] The internal combustion engine 10 includes a plurality of cylinders 12 and a crankshaft 11. The cylinders 12 are spaces partitioned in an engine body 10A for burning a mixture of fuel and intake air. The crankshaft 11 rotates in response to the combustion of the mixture in the cylinders 12. The crankshaft 11 is connected to wheels 502 via an automatic transmission 501 and the like.

[0011] The internal combustion engine 10 has a plurality of spark plugs 19. The spark plugs 19 are provided for each cylinder 12. The spark plugs 19 ignite the air-fuel mixture in the cylinders 12. The internal combustion engine 10 includes an intake passage 20, a throttle valve 21, and a plurality of fuel injection valves 22. The intake passage 20 is a passage for introducing intake air into each cylinder 12. The intake passage 20 is connected to each cylinder 12. The throttle valve 21 is located midway through the intake passage 20. The throttle valve 21 adjusts the amount of intake air GA. A fuel injection valve 22 is provided for each cylinder 12. The fuel injection valve 22 is located downstream of the throttle valve 21 in the intake passage 20. The fuel injection valve 22 injects fuel. The fuel injected by the fuel injection valve 22 reaches the inside of the cylinder 12 via the intake passage 20. That is, the fuel injection valve 22 injects fuel to be supplied into the cylinder 12.

[0012] The internal combustion engine 10 includes an exhaust passage 30, a three-way catalyst 32, and a gasoline particulate filter (hereinafter simply referred to as the filter) 34. The exhaust passage 30 is a passage for discharging exhaust gas from each cylinder 12. The exhaust passage 30 is connected to each cylinder 12. The three-way catalyst 32 is located midway through the exhaust passage 30. The three-way catalyst 32 purifies hydrocarbons, carbon monoxide, and nitrogen oxides in the exhaust gas. The filter 34 is located downstream of the three-way catalyst 32 in the exhaust passage 30. The filter 34 collects particulate matter (hereinafter referred to as PM) in the exhaust gas.

[0013] The internal combustion engine 10 is equipped with an air flow meter 61, an air-fuel ratio sensor 62, an exhaust temperature sensor 63, and a crank position sensor 64. The air flow meter 61 detects the intake air amount GA and the intake air temperature TI. The air-fuel ratio sensor 62 detects the exhaust air-fuel ratio AF, which is the air-fuel ratio of the exhaust gas flowing into the filter 34. The exhaust temperature sensor 63 detects the temperature TO of the exhaust gas flowing into the filter 34. The crank position sensor 64 detects the rotational position CR of the crankshaft 11. Each of these sensors repeatedly outputs a signal corresponding to the information detected by it to the control device 100, which will be described later.

[0014] <Other vehicle configurations> The vehicle 500 is equipped with an accelerator sensor 91, a vehicle speed sensor 92, and an ignition switch 93. The accelerator sensor 91 detects the amount of depression of the accelerator pedal in the vehicle 500 as an accelerator operation amount ACC. The vehicle speed sensor 92 detects the traveling speed of the vehicle 500 as a vehicle speed SP. Each of these sensors repeatedly outputs a signal corresponding to the information detected by the sensor to a control device 100 described later. The ignition switch 93 is a switch for starting the vehicle 500. The ignition switch 93 outputs a signal Y corresponding to an operation by a passenger to the control device 100 described later.

[0015] <Control device> The vehicle 500 includes a control device 100. The control device 100 includes a CPU 101 and a memory 102. The memory 102 prestores various programs in which processes to be executed by the CPU 101 are described. The CPU 101 controls the internal combustion engine 10 by executing the programs stored in the memory 102. There are three types of memory 102: RAM, ROM, and an electrically rewritable non-volatile type.

[0016] The CPU 101 receives a signal Y from the ignition switch 93. When the CPU 101 receives the signal Y in response to the ignition switch 93 being turned on, the CPU 101 starts the internal combustion engine 10. Hereinafter, the period from when the ignition switch 93 is turned on to when it is next turned off is referred to as "one trip." During one trip, the CPU 101 repeatedly receives detection signals from various sensors attached to the vehicle 500.

[0017] During one trip, CPU 101 repeatedly calculates various parameters based on detection signals received from various sensors. For example, CPU 101 calculates the engine speed, which is the rotation speed of crankshaft 11, based on the rotation position CR of crankshaft 11. CPU 101 also calculates PM accumulation amount DA as follows. PM accumulation amount DA is the amount of PM accumulated in filter 34. Note that, as described below, CPU 101 also calculates filter temperature TF, which is the temperature of filter 34, in the process of calculating PM accumulation amount DA.

[0018] When calculating the PM accumulation amount DA, the CPU 101 calculates the PM generation amount and the PM regeneration amount. The CPU 101 updates the PM accumulation amount DA to calculate the PM accumulation amount DA. Specifically, the CPU 101 updates the PM accumulation amount DA by adding the difference obtained by subtracting the PM regeneration amount from the PM generation amount to the PM accumulation amount DA before updating. The PM generation amount is the amount of PM generated by the combustion of the mixture in the cylinder 12. The CPU 101 calculates the PM generation amount from the intake air amount GA, the fuel injection amount, and the like. The PM regeneration amount is the amount of PM burned in the filter 34. The higher the temperature TO of the exhaust gas flowing into the filter 34, the higher the filter temperature TF. Therefore, the filter temperature TF can be obtained from the temperature TO of the exhaust gas detected by the exhaust temperature sensor 63. The CPU 101 calculates the filter temperature TF using a heat balance model of the filter 34 based on the temperature TO and flow rate of the exhaust gas flowing into the filter 34 and the temperature of the outside air. The flow rate of the exhaust gas flowing into the filter 34 can be obtained from the intake air amount GA and the fuel injection amount. Furthermore, the temperature of the outside air can be the temperature of the intake air TI detected by the air flow meter 61. When exhaust gas containing oxygen flows into the filter 34 in a state where the filter temperature TF is equal to or higher than the ignition point of the PM, the PM accumulated on the filter 34 begins to burn. Since oxygen is necessary for the combustion of PM, the amount of PM burned in the filter 34 at this time is determined according to the amount of oxygen in the exhaust gas flowing into the filter 34. The oxygen concentration of the exhaust gas flowing into the filter 34 can be obtained from the detection result of the air-fuel ratio sensor 62. Therefore, the CPU 101 calculates the PM regeneration amount based on the exhaust temperature TO detected by the exhaust temperature sensor 63, the oxygen concentration detected by the air-fuel ratio sensor 62, i.e., the exhaust air-fuel ratio AF, the intake air amount GA, and the fuel injection amount.

[0019] <Normal processing> During one trip, the CPU 101 basically controls the internal combustion engine 10 by normal processing. In the normal processing, the CPU 101 calculates a target torque of the internal combustion engine 10 based on the accelerator operation amount ACC, the vehicle speed SP, and the like. Then, the CPU 101 adjusts the opening of the throttle valve 21, injects fuel from the fuel injection valve 22, and performs ignition by the spark plug 19 so as to obtain the target torque. In this way, the CPU 101 burns the air-fuel mixture in the cylinders 12. In the normal processing, the CPU 101 repeats the calculation of the target torque and the control of various parts based on the target torque. In this way, the CPU 101 repeats the combustion of the air-fuel mixture in each cylinder 12.

[0020] During deceleration of the vehicle 500, the CPU 101 may cancel the above-described normal processing and perform a fuel cut to stop fuel injection by each fuel injection valve 22. The following describes processing performed by the CPU 101 in relation to the fuel cut.

[0021] <Flag setting process> The CPU 101 can execute a flag setting process. The flag setting process is a process for setting an inhibition flag to on or off. The inhibition flag is a flag that indicates the inhibition of the start of a fuel cut. When the inhibition flag is off, it means that the start of a fuel cut is permitted. When the inhibition flag is on, it means that the start of a fuel cut is prohibited.

[0022] The CPU 101 repeatedly executes the flag setting process during one trip. If the ignition switch 93 is turned off during the execution of the flag setting process, the CPU 101 ends the flag setting process at that point.

[0023] 3, when CPU 101 starts the flag setting process, it first performs the process of step S310. In step S310, CPU 101 sets the prohibition flag to OFF. After that, CPU 101 advances the process to step S320.

[0024] In step S320, CPU 101 resets the number of fuel cut interruptions N to 0. This number of interruptions N is updated as needed in the execution process described below. After this, CPU 101 advances the process to step S330.

[0025] In step S330, CPU 101 determines whether or not the interruption count N is equal to "1." If the interruption count N is not "1," CPU 101 executes the process of step S330 again. CPU 101 repeats the process of step S330 until the interruption count N becomes "1." Then, when the interruption count N becomes "1," CPU 101 starts measuring time and causes the process to proceed to step S340.

[0026] In step S340, CPU 101 determines whether the time that has elapsed since the number of interruptions N became "1" is longer than a predetermined time P. Memory 102 stores the predetermined time P in advance. In this embodiment, the predetermined time P is 10 seconds. The perspective by which the predetermined time P is determined will be explained later together with the predetermined number of interruptions NK, which will be described later. In step S340, if the time that has elapsed since the number of interruptions N became "1" is equal to or less than the predetermined time P (step S340: NO), CPU 101 advances the process to step S350.

[0027] A number that is one less than the interruption count N is called the provisional interruption count. In step S350, the CPU 101 judges whether the provisional interruption count matches the predetermined number NK. The memory 102 stores the predetermined number NK in advance. In this embodiment, the predetermined number NK is two times. If the provisional interruption count does not match the predetermined number NK (step S350: NO), the CPU 101 returns to the process of step S340. Then, the CPU 101 executes the process of step S340 again. After this, if the judgment of step S340 is NO and the judgment of step S350 continues to be NO, the CPU 101 repeats the processes of steps S340 and S350. In the course of this repetition, if the time that has elapsed since the interruption count N became "1" becomes longer than the predetermined time P (step S340: YES) before the provisional interruption count reaches the predetermined number NK (step S350: NO), the CPU 101 ends the series of processes of the flag setting process. Then, CPU 101 executes the process of step S310 again. When CPU 101 ends the flag setting process, it also ends the time measurement started in step S330.

[0028] On the other hand, when the time elapsed since the interruption count N became "1" is within the predetermined time P (step S340: NO) and the provisional interruption count matches the predetermined number NK (step S350: YES), CPU 101 proceeds to step S360. In this case, CPU 101 ends the time measurement started in step S330 at this point.

[0029] In step S360, CPU 101 switches the prohibition flag on, and then CPU 101 advances the process to step S370. In step S370, the CPU 101 judges whether the filter temperature TF is equal to or lower than the judgment temperature TK. The memory 102 prestores the judgment temperature TK. In this embodiment, the judgment temperature TK is 500 degrees. The judgment temperature TK is determined in advance, for example, by an experiment or a simulation, as a temperature at which PM combustion is possible in the filter 34 but which is considerably lower than the temperature at which the filter 34 is damaged. If the latest filter temperature TF is higher than the judgment temperature TK (step S370: NO), the CPU 101 executes the process of step S370 again. The CPU 101 repeats the process of step S370 until the filter temperature TF becomes equal to or lower than the judgment temperature TK. Then, when the filter temperature TF becomes equal to or lower than the judgment temperature TK (step S370: YES), the CPU 101 ends the series of processes of the filter setting process. Then, the CPU 101 executes the process of step S310 again.

[0030] In the above flag setting process, the CPU 101 performs the following process. That is, when the number of provisional interruptions reaches a predetermined number NK while the time elapsed since the number of interruptions N became "1" is within the predetermined time P, the CPU 101 turns on the prohibition flag until the filter temperature TF becomes equal to or lower than the judgment temperature TK. The number of provisional interruptions is the number of interruptions of fuel cut after one interruption of fuel cut.

[0031] <Execution process> The CPU 101 can execute the execution process. The execution process is a process for executing a fuel cut. When the execution condition of the fuel cut is switched from an unsatisfied state to a satisfied state during one trip, the CPU 101 starts the execution process. The execution condition of the fuel cut is that all of the following three requirements are satisfied. The first requirement is that the vehicle 500 is decelerating. The second requirement is that the engine rotation speed is equal to or higher than the return rotation speed. The third requirement is that the prohibition flag is off. The CPU 101 determines whether the execution condition of the fuel cut is satisfied at any time based on the latest information of parameters necessary for determining each requirement, such as the vehicle speed SP, the engine rotation speed, and the prohibition flag. Then, the CPU 101 starts the execution process every time the execution condition of the fuel cut is switched to a satisfied state. The CPU 101 may determine whether the first requirement is satisfied based on the accelerator operation amount ACC. In this case, the CPU 101 can determine that the vehicle 500 has started to decelerate, that is, the vehicle 500 is decelerating, when the accelerator operation amount ACC switches from a state in which the accelerator operation amount ACC is greater than zero to zero. The return rotation speed in the second requirement is predetermined as a value that can avoid stalling of the internal combustion engine 10 when fuel injection and combustion of the air-fuel mixture are resumed after the fuel cut.

[0032] As shown in FIG. 4, when the CPU 101 starts the execution process, it first executes the process of step S110. In step S110, the CPU 101 calculates the permissible time H. The permissible time H is the length of time that one fuel cut can be continued that is permissible from the current state of the filter 34. As a premise for the CPU 101 to calculate the permissible time H, the memory 102 stores a time map in advance. The time map represents the relationship between the filter temperature TF, the PM accumulation amount DA, and the permissible time H. Specifically, the time map is a graph or table representing the permissible time H applicable to each combination of various combinations of the filter temperature TF and the PM accumulation amount DA. In the example shown in FIG. 2, the time map is represented as a graph with the filter temperature TF on the X axis and the PM accumulation amount DA on the Y axis. Note that in FIG. 2, in order to make the relationship between the filter temperature TF, the PM accumulation amount DA, and the permissible time H easy to understand, only three permissible times H are shown as representatives for convenience. The three permissible times H in FIG. 2 have a relationship of "first time H1<second time H2<third time H3". In the example shown in FIG. 2, the isolines corresponding to the first time H1, the second time H2, and the third time H3 are represented by straight lines, but this is also for convenience. As shown in FIG. 2, the filter temperature TF, the PM accumulation amount DA, and the permissible time H have the following relationship. For the same filter temperature TF, the larger the PM accumulation amount DA, the shorter the permissible time H. For the same PM accumulation amount DA, the higher the filter temperature TF, the shorter the permissible time H. The CPU 101 calculates the permissible time H based on such a time map. Specifically, the CPU 101 refers to the latest PM accumulation amount DA and the latest filter temperature TF along with this time map. Then, the CPU 101 calculates the permissible time H corresponding to the latest PM accumulation amount DA and the latest filter temperature TF as the permissible time H for the current fuel cut based on the time map. Reflecting the contents of the time map, the CPU 101 sets the permissible time H shorter as the PM accumulation amount DA increases for the same filter temperature TF. Also, the CPU 101 sets the permissible time H shorter as the filter temperature TF increases for the same PM accumulation amount DA.As shown in FIG. 4, after CPU 101 sets permissible time H, the process proceeds to step S120.

[0033] In step S120, the CPU 101 cancels the normal process and starts a fuel cut. That is, the CPU 101 stops the fuel injection from each fuel injection valve 22. The CPU 101 also starts measuring time. After this, the CPU 101 advances the process to step S130.

[0034] In step S130, CPU 101 determines whether the duration since the start of fuel cut is longer than the allowable time H previously determined in step S110. The duration since the start of fuel cut is also referred to as the elapsed time since the start of fuel cut. If the duration is equal to or less than the allowable time H (step S130: NO), CPU 101 advances the process to step S210.

[0035] In step S210, the CPU 101 determines whether or not the execution condition for fuel cut is satisfied at the present time. If the execution condition for fuel cut is satisfied (step S210: YES), the CPU 101 returns to the process of step S130. Then, the CPU 101 executes the process of step S130 again. After that, if the determination in step S130 is NO and the determination in step S210 is YES, the CPU 101 repeats the processes of step S130 and step S210. In the course of such repetition, if the execution condition for fuel cut is not satisfied before the duration from the start of fuel cut becomes longer than the permissible time H (step S210: NO), the CPU 101 proceeds to the process of step S220. In this case, the CPU 101 ends the fuel cut in step S220 and resumes normal processing. Then, the CPU 101 ends the series of processes for execution processing. When the CPU 101 ends the execution processing, the time measurement started in step S120 also ends. In regard to the process of step S210, when CPU 101 determines that the execution condition for fuel cut is no longer satisfied, the CPU 101 may determine the first requirement of the execution condition based on the accelerator operation amount ACC. That is, CPU 101 can determine that deceleration has ended when the accelerator operation amount ACC becomes greater than zero, that is, that vehicle 500 is not decelerating.

[0036] Now, if the duration from the start of fuel cut while the execution condition for fuel cut is satisfied becomes longer than the permissible time H (step S130: YES), CPU 101 advances the process to step S140. In this case, in step S140, CPU 101 interrupts the fuel cut. Then, CPU 101 resumes normal processing. That is, CPU 101 resumes fuel injection and combustion of the air-fuel mixture. CPU 101 causes internal combustion engine 10 to idle until vehicle 500 finishes deceleration. After interrupting the fuel cut, CPU 101 advances the process to step S150.

[0037] In step S150, CPU 101 updates the interruption count N. That is, CPU 101 adds "1" to the current interruption count N to calculate the new interruption count N. After this, CPU 101 ends the process of step S150. Then, CPU 101 ends the series of processes for the execution process. As above, when CPU 101 ends the execution process, it also ends the time measurement that began in step S120.

[0038] <Regarding the specified time and number of times> Among various permissible times H corresponding to the combinations of each filter temperature TF and each PM accumulation amount DA defined in the time map, the longest permissible time H is referred to as the maximum permissible time. The predetermined time P is set to a time longer than the maximum permissible time.

[0039] The predetermined time P is set in consideration of the following points. When the CPU 101 interrupts the fuel cut, fuel injection by each fuel injection valve 22 and therefore combustion of the mixture are resumed during the deceleration of the vehicle 500. When the combustion of the mixture is resumed, the deceleration of the vehicle 500 changes. Such a change in deceleration occurs as a result of the processing performed by the CPU 101 for protecting the filter 34, regardless of the accelerator operation of the occupant. Therefore, if the CPU 101 repeatedly interrupts the fuel cut in a relatively short time, the deceleration change is repeated during that time, regardless of the accelerator operation of the occupant, and the occupant may feel uncomfortable. The predetermined time P and the predetermined number of times NK are previously determined by experiment or simulation in association with each other so that the start of the fuel cut can be prohibited before the occupant feels uncomfortable.

[0040] Here, even if the fuel cut is interrupted several times within a reasonably long time scale, such as 10 minutes, the possibility that the occupant will feel uncomfortable is quite low because the frequency of fuel cut interruptions is low. Also, even if the fuel cut is interrupted within a fairly short time scale, such as 1 millisecond, the occupant will be unable to grasp the interruption of the fuel cut and thus the change in deceleration itself, so the possibility that the occupant will feel uncomfortable is quite low. The predetermined time P is set to a time scale that allows the occupant to grasp that a change in deceleration has occurred regardless of the occupant's accelerator operation, even if the fuel cut is interrupted several times. The predetermined number of times NK is set as a value that can prohibit the start of fuel cut before the occupant feels uncomfortable due to the change in deceleration within the predetermined time P determined on such a time scale.

[0041] <Operation of the embodiment> In the following description, it is assumed that the second requirement for the execution condition of a fuel cut is always satisfied while the vehicle 500 is decelerating.

[0042] As shown in (b) of FIG. 5, the vehicle 500 repeats acceleration and deceleration in response to the accelerator operation of the occupant. In FIG. 5, the period during which the vehicle 500 is decelerating is indicated by dots. Now, it is assumed that the prohibition flag is off at time T1 when the vehicle 500 starts decelerating. In this case, when the vehicle 500 starts decelerating at time T1, the CPU 101 starts fuel cut through the execution process (step S120) as shown in (c) of FIG. 5. After the start of the fuel cut, when the duration of the fuel cut becomes longer than the permissible time H at time T2 during the deceleration of the vehicle 500 (step S130: YES), the CPU 101 interrupts the fuel cut (step S140). When the vehicle 500 starts decelerating again at time T3, the CPU 101 starts the fuel cut. Then, when the duration of the fuel cut becomes longer than the permissible time H, the CPU 101 interrupts the fuel cut at time T4 during the deceleration of the vehicle 500. In the execution process, the CPU 101 successively counts the number of times N that the fuel cut has been interrupted (step S150).

[0043] Here, it is assumed that the number of temporary interruptions reaches a predetermined number NK at time T5 (step S350: YES) before the predetermined time P has elapsed since time T2 when the number of fuel cut interruptions N became "1" (step S340: NO). In this case, CPU 101 switches the prohibition flag to ON in the flag setting process (step S360). As a result, the third requirement in the execution conditions for fuel cut is no longer satisfied. Therefore, after time T5, CPU 101 does not perform the execution process and therefore does not perform fuel cut, even if vehicle 500 decelerates.

[0044] Here, between time T1 and time T5, the CPU 101 repeatedly performs fuel cut. When the CPU 101 performs fuel cut, oxygen is supplied to the filter 34, and PM accumulated on the filter 34 is burned. Accordingly, as shown in FIG. 5(a), the filter temperature TF gradually rises. Then, at the time of time T5, the filter temperature TF is considerably high. Now, as described above, the CPU 101 of this embodiment does not perform fuel cut after time T5. If the situation where the CPU 101 does not perform fuel cut continues, the filter temperature TF gradually drops. When the filter temperature TF falls to the judgment temperature TK or less (step S370: YES), the CPU 101 switches the prohibition flag to OFF (step S310). Then, when the vehicle 500 decelerates, the CPU 101 performs the execution process and thus the fuel cut again.

[0045] <Effects of the embodiment> (1) As described in the operation of the above embodiment, under the condition that fuel cut is repeated, the filter temperature TF gradually increases with the combustion of PM. Even if the permissible time H for continuing the fuel cut is set, if the condition that fuel cut is repeated continues, the filter 34 may eventually become overheated. Now, when the permissible time H for continuing the fuel cut is set, while it is advantageous for suppressing the overheating of the filter 34, an opportunity to interrupt the fuel cut may arise. If the fuel cut is repeatedly interrupted in a relatively short period of time, the degree of deceleration during deceleration of the vehicle 500 will repeatedly change without the occupant's intention. For this reason, if the fuel cut is repeatedly interrupted in a relatively short period of time, the occupant may feel uncomfortable.

[0046] Therefore, in this embodiment, the start of fuel cut is prohibited if the fuel cut is interrupted a predetermined number of times NK within the predetermined time P. This makes it possible to prevent the filter 34 from becoming overheated, and also to prevent repeated changes in the deceleration of the vehicle 500.

[0047] (2) In order to avoid an excessive rise in temperature of the filter 34, it is preferable to shorten the permissible time H for continuing the fuel cut when the filter temperature TF is high or the PM accumulation amount DA is large, as in the time map of this embodiment. On the other hand, if the permissible time H is short, there is a high possibility that the fuel cut will be interrupted and the deceleration rate will change.

[0048] In this regard, in this embodiment, the start of fuel cut is prohibited in a situation where the frequency of fuel cut interruptions increases as a result of setting a short permissible time H. With this configuration, it is possible to set an optimal permissible time H in accordance with the state of the filter 34, while preventing the occupants from feeling uncomfortable due to changes in the deceleration of the vehicle 500.

[0049] (3) As described above, the predetermined time P is set to a time scale that allows the occupant to recognize when the CPU 101 repeatedly interrupts the fuel cut. Setting the fuel cut based on such a time scale is preferable in terms of establishing control of the internal combustion engine 10 while fully considering the riding comfort of the occupant.

[0050] (4) The determination temperature TK for lifting the prohibition of fuel cut is a temperature at which PM combustion is possible in the filter 34 but at which the filter 34 is not damaged. Therefore, after the prohibition of fuel cut is lifted, the filter 34 can be regenerated for a certain amount of time.

[0051] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other to the extent that no technical contradiction occurs.

[0052] The judgment temperature TK is not limited to the example of the above embodiment. From the viewpoint of achieving both PM combustion in the filter 34 and prevention of damage to the filter 34, it is preferable that the judgment temperature TK is set within a range of 400 degrees or more and 600 degrees or less. However, it is not essential that the judgment temperature TK is set to a value within this range. The judgment temperature TK may be set as appropriate to a temperature appropriate for lifting the prohibition of fuel cut.

[0053] The predetermined time P is not limited to the example in the above embodiment. From the viewpoint of the time scale by which the occupant can recognize the interruption of the fuel cut, it is preferable that the predetermined time P is set within the range of 1 second or more and 20 seconds or less. However, it is not essential that the predetermined time P is set to a value within this range. The predetermined time P may be set as appropriate to a time scale appropriate for determining whether or not to prohibit the fuel cut. Note that the predetermined time P is set to a time longer than the permissible time H.

[0054] The predetermined number of times NK is not limited to the example in the above embodiment, but may be set as a value that can prohibit the start of fuel cut before the occupant feels uncomfortable. · Time maps are not limited to tables or graphs, but can also be mathematical expressions.

[0055] It is not essential to determine the prohibition of fuel cut based on the time elapsed since the number of interruptions N became "1" or the number of interruptions of fuel cut. The timing used to count the number of interruptions when determining the predetermined time P and the prohibition of fuel cut can be changed as appropriate. It is sufficient to be configured to prohibit fuel cut when the number of interruptions of fuel cut within the predetermined time P reaches the predetermined number NK.

[0056] The relationship between the permissible time H, the filter temperature TF, and the PM accumulation amount DA is not limited to the example of the above embodiment. The permissible time H is preferably set as follows. For the same filter temperature TF, when the PM accumulation amount DA is a first accumulation amount, the permissible time is shorter than when the PM accumulation amount DA is a second accumulation amount that is smaller than the first accumulation amount. Also, for the same PM accumulation amount DA, when the filter temperature TF is a first temperature, the permissible time H is shorter than when the filter temperature TK is a second temperature that is lower than the first temperature. However, the relationship is not limited to that described here, and the permissible time H may be set appropriately from the viewpoint of preventing damage to the filter 34. The permissible time H may be set regardless of the filter temperature TF and the PM accumulation amount DA. For example, the permissible time H may be a predetermined fixed value.

[0057] The method of calculating the PM accumulation amount DA is not limited to the example in the above embodiment. As long as the PM accumulation amount DA can be calculated appropriately, any method of calculating the PM accumulation amount DA can be used. The method of calculating the filter temperature TF is not limited to the example in the above embodiment. As long as the filter temperature TF can be calculated appropriately, any method of calculating the filter temperature TF may be used.

[0058] The overall configuration of the internal combustion engine 10 is not limited to the example of the above embodiment. For example, the fuel injection valve 22 may be of a type that injects fuel directly into the cylinder 12. [Explanation of symbols]

[0059] 10: internal combustion engine, 12: cylinder, 22: fuel injector, 34: filter, 100: control device, 500: vehicle

Claims

1. The present invention is applied to a vehicle equipped with an internal combustion engine having a fuel injection valve that injects fuel to be supplied into a cylinder, and a filter that collects particulate matter in exhaust gas discharged from the cylinder, performing a fuel cut to stop fuel injection by the fuel injection valve while the vehicle is decelerating; interrupting the fuel cut when a duration from the start of the fuel cut becomes longer than a predetermined allowable time; When the number of interruptions of the fuel cut reaches a predetermined number within a predetermined time period, the start of the fuel cut is prohibited until the temperature of the filter becomes equal to or lower than a predetermined judgment temperature; Run Vehicle control device.

2. When an accumulation amount of particulate matter accumulated on the filter is a first accumulation amount, the permissible time is set shorter than when the accumulation amount is a second accumulation amount that is smaller than the first accumulation amount, for the same temperature of the filter; For the same amount of deposition, when the temperature of the filter is a first temperature, the permissible time is set shorter than when the temperature of the filter is a second temperature lower than the first temperature. The vehicle control device according to claim 1 .

3. The predetermined time is set within a range of 1 second to 20 seconds. The vehicle control device according to claim 1 .

4. The judgment temperature is set within a range of 400 degrees or more and 600 degrees or less. The vehicle control device according to claim 1 .

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