Vehicle control devices

Abstract

The present invention relates to a method in which a CPU of a control device executes: a specific cylinder fuel cut-off process to stop the fuel supply to a part of a plurality of cylinders and continue the fuel supply to the remaining cylinders to operate an internal combustion engine; and a fastening force reduction process to reduce the fastening force of a lockup clutch of a torque converter. When the CPU executes the specific cylinder fuel cut-off process under a condition in which the internal combustion engine is operating under load, the specific cylinder fuel cut-off process is started in a state in which the fastening force is reduced by the fastening force reduction process.

Description

Technical Field

[0001] The present invention relates to a vehicle control device and is applied to a vehicle including an internal combustion engine having a plurality of cylinders and a torque converter having a lock-up clutch. Background Art

[0002] Japanese Patent Application Laid-Open No. 5-96978 describes an example of a vehicle control device that executes a specific cylinder fuel cut process for stopping fuel supply to only one cylinder among a plurality of cylinders when the operating state of the internal combustion engine is included in a specific deceleration operating region. Summary of the invention

[0003] In recent years, the development of a vehicle control device that performs a specific cylinder fuel cut-off process when the internal combustion engine is running under load has been promoted. During the execution of the specific cylinder fuel cut-off process, the internal combustion engine is operated in a state where the supply of fuel to a part of the cylinders among the plurality of cylinders is stopped and the supply of fuel to the remaining cylinders is continued. As a result, the output torque of the internal combustion engine vibrates. As a result, during the load operation, the amplitude of the vibration of the output torque of the internal combustion engine accompanying the execution of the specific cylinder fuel cut-off process is large, so the vehicle body may vibrate greatly.

[0004] A vehicle control device for solving the above-mentioned problem is applied to a vehicle having an internal combustion engine with multiple cylinders, a torque converter with a lockup clutch, and a transmission. The control device includes an execution device for executing a specific cylinder fuel cut-off process and a tightening force reduction process, wherein the specific cylinder fuel cut-off process is a process of stopping the fuel supply to a part of the multiple cylinders and continuing the fuel supply to the remaining cylinders to operate the internal combustion engine, and the tightening force reduction process is a process of reducing the tightening force of the lockup clutch. When the execution device executes the specific cylinder fuel cut-off process under a condition that the internal combustion engine is operating under load, the specific cylinder fuel cut-off process is started in a state where the tightening force is reduced by the tightening force reduction process.

[0005] According to the above structure, when the specific cylinder fuel cut-off process is executed when the internal combustion engine is running under load, the tightening force reduction process is executed before the execution of the specific cylinder fuel cut-off process. If the tightening force reduction process is executed, the tightening force of the lockup clutch is reduced. As a result, the efficiency of torque transmission from the internal combustion engine to the transmission device becomes lower than before the tightening force is reduced. As a result, even if the output torque of the internal combustion engine vibrates due to the execution of the specific cylinder fuel cut-off process, the vibration is transmitted to the transmission device side in an attenuated manner. Thus, when the specific cylinder fuel cut-off process is executed when the internal combustion engine is running under load, the body vibration of the vehicle can be suppressed.

[0006] In one aspect of the vehicle control device, the execution device executes the specific cylinder fuel cut process when the operating state of the internal combustion engine is included in a predetermined permitted operating region in a state where the tightening force is reduced by the tightening force reducing process.

[0007] According to the above configuration, if the operating state of the internal combustion engine is included in the permitted operation region in a state where the fastening force of the lockup clutch is reduced by the fastening force reducing process, the specific cylinder fuel cut process is executed.

[0008] In one embodiment of the control device for the vehicle, in the permitted operation region, a region where the internal combustion engine speed is high and the internal combustion engine load factor is low is set as a specific region. In this case, under the condition that the reduction of the clamping force of the lockup clutch is prohibited, the execution device starts the specific cylinder fuel cut-off process without executing the clamping force reduction process, on the condition that the operation state of the internal combustion engine is included in the specific region.

[0009] Even when the internal combustion engine is running under load, when the internal combustion engine speed is relatively high and the internal combustion engine load factor is low, even if the output torque of the internal combustion engine vibrates, the vehicle body is not likely to vibrate. In this regard, according to the above-mentioned structure, when it is prohibited to reduce the tightening force of the lockup clutch, if the operating state of the internal combustion engine is included in the specific area, the specific cylinder fuel cut-off process can be executed. Therefore, the vibration of the vehicle body accompanying the execution of the specific cylinder fuel cut-off process can be suppressed, and the execution opportunity of the specific cylinder fuel cut-off process can be increased.

[0010] In the above configuration, when the operating state of the internal combustion engine is not included in the specific region under the condition where the reduction of the fastening force of the lock-up clutch is prohibited, the specific cylinder fuel cut process is not executed.

[0011] In one embodiment of the control device of the vehicle, when the tightening force reduction process is set as the first tightening force reduction process, the execution device can also execute the second tightening force reduction process that reduces the tightening force but makes the reduction amount of the tightening force smaller than when the first tightening force reduction process is executed. In addition, in the allowable operation area, the area where the internal combustion engine speed is high and the internal combustion engine load factor is low is set as a specific area. In this case, when the operating state of the internal combustion engine is not included in the specific area, the execution device executes the specific cylinder fuel cut-off process when the operating state of the internal combustion engine is included in the allowable operation area in the state where the tightening force is reduced by the first tightening force reduction process. In addition, when the operating state of the internal combustion engine is included in the specific area, the execution device starts the specific cylinder fuel cut-off process in the state where the tightening force is reduced by the second tightening force reduction process.

[0012] Even when the internal combustion engine is running under load, when the internal combustion engine speed is relatively high and the internal combustion engine load rate is low, even if the output torque of the internal combustion engine vibrates, the vehicle body is not likely to vibrate. Therefore, in the above-mentioned structure, when the operating state of the internal combustion engine is included in the specific area, the second tightening force reduction process is executed instead of the first tightening force reduction process. The specific cylinder fuel cut-off process is executed in a state where the tightening force of the lockup clutch is reduced by the second tightening force reduction process. That is, it is possible to suppress the decrease in the efficiency of transmitting the output torque of the internal combustion engine to the wheels, and suppress the vibration of the vehicle body accompanied by the execution of the specific cylinder fuel cut-off process.

[0013] In one embodiment of the control device of the above-mentioned vehicle, when the operating state of the internal combustion engine is not included in the permitted operating area even if the tightening force is reduced by the tightening force reduction processing, the execution device controls at least one of the internal combustion engine and the transmission device in order to make the operating state of the internal combustion engine included in the permitted operating area, and starts the specific cylinder fuel cut-off processing if the operating state of the internal combustion engine is included in the permitted operating area.

[0014] If the operating state of the internal combustion engine is not included in the permitted operating region even if the locking force of the lockup clutch is reduced by the locking force reduction process, the specific cylinder fuel cut-off process cannot be executed. Therefore, in the above-mentioned structure, in the case where the operating state of the internal combustion engine is not included in the permitted operating region even if the locking force of the lockup clutch is reduced by the locking force reduction process, at least one of the internal combustion engine and the transmission device is controlled in such a way that the operating state of the internal combustion engine is included in the permitted operating region. When the operating state of the internal combustion engine is included in the permitted operating region by such control, the specific cylinder fuel cut-off process is executed. Therefore, the execution opportunity of the specific cylinder fuel cut-off process can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Features, advantages and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like numerals represent like elements, and in which:

[0016] Figure 1 This is a schematic configuration diagram showing a vehicle to which the vehicle control device according to the first embodiment is applied.

[0017] Figure 2 It is a diagram showing the permitted operation area and the specific area.

[0018] Figure 3 This is a flowchart illustrating the flow of a series of processes executed by the CPU of the vehicle control device in the first embodiment.

[0019] Figure 4This is a time chart of a case where a specific cylinder fuel cut process is executed during load operation of the internal combustion engine.

[0020] Figure 5 This is a flowchart illustrating the flow of a series of processes executed by the CPU of the vehicle control device in the second embodiment. DETAILED DESCRIPTION

[0021] (First Embodiment)

[0022] Below, according to Figure 1 to Figure 4 A first embodiment of a vehicle control device will be described.

[0023] <Overall Structure>

[0024] exist Figure 1 2 shows a vehicle 100 to which the control device 60 of the present embodiment is applied. The vehicle 100 includes an internal combustion engine 10, a torque converter 40, and a transmission 50. The torque output from the internal combustion engine 10 is input to the transmission 50 via the torque converter 40. The torque output from the transmission 50 is input to the drive wheels 101.

[0025] <Structure of Internal Combustion Engine 10>

[0026] The internal combustion engine 10 has a plurality of cylinders 11. Figure 1 In the example shown, the number of cylinders in the internal combustion engine 10 is 4. Hereinafter, the cylinders 11 of the internal combustion engine 10 are indicated by cylinder numbers such as first cylinder #1, second cylinder #2, third cylinder #3, and fourth cylinder #4 in the order of their arrangement.

[0027] A piston is housed in each cylinder 11. The piston can reciprocate in each cylinder 11. The piston in each cylinder 11 is connected to a crankshaft 14 via a connecting rod. The crankshaft 14 rotates according to the reciprocating motion of the piston in each cylinder 11.

[0028] The internal combustion engine 10 includes a water jacket 19. The water jacket 19 is a passage through which cooling water for cooling the internal combustion engine 10 flows.

[0029] The internal combustion engine 10 has the same number of spark plugs 16 as the number of cylinders. That is, a spark plug 16 is provided for each cylinder 11. In the cylinder 11, each spark plug 16 ignites the mixture containing intake air and fuel based on spark discharge. In one combustion cycle of the internal combustion engine 10, the mixture is ignited in the order of the first cylinder #1, the third cylinder #3, the fourth cylinder #4, and the second cylinder #2.

[0030] The internal combustion engine 10 includes an intake passage 15 for introducing intake air to each cylinder 11 and a plurality of fuel injection valves 17. The intake passage 15 is connected to each cylinder 11. A fuel injection valve 17 is provided for each cylinder 11. Fuel injected from the fuel injection valve 17 is supplied into the cylinder 11.

[0031] The internal combustion engine 10 has an exhaust passage 21 through which the exhaust gas discharged from each cylinder 11 flows. The exhaust passage 21 is connected to each cylinder 11. A three-way catalyst 22 is provided in the exhaust passage 21. The three-way catalyst 22 has an oxygen storage capacity. Therefore, the three-way catalyst 22 can purify the exhaust gas. A gasoline particulate filter 23 is arranged downstream of the three-way catalyst 22 in the exhaust passage 21. The gasoline particulate filter 23 collects particulate matter contained in the exhaust gas. Hereinafter, the gasoline particulate filter will be referred to as "GPF". The particulate matter will be referred to as "PM".

[0032] The internal combustion engine 10 has a plurality of types of sensors. Examples of the sensors include a crank angle sensor 31, a water temperature sensor 32, and an air flow meter 33. The crank angle sensor 31 outputs a signal corresponding to the rotation speed of the crankshaft 14, i.e., the internal combustion engine rotation speed NE, as a detection signal to the control device 60. The water temperature sensor 32 detects the temperature of the cooling water circulating in the water jacket 19, i.e., the cooling water temperature THW, and outputs a detection signal corresponding to the detection result to the control device 60. The air flow meter 33 detects the flow rate of the intake air flowing in the intake passage 15, i.e., the intake air amount GA, and outputs a detection signal corresponding to the detection result to the control device 60.

[0033] <Structure of Torque Converter 40 and Speed ​​Shift Device 50>

[0034] The torque converter 40 includes a pump impeller 41 connected to the crankshaft 14 and a turbine impeller 42 connected to the input shaft 51 of the transmission 50. In the torque converter 40, torque is transmitted between the pump impeller 41 and the turbine impeller 42 via a fluid.

[0035] The torque converter 40 has a lockup clutch 43. In the torque converter 40, the operating state of the lockup clutch 43 can be set to a fastened state in which the pump impeller 41 and the turbine impeller 42 are directly connected, or to a released state in which the fastened state is completely released. The operating state of the lockup clutch 43 can be changed by supplying and discharging fluid into the torque converter 40. And, when the operating state of the lockup clutch 43 is the fastened state, the output torque of the internal combustion engine 10 is transmitted to the speed change device 50 via the lockup clutch 43. On the other hand, when the operating state of the lockup clutch 43 is the released state, the output torque of the internal combustion engine 10 is transmitted to the speed change device 50 via the fluid in the torque converter 40.

[0036] It should be noted that, in the present embodiment, even if the working state of the lockup clutch 43 is the tightening state, the tightening force FF can be made variable. In this case, the smaller the tightening force FF is, the lower the torque transmission efficiency of the lockup clutch 43 is. Such adjustment of the tightening force FF can be achieved by controlling the supply and discharge of fluid into the torque converter 40.

[0037] The transmission 50 includes an input shaft 51 to which torque is input from the torque converter 40 and an output shaft 52 to which torque is output. The transmission 50 can adjust a speed ratio under the control of the control device 60 .

[0038] The transmission 50 includes a fluid temperature sensor 55 for detecting a fluid temperature THF which is the temperature of the fluid circulating in the transmission 50 and the torque converter 40. The fluid temperature sensor 55 outputs a detection signal corresponding to the detected fluid temperature THF to the control device 60.

[0039] <Structure of the control device 60>

[0040] The control device 60 sets the internal combustion engine 10 as a control object. That is, the control device 60 operates various operating parts of the internal combustion engine 10, such as each fuel injection valve 17 and each spark plug 16, in order to operate the internal combustion engine 10. The control device 60 refers to the intake air amount GA, the internal combustion engine speed NE, the internal combustion engine load factor KL, the cooling water temperature THW, etc. in order to control the control amount of each operating part of the internal combustion engine 10. The internal combustion engine load factor KL is a parameter that determines the amount of air filled into the combustion chamber in the cylinder 11. The internal combustion engine load factor KL is, for example, a ratio of the inflow air amount per combustion cycle of one cylinder to a reference inflow air amount. The reference inflow air amount can be variably set according to the internal combustion engine speed NE.

[0041] The control device 60 controls the torque converter 40 and the transmission 50. That is, the control device 60 controls the operating state of the lockup clutch 43. For example, when the operating state is the tightening state, the control device 60 sometimes adjusts the tightening force FF of the lockup clutch 43. The control device 60 controls the speed ratio of the transmission 50 based on the moving speed of the vehicle 100, that is, the vehicle speed SP, etc.

[0042] The control device 60 includes a CPU 61, a ROM 62, and a peripheral circuit 63. In the control device 60, the CPU 61, the ROM 62, and the peripheral circuit 63 can communicate through a communication line 64. The peripheral circuit 63 includes a circuit for generating a clock signal that specifies the internal operation, a power supply circuit, a reset circuit, etc. The control device 60 controls the above-mentioned control amount by the CPU 61 executing the program stored in the ROM 62. In the present embodiment, the CPU 61 corresponds to an "executing device" that executes the specific cylinder fuel cut-off process and the tightening force reduction process described later.

[0043] <Regarding the Specific Cylinder Fuel Cutoff Process>

[0044] The CPU 61 of the control device 60 performs a specific cylinder fuel cut-off process when the internal combustion engine 10 is operated under load. In the specific cylinder fuel cut-off process, the CPU 61 stops the fuel supply to a part of the cylinders 11 among the multiple cylinders 11, and continues the fuel supply to the remaining cylinders 11 to operate the internal combustion engine 10. The cylinder 11 to which the fuel supply is stopped is set as a "stop cylinder", and the cylinder 11 to which the fuel supply is continued is called a "continue cylinder". At this time, in the specific cylinder fuel cut-off process, the CPU 61 stops the fuel injection of the fuel injection valve 17 corresponding to the stop cylinder, and continues the fuel injection of the fuel injection valve 17 corresponding to the continue cylinder. For example, the CPU 61 increases the fuel injection amount of the fuel injection valve 17 corresponding to the continue cylinder in such a way that the air-fuel ratio of the mixture in the continue cylinder is richer than the theoretical air-fuel ratio.

[0045] It should be noted that the CPU 61 executes the specific cylinder fuel cut process during the load operation of the internal combustion engine 10 for the purpose of supplying oxygen to the three-way catalyst 22 and the GPF 23 .

[0046] When the specific cylinder fuel cut process is being executed, the fuel supply to the stopping cylinder is stopped and the fuel supply to the continuing cylinder is continued, so the output torque of the internal combustion engine 10 vibrates. Therefore, if the specific cylinder fuel cut process is executed when the internal combustion engine 10 is under load operation, the amplitude of the vibration of the output torque of the internal combustion engine 10 is large, so the body of the vehicle 100 may vibrate greatly.

[0047] Therefore, conventionally, when the internal combustion engine 10 is operated under load, the operating state of the internal combustion engine 10 includes Figure 2 When the engine is in a specific region AR11 indicated by a dotted line, the specific cylinder fuel cut process is executed. The specific region AR11 is an operation region of the internal combustion engine 10 where the engine speed NE is high and the engine load factor KL is low.

[0048] On the other hand, in the present embodiment, the control device 60 controls the torque converter 40 for the purpose of increasing the chances of executing the specific cylinder fuel cut process.

[0049] <Regarding a Series of Processing Executed by the CPU 61 of the Control Device 60>

[0050] Reference Figure 2 and Figure 3 , a flow of a series of processes executed by the CPU 61 to execute the specific cylinder fuel cut process when the internal combustion engine 10 is in load operation will be described. Figure 3 The series of processing shown is realized by the CPU 61 executing a program stored in the ROM 62 .

[0051] In a series of processes, in the initial step S11, CPU61 determines whether there is an execution request for a specific cylinder fuel cut-off process. When it is necessary to supply oxygen to the three-way catalyst 22 and GPF23, it can be regarded as an execution request. On the other hand, when it is not necessary to supply oxygen to the three-way catalyst 22 and GPF23, it is not regarded as an execution request. For example, when the accumulation amount of PM in GPF23 is above a threshold value, it is necessary to supply oxygen to GPF23 for the purpose of heating GPF23 or burning PM in GPF23. And, when there is no execution request (S11: No), CPU61 temporarily ends a series of processes. On the other hand, when there is an execution request (S11: Yes), CPU61 moves the process to step S13.

[0052] In step S13, the CPU 61 determines whether the reduction of the fastening force FF of the lockup clutch 43 is prohibited. In the present embodiment, when the operating state of the lockup clutch 43 is changed, the supply and discharge of the fluid into the torque converter 40 are adjusted. At this time, if the temperature of the fluid is too high, the change of the operating state of the lockup clutch 43 is prohibited. For example, when the fluid temperature THF is above the fluid temperature judgment value, it can be regarded that the fluid temperature THF is too high for reducing the fastening force FF. Therefore, when the fluid temperature THF is above the fluid temperature judgment value, it can be determined that the reduction of the fastening force FF is prohibited. On the other hand, when the fluid temperature THF is lower than the fluid temperature judgment value, it is not determined that the reduction of the fastening force FF is prohibited.

[0053] If the determination that the reduction of the fastening force FF is prohibited is not made in step S13 (No), the CPU 61 moves the processing to step S15. In step S15, the CPU 61 performs a fastening force reduction process to reduce the fastening force FF. For example, in the fastening force reduction process, the CPU 61 makes the operating state of the lockup clutch 43 a released state. In this case, it can be said that the CPU 61 reduces the fastening force FF until the fastening force FF becomes "0".

[0054] After the tightening force FF is reduced by the tightening force reduction process, the CPU 61 moves the process to step S17. In step S17, the CPU 61 determines whether the operating state of the internal combustion engine 10 is included in the permitted operating area AR1. When the operating state of the internal combustion engine 10 is not included in the permitted operating area AR1 (S17: No), the CPU 61 repeatedly executes the determination of step S17 until the operating state is included in the permitted operating area AR1. On the other hand, when the operating state is included in the permitted operating area AR1 (S17: Yes), the CPU 61 moves the process to step S21.

[0055] Here, refer to Figure 2, the permitted operation area AR1 is described. Figure 2 As shown by the hollow arrow in FIG. 1 , the permitted operating region AR1 is a region obtained by expanding the specific region AR11 toward the side where the internal combustion engine speed NE is low and the internal combustion engine load factor KL is large. In the present embodiment, the permitted operating region AR1 includes the specific region AR11. Specifically, in the permitted operating region AR1, a region where the internal combustion engine speed NE is high and the internal combustion engine load factor KL is small is the specific region AR11.

[0056] When the specific cylinder fuel cut process is being executed, the output torque of the internal combustion engine 10 vibrates, so the vehicle body may vibrate. In the present embodiment, an operating region in which the amplitude of the vibration of the vehicle body generated when the specific cylinder fuel cut process is executed in a state where the fastening force FF of the lockup clutch 43 is reduced by the fastening force reduction process is suppressed to an allowable range is set as the allowable operating region AR1. Figure 2 In the graph shown, when the point indicating the engine speed NE and the engine load factor KL at the current time point is within the permitted operation region AR1 , it can be determined that the operation state of the internal combustion engine 10 is included in the permitted operation region AR1 .

[0057] return Figure 3 In step S13, if it is determined that the reduction of the fastening force FF is prohibited (Yes), the CPU 61 moves the processing to step S19. In step S19, the CPU 61 determines whether the operating state of the internal combustion engine 10 is included in the specific area AR11. If the operating state of the internal combustion engine 10 is not included in the specific area AR11 (S19: No), the CPU 61 moves the processing to step S13. On the other hand, if the operating state is included in the specific area AR11 (S19: Yes), the CPU 61 moves the processing to step S21.

[0058] In step S21, the CPU 61 starts the specific cylinder fuel cut process and then ends the series of processes.

[0059] For example, if it is determined that a sufficient amount of oxygen is successfully supplied to the three-way catalyst 22 and the GPF 23, the CPU 61 determines that the predetermined termination condition is met and terminates the specific cylinder fuel cut process.

[0060] <Functions and Effects of the Present Embodiment>

[0061] exist Figure 4In the example shown, at timing t11 during the load operation of the internal combustion engine 10, the execution of the specific cylinder fuel cut-off process is requested. Then, by executing the tightening force reduction process, the operating state of the lockup clutch 43 is changed from the tightening state to the released state. That is, the tightening force FF of the lockup clutch 43 is reduced. As a result, although the accelerator opening AC is maintained, the internal combustion engine speed NE increases. This is because: by changing the operating state of the lockup clutch 43 to the released state, the load acting on the internal combustion engine 10 is reduced.

[0062] It should be noted that in Figure 4 In the example shown, at timing t11, the operating state of the internal combustion engine 10 is not included in the permitted operating region AR1. Furthermore, even if the tightening force FF is reduced by the tightening force reduction process, the operating state of the internal combustion engine 10 is not included in the permitted operating region AR1. Therefore, at timing t12 when the tightening force FF is reduced by the tightening force reduction process, the specific cylinder fuel cut process is not started.

[0063] In addition, if the lockup clutch 43 is in the released state, the torque transmission efficiency of the torque converter 40 decreases. Therefore, the drive torque TQd input to the drive wheel 101 decreases. As a result, the vehicle speed SP decreases. Figure 4 In the example shown, the accelerator opening AC is increased by the driver of the vehicle 100. As the accelerator opening AC is increased, the engine speed NE increases. Then, when the vehicle speed SP rises to the value before the tightening force reduction process is started, the driver maintains the accelerator opening AC as shown at timing t13.

[0064] exist Figure 4 In the example shown, it is determined at the subsequent timing t14 that the operating state of the internal combustion engine 10 is included in the permitted operating area AR1. Therefore, the specific cylinder fuel cut-off process is started. That is, the internal combustion engine operation is started in which the fuel supply to a part of the cylinders 11 among the multiple cylinders 11 is stopped and the fuel supply to the remaining cylinders 11 is continued. As a result, the output torque of the internal combustion engine 10 vibrates. In this case, the internal combustion engine speed NE also vibrates with a period corresponding to the vibration of the output torque. As a result, the drive torque TQd input to the drive wheel 101 vibrates, and therefore the vehicle body also vibrates.

[0065] exist Figure 4 In FIG. 1 , the vibration of the driving torque TQd and the vehicle body vibration in the present embodiment are shown by solid lines. On the other hand, the vibration of the driving torque TQd and the vehicle body vibration in the comparative example are shown by dotted lines. The comparative example is a case where the specific cylinder fuel cut-off process is executed without executing the tightening force reduction process.

[0066] By reducing the fastening force FF of the lockup clutch 43 by utilizing the fastening force reduction process, the torque transmission efficiency of the torque converter 40 is reduced. In the present embodiment, the specific cylinder fuel cut-off process is performed in a state where the fastening force FF is reduced. Therefore, even if the output torque of the internal combustion engine 10 vibrates due to the execution of the specific cylinder fuel cut-off process, the vibration is transmitted to the transmission 50 in an attenuated manner. As a result, the amplitude of the vibration of the driving torque TQd input to the drive wheel 101 becomes smaller. Thus, when the specific cylinder fuel cut-off process is performed while the internal combustion engine 10 is operating under load, the body vibration of the vehicle 100 can be suppressed compared to the case of the comparative example.

[0067] It should be noted that, before the execution of the tightening force reduction process, even if the operating state of the internal combustion engine 10 is outside the permitted operating region AR1, if the tightening force FF is reduced by the tightening force reduction process, the internal combustion engine speed NE and the internal combustion engine load factor KL change, and the operating state may be included in the permitted operating region AR1. In this case, even if the accelerator opening AC is not increased after the execution of the tightening force reduction process, the specific cylinder fuel cut process is executed.

[0068] In addition, even if the operating state of the internal combustion engine 10 is included in the permissible operating region AR1 before the execution of the tightening force reduction process, the tightening force FF is reduced by the tightening force reduction process. Furthermore, even if the engine speed NE and the engine load factor KL change, if the operating state is included in the permissible operating region AR1, the specific cylinder fuel cut process is executed.

[0069] In this embodiment, the following effects can be further obtained.

[0070] (1-1) In the present embodiment, the lockup clutch 43 is operated in a released state by the tightening force reduction process. Therefore, compared with the case where the tightening force FF is reduced but the operating state is not changed to the released state, the vibration of the output torque of the internal combustion engine 10 is further damped and transmitted to the drive wheel 101. Therefore, the effect of suppressing the vibration of the vehicle body can be improved.

[0071] (1-2) If the fluid temperature THF becomes high while the lockup clutch 43 is in the locked state, the locking force FF may be prohibited from being reduced. In such a case, even if the specific cylinder fuel cut process is requested, the locking force reduction process cannot be executed.

[0072] In this regard, in the present embodiment, when the execution of the specific cylinder fuel cut process is requested under the condition that the reduction of the fastening force FF is prohibited, the specific cylinder fuel cut process is executed on the condition that the operating state of the internal combustion engine 10 is included in the specific area AR11. Therefore, the vibration of the vehicle body associated with the execution of the specific cylinder fuel cut process can be suppressed, and the execution opportunity of the specific cylinder fuel cut process can be increased.

[0073] (1-3) The specific area AR11 can be said to be a permitted operating area in the past when the tightening force reduction process was not executed before the execution of the specific cylinder fuel cut process. In this embodiment, since the tightening force reduction process is executed before the execution of the specific cylinder fuel cut process, the permitted operating area can be expanded compared with the past. As a result, the execution opportunity of the specific cylinder fuel cut process can be increased during the load operation of the internal combustion engine 10.

[0074] (Second Embodiment)

[0075] according to Figure 5 In the following description, the parts different from the first embodiment are mainly described, and the same reference numerals are given to the same or corresponding components as those in the first embodiment, and duplicate description is omitted.

[0076] Reference Figure 5 , a flow of a series of processes executed by the CPU 61 to execute the specific cylinder fuel cut process when the internal combustion engine 10 is in load operation will be described. Figure 5 The series of processing shown is realized by the CPU 61 executing a program stored in the ROM 62 .

[0077] In a series of processes, in the first step S31, the CPU 61 determines whether there is an execution request for the specific cylinder fuel cut process in the same manner as in the above step S11. If there is no execution request (S31: No), the CPU 61 temporarily ends the series of processes. On the other hand, if there is an execution request (S31: Yes), the CPU 61 moves the process to step S33.

[0078] In step S33, the CPU 61 determines whether the operating state of the internal combustion engine 10 is included in the specific area AR11. When the operating state of the internal combustion engine 10 is not included in the specific area AR11 (S33: No), the CPU 61 moves the processing to step S35. In step S35, the CPU 61 performs a first tightening force reduction process. The first tightening force reduction process is a process for reducing the tightening force FF of the lockup clutch 43. In the present embodiment, the CPU 61 reduces the tightening force FF until the operating state of the lockup clutch 43 becomes a released state in the first tightening force reduction process.

[0079] After the tightening force FF is reduced by the first tightening force reduction process, the CPU 61 moves the process to step S37. In step S37, the CPU 61 determines whether the operating state of the internal combustion engine 10 is included in the permitted operating area AR1. If the operating state is included in the permitted operating area AR1 (S37: Yes), the CPU 61 moves the process to step S43. On the other hand, if the operating state is not included in the permitted operating area AR1 (S37: No), the CPU 61 moves the process to step S39.

[0080] In step S39, the CPU 61 performs a forced process for controlling at least one of the internal combustion engine 10 and the transmission 50 so that the operating state of the internal combustion engine 10 is included in the permitted operating region AR1. The CPU 61 preferably adjusts the output torque of the internal combustion engine 10 and the gear ratio of the transmission 50 in a manner that minimizes the change in the vehicle speed SP caused by the execution of the forced process. If the operating state of the internal combustion engine 10 is included in the permitted operating region AR1 by the forced process, the CPU 61 moves the process to step S43.

[0081] On the other hand, when the operating state of the internal combustion engine 10 is included in the specific area AR11 in step S33 (yes), the CPU 61 moves the processing to step S41. In step S41, the CPU 61 performs a second tightening force reduction process. That is, in addition to the first tightening force reduction process, the CPU 61 can also perform a second tightening force reduction process. The second tightening force reduction process is a process for reducing the tightening force of the lockup clutch 43. In detail, the second tightening force reduction process is a process that reduces the tightening force FF but makes the reduction amount of the tightening force FF smaller than when the first tightening force reduction process is executed. In this embodiment, even if the second tightening force reduction process is executed, the working state of the lockup clutch 43 does not become a released state. After the tightening force FF is reduced by the second tightening force reduction process, the CPU 61 moves the processing to step S43.

[0082] In step S43, the CPU 61 starts the specific cylinder fuel cut process. Then, the CPU 61 ends a series of processes.

[0083] <Functions and Effects of the Present Embodiment>

[0084] In this embodiment, the following effects can be obtained.

[0085] (2-1) When the operating state of the internal combustion engine 10 is included in the specific area AR11, the second tightening force reduction process is executed instead of the first tightening force reduction process. In this case, the tightening force FF is greater than the case where the first tightening force reduction process is executed. The specific cylinder fuel cut-off process is executed in this state. That is, the specific cylinder fuel cut-off process is executed in a state where the torque transmission efficiency of the torque converter 40 is high compared to the case where the first tightening force reduction process is executed. As a result, it is possible to suppress the decrease in the efficiency of transmitting the output torque of the internal combustion engine 10 to the drive wheel 101, and suppress the vibration of the vehicle body associated with the execution of the specific cylinder fuel cut-off process.

[0086] (2-2) In the present embodiment, when the operating state of the internal combustion engine 10 is not included in the specific area AR11, the first tightening force reduction process is executed. Even if the tightening force FF of the lockup clutch 43 is reduced by the first tightening force reduction process, when the operating state is not included in the permitted operating area AR1, the forced process is executed. Thus, the output torque of the internal combustion engine 10 and the gear ratio of the transmission 50 are changed in such a way that the operating state is included in the permitted operating area AR1. If the operating state is included in the permitted operating area AR1 by the forced process, the specific cylinder fuel cut-off process is executed. Therefore, the execution opportunity of the specific cylinder fuel cut-off process can be increased.

[0087] (Change Example)

[0088] The above-mentioned embodiments can be implemented by modification as follows. The above-mentioned embodiments and the following modification examples can be implemented by combining with each other within the range that there is no technical contradiction.

[0089] In the second embodiment, when reducing the tightening force FF is prohibited, the specific cylinder fuel cut process may be executed without executing either the first tightening force reducing process or the second tightening force reducing process, provided that the operating state of the internal combustion engine 10 is included in the specific area AR11.

[0090] In the first embodiment described above, when the reduction of the fastening force FF is prohibited, execution of the specific cylinder fuel cut process may be prohibited regardless of the operating state of the internal combustion engine 10 .

[0091] In the first embodiment described above, the fastening force reducing process only needs to reduce the fastening force FF, and may be a process that does not change the operating state of the lockup clutch 43 to the released state.

[0092] In the second embodiment, the first tightening force reduction process only needs to reduce the tightening force FF, and may be a process that does not change the operating state of the lockup clutch 43 to the released state. However, the reduction amount of the tightening force FF caused by the execution of the first tightening force reduction process is greater than the reduction amount of the tightening force FF caused by the execution of the second tightening force reduction process.

[0093] In the first embodiment, even if the tightening force FF is reduced by the tightening force reduction process, when the operating state of the internal combustion engine 10 is not included in the permitted operating area AR1, a process of urging the driver to increase the internal combustion engine speed NE by the driver's vehicle operation may be performed. Examples of vehicle operations that can increase the internal combustion engine speed NE include increasing the accelerator opening AC and changing the speed ratio of the transmission 50 to the low speed side.

[0094] In the second embodiment, even if the fastening force FF is reduced by the first fastening force reduction process, if the operating state of the internal combustion engine 10 is not included in the permitted operating area AR1, the forced process may not be executed. In this case, instead of the forced process, a process of urging the driver to increase the internal combustion engine speed NE through the driver's vehicle operation may be executed. Examples of vehicle operations that can increase the internal combustion engine speed NE include increasing the accelerator opening AC and changing the speed ratio of the transmission 50 to the low speed side.

[0095] In the second embodiment, both the internal combustion engine 10 and the transmission 50 are controlled in the forced process, but the present invention is not limited thereto. In the forced process, the output torque of the internal combustion engine 10 may be made variable, and the speed ratio of the transmission 50 may not be changed. Conversely, in the forced process, the speed ratio of the transmission 50 may be made variable, and the output torque of the internal combustion engine 10 may not be changed.

[0096] The control device 60 is not limited to the one including the CPU 61 and the ROM 62 and executing software processing. That is, the control device 60 may be any one of the following structures (a) to (c).

[0097] (a) The control device 60 has one or more processors that execute various processes according to a computer program. The processor includes a CPU and a memory such as a RAM and a ROM. The memory stores a program code or instruction configured to cause the CPU to execute a process. The memory, i.e., a computer-readable medium, includes all available media that can be accessed by a general-purpose or special-purpose computer.

[0098] (b) The control device 60 has one or more dedicated hardware circuits for executing various processes. As dedicated hardware circuits, for example, ASIC or FPGA can be cited. It should be noted that ASIC is the abbreviation of "Application Specific Integrated Circuit" and FPGA is the abbreviation of "Field Programmable Gate Array".

[0099] (c) The control device 60 includes a processor that executes part of various processes in accordance with a computer program and a dedicated hardware circuit that executes the remaining processes among the various processes.

[0100] The internal combustion engine may be any internal combustion engine as long as the number of cylinders is two or more, and may be an internal combustion engine different from the internal combustion engine 10 .

[0101] The vehicle to which the control device 60 is applied may be any vehicle provided with the internal combustion engine 10 and the torque converter 40, and may have a configuration different from that of the vehicle 100. For example, the control device 60 may be applied to a hybrid vehicle provided with an electric motor in addition to the internal combustion engine 10 as a power source of the vehicle.

Claims

1. A vehicle control device, Applicable to vehicles equipped with an internal combustion engine having multiple cylinders, a torque converter having a lock-up clutch, and a transmission device. an execution device for executing a specific cylinder fuel cut-off process and a tightening force reduction process, wherein the specific cylinder fuel cut-off process is a process for stopping the fuel supply to a part of the plurality of cylinders and continuing the fuel supply to the remaining cylinders to operate the internal combustion engine, and the tightening force reduction process is a process for reducing the tightening force of the lockup clutch, When the execution device executes the specific cylinder fuel cut process in a state where the internal combustion engine is operating under load, the execution device starts the specific cylinder fuel cut process in a state where the fastening force is reduced by the fastening force reducing process.

2. The vehicle control device according to claim 1, The execution device executes the specific cylinder fuel cut process when the operating state of the internal combustion engine is included in a predetermined permitted operating region in a state where the tightening force is reduced by the tightening force reducing process.

3. The vehicle control device according to claim 2, In the permitted operation region, a region where the engine speed is high and the engine load factor is low is set as a specific region. In a situation where reduction of the locking force of the lockup clutch is prohibited, the actuator starts the specific cylinder fuel cut process without executing the locking force reduction process, on the condition that the operating state of the internal combustion engine is included in the specific region.

4. The vehicle control device according to claim 2, When the tightening force reduction process is set as a first tightening force reduction process, the execution device can also execute a second tightening force reduction process in which the tightening force is reduced but the amount of reduction in the tightening force is smaller than that when the first tightening force reduction process is executed. In the permitted operation region, a region where the engine speed is high and the engine load factor is low is set as a specific region. The execution device, when the operating state of the internal combustion engine is not included in the specific area, executes the specific cylinder fuel cut-off process when the operating state of the internal combustion engine is included in the allowable operating area in the state where the tightening force is reduced by the first tightening force reduction process, When the operating state of the internal combustion engine is included in the specific region, the specific cylinder fuel cut process is started in a state where the tightening force is reduced by the second tightening force reducing process.

5. The vehicle control device according to any one of claims 2 to 4, When the operating state of the internal combustion engine is not included in the permitted operating region even if the tightening force is reduced by the tightening force reducing process, the actuator controlling at least one of the internal combustion engine and the transmission device so that the operating state of the internal combustion engine is included in the permitted operation region; If the operating state of the internal combustion engine is included in the permitted operation region, the specific cylinder fuel cut process is started.

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