control device

Abstract

In internal combustion engines, retarding the ignition timing increases the exhaust gas temperature, which can easily lead to overheating of exhaust system components. [Solution] A control device for an internal combustion engine comprising an ignition device, a modification device for changing the opening timing of an exhaust valve, an exhaust system member provided in the exhaust passage, and an injection device for injecting fuel and supplying fuel to the internal combustion engine, wherein the control device performs the following processes: when it obtains a required retardation amount for the ignition timing, it controls the ignition device so that the ignition timing is retarded by an amount equal to the required retardation amount (S105); and it controls the modification device so that the opening timing of the exhaust valve is retarded more than when the required retardation amount was obtained (S104).

Description

Technical Field

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

Background Art

[0002] The control device described in Patent Document 1 reduces the torque of an internal combustion engine by delaying the ignition timing during gear shifting of an automatic transmission.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the ignition timing is retarded, as a result, the temperature of the exhaust gas rises, and overheating of the exhaust system members is likely to occur.

Means for Solving the Problems

[0005] The control device for solving the above problems is a control device for an internal combustion engine, the internal combustion engine includes an ignition device, a changing device for changing the valve opening timing of an exhaust valve, an exhaust system member provided in an exhaust passage, and an injection device for injecting fuel to supply fuel to the internal combustion engine. When the control device obtains the amount of retardation required for the ignition timing, it performs a first retardation process of controlling the ignition device so that the ignition timing is retarded by an amount equal to the amount of retardation required, and a second retardation process of controlling the changing device so that the valve opening timing of the exhaust valve is retarded more than when the amount of retardation required is obtained.

Effects of the Invention

[0006] Overheating of the exhaust system members is unlikely to occur due to retarding the ignition timing.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of one embodiment of a control device. [Figure 2] Figure 2 is a flowchart showing the ignition timing retardation process performed by the control device shown in Figure 1. [Modes for carrying out the invention]

[0008] [About internal combustion engines] Referring to Figure 1, the configuration of the internal combustion engine 20 controlled by the control device 10 will be described. The internal combustion engine 20 is mounted on the vehicle 100. The internal combustion engine 20 comprises a cylinder 22, an intake passage 24, an exhaust passage 26, and an ignition device 28. Air flows through the intake passage 24 into the cylinder 22. The ignition device 28 ignites the mixture of air and fuel flowing into the cylinder 22 by spark discharge. The burnt gas is discharged through the exhaust passage 26. The vehicle 100 may also be equipped with a supercharger, including a turbine wheel installed in the exhaust passage 26.

[0009] The intake passage 24 includes a throttle valve 30 that adjusts the amount of air flowing through the intake passage 24, and an air flow meter 32 installed downstream of the throttle valve 30. The air flow meter 32 detects the intake air volume. In addition to detecting the intake air volume, the air flow meter 32 also detects the intake air temperature. The intake passage 24 includes an intake port 34 connected to the cylinder 22. The exhaust passage 26 includes an exhaust port 36 connected to the cylinder 22.

[0010] The internal combustion engine 20 has an intake valve 38. When the intake valve 38 is open, the intake port 34 and the cylinder 22 are connected. When the intake valve 38 is closed, the connection between the intake port 34 and the cylinder 22 is cut off. The internal combustion engine 20 also has an exhaust valve 40. When the exhaust valve 40 is open, the exhaust port 36 and the cylinder 22 are connected. When the exhaust valve 40 is closed, the connection between the exhaust port 36 and the cylinder 22 is cut off. The intake valve 38 and the exhaust valve 40 open and close in accordance with the rotation of the internal combustion engine 20.

[0011] The internal combustion engine 20 is equipped with a change device 42 for the intake valve 38 that changes the opening and closing timings of the intake valve 38. The change device 42 can continuously change the opening and closing timings of the intake valve 38 from the most advanced timing to the most retarded timing, respectively, based on the operating state of the internal combustion engine 20 (hereinafter referred to as the engine operating state).

[0012] Engine operating conditions include, for example, the rotational speed of the internal combustion engine 20 (hereinafter referred to as engine rotational speed), intake air volume, intake air temperature, and fuel injection volume. The advance timing is the earliest timing within the range of opening and closing timings of the intake valve 38 that can be changed by the modification device 42. The retard timing is the latest timing within the range of opening and closing timings of the intake valve 38 that can be changed by the modification device 42.

[0013] The internal combustion engine 20 is equipped with an exhaust valve modification device 44 for changing the opening and closing timings of the exhaust valve 40. The modification device 44 can continuously change the opening and closing timings of the exhaust valve 40 from the most advanced timing to the most retarded timing, respectively, based on the engine operating conditions. The most advanced timing is the earliest timing within the range of opening and closing timings of the exhaust valve 40 that can be changed by the modification device 44. The retarded timing is the latest timing within the range of opening and closing timings of the exhaust valve 40 that can be changed by the modification device 44.

[0014] The internal combustion engine 20 is equipped with an exhaust system component 46. The exhaust system component 46 is provided in the exhaust passage 26. The internal combustion engine 20 is equipped with a catalytic converter as part of the exhaust system component 46 for purifying exhaust gases. The catalytic converter is, for example, a three-way catalytic converter.

[0015] The internal combustion engine 20 is equipped with an injection system 48. The injection system 48 supplies fuel to the internal combustion engine 20 by injecting fuel. The injection system 48 includes an in-cylinder injection valve that injects fuel into the cylinder 22 and a drive circuit that drives the in-cylinder injection valve. The injection system 48 may also include a port injection valve that injects fuel into the intake port 34 and a drive circuit that drives the port injection valve.

[0016] The internal combustion engine 20 is equipped with various sensors. These sensors include, for example, a vehicle speed sensor 50 for detecting the vehicle speed 100, an accelerator opening sensor 52 for detecting the amount of accelerator operation, a rotational speed sensor 54 for detecting the engine rotational speed, a knocking sensor 56 for detecting the occurrence of knocking in cylinder 22, and a temperature sensor 58 for detecting the exhaust temperature of the exhaust passage 26.

[0017] Vehicle 100 includes an automatic transmission 60 and a gear control device 62 that controls the automatic transmission 60. The gear control device 62 controls the gear of the automatic transmission 60 based on the intake air volume, intake air temperature, the vehicle's speed, the accelerator pedal input, and the engine speed. The gear control device 62 outputs a signal to the control device 10 that identifies the current gear.

[0018] When the gear ratio of the automatic transmission 60 is changed, the gear control device 62 outputs a signal to the control device 10 indicating that a gear change is in progress, from the time the engagement of the engagement element of the automatic transmission 60 corresponding to the gear ratio before the gear change is released until the engagement of the engagement element of the automatic transmission 60 corresponding to the gear ratio after the gear change is completed. In one example, the control device 10 detects that the automatic transmission 60 is in progress based on this signal. The control device 10 may also detect that the automatic transmission 60 is in progress based on any of the following: the rate of change of engine rotation speed is greater than or equal to a predetermined value, a signal that identifies the current gear ratio, or the loss of the proportional relationship between engine rotation speed and vehicle speed.

[0019] [About the control device] The control device 10 controls the ignition device 28, the change device 44, and the injection device 48. The control device 10 controls the ignition device 28 to change the ignition timing. The control device 10 controls the change device 44 to change the valve opening timing of the exhaust valve 40. The control device 10 controls the injection device 48 to stop the fuel supply to the internal combustion engine 20 by performing fuel injection.

[0020] [Regarding Ignition Timing and Knocking] The control device 10 obtains a retardation required amount, which is the required amount when retardating the ignition timing from the current ignition timing. Based on an increase in the accelerator operation amount, the control device 10 grasps that the vehicle 100 has shifted to an accelerating state. When it is grasped that the vehicle 100 has shifted to an accelerating state, the control device 10 obtains the retardation required amount by calculating based on the output values of various sensors. Similarly, when receiving a signal indicating that the automatic transmission 60 is in the process of shifting from the shift control device 62 of the automatic transmission 60, the control device 10 obtains the retardation required amount.

[0021] When the ignition timing is advanced, the torque generated by the internal combustion engine 20 increases. On the other hand, when the ignition timing is advanced, knocking is likely to occur. The control device 10 determines the basic ignition timing based on the engine rotational speed, the intake air amount, the intake air temperature, etc. The control device 10 gradually advances the ignition timing from the basic ignition timing within a range where the knocking sensor 56 does not detect knocking.

[0022] When the vehicle 100 accelerates, the intake air volume, engine speed, fuel injection amount, etc. change suddenly, so the combustion of fuel in the cylinder 22 becomes unstable. When the combustion of fuel becomes unstable, the range of ignition timing at which knocking does not occur also changes. As a result, the ignition timing may be advanced beyond the range where knocking does not occur. Therefore, knocking is likely to occur when the vehicle 100 accelerates. In order to suppress the occurrence of knocking, when the vehicle 100 accelerates, the control device 10 retards the ignition timing. Also, when the automatic transmission 60 executes a gear shift, in order to suppress the shock associated with the gear shift, torque reduction of the internal combustion engine 20 is executed. At this time, in order to achieve torque reduction, the control device 10 retards the ignition timing. The gear shift of the automatic transmission 60 when achieving this torque reduction is, for example, an upshift.

[0023] [Regarding the valve opening timing of the exhaust valve] The more the valve opening timing of the exhaust valve 40 is retarded, the longer the exhaust stays in the cylinder 22. During this time, the heat of the exhaust is transmitted to the inner peripheral surface of the cylinder 22. Therefore, the more the valve opening timing of the exhaust valve 40 is retarded, both the exhaust temperature and the temperature of the exhaust system member 46 become lower.

[0024] On the other hand, when the valve opening timing of the exhaust valve 40 is retarded, problems are likely to occur. A decrease in the filling efficiency of the intake air due to the exhaust remaining in the cylinder 22 and a decrease in the filling efficiency due to an increase in the period during which the exhaust valve 40 and the intake valve 38 are open simultaneously are examples of problems. Also, for example, when the vehicle 100 is equipped with a supercharger, a decrease in the supercharging efficiency is also an example of a problem.

[0025] [Regarding the temperature of the exhaust system member] The control device 10 estimates the temperature of the exhaust system components 46 based on the exhaust temperature and engine operating conditions. The control device 10 estimates the temperature of the exhaust system components 46 based on the output values ​​of various sensors. For example, the temperature of the exhaust system components 46 is higher when the exhaust temperature is high, when the intake air and fuel injection amounts are high, and when the ignition timing is delayed. Also, for example, the later the opening timing of the exhaust valve 40, the lower both the exhaust temperature and the temperature of the exhaust system components 46 become.

[0026] The control device 10 estimates the temperature rise of the exhaust system component 46 when the ignition timing is retarded, based on the temperature of the exhaust system component 46 and the amount of ignition timing retardation. For example, the temperature rise of the exhaust system component 46 increases as the temperature of the exhaust system component 46 decreases and as the amount of ignition timing retardation increases.

[0027] [Regarding ignition timing retardation] Referring to Figure 2, the procedure for ignition timing retardation performed by the control device 10 will be described. When the control device 10 starts ignition timing retardation processing, in step S101, it obtains the requested amount of ignition timing retardation. After that, the control device 10 proceeds to step S102. In the following description, the amount of ignition timing retardation from the ignition timing at the time the requested amount of ignition timing retardation was obtained will be referred to as the ignition timing retardation amount.

[0028] In step S102, the control device 10 determines whether the ignition retardation requirement is less than or equal to the first ignition retardation allowance. The first ignition retardation allowance is the upper limit of the ignition retardation amount within the range in which the temperature of the exhaust system component 46 does not exceed the temperature allowance. When the ignition retardation requirement exceeds the first ignition retardation allowance, setting the ignition retardation amount to equal the required retardation amount makes it more likely that the temperature of the exhaust system component 46 will exceed the temperature allowance. The temperature allowance is, for example, the temperature at which the degree of damage or deterioration of the exhaust system component 46 due to the temperature rise of the exhaust system component 46 becomes significant. A significant degree of damage or deterioration of the exhaust system component 46 means that the decrease in the required function of the exhaust system component 46 is so large that it cannot be ignored. For example, if the exhaust system component 46 is a three-way catalytic converter, the temperature allowance is the temperature at which the degree of deterioration of the three-way catalytic converter becomes significant.

[0029] If the control device 10 determines that the requested ignition timing is less than or equal to the first allowable ignition timing (S102: YES), it proceeds to step S105. If the control device 10 determines that the requested ignition timing is greater than the first allowable ignition timing (S102: NO), it proceeds to step S103.

[0030] In step S103, the control device 10 determines whether the ignition timing retardation requirement is less than or equal to the second ignition timing retardation allowance. The second ignition timing retardation allowance is greater than the first ignition timing retardation allowance. The second ignition timing retardation allowance is the upper limit of the ignition timing retardation when the ignition timing is retarded while the opening timing of the exhaust valve 40 is retarded to the most retarded timing, within the range in which the temperature of the exhaust system member 46 does not exceed the temperature tolerance value. The first and second ignition timing retardation allowances that the control device 10 refers to when the vehicle 100 is accelerating, and the first and second ignition timing retardation allowances that the control device 10 refers to when the automatic transmission 60 is shifting, may be the same or different.

[0031] If the control device 10 determines that the requested ignition timing is less than or equal to the second allowable ignition timing (S103: YES), it proceeds to step S104. If the control device 10 determines that the requested ignition timing is greater than the second allowable ignition timing (S103: NO), it proceeds to step S106. The processes in steps S102 and S103 are both examples of determination processes.

[0032] In step S104, the control device 10 performs a second timing retardation process. The second timing retardation process controls the modification device 44 so that the opening timing of the exhaust valve 40 is retarded compared to when the timing retardation request amount was obtained in step S101. The second timing retardation process retards the opening timing of the exhaust valve 40 to the timing of the most retarded timing. After that, the control device 10 proceeds to step S105.

[0033] In step S105, the control device 10 performs a first ignition timing retardation process. The first ignition timing retardation process controls the ignition device 28 so that the amount of ignition timing retardation since the time the ignition timing retardation request amount was obtained in step S101 becomes equal to the ignition timing retardation request amount. The process in step S105 is executed if, in step S102, it is determined that the ignition timing retardation request amount is less than or equal to the first ignition timing retardation allowance, or if, as a result of determining in step S103 that the ignition timing retardation request amount is less than or equal to the first ignition timing retardation allowance, the opening timing of the exhaust valve 40 is retarded to the minimum ignition timing in step S104. Therefore, when the ignition device 28 is controlled so that the ignition timing retardation amount is equal to the ignition timing retardation request amount, the temperature of the exhaust system components 46 is unlikely to exceed the temperature tolerance value.

[0034] In step S106, the control device 10 performs a fuel cut process. The fuel cut process is a process that controls the injection device 48 to stop fuel injection. In step S103, if the control device 10 determines that the ignition timing retardation requirement exceeds the second ignition timing retardation allowance, the control device 10 determines that it is not possible to maintain the temperature of the exhaust system component 46 above the temperature allowance and to retard the ignition timing to the ignition timing retardation requirement, and performs a fuel cut process. By performing a fuel cut process, neither a temperature rise in the exhaust system component 46 nor knocking occurs.

[0035] However, when fuel cut-off is performed, drivability is likely to deteriorate. For example, a decrease in acceleration performance after fuel injection is restarted, instability of combustion after fuel injection is restarted, and an increase in vibration of the internal combustion engine 20 due to this instability of combustion are all factors that worsen drivability.

[0036] The ignition timing retardation process is completed upon completion of step S105 or step S106. In summary, the control device 10 executes the first retardation process if it determines that the retardation request amount is less than or equal to the first retardation allowance. The control device 10 executes the first and second retardation processes if it determines that the retardation request amount exceeds the first retardation allowance and is less than or equal to the second retardation allowance. The control device 10 executes the fuel cut process if it determines that the retardation request amount exceeds the second retardation allowance.

[0037] <Effects of this embodiment> The control device 10 of this embodiment has the following effects. (1) The control device 10 performs a second ignition timing retardation process in conjunction with the first ignition timing retardation process. By performing the second ignition timing retardation process, overheating of the exhaust system components 46, which occurs when the ignition timing is retarded in the first ignition timing retardation process, is less likely to occur.

[0038] (2) When the control device 10 determines that the requested ignition timing is less than or equal to the allowable ignition timing, it does not perform the second ignition timing adjustment. Therefore, the above-mentioned problems associated with the execution of the second ignition timing adjustment are less likely to occur.

[0039] (3) In the second timing retardation process, the control device 10 retards the opening timing of the exhaust valve 40 to the timing of the most retarded timing. Compared to the case in which the opening timing of the exhaust valve 40 is retarded to an earlier timing than the timing of the most retarded timing, the exhaust temperature is reduced, so the temperature rise of the exhaust system components 46 is less likely to occur.

[0040] (4) When the control device 10 determines that the ignition timing retardation request exceeds the first ignition timing retardation allowance and is less than or equal to the second ignition timing retardation allowance, it executes the first ignition timing retardation process and the second ignition timing retardation process. Therefore, compared to the case where the control device 10 executes a fuel cut process when the ignition timing retardation allowance is exceeded, deterioration of drivability is less likely to occur.

[0041] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0042] A configuration including multiple exhaust system components 46 can be adopted. The multiple exhaust system components 46 include, for example, at least two of a catalytic converter, a filter for collecting particulate matter contained in the exhaust, a temperature sensor 58, and, if the vehicle 100 is equipped with a supercharger, a turbocharger turbine wheel.

[0043] In this configuration, both the first and second ignition timing retardation allowances are determined based on the degree of damage or deterioration of the component among multiple components that is most severely damaged or deteriorated by the ignition timing retardation. The degree of damage or deterioration of each of the multiple exhaust system components 46 can be determined based on the temperature of the component and the temperature rise when the first ignition timing retardation is performed, or when both the first and second ignition timing retardation are performed. The components referenced when determining the first and second ignition timing retardation allowances may be the same component or different components.

[0044] Therefore, with the above configuration, if the allowable angle retardation is less than or equal to the first allowable angle retardation, even if the first angle retardation treatment is performed, it is unlikely that any of the multiple exhaust system components 46 will suffer significant damage or deterioration. Furthermore, if the allowable angle retardation exceeds the first allowable angle retardation and is less than or equal to the second allowable angle retardation, if the second angle retardation treatment is performed in conjunction with the first angle retardation treatment, it is unlikely that any of the multiple exhaust system components 46 will suffer significant damage or deterioration.

[0045] The control device 10 may perform control without performing the determination in step S102. In this case, the control device 10 performs the acquisition process in step S101 and then proceeds to step S103. The processing from step S103 onward is performed in the same manner as in the embodiment.

[0046] The control device 10 does not need to be able to change the closing timing of the exhaust valve 40. The control device 10 only needs to be able to retard the opening timing of the exhaust valve 40. • In the second timing retardation process, the opening timing of the exhaust valve 40 may be retarded to an earlier time than the time of the most retarded timing. In this case, the opening timing of the exhaust valve 40 should be set to an earlier time, within a range where the temperature of the exhaust system component 46 does not exceed the temperature tolerance value when the first timing retardation process is performed. As a result, problems associated with the execution of the second timing retardation process are less likely to occur.

[0047] The control device 10 may retard the ignition timing when the automatic transmission 60 is downshifting. During downshifting, fuel cut-off is performed, so shocks are less likely to occur. However, when downshifting is performed by kickdown shifting, which is caused by pressing the accelerator pedal hard, fuel injection is performed, so shocks are more likely to occur. [Explanation of Symbols]

[0048] 10...Control device 20...Internal combustion engine 22...Cylinder 24...Intake passage 26...Exhaust passage 28...Ignition system 30...Throttle valve 32...Air flow meter 34...Intake port 36...Exhaust port 38...Intake valve 40...Exhaust valve 42...Change device 44...Modification device 46...Exhaust system component 48...Injection device 50...Vehicle speed sensor 52...Accelerator position sensor 54...Rotation speed sensor 56...Knocking sensor 58...Temperature sensor 60...Automatic transmission 62...Transmission control device 100...Vehicle

Claims

1. A control device for an internal combustion engine, The internal combustion engine comprises an ignition device, a device for changing the opening timing of the exhaust valve, an exhaust system member provided in the exhaust passage, and an injection device for injecting fuel and supplying fuel to the internal combustion engine. When the control device obtains the required amount for ignition timing retardation, A first timing retardation process controls the ignition device so that the ignition timing is retarded by an amount equal to the required timing retardation amount, A second timing retardation process is performed, which controls the modification device so that the opening timing of the exhaust valve is retarded compared to when the timing retardation request amount was obtained. Control device.

2. The control device is When the aforementioned ignition timing retardation request amount is obtained, a determination process is executed to determine whether the aforementioned ignition timing retardation request amount exceeds the ignition timing retardation allowance. When it is determined that the requested ignition timing is less than or equal to the allowable ignition timing, the first ignition timing process is executed. When it is determined that the requested ignition timing delay exceeds the allowable ignition timing delay, the first ignition timing delay process and the second ignition timing delay process are executed. The control device according to claim 1.

3. The second timing retardation process is a process that retards the opening timing of the exhaust valve to the latest timing within the range that can be changed by the modification device, which is the latest timing retardation time. The control device is When the aforementioned ignition timing retardation request amount is obtained, a determination process is executed to determine whether the aforementioned ignition timing retardation request amount exceeds the ignition timing retardation allowance. When it is determined that the requested ignition timing is less than or equal to the allowable ignition timing, the first ignition timing process and the second ignition timing process are executed. When it is determined that the required ignition timing retardation amount exceeds the allowable ignition timing retardation amount, a fuel cut process is executed to control the injection device to stop fuel injection. The control device according to claim 1.

4. The second timing retardation process is a process that retards the opening timing of the exhaust valve to the latest timing within the range that can be changed by the modification device, which is the latest timing retardation time. The control device is When the aforementioned ignition timing retardation request amount is obtained, a determination process is executed to determine whether the ignition timing retardation request amount exceeds a first ignition timing retardation allowance, and whether the ignition timing retardation request amount exceeds a second ignition timing retardation allowance that is greater than the first ignition timing retardation allowance. When it is determined that the requested ignition timing is less than or equal to the first ignition timing tolerance, the first ignition timing process is executed. When it is determined that the requested ignition timing is greater than the first ignition timing tolerance and less than or equal to the second ignition timing tolerance, the first ignition timing process and the second ignition timing process are executed. When it is determined that the required ignition timing retardation amount exceeds the second allowable ignition timing retardation amount, a fuel cut process is executed to control the injection device to stop fuel injection. The control device according to claim 1.

5. The aforementioned internal combustion engine is mounted in a vehicle equipped with an automatic transmission. The control device acquires the ignition timing retardation request amount when at least one of the acceleration of the vehicle and the shifting of the automatic transmission is performed. The control device according to any one of claims 1 to 4.

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