Engine control device

Abstract

The present application suppresses a change in engine output caused by adjustment of the amount of delay of ignition timing, while suppressing a decrease in the warming-up effect of an exhaust purification catalyst. An engine control device, in a catalyst warming-up process in which an exhaust purification catalyst is heated by delaying ignition timing, implements a delay amount adjustment process that adjusts the amount of delay in accordance with the combustion state of the engine, and a multiple injection process that implements fuel injection by an in-cylinder injection valve in two stages, intake stroke injection and compression stroke injection. Furthermore, the engine control device, in the catalyst warming-up process, performs an injection ratio adjustment process that adjusts the ratio of the fuel injection amounts of the intake stroke injection and the compression stroke injection in accordance with a change in the output of the engine due to adjustment of the amount of delay of ignition timing in the delay amount adjustment process.

Description

Technical Field

[0001] This invention relates to an engine control device. Background Technology

[0002] Patent Document 1 describes an engine control device that performs a catalyst warming promotion treatment by delaying the engine's ignition timing to promote the heating of an exhaust purification catalyst placed in the exhaust passage. In this engine control device, the amount of ignition timing delay is reduced when the engine speed decreases during the catalyst warming promotion treatment.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-175889 Summary of the Invention

[0004] Reducing the ignition timing delay improves combustion and increases engine output. To maintain engine output, it's necessary to reduce both the ignition timing delay and engine load. However, reducing the engine load, combined with the reduction in ignition timing delay, diminishes the warming-up effect of the exhaust gas purification catalyst.

[0005] The engine control device for solving the above-mentioned problems is configured as an engine control device applicable to an engine including: an in-cylinder injection valve that injects fuel into a combustion chamber; and an exhaust gas purification catalyst disposed in an exhaust passage. The engine control device performs the following processes: catalyst heating treatment, which heats the exhaust gas purification catalyst by delaying the ignition timing of the engine; delay amount adjustment treatment, which adjusts the delay amount of the ignition timing according to the combustion state of the engine during the catalyst heating treatment; multi-injection treatment, which divides the fuel injection of the in-cylinder injection valve into intake stroke injection and compression stroke injection; and injection ratio adjustment treatment, which adjusts the ratio of the fuel injection amounts of the intake stroke injection and the compression stroke injection in the multi-injection treatment according to the output change of the engine caused by adjusting the delay amount during the delay amount adjustment treatment.

[0006] Invention Effects

[0007] The aforementioned engine control device has the effect of maintaining the heating effect of the exhaust purification catalyst while suppressing changes in engine output caused by adjustments to the ignition timing delay. Attached Figure Description

[0008] Figure 1 This is a diagram schematically illustrating the configuration of one embodiment of the engine control device.

[0009] Figure 2 yes Figure 1The flowchart shows the injection ratio adjustment routine performed by the engine control unit.

[0010] Figure 3 It is a graph showing the relationship between the injection ratio during the intake stroke and the engine output.

[0011] Figure 4 This is a flowchart of an injection ratio adjustment routine performed in another embodiment of the engine control unit. Detailed Implementation

[0012] The following is for reference. Figures 1-3 A detailed description of one embodiment of the engine control device will be provided.

[0013] <Composition of Engine Control Unit 30>

[0014] First, refer to Figure 1 The configuration of the engine 10 to which the engine control device 30 of this embodiment is applied will be described. The engine 10 is mounted on a vehicle. The engine 10 includes: a combustion chamber 11 for burning a mixture of air and fuel; an intake passage 12 as an intake path for introducing intake air into the combustion chamber 11; and an exhaust passage 13 as an exhaust path for discharging exhaust gas from the combustion chamber 11. An air flow meter 14 for detecting the amount of air intake of the engine 10 and a throttle valve 15 for adjusting the intake air flow rate by changing the flow path area of ​​the intake air are provided in the intake passage 12. An exhaust gas purification catalyst 17 is provided in the exhaust passage 13. Furthermore, the engine 10 includes an in-cylinder injection valve 19 for injecting fuel into the combustion chamber 11 and an ignition device 20 for igniting the mixture in the combustion chamber 11 by spark discharge.

[0015] Next, refer to Figure 1The configuration of the engine control device 30 in this embodiment will be described. The engine control device 30 is configured as an electronic control unit including an arithmetic processing unit 31 and a storage unit 32. The storage unit 32 stores control programs or data. The engine control device 30 is configured such that the arithmetic processing unit 31 executes the program stored in the storage unit 32, thereby performing various processes for controlling the engine 10. In addition to the air flow meter 14 mentioned above, the engine control device 30 also receives detection signals from various sensors used to detect the driving status of the engine 10, such as the crankshaft angle sensor 22, the accelerator pedal sensor 33, and the vehicle speed sensor 34. The crankshaft angle sensor 22 is a sensor that detects the crankshaft angle. The crankshaft angle represents the rotation angle of the crankshaft 21, which is the output shaft of the engine 10. The accelerator pedal sensor 33 is a sensor that detects the accelerator pedal opening. The accelerator pedal opening represents the amount of accelerator pedal operation in the vehicle equipped with the engine 10. The vehicle speed sensor 34 is a sensor that detects the vehicle speed. The vehicle speed represents the driving speed of the vehicle equipped with the engine 10. The engine control unit 30 calculates the engine speed based on the crankshaft angle. Furthermore, the engine control unit 30 calculates the engine load rate based on the engine speed, intake air volume, etc. The engine load rate represents the intake air filling rate of the combustion chamber 11.

[0016] The engine control unit 30 calculates the operating parameters of the engine 10 based on the detection results of each sensor. These operating parameters include the throttle opening (the opening ratio of the throttle valve 15), the fuel injection quantity and timing of the in-cylinder injection valve 19, and the ignition timing of the air-fuel mixture based on the ignition device 20. Furthermore, the engine control unit 30 operates the actuators of the engine 10, such as the throttle valve 15, the in-cylinder injection valve 19, and the ignition device 20, based on the calculated operating parameters, thereby controlling the engine 10.

[0017] <Catalyst Warm-up Enhancement Control>

[0018] The engine control unit 30 performs catalytic converter warm-up promotion control during cold engine operation of the engine 10 to promote the warm-up of the exhaust gas purification catalyst 17. In the catalytic converter warm-up promotion control, the engine control unit 30 implements a catalytic converter heating process that heats the exhaust gas purification catalyst 17 by retarding the ignition timing of the engine 10. Furthermore, the engine control unit 30 performs a delay amount adjustment process in the catalytic converter warm-up promotion control, adjusting the ignition timing delay amount according to the combustion state of the engine 10 during the catalytic converter heating process. During the catalytic converter heating process, if the ignition timing of the engine 10 is delayed, the temperature of the exhaust gas flowing into the exhaust gas purification catalyst 17 increases, thus promoting the warm-up of the exhaust gas purification catalyst 17. However, if the ignition timing is delayed excessively, it will lead to combustion deterioration. In contrast, the engine control unit 30 suppresses combustion deterioration by adjusting the ignition timing delay amount according to the combustion state of the engine 10 during the delay amount adjustment process. Specifically, in the delay adjustment process, if a deterioration in the combustion state is confirmed during the catalyst warming process based on an increase in the amount of engine speed variation, the engine control unit 30 reduces the ignition timing delay. Furthermore, in the following description, the catalyst warming process performed during the catalyst warm-up promotion control of the engine 10 during cold engine operation will be referred to as the catalyst warming process during cold engine operation.

[0019] Multi-jet processing

[0020] During engine operation, the engine control unit 30 performs multi-injection processing, dividing fuel injection into the combustion chamber 11 via the in-cylinder injection valve 19 into intake stroke injection and compression stroke injection. In engine 10, segmented injection using multi-injection processing is also performed during catalyst warm-up processing during cold engine operation. During multi-injection processing, the engine control unit 30 determines the ratio of fuel injection quantity during intake stroke injection and compression stroke injection based on engine speed, engine load rate, and other factors.

[0021] <Injection ratio adjustment>

[0022] During catalyst warm-up treatment while the engine is running cold, the engine control unit 30 performs injection ratio adjustment processing to adjust the ratio of fuel injection quantity during intake stroke and compression stroke in the multi-injection control. Furthermore, in the following description, the ratio of fuel injection quantity during intake stroke is referred to as the intake stroke injection ratio, and the ratio of fuel injection quantity during compression stroke is referred to as the compression stroke injection ratio.

[0023] Figure 2The diagram shows a flowchart of the injection ratio adjustment routine executed by the engine control unit 30 for the injection ratio adjustment process implemented during catalyst warming treatment when the engine is cold. During engine operation, the engine control unit 30 repeatedly executes this routine according to a predetermined control cycle.

[0024] If this routine begins, the engine control unit 30 first determines in step S100 whether a catalyst warming process is being performed during cold engine operation. If it is determined that a catalyst warming process is not being performed during cold engine operation (No), the engine control unit 30 terminates the processing of this routine in the current control cycle. Conversely, if it is determined that a catalyst warming process is being performed during cold engine operation (Yes), the engine control unit 30 proceeds to step S110.

[0025] In step S110, the engine control unit 30 determines whether the actual output is equal to the target output. If it determines that the actual output is equal to the target output (yes), the engine control unit 30 terminates the processing of this routine in the current control cycle. If it determines that the actual output is not equal to the target output (no), the engine control unit 30 proceeds to step S120. The actual output represents the actual value of the engine output, and the target output represents the target value of the engine output. The engine control unit 30 estimates the actual output based on engine load rate, engine speed, etc. Furthermore, the engine control unit 30 sets the target output as the engine output required to meet the driver's driving requirements based on the amount of accelerator pedal operation, vehicle speed, etc.

[0026] In step S120, the engine control unit 30 determines whether the actual output is less than the target output. If it determines that the actual output is less than the target output (yes), the engine control unit 30 proceeds to step S130. Furthermore, in step S130, the engine control unit 30 reduces the intake stroke injection ratio. On the other hand, if it determines that the actual output is not less than the target output (no), that is, if it determines that the actual output is greater than the target output, the engine control unit 30 proceeds to step S140. Furthermore, in step S140, the engine control unit 30 increases the intake stroke injection ratio. After the processing in step S130 or step S140, the engine control unit 30 ends the processing of this routine in the current control cycle. Alternatively, the increase or decrease in the intake stroke injection ratio in steps S130 and S140 can be determined, for example, based on the difference between the actual output and the target output, so that a larger difference results in a larger value. Furthermore, the intake stroke injection ratio in steps S130 and S140 can be increased or decreased by a constant amount each time during the period when the actual output is less than the target output or the actual output is greater than the target output.

[0027] <The Role of the Implementation Method>

[0028] In the catalyst warm-up enhancement control, the engine control unit 30 performs a catalyst warm-up process during cold engine operation by retarding the ignition timing of the engine 10 to heat the exhaust purification catalyst 17. Furthermore, in the catalyst warm-up enhancement control, the engine control unit 30 performs a delay adjustment process to adjust the ignition timing delay based on the combustion state of the engine 10 during the catalyst warm-up process during cold engine operation. Moreover, during the catalyst warm-up process during cold engine operation, the engine control unit 30 performs multi-injection processing by dividing the fuel injection from the in-cylinder injection valve 19 into intake stroke injection and compression stroke injection.

[0029] If combustion is improved by reducing the ignition timing delay through delay adjustment processing, engine output increases. In contrast, the engine control device 30 of this embodiment compensates for the change in engine output caused by the adjustment of the ignition timing delay by adjusting the intake stroke injection ratio and the compression stroke injection ratio based on injection ratio adjustment processing.

[0030] Figure 3 The diagram shows the relationship between the intake stroke injection ratio and engine output. This relationship changes during cold and warm-up operation of the engine 10. Figure 3 In the diagram, a solid line is used to show the relationship between the intake stroke injection ratio and engine output during cold-running of engine 10. Furthermore, in... Figure 3 In the diagram, a double-dotted line is used to show the relationship between the intake stroke injection ratio and the engine output during the warm-up operation of engine 10.

[0031] When the engine 10 is running cold, the wall temperature of the combustion chamber 11 is low, and the fuel injected by the in-cylinder injection valve 19 is in a state where it is difficult to vaporize. The fuel that does not vaporize after injection adheres to the wall of the combustion chamber 11. The fuel adhering to the wall of the combustion chamber 11 hardly participates in combustion within the combustion chamber 11. Incidentally, the engine control unit 30, in its fuel injection control of the engine 10, predicts the amount of fuel adhering to the wall of the combustion chamber 11 and incrementally corrects the fuel injection amount of the in-cylinder injection valve 19. During the compression stroke, the intake air in the combustion chamber 11 is compressed, and its temperature rises; therefore, the temperature inside the combustion chamber 11 is higher during the compression stroke than during the intake stroke. Therefore, when the engine 10 is running cold, the proportion of fuel vaporized and participating in combustion during the compression stroke is higher than that injected during the intake stroke. Therefore, even if the total amount of fuel injected is the same, the engine output generated by combustion is greater when the intake stroke injection ratio is higher than when the intake stroke injection ratio is lower.

[0032] In contrast, in this embodiment, during the catalyst warming process during cold engine operation, if the actual output of the engine 10 is less than the target output, the engine control device 30 reduces the intake stroke injection ratio. This increases the compression stroke injection ratio, resulting in more fuel participating in combustion and thus increasing engine output. Conversely, during the catalyst warming process during cold engine operation, if the actual output of the engine 10 is greater than the target output, the engine control device 30 increases the injection stroke injection ratio. This decreases the compression stroke injection ratio, resulting in less fuel participating in combustion and thus increasing engine output. Therefore, the increase in engine output caused by the reduction in ignition timing retardation corresponding to the combustion degradation during the catalyst warming process during cold engine operation is offset by the decrease in engine output caused by the increase in the intake stroke injection ratio. Unlike the case where engine output is reduced by decreasing the engine load rate, the total amount of fuel injected by the in-cylinder injection valve 19 does not change even if the intake stroke injection ratio changes. Unburned fuel in the combustion chamber 11 is discharged into the exhaust passage 13 along with the exhaust gas. Furthermore, unburned fuel in the exhaust gas burns in the exhaust gas. Therefore, even if engine output is reduced by decreasing the intake stroke injection ratio, the reduction in heat of the exhaust flowing into the exhaust purification catalyst 17 is limited.

[0033] <Effects of the Implementation Method>

[0034] The engine control device 30 of this embodiment has the following effects.

[0035] (1) During the catalyst warming process in cold engine operation, which heats the exhaust purification catalyst 17 by delaying the ignition timing of the engine 10, the engine control unit 30 performs a delay amount adjustment process to adjust the ignition timing delay amount according to the combustion state of the engine 10. Furthermore, during the catalyst warming process in cold engine operation, the engine control unit 30 performs multi-injection processing by dividing the fuel injection of the in-cylinder injection valve 19 into intake stroke injection and compression stroke injection. Moreover, during the catalyst warming process in cold engine operation, the engine control unit 30 performs an injection ratio adjustment process to adjust the ratio of fuel injection amounts during intake stroke injection and compression stroke injection based on the output change of the engine 10 caused by the ignition timing delay amount adjustment during the delay amount adjustment process. Therefore, it is possible to maintain the warming effect of the exhaust purification catalyst 17 while suppressing changes in engine output caused by the ignition timing delay amount adjustment.

[0036] (2) In the engine control unit 30, during the injection ratio adjustment process of the catalyst warming treatment during cold engine operation of the engine 10, when the ignition timing delay is reduced, the ratio of fuel injection during the compression stroke is increased. Therefore, it is possible to adjust the appropriate injection ratio corresponding to the vaporization rate of fuel injected during the intake stroke and compression stroke during cold engine operation.

[0037] (3) The engine control unit 30 adjusts the injection ratio in the injection ratio adjustment process based on the comparison between the actual value and the target value of the engine output. Therefore, it is possible to adjust the appropriate injection ratio in accordance with the changes in engine output corresponding to the adjustment of the ignition timing delay.

[0038] (Other implementation methods)

[0039] The above-described embodiments can be implemented in the following ways. The above-described embodiments and the following modifications can be combined with each other to implement them without causing technical inconsistencies.

[0040] <Catalyst Heating During Warm-up>

[0041] For purposes such as recovering from poisoning of the exhaust gas purification catalyst 17, the exhaust gas purification catalyst 17 is sometimes heated by retarding the ignition timing during engine warm-up. Even during this catalyst warm-up process, if the ignition timing retardation is adjusted according to the combustion state of the engine 10, the engine output changes according to the change in ignition timing retardation. This change in engine output can be compensated for by adjusting the injection ratio. However, the relationship between the injection ratio and engine output differs between cold and warm-up operation.

[0042] In the foregoing Figure 3 In the diagram, a double-dotted line is used to show the relationship between the intake stroke injection ratio and engine output during warm-up operation. During warm-up operation, the wall temperature inside the combustion chamber 11 is higher than during cold-up operation, thus reducing the likelihood of fuel adhering to the walls. During such warm-up operation, compared to compression stroke injection, the proportion of fuel that participates in combustion through vaporization via mixing with the intake air increases. Therefore, in the catalyst warm-up treatment during warm-up operation, if the ignition timing retardation is reduced by adjusting the retardation amount, it can be configured as an injection ratio adjustment treatment that increases the intake stroke injection ratio. In the following description, the catalyst warm-up treatment performed during engine 10's warm-up operation will be referred to as the warm-up operation catalyst warm-up treatment.

[0043] Figure 4The diagram shows a flowchart of the injection ratio adjustment routine executed by the engine control unit 30 for the injection ratio adjustment process implemented during catalyst warm-up during engine operation. During engine operation, the engine control unit 30 repeatedly executes this routine according to a predetermined control cycle.

[0044] If this routine begins, the engine control unit 30 first determines in step S200 whether a catalyst warm-up process is being performed during engine warm-up. If it is determined that a catalyst warm-up process is being performed (Yes), the engine control unit 30 proceeds to step S210. Conversely, if it is determined that a process is not being performed (No), the processing of this routine in the current control cycle ends. In step S210, the engine control unit 30 determines whether the actual output is equal to the target output. If it is determined that the actual output is equal to the target output (Yes), the engine control unit 30 ends the processing of this routine in the current control cycle. If it is determined that they are not equal (No), the processing proceeds to step S220. In step S220, the engine control unit 30 determines whether the actual output is less than the target output. If it is determined that the actual output is less than the target output (Yes), in step S230, the engine control unit 30 increases the intake stroke injection ratio. On the other hand, if it is determined that the actual output is not less than the target output, that is, if it is determined that the actual output is greater than the target output (no), then in step S240, the engine control device 30 reduces the intake stroke injection ratio. After the processing in step S230 or step S240, the engine control device 30 ends the processing of this routine in the current control cycle.

[0045] <Method for confirming the actual output of engine 10>

[0046] In the above-described embodiment, the engine control unit 30 estimates the actual output of the engine 10 based on engine speed, engine load rate, etc. The actual output of the engine 10 can also be determined using other methods. For example, if a torque sensor is installed on the crankshaft 21, the actual output of the engine 10 can be calculated based on the detection result of the torque sensor and the engine speed. Furthermore, if the engine 10 is installed in a hybrid vehicle equipped with a motor that is driven and connected to the crankshaft 21, the torque can be determined using a rotary transformer installed on the motor. In this case, the actual output of the engine 10 can also be calculated based on the torque and the engine speed.

[0047] <Adjustment of Injection Ratio>

[0048] In the above-described embodiment, the engine control unit 30 adjusts the injection ratio based on a comparison between the actual output of the engine 10 and the target output during the injection ratio adjustment process. Alternatively, the adjustment of the injection ratio corresponding to the output change of the engine 10 caused by the adjustment of the ignition timing delay during the delay amount adjustment process can be performed, for example, in other ways described below.

[0049] In engine 10, engine speed feedback control is sometimes performed during idling driving, etc. When catalyst warming treatment is implemented in such engine speed feedback control, if the engine output increases due to reducing the ignition timing retardation through retardation adjustment treatment, the actual engine speed becomes higher than the target value. Therefore, when engine speed feedback control is performed, the change in engine output during catalyst warming treatment can be confirmed by comparing the actual engine speed with the target value. Therefore, in this case, the injection ratio can be adjusted based on the comparison result between the actual and target engine speeds.

[0050] • The injection ratio can also be adjusted based on the ignition timing delay. For example, the injection ratio can be adjusted based on a comparison between the ignition timing delay before and after the adjustment. If the adjusted ignition timing delay is less than the original, the engine output increases. Therefore, by adjusting the injection ratio to the side where the engine output decreases, the change in engine output can be suppressed.

[0051] <Other>

[0052] • It can vary the number of intake stroke injections and compression stroke injections in injection control. That is, multi-injection control can be implemented by dividing the fuel injection of the in-cylinder injection valve 19 into more than one intake stroke injection and more than one compression stroke injection.

[0053] • When the engine 10 performs catalyst warm-up treatment by delaying ignition timing in both cold and warm-up states, it can simultaneously utilize... Figure 2 and Figure 4 Injection ratio adjustment processing for two injection ratio adjustment routines.

[0054] The above-described embodiments and their modifications can also be applied to... Figure 1 The engine has 10 different configurations.

[0055] Symbol Explanation

[0056] 10-Engine, 11-Combustion chamber, 12-Intake passage, 13-Exhaust passage, 14-Air flow meter, 15-Throttle valve, 17-Exhaust gas purification catalyst, 19-In-cylinder injection valve, 20-Ignition device, 21-Crankshaft, 22-Crankshaft angle sensor, 30-Engine control unit, 31-Processing unit, 32-Storage device, 33-Throttle pedal sensor, 34-Vehicle speed sensor.

Claims

1. An engine control device, applicable to an engine comprising: an in-cylinder injection valve for injecting fuel into a combustion chamber; and an exhaust gas purification catalyst disposed in an exhaust passage, characterized in that... The following steps will be taken: Catalyst heating treatment heats the exhaust purification catalyst by delaying the ignition timing of the engine. The delay adjustment process adjusts the ignition timing delay based on the combustion state of the engine during the catalyst heating process. Multi-injection processing divides the fuel injection of the in-cylinder injection valve into intake stroke injection and compression stroke injection; and The injection ratio adjustment process adjusts the ratio of fuel injection amounts during the intake stroke and the compression stroke in the multi-injection process based on the output change of the engine caused by adjusting the delay amount during the delay amount adjustment process.

2. The engine control device according to claim 1, characterized in that, The configuration is such that the catalyst heating treatment is performed during cold engine operation, and the injection ratio adjustment treatment increases the ratio of fuel injection during the compression stroke when the delay amount is reduced by the delay amount adjustment treatment.

3. The engine control device according to claim 1, characterized in that, The catalyst heating treatment is performed during the engine warm-up operation, and the ratio of fuel injection quantity during the intake stroke is increased when the delay amount is reduced by the delay amount adjustment treatment.

4. The engine control device according to claim 1, characterized in that, The adjustment of the fuel injection ratio in the injection ratio adjustment process is based on the comparison between the actual value and the target value of the engine output.

5. The engine control device according to claim 1, characterized in that, The adjustment of the fuel injection ratio in the injection ratio adjustment process is based on the comparison between the actual value and the target value of the engine speed.

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