Control device for V-type internal combustion engine

Abstract

The present invention addresses the problem of sufficiently obtaining a sports sound effect when bubble control is executed. The internal combustion engine is a V-shaped internal combustion engine in which the ignition sequence of cylinders is unequally spaced between cylinder rows. The control device executes bubbling control when transitioning from accelerator-on to accelerator-off. The range of a lean air-fuel ratio in which a bubble sound is generated by bubble control is set to an appropriate range. When performing the bubble control, the control device sets, for each cylinder, a fuel injection amount of the cylinder that is preset so that the in-cylinder air-fuel ratio falls within the appropriate range.

Description

Technical Field

[0001] This invention relates to a control device for a V-type internal combustion engine. Background Technology

[0002] For example, as described in Patent Document 1, there are known internal combustion engines that perform bubbling control to ensure good sound quality during driving. Bubbling control is the control that continues the combustion of the air-fuel mixture by significantly delaying the ignition timing without cutting off the fuel supply when the accelerator is switched on or off. In this way, a semi-misfire state is generated by significantly delaying the ignition timing, and unburned gas burns in the exhaust passage, thereby producing a bubbling sound (explosion sound) as a type of driving sound effect.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-74885 Summary of the Invention

[0004] Bubbling sounds based on bubbling control are more likely to occur when the air-fuel ratio of the air-fuel mixture in the cylinder, i.e., the in-cylinder air-fuel ratio, is within a specified lean air-fuel ratio (a leaner air-fuel ratio than the stoichiometric air-fuel ratio) suitable for producing bubbling sounds.

[0005] In a V-type internal combustion engine where the firing order of the cylinders is unequal between the cylinder banks, a deviation in the amount of air is generated between the cylinders. If bubbling control is performed under these conditions, cylinders may sometimes be produced where the in-cylinder air-fuel ratio deviates from the lean air-fuel ratio range suitable for producing bubbling sounds. Therefore, it is possible to produce cylinders that do not produce sufficient sound effects, as described above.

[0006] The control device for solving the above-mentioned problems is applied to a V-type internal combustion engine in which the firing order of the cylinders is unequally spaced between the cylinder banks, and performs bubbling control when transitioning from accelerator on to accelerator off. This control device sets an appropriate range for the lean air-fuel ratio that produces the bubbling sound through the bubbling control, and, when performing the bubbling control, pre-sets the fuel injection quantity for each cylinder in a manner that ensures the in-cylinder air-fuel ratio falls within the appropriate range.

[0007] Invention Effects

[0008] The control unit of this V-type internal combustion engine can fully obtain the sound effect of motion when performing bubbling control. Attached Figure Description

[0009] Figure 1 This is a schematic diagram showing the cylinder arrangement of an internal combustion engine in one embodiment.

[0010] Figure 2 This is a schematic diagram showing the structure of the internal combustion engine and control device in this embodiment.

[0011] Figure 3 It is a graph showing the relationship between the cylinder air-fuel ratio and the number of bubbling combustion events in this embodiment, per cylinder.

[0012] Figure 4 This is a chart representing the correction factor for the fuel injection quantity in this embodiment, per cylinder.

[0013] Figure 5 This is a graph showing the cylinder air-fuel ratio before and after the correction of the fuel injection amount in this embodiment. Detailed Implementation

[0014] Hereinafter, an embodiment of the control device for a V-type internal combustion engine will be described with reference to the accompanying drawings.

[0015] <Cylinder Arrangement of Internal Combustion Engines>

[0016] like Figure 1 As shown, internal combustion engine 1 is a V-type internal combustion engine with 8 cylinders.

[0017] In the cylinder bank 1A of the internal combustion engine 1, four cylinders are connected in series: cylinder #1, cylinder #3, cylinder #5, and cylinder #7.

[0018] In the cylinder bank 1B of the internal combustion engine 1, four cylinders are connected in series: cylinder #2, cylinder #4, cylinder #6, and cylinder #8.

[0019] <Structure of Internal Combustion Engine and Control Device>

[0020] like Figure 2 As shown, in each cylinder of internal combustion engine 1 ( Figure 2 In the diagram (showing one cylinder), air is drawn into the combustion chamber 2 through the intake port 3a connected to the intake passage 3, and fuel injected from the fuel injection valve 4 is supplied to the combustion chamber 2. If the air-fuel mixture is ignited by the spark plug 5, the mixture burns and the piston 6 reciprocates, causing the crankshaft 7, which serves as the output shaft of the internal combustion engine 1, to rotate. In this embodiment, the crankshaft 7 has a cross-shaped plane. In an 8-cylinder V-type internal combustion engine with this cross-shaped crankshaft 7, the firing order of the cylinders is set to be unequal between the cylinder banks. That is, in the internal combustion engine 1, the firing order of the cylinders is: cylinder #1, cylinder #8, cylinder #7, cylinder #2, cylinder #4, cylinder #3, cylinder #6, and cylinder #5.

[0021] The mixture of gases after combustion in combustion chamber 2 is discharged as exhaust gas into exhaust passage 8. A catalyst 15 for purifying the exhaust gas is installed in exhaust passage 8.

[0022] A throttle valve 29 for measuring the amount of air drawn in is provided in the intake passage 3 of the internal combustion engine 1. The opening of the throttle valve 29 is adjusted by an electric motor.

[0023] An intake valve 9 is provided at the intake port 3a connected to the intake passage 3. An exhaust valve 10 is provided at the exhaust port 8a connected to the exhaust passage 8.

[0024] The control device 100 sets the internal combustion engine 1 as the controlled object, and operates the operating parts of the internal combustion engine 1, such as the throttle valve 29, fuel injection valve 4, and spark plug 5, in order to control the torque or exhaust gas composition ratio, which are the controlled quantities. Figure 1 The document contains the operating signals MS1 to MS3 for the throttle valve 29, fuel injection valve 4, and spark plug 5.

[0025] The control device 100 includes a memory 130 consisting of a CPU 120, ROM, RAM, etc. The CPU 120 performs various controls by executing programs stored in the memory 130.

[0026] When implementing various controls, the control device 100 references the output signal of the throttle position sensor 28, which detects the amount of throttle pedal 27 operated by the driver of the vehicle equipped with the internal combustion engine 1, i.e., the throttle operation amount ACCP. Furthermore, the control device 100 references the throttle valve opening degree TA, detected by the throttle valve sensor 30, and the intake air volume GA, detected by the air flow meter 31. Additionally, the control device 100 references the coolant temperature THW, detected by the coolant temperature sensor 33, and the engine speed NE, calculated from the output signal Scr of the crankshaft angle sensor 34. Finally, the control device 100 references the signal from the vehicle speed sensor 38, which detects the vehicle speed SP of the vehicle equipped with the internal combustion engine 1.

[0027] The control device 100 performs various mechanism controls based on the output signals from the aforementioned sensors, such as fuel injection control based on the fuel injection valve 4, intake air volume control based on the throttle valve 29, and ignition control based on the spark plug 5.

[0028] Bubble Control

[0029] The control device 100 performs bubble control to ensure good motion sound effects.

[0030] Bubbling control is a control performed when the accelerator pedal 27 changes from accelerator open to accelerator closed. When the accelerator pedal 27 changes to accelerator closed, the control device 100 does not immediately perform fuel cut-off control, but instead continues combustion of the air-fuel mixture under a significantly delayed ignition timing as bubbling control. That is, fuel continues to be injected from the fuel injection valve 4, and ignition of the air-fuel mixture based on the spark plug 5 continues under a significantly delayed ignition timing. Thus, by significantly delaying the ignition timing, the air-fuel mixture burns in a semi-misfire state, generating a bubbling sound, a type of sporty sound effect, from the exhaust passage 8, etc. Furthermore, the control ensures that the air-fuel ratio of the mixture during bubbling control is a lean air-fuel ratio, even leaner than the stoichiometric air-fuel ratio.

[0031] The aforementioned bubbling control ends after a predetermined time. Then, after the bubbling control ends, fuel cut-off control or idle speed control is implemented according to the engine operating status at that time.

[0032] As a prerequisite for allowing the bubbling control to be performed, for example, the following conditions (a) or (b) are set, and the control device 100 performs bubbling control when both conditions (a) and (b) are met.

[0033] (a): The temperature of catalyst 15 is within a specified range. For example, if the temperature of catalyst 15 exceeds this range and becomes high, the temperature of catalyst 15 may become too high if bubbling control is performed. Condition (a) is set to suppress such overheating of catalyst 15. In addition, the temperature of catalyst 15 can be based on the sensor's detection value or on a calculated inference value.

[0034] (b): The engine speed NE is within the specified range. For example, this is because performing bubbling control at a low engine speed NE may cause discomfort to vehicle occupants.

[0035] exist Figure 3 The diagram shows the relationship between the in-cylinder air-fuel ratio and the number of bubbling combustion events during bubbling control, categorized by cylinder. The in-cylinder air-fuel ratio is the air-fuel ratio of the air-fuel mixture within the cylinder. The number of bubbling combustion events refers to the number of combustion events that produce a bubbling sound within a specified period. Figure 3 This is represented using a bar chart. Furthermore, in... Figure 3 The value represented by the hollow circle is the average in-cylinder air-fuel ratio in each cylinder when bubbling control is implemented. Furthermore, Figure 3 The appropriate range AFb shown is the range of air-fuel ratios that easily produce bubbling combustion, and is a range of lean air-fuel ratios that are leaner than the stoichiometric air-fuel ratio. For example, the appropriate range AFb is an in-cylinder air-fuel ratio of approximately 16 to approximately 19.

[0036] In an 8-cylinder V-type internal combustion engine (i.e., internal combustion engine 1) where the firing order of the cylinders is unequal between the cylinder banks, a deviation in the amount of intake air occurs between the cylinders. If bubble control is performed under conditions that produce this deviation in the amount of intake air, cylinders may sometimes have an air-fuel ratio that deviates from the appropriate range AFb.

[0037] Here, the deviation in the amount of air intake between cylinders has an inherent tendency in internal combustion engines and can be determined in advance through prior experiments. Therefore, it is possible to predict in advance which cylinders will have an air-fuel ratio that deviates from the aforementioned appropriate range AFb.

[0038] For example, in the internal combustion engine 1 of this embodiment, when the fuel injection quantity during bubbling control in each cylinder is set to be the same, the in-cylinder air-fuel ratio of each cylinder tends to be from small to large values, namely, cylinder #5, cylinder #2, cylinder #4, cylinder #7, cylinder #1, cylinder #6, cylinder #8, and cylinder #3. Furthermore, the in-cylinder air-fuel ratios of cylinder #5, cylinder #2, and cylinder #4 are biased towards the rich side relative to the appropriate range AFb. The in-cylinder air-fuel ratios of cylinder #7, cylinder #1, and cylinder #6 are within the appropriate range AFb. Moreover, the in-cylinder air-fuel ratios of cylinder #8 and cylinder #3 are biased towards the lean side relative to the appropriate range AFb. Therefore, in cylinders other than #7 (cylinder 7), #1 (cylinder 1), and #6 (cylinder 6), combustion that produces a bubbling sound is unlikely to occur, and misfire is more likely to occur. Furthermore, if a misfire occurs, unburned fuel may be discharged into exhaust passage 8.

[0039] Therefore, in this embodiment, when performing bubbling control, the fuel injection amount of each cylinder is preset in a way that makes the air-fuel ratio in the cylinder within an appropriate range AFb.

[0040] That is, during the bubbling control, the control device 100 sets the fuel injection quantity Q(n) of the fuel injection valve 4 installed in each cylinder according to the following formula (1). In addition, "n" represents the number of each cylinder. In this embodiment, "n" is "1 to 8".

[0041] Fuel injection quantity Q(n) = reference value Qb × correction coefficient K(n) … (1)

[0042] The reference value Qb is a pre-set basic value for the fuel injection quantity Q(n) when bubbling control is performed. For example, the reference value Qb is the amount of fuel injected during idling operation that is equal to or less than that.

[0043] The correction factor K(n) is the value multiplied by the reference value Qb, preset for each cylinder. This correction factor K(n) is used to set the fuel injection quantity of each cylinder in a way that makes the in-cylinder air-fuel ratio within the appropriate range AFb when bubbling control is performed. When the correction factor K(n) is greater than 1, the fuel injection quantity Q(n) is increased relative to the reference value Qb; on the other hand, when the correction factor K(n) is less than 1, the fuel injection quantity Q(n) is decreased relative to the reference value Qb.

[0044] Therefore, for cylinders where the in-cylinder air-fuel ratio deviates from the appropriate range AFb towards the rich side, the greater the deviation towards the rich side, the smaller the value of the correction coefficient K(n) should be, so as to increase the amount of correction for the reduction in fuel injection quantity. On the other hand, for cylinders where the in-cylinder air-fuel ratio deviates from the appropriate range AFb towards the lean side, the greater the deviation towards the lean side, the larger the value of the correction coefficient K(n) should be, so as to increase the amount of correction for the increase in fuel injection quantity.

[0045] Figure 4 The correction coefficient K(n) for each cylinder is shown in the figure.

[0046] The correction coefficients K(n) for each cylinder are arranged from smallest to largest as follows: "K(5) < K(2) < K(4) < K(7) = K(1) = K(6) < K(8) < K(3)". The correction coefficients K(7), K(1), and K(6) are all set to "1", so in essence, no correction is performed on the fuel injection quantity, and the reference value Qb is directly set to the fuel injection quantity Q(n).

[0047] The correction coefficients K(5), K(2), and K(4) are all set to values ​​less than "1", so the fuel injection quantity Q(n) is reduced relative to the reference value Qb. Therefore, the air-fuel ratio in each cylinder of cylinder #5, cylinder #2, and cylinder #4 changes towards the lean side compared to before the fuel injection quantity was corrected.

[0048] On the other hand, both correction coefficients K(8) and K(3) are set to values ​​greater than "1", so the fuel injection quantity Q(n) is incrementally corrected relative to the reference value Qb. Therefore, the air-fuel ratio in each cylinder of cylinder #8 and cylinder #3 changes towards the surplus side compared to before the fuel injection quantity was corrected.

[0049] <The function of this implementation method>

[0050] In bubbling control, the fuel injection quantity Q(n) of each cylinder is set by multiplying the aforementioned correction coefficient K(n) for each cylinder individually by the reference value Qb. Therefore, the air-fuel ratio of each cylinder is as follows.

[0051] like Figure 5 As shown, for cylinders #5, #2, and #4, which have low air intake and tend to have air-fuel ratios that are biased towards the rich side relative to the appropriate range AFb, the fuel injection quantity Q(n) is reduced and corrected. Therefore, the air-fuel ratios in each cylinder of cylinders #5, #2, and #4 change towards the lean side compared to before the fuel injection quantity correction, becoming air-fuel ratios within the appropriate range AFb.

[0052] On the other hand, for cylinders #8 and #3, which have a large amount of air drawn into the cylinder and tend to have a lean air-fuel ratio relative to the appropriate range AFb, the corrected fuel injection quantity Q(n) is increased. Therefore, the air-fuel ratio in each cylinder of cylinders #8 and #3 changes towards the surplus side compared to before the fuel injection quantity correction, thus becoming a cylinder air-fuel ratio within the appropriate range AFb.

[0053] <Effects of this implementation method>

[0054] (1) When performing bubbling control, the fuel injection quantities of cylinders #5, #2, #4, #8, and #3 are preset for each cylinder to ensure that the air-fuel ratio in the cylinder is within the appropriate range AFb when bubbling control is performed. Therefore, bubbling sound is generated in each cylinder, thus fully obtaining motion sound effects when bubbling control is performed.

[0055] (2) Bubbling sounds are generated in each cylinder. Therefore, it is possible to suppress the discharge of unburned fuel that does not contribute to the generation of bubbling sounds into the exhaust passage 8.

[0056] <Example of Change>

[0057] Furthermore, the above-described implementation can be modified as follows. This implementation and the following modifications can be combined with each other within the scope of technical non-contradiction.

[0058] The correction factor K(n) is the value multiplied by the base value Qb. Alternatively, the correction factor K(n) can also be set as the value of addition or subtraction to the base value Qb.

[0059] • The reference value Qb is corrected by a correction factor K(n), and the fuel injection quantity Q(n) for each cylinder is set. Alternatively, the fuel injection quantity Q(n) for each cylinder can be set individually in advance. In this case, for example, the same value obtained by multiplying the reference value Qb by the correction factor K(n) can be preset as the fuel injection quantity Q(n) for each cylinder.

[0060] The control device 100 includes a CPU 120 and a memory 130, and is not limited to performing software processing. For example, it may include dedicated hardware circuitry (e.g., an ASIC) for processing at least a portion of the software processing performed in the above embodiments. That is, the control device 100 may be any of the following structures (a) to (c): (a) A processing device that executes all of the above processing according to a program and a program storage device such as a memory for storing the program. (b) A processing device that executes a portion of the above processing according to a program, a program storage device, and dedicated hardware circuitry for executing the remaining processing. (c) A dedicated hardware circuitry that executes all of the above processing. Here, there may be multiple software processing circuits or dedicated hardware circuits that include processing devices and program storage devices. That is, the above processing may be performed by a processing circuitry that includes at least one of one or more software processing circuits and one or more dedicated hardware circuits.

[0061] Symbol Explanation

[0062] 1-Internal combustion engine, 1A-Cylinder 1 bank, 1B-Cylinder 2 bank, 2-Combustion chamber, 3-Intake passage, 3a-Intake port, 4-Fuel injection valve, 5-Spark plug, 6-Piston, 7-Crankshaft, 8-Exhaust passage, 8a-Exhaust port, 9-Intake valve, 10-Exhaust valve, 15-Catalyst, 29-Throttle valve, 30-Throttle sensor, 31-Air flow meter, 33-Water temperature sensor, 34-Crankshaft angle sensor, 38-Vehicle speed sensor, 100-Control device, 120-CPU, 130-Memory.

Claims

1. A control device for a V-type internal combustion engine, applied to a V-type internal combustion engine in which the firing order of the cylinders is unequal between the cylinder banks, and performing bubble control when transitioning from accelerator on to accelerator off, characterized in that... Set the range of lean air-fuel ratios that produce the bubbling sound by controlling the bubbling as an appropriate range. When performing the bubbling control, the fuel injection amount of each cylinder is preset in a manner that makes the air-fuel ratio in the cylinder within the appropriate range.

2. The control device for a V-type internal combustion engine according to claim 1, characterized in that, When performing the bubbling control, the fuel injection quantity of each cylinder is set for each cylinder by multiplying a correction coefficient set for each cylinder by a preset reference value.

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