JP2024038826A - internal combustion engine system - Google Patents

Abstract

To prevent pump up when an exhaust switch valve has abnormality.SOLUTION: An internal combustion engine system comprises: an exhaust switch valve which is installed on an exhaust pipe of an internal combustion engine and changes an opening according to an air intake amount; and a control section which determines whether the exhaust switch valve has abnormality and executes air intake amount limiting control to limit the air intake amount when determining that the exhaust switch valve has abnormality. The control section determines that the exhaust switch valve has abnormality when a state where the opening of the exhaust switch valve is too large for the air intake amount lasts for a predetermined period. The control section also determines that the exhaust switch valve has abnormality when a valve opening sensor does not detect the opening that corresponds to an indicated value of the opening for the exhaust switch valve.SELECTED DRAWING: Figure 3

Description

The present invention relates to internal combustion engine systems.

Conventionally, there is a known technique for controlling an internal combustion engine based on the difference between a reference backpressure calculated from the amount of intake air detected by an airflow meter and an actual backpressure detected by an exhaust pressure sensor. For example, see Patent Document 1). Here, the back pressure is the pressure inside the exhaust pipe.

Japanese Patent Application Publication No. 11-190235

By the way, recently, internal combustion engines equipped with exhaust switching valves are known. The exhaust switching valve is opened when the internal combustion engine is operating in a high rotation range, allowing exhaust gas to escape more easily, making it easier to obtain output, and producing exhaust sound. On the other hand, the exhaust switching valve is closed when the vehicle is running at low speeds, such as in urban areas, thereby ensuring quietness when the vehicle is running.

However, if an abnormality occurs in such an exhaust switching valve, such as a valve opening sensor that detects its opening or a valve body that is stuck closed, back pressure increases. In particular, if an abnormality occurs in the exhaust switching valve and the back pressure increases when the internal combustion engine is in a high-speed, high-load state, pump-up may occur. Pump-up is a phenomenon in which the exhaust valve located upstream of the exhaust pipe and which opens and closes the combustion chamber becomes difficult to close. When pump-up occurs, sufficient compression within the cylinder of the internal combustion engine is not achieved, which worsens combustion conditions and reduces the performance of the internal combustion engine, and valve seals are exposed to high-temperature combustion heat and become susceptible to deterioration. There are things to do.

Therefore, an object of the invention disclosed in this specification is to suppress the occurrence of pump-up when an abnormality occurs in the exhaust switching valve.

The above problem involves an exhaust switching valve that is installed in an exhaust pipe and whose opening degree is changed depending on the amount of intake air, and a determination as to whether or not the exhaust switching valve is abnormal. This can be achieved by an internal combustion engine system including: a control section that performs intake air amount limiting control that limits the intake air amount using a throttle valve when it is determined that there is an abnormality.

In the above configuration, the control unit determines that the exhaust switching valve is abnormal when determining that the opening degree of the exhaust switching valve is too closed relative to the intake air amount for a predetermined period of time. It is possible to adopt a mode in which an abnormality determination is made.

Further, in the above configuration, the exhaust switching valve includes a valve opening sensor that detects the opening of the valve body, and the control unit adjusts the opening instruction value for the exhaust switching valve using the valve opening sensor. An embodiment may also be adopted in which, when a corresponding opening degree is not detected, it is determined that the exhaust switching valve is abnormal.

Furthermore, in the above configuration, when the control unit determines that warming up of the exhaust switching valve is not completed, the control unit determines whether or not the exhaust switching valve is abnormal and performs the intake air amount limiting control. This can be avoided.

Further, in the above configuration, when a vehicle diagnostic device is connected to the internal combustion engine, when the vehicle diagnostic device issues an opening instruction other than a fully open instruction for the exhaust switching valve, , the determination as to whether or not the exhaust gas switching valve is abnormal and the intake air amount restriction control may be avoided.

The invention disclosed in this specification can suppress the occurrence of pump-up when an abnormality occurs in the exhaust switching valve.

FIG. 1 is a schematic diagram showing a schematic configuration of an internal combustion engine according to an embodiment. FIG. 2 is a schematic diagram showing a schematic configuration of the exhaust switching valve of the embodiment. FIG. 3 is a flowchart showing an example of control of the internal combustion engine according to the embodiment. FIG. 4(A) is a diagram showing a state in which the exhaust switching valve is stuck in a closed state, and FIG. 4(B) is a diagram showing a state in which the exhaust switching valve is stuck in an intermediate opening state. 4(C) is a diagram showing a state in which the exhaust switching valve is over-opened. FIG. 5 is an example of a map for setting the determination opening degree of the exhaust switching valve at which pump-up is avoided in the internal combustion engine of the embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings. However, in the drawings, the dimensions, proportions, etc. of each part may not be shown to completely match the actual ones. Furthermore, some drawings may be drawn with details omitted.

(Embodiment)
[Internal combustion engine system configuration]
First, with reference to FIG. 1, a schematic configuration of an internal combustion engine system 100 according to an embodiment will be described. The internal combustion engine system 100 includes an internal combustion engine 1 that uses gasoline as fuel to obtain rotational driving force, a muffler 30 , a first muffler 31 , a second muffler 32 , and a third muffler 33 . The internal combustion engine system 100 further includes an ECU (Electronic Control Unit) 40 corresponding to a control section. The internal combustion engine 1 can use a conventionally known gasoline alternative fuel such as ethanol or natural gas instead of gasoline. Further, the internal combustion engine may be a diesel engine.

The internal combustion engine 1 includes a plurality of cylinders 2 in a cylinder block (only one cylinder 2 is shown in FIG. 1). A piston 3 is slidably housed in each cylinder 2, and the piston 3 forms a combustion chamber 2a between it and a cylinder head disposed above the cylinder block. The piston 3 is connected to a crankshaft 5 via a connecting rod 4. The combustion chamber 2a is provided with an injector 6 that injects fuel into the cylinder and a spark plug 7. The fuel injected from the injector 6 is made into an air-fuel mixture within the combustion chamber 2a, and is ignited by the ignition plug 7. The ignited mixture burns and explodes, pushing the piston 3 down. The depressed piston 3 transmits its explosive force to the crankshaft 5 via the connecting rod 4, causing the crankshaft 5 to rotate. Note that the injector 6 may be provided in the intake pipe 10 near the combustion chamber 2a.

The internal combustion engine 1 is provided with an intake port 8 and an exhaust port 9 facing the combustion chamber 2a, an intake pipe 10 is connected to the intake port 8, and an exhaust pipe 11 is connected to the exhaust port 9. ing.

The intake pipe 10 is provided with an air cleaner 12, an air flow meter 13, a throttle valve 17, and an intake manifold 18 in this order from the upstream side of the flow of intake air. The throttle valve 17 is provided with a throttle opening sensor 17a. The air flow meter 13 detects the amount of air flowing in the intake pipe 10, that is, the intake air amount GA. The throttle valve 17 adjusts the amount of air sent into the combustion chamber 2a. The throttle opening sensor 17a detects the opening of the throttle valve 17. The intake pipe 10 is branched at an intake manifold 18 and connected to the intake port 8 of each cylinder.

The exhaust pipe 11 is provided with an exhaust manifold 20 and a catalyst 21 in this order from the upstream side of the flow of exhaust gas. The catalyst 21 purifies exhaust gas. A muffler 30 is provided at the end of the exhaust pipe 11. The exhaust pipe 11 branches into a first muffler 31 , a second muffler 32 , and a third muffler 33 inside the muffler 30 . The first muffler 31 and the second muffler 32 are branched left and right along the longitudinal direction of the muffler 30. The third muffler 33 extends between the first muffler 31 and the second muffler 32.

The third muffler 33 is provided with an exhaust switching valve 34. The exhaust switching valve 34 is provided with a valve opening sensor 35 that detects the opening of the exhaust switching valve 34.

Here, with reference to FIG. 2, a schematic configuration of the exhaust switching valve 34 will be described. The exhaust switching valve 34 includes a housing portion 34a having an opening 34a1, and a valve body 34b rotatably provided to open and close the opening 34a1. The valve opening direction of the valve body 34b is a clockwise direction, and the valve closing direction of the valve body 34b is a counterclockwise direction. The valve opening sensor 35 shown in FIG. 1 detects the rotation angle of the valve body 34b as its opening degree.

The internal combustion engine 1 includes an intake valve 23 that opens and closes the intake port 8 and an exhaust valve 24 that opens and closes the exhaust port 9. The intake valve 23 is provided so as to be slidable with respect to the valve guide 23a. The valve guide 23a is provided with a valve seal 23b. The exhaust valve 24 is provided so as to be slidable with respect to the valve guide 24a. The valve guide 24a is provided with a valve seal 24b. The intake valve 23 and the exhaust valve 24 open and close in accordance with the rotation of an intake camshaft and an exhaust camshaft (not shown) which are drivingly connected to the crankshaft 5. Thereby, the intake valve 23 and the exhaust valve 24 are driven to open and close at predetermined timing in synchronization with the rotation of the crankshaft 5 and in response to the reciprocating movement of each piston 3. The internal combustion engine 1 includes an intake VVT mechanism 25 that is a variable valve mechanism that variably sets the valve timing that is the opening and closing timing of the intake valve 23, and a variable valve mechanism that variably sets the valve timing that is the opening and closing timing of the exhaust valve 24. A certain exhaust VVT mechanism 26 is provided. The intake VVT mechanism 25 and the exhaust VVT mechanism 26 form a variable valve timing device.

The internal combustion engine 1 includes a water jacket (not shown) in which cooling water circulates. The internal combustion engine 1 includes a water temperature sensor 71 that detects the temperature of cooling water circulating within the water jacket.

The ECU 40 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a storage device, and the like. ECU 40 controls internal combustion engine system 100 by executing programs stored in ROM or storage device. The ECU 40 is electrically connected to the air flow meter 13, the throttle opening sensor 17a, the valve opening sensor 35, and the water temperature sensor 71, and receives signals from these sensors. Further, the ECU 40 is electrically connected to the throttle valve 17, the intake VVT mechanism 25, the exhaust VVT mechanism 26, and the exhaust switching valve 34, and sends signals to these to control their operations. Furthermore, the ECU 40 has a timekeeping function. In addition to these, various sensors for controlling the internal combustion engine system 100 are electrically connected to the ECU 40, but a detailed explanation thereof will be omitted here.

Note that a vehicle diagnostic device 80 may be connected to the ECU 40, for example, in a repair shop or the like. Vehicle diagnostic device 80 can arbitrarily set the state of each part included in internal combustion engine system 100 in order to confirm the state of the vehicle. The vehicle diagnostic device 80 can set the exhaust switching valve 34 to an arbitrary opening degree. At this time, the vehicle diagnostic device 80 can set the opening degree of the exhaust switching valve 34 separately from the intake air amount GA, that is, separately from the intake air amount GA.

In a normal state where the vehicle diagnostic device 80 is not connected, the ECU 40 controls the opening degree of the exhaust switching valve 34 based on the intake air amount GA detected by the air flow meter 13. The exhaust gas switching valve 34 is controlled so that its opening degree increases as the intake air amount GA increases. However, if the exhaust switching valve 34 is abnormal, the opening degree of the exhaust switching valve 34 according to the intake air amount GA cannot be guaranteed, and in some cases, the exhaust valve 24 may fail to close, which may result in so-called pump-up. There is sex. Pump-up is thought to occur when the exhaust switching valve 34 is closed and the back pressure, which is the pressure inside the exhaust pipe 11, increases. When pump-up occurs, compression within the cylinder may not be sufficient, which may deteriorate the combustion state in the combustion chamber 2a, or the valve seal 24b may be exposed to high-temperature combustion heat and become susceptible to deterioration.

[Pump-up avoidance control]
In the following description, control for avoiding pump-up when the exhaust gas switching valve 34 including the valve opening sensor 35 is determined to be abnormal will be described with reference to the flowchart shown in FIG. 3. The flowchart shown in FIG. 3 includes a determination as to whether the exhaust switching valve 34 is abnormal, and a process to be performed when the state in which the exhaust switching valve 34 is determined to be abnormal continues for a predetermined period of time. Includes intake air amount limit control.

In step S1, the ECU 40 determines whether the internal combustion engine system 100 is being forcedly driven by the vehicle diagnostic device 80. When the vehicle diagnostic device 80 is connected to the ECU 40 and vehicle diagnosis is being performed, the control by the vehicle diagnostic device 80 is given priority over the control of the ECU 40 for the internal combustion engine system 100. For example, assume that the vehicle diagnostic device 80 is connected to the internal combustion engine system 100 and the accelerator of the vehicle is depressed. At this time, the opening degree of the exhaust switching valve 34 determined by the vehicle diagnostic device 80 is an intermediate opening degree such as 20 degrees, and on the other hand, the opening degree of the exhaust switching valve 34 corresponding to the intake air amount GA due to the depression of the accelerator is determined by the vehicle diagnostic device 80. Assume that it is higher than the set value by . In such a case, since the valve opening sensor 35 detects the opening set by the vehicle diagnostic device 80, there will be a discrepancy with the opening of the exhaust switching valve 34 according to the intake air amount GA, resulting in an erroneous determination. There is a possibility that Therefore, in such a case, in principle, the exhaust switching valve 34 including the valve opening sensor 35 is not determined to be abnormal in order to avoid erroneous determination. When the ECU 40 makes an affirmative determination (Yes determination) in step S1, the process proceeds to step S2, and when a negative determination (no determination) is made, the process proceeds to step S3.

In step S2, the ECU 40 determines whether the vehicle diagnostic device 80 has issued a fully open instruction to the exhaust switching valve 34. When the ECU 40 makes a negative determination in step S2, the ECU 40 returns the process. When the ECU 40 makes an affirmative determination in step S2, the process proceeds to step S4. The reason for performing the determination in step S2 is that when the exhaust gas switching valve 34 is fully open by the vehicle diagnostic device 80, abnormality detection can be performed while avoiding erroneous detection of the exhaust gas switching valve 34. As will be described in detail later, the state in which the exhaust switching valve 34 is determined to be abnormal is the state in which the actual valve opening degree A becomes smaller than the determined opening degree AZ (see step S9). This is because when an abnormality occurs in which the exhaust switching valve 34 is stuck in the closed state, back pressure increases and pump-up is likely to occur. If the exhaust switching valve 34 is stuck and the vehicle diagnostic device 80 indicates the opening of the exhaust switching valve 34 to be fully open, the exhaust switching valve 34 will open more than the instructed opening. It is thought that it is stuck in the closed state. In other words, this corresponds to the mode to be detected in this embodiment. Therefore, in such a case, control proceeds to step S4 and subsequent steps.

In step S3, the ECU 40 determines whether the engine water temperature T is equal to or higher than the determination water temperature TZ. For example, if the vehicle is placed in a low-temperature environment and the exhaust switching valve 34 is frozen, this may occur even though there is no actual abnormality in the exhaust switching valve 34. There is a possibility that an erroneous determination that an abnormality has occurred in 34 may occur. Therefore, when the ECU 40 determines that the engine coolant temperature T is lower than the determined coolant temperature TZ, that is, the warm-up has not been completed, the ECU 40 determines whether or not the exhaust switching valve 34 is abnormal and controls the intake air as described later. Amount restriction control (see step S7) is avoided. Engine water temperature T is detected by water temperature sensor 71. The determination water temperature TZ is a water temperature that is set in advance through simulation or actual machine adaptation as a value at which it can be determined that the internal combustion engine 1 has warmed up and the exhaust switching valve 34 is not frozen. In this embodiment, the warm-up determination is made based on the water temperature, but the warm-up determination may be made using other parameters that have a correlation with the water temperature, such as oil temperature or other temperatures. Good too.

If the ECU 40 makes a negative determination in step S3, the ECU 40 returns the process. When the ECU 40 makes an affirmative determination in step S3, the process proceeds to step S4.

In step S4, the ECU 40 determines whether the opening of the exhaust switching valve 34 detected by the valve opening sensor 35 is the opening commanded by the ECU 40. Step S4 is one of the abnormality determinations. This is performed in order to determine whether or not an abnormality has occurred in the valve opening sensor 35. The ECU 40 issues an opening command to the exhaust switching valve 34 according to the intake air amount GA. On the other hand, if the opening of the exhaust switching valve 34 detected by the valve opening sensor 35 is different from the opening commanded by the ECU 40, it is suspected that an abnormality has occurred in the valve opening sensor 35. . If an abnormality occurs in the valve opening sensor 35, the state of the exhaust switching valve 34 cannot be accurately determined. In this case, depending on the state of the exhaust switching valve 34, the back pressure may increase and pump-up may occur. Note that if the determination in step S4 is made via step S2, the full open instruction by the vehicle diagnostic device 80 is determined to be the opening degree commanded by the ECU 40.

Here, as a mode of abnormality of the valve opening degree sensor 35, a mode in which the detected value is higher than the actual opening degree is assumed. In this case, the ECU 40 attempts to control the exhaust switching valve 34 to the closed side based on the detected value. As a result, it is assumed that the exhaust switching valve 34 is in a state where the valve body 34b closes the opening 34a1, as illustrated in FIG. 4A. In this case, back pressure may increase and pump-up may occur.

On the other hand, as a mode of abnormality in the valve opening degree sensor 35, a mode in which the detected value is lower than the actual opening degree is assumed. In this case, the ECU 40 attempts to control the exhaust switching valve 34 to the open side based on the detected value. As a result, it is assumed that the exhaust switching valve 34 is in a state where the valve body 34b closes the opening 34a1, as illustrated in FIG. 4C. In this case, back pressure may increase and pump-up may occur.

However, even if such a situation is observed, it does not mean that a pump-up will occur immediately. In other words, when pump-up occurs, it takes time for the back pressure to actually rise, and it is assumed that the determination that the valve opening sensor 35 is abnormal may be resolved by the time the back pressure rises. . Therefore, the ECU 40 determines whether or not the state in which the opening degree according to the opening degree command is not detected continues for a predetermined period of time by processing in steps S5 and S6 described below.

When the ECU 40 makes a negative determination in step S4, the process proceeds to step S5. Then, the ECU 40 starts counting the duration H1 in step S5. In step S6, the ECU 40 determines whether the duration H1 is equal to or longer than the determination time H1Z. The determination time H1Z is a period set in advance by simulation or actual machine adaptation as a period during which pump-up is considered to occur due to continued abnormality in the exhaust gas switching valve 34.

If the ECU 40 makes a negative determination in step S6, the ECU 40 returns the process. When the ECU 40 makes an affirmative determination in step S6, the process proceeds to step S7.

In step S7, the ECU 40 adjusts the opening of the throttle valve to limit the amount of intake air. Pump-up is more likely to occur as the internal combustion engine 1 becomes more loaded and rotated at higher speeds. Therefore, in step S7, the amount of intake air is limited to avoid a situation of high load and high rotation, and to suppress an increase in back pressure. This avoids pump-up. By avoiding pump-up, deterioration of the combustion state in the combustion chamber 2a is avoided, and the valve seal 24b is prevented from being exposed to high-temperature combustion heat and becoming susceptible to deterioration.

When the ECU 40 makes an affirmative determination in step S4, the process proceeds to step S8. The ECU 40 resets the duration H1 in step S8, and proceeds to step S9. In step S9, the ECU 40 determines the determination opening degree AZ of the exhaust switching valve 34 according to the intake air amount GA detected by the air flow meter 13. The ECU 40 determines the determined opening degree AZ based on the map illustrated in FIG. 5 . The horizontal axis of the map illustrated in FIG. 5 is the intake air amount GA, and the vertical axis is the determined opening degree AZ. The determined opening degree AZ increases as the intake air amount GA increases. In the map illustrated in Figure 5, the area below the hatched solid line is set as an area where pump-up may occur, and the area above the solid line is where pump-up may occur. It is set in an area where there is no such occurrence or the possibility of it occurring is low.

In step S10, which is performed subsequent to step S9, the ECU 40 determines whether the valve opening degree A is smaller than the determination opening degree AZ. Step S10 is one of the abnormality determinations. Here, the valve opening degree A is a value detected by the valve opening degree sensor 35. As mentioned above, since there is a possibility of pumping up in the hatched area in the map shown in FIG. 5, the valve opening degree A and A comparison may be made with the determined opening degree AZ. When the area is above the solid line in the map shown in FIG. 5, the process may be returned.

Here, the assumed state of the exhaust gas switching valve 34 when an affirmative determination is made in step S10 will be described. In the case where an affirmative determination is made in step S10, it is assumed that the exhaust switching valve 34 is stuck in a closed state due to a malfunction of the actuator that drives the valve body 34b or due to foreign matter being caught in the valve body 34b. . For example, as illustrated in FIG. 4A, if the valve body 34b is stuck in the closed state, an affirmative determination is made in step S10. Furthermore, as illustrated in FIG. 4B, even if the opening is stuck at an intermediate opening, an affirmative determination may be made in step S10 depending on the relationship with the intake air amount GA.

If the ECU 40 makes an affirmative determination in step S10, the process proceeds to step S11, and if the ECU 40 makes a negative determination, the process proceeds to step S12.

In step S11, the ECU 40 starts counting the duration H2 of the state in which the affirmative determination was made in step S10, and proceeds to step S13. On the other hand, the ECU 40 resets the duration H2 in step S12, and proceeds to step S13. In step S13, the ECU 40 determines whether the duration time H2 is equal to or longer than the determination time H2Z. The determination time H2Z is a period set in advance by simulation or actual machine adaptation as a period during which pump-up is considered to occur due to continued abnormality in the exhaust gas switching valve 34. In addition, in this way, when it is determined that the state in which the opening degree of the exhaust switching valve 34 is too open relative to the intake air amount continues for a predetermined period, it is determined that the exhaust switching valve 34 is abnormal. The reason for doing this is as follows. Even if the exhaust switching valve 34 is observed to be too open, pumping up will not occur immediately; it will take time for the back pressure to actually rise, and the situation will improve before the back pressure rises. This is due to consideration of these factors.

When the ECU 40 makes a negative determination in step S13, the ECU 40 returns the process. When the ECU 40 makes an affirmative determination in step S13, the process proceeds to step S7.

The ECU 40 limits the amount of intake air in step S7. Since step S7 has already been explained, detailed explanation thereof will be omitted here. After the process of step S7 is executed, the process returns.

According to the internal combustion engine system of this embodiment, when it is determined that the exhaust switching valve 34 is abnormal, intake air amount restriction control is performed to limit the intake air amount. This avoids pump-up.

The above-mentioned embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications to these embodiments are within the scope of the present invention, and furthermore, it is within the scope of the present invention. It is obvious from the above description that various other embodiments are possible within the scope.

1 Internal combustion engine 8 Intake port 9 Exhaust port 10 Intake pipe 11 Exhaust pipe 18 Intake manifold 20 Exhaust manifold 21 Catalyst 23 Intake valve 24 Exhaust valve 25 Intake VVT mechanism 26 Exhaust VVT mechanism 30 Silencer 31 First muffler 32 Second muffler 33 3 Muffler 34 Exhaust switching valve 35 Valve opening sensor 40 ECU 80 Vehicle diagnostic device 100 Internal combustion engine system

Claims (5)

an exhaust switching valve that is provided in an exhaust pipe of an internal combustion engine and whose opening degree is changed according to the amount of intake air;
A control that determines whether or not the exhaust switching valve is abnormal, and when it is determined that the exhaust switching valve is abnormal, performs intake air amount limiting control that limits the intake air amount using a throttle valve. Department and
An internal combustion engine system with The control unit determines that the exhaust switching valve is abnormal when determining that the opening degree of the exhaust switching valve is too closed relative to the intake air amount for a predetermined period of time. do,
The internal combustion engine system according to claim 1. The exhaust switching valve includes a valve opening sensor that detects the opening of the valve body,
The control unit determines that the exhaust switching valve is abnormal when the valve opening sensor does not detect an opening corresponding to an instruction value of the opening for the exhaust switching valve.
The internal combustion engine system according to claim 1 or 2. When the control unit determines that warming up of the exhaust switching valve is not completed, the controller avoids determining whether or not the exhaust switching valve is abnormal and avoiding the intake air amount restriction control.
The internal combustion engine system according to claim 1. In the case where a vehicle diagnostic device is connected to the internal combustion engine, the control unit controls the exhaust switching valve to open when the vehicle diagnostic device issues an opening instruction other than a fully open instruction for the exhaust switching valve. determining whether or not there is an abnormality and avoiding the intake air amount limiting control;
The internal combustion engine system according to claim 1.

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