JP2023034784A - Egr valve control device - Google Patents

Abstract

To provide an EGR valve control device capable of early determining whether or not an EGR valve is jammed with a foreign matter.SOLUTION: An EGR valve control device which controls opening and closing operation of an EGR valve, arranged in an EGR passage of an internal combustion engine, using a drive duty ratio of the EGR valve comprises: a control section which performs feedback control of the drive duty ratio through calculating at least an integral term on the basis of a deviation of an actual opening from a target opening when the actual opening of the EGR valve is equal to or larger than a predetermined opening other than a full closure; and a determination section which determines that the EGR valve is jammed with a foreign matter when the drive duty ratio becomes equal to or larger than an upper limit value while the feedback control is in execution with the full closure of the EGR valve requested. The control section sets the target opening smaller than the predetermined opening when the full closure of the EGR valve is requested.SELECTED DRAWING: Figure 8

Description

The present invention relates to an EGR valve control device.

An EGR valve arranged in an EGR passage of an internal combustion engine is known (see Patent Document 1, for example).

WO2008/081643

If such a foreign matter gets caught in the EGR valve, the EGR valve cannot be fully closed. In particular, if the foreign matter is large, it may affect the operating state of the internal combustion engine. Therefore, it is desirable to quickly determine whether a foreign object is caught in the EGR valve.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an EGR valve control device capable of quickly determining whether or not a foreign object is caught in the EGR valve.

The above object is to provide an EGR valve control device for controlling the opening/closing operation of the EGR valve by controlling the drive duty ratio of the EGR valve arranged in the EGR passage of an internal combustion engine, in which the actual opening degree of the EGR valve is fully controlled. a control unit for feedback-controlling the drive duty ratio by calculating at least an integral term based on the deviation between the actual opening and the target opening when the opening is equal to or greater than a predetermined opening other than the closed EGR valve; a determination unit that determines that foreign matter is caught in the EGR valve when the drive duty ratio becomes equal to or greater than an upper limit value during execution of the feedback control upon request, wherein the control Part can be achieved by an EGR valve control device that sets the target degree of opening to a value smaller than the predetermined degree of opening when there is a request to fully close the EGR valve.

Advantageous Effects of Invention According to the present invention, it is possible to provide an EGR valve control device capable of quickly determining whether or not a foreign object is caught in the EGR valve.

FIG. 1 is a schematic configuration diagram of the engine system of this embodiment. 2A and 2B are schematic configuration diagrams of the EGR valve. FIG. 3 is an explanatory diagram of control of the drive duty ratio in the EGR valve. FIG. 4 is an explanatory diagram of a case where a foreign matter F is caught in the EGR valve. FIG. 5 is an explanatory diagram of F/B control in a comparative example and this embodiment. FIG. 6 is a timing chart showing changes in the actual opening degree and the drive duty ratio by F/B control in the comparative example and the present embodiment when foreign matter is caught. FIG. 7 is a graph showing the relationship between the time from when the actual opening is limited to the foreign object opening until the driving duty ratio becomes -100% and the deviation in the F/B control. FIG. 8 is a flowchart showing an example of foreign object jamming control executed by the ECU.

[Schematic configuration of engine system]
FIG. 1 is a schematic configuration diagram of the engine system of this embodiment. The engine 20 is an example of an internal combustion engine, and is an in-line four-cylinder gasoline engine having four cylinders, but is not limited to this, and may be a diesel engine, for example. Also, the engine 20 may be an engine with a supercharger. In the engine 20, the air-fuel mixture is combusted in the combustion chamber 23 in the cylinder head 22 installed on the cylinder block 21 in which the piston 24 is housed, and the piston 24 is reciprocated. Reciprocating motion of the piston 24 is converted into rotational motion of the crankshaft 26 . An oil pan 21a that stores lubricating oil is provided in the lower portion of the cylinder block 21 .

In the cylinder head 22 of the engine 20, an intake valve 42 for opening and closing the intake port 10i and an exhaust valve 44 for opening and closing the exhaust port 30e are provided for each cylinder. A spark plug 27 for igniting the air-fuel mixture in the combustion chamber 23 is attached to the top of the cylinder head 22 for each cylinder. The cylinder head 22 is also provided with an in-cylinder injection valve 12 that injects fuel into the combustion chamber 23 . When the intake valve 42 is open, the intake air drawn into the combustion chamber 23 and the fuel injected from the in-cylinder injection valve 12 are mixed to form an air-fuel mixture. It is ignited and burned.

The intake port 10i of each cylinder is connected to a surge tank 18 via a branch pipe for each cylinder. An intake pipe 10 is connected to the upstream side of the surge tank 18 , and an air cleaner 19 is provided at the upstream end of the intake pipe 10 . The intake pipe 10 is provided with an airflow meter 15 for detecting the amount of intake air and an electronically controlled throttle valve 13 in order from the upstream side. The surge tank 18 is also provided with an intake pressure sensor 17 for detecting the intake pressure.

The exhaust port 30e of each cylinder is connected to the exhaust pipe 30 via a branch pipe for each cylinder. A three-way catalyst 31 is provided in the exhaust pipe 30 . An air-fuel ratio sensor 33 for detecting the air-fuel ratio of the exhaust gas is installed upstream of the three-way catalyst 31 .

An EGR pipe 50 that communicates the exhaust pipe 30 and the intake pipe 10 is provided. The EGR pipe 50 is provided with an EGR valve 52 whose opening degree can be adjusted. By opening the EGR valve 52, part of the exhaust gas is recirculated to the intake pipe 10, and by adjusting the opening of the EGR valve 52, the ratio of the amount of EGR gas to the total amount of intake gas taken into the combustion chamber 23 is reduced. The EGR rate, which is a ratio, can be adjusted. The EGR pipe 50 may be provided with an EGR cooler.

The ECU (Electronic Control Unit) 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a backup RAM, and the like. The ROM stores various control programs, maps to be referred to when executing the various control programs, and the like. The CPU executes arithmetic processing based on various control programs and maps stored in the ROM. In addition, the RAM is a memory that temporarily stores the calculation results of the CPU and the data input from each sensor, etc., and the backup RAM is a non-volatile memory that stores data that should be saved when the ignition is turned off. . The CPU, ROM, RAM, and backup RAM functionally implement a control unit and a determination unit, which will be described later in detail.

The ignition plug 27 , throttle valve 13 , in-cylinder injection valve 12 and EGR valve 52 are electrically connected to the ECU 100 . The ECU 100 also includes an accelerator opening sensor 11 for detecting the accelerator opening, a throttle opening sensor 14 for detecting the throttle opening of the throttle valve 13, an airflow meter 15, an intake pressure sensor 17, and a crankshaft 26 for detecting the crank angle. A crank angle sensor 25, an air-fuel ratio sensor 33, and various other sensors are electrically connected. The ECU 100 controls the spark plug 27, the throttle valve 13, the in-cylinder injection valve 12, the EGR valve 52, etc., based on the values detected by various sensors, etc., to obtain a desired output. , fuel injection timing, throttle opening, EGR rate, and the like.

[Schematic configuration of EGR valve]
Next, a schematic configuration of the EGR valve 52 will be described. 2A and 2B are schematic configuration diagrams of the EGR valve 52. FIG. FIG. 2A shows the EGR valve 52 in a fully closed state, and FIG. 2B shows the EGR valve 52 in a fully open state. The EGR valve 52 includes a valve body 53 , a valve seat 54 , a motor 55 , a spring 56 and a position sensor 57 . The valve body 53 is provided so as to be seatable and movable with respect to a valve seat 54 arranged inside the EGR pipe 50 . A spring 56 urges the valve body 53 in a direction to be seated on the valve seat 54 .

The motor 55 is a DC (Direct Current) motor and displaces the valve body 53 in the opening/closing direction. Specifically, when the drive duty ratio of a PWM (Pulse Width Modulation) signal is given from the ECU 100 to the drive circuit of the motor 55, electric power corresponding to the drive duty ratio is supplied to the coils of the motor 55, and the coils of the motor 55 are supplied with power corresponding to the drive duty ratio. A motor driving current flows in the valve opening direction or the valve closing direction. As a result, the valve body 53 moves to the opening side or the closing side. Specifically, the drive duty ratio is set between +100% and -100%. When the drive duty ratio has a positive value, a force acts on the valve body 53 in the valve opening direction, and when it has a negative value, a force acts on the valve body 53 in the valve closing direction.

The position sensor 57 outputs a detection signal corresponding to the position of the valve body 53 , in other words, a detection value corresponding to the opening of the EGR valve 52 to the ECU 100 , and the ECU 100 obtains the actual opening of the EGR valve 52 .

FIG. 3 is an explanatory diagram of control of the drive duty ratio in the EGR valve 52. As shown in FIG. A section in which the opening degree of the EGR valve 52 is 100% (fully open) or less and is equal to or greater than the switching opening degree SD is referred to as a F/B control section in which feedback control (hereinafter referred to as F/B control) is executed. A section in which the opening degree of the EGR valve 52 is less than the switching opening degree SD to 0% (fully closed) is referred to as a seating control section in which the seating control is performed. When the actual opening belongs to the F/B control section, the drive duty ratio is F/B controlled by PID (Proportional Integral Differential) control so that the deviation between the actual opening and the target opening is eliminated. F/B control is a control for accurately matching the actual opening with the target opening. When there is a request to fully close the EGR valve 52 and the actual opening belongs to the seating control section, the drive duty ratio is controlled to increase or decrease in a predetermined order regardless of the actual opening. be. The seating control mitigates impact when the valve body 53 is seated on the valve seat 54 when there is a request to fully close the EGR valve 52 , suppresses collision noise, and prevents wear of the valve seat 54 and damage to the valve body 53 . This is a control for preventing fatigue fracture of engaging parts (for example, gears of the motor 55). The switching opening SD is the opening at which the F/B control is switched to the seating control as described above, and is set to an opening of less than 50%, for example. The switching opening SD is an example of a predetermined opening.

ECU 100 calculates the target opening according to the operating state of engine 20 . Here, the target opening is calculated within a range of 100% or less. In addition, the ECU 100 requests full closing of the EGR valve 52 to 0%, depending on the operating state of the engine 20 . When there is a request to fully close, instead of setting the target opening used in the F/B control described above to 0%, a predetermined provisional target opening that is a value other than 0%, which will be described later, is set. Set to the target opening in F/B control.

For example, when there is a full-close request while the actual opening belongs to the F/B control section, the target opening is set to the provisional target opening and the F/B control described above is executed. As a result, when the actual opening becomes less than the switching opening SD, the seating control described above is executed. Note that when there is no full-close request with a target opening other than 0, regardless of the actual opening, in other words, even if the actual opening is less than the switching opening SD, the above-described F/B control is executed.

[Foreign matter caught in the EGR valve]
Next, clogging of foreign matter in the EGR valve 52 will be described. FIG. 4 is an explanatory diagram of a case where foreign matter F is caught in the EGR valve 52. As shown in FIG. Foreign matter F is caught between the valve body 53 and the valve seat 54 when the valve body 53 moves from the valve open state in which the valve body 53 is separated from the valve seat 54 to the valve closed state in which the valve body 53 is seated on the valve seat 54 . there is a possibility. As shown in FIG. 4 , when a foreign object F gets caught between the valve body 53 and the valve seat 54 , a gap is created between the valve body 53 and the valve seat 54 . Therefore, the EGR pipe 50, which should be closed originally, may be in a communicating state due to this gap.

If such foreign matter is large, for example, during low-load operation, the exhaust pressure is higher than the intake pressure, so EGR gas may flow excessively through the intake pipe 10 and sufficient fresh air may not be supplied to the combustion chamber 23 . In the case of a supercharged engine and a supercharged EGR system that recirculates exhaust gas from upstream of the turbo to downstream of the compressor, the intake pressure is higher than the exhaust pressure during high load operation. There is a risk that the three-way catalyst 31 will be overheated due to excessive supply to the three-way catalyst 31 via the . Therefore, it is desired to determine the presence of such a foreign object at an early stage.

FIG. 5 is an explanatory diagram of F/B control in a comparative example and this embodiment. In FIG. 5, the degree of opening restricted by the foreign matter F is referred to as foreign matter opening degree FD. Also, FIG. 5 shows the case where the actual opening belongs to the F/B control section and there is a full-close request. The foreign object opening degree FD is larger than the switching opening degree SD. In the comparative example, the provisional target opening degree TDx set as the target opening degree in the F/B control when there is a full-close request matches the switching opening degree SD. On the other hand, in this embodiment, the provisional target opening TDe set as the target opening in the F/B control when there is a request for full closing is smaller than the switching opening SD. That is, in the comparative example, when the foreign matter F does not exist, when the actual opening becomes the switching opening SD, the deviation between the actual opening and the provisional target opening TDx becomes 0, and the F/B control shifts to the seating. switch to control. In this embodiment, when the foreign matter F does not exist, even if the actual opening becomes the switching opening SD, the F/ The B control is switched to the seating control.

If a foreign object F exists, the actual opening is limited to the foreign object opening FD. In this state, the difference between the actual opening (foreign object opening FD) and the provisional target opening TDe in this embodiment is greater than the deviation between the actual opening (foreign object opening FD) and the provisional target opening TDx in the comparative example. deviation is larger.

FIG. 6 is a timing chart showing changes in the actual opening degree and the driving duty ratio by F/B control in the comparative example and the present embodiment when foreign matter F is caught. When there is a full-close request at time t0, F/B control is executed based on the provisional target opening degree TDx in the comparative example, and F/B control is executed based on the provisional target opening degree TDe smaller than the provisional target opening degree TDx in the present embodiment. /B control is executed. Therefore, as described above, the deviation is larger in this embodiment than in the comparative example, and the rate of decrease in the actual opening is faster in this embodiment than in the comparative example. Therefore, at time t1, the actual opening of the present embodiment becomes the foreign object opening FD first, and at time t2, the actual opening of the comparative example becomes the foreign object opening FD. Further, in this embodiment, since the deviation is constant after time t1, the integral term increases and the drive duty ratio increases in the negative direction, reaching a maximum of -100% at time t3. Similarly, in the comparative example, since the deviation is constant after time t2, the integral term increases and the driving duty ratio increases in the negative direction, reaching a maximum of -100% at time t4. Here, as described above, since the deviation is larger in this embodiment than in the comparative example, the drive duty ratio in this embodiment reaches −100% earlier than in the comparative example.

FIG. 7 shows the relationship between the time [ms] from when the actual opening is limited to the foreign object opening FD until the drive duty ratio becomes -100%, and the deviation "%" in F/B control. graph. The vertical axis indicates time and the horizontal axis indicates deviation. In the example of FIG. 6, the above time corresponds to the time from time t2 to time t4 in the comparative example, and corresponds to the time from time t1 to time t3 in the present embodiment. As shown in FIG. 7, the larger the deviation, the shorter the above time.

Here, there are the following methods for determining whether or not the foreign matter F is caught. The ECU 100 determines that the foreign matter F is caught when the drive duty ratio is equal to or higher than the upper limit value, here -100%, when the full-close request is issued, and this state continues for a predetermined time or longer. do. As described above, in this embodiment, the time from when the actual opening is restricted by a foreign object to when the drive duty ratio reaches -100% is shorter than in the comparative example, and the drive duty ratio reaches -100% first. Become. Therefore, it is possible to determine that the foreign matter F has become caught in the present embodiment earlier than in the comparative example.

[Foreign matter entrapment determination control]
Next, an example of foreign matter jam determination control executed by the ECU 100 will be described. FIG. 8 is a flow chart showing an example of foreign matter jam determination control executed by the ECU 100. As shown in FIG. The ECU 100 determines whether or not there is a fully closed request (step S1). If No in step S1, the target opening is set to an opening within a range of 100% or less according to the operating state of the engine 20 (step S3), and F/B control is executed (step S6). . If Yes in step S1, a provisional target opening degree TDe smaller than the switching opening degree SD is set as the target opening degree in the F/B control as described above (step S2). Step S2 is an example of processing executed by the control unit.

Next, the ECU 100 determines whether or not the actual opening is less than the switching opening SD based on the detection value of the position sensor 57 (step S4). If Yes in step S4, the ECU 100 executes seating control (step S5). If No in step S4, F/B control is executed (step S6). Step S6 is an example of control executed by the control unit.

Next, the ECU 100 determines whether or not a foreign object is caught (step S7). Specifically, during the continuation of the F/B control, the ECU 100 determines that a foreign object is caught when a predetermined time has passed since the drive duty ratio became -100% as described above. be done. During the continuation of the seating control, if the actual degree of opening detected by the position sensor 57 shows a constant value for a predetermined time or longer, it is determined that a foreign object is caught. If No in step S7, that is, if it is determined that no foreign object is caught, this control ends. Step S7 is an example of control executed by the determination unit. Note that step S7 is executed even when the determination in step S1 is No and steps S3 and S6 are executed.

If Yes in step S7, that is, if it is determined that a foreign object has entered, the ECU 100 executes a predetermined fail-safe process (step S8). For example, when the engine 20 is in a low load operating state, the opening of the throttle valve 13 is increased in order to supply sufficient fresh air to the combustion chamber 23 . Further, when the engine 20 is in a high load operating state, the opening of the throttle valve 13 is reduced in order to prevent excessive supply of fresh air to the three-way catalyst 31 via the EGR pipe 50 .

In the above embodiment, the provisional target opening degree TDe used for F/B control when there is a request to fully close was a value greater than zero, but it may be zero. Also in this case, it is possible to maximize the deviation in the F/B control when there is a full-close request, and when a foreign object larger than the switching opening SD is caught, the foreign object is caught at an early stage. This is because it can be determined that

In the above embodiment, F/B control is performed by PID control, but PI (Proportional Integral) control may be used. This is because, in this case as well, the integral term increases and the drive duty ratio increases to -100% when foreign matter is caught.

In the above embodiment, the upper limit is -100%, but the upper limit is not limited to -90%. The upper limit value is set to a value at which the drive duty ratio does not increase to that value when no foreign matter is caught, but may increase beyond that value when foreign matter is caught. preferably.

In the above-described embodiment, it is determined that a foreign object has been caught when the drive duty is equal to or greater than the upper limit value and a predetermined time has elapsed, but the present invention is not limited to this. For example, it may be determined that a foreign object is caught immediately when the drive duty becomes equal to or higher than the upper limit value. As a result, it is possible to determine whether or not a foreign object has penetrated into the device more quickly.

The engine system of this embodiment may be an engine system mounted on a hybrid vehicle. The engine may also be a supercharged engine.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

20 engine 50 EGR pipe 52 EGR valve 53 valve element 54 valve seat 55 motor 56 spring 57 position sensor 100 ECU (control unit, determination unit)

Claims (1)

An EGR valve control device that controls the opening/closing operation of an EGR valve arranged in an EGR passage of an internal combustion engine by controlling the driving duty ratio of the EGR valve,
Control for feedback-controlling the drive duty ratio by calculating at least an integral term based on the deviation between the actual opening and the target opening when the actual opening of the EGR valve is equal to or greater than a predetermined opening other than the fully closed Department and
a determination unit that determines that foreign matter is caught in the EGR valve when the drive duty ratio becomes equal to or greater than an upper limit value during execution of the feedback control in response to a request to fully close the EGR valve; , and
The EGR valve control device, wherein the control unit sets the target degree of opening to a value smaller than the predetermined degree of opening when there is a request to fully close the EGR valve.

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