JP2007263051A - Intake air volume control system of internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake air volume regulator of an internal-combustion engine to improve the response of the intake air volume control or the durability of an intake throttle valve. <P>SOLUTION: It provide the intake throttle valve (12) which is arranged to the intake passage of an internal-combustion engine and opened and closed by a motor and an opening control means (46) to control the opening degree of the intake throttle valve based on the operational status of the internal-combustion engine. An opening control means makes avoid a small feeling range of change of the intake air volume to the opening of the intake throttle valve and sets the opening degree to secure the intake air volume which is needed at worst as the base opening (O<SB>B</SB>) of the intake throttle valve in order to operate the internal-combustion engine by the required high output. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an intake air amount control device for an internal combustion engine having an intake throttle valve in an intake passage.

  In this type of internal combustion engine, particularly a diesel engine, for example, an electric motor type intake throttle valve is used to increase the EGR amount or to provide an aftertreatment device such as a particulate filter to raise the temperature of the exhaust gas. The intake throttle valve is in a fully open position during normal operation, and the amount of cold intake air (fresh air amount) from outside air is reduced by restricting the intake passage as necessary.

In view of the large distance between the position of the intake throttle valve and the combustion chamber in the cylinder with respect to the intake passage, the opening / closing speed of the intake throttle valve is increased and the command value of the opening is increased to increase the target value. A technique for quickly following the amount of intake air is known (see, for example, Patent Document 1).
JP 2000-161108 A

  By the way, between the fully open position and the fully closed position of the intake throttle valve, there is a dead area, that is, an area where the change in intake air amount is still small and a desired intake air amount cannot be obtained. More specifically, the intake air amount does not follow the change in the opening degree of the intake throttle valve at a constant rate of change, and hardly changes even when the opening degree of the intake throttle valve is away from the fully open position. A region where the change in the intake air amount is still small and slightly changes with respect to the opening of the intake throttle valve is a dead region.

Here, it is conceivable to increase the opening / closing speed of the intake throttle valve as in the prior art and further increase the command value of the opening to avoid the insensitive region. In addition, there is a problem that the operation amount increases and the responsiveness of intake air amount control and the durability of the intake throttle valve decrease.
The present invention has been made in view of such problems, and an object of the present invention is to provide an intake air amount control device for an internal combustion engine that improves the response of intake air amount control and the durability of the intake throttle valve. .

  In order to achieve the above object, an intake air amount control device for an internal combustion engine according to claim 1 is provided in an intake passage of the internal combustion engine and is opened and closed by a motor, and an operating state of the internal combustion engine. Opening degree control means for controlling the opening degree of the intake throttle valve based on the opening degree control means, avoiding a dead zone where the change in the intake air amount is small with respect to the opening degree of the intake throttle valve, and The opening degree that secures the minimum amount of intake air necessary for the internal combustion engine to operate at a desired high output is set as the base opening degree of the intake throttle valve.

In the invention according to claim 2, the opening degree control means opens the intake throttle valve when the operation amount of the accelerator pedal exceeds a predetermined amount and the operation period of the accelerator pedal continues for a predetermined period. The degree is fixed at the fully open position.
Further, in the invention according to claim 3, when the opening amount of the intake throttle valve is less than a predetermined amount after the opening degree of the intake throttle valve is fixed at the fully open position, the opening degree control means It is characterized by returning the opening to the base opening at a stretch.

  Therefore, according to the intake air amount control device for an internal combustion engine of the first aspect of the present invention, the insensitive region, that is, the change in the intake air amount is still small between the fully open position and the fully closed position of the intake throttle valve. There is a region where the desired amount of intake air cannot be obtained. However, in this case, the opening degree control means makes the opening degree of the intake throttle valve the base opening degree, specifically, avoids the insensitive area where the change of the intake air amount is small with respect to the opening degree of the intake throttle valve, In addition, the opening degree is set so as to secure the minimum amount of intake air necessary for the internal combustion engine to operate at a desired high output. Therefore, it is possible to reduce the operation time and the operation amount of the intake throttle valve necessary for reducing the intake air amount while ensuring the high output of the engine. It is done.

Further, if the operation amount of the intake throttle valve is reduced, the load on the motor for driving the intake throttle valve to be reduced is reduced, so that the durability of the intake throttle valve can be improved.
According to the second aspect of the present invention, the opening degree control means provides a condition for setting the opening degree of the intake throttle valve to the fully open position. Specifically, the opening degree of the intake throttle valve is set to the fully open position only when the operation period of this pedal is satisfied in addition to the operation amount of the accelerator pedal. That is, when the pedal is only operated momentarily, the opening of the intake throttle valve does not reach the fully open position. Therefore, frequent switching between the base opening and the fully open position of the intake throttle valve can be avoided. As a result, fluttering of the intake throttle valve is suppressed, and this point also contributes to improving the durability of the intake throttle valve.

In addition, since the opening of the intake throttle valve is fixed at the fully open position, the opening / closing operation of the intake throttle valve is reduced, which also contributes to the improvement of the durability of the intake throttle valve.
Further, according to the invention of claim 3, the opening degree control means closes the opening degree of the intake throttle valve to the base opening degree at once when the accelerator pedal is restored. Accordingly, since the insensitive area is quickly avoided, it is possible to easily reduce the intake air amount.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an intake air amount control device embodied for a diesel engine. As shown in the figure, a supercharger 6 is provided in the intake passage 4 of the engine 2. Intake air taken from an air cleaner (not shown) is supercharged by the compressor 8 and then introduced into the combustion chamber 16 via the intercooler 10.

  An intake throttle valve 12 is disposed at an appropriate position in the passage 4. The throttle valve 12 includes a butterfly valve body 14 driven by a motor 13 with a brush. The flow rate (fresh air amount) of intake air is controlled by opening and closing the valve body 14, and the exhaust gas recirculation amount is further controlled. (EGR amount) is also controlled. Thus, in the throttle valve 12 of this embodiment, a brush is used to pass a current through a coil that generates a magnetic field.

A turbine 22 coupled coaxially with the compressor 8 is provided in the exhaust passage 20 of the engine 2, and the compressor 8 and the turbine 22 are rotationally driven by the exhaust gas after combustion.
The passage 4 and the passage 20 are connected by an EGR passage 24, and an EGR valve 26 is disposed at an appropriate position of the passage 24. The valve 26 includes a poppet valve body 28 driven by a brushless motor, and the EGR amount is controlled by opening and closing the valve body 28. As described above, the EGR valve 26 of the present embodiment passes a current through the coil without using a brush.

In the vehicle compartment, an input / output device (not shown), a storage device (ROM, RAM, BURAM, etc.) used for storing control programs and maps, an ECU (electronic control) including a central processing unit (CPU), a timer counter, etc Unit) 40 is installed. The ECU 40 performs comprehensive control of the engine 2 including continuous control of the opening degree of the throttle valve 12 and the EGR valve 26.
Various sensors such as an air flow sensor 30, an intake pressure sensor 32, an intake air temperature sensor 34, a rotation speed sensor 36, and an accelerator sensor 38 are connected to the input side of the ECU 40. The sensor 30 outputs a voltage corresponding to the intake air amount of the engine 2, the sensor 32 detects the intake pressure, and the sensor 34 detects the intake air temperature. The sensor 36 detects the rotational speed of the engine 2, and the sensor 38 detects the amount of operation of the accelerator pedal by the driver, that is, the accelerator opening. On the other hand, various devices such as the fuel injection valve 18 are connected to the output side of the ECU 40 in addition to the throttle valve 12 and the EGR valve 26 described above.

  Here, the ECU 40 includes an injection control unit 42 that targets the fuel injection valve 18 and an EGR control unit 44 that targets the throttle valve 12 and the EGR valve 26. In the ECU 40 of this embodiment, when a further EGR amount is requested, the opening degree of the valve body 14 of the throttle valve 12 and the opening of the valve body 28 of the EGR valve 26 are set so as to achieve the target excess air ratio. EGR amount feedback control is performed by continuously controlling the degree.

Specifically, the injection control unit 42 sets the fuel injection amount and the like based on, for example, the rotational speed from the sensor 36 and the accelerator opening from the sensor 38, and drives and controls the fuel injection valve 18 based on these set values. The engine 2 is operated.
Further, the EGR control unit 44 sets a target excess air ratio from the map based on the rotation speed and the fuel injection amount, and calculates the target EGR amount. On the other hand, the control unit 44 calculates the actual excess air ratio based on the intake air amount from the sensor 30 and the like, and calculates the actual EGR amount. Next, the deviation between the calculated target EGR amount and the actual EGR amount is fed back. Then, an instruction value is obtained from the control gain set by the PID control unit (opening control means) 46, and the rotation amount of the valve body 14 of the throttle valve 12 and the lift of the valve body 28 of the EGR valve 26 are determined by this instruction value. Continuously control the amount. As a result, the requested amount of EGR is obtained and approaches the target excess air ratio.

Here, when a further EGR amount is requested, the control unit 44 described above switches the control from the EGR valve 26 to the throttle valve 12 after controlling the opening degree of the EGR valve 26 in the fully open direction. The throttle valve 12 is throttled toward the fully closed position.
However, in the PID control unit 46, in view of the fact that there is an insensitive region, that is, a region where the change in the intake air amount is still small, in the process from the fully opened position of the throttle valve 12 to the fully closed position. It is provided different base opening degree O _B and.

Specifically, as shown in FIG. 2, the intake air amount does not follow the change in the opening degree of the throttle valve 12 at a constant rate of change, and the maximum opening degree where the opening degree of the throttle valve 12 is the fully open position. Almost no change even when moving away from the degree _Omax . A region in which the change in the intake air amount is still small and slightly decreases with respect to the opening of the throttle valve 12 is a dead region. This dead area is a characteristic caused by a small change in the pressure difference between the intake passage 4 and the exhaust passage 20. On the other hand, the intake air amount rapidly decreases after the opening of the throttle valve 12 reaches, for example, about 50% of the fully opened position. The region where the change in the intake air amount is large and rapidly decreases is the reaction region.

Accordingly, the PID controller 46, sets the base opening degree O _B at the boundary between these dead region with the reaction region. In other words, the base opening degree O _B causes avoiding dead zones, and the opening to secure the minimum necessary to become intake air amount to the engine 2 is operated at a desired high output (the throttle valve 12 The throttle opening is set to about 50% of the fully open position). At the time of normal operation as in the case of the further EGR amount is requested, the opening degree of the throttle valve 12 is adjusted within a range from the base opening degree O _B of minimum opening O _min. As a result, the amount of operation and the number of operations of the throttle valve 12 driven by the brushed motor 13 are reduced. The minimum opening degree O _min is not the high output operation, but is an opening degree that secures the minimum intake air amount required for the engine 2 to operate.

Referring to FIG. 3, a flowchart for adjusting the opening of the throttle valve 12 by the PID controller 46 is shown. Hereinafter, an operation according to the present invention of the intake air amount control device configured as described above will be described.
In step S301 in the drawing, the normal operation described above, the opening degree of the throttle valve 12 is adjusted within a range from the base opening degree O _B of minimum opening O _min.

Subsequently, in step S302 in the figure, it is determined whether or not the operation amount of the accelerator pedal exceeds a predetermined amount corresponding to the sudden acceleration of the vehicle, and the accelerator opening is determined based on the signal from the sensor 38. If it is determined that the degree A is exceeded, that is, if YES, the process proceeds to step S303.
Further, in step S303, it is determined whether or not the operation period of the accelerator pedal is continued for a predetermined period corresponding to the rapid acceleration, and it is determined by the timer counter that the operation period of the accelerator pedal is equal to or longer than the predetermined period T. If this is the case, that is, if YES, the PID control unit 46 presumes that the engine is in a high-load operation state and proceeds to step S304.

On the other hand, in either step S302 or step S303, that is, when it is determined that the accelerator opening does not exceed the predetermined opening A, or it is determined that the operation period of the accelerator pedal has not exceeded the predetermined period T. If any of the cases is true, the PID control unit 46 assumes that it is in the normal operation state and returns to step S301.
In step S304, the opening degree of the throttle valve 12 is fully open position in order to get more of the intake air amount, that is, the process proceeds to step S305 and is fixed at the maximum opening degree _{O max.} In step S305, it is determined whether or not the operation amount of the accelerator pedal is below a predetermined amount corresponding to rapid acceleration. As long as it is determined that the accelerator opening exceeds the predetermined opening A based on the signal from the sensor 38, the process returns to step S304, whereas the accelerator opening reaches the predetermined opening A. If it is determined that there is no, then constructive if PID controller 46 is in normal operating conditions, it leaves the series of routine returns once the opening of the throttle valve 12 to the base opening degree O _B.

As described above, there is an insensitive region between the fully open position and the fully closed position of the throttle valve 12 (FIG. 2). However, according to the present invention, in this case, the PID control unit 46 sets the opening degree of the throttle valve 12 to the base opening degree O _B , specifically, the change in the intake air amount with respect to the opening degree of the throttle valve 12. The opening degree is set so as to avoid the small insensitive area and to secure the minimum intake air amount necessary for the engine 2 to operate at a desired high output. Therefore, the operation time and the operation amount of the throttle valve 12 can be reduced while securing the high output of the engine 2.

More specifically, as shown in FIG. 4, the base opening degree O _B of the throttle valve 12 is set to the operation amount Y by the reduced position than the maximum opening degree O _max. Therefore, in the case of reducing the intake air amount is the throttle valve 12 is throttled, when squeezed toward the minimum opening O _min from the base opening degree O _B as in the present invention (shown in solid line), The amount of operation of the throttle valve 12 is clearly reduced as compared with the case where the throttle is throttled from the maximum opening O _max to the minimum opening O _min as shown in the prior art (indicated by a dotted line in the figure). In addition, the time required to reach the target air amount q in this case is also clearly reduced by time X in the present invention (indicated by a solid line in the figure) as compared with the conventional case (indicated by a dotted line in the figure). I understand.

As described above, according to the present invention, the operation time and the operation amount of the throttle valve 12 required for reducing the intake air amount can be reduced, and the response of the intake air amount control by the throttle valve 12 can be improved. .
Further, if the operation amount of the throttle valve 12 is reduced, the feedback control of the EGR amount by the throttle valve 12 is eliminated in the insensitive region, and setting of the control gain for the throttle valve 12 becomes unnecessary, thereby simplifying the system. .

  Moreover, if the operation amount of the throttle valve 12 is reduced, the load on the motor 13 that drives the throttle valve 12 to be opened is reduced, so that the durability of the throttle valve 12 can be improved. In particular, when the throttle valve 12 is a brushed type as in this embodiment, the wear on the sliding surface is significantly suppressed. Note that the above-described improvement in durability of the throttle valve 12 contributes to a reduction in the manufacturing cost of the throttle body.

On the other hand, the above-described PID control unit 46 has a condition for setting the opening degree of the throttle valve 12 to the maximum opening degree _Omax . Specifically, the opening degree of the throttle valve 12 is set to the fully open position only when the operation period of this pedal is satisfied in addition to the operation amount of the accelerator pedal. That is, when the pedal is only operated momentarily, the PID control unit 46 does not simulate that the engine is in a high load operation state, and the opening degree of the throttle valve 12 does not reach the fully open position. Therefore, the base opening degree O _B by the normal operation mode of the throttle valve 12, frequent switching between the maximum opening O _max with high load operating mode becomes avoidable. As a result, fluttering of the throttle valve 12 is suppressed, and this point also contributes to improving the durability of the throttle valve 12.

Moreover, since the opening degree of the throttle valve 12 is fixed at the maximum opening degree _Omax , the opening / closing operation of the throttle valve 12 is reduced, which also contributes to the improvement of the durability of the throttle valve 12.
Further, PID control unit 46, when the accelerator pedal is returned, thereby once closes the opening of the throttle valve 12 to the base opening degree O _B. Therefore, the dead area can be quickly avoided by reaching the reaction area from the dead area at once, and a state where the intake air amount can be easily introduced can be secured.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, an example in which the opening degree of the intake throttle valve is adjusted in order to obtain a further EGR amount is shown, but the present invention is not necessarily limited to the above embodiment. For example, the present invention is applicable to the case of adjusting the opening of the intake throttle valve in the exhaust gas temperature rise control in the case where an aftertreatment device such as a particulate filter (DPF) is provided. Similarly to the above, there is an effect of improving the response of the intake air amount control and the durability of the intake throttle valve.

  In the above embodiment, the intake air amount control device for the diesel engine 2 has been described. However, the present invention can be applied to all engines having an intake throttle valve that is opened and closed by a motor.

1 is an overall configuration diagram illustrating an intake air amount control device according to an embodiment of the present invention. It is a figure which shows the relationship between the opening degree of the intake throttle valve by the control apparatus of FIG. 1, and the characteristic of intake air amount. It is a flowchart of the opening degree adjustment of the intake throttle valve by the control apparatus of FIG. It is a timing chart of the opening degree adjustment of the intake throttle valve by the control device of FIG.

Explanation of symbols

2 Engine 4 Intake passage 12 Intake throttle valve 13 Motor 14 Butterfly valve body 38 Accelerator sensor 40 ECU (electronic control unit)
46 PID control unit (opening control means)

Claims (3)

An intake throttle valve disposed in an intake passage of the internal combustion engine and driven to open and close by a motor;
Opening degree control means for controlling the opening degree of the intake throttle valve based on the operating state of the internal combustion engine,
The opening degree control means is at least necessary for avoiding the insensitive region where the change in the intake air amount is small with respect to the opening degree of the intake throttle valve, and for operating the internal combustion engine at a desired high output. An intake air amount control device for an internal combustion engine, wherein an opening degree for securing an intake air amount is set to a base opening degree of the intake throttle valve.   The opening degree control means fixes the opening degree of the intake throttle valve at a fully opened position when the operation amount of the accelerator pedal exceeds a predetermined amount and the operation period of the accelerator pedal is continued for a predetermined period. The intake air amount control device for an internal combustion engine according to claim 1, wherein   The opening control means determines the opening of the intake throttle valve when the operation amount of the accelerator pedal is less than the predetermined amount after the opening of the intake throttle valve is fixed at the fully opened position. The intake air amount control device for an internal combustion engine according to claim 2, wherein the intake air amount is returned to the base opening at a stroke.

Images