JP2014196678A - Control device for internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine with a supercharger capable of performing valve opening control of an air bypass valve according to the generation timing of surge, in an internal combustion engine with a supercharger including a valve lift mechanism for an intake valve.SOLUTION: An internal combustion engine with a supercharger includes: an ABV (air bypass valve) 38 configured so that it can open/close a bypass passage 36 which bypasses a compressor 32 from an intake passage 10; and a variable valve lift mechanism 24 configured so that it can change a valve lift amount of an intake valve. Based on a target throttle opening, a target throttle passing air amount mt, which is a target value of an air amount passing through the throttle, is calculated, and when the calculated target throttle passing air amount mt becomes equal to or less than an intake pulsation generation upper limit flow amount ms of the compressor 32 calculated from a current boost pressure, the ABV 38 is opened with a time delay of a predetermined delay time T. The delay time T is calculated based on the target throttle opening and a target valve lift amount.

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger, and more particularly to control of an air bypass valve provided in a passage that bypasses a compressor of the supercharger.

  Conventionally, for example, JP 2010-38077 A discloses a control device for an air bypass valve disposed in an intake bypass passage that bypasses a compressor of a supercharger. In this conventional control device, in order to prevent the occurrence of intake pulsation (surge) during engine deceleration, the throttle valve opening, the supercharging pressure of the compressor upstream of the throttle valve, and the intake pressure downstream of the throttle valve are adjusted. The air bypass valve is opened when the current amount of air passing through the throttle valve estimated on the basis of this is below the upper limit of the intake pulsation generation of the compressor set for the current supercharging pressure.

JP 2010-38077 A JP 2012-154292 A JP 2007-255265 A

  In the conventional control device described above, the air bypass valve is opened when the current amount of air passing through the throttle valve is equal to or lower than the upper limit of the intake pulsation in order to prevent the intake pulsation (surge) from being generated during engine deceleration. I have to. Here, as an actuator for controlling the in-cylinder air amount sucked into the cylinder, there is a variable valve lift mechanism for variably setting the lift amount of the intake valve, for example, in addition to the throttle described above. In an internal combustion engine equipped with a variable valve lift mechanism, it is possible to obtain the same intake throttle effect as when the throttle opening is operated to the small opening side by operating the intake valve lift amount to the low lift side.

  However, the pressure distribution in the intake passage downstream of the compressor differs between when the cylinder air amount is controlled by the valve lift amount and when it is controlled by the throttle. That is, when the throttle is operated to the small opening side during engine deceleration, the intake passage from the downstream of the compressor to the throttle becomes high pressure, whereas when the valve lift is operated to the low lift side, from the downstream of the compressor The intake passage to the intake valve becomes high pressure. This high-pressure intake air volume difference affects the time from when the amount of air passing through the throttle reaches the intake pulsation generation upper limit flow rate until the actual occurrence of a surge. For this reason, when the above-described conventional technique for preventing a surge from being generated when the engine is decelerated is applied to an internal combustion engine having a variable valve lift mechanism, the air bypass valve is opened at an appropriate timing according to the occurrence of the surge. There is a risk that the reacceleration performance is deteriorated due to an unnecessary decrease in the supercharging pressure.

  The present invention has been made in view of the above-described problems. In an internal combustion engine with a supercharger equipped with a valve lift mechanism of an intake valve, valve opening control of an air bypass valve is performed in accordance with the occurrence timing of a surge. It is an object of the present invention to provide a control device for an internal combustion engine with a supercharger that can be used.

In order to achieve the above object, a first invention provides a control device for an internal combustion engine with a supercharger,
A compressor disposed in the intake passage of the internal combustion engine;
A bypass passage for bypassing the compressor from the intake passage;
An air bypass valve configured to open and close the bypass passage;
A variable valve lift mechanism configured to be able to vary the valve lift amount of the intake valve;
Throttle control means for controlling the throttle to a target throttle opening;
Valve lift control means for controlling the variable valve lift mechanism to a target valve lift amount;
First calculation means for calculating a target throttle passage air amount, which is a target value of an air amount passing through the throttle, based on the target throttle opening;
Control means for opening the air bypass valve by delaying a predetermined delay time when the target throttle passage air amount is equal to or lower than the intake pulsation generation upper limit flow rate calculated from the current supercharging pressure,
The control means includes second calculation means for calculating the delay time based on the target throttle opening and the target valve lift amount.

According to a second invention, in the first invention,
The second calculation means includes:
The sum of a first delay time calculated as a shorter time as the target throttle opening is smaller and a second delay time calculated as a shorter time as the target valve lift amount is larger is calculated as the delay time. It is characterized by that.

According to a third invention, in the first or second invention,
When the target throttle passage air amount during the delay time becomes larger than the compressor intake pulsation generation upper limit flow rate calculated from the current supercharging pressure, the control means opens the air bypass valve. It further has a limiting means for limiting.

  According to the first aspect, the target throttle passage air amount, which is the target value of the air amount passing through the throttle, is calculated based on the target throttle opening. When the calculated target throttle passage air amount becomes equal to or lower than the compressor intake pulsation generation upper limit flow rate set according to the current supercharging pressure, the air bypass valve is opened with a predetermined delay time delay. The Here, the time from when the throttle and the variable valve lift are operated to the target throttle opening and the target valve lift until the intake pulsation (surge) of the compressor actually occurs depends on the target throttle opening and the target valve lift. It depends on the size. Therefore, according to the present invention, since the delay time is calculated based on the target throttle opening and the target valve lift amount, it is possible to perform the valve opening control of the air bypass valve according to the time when the surge actually occurs. it can.

  According to the second aspect of the present invention, when the target throttle passing air amount becomes equal to or smaller than the intake pulsation generation upper limit flow rate mainly by reducing the target throttle opening, the target valve lift amount is mainly reduced to make the target The delay time is calculated to be shorter than when the amount of air passing through the throttle is equal to or lower than the intake pulsation generation upper limit flow rate. When the throttle is operated to the small opening side during deceleration of the internal combustion engine, etc., the intake space from the downstream of the compressor to the throttle becomes high pressure, whereas when the valve lift is operated to the small lift side, the compressor The intake space from the downstream to the intake valve becomes high pressure. This capacity difference between the high-pressure intake air affects the time from when the intake system actuator is operated to when a surge actually occurs. Therefore, according to the present invention, it is possible to set the delay time according to the time when the surge actually occurs.

  According to the third aspect of the present invention, when the target throttle passage air amount during the delay time exceeds the intake pulsation generation upper limit flow rate set according to the current supercharging pressure, the opening of the air bypass valve is restricted. Is done. For this reason, according to the present invention, it is possible to effectively avoid the situation in which the air bypass valve is opened when no surge occurs. It becomes possible to improve responsiveness.

It is the schematic which shows the structure of the supercharged engine in which the control apparatus which concerns on this Embodiment is used. It is a figure for demonstrating the relationship between the operation area | region of a compressor, and a surge area | region. It is a figure for demonstrating the pressure state in the intake passage at the time of an intake throttle operation. It is a figure which shows an example of the map for calculating delay time Tt and delay time Tv. It is a flowchart which shows the control routine performed by the control apparatus which concerns on this Embodiment.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to the drawings.

[Configuration of Embodiment 1]
An internal combustion engine (hereinafter also referred to as “engine”) in which the control device according to the present embodiment is used is a supercharged engine having a turbocharger, and more specifically, torque is adjusted by adjusting an air amount by a throttle. It is a 4-cycle reciprocating engine that can be controlled. FIG. 1 is a schematic diagram illustrating a configuration of a supercharged engine in which a control device according to the present embodiment is used. The supercharged engine according to the present embodiment includes a turbocharger 30 including a compressor 32 provided in the intake passage 10 and a turbine 34 provided in the exhaust passage 20. The intake passage 10 is connected to an intake manifold 18 attached to the engine body 2. An air cleaner 12 is provided at the inlet of the intake passage 10, and an air flow meter 42 for measuring the air flow rate is disposed downstream of the air cleaner 12 and upstream of the compressor 32.

  An intercooler 14 is provided between the compressor 32 and the throttle 16 in the intake passage 10. A supercharging pressure sensor 44 for measuring the pressure in the upstream portion of the throttle 16, that is, the supercharging pressure, is attached to the outlet of the intercooler 14. The intake passage 10 is provided with an intake bypass passage 36 for bypassing the compressor 32 from the downstream side to the upstream side of the compressor 32 to recirculate air. An air bypass valve (hereinafter also referred to as “ABV”) 38 for opening and closing the intake bypass passage 36 is provided in the middle of the intake bypass passage 36. The air bypass valve 38 is an electrically controlled air bypass valve corresponding to active control that realizes an arbitrary opening degree. For example, the air bypass valve 38 is opened when the throttle 16 is suddenly closed to suppress the occurrence of a surge and to suppress the compressor 32. It is for protection. The exhaust passage 20 is connected to an exhaust manifold 22 attached to the engine body 2. The exhaust passage 20 is provided with a waste gate valve 40 for flowing the exhaust gas bypassing the turbine 34.

  An intake manifold 18 and an exhaust manifold 22 communicate with each cylinder of the engine body 2 via an intake valve and an exhaust valve (not shown). The intake valve is provided with a variable valve lift mechanism 24 for variably setting the valve lift amount. In addition, as the variable valve lift mechanism 24 of the present embodiment, for example, a mechanism that changes the working angle stepwise together with the lift amount of the intake valve by switching a plurality of intake cams may be used. A mechanism capable of continuously changing the lift amount and the working angle by rotating the control shaft may be used.

  The control device according to the present embodiment is realized as part of the function of an ECU (Electronic Control Unit) 100 that controls the supercharged engine. In addition to the air flow meter 42 and the supercharging pressure sensor 44, the ECU 100 includes various sensors such as an intake pipe pressure sensor 46, an engine speed sensor 48, an accelerator opening sensor 50, etc. Information and signals are input. The ECU 100 operates various actuators such as the throttle 16, the variable valve lift mechanism 24, and the air bypass valve 38 based on the information and signals.

[Operation of Embodiment 1]
Next, the operation of the first embodiment will be described with reference to FIGS. If the throttle 16 is suddenly closed or the valve lift amount is suddenly reduced in the supercharged state of the supercharged engine, the amount of air taken into the engine main body 2 is suddenly reduced before the rotational speed of the compressor 32 is reduced. In this case, the intake pulsation (surge) may occur due to the loss of the air flow downstream of the compressor 32 and backflow to the compressor 32. When a surge occurs, problems such as a surge noise in the compressor 32 and an air-fuel ratio shift due to a reverse flow of intake air occur.

  In order to avoid such a problem, conventionally, control is performed to open the air bypass valve 38 when the operation region of the compressor 32 shifts to the surge generation region. This will be described in more detail with reference to FIG. FIG. 2 is a diagram for explaining the relationship between the operating region of the compressor and the surge region. Here, in FIG. 2, as a parameter for defining the operating region of the compressor 32, an air amount passing through the compressor 32 (hereinafter referred to as “compressor passing air amount”) and a downstream pressure ratio with respect to the upstream side of the compressor 32. (Hereinafter referred to as “compressor pressure ratio”). Since the pressure on the upstream side of the compressor 32 is substantially equivalent to the atmospheric pressure, the compressor pressure ratio may be replaced with the pressure on the downstream side of the compressor 32 (that is, the supercharging pressure).

  As shown in FIG. 2, when the surge of the compressor 32 occurs, the surge generation upper limit flow rate ms, which is the upper limit of the amount of air passing through the compressor 32 (boundary with the surge region in the figure), depends on the compressor pressure ratio. Change. More specifically, the surge generation upper limit flow rate ms increases as the compressor pressure ratio increases.

  Here, the amount of air passing through the compressor follows the amount of air passing through the throttle 16 (hereinafter referred to as “the amount of air passing through the throttle”). Therefore, the target throttle passage air amount mt which is the amount of air passing through the throttle realized by operating the intake system actuator such as the throttle 16 or the variable valve lift mechanism 24 is the surge generation upper limit flow rate ms corresponding to the current compressor compression ratio. In the case of the following, it can be determined that a surge will subsequently occur. Therefore, in the conventional air bypass valve control, the air bypass valve 38 is opened when the target throttle passage air amount mt ≦ the surge generation upper limit flow rate ms is established. When the air bypass valve 38 is opened, the pressure (supercharging pressure) on the downstream side of the compressor 32 is lowered, so that the surge generation upper limit flow rate ms is lowered, thereby preventing the occurrence of a surge.

  However, when the air bypass valve 38 is opened, there is a certain effect in preventing the occurrence of a surge, but a turbo lag at the time of reacceleration may be a problem due to a decrease in supercharging pressure. For this reason, it is desirable to minimize the period during which the air bypass valve 38 is opened. Further, the time from when the target throttle passage air amount mt reaches the surge generation upper limit flow rate ms to when the surge is actually generated differs depending on the intake system actuator used for the intake throttle operation. FIGS. 3A and 3B are diagrams for explaining the pressure state in the intake passage during the intake throttle operation. FIG. 3A shows the state when the intake throttle operation is performed using the throttle 16, and FIG. 3B shows the variable valve. A state when the intake throttle operation is performed using the lift mechanism 24 is shown. As shown to (A) in the figure, when the opening degree of the throttle 16 is operated in the small opening degree direction from the supercharged state, the pressure in the intake passage from the downstream of the compressor 32 to the throttle 16 increases. On the other hand, as shown in FIG. 5B, when the valve lift amount is operated to the low lift side from the supercharged state, the pressure in the intake passage from the downstream of the compressor 32 to the intake valve increases. This difference in intake capacity affects the time from when the actuator is operated to when a surge actually occurs. More specifically, even when the same target throttle passing air amount mt is realized, when the throttle 16 is operated, the time from the operation to the occurrence of surge is larger than when the variable valve lift mechanism 24 is operated. Shorter. For this reason, if the above-described valve opening control of the air bypass valve 38 is performed without considering the operation amount of each actuator, for example, when the variable valve lift mechanism 24 is mainly operated, the air bypass valve 38 is disabled. There is a risk of opening it as soon as necessary.

  Therefore, in the control device of the present embodiment, the air bypass valve 38 is opened with a delay of a predetermined delay time T after the target throttle passage air amount mt reaches the surge generation upper limit flow rate ms. The delay time T is calculated by adding the delay time Tt calculated from the target throttle opening and the delay time Tv calculated from the target valve lift amount. FIG. 4 is a diagram illustrating an example of a map for calculating the delay time Tt and the delay time Tv. As shown in this figure, the delay time Tt is calculated as a larger value as the target throttle opening is larger, and the delay time Tv is calculated as a smaller value as the target valve lift amount is larger. As a result, the delay time T when the intake throttle operation is mainly performed by the variable valve lift mechanism 24 is calculated to be longer than that when the intake throttle operation is mainly performed by the throttle 16, so that a surge is actually generated. The valve opening control of the air bypass valve 38 corresponding to the time can be performed.

  Even if the target throttle passage air amount mt is less than or equal to the surge generation upper limit flow rate ms, there is a possibility that a surge may occur even if the air bypass valve 38 is not opened in the case of reacceleration before the occurrence of the surge. Absent. Such a driving state may occur, for example, when the driver steps on again immediately after releasing the accelerator pedal in a supercharged state. In such a case, if the air bypass valve 38 is opened, the supercharging response at the time of resupercharging is lowered due to the decrease of the supercharging pressure.

  Therefore, in the control device of the present embodiment, when the target throttle passage air amount mt becomes larger than the surge generation upper limit flow rate ms before the delay time elapses, the air bypass valve 38 is opened. Suppose that there is no. As a result, unnecessary opening of the air bypass valve 38 can be avoided and the responsiveness at the time of reacceleration can be improved.

[Specific Processing in First Embodiment]
Next, a specific process of the air bypass valve opening control executed in the control device of the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing a control routine executed by ECU 100 in the present embodiment. Note that the control routine shown in FIG. 5 is repeatedly executed during operation of the supercharged engine.

  In the control routine shown in FIG. 5, first, it is determined from the opening signal of the accelerator opening sensor 50 whether or not the supercharged engine is decelerating (step S100). As a result, when it is determined that the vehicle is not decelerating, it is determined that there is no possibility of occurrence of a surge, and this routine is immediately terminated without opening the air bypass valve 38. On the other hand, if it is determined that the vehicle is decelerating, it is determined that there is a possibility that a surge will occur, the process proceeds to the next step, and the surge generation upper limit flow rate ms is calculated (step S102). Here, specifically, the surge generation upper limit flow rate ms corresponding to the current supercharging pressure detected by the supercharging pressure sensor 44 is specified from the map.

  Next, the target throttle passage air amount mt is calculated (step S104). Here, specifically, the target throttle opening calculated from the operating conditions, the excess flow rate of the orifice based on the differential pressure before and after the throttle 16, the flow path area determined by the throttle opening, and the flow coefficient are calculated. Information such as the supercharging pressure detected by the supply pressure sensor 44 and the intake pipe pressure detected by the intake pipe pressure sensor 46 is input, and the target throttle passage air amount mt is calculated from the input information.

  Next, a surge occurrence determination is performed (step S106). Specifically, it is determined whether the target throttle passage air amount mt calculated in step S104 is equal to or less than the surge generation upper limit flow rate ms calculated in step S102 (step S106). As a result, when the establishment of mt ≦ ms is not recognized, it is determined that there is no possibility of occurrence of a surge, and the routine proceeds to step S114, which will be described later, and the air bypass valve 38 is maintained in the closed state and this routine is performed. Is terminated.

  On the other hand, when the establishment of mt ≦ ms is recognized in step S106, it is determined that a surge will occur when the target throttle passage air amount mt is realized, and the process proceeds to the next step to set the delay time T. Calculated (step S108). Specifically, the delay times Tv and Tt corresponding to the target valve lift amount and the target throttle opening calculated from the operating conditions are calculated based on the map shown in FIG. Then, the sum of the delay time Tv and the delay time Tt is calculated as the delay time T.

  Next, the surge determination is performed again when the delay time T has elapsed (step S110). Here, specifically, the target throttle passage air amount mt and the surge generation upper limit flow rate ms are again calculated under the operating conditions when the delay time T has elapsed, and the magnitudes thereof are compared. This surge determination may be performed during the delay time. As a result, when it is recognized that mt ≦ ms is established, it is determined that a surge is surely generated, the process proceeds to the next step, and the air bypass valve 38 is opened (step S112).

  On the other hand, if mt ≦ ms is not satisfied as a result of the determination in step S110, it is determined that the operating condition is such that no surge is generated due to a reacceleration request or the like, the process proceeds to the next step, and the air bypass The valve 38 is maintained in a closed state (step S114).

  As described above, according to the control device of the present embodiment, the air bypass valve 38 can be opened in accordance with the timing at which the surge actually occurs, so the air bypass valve 38 keeps the valve opening to the minimum necessary. be able to. Further, according to the control device of the present embodiment, the valve opening of the air bypass valve 38 can be limited when the operation condition is shifted so that no surge occurs until the delay period elapses. It is possible to effectively suppress the decrease in supercharging response.

  By the way, in the control device of the above-described embodiment, the measured values of the supercharging pressure and the intake pipe pressure are used when calculating the target throttle passage air amount mt. It is good also as a structure using the value calculated by the model. In addition to the method described above, for example, a known method disclosed in Patent Document 1 may be used.

2 Engine body 10 Intake passage 20 Exhaust passage 30 Turbocharger 32 Compressor 34 Turbine 36 Intake bypass passage 38 Air bypass valve 40 Wastegate valve 42 Air flow meter 44 Supercharging pressure sensor 46 Intake pipe pressure sensor 48 Engine speed sensor 50 Accelerator Opening sensor 100 ECU (control device)

Claims (3)

A compressor disposed in the intake passage of the internal combustion engine;
A bypass passage for bypassing the compressor from the intake passage;
An air bypass valve configured to open and close the bypass passage;
A variable valve lift mechanism configured to be able to vary the valve lift amount of the intake valve;
Throttle control means for controlling the throttle to a target throttle opening;
Valve lift control means for controlling the variable valve lift mechanism to a target valve lift amount;
First calculation means for calculating a target throttle passage air amount, which is a target value of an air amount passing through the throttle, based on the target throttle opening;
Control means for opening the air bypass valve by delaying a predetermined delay time when the target throttle passage air amount is equal to or lower than the intake pulsation generation upper limit flow rate calculated from the current supercharging pressure,
The control apparatus for an internal combustion engine with a supercharger, wherein the control means includes second calculation means for calculating the delay time based on the target throttle opening and the target valve lift amount. The second calculation means includes:
The sum of a first delay time calculated as a shorter time as the target throttle opening is smaller and a second delay time calculated as a shorter time as the target valve lift amount is larger is calculated as the delay time. The control apparatus for an internal combustion engine with a supercharger according to claim 1.   When the target throttle passage air amount during the delay time becomes larger than the compressor intake pulsation generation upper limit flow rate calculated from the current supercharging pressure, the control means opens the air bypass valve. The control device for an internal combustion engine with a supercharger according to claim 1 or 2, further comprising limiting means for limiting.

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