JP2016008581A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent as much as possible an overshoot of an internal combustion engine which exceeds target boost pressure while making the pressure of intake air filled into a cylinder promptly reach target air intake pressure, in the internal combustion engine with an exhaust turbo supercharger.SOLUTION: An opening of a waist gate value is operated so that air intake pressure reaches target air intake pressure while reducing an opening of a throttle valve smaller than an opening which corresponds to a required opening once when the pressure of intake air filled into a cylinder approximates target air intake pressure in a process in which the pressure of the intake air rises in a situation that supercharging is performed by an exhaust turbo supercharger, and gradually expanding the opening so as to reach an opening which corresponds to the required load.

Description

  The present invention relates to a control device for controlling an internal combustion engine equipped with an exhaust turbocharger.

  The energy of the exhaust gas discharged from the cylinder is used to rotate the exhaust turbine (turbine wheel), the rotation is transmitted to the compressor impeller (compressor wheel), and the intake air is pressurized and compressed (supercharged). An exhaust turbocharger that feeds into a cylinder is well known.

  When the throttle valve opening increases during the transition period for accelerating the internal combustion engine, the displacement increases in response to the increase in intake air, and the work of the exhaust turbocharger increases, filling the cylinder. There may occur an overshoot in which the pressure of the intake air (supercharging pressure) exceeds the target intake pressure.

  In order to prevent such overshooting of the intake pressure, the waste gate valve is opened before the intake pressure reaches the target intake pressure, and a part of the exhaust is led to a bypass that bypasses the turbine to increase the intake pressure. Control is performed to loosen.

  However, there is a time lag between the operation of the waste gate valve and the actual increase in intake pressure. Therefore, in order to reliably prevent intake pressure overshoot, it is necessary to open the waste gate valve from an early stage (that is, from a stage where the deviation between the intake pressure and the target intake pressure is large). As a result, the increase of the intake pressure becomes dull before the target intake pressure, and the increase in the output of the internal combustion engine and the acceleration are delayed by that amount, which may cause a disadvantage that the acceleration response desired by the driver cannot be obtained.

  As another method for suppressing the overshoot of the intake pressure, it is also considered to perform an operation of reducing the opening of the throttle valve when the intake pressure exceeds the target intake pressure (see, for example, Patent Document 1 below). ). However, it does not prevent the intake pressure overshoot itself.

Japanese Patent Laid-Open No. 11-351010

  However, the control described in Patent Document 1 is to reduce the supercharging pressure by reducing the throttle opening after the supercharging pressure exceeds the target supercharging pressure. Therefore, it cannot be said that it completely prevents the occurrence of overshoot.

  An object of the present invention is to suppress as much as possible overshoot exceeding the target supercharging pressure while allowing the pressure of the intake air charged in the cylinder to quickly reach the target intake pressure.

  In order to solve the above problems, a control device for an internal combustion engine according to the present invention has a configuration as described below. That is, the control apparatus for an internal combustion engine according to the present invention controls an internal combustion engine attached with an exhaust turbocharger, and fills the cylinder in a situation where supercharging by the exhaust turbocharger is performed. When the target intake pressure is approached in the process of increasing the intake air pressure, the throttle valve opening is temporarily reduced from the opening corresponding to the required load, and then this becomes the opening corresponding to the required load. The opening degree of the waste gate valve is operated so that the intake pressure becomes the target intake pressure while gradually increasing.

  In such a case, when the intake pressure charged in the cylinder rises, when the target intake pressure is approached, the opening of the throttle valve is once reduced, so that the increase in the intake pressure can be suppressed quickly. Therefore, acceleration performance can be ensured while preventing the occurrence of overshoot. Furthermore, since the opening degree of the throttle valve is once reduced and then gradually increased so as to become the opening degree corresponding to the required load, it is possible to suppress the occurrence of pumping loss due to the reduction in the opening degree of the throttle valve.

  As a control device for more accurately preventing intake pressure overshoot, the larger the throttle valve opening just before performing the control to temporarily reduce the throttle valve opening, the larger the throttle valve opening in the control. One that increases the reduction amount.

  According to the present invention, it is possible to suppress as much as possible an overshoot in which the pressure of the intake air filled in the cylinder quickly reaches the target intake pressure while exceeding the target boost pressure.

1 is a schematic diagram showing an internal combustion engine according to an embodiment of the present invention. The flowchart which shows the control procedure of the embodiment roughly. Action | operation explanatory drawing of the same embodiment.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode. The ignition coil is integrally incorporated in a coil case together with an igniter that is a semiconductor switching element.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, a compressor 51 of the exhaust turbocharger 5, an intercooler 35, an electronic throttle valve 32 that is an intake throttle valve, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream side. doing.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42, an exhaust turbine 52 of the exhaust turbocharger 5, and an exhaust purification three-way catalyst 41 are arranged on the exhaust passage 4. In addition, an exhaust bypass passage 43 that bypasses the turbine 52 and a waste gate valve 44 that is a bypass valve that opens and closes the inlet of the bypass passage 43 are provided. The waste gate valve 44 is driven by the actuator 6.

The actuator 6 has a diaphragm chamber 61 and a constant pressure chamber 62, and opens a waste gate valve 44 that closes the bypass 43 using a differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62. That is, when the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 exceeds a predetermined set pressure, the valve rod 63 is displaced against the elastic biasing force of the spring 64 and opens the waste gate valve 44. When the differential pressure between the diaphragm chamber 61 and the constant pressure chamber 62 is equal to or lower than the set pressure, the valve rod 63 returns to the original position by the elastic biasing force of the spring 64, and the waste gate valve 44 is completely closed.

  Into the diaphragm chamber 61 of the actuator 6 is introduced the intake pressure, that is, the supercharging pressure, at the downstream side of the compressor 51 and the upstream side of the throttle valve 32 in the intake passage 3. Between the diaphragm chamber 61 and the relevant part of the intake passage 3, a supercharging pressure introduction flow channel 71 for communicating the two and a depressurization for opening the supercharging pressure introduction flow channel 71 (or the diaphragm chamber 61) to the atmosphere. A flow path 72 and a VSV 73 that opens and closes the depressurization flow path 72 are provided.

  The VSV 73 is a flow control valve such as a solenoid valve that receives the control signal l and changes its opening degree. If the opening degree of the VSV 73 is manipulated, a part of the supercharged air flowing from the intake passage 3 into the supercharging pressure introduction passage 71 is released to the atmosphere via the decompression passage 72, and the pressure in the diaphragm chamber 61 is increased. Can be controlled.

  Note that atmospheric pressure is usually introduced into the constant pressure chamber 62 of the actuator 6.

  The exhaust turbocharger 5 is configured such that an exhaust turbine 52 and an impeller 51 of a compressor are coaxially connected via a shaft 53 and interlocked. Then, the turbine 52 and the impeller 51 are rotationally driven by using the energy of the exhaust gas, and the compressor is pumped with the rotational force, whereby the intake air is pressurized and compressed (supercharged) and sent to the cylinder 1.

  The ECU 0 as the control device for the internal combustion engine of the present embodiment is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like.

  The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle and engine speed of the crankshaft, and depression of an accelerator pedal. An accelerator operation amount signal c output from a sensor that detects the amount as a so-called required load, a brake pedal amount signal d output from a sensor that detects a depression amount of the brake pedal, and an intake passage 3 (particularly, in the surge tank 33) An intake air temperature / intake pressure signal e output from an intake air temperature / intake pressure sensor that detects intake air temperature and intake pressure, a cooling water temperature signal f output from a water temperature sensor that detects a cooling water temperature of the internal combustion engine, an intake camshaft or exhaust Cam angle signal g output from the cam angle sensor at a plurality of cam angles of the camshaft, indicating the state of charge of the battery 62 Battery state signal h or the like to be output from the sensor for detecting the index (battery current and / or battery voltage) is input.

  From the output interface, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, an opening operation signal l for the VSV 73, and the like. Output.

  The processor of the ECU 0 interprets and executes a program stored in the memory in advance, calculates operation parameters, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, and h necessary for operation control of the internal combustion engine via the input interface, knows the engine speed, and is filled in the cylinder 1. Estimate the intake volume. Based on the engine speed, the intake air amount, and the like, various operating parameters such as required fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, and the like are determined. . The ECU 0 applies various control signals i, j, k, and l corresponding to the operation parameters via the output interface.

Therefore, in the present embodiment, the following control is performed under a situation where supercharging by the exhaust turbocharger is performed in a transition period in which the internal combustion engine is accelerated. That is, when the rising speed of the intake pressure p filled in the cylinder 1 is equal to or higher than a predetermined value, when the intake pressure p approaches the target intake pressure p ₀ in the process of increasing the intake pressure p, the opening θ of the throttle valve 32 is set. Temporarily reduce the opening degree θ ₀ corresponding to the required load by a predetermined amount, and then gradually increase the opening degree θ ₀ corresponding to the required load so that the intake pressure becomes the target intake pressure p _0. Control to manipulate the opening of the waste gate valve 44 is performed. More specifically, after the opening degree θ of the throttle valve 32 is once reduced below the opening degree θ ₀ corresponding to the required load, the opening degree θ of the throttle valve 32 becomes the opening degree θ ₀ corresponding to the required load. Thus, the operation of gradually increasing the opening degree of the waste gate valve 44 by reducing the opening degree of the VSV 73 and increasing the pressure of the diaphragm chamber 61 of the actuator 6 is performed in parallel. A predetermined area of the memory of the ECU 0 stores a valve control program for performing the above-described control by being executed by the processor. Here, in the present embodiment, “approaching the target intake pressure p ₀ ” means the absolute value of the difference between the actual measured value p of the intake pressure corresponding to the intake air temperature / intake pressure signal e and the target intake pressure p _0. Is below the threshold Δp ₀ . The target intake pressure p ₀ is an amount determined using at least the required load and the engine speed as parameters. In the memory of the ECU ₀ , map data that prescribes the relationship between the required load, the engine speed, and the target intake pressure p ₀ is stored. Further, the memory of the ECU 0 stores map data that defines the relationship between the opening θ of the throttle valve 32 and the predetermined amount that decreases the opening θ of the throttle valve 32 in advance. The predetermined amount is determined by referring to this map immediately before the control for reducing θ is performed. The valve control program is executed when a sudden increase in the intake air amount is predicted, more specifically, when the change amount per unit time of the accelerator pedal depression amount indicated by the accelerator operation amount signal c exceeds a predetermined value. Is done.

  The control procedure by this valve control program will be described below with reference to FIG. 2 which is a flowchart.

When the rising speed of the intake pressure p is greater than or equal to a predetermined value (S1), if the absolute value of the difference between the intake pressure p and the target intake pressure p ₀ falls below the threshold value Δp ₀ (S2), the throttle valve at that time The reduction degree of the opening degree θ is determined using the opening degree of 32 as a parameter (S3), and an operation for reducing the opening degree θ of the throttle valve 32 is performed (S4). Next, until the opening degree θ of the throttle valve 32 reaches the opening degree θ ₀ corresponding to the required load (S5), the opening degree θ of the throttle valve 32 is gradually increased (S6), and the intake pressure becomes the target intake pressure p _0. The opening degree of the waste gate valve 44 is gradually enlarged by gradually reducing the opening degree of the VSV 73 so as to become (S7).

Hereinafter, the effect | action by the control mentioned above is described, referring FIG. When the accelerator pedal is depressed to accelerate the internal combustion engine (time t ₁ ) and the accelerator operation amount and the opening θ of the throttle valve 32 reach the maximum (time t ₂ ), the exhaust amount also increases in response to the increase in the intake amount. increasing, in response to the workload of the exhaust turbocharger is increased, the pressure of the intake air is filled into the cylinder 1 at a later time from the time t ₂ increases rapidly. In the process, when the absolute value of the difference between the intake pressure p and the target intake pressure p ₀ falls below the threshold value Δp ₀ (time t ₃ ), the opening degree θ of the throttle valve 32 is rapidly reduced. At this time, the rising speed of the intake pressure p rapidly decreases. Thereafter, the opening degree θ of the throttle valve 32 gradually increases until the opening degree θ ₀ corresponding to the required load is reached. Note that the enlargement speed of the opening θ is high immediately after the opening θ is reduced, and decreases as time passes. On the other hand, the opening degree of the VSV 73 is reduced contrary to the increase of the opening degree θ of the throttle valve 32, and the opening degree of the waste gate valve 44 is increased accordingly. When the opening degree of the throttle valve 32 reaches the opening degree θ ₀ corresponding to the required load, the opening degree of the VSV 73 (and the opening degree of the waste gate valve 44) becomes constant. Meanwhile, the intake pressure p is maintained near the target intake pressure p ₀ .

As described above, according to the present embodiment, the throttle located closer to the cylinder 1 than the waste gate valve 44 when the target intake pressure p ₀ is approached in the process of increasing the pressure of the intake air charged in the cylinder. Since the control for temporarily reducing the opening degree of the valve 32 is executed, an increase in the intake pressure can be quickly suppressed. Therefore, acceleration performance can be ensured while preventing the occurrence of overshoot. Further, since the opening degree θ of the throttle valve 32 is once reduced, the opening degree θ is gradually increased so as to become the opening degree θ ₀ corresponding to the required load, thereby suppressing the occurrence of pumping loss due to the reduction in the opening degree of the throttle valve 32. You can also.

  Further, the larger the opening degree θ of the throttle valve 32 immediately before performing the control for temporarily reducing the opening degree θ of the throttle valve 32, the larger the reduction amount of the opening degree θ of the throttle valve 32 in the control. In addition, overshooting of the intake pressure p can be prevented more accurately.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, when the absolute value of the difference between the actually measured value of the intake pressure and the target intake pressure falls below the threshold value, the operation of reducing the opening of the throttle valve is performed. An operation of reducing the opening of the throttle valve may be performed when the ratio of the actually measured pressure value to the target intake pressure exceeds a predetermined value (less than 1). That is, “approaching the target intake pressure” not only means that the absolute value of the difference between the measured value of the intake pressure and the target intake pressure is below a predetermined pressure difference, but also the measured value of the intake pressure with respect to the target intake pressure. It is also a concept that includes a ratio exceeding a predetermined value (less than 1).

  In the above-described embodiment, the amount of reduction of the throttle valve opening in the control is increased as the throttle valve opening immediately before the control for temporarily reducing the throttle valve opening is increased. When performing control for temporarily reducing the opening degree of the throttle valve, other aspects such as an aspect in which the opening degree of the throttle valve is always reduced by a predetermined amount may be adopted.

  Further, in the above-described embodiment, the waste gate valve is driven by the actuator having the diaphragm chamber and the constant pressure chamber. However, the waste gate valve is formed by using a solenoid valve, or the like. A waste gate valve may be employed.

  In addition, various changes may be made without departing from the spirit of the present invention.

0 ... Control unit (ECU)
DESCRIPTION OF SYMBOLS 1 ... Cylinder 32 ... Throttle valve 44 ... Waste gate valve 5 ... Exhaust turbocharger

Claims (2)

An internal combustion engine controlled by an exhaust turbocharger,
When supercharging by the exhaust turbocharger is performed, when the target intake pressure is approached while the pressure of the intake air charged in the cylinder rises, the throttle valve opening is once opened corresponding to the required load. A control device for an internal combustion engine that manipulates the opening degree of the waste gate valve so that the intake pressure becomes the target intake pressure while gradually reducing the degree to a degree corresponding to the required load. 2. The control device for an internal combustion engine according to claim 1, wherein the amount of reduction of the opening degree of the throttle valve in the control is increased as the opening degree of the throttle valve immediately before performing the control for temporarily reducing the opening degree of the throttle valve is increased.

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