JP2008255861A - Intake control method for internal combustion engine and device thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which it is difficult to inexpensively specify a knocking occurrence position in a combustion chamber of an internal combustion engine. <P>SOLUTION: An intake control device for the internal combustion engine provided with a tumble control valve for adjusting intensity of tumble flow of air fuel mixture in the combustion chamber, a valve opening set part 28 setting opening of the tumble control valve according to an operation condition of the internal combustion engine, and a valve actuator 27 changing opening of the tumble control valve to opening set by the same, is provided with a cylinder pressure sensor 32 for detecting pressure change in the combustion chamber, a waveform analysis part 33 analyzing pressure change in the combustion chamber detected by the same, and a knocking position estimation part 34 estimating knocking occurrence position based on pressure change analyzed by the same. The valve opening set part 28 sets opening of the tumble control valve according to the knocking occurrence position estimated by the knock position estimation part 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an intake control method and an apparatus for suppressing the occurrence of knocking by adjusting the strength of a tumble flow of an air-fuel mixture in a combustion chamber of an internal combustion engine.

  In knocking (self-ignition), at the end of the combustion period when the combustion speed of the air-fuel mixture in the combustion chamber of the internal combustion engine decreases, the unburned air-fuel mixture compressed between the flame surface and the inner wall of the cylinder reaches the self-ignition condition. It is a phenomenon that ignites independently from the flame surface. In particular, in a spark ignition internal combustion engine, the flame propagation speed on the exhaust port side where the temperature in the combustion chamber is high increases, so that knocking tends to occur near the cylinder inner wall on the intake port side. When knocking occurs, it is difficult to advance the ignition advance angle of the internal combustion engine, which is a great obstacle when attempting to increase the output.

  In order to suppress the occurrence of such knocking, generally, the ignition timing is shifted to the retard side, or a plurality of ignition plugs are provided to promote combustion of the air-fuel mixture. In addition, Patent Document 1 and Patent Document 2 propose techniques for controlling the tumble flow of the air-fuel mixture in the combustion chamber in order to prevent knocking. In Patent Document 1, when engine knocking is detected by a knocking sensor, intake air is passed through a heat exchanger, heated, and then introduced into the combustion chamber, and the tumble control valve is driven to a closed position to mix in the combustion chamber. It is controlled so that the tumble flow of qi is strong. Further, Patent Document 2 uses knock generation data from a knock sensor to prevent the occurrence of knocking when the tumble control valve is switched between closed and open.

  Further, as a method for specifying the knocking occurrence position in the combustion chamber, it is also considered to arrange a plurality of pressure sensors, electric field sensors, or optical sensors so as to face the combustion chamber.

JP 10-339219 A Japanese Patent Laid-Open No. 9-42131

  If the ignition timing is shifted to the retarded side, the output of the internal combustion engine may decrease, fuel consumption may deteriorate, and the exhaust temperature may increase, causing thermal damage to the catalyst incorporated in the exhaust passage. is there. In addition, the provision of a plurality of ignition devices has a problem that the valve mechanism and the like are already arranged at a high density in the cylinder head, which is very difficult in terms of space and increases the cost of parts.

  In Patent Documents 1 and 2, since a knock sensor is used, it is basically impossible to grasp where knocking occurs in the combustion chamber. For this reason, it is necessary to make some association with knocking as to how to control the tumble flow, and there is a drawback that the control for that is complicated.

  In order to identify the position where knocking occurs in the combustion chamber, it is very difficult to arrange a plurality of sensors for each cylinder in a cylinder head in which valve mechanisms and the like are arranged at high density. There is a problem that costs increase. Further, in the case of an optical sensor, its detection part becomes dirty and changes its detection characteristics, so that it cannot be used for a long time.

  It is an object of the present invention to provide an intake control method and apparatus capable of estimating the occurrence position of knocking and thereby changing the strength of the tumble flow relatively easily and at low cost so that knocking is less likely to occur. There is.

  According to a first aspect of the present invention, an in-cylinder pressure sensor is arranged at a symmetrical position in a plane perpendicular to an axis of a cylinder surrounding the combustion chamber with respect to a tumble flow of an air-fuel mixture to be formed in the combustion chamber of the internal combustion engine. Detecting a first pressure wave that directly reaches the in-cylinder pressure sensor from a knocking occurrence position in the combustion chamber, detecting a pressure wave reflected by an inner wall of the combustion chamber from the knocking occurrence position in the combustion chamber, A step of estimating the distance from the position where the in-cylinder pressure sensor is installed to the knocking occurrence position from the pressure wave of the cylinder and the reflected pressure wave, And a step of changing the strength of the tumble flow of the air-fuel mixture in the internal combustion engine.

  According to a second aspect of the present invention, there is provided a tumble control valve that is arranged in the intake passage of the internal combustion engine and adjusts the strength of the tumble flow of the air-fuel mixture in the combustion chamber, and the opening degree of the tumble control valve is determined by the vehicle. An internal combustion engine comprising: a valve opening setting unit that is set according to the operating state of the engine; and a valve actuator that switches the opening of the tumble control valve so as to be the opening set by the valve opening setting unit. An in-cylinder control device that detects a pressure change in the combustion chamber, a waveform analysis unit that analyzes the pressure change in the combustion chamber detected by the cylinder pressure sensor, and an analysis by the waveform analysis unit A knock position estimator for estimating a knocking occurrence position based on the generated pressure change, and the valve opening setting unit is configured to control the tumble control valve according to the knocking occurrence position estimated by the knock position estimation unit. of It is characterized in that setting the degree.

  In the present invention, the pressure wave reflected by the inner wall of the combustion chamber near the opposite side of the knocking position does not form a simple focus due to the propagation characteristics of the pressure wave caused by the knocking generated near the inner wall of the combustion chamber. A plurality of reflected waves are generated. Accordingly, when knocking occurs at a position far from the in-cylinder pressure sensor, the in-cylinder pressure sensor has a first pressure wave that reaches the in-cylinder pressure sensor directly from the knocking occurrence position (hereinafter referred to as a primary pressure wave), A plurality of pressure waves reflected on the inner wall of the combustion chamber (hereinafter referred to as secondary or higher pressure waves) arrive in sequence. On the other hand, when knocking occurs in the vicinity of the in-cylinder pressure sensor, the reflected wave from the inner wall of the combustion chamber after the first primary pressure wave, that is, the secondary or higher pressure wave, is approximately equal to the diameter of the combustion chamber. During reciprocation, it is not detected by the cylinder pressure sensor. Therefore, the relationship between the in-cylinder sensor and the knocking occurrence position can be almost determined by analyzing the interval between the primary pressure wave and the pressure wave after the secondary, and the waveform of the secondary and higher pressure waves. . Using this result, the opening degree of the tumble control valve is adjusted based on the previously determined tumble strength and flame propagation direction characteristics so that the flame toward the knocking occurrence side becomes faster.

  In the intake control device for an internal combustion engine according to the second aspect of the present invention, the knock position estimation unit reflects the primary pressure wave that directly reaches the in-cylinder pressure sensor from the knocking occurrence position and the inner wall of the combustion chamber to the in-cylinder pressure sensor. The occurrence position of knocking may be estimated based on at least one of the time difference from the reaching second-order or higher-order pressure wave and the waveform thereof.

  In addition, it is preferable that the in-cylinder pressure sensor is disposed at a symmetrical position on a plane orthogonal to the axis of the cylinder surrounding the combustion chamber with respect to the tumble flow of the air-fuel mixture to be formed in the combustion chamber. In particular, it is effective to dispose the in-cylinder pressure sensor close to the intake valve seat or the exhaust valve seat.

  According to the intake control method of the present invention, an in-cylinder pressure sensor is disposed at a symmetrical position in a plane perpendicular to the axis of a cylinder surrounding the combustion chamber with respect to the tumble flow of the air-fuel mixture to be formed in the combustion chamber of the internal combustion engine, and the combustion A first pressure wave that directly reaches the in-cylinder pressure sensor from the knocking occurrence position in the chamber is detected, a pressure wave reflected on the inner wall of the combustion chamber from the knocking occurrence position in the combustion chamber is detected, and the first pressure wave is reflected. From the pressure wave, the distance from the position where the in-cylinder pressure sensor is installed to the knocking position is estimated, and the strength of the tumble flow of the air-fuel mixture in the combustion chamber depends on the distance from the position where the in-cylinder pressure sensor is installed to the knocking position The position of knocking can be easily estimated using only a single in-cylinder pressure sensor, and the air-fuel mixture that does not cause knocking in the combustion chamber can be estimated. It is possible to form a tumble flow.

  According to the intake control device of the present invention, an in-cylinder pressure sensor for detecting a pressure change in the combustion chamber, a waveform analysis unit for analyzing the pressure change in the combustion chamber detected by the in-cylinder pressure sensor, and the waveform analysis unit A knock position estimator for estimating the knocking occurrence position based on the pressure change analyzed in accordance with the knock position estimation unit. Therefore, a tumble flow of the air-fuel mixture that does not cause knocking in the combustion chamber can be formed.

  At least one of the time difference between the primary pressure wave that directly reaches the in-cylinder pressure sensor from the knocking occurrence position and the secondary or higher-order pressure wave that reflects from the inner wall of the combustion chamber and reaches the in-cylinder pressure sensor, and the waveform thereof Based on the above, when the knock position estimation unit estimates the knocking occurrence position, the knocking occurrence position can be easily estimated using only a single in-cylinder pressure sensor.

  When the cylinder pressure sensor is placed at a symmetrical position in a plane perpendicular to the axis of the cylinder surrounding the combustion chamber, the proximity of the intake valve seat or the exhaust valve seat to the tumble flow of the mixture to be formed in the combustion chamber When the in-cylinder pressure sensor is arranged, it is possible to suppress the occurrence of knocking simply by estimating the distance from the in-cylinder pressure sensor to the occurrence position of knocking and controlling the strength of the tumble flow, The process for estimating the knocking occurrence position can be simplified.

  An embodiment in which the present invention is applied to a spark ignition engine will be described in detail with reference to FIGS. 1 to 6. However, the present invention is not limited to such an embodiment, and other embodiments belonging to the spirit of the present invention. It can also be applied to any of these technologies.

  The cross-sectional structure of the main part in this embodiment is schematically shown in FIG. 1, and its main control block is shown in FIG. That is, the engine 10 according to the present embodiment injects gasoline, alcohol, a mixture thereof, liquefied natural gas, or the like as fuel into the intake port 12 from the fuel injection valve 11 and mixes it with air. 14 is ignited within 14. It is also possible to employ a direct injection type fuel injection valve that directly injects fuel into the combustion chamber 14 instead of the port injection type fuel injection valve 11. A cylinder head 18 defining a combustion chamber 14 is attached to the cylinder block 17 in which a cylinder 16 into which the piston 15 is slidably fitted is formed. The cylinder head 18 is formed with a pair of intake ports 12 defining an intake passage and a pair of exhaust ports 19 defining an exhaust passage so as to face the combustion chamber 14. And the circular opening end of the exhaust port 19 is an intake valve 21 that reciprocates at a predetermined timing in conjunction with the reciprocating motion of the piston 15, that is, the rotational motion of a crankshaft (not shown) connected to the piston 15 via the connecting rod 20. The exhaust valve 22 is opened and closed.

  A fuel injection valve 11 for injecting fuel into the intake port 12 is also attached to the cylinder head 18, and fuel is injected into the intake port 12 at a predetermined timing in conjunction with the reciprocating motion of the piston 15. It is sent to the combustion chamber 14 together with the flowing intake air. The fuel injection amount from the fuel injection valve 11 is set by a fuel injection amount setting unit 24 incorporated in the ECU 23 according to the operating state of the engine 10 based on information from various sensors (not shown).

  A tumble control valve 26 for adjusting the strength of the tumble flow of the air-fuel mixture in the combustion chamber 14 is attached to the end of the intake pipe 25 connected to the intake port 12 of the cylinder head 18. In the present embodiment, the intake pipe 25 has a substantially rectangular cross section, and accordingly, the connection end portion of the intake port 12 with the intake pipe 25 is also an open end of the rectangular cross section. A tumble control valve 26 having a rectangular plate shape is pivotally supported at its base end located on the upstream side of the intake passage with respect to the intake pipe 25, and a valve actuator 27 such as a stepping motor controls the tumble control. Connected to the valve 26. The opening degree of the tumble control valve 26 is set by the valve opening degree setting unit 28 of the ECU 23 in accordance with the driving state of the vehicle, and the valve opening degree is set to the valve opening degree set by the valve opening degree setting unit 28. The operation of the actuator 27 is controlled by the ECU 23. By changing the valve opening, that is, by changing the cross-sectional area of the intake passage between the tip of the tumble control valve 26 and the intake pipe 25, the tumble of the air-fuel mixture flowing from the intake port 12 into the combustion chamber 14 is changed. The strength of the flow, that is, the swirl flow around the axis parallel to the plane perpendicular to the axis of the cylinder 16 in the combustion chamber 14 can be adjusted. More specifically, the result is that the flow rate of the intake air passing through the tumble control valve 26 increases as the tumble control valve 26 is rotated so as to protrude into the intake passage from the fully open position indicated by the two-dot chain line in FIG. The tumble flow of the air-fuel mixture formed in the combustion chamber 14 tends to increase.

  The shape of the intake port 12 and the configuration of the tumble control valve 26 are not limited to the present embodiment, and conventionally known ones can be appropriately employed.

  An ignition plug 13 is also attached to the previous cylinder head 18, and the ignition gap 29 is arranged so as to face the center of the combustion chamber 14 in a state surrounded by the open ends of the intake port 12 and the exhaust port 19. ing. A high voltage is applied to the ignition gap 29 of the spark plug 13 through the ignition coil 30 at a predetermined timing in conjunction with the rotational movement of the crankshaft so as to ignite the fuel contained in the air-fuel mixture. It has become. The energization timing for the ignition coil 30 is set by the ignition timing setting unit 31 of the ECU 23 according to the operating state of the engine 10 based on detection information from various sensors (not shown).

  Further, an in-cylinder pressure sensor 32 for detecting a pressure change in the combustion chamber 14 is also mounted on the cylinder head 18, and a signal detected by the in-cylinder pressure sensor 32 is output to the ECU 23. In this embodiment, knocking is performed. It is used to estimate the occurrence position of The in-cylinder pressure sensor 32 in the present embodiment is disposed in a state of facing the outer peripheral edge of the combustion chamber 14 so as to be sandwiched between the opening ends of the pair of intake ports 12, but the opening ends of the pair of exhaust ports 19. It is also effective to arrange the combustion chamber 14 so as to face the outer peripheral edge of the combustion chamber 14. Further, by providing the second and third in-cylinder pressure sensors, it is possible to estimate the occurrence position of knocking with higher accuracy. However, in order to minimize the expensive in-cylinder pressure sensor 32, 1 is provided for each cylinder. It is desirable to incorporate one in-cylinder pressure sensor 32.

  The control block of this embodiment is shown in FIG. The above-described ECU 23 is configured to operate the fuel injection valve 11 and the ignition so that the engine 10 can be smoothly operated according to a preset program based on detection information from the above-described in-cylinder pressure sensor 32 and various sensors (not shown). The operation of the coil 30 and the like is controlled. The ECU 23 in the present embodiment also has a function of estimating the knocking occurrence position in the combustion chamber 14 and adjusting the strength of the tumble flow in the combustion chamber 14 based on this to suppress the occurrence of knocking. Yes. Therefore, in addition to the valve opening setting unit 28 described above, the waveform analysis unit 33 that analyzes the pressure change in the combustion chamber 14 detected by the in-cylinder pressure sensor 32 and the pressure change that is analyzed by the waveform analysis unit 33 And a knock position estimation unit 34 for estimating the occurrence position of knocking based on the above.

FIG. 3 schematically shows the situation when knocking occurs at a position close to the in-cylinder pressure sensor 32, and the detected waveform of the in-cylinder pressure sensor 32 analyzed by the waveform analysis unit 33 at this time is schematically shown in FIG. Show. FIG. 5 schematically shows a situation where knocking occurs at a position far from the in-cylinder pressure sensor 32, and the detected waveform of the in-cylinder pressure sensor 32 analyzed by the waveform analysis unit 33 at this time is schematically shown in FIG. Indicate. In any case, the primary pressure wave W ₁ indicated by the solid line arrow first reaches the in-cylinder pressure sensor 32 from the knocking generation point P, and then the secondary and subsequent lines indicated by the broken line arrows reflected by the inner wall of the combustion chamber 14. The pressure waves W _{n of the first and second} waves arrive sequentially. However, when knocking occurs at a position near the in-cylinder pressure sensor 32, a long distance between the primary pressure wave W ₁ and the secondary pressure wave W ₂ than when knocking occurs at a position farther in the cylinder pressure sensor 32 Tend to be. In addition, when knocking occurs at a position far from the in-cylinder pressure sensor 32, the secondary and subsequent pressure waveforms tend to be more complicated than when knocking occurs at a position near the in-cylinder pressure sensor 32. Therefore, by calculating the interval T between the primary pressure wave W ₁ and the secondary pressure wave W ₂ or analyzing the waveform of the pressure wave W _n after the secondary, the knocking occurrence point from the mounting position of the in-cylinder pressure sensor 32. It is possible to estimate the distance to P. Although the actual distance varies depending on the speed of sound, the combustion chamber 14 is almost filled with the air-fuel mixture at the time of occurrence of knocking, and the combustion immediately before the occurrence of knocking is based on the operating state of the engine 10 and the detection signal from the in-cylinder pressure sensor 32. From the absolute value of the pressure in the chamber 14, it is possible to estimate the temperature and speed of sound in the combustion chamber 14 using the gas equation of state.

Waveform analysis portion 33, the general filtering to remove noise components 4 due, the primary pressure wave W ₁ and the secondary and subsequent subsequent as shown in FIG. 6 higher pressure wave W _n of waveform Ask for.

In addition, the knock position estimating unit 34 in the present embodiment detects the secondary pressure wave W ₂ within a predetermined time set according to the operating state of the engine 10 after the primary pressure wave W ₁ , for example, within 6 microseconds. If not, it is estimated that knocking occurs at a position close to the in-cylinder pressure sensor 32. On the other hand, if the secondary pressure wave W ₂ is detected within a predetermined time set in accordance with the operating state of the engine 10, for example, 3 microseconds, following the primary pressure wave W ₁ , it is far from the in-cylinder pressure sensor 32. It is estimated that knocking has occurred at the position. Other than this, it is estimated that knocking occurs at these intermediate points. Although this method cannot determine whether the knocking occurrence point P is in the left-right direction (vertical direction in FIGS. 3 and 5) with respect to the in-cylinder pressure sensor 32, in this embodiment, the intake / exhaust valve 21, Since the arrangement of 22 is set symmetrically, the symmetrical tumble flow contacting the opening end of the pair of intake ports 12 and the opening end of the exhaust port 19 may be controlled, and there is no particular problem with respect to the above points.

  The previous valve opening setting unit 28 also has a function of setting the opening of the tumble control valve 26 according to the knocking occurrence point P estimated by the knock position estimating unit 34. For this reason, the relationship between the knocking occurrence point P and the strength of the tumble flow is obtained in advance in accordance with the characteristics of the engine 10 used together with the structure of the intake port 12 and the like, and this is converted into data and the valve opening degree of the ECU 23 is obtained. It is incorporated in the setting unit 28. Therefore, based on the knocking occurrence position estimated by the knock position estimation unit 34, the valve opening degree corresponding to the knocking occurrence point P is set by the valve opening degree setting unit 28, and the valve actuator 27 is set to the set opening degree. The opening degree of the tumble control valve 26 is changed so that

  In the present embodiment, the opening degree of the tumble control valve 26 is narrowed so that the tumble flow of the air-fuel mixture in the combustion chamber 14 becomes stronger as the knocking generation point P is farther from the attachment position of the in-cylinder pressure sensor 32. On the contrary, the opening degree of the tumble control valve 26 is made closer to the fully open state so that the tumble flow of the air-fuel mixture in the combustion chamber 14 becomes weaker as the knocking generation point P is closer to the mounting position of the in-cylinder pressure sensor 32. However, it should be noted that these relationships may be reversed depending on the structure of the engine 10 and the intake and exhaust ports 12 and 19 as described above.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

It is a conceptual diagram showing the principal part of one Embodiment of the intake control device of the internal combustion engine by this invention. FIG. 2 is a control block diagram in the embodiment shown in FIG. 1. It is a principle figure showing typically an example in which knocking occurred in a combustion chamber. FIG. 4 is a waveform diagram schematically showing a detection waveform by an in-cylinder pressure sensor in the state shown in FIG. 3. It is a principle figure showing typically another example in which knocking occurred in a combustion chamber. FIG. 6 is a waveform diagram schematically showing a detection waveform by an in-cylinder pressure sensor in the state shown in FIG. 5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Fuel injection valve 12 Intake port 13 Spark plug 14 Combustion chamber 15 Piston 16 Cylinder 17 Cylinder block 18 Cylinder head 19 Exhaust port 20 Connecting rod 21 Intake valve 22 Exhaust valve 23 ECU
DESCRIPTION OF SYMBOLS 24 Fuel injection amount setting part 25 Intake pipe 26 Tumble control valve 27 Valve actuator 28 Valve opening setting part 29 Ignition gap 30 Ignition coil 31 Ignition timing setting part 32 In-cylinder pressure sensor 33 Waveform analysis part 34 Knock position estimation part P Knock generation | occurrence | production point W ₁ primary pressure wave W ₂ secondary pressure wave W _n pressure wave after secondary T interval between primary pressure wave and secondary pressure wave

Claims (5)

Disposing an in-cylinder pressure sensor at a symmetrical position in a plane perpendicular to an axis of a cylinder surrounding the combustion chamber with respect to a tumble flow of the air-fuel mixture to be formed in the combustion chamber of the internal combustion engine;
Detecting a first pressure wave that directly reaches the in-cylinder pressure sensor from a knocking occurrence position in the combustion chamber;
Detecting a pressure wave reflected on the inner wall of the combustion chamber from a knocking occurrence position in the combustion chamber;
Estimating a distance from an arrangement position of the in-cylinder pressure sensor to a knocking occurrence position from the first pressure wave and the reflected pressure wave;
An intake control method for an internal combustion engine, comprising: changing a strength of a tumble flow of an air-fuel mixture in a combustion chamber according to a distance from an installation position of an in-cylinder pressure sensor to a knocking occurrence position. A tumble control valve that is arranged in the intake passage of the internal combustion engine and adjusts the strength of the tumble flow of the air-fuel mixture in the combustion chamber, and the valve opening that sets the opening of the tumble control valve according to the operating state of the vehicle An intake control device for an internal combustion engine comprising a setting unit and a valve actuator for switching the opening of the tumble control valve so as to be the opening set in the valve opening setting unit,
An in-cylinder pressure sensor for detecting a pressure change in the combustion chamber;
A waveform analyzer for analyzing the pressure change in the combustion chamber detected by the in-cylinder pressure sensor;
A knock position estimator for estimating a knocking occurrence position based on the pressure change analyzed by the waveform analyzer, and the valve opening setting unit is configured to generate the knock estimated by the knock position estimator. An intake control device for an internal combustion engine, wherein an opening degree of a tumble control valve is set according to a position.   The knock position estimator includes a primary pressure wave that directly reaches the in-cylinder pressure sensor from a knocking occurrence position and a secondary or higher order pressure wave that is reflected by the inner wall of the combustion chamber and reaches the in-cylinder pressure sensor. The intake control apparatus for an internal combustion engine according to claim 2, wherein the occurrence position of knocking is estimated based on at least one of the time difference and its waveform.   The in-cylinder pressure sensor is arranged at a symmetrical position in a plane orthogonal to an axis of a cylinder surrounding the combustion chamber with respect to a tumble flow of the air-fuel mixture to be formed in the combustion chamber. An intake control device for an internal combustion engine according to claim 3.   The intake control apparatus for an internal combustion engine according to claim 4, wherein the in-cylinder pressure sensor is disposed in the vicinity of an intake valve seat or an exhaust valve seat.

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