JP2005163730A - Knocking suppression method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in a conventional knocking suppression method wherein reduction itself of combustion speed of air-fuel mixture at combustion later time for combustion initial time cannot be improved and knocking prevention effect is reduced in inverse proportion to increase in compression ratio and intake efficiency of intake of an internal combustion engine. <P>SOLUTION: This knocking suppression device is provided with an ignition plug 25 in which an ignition gap 24 is arranged in a central part in the radial direction of a combustion chamber 14 of the internal combustion engine and a high pressure gas injection valve 17 arranged in an outer peripheral end part of the combustion chamber 14 so that it is positioned most apart from an exhaust port 17 opened in the combustion chamber 14 and having a nozzle 26 for injecting high pressure gas along an inner peripheral wall of a cylinder 12 surrounding the combustion chamber 14 immediately after ignition of the ignition plug 25. Turbulent flow by high pressure gas in the combustion chamber 14 is generated at combustion later time to control propagation of flame and avoid occurrence of knocking. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a knocking suppression method and apparatus for a spark ignition internal combustion engine.

  At the end of the combustion period when the combustion speed of the mixture in the combustion chamber of the internal combustion engine decreases, knocking occurs when the unburned mixture compressed between the flame surface and the inner wall of the cylinder reaches a self-ignition condition, It is a phenomenon that ignites independently. 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. The occurrence of knocking makes it difficult to advance the ignition advance angle of the internal combustion engine, and cannot increase the output.

  In order to prevent such knocking, use a high-octane fuel with high anti-knock properties, use a fuel with a large combustion speed, such as hydrogen, reduce the cylinder bore diameter to shorten the flame propagation distance, As described in Patent Documents 1 and 2, the combustion speed is increased by increasing the turbulence of the intake air flow, and further, as described in Patent Document 1, fuel is directly injected into the combustion chamber. Thus, fuel is vaporized in the combustion chamber, thereby lowering the intake air temperature.

JP-A-10-331642 JP-A-1-170713

  In the conventional knocking prevention method described above, not only the late stage of combustion in which combustion has progressed to 10 to 90%, where combustion is substantially likely to occur after the start of combustion, but also combustion in which combustion has progressed by about 10% since the start of combustion. Similarly, the knocking prevention effect can be obtained in the initial stage.

  However, if the combustion rate of the mixture in the combustion chamber is increased, for example, even if the combustion rate of the mixture is increased in the later stage of combustion, the combustion rate of the mixture in the later stage of combustion with respect to the combustion rate of the mixture in the early stage of combustion The decline itself cannot be improved and is not a fundamental measure.

  Further, the conventional method tends to have a poor knock prevention effect in inverse proportion to the increase in the compression ratio of the internal combustion engine and the intake efficiency of the intake air.

  According to a first aspect of the present invention, an air-fuel mixture is formed by supplying air and fuel into a combustion chamber of an internal combustion engine, and an ignition plug having an ignition gap disposed at a radial center portion of the combustion chamber is ignited. And burning the air-fuel mixture in the combustion chamber and flowing the air-fuel mixture intervening in the vicinity of the inner peripheral wall of the cylinder surrounding the combustion chamber along the inner peripheral wall of the cylinder during the combustion of the air-fuel mixture. There is a knocking suppression method characterized by the above.

  In the present invention, air and fuel are supplied into the combustion chamber of the internal combustion engine to form an air-fuel mixture, and a spark plug having an ignition gap arranged at the radial center of the combustion chamber is ignited. To burn. During the combustion of the air-fuel mixture, the air-fuel mixture intervening in the vicinity of the inner peripheral wall of the cylinder surrounding the combustion chamber flows along the inner peripheral wall of the cylinder, thereby increasing the turbulent flow of the unburned air-fuel mixture and causing combustion. A decrease in the combustion rate in the latter period is suppressed. Further, the flow of the air-fuel mixture suppresses the occurrence of knocking by the propagation of a flame from the intake port side along the inner peripheral wall of the cylinder.

  In the knocking suppression method according to the first aspect of the present invention, the step of causing the air-fuel mixture to flow along the inner peripheral wall of the cylinder blows high-pressure gas into the combustion chamber, and the high-pressure gas flows along the inner peripheral wall of the cylinder surrounding the combustion chamber. And having a fluidized step. In this case, the step of blowing the high-pressure gas into the combustion chamber may be performed from a position farthest from the exhaust port that opens to the combustion chamber, and the high-pressure gas flows along the inner peripheral wall of the cylinder in opposite directions. And a step of flowing toward the exhaust port side.

  The step of blowing high-pressure gas into the combustion chamber may be performed immediately after ignition of the spark plug.

  According to a second aspect of the present invention, there is provided an ignition plug in which an ignition gap is arranged at a radial center portion of a combustion chamber of an internal combustion engine, and the combustion chamber so as to be positioned farthest from an exhaust port opening to the combustion chamber. A knocking suppression device comprising a high-pressure gas injection valve having a nozzle that is arranged at an outer peripheral end and injects high-pressure gas along an inner peripheral wall of a cylinder surrounding the combustion chamber.

  In the present invention, when the high pressure gas injection valve is operated, a high pressure gas of, for example, 10 MPa or more is injected from the nozzle, flows to the exhaust port side along the inner peripheral wall of the cylinder surrounding the combustion chamber, and is in an unburned state. The turbulent flow of the air-fuel mixture is increased, and the reduction of the combustion speed in the late combustion stage is suppressed. Further, the flow of the high-pressure gas suppresses the occurrence of knocking by the propagation of a flame from the intake port side along the inner peripheral wall of the cylinder.

  In the knocking suppression device according to the second aspect of the present invention, it is effective to inject high-pressure gas from the high-pressure gas injection valve immediately after ignition of the ignition plug.

  The nozzle of the high pressure gas injection valve may have two openings that inject high pressure gas in the opposite direction along the inner peripheral wall of the cylinder.

  When the high-pressure gas is compressed air, an air pressurization pump that is driven by rotation of the crankshaft of the internal combustion engine and guides the high-pressure air obtained thereby to the high-pressure gas injection valve can be further provided.

  When the high-pressure gas is hydrogen or an inert gas, a high-pressure tank that stores the high-pressure gas and a pressure-regulating valve that regulates the high-pressure gas supplied from the high-pressure tank to a predetermined pressure and guides the high-pressure gas to the high-pressure gas injection valve are further provided. be able to.

  When the high-pressure gas is water vapor, a water tank for storing water, a water vapor generator for vaporizing the water supplied from the water tank, and the high pressure by adjusting the water vapor generated in the water vapor generator to a predetermined pressure A pressure regulating valve that leads to the gas injection valve can be further provided. In this case, the water vapor generating device may be one in which exhaust gas flowing through the exhaust port is guided and water is vaporized by the exhaust gas.

  According to the knocking suppression method of the present invention, air and fuel are supplied into a combustion chamber of an internal combustion engine to form an air-fuel mixture, and a combustion is performed by igniting a spark plug in which an ignition gap is arranged at the radial center of the combustion chamber. The air-fuel mixture in the chamber is burned, and the air-fuel mixture intervening in the vicinity of the inner peripheral wall of the cylinder surrounding the combustion chamber is caused to flow along the inner peripheral wall of the cylinder during the combustion of the air-fuel mixture. The turbulent flow of the air-fuel mixture increases, suppressing the decrease in the combustion speed in the later stage of combustion and giving no grace to self-ignite the unburned air-fuel mixture, thereby suppressing the occurrence of knocking.

  When the step of flowing the air-fuel mixture along the inner peripheral wall of the cylinder has the step of blowing high pressure gas into the combustion chamber and flowing the high pressure gas along the inner peripheral wall of the cylinder surrounding the combustion chamber, the cylinder surrounding the combustion chamber The air-fuel mixture intervening in the vicinity of the inner peripheral wall can be reliably flowed along the inner peripheral wall of the cylinder.

  When the step of injecting the high pressure gas into the combustion chamber is performed from the position farthest from the exhaust port opening in the combustion chamber, the flow of the high pressure gas to the exhaust port side along the inner peripheral wall of the cylinder causes the intake port side to As a result of the propagation of the flame along the inner peripheral wall of the cylinder, it is possible to further suppress the occurrence of knocking.

  When the step of blowing the high pressure gas into the combustion chamber includes the step of causing the high pressure gas to flow in the opposite directions along the inner peripheral wall of the cylinder toward the exhaust port side, the high pressure gas in a plane perpendicular to the cylinder axis The turbulent flow of the air-fuel mixture in an unburned state interposed along the inner peripheral wall of the cylinder can be increased.

  When the step of blowing the high-pressure gas into the combustion chamber is performed immediately after ignition of the spark plug, it is possible to more reliably suppress a decrease in the combustion speed in the later stage of combustion.

  According to the knocking suppression device of the present invention, the outer peripheral end of the combustion chamber is positioned so as to be located farthest from the spark plug in which the ignition gap is arranged at the radial center of the combustion chamber of the internal combustion engine and the exhaust port that opens to the combustion chamber. A high-pressure gas injection valve having a nozzle that injects high-pressure gas along the inner peripheral wall of the cylinder surrounding the combustion chamber, so that the high-pressure gas surrounds the combustion chamber from the nozzle of the high-pressure gas injection valve It flows to the exhaust port side along the inner peripheral wall of the cylinder, increases the turbulent flow of the unburned mixture, suppresses the decrease in the combustion speed in the late stage of combustion, and does not give the grace to self-ignite the unburned mixture, Thereby, occurrence of knocking is suppressed. In addition, as a result of the flame propagating from the intake port side along the inner peripheral wall of the cylinder due to the flow of the high-pressure gas toward the exhaust port side along the inner peripheral wall of the cylinder, it is possible to further suppress the occurrence of knocking.

  When high-pressure gas is injected from the high-pressure gas injection valve immediately after ignition of the ignition plug, it is possible to more reliably suppress a decrease in the combustion rate in the later stage of combustion.

  When the nozzle of the high-pressure gas injection valve has two openings for injecting high-pressure gas in the opposite directions along the inner peripheral wall of the cylinder, a high-pressure gas circulation flow can be formed in a plane perpendicular to the cylinder axis. It is possible to increase the turbulent flow of the unburned air-fuel mixture interposed along the inner peripheral wall of the cylinder.

  In the case of further comprising an air pressurization pump that is driven by rotation of the crankshaft of the internal combustion engine and guides the high pressure air obtained thereby to the high pressure gas injection valve, the air pressurization pump is operated in conjunction with the operation of the internal combustion engine, High pressure air can be supplied to the high pressure gas injection valve.

  When further comprising a high-pressure tank for storing high-pressure hydrogen or an inert gas and a pressure-regulating valve for regulating the high-pressure gas supplied from the high-pressure tank to a predetermined pressure and leading it to a high-pressure gas injection valve, Regardless of the state, high-pressure hydrogen or inert gas adjusted to a predetermined pressure by the pressure regulating valve can be supplied from the high-pressure gas injection valve to the combustion chamber of the internal combustion engine.

  A water tank for storing water, a steam generator for vaporizing water supplied from the water tank, and a pressure regulating valve for regulating the steam generated by the steam generator to a predetermined pressure and leading it to a high pressure gas injection valve The high-pressure water vapor adjusted to a predetermined pressure by the pressure regulating valve can be supplied from the high-pressure gas injection valve to the combustion chamber of the internal combustion engine. In particular, when the exhaust gas flowing through the exhaust port is guided to the water vapor generator and water is vaporized by the exhaust gas, the exhaust heat of the exhaust gas can be used effectively.

  Embodiments in which the knocking suppression device according to the present invention is applied to a spark ignition internal combustion engine will be described in detail with reference to FIGS. 1 to 5, but the present invention is not limited to these embodiments, and these may be further combined. Any change or modification included in the concept of the present invention described in the claims can be made, and can be naturally applied to any other technology belonging to the spirit of the present invention.

  The schematic structure of the first embodiment of the present invention is shown in FIG. 1, the flow of high-pressure gas in the sectional structure taken along the line II-II is schematically shown in FIG. 2, and the control block is shown in FIG. That is, a cylinder head 15 that defines a combustion chamber 14 is attached to a cylinder block 13 that forms a cylinder 12 into which the piston 11 is slidably fitted.

  In the cylinder head 15, a pair of intake ports 16 and a pair of exhaust ports 17 are formed so as to face the combustion chamber 14, and valve seats 18 are formed at the open ends of the intake ports 16 and the exhaust ports 17. An intake valve 21 and an exhaust valve 22 which are respectively provided and reciprocate at a predetermined timing in conjunction with the reciprocating motion of the piston 11, that is, the rotational motion of the crankshaft 20 connected to the piston 11 via the connecting rod 19. A port 16 and an exhaust port 17 communicate with the combustion chamber 14. A fuel injection valve 23 for injecting fuel into the intake port 16 is also attached to the cylinder head 15, and fuel is injected into the intake port 16 at a predetermined timing in conjunction with the reciprocating motion of the piston 11, that is, the rotational motion of the crankshaft 20. The fuel is injected and sent to the combustion chamber 14 together with the intake air flowing through the intake port 16.

  Further, an ignition plug 25 is attached to the cylinder head 15 so that the ignition gap 24 faces the radial center of the combustion chamber 14. A high voltage is applied to the ignition gap 24 of the spark plug 25 at a predetermined timing in conjunction with the reciprocating motion of the piston 11, that is, the rotational motion of the crankshaft 20, so that the fuel is ignited. .

  Further, the cylinder head 15 is provided with a high-pressure gas injection valve 27 with a nozzle 26 facing the outer peripheral edge of the combustion chamber 14 so as to be positioned on the opposite side of the ignition plug 25 with the intake valve 21 therebetween. The nozzle 26 of the high-pressure gas injection valve 27 injects high-pressure air in the opposite direction along the inner peripheral wall of the combustion chamber 14 from a position farthest from the exhaust port 17 as indicated by an arrow in FIG. Two injection holes (not shown) are provided. An air pressurizing pump 28 for supplying high-pressure air to the high-pressure gas injection valve 27 is connected to the crankshaft 20 via a toothed belt 29, and generates high-pressure air of, for example, 10 MPa or more in conjunction with the rotation of the crankshaft 20. It is like that. The high-pressure gas injection valve 27 is also configured to directly inject high-pressure air into the combustion chamber 14 at a predetermined timing in conjunction with the reciprocating motion of the piston 11, that is, the rotational motion of the crankshaft 20. In this case, by blowing high-pressure air into the combustion chamber 14, the air-fuel ratio of the air-fuel mixture in the combustion chamber 14 changes to the lean side, but combustion of the air-fuel mixture proceeds before the high-pressure air is blown. There is no significant negative impact on the continuity of combustion.

  In the present embodiment, immediately after ignition of the spark plug 25, high pressure air of 10 MPa or more is injected into the combustion chamber 14, so that the air-fuel mixture intervenes in the vicinity of the inner peripheral wall of the cylinder 12 surrounding the combustion chamber 14 during combustion of the air-fuel mixture. Can flow along the inner peripheral wall of the cylinder 12. As a result, the turbulent flow of the unburned gas mixture increases, suppressing the decrease in the combustion speed in the late combustion stage and giving no grace to self-ignite the unburned gas mixture, thereby suppressing the occurrence of knocking. It becomes.

  The fuel injection amount from the fuel injection valve 23, the injection timing thereof, the ignition timing of the spark plug 25, the injection amount of high pressure air from the high pressure gas injection valve 27, the injection timing thereof, etc. Detection signal from the accelerator opening sensor 30 that detects the amount of pedal depression, detection signal from the vehicle speed sensor 31 that detects the traveling speed of the vehicle, and detection from the crank angle sensor 32 that detects the rotational phase of the crankshaft 20 Based on the signal, the controller 33 is controlled in a preset relationship.

  In the above-described embodiment, the high-pressure air is supplied to the high-pressure gas injection valve 27 using the air pressurizing pump 28 that is linked to the crankshaft 20 of the engine. An active gas such as argon or helium can be supplied to the high-pressure gas injection valve 27.

  Such a schematic structure of another embodiment according to the present invention is shown in FIG. 4, but elements having the same functions as those of the previous example are denoted by the same reference numerals, and redundant description is omitted. That is, a pressure regulating valve 35 for regulating the high-pressure hydrogen gas in the hydrogen gas tank 34 to a predetermined pressure is incorporated between the high-pressure gas injection valve 27 and the hydrogen gas tank 34 storing high-pressure hydrogen gas or liquid hydrogen. High pressure hydrogen of 10 MPa or more is injected into the combustion chamber 14 by the high pressure gas injection valve 27. Also in this case, the high-pressure hydrogen gas is injected in the opposite direction along the inner peripheral wall of the combustion chamber 14 from the position farthest from the exhaust port 17, and a swirling flow as shown by the arrow in FIG. 14 is formed.

  When hydrogen as in the present embodiment is used as the high-pressure gas, the characteristics of hydrogen are high, the combustion speed is fast, and the ignitability is excellent. Therefore, it is possible to match the injection timing immediately before the end of the compression stroke of the piston 11 or the ignition timing of the spark plug 25.

  It is possible to use water vapor as the high-pressure gas, and FIG. 5 shows a schematic structure of still another embodiment according to the present invention. Elements having the same functions as those in the previous embodiment are denoted by the same reference numerals. It will be noted that duplicate explanation will be omitted. That is, between the high-pressure gas injection nozzle 27 and the water vapor generator 37 that vaporizes water 36 supplied from a water tank (not shown) in which water is stored, high-pressure water vapor generated by the water vapor generator 37 is, for example, 2. A pressure regulating valve 38 for regulating the pressure to about 8 MPa is incorporated. When the cylinder pressure immediately before the compression top dead center of the piston 11, that is, the pressure in the combustion chamber 14 is set to 1.5 MPa, the water vapor pressure is set to about 2.8 MPa, so that the high pressure gas injection valve 27 to the combustion chamber 14 is set. Water vapor can be injected into the inside at a speed of sound.

The steam generator 37 incorporates a heat exchanger 39 for guiding the high-temperature (about 600 ° C.) exhaust gas discharged from the exhaust port 17 to vaporize the water 36, and to obtain the above-described steam pressure. The water 36 is supplied from the water tank to the water vapor generator 37 so that water vapor is formed at a rate of 0.14 m ³ / kg. Also in this embodiment, water vapor is injected in the opposite direction along the inner peripheral wall of the combustion chamber 14 from the position farthest from the exhaust port 17, and a swirling flow as shown by the arrow in FIG. As a result, the turbulent flow of the unburned gas mixture increases, preventing a decrease in the combustion speed in the late combustion period and giving no time to self-ignite the unburned gas mixture. Can be suppressed.

It is sectional drawing showing the schematic structure of one Embodiment which applied the knocking suppression apparatus by this invention to the spark ignition internal combustion engine. It is a conceptual diagram which represents typically the flow of the high pressure air in the II-II arrow cross section in FIG. FIG. 2 is a control block diagram in the embodiment shown in FIG. 1. It is sectional drawing showing the schematic structure of other one Embodiment of the knocking suppression apparatus by this invention. It is sectional drawing showing the schematic structure of another one Embodiment of the knocking suppression apparatus by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Piston 12 Cylinder 13 Cylinder block 14 Combustion chamber 15 Cylinder head 16 Intake port 17 Exhaust port 18 Valve seat 19 Connecting rod 20 Crankshaft 21 Intake valve 22 Exhaust valve 23 Fuel injection valve 24 Ignition gap 25 Spark plug 26 Nozzle 27 High pressure gas injection valve DESCRIPTION OF SYMBOLS 28 Air pressurization pump 29 Toothed belt 30 Accelerator opening sensor 31 Vehicle speed sensor 32 Crank angle sensor 33 Control apparatus 34 Hydrogen gas tank 35 Pressure regulating valve 36 Water 37 Steam generator 38 Pressure regulating valve 39 Heat exchanger

Claims (12)

Supplying air and fuel into a combustion chamber of an internal combustion engine to form an air-fuel mixture;
Igniting a spark plug in which an ignition gap is arranged in the radial center of the combustion chamber to burn the air-fuel mixture in the combustion chamber;
A step of causing the air-fuel mixture intervening in the vicinity of the inner peripheral wall of the cylinder surrounding the combustion chamber during combustion of the air-fuel mixture to flow along the inner peripheral wall of the cylinder.   The step of causing the air-fuel mixture to flow along the inner peripheral wall of the cylinder has a step of blowing high pressure gas into the combustion chamber and causing the high pressure gas to flow along the inner peripheral wall of the cylinder surrounding the combustion chamber. The knocking suppression method according to claim 1.   The method of suppressing knocking according to claim 2, wherein the step of blowing high-pressure gas into the combustion chamber is performed from a position farthest from an exhaust port opening in the combustion chamber.   4. The knocking according to claim 3, wherein the step of blowing the high-pressure gas into the combustion chamber includes a step of causing the high-pressure gas to flow toward the exhaust port side along the inner peripheral wall of the cylinder in opposite directions. Suppression method.   The method for suppressing knocking according to any one of claims 2 to 4, wherein the step of blowing high-pressure gas into the combustion chamber is performed immediately after the ignition of the ignition plug. A spark plug in which an ignition gap is arranged in the radial center of the combustion chamber of the internal combustion engine;
High-pressure gas injection having a nozzle that is disposed at the outer peripheral end of the combustion chamber so as to be positioned farthest from an exhaust port that opens to the combustion chamber, and that injects high-pressure gas along an inner peripheral wall of a cylinder that surrounds the combustion chamber A knocking suppression device characterized by comprising a valve.   The knocking suppression device according to claim 6, wherein the high-pressure gas from the high-pressure gas injection valve is injected immediately after the ignition of the ignition plug.   The knocking suppression device according to claim 6 or 7, wherein the nozzle of the high-pressure gas injection valve has two openings for injecting high-pressure gas in opposite directions along the inner peripheral wall of the cylinder.   The high-pressure gas is compressed air, and is further driven by rotation of a crankshaft of the internal combustion engine, and further includes an air pressurizing pump for guiding the high-pressure air obtained thereby to the high-pressure gas injection valve. The knocking suppression device according to claim 8.   The high pressure gas is hydrogen or an inert gas, and further includes a high pressure tank that stores the high pressure gas, and a pressure regulating valve that regulates the high pressure gas supplied from the high pressure tank to a predetermined pressure and guides the high pressure gas to the high pressure gas injection valve. The knocking suppression device according to any one of claims 6 to 8, wherein   The high-pressure gas is water vapor, a water tank in which water is stored, a water vapor generator that vaporizes water supplied from the water tank, and water vapor generated in the water vapor generator is adjusted to a predetermined pressure. The knocking suppression device according to any one of claims 6 to 8, further comprising a pressure regulating valve that leads to the high-pressure gas injection valve. 12. The knocking suppression device according to claim 11, wherein the water vapor generating device guides exhaust gas flowing through the exhaust port and vaporizes water by heat of the exhaust gas.

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