JP2004239138A - Spark ignition type internal combustion engine and combustion control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain/eliminate knocking without impairing an output characteristic by using hydrogen or hydrogen-rich gas in a spark ignition type internal combustion engine. <P>SOLUTION: A control unit 40 determines a hydrogen heat quantity rate R<SB>H2</SB>according to an engine speed detected by a crank angle position sensor 52 when detecting the knocking by a knocking sensor 50. The control unit 40 determines a hydrogen supply quantity and a gasoline supply quantity by using the determined hydrogen heat quantity rate R<SB>H2</SB>, and injects gasoline of quantity determined from a fuel injection valve IJ into an intake port 16. The control unit 40 directly injects hydrogen of quantity determined from a hydrogen injection valve HIJ into a cylinder 11 at a compression stroke after closing an intake valve 161. The control unit 40 performs spark ignition via a spark plug 31 in the ignition timing of MBT to an air-fuel mixture including gasoline and hydrogen. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine that suppresses knocking in a spark ignition type internal combustion engine and a combustion control method that suppresses knocking.
[0002]
[Prior art]
In a spark ignition type internal combustion engine such as a gasoline internal combustion engine using gasoline as a fuel, the occurrence of knocking is the biggest factor in reducing the maximum output at full load, and many knocking prevention technologies have been proposed. I have.
[0003]
Knocking generally occurs when gasoline fuel (air-fuel mixture) reaches a self-ignition temperature due to an increase in temperature and an acting pressure surrounded by a piston head, an inner wall of a cylinder (cylinder), and a propagating flame. It is caused by ignition by self-ignition prior to ignition by propagation of the flame generated by.
[0004]
Therefore, it is conceivable to reduce or avoid knocking by lowering the compression ratio and using gasoline fuel (so-called high-octane gasoline) having a high auto-ignition temperature (octane number). In addition, since knocking occurs in the latter half of combustion in which the pressure in the cylinder (combustion chamber) rises, it is conceivable to suppress or avoid knocking by increasing the combustion speed. On the other hand, a technique has been proposed in which an in-cylinder temperature is reduced by spraying an anti-knock agent such as water into a cylinder (see Patent Document 1).
[0005]
[Patent Document 1]
JP 2001-271672 A
[0006]
[Problems to be solved by the invention]
However, if the compression ratio is reduced, there is a problem that the maximum output decreases, and high-octane gasoline has a problem that the running cost is higher than regular gasoline. In addition, when the combustion speed is simply increased, combustion in the cylinder occurs rapidly, so that the temperature in the cylinder increases, and knocking is more likely to occur. Further, when the in-cylinder temperature is reduced, there is a problem that the thermal efficiency is reduced.
[0007]
The present invention has been made to solve the above-described problems, and has an object to suppress or eliminate knocking in a spark ignition type internal combustion engine by adding hydrogen or a hydrogen-rich gas to a main fuel without impairing output characteristics. And
[0008]
[Means for Solving the Problems and Functions / Effects]
In order to solve the above-described problems, a first aspect of the present invention provides an internal combustion engine that obtains an output by burning a mixture supplied to a cylinder. An internal combustion engine according to a first aspect of the present invention includes a required heat amount determining means for determining a total heat amount required according to an operation state of the internal combustion engine, and 10% to 30% of the total heat amount in terms of heat amount. A hydrogen supply device for directly supplying an amount of hydrogen to the cylinder, a main fuel supply device for supplying a main fuel in an amount corresponding to 90% to 70% of the total heat amount in terms of heat amount, A spark ignition device for spark-igniting an air-fuel mixture containing the main fuel and hydrogen.
[0009]
According to the internal combustion engine according to the first aspect of the present invention, hydrogen is supplied by the main fuel supply device in an amount corresponding to 10% to 30% of the total heat directly supplied into the cylinder by the hydrogen supply device. Since spark ignition is performed on a mixture of the main fuel with an amount corresponding to 90% to 70% of the total heat, knocking can be suppressed or prevented without impairing output characteristics. In a region where the supply amount of hydrogen is less than 10% of the total amount of heat in terms of the amount of heat, the ignition timing cannot be advanced (advanced) because the combustion speed of the air-fuel mixture is not improved, and the ignition is performed at the ignition timing at which the most output is obtained. Processing cannot be performed. In a region where the supply amount of hydrogen exceeds 30% of the total calorie in terms of calorific value, the combustion speed of the air-fuel mixture becomes too high, the air-fuel mixture burns rapidly, the temperature in the cylinder rises, and knocking occurs on the contrary. Resulting in.
[0010]
In the internal combustion engine according to the first aspect of the present invention, the hydrogen supply device may supply the hydrogen to a vicinity of the spark ignition device and an inner peripheral portion of the cylinder. In such a case, the hydrogen supplied in the vicinity of the spark ignition device enhances the ignitability of the air-fuel mixture and increases the combustion speed, thereby enabling ignition at the ignition timing at which the most output can be obtained and improving the flame quality. Knocking is suppressed and prevented by propagation. Further, the hydrogen supplied to the inner peripheral edge of the cylinder promotes combustion at the inner peripheral edge of the cylinder to the end and suppresses / prevents knocking at the inner peripheral edge of the cylinder due to its own knocking resistance.
[0011]
In the internal combustion engine according to the first aspect of the present invention, the main fuel may be gasoline fuel, natural gas fuel or liquefied petroleum fuel. In such a case, the same operation and effect as when gasoline fuel is used can be obtained.
[0012]
The first aspect of the present invention may be realized as a combustion control method in a spark ignition type internal combustion engine. In such a case, the combustion control method in the spark ignition type internal combustion engine according to the first aspect of the present invention determines the total heat quantity required according to the operating state of the internal combustion engine, and calculates the total heat quantity in terms of heat quantity. Supplying an amount of hydrogen corresponding to 10% to 30% directly into the cylinder of the internal combustion engine, and supplying a main fuel in an amount corresponding to 90% to 70% of the total heat amount in terms of heat amount; It is characterized by spark ignition of an air-fuel mixture containing main fuel and hydrogen.
[0013]
A second aspect of the present invention provides an internal combustion engine that obtains an output by burning an air-fuel mixture supplied into a cylinder. An internal combustion engine according to a second aspect of the present invention includes a main fuel supply device that supplies a main fuel, a hydrogen-rich gas supply device that supplies a hydrogen-rich gas directly into the cylinder, and the main fuel and a hydrogen-rich gas. A spark ignition device for spark ignition of the air-fuel mixture, an engine speed detection unit for detecting an engine speed of the internal combustion engine, and a control device for controlling the hydrogen-rich gas supply device, wherein the detected engine speed is When the engine speed is equal to or higher than the engine speed at which knocking occurs, a control device that does not supply the hydrogen-rich gas by the hydrogen-rich gas supply device is provided.
[0014]
According to the internal combustion engine of the second aspect of the present invention, when the engine speed is equal to or higher than the engine speed at which knocking occurs, the supply of hydrogen-rich gas by the hydrogen-rich gas supply device is not performed. It is possible to prevent unnecessary supply of hydrogen in a region where no hydrogen is supplied and to prevent knocking caused by the supply of hydrogen.
[0015]
In the internal combustion engine according to the second aspect of the present invention, when the detected engine speed is lower than the engine speed at which knocking occurs, the control device supplies the hydrogen-rich gas by the hydrogen-rich gas supply device. May be performed. In such a case, by supplying the hydrogen-rich gas, it is possible to improve the combustion rate of the air-fuel mixture and improve the knocking resistance, and it is possible to suppress and prevent the occurrence of knocking in the spark ignition type internal combustion engine.
[0016]
In the internal combustion engine according to the second aspect of the present invention, the spark ignition device may execute spark ignition at an ignition timing (MBT) at which the most output can be obtained. Since the knocking resistance is improved by supplying the hydrogen-rich gas, knocking does not occur even when ignited in the MBT, and the output characteristics of the internal combustion engine can be improved.
[0017]
The second aspect of the present invention may be realized as a combustion control method in a spark ignition type internal combustion engine. In such a case, the combustion control method in the spark ignition type internal combustion engine according to the second aspect of the present invention detects the engine speed of the internal combustion engine, and the detected engine speed is lower than the engine speed at which knocking occurs. In this case, the main fuel is supplied to the internal combustion engine, and the hydrogen-rich gas is directly supplied into the cylinder of the internal combustion engine, and spark-ignition is performed on a mixture containing the main fuel and the hydrogen-rich gas. And
[0018]
A third aspect of the present invention provides an internal combustion engine that obtains an output by burning an air-fuel mixture supplied into a cylinder. An internal combustion engine according to a third aspect of the present invention includes a main fuel supply device that supplies main fuel, a hydrogen-rich gas supply device that supplies hydrogen-rich gas directly into the cylinder, and detects an engine speed of the internal combustion engine. Engine speed detecting means for detecting the engine speed, obtaining means for obtaining a difference between the ignition timing at which the most output is obtained and the ignition timing at which knocking occurs at the detected engine speed, and obtaining the hydrogen based on the obtained difference. Determining means for determining the amount of hydrogen-rich gas supplied by the rich gas supply device, and a spark igniter for performing spark ignition at the ignition timing at which the most output is obtained for the mixture containing the main fuel and the hydrogen-rich gas. It is characterized by having.
[0019]
According to the internal combustion engine according to the third aspect of the present invention, the difference between the ignition timing at which the maximum output is obtained at the detected engine speed of the internal combustion engine and the ignition timing at which knocking occurs is determined. Since the amount of hydrogen-rich gas supplied by the hydrogen-rich gas supply device is determined based on this, knocking can be prevented even if spark ignition is performed at the ignition timing at which the most output can be obtained. In addition, since spark ignition is performed at the ignition timing at which the most output can be obtained for the mixture containing the main fuel and the hydrogen-rich gas, knocking can be suppressed or prevented without impairing the output.
[0020]
In the internal combustion engine according to the third aspect of the present invention, the main fuel is gasoline fuel, the hydrogen-rich gas is pure hydrogen gas, and the amount of the hydrogen-rich gas supplied by the hydrogen-rich gas supply device is expressed in terms of calorific value. Alternatively, it may be in the range of 10 to 30% of the total heat required in the internal combustion engine. Within such a range, knocking can be suppressed and prevented by supplying the hydrogen-rich gas most effectively.
[0021]
The third aspect of the present invention may be realized as a combustion control method in a spark ignition type internal combustion engine. In such a case, the combustion control method in the spark ignition type internal combustion engine according to the third aspect of the present invention detects the engine speed of the internal combustion engine, and determines the ignition timing at which the most output is obtained at the detected engine speed. A difference from the ignition timing at which knocking occurs is obtained, a hydrogen-rich gas amount supplied by the hydrogen-rich gas supply device is determined based on the obtained difference, and the main fuel is supplied to the internal combustion engine. Of hydrogen-rich gas directly into the cylinder of the internal combustion engine, and performs spark ignition at the ignition timing at which the most output can be obtained for the mixture containing the main fuel and hydrogen-rich gas. .
[0022]
A fourth aspect of the present invention provides an internal combustion engine that obtains an output by burning an air-fuel mixture supplied into a cylinder. An internal combustion engine according to a fourth aspect of the present invention includes a knocking detector that detects occurrence of knocking in the internal combustion engine, an engine speed detection unit that detects an engine speed of the internal combustion engine, and a knocking detector. When the occurrence of knocking is detected, a fuel supply amount determining means for determining a hydrogen-rich gas amount and a main fuel amount to be supplied based on the detected engine speed, and the determined amount of the hydrogen-rich gas. A hydrogen-rich gas supply device for supplying directly into the cylinder, a main fuel supply device for supplying the determined amount of main fuel, and a spark ignition device for spark-igniting an air-fuel mixture containing the main fuel and hydrogen-rich gas And characterized in that:
[0023]
According to the internal combustion engine according to the fourth aspect of the present invention, when knocking is detected by the knocking detector, the amount of hydrogen-rich gas to be supplied is determined based on the engine speed, and the determined amount of hydrogen-rich gas is determined. Is supplied directly into the cylinder, a predetermined amount of main fuel is supplied, and a mixture containing the main fuel and hydrogen-rich gas is spark-ignited, so that knocking can be suppressed and prevented.
[0024]
In the internal combustion engine according to a fourth aspect of the present invention, the hydrogen gas-rich gas supply means may supply a hydrogen-rich gas into the cylinder during a compression stroke of the internal combustion engine. In such a case, the hydrogen-rich gas can be supplied into the cylinder without obstructing the intake of air into the cylinder.
[0025]
In the internal combustion engine according to the fourth aspect of the present invention,
The fuel supply amount determining means,
Requested heat amount determining means for determining the total heat amount required according to the operating state of the internal combustion engine,
A calorific-ratio determining means for determining a calorific ratio of the hydrogen gas-rich gas to the total calorific value based on the detected engine speed,
Hydrogen-rich gas amount determining means for determining a hydrogen-rich gas amount corresponding to the determined heat amount ratio of the hydrogen-rich gas,
Main fuel amount determining means for determining a heat amount ratio of the main fuel from the total heat amount and the heat amount ratio of the hydrogen-rich gas and determining a main fuel amount corresponding to the calculated heat amount ratio of the main fuel may be provided. In such a case, the heat amount ratio of the hydrogen-rich gas can be determined without changing the total heat amount required for the internal combustion engine, and the supply amount of the hydrogen-rich gas and the supply amount of the main fuel can be determined.
[0026]
In the internal combustion engine according to a fourth aspect of the present invention, the main fuel is a gasoline fuel, the hydrogen-rich gas is a pure hydrogen gas, and the calorific ratio of the hydrogen-rich gas determined by the calorific-ratio determining means is equal to the total calorific value. It may be in the range of 10 to 30% of the calorific value. In such a case, in the most widely used gasoline internal combustion engine, occurrence of knocking can be suppressed or prevented without impairing the output. Further, in such a range, knocking can be suppressed and prevented without lowering the output by supplying the hydrogen-rich gas most effectively.
[0027]
The fourth aspect of the present invention may be realized as a combustion control method in a spark ignition type internal combustion engine. In such a case, the combustion control method in the spark ignition type internal combustion engine according to the fourth aspect of the present invention detects the occurrence of knocking in the internal combustion engine, detects the engine speed of the internal combustion engine, and detects the occurrence of knocking. In this case, the amount of the hydrogen-rich gas and the amount of the main fuel to be supplied are determined based on the detected engine speed, and the determined amount of the main fuel is supplied to the internal combustion engine and the determined amount is determined. May be directly supplied into the cylinder to spark-ignite a mixture containing the main fuel and the hydrogen-rich gas.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a spark ignition type internal combustion engine according to the present invention will be described based on some embodiments with reference to the drawings.
[0029]
-First embodiment:
A schematic configuration of a spark ignition type internal combustion engine according to a first embodiment will be described with reference to FIGS. FIG. 1 is an explanatory diagram showing a schematic configuration of a spark ignition type internal combustion engine according to a first embodiment. FIG. 2 is an explanatory diagram schematically showing an existing range of hydrogen supplied into the combustion chamber in the spark ignition type internal combustion engine according to the first embodiment.
[0030]
A spark ignition type internal combustion engine 10 according to a first embodiment includes a cylinder block 12 having a plurality of cylinders 11 therein, a piston 13 reciprocating in the cylinder 11, and a crankcase 14 disposed at the bottom of the cylinder block 12. , A cylinder head 15 disposed above the cylinder block 12 (cylinder 11). The cylinder block 12 is provided with a knocking sensor 50 for detecting knocking occurring in the cylinder 11 (combustion chamber). The knocking sensor 50 is, for example, a sensor that detects occurrence of knocking by detecting a natural frequency generated when knocking occurs.
[0031]
The cylinder head 15 has an intake port 16 and an exhaust port 17 for each cylinder 11. Each intake port 16 is provided with an intake valve 161 driven by an intake cam IC to open and close the intake port 16, and each exhaust port 17 is driven by an exhaust cam EC to open and close the exhaust port 17. An exhaust valve 171 is provided.
[0032]
A branch end of an intake pipe 18 is connected to each intake port 16, and a branch end of an exhaust pipe (exhaust manifold) 19 is connected to each exhaust port 17. An intake control valve 30 for controlling the amount of intake air flowing into the combustion chamber and a throttle opening sensor 51 for detecting the throttle opening of the intake control valve 30 are arranged in the intake pipe 19.
[0033]
Each intake port 16 is provided with a fuel injection valve IJ for injecting gasoline fuel as a main fuel. That is, the internal combustion engine 10 used in the first embodiment is a port injection type internal combustion engine. Fuel is supplied to each fuel injection valve IJ via a fuel delivery pipe FD.
[0034]
In the cylinder head 15, a hydrogen injection valve HIJ for directly injecting hydrogen gas into the cylinder 11 is arranged near the intake port 16, and a spark plug 31 for spark ignition is arranged at a substantially central position of each cylinder 11. . In the first embodiment, hydrogen is supplied according to the operating state of the internal combustion engine in addition to gasoline as the main fuel. Hydrogen has a characteristic that it has a high self-ignition temperature and excellent knocking resistance. Since the self-ignition temperature is high, the self-ignition of the gasoline mixture on the inner peripheral wall of the cylinder 11 can be suppressed. Further, since the combustion speed is high, the flame propagation time after ignition becomes short, and the gasoline mixture on the inner peripheral wall of the cylinder 11 can be burned by flame propagation before self-ignition. Therefore, knocking can be suppressed or prevented by appropriately adjusting the supply amount and the supply position in the cylinder 11 (combustion chamber).
[0035]
The hydrogen stored in the high-pressure hydrogen tank HT is supplied to the hydrogen injection valve HIJ via a hydrogen delivery pipe HFD after the pressure of the hydrogen stored in the high-pressure hydrogen tank HT is reduced to a predetermined pressure (injection pressure: 4 to 5 MPa, for example) by a pressure reducing valve or the like. . The hydrogen injection valve HIJ is provided with three injection holes, and hydrogen gas is supplied to the vicinity of the ignition plug 31 and the inner wall of the cylinder 11, respectively, as shown in FIG. Generally, since knocking is likely to occur on the inner wall of the cylinder 11 (the outer peripheral edge of the piston head surface), hydrogen is supplied to the inner wall of the cylinder 11 and is supplied to the vicinity of the ignition plug 31 to ignite the gasoline mixture. Improve the performance. As a result, even if the ignition timing is advanced, sufficient flame propagation can be obtained because the combustion speed is high, and self-ignition of gasoline on the inner wall of the cylinder 11 can be suppressed and combustion can be improved. Therefore, knocking in the internal combustion engine 10 can be suppressed.
[0036]
The control unit 40 has an arithmetic processing function (CPU), and a storage function (ROM, RAM) for storing maps, programs, and the like. Various sensors such as a knocking sensor 50, a throttle opening sensor 51, and a crank position sensor 52 for detecting the engine speed are connected to the control unit 40, and signals from the various sensors for detecting the operating state of the internal combustion engine 10 are transmitted. Is entered. A fuel injection valve IJ, a hydrogen injection valve HJ, an intake control valve 30, and a spark plug 31 are connected to the control unit 40, and supply amounts of gasoline and hydrogen, injection timing of gasoline and hydrogen, ignition timing, intake air amount, and the like. Is appropriately controlled.
[0037]
An operation control process in the internal combustion engine 10 according to the first embodiment will be described with reference to FIGS. FIG. 3 is a flowchart showing a processing routine executed in the operation control processing of the internal combustion engine in the first embodiment. FIG. 4 shows the hydrogen calorie ratio R based on the engine speed Ne. _H2 FIG. 9 is an explanatory diagram showing an example of a map for obtaining (%). FIG. 5 is an explanatory diagram showing the relationship between knocking occurrence timing and the ratio of added hydrogen (heat ratio). FIG. 6 is a flowchart showing a processing routine executed in the hydrogen injection control processing. FIG. 7 is a flowchart showing a processing routine executed in the gasoline injection control processing. FIG. 8 is an explanatory diagram showing output torque characteristics improved by adding hydrogen to gasoline in the first embodiment.
[0038]
The operation control process of the internal combustion engine will be described with reference to FIG. This processing routine is repeatedly executed at predetermined time intervals. The control unit 40 acquires the engine speed Ne from the crank position sensor 52 and acquires the throttle opening from the throttle opening sensor 51 (step S100). The control unit 40 acquires the raw gasoline injection amount Aa (cc / st) and the raw gasoline injection end timing Bg (° ATDC) based on the current operation state (step S110). The control unit 40 acquires the air-fuel ratio A / F based on the detected throttle opening (step S120). The throttle opening and the air-fuel ratio A / F are related to, for example, A / F = 14.5 in a partial throttle opening range and A / F = 12.5 in a full throttle opening range. It goes without saying that other air-fuel ratios can be taken.
[0039]
The control unit 40 determines whether or not knocking in the internal combustion engine 10 is detected by the knocking sensor 50 (step S130), and when it is determined that knocking has not occurred (not detected) (step S130: No), this processing routine ends. The detection of knocking by the knocking sensor 50 is performed by detecting a natural frequency generated by knocking. For example, in the first embodiment, knocking is performed by providing a vibration sensor that resonates at the natural frequency at the time of knocking. The eigenfrequency associated with is detected more accurately.
[0040]
When it is determined that knocking has occurred (step S130: Yes), the control unit 40 determines whether or not hydrogen to be added (supplied) based on the engine speed Ne detected using the map shown in FIG. Calorific value ratio R _H2 Is determined (step S140). Generally, in a spark ignition type internal combustion engine, knocking is less likely to occur as the engine speed increases, and as shown in FIG. 4, as the engine speed Ne decreases, the heat quantity ratio R of hydrogen decreases. _H2 Increase. That is, since the piston speed increases with an increase in the engine speed, the turbulence of the air-fuel mixture in the cylinder 11 is increased to increase the burning speed, and the knocking occurs in the region (piston head, cylinder inner wall, propagation flame due to the propagation flame) This is because the volume per unit time of the (enclosed area) increases, and the degree of compression is reduced.
[0041]
Hydrogen calorie ratio R _H2 Is determined in the range of 10% to 30%, more preferably in the range of 15% to 25% of the total amount of heat required for the internal combustion engine 10, that is, the amount of heat conventionally generated by burning gasoline. FIG. 5 shows the heat quantity ratio R of hydrogen when the engine speed is 1,600 rpm and the throttle is fully opened, that is, when the engine speed is low and the load is low. _H2 And the ignition timing (° BTDC) at which knocking occurs. The + direction on the vertical axis indicates the direction in which ° BTDC increases, that is, the advance angle direction. Also, in FIG. 5, a solid circle means a point where knocking does not occur, and an open circle means a point where knocking occurs. From FIG. 5, it can be seen from FIG. 5 that the heat quantity ratio R of hydrogen at which knocking does not occur even if the ignition timing is advanced to the vicinity of the ignition timing (MBT) where the most output can be obtained _H2 Is about 10 to 30%, more preferably about 15 to 25%. Therefore, the supply amount of hydrogen to gasoline is preferably in the range of 10% to 30%, more preferably in the range of 15% to 25%, in terms of calorific value, with respect to the conventional gasoline supply amount (required total heat amount). It can be said. In the description with reference to FIGS. 5 and 8, "retarding" means delaying the ignition timing with respect to a certain ignition timing, and "advancement" means leading the ignition timing with respect to a certain ignition timing. .
[0042]
If the calorific value of hydrogen is too small, the combustion speed cannot be improved because sufficient hydrogen does not spread in the cylinder 11 (combustion chamber), and as shown in FIG. Therefore, ignition cannot be performed by MBT, and the obtained output is reduced.
[0043]
On the other hand, if the proportion of the calorific value of hydrogen is too large, the initial combustion after ignition becomes too fast, so that the compressed high-temperature mixture burns at a time and the temperature in the cylinder 11 rises significantly, causing knocking. Easier to do. Therefore, in order to prevent knocking, slow ignition must be performed by delaying the ignition timing, and the ignition timing cannot be advanced significantly. For this reason, since the MBT is located on the advance side of the knocking occurrence ignition timing, the MBT cannot be ignited and the output decreases. Therefore, the heat quantity ratio R of hydrogen for performing ignition near the MBT while avoiding knocking _H2 Has an appropriate range of about 10-30%, more preferably about 15-25%.
[0044]
The control unit 40 determines the calorific value of hydrogen R _H2 Is determined, hydrogen injection control for injecting hydrogen (step S150) and gasoline injection control for injecting gasoline (step S160) are respectively performed. The hydrogen injection control and the gasoline injection control will be described in detail below with reference to FIGS.
[0045]
The control unit 40 determines whether knocking still occurs based on the detection signal from the knocking sensor 50 (step S170), and when it is determined that knocking has occurred (step S170: Yes). , The current hydrogen calorie ratio R _H2 Multiplied by a coefficient α (> 1) _H2 Is increased (step S180), and the hydrogen injection control and the gasoline injection control (steps S150 and S160) are executed again. When it is determined that knocking has not occurred (step S170: No), the control unit 40 ends the processing routine.
[0046]
The hydrogen injection control process will be described in detail with reference to FIG. The control unit 40 calculates the hydrogen supply heat amount Fh (J / st) (step S1500), and calculates the hydrogen supply amount Ah (cc / st) using the calculated hydrogen supply heat amount Fh (step S1510). The hydrogen supply heat amount Fh is obtained by calculating the total supply heat amount Fa (J / st) obtained from the raw gasoline injection amount Aa and the gasoline lower calorific value Hg (J / cc) and the heat amount ratio R of hydrogen. _H2 And is obtained from the following equation.
Fa = Aa × Hg Formula (1)
Fa = Fh + Fg Equation (2)
Fh / Fg = R _H2 Equation (3)
Here, the gasoline lower heating value Hg indicates a heating value obtained only from the gasoline component, and a prescribed value is used.
[0047]
The hydrogen supply heat amount Ah is obtained from the following equation using the hydrogen supply heat amount Fh and the hydrogen lower heat value Hh (J / cc) obtained in step S1500.
Ah = Fh / Hh Equation (4)
Here, the hydrogen lower heating value Hh indicates a heating value obtained only from the hydrogen component, and a prescribed value is used.
[0048]
The control unit 40 determines a hydrogen injection time τh (ms) required to supply the determined hydrogen supply amount Ah, and supplies hydrogen based on the detected engine speed Ne and the determined hydrogen injection time τh. A hydrogen injection crank angle θh (° CA), which is a crank angle for continuing injection, is calculated (step S1520). The hydrogen injection time τh is determined, for example, as the time required for detecting the pressure of the hydrogen delivery pipe HFD and injecting the hydrogen supply amount Ah under the detected pressure.
[0049]
The control unit 40 calculates a hydrogen injection start crank angle Sh (° BTDC) for starting hydrogen injection from the following equation using the obtained hydrogen injection crank angle θh and a predetermined hydrogen injection end crank angle Bh. (Step S1530).
Sh = Bh + θh Equation (5)
Here, the hydrogen injection termination crank angle Bh may be an angle at which the air-fuel mixture is wound up on the piston 13 or in the cavity of the piston 13, for example, 40 ° BTDC, that is, the latter half of the compression stroke is preferable. In addition, since the hydrogen gas as a gas is injected into the cylinder 11, it is desirable that the intake valve 161 be closed.
[0050]
The control unit 40 drives the hydrogen injector HIJ to open at the determined hydrogen injection start crank angle Sh, closes the hydrogen injector HIJ at the hydrogen injection end crank angle Bh (step S1540), and ends the processing routine. .
[0051]
The gasoline injection control process will be described in detail with reference to FIG. The control unit 40 calculates the gasoline supply heat amount Fg (J / st) (step S1600), and calculates the gasoline supply amount Ag (cc / st) using the calculated gasoline supply heat amount Fg (step S1610). The gasoline supply calorie Fg may be calculated using the above-described equations (1) to (3), or if the hydrogen supply calorie Fh has been previously obtained, the above-described equation (2) May be obtained by using.
[0052]
The gasoline supply amount Ag is obtained from the following equation using the gasoline supply heat amount Fg obtained in step S1600 and the gasoline lower heating value Hh (J / cc).
Ag = Fg / Hg Formula (6)
[0053]
The control unit 40 determines a gasoline injection time τg (ms) required to supply the determined gasoline supply amount Ag, and supplies gasoline based on the detected engine speed Ne and the determined gasoline injection time τg. The gasoline injection crank angle θg (° CA), which is the crank angle for continuing injection, is calculated (step S1620). The gasoline injection time τg is obtained, for example, as a time required for detecting the pressure of the gasoline delivery pipe FD and injecting the gasoline supply amount Ag under the detected pressure.
[0054]
The control unit 40 uses the obtained gasoline injection crank angle θg and the previously obtained raw gasoline injection end crank angle Bg to calculate the gasoline injection start crank angle Sg (° BTDC) for starting gasoline injection from the following equation. It is calculated (step S1630).
Sg = Bg + θg Equation (7)
[0055]
The control unit 40 drives the gasoline injector IJ to open at the determined gasoline injection start crank angle Sg, closes the gasoline injector IJ at the gasoline injection end crank angle Bh (step S1640), and ends the processing routine. . It should be noted that spark ignition is performed by the spark plug 31 on the gasoline, hydrogen, and air mixture injected and generated from the fuel injection valve IJ and the hydrogen injection valve HIJ. The ignition timing executed by the control unit 40 is MBT, and the internal combustion engine 10 can execute efficient combustion.
[0056]
As described above, according to the internal combustion engine according to the first embodiment, the total amount of heat required when only gasoline is supplied in addition to gasoline as the main fuel is approximately 10 % To 30%, preferably about 15 to 25% of hydrogen, so that knocking can be achieved without reducing the maximum output in the entire operation range of the internal combustion engine even when using general regular gasoline. It can be suppressed and avoided.
[0057]
That is, by adding hydrogen, the combustion speed of the air-fuel mixture is improved, and as shown in FIG. 8, the characteristic line of the generated torque with respect to the ignition timing is shifted to the upper left (toward the retard side). As a result, the MBT moves to a more retarded side than the knocking ignition timing when only gasoline is used as fuel, so that the output decreases even if the ignition timing is advanced significantly from the conventional ignition timing (knock point). There is no danger. In the conventional knock avoidance technology, the ignition timing has been delayed, but since the combustion speed of gasoline is lower than the combustion speed of hydrogen, excessive retarding causes a large decrease in output, so that retarding is performed. There was a limit to the conversion.
[0058]
In addition, since the characteristic line of the generated torque with respect to the ignition timing is shifted to the upper left (toward the retard side), knocking does not occur even if the spark ignition timing by the spark plug 31 is set to MBT, as shown in FIG. Therefore, the occurrence of knocking can be suppressed or avoided, and the output characteristics of the internal combustion engine 10 can be improved.
[0059]
Further, as shown in FIG. 8, the characteristic line of the generated torque with respect to the advance / retard of the ignition timing is shifted to the upper left, so that the generated torque of the internal combustion engine 10 can be increased. This is considered to be due to an increase in the amount of gas in the cylinder 11 due to the injection of hydrogen and an increase in the isovolume at the time of the explosion due to the promotion of combustion, thereby increasing the output.
[0060]
In addition, since hydrogen supply for preventing knocking is performed depending on whether knocking has occurred or not, for example, occurrence of knocking can be suppressed or prevented in accordance with individual conditions such as temperature.
[0061]
-2nd Example:
An internal combustion engine according to a second embodiment will be described with reference to FIGS. FIG. 9 is a flowchart showing a processing routine executed in the operation processing control processing in the internal combustion engine according to the second embodiment. FIG. 10 is an explanatory diagram showing a map used for obtaining the knocking prevention retard amount C from the engine speed Ne. Since the configuration of the internal combustion engine used in the second embodiment is the same as the configuration of the internal combustion engine 10 according to the first embodiment, the same components will be denoted by the same reference numerals and description thereof will be omitted.
[0062]
This processing routine is repeatedly executed at predetermined time intervals. The control unit 40 acquires the engine speed Ne from the crank position sensor 52 and acquires the throttle opening from the throttle opening sensor 51 (step S200). The control unit 40 determines whether or not the acquired engine speed Ne is equal to or less than the determined engine speed N0 (step S210). When it is determined that Ne> N0 (Step S210: No), the control unit 40 determines the gasoline injection amount without performing the hydrogen injection (Step S220).
[0063]
As described above, in the spark ignition type internal combustion engine, knocking is less likely to occur as the engine speed increases. Therefore, in general, the engine speed at which knocking does not occur is set as the determination engine speed N, and hydrogen addition is not performed.
[0064]
When it is determined that Ne ≦ N0 (Step S210: Yes), the control unit 40 obtains the knocking prevention delay amount C from the engine speed Ne with reference to the map shown in FIG. It is determined whether or not it is larger than the angular amount C0 (step S230). The knocking prevention retard amount C is a difference between the knocking occurrence ignition timing and the MBT, and means a retard amount that must be retarded in order to prevent knocking. The manner in which knocking is less likely to occur as the engine speed increases is also indicated by the fact that the knock prevention retard amount C decreases as the engine speed Ne increases, as shown in FIG. The determination knock prevention retard amount C0 is determined by the hydrogen calorie ratio R _H2 When the determination knocking prevention retard amount C is larger than the determination knocking prevention retard amount C0, the hydrogen heat amount ratio R _H2 Is set higher. Here, the hydrogen calorie ratio R _H2 Means the ratio of the amount of heat to be generated by the combustion of hydrogen when supplying hydrogen to the amount of heat when the total amount of heat required for the internal combustion engine 10 is generated by gasoline.
[0065]
When the control unit 40 determines that the knocking prevention retard amount C> the determination knock prevention retard amount C0 (step S230: Yes), the hydrogen heat amount ratio R _H2 Is set to A% (step S230A), and the gasoline injection amount and the hydrogen injection amount are determined (step S240). Here, A% is set to, for example, 25%. In such a case, since the knocking prevention retard amount C is large, the heat amount ratio R of hydrogen is calculated. _H2 If the hydrogen supply rate is not increased, the effect of improving the combustion speed and the knocking resistance by adding hydrogen cannot be obtained, so a value near the maximum allowable value of the hydrogen supply amount is set.
[0066]
When the control unit 40 determines that the knocking prevention retard amount C> the determination knocking prevention retard amount C0 is not satisfied (step S230: No), the hydrogen heat amount ratio R _H2 Is set to B% (step S230B), and the gasoline injection amount and the hydrogen injection amount are determined (step S240). Here, B% is set to, for example, 15%. In such a case, since the knocking prevention retard amount C is relatively small, a value near the minimum allowable value of the hydrogen supply amount is set.
[0067]
The gasoline injection amount and the hydrogen injection amount are obtained in the same manner as described in the first embodiment. Specifically, the gasoline calorie required for the internal combustion engine 10 is defined as the total calorie, and the hydrogen calorie ratio R determined with respect to the total calorie _H2 And a gasoline supply amount for realizing the remaining amount of heat.
[0068]
The control unit 40 sets the ignition timing to MBT (step S260), and executes the injection / ignition control (step S270). The injection from the gasoline injector IJ is executed in the intake stroke of the internal combustion engine 10, and the injection from the hydrogen injector HIJ is executed in the latter half of the compression stroke of the internal combustion engine 10. In addition, spark ignition by the ignition plug 31 is executed for MBT.
[0069]
The control unit 40 determines again whether knocking has been detected by the knocking sensor 50 (whether knocking has occurred) (step S280). If it is determined that knocking has not been detected (step S280: No), This processing routine ends.
[0070]
When the control unit 40 determines that knocking has been detected (step S280: Yes), the hydrogen calorie ratio R _H2 Is determined to be less than 25% (step S290), and the hydrogen calorie ratio R _H2 Is less than 25% (step S290: Yes), the hydrogen calorie ratio R _H2 Is increased (step S295), and the routine goes to step S230B. However, the hydrogen calorie ratio R _H2 Is 25%.
[0071]
On the other hand, the control unit 40 calculates the hydrogen calorie ratio R _H2 Is determined to be 25% (step S290: No), this processing routine ends. In the second embodiment, the hydrogen calorie ratio R _H2 Is set to 25%, the hydrogen calorie ratio R _H2 Is less than 25%, the hydrogen calorie ratio R _H2 The knocking is suppressed by increasing the hydrogen calorie ratio R _H2 Is 25%, the ignition timing is retarded or the like.
[0072]
As described above, according to the internal combustion engine 10 according to the second embodiment, even in an operation region in which the ignition timing could not be set to the MBT due to the occurrence of knocking in the past, for example, even in a low-speed high-load region, hydrogen is supplied. By adding the gasoline to the gasoline at an appropriate ratio, the ignition with the MBT can be executed, so that the output can be improved while suppressing knocking.
[0073]
In addition, in a high rotation region where knocking generally does not easily occur, the operation control of the internal combustion engine 10 can be simplified by not adding hydrogen.
[0074]
-Other examples:
In the above embodiment, the hydrogen gas stored at high pressure in the high-pressure hydrogen tank HT is used, but liquid hydrogen may be used. Although pure hydrogen is used in the above embodiment, a reformer may be mounted on the internal combustion engine 10 and a hydrogen-rich gas generated by the reformer may be used. In such a case, the appropriate heat quantity ratio of the hydrogen-rich gas is newly set.
[0075]
In the above embodiment, gasoline is used as the main fuel, but natural gas fuel, liquefied petroleum fuel, or the like may be used. If the amount of heat generated during combustion is the same as that of gasoline, the hydrogen heat amount ratio R _H2 Is preferably 10 to 30%, more preferably 15 to 25%. If the heat generated during combustion is different from that of gasoline, the hydrogen calorie ratio R depends on the heat generated during combustion. _H2 Is appropriately determined.
[0076]
In the above embodiment, the port injection type fuel injection valve IJ is used, but a direct injection type fuel injection valve in which fuel is directly injected into the cylinder 11 may be used.
[0077]
As described above, the internal combustion engine and the combustion control method for the internal combustion engine according to the present invention have been described based on some embodiments. However, the above-described embodiments of the present invention are for facilitating understanding of the present invention. It is not intended to limit the invention. The present invention can be modified and improved without departing from the spirit and scope of the claims, and it is needless to say that the present invention includes equivalents thereof.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a spark ignition type internal combustion engine according to a first embodiment.
FIG. 2 is an explanatory diagram schematically showing an existing range of hydrogen supplied into a combustion chamber in the spark ignition type internal combustion engine according to the first embodiment.
FIG. 3 is a flowchart showing a processing routine executed in an operation control process of the internal combustion engine in the first embodiment.
FIG. 4 is a diagram showing a hydrogen calorie ratio R based on an engine speed Ne _H2 FIG. 9 is an explanatory diagram showing an example of a map for obtaining (%).
FIG. 5 is an explanatory diagram showing a relationship between knocking occurrence timing and a ratio of added hydrogen (amount of heat).
FIG. 6 is a flowchart showing a processing routine executed in the hydrogen injection control processing.
FIG. 7 is a flowchart showing a processing routine executed in the gasoline injection control processing.
FIG. 8 is an explanatory diagram showing output torque characteristics improved by adding hydrogen to gasoline in the first embodiment.
FIG. 9 is a flowchart showing a processing routine executed in an operation processing control processing in the internal combustion engine according to the second embodiment.
FIG. 10 is an explanatory diagram showing a map used for obtaining a knocking prevention retard amount C from an engine speed Ne.
[Explanation of symbols]
10. Internal combustion engine
11 ... Cylinder
12 ... Cylinder block
13 ... Piston
14 ... Crankcase
15 ... Cylinder head
16 ... intake port
161: Intake valve
17… Exhaust port
171: Exhaust valve
18 ... intake pipe
19 ... exhaust pipe
30 ... intake control valve
31 ... Spark plug
40 ... Control unit
50: knocking sensor
51 ... Throttle opening sensor
52 ... Crank position sensor
IC: intake side cam
EC: Exhaust side cam
IJ: Fuel injection valve (injector)
FD: Fuel delivery pipe
HIJ: hydrogen injection valve
HFD: hydrogen delivery pipe
HT: High-pressure hydrogen tank

Claims (16)

An internal combustion engine that obtains output by burning an air-fuel mixture supplied into a cylinder,
Requested heat amount determining means for determining the total heat amount required according to the operating state of the internal combustion engine,
A hydrogen supply device for directly supplying hydrogen into the cylinder in an amount corresponding to 10% to 30% of the total heat amount in terms of heat amount;
A main fuel supply device that supplies a main fuel in an amount corresponding to 90% to 70% of the total amount of heat in terms of heat amount;
An internal combustion engine comprising: a spark ignition device for spark-igniting an air-fuel mixture containing the main fuel and hydrogen. The internal combustion engine according to claim 1,
An internal combustion engine that supplies the hydrogen to the vicinity of the spark ignition device and to an inner peripheral portion of the cylinder. The internal combustion engine according to claim 1 or claim 2,
An internal combustion engine wherein the main fuel is gasoline fuel, natural gas fuel or liquefied petroleum fuel. An internal combustion engine that obtains output by burning an air-fuel mixture supplied into a cylinder,
A main fuel supply device for supplying main fuel,
A hydrogen-rich gas supply device for supplying hydrogen-rich gas directly into the cylinder,
A spark ignition device for spark-igniting an air-fuel mixture containing the main fuel and hydrogen-rich gas,
Engine speed detection means for detecting the engine speed of the internal combustion engine,
A control device for controlling the hydrogen-rich gas supply device, wherein when the detected engine speed is equal to or higher than the engine speed at which knocking occurs, control for not supplying the hydrogen-rich gas by the hydrogen-rich gas supply device And an internal combustion engine comprising the device. The internal combustion engine according to claim 4,
The internal combustion engine, wherein the control device supplies the hydrogen-rich gas by the hydrogen-rich gas supply device when the detected engine speed is lower than the engine speed at which knocking occurs. The internal combustion engine according to claim 4 or claim 5,
The spark ignition device is an internal combustion engine that performs spark ignition at an ignition timing at which the most output can be obtained. An internal combustion engine that obtains output by burning an air-fuel mixture supplied into a cylinder,
A main fuel supply device for supplying main fuel,
A hydrogen-rich gas supply device for supplying hydrogen-rich gas directly into the cylinder,
Engine speed detection means for detecting the engine speed of the internal combustion engine,
An acquisition unit that acquires a difference between an ignition timing at which the most output is obtained and an ignition timing at which knocking occurs at the detected engine speed;
Determining means for determining an amount of hydrogen-rich gas supplied by the hydrogen-rich gas supply device based on the obtained difference,
An internal combustion engine comprising: a spark ignition device that performs spark ignition at an ignition timing at which the most output can be obtained with respect to a mixture containing the main fuel and hydrogen-rich gas. The internal combustion engine according to claim 7,
The main fuel is gasoline fuel,
The hydrogen-rich gas is pure hydrogen gas,
An internal combustion engine in which an amount of the hydrogen-rich gas supplied by the hydrogen-rich gas supply device is in a range of 10 to 30% of a total amount of heat required in the internal combustion engine in terms of calorific value. An internal combustion engine that obtains output by burning an air-fuel mixture supplied into a cylinder,
A knocking detector that detects occurrence of knocking in the internal combustion engine;
Engine speed detection means for detecting the engine speed of the internal combustion engine,
A fuel supply amount determining unit that determines a hydrogen-rich gas amount and a main fuel amount to be supplied based on the detected engine speed when knocking is detected by the knocking detector;
A hydrogen-rich gas supply device for directly supplying the determined amount of hydrogen-rich gas into the cylinder;
A main fuel supply device for supplying the determined amount of main fuel;
An internal combustion engine comprising: a spark ignition device for spark-igniting an air-fuel mixture containing the main fuel and hydrogen-rich gas. The internal combustion engine according to claim 9,
The internal combustion engine supplies the hydrogen-rich gas into the cylinder during a compression stroke of the internal combustion engine. The internal combustion engine according to claim 10,
The fuel supply amount determining means,
Requested heat amount determining means for determining the total heat amount required according to the operating state of the internal combustion engine,
A calorific-ratio determining means for determining a calorific ratio of the hydrogen gas-rich gas to the total calorific value based on the detected engine speed,
Hydrogen-rich gas amount determining means for determining a hydrogen-rich gas amount corresponding to the determined heat amount ratio of the hydrogen-rich gas,
An internal combustion engine comprising: a main fuel amount determining means for determining a heat amount ratio of the main fuel from the total heat amount and a heat amount ratio of the hydrogen-rich gas, and determining a main fuel amount corresponding to the calculated heat amount ratio of the main fuel. The internal combustion engine according to any one of claims 9 to 11,
The main fuel is gasoline fuel,
The hydrogen-rich gas is pure hydrogen gas,
The internal combustion engine, wherein a calorific value ratio of the hydrogen-rich gas determined by the calorific value ratio determining means is in a range of 10 to 30% of the total calorific value. A combustion control method in a spark ignition type internal combustion engine,
Determine the total amount of heat required according to the operating state of the internal combustion engine,
Supplying an amount of hydrogen corresponding to 10% to 30% of the total amount of heat directly into the cylinder of the internal combustion engine in terms of the amount of heat,
In terms of calorific value, supply the main fuel in an amount corresponding to 90% to 70% of the total caloric value,
A method for spark-igniting an air-fuel mixture containing the main fuel and hydrogen. A combustion control method in a spark ignition type internal combustion engine,
Detecting the engine speed of the internal combustion engine,
If the detected engine speed is less than the engine speed at which knocking occurs, supply the main fuel to the internal combustion engine and supply hydrogen-rich gas directly into the cylinder of the internal combustion engine,
A method for spark-igniting an air-fuel mixture containing the main fuel and a hydrogen-rich gas. A combustion control method in a spark ignition type internal combustion engine,
Detecting the engine speed of the internal combustion engine,
At the detected engine speed, obtain the difference between the ignition timing at which the most output is obtained and the ignition timing at which knocking occurs,
Determine the amount of hydrogen-rich gas supplied by the hydrogen-rich gas supply device based on the obtained difference,
Supplying the main fuel to the internal combustion engine and supplying the determined amount of hydrogen-rich gas directly into the cylinder of the internal combustion engine,
A method of performing spark ignition at an ignition timing at which the most output can be obtained for a mixture containing the main fuel and hydrogen-rich gas. A combustion control method in a spark ignition type internal combustion engine,
Detecting the occurrence of knocking in the internal combustion engine,
Detecting the engine speed of the internal combustion engine,
If the occurrence of knocking is detected, determine the amount of hydrogen-rich gas and the amount of main fuel to be supplied based on the detected engine speed,
Supplying a determined amount of main fuel to the internal combustion engine and directly supplying the determined amount of hydrogen-rich gas into the cylinder;
A method for spark-igniting an air-fuel mixture containing the main fuel and a hydrogen-rich gas.

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