JP2006328981A - Ignition control device for internal combustion engine utilizing hydrogen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of excessive knocking during addition of hydrogen gas. <P>SOLUTION: The device is equipped with a knocking control means (KCS control means 30B<SB>1</SB>) for controlling knocking by retarding ignition timing IG of an ignition plug 60 at the time of knocking detection, and a maximum retard ignition timing setting means 30B<SB>2</SB>for expanding to a retarded side a retarded side limit ignition timing (maximum retard ignition timing IGr<SB>H2</SB>at combustion with addition of hydrogen) when the knocking control means (KCS control means 30B<SB>1</SB>) carrying out retarding control during addition of hydrogen gas in accordance with addition ratio AD<SB>H2</SB>of hydrogen gas compared with the case of combustion carried out by hydrocarbon fuel only. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ignition control device for a hydrogen-utilizing internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel.

  Conventionally, there are hydrogen-based internal combustion engines that utilize the rapid combustion characteristics of hydrogen gas. This hydrogen-utilized internal combustion engine uses both hydrocarbon fuel and hydrogen gas as fuel, and can be burned at a leaner air-fuel ratio by adding hydrogen gas than when it is not added. This makes it possible to further reduce substances (NOx) and improve combustion efficiency. For example, this type of hydrogen-utilizing internal combustion engine is disclosed in Patent Document 1 below.

  By the way, regardless of whether or not hydrogen gas is added, in an internal combustion engine, it is preferable to ignite at an MBT ignition timing (minimum advance for best torque: optimum ignition timing at which maximum torque can be obtained) in order to obtain a high shaft torque. .

  However, since the internal combustion engine is operated under various operating conditions, for example, in order to suppress the occurrence of excessive knocking, it is necessary to ignite on the retard side from the MBT ignition timing. For this reason, a conventional internal combustion engine is provided with a knock control system (KCS) that retards or advances the ignition timing so as not to cause excessive knocking. For example, as such a knock control system, Patent Literature 2 below discloses an ignition control device for an internal combustion engine that performs combustion using only hydrocarbon fuel.

  Here, the shaft torque decreases as the ignition timing becomes more retarded than the MBT ignition timing. For this reason, if the ignition timing is excessively retarded, the shaft torque is extremely reduced, which is not preferable.

  Therefore, in the ignition control device disclosed in Patent Document 2, a retard guard value is set so as to prevent the ignition timing from being retarded any further, and the spark angle is advanced to the limit at which knocking occurs (hereinafter referred to as “knock”). By limiting the retard control at the retard side limit ignition timing that is retarded by the angle of the retard guard value from the "limit"), extreme shaft torque reduction is suppressed. In Patent Document 2, the retard guard value is changed in accordance with the open / closed state of the airflow control valve provided in the intake passage.

JP 2004-116398 A JP 2004-11519 A

  Here, the MBT ignition timing and the ignition timing at the knock limit (hereinafter referred to as “trace knock point”) are different between the combustion state with only hydrocarbon fuel and the combustion state with addition of hydrogen gas, respectively. The MBT ignition timing and the trace knock point shift toward the retard side as the hydrogen gas addition ratio (hereinafter referred to as “hydrogen addition ratio”) increases.

  Therefore, if the retard control is executed with the same retard guard value in the two combustion states, that is, the hydrocarbon fuel similar to the ignition control device disclosed in Patent Document 2 in each combustion state. If the retard control of the ignition timing is performed with the retard retard value for use, when hydrogen gas is added, it is restricted by the retard guard value and cannot be retarded any further. Thus, for example, the ignition timing cannot be retarded to the trace knock point at the time of hydrogenation combustion, and excessive knocking may occur. In addition, the interval between the trace knock point and the retarded limit ignition timing becomes narrow, and the ignition timing may not be retarded to a region where excessive knocking does not occur.

  Therefore, the present invention improves the disadvantages of the conventional example, and suppresses the occurrence of excessive knocking even when hydrogen gas is added in a hydrogen-based internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel. An object of the present invention is to provide an ignition control device for a hydrogen-utilizing internal combustion engine.

  In order to achieve the above object, according to the first aspect of the present invention, in the ignition control device for a hydrogen-using internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel, the ignition timing of the spark plug is retarded when knocking is detected. Knocking control means for controlling knocking, and the limit ignition timing on the retard side when the knocking control means retards the control when hydrogen gas is added, according to the addition ratio of the hydrogen gas. And a most retarded ignition timing setting means for enlarging the retarded side more than the case.

  According to the ignition control device of the first aspect, the combustion state with only the hydrocarbon fuel is different from the combustion state when hydrogen gas is added, and is set further on the retard side than that with the hydrocarbon fuel. It is possible to extend the retarded limit ignition timing at the time of hydrogen addition combustion to the retard angle side, and to extend the retard control range at the time of hydrogen addition combustion. For this reason, the ignition timing can be retarded to a region where excessive knocking does not occur during hydrogenation combustion, and excessive knocking can be suppressed.

  Here, if the limit ignition timing on the retarded side during hydrogen addition combustion is not shifted to the retarded side as the hydrogen gas addition ratio increases, the ignition timing is retarded to a region where excessive knocking does not occur. It may not be possible to Therefore, as in the invention according to claim 2, in the ignition control device according to claim 1, the most retarded ignition is performed so that the retarded limit ignition timing is increased to the retarded side as the hydrogen gas addition ratio increases. It is preferable to constitute a time setting means. According to this, it is possible to set the optimum retarded ignition timing on the retard side according to the hydrogen gas addition ratio, and effectively suppress the occurrence of excessive knocking according to the change in the hydrogen gas addition ratio. be able to.

  In order to achieve the above object, according to a third aspect of the present invention, in the ignition control device for a hydrogen-utilizing internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel, the ignition timing of the spark plug is delayed when knocking is detected. A knocking control means for controlling the knocking at an angle, and a retarding speed by expanding the ignition delay control amount when the knocking control means retards the addition of hydrogen gas as compared with the case of combustion with only hydrocarbon fuel. And retard angle speed setting means for speeding up the operation.

  According to the ignition control device of the third aspect, the ignition timing at the time of hydrogen addition combustion differs between the combustion state with only hydrocarbon fuel and the combustion state at the time of adding hydrogen gas, and the hydrocarbon fuel It is possible to retard the ignition timing earlier to the ignition timing at the knock limit which is further retarded than the time. For this reason, during hydrogenation combustion, the ignition timing is quickly retarded to a region where excessive knocking does not occur, so that excessive knocking during the transition period during knocking control can be suppressed.

  Here, during hydrogen addition combustion, the combustion rate increases as the proportion of hydrogen gas added increases, and further, the knock limit on the retard side during hydrogen addition combustion shifts to the retard side. If the speed is not made faster, excessive knocking may occur during the transition period. Therefore, as in the invention according to claim 4, in the ignition control device according to claim 3, it is preferable that the retarding speed setting means is configured to increase the ignition retarding control amount as the hydrogen gas addition ratio increases. . According to this, it is possible to set an optimal retarding speed according to the addition ratio of hydrogen gas, and to effectively suppress the occurrence of excessive knocking during the transition period according to the change in the addition ratio of hydrogen gas. it can.

  The ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention can control the retarded-side limit ignition timing to an optimum value according to the addition ratio of hydrogen gas by the above-described most retarded ignition timing setting means. The occurrence of excessive knocking when hydrogen gas is added can be suppressed. In addition, the ignition control device can control the retarding speed during the retarding control to an optimum speed according to the addition rate of the hydrogen gas by the retarding speed setting means described above, so that the knocking at the time when the hydrogen gas is added It is possible to suppress the occurrence of excessive knocking during the control transition period.

  Embodiments of an ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

  A first embodiment of an ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention will be described with reference to FIGS.

  First, the configuration of a hydrogen-utilized internal combustion engine to which the ignition control device of the first embodiment is applied will be described with reference to FIG. Reference numeral 10 in FIG. 1 indicates the hydrogen-utilizing internal combustion engine of the first embodiment. Although the combustion chamber 11 having only one cylinder is shown here, the present invention is also applicable to a multi-cylinder internal combustion engine regardless of the type such as in-line or V-type.

  A hydrogen-utilizing internal combustion engine 10 according to the first embodiment includes a cylinder head 12, a cylinder block 13, and a piston 14 that form a combustion chamber 11, as shown in FIG. Here, the cylinder head 12 and the cylinder block 13 are fastened with bolts or the like via the head gasket 15 shown in FIG. 1, and the recess 12a on the lower surface of the cylinder head 12 and the cylinder bore 13a of the cylinder block 13 formed thereby. In the space, the piston 14 is disposed so as to be reciprocally movable. The combustion chamber 11 described above is constituted by a space surrounded by the wall surface of the recess 12 a of the cylinder head 12, the wall surface of the cylinder bore 13 a, and the top surface 14 a of the piston 14.

  Here, air and fuel are supplied into the combustion chamber 11 from the outside.

  First, air from the outside is supplied into the combustion chamber 11 via the intake passage 20 shown in FIG. The intake passage 20 of the first embodiment includes an intake passage 21 for introducing air from the outside, and an intake port 22 of the cylinder head 12 that supplies the air in the intake passage 21 into the combustion chamber 11.

On the intake passage 21 constituting the intake passage 20, an air cleaner 23 for removing foreign matters such as dust from the introduced air in order from the outside, an air flow meter 24 for detecting the intake air amount Ga _out from the outside, A throttle valve 25 for adjusting the intake air amount Ga into the combustion chamber 11 and a throttle valve actuator 26 for opening and closing the throttle valve 25 are provided.

The detection signal of the air flow meter 24 is sent to an electronic control unit (ECU) 30 which is a control means of the hydrogen-utilizing internal combustion engine 10, and the intake air amount Ga _out from the outside is calculated based on the detection signal. Further, the ECU 30 issues a control command for the valve opening angle of the throttle valve 25 to the throttle valve actuator 26, and a desired intake air amount Ga corresponding to the engine operating state of the hydrogen-utilizing internal combustion engine 10 is set in the combustion chamber 11. Inhaled into the mouth.

  On the other hand, one end of the intake port 22 constituting the intake path 20 is open to the combustion chamber 11, and an intake valve 27 that can open and close the opening is disposed in the opening portion. For this reason, air is sucked into the combustion chamber 11 from the intake port 22 by opening the intake valve 27, while the inflow of air into the combustion chamber 11 is blocked by closing the intake valve 27. Is done.

  The number of openings into the combustion chamber 11 in the intake port 22 may be one or more, and an intake valve 27 is provided for each opening. In addition, when a so-called variable valve mechanism that can appropriately adjust the opening / closing timing and lift amount of the intake valve 27 according to operating conditions or the like is provided, the operation of the variable valve mechanism is controlled by the ECU 30 described above.

  Further, in the hydrogen-utilizing internal combustion engine 10 of the first embodiment, fuel is also supplied into the combustion chamber 11 via the intake passage 20. Here, as the fuel of the hydrogen-utilizing internal combustion engine 10, two kinds of fuels, hydrocarbon fuel (here, gasoline is illustrated) and hydrogen gas are used. For this reason, the cylinder head 12 of the first embodiment is supplied via the hydrocarbon fuel injection device 40 for injecting the hydrocarbon fuel supplied via the hydrocarbon fuel supply means to the intake port 22 and the hydrogen gas supply means. A hydrogen gas injection device 50 for injecting hydrogen gas into the intake port 22 is provided.

  In the first embodiment, as the hydrocarbon fuel supply means, a fuel tank 41 that stores liquid hydrocarbon fuel, and a hydrocarbon that guides the hydrocarbon fuel in the fuel tank 41 to the hydrocarbon fuel injection device 40 A fuel supply passage 42, a fuel pump 43 that sucks up the hydrocarbon fuel in the fuel tank 41 and pressurizes it to a predetermined pressure, and sends it out, and the pressure of the hydrocarbon fuel sent out from the fuel pump 43 is used as a hydrogen internal combustion engine. And a regulator 44 that adjusts to a desired pressure according to the engine operating state of the engine 10.

  The hydrogen gas supply means includes a hydrogen fuel tank 51 in which compressed high-pressure hydrogen gas is stored, and a hydrogen gas supply path 52 that guides the hydrogen gas in the hydrogen fuel tank 51 to the hydrogen gas injection device 50. The hydrogen fuel pump 53 that sucks up the hydrogen gas in the hydrogen fuel tank 51 and pressurizes the hydrogen gas to a predetermined pressure, and sends it out. A regulator 54 that adjusts to a desired pressure according to the operating state is provided.

Here, the ECU 30 of the first embodiment is provided with a fuel injection control device 30A that performs fuel injection control as one of the control functions. By the hydrocarbon fuel injection control means 30A _{1 of} this fuel injection control device 30A. The operations of the hydrocarbon fuel injection device 40 and the fuel pump 43 and the regulator 44 of the hydrocarbon fuel supply means are controlled, and hydrocarbon fuel is injected at an injection amount and injection timing according to the engine operating state of the hydrogen-utilizing internal combustion engine 10. .

On the other hand, the fuel injection control device 30A is also provided with a hydrogen gas injection device 50, and a hydrogen addition control means 30A ₂ for controlling the operation of the fuel pump 53 and the regulator 54 of the hydrogen gas supply means. Hydrogen gas injection control is executed at an injection amount and an injection timing according to the engine operating state of the engine 10. This hydrogen addition control means 30A ₂ sets a ratio (hydrogen addition ratio) AD _H2 of the injection amount of hydrogen gas to the injection amount of hydrocarbon fuel according to the engine operating state, and based on this, sets the injection amount of hydrogen gas. decide. The hydrogen addition ratio AD _H2 may be the ratio of the hydrogen gas injection amount to the total fuel amount required for the hydrogen-utilizing internal combustion engine 10.

  With such a configuration, intake air amount Ga and injection amount of air according to the engine operating state, hydrocarbon fuel and / or hydrogen gas are supplied to the combustion chamber 11, and the spark plug shown in FIG. It is ignited at 60.

  For example, when performing lean combustion, the ECU 30 controls the valve opening angle of the throttle valve 25 and the injection timing and injection amount of each of the hydrocarbon fuel injection device 40 and the hydrogen gas injection device 50 to enter the combustion chamber 11. A lean air-fuel ratio mixture is formed in accordance with the engine operating state consisting of hydrocarbon fuel, hydrogen gas, and air. An ignition control device 30B provided as one of the control functions of the ECU 30 ignites the air-fuel mixture from the ignition plug 60, and causes the hydrogen-utilized internal combustion engine 10 to perform combustion.

Here, since the hydrogen gas has a characteristic of performing rapid combustion as compared with the hydrocarbon fuel, the MBT ignition timing is shifted to the retard side as compared with the combustion of only hydrocarbon combustion, as shown in FIG. In the combustion at the time of hydrogen addition, combustion efficiency is improved and knocking is improved as compared with combustion with only hydrocarbon fuel. In FIG. 2, for the sake of convenience, only the case of hydrocarbon fuel (gasoline) and the case where the hydrogen addition ratio _ADH2 is 10% are shown. Further, as the combustion efficiency is improved, the air-fuel ratio can be shifted to a leaner region side (that is, the lean limit can be extended), so that the fuel consumption rate can be reduced by adding hydrogen gas, Reduction of emissions such as NOx (nitrogen oxide) and THC (total hydrocarbons) can be achieved.

By the way, in any case of combustion with only hydrocarbon fuel or combustion with hydrocarbon fuel and hydrogen gas, knocking will occur unless ignition is performed at an accurate ignition timing IG according to the engine operating state. For this reason, the ignition control device 30B of the ECU 30 according to the first embodiment causes excessive knocking by retarding or advancing the ignition timing IG according to whether or not knocking (knock vibration) is detected from the knock sensor 71. Knocking control means (hereinafter referred to as “KCS control means”) 30B _{1 to} be suppressed is provided.

Specifically, the KCS control means 30B ₁ sets the ignition timing IG of the spark plug 60 at a predetermined angle (hereinafter referred to as “ignition delay”) until knocking does not occur or slight knocking is detected when knocking is detected. "Angle main control amount")) Delay control is performed by SR. On the other hand, when knocking is not detected, the ignition timing IG of the spark plug 60 is referred to as a predetermined angle (hereinafter referred to as “ignition advance main control amount”) so that the knocking is mild within a range where knocking does not occur or even if it occurs. ) Advance angle control by SF.

Further, the KCS control means 30B ₁ is configured so that when the knocking is not detected by the retarding control of each ignition retarding main control amount SR, the above-mentioned ignition is controlled so as to suppress the knocking to a limit or mild knocking. The advance control of the ignition timing IG is performed at an angle smaller than the advance angle main control amount SF (hereinafter referred to as “ignition advance angle sub control amount”) SF _sub . On the other hand, when excessive knocking is detected by the advance control of each ignition advance main control amount SF, the above-mentioned ignition retard main control amount SR is used until knocking does not occur or slight knocking occurs. The ignition timing IG is retarded at a smaller angle (hereinafter referred to as “ignition retarding sub-control amount”) SR _sub .

For example, in the first embodiment, the main ignition delay main control amount SR when the KCS control means 30B ₁ performs the retard control and the main ignition advance main control amount SF when the advance control is performed are 1 respectively. The ignition retard sub-control amount SR _sub and the ignition advance sub-control amount SF _sub are each set to 0.2 ° CA.

Here, as is apparent from FIG. 2, the ignition timings (trace knock points TK _gas , TK _H2 ) at the advance side of each of the advance angles are not less than the MBT ignition timing, regardless of whether hydrocarbon fuel combustion or hydrogenation combustion is performed. since also retarded, KCS controller 30B ₁ described above, the MBT trace knock point to retard side of ignition timing TK _gas, retarding the ignition timing IG toward the TK _H2.

However, since the occurrence of excessive knocking is not always suppressed at the trace knock points TK _gas and TK _H2 , the ignition timing IG may be further retarded, but the shaft torque gradually increases with the MBT ignition timing as a boundary. Therefore, if the ignition timing IG is retarded excessively, the shaft torque is greatly reduced. For this reason, in the first embodiment, a retard side limit ignition timing (hereinafter referred to as “most retarded ignition timing”) IGr for suppressing excessive retard control during KCS control is set. The retarded ignition timing IG is regulated by the set most retarded ignition timing IGr.

By the way, since the knocking can be improved by adding hydrogen gas as described above, the difference (ΔSA) between the MBT ignition timing and the trace knock point is reduced as compared with the time of hydrocarbon fuel combustion as shown in FIG. Torque can be obtained, but by adding the hydrogen gas, as shown in FIG. 2, the trace knock point TK _H2 at the time of hydrogen addition combustion is retarded from the trace knock point TK _gas at the time of hydrocarbon fuel combustion. There is a case. Therefore, for example, if KCS control is performed during hydrogen addition combustion using the same most retarded ignition timing IGr as during hydrocarbon fuel combustion, the trace knock point TK during hydrogen addition combustion is greater than the most retarded ignition timing IGr. _H2 and when in the advance angle side, and the gap between the most retarded ignition timing IGr and trace knock point TK _H2 is narrow, making it possible to retard the ignition timing IG than its most retarded ignition timing IGr There is a risk that excessive knocking may occur during hydrogenation combustion.

Therefore, in the first embodiment, the most retarded ignition timing for setting different retarded ignition timings IGr _gas and IGr _H2 in each of the combustion state with only hydrocarbon fuel and the combustion state when hydrogen gas is added. Timing setting means 30B ₂ is provided in the ignition control device 30B.

Here, the most retarded ignition timings IGr _gas and IGr _{H2 according to the} first embodiment are determined from a knock limit ignition timing (trace knock points TK _gas and TK _H2 ) by a predetermined retard margin (hereinafter referred to as “retard guard value”). It is defined as the ignition timing when retarded by RG _gas and RG _H2 . Therefore, the most retarded ignition timings IGr _gas and IGr _H2 are obtained by the most retarded ignition timing setting means 30B ₂ from the trace knock points TK _gas and TK _H2 and the retard guard values RG _gas and RG _H2 , respectively. be able to.

First, the trace knock points TK _gas and TK _H2 will be described.

The trace knock points TK _gas and TK _H2 differ between the combustion state using only hydrocarbon fuel and the combustion state using hydrocarbon fuel and hydrogen gas, but more strictly, even in the same combustion state, the air-fuel ratio and hydrogen It varies depending on the addition ratio AD _{H2 and the} like, and during hydrogen addition combustion, as the hydrogen addition ratio AD _H2 increases, it shifts to the retard side.

Therefore, map data (a hydrocarbon fuel combustion TK point map, a hydrogen addition combustion TK point map) is divided into a trace knock point TK _gas at the time of hydrocarbon fuel combustion and a trace knock point TK _H2 at the time of hydrogen addition combustion. Prepared and the most retarded ignition timing setting means 30B ₂ reads the trace knock points TK _gas and TK _H2 as appropriate from this map data and uses them to calculate the most retarded ignition timings IGr _gas and IGr _H2 .

The hydrocarbon fuel combustion TK point map indicates the ignition timing (trace knock point TK _gas ) at the advance side knock limit according to the engine operating state such as the engine speed Ne and the engine load factor Kl and the air-fuel ratio. It is obtained by experiments and simulations, and these correspondences are stored. On the other hand, the hydrogenation and the combustion time of TK point map, the engine speed Ne and the engine load ratio engine operating condition and the air-fuel ratio and further the ignition timing on the advance side knock limit of in accordance with the hydrogen addition ratio AD _H2 such Kl ( The trace knock point TK _H2 ) is obtained in advance by experiments and simulations, and the corresponding relationship is stored.

  Here, the engine speed Ne is calculated based on the detection signal of the crank angle sensor 72 shown in FIG. On the other hand, the engine load factor Kl is a value indicating the current load ratio with respect to the maximum engine load. The engine load factor Kl is calculated based on, for example, the valve opening angle of the throttle valve 25 (that is, a value corresponding to the intake air amount Ga into the combustion chamber 11) and the engine speed Ne.

Next, the retard angle guard values RG _gas and RG _H2 will be described.

First, the retard guard value (hereinafter referred to as “hydrocarbon fuel retard guard value”) RG _gas at the time of combustion of hydrocarbon fuel is determined by the engine operating state such as the engine speed Ne and the engine load factor Kl and the air-fuel ratio. A corresponding value is obtained in advance by experiments and simulations, and is prepared as a hydrocarbon fuel retard angle guard value map consisting of the corresponding relationship.

This because, the most retarded ignition timing setting section 30B _2, the hydrocarbon fuel retard guard value map based on the engine operating state and the air-fuel ratio read the hydrocarbon fuel retard guard value RG _gas, which hydrocarbon fuel A retard guard value (hereinafter referred to as “KCS control retard guard value”) RG _KCS when performing KCS control during combustion is set. The ignition timing IG is set to the KCS control retard guard value RG _KCS (= hydrocarbon fuel retard guard value RG _gas ) based on the trace knock point TK _gas read from the hydrocarbon fuel combustion TK point map. The ignition timing at that time is retarded and set as the most retarded ignition timing IGr _gas at the time of hydrocarbon fuel combustion.

On the other hand, at the time of hydrogen addition combustion, a retarded guard value at the time of hydrogen addition combustion (hereinafter referred to as “the engine speed Ne and engine load factor Kl”, etc., the air fuel ratio, and further the hydrogen addition ratio AD _H2. Hydrogen addition retarded guard value ") RG _H2 is prepared in advance as map data (hydrogen addition retarded guard value map) in the same manner as in the above-described hydrocarbon fuel combustion, and the hydrogen addition obtained by using this The retard guard value RG _H2 may be set as the KCS control retard guard value RG _KCS during hydrogenation combustion. In such a case, the most retarded ignition timing setting means 30B ₂ uses the trace knock point TK _H2 read from the hydrogen addition combustion time TK point map as a base point to change the ignition timing IG to the KCS control retard guard value RG _KCS (= hydrogen addition delay). The ignition timing at that time is retarded by the angle guard value RG _H2 ), and the ignition timing at that time is set as the most retarded ignition timing IGr _H2 during hydrogenation combustion.

However, in the first embodiment, the hydrocarbon fuel retardation guard value RG _gas corrected according to the hydrogen addition ratio AD _H2 is set as the KCS control retardation guard value RG _KCS at the time of hydrogen addition combustion.

Specifically, the correction value in the retard guard value during the hydrogenation combustion in accordance with the hydrogen addition ratio AD _H2 (hereinafter, referred to as "hydrogenated retarded guard correction value".) Obtained in advance by experiment or simulation and RGc, its The correspondence is prepared as a retard guard correction value map shown in FIG. The hydrogen addition retardation guard correction value RGc increases as the hydrogen addition ratio AD _H2 increases as shown in FIG.

Then, the most retarded ignition timing setting means 30B ₂ reads the hydrocarbon fuel retard angle guard value RG _gas corresponding to the engine operating state and the air-fuel ratio from the hydrocarbon fuel retard angle guard value map, and the hydrogen addition ratio at that time Based on AD _H2 , the hydrogen addition retard guard correction value RGc is read from the retard guard correction value map, and these are added to expand the retard control range of the KCS control retard guard value RG _KCS. Set as KCS control retard angle guard value RG _KCS . In such a case, the most retarded ignition timing setting means 30B ₂ uses the trace knock point TK _gas read from the TK point map at the time of hydrocarbon fuel combustion as a base point to set the ignition timing IG to the KCS control retard guard value RG _KCS (= hydrocarbon). The fuel retarded angle is retarded by the fuel retarded guard value RG _gas + hydrogen addition retarded guard correction value RGc), and the ignition timing at that time is set as the most retarded ignition timing IGr _H2 during the hydrogenated combustion.

In the KCS control means 30B ₁ of the first embodiment, the ignition timing IG enters the retarded side with respect to the most retarded ignition timings IGr _gas and IGr _H2 set by the most retarded ignition timing setting means 30B ₂ as described above. KCS control is executed so that there is no.

As a result, in the hydrogen-utilizing internal combustion engine 10 of the first embodiment, excessive knocking is suppressed regardless of whether or not hydrogen gas is added, by using the most retarded ignition timings IGr _gas and IGr _H2 according to the respective combustion states. In addition, combustion can be performed in the combustion chamber 11 while suppressing a significant decrease in shaft torque.

  The in-cylinder gas after the combustion is discharged from the combustion chamber 11 to the exhaust path 80 shown in FIG. The exhaust path 80 includes an exhaust port 81 of the cylinder head 12 into which in-cylinder gas after combustion flows from an opening between the combustion chamber 11 and an exhaust passage 82 communicating with the exhaust port 81.

  Here, an exhaust valve 83 that can open and close an opening between the exhaust port 81 and the combustion chamber 11 is disposed in the exhaust port 81 constituting the exhaust path 80. Therefore, the in-cylinder gas after combustion is discharged from the combustion chamber 11 to the exhaust port 81 by opening the exhaust valve 83, and the in-cylinder gas exhaust port 81 is closed by closing the exhaust valve 83. Is blocked.

  The number of openings into the combustion chamber 11 in the exhaust port 81 may be one or plural, and the exhaust valve 83 described above is provided for each opening. In addition, when a so-called variable valve mechanism that can appropriately adjust the opening / closing timing and lift amount of the exhaust valve 83 according to operating conditions or the like is provided, the operation of the variable valve mechanism is controlled by the ECU 30 described above.

  Next, the KCS control operation by the ignition control device 30B of the first embodiment will be described based on the flowcharts of FIGS.

First, in the ignition control device 30B of the first embodiment, as shown in the flowchart of FIG. 4, whether or not the hydrogen addition control means 30A ₂ of the fuel injection control device 30A is executing hydrogen addition control by the KCS control means 30B ₁ . It is determined whether or not (step ST1). For example, in the first embodiment, whether or not the hydrogen addition control is being executed by the KCS control means 30B ₁ based on the execution flag set when the hydrogen addition control means 30A ₂ executes the hydrogen addition control is determined. Let them judge.

Here, when the KCS control means 30B ₁ determines that the hydrogen addition control is being executed, the most retarded ignition timing setting means 30B ₂ of the ignition control device 30B uses the hydrogen addition ratio AD _H2 set by the hydrogen addition control means 30A _2. Reading (step ST2), the hydrogen addition retard guard correction value RGc corresponding to the hydrogen addition ratio AD _H2 is read from the retard guard correction value map of FIG. 3 (step ST3).

Thereafter, the most retarded ignition timing setting means 30B ₂ sets the hydrocarbon fuel retarded guard value RG _gas based on the engine operating state such as the current engine speed Ne and the engine load factor Kl and the air-fuel ratio. Read from the hydrocarbon fuel retard angle guard value map, add the hydrogen addition retard angle guard correction value RGc to this hydrocarbon fuel retard angle guard value RG _gas , and add this to the KCS control retard angle guard value RG _KCS during the hydrogen addition combustion. (= RG _gas + RGc) is set (step ST4).

For example, as shown in FIG. 3, when the hydrogen addition rate AD _H2 is 10%, the hydrogen addition retard guard correction value RGc is 7.5 ° CA, and this and the hydrocarbon fuel retard guard value shown in FIG. A value (9.5 ° CA) obtained by adding RG _gas (= 2 ° CA) is set as the KCS control retardation guard value RG _KCS at the time of hydrogenation combustion.

Then, the most retarded ignition timing setting means 30B ₂ is provided with a trace knock at the time of hydrocarbon fuel combustion based on the engine operating state such as the engine speed Ne used when setting the KCS control retard guard value RG _KCS and the air-fuel ratio. The point TK _gas is read from the above-mentioned hydrocarbon fuel combustion TK point map (step ST5), and based on the trace knock point TK _gas and the KCS control retard guard value RG _KCS set in step ST4, during hydrogen addition combustion The most retarded ignition timing IGr _H2 is set (step ST6).

Ignition control device 30B of the first embodiment, then, executes the KCS control during hydrogenation burned by KCS control means 30B ₁ (step ST7). The KCS control at this time is executed as follows.

As shown in the flowchart of FIG. 5, the KCS control means 30B ₁ suppresses knocking if it occurs at the current ignition timing IG, and suppresses knocking if the knocking is not occurring, while increasing the shaft torque. Thus, the ignition timing IG of the spark plug 60 is controlled.

Specifically, the KCS control means 30B ₁ first determines whether or not knocking has occurred from the detection signal of the knock sensor 71 (step ST7A).

Here, when it is determined that knocking has occurred, the KCS control means 30B ₁ retards the ignition timing IG by the ignition retard main control amount SR described above (step ST7B), and again whether knocking has occurred. Is determined (step ST7C). If knocking also occurs at this time, the process returns to step ST7B, and the retard control of the ignition retard main control amount SR is repeated until knocking is not detected in step ST7C. Then, after no detected knocking in that step ST7c, KCS controller 30B _1, only the ignition advance sub control amount SF _sub mentioned above the ignition timing IG advance control (step ST7d), ignition at that time Returning to step ST1 while maintaining the time IG, the same operation is repeated.

On the other hand, when the knocking is determined to not occurred, KCS controller 30B ₁ is the only ignition advance main control amount SF of the ignition timing IG advance control described above (step ST7E), again occurrence or non-occurrence of knocking Is determined (step ST7F). If knocking has not occurred at this time, the process returns to step ST7E, and the advance control of the ignition advance main control amount SF is repeated until knocking is detected in step ST7F. After the knocking is detected in the step ST7F, KCS controller 30B ₁ controls retarded only the ignition timing IG ignition retard secondary control amount SR _sub as described above (step ST7G), the ignition timing at that time Returning to step ST1 while maintaining IG, the same operation is repeated.

As described above, when hydrogen gas is added, the ignition delay control width (KCS control retard guard value RG _KCS ) to the retard side is increased in accordance with the hydrogen addition ratio AD _H2. It is possible to eliminate the inconvenience of being excessively knocked due to the retard guard value RG _gas being unable to retard further. As a result, the hydrogen-using internal combustion engine 10 can be efficiently operated with a high shaft torque within a range in which the occurrence of knocking can be suppressed.

  In the first embodiment, in steps ST7A, ST7C, and ST7F, it is determined that only knocking has occurred or not. However, if knocking has occurred, this may be determined. It may be allowed to return to step ST1.

Next, KCS controller 30B ₁ at step ST1 is not performing hydrogen addition control (i.e., only the combustion control hydrocarbon fuel is being performed) for when it is determined that, returning to FIG. 4 described To do. In such a case, the most retarded ignition timing setting section 30B ₂ of the ignition control device 30B, similar to the step ST4 reads the hydrocarbon fuel retard guard value RG _gas from a hydrocarbon fuel retard guard value map, carbonizing this A KCS control retard guard value RG _KCS at the time of hydrogen fuel combustion is set (step ST8).

Thereafter, the most retarded ignition timing setting means 30B ₂ reads the trace knock point TK _gas at the time of hydrocarbon fuel combustion from the TK point map at the time of combustion of hydrocarbon fuel (step ST9), as in step ST5 described above. Based on the trace knock point TK _gas and the KCS control retard guard value RG _KCS set in step ST8, the most retarded ignition timing IGr _gas at the time of hydrocarbon fuel combustion is set (step ST10).

Then, KCS controller 30B ₁ of the ignition control device 30B proceeds to step ST7, executes KCS controlled in the same manner as the flow chart of FIG. Thereby, the hydrogen-utilized internal combustion engine 10 can be operated with a high shaft torque within a range in which the occurrence of knocking can be suppressed.

As described above, according to the ignition control device 30B of the first embodiment, the hydrocarbon fuel combustion is based on the KCS control retardation guard value RG _KCS (hydrocarbon fuel retardation guard value RG _gas ) similar to the conventional one. KCS control is performed at the most retarded ignition timing IGr _gas , and excessive knocking that may cause problems such as melting of the piston 14 can be suppressed. On the other hand, at the time of hydrogen addition combustion, the KCS control retard angle guard value RG _KCS is expanded according to the hydrogen addition ratio AD _H2 (RG _KCS = RG _gas + RGc), and the most retarded ignition timing IGR _H2 is shifted to the retard side. Therefore, the ignition timing IG can be retarded to a region where excessive knocking does not occur, and the occurrence of excessive knocking can be suppressed.

  Next, a second embodiment of the ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention will be described with reference to FIGS. 2 and 6 to 8.

Here, in the above-described first embodiment, when adding hydrogen gas, the KCS control retardation guard value RG _KCS (hydrocarbon fuel retardation guard value RG _gas ) at the time of hydrocarbon fuel combustion is corrected to the hydrogen addition retardation guard correction. The value is corrected and expanded with the value RGc, and KCS control is performed as a KCS control retard guard value RG _KCS at the time of hydrogen addition combustion to suppress excessive knocking at the time of hydrogen addition combustion.

However, when hydrogen gas is added, the combustion speed increases, so that the knock sensitivity to the ignition timing IG increases. In addition, as described in the first embodiment, the trace knock point TK _H2 at the time of hydrogen addition combustion may be retarded from the trace knock point TK _gas at the time of hydrocarbon fuel combustion as hydrogen gas is added. is there. In particular, the higher the hydrogen addition ratio AD _H2 , the faster the combustion speed, and the trace knock point TK _H2 during hydrogen addition combustion _shifts to the retard side.

For this _reason , even if KCS control is performed during hydrogen addition combustion using the expanded KCS control retard guard value RG _KCS , the retard control is performed with the same ignition retard main control amount SR as during hydrocarbon fuel combustion. Is executed, it takes time to reach the trace knock point TK _H2 during hydrogenation combustion. That is, the ignition retard main control amount SR per one knocking detection is small (in other words, the retarding speed of the ignition timing IG is slow), and it takes time to reach a region where excessive knocking does not occur. For this reason, in the KCS control at the time of hydrogen addition combustion, excessive knocking may continue to occur over a long period of time from the start of control to the end of control or the transition to the trace knock point TK _H2 .

Therefore, in the second embodiment, the retardation angle speed is changed in accordance with the hydrogen addition ratio AD _H2 to suppress excessive knocking in the transition period.

  Reference numeral 100 in FIG. 6 indicates a hydrogen-utilizing internal combustion engine to which the ignition control device of the second embodiment is applied. The hydrogen-utilizing internal combustion engine 100 and ECU 30 of the second embodiment exemplify those configured similarly to the hydrogen-utilizing internal combustion engine 10 and ECU 30 of the first embodiment described above except for the following configuration. Although the combustion chamber 11 having only one cylinder is shown here, the present invention is also applicable to a multi-cylinder internal combustion engine regardless of the type such as in-line or V-type.

The ignition control device 30B of the second embodiment further includes a retard speed setting means 30B ₃ shown in FIG. 6 that changes the retard speed of the ignition timing IG according to the hydrogen addition ratio AD _H2 in addition to the configuration of the first embodiment. Yes.

Here, the retarding speed represents the ignition retard main control amount SR per one knocking detection as described above. Therefore, in the second embodiment, the ignition retard main control amount SR is set to hydrogen. changing the retard speed by changing depending on the addition rate AD _H2.

For example, the ignition retard main control amount SR _gas at the time of hydrocarbon fuel combustion is set to 1 ° CA as in the first embodiment, and this is set as the retard speed setting means 30B ₃ when executing KCS control at the time of hydrocarbon fuel combustion. Is set as the ignition retard main control amount SR when KCS control is executed during hydrocarbon fuel combustion.

On the other hand, when the retard speed setting means 30B ₃ during hydrogenation combustion for setting the ignition retard main controlled variable SR is correction of the ignition retard main control amount for the time of hydrogenation the combustion in accordance with the hydrogen addition ratio AD _H2 The value (hereinafter referred to as “ignition retard main control amount correction value”) SRc is read from the ignition retard main control amount correction value map shown in FIG. 7 and the ignition retard main control amount during combustion of hydrocarbon fuel. SR _gas is added and set as the ignition retard main control amount SR when KCS control is executed during hydrogenation combustion. The ignition delay main control amount correction value map is obtained by previously obtaining an ignition delay main control amount correction value SRc corresponding to the hydrogen addition ratio AD _H2 through experiments and simulations, and storing the corresponding relationship. The ignition retard main control amount correction value SRc is increased as AD _H2 increases.

  Hereinafter, the KCS control operation by the ignition control device 30B according to the second embodiment will be described with reference to the flowcharts of FIGS.

First, in the ignition control device 30B of the second embodiment, as shown in the flowchart of FIG. 8, the KCS control means 30B ₁ causes the hydrogen addition control means 30A ₂ of the fuel injection control apparatus 30A to execute hydrogen addition control. It is determined whether or not there is (step ST11).

  Here, the ignition control device 30B proceeds to step ST12 if the hydrogen addition control is being executed, and proceeds to step ST20 if the hydrogen addition control is not being executed. In the second embodiment, the processing operations from step ST12 to ST16 and the processing operations from step ST20 to ST22, including step ST11 described above, are the processing from step ST2 to ST6 of the first embodiment described above. Since the operations and the processing operations in steps ST8 to ST10 are the same, the description thereof is omitted here.

First, in the case of hydrogen addition control executed, ignition control device 30B, after setting the most retarded ignition timing IGR _H2 during hydrogenation combustion at step ST16, by the retard speed setting means 30B _3, read in the step ST12 The ignition delay main control amount correction value SRc is read from the ignition delay main control amount correction value map of FIG. 7 in accordance with the hydrogen addition ratio AD _H2 (step ST17).

Thereafter, the retard speed setting means 30B ₃ reads the hydrocarbon fuel ignition retard main controlled variable SR _gas during combustion, during hydrogenation burned by adding therewith a spark retard main control amount correction value SRc The ignition retard main control amount SR is set as SR (= SR _gas + SRc) (step ST18).

For example, as shown in FIG. 7, when the hydrogen addition ratio AD _H2 is 10%, the ignition retard main control amount correction value SRc is 0.25 ° CA. A value (1.25 ° CA) obtained by adding the control amount SR _gas (= 1 ° CA) is set as the ignition retard main control amount SR during hydrogenation combustion.

Then, KCS controller 30B ₁ of the ignition control device 30B executes the KCS control during hydrogenation combustion (step ST19). As a result, the ignition timing IG is retarded with the ignition retard main control amount SR that is expanded in accordance with the hydrogen addition ratio _ADH2 , so that the ignition timing IG is set to the trace knock point at the time of hydrogen addition combustion. TK _H2 can be reached, and excessive knocking in the transition period of KCS control can be suppressed. Note that the KCS control at that time is executed in the same manner as the flowchart of FIG. 5 in the first embodiment except that the numerical value of the ignition retard main control amount SR is different, and thus detailed description thereof is omitted here.

On the other hand, when the hydrogen addition control is not being executed, the ignition control device 30B sets the most retarded ignition timing IGr _gas at the time of hydrocarbon fuel combustion in step ST22, and then uses the retarded speed setting means 30B ₃ to perform carbonization. The ignition retard main control amount SR _gas at the time of hydrogen fuel combustion is read and set as the ignition retard main control amount SR (= SR _gas ) at the time of executing the KCS control at the time of hydrocarbon fuel combustion (step ST23). .

Then, the KCS control means 30B ₁ of the ignition control device 30B proceeds to step ST19 and executes KCS control in the same manner as in the first embodiment.

Note that the setting process of the most retarded ignition timing IGr _H2 at the time of hydrogen addition combustion in steps ST13 to ST16 and the setting process of the ignition retard main control amount SR at the time of hydrogen addition combustion in steps ST17 and ST18 will be performed first. After the setting process of the retard main control amount SR is executed, the setting process of the most retarded ignition timing IGr _H2 may be executed, or the respective setting processes may be executed simultaneously. Further, the setting process of the most retarded ignition timing IGr _gas at the time of hydrocarbon fuel combustion in steps ST20 to ST22 and the setting process of the ignition retard main control amount SR at the time of hydrocarbon fuel combustion in step ST23 are also first ignited. The setting process of the retard main control amount SR may be executed, or may be executed simultaneously.

As described above, according to the ignition control device 30B of the second embodiment, during the combustion of the hydrocarbon fuel, based on the most retarded ignition timing IGR _gas and the ignition retard main control amount SR (= SR _gas ) as in the conventional case. The occurrence of excessive knocking can be suppressed by performing KCS control at the ignition timing IG.

On the other hand, at the time of hydrogen addition combustion, similarly to the first embodiment, the most retarded ignition timing IGr _H2 is set by expanding the KCS control retard guard value RG _KCS (RG _KCS = RG _gas + RGc) according to the hydrogen addition ratio AD _H2. By doing so, the ignition timing IG can be retarded to a region where excessive knocking does not occur, and the occurrence of excessive knocking can be suppressed. Further, since the ignition delay main control amount SR is expanded (SR = SR _gas + SRc) according to the hydrogen addition ratio AD _H2 , the ignition timing IG is retarded to the trace knock point TK _H2 at the time of hydrogen addition combustion at an early stage. And the occurrence of excessive knocking during the transition period of the KCS control can be suppressed.

  Here, in each of the first and second embodiments described above, the naturally-intake hydrogen-utilized internal combustion engines 10 and 100 are illustrated, but the ignition control device 30B according to the present invention has an exhaust between the intake passage 20 and the exhaust passage 80. The present invention may be applied to a hydrogen-utilizing internal combustion engine equipped with a turbocharger. In the hydrogen-utilizing internal combustion engines 10 and 100 of the first and second embodiments, the fuel is injected into the intake port 22 and mixed with the intake air in the combustion chamber 11, but the fuel is burned. The ignition control device 30B according to the present invention may be applied to a so-called in-cylinder direct injection type hydrogen-utilizing internal combustion engine that directly injects into the chamber 11 and mixes with the intake air in the combustion chamber 11.

  As described above, the ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention is useful as a technique that can suppress the occurrence of excessive knocking when hydrogen gas is added.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of a first embodiment of an ignition control device for a hydrogen-utilizing internal combustion engine according to the present invention. It is a figure which shows an example of the relationship of the shaft torque for every ignition timing, Comprising: It is a figure which shows the case where only the hydrocarbon fuel about the relationship and the case where hydrogen gas is added. It is a figure which shows an example of the retard guard correction value map used when setting the KCS control retard guard value at the time of hydrogen addition combustion. 6 is a flowchart illustrating a setting processing operation of a KCS control retardation guard value in the first embodiment. It is a flowchart explaining a KCS control operation. It is a figure shown about the structure of Example 2 of the ignition control apparatus of the hydrogen utilization internal combustion engine which concerns on this invention. It is a figure which shows an example of the ignition retard main control amount correction value map used when setting the ignition retard main control amount at the time of hydrogen addition combustion. 10 is a flowchart for explaining a setting processing operation of a KCS control retard guard value and an ignition retard main control amount setting processing operation in Embodiment 2.

Explanation of symbols

10,100 Hydrogen-utilized internal combustion engine 30 Electronic control unit (ECU)
30B Ignition control device 30B ₁ KCS control means (knocking control means)
30B _{2 most} retarded ignition timing setting means 30B ₃ retard angle speed setting means 40 hydrocarbon fuel injection device 50 hydrogen gas injection device 60 spark plug 71 knock sensor AD _H2 hydrogen addition ratio IG ignition timing IGr _gas latest retarded during hydrocarbon fuel combustion Angle ignition timing IGr _H2 Most retarded ignition timing during hydrogen addition combustion RG _KCS KCS control retard guard value RG _gas Hydrocarbon fuel retard guard value RGc Hydrogen addition retard guard correction value SF Ignition advance control amount SF _sub ignition Advancing sub-control amount SR Ignition retarding main control amount SR _sub Ignition retarding sub-control amount SR _gas Ignition retarding main control amount during hydrocarbon fuel combustion SRc Ignition retarding main control amount correction value TK _{gas During} hydrocarbon fuel combustion Trace knock point of TK Trace knock point during _H2 hydrogenation combustion

Claims (4)

In an ignition control device for a hydrogen-using internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel,
Knocking control means for controlling knocking by retarding the ignition timing of the spark plug when knocking is detected;
The limit ignition timing on the retard side when the knocking control means retards the addition of the hydrogen gas is set to the retard side compared to the case of combustion with only the hydrocarbon fuel according to the addition ratio of the hydrogen gas. And the most retarded ignition timing setting means to expand,
An ignition control device for a hydrogen-utilizing internal combustion engine, comprising:   The hydrogen-utilized internal combustion engine according to claim 1, wherein the most retarded ignition timing setting means is configured to expand the retarded limit ignition timing to the retarded side as the hydrogen gas addition ratio increases. Engine ignition control device. In an ignition control device for a hydrogen-using internal combustion engine that uses both hydrocarbon fuel and hydrogen gas as fuel,
Knocking control means for controlling knocking by retarding the ignition timing of the spark plug when knocking is detected;
A retarding speed setting means for increasing the retarding speed by expanding the ignition retarding control amount when the knocking controlling means retards the control during the addition of the hydrogen gas, compared to the case of combustion with only the hydrocarbon fuel;
An ignition control device for a hydrogen-utilizing internal combustion engine, comprising: 4. The ignition control device for a hydrogen-using internal combustion engine according to claim 3, wherein the retard angle setting means is configured to increase the ignition retard control amount as the hydrogen gas addition ratio increases.

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