JP4232710B2 - Control device for hydrogenated internal combustion engine - Google Patents

Description

  The present invention relates to a control device for a hydrogenated internal combustion engine that can be operated using gasoline and hydrogen as fuel, and more particularly to a technique for suppressing torque fluctuation by increasing or decreasing the hydrogenation rate.

Conventionally, as disclosed in, for example, Patent Document 1, a technique of using hydrogen as a fuel for an internal combustion engine together with gasoline is known. Since hydrogen is excellent in combustibility, the lean burn area of an internal combustion engine can be expanded by adding hydrogen to gasoline, and remarkable effects such as improvement of fuel consumption and reduction of NOx emissions can be obtained. . Further, as disclosed in Patent Document 1, when the misfire or reduction of explosive force occurs due to deterioration of the combustion state and the torque output from the internal combustion engine fluctuates, the hydrogen injection amount is increased. Thus, there is also an effect that torque fluctuation can be suppressed by improving the combustion state.
JP 2004-116398 A JP-A-6-200805

  However, in the above-described prior art, when torque fluctuation occurs, an increase in the hydrogen injection amount is added to the specified fuel injection amount, so that the fuel efficiency is deteriorated accordingly. Further, since the total heat generation amount per cycle is increased by increasing the hydrogen injection amount, more torque than necessary is output.

  The present invention has been made to solve the above-described problems, and controls a hydrogenated internal combustion engine that can suppress fluctuations in torque in a manner that does not cause deterioration in fuel consumption or unnecessary increase in torque. An object is to provide an apparatus.

In order to achieve the above object, a first invention provides a control device for a hydrogenated internal combustion engine operable with gasoline and hydrogen as fuels.
Fuel injection amount control means for performing injection amount control of gasoline and hydrogen at a ratio determined according to the operating state of the internal combustion engine;
Torque fluctuation detecting means for detecting fluctuations in torque of the internal combustion engine;
When the magnitude of torque fluctuation detected by the torque fluctuation detection means exceeds a predetermined value, torque fluctuation suppression means for suppressing the torque fluctuation by correcting the hydrogen addition ratio to the increase side;
It is characterized by having.

  In a second aspect based on the first aspect, the torque fluctuation suppressing means corrects the hydrogen addition ratio to the decreasing side when the magnitude of the torque fluctuation detected by the torque fluctuation detecting means is less than a predetermined value. It is characterized by that.

In a third aspect based on the first aspect or the second aspect, the torque variation detecting means detects a torque difference between the cylinders as a torque variation,
The torque fluctuation suppressing means performs correction of the hydrogen addition ratio for each cylinder in accordance with the torque difference.

According to a fourth invention, in the first or second invention, a target equivalence ratio setting means for determining a target value of the equivalence ratio from an operating state of the internal combustion engine;
An intake air amount control means for determining an intake air amount from the target equivalent ratio, the gasoline injection amount, and the hydrogen injection amount;
When the hydrogen addition ratio reaches a predetermined upper limit, the torque fluctuation suppressing means stops correcting the hydrogen addition ratio and suppresses torque fluctuation by correcting the target equivalent ratio to the increasing side. It is a feature.

In order to achieve the above object, a fifth invention provides a control device for a hydrogenated internal combustion engine operable with gasoline and hydrogen as fuels.
Target equivalence ratio setting means for determining a target value of the equivalence ratio from the operating state of the internal combustion engine;
Fuel injection amount control means for performing injection amount control of gasoline and hydrogen at a ratio determined according to the operating state of the internal combustion engine;
Intake air amount control means for determining the intake air amount from the target equivalent ratio, the gasoline injection amount, and the hydrogen injection amount;
Torque fluctuation detecting means for detecting fluctuations in torque of the internal combustion engine;
A torque fluctuation suppressing means for suppressing the torque fluctuation by correcting the target equivalence ratio to the increasing side when the magnitude of the torque fluctuation detected by the torque fluctuation detecting means exceeds a predetermined value;
The torque fluctuation suppressing means is characterized in that when the target equivalent ratio reaches a predetermined upper limit value, the hydrogen addition ratio is corrected to the increasing side and the target equivalent ratio is corrected to the decreasing side.

  According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the fuel injection amount control means determines a target value of a load factor of the internal combustion engine from an operating state of the internal combustion engine. Setting means and a hydrogen addition ratio setting means for determining a hydrogen addition ratio from the operating state of the internal combustion engine, calculating a load factor shared by gasoline and hydrogen from the target load factor and the hydrogen addition ratio, The fuel injection amount is determined from the load factor shared by the fuel, and the hydrogen injection amount is determined from the load factor shared by the hydrogen.

  In the first aspect of the invention, when the hydrogen addition rate is corrected to increase, the hydrogen injection amount is increased accordingly, and conversely, the gasoline injection rate is reduced by decreasing the gasoline addition rate as the hydrogen addition rate increases. As a result, the overall energy consumption is offset by the increased amount of hydrogen and the decreased amount of gasoline, and the deterioration of fuel consumption is prevented. In addition, since the gasoline injection amount is reduced by the increase in the hydrogen injection amount, it is possible to prevent the torque output from the internal combustion engine from being increased unnecessarily. According to the first aspect of the present invention, torque fluctuations can be suppressed without causing deterioration of fuel consumption or unnecessary increase in torque.

  Further, according to the second invention, since the hydrogen addition ratio is corrected to a decreasing side in a situation where torque fluctuation is small, it is possible to minimize the amount of hydrogen used.

  Further, according to the third aspect, torque fluctuation can be suppressed by eliminating the torque difference between the cylinders without causing deterioration in fuel consumption or unnecessary increase in torque.

  Further, according to the fourth invention, when the hydrogen addition ratio reaches the upper limit value, it is switched from suppression of torque fluctuation by correcting the hydrogen addition ratio to suppression of torque fluctuation by correcting the target equivalent ratio. Torque fluctuations can be suppressed while suppressing an increase in the amount of hydrogen used.

  In the fifth aspect of the invention, when the target equivalence ratio is corrected to the increasing side, the fuel concentration in the cylinder is increased and the combustion state is improved. Since the increase in the equivalence ratio is realized by the decrease in the intake air amount, the torque is prevented from increasing unnecessarily. In addition, the NOx emission increases as the equivalence ratio increases. However, when the target equivalence ratio reaches the upper limit, the target equivalence ratio is reduced after the hydrogen addition ratio is corrected to the increase side. Therefore, it is possible to prevent the NOx emission amount from becoming excessive. Further, when the equivalence ratio increases, the fuel efficiency deteriorates due to an increase in pumping loss, but the upper limit is provided for the target equivalence ratio, so that the deterioration of fuel economy is suppressed. Further, when the target equivalent ratio is corrected to the decreasing side, the hydrogen addition ratio is corrected to the increasing side, so that even if the equivalent ratio is decreased, deterioration of combustion is not caused. According to the fifth aspect of the present invention, torque fluctuations can be suppressed without causing deterioration of fuel consumption and unnecessary increase in torque and minimizing the use of hydrogen.

  According to the sixth aspect of the invention, since the hydrogen injection amount and the gasoline injection amount are determined based on the target load factor, an unnecessary increase in the torque output from the internal combustion engine can be prevented more reliably.

Embodiment 1 FIG.
The first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which a control device according to Embodiment 1 of the present invention is applied. The internal combustion engine 2 includes a cylinder block 6 in which a piston 8 is disposed, and a cylinder head 4 assembled to the cylinder block 6. A space from the upper surface of the piston 8 to the cylinder head 4 forms a combustion chamber 10, and an intake port 18 and an exhaust port 20 are formed in the cylinder head 4 so as to communicate with the combustion chamber 10. An intake valve 12 for controlling the communication state between the intake port 18 and the combustion chamber 10 is provided at a connection portion between the intake port 18 and the combustion chamber 10, and an exhaust gas is provided at a connection portion between the exhaust port 20 and the combustion chamber 10. An exhaust valve 14 for controlling the communication state between the port 20 and the combustion chamber 10 is provided. A spark plug 16 is attached to the cylinder head 4 so as to protrude from the top of the combustion chamber 10 into the combustion chamber 10.

  An intake passage 30 for introducing fresh air into the combustion chamber 10 is connected to the intake port 18 of the cylinder head 4. An air cleaner 32 is provided at the upstream end of the intake passage 30, and fresh air is taken into the intake passage 30 via the air cleaner 32. An air flow meter 76 for measuring the amount of intake air is attached downstream of the air cleaner 32 in the intake passage 30. A downstream portion of the intake passage 30 is branched for each cylinder (for each intake port 18), and a surge tank 34 is provided at the branched portion. An electronically controlled throttle valve 36 is disposed upstream of the surge tank 34 in the intake passage 30. The throttle valve 36 is a device for adjusting the amount of air taken into the combustion chamber 10 and is opened and closed by a motor. The throttle valve 36 is provided with a throttle sensor 78 for measuring the opening degree.

  In the vicinity of the intake port 18 of the intake passage 30, two injectors 50 and 60 for injecting fuel are provided for each cylinder. One injector 60 is a gasoline injector, and is an electromagnetic valve that is driven to open and close by energization control and injects gasoline. The gasoline injector 60 is connected to a gasoline tank 62 via a gasoline passage 64. A gasoline pump 66 is disposed in the gasoline passage 64, and the gasoline in the gasoline tank 62 is compressed by the gasoline pump 66 and supplied to the gasoline injector 60. The other injector 50 is a hydrogen injector, which is an electromagnetic valve that is driven to open and close by energization control and injects hydrogen. The hydrogen injector 50 is connected to the hydrogen tank 52 via the hydrogen passage 54. A hydrogen pump 56 is disposed in the hydrogen passage 54, and hydrogen in the hydrogen tank 52 is compressed by the hydrogen pump 56 and supplied to the hydrogen injector 50.

  Further, the internal combustion engine 2 is provided with an ECU (Electronic Control Unit) 70 as its control device. Various devices such as the gasoline injector 60, the hydrogen injector 50, and the throttle valve 36 are connected to the output side of the ECU 70. In addition to the air flow meter 76 and the throttle sensor 78 described above, various sensors such as an accelerator position sensor 72 and a crank angle sensor 74 are connected to the input side of the ECU 70. The accelerator position sensor 72 is a sensor that outputs a signal corresponding to the opening degree of the accelerator pedal, and the crank angle sensor 74 is a sensor that outputs a signal corresponding to the crank angle. The ECU 70 drives each device according to a predetermined control program based on the output of each sensor.

  As one of the controls of the internal combustion engine 2 performed by the ECU 70, there is fuel injection amount control for determining the gasoline injection amount from the gasoline injector 60 and the hydrogen injection amount from the hydrogen injector 50. FIG. 2 is a flowchart showing a fuel injection amount control routine executed by the ECU 70. This routine is periodically executed at every constant crank angle.

  In the first step 100 of the fuel injection amount control routine, the accelerator opening is read from the signal of the accelerator position sensor 72, and the rotation speed (the rotation speed of the crankshaft) is read from the signal of the crank angle sensor 74. In the next step 102, a target value (target load factor) of the load factor of the internal combustion engine 2 corresponding to the accelerator opening and the rotational speed read in step 100 is calculated from a map stored in advance. The load factor is a numerical value representing the load state of the internal combustion engine 2, and is 0% when there is no load and 100% when there is a full load. In step 104, a hydrogen addition ratio corresponding to the accelerator opening and the rotational speed read in step 100 is calculated from a map stored in advance. In the present embodiment, the hydrogen addition ratio is defined as the ratio of the calorific value of hydrogen to the total calorific value of the entire fuel including gasoline and hydrogen.

In the next step 106, the load factor shared by gasoline and hydrogen is calculated from the target load factor and the hydrogen addition ratio using the following equations (1) and (2).
Hydrogen load factor = target load factor x hydrogen addition ratio (1)
Gasoline load factor = target load factor-hydrogen load factor (2)
In the above formulas (1) and (2), the value calculated in step 102 is used as the target load factor. On the other hand, as the hydrogen addition ratio, a value obtained by correcting the basic value by a hydrogen addition ratio control routine described later, using the hydrogen addition ratio calculated in step 104 as a basic value, is used.

In the next step 108, the valve opening time of the hydrogen injector 50 is calculated from the hydrogen load factor using the following equation (3), and the gasoline injector 60 is calculated from the gasoline load factor using the following equation (4). The valve opening time is calculated.
Hydrogen injector valve opening time = Hydrogen load factor x Factor 1 (3)
Gasoline injector valve opening time = gasoline load factor x factor 2 (4)
In the above equations (3) and (4), each coefficient is determined from the fuel injection amount per unit valve opening time of each injector, the heat generation amount per unit amount of each fuel, and the like. These coefficients may be fixed values or variables. However, the coefficient 1 is preferably a variable determined by the temperature and pressure of hydrogen flowing through the hydrogen passage 54 in consideration of the volume change of hydrogen due to temperature and pressure.

  The hydrogen injector valve opening time calculated in step 108 is set in a driver in the ECU 70 that drives the hydrogen injector 50. The gasoline injector valve opening time is set in a driver in the ECU 70 that drives the gasoline injector 60. The process of step 108 is executed before the fuel injection timing, and each driver drives each injector 50, 60 based on each valve opening time set in step 108.

  The fuel injection amount control routine is one of basic control routines executed by the ECU 70. As another basic control routine executed by the ECU 70, there is an intake air amount control routine for determining an intake air amount. In the intake air amount control routine, first, the target value (target equivalent ratio) of the equivalence ratio is determined from the operating state of the internal combustion engine 2 (for example, the accelerator opening and the rotational speed). When the target equivalence ratio is determined, the intake air amount is determined from each fuel injection amount determined in the fuel injection amount control routine and the target equivalent ratio. The determined intake air amount is set in a driver in the ECU 70 that drives the throttle valve 36, and the driver drives the throttle valve 36 based on the set intake air amount. Note that in a hydrogenated internal combustion engine such as the internal combustion engine 2 of the present embodiment, by adding hydrogen to gasoline, stable combustion can be performed under a lower equivalent ratio than in the case of gasoline alone. At this time, as long as stable combustion can be ensured, lowering the equivalence ratio can lower the combustion temperature and reduce NOx emissions. Therefore, in the intake air amount control routine according to the present embodiment, a substantially equivalent minimum equivalent ratio that can ensure stable combustion is set as the target equivalent ratio.

  The ECU 70 also executes the following hydrogen addition ratio control routine as a routine related to the fuel injection amount control together with the above basic routines. FIG. 3 is a flowchart showing a hydrogen addition ratio control routine executed by the ECU 70. This routine is a routine that is executed for the purpose of suppressing fluctuations in torque that occurs as the combustion state deteriorates, and is periodically executed at fixed crank angles.

  In the first step 200 of the hydrogen addition ratio control routine, it is determined whether or not the current operation region of the internal combustion engine 2 is in the torque fluctuation feedback region. The torque fluctuation feedback refers to the processing after step 202, and the torque fluctuation feedback area refers to the operation area where the processing after step 202 needs to be executed, specifically, the low rotation / low load area where torque fluctuation is likely to occur. ing. When the operation region of the internal combustion engine 2 is out of the torque fluctuation feedback region, the processing after step 202 is not executed.

  When the operating range of the internal combustion engine 2 enters the torque fluctuation feedback area, it is determined whether or not the torque fluctuation has deteriorated, that is, whether or not the magnitude of the torque fluctuation has exceeded a predetermined reference value (step) 202). As an index value indicating the magnitude of torque fluctuation, the standard deviation or variance of torque in the past plural cycles may be used, or the trajectory length of torque in the past plural cycles may be used. Alternatively, the difference between the maximum value and the minimum value of torque in a plurality of past cycles may be used as the index value. The torque output from the internal combustion engine 2 can be directly detected by a torque sensor, or the angular acceleration of the crankshaft can be obtained based on a signal supplied from the crank angle sensor 74 and used as a torque corresponding value. Alternatively, when an in-cylinder pressure sensor for detecting the pressure in the combustion chamber 10 is provided, the indicated torque is calculated based on the signal supplied from the in-cylinder pressure sensor and the signal supplied from the crank angle sensor 74, and this is calculated. It can also be used as a torque corresponding value.

  As a result of the determination in step 202, when it is determined that the torque fluctuation has deteriorated, the hydrogen addition ratio is corrected to the increase side (step 204). Specifically, a predetermined ratio (for example, several percent) is added as a correction value to the current hydrogen addition ratio. As described above, the hydrogen addition ratio calculated in step 104 is a basic value, and a correction value is added to the basic value every time the process of step 204 is executed. Since the hydrogen injector valve opening time calculated in step 108 is set based on the corrected hydrogen addition rate, the hydrogen injection rate from the hydrogen injector 50 is increased as a result of correcting the hydrogen addition rate to the increase side. . Conversely, the gasoline injection amount from the gasoline injector 60 is reduced by a decrease in the gasoline addition rate accompanying an increase in the hydrogen addition rate.

  On the other hand, if it is determined that the torque fluctuation has not deteriorated as a result of the determination in step 202, the hydrogen addition ratio is corrected to the decreasing side (step 206). Specifically, a predetermined ratio (for example, several%) is subtracted as a correction value from the current hydrogen addition ratio. Every time the process of step 206 is executed, the correction value is subtracted from the basic value. As a result of correcting the hydrogen addition rate to the decrease side, the hydrogen injection amount from the hydrogen injector 50 is reduced, and conversely, the gasoline injection amount from the gasoline injector 60 is increased by an increase in the gasoline addition rate accompanying a decrease in the hydrogen addition rate. Is done.

  According to the hydrogen addition ratio control routine described above, when the torque fluctuation is deteriorated, the hydrogen addition ratio is corrected to the increase side, whereby the combustion is improved and the torque fluctuation is suppressed. At this time, the hydrogen injection amount is increased by increasing the hydrogen addition ratio, but the gasoline injection amount is decreased on the contrary, so the total energy consumption (heat consumption) is the increase in hydrogen and the decrease in gasoline. It will be offset by minutes, and fuel consumption will be prevented from deteriorating. In addition, the amount of hydrogen injection and gasoline injection amount are determined in the fuel injection amount control routine on the premise of the target load factor, although there is a slight increase in torque due to the increase in the hydrogen addition ratio with excellent combustibility. The torque is prevented from increasing unnecessarily.

  Further, according to the above hydrogen addition ratio control routine, the hydrogen addition ratio is corrected to a decrease side in a situation in which no deterioration in torque fluctuation is observed, so the hydrogen injection amount is reduced, and compared to gasoline, the hydrogen injection ratio is reduced. It becomes possible to minimize the usage of hydrogen with a small installed capacity. Also at this time, it is possible to prevent the torque output from the internal combustion engine 2 from being increased unnecessarily regardless of the increase or decrease of each fuel.

  In the above embodiment, the ECU 70 executes the fuel injection amount control routine of FIG. 2 so that the “fuel injection amount control means” according to the first invention and the “target load factor setting” according to the sixth invention. Means "," hydrogen addition ratio setting means "and" fuel injection amount control means "are realized. 3 is executed by the ECU 70, the “torque fluctuation detecting means” and the “torque fluctuation suppressing means” of the first invention, and the “torque fluctuation suppressing means” of the second invention. Is realized.

Embodiment 2.
Next, a second embodiment of the present invention will be described with reference to FIG.
The control device as the second embodiment of the present invention can be realized by causing the ECU 70 to execute the hydrogen addition ratio control routine of FIG. 4 instead of the hydrogen addition ratio control routine of FIG. 3 in the first embodiment. it can. The fuel injection amount control routine and the intake air amount control routine, which are basic routines, are also executed in this embodiment.

  In the internal combustion engine 2, explosions occur in order in each cylinder. Therefore, if there is a difference in torque between the cylinders, the torque output from the internal combustion engine 2 varies. In this embodiment, the torque difference between the cylinders is reduced by controlling the hydrogen addition ratio for each cylinder by the hydrogen addition ratio control routine of FIG. Note that this routine is also periodically executed at fixed crank angles.

  In the first step 300 of the hydrogen addition ratio control routine of FIG. 4, it is determined whether or not the current operation region of the internal combustion engine 2 is in the torque fluctuation feedback region. When the operating area of the internal combustion engine 2 enters the torque fluctuation feedback area, the torque fluctuation feedback processing after step 302 is sequentially executed for each cylinder. Here, a 4-cylinder engine is assumed, and the processing after step 302 is repeated four times in one execution of this routine.

  In step 302, it is determined whether or not the torque of the target cylinder (i cylinder: i = 1 to 4) is the smallest among all the cylinders. When executing this routine, the ECU 70 calculates the average torque of each cylinder in the past plural cycles, and in step 302, the average torque of each cylinder is compared. When the torque of the target cylinder is minimum, the hydrogen addition ratio in the target cylinder is corrected to the increasing side (step 304). Since the method for correcting the hydrogen addition ratio is the same as that in Embodiment 1, the description thereof is omitted here. Due to the increase correction of the hydrogen addition ratio, the hydrogen injection amount from the hydrogen injector 50 of the target cylinder is increased, and conversely, the gasoline injection amount from the gasoline injector 60 of the target cylinder decreases as the hydrogen addition ratio increases. Is lost.

  If the result of determination in step 302 is that the torque of the target cylinder is not minimum, it is next determined whether or not the torque of the target cylinder is maximum among all the cylinders (step 306). When it is determined that the torque of the target cylinder is maximum, the hydrogen addition ratio in the target cylinder is corrected to the decreasing side (step 308). As a result, the hydrogen injection amount from the hydrogen injector 50 of the target cylinder is decreased, and conversely, the gasoline injection amount from the gasoline injector 60 of the target cylinder is increased by an increase in the gasoline addition rate accompanying a decrease in the hydrogen addition rate. On the other hand, when the torque of the target cylinder is neither minimum nor maximum, the hydrogen addition ratio of the target cylinder is maintained at the current value.

  By executing a series of processes after step 302 for all four cylinders, the hydrogen injection amount is increased and the gasoline injection amount is decreased for the cylinder with the smallest torque. As a result, combustion is improved in the cylinder having the minimum torque, and misfire and a decrease in explosive force are suppressed, and the average torque is improved. Thereby, the torque difference between the cylinders is reduced, and the fluctuation of the torque output from the internal combustion engine 2 is suppressed. In addition, the hydrogen injection amount is increased, but the gasoline injection amount is decreased, so the overall fuel consumption is offset by the increase in hydrogen and the decrease in gasoline. Deterioration is prevented.

  Furthermore, according to the above hydrogen addition ratio control routine, the hydrogen injection amount is reduced for the cylinder with the maximum torque, that is, the cylinder with good combustion, so that the amount of hydrogen used can be minimized. become.

  In the above embodiment, the ECU 70 executes the hydrogen addition ratio control routine of FIG. 4 to realize the “torque fluctuation detecting means” and the “torque fluctuation suppressing means” of the third invention.

Embodiment 3.
Next, a third embodiment of the present invention will be described with reference to FIG.
The control device as the third embodiment of the present invention can be realized by causing the ECU 70 to execute the torque fluctuation control routine of FIG. 5 instead of the hydrogen addition ratio control routine of FIG. 3 in the first embodiment. it can. The fuel injection amount control routine and the intake air amount control routine, which are basic routines, are also executed in this embodiment.

  In the first embodiment, the hydrogen addition ratio is corrected to the increasing side until the torque fluctuation is suppressed, and the hydrogen injection amount is increased. However, since the capacity of the hydrogen tank 52 is small, if a large amount of hydrogen is used, it may be depleted at an early stage. Therefore, in the present embodiment, in the torque fluctuation control routine of FIG. 5, an upper limit value is provided for the hydrogen addition ratio, and when the hydrogen addition ratio reaches the upper limit value, a torque fluctuation suppression method is a method by correcting the hydrogen addition ratio. By switching from to other methods, the amount of hydrogen used is reduced. Note that this routine is also periodically executed at fixed crank angles.

  In the first step 400 of the torque fluctuation control routine of FIG. 5, it is determined whether or not the current hydrogen addition ratio is within a predetermined upper limit value. If the hydrogen addition rate has not yet exceeded the upper limit value, hydrogen addition rate feedback is executed (step 402). The hydrogen addition rate feedback means the increase / decrease control of the hydrogen addition rate by the hydrogen addition rate control routine described with reference to FIG. When the magnitude of torque fluctuation exceeds a predetermined reference value, the hydrogen addition ratio is corrected to the increasing side, and when the magnitude of torque fluctuation is equal to or less than the reference value, the hydrogen addition ratio is corrected to the decreasing side.

  In the hydrogen addition rate feedback, the hydrogen addition rate is increased or decreased according to the combustion state of the internal combustion engine 2. When the combustion state of the internal combustion engine 2 is not good, the hydrogen addition rate is gradually corrected to the increasing side, and eventually exceeds the upper limit value. If it is determined in step 400 that the current hydrogen addition ratio has exceeded the upper limit value, the hydrogen addition ratio feedback is switched to the equivalent ratio feedback described below (step 404).

  As described in the first embodiment, the ECU 70 determines the target equivalent ratio from the operating state of the internal combustion engine 2 by executing the intake air amount control routine, and determines the intake air amount from the target equivalent ratio and the injection amount of each fuel. is doing. In the equivalence ratio feedback, the target equivalence ratio is controlled to increase or decrease according to the magnitude of torque fluctuation. Specifically, first, it is determined whether or not the operating state of the internal combustion engine 2 is in the torque fluctuation feedback region (corresponding to step 200 in FIG. 3). When the operation region is in the torque fluctuation feedback region, it is determined whether or not the magnitude of torque fluctuation exceeds a predetermined reference value (corresponding to step 202 in FIG. 3). When the magnitude of the torque fluctuation exceeds a predetermined reference value, the target equivalence ratio is corrected to the increasing side (corresponding to step 204 in FIG. 3). The target equivalent ratio can be corrected by the same method as the correction of the hydrogen addition ratio described above. By correcting the target equivalence ratio to the increase side, the intake air amount is reduced, and as a result, the fuel concentration in the cylinder becomes high and the combustion state becomes good. That is, torque fluctuation is suppressed. Further, as described above, the increase in the equivalence ratio is realized by the decrease in the intake air amount, so that the fuel consumption is prevented from deteriorating and the torque is prevented from increasing unnecessarily. On the other hand, when the magnitude of torque fluctuation is less than or equal to the reference value, the target equivalent ratio is corrected to the decreasing side (corresponding to step 206 in FIG. 3). By correcting the target equivalence ratio to the decreasing side, the intake air amount is increased. As a result, the combustion temperature in the cylinder is lowered and the NOx generation amount is reduced.

  As described above, switching from torque fluctuation suppression by hydrogen addition rate feedback to torque fluctuation suppression by target equivalent ratio feedback makes it possible to suppress torque fluctuation while suppressing an increase in the amount of hydrogen used. . In the subsequent step 406, it is determined whether or not a certain time (or a certain crank angle) has elapsed since the execution of the processing in steps 408 and 410. These processes are executed at a period longer than the execution period of this routine at regular intervals. When a certain time has elapsed since the previous execution, first, the hydrogen addition ratio is corrected to the decreasing side (step 408). Next, the target equivalent ratio is corrected to the decreasing side (step 410). By executing the reduction correction of the hydrogen addition ratio and the reduction correction of the target equivalent ratio in a long cycle, the hydrogen addition ratio and the equivalent ratio are suppressed as a whole. As a result, the amount of hydrogen used is suppressed, and the NOx emission amount is also suppressed. In addition, when the hydrogen addition rate is reduced to the upper limit value or less by the processing in step 408, the target equivalent ratio feedback is switched to the hydrogen addition rate feedback again.

  In the above embodiment, the “torque fluctuation suppressing means” of the fourth aspect of the present invention is realized by the ECU 70 executing the torque fluctuation control routine of FIG. Further, by executing the intake air amount control routine described above, the “target equivalent ratio setting means” and the “intake air amount control means” of the fourth invention are realized.

Embodiment 4.
Next, a fourth embodiment of the present invention will be described with reference to FIG.
The control device as the fourth embodiment of the present invention can be realized by causing the ECU 70 to execute the torque fluctuation control routine of FIG. 6 instead of the hydrogen addition ratio control routine of FIG. 3 in the first embodiment. . The fuel injection amount control routine and the intake air amount control routine, which are basic routines, are also executed in this embodiment.

  As described in the third embodiment, the torque fluctuation suppression method includes a method by correcting the hydrogen addition ratio and a method by correcting the target equivalent ratio. In the present embodiment, torque fluctuations are suppressed by correcting the target equivalent ratio. However, if the equivalence ratio is increased, the combustion temperature rises and the NOx generation amount increases, so there is an upper limit to the set value of the target equivalence ratio. Therefore, in the present embodiment, an upper limit value is provided for the target equivalence ratio in the torque fluctuation control routine of FIG. 6, and torque fluctuation is suppressed by correcting the target equivalent ratio. Note that this routine is also periodically executed at fixed crank angles.

  In the first step 500 of the torque fluctuation control routine of FIG. 6, it is determined whether or not the current target equivalence ratio is within a predetermined upper limit value. If the target equivalence ratio has not yet exceeded the upper limit value, equivalence ratio feedback is executed (step 502). In the equivalence ratio feedback, as described in the third embodiment, first, it is determined whether or not the operating state of the internal combustion engine 2 is in the torque fluctuation feedback region. It is determined whether or not the magnitude of the fluctuation exceeds a predetermined reference value. When the magnitude of torque fluctuation exceeds a predetermined reference value, the target equivalent ratio is corrected to the increasing side, and when the magnitude of torque fluctuation is equal to or less than the reference value, the target equivalent ratio is corrected to the decreasing side. The The operation and effect of the equivalence ratio feedback is as described in the third embodiment.

  In the equivalence ratio feedback, the target equivalence ratio is increased or decreased according to the combustion state of the internal combustion engine 2. When the combustion state of the internal combustion engine 2 is not good, the target equivalence ratio is gradually corrected to the increasing side, and eventually exceeds the upper limit value. If it is determined in step 500 that the current target equivalence ratio exceeds the upper limit, the equivalence ratio feedback is temporarily stopped and the processing is switched to steps 504 and 506.

  In step 504, the hydrogen addition ratio is corrected to the increasing side. The hydrogen injection amount is increased and the gasoline injection amount is decreased by the increase correction of the hydrogen addition ratio. By increasing the amount of hydrogen having excellent combustibility, the combustion state of the internal combustion engine 2 is improved, and operation in a lean region becomes possible. Therefore, in the next step 506, the target equivalent ratio is corrected to the decreasing side. By correcting the target equivalence ratio to the decreasing side after correcting the hydrogen addition ratio to the increasing side, it is possible to prevent the NOx emission amount from becoming excessive without causing deterioration of combustion. When the target equivalence ratio is lowered to the upper limit value or less by the processing in step 504 and step 506, equivalence ratio feedback is executed again.

  In the subsequent step 508, it is determined whether or not a certain time (or a certain crank angle) has elapsed since the execution of the processing in step 510 described later. The process of step 510 is a process executed at a period longer than the execution period of this routine at regular time intervals. When a certain time has elapsed since the previous execution, the process of step 510 is executed and the hydrogen addition rate is corrected to the decreasing side. The hydrogen addition ratio corrected to the increase side by the process of step 504 is corrected again to the decrease side by the process of step 510, so the hydrogen addition ratio does not become excessive and the amount of hydrogen used is necessary. Minimized.

  In the above embodiment, the “torque fluctuation detecting means” and the “torque fluctuation suppressing means” according to the fifth aspect of the present invention are implemented by the ECU 70 executing the torque fluctuation control routine of FIG. Further, by executing the fuel injection amount control routine described above, the “fuel injection amount control means” of the fifth invention, the “target load factor setting means”, and the “hydrogen addition ratio setting means” of the sixth invention. And the “fuel injection amount control means” and the intake air amount control routine are executed, thereby realizing the “target equivalent ratio setting means” and the “intake air amount control means” of the fifth aspect of the invention.

Others.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  The hydrogen addition ratio control (FIG. 4) according to the second embodiment can be executed in combination with the hydrogen addition ratio control (FIG. 3) according to the first embodiment. Specifically, after the hydrogenation rate is uniformly controlled for all cylinders by the hydrogenation rate control according to the first embodiment, the hydrogenation rate is controlled for each cylinder by the hydrogenation rate control according to the second embodiment. . According to this, torque fluctuation can be more reliably suppressed.

  In the above embodiment, the intake air amount is controlled by the throttle valve 36. However, in the case of the internal combustion engine 2 having the intake control valve at each intake port 18, the intake air amount is controlled for each cylinder by the intake control valve. You may control. When the intake air amount can be controlled for each cylinder, the torque fluctuation control according to the third or fourth embodiment can be executed for each cylinder by correcting the target equivalence ratio for each cylinder.

  In the configuration of FIG. 1, the hydrogen injector 50 is arranged in the intake passage 30, but the arrangement is not limited to this. That is, the hydrogen injector 50 may be incorporated in the cylinder head 4 so that hydrogen can be injected directly into the combustion chamber 10. The same applies to the gasoline injector 60, and the gasoline injector 60 may be incorporated in the cylinder head 4 so that gasoline can be injected directly into the combustion chamber 10.

  In the intake air amount control according to the above embodiment, the minimum equivalent ratio that enables stable combustion is set as the target equivalent ratio, but the application of the present invention is limited to the operation in such a lean burn region. It can be applied to stoichiometric operation.

1 is a diagram showing a schematic configuration of an internal combustion engine to which a control device as Embodiment 1 of the present invention is applied. It is a flowchart shown about the fuel injection amount control routine performed in Embodiment 1 of this invention. It is a flowchart shown about the hydrogen addition ratio control routine performed in Embodiment 1 of this invention. It is a flowchart shown about the hydrogenation ratio control routine performed in Embodiment 2 of this invention. It is a flowchart shown about the torque fluctuation control routine performed in Embodiment 3 of this invention. It is a flowchart shown about the torque fluctuation control routine performed in Embodiment 4 of this invention.

Explanation of symbols

2 Internal combustion engine 10 Combustion chamber 12 Intake valve 14 Exhaust valve 16 Spark plug 18 Intake port 20 Exhaust port 30 Intake passage 34 Surge tank 36 Throttle valve 40 Exhaust passage 50 Hydrogen injector 52 Hydrogen tank 60 Gasoline injector 62 Gasoline tank 70 ECU (Electronic Control) Unit)
72 Acceleration position sensor 74 Crank angle sensor 76 Air flow meter 78 Throttle sensor

Claims (3)

In a control device for a hydrogenated internal combustion engine that can be operated using gasoline and hydrogen as fuel,
Target equivalence ratio setting means for determining a target value of the equivalence ratio from the operating state of the internal combustion engine;
A hydrogen addition ratio setting means for determining a hydrogen addition ratio from the operating state of the internal combustion engine;
Fuel injection amount control means for determining an injection amount of gasoline and hydrogen according to the hydrogen addition ratio based on a target load state of the internal combustion engine ;
Intake air amount control means for determining the intake air amount from the target equivalent ratio, the gasoline injection amount, and the hydrogen injection amount;
Torque fluctuation detecting means for detecting fluctuations in torque of the internal combustion engine;
A torque fluctuation suppressing means for suppressing the torque fluctuation by correcting the hydrogen addition ratio to the increasing side when the magnitude of the torque fluctuation detected by the torque fluctuation detecting means exceeds a predetermined value;
When the hydrogen addition ratio reaches a predetermined upper limit, the torque fluctuation suppressing means stops correcting the hydrogen addition ratio and suppresses torque fluctuation by correcting the target equivalent ratio to the increasing side. A control device for a hydrogenated internal combustion engine. In a control device for a hydrogenated internal combustion engine that can be operated using gasoline and hydrogen as fuel,
Target equivalence ratio setting means for determining a target value of the equivalence ratio from the operating state of the internal combustion engine;
A hydrogen addition ratio setting means for determining a hydrogen addition ratio from the operating state of the internal combustion engine;
Fuel injection amount control means for determining an injection amount of gasoline and hydrogen according to the hydrogen addition ratio based on a target load state of the internal combustion engine ;
Intake air amount control means for determining the intake air amount from the target equivalent ratio, the gasoline injection amount, and the hydrogen injection amount;
Torque fluctuation detecting means for detecting fluctuations in torque of the internal combustion engine;
A torque fluctuation suppressing means for suppressing the torque fluctuation by correcting the target equivalence ratio to the increasing side when the magnitude of the torque fluctuation detected by the torque fluctuation detecting means exceeds a predetermined value;
The torque fluctuation suppressing means corrects the hydrogen addition ratio to the increase side and corrects the target equivalent ratio to the decrease side when the target equivalent ratio reaches a predetermined upper limit value. Control device. The fuel injection amount control means includes target load factor setting means for determining a target load factor that is a target value of the load state of the internal combustion engine from the operating state of the internal combustion engine, and from the target load factor and the hydrogen addition rate, gasoline and The load factor shared by each hydrogen is calculated, the gasoline injection amount is determined from the load factor shared by gasoline, and the hydrogen injection amount is determined from the load factor shared by hydrogen. The control apparatus for a hydrogenated internal combustion engine according to claim 1 or 2.

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