JP2008121690A - Controller of hydrogen-added internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a combustion state even when factors such as property of gasoline change in a hydrogen-added internal combustion engine using hydrogen gas together with gasoline as fuel for combustion. <P>SOLUTION: This controller for the hydrogen-added internal combustion engine using hydrogen gas together with hydrocarbon fuel as the fuel for combustion is provided with a means for obtaining a decreasing quantity of an engine rotation frequency immediately after start, a feedback correction value of an ignition timing lead angle immediately after star, or a feedback correction value of injection quantity increase of a hydrocarbon fuel immediately after start and an addition rate increase means for increasing an addition rate of hydrogen gas for the hydrocarbon fuel in the case that the obtained value is equal to or larger than a predetermined value. Thus, as the addition rate of hydrogen gas to hydrocarbon fuel is increased when the combustion state in a cylinder is deteriorated, it is possible to prevent deterioration of the combustion state and improve emission and drivability. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a hydrogenated internal combustion engine.

In an internal combustion engine that uses gasoline as fuel, it is known that further reduction of nitrogen oxides (NO _x ) in exhaust gas is possible by supplying hydrogen gas in addition to gasoline. For example, Japanese Patent Application Laid-Open No. 2004-116398 describes a technique for operating an internal combustion engine by determining a hydrogen addition ratio so as to reduce NO _X emissions and injecting gasoline and hydrogen according to the determined ratio. Yes.

JP 2004-116398 A JP-A-6-200805

  However, since the conventional technology does not consider the properties of gasoline, combustion in a cylinder may deteriorate if the properties of gasoline fluctuate. In particular, if the properties of gasoline are heavy during cold start, the degree of gasoline atomization in the cylinder decreases, so cold hesitation is likely to occur, acceleration is slow, and drivability such as engine stoppage deteriorates. Problem arises. Further, when the combustion state is deteriorated due to the properties of gasoline, there is a problem that the emission is deteriorated.

  The present invention has been made to solve the above-described problems. In a hydrogenated internal combustion engine that uses hydrogen gas together with gasoline as a fuel for combustion, even when factors such as the properties of gasoline change. The purpose is to improve the combustion state.

In order to achieve the above object, a first invention is a control device for a hydrogenated internal combustion engine that uses hydrogen gas together with hydrocarbon fuel as combustion fuel,
Means for obtaining a reduction amount of the engine speed immediately after the start, a feedback correction value of the ignition timing advance immediately after the start, or a feedback correction value of an increase in the injection amount of hydrocarbon fuel immediately after the start;
When the amount of decrease in the engine speed, the feedback correction value for the ignition timing advance, or the feedback correction value for the increase in the injection amount of the hydrocarbon fuel is equal to or greater than a predetermined value, the proportion of hydrogen gas added to the hydrocarbon fuel is increased. Means for increasing the addition ratio,
It is provided with.

  According to the first invention, when the amount of decrease in the engine speed immediately after starting, the feedback correction value of the ignition timing advance, or the feedback correction value of the increase in the injection amount of hydrocarbon fuel is greater than or equal to a predetermined value, Therefore, it is possible to suppress the deterioration of the combustion state by increasing the proportion of hydrogen gas added to the hydrocarbon fuel. Therefore, it is possible to improve the emission and drivability.

  An embodiment of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining the configuration of a system including a hydrogenated internal combustion engine 10 according to Embodiment 1 of the present invention. A piston 12 that reciprocates inside the cylinder of the internal combustion engine 10 is provided. Further, the internal combustion engine 10 includes a cylinder head 14. A combustion chamber 16 is formed between the piston 12 and the cylinder head 14. An intake port 18 and an exhaust port 20 communicate with the combustion chamber 16. An intake valve 22 and an exhaust valve 24 are disposed in the intake port 18 and the exhaust port 20, respectively.

  The intake port 18 is provided with a gasoline injection valve 26 that injects gasoline (hydrocarbon fuel) into the port. The intake port 18 is provided with a hydrogen fuel port injection valve 28 for injecting hydrogen into the port.

  A gasoline tank 34 communicates with the gasoline injection valve 26 via a gasoline supply pipe 32. The gasoline supply pipe 32 includes a pump 36 between the gasoline injection valve 26 and the gasoline tank 34. The pump 36 can supply gasoline to the gasoline injection valve 26 at a predetermined pressure. For this reason, the gasoline injection valve 26 is able to inject an amount of gasoline into the intake port 18 according to the opening time by opening the valve in response to a drive signal supplied from the outside.

  The system of this embodiment includes a hydrogen tank 38 for storing hydrogen in a gaseous state at a high pressure. A hydrogen supply pipe 40 communicates with the hydrogen tank 38. The hydrogen supply pipe 40 communicates with the hydrogen fuel port injection valve 28. In the system of the present embodiment, hydrogen gas charged into the hydrogen tank 38 from the outside is used as the hydrogen fuel supplied to the hydrogen fuel port injection valve 28, but supplied to these injection valves. The hydrogen fuel is not limited to this, and a hydrogen-rich gas containing a high concentration of hydrogen generated on the vehicle or supplied from the outside may be used.

  A regulator 44 is disposed in the hydrogen supply pipe 40. According to such a configuration, hydrogen in the hydrogen tank 38 is supplied to the hydrogen fuel port injection valve 28 at a predetermined pressure reduced by the regulator 44. For this reason, the hydrogen fuel port injection valve 28 opens the valve in response to a drive signal supplied from the outside, and can inject an amount of hydrogen into the intake port 18 in accordance with the valve opening time.

  In the hydrogen supply pipe 40, a fuel pressure sensor 48 is disposed between the regulator 44 and the hydrogen fuel port injection valve 28. The fuel pressure sensor 48 is a sensor that emits an output corresponding to the pressure of hydrogen supplied to the hydrogen fuel port injection valve 28. In the system of this embodiment, the regulator 44 is controlled based on the output generated by the fuel pressure sensor 48. For this reason, even when the pressure of hydrogen supplied from the hydrogen tank 38 fluctuates, hydrogen can be supplied to the hydrogen fuel port injection valve 28 at a stable pressure.

  The system of this embodiment includes an ECU 50. In addition to the fuel pressure sensor 48 described above, the ECU 50 includes a KCS sensor that detects the occurrence of knocking in order to grasp the operating state of the internal combustion engine 10, a throttle opening, an engine speed, an exhaust temperature, a coolant temperature, a lubricating oil Various sensors (not shown) for detecting temperature, catalyst bed temperature and the like are connected. The ECU 50 is connected to actuators such as the gasoline injection valve 26, the hydrogen fuel port injection valve 28, and the pump 36 described above. According to such a configuration, the ECU 50 can arbitrarily select an injection valve that performs fuel injection according to the operating state of the internal combustion engine 10.

  Therefore, by injecting hydrogen from the hydrogen fuel port injection valve 28 according to the operating state of the internal combustion engine 10, the combustion state in the cylinder (inside the combustion chamber 16) can be improved, and the amount of NOx emission is reduced. Can be made.

  By the way, there are variations in the properties of gasoline, and the properties of gasoline affect the combustion state in the cylinder. In particular, when the properties of the gasoline are heavy, the gasoline injected from the gasoline injection valve 26 tends to adhere to the wall surface of the intake port 18 or the cylinder inner wall surface, and the degree of gasoline atomization is reduced and the combustion state is poor. May become stable.

  For this reason, in the system of this embodiment, the property of gasoline is discriminated, and when the property of gasoline is heavy, the amount of hydrogen injected from the hydrogen fuel port injection valve 28 is increased. Thereby, even if the property of gasoline is heavy, it becomes possible to make a combustion state favorable.

  In addition, since the deterioration of emissions and drivability due to the properties of gasoline mainly occurs at the first idle immediately after the start, it is preferable to increase the hydrogen gas at the first idle, but at the idling after the first idle, Or the deterioration of the combustion state resulting from heavy fuel can also be suppressed by increasing the amount of hydrogen gas during normal operation.

  The property determination of gasoline is performed based on, for example, the engine speed immediately after starting. When the properties of gasoline are heavy, the engine speed immediately after start-up is lower than the normal properties. Accordingly, a threshold value for determining the heavyness is determined in advance, and when the engine speed immediately after the start of operation is lower than the threshold value, it is determined that the gasoline is heavy.

  Further, when the engine speed immediately after start-up decreases, feedback correction is performed by control for advancing the ignition timing or control for increasing the injection amount of gasoline. Therefore, the property of gasoline may be determined based on the correction amount of the ignition timing or the correction amount of the gasoline injection amount.

  When it is determined that the gasoline is heavy, the amount of hydrogen to be added is determined based on the degree of heavyness. At this time, since the combustion state in the cylinder fluctuates according to the cooling water temperature, it is preferable to determine the addition amount of hydrogen in consideration of the cooling water temperature.

  Next, a processing procedure in the system of this embodiment will be described based on the flowchart of FIG. First, in step S1, the property of gasoline is determined based on the engine speed immediately after starting. At this time, as described above, the property of gasoline may be determined based on the ignition timing or the feedback correction amount of the gasoline injection amount.

  If it is determined in step S1 that the gasoline is heavy, the process proceeds to step S2. In step S2, the target hydrogen addition ratio is calculated based on parameters representing the operating condition such as the degree of heavy gasoline properties and the coolant temperature. Here, a map corresponding to heavy gasoline is used, and the target hydrogen addition ratio is calculated by applying parameters such as the degree of heavyness and cooling water temperature to the map. At this time, the target hydrogen addition ratio is set higher as the property of gasoline is heavier. Further, since the combustion state decreases as the cooling water temperature decreases, the target hydrogen addition ratio is set high.

  On the other hand, when the property of gasoline is not determined to be heavy in step S1, and the normal property is determined, the process proceeds to step S3. In this case, a target hydrogen addition ratio is calculated by using a map corresponding to gasoline having normal properties and applying a parameter representing an operation state such as a cooling water temperature to the map. The target hydrogen addition ratio calculated in steps S2 and S3 represents the ratio of the energy of hydrogen gas combustion to the engine load factor.

  After steps S2 and S3, the process proceeds to step S4. In step S4, the hydrogen addition amount actually injected from the hydrogen fuel port injection valve 28 is determined based on the target hydrogen addition ratio determined in steps S2 and S3. Specifically, the hydrogen addition amount is determined by multiplying the load factor obtained from the accelerator opening and the engine speed by the target hydrogen addition ratio and further multiplying by a predetermined coefficient. Then, the internal combustion engine 10 is operated with the determined hydrogen addition amount.

  As described above, according to the first embodiment, when the property of gasoline is determined to be heavy, the amount of hydrogen gas added can be increased. Therefore, the deterioration of the combustion state caused by the heavy fuel can be surely suppressed, and the emission and drivability can be improved.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. The system configuration in the second embodiment is the same as that shown in FIG. The second embodiment suppresses the deterioration of emission and drivability especially at the first idle immediately after starting.

  When the properties of gasoline are heavy, gasoline adheres to the wall surface of the intake port 18 and the wall surface in the cylinder, so that cold hesitation is likely to occur especially during cold start, and emission and drivability may be deteriorated. . For this reason, in the second embodiment, the initial value of the hydrogen addition ratio is set high during the first idling to increase the amount of hydrogen addition. Then, after the first idle time has elapsed, control is performed to reduce the amount of hydrogen added to the lower limit value according to the properties of gasoline.

  In this way, by setting the initial value of the hydrogen addition ratio to a uniformly high value, it is possible to prevent the combustion at the time of the first idle from being affected by the properties of gasoline. Thereby, the idling speed can be set to a low value, the fuel efficiency at the time of the first idling can be improved, and the emission and drivability can be improved. Further, since the amount of hydrogen addition is reduced to a necessary level after the first idle, the amount of hydrogen used can be minimized, and the system efficiency can be increased.

  Next, processing procedures in the system of the second embodiment will be described based on the flowcharts of FIGS. 3 and 4. Here, the flowchart of FIG. 3 shows a process of setting the hydrogen addition rate high during the first idle, and reducing the hydrogen addition rate to the lower limit after the first idle. Further, the flowchart of FIG. 4 shows a process of calculating a lower limit value for decreasing the hydrogen addition ratio after the first idle based on the degree of gasoline heavyness.

  First, the process of FIG. 3 will be described. First, in step S11, it is determined whether or not 2 seconds have passed since the start, and it is determined whether or not the current operation is an operation during fast idle. If it is within 2 seconds immediately after the start, it is the operation at the time of the first idle, and the process proceeds to step S12.

  In step S12, an initial value of the hydrogen addition ratio is set. The initial value of the hydrogen addition ratio is a value calculated on the basis of the coolant temperature, and is set to a sufficiently large value so that combustion is good regardless of the properties of gasoline. As a result, the combustion state at the time of first idling can always be made good, and idling can be performed stably. Therefore, it is possible to reliably prevent the emission and drivability from deteriorating during the first idling due to the properties of the fuel.

  On the other hand, if it is longer than 2 seconds after the start in step S11, the process proceeds to step S13. In this case, idling at the time of first idling has already been maintained in a stable state by the process of step S12. Therefore, in order to supply only a necessary amount of hydrogen gas, processing for reducing the hydrogen addition ratio is performed in the processing after step S13.

  That is, in step S13, it is determined whether or not the current hydrogen addition ratio is greater than the lower limit value. Here, the lower limit value of the hydrogen addition ratio is determined from a heavy index representing the degree of heavyness of the properties of gasoline as will be described later with reference to the flowchart of FIG.

  When the current hydrogen addition ratio is larger than the lower limit value in step S13, the process proceeds to step S14, and a process for reducing the hydrogen addition ratio by a predetermined value is performed. On the other hand, if the current hydrogen addition ratio is equal to or lower than the lower limit value in step S13, the process proceeds to step S15.

  After steps S12 and S14, the process proceeds to step S15. In step S15, the hydrogen addition amount actually injected from the hydrogen fuel port injection valve 28 is determined based on the target hydrogen addition ratio determined in steps S12 and S14. Specifically, the hydrogen addition amount is determined by multiplying the load factor obtained from the accelerator opening and the engine speed by the target hydrogen addition ratio and further multiplying by a predetermined coefficient. Then, the internal combustion engine 10 is operated with the determined hydrogen addition amount.

  Next, processing for calculating the lower limit value of the hydrogen addition ratio used in step S13 of FIG. 3 will be described based on FIG. First, in step S21, it is determined whether or not 2 seconds have passed since the start, and it is determined whether or not the current operation is an operation at the time of first idle. If it is within 2 seconds after the start, it is the operation at the time of the first idle, so that the process proceeds to step S12. On the other hand, if it has exceeded 2 seconds since the start, the process is terminated (RETURN).

  When the process proceeds to step S22, hydrogen gas is added based on the initial value of the hydrogen addition ratio by the processes of steps S12 to S15 in FIG. In step S22, the idling speed is controlled by increasing or decreasing the gasoline injection amount in a state where hydrogen is added based on the initial value of the hydrogen addition ratio.

  In the next step S23, when the idling speed is stabilized at a desired value, an increase amount Δf of the gasoline injection amount at this time is obtained. When the property of gasoline is heavy, since the degree of atomization of gasoline is low, the value of Δf at the time of first idling becomes larger than usual.

  In the next step S24, based on the increase amount Δf obtained in step S23, a heavy index is calculated from a map defining the relationship between the increase amount Δf and the degree of heavy gasoline property (heavy index). Here, since the degree of weight is higher as the increase amount Δf is larger, the value of the weight index becomes larger.

  In the next step S25, a lower limit value of the hydrogen addition ratio is calculated based on the heavy index and the cooling water temperature. Here, the higher the heavy index, the higher the degree of heavy gasoline properties, and it is necessary to stabilize the combustion by increasing the amount of hydrogen added, so the lower limit is set to a large value. Further, the lower the cooling water temperature is, the more hydrogen must be added to improve the combustion, so the lower limit value is set to a large value. After step S25, the process ends.

  According to the process of FIG. 4, the lower limit value of the hydrogen addition ratio can be obtained based on the increase amount Δf of the gasoline injection amount at the time of first idling. And since the property of gasoline is taken into consideration for the lower limit value of the obtained hydrogen addition ratio, it is attributed to the property of gasoline by adding more hydrogen than the lower limit value after the first idle by the processing of FIG. This can prevent the combustion from becoming unstable. Therefore, it is possible to improve the emission and drivability.

  As described above, according to the second embodiment, the initial value of the hydrogen addition ratio is set high at the time of first idling to increase the amount of hydrogen addition, so that the combustion state at the time of first idling is deteriorated due to the properties of gasoline. Can be prevented. As a result, stable idling can be performed, and emission and drivability can be improved. Further, since the amount of hydrogen addition is reduced to a necessary level after the first idle, the amount of hydrogen used can be minimized, and the system efficiency can be increased.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. In the third embodiment, when the combustion state immediately after starting becomes unstable due to the properties of gasoline, or when the combustion immediately after starting becomes unstable due to other factors, the amount of hydrogen added is reduced. This increases the combustion state in the cylinder. The system configuration in the third embodiment is the same as that shown in FIG.

  As a case where combustion at start-up becomes unstable due to a factor other than the property of gasoline, for example, a case where droplet-like gasoline adheres to a spark plug and the ignitability of the fuel decreases. In addition, when air bubbles are generated in the gasoline before being injected by the gasoline injection valve 26 at a high temperature or the like, and the amount of gasoline injected from the gasoline injection valve 26 is reduced below the indicated value, the combustion is also unstable. .

  In the third embodiment, when the in-cylinder combustion becomes unstable due to gasoline properties or other factors including the above factors, the amount of hydrogen gas added is increased to improve the combustion state. It is.

  Hereinafter, a processing procedure in the system of the present embodiment will be described based on the flowchart of FIG. First, in step S31, the in-cylinder combustion state is determined based on the engine speed immediately after starting. If the in-cylinder combustion state has deteriorated due to the gasoline characteristics or the above-mentioned factors, the engine speed immediately after starting decreases, so in step S31, a threshold value for determining the combustion state is set. It is determined in advance, and it is determined that the in-cylinder combustion state has deteriorated when the engine speed immediately after starting falls below a threshold value.

  Further, when the rotation speed immediately after the start is reduced due to the deterioration of the combustion state in the cylinder, feedback correction is performed by control for advancing the ignition timing or control for increasing the injection amount of gasoline. Therefore, in step S31, the combustion state in the cylinder may be determined based on the correction amount of the ignition timing or the correction amount of the gasoline injection amount.

  If it is determined in step S31 that the combustion state has deteriorated, the process proceeds to step S32. In step S32, the target hydrogen addition ratio is calculated based on parameters representing the operating state such as the degree of deterioration of the combustion state and the coolant temperature. Specifically, using the map used when the combustion state is worsening, the engine speed reduction amount, ignition timing correction amount, or gasoline injection amount correction amount, and the operating state such as cooling water temperature The target hydrogen addition ratio is calculated by applying the parameter to the map. At this time, the target hydrogen addition ratio is set higher as the reduction amount of the engine speed or the correction amount is larger. Further, since the combustion state decreases as the cooling water temperature decreases, the target hydrogen addition ratio is set high.

  On the other hand, if it is determined in step S31 that the combustion state is normal, the process proceeds to step S33. In this case, using a normal map, a target hydrogen addition ratio is calculated by applying a parameter representing an operation state such as cooling water temperature to the map.

  After steps S32 and S33, the process proceeds to step S34. In step S34, the hydrogen addition amount actually injected from the hydrogen fuel port injection valve 28 is determined based on the target hydrogen addition ratio determined in steps S32 and S33. Specifically, the hydrogen addition amount is determined by multiplying the load factor obtained from the accelerator opening and the engine speed by the target hydrogen addition ratio and further multiplying by a predetermined coefficient. Then, the internal combustion engine 10 is operated with the determined hydrogen addition amount.

  As described above, according to the third embodiment, when the reduction amount of the engine speed immediately after the start, the correction amount of the ignition timing, or the correction amount of the gasoline injection amount exceeds a predetermined value, the addition of hydrogen gas The amount can be increased. Therefore, it is possible to reliably suppress the deterioration of the combustion state at the start, and to improve the emission and drivability.

It is a mimetic diagram showing a system of a hydrogenation internal-combustion engine concerning each embodiment of the present invention. 3 is a flowchart illustrating a processing procedure according to the first embodiment. 10 is a flowchart illustrating a processing procedure according to the second embodiment. 10 is a flowchart illustrating a processing procedure according to the second embodiment. 10 is a flowchart illustrating a processing procedure according to the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydrogen addition internal combustion engine 26 Gasoline injection valve 28 Hydrogen fuel port injection valve 50 ECU

Claims (1)

A control device for a hydrogenated internal combustion engine that uses hydrogen gas together with a hydrocarbon fuel as a combustion fuel,
Means for obtaining a reduction amount of the engine speed immediately after the start, a feedback correction value of the ignition timing advance immediately after the start, or a feedback correction value of an increase in the injection amount of hydrocarbon fuel immediately after the start;
When the amount of decrease in the engine speed, the feedback correction value for the ignition timing advance, or the feedback correction value for the increase in the injection amount of the hydrocarbon fuel is equal to or greater than a predetermined value, the proportion of hydrogen gas added to the hydrocarbon fuel is increased. Means for increasing the addition ratio,
A control device for a hydrogenated internal combustion engine, comprising:

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