JP2006105088A - Hydrogenation internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimally inject hydrogen into a suction pipe or a cylinder in a hydrogenation internal combustion engine using hydrogen gas together with gasoline as combustion fuel. <P>SOLUTION: The hydrogenation internal combustion engine 10 using hydrogen gas together with hydrocarbon fuel as combustion fuel is provided with a hydrogen fuel port injection valve 28 injecting hydrogen gas into the suction port 18 or the cylinder, and a regulator 44 regulating pressure of hydrogen gas acting on the hydrogen fuel port injection valve 28 lower as hydrogen quantity injected from the hydrogen fuel port injection valve is lower. Since pressure of hydrogen gas is regulated according to hydrogen quantity injected from the hydrogen fuel port injection valve 28, an unstable zone where hydrogen quantity injected from the hydrogen fuel port injection valve 28 is unstable is not used and hydrogen injection quantity is accurately controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to 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 discloses an internal combustion engine that includes a hydrogen injector and a gasoline injector and injects hydrogen and gasoline into a cylinder at a predetermined ratio.

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

  An injector such as a hydrogen injector or a gasoline injector is configured to inject a desired amount of fuel by opening a valve for a predetermined time. However, if the valve opening time is shortened, it becomes difficult for the injector itself to stably inject fuel. This phenomenon occurs after the valve is opened and until the fuel is actually injected from the injector due to the time from when the valve starts to open until the maximum lift is reached, or due to properties such as the inertia, viscosity, and density of the fuel. This is due to the fact that there is a time delay in the process. In this case, since the relationship between the valve opening time and the injection amount becomes nonlinear, it becomes difficult to control the fuel injection amount based on the valve opening time, and the controllability of the fuel injection amount is lowered.

  Especially when the valve opening time of the injector is very short, the time until the maximum lift is reached after the valve starts to open accounts for a large percentage of the total valve opening time, and the time delay of fuel injection is the total injection amount. Therefore, the relationship between the valve opening time and the injection amount is likely to be nonlinear.

  Further, in an internal combustion engine that supplies hydrogen gas in addition to gasoline, fuel is supplied from both the hydrogen injector and the gasoline injector, so that the amount of fuel injected from one injector is smaller than that of a normal one-fuel engine. . Accordingly, the valve opening time of the injector becomes very short in a low load range or the like. Also, since hydrogen has lower combustion energy per unit volume than liquid fuel such as gasoline, it is necessary to set the hydrogen pressure applied to the injector higher in order to inject a desired amount of fuel. If the value is increased, the injection amount with respect to the drive time of the injector increases, so that there is a problem that the valve opening time of the injector is shortened also in a low load region or the like.

  In addition, in an internal combustion engine that supplies hydrogen gas in addition to gasoline, when hydrogen is directly injected into the cylinder from the hydrogen injector during the compression stroke, the pressure in the cylinder becomes very high during the compression stroke. When such hydrogen pressure is low, it is assumed that hydrogen cannot be sufficiently injected into the cylinder.

  The present invention has been made to solve the above-mentioned problems, and optimally injects hydrogen into an intake pipe or a cylinder in a hydrogenated internal combustion engine that uses hydrogen gas together with gasoline as combustion fuel. For the purpose.

  In order to achieve the above object, a first invention is a hydrogen addition internal combustion engine that uses hydrogen gas together with hydrocarbon fuel as a combustion fuel, a hydrogen injection valve that injects hydrogen gas into an intake pipe or a cylinder, Pressure adjusting means for reducing the pressure of hydrogen gas applied to the hydrogen injector as the amount of hydrogen injected from the hydrogen injector decreases.

  According to a second invention, there is provided valve opening time acquisition means for acquiring a valve opening time when the hydrogen injection valve injects the hydrogen gas in the first invention, and the pressure adjusting means includes the valve opening time. The pressure of the hydrogen gas is reduced when it is equal to or lower than a predetermined threshold value.

According to a third invention, in the second invention, an operating state acquisition means for acquiring the operating state of the engine,
A hydrogen temperature acquisition means for acquiring the temperature of the hydrogen gas; and a hydrogen pressure acquisition means for acquiring the pressure of the hydrogen gas applied to the hydrogen injection valve, wherein the valve opening time acquisition means includes the operation state, the hydrogen gas The valve opening time is calculated based on the temperature of the gas and the pressure of the hydrogen gas.

  In order to achieve the above object, a fourth invention is a hydrogenated internal combustion engine that uses hydrogen gas together with hydrocarbon fuel as combustion fuel, a hydrogen injection valve that injects hydrogen gas into a cylinder, and operation of the engine An operation state acquisition means for acquiring a state; a first mode in which hydrogen gas is injected from the hydrogen injection valve in a compression stroke according to the operation state; and a first mode in which hydrogen gas is injected from the hydrogen injection valve in an intake stroke. Control means for operating the engine by switching between the two modes, and the pressure of the hydrogen gas applied to the hydrogen injector in the first mode is the pressure of the hydrogen gas applied to the hydrogen injector in the second mode. And a pressure adjusting means for adjusting the pressure to be higher.

  In a fifth aspect based on the fourth aspect, the first mode is a mode in which an engine is operated by adding hydrogen gas to a hydrocarbon fuel in a high load region, and the second mode is a low load to The mode is characterized in that the engine is operated by adding hydrogen gas to the hydrocarbon fuel in the middle load range.

  According to the first invention, the smaller the amount of hydrogen injected from the hydrogen injector, the lower the pressure of the hydrogen gas applied to the hydrogen injector, so the amount of hydrogen injected from the hydrogen injector is unstable. The region is not used, and the hydrogen injection amount can be accurately controlled. Therefore, the combustion state can be optimized in lean burn combustion using both hydrocarbon fuel and hydrogen.

  According to the second invention, when the opening time of the hydrogen injector is less than or equal to the predetermined threshold value, the hydrogen gas pressure is reduced. Hydrogen can be injected in a region where the relationship is almost linear. Therefore, even when the hydrogen injection amount is small, the hydrogen injection amount can be controlled with high accuracy.

  According to the third invention, since the valve opening time of the hydrogen injector is calculated based on the operating state, the temperature of the hydrogen gas, and the pressure of the hydrogen gas, the valve opening time can be obtained with high accuracy. Become.

  According to the fourth aspect of the present invention, the pressure of the hydrogen gas applied to the hydrogen injector in the first mode is higher than the pressure of the hydrogen gas applied to the hydrogen injector in the second mode. It becomes possible to inject hydrogen directly into the inside. Therefore, hydrogen can be added into the cylinder without reducing the output.

According to the fifth aspect, since the first mode is a mode in which the engine is operated by adding hydrogen gas to the hydrocarbon fuel in the high load region, knocking suppression in the high load region and reduction of the exhaust temperature are achieved. it can. In addition, since the second mode is a mode in which the engine is operated by adding hydrogen gas to the hydrocarbon fuel in a low load to medium load range, lean burn can improve fuel efficiency and efficiency, and NO _X Since emissions can be suppressed, emissions can be improved.

  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. The gasoline injection valve and the hydrogen fuel injection valve may be provided so as to inject fuel directly into the cylinder of the internal combustion engine 10.

  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 the hydrogen fuel port injection valve 28. The hydrogen fuel to be used is not limited to this, and a hydrogen-rich gas containing high-concentration 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 temperature sensor 46 and a fuel pressure sensor 48 are disposed between the regulator 44 and the hydrogen fuel port injection valve 28. The temperature sensor 46 is a sensor that emits an output corresponding to the temperature of hydrogen supplied to 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 the present embodiment, the regulator 44 is controlled based on the outputs generated by the temperature sensor 46 and the fuel pressure sensor 48. For this reason, even when the temperature and pressure of hydrogen supplied from the hydrogen tank 38 fluctuate, 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 temperature sensor 46 and 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 cooling water Various sensors (not shown) for detecting temperature, lubricating oil 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 the hydrogen from the hydrogen fuel port injection valve 28 in accordance with the operating condition of the internal combustion engine 10, it is possible to improve the combustion state in a cylinder (in the combustion chamber 16), the emissions of the NO _X Can be reduced.

  As described above, the hydrogen fuel port injection valve 28 can inject an amount of hydrogen into the intake port 18 in accordance with the valve opening time. When the hydrogen injection amount is relatively large, the relationship between the drive time (opening time) of the hydrogen fuel port injection valve 28 and the actual hydrogen injection amount injected from the hydrogen fuel port injection valve 28 is substantially linear. However, when the hydrogen injection amount becomes smaller than a predetermined value, the relationship between the drive time and the hydrogen injection amount may be nonlinear. This is due to the time from when the valve begins to open until the maximum lift is reached, or due to physical properties such as the inertia, viscosity, and density of the fuel, after the valve is opened and before the fuel is actually injected from the injector. This is caused by the time lag.

  FIG. 2 is a characteristic diagram showing the relationship between the drive time (valve opening time) of the hydrogen fuel port injection valve 28 and the hydrogen injection amount. As shown in FIG. 2, when the drive time of the hydrogen fuel port injection valve 28 is longer than the time A, the relationship between the drive time and the hydrogen injection amount has a substantially linear characteristic. In this case, the hydrogen injection amount can be controlled based on the drive time by storing the linear characteristic indicated by the broken line in FIG. 2 in the ECU 50 or the like. However, when the driving time of the hydrogen fuel port injection valve 28 is equal to or shorter than the time A, the relationship between the driving time and the hydrogen injection amount becomes non-linear. In the control based on the linear characteristic indicated by the broken line in FIG. It is difficult to accurately control the amount.

For example, when it is desired to adjust the hydrogen injection amount to the target value V shown in FIG. 2 in an operation state where the hydrogen injection amount is small, the hydrogen fuel port injection valve 28 is controlled by performing control based on the linear characteristic indicated by the broken line in FIG. The driving time is t1. In this case, since the actual hydrogen injection amount is V ₁ , the actual hydrogen injection amount V ₁ is smaller than the target value V. When performing lean burn combustion using both gasoline and hydrogen, the combustion state becomes unstable when the injection amount of hydrogen is lower than the target value.

  FIG. 3 is a characteristic diagram showing the relationship between the drive time of the hydrogen fuel port injection valve 28 and the hydrogen injection amount as in FIG. 2. The characteristic (characteristic A) shown in FIG. Both the characteristics (characteristic B) when the hydrogen pressure (hydrogen fuel pressure) applied to the fuel port injection valve 28 is lowered are shown.

  As shown in FIG. 3, when the hydrogen pressure applied to the hydrogen fuel port injection valve 28 is lowered, the hydrogen injection amount for the same driving time is reduced. However, the time A that is the boundary between the linear characteristic and the nonlinear characteristic is constant without being affected by the hydrogen pressure. Therefore, when the hydrogen pressure is reduced from the characteristic A to the characteristic B, hydrogen can be injected in a linear characteristic region even when the hydrogen injection amount is small.

  Specifically, when it is desired to adjust the hydrogen injection amount to the target value V described above, the hydrogen pressure applied to the hydrogen fuel port injection valve 28 is reduced to the hydrogen pressure corresponding to the characteristic B, and the hydrogen fuel port injection valve 28 is adjusted. Drive for the drive time t2. Thereby, the hydrogen fuel port injection valve 28 can be driven in a linear characteristic region, and the hydrogen injection amount can be accurately controlled to the target value V.

  On the other hand, when the target value of the hydrogen injection amount is sufficiently large, if the hydrogen pressure is reduced, the drive time of the hydrogen fuel port injection valve 28 becomes longer, particularly in the high load region, and the drive of the hydrogen fuel port injection valve 28 is driven. The load (power consumption) increases. Moreover, there is a concern that backfire may occur when the injection time is prolonged. Therefore, when the target value of the hydrogen injection amount is sufficiently large, the hydrogen pressure is set to the high pressure side (pressure corresponding to the characteristic A). Thereby, the drive load of the hydrogen fuel port injection valve 28 can be reduced. Further, since all hydrogen can be injected during the intake stroke even in a high load range, backfire can be reliably avoided. Accordingly, it is possible to suppress a decrease in the efficiency of the engine.

  Thus, in this embodiment, when the hydrogen injection amount is small and the drive time of the hydrogen fuel port injection valve 28 is short, the drive time is lengthened by reducing the hydrogen pressure applied to the hydrogen fuel port injection valve 28. I am doing so. Thereby, hydrogen can be injected in a region where the relationship between the drive time of the hydrogen fuel port injection valve 28 and the hydrogen injection amount is linear, and the hydrogen injection amount can be accurately controlled.

  In particular, when lean burn combustion is performed using both gasoline and hydrogen, the combustion state becomes unstable when the injection amount of hydrogen decreases from the target value. According to this embodiment, an unstable region where the hydrogen injection amount from the hydrogen fuel port injection valve 28 is not constant is not used, and the hydrogen injection amount can be accurately controlled. In lean burn combustion using both, the combustion state can be optimized.

  Next, the operation mode of the system of this embodiment will be described based on FIG. FIG. 4 is a schematic diagram showing each operation mode set according to the engine speed and the load. The system of the present embodiment includes a gasoline combustion region in which the internal combustion engine 10 is operated using only gasoline, and a hydrogen addition lean burn region in which the internal combustion engine 10 is operated by lean burn combustion using both gasoline and hydrogen. Has different modes.

As shown in FIG. 4, the operation is performed in the hydrogen addition lean burn region in the idling to normal rotation region. In addition, the operation is performed in the gasoline combustion region in a higher load and higher rotation region than in the hydrogen addition lean burn region. In the operation in the hydrogenated lean burn region, lean burn can improve fuel consumption and efficiency, and can suppress emission of NO _x , thereby improving emissions.

  The state where the hydrogen injection amount is small and the drive time of the hydrogen fuel port injection valve 28 is shorter than the time A shown in FIGS. 2 and 3 is a light load operation state where both the engine speed and the load are small. Occurs in the lean burn area. Therefore, in the present embodiment, the hydrogen addition lean burn region is divided into two regions, a hydrogen low fuel pressure setting region where the hydrogen pressure is set low and a hydrogen high fuel pressure setting region where the hydrogen pressure is set high. In the hydrogen low fuel pressure setting region, the hydrogen pressure applied to the hydrogen fuel port injection valve 28 is set to a pressure corresponding to the characteristic B in FIG. In the hydrogen high fuel pressure setting region, the hydrogen pressure applied to the hydrogen fuel port injection valve 28 is set to a pressure corresponding to the characteristic A in FIG. As a result, in a light load operating state where the engine speed and load are small, hydrogen can be injected according to the characteristic B, and the hydrogen injection amount can be accurately controlled even if the hydrogen injection amount is a minute value.

  Next, a processing procedure in the system of this embodiment will be described based on the flowchart of FIG. First, in step S1, the engine speed and the accelerator opening (load) are detected in order to acquire the current operating state. In the next step S2, based on the engine speed and the accelerator opening obtained in step S1, it is determined whether or not the current operation state is an operation in a hydrogen addition lean burn region in which operation is performed by adding hydrogen to gasoline. judge. If it is determined in step S2 that the current operation state is not the hydrogen addition lean burn region, that is, if the current operation state is determined to be the gasoline combustion region, it is necessary to inject hydrogen from the hydrogen fuel port injection valve 28. Since there is no data, the process ends (RETURN).

  On the other hand, if it is determined in step S2 that the current operating state is the hydrogenated lean burn region, the process proceeds to step S3. In step S3, the fuel pressure of hydrogen applied to the hydrogen fuel port injection valve 28 and the temperature of hydrogen are detected from the output values of the temperature sensor 46 and the fuel pressure sensor 48.

  In the next step S4, the driving time τ of the hydrogen fuel port injection valve 28 corresponding to the current operating state based on the engine speed, the accelerator opening obtained in step S1, the hydrogen fuel pressure detected in step S3, and the hydrogen temperature. Is calculated from the map.

  In the next step S5, the magnitude relationship between the drive time τ calculated in step S4 and a predetermined threshold value (time A shown in FIGS. 2 and 3) is compared, and it is determined whether or not τ <A. .

  If τ <A in step S5, the process proceeds to step S6. In this case, since the drive time τ is shorter than the time A, if hydrogen is injected with the drive time of the hydrogen fuel port injection valve 28 set to τ, the linearity of the hydrogen injection amount with respect to the drive time τ cannot be obtained. It becomes difficult to accurately control the injection amount.

  Therefore, in step S6, the hydrogen fuel pressure applied to the hydrogen fuel port injection valve 28 is set to a pressure (for example, a predetermined value less than 0.3 MPa) corresponding to the characteristic B in FIG. Thereby, even when the hydrogen injection amount is small and the drive time of the hydrogen fuel port injection valve 28 is very short, hydrogen can be injected in a region where the relationship between the drive time and the hydrogen injection amount is linear.

  On the other hand, if τ ≧ A in step S5, the process proceeds to step S7. In this case, since the drive time τ is equal to or longer than the time A, hydrogen can be injected in a region where the relationship between the drive time and the hydrogen injection amount is linear without reducing the hydrogen fuel pressure. Therefore, in this case, the hydrogen fuel pressure applied to the hydrogen fuel port injection valve 28 is set to a pressure (for example, a predetermined value of 0.3 MPa or more and 0.6 MPa or less) corresponding to the characteristic A in FIG. As described above, when the drive time τ is longer than the time A, it is possible to prevent the drive time of the hydrogen fuel port injector 28 from being prolonged by increasing the hydrogen fuel pressure, and the hydrogen fuel port injector 28. The driving load when opening the valve can be reduced.

  After steps S6 and S7, the process proceeds to step S8. In step S8, the actuator of the regulator 44 is driven based on the hydrogen fuel pressure set in steps S6 and S7, and the hydrogen fuel pressure applied to the hydrogen fuel port injection valve 28 is controlled to be the value set in steps S6 and S7.

  In the next step S9, the hydrogen fuel pressure after driving the actuator of the regulator 44 is detected from the fuel pressure sensor 48, and a deviation Pd between the detected hydrogen fuel pressure and the target fuel pressure (value set in steps S6 and S7) is obtained. Then, it is determined whether or not Pd <B, and it is determined whether or not the deviation Pd is within a predetermined threshold value B.

  If Pd <B in step S9, the process proceeds to step S10. In this case, since the deviation Pd is smaller than the threshold value B, it is determined that the hydrogen fuel pressure is controlled to the target value. Then, from the output values of the temperature sensor 46 and the fuel pressure sensor 48, the hydrogen fuel pressure and the hydrogen temperature applied to the hydrogen fuel port injector 28 are detected, and based on this, the drive time of the hydrogen fuel port injector 28 is corrected, Find the final drive time.

  After step S10, the process proceeds to step S11, and an injection signal is started to the hydrogen fuel port injection valve 28 based on the final drive time obtained in step S10. As a result, the hydrogen fuel port injection valve 28 is opened during the drive time obtained in step S10.

  On the other hand, if Pd ≧ B in step S9, the deviation Pd is greater than or equal to the threshold value B, so it is determined that the hydrogen fuel pressure is not controlled to the target value. In this case, the process returns to step S8, and the adjustment by the regulator 44 is performed again so that the hydrogen fuel pressure becomes the target value.

  According to the process of FIG. 5, when the driving time τ of the hydrogen fuel port injection valve 28 is shorter than the predetermined threshold A, the hydrogen fuel pressure is set to a low fuel pressure, so that the driving time τ, the hydrogen injection amount, Hydrogen can be injected in a region where the relationship is linear. Therefore, even when the hydrogen injection amount is small, the hydrogen injection amount can be accurately controlled.

  Further, since hydrogen is a gaseous fuel, the injection amount varies greatly depending on the temperature and pressure of hydrogen even if the driving time of the hydrogen fuel port injection valve 28 is the same. According to the processing of FIG. 5, the driving time τ is obtained in consideration of the temperature and pressure of hydrogen, and the pressure applied to the hydrogen fuel port injection valve 28 is set based on the driving time τ. The pressure applied to the hydrogen fuel port injection valve 28 can be set with higher accuracy than when the pressure is set based on the state (the number of revolutions and the load). Therefore, it is possible to reliably avoid hydrogen injection in an unstable region where the hydrogen injection amount from the hydrogen fuel port injection valve 28 is not constant. Further, in step S10 for obtaining the final drive time, the drive time of the hydrogen fuel port injector 28 is corrected because the drive time of the hydrogen fuel port injector 28 is corrected based on the hydrogen fuel pressure and the hydrogen temperature. It can be controlled with high accuracy.

  As described above, according to the first embodiment, when the drive time of the hydrogen fuel port injection valve 28 is short, the hydrogen fuel pressure is reduced, so that the relationship between the drive time and the hydrogen injection amount is substantially linear. Hydrogen can be injected in the region. Therefore, even when the hydrogen injection amount is small, the hydrogen injection amount can be controlled with high accuracy.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 6 is a schematic diagram illustrating a configuration of a system including the hydrogenated internal combustion engine 10 according to the second embodiment. As shown in FIG. 6, in the second embodiment, a hydrogen fuel in-cylinder injection valve 30 that directly injects hydrogen into the cylinder of the hydrogenated internal combustion engine 10 is provided instead of the hydrogen fuel port injection valve 28 in FIG. Yes. Other configurations of the system of the second embodiment are the same as those in FIG.

  FIG. 7 is a schematic diagram illustrating an operation mode of the system according to the second embodiment. Also in the second embodiment, the operation is performed in the hydrogen addition lean burn region in the idling to normal rotation region, and the operation is performed in the gasoline combustion region in the higher load and high rotation region than the hydrogen addition lean burn region.

  By the way, when the operation is performed on the higher rotation side and the higher load side, the exhaust temperature rises and the exhaust loss increases, so the efficiency may decrease. Further, knocking may occur when operation is performed under conditions of low rotation and high load.

  For this reason, in the second embodiment, as shown in FIG. 7, a hydrogen addition region is provided in each of the region on the higher rotation side and the higher load side than the gasoline combustion region, and the region on the lower rotation and higher load side of the gasoline combustion region. Is set. In the hydrogen addition region, gasoline is supplied from the gasoline injection valve 26 into the cylinder, and hydrogen is injected from the hydrogen fuel in-cylinder injection valve 30 into the cylinder. Thereby, the combustion speed in a cylinder can be made quick and a combustion state can be made favorable. Therefore, it is possible to reliably suppress the occurrence of knocking and the decrease in efficiency due to the increase in exhaust temperature.

  When hydrogen is injected in the hydrogen addition region, if the hydrogen is injected during the intake stroke, the amount of intake air into the cylinder decreases, and the high output originally required in the hydrogen addition region cannot be obtained. . In the present embodiment, since the hydrogen fuel in-cylinder injection valve 30 for directly injecting hydrogen into the cylinder is provided, hydrogen can be injected into the cylinder in the compression stroke. Accordingly, it is possible to avoid a reduction in the amount of intake air due to hydrogen injection, and it is possible to add hydrogen without lowering the output in a high load range.

  In the hydrogen addition lean burn region, since the amount of intake air is smaller than that in the hydrogen addition region, the output does not decrease even if hydrogen is injected in the first half of the intake stroke to the compression stroke. In the hydrogen addition lean burn region, in order to perform the lean burn operation, it is preferable to inject hydrogen during the intake stroke in order to mix hydrogen with the gasoline mixture as soon as possible. Accordingly, in the hydrogen addition lean burn region, hydrogen is injected in the first half of the intake stroke to the compression stroke.

  As a result, the occurrence of knocking in the hydrogen addition region and the reduction in efficiency due to the increase in the exhaust temperature can be reliably suppressed, and the fuel consumption and the emission can be improved by the lean burn operation in the hydrogen addition lean burn region.

  As described above, in the second embodiment, hydrogen is added in both the hydrogenation region and the hydrogenation lean burn region. However, in the case of adding hydrogen in the hydrogenation region and in the hydrogenation lean burn region, hydrogen is added. It is preferable that the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 be varied.

  When hydrogen is injected into the cylinder in the compression stroke, the pressure in the cylinder is increased, and therefore it is necessary to inject hydrogen at a high pressure into the cylinder. For this reason, in the hydrogen addition region, it is necessary to set the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 to a high pressure.

  On the other hand, in the hydrogen addition lean burn region, since the in-cylinder pressure in the first half of the intake stroke to the compression stroke is lower than that in the compression stroke, the hydrogen fuel pressure can be set to the low pressure side. As a result, it is possible to avoid an increase in the drive time of the hydrogen fuel in-cylinder injection valve 30, and to reduce the drive load of the hydrogen fuel in-cylinder injection valve 30. Further, since the intake stroke injection can be performed at a low pressure in the low load to medium load range, the hydrogen in the hydrogen tank 38 can be used effectively. Furthermore, by setting the hydrogen fuel pressure to the low pressure side, the load on the compressor for pressurization can be reduced when the system does not have a high-pressure hydrogen cylinder.

  In the present embodiment, the hydrogen pressure is uniformly set on the low pressure side in the entire hydrogen-added lean burn region, but injection is performed in an unstable region where the hydrogen injection amount is not constant in the same manner as in the first embodiment. In order to avoid this, the region where the hydrogen pressure becomes lower may be set on the low rotation and low load side of the hydrogen addition lean burn region.

  Next, a processing procedure in the system of this embodiment will be described based on the flowchart of FIG. First, in step S21, the engine speed and the accelerator opening (load) are detected in order to acquire the current operating state. In the next step S22, it is determined whether or not the current operation state is the operation in the hydrogen addition lean burn region or the hydrogen addition region based on the engine speed and the accelerator opening obtained in step S21. If it is determined in step S22 that the current operation state does not correspond to either the hydrogen addition lean burn region or the hydrogen addition region, that is, if the current operation state is determined to be the gasoline combustion region, the hydrogen fuel port Since it is not necessary to inject hydrogen from the injection valve 28, the process is terminated (RETURN).

  On the other hand, if it is determined in step S22 that the current operation state is the hydrogenated lean burn region or the hydrogenated region, the process proceeds to step S23. In step S23, the hydrogen fuel pressure and the hydrogen temperature applied to the hydrogen fuel in-cylinder injection valve 30 are detected from the output values of the temperature sensor 46 and the fuel pressure sensor 48.

  In the next step S24, it is determined based on the engine speed and the accelerator opening acquired in step S21 whether or not the current operation state is the operation in the hydrogen addition lean burn region.

  When it is determined in step S24 that the current operation state is the hydrogen addition lean burn region, the process proceeds to step S25. Proceed to step S25. In this case, since hydrogen is injected from the hydrogen fuel in-cylinder injection valve 30 in the first half of the intake stroke to the compression stroke, it is not necessary to set the hydrogen fuel pressure high. Therefore, in step S25, the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 is set to a low fuel pressure (for example, a predetermined value less than 1.0 MPa).

  On the other hand, if it is not determined in step S24 that the current operation state is the hydrogen addition lean burn region, the process proceeds to step S26. In this case, since the current operation state is the hydrogen addition region and it is necessary to inject hydrogen into the cylinder during the compression stroke, the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 is set to a high fuel pressure (for example, 0.3 MPa). The predetermined value is 0.6 MPa or less.

  After steps S25 and S26, the process proceeds to step S27. In step S27, the actuator of the regulator 44 is driven based on the hydrogen fuel pressure set in steps S25 and S26 so that the hydrogen fuel pressure required for operation by adding hydrogen to gasoline becomes the value set in steps S25 and S26. To control.

  In the next step S28, the hydrogen fuel pressure after driving the actuator of the regulator 44 is detected from the fuel pressure sensor 48, and a deviation Pd between the detected hydrogen fuel pressure and the target fuel pressure (value set in steps S25 and S26) is obtained. Then, it is determined whether or not Pd <B, and it is determined whether or not the deviation Pd is within a predetermined threshold value B.

  If Pd <B in step S28, the process proceeds to step S29. In this case, since the deviation Pd is smaller than the threshold value B, it is determined that the hydrogen fuel pressure is controlled to the target value. Then, from the output values of the temperature sensor 46 and the fuel pressure sensor 48, the hydrogen fuel pressure and the hydrogen temperature applied to the hydrogen fuel port injector 28 are detected, and based on this, the drive time of the hydrogen fuel port injector 28 is corrected, Find the final drive time.

  After step S29, the process proceeds to step S30, and an injection signal is started to the hydrogen fuel port injection valve 28 based on the final drive time obtained in step S29. As a result, the hydrogen fuel port injection valve 28 is opened during the drive time obtained in step S29.

  On the other hand, if Pd ≧ B in step S28, the deviation Pd is equal to or greater than the threshold value B, so it is determined that the hydrogen fuel pressure is not controlled to the target value. In this case, the process returns to step S27, and the adjustment by the regulator 44 is performed again so that the hydrogen fuel pressure becomes the target value.

  According to the process of FIG. 8, when hydrogen is injected in the hydrogen addition region, the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 is set to a high fuel pressure, so that hydrogen is directly injected into the cylinder in the compression stroke. It becomes possible. Therefore, it is possible to add hydrogen into the cylinder without reducing the output.

  As described above, according to the second embodiment, when hydrogen is injected in the hydrogen addition region for the purpose of suppressing knocking or lowering the exhaust temperature, the hydrogen fuel pressure applied to the hydrogen fuel in-cylinder injection valve 30 is set to a high fuel pressure. Therefore, it is possible to inject hydrogen directly into the cylinder during the compression stroke. Therefore, it is possible to add hydrogen to the cylinder without reducing the output, and it is possible to suppress a reduction in efficiency due to the occurrence of knocking or an increase in exhaust temperature.

It is a schematic diagram which shows the structure of the system provided with the hydrogenation internal combustion engine which concerns on Embodiment 1 of this invention. It is a characteristic view which shows the relationship between the drive time (valve opening time) of a hydrogen fuel port injection valve, and hydrogen injection amount. FIG. 3 is a characteristic diagram showing the relationship between the driving time of the hydrogen fuel port injection valve and the hydrogen injection amount, the characteristic of FIG. 2 (characteristic A) and the characteristic when the hydrogen pressure is lowered from characteristic A (characteristic B). It is a characteristic view which shows both. 3 is a schematic diagram illustrating an operation mode according to Embodiment 1. FIG. 3 is a flowchart illustrating a processing procedure in the system according to the first embodiment. It is a schematic diagram which shows the structure of the system provided with the hydrogenation internal combustion engine which concerns on Embodiment 2 of this invention. 6 is a schematic diagram illustrating an operation mode of a second embodiment. FIG. 10 is a flowchart illustrating a processing procedure in the system according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydrogenation internal combustion engine 28 Hydrogen fuel port injection valve 30 Hydrogen fuel cylinder injection valve 44 Regulator 46 Temperature sensor 48 Fuel pressure sensor 50 ECU

Claims (5)

A hydrogenated internal combustion engine that uses hydrogen gas as a combustion fuel together with a hydrocarbon fuel,
A hydrogen injection valve for injecting hydrogen gas into the intake pipe or cylinder;
Pressure adjusting means for reducing the pressure of hydrogen gas applied to the hydrogen injection valve as the amount of hydrogen injected from the hydrogen injection valve decreases;
A hydrogenated internal combustion engine comprising: A valve opening time acquisition means for acquiring a valve opening time when the hydrogen injection valve injects the hydrogen gas;
2. The hydrogenated internal combustion engine according to claim 1, wherein the pressure adjusting means reduces the pressure of the hydrogen gas when the valve opening time is equal to or less than a predetermined threshold value. Operating state acquisition means for acquiring the operating state of the engine;
Hydrogen temperature acquisition means for acquiring the temperature of hydrogen gas;
Hydrogen pressure acquisition means for acquiring the pressure of hydrogen gas applied to the hydrogen injection valve,
3. The hydrogenated internal combustion engine according to claim 2, wherein the valve opening time acquisition unit calculates the valve opening time based on the operating state, the temperature of the hydrogen gas, and the pressure of the hydrogen gas. A hydrogenated internal combustion engine that uses hydrogen gas as a combustion fuel together with a hydrocarbon fuel,
A hydrogen injection valve for injecting hydrogen gas into the cylinder;
Operating state acquisition means for acquiring the operating state of the engine;
According to the operating state, the engine is switched by switching between a first mode in which hydrogen gas is injected from the hydrogen injector in the compression stroke and a second mode in which hydrogen gas is injected from the hydrogen injector in the intake stroke. Control means for driving;
Pressure adjusting means for adjusting the pressure of hydrogen gas applied to the hydrogen injector in the first mode to be higher than the pressure of hydrogen gas applied to the hydrogen injector in the second mode;
A hydrogenated internal combustion engine comprising:   The first mode is a mode in which the engine is operated by adding hydrogen gas to the hydrocarbon fuel in a high load range, and the second mode is a mode in which hydrogen gas is added to the hydrocarbon fuel in a low load to medium load range. The hydrogenated internal combustion engine according to claim 4, wherein the mode is a mode for operating the engine.

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