JP2006125267A - Hydrogen-added internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten warming-up time of a catalyst in a hydrogen-added internal combustion engine using hydrogen gas together with gasoline as fuel for combustion. <P>SOLUTION: This hydrogen-added internal combustion engine 10 uses hydrogen gas together with hydrocarbon fuel as fuel for combustion. The hydrogen-added internal combustion engine 10 is provided with a gasoline injection valve 38 injecting gasoline to an intake passage 12; a hydrogen fuel port injection valve 40 injecting hydrogen gas to the intake passage 12; and a hydrogen injection amount increasing means increasing injection amount of hydrogen gas at the time of catalyst warming-up, compared to normal time. Thereby, unburned hydrogen gas that was not burned inside a cylinder can be combusted on the catalyst, and catalyst warming-up can be performed for a short time. <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-4-318214 Japanese National Patent Publication No. 11-501378 JP-T-2001-510260

  Although an internal combustion engine is equipped with a catalyst that purifies exhaust gas, it is difficult to purify exhaust components until the catalyst is activated because the catalyst temperature is low immediately after the engine is started and the catalyst is not activated. It becomes. For this reason, in an internal combustion engine that uses ordinary gasoline as fuel, the amount of gasoline supplied into the cylinder at the time of engine startup is greatly increased from the stoichiometric ratio, and unburned components are sent to the exhaust system, and unburned components are burned on the catalyst. In this way, the catalyst is activated.

  However, because the unburned components of gasoline sent to the exhaust system have a low combustion temperature, when the amount of gasoline is increased for warming up in an internal combustion engine that burns hydrogen and gasoline, the warm-up time of the catalyst becomes longer. Problems arise. For this reason, it takes a long time for the catalyst to be activated, and the exhaust component cannot be purified until the catalyst is activated, resulting in a problem of reduced emissions.

  In addition, since unburned components of gasoline have characteristics that are relatively difficult to burn, when gasoline is burned on a catalyst, it is necessary to supply a large amount of gasoline. For this reason, the problem that efficiency and a fuel consumption fall arises. Furthermore, since the unburned components of gasoline do not burn on the catalyst until the catalyst reaches a certain temperature, when a large amount of gasoline is supplied, the unburned gasoline passes through the catalyst and is discharged outside. Also occurs.

  The present invention has been made to solve the above-described problems, and an object thereof is to further shorten the warm-up time of a catalyst in a hydrogenated internal combustion engine that uses hydrogen gas together with gasoline as combustion fuel. .

  In order to achieve the above object, a first aspect of the present invention is a hydrogenated internal combustion engine that uses hydrogen gas together with hydrocarbon fuel as combustion fuel, and injects hydrocarbon fuel into an intake passage or a cylinder. And a hydrogen injection valve for injecting hydrogen gas into the intake passage or the cylinder, and a hydrogen injection amount increasing means for increasing the injection amount of hydrogen gas compared to the normal time when the catalyst is warmed up. To do.

  A second invention is characterized in that, in the first invention, the hydrogen injection amount increasing means increases the ratio of addition of hydrogen gas to the hydrocarbon fuel when the catalyst is warmed up compared to the normal time.

  According to a third invention, in the first or second invention, the hydrogen injection valve is an injection valve that directly injects hydrogen gas into a cylinder, and injects hydrogen gas in an intake stroke or a compression stroke and an exhaust stroke. It is characterized by.

  According to a fourth invention, in the third invention, hydrogen gas is continuously injected from an intake stroke or a compression stroke to an exhaust stroke.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, only hydrogen gas is supplied as combustion fuel when the catalyst is warmed up.

  A sixth invention is characterized in that, in any one of the first to fifth inventions, after the catalyst temperature reaches a predetermined temperature, the injection amount of hydrocarbon fuel is increased and the injection amount of hydrogen gas is decreased. To do.

  According to the first aspect of the invention, when the catalyst is warmed up, the amount of hydrogen gas injected is increased as compared with the normal time. Therefore, unburned hydrogen gas that has not been burned in the cylinder is sent to the exhaust passage, and the hydrogen gas is passed over the catalyst. Can be burned. Since hydrogen has a high combustion rate and a high combustion temperature, the catalyst can be warmed up in a short time. In addition, since a part of the supplied hydrogen gas is lean burn burned together with the hydrocarbon fuel in the cylinder, fuel efficiency and efficiency can be improved.

  According to the second aspect of the invention, when the catalyst is warmed up, the ratio of hydrogen gas to the hydrocarbon fuel is increased as compared with the normal time, so that the hydrogen gas injection amount can be increased as compared with the normal time. Therefore, it becomes possible to burn unburned hydrogen gas on the catalyst.

  According to the third aspect, since the hydrogen gas is directly injected into the cylinder during the exhaust stroke, the injected hydrogen gas can be sent to the exhaust passage. Since the injected hydrogen gas does not contribute to combustion in the cylinder, the entire amount of the injected hydrogen gas can be burned on the catalyst. Further, by injecting the hydrogen gas in the intake stroke or the compression stroke, the lean burn combustion of the hydrogen gas and the hydrocarbon fuel can be performed in the cylinder, and the fuel consumption and emission can be improved.

  According to the fourth invention, since hydrogen gas is continuously injected from the intake stroke or the compression stroke to the exhaust stroke, the in-cylinder combustion hydrogen gas and the catalyst warm-up hydrogen gas can be injected simultaneously.

  According to the fifth aspect of the present invention, only hydrogen gas is supplied as combustion fuel when the catalyst is warmed up, so that the catalyst can be warmed up only by burning hydrogen gas.

  According to the sixth aspect of the invention, after the catalyst temperature reaches the predetermined temperature, in order to increase the injection amount of the hydrocarbon fuel, the catalyst can be warmed up by burning the hydrocarbon fuel on the catalyst. Therefore, by reducing the injection amount of hydrogen gas, the amount of hydrogen used for warming up the catalyst can be minimized, and the size of the tank for storing hydrogen gas can be minimized.

  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. An intake passage 12 and an exhaust passage 14 communicate with the internal combustion engine 10. The intake passage 12 includes an air filter 16 at an upstream end. The air filter 16 is assembled with an intake air temperature sensor for detecting the intake air temperature THA (that is, the outside air temperature).

  An air flow meter 18 is disposed downstream of the air filter 16. A surge tank 20 is provided downstream of the air flow meter 18. A throttle valve 22 is provided downstream of the surge tank 20. In the vicinity of the throttle valve 22, a throttle sensor that detects the throttle opening degree TA and an idle switch that is turned on when the throttle valve is fully closed are disposed.

  A piston 24 that reciprocates inside the cylinder of the internal combustion engine 10 is provided. The internal combustion engine 10 includes a cylinder head 26. A combustion chamber 28 is formed between the piston 24 and the cylinder head 26. An intake port 30 and an exhaust port 32 communicate with the combustion chamber 28, and the intake port 30 is connected to the intake passage 12, and the exhaust port 32 is connected to the exhaust passage 14. An intake valve 34 and an exhaust valve 36 are disposed in the intake port 30 and the exhaust port 32, respectively.

  A gasoline injection valve 38 for injecting gasoline (hydrocarbon fuel) into the port is disposed in the intake passage 12. A hydrogen fuel port injection valve 40 for injecting hydrogen into the port is disposed in the intake passage 12. 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 44 communicates with the gasoline injection valve 38 via a gasoline supply pipe 42. The gasoline supply pipe 42 includes a pump 46 and a gasoline flow meter 48 between the gasoline injection valve 38 and the gasoline tank 44. The pump 46 can supply gasoline at a predetermined pressure to the gasoline injection valve 38. For this reason, the gasoline injection valve 38 is able to inject an amount of gasoline into the intake passage 12 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 50 for storing hydrogen in a gaseous state at a high pressure. A hydrogen supply pipe 52 communicates with the hydrogen tank 50. The hydrogen supply pipe 52 communicates with the hydrogen fuel port injection valve 40. In the system of the present embodiment, hydrogen gas charged into the hydrogen tank 50 from the outside is used as the hydrogen fuel supplied to the hydrogen fuel port injection valve 40. However, the hydrogen fuel is supplied to the hydrogen fuel port injection valve 40. 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 56 is disposed in the hydrogen supply pipe 40. According to such a configuration, the hydrogen in the hydrogen tank 50 is supplied to the hydrogen fuel port injection valve 40 at a predetermined pressure reduced by the regulator 56. For this reason, the hydrogen fuel port injection valve 40 is able to inject an amount of hydrogen into the intake passage 12 according to the opening time by opening the valve in response to a drive signal supplied from the outside.

  In the hydrogen supply pipe 52, a temperature sensor 54 and a fuel pressure sensor 55 are disposed between the regulator 56 and the hydrogen tank 50. The temperature sensor 54 is a sensor that emits an output corresponding to the temperature of hydrogen supplied to the hydrogen fuel port injection valve 40. The fuel pressure sensor 55 is a sensor that emits an output corresponding to the pressure of hydrogen supplied to the hydrogen fuel port injection valve 40. In the system of the present embodiment, the regulator 52 is controlled based on the outputs generated by the temperature sensor 54 and the fuel pressure sensor 55. For this reason, even if the temperature and pressure of hydrogen supplied from the hydrogen tank 50 vary, hydrogen can be supplied to the hydrogen fuel port injection valve 40 at a stable pressure.

An O ₂ sensor 58 and a NOx sensor 60 are incorporated in the exhaust passage 14. The O ₂ sensor 58 is a sensor that generates an output corresponding to the exhaust air-fuel ratio based on the presence or absence of oxygen in the exhaust gas. The NOx sensor 60 is a sensor that emits an output corresponding to the NOx concentration in the exhaust gas. A catalyst 62 for purifying exhaust gas is disposed downstream of the sensors 58 and 60. The catalyst 62 incorporates a catalyst bed temperature sensor 64 for detecting the catalyst bed temperature. The catalyst bed temperature sensor 64 is constituted by a thermocouple or the like.

The system of this embodiment includes an ECU 70. In addition to the temperature sensor 54, the fuel pressure sensor 55, the O ₂ sensor 58, the NOx sensor 60, and the catalyst bed temperature sensor 62 described above, the ECU 70 includes a KCS sensor that detects the occurrence of knocking in order to grasp the operating state of the internal combustion engine 10. Also, various sensors (not shown) for detecting the throttle opening, the engine speed, the exhaust temperature, the coolant temperature, the lubricating oil temperature, and the like are connected. The ECU 70 is connected to actuators such as the gasoline injection valve 38, the hydrogen fuel port injection valve 40, and the pump 46 described above. According to such a configuration, the ECU 70 can arbitrarily select an injection valve that performs fuel injection according to the operating state of the internal combustion engine 10.

  FIG. 2 is a schematic diagram for explaining the operation mode of the system of the present embodiment, and shows 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. 2, 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 hydrogen-added lean burn region, hydrogen is added to gasoline and lean burn combustion is performed, so that the combustion state in the cylinder (in the combustion chamber 16) can be improved, and fuel efficiency and efficiency can be improved. it can. Further, emission of NO _x can be suppressed by lean burn combustion, so that emission can be improved.

In the hydrogenation combustion mode, when gasoline and hydrogen are combusted, hydrogen is added to the gasoline at an addition ratio at which the heat generation amount of hydrogen is about 20% with respect to the heat generation amount of gasoline. Thereby, the combustion state in the cylinder (inside the combustion chamber 16) can be improved, and fuel efficiency and efficiency can be improved. Further, emission of NO _x can be suppressed by lean burn combustion, so that emission can be improved.

  In the system of the present embodiment configured as described above, immediately after starting, the catalyst warm-up operation is performed in order to make the temperature of the catalyst 62 reach the activation temperature. Specifically, the fuel amount is increased from the normal time, and the unburned fuel that has not been burned in the cylinder is burned on the catalyst 62, whereby the operation for raising the catalyst temperature in a short time is performed.

  At this time, if the injection amount from the gasoline injection valve 38 is increased, the combustion temperature of gasoline is relatively low, so that a certain amount of time is required until the temperature of the catalyst 62 reaches the activation temperature. On the other hand, since the combustion temperature of hydrogen is much higher than that of gasoline, if the hydrogen injection amount is increased during warm-up, the catalyst 62 can be warmed up in a very short time.

  For this reason, in the present embodiment, when warming up the catalyst 62, the amount of hydrogen sent into the cylinder is increased from the normal time. Thereby, the unburned hydrogen that has not been burned in the cylinder can be burned on the catalyst 62 side. Since hydrogen has a high combustion speed and a high combustion temperature, the temperature of the catalyst 62 can instantaneously reach the activation temperature even with a small increase. Therefore, it is possible to greatly improve the emission immediately after starting.

  As a guideline for increasing the amount of hydrogen, only the amount of hydrogen is increased so that the total amount of gasoline and hydrogen supplied into the cylinder becomes fuel rich with respect to the amount of intake air. As a result, unburned fuel is generated, and hydrogen that has not been burned in the cylinder can flow to the exhaust passage 14 side.

  In the normal hydrogenation combustion mode, when hydrogen is added so that the heat generation amount of hydrogen is 20% of the heat generation amount of gasoline, the hydrogen addition ratio to gasoline is 0 hydrogen per gram of gasoline. .07 grams. Then, lean burn combustion is performed with the excess air ratio λ = 2. Here, the excess air ratio λ is the ratio of the air amount to the fuel amount (gasoline amount and hydrogen amount), and when the excess air ratio λ = 1, the stoichiometric ratio with respect to the fuel amount (gasoline amount and hydrogen amount). The amount of air is sent into the cylinder. Therefore, in the hydrogen addition combustion mode in which the excess air ratio λ = 2, twice the amount of air as in the case of stoichiometric is sent into the cylinder.

  On the other hand, when the catalyst is warmed up, only the hydrogen amount is increased without changing the gasoline amount, and the excess air ratio λ is controlled to be 1 or less. As a result, the amount of fuel becomes richer than the amount of air, so that unburned fuel is generated in the cylinder. Specifically, in order to increase only the hydrogen amount without changing the gasoline amount so that the excess air ratio λ is 1 or less, the hydrogen addition ratio to gasoline is 0.56 g hydrogen to 1 gram gasoline. That's it. Thereby, the excess air ratio can be made 1 or less, and unburned hydrogen can be sent to the catalyst 62 side.

  Thus, in the system of the present embodiment, the amount of hydrogen injected into the cylinder is increased more than usual when the catalyst is warmed up, so that the catalyst can be warmed up in a very short time. In addition, since a part of the supplied hydrogen burns lean together with gasoline in the cylinder, fuel efficiency and efficiency can be improved. Therefore, it is possible to simultaneously achieve both a reduction in the catalyst warm-up time due to the increase in hydrogen and an improvement in efficiency due to lean burn combustion. In addition, in the case of an engine that supplies only hydrogen as fuel, it is necessary to supply a large amount of hydrogen in order to warm up the catalyst while generating an idle load. In this embodiment, gasoline and hydrogen are burned together. Thus, a predetermined load can be generated, so that the amount of hydrogen during warm-up can be minimized. Furthermore, since the hydrogen amount is increased without changing the gasoline amount when the catalyst is warmed up, the total amount of hydrocarbons flowing into the exhaust passage 14 can be reduced.

  In addition, when the catalyst is warmed up, the gasoline injection may be stopped and only hydrogen may be injected from the hydrogen fuel port injection valve 40. At this time, hydrogen is injected so that the total amount of hydrogen supplied into the cylinder becomes fuel rich with respect to the intake air amount. Thereby, unburned hydrogen is generated, and hydrogen that has not been burned in the cylinder can flow to the exhaust passage 14 side.

  Next, a processing procedure in the system of the present embodiment will be described based on the flowchart of FIG. First, in step S1, the catalyst bed temperature Tcat is acquired from the output of the catalyst bed temperature sensor 64. In the next step S2, the catalyst bed temperature Tcat and the catalyst activation temperature T0 are compared to determine whether or not Tcat <T0. Here, the catalyst activation temperature T0 is the lowest temperature for the catalyst to perform its function.

  If Tcat <T0 in step S2, the process proceeds to step S3. In this case, since the current catalyst bed temperature Tcat has not reached the catalyst activation temperature T0, the catalyst 62 needs to be warmed up. Accordingly, in step S3, hydrogen rich control for increasing the hydrogen injection amount is started. Then, hydrogen rich control for warming up the catalyst 62 is performed in subsequent steps. Specifically, as described above, without changing the gasoline injection amount, only the hydrogen injection amount is increased and the excess air ratio λ is controlled to be 1 or less.

  On the other hand, if Tcat ≧ T0 in step S2, the current catalyst bed temperature Tcat has reached the catalyst activation temperature T0, so there is no need to warm up the catalyst 62. Therefore, in this case, the process is terminated (RETURN).

  After step S3, the process proceeds to step S4. In step S4, in order to warm up the catalyst 62, the hydrogen injection amount from the hydrogen fuel port injection valve 40 is increased. Due to this increase, unburned hydrogen that has not burned in the cylinder out of the hydrogen injected from the hydrogen fuel port injection valve 40 is sent to the exhaust passage 14 and burned on the catalyst 62. Since the combustion temperature of hydrogen is much higher than that of gasoline, it is possible to instantly warm up the catalyst 62 by burning unburned hydrogen on the catalyst 62. Therefore, the catalyst 62 can reach the activation temperature in a very short time.

After step S4, the process proceeds to step S5. In step S5, the amount of oxygen in the exhaust gas is acquired based on the output of the O ₂ sensor 58 provided in the exhaust passage 14. In the next step S6, the excess air ratio λ is calculated based on the oxygen amount obtained in step S5, and it is determined whether or not λ <1. Here, when it is detected from the output of the O ₂ sensor 58 that oxygen is flowing into the exhaust passage 14, the amount of oxygen after combustion in the cylinder is excessive, so the gasoline supplied into the cylinder, It can be determined that most of the hydrogen is burning in the cylinder. Therefore, in this case, it can be determined that the excess air ratio λ is 1 or more. On the other hand, when almost no oxygen flows in the exhaust passage, most of the oxygen in the air supplied into the cylinder is used for combustion in the cylinder, and unburned hydrogen flows in the exhaust passage. I can judge. Therefore, in this case, it can be determined that the excess air ratio λ is less than 1. An A / F sensor may be provided in place of the O ₂ sensor 58, and it may be determined whether or not the excess air ratio λ is less than 1 based on the output of the A / F sensor.

  When λ <1 in step S6, the excess air ratio is smaller than 1, and therefore the amount of hydrogen increase in step S4 is appropriately performed. Accordingly, in this case, the process returns to step S2, and it is determined whether or not the catalyst bed temperature Tcat has reached the catalyst activation temperature T0. If the catalyst bed temperature T0 has not reached the catalyst activation temperature T0, the processes after step S3 are performed again. If the catalyst bed temperature Tcat has reached the catalyst activation temperature T0 in step S2, the process is terminated (RETURN).

  If λ ≧ 1 in step S6, the excess air ratio is 1 or more, so it can be determined that the amount of hydrogen increase for performing catalyst warm-up is insufficient. Therefore, in this case, the process returns to step S4, and hydrogen is increased again.

  According to the process of FIG. 3, when the catalyst bed temperature Tcat has not reached the catalyst activation temperature T0, the hydrogen injection amount from the hydrogen fuel port injection valve 40 is increased, so that unburned hydrogen is removed from the catalyst 62. Can be burned. Therefore, the catalyst 62 can be warmed up in a short time.

  In the process of FIG. 3, when the catalyst bed temperature Tcat reaches a predetermined temperature lower than the catalyst activation temperature T0, the catalyst is warmed up by increasing the injection amount of gasoline and burning unburned gasoline on the catalyst. May be. Thereby, since the hydrogen injection amount can be reduced, the amount of hydrogen used for warming up the catalyst can be minimized, and the hydrogen tank 50 can be downsized.

  As described above, according to the first embodiment, when the catalyst 62 is warmed up, the amount of hydrogen supplied into the cylinder is increased, so that unburned hydrogen that has not burned in the cylinder is exhausted. It can flow to the passage 14. Therefore, hydrogen can be burned in or near the catalyst 62, and the temperature of the catalyst 62 can be instantaneously increased. Thereby, it is possible to greatly improve the emission immediately after the engine is started.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. FIG. 4 is a diagram for explaining a configuration of a system including the hydrogenated internal combustion engine 10 according to the second embodiment. As shown in FIG. 4, in the second embodiment, a hydrogen fuel in-cylinder injection valve 66 for directly injecting hydrogen into the cylinder of the hydrogenated internal combustion engine 10 is provided instead of the hydrogen fuel port injection valve 40 in FIG. Yes. Other configurations of the system of the second embodiment are the same as those in FIG. Moreover, the operation mode of Embodiment 2 is the same as that of FIG.

  In the system according to the second embodiment, hydrogen can be directly injected into the cylinder from the hydrogen fuel in-cylinder injection valve 66. Therefore, it is possible to send unburned hydrogen to the catalyst 62 by injecting hydrogen in the exhaust stroke. Become. That is, when hydrogen is injected on the intake passage 12 side, hydrogen is injected during the intake stroke in which the intake valve 34 is open, and unburned hydrogen is sent to the catalyst 62 via the combustion chamber 28. When hydrogen is directly injected into the cylinder, unburned hydrogen can be sent to the exhaust passage 14 as it is if hydrogen is injected in the exhaust stroke.

  Since the hydrogen injected in the exhaust stroke is not involved in combustion in the cylinder, it is sent to the exhaust passage 14 as it is. Therefore, the amount of hydrogen sent to the exhaust passage 14 can be controlled more accurately by injecting hydrogen into the cylinder during the exhaust stroke.

  On the other hand, since the operation mode of the second embodiment is the same as that of the first embodiment as described above, the operation is performed in the hydrogenation combustion mode in the idling to normal rotation range. Accordingly, hydrogen is injected in the exhaust stroke for warming up the catalyst, and hydrogen is injected for combustion in the cylinder in the intake stroke or compression stroke.

  FIG. 5 is a timing chart showing the relationship between in-cylinder pressure, valve timing, and hydrogen injection timing and crank angle. FIG. 5 (A) shows in-cylinder pressure, FIG. 5 (B) shows valve timing, 5 (C) indicates the hydrogen injection timing. As shown in FIG. 5A, an explosion stroke is performed every 720 ° of the crank angle, and the in-cylinder pressure rapidly rises during the explosion stroke. As shown in FIG. 5B, the exhaust valve 36 is opened in the exhaust stroke after the explosion stroke, and the intake valve 34 is opened in the subsequent intake stroke.

  As shown in FIG. 5C, in the system of the second embodiment, hydrogen is injected from the hydrogen fuel in-cylinder injection valve 66 in order to warm up the catalyst in the exhaust stroke. In the intake stroke, hydrogen is injected from the hydrogen fuel in-cylinder injection valve 66 in order to perform lean burn in the hydrogen addition combustion mode. Therefore, in the system of the present embodiment, hydrogen injection is performed twice during one cycle of a single cylinder. Thereby, the hydrogen injected in the exhaust stroke can be directly sent to the exhaust passage 14 and combusted on the catalyst 62 side, and the catalyst can be warmed up instantaneously. Further, since the internal combustion engine 10 can be operated in the hydrogenation combustion mode together with the catalyst warm-up, the fuel consumption and emission can be improved.

  In FIG. 5, hydrogen injection is performed twice in one cycle, but hydrogen injection in the exhaust stroke and hydrogen injection in the intake stroke may be performed continuously. FIG. 6 is a timing chart showing a case where hydrogen is continuously injected from the exhaust stroke to the intake stroke.

  In this case, of the continuously injected hydrogen, the hydrogen injected in the exhaust stroke flows mainly to the exhaust passage 14 side and burns on the catalyst 62. Further, since the hydrogen injected in the intake stroke burns in the next combustion stroke, it mainly contributes to combustion in the cylinder. Thus, by injecting hydrogen continuously from the exhaust stroke to the intake stroke, hydrogen can be burned on the catalyst 62 and hydrogen can be burned in the cylinder. Therefore, it is possible to simplify the control of hydrogen injection.

  When gasoline is injected in the exhaust stroke, the in-cylinder temperature during the exhaust stroke is relatively low, so the gasoline adheres to the cylinder inner wall surface. Therefore, even if gasoline is injected into the cylinder in the exhaust stroke, the catalyst cannot be warmed up efficiently. However, since hydrogen, which is a gaseous fuel, does not adhere to the inner wall surface of the cylinder, it is possible to reliably send hydrogen onto the catalyst 62 by injecting hydrogen into the cylinder during the exhaust stroke.

  In the system of the second embodiment, it is possible to inject hydrogen from the hydrogen fuel in-cylinder injection valve 66 even in the compression stroke. Therefore, hydrogen may be injected during the compression stroke for combustion in the cylinder. In this case, the hydrogen injection pressure is set to be higher than the in-cylinder pressure.

  Next, a processing procedure in the system of this embodiment will be described based on the flowchart of FIG. First, in step S11, the catalyst bed temperature Tcat is acquired from the output of the catalyst bed temperature sensor 64. In the next step S12, the catalyst bed temperature Tcat and the catalyst activation temperature T0 are compared to determine whether or not Tcat <T0.

  If Tcat <T0 in step S12, the process proceeds to step S13. In this case, since the current catalyst bed temperature Tcat has not reached the catalyst activation temperature T0, the catalyst 62 needs to be warmed up. Accordingly, in step S13, hydrogen is injected from the hydrogen fuel cylinder injection valve 66 in the exhaust stroke.

  Thereby, the hydrogen injected from the hydrogen fuel in-cylinder injection valve 66 is sent to the exhaust passage 14 as it is, and burns in the vicinity of the inside of the catalyst 62. Since the combustion temperature of hydrogen is much higher than that of gasoline, it is possible to instantly warm up the catalyst 62 by burning unburned hydrogen on the catalyst 62. Therefore, the catalyst 62 can reach the activation temperature in a very short time.

  On the other hand, if Tcat ≧ T0 in step S12, the catalyst bed temperature Tcat at the present time has reached the catalyst activation temperature T0, so there is no need to warm up the catalyst 62. Therefore, in this case, the process is terminated (RETURN).

  After step S13, the process returns to step S12 to determine whether or not the catalyst bed temperature Tcat has reached the catalyst activation temperature T0. If the catalyst bed temperature Tcat has not reached the catalyst activation temperature T0, the process of step S13 is performed again. If the catalyst bed temperature Tcat has reached the catalyst activation temperature T0, the process is terminated (RETURN).

  As described above, according to the second embodiment, in the system including the hydrogen fuel in-cylinder injection valve 66 that directly injects hydrogen into the cylinder, the hydrogen is injected in the exhaust stroke. It can flow to the exhaust passage 14. Accordingly, hydrogen can be burned on the catalyst 62, and the temperature of the catalyst 62 can be instantaneously increased. Thereby, it is possible to greatly improve the emission at the time of starting the engine. In addition, since the operation in the hydrogen addition combustion mode can be performed by injecting hydrogen from the hydrogen fuel in-cylinder injection valve 66 in the intake stroke, the catalyst warm-up performance by the exhaust stroke injection and the fuel consumption by the intake stroke injection are improved. Both emission improvement can be achieved.

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 schematic diagram for demonstrating the operation mode of the system of each embodiment of this invention. 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 timing chart showing the timing of hydrogen injection in the second embodiment. 6 is a timing chart showing the timing of hydrogen injection in the second embodiment. 10 is a flowchart illustrating a processing procedure in the system according to the second embodiment.

Explanation of symbols

38 Gasoline injection valve 40 Hydrogen fuel port injection valve 66 Hydrogen fuel in-cylinder injection valve 70 ECU

Claims (6)

A hydrogenated internal combustion engine that uses hydrogen gas as a combustion fuel together with a hydrocarbon fuel,
A hydrocarbon fuel injection valve for injecting hydrocarbon fuel into the intake passage or the cylinder;
A hydrogen injection valve for injecting hydrogen gas into the intake passage or the cylinder;
A hydrogen injection amount increasing means for increasing the injection amount of hydrogen gas as compared with the normal time when the catalyst is warmed up;
A hydrogenated internal combustion engine comprising:   2. The hydrogen-added internal combustion engine according to claim 1, wherein the hydrogen injection amount increasing means increases the addition ratio of hydrogen gas to the hydrocarbon fuel when the catalyst is warmed up as compared with the normal time.   3. The hydrogen-added internal combustion engine according to claim 1, wherein the hydrogen injection valve is an injection valve that directly injects hydrogen gas into a cylinder, and injects hydrogen gas in an intake stroke or a compression stroke and an exhaust stroke. .   The hydrogenated internal combustion engine according to claim 3, wherein hydrogen gas is continuously injected from an intake stroke or a compression stroke to an exhaust stroke.   The hydrogenated internal combustion engine according to any one of claims 1 to 4, wherein only hydrogen gas is supplied as a fuel for combustion when the catalyst is warmed up.   6. The hydrogen-added internal combustion engine according to claim 1, wherein after the catalyst temperature reaches a predetermined temperature, the injection amount of hydrocarbon fuel is increased and the injection amount of hydrogen gas is decreased.

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