JP4470838B2 - Control device for hydrogen engine - Google Patents

Description

  The present invention relates to a control device for a hydrogen engine using gaseous hydrogen as fuel.

  As is well known, exhaust gases emitted from automobile engines contain air pollutants such as NOx (nitrogen oxide), CO (carbon monoxide), and HC (hydrocarbon). In order to purify the exhaust gas, an exhaust gas purification device using a catalyst is provided in the exhaust system. Normally, the catalyst used in this apparatus cannot fully exert its purifying power unless its temperature reaches a predetermined activation temperature. Therefore, when the engine is cold started, an air pollutant is not obtained. In order to reduce the discharge amount of the catalyst, it is necessary to quickly increase the catalyst temperature.

Conventionally, as one method for increasing the catalyst temperature in the exhaust gas purification device, it is known to retard the ignition timing and raise the exhaust gas temperature. For example, Patent Document 1 intends to reduce the exhaust amount of all hydrocarbons while raising the exhaust gas temperature at the start and appropriately warming up the catalyst, and retarding the ignition timing at the start of the engine to raise the exhaust gas temperature. In an internal combustion engine that performs the above, a catalyst temperature raising apparatus for an internal combustion engine is disclosed in which hydrogen is added to gasoline as a main fuel when the exhaust gas temperature is raised.
JP 2005-48631 A

  By the way, in recent years, for the purpose of reducing pollution, development of a vehicle equipped with an engine that uses only gaseous fuel such as compressed natural gas, liquefied petroleum gas, and compressed hydrogen has been developed. Also in the hydrogen engine to be used, it is desirable to quickly increase the temperature of the catalyst in the exhaust gas purification device and activate the catalyst quickly, particularly at the time of cold start.

  However, in a hydrogen engine, control is usually performed so that the air / fuel ratio is set to a leaner side than the stoichiometric air / fuel ratio in order to suppress NOx emissions. Under such control, the catalyst temperature rises during idle operation after startup. However, it takes time to activate the catalyst. If the running is started in a state where the catalyst temperature does not rise and the catalyst is not warmed up, the catalyst is not properly purified and a large amount of NOx is discharged.

  On the other hand, as described above, the ignition timing is retarded to raise the exhaust gas temperature, whereby the catalyst temperature can be raised and the activation of the catalyst can be accelerated. It becomes difficult to suppress NOx emissions in the machine.

  The present invention has been made in view of the above technical problem, and provides a control device for a hydrogen engine that can achieve early activation of a catalyst that purifies exhaust gas while suppressing NOx emissions. Objective.

  For this reason, the invention according to claim 1 of the present application is provided with an exhaust gas purification means that is disposed in the engine exhaust system and purifies the exhaust gas with a catalyst, and an EGR means that recirculates part of the exhaust gas to the intake system. In the control apparatus for a hydrogen engine, a temperature detection means for detecting a temperature related to the temperature of the catalyst of the exhaust gas purification means, and an air-fuel ratio control means for controlling the air-fuel ratio of the engine, which are theoretically operated under predetermined conditions. Air-fuel ratio control means for controlling the air-fuel ratio to be substantially zero on the lean side of the air-fuel ratio and EGR control means for controlling the recirculation operation of the EGR means, and the temperature detection means When the temperature of the catalyst of the exhaust gas purification means determined based on the detected temperature is lower than a predetermined activation temperature, the air / fuel ratio control means corrects the air / fuel ratio to be richer than the stoichiometric air / fuel ratio. Moni, in which the EGR control means is characterized in that to perform a reflux operation in the EGR unit.

  The invention according to claim 2 of the present application further includes ignition timing control means for controlling the ignition timing of the engine in the invention according to claim 1, and the ignition timing control means includes the exhaust gas purification means. When the temperature of the catalyst is lower than a predetermined activation temperature, the ignition timing of the engine is retarded by a predetermined amount.

  Further, the invention according to claim 3 of the present application is the invention according to claim 1 or 2, wherein the air-fuel ratio control means sets the air-fuel ratio richer than the stoichiometric air-fuel ratio based on the temperature of the catalyst of the exhaust gas purification means. The EGR control means adjusts the EGR rate of the EGR means so that the NOx emission amount is suppressed according to the enrichment degree corrected by the air-fuel ratio control means. It is characterized by controlling.

  The invention according to claim 4 of the present application is the invention according to claim 2 or 3, wherein the ignition timing control means corrects the retard amount of the ignition timing based on the temperature of the catalyst of the exhaust gas purification means. Accordingly, the EGR control means controls the EGR rate of the EGR means so that the NOx emission amount is suppressed according to the retard amount of the ignition timing corrected by the ignition timing control means. Is.

According to the invention of claim 1 of the present application, when the temperature of the catalyst of the exhaust gas purification means is lower than the predetermined activation temperature, the exhaust gas temperature is raised by the enrichment of the air-fuel ratio, and the catalyst is activated early. In addition, by executing EGR, the NOx emission amount can be suppressed, and as a result, both early activation of the catalyst and suppression of the NOx emission amount can be achieved.
In particular, in a hydrogen engine, the ignitability of gaseous hydrogen, which is a fuel, is good, so that the ignitability of the fuel can be ensured even when EGR is performed when the catalyst is in a low temperature state, and the above effects are more effectively achieved. be able to.

  Further, according to the invention of claim 2 of the present application, basically the same effect as that of the invention of claim 1 can be obtained. In addition, when the temperature of the catalyst of the exhaust gas purification means is lower than the predetermined activation temperature, the ignition timing is retarded, so that the increase of the exhaust gas temperature can be promoted, and further early activation of the catalyst is achieved. be able to.

  Furthermore, according to the invention of claim 3 of the present application, basically the same effect as that of the invention according to claim 1 or 2 can be obtained. In addition, as the air-fuel ratio is corrected from the stoichiometric air-fuel ratio to a richer side with a predetermined enrichment degree based on the temperature of the catalyst of the exhaust gas purification means, the NOx emission amount is increased according to the corrected enrichment degree. Since the EGR rate is controlled so as to be suppressed, it is possible to suppress an increase in NOx emission by executing EGR while suppressing adverse effects on the ignitability of fuel accompanying the execution of EGR, making the above effect more effective. Can play.

  Furthermore, according to the invention of claim 4 of the present application, basically the same effect as that of the invention according to claim 2 or 3 can be obtained. In addition, as the ignition timing retard amount is corrected based on the catalyst temperature of the exhaust gas purification means, the EGR rate is adjusted so that the NOx emission amount is suppressed according to the corrected ignition timing retard amount. Since it is controlled, an increase in the NOx emission amount can be suppressed by the EGR execution while suppressing an adverse effect on the ignitability of the fuel accompanying the EGR execution, and the above effect can be more effectively achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram schematically showing a rotary type hydrogen engine according to an embodiment of the present invention.
The hydrogen engine 1 includes a rotor housing H ₁ having a trochoidal inner peripheral surface and a substantially flat side housing H ₂ that extends along the planar direction of the rotor R as an outer configuration. . In a state where the housings H ₁ and H ₂ are combined and the rotor R is housed in an internal space formed inside the housings H ₁ and H ₂ , the inner surface of the rotor housing H ₁ , the side housing H ₂ , Thus, three working chambers E are defined.
Each working chamber E repeatedly expands and contracts its working volume as the rotor R rotates about the eccentric axis C, and during each rotation of the rotor R, each working chamber E has an intake stroke, a compression stroke, and an expansion stroke. A series of strokes consisting of a stroke and an exhaust stroke is performed.

In the rotor housing H ₁ is a hydrogen injector 10 which injects directly into gaseous hydrogen into the working chamber E, a spark plug 2 for igniting the air-fuel mixture consisting of the gas supplied hydrogen and air to the working chamber E Is provided. On the other hand, the side housing H ₂ is formed with an intake port 4 communicating with the intake passage 3 and an exhaust port 6 communicating with the exhaust passage 5.

  The intake passage 3 is provided with a throttle valve 25 for restricting air, and the exhaust passage 5 is provided with an exhaust gas purification device 7 for purifying exhaust gas. In the exhaust gas purification device 7, as a catalyst for purifying the exhaust gas, for example, a three-way catalyst that simultaneously purifies NOx, CO, and HC at once is used.

  In the present embodiment, as a configuration for realizing exhaust gas recirculation (EGR), an EGR passage 8 is provided between the intake passage 3 and the exhaust passage 5, and the EGR passage 8 includes an EGR passage 8. An EGR valve 9 that controls the gas flow rate and an EGR cooler 11 that cools the EGR gas are interposed. By opening the EGR valve 9, a part of the exhaust gas in the exhaust passage 5 is recirculated to the intake passage 3 through the EGR passage 8, supplied into the working chamber E of the hydrogen engine 1, and recombusted. . The EGR control described below represents the control of the EGR rate by controlling the opening degree of the EGR valve 9.

FIG. 2 is an explanatory diagram conceptually showing the hydrogen engine 1 and the configuration related thereto. As shown in this figure, the hydrogen injector 10 is provided with a solenoid valve V _1, the fuel injection hydrogen injector 10 is controlled based on the opening and closing operation of the electromagnetic valve V _1. In FIG. 2, to hydrogen injector 10, but the solenoid valve V ₁ is shown separately provided, actually an electromagnetic valve V ₁ was built into the interior of the hydrogen injector 10. Further, as shown in FIG. 2, in the present embodiment, a water temperature sensor 20 for detecting the engine water temperature, an engine speed sensor 21 for detecting the engine speed, an ignition switch ( And a starter 22 that is driven by cranking the hydrogen engine 1 is provided.

  In the intake passage 3, an air amount sensor 23 for detecting the intake air amount and an actuator 24 are used to correct the increase / decrease in the amount of air supplied to the working chamber so that the idling engine speed matches the target engine speed during idling. On the other hand, a throttle valve 25 is provided that is controlled to open and close in accordance with the amount of depression of an accelerator pedal (not shown) during non-idling. On the other hand, the exhaust passage 5 is provided with an oxygen concentration sensor 26 that detects the oxygen concentration in order to calculate the air-fuel ratio λ in the working chamber, upstream of the exhaust gas purification device 7.

  Further, the hydrogen injector 10 is connected via a hydrogen supply passage 30 to a hydrogen storage tank 31 that stores gaseous hydrogen as fuel in the hydrogen injector 10. The discharge port of the hydrogen storage tank 31 is provided with a stop valve 32 that is controlled to be opened and closed in order to control the hydrogen discharge from the hydrogen storage tank 31 to the hydrogen supply passage 30. A shutoff valve 33 for controlling the hydrogen supply to the hydrogen injector 10 is provided in the hydrogen supply passage 30. In the hydrogen supply passage 30, a pressure sensor 34 for detecting the hydrogen pressure in the hydrogen supply passage 30 is provided between the shut-off valve 33 and the hydrogen injector 10.

  Although not particularly shown, the configuration related to the hydrogen engine 1 is not limited to the above, such as an air cleaner provided in the intake passage 3, a throttle opening sensor for detecting the opening of the throttle valve 25, and an exhaust temperature sensor. A configuration is provided.

  Furthermore, as shown in FIG. 2, a control unit 40 is provided for controlling the hydrogen engine 1 and related components. The control unit 40 is a comprehensive control device for the hydrogen engine 1, and the intake air amount detected by the air amount sensor 23, the throttle opening detected by the throttle opening sensor, and the exhaust detected by the exhaust temperature sensor. The temperature, the engine water temperature detected by the water temperature sensor 20, the engine speed detected by the engine speed sensor 21, the starter signal from the starter 22 for detecting the start of the hydrogen engine 1, and the pressure sensor 34. Based on various control information such as the hydrogen pressure in the hydrogen supply passage 30, various controls such as air-fuel ratio control, EGR control, and ignition timing control, which will be described later, are performed. Note that the control unit 40 includes a microcomputer as a main part.

  In the hydrogen engine 1 having the above-described configuration, basically, control for setting the air-fuel ratio leaner than the stoichiometric air-fuel ratio is performed in order to suppress the NOx emission amount. Conventionally, under such control, there has been a problem that, for example, during the cold start, the catalyst temperature hardly rises and the catalyst cannot be activated quickly. When the temperature of the catalyst used in the gas purification device 7 is lower than a predetermined activation temperature, the air-fuel ratio is corrected to the rich side from the stoichiometric air-fuel ratio, and the NOx emission amount that increases as the air-fuel ratio becomes rich is reduced. Therefore, this problem is solved by controlling the EGR according to the NOx emission amount. In the present embodiment, the temperature of the catalyst used in the exhaust gas purification device 7 is estimated based on the engine water temperature detected by the water temperature sensor 20.

Hereinafter, the control of the air-fuel ratio and EGR executed for the hydrogen engine 1 will be described in detail.
FIG. 3 is a graph showing changes in the catalyst temperature and NOx emission concentration after the cold start for the hydrogen engine 1. In FIG. 3, the upper graph shows the change in the catalyst temperature with time after the cold start, while the lower graph shows the change in the NOx emission concentration after the cold start. Further, in FIG. 3, the case where the air-fuel ratio leaner than the stoichiometric air-fuel ratio that causes lean combustion (Comparative Example A) is indicated by a one-dot chain line, and a predetermined air-fuel ratio richer than the stoichiometric air-fuel ratio or stoichiometric air-fuel ratio is shown. When the air-fuel ratio (for example, the stoichiometric air-fuel ratio) is set (Comparative Example B) is represented by a solid line, and in this embodiment, a predetermined air-fuel ratio richer than the stoichiometric air-fuel ratio is set and EGR is executed. The case (this embodiment) is represented by a broken line. Further, in the upper graph, the activation temperature of the catalyst is represented by a two-dot chain line.

  When the hydrogen engine 1 is set to an air-fuel ratio leaner than the stoichiometric air-fuel ratio at the time of cold start (Comparative Example A), lean combustion is performed, and as shown by the one-dot chain line in FIG. Although the exhaust concentration is low, the catalyst temperature rises slowly after the cold start. That is, it takes a long time for the catalyst to reach a predetermined activation temperature.

Further, in the hydrogen engine 1, when the stoichiometric air-fuel ratio or an air-fuel ratio richer than the stoichiometric air-fuel ratio is set at the time of cold start (Comparative Example B), as shown by the solid line in FIG. increase in the catalyst temperature after starting is performed at an early stage, the catalyst temperature reaches a predetermined activation temperature at the elapsed time t _1. For this reason, after the elapsed time t ₁ , the NOx emission concentration is greatly reduced by the catalyst, and becomes lower than in the case of the lean combustion. However, in this case remains high NOx exhaust concentration by enrichment of the air-fuel ratio until the elapsed time t _1. Thus, by setting the air-fuel ratio richer than the stoichiometric air-fuel ratio, the catalyst temperature can be quickly raised to a predetermined activation temperature, but the NOx emission concentration depends on the degree of enrichment of the air-fuel ratio. Will increase.

On the other hand, in the present embodiment, in the hydrogen engine 1, a stoichiometric air-fuel ratio or an air-fuel ratio richer than the stoichiometric air-fuel ratio is set at the cold start, and NOx emission that increases as the air-fuel ratio becomes richer To reduce the concentration, EGR is performed. In this case, as indicated by a broken line, the time until the catalyst temperature reaches a predetermined activation temperature (time) as compared with the case where EGR is not executed at the stoichiometric air-fuel ratio or an air-fuel ratio richer than the stoichiometric air-fuel ratio. Although t ₂ ) is a little longer, the NOx emission amount until the predetermined activation temperature is reached can be significantly reduced by executing EGR.

  As described above, in the hydrogen engine 1, the NOx emission that increases as the air-fuel ratio becomes richer by correcting to the stoichiometric air-fuel ratio or an air-fuel ratio richer than the stoichiometric air-fuel ratio during cold start and executing EGR. The amount can be reduced, and the catalyst temperature can be activated at an early stage while suppressing the deterioration of the NOx emission amount.

  In the present embodiment, in the hydrogen engine 1, in addition to the enrichment of the air-fuel ratio, the catalyst is further activated at the time of cold start, and the ignition timing is retarded. By retarding the ignition timing, the exhaust gas temperature can be further increased, and as a result, the catalyst is activated early. In this case, the retard amount of the ignition timing is controlled according to the engine temperature. FIG. 4 is a map showing the relationship between the engine temperature and the retard amount of the ignition timing. The control unit 40 changes the retard amount of the ignition timing according to the engine temperature based on the engine water temperature detected by the water temperature sensor 20 based on the map shown in FIG. Thereby, the retard amount of the ignition timing is set to be larger as the engine temperature is lower, and the retard amount of the ignition timing is set to be smaller as the engine temperature is higher.

  Along with the change in the retard amount of the ignition timing according to the engine temperature, the NOx emission amount changes. Specifically, when the ignition timing retard amount is large, combustion slows down and the combustion temperature decreases, so the NOx emission amount is small. On the other hand, when the ignition timing retard amount is small, the combustion does not occur so much after combustion. Since the temperature does not decrease, the amount of NOx emissions increases.

  In the present embodiment, the EGR rate is further controlled in response to the increase in the NOx emission amount accompanying the ignition timing retard control. FIG. 5 is an example of a map showing the relationship between the ignition timing retard amount and the EGR rate. The control unit 40 changes the EGR rate according to the ignition timing retard amount based on the map shown in FIG. As a result, the smaller the ignition timing retard amount, the larger the NOx emission amount. Therefore, the EGR rate is set larger. The larger the ignition timing retard amount, the smaller the NOx emission amount, so the EGR rate is set smaller.

  Thus, in the present embodiment, further early activation of the catalyst at the time of cold start is attempted, the ignition timing is retarded, and the EGR rate is controlled according to the retard amount. An increase in NOx emissions accompanying ignition timing retard is avoided.

  FIG. 6 is a flowchart of the control process of the hydrogen engine 1 according to this embodiment. In this process, first, signals detected by the configuration related to the hydrogen engine 1 shown in FIG. 2, that is, various signals representing engine water temperature, engine speed, intake air amount, throttle opening, etc. are read (step #). 1). Next, in step # 2, the hydrogen injection amount supplied to the working chamber E is set according to the operating state of the engine, that is, according to the engine speed and the engine load based on the signal. In step # 3, the ignition timing by the spark plug 2 is set according to the operating state.

  When the hydrogen injection amount and the ignition timing are set in steps # 2 and # 3, it is determined in step # 4 whether or not the hydrogen engine 1 is in a starting state. That is, it is determined by the starter 22 whether cranking is in progress. If the determination result in step # 4 is yes (YES), that is, if the hydrogen engine 1 is in the starting state, it is determined whether or not the engine water temperature detected by the water temperature sensor 20 is higher than the predetermined temperature α. (Step # 5). The predetermined temperature α is set according to the activation temperature of the catalyst used in the exhaust gas purification device 7, that is, in step # 5, the temperature of the catalyst used in the exhaust gas purification device 7. Is higher than its activation temperature.

  If the determination result in step # 5 is YES, that is, if the engine water temperature is higher than the predetermined temperature α, the air-fuel ratio is set to a leaner side than the stoichiometric air-fuel ratio, and lean combustion is performed (step # 6). In this embodiment, the NOx emission amount is set to a leaner air-fuel ratio (λ = 2) than the stoichiometric air-fuel ratio at which the NOx emission amount is substantially near zero.

  On the other hand, if the determination result in step # 5 is no (NO), that is, if the engine water temperature is equal to or lower than the predetermined temperature α, in step # 7, the ignition timing is set to the ignition timing set in step # 3. It is corrected so as to be retarded. The retard amount of the ignition timing is set to be larger as the engine water temperature is lower based on the map shown in FIG.

  Further, in step # 8, the air-fuel ratio is enriched (that is, the air-fuel ratio is corrected so as to become a richer air-fuel ratio than the stoichiometric air-fuel ratio). In this embodiment, for example, when the air-fuel ratio is enriched, the air-fuel ratio is corrected to λ = 1. However, the present invention is not limited to this, and the degree of enrichment of the air-fuel ratio is changed according to the engine water temperature. May be.

In steps # 7 and # 8, if the ignition timing is retarded and the air-fuel ratio is enriched according to the engine water temperature, the NOx emission amount can increase. Therefore, in step # 9, in order to suppress the NOx emission amount EGR is performed. As the EGR is executed, the EGR rate is corrected according to at least one of the ignition timing retard amount corrected in step # 7 and the air-fuel ratio enrichment degree corrected in step # 8. Specifically, with respect to the ignition timing retard amount, the larger the ignition timing retard amount, the larger the EGR rate is set. .
When the catalyst activation control for activating the catalyst in steps # 7 to # 9 is executed, the flag (Flag) is set to “1” in step # 10.

  If the determination result in step # 4 is YES, as shown in steps # 5 to # 10 according to the control flowchart of FIG. 6, lean combustion is performed at the time of warm start when the engine water temperature is equal to or higher than a predetermined temperature, At the time of cold start when the engine water temperature is equal to or lower than the predetermined temperature, EGR is executed along with retarding the ignition timing and enriching the air-fuel ratio. On the other hand, if the determination result in step # 4 is NO, that is, the hydrogen engine 1 If is not in the starting state, it is subsequently determined in step # 11 whether or not the flag is “1”.

  If the determination result in step # 11 is YES, that is, if the flag is “1”, control for activating the catalyst is performed, and in step # 12, within a predetermined period after the engine is started. It is determined whether or not there is. If the determination result in step # 12 is YES, that is, within a predetermined period after the start, EGR is executed together with the ignition timing retard and air-fuel ratio enrichment as shown in steps # 7 to # 10. The flag “1” is continued.

  On the other hand, if the determination result in step # 12 is NO, that is, if it is not within a predetermined period after startup, the catalyst activation control execution flag is reset to “0” and normal control is performed (step # 13). Similarly, if the determination result in step # 11 is NO, that is, if the flag is not “1”, normal control is performed in step # 13. In the present embodiment, as the normal control, the air-fuel ratio is set to the stoichiometric air-fuel ratio and EGR is executed. In addition, it is not limited to this, Other control may be performed.

As is apparent from the above description, according to the present embodiment, when the temperature of the catalyst used in the exhaust gas purification device 7 is lower than the predetermined activation temperature, the air-fuel ratio becomes richer than the stoichiometric air-fuel ratio. By correcting, the exhaust gas temperature can be raised, and in addition to the enrichment of the air-fuel ratio, the EGR is executed to suppress the NOx emission amount that increases with the enrichment of the air-fuel ratio. Therefore, it is possible to achieve both suppression of NOx emission and early activation of the catalyst.
In particular, in a hydrogen engine, the ignitability of gaseous hydrogen, which is a fuel, is good. Therefore, even when EGR is performed when the temperature of the catalyst used in the exhaust gas purification device 7 is in a low temperature state, the ignitability of the fuel is ensured. And the above effect can be more effectively achieved.

  Further, according to the present embodiment, when the temperature of the catalyst used in the exhaust gas purification device 7 is lower than a predetermined activation temperature, the ignition timing is retarded, so that the exhaust gas temperature can be further increased. Further early activation of the catalyst can be achieved.

  Furthermore, according to the present embodiment, the EGR rate is controlled so as to suppress the NOx emission amount according to at least one of the richness of the air-fuel ratio and the ignition timing retard amount corrected based on the temperature related to the temperature of the catalyst. By being controlled, it is possible to avoid an increase in the NOx emission amount while suppressing an adverse effect on the ignitability of the fuel accompanying the execution of EGR.

  It should be noted that the present invention is not limited to the illustrated embodiment, and it goes without saying that various improvements and design changes can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the rotary engine is exemplified as the hydrogen engine 1, but the present invention can be similarly applied to other types of engines such as a reciprocating engine. In the above-described embodiment, the hydrogen engine 1 is exemplified by the engine including the direct injection type hydrogen injector 10. However, the present invention is not limited thereto, and the present invention includes a premixed type hydrogen injector. The present invention can be similarly applied to other types of engines such as an engine.

  The present invention is a control device for a hydrogen engine provided with a hydrogen injector for supplying hydrogen, and can be suitably applied to a device equipped with the hydrogen engine, such as a vehicle such as an automobile.

It is explanatory drawing which shows roughly the rotary type hydrogen engine which concerns on embodiment of this invention. It is explanatory drawing which shows notionally the said hydrogen engine and the structure relevant to it. It is a graph showing the change of the catalyst temperature after a cold start regarding a hydrogen engine, and a NOx discharge concentration. It is an example of the map showing the relationship between the engine temperature and the retard amount of the ignition timing. It is an example of the map showing the relationship between the retard amount of ignition timing and the EGR rate. It is a flowchart regarding the control processing of the hydrogen engine which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hydrogen engine 3 Intake passage 5 Exhaust passage 7 Exhaust gas purification device 8 EGR passage 9 EGR valve 10 Hydrogen injector 20 Water temperature sensor 26 Oxygen concentration sensor 30 Control unit

Claims (4)

In a control device for a hydrogen engine, provided in an engine exhaust system, comprising exhaust gas purification means for purifying exhaust gas with a catalyst, and EGR means for recirculating a part of the exhaust gas to the intake system,
Temperature detection means for detecting a temperature related to the temperature of the catalyst of the exhaust gas purification means;
An air-fuel ratio control means for controlling the air-fuel ratio of the engine, the air-fuel ratio control means for controlling the air-fuel ratio to be substantially zero on the lean side of the stoichiometric air-fuel ratio under a predetermined condition so that the NOx emission amount becomes substantially zero;
EGR control means for controlling the reflux operation of the EGR means,
When the temperature of the catalyst of the exhaust gas purification means determined based on the temperature detected by the temperature detection means is lower than a predetermined activation temperature, the air-fuel ratio control means brings the air-fuel ratio to a richer side than the stoichiometric air-fuel ratio. A hydrogen engine control apparatus characterized by correcting and causing the EGR control means to cause the EGR means to perform a reflux operation.   Ignition timing control means for controlling the ignition timing of the engine is further provided. When the temperature of the catalyst of the exhaust gas purification means is lower than a predetermined activation temperature, the ignition timing control means sets the ignition timing of the engine by a predetermined amount. The hydrogen engine control device according to claim 1, wherein retarding is performed.   As the air-fuel ratio control unit corrects the air-fuel ratio from the stoichiometric air-fuel ratio to a rich side based on the temperature of the catalyst of the exhaust gas purification unit, the EGR control unit performs the air-fuel ratio control. 3. The hydrogen engine control device according to claim 1, wherein the EGR rate of the EGR means is controlled so that the NOx emission amount is suppressed in accordance with the enrichment degree corrected by the means. 4. As the ignition timing control means corrects the ignition timing retard amount based on the catalyst temperature of the exhaust gas purification means, the EGR control means corrects the ignition timing retard amount corrected by the ignition timing control means. 4. The hydrogen engine control device according to claim 2, wherein the EGR rate of the EGR means is controlled so as to suppress NOx emission.

Images