JP4618150B2 - Control device for hydrogen engine - Google Patents

Description

  The present invention relates to a control device for a hydrogen engine.

  Conventionally, hydrogen engines using hydrogen gas as a fuel are known. This hydrogen engine has various problems different from those of a gasoline engine due to the nature of hydrogen gas, and one of them is pre-ignition. Pre-ignition means that when a mixture of hydrogen gas and air comes into contact with a high-temperature part in the combustion chamber, residual gas, high-temperature suspended matter, etc., they are ignited and ignited before ignition by the spark plug. This is because the air-fuel mixture explodes and the ignition energy of hydrogen is small and it is easy to ignite. When pre-ignition occurs, combustion gas may flow into the intake port at the beginning of the compression stroke (a state where the intake port is still slightly open), and backfire may occur if fuel is injected in the next cycle. Since this pre-ignition has a higher risk of occurring as the hydrogen concentration increases, it is difficult to enrich the air-fuel ratio, and as a result, the output cannot be increased.

For this reason, in the hydrogen engine, engine control in consideration of this pre-ignition has been conventionally performed. For example, in Patent Document 1, during low-power operation, hydrogen is directly injected during the intake stroke to reduce NOx, and combustion is performed. During high-power operation, hydrogen supplied during the intake stroke is burned to prevent pre-ignition. In addition, a hydrogen engine is disclosed in which fuel is directly supplied to perform combustion during combustion.
Japanese Patent Laid-Open No. 07-133731

  Incidentally, the supply of hydrogen in the hydrogen engine disclosed in Patent Document 1 is based on the intake stroke supply for supplying hydrogen during the intake stroke. When hydrogen and air are mixed during the intake stroke, there is a problem that the volumetric efficiency of the engine is reduced because hydrogen is a gaseous fuel and the output is reduced. Generally, the volumetric efficiency is poor in a low rotational speed region where the engine rotational speed is low. Therefore, if the intake stroke is supplied in the low rotational speed region, the volumetric efficiency is further reduced. Thus, in the hydrogen engine disclosed in Patent Document 1, the output performance is not sufficiently improved.

  Therefore, in order to solve this decrease in volumetric efficiency, a compression stroke supply for supplying hydrogen into the combustion chamber during the compression stroke is conceivable. However, in this compression stroke supply, the mixing (mixing) of hydrogen and air becomes insufficient, and the hydrogen in the combustion chamber tends to agglomerate. In the part where hydrogen agglomerates and the hydrogen concentration is locally high, pre-ignition is performed. Is likely to occur. Therefore, in the compression stroke supply, although the volumetric efficiency is improved, the air-fuel ratio cannot be enriched so much and the output performance cannot be sufficiently improved.

  This invention is made | formed in view of this point, The place made into the objective is to improve the output performance of a hydrogen engine, suppressing a pre-ignition.

  The present invention provides a compression stroke supply for supplying hydrogen during the compression stroke, an intake stroke supply for supplying hydrogen during the intake stroke, and an exhaust gas recirculation for returning the exhaust gas to the intake system in accordance with the engine speed. By using them properly, the output torque is improved while suppressing pre-ignition.

Specifically, the first invention provides a hydrogen supply means for supplying hydrogen, an intake stroke supply for supplying hydrogen to the hydrogen supply means during an intake stroke, and a hydrogen supply means for supplying hydrogen during a compression stroke. A control device for a hydrogen engine comprising control means for controlling the supply timing of hydrogen by switching and using in combination with compression stroke supply. Further, exhaust gas recirculation means for recirculating exhaust gas to the intake system is provided, and the control means compresses the hydrogen supply means with the compression in a first engine operating state where the engine rotational speed is less than a predetermined first rotational speed. The exhaust gas recirculation means causes the exhaust gas to recirculate to the intake system, and the engine rotational speed is equal to or higher than the first rotational speed and less than a predetermined second rotational speed that is higher than the first rotational speed. In the second engine operating state, the hydrogen supply means performs the intake stroke supply and the compression process supply, and the exhaust gas recirculation means causes the exhaust gas to recirculate to the intake system so that the engine rotation speed is the second rotation. in the above third engine operating state speed, the said hydrogen supply means to perform the intake stroke supply and the compression stroke supply, to said second engine operating condition The exhaust gas recirculation to the intake system by the exhaust gas recirculation means is performed only in a predetermined high load region, and the amount of exhaust gas recirculated at that time is recirculated in the first engine operating state. It shall be less than the amount of exhaust gas .

  In the first engine operating state, the engine rotational speed is slow, so volume efficiency is low in the first place. Thus, by supplying hydrogen by the compression stroke supply, the volume efficiency can be improved and the output can be improved.

  However, in the compression stroke supply, hydrogen may be agglomerated, and in such a case, pre-ignition may easily occur. Therefore, the exhaust gas is recirculated to the intake system by the exhaust gas recirculation means, so that the combustion temperature is lowered. As a result, the temperature rise in the combustion chamber can be suppressed, and pre-ignition can be suppressed. If pre-ignition can be suppressed in this way, the air-fuel ratio can be enriched accordingly, and the output can be further improved. By recirculating the exhaust gas, the combustion temperature can be lowered and the NOx emission amount can be suppressed.

  Thus, in the first engine operating state, exhaust gas recirculation can reduce the combustion temperature to suppress pre-ignition and improve the output by supplying the compression stroke.

  In the second engine operating state, the engine speed is higher than that in the first engine operating state, so that the time from when hydrogen is supplied until ignition is shortened. As a result, mixing of hydrogen supplied by the compression stroke supply deteriorates. Therefore, in the second engine operating state, not only the compression stroke supply but also the intake stroke supply is used in combination. When the intake stroke is supplied, the supplied hydrogen is sufficiently mixed with the air during the intake stroke, so that the mixing can be improved and the pre-ignition can be suppressed. In addition, the pre-ignition can be further suppressed by performing exhaust gas recirculation in the same manner as in the first engine operating state. Thus, if the pre-ignition can be suppressed, the air-fuel ratio can be made rich accordingly, and the output can be improved.

  Moreover, since the compression stroke supply is also used, the output can be further improved by improving the volume efficiency.

  Thus, in the second engine operating state, mixing can be improved by supplying the intake stroke, the combustion temperature can be lowered by recirculating the exhaust gas to suppress preignition, and output can be improved by supplying the compression stroke.

  In the third engine operating state, since the engine rotational speed is relatively fast and the combustion gas becomes high temperature, when the exhaust gas is recirculated by the exhaust gas recirculation means, the combustion chamber becomes high temperature and pre-ignition occurs. It becomes an easy environment. Further, in a state where the engine rotation speed is high, when the exhaust gas is recirculated, the air charging efficiency is greatly reduced, and the output may be reduced. Therefore, by stopping the exhaust gas recirculation by the exhaust gas recirculation means, the above adverse effects can be prevented. The supply of hydrogen is performed using both the intake stroke supply and the compression stroke supply. By doing so, as in the second engine operation state, mixing of hydrogen and air can be improved by supplying the intake stroke to suppress pre-ignition, and output can be improved by supplying the compression stroke. .

  Thus, in the third engine operating state, the exhaust gas recirculation is stopped to prevent the temperature in the combustion chamber from rising and the air charging efficiency from being lowered, and the intake stroke supply improves mixing and suppresses pre-ignition, Output can be improved by supplying a compression stroke.

  Thus, by properly using the intake stroke supply, the compression stroke supply, and the exhaust gas recirculation according to the engine speed, the output can be improved while suppressing pre-ignition in each engine operating state.

Further, if the exhaust gas recirculation amount is too large, the air charging efficiency may be adversely affected. Therefore, in the second engine operating state, since the pre-ignition is suppressed to some extent by the intake stroke supply, the exhaust gas recirculation is performed in the low load region where the risk of pre-ignition is low and the load is relatively low. The air filling efficiency is improved. In a high load state where the risk of pre-ignition in the second engine operation state is high and the load is relatively high, not only the combined use of the intake stroke supply and the compression stroke supply, but also the exhaust gas recirculation means by the exhaust gas recirculation means. By performing the reflux, the pre-ignition can be reliably suppressed. However, since the exhaust gas recirculation amount at this time is smaller than the exhaust gas recirculation amount in the first engine operating state, the influence on the air charging efficiency should be reduced as much as possible to prevent the output from decreasing. Can do.

  In a second aspect based on the first aspect, the control means is arranged such that the hydrogen supply means is in the fourth engine operating state in which the engine rotational speed is equal to or higher than a predetermined third rotational speed that is higher than the second rotational speed. It is assumed that only the intake stroke supply is performed.

In the case of the above-described configuration, the fourth engine operating state in which the engine rotational speed is equal to or higher than the third rotational speed is set, and in the fourth engine operating state, only the intake stroke supply is performed. That is, since the engine speed is relatively high in the fourth engine operating state, there is a possibility that hydrogen is not sufficiently mixed in the combustion chamber in the compression stroke supply in which hydrogen is supplied during the compression stroke, which is caused by a mixing failure. Increased risk of pre-ignition. Therefore, by supplying hydrogen only by the intake stroke supply without performing the compression stroke supply, the mixing can be improved and the pre-ignition can be suppressed .

According to a third invention, in the first or second invention, the distribution ratio between the intake stroke supply and the compression stroke supply in the third engine operating state is set to be higher as at least one of the engine rotational speed and the engine load is higher. The rate of process supply shall be increased.

  In the case of the above-described configuration, the higher the engine speed and the engine load, the more the air-fuel ratio must be enriched, and the combustion temperature also increases, so the risk of pre-ignition increases. Therefore, the pre-ignition can be reliably suppressed by increasing the ratio of the intake stroke supply with better mixing as the engine rotation speed and the engine load increase.

According to a fourth invention, in the first or second invention, the hydrogen supply means is direct injection supply means for supplying and supplying hydrogen directly into the combustion chamber.

  In the case of the above configuration, the intake stroke supply and the compression stroke supply can be realized by changing the supply timing of hydrogen by the direct injection supply means.

According to a fifth invention, in the first or second invention, the hydrogen supply means directly supplies the hydrogen into the combustion chamber by injecting hydrogen into the intake passage, and directly into the combustion chamber. Direct injection supply means for injecting and supplying hydrogen, and the control means causes the in-passage supply means to perform the intake stroke supply and causes the compression stroke supply to be performed to the direct injection supply means. .

  In the case of the above configuration, the hydrogen supplied into the intake passage by the supply means in the passage in the intake stroke supply is sufficiently mixed because there is a distance and time until it is supplied to the combustion chamber. As a result, pre-ignition can be reliably suppressed.

In a sixth aspect based on the second aspect, the hydrogen supply means includes direct injection supply means for supplying and supplying hydrogen directly into the combustion chamber, and hydrogen is injected into the intake passage to inject hydrogen into the combustion chamber. The supply means in the passage, and the control means causes the supply means in the passage to perform the intake stroke supply in the second and third engine operating states out of the intake stroke supply, In the four-engine operating state, the intake stroke supply is performed by both the direct injection supply means and the in-passage supply means, and the compression stroke supply is performed by the direct injection supply means.

  In the case of the above configuration, in the second and third engine operating states, the intake stroke supply is performed by the in-passage supply means, so that hydrogen and air can be sufficiently mixed. On the other hand, in the fourth engine operating state, the compression stroke supply is not performed in order to improve mixing, so that the effect of the compression stroke supply that the volumetric efficiency is high cannot be enjoyed. Therefore, the intake stroke supply by the direct injection supply means is used together with the intake stroke supply not only by the in-passage supply means excellent in mixing. Since the intake stroke supply by the direct injection supply means has higher volumetric efficiency than the intake stroke supply by the in-passage supply means, the pre-ignition can be ensured by using the intake stroke supply by the direct injection supply means together. The output can be improved as much as possible.

  According to the present invention, in the first engine operating state where the engine rotational speed is less than the first rotational speed, the combustion temperature is decreased due to the exhaust gas recirculation while improving the output by improving the volumetric efficiency by supplying the compression stroke. Therefore, the pre-ignition can be suppressed and the output can be further improved. Further, in the second engine operating state in which the engine rotation speed is equal to or higher than the first rotation speed and lower than the second rotation speed, the output is improved by improving the volume efficiency by the compression stroke supply, and the mixing by the intake stroke supply is performed. The output can be further improved by suppressing the pre-ignition by the improvement of the above and the reduction of the combustion temperature due to the exhaust gas recirculation. Further, in the third engine operating state in which the engine speed is equal to or higher than the second speed, the output is improved by improving the volumetric efficiency by supplying the compression stroke, and the mixing is improved by the intake stroke supply and the exhaust gas is recirculated. By preventing the temperature in the combustion chamber from rising due to the stop of the engine, the pre-ignition can be suppressed and the output can be further improved.

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

  FIG. 1 is a schematic view of an engine that employs a hydrogen engine control apparatus according to the present invention. Reference numeral 1 denotes a rotary engine. The rotary engine 1 is mounted on a vehicle such as an automobile and uses hydrogen as a fuel.

  The rotary engine 1 includes a rotor housing chamber (hereinafter referred to as a cylinder) 11 surrounded by a bowl-shaped rotor housing having a trochoid inner peripheral surface and a side housing, and a substantially triangular rotor 12 accommodated therein. In addition, three working chambers (combustion chambers) are defined on the outer peripheral side of the rotor 12. Although not shown, the rotary engine 1 is formed by integrating two rotor housings so as to be sandwiched between three side housings, and two cylinders 11 formed therebetween (in FIG. 1, one of them). 2 is a two-rotor type in which the rotor 12 is accommodated in each of the two.

  Each of the rotors 12 rotates while rotating around the eccentric shaft 13 in a state where seal portions respectively disposed at three tops of the outer periphery of the rotor 12 are in contact with the inner surface of the trochoid of the rotor housing. Revolves around 13 axes. Then, while the rotor 12 makes one revolution, the working chambers formed between the tops of the rotor 12 move in the circumferential direction to perform intake, compression, expansion (combustion), and exhaust strokes. Is generated from the eccentric shaft 13 via the rotor 12.

  In addition, the intake passage 2 communicates with each cylinder 11 so as to communicate with the working chamber in the intake stroke, and the exhaust passage 3 communicates with the working chamber in the exhaust stroke. The intake passage 2 is one on the upstream side, but is divided into two on the downstream side and communicates with the working chambers of the cylinders 11. Further, two exhaust passages 3 are provided on the upstream side so as to communicate with the working chambers of the respective cylinders 11, but are joined together on the downstream side.

  On the upstream side of the branch portion of the intake passage 2, the air cleaner 21 for purifying at least air (intake air) sucked into the intake passage 2 in order from the upstream side to the downstream side, and sucked into the intake passage 2. An air flow sensor 22 that detects the intake air flow rate, and a throttle valve 23 that is driven by an actuator such as a stepping motor to adjust the cross-sectional area (valve opening degree) of the intake passage 2 are disposed. The intake passage 2, the air cleaner 21, the air flow sensor 22, the throttle valve 23 and the like constitute an intake system.

  A three-way catalyst 31 as an exhaust purification catalyst for purifying exhaust gas is disposed at least downstream of the merging portion of the exhaust passage 3. The exhaust passage 3 and the three-way catalyst 31 constitute an exhaust system.

  A portion of the intake passage 2 that is upstream of the branch portion and downstream of the throttle valve 23, a portion of the exhaust passage 3 that is downstream of the junction and the three-way catalyst 31. The upstream portion is connected by an EGR passage 4, and a part of the exhaust gas is recirculated to the intake system as EGR gas by the EGR passage 4. In the EGR passage 4, an EGR cooler 41 for cooling the EGR gas and an EGR valve 42 for adjusting the amount of EGR gas returning to the intake passage 2 are arranged in order from the upstream side to the downstream side. ing. The EGR passage 4, the EGR cooler 41, and the EGR valve 42 constitute exhaust gas recirculation means that recirculates the exhaust gas of the engine 1 to the intake system of the engine 1.

  Each cylinder 11 of the rotary engine 1 is provided with two direct injection injectors 14a and 14b for directly injecting hydrogen supplied from a hydrogen tank (not shown) into the combustion chamber. The two direct injection injectors 14a and 14b are respectively arranged in the vicinity of the long axis of the rotor housing so that the injection holes for injecting hydrogen face the combustion chamber (in FIG. 1, the two direct injection injectors 14a, 14a, 14b are arranged side by side in the circumferential direction of the eccentric shaft 13, but this is for convenience of explanation, and is precisely arranged in the axial direction of the eccentric shaft 13). The positions where these direct injection injectors 14a and 14b are provided correspond to positions that open to the working chamber from the intake stroke to the compression stroke. These direct injection injectors 14a and 14b are supplied with hydrogen gas from a hydrogen tank (not shown) via a fuel supply passage. Each direct injection injector 14a (14b) is provided with a timing valve so that the amount of hydrogen gas to be injected can be freely controlled. Of these two direct injection injectors, one direct injection injector 14a is an intake stroke direct injection injector that injects hydrogen during the intake stroke, and the other direct injection injector 14b directly injects hydrogen during the compression stroke. This is a direct injection injector for the compression stroke.

  Further, an in-passage injector 15 for injecting hydrogen supplied from the above-described hydrogen tank into the intake passage 2 is disposed downstream of the branch portion of the intake passage 2 of the rotary engine 1. Similarly to the direct injection injectors 14a and 14b, the in-passage injector 15 is supplied with hydrogen gas from a hydrogen tank via a fuel supply passage, and the amount of hydrogen gas injected by an internal timing valve is reduced. It can be freely controlled. The in-passage injector 15 injects hydrogen into the intake passage 2 during the intake stroke, and supplies the hydrogen into the combustion chamber via the intake passage 2.

  That is, the rotary engine 1 has the intake stroke direct injection injector 14a and the in-passage injector 15 as hydrogen supply means for supplying intake stroke to supply hydrogen during the intake stroke, and supplies hydrogen during the compression stroke. A compression stroke direct injection injector 14b is provided as a hydrogen supply means for supplying the compression stroke.

  Here, each supply system will be further described. Since the intake stroke supply supplies hydrogen during the intake stroke, the hydrogen is easily mixed with the air sucked into the combustion chamber, and the mixing is good, while the sucked air decreases. Low volumetric efficiency. Although it is the same intake stroke injector, the intake stroke direct injection injector 14a is superior in volume efficiency to the in-passage injector 15, and the in-passage injector 15 is in comparison with the intake stroke direct injection injector 14a. Excellent in terms of mixing.

  In addition, since the compression stroke supply supplies hydrogen during the compression stroke, the volumetric efficiency is high, while the time to ignition is short and the flow of the air-fuel mixture is not as great as the intake stroke, so the mixing is poor.

  Each cylinder 11 of the rotary engine 1 is provided with two spark plugs 16, 16. The two spark plugs 16, 16 are respectively disposed near the minor axis of the rotor housing.

  The rotary engine 1 is provided with a power train control module (hereinafter referred to as PCM) 5 that controls the operation state of the rotary engine 1. The PCM 5 receives at least an engine rotation speed sensor 61 for detecting the engine rotation speed of the rotary engine 1 and an input signal from the air flow sensor 22, and at least the injectors 14a, 14b, 15 and the throttle valve 23. The control signals are output to the spark plugs 16 and 16 and the EGR valve 42 to control the operation thereof. That is, the PCM 5 selects an injector to be used from the injectors 14a, 14b, and 15 based on fuel injection control to be described later, and a predetermined amount of the selected injector at a predetermined timing according to the rotational position of the rotor 12. Inject hydrogen. That is, the PCM 5 constitutes a control means for controlling the hydrogen supply timing. Further, the PCM 5 adjusts the opening of the throttle valve 23 according to an output signal of an accelerator opening sensor (not shown). Further, the PCM 5 ignites each spark plug 16 at a predetermined timing according to the rotational position of the rotor 12. Furthermore, the PCM 5 controls the EGR valve 42 according to the engine operating state to adjust the amount of EGR gas that is recirculated to the intake system.

  Hereinafter, fuel supply control by the PCM 5 will be described using the flowchart of FIG. 2 and the fuel supply specification map of FIG. The fuel supply specification map of FIG. 3 is a map showing the injector to be used and the presence or absence of recirculation of exhaust gas, which are set according to the engine speed and the engine load. Note that the curve in FIG. 3 is the maximum output torque of the rotary engine 1 according to the present embodiment achieved by the following fuel supply control.

  First, in step S1, the engine rotational speed N detected by the engine rotational speed sensor 61 is less than a predetermined first rotational speed n1, or more than a first rotational speed n1, and a predetermined second rotational speed n2 (n2> n1). Or less than a second rotation speed n2 and less than a predetermined third rotation speed n3 (n3> n2), or a third rotation speed n3 or more.

  When the engine rotational speed N is less than the first rotational speed n1 (hereinafter referred to as the first engine operating state), in step S2, the compression stroke is supplied by the compression stroke direct injection injector 14b and the exhaust gas is recirculated. (Region I in FIG. 3). However, in the low load region, since the risk of pre-ignition is low, the exhaust gas is not recirculated, and only hydrogen supply is performed by the compression stroke direct injection injector 14b (region I 'in FIG. 3).

  Specifically, the PCM 5 determines the supply amount of hydrogen based on the detection value of the air flow sensor 22 so that the excess air ratio λ is 1.0 or less, and causes the compression stroke direct injection injector 14b to supply the compression stroke. At the same time, the recirculation amount of the exhaust gas to be recirculated is determined based on the detection values of the engine rotation speed sensor 61 and the air flow sensor 22, and the EGR valve 42 is controlled accordingly. When the engine load calculated from the detection value of the airflow sensor 22 is in a low load region where the engine load is smaller than a predetermined value, the output is not so much required, so the air-fuel ratio is made lean and the excess air ratio λ becomes 1.8. Thus, the supply amount of hydrogen is determined and the recirculation of the exhaust gas is stopped. In the idling state (region ID) where the engine speed is equal to or less than a predetermined value, the hydrogen supply amount is determined so that the excess air ratio λ becomes 1.8, and the exhaust gas recirculation is stopped.

  Although the first engine operation state (region I) is low in volume efficiency even in the low rotation region, it is possible to improve the volume efficiency and improve the output by supplying the compression stroke by the compression stroke direct injection injector 14b. it can. However, when the compression stroke is supplied, hydrogen is easily agglomerated and the risk of pre-ignition increases. Thus, the exhaust gas is recirculated to suppress the combustion temperature, and as a result, the temperature in the cylinder 11 can be suppressed to suppress the occurrence of pre-ignition. Of course, the NOx emission amount can be suppressed by the recirculation of the exhaust gas. Thus, if the occurrence of pre-ignition can be suppressed, the air-fuel ratio can be enriched by that amount, and the output can be improved. As a result, in the present embodiment, the air excess ratio λ can be enriched to an extent of 1.0 or less.

  When the engine rotation speed N is not less than the first rotation speed n1 and less than the second rotation speed n2 (hereinafter referred to as the second engine operating state), the engine load is calculated based on the detected value of the air flow sensor 22 in step S3. Then, it is determined whether or not the calculated engine load is larger than a predetermined value set in advance for each engine speed. If the engine load is greater than the predetermined value, the process proceeds to step S4 assuming that the engine is in a high load state.

  That is, when the engine is in the second engine operating state and is in a high load state (region II in FIG. 3), in step S4, the intake stroke is supplied by the in-passage injector 15 and the compression stroke direct injection injector 14b. To supply the compression stroke. Further, the exhaust gas is recirculated. On the other hand, when the engine is in the second engine operating state and is in a low load state (region II ′ in FIG. 3), the intake stroke is supplied by the in-passage injector 15 and the compression stroke direct injection is performed in step S5. The compression stroke is supplied by the injector 14b. In the low load state, it is not necessary to enrich the air-fuel ratio so much that the risk of pre-ignition is low. Therefore, the exhaust gas is not recirculated.

  The second engine operating state (regions II and II ') is a middle rotation region, and when a large amount of exhaust gas is recirculated, the air charging efficiency is lowered and the output is lowered. Therefore, the pre-ignition is suppressed by supplying the intake stroke. The exhaust gas is recirculated only in a high load region where the risk of pre-ignition is high.

  Specifically, the PCM 5 determines the hydrogen supply amount based on the detection value of the air flow sensor 22 so that the excess air ratio λ becomes 1.1 to 1.3 (high load region) or 1.5 to 1.6 (low load region). Then, the determined supply amount is distributed to the in-passage injector 15 and the compression stroke direct injection injector 14b at a ratio of 1: 1, and the intake stroke supply or the compression stroke supply is performed respectively. In the case of the high load region, the exhaust gas recirculation amount to be recirculated is determined based on the detected values of the engine speed sensor 61 and the air flow sensor 22 and the EGR valve 42 is controlled accordingly. However, the amount of exhaust gas recirculated is set to be smaller than the amount of exhaust gas recirculated in the first engine operating state. On the other hand, in the low load region, the exhaust gas is not recirculated.

  Thus, by supplying the intake stroke with the injector 15 in the passage, the mixing of hydrogen and air is improved, and pre-ignition can be suppressed. Further, in a high load state (region II) in which the air-fuel ratio has to be enriched and the risk of pre-ignition increases, the pre-ignition can be further suppressed by recirculating the exhaust gas. However, since the amount of the exhaust gas recirculated is a small amount as compared with the first engine operating state, the air filling efficiency is not greatly affected. In the low load state (region II ′) where the risk of pre-ignition is low, the air filling efficiency is improved by stopping the exhaust gas recirculation. Thus, if the pre-ignition can be suppressed, the output can be improved accordingly. Further, since the volume efficiency can be improved by supplying hydrogen during the compression stroke by the compression stroke direct injection injector 14b, the output can also be improved by this. As a result, in the present embodiment, by suppressing the pre-ignition, the excess air ratio λ can be enriched from 1.1 to 1.3 in the high load region (region II). In the low load region (region II '), the exhaust gas is not recirculated, but the excess air ratio λ can be enriched from 1.5 to 1.6.

  When the engine rotational speed N is equal to or higher than the second rotational speed n2 and lower than the third rotational speed n3 (hereinafter referred to as the third engine operating state), the intake stroke is supplied by the in-passage injector 15 and the compression stroke is performed in step S5. The compression stroke is supplied by the direct injection injector 14b (region III in FIG. 3). At this time, unlike step S5 in the second engine operating state, the rate of hydrogen supply by the intake stroke direct injection injector 14a is increased as at least one of the engine speed and the engine load is higher. Note that the exhaust gas is not recirculated.

  Specifically, the PCM 5 determines the hydrogen supply amount based on the detection value of the airflow sensor 22 so that the excess air ratio λ becomes 1.4 to 1.6. Then, the determined hydrogen supply amount is distributed to the in-passage injector 15 and the compression stroke direct injection injector 14b based on the engine rotational speed N and the engine load T. In the present embodiment, the third engine operating state is divided into four regions, and the distribution ratio is determined for each region in advance. That is, the distribution ratio between the in-passage injector 15 and the compression stroke direct injection injector 14b is 5: 5 in the low rotation and low load region (a), and the low rotation and high load region (b) and the high rotation and low load region. (C) is set to 6: 4, and the high rotation and high load region (d) is set to 7: 3. According to this distribution ratio, hydrogen is supplied to the in-passage injector 15 and the compression stroke direct injection injector 14b, respectively.

  The third engine operation state (region III) is a high rotation region, and the exhaust gas becomes high temperature. Therefore, when the exhaust gas is recirculated, the temperature of the combustion chamber is raised, and an environment in which pre-ignition is likely to occur is generated. . In addition, when the exhaust gas is recirculated in a state where the engine rotation speed is high, the air filling efficiency is greatly reduced. That is, by stopping the exhaust gas recirculation, adverse effects due to the exhaust gas recirculation can be prevented. The pre-ignition can be suppressed by supplying the intake stroke by the in-passage injector 15. Further, by using together the compression stroke supply by the compression stroke direct injection injector 14b, the volumetric efficiency can be improved and the output can be improved. Furthermore, since the risk of pre-ignition increases as the engine speed and engine load increase, the pre-ignition can be ensured by changing the distribution ratio between the in-passage injector 15 and the compression stroke direct injection injector 14b as described above. Can be suppressed. Thus, if the pre-ignition can be suppressed, the output can be improved accordingly. As a result, in the present embodiment, the excess air ratio λ can be enriched from 1.4 to 1.6 by suppressing the pre-ignition.

  When the engine rotational speed N is equal to or higher than the third rotational speed n3 (hereinafter referred to as the fourth engine operating state), in step S6, the intake stroke supply is performed by using the in-passage injector 15 and the intake stroke direct injection injector 14a together. Perform (region IV in FIG. 3). Note that the exhaust gas is not recirculated.

  Specifically, the PCM 5 determines the supply amount of hydrogen so that the excess air ratio λ becomes 1.4 to 1.6 based on the detection value of the air flow sensor 22, and the determined supply amount is determined with the injector 15 in the passage. The intake stroke direct injection injector 14a is distributed at a ratio of 1: 1 so that the intake stroke is supplied to each.

  The fourth engine operation state (region IV) is a higher rotation region than the third engine operation state, and the period of each stroke is short. Therefore, when hydrogen is supplied to the compression stroke, the hydrogen is very easily agglomerated. Therefore, the compression stroke supply by the compression stroke direct injection injector 14b is stopped, and the intake stroke supply is performed by the in-passage injector 15 and the intake stroke direct injection injector 14a, thereby improving the mixing and suppressing the pre-ignition. be able to. Even when the intake stroke is supplied, not only the in-passage injector 15 but also the intake stroke direct injection injector 14a, which is relatively superior in volume efficiency, is used, so that not only the pre-ignition is suppressed but also the volume efficiency. It is also possible to improve the output. Thus, if the pre-ignition can be suppressed, the output can be improved accordingly. As a result, in the present embodiment, the excess air ratio λ can be enriched from 1.4 to 1.6 by suppressing the pre-ignition.

  Therefore, according to the present embodiment, the intake stroke direct injection injector 14a, the compression stroke direct injection injector 14b, and the in-passage injector 15 are selectively used in accordance with the engine rotational speed, and the presence or absence of exhaust gas recirculation is switched. In addition, the pre-ignition can be suppressed and the output can be improved.

<< Other Embodiments >>
The present invention may be configured as follows with respect to the embodiment. That is, in the above-described embodiment, the three injectors of the intake stroke direct injection injector 14a, the compression stroke direct injection injector 14b, and the in-passage injector 15 are provided, but the present invention is not limited thereto. That is, the number and type of injectors can be arbitrarily set as long as the intake stroke supply and the compression stroke supply can be performed. For example, the configuration may include only the compression stroke direct injection injector 14b and the in-passage injector 15, or may include only the intake stroke direct injection injector 14a and the compression stroke direct injection injector 14b. Also, instead of using two direct injection injectors for the compression stroke and the intake stroke, only one direct injection injector is used, and the intake timing supply and the compression stroke supply are controlled by controlling the injection timing of the direct injection injector. You may make it perform. In the first engine operation state, the compression stroke supply and the exhaust gas recirculation are performed. In the second engine operation state, the intake stroke supply, the compression stroke supply, and the exhaust gas recirculation (only in the high load region) are performed. In the third engine operating state, intake stroke supply and compression stroke supply may be performed, and in the fourth engine operating state, intake stroke supply may be performed. By doing so, output can be improved while suppressing pre-injection.

  That is, in the case of the configuration including only the compression stroke direct injection injector 14b and the in-passage injector 15, in the first engine operation state, the compression stroke direct injection and the exhaust gas recirculation are performed by the compression stroke direct injection injector 14b. In the two-engine operating state, the compression stroke is supplied by the compression stroke direct injection injector 14b, the intake stroke is supplied by the in-passage injector 15 and the exhaust gas is recirculated (only in the high load region). In the third engine operating state, the compression stroke is supplied. The compression stroke supply by the direct injection injector 14b and the intake stroke supply by the in-passage injector 15 are performed. In the fourth engine operating state, the intake stroke supply by only the in-passage injector 15 (or the intake stroke to the compression stroke direct injection injector 14b). The fuel is injected into the fuel, and the intake stroke is provided by the compression stroke direct injection injector 14b. The combination) may be performed.

  Further, in the case of the configuration including only the intake stroke direct injection injector 14a and the compression stroke direct injection injector 14b, in the first engine operating state, the compression stroke supply by the compression stroke direct injection injector 14b and the exhaust gas recirculation are performed. In the second engine operating state, intake stroke supply by the intake stroke direct injection injector 14a, compression stroke supply by the compression stroke direct injection injector 14b, and exhaust gas recirculation (only in a high load region) are performed. In the operating state, intake stroke supply by the intake stroke direct injection injector 14a and compression stroke supply by the compression stroke direct injection injector 14b are performed. In the fourth engine operating state, intake stroke supply by the intake stroke direct injection injector 14a is performed. You just have to do it. As described above, hydrogen is not injected into the direct-injector 14a for the intake stroke and the direct-injector 14b for the compression stroke, but is injected into the single direct-injector in the intake stroke and the compression stroke, respectively. In this configuration, the intake stroke supply and the compression stroke supply may be performed by the one direct injection injector.

  Furthermore, in the above embodiment, the injector to be used and the presence or absence of the recirculation of exhaust gas are set by dividing into four states (regions) from the first engine operating state to the fourth engine operating state according to the engine speed. However, it is not limited to this. That is, at least a first engine operation state in which the compression stroke supply and the exhaust gas recirculation are performed, and a second engine operation state in which the intake stroke supply, the compression stroke supply, and the exhaust gas recirculation (only in the high load region) are performed, What is necessary is just to divide into the 3rd engine operating state which performs intake stroke supply and compression stroke supply. At this time, the fourth engine operating state is included in the third engine operating state. If the engine rotational speed is equal to or higher than the third rotational speed n3, the intake stroke supply and the compression stroke supply are performed. That's fine.

  Further, in the embodiment, in the second engine operating state, the presence or absence of exhaust gas recirculation is set according to the load state. However, the present invention is not limited to this, and exhaust gas is exhausted in the entire region in the second engine operating state. The gas may be refluxed. Even in such a configuration, pre-ignition can be suppressed by supplying the intake stroke and recirculation of the exhaust gas, and output can be improved by supplying the compression stroke. However, it is preferable that the amount of exhaust gas recirculated is smaller than the amount of exhaust gas recirculated in the first engine operating state. By doing so, it is possible to suppress a decrease in air filling efficiency.

  Furthermore, in the above-described embodiment, in the third engine operating state, the distribution ratio between the intake stroke supply and the compression stroke supply is changed according to the engine speed and the engine load. The intake stroke supply and the compression stroke supply may be performed at a distribution ratio. Even in such a configuration, pre-ignition can be suppressed by the intake stroke supply, and the output can be improved by the compression stroke supply.

  Furthermore, the distribution ratio between the intake stroke supply and the compression stroke supply in the second engine operation state to the fourth engine operation state is not limited to the above ratio, and the engine operation state, pre-ignition, output, etc. Any ratio can be adopted in consideration.

  Moreover, although the case where this invention was applied to the rotary engine was demonstrated in the said embodiment, it is not restricted to this, It can also apply to a reciprocating engine.

  As described above, the present invention is useful for a hydrogen engine because the output can be improved while suppressing pre-ignition.

It is the schematic which shows the rotary engine which concerns on embodiment of this invention. It is a flowchart which shows fuel supply control. It is a map which shows the specification about the presence or absence of the injector used and the recirculation | reflux of exhaust_gas | exhaustion.

14a Direct injection injector for intake stroke (hydrogen supply means, direct injection supply means)
14b Direct injection injector for compression stroke (hydrogen supply means, direct injection supply means)
15 In-passage injector (hydrogen supply means, in-passage supply means)
4 EGR passage (exhaust gas recirculation means)
41 EGR cooler (exhaust gas recirculation means)
42 EGR valve (exhaust gas recirculation means)
5 PCM (control means)

Claims (6)

A hydrogen supply means for supplying hydrogen, an intake stroke supply for supplying hydrogen during the intake stroke to the hydrogen supply means, and a compression stroke supply for supplying hydrogen during the compression stroke to the hydrogen supply means are switched and used in combination. And a control device for controlling the supply timing of the hydrogen engine,
It further comprises exhaust gas recirculation means for recirculating exhaust gas to the intake system,
The control means includes
In the first engine operating state where the engine rotation speed is less than a predetermined first rotation speed, the hydrogen supply means supplies the compression stroke, and the exhaust gas recirculation means causes the exhaust gas to recirculate to the intake system.
In the second engine operating state in which the engine rotation speed is equal to or higher than the first rotation speed and less than a predetermined second rotation speed higher than the first rotation speed, the intake stroke supply and the compression process supply are supplied to the hydrogen supply means. And the exhaust gas recirculation means causes the exhaust gas to recirculate to the intake system,
In the third engine operating state where the engine rotation speed is equal to or higher than the second rotation speed, the hydrogen supply means performs the intake stroke supply and the compression stroke supply ,
The exhaust gas recirculation to the intake system by the exhaust gas recirculation means in the second engine operating state is performed only in a predetermined high load region, and the amount of exhaust gas recirculated at that time is the first engine A control device for a hydrogen engine, characterized in that it is less than the amount of exhaust gas recirculated in an operating state . The control device for a hydrogen engine according to claim 1,
The control means causes the hydrogen supply means to perform only the intake stroke supply in a fourth engine operating state in which the engine speed is equal to or higher than a predetermined third speed higher than the second speed. Control device for hydrogen engine. The hydrogen engine control device according to claim 1 or 2 ,
The distribution ratio between the intake stroke supply and the compression stroke supply in the third engine operation state is such that the higher the at least one of the engine rotational speed and the engine load, the higher the intake stroke supply ratio. Control device for hydrogen engine. The hydrogen engine control device according to claim 1 or 2 ,
2. The hydrogen engine control apparatus according to claim 1, wherein the hydrogen supply means is direct injection supply means for supplying hydrogen directly into the combustion chamber. The hydrogen engine control device according to claim 1 or 2 ,
The hydrogen supply means includes in-passage supply means for supplying hydrogen into the combustion chamber by injecting hydrogen into the intake passage, and direct injection supply means for supplying hydrogen directly into the combustion chamber,
2. The hydrogen engine control apparatus according to claim 1, wherein the control means causes the in-passage supply means to perform the intake stroke supply, and causes the direct injection supply means to perform the compression stroke supply. The control device for a hydrogen engine according to claim 2,
The hydrogen supply means has direct injection supply means for supplying hydrogen directly into the combustion chamber, and in-passage supply means for supplying hydrogen into the combustion chamber by injecting hydrogen into an intake passage,
The control means includes
Of the intake stroke supply, the intake stroke supply in the second and third engine operating states is performed by the in-passage supply means, while the intake stroke supply in the fourth engine operating state is performed by the direct injection supply means and While letting both of the supply means in the passage,
A control device for a hydrogen engine, characterized in that the compression stroke supply is performed by the direct injection supply means.

Images