JP4353104B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device including a direct injection hydrogen injection valve that directly injects gaseous hydrogen into a working chamber and an intake passage injection valve that supplies gaseous hydrogen or gasoline into the intake passage.

  In recent years, for the purpose of reducing pollution, development of a vehicle equipped with an engine to be used with gaseous fuel such as compressed natural gas, liquefied propane gas, and compressed hydrogen has been promoted. In an engine using such a gaseous fuel, moisture generated by combustion or moisture originally contained in the gas freezes as the outside air temperature decreases, and it adheres to an injection valve that injects gaseous fuel and hinders its operation. May occur. In response to such a problem, for example, Japanese Patent Application Laid-Open No. 11-264334 proposes a method of setting a long drive current supply time to the injection valve at a low temperature start and melting icing by a heat generation action associated therewith. .

JP-A-11-264334

  However, as disclosed in the above-mentioned Patent Document 1, when the energization time is lengthened, the injection amount increases as a result, and the air-fuel ratio at the time of starting becomes over-rich. There is a fear. Therefore, it is highly desirable to eliminate icing in the injection valve while ensuring stable engine startability. In an engine that uses compressed hydrogen as a fuel in particular, it is very meaningful to realize this because water is generated with combustion of gaseous hydrogen.

  The present invention has been made in view of the above technical problem, and in particular, a direct injection type hydrogen injection valve that directly injects gaseous hydrogen into the working chamber, and an intake passage injection valve that supplies gaseous hydrogen or gasoline into the intake passage. It is an object of the present invention to provide an engine control device that can ensure stable startability of the engine while avoiding the influence of freezing on the hydrogen injection valve at the time of low-temperature start of the engine having the above.

  The invention according to claim 1 of the present application controls an engine including a direct injection hydrogen injection valve that directly injects gaseous hydrogen into a working chamber, and an intake passage injection valve that supplies gaseous hydrogen or gasoline into the intake passage. In the apparatus, when the engine is started at a low temperature, the supply of hydrogen by the direct injection hydrogen injection valve is prohibited, and gaseous hydrogen or gasoline is supplied by the intake passage injection valve.

  In the invention according to claim 2 of the present application, in the invention according to claim 1, when it is estimated that the temperature of the direct injection hydrogen injection valve has risen above a predetermined temperature, the fuel injection valve is used for the intake passage. The injection valve is switched to the direct injection hydrogen injection valve.

  Further, the invention according to claim 3 of the present application is the invention according to claim 2, wherein the temperature of the direct injection hydrogen injection valve is predetermined when a predetermined time has elapsed from the start time or completion time of the cold start of the engine. It is estimated that the temperature has risen above the temperature.

  Furthermore, the invention according to claim 4 of the present application is the invention according to claim 2 or 3, wherein when the engine temperature rises to a predetermined temperature or higher, the temperature of the direct injection hydrogen injection valve becomes equal to or higher than the predetermined temperature. It is characterized by an increase.

  Furthermore, the invention according to claim 5 of the present application is the invention according to any one of claims 1 to 5, wherein the intake passage injection valve includes a gasoline injection valve for supplying gasoline, and gaseous hydrogen. When the engine temperature is determined to be equal to or higher than a predetermined temperature, gaseous hydrogen is supplied from the hydrogen injection valve, and the engine temperature is determined to be lower than the predetermined temperature. In this case, gasoline is supplied from the gasoline injection valve.

  According to the invention according to claim 1 of the present application, when restarting from a state where moisture generated by combustion of gaseous hydrogen after the engine is stopped may be frozen near the tip of the direct injection hydrogen injection valve, Since the intake passage injection valve is used, even if the direct injection type hydrogen injection valve freezes, the influence can be avoided and good engine startability can be ensured.

  Further, according to the invention according to claim 2 of the present application, it is estimated that the engine temperature rises after the low temperature start, and with the temperature rise, the temperature of the direct injection hydrogen injection valve rises and icing is eliminated. In addition, since switching from the intake passage injection valve to the direct injection type hydrogen injection valve is performed, high air-fuel ratio control accuracy can be ensured.

  Further, according to the third aspect of the present invention, the temperature of the direct injection hydrogen injector can be easily estimated based on the elapsed time from the start time or completion time of the low temperature engine start.

  Furthermore, according to the invention of claim 4 of the present application, the temperature of the direct injection hydrogen injection valve can be easily estimated based on the engine temperature.

  Further, according to the invention of claim 5 of the present application, when the engine temperature is lower than the predetermined temperature, the engine is started using the gasoline injection valve for the intake passage, so that it can be greatly increased. Therefore, it is possible to prevent the drive current from being supplied to the hydrogen injection valve for the intake passage, and to suppress the power supply voltage drop when the engine is started.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram schematically showing a rotary type hydrogen engine according to an embodiment of the present invention. The hydrogen engine 1 has a rotor housing H ₁ having a trochoidal inner peripheral surface and a substantially flat side housing H ₂ that extends along the plane 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 ₁ , E ₂ and E ₃ are defined. Each working chamber E ₁ , E ₂ , E ₃ repeats expansion and contraction as the rotor R rotates about the eccentric shaft C, and each working chamber E ₁ , E ₂ , E ₃ , intake stroke in E _3, compression stroke, expansion stroke, a series of stroke is completed consisting exhaust stroke.

The rotor housing H ₁ includes a gaseous hydrogen injection valve (hereinafter referred to as a direct injection hydrogen injector) I ₁ that directly injects gaseous hydrogen into the working chambers E ₁ , E ₂ , E ₃ , and working chambers E ₁ , E _2. , the spark plug 7 for igniting the air-fuel mixture consisting of supplied fuel (gaseous hydrogen or gasoline) and air in E _3, are provided. On the other hand, the side housing H ₂ is formed with an intake port 2 a communicating with the intake passage 2 and an exhaust port 3 a communicating with the exhaust passage 3.

Furthermore, in this embodiment, in addition to the direct injection type hydrogen injector I ₁ provided in the rotor housing H ₁ , a gasoline injection valve I ₂ (hereinafter referred to as port injection) that is attached to the intake passage 2 and injects gasoline into the intake passage 2. with that formula gasoline injector I ₂₎ is provided, on its upstream side, likewise attached to the intake passage 2, a hydrogen injector I ₃ for injecting gaseous hydrogen into the intake passage 2 _{(hereinafter,} port injection hydrogen injector I ₃ ). When the fuel supply to the working chamber of the hydrogen engine 1 is required, the fuel can be directly adjusted according to various conditions such as the engine speed, the remaining amount of hydrogen or gasoline, or according to the driver's request. An appropriate one is selected from the injection type hydrogen injector I ₁ , the port injection type gasoline injector I ₂ , and the port injection type hydrogen injector I ₃ .

FIG. 2 is a diagram conceptually showing the hydrogen engine 1 and the configuration related thereto. As can be seen from this figure, solenoid valves V ₁ , V _2, and V ₃ are attached to the direct injection hydrogen injector I ₁ , the port injection type gasoline injector I _2, and the port injection type hydrogen injector I ₃ , respectively. The fuel injection in the injector is controlled based on the opening / closing operation of each solenoid valve. In FIG. 2, the solenoid valves V ₁ , V ₂ , and V ₃ are separately provided for the injectors I ₁ , I ₂ , and I ₃ , but in reality, the direct injection hydrogen injector I is shown. _As shown in FIGS. 3A and 3B showing the cross-sectional structure of FIG. ₁ , a solenoid valve is incorporated in each injector.

  As shown in FIG. 2, in the present embodiment, with respect to the main body of the hydrogen engine 1, a water temperature sensor 18 for detecting the coolant temperature of the engine 1 and an engine rotation for detecting the engine speed. A number sensor 19 is provided. The intake passage 2 is provided with an intake air temperature sensor 21 that detects the temperature of the air flowing in the intake passage 2, while the exhaust passage 3 detects an oxygen concentration so as to calculate the air-fuel ratio in the working chamber. For this purpose, an oxygen concentration sensor (so-called λ sensor) 22 is provided.

Further, as shown in FIG. 2, the direct injection hydrogen injector I ₁ provided in the rotor housing H ₁ constituting the engine body and the port injection hydrogen injector I ₃ attached to the intake passage 2 include a hydrogen supply pipe 9. Is connected to a hydrogen storage tank 14 for storing gaseous hydrogen. On the other hand, the port injection type gasoline injector I ₂ attached to the intake passage 2 is connected to a gasoline storage tank (not shown) via a gasoline supply pipe 13. The discharge port of the hydrogen storage tank 14 is provided with a stop valve 15 that is controlled to be opened and closed to control hydrogen discharge from the hydrogen storage tank 14 to the hydrogen supply pipe 9. Further, a shutoff valve 16 is provided in the hydrogen supply pipe 9 for controlling hydrogen supply to each of the direct injection type hydrogen injector I ₁ and the port injection type hydrogen injector I ₃ . Further, in the hydrogen supply pipe 9, the residual pressure in the hydrogen supply pipe 9 is detected between the shutoff valve 16 and the direct injection hydrogen injector I _{1 in} order to calculate the remaining amount of hydrogen in the hydrogen storage tank 14. A pressure sensor 17 is provided.

  Although not particularly shown, the configuration related to the hydrogen engine 1 includes an air cleaner provided in the intake passage 2, an air flow sensor for detecting the intake air amount, and opening / closing according to the amount of depression of an accelerator pedal (not shown). Throttle valve that throttles air, a throttle opening sensor that detects the opening of the throttle valve, a surge tank that stabilizes the air flow, an exhaust gas purification catalyst provided in the exhaust passage 3, an exhaust temperature sensor In addition, a configuration other than the above is provided, such as a fuel flow meter that is provided in the hydrogen supply passage 9 or the gasoline supply passage 13 and detects the flow rate of the fuel supplied to various injectors.

Further, as shown in FIG. 2, a control unit 10 is provided for controlling the hydrogen engine 1 and the related configuration as described above. The control unit 10 is a comprehensive control device for the hydrogen engine 1 comprising a computer, and includes an intake air amount detected by an air flow sensor, an engine water temperature detected by a water temperature sensor 18, a throttle opening sensor, and an idle switch. (A switch that is turned on when the accelerator pedal is fully closed, but not shown here), the throttle opening detected by the engine speed sensor 19, the engine speed detected by the engine speed sensor, the exhaust temperature detected by the exhaust temperature sensor, Various controls such as fuel injection control and ignition timing adjustment control of the engine 1 are performed based on various control information such as the fuel flow rate to the injector detected by the fuel flow meter, and injectors I ₁ and I ₂ described later. , and it performs the drive control processing of I _3. The control unit 10 has a microcomputer (not shown) therein, and correction and calculation executed when various controls including drive control of the injectors I ₁ , I ₂ , and I ₃ are performed. Processing such as determination is performed by the microcomputer.

Next, the structure of the direct injection type hydrogen injector I ₁ that is driven and controlled by the control unit 10 will be described. 3A and 3B are longitudinal sectional explanatory views showing the direct-injection hydrogen injector I ₁ in a closed state and an open state, respectively. The hydrogen injector I ₁ includes an injector body 4 having a gas passage 4a extending along the axial direction, and a gas passage 5a that is provided in the gas passage 4c of the injector body 4 and also extends along the axial direction. A needle valve 5.

The injector body 4 communicates with the hydrogen supply pipe 9 at one end side (the upper end side in FIGS. 3A and 3B), and forms the injection hole 4b at the other end side (the lower end side in FIGS. 3A and 3B). It faces the internal space. Further, the needle valve 5 provided in the gas passage 4a is held so as to slide along the inner peripheral surface of the gas passage 4a on one end side (the upper end side in FIGS. 3A and 3B), while on the other end side. (The lower end side in FIGS. 3A and 3B) constitutes the seal portion 5b, and a plurality of branches formed so as to branch from the gas passage 5a and open at the side surface of the needle valve 5 on the upstream side of the seal portion 5b. A passage 5c is provided. Corresponding to the seal portion 5b of the needle valve 5, a valve seat surface 4c is formed in the gas passage 4a of the injector body 4 on the upstream side of the injection hole 4b. By sealing portion 5b of the needle valve 5 is seated on the valve seat surface 4c, hydrogen injection from the injection hole 4b of the injector body 4 is prevented and the hydrogen supply from the direct-injection hydrogen injector I ₁ to the working chamber of the hydrogen engine 1 Is stopped.

A magnetic body (not shown) is attached to the needle valve 5, while a solenoid coil 6 that constitutes the electromagnetic valve V ₁ together with the needle valve 5 is incorporated in the injector body 4 around the gas passage 4 a. Yes. By providing such a configuration, in the direct injection hydrogen injector I ₁ , the needle valve 5 is shifted upward along the gas passage 4 c of the injector body 4 when supplying the drive current to the solenoid coil 6. Within the moving range of the needle valve 5, the amount of shift upward of the needle valve 5 increases as the drive current increases.

That is, in a state where the drive current is not supplied to the solenoid coil 6, the seal portion 5 b of the needle valve 5 is seated on the valve seat surface 4 c formed in the gas passage 4 a of the injector body 4, thereby ₁ is closed (see FIG. 3A), while in the state in which the driving current is supplied to the solenoid coil 6, that the seal portion 5b of the needle valve 5 is separated from the valve seat surface 4c, the solenoid valve V ₂ is opened ( (See FIG. 3B). In a state where the solenoid valve V ₂ is opened, as indicated by broken line arrow in FIG. 3B, gaseous hydrogen is a gas passage 4a of the injector body 4, the gas passage 5a of the needle valve 5, the branch passage 5c of the needle valve 5, The gas flows in the order of the gas passage 4 a of the injector body 4 and the injection hole 4 b of the injector body 4, and is injected from the injection hole 4 b of the injector body 4.

The injection timing and the injection amount of gaseous hydrogen in the direct injection hydrogen injector I ₁ having such a configuration are controlled by a control unit 10 including a microcomputer. More specifically, the control unit 10 outputs a pulse to be output to the direct injection hydrogen injector I ₁ based on signals detected from various sensors such as an air flow meter, a throttle sensor, a pressure sensor 17, a water temperature sensor 18, and an engine speed sensor 19. timing and BALS width, i.e., so as to calculate the opening timing and opening time of the solenoid valve V _1, to control the injection timing and injection amount of gaseous hydrogen.

Here, the direct injection type hydrogen injector I ₁ provided in the rotor housing H ₁ has been described. However, in this embodiment, the port injection type hydrogen injector I ₃ attached to the intake passage 2 has the same configuration. What you have is used.

Subsequently, in the hydrogen engine 1, hydrogen injectors (direct injection type hydrogen injector I ₁ and port injection type hydrogen injector I ₃ ) having the above-described structure are selectively used according to the engine speed detected by the engine speed sensor 19. The control by the control unit 10 in which the injection timing is changed will be described. FIG. 4 is an explanatory diagram showing a hydrogen injector adopted according to each engine speed and its injection timing. First, in the low rotation region (about 800 to 2500 rpm), the direct injection type hydrogen injector I ₁ is employed, and injection in the compression stroke is executed. Here, when gaseous hydrogen with a large volume is supplied during the intake stroke, the problem is that the volume of hydrogen does not allow air to sufficiently enter the working chamber via the intake port 2a. During the stroke, gaseous hydrogen is supplied, and a decrease in fuel charging efficiency is suppressed.

Further, in the middle speed region (approximately 2500～5000Rpm), it is adopted direct-injection hydrogen injector _{I 1,} is executed injection in the intake stroke. Here, in order to cope with the problem that abnormal combustion occurs when ignition is performed with the gaseous hydrogen and air separated, the gaseous hydrogen is injected from the direct injection hydrogen injector I ₁ at an early stage of the intake stroke, and the mixing time is reached. By ensuring this, the mixing property of gaseous hydrogen and air is improved.

Finally, in the high rotation region (about 5000～7000Rpm), the direct-injection hydrogen injector _{I 1} and the port-injection hydrogen injector _{I 3} are combined. Here, the port injection type hydrogen injector I ₃ is used to improve the mixing property between gaseous hydrogen and air, and the premixed injection is executed. At the same time, the direct injection type hydrogen injector I ₁ is used to suppress the torque drop. Are used to perform injection in the compression stroke. As an example, the ratio of hydrogen feed is 80% the amount supplied from the port injection hydrogen injector I _3, the supply amount from the direct-injection hydrogen injector I ₁ is 20%.

By the way, in the engine equipped with the conventional direct injection type hydrogen injector, the water generated by the combustion of gaseous hydrogen is frozen as the outside air temperature decreases, and it adheres to the direct injection type hydrogen injector and may hinder its operation. However, in the present embodiment, basically, at the time of low temperature start, the port injection type gasoline injector I ₂ and the hydrogen injector I ₃ are used, and the influence of freezing on the direct injection type hydrogen injector I ₁ is avoided.

Further, in this embodiment, when it is estimated that the temperature of the direct injection hydrogen injector I ₁ has risen above a predetermined temperature from the start of the low temperature start (for example, when a predetermined time has elapsed since the start of the low temperature start, or the engine temperature is When the temperature rises to a predetermined temperature or higher), the port injection type gasoline injector I ₂ and the hydrogen injector I ₃ are switched to the direct injection type hydrogen injector. Thereby, higher air-fuel ratio control accuracy is ensured.

Further, when the engine temperature is higher than a predetermined temperature, it is used port injection hydrogen injector I _3, on the other hand, when the engine temperature is lower than the predetermined temperature, the port injection gasoline injector I ₂ is used. This prevents the supply of addresses to the extremely severe icing conditions to the port injection hydrogen injector I ₃ of the driving current is greatly increased, the power supply voltage drop at the start of the engine is suppressed.

Hereinafter, the first and second injector drive controls executed by the computer unit 10 will be described with reference to the flowcharts of FIGS. 5 and 6, respectively. Note that there is a difference between the first and second injector drive control in terms of the conditions for switching from the port injection type gasoline injector I ₂ or the hydrogen injector I ₃ to the direct injection type hydrogen injector I ₁ .

  FIG. 5 is a flowchart of the first injector drive control process executed by the control unit 10. In this process, first, for example, various signals detected by the configuration related to the hydrogen engine 1 shown in FIG. 2 are read (# 11), and based on those signals, whether or not the hydrogen engine 1 is started, that is, an ignition. Whether or not is turned on from the off state is determined (# 12). As a result, if it is determined that the hydrogen engine 1 has been started, the process proceeds to step # 13. On the other hand, if it is determined that the hydrogen engine 1 has not been started, the process proceeds to step # 19.

In step # 13, it is determined whether or not the intake air temperature is less than 0 ° C. As a result, if it is determined that the intake air temperature is not less than 0 ° C., that is, greater than or equal to 0 ° C., the direct injection hydrogen injector I as the temperature of ₁ is no predetermined temperature or higher possibility of freezing, allowed to drive direct-injection hydrogen injector I ₁ (# 18), gaseous hydrogen is injected into the working chamber. The process is returned as above. On the other hand, if it is determined that the intake air temperature is less than 0 ° C., the temperature of the direct injection hydrogen injector I ₁ is less than the predetermined temperature, and there is a possibility of freezing.

In step # 14, it is determined whether or not a predetermined time has elapsed from the start of the start of the hydrogen engine 1. As a result, if it is determined that the predetermined time has elapsed, it is assumed that icing has already been eliminated, and the direct injection type hydrogen injector I ₁ is driven (# 18), gaseous hydrogen is injected into the working chamber. The process is returned as above. On the other hand, if it is determined that the predetermined time has not elapsed, there is a possibility of freezing, and the process further proceeds to step # 15.

In step # 15, it is determined whether or not the intake air temperature is less than −10 ° C. As a result, if it is determined that the intake air temperature is less than −10 ° C., it is determined that the engine temperature is less than the predetermined temperature. , port-injection gasoline injector I ₂ is driven (# 16), the gasoline is injected into the intake passage 2. On the other hand, if it is determined that the intake air temperature is not lower than −10 ° C., that is, equal to or higher than −10 ° C., the port injection hydrogen injector I ₃ is driven assuming that the engine temperature is equal to or higher than the predetermined temperature ( # 17), gaseous hydrogen is injected into the intake passage 2; After steps # 16 and # 17, the process is returned.

In relation to step # 16 and # 17, in the present embodiment, between the port injection gasoline injector I ₂ and hydrogen injector I _3, in achieving charging efficiency of the same fuel hydrogen injector I ₃ There is a relationship that a larger driving current needs to be supplied. In consideration of this, in step # 15, particularly when the engine temperature is lower than the predetermined temperature and it is determined that the icing is severe, the power supply voltage drop is suppressed and the engine start such as the voltage for the engine starter is started. to ensure a voltage to other configurations requiring when the power voltage, the port injection gasoline injector I ₂ is driven. In this case, the moisture contained in the blowback of the burned gas from the working chamber to the intake passage 2 is frozen, and the hydrogen injector in the intake passage 2 may be frozen. to ensure the startability, the port injection gasoline injector I ₂ is driven.

Further, in step # 19 which proceeds when it is determined in step # 12 that it is not at the time of starting the hydrogen engine 1, it is determined whether or not the residual hydrogen pressure detected by the pressure sensor 17 (see FIG. 2) is greater than 0.5 MPa. If it is determined that the residual hydrogen pressure is greater than 0.5 MPa, it is determined that there is sufficient hydrogen remaining in the hydrogen storage tank 14 and the engine rotation described above with reference to FIG. The direct injection type hydrogen injector I ₁ and the port injection type hydrogen injector I ₃ are switched according to the number (# 20). Also, whereas, if the hydrogen residual pressure is determined to be 0.5MPa or less, as is not sufficient the remaining amount of hydrogen in the hydrogen storage tank 14, a port injection gasoline injector I ₂ is driven (# 21 ), Gasoline is injected into the intake passage 2. After steps # 20 and # 21, the process is returned.

In the first injector drive control process, switching from the port injection type gasoline injector I ₂ or the hydrogen injector I ₃ to the direct injection type hydrogen injector I ₁ is performed when a predetermined time has elapsed from the start of the start.

  Next, FIG. 6 is a flowchart of the second injector drive control process executed by the control unit 10. In this process, first, for example, various signals detected by the configuration related to the hydrogen engine 1 shown in FIG. 2 are read (# 31), and based on those signals, whether or not the hydrogen engine 1 is started, that is, an ignition. Whether or not is turned on from the off state is determined (# 32). As a result, if it is determined that the hydrogen engine 1 has been started, the process proceeds to step # 33. On the other hand, if it is determined that the hydrogen engine 1 has not been started, the process proceeds to step # 39.

In step # 33, it is determined whether or not the intake air temperature is less than 0 ° C. As a result, if it is determined that the intake air temperature is not less than 0 ° C., that is, greater than or equal to 0 ° C., the direct injection hydrogen injector I Assuming that the temperature of ₁ is equal to or higher than a predetermined temperature at which there is no possibility of freezing, the direct injection hydrogen injector I ₁ is driven (# 38), and gaseous hydrogen is injected into the working chamber. The process is returned as above. On the other hand, if it is determined that the intake air temperature is less than 0 ° C., the temperature of the direct injection hydrogen injector I ₁ is less than the predetermined temperature, and there is a possibility of freezing.

In step # 34, it is determined whether or not the intake air temperature is less than −10 ° C. As a result, if it is determined that the intake air temperature is less than −10 ° C., it is determined that the engine temperature is less than the predetermined temperature. , port-injection gasoline injector I ₂ is driven (# 35), the gasoline is injected into the intake passage 2. On the other hand, if it is determined that the intake air temperature is not lower than −10 ° C., that is, equal to or higher than −10 ° C., the port injection hydrogen injector I ₃ is driven assuming that the engine temperature is equal to or higher than the predetermined temperature ( # 37) Gaseous hydrogen is injected into the intake passage 2. After the step # 35 or # 37, icing measures port injection gasoline injector I ₂ or hydrogen injector I ₃ is used is performed once, as the startup has been completed, the flag (FLAG) is set to 1, the process Returned.

  Further, in step # 39, which proceeds when it is determined in step # 32 that it is not at the time of starting the hydrogen engine 1, the flag is confirmed, and whether or not the flag is 1, that is, whether or not the countermeasure for freezing has already been executed. As a result, if it is determined that the flag is 0, it is determined that there is no possibility of freezing, and the process proceeds to step # 42. On the other hand, if the flag is determined to be 1, the process continues. Then, it is determined whether or not a predetermined time has elapsed from the start completion time point when the flag is set to 1 (# 40).

  As a result of Step # 40, if it is determined that the predetermined time has elapsed, it is determined that the icing has already been resolved, and the process proceeds to Step # 42. On the other hand, if it is determined that the predetermined time has not elapsed, Subsequently, the previous injector, that is, the port injection gasoline injector or the hydrogen injector selected in step # 35 or # 37 is continuously driven (# 41). The process is returned as above.

In step # 42, it is determined whether or not the residual hydrogen pressure detected by the pressure sensor 17 (see FIG. 2) is greater than 0.5 MPa, and as a result, it is determined that the residual hydrogen pressure is greater than 0.5 MPa. In this case, it is assumed that the hydrogen remaining amount in the hydrogen storage tank 14 is sufficient, and the direct injection type hydrogen injector I ₁ and the port injection type hydrogen injector I ₃ are switched according to the engine speed described above with reference to FIG. Is performed (# 43). Also, whereas, if the hydrogen residual pressure is determined to be 0.5MPa or less, as is not sufficient the remaining amount of hydrogen in the hydrogen storage tank 14, a port injection gasoline injector I ₂ is driven (# 44 ), Gasoline is injected into the intake passage 2. After steps # 43 and # 44, the process is returned.

In the second injector drive control process, switching from the port injection type gasoline injector I ₂ or the hydrogen injector I ₃ to the direct injection type hydrogen injector I ₁ is performed when a predetermined time has elapsed from the start completion time.

As is apparent from the above description, according to the present invention, after the engine is stopped, the water generated by hydrogen combustion freezes in the vicinity of the front end of the direct injection hydrogen injector I ₁ and restarts in that state. Since gasoline or hydrogen is supplied by the injection type gasoline injector I ₂ or the hydrogen injector I ₃ , even if the direct injection type hydrogen injector I ₁ freezes, good engine startability is ensured.
Further, when it is estimated that the engine temperature rises after the low temperature start and the temperature of the direct injection hydrogen injector I ₁ rises and the icing is eliminated along with the temperature rise, the port injection type gasoline injector I ₂ or hydrogen Since the switching from the injector I ₃ to the direct injection hydrogen injector I ₁ is performed, high air-fuel ratio control accuracy can be ensured. That is, in the present embodiment, during hydrogen traveling, the air-fuel ratio is controlled so as to be in a lean state (λ = 2) in order to suppress NOx, but a direct injection injector I ₁ that can achieve higher air-fuel ratio control accuracy. By switching to, the air-fuel ratio can be maintained in the lean state with higher accuracy.
Further, when the engine temperature is lower than the predetermined temperature, the engine is started using the port injection type gasoline injector I ₂ , so that a greatly increased drive current is supplied to the intake passage hydrogen injection valve. This can prevent the power supply voltage from dropping when the engine is started.

It should be noted that the present invention is not limited to the illustrated embodiments, 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 first and second injector drive control processes described above with reference to FIGS. 5 and 6, the switching from the port injection type gasoline injector I ₂ or the hydrogen injector I ₃ to the direct injection type hydrogen injector I ₁ is completed when the start is completed. It may be done at the same time. When switching the injector, the air-fuel ratio changes, and the output change accompanying this may cause the driver to feel uncomfortable. However, when switching to the direct-injection hydrogen injector I ₁ is performed when the start is completed. The output change is recognized by the driver as a phenomenon at the time of starting the engine, and the above-mentioned uncomfortable feeling can be solved.

In step # 40 in the steps # 14 and 6 in FIG. 5, in order to estimate the temperature of the direct-injection hydrogen injector I ₁ rises above a predetermined temperature, respectively, starting the beginning and start completion time However, the present invention is not limited to this, and it may be determined whether the engine water temperature is equal to or higher than a predetermined temperature. In step # 34 in the steps # 15 and 6 in FIG. 5, in order to estimate that the port injection hydrogen injector I ₃ is the possibility of freezing, respectively, is determined based on the intake air temperature However, the determination may be made based on the engine water temperature without being limited thereto.

  Furthermore, in the above-described embodiment, the rotary engine is taken up as the hydrogen engine 1, but the present invention is not limited to this, and the present invention can also be applied to a reciprocating engine.

  A hydrogen engine control apparatus according to the present invention includes a vehicle such as an automobile, and includes a direct injection type hydrogen injector that directly injects gaseous hydrogen into a working chamber, and a port injection type gasoline injector that injects gasoline or gaseous hydrogen into an intake passage. Alternatively, the present invention can be applied to any device as long as an engine including a hydrogen injector is mounted.

1 is a diagram schematically showing a hydrogen engine according to an embodiment of the present invention. FIG. 2 is a diagram conceptually showing the hydrogen engine and a configuration related to the hydrogen engine. It is longitudinal cross-sectional explanatory drawing which shows the hydrogen injector in a closed state. It is longitudinal cross-sectional explanatory drawing which shows the hydrogen injector in an open state. It is explanatory drawing showing the hydrogen injector employ | adopted according to each engine speed, and its injection timing. It is a flowchart about the 1st injector drive control processing performed by a control unit. It is a flowchart about the 2nd injector drive control process performed by the control unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Intake passage, 3 ... Exhaust passage, 4 ... Injector main body, 5 ... Needle valve, 6 ... Solenoid coil, 7 ... Spark plug, 9 ... Hydrogen supply passage, 10 ... Control unit, 13 ... Gasoline supply passage, 14 ... hydrogen storage tank, 15 ... stop valve, 16 ... shutoff valve, 17 ... pressure sensor, 18 ... water temperature sensor, 19 ... engine speed sensor, 21 ... intake air temperature sensor, 22 ... oxygen sensor, _{I 1} ... Direct injection type hydrogen injector, I ₂ ... port injection type gasoline injector, I ₃ ... port injection type hydrogen injector, V ₁ , V ₂ , V ₃ ... solenoid valve.

Claims (5)

In an engine control device comprising a direct injection hydrogen injection valve that directly injects gaseous hydrogen into a working chamber, and an intake passage injection valve that supplies gaseous hydrogen or gasoline into the intake passage.
An engine control device characterized in that, when the engine is started at a low temperature, supply of hydrogen by the direct injection hydrogen injection valve is prohibited, and gaseous hydrogen or gasoline is supplied by the intake passage injection valve.   The fuel injection valve is switched from the intake passage injection valve to the direct injection hydrogen injection valve when it is estimated that the temperature of the direct injection hydrogen injection valve has risen above a predetermined temperature. Item 4. The engine control device according to Item 1.   The temperature of the direct injection hydrogen injection valve is estimated to have risen above a predetermined temperature when a predetermined time has elapsed from the start or completion of the cold start of the engine. Engine control device.   The engine control device according to claim 2 or 3, wherein when the engine temperature rises to a predetermined temperature or higher, it is estimated that the temperature of the direct injection hydrogen injection valve has risen to a predetermined temperature or higher. The intake passage injection valve is composed of a gasoline injection valve for supplying gasoline and a hydrogen injection valve for supplying gaseous hydrogen, and when it is determined that the engine temperature is equal to or higher than a predetermined temperature, The gas hydrogen is supplied from the hydrogen injection valve, and when it is determined that the engine temperature is lower than the predetermined temperature, the gasoline is supplied from the gasoline injection valve. The engine control device according to claim 1.

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