Control device for internal combustion engines
The control device directs residual gaseous fuel into the intake passage by managing valve states, addressing leakage and ignition risks in internal combustion engines.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-08-25
- Publication Date
- 2026-05-19
AI Technical Summary
In internal combustion engines using gaseous fuel, the fuel supply passage pressure increases when the engine stops, leading to potential leakage and ignition risks in the exhaust passage due to residual fuel.
A control device that manages the fuel supply valve and injector nozzles based on crankshaft position, ensuring the intake valve is open and exhaust valve is closed to direct residual fuel into the intake passage, preventing leakage into the exhaust.
Prevents gaseous fuel from reaching the exhaust passage, reducing ignition risks and maintaining engine safety during shutdown.
Smart Images
Figure 0007861734000001 
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Figure 0007861734000003
Abstract
Description
Technical Field
[0001] This invention relates to a control device for an internal combustion engine.
Background Art
[0002] The internal combustion engine disclosed in Patent Document 1 includes a cylinder, an injector, a fuel tank, a fuel supply passage, and a valve. The fuel tank stores gaseous fuel. The fuel supply passage connects the fuel tank and the injector. The valve is located in the middle of the fuel supply passage. The valve opens and closes the fuel supply passage. During operation of the internal combustion engine, the valve is in an open state. In this case, the gaseous fuel in the fuel tank is supplied to the injector through the fuel supply passage. Then, the injector injects the gaseous fuel into the cylinder. On the other hand, when the operation of the internal combustion engine is stopped, the valve is in a closed state.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In a technique such as Patent Document 1 that supplies gaseous fuel to an injector through a fuel supply passage, when the valve is closed with the stop of the operation of the internal combustion engine, the inside of the fuel supply passage between the valve and the injector becomes high pressure due to the gaseous fuel remaining in the fuel supply passage. Also, in the case of gaseous fuel, compared with liquid fuel, leakage of the gaseous fuel from the injection port of the injector into the cylinder is likely to occur. If the gaseous fuel that has leaked into the cylinder reaches the high-temperature exhaust passage immediately after the operation of the internal combustion engine stops, it is impossible to rule out the possibility of the gaseous fuel igniting in the exhaust passage.
Means for Solving the Problems
[0005] A control device for an internal combustion engine to solve the above problems is: Crankshaft and An engine body comprising multiple cylinders, and an intake passage connected to each of the said cylinders, A surge tank located in the middle of the intake passage and storing a certain volume of gas, An exhaust passage connected to each of the aforementioned cylinders, and a connection port to the cylinder in the intake passage provided for each of the aforementioned cylinders In accordance with the rotation of the crankshaft An intake valve that opens and closes, and a connection port to the cylinder in the exhaust passage provided for each cylinder In accordance with the rotation of the crankshaft An exhaust valve that opens and closes, and provided for each cylinder ,air Injecting fuel The injection nozzle is located inside the cylinder. An injector, a fuel tank storing gaseous fuel, a fuel supply passage connecting the fuel tank and the injector for each cylinder, and a fuel supply valve provided on the fuel tank side of the branching point to the injector for each cylinder in the fuel supply passage, for opening and closing the fuel supply passage. A pressure sensor that detects the internal pressure in the portion of the fuel supply passage between the fuel supply valve and the branching point, and a crank position sensor that outputs a signal indicating the rotational phase of the crankshaft, Applicable to an internal combustion engine equipped with, when stopping the operation of the internal combustion engine, In conjunction with closing all of the injector nozzles, A first process of closing the fuel supply valve, When a target cylinder is selected from among the multiple cylinders in which the exhaust valve is closed and the intake valve is open, when the rotation of the crankshaft stops, the nozzles of all the injectors corresponding to the target cylinder are opened while the nozzles of all the remaining injectors are closed until the internal pressure of the fuel supply passage falls below a set value. The second process, When the internal pressure of the fuel supply passage falls below the set value, the process of closing all the injector nozzles is performed. And, execute Furthermore, the aforementioned setting value is predetermined as a value such that gaseous fuel does not leak from the injection port of each injector into the cylinder when all the injection ports of the injectors are closed. [Effects of the Invention]
[0006] The above technical concept prevents gaseous fuel from reaching the exhaust passage after the internal combustion engine has been shut down. [Brief explanation of the drawing]
[0007] [Figure 1] Figure 1 is a schematic diagram showing the general configuration of an internal combustion engine. [Figure 2] Figure 2 is a schematic diagram showing the general configuration of an internal combustion engine. [Figure 3] Figure 3 is a schematic diagram showing the configuration of the injector. [Figure 4] Figure 4 is a flowchart illustrating the purging process. [Modes for carrying out the invention]
[0008] Hereinafter, one embodiment of a control device for an internal combustion engine will be described with reference to the drawings. <Overall structure of an internal combustion engine> Vehicle 500 is equipped with an internal combustion engine 100. The internal combustion engine 100 is the power source for vehicle 500.
[0009] As shown in Figures 1 and 2, the internal combustion engine 100 comprises an engine body 10, a plurality of cylinders 11, a plurality of pistons 12, a plurality of connecting rods 13, and a crankshaft 14. Note that Figure 1 shows only one of the plurality of cylinders 11. The same applies to the pistons 12 and connecting rods 13. In this embodiment, there are four cylinders 11: cylinder #1, cylinder #2, cylinder #3, and cylinder #4.
[0010] Cylinder 11 is a space partitioned within the engine body 10. A mixture of intake air and gaseous fuel burns inside cylinder 11. A piston 12 is provided for each cylinder 11. The piston 12 is located inside cylinder 11. The piston 12 reciprocates inside cylinder 11. The piston 12 is connected to the crankshaft 14 via a connecting rod 13. The crankshaft 14 rotates in accordance with the movement of the piston 12. The crankshaft 14 is connected to the drive wheels 502 via an automatic transmission 501 or the like. The internal combustion engine 100 is a four-stroke, one-cycle engine in which the intake stroke, compression stroke, expansion stroke, and exhaust stroke in each cylinder 11 complete one cycle by rotating the crankshaft 14 720 degrees.
[0011] As shown in Figures 1 and 2, the internal combustion engine 100 is equipped with multiple spark plugs 19. Note that Figure 1 shows only one of the multiple spark plugs 19. A spark plug 19 is provided for each cylinder 11. The tip of the spark plug 19 is located inside the cylinder 11. The spark plug 19 ignites the fuel-air mixture inside the cylinder 11. In this embodiment, the four spark plugs 19 ignite in the order of cylinder 1 #1, cylinder 3 #3, cylinder 4 #4, and cylinder 2 #2. In other words, the four cylinders 11 undergo the expansion stroke associated with the combustion of the fuel-air mixture in the order of cylinder 1 #1, cylinder 3 #3, cylinder 4 #4, and cylinder 2 #2.
[0012] As shown in Figures 1 and 2, the internal combustion engine 100 is equipped with multiple injectors 50. Note that Figure 1 shows only one of the multiple injectors 50. An injector 50 is provided for each cylinder 11. The injection port 54 of the injector 50 is located inside the cylinder 11. That is, the injector 50 injects fuel directly into the cylinder 11 without going through the intake passage 41, which will be described later. The injector 50 injects hydrogen, which is a gaseous fuel.
[0013] As shown in Figure 1, the internal combustion engine 100 includes an intake passage 41, an air cleaner 43, a throttle valve 44, and a surge tank 45. The intake passage 41 is a passage for introducing intake air to each cylinder 11. The intake passage 41 is connected to each cylinder 11. The air cleaner 43 is located in the middle of the intake passage 41. The air cleaner 43 filters the intake air taken into the intake passage 41. The throttle valve 44 is located downstream of the air cleaner 43 in the intake passage 41. The throttle valve 44 adjusts the amount of intake air. The surge tank 45 is located downstream of the throttle valve 44 in the intake passage 41. The surge tank 45 stores a certain volume of intake air.
[0014] The internal combustion engine 100 includes a plurality of intake valves 15 and an intake valve operating mechanism 25. In FIG. 1, only one of the plurality of intake valves 15 is shown. The intake valve 15 is provided for each cylinder 11. The intake valve 15 is located at the connection port of the intake passage 41 with the cylinder 11. This connection port is also referred to as the opening on the cylinder 11 side in the intake passage 41. The intake valve operating mechanism 25 includes an intake camshaft 25A. The intake camshaft 25A rotates in conjunction with the crankshaft 14. The intake camshaft 25A rotates once while the crankshaft 14 rotates twice. The intake valve 15 operates in accordance with the rotation of the intake camshaft 25A. By this operation, the intake valve 15 opens and closes the above connection port between the intake passage 41 and the cylinder 11. When the intake valve 15 is in the open state, the intake valve 15 is separated from the above connection port between the intake passage 41 and the cylinder 11, and the opening degree of the intake valve 15 is greater than 0%. On the other hand, when the intake valve 15 is in the closed state, the intake valve 15 contacts the above connection port between the intake passage 41 and the cylinder 11, and the opening degree of the intake valve 15 is 0%.
[0015] The internal combustion engine 100 includes an exhaust passage 49 and an oxidation catalyst. The exhaust passage 49 is a passage for discharging exhaust from each cylinder 11. The exhaust passage 49 is connected to each cylinder 11. Although not shown, the oxidation catalyst is located in the middle of the exhaust passage 49. The oxidation catalyst oxidizes the components contained in the exhaust.
[0016] The internal combustion engine 100 includes a plurality of exhaust valves 16 and an exhaust valve operating mechanism 26. In FIG. 1, only one of the plurality of exhaust valves 16 is shown. The exhaust valve 16 is provided for each cylinder 11. The exhaust valve 16 is located at the connection port of the exhaust passage 49 with the cylinder 11. This connection port is also referred to as the opening on the cylinder 11 side in the exhaust passage 49. The exhaust valve operating mechanism 26 includes an exhaust camshaft 26A. The exhaust camshaft 26A rotates in conjunction with the crankshaft 14. The exhaust camshaft 26A rotates once while the crankshaft 14 rotates twice. The exhaust valve 16 operates in response to the rotation of the exhaust camshaft 26A. By this operation, the exhaust valve 16 opens and closes the connection port between the exhaust passage 49 and the cylinder 11. When the exhaust valve 16 is in the open state, the exhaust valve 16 is separated from the connection port between the exhaust passage 49 and the cylinder 11, and the opening degree of the exhaust valve 16 is greater than 0%. On the other hand, when the exhaust valve 16 is in the closed state, the exhaust valve 16 contacts the connection port between the exhaust passage 49 and the cylinder 11, and the opening degree of the exhaust valve 16 is 0%.
[0017] <Fuel supply system> As shown in FIG. 2, the internal combustion engine 100 includes a fuel tank 71, a main passage 72, a delivery pipe 73, a plurality of branch passages 74, a fuel supply valve 76, and a pressure regulator 77. The main passage 72, the delivery pipe 73, and the branch passages 74 constitute a fuel supply passage 75. The branch passage 74 is provided for each injector 50.
[0018] The fuel tank 71 stores hydrogen, which is a gaseous fuel. The main passage 72 connects the fuel tank 71 to the delivery pipe 73. The delivery pipe 73 connects to each injector 50 via branch passages 74 for each injector 50. The pressure regulator 77 is located in the middle of the main passage 72. The pressure regulator 77 adjusts and releases the pressure of the gaseous fuel. The fuel supply valve 76 is located in the main passage 72, closer to the fuel tank 71 than the pressure regulator 77. The fuel supply valve 76 is a valve that opens and closes in response to a command signal from the control device 110, which will be described later. For example, the fuel supply valve 76 is a normally closed solenoid valve. When the fuel supply valve 76 is closed, the fuel supply from the fuel tank 71 to each injector 50 is cut off. When the fuel supply valve 76 is open, gaseous fuel is supplied from the fuel tank 71 to each injector 50.
[0019] <Injector> The structure of each injector 50 is identical. Below, we will describe the details of one of the four injectors 50.
[0020] As shown in Figure 3, the injector 50 comprises a housing 52, a nozzle valve 57, an electromagnetic solenoid 58, a drive circuit 59, and a spring. Note that the spring is not shown in Figure 3.
[0021] Inside the housing 52, there is a housing passage 53 through which gaseous fuel flows. The housing passage 53 extends in a straight line. The end of the housing passage 53 opens to the outside of the housing 52. This opening is an injection port 54 that connects the inside and outside of the housing 52. The portion of the housing passage 53 just before the injection port 54 is a sloping seat surface 55 that tapers as it approaches the injection port 54.
[0022] The nozzle valve 57 is located in the housing passage 53. The nozzle valve 57 is capable of moving closer to and further away from the seat surface 55. The nozzle valve 57 is subjected to a biasing force from a spring. This biasing force presses the nozzle valve 57 against the seat surface 55.
[0023] The electromagnetic solenoid 58 drives the operation of the nozzle valve 57. When the electromagnetic solenoid 58 is energized, the nozzle valve 57 moves away from the seat surface 55 against the biasing force of the spring. As a result, the injection port 54 opens, and gaseous fuel is injected from the injection port 54. On the other hand, when the energization of the electromagnetic solenoid 58 is stopped, the nozzle valve 57 seats back onto the seat surface 55 due to the biasing force of the spring. As a result, the injection port 54 closes, and the injection of gaseous fuel from the injection port 54 stops.
[0024] The drive circuit 59 is interposed between a battery (not shown) mounted on the vehicle 500 and the electromagnetic solenoid 58. The drive circuit 59 is an electrical circuit and includes switches, etc. The drive circuit 59 turns the power supply to the electromagnetic solenoid 58 on and off in response to command signals from the control device 110, which will be described later.
[0025] <Sensor> As shown in Figure 1, the internal combustion engine 100 is equipped with a pressure sensor 91. The pressure sensor 91 detects the internal pressure of the delivery pipe 73. The pressure sensor 91 outputs a signal P corresponding to the detected information.
[0026] The internal combustion engine 100 includes a sensor plate 167 and a crank position sensor 92. The sensor plate 167 rotates integrally with the crankshaft 14. Multiple teeth 168 are formed on the outer circumference of the sensor plate 167. The multiple teeth 168 are basically arranged at equal intervals. However, there is one missing tooth section 169 where the spacing between adjacent teeth 168 is larger than the others. The crank position sensor 92 is positioned opposite the outer circumference of the sensor plate 167. The crank position sensor 92 outputs an L signal when it is facing the teeth 168 of the sensor plate 167, and outputs an H signal when it is facing the gap between adjacent teeth 168. Therefore, corresponding to the arrangement of the teeth 168 described above, the crank position sensor 92 basically outputs L signals and H signals alternately at a constant normal interval. Then, at the location corresponding to the missing tooth section 169, the crank position sensor 92 outputs an H signal with a longer interval than the normal interval as a missing tooth signal. Hereinafter, the signals output by the crank position sensor 92 will be collectively referred to as the crank signal CR. In this case, in conjunction with the order of the expansion strokes in each cylinder 11 as described above, the piston 12 of the first cylinder #1 and the piston 12 of the fourth cylinder #4 are located at top dead center at the same time. In this embodiment, the position of the missing tooth portion 169 is determined such that the crank signal CR switches from a missing tooth signal to an L signal before and after the piston 12 of the first cylinder #1 and the piston 12 of the fourth cylinder #4 reach top dead center.
[0027] The internal combustion engine 100 includes a rotor plate 31 and a cam position sensor 93. The rotor plate 31 rotates integrally with the intake camshaft 25A. Three fan-shaped protrusions 32 are formed on the outer circumference of the rotor plate 31. The three protrusions 32 extend outwards in different circumferential directions. The spacing between adjacent protrusions 32 is also different. The cam position sensor 93 is positioned opposite the outer circumference of the rotor plate 31. The cam position sensor 93 outputs an L signal when it is facing each protrusion 32 and an H signal when it is facing the gap between adjacent protrusions 32. When the largest protrusion, which occupies the largest area of the three protrusions 32, passes in front of the cam position sensor 93, it outputs an L signal at a longer interval than when the other protrusions 32 pass. Hereinafter, the L signal output by the cam position sensor 93 when the large protrusion passes in front of the cam position sensor 93 will be referred to as the longest signal. Furthermore, in the following, all signals output by the cam position sensor 93 will be collectively referred to as the cam signal M. In this embodiment, the positions of each projection 32 are determined so that the cam signal M switches from the longest signal to the H signal before and after the piston 12 of the first cylinder #1 reaches top dead center. Incidentally, since the intake camshaft 25A rotates once for every two rotations of the crankshaft 14, the outer circumference of the rotor plate 31 that the cam position sensor 93 faces differs when the piston 12 of the first cylinder #1 is at top dead center compared to when the piston 12 of the fourth cylinder #4 is at top dead center. Therefore, when the cam signal M switches from the longest signal to the H signal, the piston 12 of the fourth cylinder #4 is not at top dead center.
[0028] Vehicle 500 is equipped with an ignition switch 99. The ignition switch 99 outputs a signal G in response to the occupant's operation. <Control device> As shown in Figure 1, the vehicle 500 is equipped with a control device 110. The control device 110 may be configured as one or more processors that execute various processes according to a computer program (software). Alternatively, the control device 110 may be configured as a circuit including one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), or a combination thereof, that execute at least some of the various processes. The processor includes a CPU 112 and memory 114 such as RAM and ROM. Memory 114 stores program code or instructions configured to cause the CPU 112 to execute processes. Memory 114, or computer-readable media, includes any available media that can be accessed by a general-purpose or dedicated computer. Memory 114 includes electrically rewritable non-volatile memory.
[0029] The control device 110 repeatedly receives signals from the various sensors in the internal combustion engine 100. Based on the information received from the various sensors, the control device 110 understands the operating state of the internal combustion engine 100. For example, the control device 110 understands the open / closed state of the intake valve 15 and exhaust valve 16 based on the crank signal CR and the cam signal M. In this embodiment, the control device 110 understands the open / closed state of the intake valve 15 and exhaust valve 16 in the following manner as an example. The control device 110 repeatedly calculates the crank angle CA, which indicates the rotational phase of the crankshaft 14, based on the crank signal CR and the cam signal M. The crank angle CA takes values from 0 degrees to 720 degrees. The control device 110 calculates the crank angle CA starting from a predetermined reference angular position. The reference angular position is, for example, the angular position of the crankshaft 14 when the piston 12 of the first cylinder #1 is at top dead center of compression. By calculating the crank angle CA starting from a reference angular position, the crank angle CA reflects the phase of each cylinder 11. The control device 110 can determine the reference angular position by combining the crank signal CR and the cam signal M. For example, the control device 110 can determine that the piston 12 of the first cylinder #1 is at top dead center when the crank signal CR switches from a missing tooth signal to an L signal and the cam signal M switches from a longest signal to an H signal. In this embodiment, as an example, the opening and closing timing of the intake valve 15 and exhaust valve 16 during the operation of the internal combustion engine 100 is fixed to a constant value. That is, the crank angle CA at which the intake valve 15 switches from a closed state to an open state, and the crank angle CA at which the intake valve 15 switches from an open state to a closed state are predetermined for each cylinder 11. Similarly, in this embodiment, the crank angle CA at which the exhaust valve 16 switches from a closed state to an open state, and the crank angle CA at which the exhaust valve 16 switches from an open state to a closed state, are predetermined for each cylinder 11. The control device 110 stores in advance the crank angle CA that determines the opening and closing timing of these intake valves 15 and exhaust valves 16. Therefore, the control device 110 can determine the open and closed states of the intake valves 15 and exhaust valves 16 by referring to the current crank angle CA.
[0030] The control device 110 controls various parts of the internal combustion engine 100. For example, the control device 110 controls the injector 50. Specifically, the control device 110 controls the power supply to the electromagnetic solenoid 58 by outputting a command signal to the drive circuit 59. The control device 110 also controls the opening and closing of the fuel supply valve 76. The control device 110 opens the fuel supply valve 76 while the internal combustion engine 100 is running. On the other hand, the control device 110 closes the fuel supply valve 76 when the internal combustion engine 100 is stopped.
[0031] The control device 110 receives a signal G from the ignition switch 99. When the control device 110 receives a signal G corresponding to the ignition switch 99 being turned ON, it starts operating the internal combustion engine 100. While the internal combustion engine 100 is running, the control device 110 adjusts the opening of the throttle valve 44, injects gaseous fuel from each injector 50, and ignites with each spark plug 19. In this way, the control device 110 burns the fuel-air mixture in each cylinder 11.
[0032] On the other hand, when the control device 110 receives a signal G corresponding to the ignition switch 99 being turned off, it stops the operation of the internal combustion engine 100. At this time, the control device 110 performs the following series of processes. First, the control device 110 stops ignition by each spark plug 19 and fuel injection by each injector 50. Specifically, when stopping fuel injection, the control device 110 closes the injection port 54 of each injector 50 by stopping the power supply to the electromagnetic solenoid 58 of each injector 50. In addition, the control device 110 closes the fuel supply valve 76 in conjunction with stopping fuel injection. The process by which the control device 110 closes the fuel supply valve 76 is the first process. After this, the control device 110 waits until the rotation of the crankshaft 14 stops. The control device 110 can determine when the rotation of the crankshaft 14 has stopped based on the crank signal CR. When the rotation of the crankshaft 14 stops, the control device 110 starts the purging process described below. The control device 110 remains in the running state until the purging process is completed.
[0033] As shown in Figure 4, when the control device 110 starts the purging process, it first executes the process in step S10. In step S10, the control device 110 identifies the target cylinder. The target cylinder is one of the multiple cylinders 11 in which the exhaust valve 16 is closed while the intake valve 15 is open. The control device 110 determines the current open / closed state of the intake valve 15 and exhaust valve 16 of each cylinder 11 by referring to the current crank angle CA. Then, the control device 110 identifies the target cylinder. Depending on the setting of the opening and closing timing of the intake valve 15 and exhaust valve 16, there may be multiple target cylinders corresponding to the current crank angle CA. In this case, the control device 110 identifies all of these multiple target cylinders. After this, the control device 110 proceeds to step S20. Furthermore, if in step S10 there are no target cylinders corresponding to the current crank angle CA, the control device 110 cancels the processing from step S20 onward and terminates the purging process.
[0034] In step S20, the control device 110 starts energizing the electromagnetic solenoid 58 of the injector 50 corresponding to the target cylinder identified in step S10. This causes the control device 110 to open the injection port 54 of the injector 50 for the target cylinder. If the control device 110 identified multiple target cylinders in step S10, it starts energizing the electromagnetic solenoid 58 of the injectors 50 for all of these target cylinders. On the other hand, the control device 110 does not energize the electromagnetic solenoid 58 of all injectors 50 other than the target cylinder identified in step S10. In other words, the control device 110 closes the injection ports 54 of all the remaining injectors 50. The remaining injectors 50 include injectors 50 corresponding to cylinders 11 where the exhaust valve 16 is open, and injectors 50 corresponding to cylinders 11 where both the exhaust valve 16 and the intake valve 15 are closed. When the control device 110 starts energizing the electromagnetic solenoid 58 of the injector 50 corresponding to the target cylinder, it proceeds to step S30. The "injector 50 corresponding to cylinder 11" refers to the injector 50 that supplies fuel to that cylinder 11.
[0035] In step S30, the control device 110 determines whether the latest value of the internal pressure of the delivery pipe 73 detected by the pressure sensor 91 is below a set value. The control device 110 has a set value stored in advance. The set value is predetermined, for example, through experimentation or simulation, as the value at which gaseous fuel does not leak from the injection port 54 of each injector 50 into the cylinder 11 when all the injection ports 54 of the injectors 50 are closed. If the internal pressure of the delivery pipe 73 is greater than the set value (step S30: NO), the control device 110 executes the process in step S30 again. The control device 110 repeats the process in step S30 until the internal pressure of the delivery pipe 73 is below the set value. Then, when the internal pressure of the delivery pipe 73 is below the set value (step S30: YES), the control device 110 proceeds to step S40.
[0036] In step S40, the control device 110 terminates the energization of the electromagnetic solenoid 58, which was energized in step S20. Consequently, the injection nozzles 54 of all injectors 50, including the target cylinder, are closed. After this, the control device 110 completes the series of purging processes.
[0037] Regarding the purging process described above, the second process involves the control device 110 opening the injection port 54 of the target cylinder's injector 50 while closing the injection ports 54 of all remaining injectors 50. The control device 110 starts the second process in step S20 and ends it in step S40.
[0038] <Operation of the Embodiment> Now, let's assume that the control device 110 has received a signal G corresponding to the ignition switch 99 being turned off. Accordingly, let's assume that the control device 110 has stopped fuel injection by the injectors 50 in order to stop the internal combustion engine 100. At this time, gaseous fuel may remain under high pressure in the portion of the fuel supply passage 75 between the fuel supply valve 76 and each injector 50, such as the delivery pipe 73. The control device 110 releases this gaseous fuel into the intake passage 41 by purging. That is, in the purging process, the control device 110 opens only the injection port 54 of the injector 50 corresponding to the target cylinder. For example, let's assume that the target cylinder is cylinder #1 of the four cylinders 11 in Figure 2. In this case, the control device 110 opens only the injection port 54 of the injector 50 corresponding to cylinder #1. As shown by arrow L1 in Figure 2, the gaseous fuel remaining in the fuel supply passage 75 flows only into the target cylinder, cylinder #1. Here, as shown by the dashed line Q in Figure 1, the exhaust valve 16 is closed in the target cylinder. Therefore, the gaseous fuel that flows into the target cylinder does not reach the exhaust passage 49. On the other hand, the intake valve 15 is open in the target cylinder. Therefore, as shown by arrow L2 in Figure 1, the gaseous fuel that flows into the target cylinder flows out into the intake passage 41.
[0039] <Effects of the Embodiment> (1) As described in the operation of the above embodiment, in the configuration of this embodiment, when the operation of the internal combustion engine 100 is stopped, the gaseous fuel remaining in the fuel supply passage 75 is allowed to flow only into the target cylinder. Since the exhaust valve 16 is closed in this target cylinder, it is possible to prevent this gaseous fuel from flowing out into the exhaust passage 49.
[0040] (2) When stopping the operation of the internal combustion engine 100, suppose the injection port 54 of the injector 50 corresponding to the cylinder 11 in which both the intake valve 15 and the exhaust valve 16 are closed is opened. Then, the gaseous fuel remaining in the fuel supply passage 75 is allowed to flow into this cylinder 11. In this case, a high concentration of gaseous fuel remains in this cylinder 11 until the internal combustion engine 100 is started again. If such a high concentration of gaseous fuel remains in the cylinder 11, various problems may occur, such as abnormal combustion occurring in the cylinder 11 when the internal combustion engine 100 is started again.
[0041] In this embodiment, the gaseous fuel remaining in the fuel supply passage 75 is introduced into the target cylinder where the exhaust valve 16 is closed and the intake valve 15 is open. Since the intake valve 15 is open in the target cylinder, the gaseous fuel that has entered the target cylinder flows out into the intake passage 41. The intake passage 41 has a large overall volume, for example, because it includes a surge tank 45, an air cleaner 43, etc. Therefore, the gaseous fuel that flows out into the intake passage 41 diffuses within the intake passage 41. As a result, the concentration of the gaseous fuel becomes sufficiently dilute.
[0042] <Example of changes> The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.
[0043] Regarding the second process, if there are multiple target cylinders, it is not necessary to open the injection nozzles 54 of the injectors 50 for all of these target cylinders. It is sufficient to open the injection nozzles 54 of the injectors 50 for one or more target cylinders.
[0044] The method for determining the duration of the second process is not limited to referring to the internal pressure of the delivery pipe 73 itself, as in step S30 of the above embodiment. For example, the set time required for the internal pressure of the delivery pipe 73 to drop below a set value may be determined in advance through experiments or other means. Then, the second process may be completed when the set time has elapsed after the completion of the process in step S20.
[0045] During operation of the internal combustion engine 100, the opening and closing timing of the intake valve 15 may be changed by altering the relative rotational phase of the intake camshaft 25A with respect to the crankshaft 14. In this case, the open or closed state of the intake valve 15 can be determined by understanding the amount of change in the relative rotational phase and adding that change to the base opening and closing timing. The same applies to the exhaust valve 16.
[0046] A cylinder 11 in which the exhaust valve 16 is closed is referred to as a closed cylinder. The purging process can be configured to open the injection port 54 of the injector 50 corresponding to one or more closed cylinders, and to close the injection port 54 of the injector 50 corresponding to the cylinder 11 in which the exhaust valve 16 is open. The closed cylinder in which the injection port 54 of the injector 50 is opened is not limited to the target cylinder, but may also be a cylinder 11 in which the intake valve 15 is closed. Even if the injection port 54 of the injector 50 of a closed cylinder in which the intake valve 15 is closed is opened, the exhaust valve 16 is closed in this closed cylinder, so the effect of (1) above can be enjoyed.
[0047] The method for identifying the target cylinder and the closed cylinder is not limited to the example of the above embodiment using the crank angle CA. Any method for identifying the target cylinder and the closed cylinder is acceptable as long as they can be identified.
[0048] The period from when the ignition switch 99 is turned ON until it is turned OFF is referred to as one trip. During this trip, if the vehicle 500 comes to a temporary stop, the control device 110 may automatically stop and restart the internal combustion engine 100. A purge process may be performed when such an automatic stop occurs.
[0049] • Gaseous fuels are not limited to hydrogen. The overall configuration of the internal combustion engine 100 is not limited to the example of the above embodiment. For example, the number of cylinders 11 may be changed from the example of the above embodiment. The injector 50 may be changed to a type that supplies gaseous fuel into the cylinders 11 via the intake passage 41. The injector 50 only needs to be able to inject gaseous fuel to be supplied into the cylinders 11. [Explanation of symbols]
[0050] 10…Engine body 11 cylinders 15…Intake valve 16… Exhaust valve 41…Intake passage 49... Exhaust passage 50... Injector 71…Fuel tank 75…Fuel supply passage 76…Fuel supply valve 100... Internal combustion engine 110...Control device
Claims
[Claim 1] A crankshaft, an engine body comprising a plurality of cylinders, an intake passage connected to each of the cylinders, a surge tank located in the middle of the intake passage and storing a certain volume of gas, an exhaust passage connected to each of the cylinders, an intake valve provided for each cylinder which opens and closes the connection port to the cylinder in the intake passage in accordance with the rotation of the crankshaft, an exhaust valve provided for each cylinder which opens and closes the connection port to the cylinder in the exhaust passage in accordance with the rotation of the crankshaft, and an injection port provided for each cylinder which injects gaseous fuel This invention is applied to an internal combustion engine comprising: an injector located within the cylinder; a fuel tank storing gaseous fuel; a fuel supply passage connecting the fuel tank and the injector for each cylinder; a fuel supply valve provided on the fuel tank side of the branching point to the injector for each cylinder in the fuel supply passage, which opens and closes the fuel supply passage; a pressure sensor that detects the internal pressure in the portion of the fuel supply passage between the fuel supply valve and the branching point; and a crank position sensor that outputs a signal indicating the rotational phase of the crankshaft. When stopping the operation of the internal combustion engine, A first process involves closing the fuel supply valve in conjunction with closing all the injector nozzles, When, among the multiple cylinders, the cylinder in which the exhaust valve is closed while the intake valve is open is designated as the target cylinder, When the rotation of the crankshaft stops, a second process is performed in which the nozzles of all the injectors corresponding to the target cylinders are opened while the nozzles of all the remaining injectors are closed until the internal pressure of the fuel supply passage falls below a set value. When the internal pressure of the fuel supply passage falls below the set value, the process of closing all the injector nozzles is performed. Execute, The aforementioned setting value is predetermined as a value such that gaseous fuel does not leak from the injection port of each injector into the cylinder when all the injection ports of the injectors are closed. Control device for internal combustion engines.