Internal combustion engine

Abstract

This design minimizes the impact on the output control of the internal combustion engine while preventing the hydrogen concentration in the crankcase from increasing. [Solution] The hydrogen-fueled internal combustion engine 10 includes an ignition device 200 that ignites the gas in the crankcase 19, a control device 100 that controls the ignition by the ignition device 200, and a hydrogen concentration sensor 58 that detects the hydrogen concentration in the crankcase 19. When the range of hydrogen concentration in the crankcase 19 that causes slow combustion is defined as the slow combustion range, the control device 100 performs an ignition process in which the ignition device 200 ignites the hydrogen when the hydrogen concentration detected by the hydrogen concentration sensor is within the slow combustion range.

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] In an internal combustion engine that uses hydrogen as fuel, since the blow-by gas flowing into the crankcase contains hydrogen, the hydrogen concentration in the crankcase may increase. Therefore, in the internal combustion engine described in Patent Document 1, for example, air is introduced into the crankcase from the downstream of the compressor wheel provided in the supercharger to dilute the gas in the crankcase. Then, the diluted gas is discharged into the intake passage upstream of the compressor wheel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the internal combustion engine described in Patent Document 1 above, since the diluted gas containing hydrogen is discharged into the intake passage, it may affect the output control of the internal combustion engine.

Means for Solving the Problems

[0005] The internal combustion engine that solves the above problems is an internal combustion engine that uses hydrogen as fuel, and includes an ignition device that ignites the gas in the crankcase and a control device that controls the ignition by the ignition device.

Effects of the Invention

[0006] According to this invention, it is possible to suppress an increase in the hydrogen concentration in the crankcase while suppressing the influence on the output control of the internal combustion engine. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of an internal combustion engine in one embodiment. [Figure 2] Figure 2 is a flowchart showing the procedure of processing performed by the control device of the same embodiment. [Modes for carrying out the invention]

[0008] The following describes one embodiment of an internal combustion engine. <Configuration of an internal combustion engine> As shown in Figure 1, the internal combustion engine 10 comprises a cylinder block 11, a cylinder head 12, and a head cover 13. Inside the cylinder block 11 is a cylinder 16 in which a piston 15 is arranged to reciprocate.

[0009] The cylinder head 12 is provided with an intake port 30 for introducing intake air into the combustion chamber 17 of the internal combustion engine 10, and an exhaust port 70 for discharging exhaust gas from the combustion chamber 17. An intake valve 81 is provided in the intake port 30. An exhaust valve 82 is provided in the exhaust port 70.

[0010] The cylinder head 12 is equipped with a fuel injector 84 that injects hydrogen, which is the fuel for the internal combustion engine 10, into the combustion chamber 17, and a spark plug 23. A crankcase 19 is provided at the lower part of the cylinder block 11, which houses the crankshaft 18 of the internal combustion engine 10.

[0011] The crankcase 19 is provided with an ignition device 200 that ignites the gas inside the crankcase 19. The ignition device 200 in this embodiment is a spark plug that produces a spark discharge. An intake manifold 29 equipped with a surge tank 60 is connected upstream of the intake port 30, and an intake pipe 20 is connected upstream of the surge tank 60. The surge tank 60 is equipped with an intake pressure sensor 53 for detecting the intake pressure PIM. The intake pressure PIM is the pressure inside the surge tank 60, which is the pressure downstream of the throttle valve 28 in the intake passage.

[0012] The intake pipe 20, surge tank 60, and intake manifold 29 constitute the intake passage of the internal combustion engine 10. The intake manifold 20 is equipped with, in order from upstream, an air cleaner 21, an air flow meter 51, a compressor wheel 24C of a supercharger 24 driven by exhaust gases from the combustion chamber 17, a boost pressure sensor 52, an intercooler 27, and a throttle valve 28.

[0013] The air cleaner 21 filters the intake air taken into the intake manifold 20. The air flow meter 51 detects the intake air volume GA of the internal combustion engine 10. The compressor wheel 24C of the supercharger 24 supercharges the intake air flowing through the intake passage. The boost pressure sensor 52 detects the boost pressure PTC, which is the pressure in the downstream portion of the compressor wheel 24C in the intake manifold 20. The intercooler 27 cools the air after it has passed through the compressor wheel 24C. The throttle valve 28 is a valve that adjusts the intake air volume of the internal combustion engine 10, and the opening of the valve is changed by an electric motor.

[0014] Downstream of the exhaust port 70, an exhaust passage 90 is connected. Partway along the exhaust passage 90, a housing for the turbine wheel 24T of the supercharger 24 is connected. The internal combustion engine 10 is equipped with a blow-by gas treatment mechanism that processes blow-by gas leaking from the combustion chamber 17 into the crankcase 19. This blow-by gas contains hydrogen fuel, lubricating oil for the internal combustion engine 10, and combustion gases of the fuel-air mixture.

[0015] The blow-by gas treatment mechanism includes a first communication passage 37. One end of the first communication passage 37 is connected to the intake pipe 20 between the air cleaner 21 and the compressor wheel 24C. The first communication passage 37 passes through the head cover 13, through the inside of the cylinder head 12 and cylinder block 11, and connects to the crankcase 19. A separator 38, which is an oil separator installed inside the head cover 13, is provided in the middle of the first communication passage 37. The first communication passage 37 and the separator 38 constitute a first passage that connects the portion of the intake passage upstream of the compressor wheel 24C to the crankcase 19.

[0016] The blow-by gas treatment mechanism includes a second communication passage 32 for guiding blow-by gas from the crankcase 19 to a separator 31, which is an oil separator provided in the head cover 13. The end of the second communication passage 32 connected to the separator 31 opens into the crankcase 19. Alternatively, the separator 31 may be located in the middle of the second communication passage 32.

[0017] The separator 31 is connected to the surge tank 60 via a differential pressure valve, a PCV (positive crankcase ventilation) valve 34, and a PCV passage 35. The PCV valve 34 opens when the pressure in the surge tank 60 becomes lower than the pressure in the separator 31, allowing blow-by gas to flow from the separator 31 to the surge tank 60. The pressure in the separator 31 is equal to the pressure in the crankcase 19. Therefore, the PCV valve 34 is a valve that opens when the intake pressure PIM becomes lower than the pressure in the crankcase 19.

[0018] The second communication passage 32, separator 31, PCV valve 34, and PCV passage 35 constitute a second passage that connects the portion of the intake passage downstream of the throttle valve 28 to the crankcase 19.

[0019] When the operating state of the internal combustion engine 10 is in the naturally aspirated region and the intake pressure PIM is lower than the atmospheric pressure, the pressure in the surge tank 60 becomes lower than the pressure in the crankcase 19. Therefore, the PCV valve 34 opens. When the PCV valve 34 opens, fresh air flows into the crankcase 19 from the intake pipe 20 through the first communication passage 37. Further, blow-by gas in the crankcase 19 is sucked into the surge tank 60 through the second communication passage 32, the separator 31, the PCV valve 34, and the PCV passage 35. The blow-by gas sucked into the surge tank 60 is sent to the combustion chamber 17 together with the intake air and burned. In the naturally aspirated region, the blow-by gas is processed in this way, so the hydrogen in the crankcase 19 is ventilated, and the hydrogen concentration in the crankcase 19 decreases.

[0020] The control device 100 controls the internal combustion engine 10 and operates various operation targets such as the throttle valve 28, the fuel injection valve 84, the ignition plug 23, and the ignition device 200. The control device 100 includes a CPU 110 that performs arithmetic processing, a memory 120 in which control programs and data are stored, and the like. Then, the control device 100 executes processes related to various controls by the CPU 110 executing the programs stored in the memory 120.

[0021] The detection signals of the above-described air flow meter 51, supercharging pressure sensor 52, and intake air pressure sensor 53 are input to the control device 100. Further, the detection signals of various other sensors are input to the control device 100. For example, the detection signal of a crank angle sensor 54 that detects the rotation angle (crank angle) of the crankshaft 18 is input to the control device 100 in order to calculate the engine speed NE. Further, the detection signal of an accelerator operation amount sensor 55 that detects an accelerator operation amount ACCP, which is an operation amount of an accelerator pedal for adjusting the output of the internal combustion engine 10, is input to the control device 100. Further, the detection signal of a throttle sensor 56 that detects a throttle opening TA, which is the opening of the throttle valve 28, is input to the control device 100. Further, the detection signal of a vehicle speed sensor 57 that detects the vehicle speed SP of the vehicle is input to the control device 100. Further, the detection signal of a hydrogen concentration sensor 58 that detects the hydrogen concentration H in the crankcase 19 is input to the control device 100.

[0022] The control device 100 calculates an engine load ratio KL based on the engine speed NE and the intake air amount GA. The engine load ratio KL is a parameter that determines the amount of air filled in the combustion chamber 17, and is a ratio of the intake air amount per one combustion cycle of one cylinder to the reference inflow air amount. The reference inflow air amount is variably set according to the engine speed NE.

[0023] <Regarding ignition processing> When the internal combustion engine 10 is operating in a supercharging region where supercharging is performed by the supercharger 24, the pressure in the crankcase 19 tends to be higher than the pressure in the intake pipe 20 between the air cleaner 21 and the compressor wheel 24C. Therefore, the inflow of fresh air from the intake pipe 20 into the crankcase 19 through the first communication passage 37 becomes difficult. Therefore, the hydrogen concentration in the crankcase 19 tends to increase.

[0024] Therefore, the control device 100 executes the ignition processing described below to suppress the occurrence of such inconveniences. Figure 2 shows the procedure for performing the ignition process. The process shown in Figure 2 is achieved by the CPU 110 repeatedly executing a program stored in the memory 120 of the control device 100 at predetermined intervals. In the following, the step number of each process is represented by a number preceded by "S".

[0025] When the process shown in Figure 2 is started, the control device 100 acquires the currently detected hydrogen concentration H (S100). Next, the control device 100 determines whether the acquired hydrogen concentration H is within the slow combustion range (S110). The slow combustion range is the range of hydrogen concentrations in which the hydrogen in the crankcase 19 ignites but burns slowly without causing a pressure increase, and is predetermined. For example, this slow combustion range can be defined as a range of approximately 8 vol% or less and approximately 4 vol% or more, which is the lower limit of the flammability limit of hydrogen.

[0026] If the acquired hydrogen concentration H is determined to be within the slow combustion range (S110: YES), the control device 100 operates the ignition device 200 to perform ignition (S120). Then, if the process in S120 is executed, or if the process in S110 is deemed negative, the control device 100 terminates the execution of this process for the current execution cycle.

[0027] <Operation and Effects of This Embodiment> (1) The hydrogen-fueled internal combustion engine 10 is equipped with an ignition device 200 that ignites the gas in the crankcase 19 and a control device 100 that controls the ignition by the ignition device 200. Therefore, it is possible to burn the blow-by gas in the crankcase 19 containing hydrogen by ignition by the ignition device 200 before the hydrogen concentration in the crankcase 19 becomes high. Thus, it is possible to suppress the increase in hydrogen concentration in the crankcase 19 while minimizing the impact on the output control of the internal combustion engine 10.

[0028] (2) Hydrogen has a slow combustion range, which is a range of hydrogen concentrations in which ignition occurs but combustion is slow without a pressure increase. Therefore, the internal combustion engine 10 of this embodiment has a hydrogen concentration sensor 58 that detects the hydrogen concentration H in the crankcase 19. Then, as shown in Figure 2, the control device 100 performs an ignition process in which the ignition device 200 ignites the hydrogen when the hydrogen concentration H detected by the hydrogen concentration sensor 58 is within the slow combustion range (S110: YES) (S120).

[0029] Therefore, when blow-by gas containing hydrogen in the crankcase 19 is burned by ignition by the ignition device 200, the hydrogen can be burned slowly without a rapid increase in pressure.

[0030] (3) The internal combustion engine 10 is equipped with a supercharger 24 that supercharges the intake air flowing through the intake passage. When the internal combustion engine 10 equipped with such a supercharger 24 is operated in the supercharging range, it is difficult to introduce fresh air into the crankcase 19. As a result, the hydrogen concentration in the crankcase 19 tends to increase. In this embodiment, an ignition device 200 that ignites the gas in the crankcase 19 is provided in the internal combustion engine 10 equipped with such a supercharger 24. As a result, even if the internal combustion engine 10 is equipped with a supercharger 24, it is possible to suppress the increase in hydrogen concentration.

[0031] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0032] The operating range in which the hydrogen concentration in the crankcase 19 falls within the slow combustion range can be determined through prior experiments. Therefore, when the internal combustion engine is operating in the operating range in which the hydrogen concentration in the crankcase 19 falls within the slow combustion range, ignition may be performed by the ignition device 200. Even in this case, when the blow-by gas in the crankcase 19 containing hydrogen is burned by ignition by the ignition device 200, the hydrogen can be burned slowly without a sudden increase in pressure. The above operating range can be defined, for example, by the engine speed and engine load ratio.

[0033] As described above, in an internal combustion engine 10 equipped with a supercharger 24, the hydrogen concentration in the crankcase 19 tends to increase when the engine is operating in the supercharged range. Therefore, when the internal combustion engine 10 is operating in such a supercharged range, an ignition process using the ignition device 200 may be performed. In this case, before the hydrogen concentration in the crankcase 19 increases, the blow-by gas in the crankcase 19 is burned by ignition from the ignition device 200, allowing the hydrogen to be burned gradually without a rapid pressure increase.

[0034] The ignition device 200 may be an ignition device other than a spark plug. In other words, the ignition device 200 may be any device that can ignite the gas in the crankcase 19, such as a heater.

[0035] The internal combustion engine 10 does not necessarily have to be equipped with a supercharger 24. That is, even in a naturally aspirated internal combustion engine, when the engine load increases, the inflow of fresh air from the intake manifold 20 through the first communication passage 37 into the crankcase 19 becomes difficult, so the hydrogen concentration in the crankcase 19 tends to increase. Therefore, even in such a naturally aspirated internal combustion engine, the same effects as in the above embodiment can be obtained by equipping it with the ignition device 200 and control device 100 described above.

[0036] The internal combustion engine 10 may be equipped with a fuel injection valve that injects fuel into the intake port 30. The control device 100 is not limited to one that includes a CPU and memory and performs software processing. For example, the control device 100 may include a dedicated hardware circuit, such as an ASIC, that performs hardware processing for at least a portion of what is processed by software in the above embodiment. That is, the control device 100 may include a processing circuit having any of the following configurations (a) to (c): (a) A processing circuit comprising one or more processing units that perform all of the above processing according to a program, and one or more program storage devices such as ROMs that store the program. (b) A processing circuit comprising one or more processing units and one or more program storage devices that perform a portion of the above processing according to a program, and one or more dedicated hardware circuits that perform the remaining processing. (c) A processing circuit comprising one or more dedicated hardware circuits that perform all of the above processing. The program storage device, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. [Explanation of Symbols]

[0037] 10... Internal combustion engine 15... Piston 16...Cylinder 18... Crankshaft 19... Crankcase 20... Intake pipe 23... Spark plug 24… Supercharger 27…Intercooler 28... Throttle valve 29…Intake manifold 30…Intake port 32…Second communication passage 34…PCV valve 35…PCV passage 37…1st communication passage 58…Hydrogen concentration sensor 60... Surge Tank 70... Exhaust port 81... Intake valve 82... Exhaust valve 84…Fuel injector 90... Exhaust passage 100...Control device 200…Ignition device

Claims

1. An internal combustion engine that uses hydrogen as fuel, An ignition device that ignites the gas inside the crankcase, The system includes a control device that controls ignition by the ignition device. Internal combustion engine.

2. The internal combustion engine has a sensor that detects the hydrogen concentration in the crankcase, When the range of hydrogen concentration in the aforementioned crankcase where slow combustion occurs is defined as the slow combustion range, The control device performs an ignition process in which the ignition device ignites the hydrogen when the hydrogen concentration detected by the sensor is within the slow combustion range. The internal combustion engine according to claim 1.

3. When the range of hydrogen concentration in the aforementioned crankcase where slow combustion occurs is defined as the slow combustion range, The control device performs an ignition process in which the ignition device ignites the engine when the internal combustion engine is operating in an operating range where the hydrogen concentration in the crankcase is within the slow combustion range. The internal combustion engine according to claim 1.

4. It is equipped with a supercharger that supercharges the intake air flowing through the intake passage. The internal combustion engine according to claim 1.

5. The control device performs ignition processing, which involves ignition by the ignition device, when the internal combustion engine is operating in the supercharged range where supercharging by the supercharger is occurring. The internal combustion engine according to claim 4.

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