Internal combustion engine

Abstract

To treat blow-by gas while adjusting an intake air amount of an internal combustion engine with a simple configuration.SOLUTION: An internal combustion engine 10 has: an intake passage; a throttle valve 28 provided in the intake passage; a flow control valve 40 provided in the intake passage downstream of the throttle valve 28; a first passage communicating the intake passage between the throttle valve 28 and the flow control valve 40 with a crankcase 19; and a second passage communicating the intake passage downstream of the flow control valve 40 with the crankcase 19.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an internal combustion engine.

Background Art

[0002] For example, the internal combustion engine described in Patent Document 1 includes a flow rate adjustment valve provided in an intake passage, a first passage that communicates the intake passage upstream of the flow rate adjustment valve with a crankcase, and a second passage that communicates the intake passage downstream of the flow rate adjustment valve with the crankcase. Then, by adjusting the opening degree of the flow rate adjustment valve, blow-by gas treatment is performed to introduce blow-by gas in the crankcase into the intake passage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the internal combustion engine described in Patent Document 1, the intake air amount is adjusted using a complicated mechanism such as a variable valve mechanism. Therefore, it is desired to adjust the intake air amount of the internal combustion engine with a simpler configuration while treating blow-by gas.

Means for Solving the Problems

[0005] The internal combustion engine that solves the above problems includes an intake passage, a throttle valve provided in the intake passage, a flow rate adjustment valve provided downstream of the throttle valve in the intake passage, a first passage that communicates the intake passage between the throttle valve and the flow rate adjustment valve with a crankcase, and a second passage that communicates the intake passage downstream of the flow rate adjustment valve with the crankcase.

Effects of the Invention

[0006] This internal combustion engine can process blow-by gas while adjusting the intake air amount of the internal combustion engine with a simple configuration.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0008] Hereinafter, an embodiment in which an internal combustion engine mounted on a vehicle is embodied will be described. <Configuration of the Internal Combustion Engine> As shown in FIG. 1, the internal combustion engine 10 includes a cylinder block 11, a cylinder head 12, a head cover 13, and an oil pan 14. Inside the cylinder block 11, a cylinder 16 in which a piston 15 is reciprocally arranged is provided.

[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 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 provided with a port injection valve 83 for injecting hydrogen gas, which is engine fuel, into the intake port 30, an in-cylinder injection valve 84 for directly injecting hydrogen gas, which is engine fuel, into the combustion chamber 17, and a spark plug (not shown).

[0011] At the lower part of the cylinder block 11, a crankcase 19 is provided in which a crankshaft 18, which is the output shaft of the internal combustion engine 10, is housed. At the lower part of the crankcase 19, an oil pan 14 for storing lubricating oil is provided.

[0012] Upstream of the intake port 30, an intake manifold 29 equipped with a surge tank 60 is connected, and an intake pipe 20 is connected upstream of the surge tank 60. The intake pipe 20, the surge tank 60, and the intake manifold 29 constitute the intake passage of the internal combustion engine 10.

[0013] In the intake pipe 20, in order from its upstream, an air cleaner 21, a compressor wheel 24C of a supercharger 24 driven by using the exhaust discharged from the combustion chamber 17, an intercooler 27, a throttle valve 28, and a flow rate adjustment valve 40 are installed.

[0014] The throttle valve 28 is a valve for adjusting the intake air amount of the internal combustion engine 10, and the opening degree of the valve is changed by rotating a butterfly valve by an electric motor. The flow rate adjustment valve 40 is a valve for adjusting the flow rate of blow-by gas introduced from the crankcase 19 into the intake passage, and the opening degree of the valve is changed by an electric motor. The flow rate adjustment valve 40 of the present embodiment has the same valve structure as the throttle valve 28, but a different valve structure may also be used.

[0015] The air cleaner 21 filters the intake air taken into the intake pipe 20. The supercharger 24 supercharges the air in the intake pipe 20. Further, the intercooler 27 cools the air after passing through the compressor wheel 24C.

[0016] Downstream of the exhaust port 70, an exhaust passage 90 is connected. In the middle of the exhaust passage 90, a housing for housing the turbine wheel 24T of the supercharger 24 is connected. The internal combustion engine 10 is provided with a blow-by gas treatment device for treating gas, so-called blow-by gas, that leaks from the combustion chamber 17 into the crankcase 19 during the compression stroke or the combustion stroke.

[0017] The blow-by gas treatment device is provided with a fresh air introduction passage 37 for introducing fresh air into the crankcase 19 for scavenging. One end of both ends of the fresh air introduction passage 37 is connected to the intake pipe 20 between the throttle valve 28 and the flow rate adjustment valve 40. The fresh air introduction passage 37 passes through the head cover 13, through the inside of the cylinder head 12 and the cylinder block 11, and is connected to the crankcase 19. In the middle of the fresh air introduction passage 37, a separator 38 which is an oil separator installed in the head cover 13 is provided. The fresh air introduction passage 37 and the separator 38 constitute a first passage communicating the intake passage between the throttle valve 28 and the flow rate adjustment valve 40 and the crankcase 19.

[0018] The blow-by gas treatment device is provided with a suction passage 32 for guiding the blow-by gas in the crankcase 19 to a separator 31 which is an oil separator provided in the head cover 13. The end of the suction passage 32 connected to the separator 31 opens into the crankcase 19. Note that a separator 31 may be provided in the middle of the suction passage 32.

[0019] The separator 31 is connected to the surge tank 60 via a PCV (positive crankcase ventilation) valve 34 which is a differential pressure valve 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, and allows the inflow of blow-by gas from the separator 31 to the surge tank 60. These suction passage 32, separator 31, PCV valve 34, and PCV passage 35 constitute a second passage communicating the intake passage downstream of the flow rate adjustment valve 40 and the crankcase 19.

[0020] Fresh air is introduced into the crankcase 19 through the fresh air introduction passage 37. Also, when the opening degree of the flow rate adjustment valve 40 is adjusted to be reduced, the pressure on the downstream side of the flow rate adjustment valve 40 in the intake pipe 20 decreases. When the pressure on the downstream side of the flow rate adjustment valve 40 decreases, the blow-by gas in the crankcase 19 is introduced into the intake pipe 20 through the suction passage 32 together with the fresh air. The blow-by gas introduced into the intake pipe 20 is sent to the combustion chamber 17 together with the intake air and burned.

[0021] The control device 100 controls the internal combustion engine 10 and operates various operation target devices such as the throttle valve 28, the flow rate adjustment valve 40, the port injection valve 83, the in-cylinder injection valve 84, and the spark plug. 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.

[0022] The control device 100 receives detection signals from an air flow meter 22 that detects the intake air amount GA, a throttle sensor 25 that detects the throttle opening TA which is the opening degree of the throttle valve 28, and a valve opening sensor 26 that detects the valve opening BA which is the opening degree of the flow control valve 40. Further, the control device 100 receives a detection signal from a crank angle sensor 51 that detects the rotation angle (crank angle) of the crankshaft 18 in order to calculate the engine rotational speed NE. Further, the control device 100 receives a detection signal from an accelerator operation amount sensor 52 that detects the accelerator operation amount ACP which is the operation amount of the accelerator pedal. Further, the control device 100 receives detection signals from a water temperature sensor 53 that detects the cooling water temperature THW which is the temperature of the cooling water of the internal combustion engine 10, and an oil temperature sensor 54 that detects the oil temperature THO which is the temperature of the lubricating oil of the internal combustion engine 10. Note that the cooling water temperature THW is the engine water temperature. Also, the oil temperature THO is the engine oil temperature. Further, the control device 100 also receives detection signals such as a vehicle speed sensor 55 that detects the vehicle speed SP of the vehicle on which the internal combustion engine 10 is mounted. The control device 100 calculates the engine load ratio KL based on the engine rotational 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 the ratio of the intake air amount per combustion cycle of one cylinder to the reference intake air amount. The reference intake air amount is variably set according to the engine rotational speed NE.

[0023] Hydrogen gas, which is the engine fuel, has a wider range of combustible mixtures compared to gasoline and can burn even with a lean mixture. Therefore, the control device 100 performs the following output control.

[0024] That is, the control device 100 calculates a target output Pe, which is the target value of the output required for the internal combustion engine 10, based on the accelerator operation amount ACP and the vehicle speed SP. When the target output Pe is large, control is executed to make the air-fuel ratio of the air-fuel mixture smaller than when the target output Pe is small. More specifically, the control device 100 basically maintains the throttle valve 28 at an opening degree equal to or greater than a predetermined value, for example, an opening degree near full opening. Then, the required injection amount Qd is set so that the larger the target output Pe, the larger the required injection amount Qd. The required injection amount Qd is the target value of the fuel injected from the port injection valve 83 and the in-cylinder injection valve 84. Then, the control device 100 controls the port injection valve 83 and the in-cylinder injection valve 84 so as to obtain the required injection amount Qd. In this way, in the internal combustion engine 10, output adjustment is performed by changing the air-fuel ratio of the air-fuel mixture through adjustment of the fuel injection amount.

[0025] <Opening Degree Control of the Flow Rate Adjusting Valve> Since the engine fuel of the internal combustion engine 10 is hydrogen gas, which is a gaseous fuel, the proportion of hydrogen molecules in the fuel is larger than in the case of gasoline or the like, which is a liquid fuel. Therefore, the amount of moisture contained in the blow-by gas increases. Here, if the state where the internal combustion engine 10 is not warmed up continues, the temperature in the crankcase 19 does not rise, so that condensed water derived from the moisture contained in the blow-by gas is likely to be generated. When condensed water is generated in the crankcase 19, for example, the condensed water mixes into the lubricating oil stored in the oil pan 14.

[0026] Therefore, the control device 100 scavenges the blow-by gas in the crankcase 19 through the opening degree control of the flow rate adjusting valve 40. FIG. 2 shows a processing procedure for controlling the opening degree of the flow rate adjusting valve 40. The processing shown in FIG. 2 is realized by the CPU 110 repeatedly executing a program stored in the memory 120 of the control device 100 at a predetermined cycle. Hereinafter, the step numbers of each process are represented by numbers preceded by "S".

[0027] In the series of processes shown in FIG. 2, the control device 100 acquires the coolant temperature THW, the oil temperature THO, the engine rotational speed NE, and the throttle opening TA (S100). Next, the control device 100 executes a process of calculating a target opening BAt, which is the target value of the opening of the flow rate adjustment valve 40, based on the coolant temperature THW, the oil temperature THO, the engine rotational speed NE, and the throttle opening TA (S110).

[0028] When the coolant temperature THW or the oil temperature THO is low, the amount of condensed water generated in the crankcase 19 increases, so it is desirable to increase the amount of blow-by gas introduced into the intake pipe 20. Therefore, the control device 100 calculates the target opening BAt such that the value of the target opening BAt becomes smaller as the coolant temperature THW is lower. Also, the control device 100 calculates the target opening BAt such that the value of the target opening BAt becomes smaller as the oil temperature THO is lower.

[0029] Also, the engine rotational speed NE is a value related to the amount of blow-by gas in the crankcase 19. Here, since the amount of blow-by gas flowing into the crankcase 19 increases as the engine rotational speed NE is higher, it is desirable to increase the amount of blow-by gas introduced into the intake pipe 20. However, if the amount of blow-by gas is increased in this way, there is a risk that the intake air amount will be insufficient. Therefore, the control device 100 calculates the target opening BAt according to the engine rotational speed NE while considering the balance between the amount of blow-by gas introduced into the intake pipe 20 and the intake air amount.

[0030] Also, when the required intake air amount for the internal combustion engine 10 is large and the opening of the throttle valve 28 is increased, if the opening of the flow rate adjustment valve 40 is decreased, there is a risk that the intake air amount will be insufficient. Therefore, the control device 100 calculates the target opening BAt according to the throttle opening TA while considering the balance between the amount of blow-by gas introduced into the intake pipe 20 and the intake air amount.

[0031] Note that the control device 100 calculates the target opening BAt based on map data showing the relationship between the coolant water temperature THW, the oil temperature THO, the engine speed NE, and the throttle opening TA and the target opening BAt, or an arithmetic expression or the like.

[0032] Next, the control device 100 adjusts the opening of the flow control valve 40 so that the valve opening BA and the target opening BAt match (S120). Then, the control device 100 ends the execution of this process in the current execution cycle.

[0033] <Actions and Effects of the Present Embodiment> (1) The internal combustion engine 10 includes an intake passage, a throttle valve 28 provided in the intake passage, and a flow control valve 40 provided downstream of the throttle valve 28 in the intake passage. Further, the internal combustion engine 10 has a first passage that communicates the intake passage between the throttle valve 28 and the flow control valve 40 with the crankcase 19, and a second passage that communicates the intake passage downstream of the flow control valve 40 with the crankcase 19. Therefore, fresh air is introduced into the crankcase 19 through the first passage. Further, by adjusting the opening of the flow control valve 40, the blow-by gas in the crankcase 19 is introduced into the intake passage through the second passage together with the fresh air. Further, by adjusting the opening of the throttle valve 28, the intake air amount of the internal combustion engine 10 is adjusted. Therefore, it is possible to process the blow-by gas while adjusting the intake air amount of the internal combustion engine 10 with a simpler configuration compared to the case of using a variable valve mechanism.

[0034] (2) The internal combustion engine 10 includes a control device 100 that adjusts the opening of the flow control valve 40. And the control device 100 executes a process of adjusting the opening of the flow control valve 40 based on the coolant water temperature THW, the oil temperature THO, the engine speed NE, and the throttle opening TA as described above. Therefore, the opening of the flow control valve 40 can be set appropriately.

[0035] (3) As described above, when the fuel of the internal combustion engine 10 is gaseous fuel, the proportion of hydrogen molecules in the fuel is higher than that in the case of gasoline or the like which is liquid fuel. Therefore, the amount of moisture contained in the blow-by gas increases, and condensed water is likely to be generated in the crankcase 19. In this regard, in the present embodiment, it is possible to scavenge the blow-by gas in the crankcase 19 by adjusting the opening degree of the flow rate adjustment valve 40. Therefore, it is possible to suppress the generation of the condensed water in the internal combustion engine 10 using gaseous fuel in which condensed water is likely to be generated in the crankcase 19.

[0036] <Modified Example> Note that the present embodiment can be implemented with the following modifications. The present embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0037] · When the opening degree of the flow rate adjustment valve 40 is adjusted, the intake air amount of the internal combustion engine 10 changes. Therefore, the control device 100 may execute a process of correcting the opening degree of the throttle valve 28 so as to suppress the change in the intake air amount accompanying the adjustment of the opening degree of the flow rate adjustment valve 40.

[0038] FIG. 3 shows a processing procedure when controlling the opening degree of the flow rate adjustment valve 40 in this modified example. The process shown in FIG. 3 is realized by the CPU 110 repeatedly executing a program stored in the memory 120 of the control device 100 at a predetermined cycle.

[0039] In a series of processes shown in FIG. 3, the control device 100 acquires the coolant water temperature THW, the oil temperature THO, the engine rotational speed NE, the throttle opening TA, and the intake air amount GA (S200). Next, the control device 100 executes a process of calculating a target opening degree BAt which is the target value of the opening degree of the flow rate adjustment valve 40 based on the coolant water temperature THW, the oil temperature THO, the engine rotational speed NE, and the throttle opening TA (S210). The process of S210 is the same as the process of S110 described above.

[0040] Next, the control device 100 adjusts the opening degree of the flow rate adjustment valve 40 so that the valve opening degree BA matches the target opening degree BAt (S220). The process of S220 is the same as the process of S120 described above.

[0041] Next, the control device 100 executes a process of correcting the opening degree of the throttle valve 28 (S230). In the process of S230, the control device 100 executes the following processes. That is, the control device 100 acquires the intake air amount GA after adjusting the opening degree of the flow rate adjustment valve 40 in the process of S220. Then, the control device 100 corrects the opening degree of the throttle valve 28 so that the acquired intake air amount GA becomes the same as the intake air amount GA acquired in the process of S200, that is, the intake air amount GA before adjusting the opening degree of the flow rate adjustment valve 40.

[0042] Then, the control device 100 ends the execution of this process in the current execution cycle. According to this modification example, since the process of correcting the opening degree of the throttle valve 28 is executed so as to suppress the change in the intake air amount accompanying the adjustment of the opening degree of the flow rate adjustment valve 40, such a change in the intake air amount can be suppressed.

[0043] As a modification example in the process of S230, the control device 100 may execute the following process. That is, the control device 100 may correct the opening degree of the throttle valve 28 so that the intake air amount GA after adjusting the opening degree of the flow rate adjustment valve 40 becomes equal to the intake air amount required by the internal combustion engine 10.

[0044] · The control device 100 may execute a process of adjusting the opening degree of the flow rate adjustment valve 40 based on at least one of the coolant temperature THW, the oil temperature THO, the engine speed NE, and the throttle opening degree TA.

[0045] Note that, as used herein, the expression "at least one" means "one or more" of the desired options. As an example, the expression "at least one" as used herein means "only one option" or "both of the two options" if the number of options is two. As another example, the expression "at least one" as used herein means "only one option" or "any combination of two or more options" if the number of options is three or more.

[0046] · Although the suction passage 32 was connected to the surge tank 60, the connection location may be changed as appropriate as long as it is a location downstream of the flow rate adjustment valve 40 in the intake passage. · The internal combustion engine 10 may be provided with only one of the port injection valve 83 or the in-cylinder injection valve 84.

[0047] · It is not essential for the internal combustion engine 10 to be equipped with the supercharger 24. · It is not essential for the internal combustion engine 10 to be equipped with the PCV valve 34. · As the engine fuel of the internal combustion engine 10, gaseous fuels such as LPG and CNG may be used.

[0048] · As the engine fuel of the internal combustion engine 10, liquid fuels such as gasoline, light oil, or alcohol fuel may be used. Even in this case, the operations and effects described in (1) and (2) above can be obtained.

[0049] ·The control device is not limited to one that includes a CPU 110 and a memory 120 and executes software processing. For example, at least a part of what was software-processed in the above embodiment may be provided with a dedicated hardware circuit such as an ASIC that performs hardware processing. That is, the control device may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a ROM that stores the program. (b) It includes a processing device and a program storage device that execute a part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) It includes a dedicated hardware circuit that executes all of the above processing. Here, the software execution device including the processing device and the program storage device, and the dedicated hardware circuit may be one or any plurality.

Explanation of Signs

[0050] 10…Internal combustion engine 12…Cylinder head 13…Head cover 19…Crankcase 20…Intake pipe 22…Air flow meter 24…Supercharger 25…Throttle sensor 26…Valve opening sensor 28…Throttle valve 31…Separator 32…Suction passage 34…PCV valve 35…PCV passage 37…Fresh air introduction passage 38…Separator 40…Flow control valve 51…Crank angle sensor 53…Water temperature sensor 54…Oil temperature sensor 60…Surge tank 90…Exhaust passage 100…Control device 110…CPU 120…Memory

Claims

Claim 1 An internal combustion engine having an intake passage, a throttle valve provided in the intake passage, a flow rate adjustment valve provided downstream of the throttle valve in the intake passage, a first passage communicating the intake passage between the throttle valve and the flow rate adjustment valve with a crankcase, and a second passage communicating the intake passage downstream of the flow rate adjustment valve with the crankcase. Internal combustion engine. Claim 2 Comprising a control device for adjusting the opening degree of the flow rate adjustment valve, The control device executes a process of adjusting the opening degree of the flow rate adjustment valve based on at least one of the engine coolant temperature, the engine oil temperature, the engine rotational speed, and the opening degree of the throttle valve. The internal combustion engine according to claim 1. Claim 3 The control device executes a process of correcting the opening degree of the throttle valve so as to suppress a change in the intake air amount accompanying the adjustment of the opening degree of the flow rate adjustment valve. The internal combustion engine according to claim 2. Claim 4 The fuel of the internal combustion engine is gaseous fuel. The internal combustion engine according to claim 1.

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