Control device for internal combustion engines

Abstract

To enable a fuel injection amount to be corrected without using an air-fuel ratio sensor.SOLUTION: A control device of an internal combustion engine executes the steps of: acquiring a rotation speed, a load rate and current torque from a sensor mounted on a vehicle (step S10); calculating predicted torque and a predicted blow-by gas amount based on the rotation speed and the load rate (step S20); calculating an estimated rich ratio, which indicates the degree to which an air-fuel mixture in the combustion chamber is enriched by the blow-by gas, based on a difference between the current torque and the predicted torque, and the predicted blow-by gas amount (step S50); and correcting a fuel injection amount from a fuel injection valve based on the estimated rich ratio (step S80).SELECTED DRAWING: Figure 2

Description

[[Technical Field]]

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

[0002] Patent Document 1 discloses a control device for an internal combustion engine that corrects a fuel injection amount of the internal combustion engine based on an air-fuel ratio detected by an air-fuel ratio sensor. [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Patent Laid-Open No. 2015-137547 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] When the amount of fuel in blow-by gas increases, the air-fuel ratio becomes rich and torque increases. However, an internal combustion engine using hydrogen as fuel does not include an air-fuel ratio sensor, so correction of the fuel injection amount based on the air-fuel ratio cannot be performed. Therefore, there are concerns about deterioration of drivability, noise, and vibration, occurrence of pre-ignition, and deterioration of emissions due to excessive fuel supply caused by addition of fuel derived from blow-by gas. [[Means for Solving the Problem]]

[0005] Means for solving the above problem and the operational effects thereof will be described below. According to one aspect of the present disclosure, there is provided a control device for an internal combustion engine which is applied to a vehicle equipped with a hydrogen engine and controls the hydrogen engine, the control device acquiring the number of revolutions, a load factor, and a current torque from a sensor mounted on the vehicle, calculating a predicted torque and a predicted blow-by gas amount based on the number of revolutions and the load factor, and calculating a difference between the current torque and the predicted torque The larger the size, the larger it becomes, and the predicted blow-by gas amount The larger it gets, the smaller it becomes.The estimated richness ratio, which indicates the proportion of the mixture in the combustion chamber that is enriched by blow-by gas, is calculated, and the estimated richness ratio The higher the Amount of fuel injected from the fuel injector In order to reduce the The present invention provides a control device for an internal combustion engine that corrects the amount of fuel injected. [Effects of the Invention]

[0006] The control system for an internal combustion engine can correct the fuel injection amount without using an air-fuel ratio sensor. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of a control device for an internal combustion engine in one embodiment. [Figure 2] This is a flowchart for how a control device corrects the fuel injection amount in one embodiment. [Figure 3] This graph shows the relationship between the torque difference, the predicted blow-by gas volume, and the estimated richness ratio. [Figure 4] This is a flowchart for how the control device corrects the fuel injection amount in another embodiment. [Modes for carrying out the invention]

[0008] An embodiment of a control device for an internal combustion engine will be described below with reference to Figure 1. <Configuration of internal combustion engine 10> Figure 1 schematically shows an internal combustion engine 10 mounted on a vehicle. The internal combustion engine 10 shown in Figure 1 is a hydrogen engine that uses hydrogen as fuel.

[0009] As shown in Figure 1, the internal combustion engine 10 comprises a cylinder head 11, a cylinder block 12, and a piston 13. The cylinder block 12 includes a cylinder 14. A combustion chamber 15 for burning hydrogen is formed in the portion of the cylinder 14 above the piston 13. A crankcase 16 is formed in the lower portion of the cylinder block 12. The crankcase 16 is equipped with a crankshaft 17, a crank angle sensor 18, and a torque detection device 19. A connecting rod 20 is connected to link the piston 13 and the crankshaft 17. The connecting rod 20 transmits the motion of the piston 13 to the crankshaft 17.

[0010] The internal combustion engine 10 includes an intake passage 21, which is the passage for introducing intake air into the combustion chamber 15, and an exhaust passage 22, which is the passage for discharging exhaust gas from the combustion chamber 15. Furthermore, the internal combustion engine 10 includes a fuel injection valve 23 that injects hydrogen fuel into the intake air to form a fuel-air mixture, and a spark plug 24 that ignites the fuel-air mixture in the combustion chamber 15 by spark discharge. The intake passage 21 is provided with an air cleaner 25 that filters out dust and other particles from the air. The intake passage 21 is also provided with an airflow meter 26 and a throttle valve 27. The throttle valve 27 adjusts the amount of intake air introduced into the combustion chamber 15 according to its opening. The exhaust gas generated by the combustion of the fuel-air mixture in the combustion chamber 15 is discharged into the exhaust passage 22.

[0011] <Configuration of the control device 30> The control device 30 receives detection signals from various sensors for detecting the state of the internal combustion engine 10. These sensors include a crank angle sensor 18, a torque detection device 19, an airflow meter 26, and a vehicle speed sensor 31. The crank angle sensor 18 is a sensor that detects the crank angle of the internal combustion engine 10. The torque detection device 19 is a device that detects the magnitude of the torque generated by the internal combustion engine 10. An example of a torque detection device 19 is a motor generator in a hybrid vehicle. The airflow meter 26 is a sensor that detects the intake airflow rate. The vehicle speed sensor 31 is a sensor that detects the vehicle speed.

[0012] <Blow-by gas circulation> Next, the circulation of blow-by gas will be explained. Not all of the fuel in the combustion chamber 15 is burned; some of the fuel leaks out between the cylinder 14 and the piston 13 into the crankcase 16. To reuse the unburned fuel that leaks into the crankcase 16 as fuel, the crankcase 16 and the intake passage 21 are connected by a PCV passage 40. A PCV valve 41 is provided in the PCV passage 40. The control device 30 issues instructions to the PCV valve 41 to control the amount of circulating blow-by gas.

[0013] <Control of fuel injection amount by control device 30> Next, the control of the fuel injection amount performed by the control device 30 will be described. The rotational speed of the crankshaft 17 based on the detection signal of the crank angle sensor 18 will be defined as the "number of rotations". The ratio of the current intake airflow rate to the intake airflow rate when the internal combustion engine 10 is operating steadily under full load will be defined as the "load ratio". When controlling the fuel injection amount, the control device 30 determines the target torque based on the number of rotations, the load ratio, etc.

[0014] Next, the control device 30 determines the excess air ratio λ to achieve the target torque based on the target torque and rotational speed. The excess air ratio λ is determined within a certain range using a calculation map with the target torque and rotational speed as input variables. For example, the excess air ratio λ determined using the calculation map is a value in the range of 3.0 to 1.5. The larger the target torque, the smaller the value of the excess air ratio λ is determined to be.

[0015] Next, the control device 30 determines the fuel injection amount according to the intake air flow rate so that the excess air ratio λ determined in this way is achieved. Then, the control device 30 controls the fuel injector 23 based on the determined fuel injection amount. In this way, the control device 30 injects hydrogen into the fuel injector 23.

[0016] <Processing performed by the control device 30 of the internal combustion engine 10 in one embodiment> FIG. 2 shows a flow of a series of processes executed by the control device 30 in correcting a fuel injection amount. This series of processes is repeatedly executed by the control device 30 during operation of the internal combustion engine 10. First, in the process of step S10, the control device 30 acquires information of the rotational speed, the load factor, and the current torque.

[0017] Next, in the process of step S20, the control device 30 calculates a predicted torque and a predicted blow-by gas amount based on the acquired rotational speed and load factor. In the present embodiment, the predicted torque and the target torque are the same value.

[0018] In the process of step S30, the control device 30 calculates a difference between the current torque and the predicted torque. The difference calculated herein is the difference obtained by subtracting the predicted torque from the current torque. In the process of step S40, the control device 30 compares the magnitude of the calculated torque difference with a preset predetermined value. As a result of the comparison, if the torque difference is larger than the predetermined value (step S40: YES), the process proceeds to step S50. If the torque difference is equal to or less than the predetermined value (step S40: NO), the control device 30 temporarily terminates this series of processes as it is.

[0019] In the process of step S50, the control device 30 calculates an estimated rich ratio from the torque difference and the predicted blow-by gas amount as shown in FIG. 3. The estimated rich ratio is an index indicating how much excess fuel exists in the combustion chamber 15 relative to the injection amount injected from the fuel injection valve 23. The relationship between the torque difference, the predicted blow-by gas amount and the estimated rich ratio shown in FIG. 3 can be specified, for example, based on experimental results.

[0020] In step S60, the control device 30 compares the duration of the period during which there is a difference between the current torque and the predicted torque with a predetermined period. If the duration is longer than the predetermined period (step S60: YES), the process proceeds to step S70. If the duration is less than or equal to the predetermined period (step S60: NO), the control device 30 terminates this series of processes.

[0021] In step S70, the control device 30 compares the estimated richness ratio calculated in step S50 with the estimated richness ratio calculated under different operating conditions. Different operating conditions refer to conditions where the rotational speed and load ratio are different from those obtained in step S10. If the difference between the two estimated richness ratios is less than or equal to a predetermined value (step S70: YES), the process proceeds to step S80. If the difference between the two estimated richness ratios exceeds a predetermined value (step S70: NO), the control device 30 terminates this series of processes.

[0022] In step S80, the control device 30 corrects the fuel injection amount based on the estimated richness ratio calculated in step S50. At this time, the amount of fuel contained in the air-fuel mixture in the combustion chamber 15 is greater than the amount of fuel injected from the fuel injector 23 due to the effect of blow-by gas, and the air-fuel mixture is rich. Therefore, the control device 30 reduces the fuel injection amount through correction. The control device 30 determines the amount of correction to reduce the fuel injection amount so that the higher the estimated richness ratio, the greater the reduction in the fuel injection amount. With this process, the series of processes by the control device 30 is completed.

[0023] <Operation of this embodiment> The control device 30 of the internal combustion engine 10 controls the fuel injection amount as part of the control of the internal combustion engine 10, which is a hydrogen engine. The control device 30 acquires data from sensors mounted on the vehicle (step S10). The control device 30 calculates an estimated richness ratio based on the acquired data and data calculated based on the acquired data (step S50). The control device 30 corrects the fuel injection amount based on the calculated estimated richness ratio (step S80).

[0024] <Effects of this embodiment> (1) The control device 30 corrects the fuel injection amount based on the estimated richness ratio, thereby enabling the internal combustion engine 10, which is a hydrogen engine, to correct the fuel injection amount without using an air-fuel ratio sensor.

[0025] (2) The control device 30 can correct the fuel injection amount to suppress deterioration of drivability, noise, and vibration, occurrence of pre-ignition, and deterioration of emissions caused by excessive fuel supply due to the addition of fuel originating from blow-by gas.

[0026] (3) Current torque is greater than predicted torque due to the effect of blow-by gas. If you want to constantly eliminate the difference between predicted torque and current torque, you need to constantly calculate the estimated richness ratio and constantly correct the fuel injection amount.

[0027] The control device 30 calculates the estimated richness ratio on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value. According to the above embodiment, if the difference between the current torque and the predicted torque is less than or equal to a set predetermined value, the difference is tolerated. The control device 30 does not calculate the estimated richness ratio if the difference is small enough to be tolerated. This prevents the control device 30 from calculating the estimated richness ratio excessively.

[0028] (4) The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the difference between the current torque and the predicted torque is greater than a predetermined value. The control device 30 does not correct the amount of fuel injected if the difference is small enough to be acceptable. This prevents the control device 30 from correcting the amount of fuel injected excessively.

[0029] (5) When the driving conditions change while the vehicle is in motion, a temporary difference may occur between the current torque and the predicted torque due to the change in driving conditions. This difference may be resolved without correction of the fuel injection amount. Therefore, the control device 30 corrects the fuel injection amount on the condition that the time during which there is a difference between the current torque and the predicted torque is longer than a predetermined period.

[0030] According to the above embodiment, the control device 30 allows a state in which there is a difference between the current torque and the predicted torque when the duration is less than a set predetermined period. The control device 30 does not correct the fuel injection amount when a temporary difference occurs. Therefore, it is possible to suppress the number of times the control device 30 corrects the fuel injection amount.

[0031] (6) The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the difference between the estimated richness ratio calculated through the process in step S50 and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value.

[0032] The proportion of fuel in the blow-by gas does not fluctuate significantly in a short period of time. Therefore, if enrichment occurs due to fuel originating from the blow-by gas, the estimated richness ratio calculated by the control device 30 does not fluctuate significantly even if the operating conditions change.

[0033] According to the above embodiment, the correction of the fuel injection amount based on the estimated richness ratio is performed based on the small difference between two estimated richness ratios calculated under different operating conditions. Therefore, when enrichment occurs due to fuel originating from blow-by gas, the fuel injection amount can be appropriately controlled by performing a correction based on the estimated richness ratio.

[0034] <Example of changes> Other elements that can be modified in common with each of the above embodiments are as follows. The following examples of modifications can be combined with each other to the extent that they do not contradict each other technically.

[0035] The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the duration is longer than a predetermined period (step S60) and the difference between the estimated richness ratio and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value (step S70). Alternatively, the control device 30 may correct the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, regardless of whether the duration is longer than a predetermined period and whether the difference between the estimated richness ratio and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value. A series of processes performed by the control device 30 will be explained with reference to Figure 4.

[0036] Figure 4 shows the flow of a series of processes performed by the control device 30 in correcting the fuel injection amount. This series of processes is repeatedly performed by the control device 30 while the internal combustion engine 10 is running. First, in the process of step S110, the control device 30 acquires information on the rotational speed, load factor, and current torque.

[0037] Next, in step S120, the control device 30 calculates the predicted torque and the predicted blow-by gas amount based on the acquired rotational speed and load factor. In this embodiment, the predicted torque and the target torque are the same value.

[0038] In step S130, the control device 30 calculates the difference between the current torque and the predicted torque. The difference calculated here is the difference obtained by subtracting the predicted torque from the current torque. In step S140, the control device 30 compares the magnitude of the calculated torque difference with a predetermined value. If the torque difference is greater than the predetermined value (step S140: YES), the process proceeds to step S150. If the torque difference is less than or equal to the predetermined value (step S140: NO), the control device 30 terminates this series of processes.

[0039] In step S150, the control device 30 calculates the estimated richness ratio from the torque difference and the predicted blow-by gas amount, as shown in Figure 3. The estimated richness ratio is an indicator of how much more fuel is present in the combustion chamber 15 relative to the amount injected from the fuel injector 23. The relationship between the torque difference and the predicted blow-by gas amount shown in Figure 3 and the estimated richness ratio can be determined, for example, based on experimental results.

[0040] In step S160, the control device 30 corrects the fuel injection amount based on the estimated richness ratio calculated in step S150. At this time, the amount of fuel contained in the air-fuel mixture in the combustion chamber 15 is greater than the amount of fuel injected from the fuel injector 23 due to the effect of blow-by gas, and the air-fuel mixture is rich. Therefore, the control device 30 reduces the fuel injection amount through correction. The control device 30 determines the amount of correction to reduce the fuel injection amount so that the higher the estimated richness ratio, the greater the reduction in the fuel injection amount. With this process, the series of processes by the control device 30 is completed.

[0041] Such a control device 30 can achieve the same effects as effects (1), (2), and (4) described in the effects of the above embodiment. The control device 30 calculates the estimated richness ratio on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value (step S40). Alternatively, the control device 30 may calculate the estimated richness ratio regardless of whether the difference between the current torque and the predicted torque is greater than a predetermined value. Such a control device 30 can achieve the same effects as effects (1), (2), (5), and (6) described in the effects of the above embodiment.

[0042] The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the difference between the current torque and the predicted torque is greater than a predetermined value (step S140). Alternatively, the control device 30 may correct the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, regardless of whether the difference between the current torque and the predicted torque is greater than a predetermined value. Such a control device 30 can achieve the same effects as effects (1) and (2) described in the effects of the above embodiment.

[0043] The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the duration is longer than a predetermined period (step S60). Alternatively, the control device 30 may correct the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, regardless of whether the duration is longer than a predetermined period. Such a control device 30 can achieve the same effects as effects (1), (2), (3) and (6) described in the effects of the above embodiment.

[0044] The control device 30 corrects the amount of fuel injected from the fuel injector 23 based on the estimated richness ratio, provided that the difference between the estimated richness ratio and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value (step S70). Alternatively, the control device 30 may correct the amount of fuel injected based on the estimated richness ratio regardless of whether the difference between the estimated richness ratio and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value. Such a control device 30 can achieve the same effects as effects (1), (2), (3) and (5) described in the effects of the above embodiment. [Explanation of Symbols]

[0045] 10...Internal combustion engine, 11...Cylinder head, 12...Cylinder block, 13...Piston, 14...Cylinder, 15...Combustion chamber, 16...Crankcase, 17...Crankshaft, 18...Crank angle sensor, 19...Torque detection device, 20...Connecting rod, 21...Intake passage, 22...Exhaust passage, 23...Fuel injector, 24...Spark plug, 25...Air cleaner, 26...Airflow meter, 27...Throttle valve, 30...Control device, 31...Vehicle speed sensor, 40...PCV passage, 41...PCV valve

Claims

1. A control device for an internal combustion engine, applied to a vehicle equipped with a hydrogen engine and used to control the hydrogen engine, From the sensors mounted on the aforementioned vehicle, the rotational speed, load factor, and current torque are obtained. Based on the rotational speed and load factor, the predicted torque and predicted blow-by gas volume are calculated. The estimated richness ratio, which indicates the proportion to which the mixture in the combustion chamber is enriched by blow-by gas, is calculated such that it increases as the difference between the current torque and the predicted torque increases, and decreases as the predicted amount of blow-by gas increases. The amount of fuel injected from the fuel injector is corrected so that the higher the estimated richness ratio, the lower the amount of fuel injected from the fuel injector. Control device for internal combustion engines.

2. The estimated richness ratio is calculated on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value. A control device for an internal combustion engine according to claim 1.

3. If the difference between the current torque and the predicted torque is greater than a predetermined value, the amount of fuel injected from the fuel injector is corrected based on the estimated richness ratio. A control device for an internal combustion engine according to claim 1.

4. If the period during which there is a difference between the current torque and the predicted torque is longer than a predetermined period, the amount of fuel injected from the fuel injector is corrected based on the estimated richness ratio. A control device for an internal combustion engine according to claim 1.

5. Provided that the difference between the estimated richness ratio and the estimated richness ratio calculated under different operating conditions is less than or equal to a predetermined value, the amount of fuel injected from the fuel injector is corrected based on the estimated richness ratio. A control device for an internal combustion engine according to claim 1.

Images