Internal combustion engine control device

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 the fuel injection amount of the internal combustion engine based on the air-fuel ratio detected by an air-fuel ratio sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the amount of fuel in the blow-by gas increases, the air-fuel ratio becomes rich and the torque increases. However, in an internal combustion engine that uses hydrogen as fuel, since there is no air-fuel ratio sensor, it is impossible to correct the fuel injection amount based on the air-fuel ratio. Therefore, there is a concern 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 Problems

[0005] Hereinafter, means for solving the above problems and their operational effects will be described. According to one aspect of the present disclosure, there is provided a control device for an internal combustion engine that is applied to a vehicle equipped with a hydrogen engine and controls the hydrogen engine. The control device acquires the rotational speed, the load factor, and the current torque from sensors mounted on the vehicle, calculates a predicted torque and a predicted blow-by gas amount based on the rotational speed and the load factor, calculates an estimated rich ratio indicating the ratio at which the air-fuel mixture in the combustion chamber is enriched by the blow-by gas based on the difference between the current torque and the predicted torque and the predicted blow-by gas amount, and corrects the fuel injection amount injected from the fuel injection valve based on the estimated rich ratio.

Advantages of the Invention

[0006] The control device for the internal combustion engine can correct the fuel injection amount without using an air-fuel ratio sensor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0008] Hereinafter, with reference to FIG. 1, an embodiment of the control device for an internal combustion engine will be described. <Configuration of the Internal Combustion Engine 10> FIG. 1 schematically shows an internal combustion engine 10 mounted on a vehicle. The internal combustion engine 10 shown in FIG. 1 is a hydrogen engine that uses hydrogen as fuel.

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

[0010] The internal combustion engine 10 includes an intake passage 21 that is an intake introduction passage to the combustion chamber 15 and an exhaust passage 22 that is an exhaust discharge passage from the combustion chamber 15. Further, the internal combustion engine 10 includes a fuel injection valve 23 that injects hydrogen as fuel into the intake air to form an air-fuel mixture, and a spark plug 24 that ignites the air-fuel mixture in the combustion chamber 15 by spark discharge. An air cleaner 25 that filters dust and the like in the air is provided in the intake passage 21. Also, an air flow meter 26 and a throttle valve 27 are provided in the intake passage 21. The throttle valve 27 adjusts the amount of intake air introduced into the combustion chamber 15 according to the opening degree. The exhaust generated by the combustion of the air-fuel mixture in the combustion chamber 15 is discharged into the exhaust passage 22.

[0011] <Configuration of the control device 30> Detection signals of various sensors for detecting the state of the internal combustion engine 10 are input to the control device 30. The various sensors include a crank angle sensor 18, a torque detection device 19, an air flow 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 the torque detection device 19 is a motor generator in a hybrid vehicle. The air flow meter 26 is a sensor that detects the intake air flow rate. The vehicle speed sensor 31 is a sensor that detects the vehicle speed.

[0012] <Blow-by gas circulation> Next, the blow-by gas circulation will be described. Not all the fuel in the combustion chamber 15 is burned, and some fuel leaks from between the cylinder 14 and the piston 13 into the crankcase 16. In order to reuse the unburned fuel that has leaked 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 gives an instruction to the PCV valve 41 to control the amount of blow-by gas to be circulated.

[0013] <Control of fuel injection amount by the control device 30> Next, the control of the fuel injection amount executed 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 is defined as the "number of revolutions". The ratio of the current intake air flow rate to the intake air flow rate when the internal combustion engine 10 is in a steady operation at full load is defined as the "load factor". When controlling the fuel injection amount, the control device 30 determines the target torque based on the number of revolutions, the load factor, etc.

[0014] Subsequently, the control device 30 determines the air excess ratio λ for realizing the target torque based on the target torque and the number of revolutions. The air excess ratio λ is determined within a certain range using an arithmetic map with the target torque and the number of revolutions as input variables. For example, the air excess ratio λ determined using the arithmetic map is a value in the range between 3.0 and 1.5. The air excess ratio λ is determined to be a smaller value as the target torque is larger.

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

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

[0018] In the process of step S30, 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 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 greater 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 immediately terminates this series of processes.

[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 Figure 3. The estimated rich ratio is an index indicating how much 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 and the predicted blow-by gas amount shown in Figure 3 and the estimated rich ratio can be specified based on, for example, the results of experiments.

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

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

[0022] In the process of step S80, the control device 30 corrects the fuel injection amount based on the estimated rich ratio calculated in step S50. At this time, the amount of fuel contained in the air-fuel mixture in the combustion chamber 15 is more than the amount of fuel injected from the fuel injection valve 23 due to the influence of blow-by gas, and the air-fuel mixture is rich. Therefore, the control device 30 reduces the fuel injection amount by correction. The control device 30 determines the amount of correction to further reduce the fuel injection amount as the estimated rich ratio is higher. By this process, the series of processes by the control device 30 is completed.

[0023] <Actions 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 rich 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 rich ratio (step S80).

[0024] <Effects of the present embodiment> (1) By correcting the fuel injection amount based on the estimated rich ratio, the control device 30 can correct the fuel injection amount without using an air-fuel ratio sensor in the internal combustion engine 10 which is a hydrogen engine.

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

[0026] (3) The current torque becomes larger than the predicted torque due to the influence of blow-by gas. When trying to always eliminate the difference between the predicted torque and the current torque, it is necessary to continuously calculate the estimated rich ratio and continuously correct the fuel injection amount.

[0027] The control device 30 calculates the estimated rich ratio on the condition that the difference between the current torque and the predicted torque is larger than a predetermined value. According to the above embodiment, when the difference between the current torque and the predicted torque is equal to or less than the set predetermined value, the difference is allowed. The control device 30 does not calculate the estimated rich ratio when the difference is small enough to be acceptable. Thereby, it is possible to suppress the frequency of calculation of the estimated rich ratio by the control device 30 from becoming excessive.

[0028] (4) The control device 30 corrects the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value. When the difference is small enough to be acceptable, the control device 30 does not correct the fuel injection amount. Thereby, it is possible to suppress excessive correction of the fuel injection amount by the control device 30.

[0029] (5) When the driving state fluctuates during the running of the vehicle, a temporary difference may occur between the current torque and the predicted torque due to the fluctuation of the driving state. The difference may be eliminated without correcting the fuel injection amount. Therefore, the control device 30 corrects the fuel injection amount on the condition that the time during which the state of difference between the current torque and the predicted torque continues is longer than a predetermined period.

[0030] According to the above embodiment, when the continuous time is less than the set predetermined period, the control device 30 allows a state of difference between the current torque and the predicted torque. When a state of temporary difference occurs, the control device 30 does not correct the fuel injection amount. Therefore, it is possible to suppress an excessive number of correction controls of the fuel injection amount by the control device 30.

[0031] (6) The control device 30 corrects the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio on the condition that the difference between the estimated rich ratio calculated through the process of step S50 and the estimated rich ratio calculated in a different driving state is equal to or less than a predetermined value.

[0032] The ratio of the amount of fuel in the blow-by gas does not fluctuate significantly in a short time. Therefore, when enrichment occurs due to the fuel derived from the blow-by gas, the estimated rich ratio calculated by the control device 30 does not fluctuate significantly even if the driving state changes.

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

[0034] <Modified Example> In addition, the following are elements that can be modified in common to each of the above embodiments. The following modified examples can be implemented in combination with each other as long as there is no technical contradiction.

[0035] · The control device 30 corrects the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio on the condition that the duration is longer than a predetermined period (step S60) and the difference between the estimated rich ratio and the estimated rich ratio calculated in a different operating state is equal to or less than a predetermined value (step S70). On the other hand, the control device 30 may correct the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio regardless of whether the duration is longer than a predetermined period and regardless of whether the difference between the estimated rich ratio and the estimated rich ratio calculated in a different operating state is equal to or less than a predetermined value. A series of processes executed by the control device 30 will be described with reference to FIG. 4.

[0036] FIG. 4 shows the flow of a series of processes executed by the control device 30 in correcting the fuel injection amount. This series of processes is repeatedly executed by the control device 30 during the operation of the internal combustion engine 10. 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 the process of step S120, 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 this embodiment, the predicted torque and the target torque have the same value.

[0038] In the process of 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 the process of step S140, 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 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 immediately terminates this series of processes.

[0039] In the process of step S150, 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 fuel exists in the combustion chamber 15 with respect to the injection amount injected from the fuel injection valve 23. The relationship between the torque difference and the predicted blow-by gas amount shown in FIG. 3 and the estimated rich ratio can be specified based on, for example, the results of experiments.

[0040] In the process of step S160, the control device 30 corrects the fuel injection amount based on the estimated rich ratio calculated in step S150. At this time, the amount of fuel contained in the air-fuel mixture in the combustion chamber 15 is larger than the amount of fuel injected from the fuel injection valve 23 due to the influence of blow-by gas, and the air-fuel mixture is enriched. Therefore, the control device 30 reduces the fuel injection amount by correction. The control device 30 determines the amount of correction to further reduce the fuel injection amount as the estimated rich ratio is higher. By this process, the series of processes by the control device 30 is terminated.

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

[0042] ·The above control device 30 corrects the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value (step S140). In contrast, the control device 30 may correct the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich 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 the effects (1) and (2) described in the effects of the above embodiment.

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

[0044] ·The above control device 30 corrects the fuel injection amount injected from the fuel injection valve 23 based on the estimated rich ratio on the condition that the difference between the estimated rich ratio and the estimated rich ratio calculated in a different operating state is equal to or less than a predetermined value (step S70). In contrast, the control device 30 may correct the fuel injection amount based on the estimated rich ratio regardless of whether the difference between the estimated rich ratio and the estimated rich ratio calculated in a different operating state is equal to or less than a predetermined value. Such a control device 30 can achieve the same effects as the 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 injection valve, 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 that is applied to a vehicle equipped with a hydrogen engine and controls the hydrogen engine, obtains the rotational speed, the load factor, and the current torque from sensors mounted on the vehicle, calculates a predicted torque and a predicted blow-by gas amount based on the rotational speed and the load factor, calculates an estimated rich ratio indicating the ratio at which the air-fuel mixture in the combustion chamber is enriched by the blow-by gas based on the difference between the current torque and the predicted torque and the predicted blow-by gas amount, corrects the fuel injection amount injected from the fuel injection valve based on the estimated rich ratio, A control device for an internal combustion engine.

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

3. corrects the fuel injection amount injected from the fuel injection valve based on the estimated rich ratio on the condition that the difference between the current torque and the predicted torque is greater than a predetermined value, The control device for an internal combustion engine according to claim 1.

4. corrects the fuel injection amount injected from the fuel injection valve based on the estimated rich ratio on the condition that the time during which the state of difference between the current torque and the predicted torque continues is longer than a predetermined period, The control device for an internal combustion engine according to claim 1.

5. performs correction of the fuel injection amount injected from the fuel injection valve based on the estimated rich ratio on the condition that the difference between the estimated rich ratio and the estimated rich ratio calculated in a different operating state is equal to or less than a predetermined value, The control device for an internal combustion engine according to claim 1.

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