Control device for hydrogen engine

Abstract

To inhibit oil from being ejected toward an intake passage through a blow-by gas passage.SOLUTION: A hydrogen engine includes a blow-by gas passage for recirculating blow-by gas leaked from a combustion chamber to a crankcase from the crankcase to an intake passage. A threshold temperature is preset on the basis of a temperature at which moisture included in oil stored in the crankcase starts to evaporate in the crankcase. The control device limits output of the hydrogen engine over a prescribed period from the time when an oil temperature that is a temperature of the oil exceeds the threshold temperature (S306-S310).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a control device for a hydrogen engine. [Background technology]

[0002] Patent Document 1 discloses a control device for an internal combustion engine. The internal combustion engine is equipped with a pressure sensor that detects the pressure inside the crankcase. The control device executes a restriction process to limit the output of the internal combustion engine when the pressure detected by the pressure sensor is equal to or greater than a predetermined pressure. When the pressure detected by the pressure sensor is equal to or greater than the predetermined pressure, there is a high possibility that abnormal combustion such as pre-ignition has occurred. The smaller the output of the internal combustion engine, the less likely abnormal combustion is to occur. Therefore, the control device can suppress the occurrence of abnormal combustion through the restriction process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-100730 Summary of the Invention [Problem to be solved by the invention]

[0004] During operation of a hydrogen engine, blow-by gas can leak from the combustion chamber into the crankcase. Compared to gasoline engines, blow-by gas in hydrogen engines contains a higher moisture content. Due to the long cold running time after starting a hydrogen engine, moisture from the blow-by gas can accumulate in the oil in the crankcase. As the oil temperature rises with continued engine operation, moisture accumulated in the oil due to the blow-by gas begins to evaporate. This causes a sudden increase in pressure inside the crankcase. In such a case, oil may be ejected into the intake passage along with the blow-by gas through the blow-by gas passage that returns the blow-by gas to the intake passage. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. According to one aspect of the present disclosure, there is provided a control device for a hydrogen engine equipped with a blow-by gas passage that returns blow-by gas that has leaked from the combustion chamber into the crankcase to the intake passage from the crankcase, wherein a threshold temperature is preset based on the temperature at which water contained in oil stored in the crankcase begins to evaporate in the crankcase, and the control device for a hydrogen engine limits the output of the hydrogen engine for a predetermined period of time from when the oil temperature exceeds the threshold temperature. [Effects of the Invention]

[0006] According to the above configuration, it is possible to prevent oil from being sprayed out toward the intake passage through the blow-by gas passage. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a hydrogen engine according to one embodiment. [Figure 2] FIG. 2 is a diagram showing a control device for controlling the hydrogen engine shown in FIG. [Figure 3] FIG. 3 is a flowchart showing the processing according to the first embodiment. [Figure 4] FIG. 4 is a time chart for explaining the operation according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing the processing according to the second embodiment. [Figure 6] FIG. 6 is a time chart for explaining the operation according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) The control device for a hydrogen engine according to the first embodiment will be described below with reference to the drawings.

[0009] <Configuration of the hydrogen engine 100> As shown in Figure 1, the hydrogen engine 100 has a cylinder block 16. The hydrogen engine 100 has a cylinder head 18 attached to the upper end of the cylinder block 16. The hydrogen engine 100 has a crankcase 12 attached to the lower end of the cylinder block 16. In addition, the upper part of the cylinder head 18 is covered by a ventilation case 22.

[0010] When fuel is combusted in the combustion chamber 10 of the hydrogen engine 100, blow-by gas leaks from the combustion chamber 10 of the hydrogen engine 100 into the crankcase 12. The hydrogen engine 100 is equipped with a blow-by gas reduction device for directing the blow-by gas that has leaked into the crankcase 12 into the intake system 14 of the hydrogen engine 100. Figure 1 shows an intake passage 14a, which is part of the intake system 14.

[0011] The blow-by gas reduction device has a blow-by gas passage 20 for causing the blow-by gas to flow into the intake system 14 of the hydrogen engine 100. In other words, the hydrogen engine 100 is equipped with the blow-by gas passage 20 for returning the blow-by gas that has leaked from the combustion chamber 10 to the crankcase 12 from the crankcase 12 to the intake passage 14a. The blow-by gas reduction device is equipped with a PCV (Positive Crankcase Ventilation) valve 24 for adjusting the amount of blow-by gas flowing through the blow-by gas passage 20. The PCV valve 24 is provided in the blow-by gas passage 20 and is attached to the ventilation case 22.

[0012] The blow-by gas passage 20 communicates with the crankcase 12. The blow-by gas passage 20 extends through the cylinder block 16 and the cylinder head 18. The interior of the ventilation case 22 forms part of the blow-by gas passage 20. As described above, the PCV valve 24 is attached to the ventilation case 22. The hose 21 connects the PCV valve 24 to the intake passage 14a. The interior of the hose 21 forms part of the blow-by gas passage 20. In this way, the blow-by gas passage 20 communicates with the intake passage 14a.

[0013] As described above, the ventilation case 22 is provided midway through the blow-by gas passage 20. The PCV valve 24 is provided midway through the blow-by gas passage 20. As described above, the PCV valve 24 adjusts the amount of blow-by gas flowing through the blow-by gas passage 20. This changes the flow rate of blow-by gas flowing from the crankcase 12 to the intake passage 14a. The PCV valve 24 is a one-way valve that allows gas to flow from the crankcase 12 side to the intake passage 14a side and blocks gas from the intake passage 14a side to the crankcase 12 side. The PCV valve 24 opens when the difference between the pressure in the crankcase 12 upstream of the PCV valve 24 and the pressure in the intake passage 14a downstream of the PCV valve 24 reaches or exceeds a predetermined value.

[0014] <Control device 50> 2, the control device 50 of the hydrogen engine 100 acquires various signals from the hydrogen engine 100. For example, the control device 50 acquires a signal from an oil temperature sensor 30 that detects the oil temperature, which is the temperature of the oil stored in the crankcase 12. The control device 50 acquires a signal from a pressure sensor 32 that detects the crankcase pressure, which is the pressure in the crankcase 12. The control device 50 acquires a signal from a water temperature sensor 34 that detects the temperature of the cooling water that cools the hydrogen engine 100.

[0015] The control device 50 controls the fuel injection valve 40, ignition device 42, throttle valve 44, etc. provided in the hydrogen engine 100 based on various signals acquired from the hydrogen engine 100. In this way, the control device 50 controls the output of the hydrogen engine 100.

[0016] <Processing Executed by the Control Device 50> The process executed by the control device 50 will be described with reference to Figure 3. The control device 50 starts the flow shown in Figure 3 when the hydrogen engine 100 is started. After completing the process shown in Figure 3 once, the control device 50 does not execute the flow shown in Figure 3 until the hydrogen engine 100 is started again. For this reason, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time when a logical product condition, which will be described later, is met for the first time within one trip (S306 to S310). Here, the logical product condition consists of a condition that the oil temperature exceeds a threshold temperature and a condition that the crankcase pressure detected by the pressure sensor 32 exceeds a threshold pressure. One trip is the period from when the hydrogen engine 100 is started to when it is stopped.

[0017] In step S300, the control device 50 determines whether the oil temperature acquired from the oil temperature sensor 30 is above a threshold temperature. Here, the threshold temperature is set in advance based on the temperature at which moisture contained in the oil stored in the crankcase 12 starts to evaporate in the crankcase 12. The threshold temperature may be the temperature at which moisture contained in the oil starts to evaporate, or it may be a temperature slightly higher or slightly lower than the temperature at which evaporation starts. If the control device 50 makes a negative determination in step S300 (S300: NO), it repeats step S300. If the control device 50 makes a positive determination in step S300 (S300: YES), it proceeds to step S302.

[0018] In step S302, the control device 50 determines whether the crankcase pressure detected by the pressure sensor 32 exceeds a threshold pressure. The threshold pressure is set to a value lower than the pressure at which oil is sprayed from the blow-by gas passage 20 toward the intake passage 14a. If the control device 50 makes a negative determination in step S302 (S302: NO), the control device 50 returns to step S300. If the control device 50 makes a positive determination in step S302 (S302: YES), the control device 50 proceeds to step S304.

[0019] In step S304, the control device 50 determines whether the crankcase pressure has exceeded the threshold pressure within a certain period of time after the oil temperature exceeded the threshold temperature. The certain period of time is set in advance as appropriate, such as several tens of seconds. If the control device 50 determines negative in step S304 (S304: NO), it ends the flow of FIG. 3. If the control device 50 determines positive in step S304 (S304: YES), it proceeds to step S306.

[0020] In step S306, the control device 50 begins limiting the output of the hydrogen engine 100. In the first embodiment, the control device 50 reduces the output of the hydrogen engine 100 by a predetermined amount. After reducing the output of the hydrogen engine 100 by the predetermined amount, the control device 50 does not increase the output of the hydrogen engine 100. The control device 50 then proceeds to step S308.

[0021] In step S308, the control device 50 determines whether a predetermined period has elapsed since the oil temperature exceeded the threshold temperature. If the determination in step S308 is negative (S308: NO), the control device 50 repeats step S308. If the determination in step S308 is positive (S308: YES), the control device 50 proceeds to step S310.

[0022] In step S310, the control device 50 ends the limitation on the output of the hydrogen engine 100. After completing step S310, the control device 50 ends the flow of FIG. <Operation of the First Embodiment> The operation of the first embodiment will be described with reference to Figure 4. In Figure 4, the solid line shows an example in which the output of the hydrogen engine 100 according to the first embodiment is limited. In Figure 4, the dashed line shows a comparative example in which the output of the hydrogen engine 100 is not limited.

[0023] At time T11, the hydrogen engine 100 starts. The control device 50 starts the flow shown in Figure 3 when the hydrogen engine 100 starts. The hydrogen engine 100 is in cold operation from time T11 to time T12. During cold operation, moisture derived from blow-by gas accumulates in the oil.

[0024] In the example shown in Figure 4, the output of the hydrogen engine 100 increases after time T12. As the output of the hydrogen engine 100 increases, the crankcase pressure and oil temperature rise. At time T13, the oil temperature exceeds the threshold temperature (S300: YES). In the example shown in Figure 4, the oil temperature exceeds the threshold temperature after time T13. Then, at time T14, the crankcase pressure exceeds the threshold pressure (S302: YES).

[0025] In the first embodiment, the output of the hydrogen engine 100 is limited from time T14 to time T15 (S306, S308: NO). In contrast, in the comparative example, the output of the hydrogen engine 100 is not limited. In particular, in the comparative example, the output of the hydrogen engine 100 increases after time T14, as shown by the dashed line.

[0026] In the first embodiment, the output of the hydrogen engine 100 is limited from time T14 to time T15, so the increase in oil temperature is suppressed compared to the comparative example. The suppression of the increase in oil temperature reduces the peak value of the crankcase pressure.

[0027] At time T15, the predetermined period has elapsed, and therefore the control device 50 ends the limitation on the output of the hydrogen engine 100 at time T15 (S308: YES, S310). <Effects of the first embodiment> (1-1) The hydrogen engine 100 is equipped with a blow-by gas passage 20 that returns blow-by gas that has leaked from the combustion chamber 10 into the crankcase 12 to the intake passage 14a from the crankcase 12. A threshold temperature is set in advance based on the temperature at which moisture contained in the oil stored in the crankcase 12 begins to evaporate in the crankcase 12. The control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time from when the oil temperature exceeds the threshold temperature (S300, S306 to S310).

[0028] When the oil temperature exceeds a certain level, the moisture accumulated in the oil begins to evaporate all at once. The greater the output of the hydrogen engine 100, the greater the amount of blow-by gas leaking into the crankcase 12. Therefore, if high output is generated when the moisture in the oil begins to evaporate, the pressure increase due to the moisture evaporation and the inflow of a large amount of blow-by gas may combine to cause a sudden increase in pressure inside the crankcase 12. If the pressure in the crankcase 12 suddenly increases, oil may be ejected along with the blow-by gas through the blow-by gas passage 20 toward the intake passage 14a. With the above configuration, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period when the oil temperature exceeds the threshold temperature. This suppresses the increase in pressure in the crankcase 12 after the oil temperature exceeds the threshold temperature. In other words, it is possible to reduce the peak value of pressure in the crankcase 12. This suppresses the ejection of oil through the blow-by gas passage 20 toward the intake passage 14a.

[0029] (1-2) The hydrogen engine 100 is equipped with a pressure sensor 32 that detects the crankcase pressure, which is the pressure in the crankcase 12. When a logical AND condition is met, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time. Here, the logical AND condition consists of a condition that the oil temperature exceeds a threshold temperature and a condition that the crankcase pressure detected by the pressure sensor 32 exceeds a threshold pressure. The threshold pressure is set to a value lower than the pressure at which oil is sprayed from the blow-by gas passage 20 toward the intake passage 14a.

[0030] If the crankcase pressure is sufficiently low, there is little chance that oil will spray toward the intake passage 14a through the blow-by gas passage 20. If the oil temperature exceeds the threshold temperature and the crankcase pressure exceeds the threshold pressure, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time. This makes it possible to avoid limiting the output of the hydrogen engine 100 even when the crankcase pressure is sufficiently low.

[0031] (1-3) The hydrogen engine 100 is equipped with a pressure sensor 32 that detects the crankcase pressure, which is the pressure in the crankcase 12. If the crankcase pressure exceeds a threshold pressure within a certain period of time after the oil temperature exceeds a threshold temperature, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time (S304: YES, S306 to S310). The threshold pressure is set to a value lower than the pressure at which oil is sprayed from the blow-by gas passage 20 toward the intake passage 14a.

[0032] If the crankcase pressure exceeds the threshold pressure after a certain period of time has elapsed since the oil temperature exceeded the threshold temperature, the output of the hydrogen engine 100 will not be limited. Therefore, once a sufficient amount of time has passed since the oil temperature exceeded the threshold, and the moisture has been sufficiently removed from the oil, the output of the hydrogen engine 100 will not be limited. This makes it easier to avoid limiting the output of the hydrogen engine 100 even when there is little possibility of oil spraying toward the intake passage 14a.

[0033] (1-4) The hydrogen engine 100 is equipped with a pressure sensor 32 that detects the crankcase pressure, which is the pressure in the crankcase 12. The control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time when a logical product condition is met for the first time during one trip. Here, the logical product condition consists of a condition that the oil temperature exceeds a threshold temperature and a condition that the crankcase pressure detected by the pressure sensor 32 exceeds a threshold pressure. One trip is the period from when the hydrogen engine 100 starts to when it stops. The threshold pressure is set to a value lower than the pressure at which oil is sprayed from the blow-by gas passage 20 toward the intake passage 14a.

[0034] With the above configuration, the control device 50 limits the output of the hydrogen engine 100 for a predetermined period of time when the logical AND condition is met for the first time during one trip. Therefore, once the oil temperature reaches or exceeds the threshold and the water has sufficiently evaporated from the oil, the output of the hydrogen engine 100 will not be limited even if the crankcase pressure exceeds the threshold pressure. This makes it easier to avoid limiting the output of the hydrogen engine 100 even when there is little possibility of oil spraying toward the intake passage 14a.

[0035] (Second embodiment) A control device for a hydrogen engine according to the second embodiment will be described below with reference to the drawings. Descriptions of components common to the first and second embodiments will be omitted. In the second embodiment, the hydrogen engine 100 executes the flow shown in Figure 5 instead of the flow shown in Figure 3.

[0036] The processing executed by the control device 50 will be described with reference to Fig. 5. The control device 50 starts the flow of Fig. 5 when the hydrogen engine 100 is started. Once the processing shown in Fig. 5 is completed, the control device 50 will not execute the flow shown in Fig. 5 until the hydrogen engine 100 is started again.

[0037] In step S300, the control device 50 determines whether the oil temperature is above the threshold temperature. If the determination in step S300 is negative (S300: NO), the control device 50 repeats step S300. If the determination in step S300 is positive (S300: YES), the control device 50 proceeds to step S302. Steps S300 and S302 in the flow of FIG. 5 are the same processes as steps S300 and S302 in the flow of FIG. 3.

[0038] In step S302, the control device 50 determines whether the crankcase pressure exceeds the threshold pressure. If the determination in step S302 is negative (S302: NO), the control device 50 returns to step S300. If the determination in step S302 is positive (S302: YES), the control device 50 proceeds to step S500.

[0039] In step S500, the control device 50 sets an upper limit value used to limit the output of the hydrogen engine 100. As a result, the control device 50 sets an upper limit value for the output of the hydrogen engine 100 and limits the output of the hydrogen engine 100 to less than or equal to the upper limit value. Next, the control device 50 proceeds to step S502. In step S502, the control device 50 determines whether a predetermined period has elapsed since the oil temperature exceeded the threshold temperature. If the control device 50 makes a negative determination in step S502 (S502: NO), it repeats step S502. If the control device 50 makes a positive determination in step S502 (S502: YES), it proceeds to step S504.

[0040] In step S504, the control device 50 cancels the upper limit value used to limit the output of the hydrogen engine 100. After completing step S504, the control device 50 ends the flow of FIG.

[0041] <Operation of the Second Embodiment> The operation of the second embodiment will be described with reference to Figure 6. In Figure 6, the solid line shows an example in which the output of the hydrogen engine 100 according to the second embodiment is limited. In Figure 6, the dashed line shows a comparative example in which the output of the hydrogen engine 100 is not limited.

[0042] At time T21, the hydrogen engine 100 starts. The control device 50 starts the flow shown in Figure 5 when the hydrogen engine 100 starts. The hydrogen engine 100 is in cold operation from time T21 to time T22. During cold operation, moisture derived from blow-by gas accumulates in the oil.

[0043] In the example shown in FIG. 6, the output of the hydrogen engine 100 increases after time T22. As the output of the hydrogen engine 100 increases, the crankcase pressure and oil temperature rise. At time T23, the oil temperature exceeds the threshold temperature (S300: YES). In the example shown in FIG. 6, the oil temperature exceeds the threshold temperature after time T23. Next, at time T24, the crankcase pressure exceeds the threshold pressure (S302: YES). Therefore, in the second embodiment, at time T24, the control device 50 sets an upper limit for limiting the output of the hydrogen engine 100 (S500). At time T25, the output of the hydrogen engine 100 reaches the upper limit. In the second embodiment, the output of the hydrogen engine 100 is limited to or below the upper limit from time T25 to time T26. In contrast, in the comparative example, the output of the hydrogen engine 100 is not limited from time T25 to time T26.

[0044] In the second embodiment, the output of the hydrogen engine 100 is limited from time T25 to time T26, so the increase in oil temperature is suppressed compared to the comparative example. The suppression of the increase in oil temperature reduces the peak value of the crankcase pressure.

[0045] At time T26, the predetermined period has elapsed, and therefore the control device 50 ends the limitation on the output of the hydrogen engine 100 at time T26 (S502: YES, S504). <Effects of the second embodiment> (2-1) The control device 50 sets an upper limit value for the output of the hydrogen engine 100 and limits the output of the hydrogen engine 100 to below the upper limit value for a predetermined period of time from when the oil temperature exceeds the threshold temperature (S500 to S504).

[0046] According to the above configuration, the control device 50 limits the output of the hydrogen engine 100 to an upper limit or lower for a predetermined period of time from when the oil temperature exceeds the threshold temperature. This prevents the output of the hydrogen engine 100 from becoming excessively large during the predetermined period of time.

[0047] (Example of change) Possible modifications to the first and second embodiments are as follows: The following modifications can be implemented in combination with each other within the scope of technical compatibility.

[0048] In the first embodiment, at least one of step S302 and step S304 may be omitted. In the second embodiment, step S302 may be omitted.

[0049] The first and second embodiments may be combined as long as no technical contradiction exists. For example, the output limitation of the hydrogen engine 100 in the first embodiment may be changed to the output limitation of the hydrogen engine 100 in the second embodiment.

[0050] In the first and second embodiments, once a flow is completed during one trip, the output of the hydrogen engine 100 is not limited for the duration of that trip. However, for example, if the crankcase pressure is greater than the threshold pressure immediately after limiting the output of the hydrogen engine 100 is completed, limiting the output of the hydrogen engine 100 may be resumed. [Explanation of symbols]

[0051] 10... combustion chamber, 12... crankcase, 14a... intake passage, 20... blow-by gas passage, 32... pressure sensor, 50... control device, 100... hydrogen engine

Claims

1. A control device for a hydrogen engine equipped with a blow-by gas passage that returns blow-by gas leaking from a combustion chamber to a crankcase from the crankcase to an intake passage, a threshold temperature is preset based on a temperature at which moisture contained in oil stored in the crankcase starts to evaporate in the crankcase, limiting the output of the hydrogen engine for a predetermined period of time from when the oil temperature exceeds the threshold temperature; Hydrogen engine control device.

2. The hydrogen engine further includes a pressure sensor that detects crankcase pressure, which is the pressure in the crankcase. the control device limits the output of the hydrogen engine for the predetermined period when a logical AND condition consisting of a condition that the oil temperature is higher than the threshold temperature and a condition that the crankcase pressure detected by the pressure sensor is higher than a threshold pressure is satisfied; The threshold pressure is set to a value lower than the pressure at which the oil is sprayed from the blow-by gas passage toward the intake passage. The control device for a hydrogen engine according to claim 1.

3. The hydrogen engine further includes a pressure sensor that detects crankcase pressure, which is the pressure in the crankcase. the control device limits the output of the hydrogen engine for the predetermined period if the crankcase pressure exceeds a threshold pressure within a certain period after the oil temperature exceeds the threshold temperature; The threshold pressure is set to a value lower than the pressure at which the oil is sprayed from the blow-by gas passage toward the intake passage. The control device for a hydrogen engine according to claim 1.

4. The hydrogen engine further includes a pressure sensor that detects crankcase pressure, which is the pressure in the crankcase. the control device limits the output of the hydrogen engine for the predetermined period on the condition that a logical AND condition consisting of a condition that the oil temperature is above the threshold temperature and a condition that the crankcase pressure detected by the pressure sensor is above a threshold pressure is met for the first time within one trip, which is the period from when the hydrogen engine is started to when it is stopped; The threshold pressure is set to a value lower than the pressure at which the oil is sprayed from the blow-by gas passage toward the intake passage. The control device for a hydrogen engine according to claim 1.

5. the control device sets an upper limit value for the output of the hydrogen engine and limits the output of the hydrogen engine to be equal to or lower than the upper limit value for the predetermined period from when the oil temperature exceeds the threshold temperature; The control device for a hydrogen engine according to claim 1.

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