Ventilation system

Abstract

This reduces the possibility that crankcase ventilation may be hindered due to the pressure downstream of the compressor being close to atmospheric pressure. [Solution] The first PCV valve 68 opens when the pressure in the part downstream of the compressor 60a reaches a first predetermined pressure or higher, which is higher than atmospheric pressure. The vehicle control device performs ventilation based on the fact that a logical AND condition consisting of the condition that battery charging is permitted and the condition that the pressure in the part downstream of the compressor 60a is above a first threshold and below a second threshold is satisfied for a predetermined period of time. The ventilation process is a process of supercharging the hydrogen engine 10 so that the pressure in the part downstream of the compressor 60a reaches a first predetermined pressure or higher, and also performing regenerative charging.

Description

Technical Field

[0001] The present disclosure relates to a ventilation system.

Background Art

[0002] Patent Document 1 discloses a vehicle equipped with an internal combustion engine. The internal combustion engine includes a PCV (Positive Crankcase Ventilation) valve. The PCV valve is provided in the middle of the blow-by gas passage. The blow-by gas passage is a passage extending from the crankcase to the surge tank. The PCV valve adjusts the amount of blow-by gas flowing through the blow-by gas passage. The blow-by gas passage is a passage for flowing the blow-by gas leaked from the combustion chamber of the internal combustion engine to the crankcase into the intake system of the internal combustion engine.

[0003] In the idling state of the internal combustion engine, as the piston descends, the surge tank located downstream of the throttle valve is in a negative pressure state. Since the surge tank is in a negative pressure state, the PCV valve is open, and blow-by gas flows from the crankcase into the intake system. In this way, ventilation of the crankcase through the PCV valve is performed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the idling state, as described above, the crankcase is ventilated via the PCV valve. When the driver of the vehicle presses the accelerator pedal, the throttle valve opens wider. Consequently, the amount of air flowing into the surge tank increases, causing the pressure in the surge tank to move from negative pressure to atmospheric pressure. When the pressure in the surge tank is close to atmospheric pressure, the crankcase ventilation via the PCV valve described above is less effective.

[0006] When the above-mentioned internal combustion engine is a hydrogen engine, the need for crankcase ventilation is greater compared to when it is a gasoline engine. The reason for this is explained below. The molecules that make up the fuel used in a hydrogen engine are smaller than the molecules that make up the fuel used in a gasoline engine. Therefore, the molecules that make up the fuel used in a hydrogen engine can easily slip through the gap between the piston and the cylinder from the combustion chamber to the crankcase. Consequently, in a hydrogen engine, unburned fuel tends to accumulate in the crankcase more easily than in a gasoline engine. [Means for solving the problem]

[0007] According to one aspect of the present disclosure, a ventilation system comprising a hydrogen engine and a vehicle control device, wherein the hydrogen engine includes an intake passage, a compressor of a supercharger installed in the intake passage, an air intake passage extending from the intake passage to the crankcase, and a first PCV (Positive Crankcase Valve) provided in the middle of the air intake passage and configured to open when the portion of the intake passage downstream of the compressor becomes above a first predetermined pressure, which is higher than atmospheric pressure. A ventilation system is provided, comprising a Ventilation valve and a return passage extending from the portion of the intake passage upstream of the compressor to the crankcase, wherein the vehicle control device includes a processing circuit, the processing circuit configured to perform a threshold determination process to determine whether the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to a first threshold lower than atmospheric pressure, and a ventilation process to supercharge the hydrogen engine so that the portion of the intake passage downstream of the compressor is greater than or equal to a first predetermined pressure, based on the condition that the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to the first threshold. [Effects of the Invention]

[0008] With the above configuration, it is easier to avoid situations where the crankcase is poorly ventilated due to the pressure downstream of the compressor being close to atmospheric pressure rather than negative pressure. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows a vehicle equipped with a ventilation system according to the first embodiment. [Figure 2] Figure 2 shows the hydrogen engine included in the ventilation system according to the first embodiment. [Figure 3] Figure 3 shows the supercharging state of the hydrogen engine provided by the ventilation system according to the first embodiment. [Figure 4]Figure 4 shows the process performed by the vehicle control device included in the ventilation system according to the first embodiment. [Figure 5] Figure 5 is a diagram illustrating the ventilation process shown in Figure 4. [Figure 6] Figure 6 is a diagram illustrating the operation of the ventilation system according to the first embodiment, where (a) is the accelerator request, (b) is the ventilation flag, (c) is the intake manifold pressure, (d) is the shaft torque, (e) is the regenerative torque, and (f) is the State of Operation (SOC). [Figure 7] Figure 7 shows the process performed by the vehicle control device included in the ventilation system according to the second embodiment. [Figure 8] Figure 8 shows the process performed by the vehicle control device included in the ventilation system according to the second embodiment. [Figure 9] Figure 9 is a diagram illustrating the second ventilation process shown in Figure 8. [Modes for carrying out the invention]

[0010] (First Embodiment) The ventilation system according to the first embodiment will be described below with reference to the drawings. <Vehicle 100 composition> The configuration of vehicle 100 will be described with reference to Figure 1. Vehicle 100 is equipped with a hydrogen engine 10. The hydrogen engine 10 is an internal combustion engine that uses hydrogen as fuel. Vehicle 100 is equipped with a first motor generator 16 and a second motor generator 18. Each of the first motor generator 16 and the second motor generator 18 can operate as a power source for vehicle 100. Furthermore, each of the first motor generator 16 and the second motor generator 18 can operate as a generator that generates electricity by receiving power from the hydrogen engine 10. The hydrogen engine 10, the first motor generator 16, the second motor generator 18, and the vehicle control device 30 described later constitute the ventilation system 90.

[0011] The vehicle 100 is also equipped with a power split mechanism 14, which is a planetary gear mechanism having three rotating elements: a sun gear, a planetary carrier, and a ring gear. The power split mechanism 14 is connected to a hydrogen engine 10 and a first motor generator 16. The power split mechanism 14 is connected to a second motor generator 18 via a reduction gear 22. The reduction gear 22 is connected to the drive wheels via a differential mechanism. The power split mechanism 14, the first motor generator 16, the second motor generator 18, and the reduction gear 22 constitute a transmission.

[0012] The first motor generator 16 and the second motor generator 18 are electrically connected to the battery 20 via a power control unit 34 (hereinafter referred to as PCU34). The PCU34 adjusts the amount of power supplied from the battery 20 to the first motor generator 16 and the second motor generator 18, and the amount of charge supplied from the first motor generator 16 and the second motor generator 18 to the battery 20.

[0013] Vehicle 100 is equipped with an engine control unit 32, which is an electronic control unit that controls the hydrogen engine 10. Vehicle 100 is also equipped with a vehicle control unit 30 that comprehensively controls the engine control unit 32 and the PCU 34. Both the vehicle control unit 30 and the engine control unit 32 are computer units comprising a memory device that stores control programs and data, a CPU (Central Processing Unit) that executes the programs stored in the memory device, and RAM (Random Access Memory) which serves as a workspace for the CPU when executing programs. The memory device is, for example, ROM (Read Only Memory).

[0014] The engine control device 32 receives detection signals such as the depression amount of the driver's accelerator pedal and the speed of the vehicle 100. Then, the vehicle control device 30 calculates the vehicle required power, which is the required value of the driving force of the vehicle 100, based on the accelerator depression amount and the vehicle speed. Further, the vehicle control device 30 calculates the required engine output, the MG1 required torque, and the MG2 required torque respectively based on the vehicle required power and the power storage amount of the battery 20. The required engine output is the required value of the engine output. The MG1 required torque is the required value of the power running / regeneration torque of the first motor generator 16. The MG2 required torque is the required value of the power running / regeneration torque of the second motor generator 18. Then, the engine control device 32 performs output control of the hydrogen engine 10 according to the required engine output, and the PCU 34 performs torque control of the first motor generator 16 and the second motor generator 18 according to the MG1 required torque and the MG2 required torque. Thereby, the running control of the vehicle 100 is performed.

[0015] <Configuration of the hydrogen engine 10> Referring to FIG. 2, the configuration of the hydrogen engine 10 will be described. The hydrogen engine 10 includes a cylinder block 40, a crankcase 42 connected to the lower part of the cylinder block 40, and a cylinder head 44 connected to the upper part of the cylinder block 40. A ventilation case 46 is provided for the cylinder head 44.

[0016] The cylinder block 40 has cylinders 54. A piston 56 reciprocates inside the cylinders 54. An intake passage 50 and an exhaust passage 52 are connected to the cylinders 54. The intake passage 50 includes, in this order from upstream, an air cleaner 58, a compressor 60a of a supercharger 60, an intercooler 62, a throttle valve 64, and an intake manifold 66. The throttle valve 64 is installed in a portion of the intake passage 50 downstream of the compressor 60a. The turbine wheel 60b of the supercharger 60 is provided in the exhaust passage 52.

[0017] The hydrogen engine 10 further includes an air introduction passage 76 that extends from a portion downstream of the throttle valve 64 in the intake passage 50 to the crankcase 42. The hydrogen engine 10 further includes a first PCV (Positive Crankcase Ventilation) valve 68 provided in the middle of the air introduction passage 76. The first PCV opens in response to the portion downstream of the compressor 60a in the intake passage 50, specifically the portion downstream of the throttle valve 64, reaching a first predetermined pressure or higher that is higher than atmospheric pressure.

[0018] The blow-by gas passage 70 extends from the crankcase 42 to the intake manifold 66. That is, the blow-by gas passage 70 extends from the crankcase 42 to a portion downstream of the throttle valve 64 in the intake passage 50. The blow-by gas passage 70 extends inside the cylinder block 40, inside the cylinder head 44, and inside the ventilation case 46. A second PCV valve 74 is provided in the blow-by gas passage 70 between the intake manifold 66 and the ventilation case 46. The second PCV valve 74 adjusts the amount of blow-by gas flowing through the blow-by gas passage 70. The second PCV valve 74 opens in response to the portion downstream of the compressor 60a in the intake passage 50, specifically the portion downstream of the throttle valve 64, reaching a second predetermined pressure or lower that is lower than atmospheric pressure. As will be described later, this allows the blow-by gas stored in the crankcase 42 to flow into the intake passage 50.

[0019] The recirculation passage 72 extends from a portion upstream of the compressor 60a in the intake passage 50 to the crankcase 42. The recirculation passage 72 extends from a location between the air cleaner 58 and the compressor 60a in the intake passage 50 to the ventilation case 46. Further, the recirculation passage 72 extends inside the ventilation case 46, inside the cylinder head 44, inside the cylinder block 40, and opens into the crankcase 42.

[0020] In the intake passage 50, a compressor inlet sensor 80 is provided between the air cleaner 58 and the compressor 60a. The compressor inlet sensor 80 detects the pressure at the location between the air cleaner 58 and the compressor 60a. The pressure detected by the compressor inlet sensor 80 is input to the vehicle control device 30.

[0021] In the intake passage 50, a boost pressure sensor 82 is provided between the compressor 60a and the intercooler 62. The boost pressure sensor 82 detects the pressure at the location between the compressor 60a and the intercooler 62. The pressure detected by the boost pressure sensor 82 is input to the vehicle control device 30.

[0022] In the intake passage 50, an intake manifold pressure sensor 84 is provided on the intake manifold 66. The intake manifold pressure sensor 84 detects the pressure in the intake manifold 66. The pressure detected by the intake manifold pressure sensor 84 is input to the vehicle control device 30.

[0023] <Airflow> Figure 2 shows the state where the pressure downstream of the throttle valve 64 is below the second predetermined pressure, which is lower than atmospheric pressure. The second PCV valve 74 is open. The first PCV valve 68 is closed. The arrows in Figure 2 indicate the airflow.

[0024] When the second PCV valve 74 is open, blow-by gas leaking from the combustion chamber into the crankcase 42 flows from the crankcase 42 to the intake passage 50 through the blow-by gas passage 70, and fresh air flows into the crankcase 42 through the recirculation passage 72. This allows blow-by gas stored in the crankcase 42 to flow into the intake passage 50.

[0025] Figure 3 shows the state where the pressure downstream of the throttle valve 64 is above the first predetermined pressure, which is higher than atmospheric pressure. The first PCV valve 68 is open. The second PCV valve 74 is closed. The arrows in Figure 3 indicate the airflow.

[0026] When the first PCV valve 68 is open, blow-by gas flows from the crankcase 42 to the intake passage 50 through the return passage 72, and fresh air flows into the crankcase 42 through the atmospheric intake passage 76.

[0027] <Processing performed by the vehicle control device 30> Referring to Figures 4 and 5, the processes executed by the vehicle control device 30 will be explained. The vehicle control device 30 starts the process shown in Figure 4 when the vehicle 100 is started. Note that the ventilation flag, which will be described later, is Off when the vehicle 100 is started.

[0028] In step S400, the vehicle control device 30 performs a charge determination process to determine whether or not charging of the battery 20 connected to the first motor generator 16 and the second motor generator 18 is permitted. Specifically, the vehicle control device 30 determines whether or not the State of Charge (SOC) of the battery 20 is below the charge threshold. If the SOC is below the charge threshold, the vehicle control device 30 determines that charging of the battery 20 is permitted. If the vehicle control device 30 makes an affirmative determination in step S400 (S400: YES), it proceeds to step S402. If the vehicle control device 30 makes a negative determination in step S400 (S400: NO), it proceeds to step S408. In step S408, the vehicle control device 30 clears the time counter, which will be described later, to 0.

[0029] In step S402, the vehicle control device 30 performs a threshold determination process to determine whether the pressure downstream of the throttle valve 64 is above a first threshold, which is lower than atmospheric pressure. The first threshold is below a second predetermined pressure. If the vehicle control device 30 determines that the pressure in step S402 is positive (S402: YES), it proceeds to step S404. If the vehicle control device 30 determines that the pressure in step S402 is negative (S402: NO), it proceeds to step S408.

[0030] In step S404, the vehicle control device 30 performs a threshold determination process to determine whether the pressure in the part downstream of the throttle valve 64 is below a second threshold that is higher than atmospheric pressure. The second threshold is greater than or equal to the first default pressure. The second threshold is greater than the first threshold. If the vehicle control device 30 makes an affirmative determination in step S404 (S404: YES), it proceeds to step S406. If the vehicle control device 30 makes a negative determination in step S404 (S404: NO), it proceeds to step S408. Thus, the second threshold ≥ first default pressure > atmospheric pressure > second default pressure ≥ first threshold. According to steps S402 and S404, the vehicle control device 30 determines whether the pressure in the part downstream of the throttle valve 64 is near atmospheric pressure. If the pressure in the part downstream of the throttle valve 64 is near atmospheric pressure, both the first PCV valve 68 and the second PCV valve 74 are closed. This means that the crankcase 42 is not being ventilated.

[0031] In step S406, the vehicle control device 30 increments the time counter. The time counter is 0 at the start of the process in Figure 4. The time counter is cleared to 0 at the end of the process in Figure 4. The time counter continuously measures the time for which a positive determination is made in all of steps S400, S402, and S404.

[0032] The vehicle control device 30 proceeds to step S410 after step S406 or step S408. In step S410, the vehicle control device 30 determines whether the time counter is above a predetermined period. The predetermined period is determined in advance, taking into account the time it takes for a certain amount of blow-by gas to accumulate in the crankcase 42. The predetermined period is, for example, 10 seconds. If the vehicle control device 30 determines that the time counter is above a predetermined period (S410: YES) in step S410, it proceeds to step S412. If the vehicle control device 30 determines that the time counter is above a predetermined period (S410: NO) in step S410, it returns to step S400.

[0033] In step S412, the vehicle control device 30 turns on the ventilation flag. When the ventilation flag is turned on, it means that the vehicle control device 30 is in a state where it should perform the ventilation process described later. In step S412, the vehicle control device 30 starts the ventilation process. According to steps S400 to S412, the vehicle control device 30 performs the ventilation process based on the fact that the logical AND condition is satisfied for a predetermined period of time. Here, the logical AND condition consists of a condition that charging of the battery 20 is permitted and a condition that the pressure in the part downstream of the throttle valve 64 is greater than or equal to a first threshold and less than or equal to a second threshold. The second threshold is greater than atmospheric pressure and greater than the first threshold.

[0034] The ventilation process will be explained with reference to Figure 5. The ventilation process is a process that supercharges the hydrogen engine 10 so that the portion downstream of the throttle valve 64 is equal to or greater than the first predetermined pressure, and regenerates the battery 20. Regenerative charging is performed by the first motor generator 16 or the second motor generator 18. In step S500, the vehicle control device 30 increases the lower limit of the shaft torque output from the hydrogen engine 10. According to step S500, the vehicle control device 30 supercharges the hydrogen engine 10 by increasing the lower limit of the shaft torque output from the hydrogen engine 10. Next, in step S502, the vehicle control device 30 requests the first motor generator 16 or the second motor generator 18 to perform regenerative charging. Then, the vehicle control device 30 completes the flow shown in Figure 5.

[0035] As shown in Figure 4, following step S412, the vehicle control device 30 proceeds to step S414. In step S414, the vehicle control device 30 determines whether the conditions for terminating the ventilation process have been met. The conditions for terminating the ventilation process include the fact that charging of the battery 20 is no longer permitted. That is, the fact that charging of the battery 20 is no longer permitted means that the SOC has become greater than the charging threshold described above. If the vehicle control device 30 determines in step S414 that the conditions have been met (S414: NO), it repeats step S414. If the vehicle control device 30 determines in step S414 that the conditions have been met (S414: YES), it proceeds to step S416.

[0036] In step S416, the vehicle control device 30 turns off the ventilation flag. In step S416, the vehicle control device 30 terminates the ventilation process. Specifically, the vehicle control device 30 releases the setting of the lower limit of the shaft torque. The vehicle control device 30 releases the regenerative charging request mentioned above.

[0037] According to steps S414 and S416, the vehicle control device 30 is configured to terminate the ventilation process when the conditions for terminating the ventilation process are met, and the conditions for terminating the ventilation process include the fact that charging of the battery 20 is no longer permitted.

[0038] After step S416, the vehicle control device 30 completes the flow shown in Figure 4. <Operation of the First Embodiment> The operation of the first embodiment will be explained with reference to Figure 6. The solid lines in Figure 6 illustrate the operation of this embodiment. In contrast, the dashed lines in Figure 6 show a comparative example in which the processing of this embodiment is not performed. In the example shown in Figure 6, the SOC is below the charge threshold from time T0 to time T4. Therefore, when the vehicle control device 30 performs step S400 in Figure 4 from time T0 to time T4, the vehicle control device 30 makes an affirmative judgment in step S400 (S400: YES).

[0039] At time T0, the hydrogen engine 10 is idling. That is, the magnitude of the accelerator request is 0. Since the hydrogen engine 10 is idling, as the piston 56 descends, the pressure downstream of the throttle valve 64 becomes a negative pressure of about 60 kPa.

[0040] The accelerator request increases from time T0 onward. This means that as the accelerator request increases, the opening of the throttle valve 64 increases, and therefore the pressure in the part downstream of the throttle valve 64 increases.

[0041] At time T1, the intake manifold pressure, which is the pressure downstream of the throttle valve 64, exceeds the first threshold. As shown in Figure 6(c), from time T1 to time T2, the intake manifold pressure is between the first threshold and the second threshold. Therefore, the vehicle control device 30 makes a positive determination in steps S402 and S404 from time T1 to time T2 (S402: YES, S404: YES).

[0042] At time T2, the time counter reaches a predetermined period (S410: YES). Therefore, as shown in Figure 6(b), the vehicle control device 30 changes the ventilation flag from Off to On at time T2. The vehicle control device 30 starts the ventilation process from time T2. As shown in Figures 6(d) and (e), the shaft torque and regenerative torque increase at time T2.

[0043] At time T3, as shown in Figure 6(c), the intake manifold pressure has reached a value greater than the second threshold. As shown in Figure 6(a), the accelerator request increases from time T2 to time T4. As shown in Figure 6(d), the shaft torque remains constant from time T2 to time T4. Therefore, as shown in Figure 6(e), the regenerative torque, which represents charging the battery 20, decreases as the accelerator request increases.

[0044] At time T4, the State of Charge (SOC) has reached the charge threshold. Therefore, the condition for terminating the ventilation process is met (S414: YES). For this reason, the ventilation flag is turned OFF at time T4 (S416). In other words, the vehicle control device 30 terminates the ventilation process at time T4.

[0045] Comparing this embodiment with the comparative example, in the comparative example, the period during which the intake manifold pressure is within the range from the first threshold to the second threshold is longer. In contrast, in this embodiment, the period during which the intake manifold pressure is within the range from the first threshold to the second threshold is shorter. The first PCV valve 68 opens when the pressure exceeds or exceeds the first predetermined pressure. Here, the second threshold is equal to or greater than the first predetermined pressure. Therefore, in this embodiment, it is possible to effectively ventilate the crankcase 42 through the first PCV valve 68.

[0046] <Effects of the First Embodiment> (1) The ventilation system 90 comprises a hydrogen engine 10, a first motor generator 16 and a second motor generator 18 capable of operating as generators that receive power from the hydrogen engine 10 to generate electricity, and a vehicle control device 30. The hydrogen engine 10 comprises an intake passage 50, a compressor 60a of a supercharger 60 installed in the intake passage 50, and a throttle valve 64 installed in the intake passage 50 downstream of the compressor 60a. The hydrogen engine 10 further comprises a blow-by gas passage 70 extending from the crankcase 42 to the intake passage 50 downstream of the throttle valve 64. The hydrogen engine 10 further comprises an atmospheric intake passage 76 extending from the intake passage 50 downstream of the throttle valve 64 to the crankcase 42. The hydrogen engine 10 further includes a first PCV (Positive Crankcase Ventilation) valve 68 located in the middle of the atmospheric intake passage 76 and configured to open when the pressure in the portion downstream of the throttle valve 64 is above a first predetermined pressure, which is higher than atmospheric pressure. The hydrogen engine 10 further includes a second PCV valve 74 located in the middle of the blow-by gas passage 70 and configured to open when the pressure in the portion downstream of the throttle valve 64 is below a second predetermined pressure, which is lower than atmospheric pressure. The hydrogen engine 10 further includes a recirculation passage 72 extending from the portion upstream of the compressor 60a in the intake passage 50 to the crankcase 42. The vehicle control device 30 performs a charge determination process to determine whether charging of the battery 20 connected to the first motor generator 16 and the second motor generator 18 is permitted. The vehicle control device 30 performs a threshold determination process to determine whether the pressure in the portion downstream of the throttle valve 64 is above a first threshold and below a second threshold, which is lower than atmospheric pressure. The vehicle control device 30 performs ventilation based on the fact that a logical AND condition consisting of the condition that charging of the battery 20 is permitted and the condition that the pressure in the part downstream of the throttle valve 64 is above a first threshold and below a second threshold is satisfied for a predetermined period of time.The ventilation process involves supercharging the hydrogen engine 10 so that the portion downstream of the throttle valve 64 is at or above a first predetermined pressure, and regenerating the battery 20 using the first motor generator 16 or the second motor generator 18.

[0047] If the pressure downstream of the throttle valve 64 approaches atmospheric pressure from negative pressure, ventilation of the crankcase 42 via the second PCV valve 74 becomes difficult. In such cases, if charging of the battery 20 is permitted, the vehicle control device 30 supercharges the hydrogen engine 10 so that ventilation of the crankcase 42 via the first PCV valve 68 occurs. This makes it easier to avoid a situation where ventilation of the crankcase 42 is difficult due to the pressure downstream of the throttle valve 64 approaching atmospheric pressure from negative pressure. Furthermore, the increase in shaft torque generated by supercharging the hydrogen engine 10 is used to charge the battery 20. This prevents the driver from feeling any discomfort due to the increase in shaft torque.

[0048] (2) The logical AND condition consists of a condition that charging of the battery 20 is permitted and a condition that the pressure in the part downstream of the throttle valve 64 is greater than or equal to a first threshold and less than or equal to a second threshold, wherein the second threshold is greater than atmospheric pressure and greater than the first threshold.

[0049] If the pressure downstream of the throttle valve 64 is very high, ventilation is not performed. If the pressure downstream of the throttle valve 64 is very high, it is highly likely that ventilation of the crankcase 42 is being performed via the first PCV valve 68. Therefore, with the above configuration, unnecessary ventilation can be avoided.

[0050] (3) The vehicle control device 30 puts the hydrogen engine 10 into a supercharged state by increasing the lower limit of the shaft torque output from the hydrogen engine 10. According to the above configuration, the hydrogen engine 10 can be supercharged by increasing the lower limit of the shaft torque.

[0051] (4) The vehicle control device 30 is configured to terminate the ventilation process when the conditions for terminating the ventilation process are met, and the conditions for terminating the ventilation process include the fact that charging of the battery 20 is no longer permitted.

[0052] The above configuration makes it easier to avoid situations where charging of battery 20 occurs even though charging is not permitted. (Second Embodiment) The ventilation system according to the second embodiment will be described with reference to Figures 7 to 9. In the following, explanations of components common to the ventilation system according to the second embodiment and the ventilation system according to the first embodiment will be omitted as appropriate.

[0053] In the second embodiment, the vehicle control device 30 executes steps S400 to S416 in the same manner as in the first embodiment. Here, the threshold determination process in the first embodiment corresponds to the first threshold determination process in the second embodiment. The time counter in the first embodiment corresponds to the first time counter in the second embodiment. The ventilation process in the first embodiment corresponds to the first ventilation process in the second embodiment. The ventilation flag in the first embodiment corresponds to the first ventilation flag in the second embodiment. In the first embodiment, the vehicle control device 30 proceeds to step S410 after executing step S408. In contrast, in the second embodiment, the vehicle control device 30 proceeds to step S800 after executing step S408.

[0054] As shown in Figure 8, in step S800, the vehicle control device 30 performs a discharge determination process to determine whether or not discharge of the battery 20 connected to the first motor generator 16 and the second motor generator 18 is permitted. Specifically, the vehicle control device 30 determines whether or not the State of Charge (SOC) of the battery 20 is equal to or greater than the discharge threshold. The discharge threshold is smaller than the charge threshold described above. If the SOC is equal to or greater than the discharge threshold, the vehicle control device 30 determines that discharge of the battery 20 is permitted. If the vehicle control device 30 makes an affirmative determination in step S800 (S800: YES), it proceeds to step S802. If the vehicle control device 30 makes a negative determination in step S800 (S800: NO), it proceeds to step S808. In step S808, the vehicle control device 30 clears the second time counter, described later, to 0. After executing step S808, the vehicle control device 30 returns to step S400 in Figure 7.

[0055] In step S802, the vehicle control device 30 performs a second threshold determination process to determine whether the pressure downstream of the throttle valve 64 is above a first threshold, which is lower than atmospheric pressure. The first threshold is below a second predetermined pressure. If the vehicle control device 30 makes an affirmative determination in step S802 (S802: YES), it proceeds to step S804. If the vehicle control device 30 makes a negative determination in step S802 (S802: NO), it proceeds to step S808.

[0056] In step S804, the vehicle control device 30 performs a second threshold determination process to determine whether the pressure downstream of the throttle valve 64 is below a second threshold that is higher than atmospheric pressure. The second threshold is greater than or equal to the first predetermined pressure. The second threshold is greater than the first threshold. If the vehicle control device 30 makes an affirmative determination in step S804 (S804: YES), it proceeds to step S806. If the vehicle control device 30 makes a negative determination in step S804 (S804: NO), it proceeds to step S808.

[0057] In step S806, the vehicle control device 30 increments the second time counter. The second time counter is 0 at the start of the process in Figure 8. The second time counter is cleared to 0 at the end of the process in Figure 8. The second time counter measures the time for which a positive determination is continuously made in all of steps S800, S802, and S804.

[0058] The vehicle control device 30 proceeds to step S810 after step S806. In step S810, the vehicle control device 30 determines whether the second time counter is equal to or greater than a predetermined period. If the vehicle control device 30 determines that the second time counter is equal to or greater than a predetermined period in step S810 (S810: YES), it proceeds to step S812. If the vehicle control device 30 determines that the second time counter is equal to or greater than a predetermined period in step S810 (S810: NO), it returns to step S800.

[0059] In step S812, the vehicle control device 30 turns on the second ventilation flag. When the second ventilation flag is turned on, it means that the vehicle control device 30 is in a state where it should perform the second ventilation process described later. In step S812, the vehicle control device 30 starts the second ventilation process. According to steps S800 to S812, the vehicle control device 30 performs the second ventilation process based on the fact that the logical AND condition is satisfied for a predetermined period of time. Here, the logical AND condition consists of a condition that discharge of the battery 20 is permitted and a condition that the pressure in the part downstream of the throttle valve 64 is greater than or equal to the first threshold and less than or equal to the second threshold. The second threshold is greater than atmospheric pressure and greater than the first threshold.

[0060] The second ventilation process will be described with reference to Figure 9. The second ventilation process includes operating the hydrogen engine 10 so that the portion downstream of the throttle valve 64 is below a second predetermined pressure. The second ventilation process further includes the first motor generator 16 or the second motor generator 18 assisting the output of the hydrogen engine 10 by discharging the battery 20. In step S900, the vehicle control device 30 sets an upper limit on the shaft torque output from the hydrogen engine 10. This limits the opening of the throttle valve 64 so that the shaft torque output from the hydrogen engine 10 does not exceed the upper limit. According to step S900, the vehicle control device 30 operates the hydrogen engine 10 so that the portion downstream of the throttle valve 64 is below a second predetermined pressure by setting an upper limit on the shaft torque. Next, in step S902, the vehicle control device 30 requests the first motor generator 16 or the second motor generator 18 to assist the output of the hydrogen engine 10 by discharging the battery 20 so that the required power can be achieved. The vehicle control device 30 then completes the flow shown in Figure 9.

[0061] As shown in Figure 8, following step S812, the vehicle control device 30 proceeds to step S814. In step S814, the vehicle control device 30 determines whether the conditions for ending the second ventilation process have been met. The conditions for ending the second ventilation process include the fact that the discharge of the battery 20 is no longer permitted. That is, the fact that the discharge of the battery 20 is no longer permitted means that the SOC has become smaller than the discharge threshold described above. If the vehicle control device 30 determines in step S814 that the conditions have been met (S814: NO), it repeats step S814. If the vehicle control device 30 determines in step S814 that the conditions have been met (S814: YES), it proceeds to step S816.

[0062] In step S816, the vehicle control device 30 turns off the second ventilation flag. In step S816, the vehicle control device 30 terminates the second ventilation process. Specifically, the vehicle control device 30 releases the setting of the upper limit of the shaft torque. The vehicle control device 30 releases the request for output assistance of the hydrogen engine 10 as described above.

[0063] After step S816, the vehicle control device 30 completes the flow shown in Figure 8. <Operation of the second embodiment> When the pressure downstream of the throttle valve 64 is near atmospheric pressure, the first PCV valve 68 and the second PCV valve 74 are closed. This means that the crankcase 42 is not being ventilated.

[0064] If the pressure downstream of the throttle valve 64 remains near atmospheric pressure and charging of the battery 20 is permitted, the vehicle control device 30 performs the first ventilation process (step S410: YES, step S412 in Figure 7).

[0065] If charging of the battery 20 is not permitted, the vehicle control device 30 proceeds to the process shown in Figure 8 (step S400 in Figure 7: NO). If the pressure downstream of the throttle valve 64 remains near atmospheric pressure and the discharge of the battery 20 is permitted, the vehicle control device 30 performs the second ventilation process (step S810 in Figure 8: YES, step S812).

[0066] <Effects of the second embodiment> (2-1) The ventilation process of the first embodiment corresponds to the first ventilation process of the second embodiment. The threshold determination process of the first embodiment corresponds to the first threshold determination process of the second embodiment. If charging of the battery 20 is not permitted, the vehicle control device 30 performs the following processes: The vehicle control device 30 performs a discharge determination process to determine whether or not discharge of the battery 20 is permitted. The vehicle control device 30 performs a second threshold determination process to determine whether or not the pressure in the portion downstream of the throttle valve 64 is above a first threshold (lower than atmospheric pressure) and below a second threshold (higher than atmospheric pressure). The vehicle control device 30 performs a second ventilation process based on the fact that a logical AND condition consisting of the condition that discharge of the battery 20 is permitted and the condition that the pressure in the portion downstream of the throttle valve 64 is above a first threshold and below a second threshold is satisfied for a predetermined period of time. The second ventilation process includes operating the hydrogen engine 10 so that the portion downstream of the throttle valve 64 is below a second predetermined pressure. The second ventilation process further includes the first motor generator 16 or the second motor generator 18 assisting the output of the hydrogen engine 10 by discharging the battery 20.

[0067] Even if charging of the battery 20 is not permitted, if discharging of the battery 20 is permitted, the second ventilation process can be performed. This makes it easier to provide an opportunity for ventilation of the crankcase 42.

[0068] (Example of change) Other elements that can be modified from the first and second embodiments described above are as follows. The following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0069] The configuration of vehicle 100 can be changed as appropriate. For example, vehicle 100 may have only one motor-generator. In this case, the ventilation system 90 comprises the hydrogen engine 10, the single motor-generator, and the vehicle control device 30.

[0070] In the first embodiment described above, the first motor generator 16 or the second motor generator 18 is mechanically indirectly connected to the hydrogen engine 10. Alternatively, the vehicle 100 may be equipped with a motor generator that is mechanically directly connected to the hydrogen engine 10.

[0071] In the first embodiment described above, the logical AND condition consists of a condition that charging of the battery 20 is permitted and a condition that the pressure in the part downstream of the throttle valve 64 is greater than or equal to a first threshold and less than or equal to a second threshold. For example, the logical AND condition may consist of a condition that charging of the battery 20 is permitted and a condition that the pressure in the part downstream of the throttle valve 64 is greater than or equal to a first threshold.

[0072] In the first embodiment described above, the vehicle control device 30 performs ventilation based on the logical AND condition being met for a predetermined period of time. Alternatively, the vehicle control device 30 may perform ventilation based on the logical AND condition being met. That is, the vehicle control device 30 may perform ventilation when the logical AND condition is met instantaneously.

[0073] In the first embodiment described above, the increase in shaft torque generated by supercharging the hydrogen engine 10 is used to charge the battery 20. However, this is merely an example. For example, during ventilation, the first motor generator 16 or the second motor generator 18 may consume at least a portion of the shaft torque output from the hydrogen engine 10 that has increased due to the ventilation process. This is a consumption of shaft torque caused by the first motor generator 16 or the second motor generator 18 being driven around by the hydrogen engine 10.

[0074] • The charging detection process may be omitted. The condition that charging from battery 20 is permitted, which is included in the logical AND condition, may be removed.

[0075] The process of regenerating and charging the battery 20 may be omitted from the ventilation process. In the first embodiment described above, the vehicle control device 30 supercharges the hydrogen engine 10 by increasing the lower limit of the shaft torque output from the hydrogen engine 10. Alternatively, for example, the vehicle control device 30 may increase the shaft torque output from the hydrogen engine 10 to a constant value.

[0076] In the first embodiment described above, the vehicle control device 30 is configured to terminate the ventilation process when the conditions for terminating the ventilation process are met, and the conditions for terminating the ventilation process include the fact that charging of the battery 20 is no longer permitted. The conditions for terminating the ventilation process may also include the condition that the accelerator request has become large enough to cause the hydrogen engine 10 to operate under supercharging. The conditions for terminating the ventilation process may also include the condition that a predetermined period of time has elapsed since the start of the ventilation process.

[0077] In the first and second embodiments described above, each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory). Each of the engine control unit 32, PCU 34, and vehicle control unit 30 executes software processing. However, this is merely an example. For example, each of the engine control unit 32, PCU 34, and vehicle control unit 30 may include a dedicated hardware circuit that processes at least a portion of the software processing executed in the above embodiments. The dedicated hardware circuit is, for example, an ASIC (Application Specific Integrated Circuit). That is, each of the engine control unit 32, PCU 34, and vehicle control unit 30 may have any of the following configurations (a) to (c): (a) Each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a processing unit that executes all processing according to a program, and a program storage device such as a ROM that stores the program. That is, each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a software execution device. (b) Each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a processing unit that executes part of the processing according to a program, and a program storage unit. Furthermore, each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a dedicated hardware circuit that executes the remaining processing. (c) Each of the engine control unit 32, PCU 34, and vehicle control unit 30 includes a dedicated hardware circuit that executes all of the processing. Here, there may be multiple software execution units and / or dedicated hardware circuits. That is, the above processing may be executed by a processing circuitry that includes at least one of a software execution unit and a dedicated hardware circuitry. There may be multiple software execution units and dedicated hardware circuits included in the processing circuitry. The program storage unit, i.e., computer-readable medium, includes a storage device which is any available medium that can be accessed by a general-purpose or dedicated computer.

[0078] <Note> The technical concepts that can be understood from the above embodiments and modified examples are described below. [Note 1] A ventilation system comprising a hydrogen engine and a vehicle control device, The aforementioned hydrogen engine, Intake passage and A compressor of a supercharger installed in the aforementioned intake passage, An air intake passage extends from the aforementioned intake passage to the crankcase, A first PCV (Positive Crankcase Ventilation) valve is provided in the middle of the air intake passage and is configured to open when the portion of the intake passage downstream of the compressor reaches a first predetermined pressure higher than atmospheric pressure, A return passage extending from the portion of the intake passage upstream of the compressor to the crankcase, Equipped with, The vehicle control device includes a processing circuit, and the processing circuit is A threshold determination process that determines whether the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to a first threshold lower than atmospheric pressure, Based on the condition that the pressure in the portion of the intake passage downstream of the compressor is equal to or greater than the first threshold, a ventilation process is performed to supercharge the hydrogen engine so that the portion of the intake passage downstream of the compressor is equal to or greater than the first predetermined pressure, It is configured to do, Ventilation system.

[0079] [Note 2] The processing circuit is configured to perform the ventilation process based on the condition that the pressure in the portion of the intake passage downstream of the compressor is equal to or greater than the first threshold for a predetermined period of time. The ventilation system described in Appendix 1.

[0080] [Note 3] The above condition is that the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to the first threshold and less than or equal to the second threshold, wherein the second threshold is greater than atmospheric pressure and greater than the first threshold. The ventilation system described in Appendix 1 or 2.

[0081] [Note 4] The ventilation system further comprises a motor generator capable of operating as a generator that receives power from the hydrogen engine to generate electricity. The processing circuit is configured to regenerate-charge the battery by the motor generator during the ventilation process if charging of the battery connected to the motor generator is permitted during the ventilation process. A ventilation system as described in any one of the appendices 1 through 3.

[0082] [Note 5] The ventilation system further comprises a motor generator mechanically connected directly or indirectly to the hydrogen engine. The processing circuit is configured to consume at least a portion of the shaft torque output from the hydrogen engine, which is increased due to the ventilation process, by the motor generator during the ventilation process. A ventilation system as described in any one of the appendices 1 through 4.

[0083] [Note 6] The aforementioned hydrogen engine, A blow-by gas passage extending from the crankcase to the portion of the intake passage downstream of the compressor, The system further includes a second PCV valve provided in the middle of the blow-by gas passage and configured to open when the portion downstream of the compressor falls below a second predetermined pressure, which is lower than atmospheric pressure, A ventilation system as described in any one of the appendices 1 through 5.

[0084] [Note 7] The processing circuit brings the hydrogen engine into the supercharged state by increasing the lower limit of the shaft torque output from the hydrogen engine. A ventilation system as described in any one of the appendices 1 through 6.

[0085] [Note 8] The processing circuit is configured to terminate the ventilation process when the termination condition for the ventilation process is met, and the termination condition for the ventilation process includes the fact that charging of the battery is no longer permitted. The ventilation system described in Appendix 4.

[0086] [Note 9] The ventilation system is capable of operating as a generator that receives power from the hydrogen engine to generate electricity, and further comprises a motor generator capable of operating as a power source for the vehicle. The ventilation process is a first ventilation process, and the threshold determination process is a first threshold determination process. The processing circuit, if charging of the battery connected to the motor generator is not permitted, A discharge determination process that determines whether or not the discharge of the battery is permissible, A second threshold determination process that determines whether the pressure in the portion of the intake passage downstream of the compressor is above a first threshold (lower than atmospheric pressure) and below a second threshold (higher than atmospheric pressure), Based on the fact that a logical AND condition consisting of the condition that the discharge of the battery is permitted and the condition that the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to the first threshold and less than or equal to the second threshold is satisfied for a predetermined period of time, the hydrogen engine is operated so that the portion of the intake passage downstream of the compressor is less than or equal to the second predetermined pressure, and a second ventilation process is performed in which the motor generator assists the output of the hydrogen engine by discharging the battery, It is configured to do, The ventilation system described in Appendix 6. [Explanation of symbols]

[0087] 10…Hydrogen engine, 20…Battery, 30…Vehicle control system, 42…Crankcase, 50…Intake passage, 60…Supercharger, 60a…Compressor, 68…First PCV valve, 70…Blow-by gas passage, 72…Recirculation passage, 74…Second PCV valve, 76…Atmospheric intake passage, 90…Ventilation system, 100…Vehicle

Claims

1. A ventilation system comprising a hydrogen engine and a vehicle control device, The aforementioned hydrogen engine, Intake passage and A compressor of a supercharger installed in the aforementioned intake passage, An air intake passage extends from the aforementioned intake passage to the crankcase, A first PCV (Positive Crankcase Ventilation) valve is provided in the middle of the air intake passage and is configured to open when the portion of the intake passage downstream of the compressor reaches a first predetermined pressure higher than atmospheric pressure, A return passage extending from the portion of the intake passage upstream of the compressor to the crankcase, Equipped with, The vehicle control device includes a processing circuit, and the processing circuit is A threshold determination process that determines whether the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to a first threshold lower than atmospheric pressure, Based on the condition that the pressure in the intake passage downstream of the compressor is equal to or greater than the first threshold, a ventilation process is performed to supercharge the hydrogen engine so that the pressure in the intake passage downstream of the compressor is equal to or greater than the first predetermined pressure, It is configured to do, Ventilation system.

2. The processing circuit is configured to perform the ventilation process based on the condition that the pressure in the portion of the intake passage downstream of the compressor is equal to or greater than the first threshold for a predetermined period of time. The ventilation system according to claim 1.

3. The above condition is that the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to the first threshold and less than or equal to the second threshold, wherein the second threshold is greater than atmospheric pressure and greater than the first threshold. The ventilation system according to claim 1 or 2.

4. The ventilation system further comprises a motor generator capable of operating as a generator that receives power from the hydrogen engine to generate electricity. The processing circuit is configured to regenerate-charge the battery by the motor generator during the ventilation process if charging of the battery connected to the motor generator is permitted during the ventilation process. The ventilation system according to claim 1 or 2.

5. The ventilation system further comprises a motor generator mechanically connected directly or indirectly to the hydrogen engine. The processing circuit is configured to consume at least a portion of the shaft torque output from the hydrogen engine, which is increased due to the ventilation process, by the motor generator during the ventilation process. The ventilation system according to claim 1 or 2.

6. The aforementioned hydrogen engine, A blow-by gas passage extending from the crankcase to the portion of the intake passage downstream of the compressor, The system further includes a second PCV valve provided in the middle of the blow-by gas passage and configured to open when the portion downstream of the compressor falls below a second predetermined pressure, which is lower than atmospheric pressure, The ventilation system according to claim 1 or 2.

7. The processing circuit brings the hydrogen engine into the supercharged state by increasing the lower limit of the shaft torque output from the hydrogen engine. The ventilation system according to claim 1 or 2.

8. The processing circuit is configured to terminate the ventilation process when the termination condition for the ventilation process is met, and the termination condition for the ventilation process includes the fact that charging of the battery is no longer permitted. The ventilation system according to claim 4.

9. The ventilation system is capable of operating as a generator that receives power from the hydrogen engine to generate electricity, and further comprises a motor generator capable of operating as a power source for the vehicle. The ventilation process is a first ventilation process, and the threshold determination process is a first threshold determination process. The processing circuit, if charging of the battery connected to the motor generator is not permitted, A discharge determination process that determines whether or not the discharge of the battery is permissible, A second threshold determination process that determines whether the pressure in the portion of the intake passage downstream of the compressor is above a first threshold (lower than atmospheric pressure) and below a second threshold (higher than atmospheric pressure), Based on the fact that a logical AND condition consisting of the condition that the discharge of the battery is permitted and the condition that the pressure in the portion of the intake passage downstream of the compressor is greater than or equal to the first threshold and less than or equal to the second threshold is satisfied for a predetermined period of time, the hydrogen engine is operated so that the portion of the intake passage downstream of the compressor is less than or equal to the second predetermined pressure, and a second ventilation process is performed in which the motor generator assists the output of the hydrogen engine by discharging the battery, It is configured to do, The ventilation system according to claim 6.

Images