Control system for plug-in hybrid vehicles

Abstract

The internal combustion engine can be forcibly started at the user's desired timing. [Solution] The processing circuit 101 performs the following steps: calculates the amount of oil dilution, which is the amount of fuel mixed in the oil stored in the oil pan 29 of the internal combustion engine 11; and, if the calculated amount of oil dilution is greater than or equal to a predetermined threshold, increases the charge level of the battery 39 that allows electric driving by a larger amount than a predetermined value, the greater the amount of oil dilution.

Description

Technical Field

[0001] The present invention relates to a control device for a plug-in hybrid vehicle. Background Art

[0002] In a low-temperature environment, or when the operation and shutdown of an internal combustion engine are repeatedly performed in a short period of time, fuel adhering to the inside of a cylinder mixes into the oil stored in an oil pan of the internal combustion engine, causing oil dilution. For example, as disclosed in Patent Document 1, when an oil dilution amount, which is the amount of fuel mixed into the oil, reaches or exceeds a predetermined threshold, a vehicle control device forcibly starts the internal combustion engine to increase the engine temperature, thereby performing a volatilization process to volatilize the fuel mixed into the oil. Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2023-101940 Summary of Invention Problem to be Solved by the Invention

[0004] Here, in a plug-in hybrid vehicle capable of electric travel that runs only on output from an electric motor, when the state of charge of the battery is sufficient, users of the vehicle expect that electric travel is performed as much as possible without starting the internal combustion engine. Therefore, it is preferable that the above-described forced start of the internal combustion engine is performed at timing desired by the user. Means for Solving the Problem

[0005] A control device for a plug-in hybrid vehicle to solve the above problems is applied to a plug-in hybrid vehicle equipped with an internal combustion engine and an electric motor as a drive source, and a battery that supplies power to the electric motor, and is a control device for a plug-in hybrid vehicle capable of switching between electric driving, in which the vehicle is driven only by the output of the electric motor with the operation of the internal combustion engine stopped, and hybrid driving, in which the output of the internal combustion engine can be used as driving power, and comprises a processing circuit, the processing circuit performs the following: calculates the oil dilution amount, which is the amount of fuel mixed in the oil stored in the oil pan of the internal combustion engine, and if the calculated oil dilution amount is greater than or equal to a predetermined threshold, the process increases the charge level of the battery that permits electric driving by a larger amount than a predetermined value, the greater the oil dilution amount. [Effects of the Invention]

[0006] This invention allows for the forced starting of an internal combustion engine at a timing desired by the user. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a plug-in hybrid vehicle. [Figure 2] Figure 2 is a flowchart showing the steps of the processing circuit. [Modes for carrying out the invention]

[0008] The following describes one embodiment of a control device for a plug-in hybrid vehicle. <Configuration of plug-in hybrid vehicles> As shown in Figure 1, the plug-in hybrid vehicle 10 is equipped with an internal combustion engine 11 and a first electric motor 31 and a second electric motor 32 as a drive source for driving. Each of the first electric motor 31 and the second electric motor 32 functions not only as a motor that generates power by receiving an electrical supply, but also as a generator that generates electricity by receiving power from an external source.

[0009] The plug-in hybrid vehicle 10 is equipped with a power split mechanism 33. The power split mechanism 33 is a planetary gear having three rotating elements: a sun gear S, a ring gear R, and a planetary carrier C. The internal combustion engine 11 is connected to the planetary carrier C of the power split mechanism 33, and the first electric motor 31 is connected to the sun gear S. Furthermore, the second electric motor 32 and the drive wheels 34 are connected to the ring gear R of the power split mechanism 33 via a reduction differential mechanism 35. The first electric motor 31 and the second electric motor 32 are also electrically connected to a battery 39 via an inverter 38. The battery 39 is charged with electricity generated by the first electric motor 31 and the second electric motor 32 using the output of the internal combustion engine 11. The battery 39 supplies the stored electricity to the first electric motor 31 and the second electric motor 32 when they are functioning as motors. The inverter 38 adjusts the amount of power exchanged between the first electric motor 31 and the second electric motor 32 and the battery 39.

[0010] The plug-in hybrid vehicle 10 is equipped with an on-board charger 19. The on-board charger 19 is electrically connected to the battery 39. The on-board charger 19 is also electrically connected to a charging port 18. A charging plug (not shown) is inserted into the charging port 18 from outside the vehicle. The charging plug is connected to an AC power source (not shown). The on-board charger 19 charges the battery 39 by converting the AC power input from the AC power source via the charging plug connected to the charging port 18 into DC power and outputting it.

[0011] The internal combustion engine 11 is equipped with multiple cylinders 12. In this embodiment, there are four cylinders 12. Each cylinder 12 is connected to an intake passage 13 for introducing intake air into the cylinder 12. The downstream side of the intake passage 13 branches into four passages, corresponding to the number of cylinders 12. Each branched passage is connected to a cylinder 12. A fuel injection valve 14 for supplying fuel into each branched passage is also installed.

[0012] Upstream of the branching point in the intake passage 13, a throttle valve 15 is installed to open and close the intake passage 13. The throttle valve 15 adjusts the amount of intake air supplied to each cylinder 12 by changing the cross-sectional area of ​​the intake passage 13.

[0013] An exhaust passage 21 is connected to cylinder 12 for discharging exhaust gas from that cylinder 12. The upstream side of the exhaust passage 21 branches into four, corresponding to the number of cylinders 12. Each branched passage is connected to cylinder 12. Although not shown in the diagram, a water jacket is partitioned inside the internal combustion engine 11 through which cooling water flows to cool the engine 11.

[0014] The internal combustion engine 11 is equipped with an oil pan 29 for storing oil that is supplied to the internal combustion engine 11 and other parts of the system. The oil stored in the oil pan 29 is pumped by an oil pump P. After being supplied to the internal combustion engine 11 and other devices, the oil is returned to the oil pan 29.

[0015] <Control device> The control device 100 applied to the plug-in hybrid vehicle 10 described above comprises a processing circuit 101 that executes a program and performs various processes, and a storage device 102 in which the program is stored. The processing circuit 101 includes a processor. The storage device 102 is capable of storing various types of data.

[0016] The processing circuit 101 acquires detection signals from various sensors installed in the internal combustion engine 11. The internal combustion engine 11 is equipped with an air flow meter 16 and a water temperature sensor 17. The airflow meter 16 is located upstream of the throttle valve 15 in the intake passage 13. The airflow meter 16 detects the intake air volume, which is the flow rate of air flowing through the intake passage 13 that introduces outside air into the internal combustion engine 11. The processing circuit 101 obtains the intake air volume from the airflow meter 16. The water temperature sensor 17 is located at the downstream end of the water jacket. The water temperature sensor 17 detects the coolant temperature, which is the temperature of the coolant. The processing circuit 101 obtains the coolant temperature from the water temperature sensor 17. The processing circuit 101 obtains the state of charge (SOC) from the battery 39.

[0017] <Driving Pattern> The plug-in hybrid vehicle 10 to which the control device 100 is applied is switchable between electric driving and hybrid driving. The processing circuit 101 can perform the process of switching between electric driving and hybrid driving based on the charge rate of the battery 39, etc. Electric driving is a driving mode in which the operation of the internal combustion engine 11 is stopped and the vehicle is driven only by the output of the first electric motor 31 and the second electric motor 32. Hybrid driving is a driving mode in which the output of the internal combustion engine 11 can be used as power for driving.

[0018] The processing circuit 101, when the battery 39's state of charge (SOC) is sufficiently high and equal to or above the permitted charge rate (SOCv), which is the charge rate that allows electric driving, selects electric driving as much as possible without starting the internal combustion engine 11. Furthermore, the processing circuit 101 selects hybrid driving when the battery 39's SOC falls below the permitted charge rate (SOCv). The permitted charge rate (SOCv) is pre-set, for example, 14%, and stored as a default value in the storage device 102.

[0019] Furthermore, if the charge level (SOC) of the battery 39 falls below the permitted charge level (SOCv), the processing circuit 101 uses the output of the internal combustion engine 11 to charge the battery 39 with the power generated by the first motor 31 and the second motor 32. In other words, when the charge level (SOC) of the battery 39 falls below the permitted charge level (SOCv), the processing circuit 101 forcibly starts the internal combustion engine 11 to charge the battery 39.

[0020] <Volatilization Process> The processing circuit 101 executes processing for calculating an oil dilution amount, which is the amount of fuel mixed into oil stored in an oil pan 29, for each predetermined control cycle. Such calculation of the oil dilution amount is well known in the art. For example, the processing circuit 101 calculates a larger estimated value of the amount of fuel mixed into the oil as the intake air amount acquired from the air flow meter 16 increases. Further, the processing circuit 101 calculates a larger estimated value of the amount of fuel mixed into the oil as the coolant temperature acquired from the water temperature sensor 17 increases. Then, a new oil dilution amount is calculated by adding a difference, which is obtained by subtracting the estimated value of the amount of fuel volatilized from the oil from the estimated value of the amount of fuel mixed into the oil, to the oil dilution amount calculated in the previous cycle. Further, the processing circuit 101 calculates a dilution ratio, which is the ratio of the amount of mixed fuel to the total amount of oil stored in the oil pan 29, based on the calculated oil dilution amount. The value of the dilution ratio increases as the oil dilution amount increases.

[0021] When the calculated dilution ratio, in other words, the oil dilution amount is equal to or greater than a predetermined threshold, the processing circuit 101 performs a volatilization process of volatilizing and removing fuel contained in the oil stored in the oil pan 29. When the volatilization process is performed during electric driving, the processing circuit 101 forcibly starts the internal combustion engine 11 and operates the internal combustion engine 11 for a predetermined operating time to increase the temperature of the internal combustion engine 11. As a result, the temperature of the oil stored in the oil pan 29 becomes a temperature sufficient to volatilize the fuel, so the amount of fuel contained in the oil decreases.

[0022] <Allowed Charge Rate Increasing Process> If the calculated dilution ratio, or in other words, the amount of oil dilution, is greater than or equal to a predetermined threshold, the processing circuit 101 executes a process to raise the permitted charge rate (SOCv) of the battery 39 above the default value. If the amount of oil dilution is less than the threshold, the processing circuit 101 does not execute the process to raise the permitted charge rate (SOCv). When the processing circuit 101 executes the process to raise the permitted charge rate (SOCv), the permitted charge rate (SOCv) is raised, for example, from the default value of 14% to 20%. The permitted charge rate (SOCv) after the increase is denoted as [Modified Permitted Charge Rate (SOCv)].

[0023] The processing circuit 101 calculates the permitted charge rate SOCva based on the calculated dilution ratio. If the dilution ratio is 40%, the processing circuit 101 calculates the permitted charge rate SOCva as 25%, and if the dilution ratio is 60%, the processing circuit 101 calculates the permitted charge rate SOCva as 30%. If the dilution ratio is 80%, the processing circuit 101 calculates the permitted charge rate SOCva as 35%. If the dilution ratio is 100%, the processing circuit 101 forces the internal combustion engine 11 to start regardless of the value of the charge rate SOC. In this way, in the process of raising the permitted charge rate SOCv, the processing circuit 101 raises the permitted charge rate SOCv above the default value as the dilution ratio, i.e., the amount of oil diluted, increases.

[0024] The permitted charge rate SOCva, calculated based on the dilution ratio, may be estimated by calculation, or it may be calculated using a data map or table pre-stored in the memory device 102. In short, as long as the permitted charge rate SOCva can be calculated based on the acquired dilution ratio, the calculation method is arbitrary.

[0025] <Processing performed by the processing circuit> Figure 2 shows the procedure for the processing circuit 101 to be executed at predetermined intervals. In the following, the step number of each process is represented by a number preceded by "S".

[0026] When the series of processes shown in Figure 2 is started, the processing circuit 101 acquires the currently calculated oil dilution amount (S100). If the acquired oil dilution amount is greater than or equal to a threshold, the processing circuit 101 calculates a dilution ratio based on the acquired oil dilution amount and calculates the permitted charge rate SOCva based on that dilution ratio (S110). The calculated permitted charge rate SOCva is stored in the memory device 102. Then, when the charge rate SOC of the battery 39 falls below the permitted charge rate SOCva during electric driving, the processing circuit 101 forcibly starts the internal combustion engine 11 to charge the battery 39 (S120). After that, the processing circuit 101 temporarily terminates the series of processes shown in Figure 2.

[0027] When the internal combustion engine 11 is forcibly started by the S120 process, the internal combustion engine 11, which had been stopped, begins to operate. This raises the temperature of the internal combustion engine 11. As the above process is repeated, the temperature of the oil stored in the oil pan 29 reaches a temperature sufficient to vaporize the fuel, and thus the amount of fuel contained in the oil decreases.

[0028] [Effects and Effects of the Embodiment] According to the above embodiment, the following actions and effects can be obtained. (1) If the oil dilution amount is above a threshold, the processing circuit 101 performs a process to raise the permitted charge rate (SOCv) of the battery 39 from the default value. As a result, compared to when the permitted charge rate (SOCv) is not raised, the forced start of the internal combustion engine 11 for the purpose of charging the battery 39 is performed earlier, and the number of forced starts is increased. For users who expect to drive on electric power as much as possible, the forced start for charging the battery 39 is not a problem, so the forced start of the internal combustion engine 11, which is performed to reduce the amount of fuel contained in the oil, is performed at a timing that is desirable for the user. [Explanation of Symbols]

[0029] 10...Plug-in hybrid vehicle, 11...Internal combustion engine, 29...Oil pan, 39...Battery, 31...First electric motor, 32...Second electric motor, 100...Control device, 101...Processing circuit.

Claims

[Claim 1] A control device for a plug-in hybrid vehicle, which is equipped with an internal combustion engine and an electric motor as a drive source and a battery that supplies power to the electric motor, and which can perform a process to switch between electric driving, in which the vehicle is driven only by the output of the electric motor with the operation of the internal combustion engine stopped, and hybrid driving, in which the output of the internal combustion engine can be used as the power for driving, Equipped with a processing circuit, The aforementioned processing circuit A process for calculating the oil dilution amount, which is the amount of fuel mixed in the oil stored in the oil pan of the internal combustion engine, If the calculated oil dilution amount is greater than or equal to a predetermined threshold, the greater the oil dilution amount, the greater the charge level of the battery that allows electric driving is raised above a predetermined value. A control device for plug-in hybrid vehicles that performs the following actions.

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