Control system for plug-in hybrid vehicles

Abstract

Even if an internal combustion engine is forcibly started, it can be made difficult for the user to know that the engine is running. [Solution] The processing circuit 101 performs the following: calculates the oil dilution amount, which is the amount of fuel mixed in the oil stored in the oil pan 29 of the internal combustion engine 11; and, when the vehicle is running on electric power, if the calculated oil dilution amount is above a predetermined threshold, it forcibly starts the internal combustion engine 11 at a vehicle speed set higher the lower the calculated oil dilution amount.

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 stoppage of an internal combustion engine are repeated in a short period of time, fuel adhering to the inside of a cylinder mixes into 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 the Invention] [Problem to be Solved by the Invention]

[0004] Here, in a plug-in hybrid vehicle capable of electric travel that is powered only by the output of an electric motor, when the state of charge of the battery is sufficient, vehicle users expect that electric travel will be performed as much as possible without starting the internal combustion engine. Therefore, even when the aforementioned forced start of the internal combustion engine is initiated, it is preferable that the engine operation resulting from the forced start is not noticeable to 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 is a control device for a plug-in hybrid vehicle that performs a process to switch between electric driving, in which the vehicle runs using only 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 power for driving, and comprises a processing circuit, the processing circuit performs a process to calculate 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, in the case of electric driving, if the calculated oil dilution amount is above a predetermined threshold, the process to forcibly start the internal combustion engine at a vehicle speed set higher the lower the calculated oil dilution amount. [Effects of the Invention]

[0006] This invention makes it difficult for the user to know that an internal combustion engine is running, even if it is forcibly started. [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 the charging port 20. A charging plug (not shown) is inserted into the charging port 20 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 20 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, a water temperature sensor 17, and a vehicle speed sensor 18.

[0017] 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 vehicle speed sensor 18 detects the vehicle speed SPD, which is the driving speed of the plug-in hybrid vehicle 10. The processing circuit 101 obtains the vehicle speed SPD of the plug-in hybrid vehicle 10 from the vehicle speed sensor 18.

[0018] <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 level 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. When the charge level of the battery 39 is sufficiently high, the processing circuit 101 selects electric driving as much as possible without starting the internal combustion engine 11. Also, when the charge level of the battery 39 falls to a predetermined value, the processing circuit 101 selects hybrid driving.

[0019] <Volatile treatment> The processing circuit 101 executes, for each predetermined control cycle, a process of calculating an oil dilution amount that is the amount of fuel mixed in the oil stored in the oil pan 29. Such calculation of the oil dilution amount is well known. 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 obtained from the air flow meter 16 is larger. Further, the processing circuit 101 calculates a larger estimated value of the amount of fuel mixed into the oil as the coolant temperature obtained from the water temperature sensor 17 is higher. Then, a new oil dilution amount is calculated by adding the difference 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.

[0020] Then, 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 for volatilizing and removing the fuel contained in the oil stored in the oil pan 29. When performing the volatilization process during electric travel, the processing circuit 101 forcibly starts the internal combustion engine 11 and operates the internal combustion engine 11 for a predetermined operation 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.

[0021] <Target Vehicle Speed Setting Process> The processing circuit 101 executes a process of calculating a target vehicle speed SPDt, which is a vehicle speed SPD at which the internal combustion engine 11 is forcibly started during electric driving, when the calculated dilution ratio, in other words, the oil dilution amount is equal to or greater than a predetermined threshold. If the oil dilution amount is less than the threshold, the processing circuit 101 does not execute the process of calculating the target vehicle speed SPDt. For example, when the dilution ratio is 20%, the processing circuit 101 calculates 100 km / h as the target vehicle speed SPDt; when the dilution ratio is 40%, the processing circuit 101 calculates 80 km / h as the target vehicle speed SPDt. When the dilution ratio is 60%, the processing circuit 101 calculates 60 km / h as the target vehicle speed SPDt; when the dilution ratio is 80%, the processing circuit 101 calculates 40 km / h as the target vehicle speed SPDt. As described above, the processing circuit 101 calculates a higher vehicle speed SPD as the target vehicle speed SPDt when the dilution ratio is lower, that is, when the oil dilution amount is smaller. Further, when the dilution ratio is 100%, the processing circuit 101 forcibly starts the internal combustion engine 11 without calculating the target vehicle speed SPDt.

[0022] Note that the target vehicle speed SPDt calculated based on the oil dilution amount may be calculated by computation, or may be calculated using a data map or table pre-stored in the storage device 102. In short, any calculation method is acceptable as long as the target vehicle speed SPDt can be calculated from the acquired oil dilution amount.

[0023] <Processing Performed by Processing Circuit> FIG. 2 shows a procedure of processing executed by the processing circuit 101 at predetermined intervals. In the following description, step numbers of respective processes are represented by numerals prefixed with "S".

[0024] When the series of processes shown in Figure 2 is initiated, the processing circuit 101 acquires the currently calculated oil dilution amount (S100). Based on the acquired oil dilution amount, the processing circuit 101 calculates the dilution ratio and, based on the calculated dilution ratio, calculates the target vehicle speed SPDt for forced starting (S110). When the vehicle speed SPD of the plug-in hybrid vehicle 10 reaches the calculated target vehicle speed SPDt during electric driving, the processing circuit 101 forcibly starts the internal combustion engine 11 (S120). After that, the processing circuit 101 temporarily terminates the series of processes shown in Figure 2.

[0025] As described above, the processing circuit 101 calculates a higher target vehicle speed SPDt the less oil dilution it has. Therefore, the less oil dilution it has, the higher the vehicle speed SPD at which the internal combustion engine 11 is forcibly started. Accordingly, when the vehicle is running on electric power, if the calculated oil dilution amount is above a predetermined threshold, the processing circuit 101 executes a process to forcibly start the internal combustion engine 11 at a vehicle speed SPD that is set higher the less the calculated oil dilution amount has.

[0026] 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.

[0027] [Effects and Effects of the Embodiment] According to the above embodiment, the following actions and effects can be obtained. (1) When the vehicle is running on electric power, if the oil dilution amount is above a threshold, the processing circuit 101 forces the internal combustion engine 11 to start. Forcing the internal combustion engine 11 to start raises its temperature, which causes the fuel mixed in the oil to volatilize and reduces the amount of fuel mixed in the oil. For the process of forcing the internal combustion engine 11 to start, the vehicle speed SPD is calculated as the target vehicle speed SPDt, which is set higher the lower the oil dilution amount. Therefore, when the oil dilution amount is low, even if the internal combustion engine 11 is forcibly started, its starting sound is easily masked by the driving sound at high vehicle speeds. Thus, even if the internal combustion engine 11 is forcibly started, it is difficult for the user to notice that the engine is running, making this a desirable process for users who hope to run on electric power as much as possible. Furthermore, when the oil dilution amount is high, the internal combustion engine 11 is forcibly started at a low vehicle speed, which promotes the warming up of the internal combustion engine 11 and reduces the amount of fuel mixed in the oil. [Explanation of Symbols]

[0028] 10...Plug-in hybrid vehicle, 11...Internal combustion engine, 29...Oil pan, 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 applied to a plug-in hybrid vehicle equipped with an internal combustion engine and an electric motor as a drive source, and which performs a process to switch between electric driving, in which the operation of the internal combustion engine is stopped and the vehicle is driven only by the output of the electric motor, 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 processing circuit described above 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, During the aforementioned electric driving, if the calculated oil dilution amount is greater than or equal to a predetermined threshold, the internal combustion engine is forcibly started at a vehicle speed set higher the less the calculated oil dilution amount is. A control device for plug-in hybrid vehicles that performs the following actions.

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