Vehicle control system

Abstract

The objective is to suppress the generation of unburned fuel in internal combustion engines that use alcohol fuel. [Solution] The vehicle control device is a vehicle control device for a vehicle equipped with an internal combustion engine that can use alcohol fuel, and when it is determined that the alcohol concentration of the alcohol fuel is above a predetermined value and the internal combustion engine is in a cold start state, it performs control to fix the shift position of the shift device equipped with the vehicle to a shift position that puts the vehicle in a stationary state using the shift lock mechanism equipped with the vehicle, until it is determined that the warm-up of the internal combustion engine is complete.

Description

Technical Field

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[0001] The present invention relates to a control device for a vehicle.

Background Art

[0002] Recently, FFVs (Flexible-fuel vehicles) that can use alcohol fuels such as ethanol have emerged. Alcohol fuels have lower volatility compared to gasoline fuels. Therefore, in FFVs using alcohol fuels, the starting performance of the internal combustion engine at low temperatures and the drivability immediately after starting may deteriorate. Conventionally, when it is in a low-temperature region where the coolant temperature of the internal combustion engine is lower than a predetermined value and in a high-concentration region where the alcohol concentration of the main fuel is higher than a predetermined value, a proposal has been made to increase the injection amount of the main fuel for correction (see, for example, Patent Document 1). According to Patent Document 1, it is possible to suppress the deterioration of the starting performance of the internal combustion engine at low temperatures and the drivability immediately after starting.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, alcohol fuels have low volatility as described above. Therefore, the fuel concentration in the in-cylinder mixture becomes thin, and output reduction is likely to occur. Also, the unburned fuel that could not be vaporized is likely to increase. When the unburned fuel increases, there is a concern that emissions may deteriorate or so-called catalyst OT (Over Temperature) may occur, in which the unburned fuel burns in the catalyst. Recently, FFVs are required to cope with further low-temperature of their usage environment. For this reason, there is a concern that the above problems may become more prominent.

[0005] Patent Document 1 can compensate for the decrease in output by increasing the injection amount of the main fuel, but there is room for improvement in that unburned fuel is easily generated.

[0006] Therefore, the present invention aims to suppress the generation of unburned fuel in internal combustion engines that use alcohol fuel. [Means for solving the problem]

[0007] The above objective is achieved by a vehicle control device for a vehicle equipped with an internal combustion engine that can use alcohol fuel, wherein when the alcohol concentration of the alcohol fuel is determined to be above a predetermined value and the internal combustion engine is being cold-started, the vehicle control device performs control to fix the shift position of the vehicle's shift device to a shift position that puts the vehicle in a stationary state using a shift lock mechanism provided in the vehicle, until it is determined that the internal combustion engine has finished warming up. [Effects of the Invention]

[0008] This can suppress the generation of unburned fuel in internal combustion engines that use alcohol fuel. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram illustrating a hybrid vehicle to which the vehicle control device of the embodiment is applied. [Figure 2] Figure 2 is a flowchart illustrating the processes performed by the vehicle control device of the embodiment. [Modes for carrying out the invention]

[0010] (Embodiment) The control device of the vehicle according to the embodiment will be described below with reference to the drawings.

[0011] [Hybrid Vehicle Configuration] Figure 1 is a schematic diagram illustrating a hybrid electric vehicle (Hybrid Vehicle) 1. The hybrid vehicle 1 comprises an internal combustion engine 10, a motor generator (motor MG1 and motor MG2), a battery 32, a battery ECU (Electronic Control Unit) 34, an HV (hybrid) ECU 40, an engine ECU 42, and a motor ECU 44.

[0012] Hybrid vehicle 1 is capable of both HV (hybrid vehicle) and EV (electric vehicle) driving. In HV driving, the operation of the internal combustion engine 10 and the motor MG are operated in cooperation. In EV driving, the internal combustion engine 10 is not operated, and the vehicle is driven by the motor MG using the power from the battery 32. Hybrid vehicle 1 can be driven in CS (Charge Sustaining) mode, which maintains the charge level (SOC: State of Charge) of the battery 32 near the control center, and CD (Charge Depleting) mode, which consumes the charge level (SOC) of the battery 32.

[0013] Hybrid vehicle 1 is a fast-drive vehicle (FFV) that can use alcohol fuel such as ethanol as fuel for its internal combustion engine 10. The internal combustion engine 10 includes a cylinder block, pistons, crankshaft, intake valves, exhaust valves, intake passages, exhaust passages, catalytic converter, fuel injectors, and spark plugs. Since each of these components is conventionally known, a detailed explanation of them is omitted here. Furthermore, a description of auxiliary equipment for the internal combustion engine 10, such as the oil pump, is also omitted.

[0014] The internal combustion engine 10 can achieve an Atkinson cycle in which the compression ratio is smaller than the expansion ratio. The internal combustion engine 10 can change the opening and closing timing of the intake valves by a hydraulically operated variable valve timing mechanism (VVT) 67. The internal combustion engine 10 can achieve an Atkinson cycle by retarding the intake valve closing timing (IVC) using the VVT ​​67. The internal combustion engine 10 can improve starting performance by advancing the IVC at startup. In addition, advancing the IVC improves the combustibility of the air-fuel mixture, which accelerates the warm-up of the internal combustion engine 10.

[0015] Motors MG1 and MG2, shown in Figure 1, are powered by electricity supplied from battery 32.

[0016] The planetary gear 14 is connected to the crankshaft (not shown) of the internal combustion engine 10 via a damper 12, and also to motors MG1 and MG2. Motor MG2 is connected to the drive wheels 1a of the hybrid vehicle 1 via a differential gear 16. The driving force generated by the internal combustion engine 10, motors MG1 and MG2 is transmitted to the drive wheels 1a, and the hybrid vehicle 1 moves.

[0017] Inverter 20 is electrically connected to motor MG1 and battery 32. Inverter 22 is electrically connected to motor MG2 and battery 32. Inverter 20 converts the AC power generated by motor MG1 into DC power and supplies it to battery 32, and converts the DC power from battery 32 into AC power and supplies it to motor MG1. Inverter 22 similarly converts between DC power and AC power.

[0018] The hybrid vehicle 1 is equipped with a shift device 13. The shift device 13 switches the transmission to the P (Parking) range, N (Neutral) range, and D (Drive) range, etc. The hybrid vehicle 1 is also equipped with a shift lock mechanism 15 that locks the shift device 13 in a shift position that puts the hybrid vehicle 1 in a stationary state, such as the P range or N range. The shift lock mechanism 15 can be a conventionally known mechanism, so a detailed explanation thereof is omitted here. When the shift position of the hybrid vehicle 1 is locked in the P range or N range by the shift lock mechanism 15, the hybrid vehicle 1 becomes inoperable.

[0019] The battery ECU34, HVECU40, engine ECU42, and motor ECU44 each contain a processing unit such as a CPU (Central Processing Unit), and storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory). These ECUs constitute the vehicle's control system.

[0020] The motor ECU 44 controls inverters 20 and 22, motor MG1, and motor MG2. The battery ECU 34 monitors the state of charge (SOC) of battery 32 and controls the SOC control center, the upper limit of the power output of battery 32, and other parameters.

[0021] The HVECU 40 is connected to the battery ECU 34, the engine ECU 42, and the motor ECU 44. The HVECU 40 controls the switching between the CS mode and the CD mode. The switching of the driving mode can also be performed, for example, when the user operates a mode switch (not shown). The HVECU 40 acquires the accelerator opening detected by the accelerator opening sensor 11 and determines the required output based on the accelerator opening. The HVECU 40 controls the start and stop of the internal combustion engine 10. In the present embodiment, an ignition switch (IG) 46, a shift position sensor 48, an alcohol concentration sensor 50, a water temperature sensor 52, and an oil temperature sensor 54 are electrically connected to the HVECU 40. The IG 46 starts and stops each ECU provided in the hybrid vehicle 1. When the IG 46 is turned on, each ECU starts, and the hybrid vehicle 1 is in a ready state for running. The shift position sensor 48 detects the shift position in the shift device 13. When shift-by-wire is adopted, the HVECU 40 holds information regarding the shift position, and thus the shift position sensor 48 may be omitted. The alcohol concentration sensor 50 detects the alcohol concentration of the fuel. The water temperature sensor 52 detects the temperature of the cooling water circulating in the internal combustion engine 10. The oil temperature sensor 54 detects the temperature of the lubricating oil circulating in the internal combustion engine 10. The lubricating oil is also used for driving the VVT 67.

[0022] The HVECU 40 is electrically connected to a shift lock mechanism 15. The shift lock mechanism 15 locks the shift device 13 based on the shift lock signal of the HVECU 40.

[0023] The engine ECU 42 controls the fuel injection amount and injection timing from the fuel injection valve. The engine ECU 42 controls the ignition timing by the ignition plug. The engine ECU 42 acquires the amount of air (actual air amount) detected by the air flow meter. The engine ECU 42 changes the actual air amount by controlling the opening degree of the throttle valve. The engine ECU 42 acquires the rotation angle detected by the crank angle sensor and acquires the rotational speed of the internal combustion engine 10 based on the rotation angle. The engine ECU 42 calculates the required torque of the internal combustion engine 10 based on the required output, rotational speed, etc.

[0024] [Vehicle Control] Next, an example of the process executed by the vehicle control device of the present embodiment will be described. As a process to be executed, the vehicle control device of the present embodiment fixes the shift position to the P range or the N range. That is, the control device sets the hybrid vehicle in a state where it cannot run under predetermined conditions. If the shift position is fixed to the P range or the N range and the hybrid vehicle 1 cannot run, the driver is prevented from stepping on the accelerator pedal. As a result, fuel injection in a state where fuel is difficult to vaporize is avoided, and the occurrence of unburned combustion is suppressed.

[0025] Here, the situation where the process is executed and the process policy will be described. The process of fixing the shift position is applied when it is determined that the alcohol concentration of the alcohol fuel is equal to or higher than a predetermined value and the internal combustion engine 10 is cold-started. Alcohol fuel has lower volatility compared to gasoline, and the higher the alcohol concentration, the lower the volatility. When the volatility of the fuel is low, unburned fuel may occur, and emissions may deteriorate. In addition, unburned fuel may reach the catalyst, and unburned fuel may burn in the catalyst, causing catalyst OT. Therefore, the fact that the alcohol concentration, which is one of the causes of these phenomena, is equal to or higher than a predetermined value is one of the conditions for executing the process.

[0026] When the internal combustion engine 10 is cold-started, the alcohol fuel becomes even less volatile, making it easier for unburned fuel to be generated. Also, when the internal combustion engine 10 is cold-started, the viscosity of the lubricating oil that drives the VVT ​​67 is high, and the oil pressure does not rise easily, resulting in slow operation of the VVT ​​67. As a result, it becomes difficult to advance the IVC. If the IVC cannot be advanced, there is a possibility that intake air that has entered the cylinder will be blown back into the intake port. When intake air is blown back, the amount of air in the cylinder decreases, and combustibility deteriorates. As a result, the warm-up of the internal combustion engine 10 is delayed, and the condition in which unburned fuel is easily generated is prolonged. Therefore, the cold-start condition of the internal combustion engine 10, which is one of the causes of these phenomena, is considered one of the conditions for executing the process.

[0027] First, in step S1, HVECU40 determines whether the system state is OFF or not. Specifically, it determines whether IG46 is OFF or not. If the result in step S1 is positive (Yes), the process proceeds to step S2. If the result in step S1 is negative (No), the process ends.

[0028] In step S2, the HVECU40 determines whether a system startup operation has occurred. Specifically, it determines whether IG46 has been operated and turned ON. If the determination in step S2 is Yes, the process proceeds to step S3. If the determination in step S2 is No, the process ends.

[0029] In step S3, the HVECU 40 determines whether the shift position is within the activating range based on the value detected by the shift position sensor 48. Specifically, it determines whether the shift position is in the P range or the N range. If the determination in step S3 is Yes, the process proceeds to step S4. If the determination in step S3 is No, the process ends.

[0030] In step S4, the HVECU 40 activates each ECU, such as the engine ECU 42. The engine ECU 42 also starts the internal combustion engine 10. After executing the process in step S4, the HVECU 40 proceeds to step S5. At the time of executing the process in step S4, the shift lock mechanism 15 has the shift position fixed in the P range or N range.

[0031] In step S5, the HVECU 40 determines whether the alcohol concentration is higher than a preset threshold based on the detection value of the alcohol concentration sensor 50. Specifically, it determines whether the alcohol concentration is higher than E85. If the determination in step S5 is Yes, the process proceeds to step S6. If the determination in step S5 is No, the process ends. In this embodiment, E85 is used as the threshold because it is known that alcohol concentrations higher than E85 are difficult to vaporize, but this value is just an example, and other values ​​may be used as appropriate.

[0032] In step S6, the HVECU 40 determines, based on the value detected by the water temperature sensor 52, whether the engine coolant temperature is lower than a preset threshold. Here, the threshold is a value that has been set in advance through experiments and simulations as a value at which it can be determined that the internal combustion engine 10 has finished warming up. If the result in step S6 is Yes, the process proceeds to step S7. If the result in step S6 is No, the process proceeds to step S11.

[0033] In step S11, the HVECU 40 releases the shift lock by the shift lock mechanism 15. This allows the driver to change the shift position, and for example, by shifting to the D range, the hybrid vehicle 1 can be driven.

[0034] In step S7, the HVECU 40 determines, based on the value detected by the oil temperature sensor 54, whether the engine oil temperature is lower than a preset threshold. Here, the threshold is a value that has been set in advance through experiments or simulations as a value at which it can be determined that the warm-up of the internal combustion engine 10 is complete. The threshold can be set, for example, to a temperature that can guarantee the operation of the VVT ​​67. Note that the determination of whether the warm-up of the internal combustion engine 10 is complete may be performed only by the process in step S6 based on the engine coolant temperature. However, by determining the engine oil temperature in step S7, it is possible to detect, for example, when the internal combustion engine 10 is in a restart state. Comparing water temperature and engine oil temperature, water temperature rises and falls more easily. Therefore, when the internal combustion engine 10 is restarting, the water temperature may be lower than the threshold, but the engine oil temperature may be higher than the threshold. In such a temperature state, it is also assumed that the volatility of the alcohol fuel is not very low. By determining the engine oil temperature, it is possible to isolate and control such a state. If Yes is determined in step S7, the process proceeds to step S8. If the result in step S7 is No, the process proceeds to step S11. In other words, when the internal combustion engine 10 is restarted, the shift lock is released, and the hybrid vehicle 1 can be driven. The determination of when the internal combustion engine 10 has finished warming up can be made using conventionally known methods, either in place of or in conjunction with determinations based on water temperature or engine oil temperature.

[0035] In step S8, the HVECU 40 starts counting the shift lock duration. Then, in step S9, the HVECU 40 determines whether the shift lock duration has exceeded a preset threshold. Here, the shift lock duration is a time set in advance through experiments and simulations as the time it takes to transition to a state where the evaporation of alcohol fuel is accelerated. If the determination in step S9 is Yes, the process proceeds to step S10. If the determination in step S9 is No, the process proceeds to step S11. By proceeding to step S11, for example, even if the water temperature or engine oil temperature is not measured properly, the hybrid vehicle 1 can be brought into a state where it can be driven.

[0036] In step S10, the HVECU40 maintains the shift lock state. Then, the process from step S6 is repeated. By maintaining the shift lock state, the driver is prevented from pressing the accelerator pedal. As a result, fuel injection in a state where fuel is difficult to vaporize is avoided, and the occurrence of unburned combustion is suppressed.

[0037] The series of processes ultimately ends (END) via step S11.

[0038] [Effects] The control device of this embodiment locks the vehicle in a stationary position when it is determined that the alcohol concentration of the alcohol fuel is above a predetermined value and the internal combustion engine 10 is in a cold start state. This prevents the accelerator from being pressed when the fuel is in a state where it is difficult to volatilize, and suppresses the generation of unburned fuel. As a result, deterioration of emissions and catalytic converter OT are avoided.

[0039] Although the control device of this embodiment is intended for hybrid vehicles 1, it can also be applied to vehicles that use only an internal combustion engine 10 as a power source. In other words, any FFV equipped with an internal combustion engine 10 that can use alcohol fuel can be controlled. Furthermore, FFVs equipped with an internal combustion engine that is not equipped with VVT67 can also be controlled.

[0040] Furthermore, in this embodiment, the process illustrated in Figure 2 is performed by the HVECU 40, but other ECUs may perform similar processes. Alternatively, a separate control unit may be provided to perform the process illustrated in Figure 2.

[0041] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0042] 1…Hybrid vehicle, 1a…Drive wheels, 10…Internal combustion engine, 11…Accelerator position sensor, 12…Damper, 13…Shift mechanism, 14…Planetary gear, 15…Shift lock mechanism, 16…Differential gear, 20, 22…Inverter, 32…Battery, 34…Battery ECU, 40…HVECU, 42…Engine ECU, 44…Motor ECU, 46…Ignition, 48…Shift position sensor, 50…Alcohol concentration sensor, 52…Water temperature sensor, 54…Oil temperature sensor, 67…VVT, MG1, MG2…Motor

Claims

[Claim 1] A control device for a vehicle equipped with an internal combustion engine that can use alcohol fuel, If the alcohol concentration of the alcohol fuel is above a predetermined value and it is determined that the internal combustion engine is in a cold start state, the vehicle will execute control to fix the shift position of the vehicle's shift device to a shift position that puts the vehicle in a stationary state using the vehicle's shift lock mechanism until it is determined that the internal combustion engine has finished warming up. Vehicle control system.

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