Control device for hybrid vehicle

Abstract

The present invention provides a control device for a hybrid vehicle capable of appropriately operating an engine even when the moisture ratio of fuel in a fuel tank is increased. This control device for a hybrid vehicle is provided with, as the power source of the vehicle, both an engine and an electric motor that can be operated using a fuel containing an alcohol, and is provided with: a moisture ratio calculation unit that calculates the moisture ratio of the engine to the electric motor; calculating the moisture ratio of the fuel in the fuel tank when the engine is started; and an injection amount control unit that, when the value of the moisture ratio of the fuel in the fuel tank calculated by the moisture ratio calculation unit is higher than a predetermined value, increases the fuel injection amount in accordance with the value of the moisture ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to a control device of a hybrid vehicle. BACKGROUND

[0002] In the past, a hybrid vehicle that has both an engine and an electric motor as a power source of a vehicle, which can operate using fuel containing alcohol, has been known (for example, refer to Patent Literature 1).

[0003] PRIOR ART DOCUMENT

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2019-189026 SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, moisture is sometimes contained in alcohol fuel. In recent years, the opportunity to use bioethanol fuel, which is one type of alcohol fuel, is also increasing. Bioethanol fuel mostly contains moisture. Volatile components contained in bioethanol fuel sometimes evaporate inside a fuel tank provided in a hybrid vehicle. When the evaporation of volatile components inside the fuel tank progresses, the moisture ratio in the fuel becomes high.

[0007] In recent years, plug-in hybrid vehicles that can be externally powered are also increasing. Plug-in hybrid vehicles have a tendency to have a large battery capacity and a reduced frequency of engine operation. When the frequency of engine operation is reduced, the opportunity to replace the fuel inside the fuel tank decreases. As a result, the moisture ratio in the fuel inside the fuel tank becomes high.

[0008] When fuel with a high moisture ratio is used, it is possible that torque reduction or misfire, which affects the operation of the engine, occurs in the engine.

[0009] In Patent Literature 1, countermeasures when the moisture ratio in the fuel becomes high are not studied.

[0010] Therefore, an object of the present application is to provide a control device of a hybrid vehicle that can appropriately operate the engine even when the moisture ratio in the fuel inside the fuel tank becomes high.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] The above object can be achieved by a control device for a hybrid vehicle that has an engine and an electric motor as power sources for the vehicle, the engine being capable of operating using fuel containing alcohol, the control device for the hybrid vehicle comprising: a moisture ratio calculation section that calculates a moisture ratio of the fuel in a fuel tank at engine start; and an injection amount control section that increases the fuel injection amount in accordance with the value of the moisture ratio of the fuel in the fuel tank calculated by the moisture ratio calculation section when the value of the moisture ratio of the fuel in the fuel tank calculated by the moisture ratio calculation section is higher than a predetermined value.

[0013] Effects of Invention

[0014] A control device for a hybrid vehicle that appropriately operates the engine even when the moisture ratio of the fuel in the fuel tank is high can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic configuration diagram of a hybrid vehicle.

[0016] Figure 2 is an example of a time chart showing changes in the use state of the engine and the electric motor, the amount of moisture in the fuel tank, the moisture ratio in the fuel tank, and the A / F value in the hybrid vehicle.

[0017] Figure 3 (A) of is an example of a flowchart showing control of the hybrid vehicle. Figure 3 (B) of is an example of a map for setting the fuel injection amount based on the moisture ratio in the fuel tank. DETAILED DESCRIPTION

[0018] [Schematic Configuration of Hybrid Vehicle]

[0019] Figure 1 is a schematic configuration diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a K0 clutch 14, an electric motor (hereinafter, simply referred to as "motor") 15, a wet clutch 18, and a transmission 19 are provided in this order on a power transmission path from an engine 10 to drive wheels 13. The engine 10 and the motor 15 are mounted as power sources for running of the hybrid vehicle 1. The engine 10 is, for example, an in-line four-cylinder engine, but the number of cylinders is not limited thereto, and a V-type or a horizontally opposed engine can also be used. The engine 10 corresponds to an alcohol fuel and is capable of using bioethanol fuel. In the present embodiment, bioethanol fuel is used. The K0 clutch 14, the motor 15, the wet clutch 18, and the transmission 19 are provided in a transmission unit 11. The transmission unit 11 is drivingly connected to the left and right drive wheels 13 via a differential 12.

[0020] The K0 clutch 14 is provided on the power transmission path between the engine 10 and the motor 15. The K0 clutch 14 becomes an engaged state by receiving supply of hydraulic pressure from a disengaged state, and connects the power transmission between the engine 10 and the motor 15. The K0 clutch 14 becomes a disengaged state by stopping the supply of hydraulic pressure, and cuts off the power transmission between the engine 10 and the motor 15. The engaged state is a state in which both engagement elements of the K0 clutch 14 are linked and the engine 10 and the motor 15 become the same rotational speed. The disengaged state is a state in which both engagement elements of the K0 clutch 14 are disengaged.

[0021] The motor 15 is connected to the battery 16 via the inverter 17. The motor 15 functions as a motor that generates a driving force of the vehicle in accordance with the supply of electric power from the battery 16, and also functions as a generator that generates electric power to charge the battery 16 in accordance with the power transmission from the engine 10, the drive wheels 13. The electric power received and given between the motor 15 and the battery 16 is adjusted by the inverter 17. The battery 16 is provided with a charging mechanism 40 that can be charged from an external power source. The hybrid vehicle is a so-called plug-in hybrid vehicle.

[0022] The inverter 17 is controlled by an ECU (Electronic Control Unit) 100 described later, converts the direct-current voltage from the battery 16 into alternating-current voltage, or converts the alternating-current voltage from the motor 15 into direct-current voltage. In the case of traction running in which the motor 15 outputs torque, the inverter 17 converts the direct-current voltage of the battery 16 into alternating-current voltage and adjusts the electric power supplied to the motor 15. In the case of regenerative running in which the motor 15 generates electric power, the inverter 17 converts the alternating-current voltage from the motor 15 into direct-current voltage and adjusts the electric power supplied to the battery 16.

[0023] The transmission 19 is a stepped automatic transmission that switches the gear ratio in a plurality of stages by switching of gear stages, but is not limited thereto, and can be a continuously variable automatic transmission. The transmission 19 is provided on the power transmission path between the motor 15 and the drive wheels 13. A wet clutch 18 that becomes an engaged state by receiving supply of hydraulic pressure and directly links the motor 15 and the transmission 19 is provided.

[0024] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic pressure control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the wet clutch 18, and the transmission 19 via the hydraulic pressure control mechanism 22, respectively. In the hydraulic pressure control mechanism 22, a hydraulic circuit of each of the K0 clutch 14, the wet clutch 18, and the transmission 19 and various hydraulic pressure control valves for controlling the working hydraulic pressure thereof are provided. In addition, a torque converter provided with a lock-up clutch can be provided instead of the wet clutch 18.

[0025] The hybrid vehicle 1 is provided with a fuel tank 30 that stores fuel supplied to the engine 10. A fuel gauge 30a that can detect the amount of liquid inside is provided in the fuel tank 30. The fuel tank 30 is of a non-closed type, and the volatile components of the fuel stored inside are sometimes emitted to the outside. The hybrid vehicle 1 of the present embodiment is capable of using bioethanol fuel. The bioethanol fuel sometimes contains moisture. When bioethanol fuel is stored in the fuel tank 30, the moisture ratio Aw in the fuel becomes high when the volatile components thereof are emitted to the outside of the fuel tank 30. The change in the moisture ratio Aw is described in detail later.

[0026] The fuel in the fuel tank 30 is supplied to the engine 10 via a delivery pipe 31. An alcohol concentration sensor (hereinafter, simply referred to as "alcohol concentration sensor") 32 that is provided with a moisture sensor inside is provided in the delivery pipe 31. The alcohol concentration sensor 32 detects the alcohol concentration of the fuel injected in the engine 10, and detects the moisture ratio As in the injected fuel.

[0027] The hybrid vehicle 1 is provided with an ECU 100 as a control device of the vehicle. The ECU 100 is an electronic control unit provided with an arithmetic processing circuit that performs various arithmetic processing related to the travel control of the vehicle, and a memory that stores programs and data for control. The alcohol concentration sensor 32 and the A / F sensor 71 are electrically connected to the ECU 100. Other multiple sensors for controlling the entire hybrid vehicle 1 including the engine 10 and the motor 15 are connected to the ECU 100, but the description thereof is omitted here.

[0028] The ECU 100 has a portion that functions as a moisture ratio calculation section 100a that calculates the moisture ratio Aw in the fuel in the fuel tank 30. In addition, the ECU 100 has a portion that functions as a fuel injection amount control section 100b that sets the fuel injection amount Qfi at the time of starting the engine 10 based on the moisture ratio Aw.

[0029] The ECU 100 controls the driving of the engine 10 and the motor 15. Specifically, the ECU 100 controls the torque and the rotational speed of the engine 10 by controlling the throttle opening degree, the ignition timing, and the fuel injection amount of the engine 10. The ECU 100 controls the rotational speed and the torque of the motor 15 by controlling the amount of power given and received between the motor 15 and the battery 16 by controlling the converter 17. In addition, the ECU 100 performs the driving control of the K0 clutch 14, the wet clutch 18, and the transmission 19 by the control of the hydraulic control mechanism 22.

[0030] The ECU 100 causes the hybrid vehicle to travel in either of an electric traveling mode (hereinafter referred to as a BEV (Battery Electric Vehicle) mode) and a hybrid traveling mode (hereinafter referred to as an HEV (Hybrid Electric Vehicle) mode). In the BEV mode, the ECU 100 causes the K0 clutch 14 to be disengaged and travel by the power of the electric motor 15. In the HEV mode, the ECU 100 switches the K0 clutch 14 to an engaged state and travels at least by the power of the engine 10. In addition, the HEV mode includes a mode in which the vehicle travels by the power of the engine 10 alone and a mode in which the vehicle travels by the power of both the engine 10 and the electric motor 15 with the electric motor 15 performing traction operation.

[0031] The switching of the traveling mode is performed on the basis of a required driving force of the vehicle calculated from the vehicle speed and the accelerator opening degree and the SOC (State Of Charge) of the storage battery 16, and the like. For example, in a case where the required driving force is relatively small and the SOC is relatively high, the BEV mode is selected. In a case where the required driving force is relatively large or the SOC of the storage battery 16 is relatively low, the HEV mode is selected.

[0032] [Change in moisture ratio Aw in fuel in fuel tank]

[0033] Here, with reference to Figure 2 , an example of the traveling mode of the hybrid vehicle 1 and a case of a change in the amount of moisture in the fuel in the fuel tank 30 accompanying the same will be described.

[0034] In addition, a change in the A / F value accompanying the change in the amount of moisture will be described.

[0035] In the period before time tl in Figure 2 , travel by the electric motor 15 alone, that is, travel in the BEV mode is implemented. In the BEV mode, the engine 10 is not operated. Therefore, the fuel in the fuel tank 30 is not consumed. If the fuel is not consumed, the amount of moisture Qf in the fuel tank 30 also does not change. However, emission of a volatile component in the fuel sometimes occurs. If emission of the volatile component occurs, the proportion of moisture relatively increases. That is, the value of the moisture ratio Aw increases.

[0036] In the period from time tl to time t2 in Figure 2 , travel in the HEV mode in which the engine 10 is operated is implemented. If the engine 10 is operated, fuel injection is performed. The injected fuel contains moisture. Therefore, the amount of moisture Qf in the fuel tank 30 decreases. Therefore, during the period of the injected fuel, the moisture ratio Aw in the fuel tank 30 does not change.

[0037] exist Figure 2 The water content Qf and water ratio Aw show the same changes as before time t1 during the periods from time t2 to time t3 and from time t4 to time t5. The water content Qf and water ratio Aw show the same changes as before time t1 during the periods from time t3 to time t4 and from time t5 to time t6.

[0038] Here, the changes in the A / F value are explained. Figure 2 In the example shown, engine 10 operates during the periods from time t1 to time t2, from time t3 to time t4, and from time t5 to time t6, and the A / F value is detected by A / F sensor 71. Moisture in the fuel does not contribute to combustion. Therefore, when the moisture ratio Aw increases, the A / F value on the lean-burn side is displayed accordingly. (Refer to...) Figure 2 As shown by the thin solid line, the moisture ratio Aw increases over time, indicating the A / F value on the lean-burn side. Furthermore, without any countermeasures, it is conceivable that this A / F value will reach a pre-set threshold, which is the lean-burn limit. If the A / F value reaches the lean-burn limit, it may cause insufficient torque or vibration, leading to misfire.

[0039] Therefore, in this embodiment, in Figure 2 In this context, the fuel injection quantity is set using the A / F value, which is represented by a thick solid line. The setting of the fuel injection quantity Qfi corresponding to the moisture ratio Aw will be explained below.

[0040] [Fuel Injection Quantity (QFI) Settings]

[0041] Reference Figure 3 The flowchart shown in (A) explains the setting of the fuel injection quantity Qfi in relation to the change in the moisture ratio Aw of the fuel in the fuel tank 30.

[0042] First, in step S1, the moisture ratio calculation unit 100a calculates the moisture ratio Aw of the fuel in the fuel tank 30 at the time of engine startup. Here, at engine startup, for example... Figure 2 The time points t1, t3, and t5 in the time graph shown represent the starting points of HEV operation. The moisture ratio Aw can be calculated using the following Equation 1.

[0043] Formula 1 Aw(%)=As(%)×Qf0(L) / Qf1(L)

[0044] Here, As (%) is a value detected by the alcohol concentration sensor 32 at the time of the last engine stop. QfO (L) is the liquid amount in the fuel tank 30 measured by the fuel gauge 30a at the time of the last engine stop. Qfl (L) is the liquid amount in the fuel tank 30 measured by the fuel gauge 30a at the time of the present engine start. As (%) x QfO (L) indicates the water amount in the fuel tank 30. If QfO (L) and Qfl (L) are compared, the possibility that Qfl (L) indicates a smaller value is higher. This is because, sometimes, volatile components are emitted during the period from the time of the last engine stop to the time of the present engine start.

[0045] In step S2 implemented after step Sl, the injection amount control section 100b determines whether the water ratio Aw is larger than a threshold value At. The threshold value At is a value of the water ratio that becomes a boundary of whether the fuel injection amount Qfi needs to be increased, and is set in advance by simulation. When the water ratio Aw is higher, the lean limit is approached. Therefore, the threshold value At is set to a value of the water ratio that becomes the lean limit. The injection amount control section 100b, when affirmative determination ("Yes" determination) is made in step S2, proceeds to step S3. The injection amount control section 100b, when negative determination ("No" determination) is made in step S2, ends the processing. This is because, when negative determination is made, the water ratio Aw is not high to the extent that becomes the lean limit, and the fuel injection amount Qfi does not need to be corrected.

[0046] In step S3, the injection amount control section 100b sets the fuel injection amount Qfi at the time of engine start based on the water ratio Aw at the time of engine start. Here, the fuel injection amount Qfi becomes a value increased with respect to the fuel injection amount when the threshold value At is lower than the water ratio Aw. In a case where the water ratio Aw is higher, the water amount is more, and it is intended to increase the fuel injection amount to compensate for the combustible components. The fuel injection amount Qfi is set, for example, in accordance with the map illustrated in (B) of FIG. 8. The higher the water ratio Aw, that is, the more the water amount in the injected fuel, the more the fuel injection amount Qfi is increased. Figure 3

[0047] The EC 100 instructs the fuel injection system of the fuel injection amount Qfi set in step S3 at the time of engine 10 start. Thereby, as the A / F value indicated by the bold solid line in FIG. 9, it is possible to shift the combustion state to the stoichiometric side, and realize combustion below the lean limit. As a result, it is possible to avoid the generation of torque shortage, vibration, and further, the generation of misfire. Figure 2

[0048] ​​In step S4 implemented after step S3, the moisture ratio calculating section 100a updates the value of the moisture ratio As. By the engine 10 start-up, the moisture ratio can be measured by the alcohol concentration sensor 32 based on. The moisture ratio As measured and updated by the engine 10 start-up is used as the value of the moisture ratio at the last engine stop at the next engine 10 start-up. By completing the process of step S4, the series of control procedures ends, and prepares for the next engine start-up.

[0049] [Effects]

[0050] The present embodiment has the moisture ratio calculating section 100a that calculates the moisture ratio of the above fuel in the fuel tank at the engine start-up. In addition, it has the injection amount controlling section 100b that increases the fuel injection amount Qfi according to the value of the moisture ratio Aw when the value of the moisture ratio Aw is higher than the threshold value At. Thereby, even in the case where the volatile component of the fuel in the fuel tank 30 is emitted and the moisture ratio Aw becomes high, it is possible to avoid the generation of torque deficiency, vibration, and misfire in the engine 10.

[0051] The above describes the embodiment of the present application, but the present application is not limited to this particular embodiment, and various modifications and changes can be made within the scope of the spirit of the present application described in the claims.

[0052] Explanation of Reference Signs

[0053] 1...hybrid vehicle, 10...engine, 15...electric motor, 30...fuel tank, 30a...fuel gauge, 31...delivery pipe, 32...alcohol concentration sensor with built-in moisture sensor, 100...ECU, 100a...moisture ratio calculating section, 100b...injection amount controlling section.

Claims

1. A control device for a hybrid vehicle, the hybrid vehicle comprising an engine and an electric motor capable of operating using fuel containing alcohol as power sources for the vehicle, the control device for the hybrid vehicle comprising: The moisture ratio calculation unit calculates the moisture ratio of the fuel in the fuel tank during engine startup; and The injection quantity control unit increases the fuel injection quantity based on the moisture ratio value when the moisture ratio calculated by the moisture ratio calculation unit is higher than a predetermined value.

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