Vehicle control device

Abstract

To provide a vehicle control device capable of suppressing output of an electric motor when an internal combustion engine is started.SOLUTION: A vehicle control device which starts an internal combustion engine with an electric motor comprises: a determination section which determines whether a predetermined condition is met; an acquisition section which acquires a change rate of a rotation speed of the internal combustion engine when the same is started up with the electric motor when the predetermined condition is met; and an output setting section which sets output of the electric motor based on the change rate of the rotation speed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A technique has been developed to detect that a difference in the output torque characteristics of an internal combustion engine is due to the fuel (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-076042 Summary of the Invention [Problem to be solved by the invention]

[0004] An internal combustion engine is sometimes started by an electric motor. If the output of the electric motor is high, the amount of power consumed increases and fuel economy deteriorates. Therefore, the object of the present invention is to provide a vehicle control device that can suppress the output of the electric motor when starting the internal combustion engine. [Means for solving the problem]

[0005] The above object can be achieved by a vehicle control device that starts an internal combustion engine using an electric motor, the vehicle control device including: a determination unit that determines whether a predetermined condition is met; an acquisition unit that, when it is determined that the condition is met, acquires the rate of change of the rotation speed of the internal combustion engine when the internal combustion engine is started by the electric motor; and an output setting unit that sets the output of the electric motor based on the rate of change of the rotation speed. [Effects of the Invention]

[0006] A vehicle control device can be provided that is capable of suppressing the output of the electric motor when the internal combustion engine is started. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle according to this embodiment. [Figure 2] FIG. 2 is a flowchart illustrating the processing executed by the ECU. [Figure 3] Fig. 3(a) is a diagram illustrating an example of a time chart, and Fig. 3(b) is a diagram illustrating an example of the relationship between the rising gradient and the target value of the output. DETAILED DESCRIPTION OF THE INVENTION

[0008] FIG. 1 is a schematic diagram of a vehicle 1 according to this embodiment. The vehicle 1 is a hybrid vehicle and includes an ECU (Electronic Control Unit) 50, an engine 10 (internal combustion engine), a first motor generator (hereinafter referred to as "first MG (Motor Generator)") 14, a second motor generator (hereinafter referred to as "second MG") 15, a PCU (Power Control Unit) 17, a battery 18, a power split mechanism 20, a transmission mechanism 22, a reduction mechanism 24, and drive wheels 26. The engine 10 may be a gasoline engine or a diesel engine. The engine 10, the first MG 14, and the second MG 15 are power sources for driving the vehicle 1.

[0009] The first MG 14 and the second MG 15 function as an electric motor and a generator. When drive power is supplied to the first MG 14 and the second MG 15, they output torque, and when torque is applied to them, they generate regenerative power. The first MG 14 and the second MG 15 are, for example, AC rotating electric machines. The AC rotating electric machine is, for example, a permanent magnet synchronous motor having a rotor with a permanent magnet embedded therein.

[0010] The first MG 14 and the second MG 15 are electrically connected to the battery 18 via the PCU 17. The PCU 17 charges the battery 18 using regenerative power generated in the first MG 14 or the second MG 15, and drives the first MG 14 or the second MG 15 using the power charged in the battery 18. The PCU 17 includes a first inverter that exchanges power with the first MG 14, a second inverter that exchanges power with the second MG 15, and a converter. The converter boosts the power of the battery 18 and supplies it to the first and second inverters, and reduces the power supplied from the first and second inverters and supplies it to the battery 18. The first inverter converts DC power from the converter into AC power and supplies it to the first MG 14, and converts AC power from the first MG 14 into DC power and supplies it to the converter. The second inverter converts DC power from the converter into AC power and supplies it to second MG 15, and converts AC power from second MG 15 into DC power and supplies it to the converter.

[0011] The battery 18 is made up of a plurality of stacked cells, which may be secondary batteries such as nickel-metal hydride batteries or lithium-ion batteries.

[0012] The power split mechanism 20 mechanically couples the crankshaft of the engine 10, the rotating shaft of the first MG 14, and the output shaft of the power split mechanism 20. The power split mechanism 20 is, for example, a planetary gear mechanism including a sun gear, a planetary carrier, a pinion gear, and a ring gear. The output shaft of the power split mechanism 20 is coupled to a transmission mechanism 22. The rotating shaft of the second MG 15 is also coupled to the transmission mechanism 22. The transmission mechanism 22 is coupled to a reduction mechanism 24. The driving forces of the engine 10, the first MG 14, and the second MG 15 are transmitted to drive wheels 26 via the transmission mechanism 22 and the reduction mechanism 24.

[0013] The reduction mechanism 24 is a multi-stage automatic transmission that changes the gear ratio. Under the control of the ECU 50, the reduction mechanism 24 changes the gear ratio and switches between multiple power transmission states. The multiple power transmission states include an N (neutral) range, a D (drive) range, an R (reverse) range, and a P (parking) range. A continuously variable transmission (CVT) that continuously changes the gear ratio may be used instead of the reduction mechanism 24.

[0014] The vehicle 1 has an oil sensor 30, a liquid level sensor 32, and temperature sensors 34 and 36. The oil sensor 30 detects the amount of oil (oil level). The liquid level sensor 32 detects the height of the fuel liquid surface in the fuel tank. The temperature sensor 34 detects the temperature of the cooling water (water temperature) of the engine 10. The temperature sensor 36 detects the temperature of the oil (oil temperature).

[0015] The ECU 50 is a control device for the vehicle 1, and includes an arithmetic unit such as a CPU (Central Processing Unit), and storage devices such as a RAM (Random Access Memory) and a ROM (Read Only Memory). The ECU 50 performs various controls by executing programs stored in the ROM and storage devices. The ECU 50 acquires the oil level from the oil sensor 30, the liquid level from the liquid level sensor 32, the water temperature from the temperature sensor 34, and the oil temperature from the temperature sensor 36.

[0016] The ECU 50 controls the first MG 14, the second MG 15, the PCU 17, and the battery 18. The ECU 50 starts the engine 10, for example, by transmitting the driving force of the first MG 14 to the engine 10 and increasing the rotation speed of the engine 10. The ECU 50 functions as a determination unit that determines whether an event has occurred, an acquisition unit that acquires the rate of change (increase gradient) of the rotation speed of the engine 10, and an output setting unit that sets the output of the MG.

[0017] FIG. 2 is a flowchart illustrating processing executed by the ECU 50. The ECU 50 determines whether an event has occurred (step S10). An event may be an engine oil change or refill, fuel supply, completion of warm-up of the engine 10, or high oil temperature. When the ignition is switched from off to on, the ECU 50 checks whether the engine oil has been changed or refilled, or whether fuel has been supplied. When the oil level or fuel level when the ignition is on is higher than the level when the ignition is off by a predetermined amount or more, the ECU 50 determines that an event has occurred. When a start flag for the engine 10 is set, the ECU 50 checks the warm-up and oil temperature. If the water temperature or oil temperature is equal to or higher than a predetermined value T1, the ECU 50 determines that warm-up has been completed. If the oil temperature is equal to or higher than a predetermined value T2 (>T1), the ECU 50 determines that the oil temperature is high.

[0018] If the determination in step S10 is negative (No), step S10 is repeated. If the determination in step S10 is positive (Yes), the first MG 14 causes the engine 10 to generate torque for starting. The ECU 50 measures the rate of increase in the rotation speed of the engine 10 (step S12). Based on the rate of increase in the rotation speed, the ECU 50 sets and stores a target value for the starting output (step S14). This ends the process.

[0019] FIG. 3(a) is a diagram illustrating an example of a time chart. The upper part shows the torque (starting torque) output by the first MG 14. The lower part shows the rotation speed of the engine 10. At time t1, torque for starting the engine is generated. As the torque is input to the engine 10, the rotation speed increases. The ECU 10 measures the rate of change (increase gradient) of the rotation speed (step S12 in FIG. 2).

[0020] FIG. 3(b) is a diagram illustrating the relationship between the increase gradient and the target value of the output. The horizontal axis represents the increase gradient of the rotation speed. The vertical axis represents the target value of the MG output. The higher the increase gradient, the smaller the target value. If the increase gradient is X1, the ECU 50 sets Y1 as the target value (step S14 in FIG. 2).

[0021] According to this embodiment, the ECU 50 determines whether an event has occurred (step S10 in FIG. 2). An event may change the state of the powertrain (the power source such as the engine 10, and the power transmission mechanism 22 and other components that transmit power). When an event occurs, the ECU 50 measures the rate of increase in the rotation speed relative to the starting torque and sets an output target value based on the rate of increase (steps S12 and S14). The output of the first MG 14 becomes appropriate. After setting, the first MG 14 starts the engine 10 by outputting the target value. By suppressing the output at startup, the power consumption of the first MG 14 is reduced, and deterioration of fuel economy is suppressed.

[0022] The starting torque output by the first MG 14 when an event occurs is set to a value greater than the value required for starting the engine 10, thereby preventing failure of starting the engine 10.

[0023] The ECU 50 stores a map such as that shown in Figure 3(b). The target value of the output can be set according to the rate of increase in the engine speed. The target value may be the same for all events, or may be set to a different value for each different event.

[0024] Three thresholds T1, T2, and T3 are set for the oil temperature. Temperature T3 is higher than temperature T1 and lower than temperature T2. As the oil temperature decreases, if the oil temperature is equal to or higher than T2 or between T2 and T3, the oil temperature is determined to be high. If the oil temperature is lower than T3 or equal to or higher than T1, the warm-up is determined to be complete. As the oil temperature increases, if the oil temperature is equal to or higher than temperature T1 but lower than T2, the ECU 50 determines that the warm-up is complete. If the oil temperature is equal to or higher than temperature T2, the ECU 50 determines that the oil is high temperature. If the number of times an event is determined to have occurred is large, the engine 10 will be started with a larger output, which will increase power consumption. Because T2 is higher than T1 and T3, a high temperature event is determined when the oil temperature has risen sufficiently. The number of times an event is determined to have occurred decreases.

[0025] When an event occurs, the ECU 50 assumes that the condition is met and measures the start-up and the rate of increase in engine speed. The condition is an event that may change the state of the powertrain. Fuel efficiency can be improved by optimizing the output after the event. The event may be at least one of oil change and refill, refueling, warm-up completion, and high oil temperature, or may include other events. The number of MGs provided in the vehicle may be two or one.

[0026] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0027] 1 vehicle 10 Engine 14 First motor generator 15 Second motor generator 17 PCU 18 Battery 20 Power split mechanism 22 Transmission Mechanism 24 Reduction mechanism 26 Drive wheels 30 Oil sensor 32 Liquid level sensor 34, 36 Temperature sensor 50 ECU

Claims

[Claim 1] A control device for a vehicle that starts an internal combustion engine using an electric motor, a determination unit that determines whether a predetermined condition is met; an acquisition unit that acquires a rate of change of a rotation speed of the internal combustion engine when the internal combustion engine is started by the electric motor when it is determined that the condition is satisfied; an output setting unit that sets an output of the electric motor based on the rate of change of the rotation speed, the predetermined condition is any one of the following: engine oil of the internal combustion engine has been changed or replenished, fuel has been supplied, warm-up of the internal combustion engine has been completed, or the oil temperature of the engine oil is a high temperature equal to or higher than a threshold temperature; The output setting unit sets the output of the electric motor to a smaller value as the rate of change of the rotation speed increases.

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