Hybrid vehicle control device

Abstract

To provide a technique that prevents both lithium precipitation in a battery and discomfort for a driver.SOLUTION: A hybrid vehicle control device calculates reference electric power, among a total power generation amount by deceleration, for blowing an engine when a vehicle is in a brake range and required power is 0 or less, calculates electric power for preventing lithium precipitation in a battery, charges the battery with charging power while controlling an engine speed using a motor so that blowing power not less than the reference electric power among the total power generation amount is consumed when the reference electric power is less than the electric power for preventing the lithium precipitation, controls the engine speed using the motor so as to consume the blowing power when the reference electric power exceeds the electric power for preventing the lithium precipitation, charges the battery with the electric power obtained by subtracting surplus electric power exceeding the electric power for preventing the lithium precipitation from the charging power, converts the surplus electric power into deceleration torque, and causes a hydraulic brake to generate the converted deceleration toque.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a control device for a hybrid vehicle. [Background technology]

[0002] Patent Document 1 discloses a hybrid vehicle. This vehicle applies braking force to the vehicle while charging the battery within the battery's input limit by using regenerative drive and motoring the engine with fuel injection stopped using a motor when the shift range is in the brake range and the accelerator is released. When the battery temperature is below a threshold, the required charge / discharge power is increased (a smaller value on the charging side) compared to when the battery temperature is above the threshold, and the target charge / discharge power, target motoring power, and target engine rotation speed are increased. This prevents the hybrid vehicle from causing discomfort to the driver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-047820 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hybrid vehicle described in Patent Document 1, if the battery input limit changes under conditions different from those related to the battery temperature, the engine speed may not behave as intended by the driver, which may cause the driver to feel uncomfortable. This disclosure provides a technology that achieves both prevention of lithium deposition in the battery and suppression of discomfort felt by the driver. [Means for solving the problem]

[0005] A control device for a hybrid vehicle according to one aspect of the present disclosure is a control device for a hybrid vehicle that controls a hybrid vehicle that can run using driving force from one or both of an engine and a motor and that can convert the vehicle's kinetic energy into electrical energy to charge a lithium-ion battery, and includes: a shift range sensor that detects a drive range and a brake range that applies a stronger deceleration force than the drive range; an accelerator pedal sensor that detects an operation amount of an accelerator pedal; and a control unit connected to the shift range sensor and the accelerator pedal sensor, and when the range detected by the shift range sensor is the brake range and the required power according to the operation amount detected by the accelerator pedal sensor is 0 or less, the control unit controls the engine to generate a power of 0% of the total power generated by deceleration. a reference power that specifies the power to be consumed by increasing the speed of the engine; calculates the power for preventing lithium deposition in the lithium ion battery; if the reference power is lower than the power for preventing lithium deposition, the engine speed is controlled by the motor so that the blow-up power equal to or greater than the reference power is consumed from the total amount of generated power; the lithium ion battery is charged with charging power excluding the blow-up power from the total amount of generated power; if the reference power exceeds the power for preventing lithium deposition, the engine speed is controlled by the motor so that the blow-up power equal to or greater than the reference power is consumed from the total amount of generated power; the lithium ion battery is charged with power excluding the power in excess of the power for preventing lithium deposition; converts the excess power into deceleration torque; and generates the converted deceleration torque by the hydraulic brake. [Effects of the Invention]

[0006] According to the present disclosure, a technology is provided that achieves both prevention of lithium deposition in a battery and suppression of discomfort felt by the driver. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a hybrid vehicle equipped with a control device according to an embodiment. [Figure 2]FIG. 2 is a flowchart showing the operation of the control device. [Figure 3] FIG. 3 is a time chart illustrating the operation of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] [Vehicle configuration] Fig. 1 is a block diagram showing an example of the configuration of a hybrid vehicle equipped with a control device according to an embodiment. As shown in Fig. 1, the control device 1 is mounted on a hybrid vehicle 2, for example. The hybrid vehicle 2 may be a vehicle driven by a driver, or may be an autonomous vehicle.

[0010] The hybrid vehicle 2 includes an accelerator pedal sensor 11, a shift range sensor 12, a control unit 13, an engine 14, a motor 15, a battery 16 (an example of a lithium ion battery), and a hydraulic brake system 17. The control device 1 includes the accelerator pedal sensor 11, the shift range sensor 12, and the control unit 13.

[0011] The accelerator pedal sensor 11 is a detector that detects the amount of accelerator pedal operation (accelerator opening) by the driver, and outputs the detected amount of operation to the control unit 13.

[0012] The shift range sensor 12 is a detector that detects the shift range of the hybrid vehicle 2. The shift range sensor 12 detects a drive range (D range) for forward travel and a brake range (B range or S range) that applies a stronger deceleration force than the drive range. The shift range sensor 12 may also detect other ranges such as a parking range (P range) used when parking, a reverse range (R range) for reverse travel, and a neutral range (N range).

[0013] The control unit 13 is a device that controls the hybrid vehicle 2, and is configured, for example, by an ECU (Electronic Control Unit). The ECU is an electronic control unit that has a processor such as a CPU (Central Processing Unit), storage devices such as a ROM (Read Only Memory) and a RAM (Random-Access Memory), storage devices such as a CAN (Controller Area Network) communication circuit, and input / output circuits. The control unit 13 is connected to the accelerator pedal sensor 11 and the shift range sensor 12, and controls the hybrid vehicle 2. The control unit 13 may be configured by multiple ECUs.

[0014] Engine 14 is an internal combustion engine that outputs power using gasoline, diesel, or the like as fuel. Control unit 13 acquires the crank angle of the crankshaft of engine 14, the throttle opening of the throttle valve, and the like, and controls engine 14 by transmitting control signals to a throttle motor that adjusts the position of the throttle valve, control signals to fuel injection valves, control signals to an ignition coil, and the like. Control unit 13 calculates the rotation speed of the crankshaft, i.e., the rotation speed Ne of engine 14, based on the crank angle.

[0015] The motor 15 is, for example, a synchronous generator motor. Two motors 15 are provided, one as a motor and one as a generator, and are connected to the drive shaft of the hybrid vehicle 2 via a power split mechanism. The control unit 13 acquires the rotational position of the rotor of the motor 15, the phase current flowing through each phase of the motor 15, etc. The control unit 13 calculates the rotation speed of the motor 15 based on the rotational position.

[0016] The battery 16 is configured as a lithium-ion secondary battery. The battery 16 is connected to the motor 15 via an inverter. The battery 16 is managed by the control unit 13. The control unit 13 acquires a battery voltage Vb from a voltage sensor installed between the terminals of the battery 16, a battery current Ib (a positive value when discharging from the battery 16) from a current sensor attached to the output terminal of the battery 16, and the like. The control unit 13 calculates a power storage ratio SOC based on an integrated value of the battery current Ib from the current sensor. The power storage ratio SOC is the ratio of the amount of power that can be discharged from the battery 16 to the total capacity of the battery 16. The control unit 13 calculates a power limit Win that serves as an input limit for the battery 16 and a power limit Wout that serves as an output limit for the battery 16. The power limit Win is an allowable charging power that may be charged to the battery 16, and the power limit Wout is an allowable discharging power that may be discharged from the battery 16.

[0017] The hydraulic brake system 17 is a system that brakes the hybrid vehicle 2, and includes hydraulic brakes that are hydraulically driven. The hydraulic brake system 17 is operated by the control unit 13.

[0018] The control unit 13 controls the engine 14 and the motor 15, and drives the hybrid vehicle 2 using the driving force of one or both of the engine 14 and the motor 15. The control unit 13 converts the kinetic energy of the hybrid vehicle 2 into electrical energy and charges the battery 16.

[0019] As a specific example, the control unit 13 sets a required torque required for traveling (required from the drive shaft) based on the shift range, accelerator opening, and vehicle speed. Then, while operating or stopping the engine 14, the control unit 13 controls the engine 14 and the motor 15 so that the charge / discharge power Pb (=Vb·Ib) of the battery 16 falls within the range of the power limits Win and Wout, which are input / output limits, and so that torque based on the required torque is output to the drive shaft.

[0020] When the hybrid vehicle 2 decelerates, the battery 16 continues to be charged, which may cause lithium deposition in the battery 16 and result in deterioration of the battery 16. To prevent lithium deposition, the control unit 13 performs Iwin control (control to narrow the power limit Win) to reduce the amount of charge to the battery 16. To ensure the deceleration rate, the control unit 13 increases (revs up) the rotation speed Ne of the engine 14 by the motor 15 simultaneously with the Iwin control, thereby consuming the excess power generated by the Iwin control. While lithium deposition can be suppressed in this way, executing the Iwin control may worsen noise and vibration characteristics because the rotation speed Ne of the engine 14 increases.

[0021] One way to prevent the deterioration of noise and vibration characteristics is to reduce the number of times the I win control is intervened. To achieve this, in situations where the charge amount is large, such as when the shift range is in the B or S range during forward driving, Winp control can be performed to intentionally narrow the power limit Win in advance, and the motor 15 can increase the engine speed Ne of the engine 14 in response to driver operation, thereby reducing the sense of discomfort. However, if charging continues even if the charge amount is reduced by Winp control, all that can be done is to extend the time until the I win control is intervened. Therefore, the control unit 13 compares the degree of intervention between the Winp control and the I win control, and if a difference is found, the hydraulic brake system 17 ensures deceleration and controls each component to reduce the charge amount.

[0022] Fig. 2 is a flowchart showing the operation of the control device. The flowchart shown in Fig. 2 starts, for example, when the ignition of the hybrid vehicle 2 is turned on. The flowchart shown in Fig. 2 will be explained with appropriate reference to Fig. 3. Fig. 3 is a time chart explaining the operation of the control device.

[0023] 2, in Step S10, the control unit 13 of the control device 1 determines whether the current range detected by the shift range sensor 12 is the B range or the S range. If the current range is the B range or the S range (Step S10: YES), the control unit 13 determines whether the user requested power is 0 or less in Step S12. The control unit 13 calculates the user requested power based on the operation amount detected by the accelerator pedal sensor 11. For example, when the accelerator pedal is released, the user requested power is 0 or less.

[0024] If it is determined that the user requested power is equal to or less than 0 (step S12: YES), the control unit 13 calculates, in step S 14, a reference power Win for engine revving. The reference power Win defines the power consumed by revving up the engine 14 out of the total amount of power generated by deceleration.

[0025] As shown in (A) and (B) of Figure 3, when the current range is B range or S range (time t1) and the accelerator is released (time t2), deceleration begins as shown in (C) of Figure 3. The user power (total generated power) shown in (D) of Figure 3 is not fully charged, but power within a range smaller than the reference power Win for engine rev-up is charged, and the Ne rev-up power that exceeds the reference power Win for engine rev-up is consumed by controlling the rotation speed Ne of the engine 14 with the motor 15. (F) of Figure 3 shows the rotation speed Ne of the engine 14, which is controlled according to the Ne rev-up power.

[0026] If it is determined that the user requested power is equal to or less than 0 (step S12: YES), the control unit 13 further calculates, in step S16, the power Win for preventing lithium deposition of the battery 16. The power Win for preventing lithium deposition is a limited power, and is set so that charging of power exceeding the power Win for preventing lithium deposition is not performed. As shown in FIG. 3(E), as an example, the power Win for preventing lithium deposition monotonically decreases from the timing (time t2) when the accelerator is released.

[0027] Subsequently, in step S18, control unit 13 subtracts power W for preventing lithium deposition from reference power W for engine racing, and determines whether the resulting difference is within a predetermined value. Control unit 13 determines whether reference power W calculated in step S14 is lower than power W for preventing lithium deposition calculated in step S16.

[0028] If it is determined that the reference power Win is lower than the lithium deposition prevention power Win (step S18: YES), the control unit 13 performs normal control. Specifically, the control unit 13 controls the rotation speed Ne of the engine 14 by the motor 15 so as to consume the blow-up power equal to or greater than the reference power Win out of the total power generation amount, and charges the battery 16 with the charging power excluding the blow-up power from the total power generation amount. This normal control is executed from time t2 to time t3.

[0029] If it is determined that the reference power W is lower than the lithium deposition prevention power W (step S18: NO), that is, if the reference power W exceeds the lithium deposition prevention power W (after time t3), it is necessary to consume power somewhere that is equal to or greater than the lithium deposition prevention power W and equal to or less than the reference power W. For example, it is possible to balance the charge and discharge balance by consuming this power as revving power, but the behavior of the engine speed as shown by the dashed line in (F) of Figure 3 results in revving up unintended by the driver.

[0030] Therefore, in step S20, control unit 13 converts the excess power into deceleration and, in step S22, requests hydraulic braking. As shown in FIG. 3(G), from time t3 onward, hydraulic brake system 17 is instructed to provide a brake hydraulic pressure that achieves deceleration equivalent to the charging power exceeding the lithium deposition prevention power Win. Because the hydraulic brake ensures deceleration, the engine speed continues to follow the solid line after time t3, preventing the driver from accidentally racing. In this way, control unit 13 controls engine speed Ne by motor 15 so as to consume the racing power equal to or greater than reference power Win of the total power generation. The controller 13 charges battery 16 with the charging power excluding the power exceeding the lithium deposition prevention power Win, converts the excess power into deceleration torque, and generates the converted deceleration torque using the hydraulic brake.

[0031] If the current range is not the B range or the S range (step S10: NO), if it is determined that the user requested power is not equal to or less than 0 (step S12: NO), if the normal control from step S18 onwards has ended, or if the control using the hydraulic brake from step S22 onwards has ended, the flowchart shown in Fig. 2 ends. The flowchart shown in Fig. 2 is repeatedly executed from the beginning until an ending condition is met.

[0032] [Summary of the embodiment] According to the control unit 13 of the control device 1, by using a hydraulic brake, which is an actuator other than the battery 16, the engine 14, and the motor 15, the charging power that would otherwise be consumed by revving up the engine 14 can be replaced by the hydraulic brake, so the rotation speed Ne of the engine 14 can be reduced, and an increase in engine rotation speed unintended by the driver can be suppressed, thereby suppressing discomfort felt by the driver. Furthermore, because the control device 1 can reduce the rotation speed Ne of the engine 14, it can prevent deterioration of noise and vibration characteristics and achieve driving that maintains a balance between fuel economy, noise and vibration characteristics, and drivability. As described above, the control device 1 can both prevent lithium deposition in the battery 16 and suppress discomfort felt by the driver.

[0033] Although exemplary embodiments have been described above, various omissions, substitutions, and modifications may be made without being limited to the above-described exemplary embodiments. [Explanation of symbols]

[0034] 1...control device, 2...hybrid vehicle, 11...accelerator pedal sensor, 12...shift range sensor, 13...control unit, 14...engine, 15...motor, 16...battery, 17...hydraulic brake system

Claims

[Claim 1] A control device for a hybrid vehicle that controls a hybrid vehicle that can run using the driving force of one or both of an engine and a motor and can convert the kinetic energy of the vehicle into electrical energy to charge a lithium ion battery, a shift range sensor that detects a drive range and a brake range that applies a stronger deceleration force than the drive range; an accelerator pedal sensor that detects an amount of accelerator pedal operation; a control unit connected to the shift range sensor and the accelerator pedal sensor; Equipped with The control unit When the range detected by the shift range sensor is the brake range and the required power according to the operation amount detected by the accelerator pedal sensor is 0 or less, calculating a reference power that defines the power consumed by revving up the engine out of the total amount of power generated by deceleration; Calculating the power for preventing lithium deposition in the lithium ion battery; When the reference power is lower than the power for preventing lithium deposition, the rotation speed of the engine is controlled by the motor so that a blow-up power equal to or greater than the reference power is consumed from the total amount of power generation, and the charging power excluding the blow-up power from the total amount of power generation is charged to the lithium ion battery; When the reference power exceeds the power for preventing lithium deposition, the rotation speed of the engine is controlled by the motor so that a blow-up power equal to or greater than the reference power is consumed from the total amount of power generation, the power excluding the power exceeding the power for preventing lithium deposition is charged to the lithium ion battery from the charging power, the excess power is converted into deceleration torque, and the converted deceleration torque is generated by a hydraulic brake. A control device for a hybrid vehicle.

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