Vehicle control system

Abstract

This suppresses the starting of the internal combustion engine when the battery is cold. [Solution] The vehicle 500 includes an internal combustion engine 10, a planetary gear mechanism 350, a first motor generator 310, a second motor generator 320, drive wheels 360, and a battery 250 that exchanges power with both the first motor generator 310 and the second motor generator 320. The control device 100 controls the charging power of the battery 250 so as not to exceed an allowable charging power, which is changed to a smaller value as the temperature of the battery 250 decreases. The control device 100 has a processing circuit 110. When the temperature of the battery 250 is low, the processing circuit 110 performs a process to adjust the regenerative braking force so that the regenerative braking force generated by the second motor generator 320 when the accelerator is released in the vehicle 500 is small compared to when the temperature is high.

Description

Technical Field

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

Background Art

[0002] For example, a hybrid vehicle disclosed in Patent Document 1 includes an internal combustion engine, a planetary gear mechanism, a battery, and a control device. The planetary gear mechanism includes a carrier that holds a sun gear, a ring gear, and pinion gears. A first motor generator is connected to the sun gear. A crankshaft of the internal combustion engine is connected to the carrier. A second motor generator and drive wheels are connected to the ring gear. The battery exchanges electric power with both the first motor generator and the second motor generator.

[0003] In such a hybrid vehicle provided with a planetary gear mechanism, when the accelerator is off and the operation of the internal combustion engine is stopped, a regenerative braking force, which is a braking force generated by regeneration, is generated in the second motor generator.

[0004] Therefore, when the accelerator is off, the battery is charged by supplying the electric power generated by the second motor generator to the battery.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] If the charging power supplied to the battery is excessively high, it can accelerate battery degradation. Furthermore, the allowable charging power, which is the upper limit of charging power set to prevent such degradation, decreases as the battery temperature decreases. Therefore, the allowable charging power is reduced as the battery temperature decreases. The battery's charging power is then controlled to ensure it does not exceed the allowable charging power.

[0007] Here, when the battery temperature is low, the allowable charging power decreases, which may cause the battery's charging power to exceed the allowable charging power. In the case of a hybrid vehicle equipped with the planetary gear mechanism described above, if the battery's charging power is likely to exceed the allowable charging power when the accelerator is released, it is conceivable to drive the first motor generator to start the internal combustion engine. However, in the case of a hybrid vehicle, the driver often expects the operation of the internal combustion engine to be kept to a minimum. Therefore, deliberately starting the internal combustion engine, which has stopped due to the release of the accelerator, may cause discomfort to the driver. For this reason, it is desirable to suppress the starting of the internal combustion engine as much as possible when the battery temperature is low. [Means for solving the problem]

[0008] The vehicle control device that solves the above problem is applied to a vehicle comprising: a planetary gear mechanism having a sun gear, a ring gear, and a carrier; a first motor generator connected to the sun gear; an internal combustion engine with a crankshaft connected to the carrier; a second motor generator connected to the ring gear; a drive wheel connected to the ring gear; and a battery that exchanges power with both the first motor generator and the second motor generator. The control device controls the charging power of the battery so as not to exceed an allowable charging power, which is changed to a smaller value as the battery temperature decreases. The control device has a processing circuit. When the battery temperature is low, the processing circuit performs a process to adjust the regenerative braking force generated by the second motor generator when the accelerator is released in the vehicle, so that the regenerative braking force generated by the second motor generator is smaller than when the battery temperature is high. [Effects of the Invention]

[0009] The vehicle's control system can suppress the starting of the internal combustion engine when the battery temperature is low. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a vehicle in one embodiment. [Figure 2] Figure 2 is a flowchart showing the processing steps performed by the processing circuit of this embodiment. [Figure 3] Figure 3 shows the relationship between battery temperature and the magnitude of regenerative braking force in the same embodiment. [Figure 4] Figure 4 is a timing chart illustrating the operation of the embodiment. Figure 4(A) shows the change in battery temperature, Figure 4(B) shows the change in accelerator pedal input, and Figure 4(C) shows the change in regenerative mode. [Modes for carrying out the invention]

[0011] The following describes one embodiment of a vehicle control system. <Vehicle Configuration> As shown in Figure 1, the vehicle 500 is equipped with an internal combustion engine 10 and an electric motor, which are its power sources.

[0012] The crankshaft 18 of the internal combustion engine 10 is mechanically connected to the carrier C of the planetary gear mechanism 350, which constitutes the power split mechanism. The carrier C holds the rotation axes of the multiple pinion gears of the planetary gear mechanism 350.

[0013] The sun gear S of the planetary gear mechanism 350 is mechanically connected to the rotating shaft 310a of the first motor generator (hereinafter referred to as the first MG) 310. Furthermore, the ring gear R of the planetary gear mechanism 350 is mechanically connected to the rotating shaft 320a of the second motor generator (hereinafter referred to as the second MG) 320 and the drive wheel 360.

[0014] The first MG310 functions as a generator that generates electricity using engine output, and also functions as a starting starter that cranks the crankshaft 18 when starting the internal combustion engine 10.

[0015] The second MG320 functions as an electric motor that generates driving force for the drive wheels 360, and also functions as a generator that generates electricity through regeneration when the vehicle 500 is decelerating. When the second MG320 generates electricity through regeneration, it generates regenerative braking force, which is the braking force produced by that regeneration.

[0016] Both the first MG310 and the second MG320 exchange power with the battery 250 via the PCU (Power Control Unit) 200. The battery 250 is charged using the output of the internal combustion engine 10 and also supplies power to the first MG310 and the second MG320. The PCU 200 includes a converter that boosts the DC voltage input from the battery 250 and outputs it, and an inverter that converts the DC voltage boosted by the converter into AC voltage and outputs it to each MG310 and 320.

[0017] <Regarding the control device> The control device 100 controls the output and exhaust characteristics of the internal combustion engine 10 by controlling the intake air amount, fuel injection amount, and ignition timing. Further, the control device 100 operates an inverter via the PCU 200 to control the torque of the first MG3 10. Further, the control device 100 operates an inverter via the PCU 200 to control the torque of the second MG3 20. Further, by operating the inverter via the PCU 200, the magnitude of the regenerative braking force of the second MG3 20 is changed. Note that the greater the power generated by the second MG3 20, the greater the regenerative braking force and the greater the deceleration of the vehicle 500 due to the regenerative braking force.

[0018] The control device 100 includes a processing circuit 110. The processing circuit 110 includes a CPU that executes various processes according to a program and a ROM in which various programs are stored.

[0019] The control device 100 refers to the detection values of various sensors. For example, the control device 100 refers to the detection value of an air flow meter 51 that detects the intake air amount GA of the internal combustion engine 10. The control device 100 refers to the detection signal Scr of a crank angle sensor 52 that detects the rotation angle of the crankshaft 18. The control device 100 refers to the detection value of a water temperature sensor 53 that detects the cooling water temperature THW, which is the temperature of the cooling water of the internal combustion engine 10. The control device 100 refers to the detection value of an intake air temperature sensor 54 that detects the intake air temperature THA, which is the temperature of the intake air of the internal combustion engine 10. The control device 100 refers to the detection signal of an accelerator position sensor 55 that detects the accelerator operation amount ACCP, which is the operation amount of an accelerator pedal operated by the driver of the vehicle 500. The control device 100 refers to the detection signal of a speed sensor 56 that detects the vehicle speed SP of the vehicle 500. The control device 100 refers to the output signal Sm1 of a first rotation angle sensor 330 that detects the rotation angle of the first MG3 10 and the output signal Sm2 of a second rotation angle sensor 340 that detects the rotation angle of the second MG3 20. The control device 100 acquires the battery temperature Tb, which is the temperature of the battery 250, from the PCU 200.

[0020] The control device 100 calculates the engine speed NE based on the detection signal Scr of the crank angle sensor 52. Further, the control device 100 calculates the engine load ratio KL based on the engine speed NE and the intake air amount GA. The engine load ratio KL represents the ratio of the current cylinder inflow air amount to the cylinder inflow air amount when the internal combustion engine 10 is in steady operation at the current engine speed NE under the full load state. Note that the cylinder inflow air amount is the amount of air flowing into each cylinder in the intake stroke.

[0021] The control device 100 calculates the required torque necessary for the vehicle to travel based on the accelerator operation amount ACCP and the vehicle speed SP. Then, the control device 100 controls the required output Pe of the internal combustion engine 10 and the torques of the first motor generator 310 and the second motor generator 320 so as to satisfy the required torque of the vehicle. For example, when the required output Pe of the internal combustion engine 10 is "0", the control device 100 stops the operation of the internal combustion engine 10 and performs EV driving in which the vehicle travels using the output torque of the second motor generator 320. When the required output Pe of the internal combustion engine 10 is greater than "0", the control device 100 performs the operation of the internal combustion engine 10 to obtain the engine output, and performs hybrid driving in which the vehicle travels using the engine output and the output torque of the second motor generator 320.

[0022] The control device 100 adjusts the charging power, which is the power supplied from the second MG320 to the battery 250, by controlling the regenerative braking force generated by the second MG320 when the accelerator is off and the accelerator operation amount ACCP becomes "0".

[0023] The control device 100 variably sets the allowable charging power Win to be smaller as the battery temperature Tb is lower. The allowable charging power Win is the upper limit value of the charging power when charging the battery 250. Then, the control device 100 controls the charging power of the battery 250 so as not to exceed the allowable charging power Win. Hereinafter, the process for adjusting the regenerative braking force involved in such charging power will be described.

[0024] <Regarding the adjustment of regenerative braking force> When the battery temperature Tb is low, the processing circuit 110 performs a process to adjust the regenerative braking force generated by the second MG320 when the accelerator is released in the vehicle 500, so that the regenerative braking force generated by the second MG320 is smaller than when the battery temperature Tb is high.

[0025] Figure 2 shows the procedure for adjusting the regenerative braking force. This procedure is performed by the processing circuit 110 of the control device 100 at predetermined execution cycles. In the following, the step number of each procedure is represented by a number preceded by "S".

[0026] In the series of processes shown in Figure 2, the processing circuit 110 first acquires the battery temperature Tb (S100). Next, the processing circuit 110 determines whether or not there is a change in the temperature range to which the acquired battery temperature Tb belongs (S110). In this embodiment, multiple temperature ranges are set with respect to the battery temperature Tb. As an example, in this embodiment, a first temperature range, a second temperature range, and a third temperature range are set. The first temperature range is a temperature range of a default value A or higher. The third temperature range is a temperature range of a default value B or lower, which is set to a temperature lower than the default value A. The second temperature range is a temperature range where the temperature is higher than the default value B and lower than the default value A. Therefore, the second temperature range is a temperature range higher than the third temperature range. The first temperature range is a temperature range higher than the second temperature range.

[0027] In the S110 process, the processing circuit 110 determines that there has been a change in the temperature range to which the battery temperature Tb belongs if there is a difference between the temperature range to which the battery temperature Tb acquired during the previous main process execution belonged and the temperature range to which the battery temperature Tb acquired during the current main process execution belongs. On the other hand, if the temperature range to which the battery temperature Tb acquired during the previous main process execution belonged and the temperature range to which the battery temperature Tb acquired during the current main process execution belonged are the same, the processing circuit 110 determines that there has been no change in the temperature range to which the acquired battery temperature Tb belongs.

[0028] In the process of S110, if it is determined that there is a change in the temperature range to which the acquired battery temperature Tb belongs, the processing circuit 110 determines whether the temperature range to which the acquired battery temperature Tb belongs is the first temperature range (S120). If the processing circuit 110 determines that it is the first temperature range (S120: YES), it acquires the current accelerator operation amount ACCP (S130).

[0029] After executing the process in S130, the processing circuit 110 then determines whether the acquired accelerator operation amount ACCP is greater than or equal to the determination value ACCPref (S140). The magnitude of the determination value ACCPref is predetermined so that it can accurately determine that the accelerator pedal has been pressed by the driver of the vehicle 500 based on whether the accelerator operation amount ACCP is greater than or equal to the determination value ACCPref.

[0030] In the process of S140, if it is determined that the accelerator operation amount ACCP is equal to or greater than the determination value ACCPref (S140: YES), the processing circuit 110 selects the first mode as the regenerative mode for setting the regenerative braking force of the second MG320 when the accelerator is released.

[0031] As shown in Figure 3, in this embodiment, three regenerative modes are set: a first mode, a second mode, and a third mode. The first mode is the mode in which the regenerative braking force is greatest compared to the other modes. The third mode is the mode in which the regenerative braking force is least compared to the other modes. The second mode is a mode in which the regenerative braking force is less than that of the first mode and greater than that of the third mode. In other words, the second mode is a mode in which the regenerative braking force is moderate compared to the other modes.

[0032] In the process of S120 described above, if it is determined that the temperature range to which the acquired battery temperature Tb belongs is not the first temperature range (S120: NO), the processing circuit 110 executes the process of S160.

[0033] In the process of S160, the processing circuit 110 determines whether the temperature range to which the acquired battery temperature Tb belongs is the second temperature range. If the processing circuit 110 determines that it is the second temperature range (S160: YES), it acquires the current accelerator operation amount ACCP (S170).

[0034] After executing the process in S170, the processing circuit 110 then determines whether the acquired accelerator operation amount ACCP is greater than or equal to the determination value ACCPref (S180). The process in S180 is the same as the process in S140 described above.

[0035] In the process of S180, if it is determined that the accelerator operation amount ACCP is equal to or greater than the determination value ACCPref (S180: YES), the processing circuit 110 selects the second mode as the regenerative mode.

[0036] In the process described in S160, if it is determined that the temperature range to which the acquired battery temperature Tb belongs is not the second temperature range (S160: NO), the processing circuit 110 acquires the current accelerator operation amount ACCP (S200).

[0037] After executing the process in S200, the processing circuit 110 then determines whether the acquired accelerator operation amount ACCP is greater than or equal to the determination value ACCPref (S210). The process in S210 is the same as the process in S140 described above.

[0038] In the process of S210, if it is determined that the accelerator operation amount ACCP is equal to or greater than the determination value ACCPref (S210: YES), the processing circuit 110 selects the third mode as the regenerative mode.

[0039] Then, if the processing circuit 110 completes any of the processes S150, S190, and S220, or if it makes a negative determination in any of the processes S110, S140, S180, and S210, it terminates the processing for the current execution cycle.

[0040] <Operation of this embodiment> Figure 4 shows an example of the switching of regenerative modes. Figure 4(A) shows the change in battery temperature, Figure 4(B) shows the change in accelerator pedal input, and Figure 4(C) shows the change in regenerative mode. In the example shown in Figure 4, the battery temperature Tb is in the third temperature range, which is below the default value B, before time t1.

[0041] As shown in Figure 4, when the battery temperature Tb falls within the third temperature range, which is the lowest temperature range, the third mode, which generates the smallest regenerative braking force, is selected as the regenerative mode. Therefore, when the accelerator is released and the accelerator operation amount ACCP becomes "0", the second MG320 generates regenerative braking force in the third mode.

[0042] Then, as the battery temperature Tb gradually rises, if it exceeds the default value B at time t1, the battery temperature Tb will fall into the second temperature range, and the process in S160 will be judged as positive. However, if the accelerator operation amount ACCP is "0" at this point, that is, if the accelerator is off, the process in S180 will be judged as negative, and the regenerative mode will not be switched, and the third mode will be maintained.

[0043] Subsequently, at time t2, if the accelerator operation amount ACCP increases from "0" to the judgment value ACCPref or greater, the process in S180 above makes a positive judgment. Therefore, the second mode is selected as the regenerative mode, and the regenerative mode is switched. After the regenerative mode is switched to the second mode, when the accelerator is released and the accelerator operation amount ACCP becomes "0", the second MG320 generates regenerative braking force according to the second mode. Consequently, a larger regenerative braking force is generated than when the third mode is selected as the regenerative mode.

[0044] <Effects of this embodiment> (1) The control device 100 controls the charging power of the battery 250 so as not to exceed the allowable charging power Win, which is changed to a smaller value as the battery temperature Tb decreases. The control device 100 has a processing circuit 110.

[0045] When the battery temperature Tb is low, the processing circuit 110 performs a process to adjust the regenerative braking force generated by the second MG320 when the accelerator is released in the vehicle 500, so that the regenerative braking force generated by the second MG320 is smaller than when the battery temperature Tb is high.

[0046] Therefore, the lower the battery temperature Tb and the smaller the allowable charging power Win, the smaller the regenerative braking force becomes, resulting in less power generation from the second MG320. When the power generation from the second MG320 decreases, the power supplied to the battery 250 decreases. As a result, the charging power to the battery 250 can be reduced without having to drive the first MG310 to start the internal combustion engine 10. Consequently, the starting of the internal combustion engine 10 when the battery 250 is cold can be suppressed.

[0047] (2) Multiple temperature ranges are set for the battery temperature Tb. And the regenerative braking force is set for each temperature range. Therefore, compared to setting the regenerative braking force for each battery temperature Tb without setting such temperature ranges, it is possible to simplify the matching of battery temperature Tb and regenerative braking force, for example. In addition, the computational load when setting the regenerative braking force can be reduced.

[0048] (3) If a change in regenerative braking force occurs due to a temperature change of the battery 250 while regenerative braking force is being generated by releasing the accelerator, it may cause discomfort to the driver of the vehicle 500. In this embodiment, however, the change in regenerative braking force due to a temperature change of the battery 250 is performed after the driver of the vehicle 500 has pressed the accelerator pedal. In other words, the regenerative mode is selected if an affirmative determination is made in any of the processes S140, S180, or S210.

[0049] Therefore, while regenerative braking force is being generated due to the release of the accelerator, the regenerative braking force is not changed due to temperature changes in the battery 250, and the changed regenerative braking force will be obtained the next time the accelerator is released. Consequently, the feeling of discomfort described above is suppressed for the driver.

[0050] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0051] The number of temperature ranges for battery temperature Tb may be changed as appropriate. The number of regenerative modes may be changed as needed. • The regenerative braking force may be set for each battery temperature Tb without setting a temperature range for the battery temperature Tb. In this case as well, effects other than those described in (2) above can be obtained.

[0052] The processes S130, S140, S170, S180, S200, and S210 shown in Figure 2 are omitted. If the result of process S120 is positive, process S150 is executed. If the result of process S160 is positive, process S190 is executed. Alternatively, if the result of process S160 is negative, process S220 may be executed. In this case as well, effects other than those described in (3) above can be obtained.

[0053] If the vehicle 500 offers a driving mode that increases regenerative braking force compared to normal driving, the above-described adjustment of regenerative braking force may also be performed when selecting such a driving mode. Examples of driving modes that increase regenerative braking force compared to normal driving include sport mode and power mode, which enhance the vehicle 500's performance compared to normal driving. Another example is the S range mode, which sets the shift pattern of the transmission in the drivetrain to a pattern suitable for sporty driving.

[0054] The control device 100 is not limited to one that includes a CPU and memory and performs software processing. For example, the control device 100 may include a dedicated hardware circuit, such as an ASIC, that performs hardware processing for at least a portion of what is processed by software in the above embodiment. That is, the control device 100 may include a processing circuit having any of the following configurations (a) to (c): (a) A processing circuit comprising one or more processing units that perform all of the above processing according to a program, and one or more program storage devices such as ROMs that store the program. (b) A processing circuit comprising one or more processing units and one or more program storage devices that perform a portion of the above processing according to a program, and one or more dedicated hardware circuits that perform the remaining processing. (c) A processing circuit comprising one or more dedicated hardware circuits that perform all of the above processing. The program storage device, i.e., computer-readable medium, includes any available medium that can be accessed by a general-purpose or dedicated computer. [Explanation of Symbols]

[0055] 10...Internal combustion engine 18...Crankshaft 51...Air flow meter 52...Crank angle sensor 53...Water temperature sensor 54...Intake air temperature sensor 55...Accelerator position sensor 56...Speed ​​sensor 100...Control unit 110...Processing circuit 200...PCU 250...Battery 310...First motor generator 310a...Rotating shaft 320...Second motor generator 320a...Rotating shaft 330...First rotation angle sensor 340...Second rotation angle sensor 350...Planetary gear mechanism 360...Drive wheels 500...Vehicle

Claims

1. A control device applied to a vehicle comprising a planetary gear mechanism having a sun gear, a ring gear, and a carrier; a first motor generator connected to the sun gear; an internal combustion engine with a crankshaft connected to the carrier; a second motor generator connected to the ring gear; a drive wheel connected to the ring gear; and a battery that exchanges power with both the first motor generator and the second motor generator, wherein the control device controls the charging power of the battery so as not to exceed an allowable charging power which is changed to a smaller value as the battery temperature decreases, It has a processing circuit, The processing circuit, when the battery temperature is low, performs a process to adjust the regenerative braking force generated by the second motor generator when the accelerator is released in the vehicle, so that the regenerative braking force generated by the second motor generator is smaller than when the battery temperature is high. Vehicle control system.

2. Multiple temperature ranges are set for the temperature of the aforementioned battery. The regenerative braking force is set for each temperature range. A vehicle control device according to claim 1.

3. The change in regenerative braking force due to the temperature change of the battery is performed after the driver of the vehicle has pressed the accelerator pedal. A vehicle control device according to claim 1.

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