JP7704086B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

Conventionally, a control device for this type of vehicle has been proposed that uses the lowest rotation speed of each wheel detected by a wheel speed sensor as a reference rotation speed, and judges slippage of each wheel by comparing the reference rotation speed with the rotation speed of the motor corresponding to each wheel (see, for example, Patent Document 1). Based on the results of the slip judgment, this vehicle control device calculates the required torque of the motor driving the slipping wheel so that the rotation speed of the slipping wheel matches the target rotation speed, and reallocates the resulting torque reduction amount of the slipping wheel to the non-slip wheels. This process is said to suppress the occurrence of slippage of each wheel and improve drivability by suppressing vibrations in the motor and tires.

JP 2016-073107 A

When slip and grip caused by the spinning of the drive wheels occurs repeatedly, the vibration caused by the repetition grows and causes the powertrain to vibrate. This powertrain vibration can cause the mount to collide with the stopper, generating a striking noise. This striking noise causes discomfort and strangeness to the driver and passengers.

The main purpose of the vehicle control device of the present invention is to suppress repeated slipping and gripping caused by the spinning of the drive wheels.

The vehicle control device of the present invention employs the following means to achieve the above-mentioned main objective.

The vehicle control device of the present invention comprises:
A control device for a vehicle,
the control device limits the torque of the drive wheels when an integrated value of the wheel speed difference between the front and rear wheels within a predetermined time period during running under a predetermined slip condition is equal to or greater than a threshold value.
It is characterized by:

In the vehicle control device of the present invention, when the integrated value of the wheel speed difference between the front and rear wheels within a specified time period during driving with a specified slip is equal to or greater than a threshold value, the torque of the drive wheels is limited to suppress slippage caused by the drive wheels spinning. This makes it possible to suppress driving that alternates between slippage and gripping caused by the drive wheels spinning.

Here, the "wheel speed difference between the front and rear wheels" may be the smaller of the left wheel speed difference between the front left wheel and the rear left wheel, and the right wheel speed difference between the front right wheel and the rear right wheel. Also, the "time of driving with a specified slip" may be when all of the following conditions are met: the shift is in second gear or lower, the vehicle is not turning, and traction control is not operating. The "specified time" may be 300 msec, 500 msec, 700 msec, etc.

1 is a diagram showing an outline of the configuration of a vehicle 20 according to an embodiment of the present invention. 4 is a flowchart showing an example of a slippage travel control process executed by an HVECU 70.

Next, we will explain how to implement the present invention using examples.

Figure 1 is a schematic diagram showing the configuration of a vehicle 20 according to one embodiment of the present invention. As shown in the figure, the vehicle 20 according to the embodiment includes an engine 22, a motor 30, an inverter 32, a clutch K0, an automatic transmission 40, a high-voltage battery 60, a low-voltage battery 62, a DC/DC converter 64, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel from a fuel tank. The crankshaft 23 of the engine 22 is connected to the rotating shaft 31 (rotor) of the motor 30 via a clutch K0. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as the "engine ECU") 24.

The engine ECU 24 includes a microcomputer having a CPU, ROM, RAM, flash memory, input/output ports, and communication ports (not shown). Signals from various sensors necessary for controlling the operation of the engine 22 are input to the engine ECU 24 via the input port. Examples of signals input to the engine ECU 24 include the crank angle θcr from the crank position sensor 23a that detects the rotational position of the crankshaft 23 of the engine 22, and the cooling water temperature Tw from a water temperature sensor (not shown) that detects the temperature of the cooling water of the engine 22. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via the output port. The engine ECU 24 is connected to the HVECU 70 via the communication port. The engine ECU 24 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr of the crankshaft 23 from the crank position sensor 23a.

A starter motor 25 for cranking the engine 22 and an alternator 26 for generating electricity using power from the engine 22 are connected to the crankshaft 23 of the engine 22. The starter 25 and the alternator 26 are connected to a low-voltage power line 63 together with a low-voltage battery 62, and are controlled by the HVECU 70.

The motor 30 is configured as a synchronous generator motor, and has a rotor with a permanent magnet embedded in the rotor core, and a stator with a three-phase coil wound around the stator core. The rotating shaft 31 to which the rotor of the motor 30 is fixed is connected to the crankshaft 23 of the engine 22 via the clutch K0, and is also connected to the input shaft 41 of the automatic transmission 45. The inverter 32 is used to drive the motor 30, and is connected to the high-voltage power line 61. The motor 30 is driven to rotate by the motor electronic control unit (hereinafter referred to as the "motor ECU") 34 controlling the switching of multiple switching elements of the inverter 32.

Although not shown, the motor ECU 34 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input/output ports, and communication ports. Signals from various sensors are input to the motor ECU 34 via the input port. Examples of signals input to the motor ECU 34 include the rotational position θm from the rotational position sensor 30a that detects the rotational position of the rotor (rotating shaft 31) of the motor 30, and the phase currents Iu and Iv from the current sensors that detect the phase currents of each phase of the motor 30. The motor ECU 34 outputs control signals to the inverter 32 and the like via the output port. The motor ECU 34 is connected to the HVECU 70 via a communication port. The motor ECU 34 calculates the rotation speed Nm of the motor 30 based on the rotational position θm of the rotor (rotating shaft 31) of the motor 30 from the rotational position sensor 30a.

The clutch K0 is configured, for example, as a hydraulically driven friction clutch and is controlled by the HVECU 70 to connect and disconnect the crankshaft 23 of the engine 22 and the rotating shaft 31 of the motor 30.

The automatic transmission 40 has a torque converter 43 and a six-speed automatic transmission 45. The torque converter 43 is configured as a general fluid transmission device, and transmits the power of the input shaft 41 connected to the rotating shaft 31 of the motor 30 to the transmission input shaft 44, which is the input shaft of the automatic transmission 45, with the torque amplified, or transmits the torque as is without amplifying it. The automatic transmission 45 has the transmission input shaft 44, an output shaft 42 connected to the rear wheels 54L and 54R as driving wheels via a differential gear 53, multiple planetary gears, and multiple hydraulically driven friction engagement elements (clutches, brakes). The automatic transmission 45 forms forward gears from 1st to 6th gears and reverse gears by engaging and disengaging the multiple friction engagement elements, and transmits power between the transmission input shaft 44 and the output shaft 42. The hydraulic pressure of the hydraulic oil from a mechanical oil pump or an electric oil pump is adjusted and supplied to the clutch K0 and the automatic transmission 45 by a hydraulic control device (not shown). The hydraulic control device has a valve body with multiple oil passages, multiple regulator valves, multiple linear solenoid valves, etc. This hydraulic control device is controlled by the HVECU 70.

The high-voltage battery 60 is configured as, for example, a lithium-ion secondary battery or a nickel-hydrogen secondary battery with a rated voltage of several hundred volts, and is connected to the high-voltage power line 61 together with the inverter 32. The low-voltage battery 62 is configured as, for example, a lead-acid battery with a rated voltage of about 12 or 14 volts, and is connected to the low-voltage power line 63 together with the starter motor 25 and the alternator 26. The DC/DC converter 64 is connected to the high-voltage power line 61 and the low-voltage power line 63. This DC/DC converter 64 supplies power from the high-voltage power line 61 to the low-voltage power line 63 with a voltage step-down.

Although not shown, the HVECU 70 is equipped with a microcomputer having a CPU, ROM, RAM, flash memory, input/output ports, and communication ports. Signals from various sensors are input to the HVECU 70 via the input ports. Examples of signals input to the HVECU 70 include the rotation speed Nin from the rotation speed sensor 41a attached to the input shaft 41 of the automatic transmission 40, the rotation speed Nmi from the rotation speed sensor 44a attached to the transmission input shaft 44 of the automatic transmission 40, and the rotation speed Nout from the rotation speed sensor 42a attached to the output shaft 42 of the automatic transmission 40. The voltage Vbh of the high-voltage battery 60 from a voltage sensor attached between the terminals of the high-voltage battery 60, the current Ibh of the high-voltage battery 60 from a current sensor attached to the output terminal of the high-voltage battery 60, and the voltage Vbl from a voltage sensor attached between the terminals of the low-voltage battery 62 can also be mentioned. Examples of the inputs include an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82 that detects the operating position of a shift lever 81, an accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, and a brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85. Other examples include a vehicle speed V from a vehicle speed sensor 87, and wheel speeds Vfl, Vfr, Vrl, and Vrr from wheel speed sensors 88L, 88R, 89L, and 89R attached to the front wheels 52L and 52R and the rear wheels 54L and 54R.

Various control signals are output from the HVECU 70 via output ports. Examples of signals output from the HVECU 70 include a control signal to the starter motor 25 and a control signal to the alternator 26. Other examples include control signals to the clutch K0 and the automatic transmission 40 (hydraulic control device), and a control signal to the DC/DC converter 64. The HVECU 70 is connected to the engine ECU 24 and the motor ECU 34 via communication ports. The HVECU 70 calculates the rotation speed ratio Gt of the automatic transmission 40 by dividing the rotation speed Nin of the input shaft 41 of the automatic transmission 40 from the rotation speed sensor 41a by the rotation speed Nout of the output shaft 42 of the automatic transmission 40 from the rotation speed sensor 42a.

In the vehicle 20 of the embodiment thus configured, the engine 22, clutch K0, motor 30, and automatic transmission 40 are controlled by cooperative control between the HVECU 70, engine ECU 24, and motor ECU 34 so that the vehicle runs in a hybrid driving mode (HV driving mode) or an electric driving mode (EV driving mode). Here, the HV driving mode is a mode in which the clutch K0 is engaged and the vehicle runs using the power of the engine 22, and the EV driving mode is a mode in which the clutch K0 is released and the vehicle runs without using the power of the engine 22.

When controlling the automatic transmission 40 in the HV driving mode or the EV driving mode, the HVECU 70 first sets the target gear M* of the automatic transmission 45 based on the accelerator opening Acc and the vehicle speed V. Then, when the gear M of the automatic transmission 45 matches the target gear M*, the HVECU 70 controls the automatic transmission 45 so that the gear M is maintained. On the other hand, when the gear M and the target gear M* differ, the HVECU 70 controls the automatic transmission 45 so that the gear M matches the target gear M*.

In controlling the engine 22 and the motor 30 in the HV driving mode, the HVECU 70 first sets the required torque Tout* required for driving (required of the output shaft 42 of the automatic transmission 40) based on the accelerator opening Acc and the vehicle speed V. Next, the required torque Tout* of the output shaft 42 is divided by the rotation speed ratio Gt of the automatic transmission 40 and set as a provisional required torque Tintmp as a provisional value of the required torque Tin* of the input shaft 41. Then, the provisional required torque Tintmp of the input shaft 41 is subjected to a slow change process such as a rate process or an averaging process and set as the required torque Tin* of the input shaft 41. Once the required torque Tin* of the input shaft 41 is set in this manner, the target torque Te* of the engine 22 and the torque command Tm* of the motor 30 are set so that the required torque Tin* is output to the input shaft 41, and the target torque Te* of the engine 22 is sent to the engine ECU 24, and the torque command Tm* of the motor 30 is sent to the motor ECU 34. Upon receiving the target torque Te*, the engine ECU 24 performs operation control of the engine 22 (intake air amount control, fuel injection control, ignition control, etc.) so that the engine 22 is operated at the target torque Te*. Upon receiving the torque command Tm*, the motor ECU 34 performs switching control of multiple switching elements of the inverter 32 so that the motor 30 is driven at the torque command Tm*.

In controlling the motor 30 in the EV driving mode, the HVECU 70 sets the required torque Tin* of the input shaft 41 in the same manner as in the HV driving mode, sets the torque command Tm* of the motor 30 so that the required torque Tin* is output to the input shaft 41, and transmits the set torque command Tm* to the motor ECU 34. The motor ECU 34 controls the switching of multiple switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

Next, the operation of the vehicle 20 of the embodiment thus configured, particularly the operation during slipping, will be described. Here, "slipping" refers to a state in which the drive wheels alternate between slight slipping and gripping due to freewheeling. FIG. 2 is a flowchart showing an example of slipping control processing executed by the HVECU 70. This processing is executed repeatedly at predetermined time intervals.

When slip-on driving control processing is executed, the HVECU 70 first determines whether the conditions for executing slip-on driving control are met (step S100). The conditions for executing slip-on driving control are driving conditions that are likely to cause repeated slight slippage and grip due to spinning of the drive wheels, such as when the shift is in second gear or lower, when the vehicle is not turning, and when traction control is not activated. The conditions for executing slip-on driving control are determined to be met when all of the above conditions are met. If it is determined that the conditions for executing slip-on driving control are not met, it is determined that slip-on driving control is unnecessary and the processing ends.

When it is determined in step S100 that the conditions for executing the slip-time driving control are met, the front and rear wheel speed differences ΔVL, ΔVR are calculated (step S110). The front and rear wheel speed difference ΔVL is calculated as the difference (Vrl-Vfl) between the wheel speed Vrl from the wheel speed sensor 89L attached to the rear left wheel 54L and the wheel speed Vfl from the wheel speed sensor 88L attached to the front left wheel 52L. The front and rear wheel speed difference ΔVR is calculated as the difference (Vrr-Vfr) between the wheel speed Vrr from the wheel speed sensor 89R attached to the rear right wheel 54R and the wheel speed Vfr from the wheel speed sensor 88R attached to the front right wheel 52R. Then, the smaller of the front and rear wheel speed differences ΔVL, ΔVR is obtained as the front and rear wheel speed difference ΔV (step S120), and the integrated value ΣΔV of the front and rear wheel speed difference ΔV from a predetermined time ago is calculated (step S130). Here, the predetermined time can be 300 msec, 500 msec, 700 msec, etc.

Next, it is determined whether the integrated value ΣΔV of the front and rear wheel speed difference ΔV from a predetermined time ago is equal to or greater than a threshold value Vref1 (step S140). The threshold value Vref1 is a threshold value for determining whether slipping is occurring, and can be obtained by experiments, machine learning, or the like. When it is determined that the integrated value ΣΔV is equal to or greater than the threshold value Vref1, it is determined that slipping is occurring, and a torque limit is imposed on the drive wheels (rear wheels 54L, 54R in this embodiment) (step S150). As the torque limit of the drive wheels, for example, an upper limit guard (60% or 70% of the maximum output torque, etc.) is imposed on the required torque Tout* required for the output shaft 42 of the automatic transmission 40, which is set based on the accelerator opening Acc and the vehicle speed V, or the required torque Tout* multiplied by a coefficient k (for example, 0.6, 0.7, 0.8, etc.) smaller than the value 1 can be used as the required torque Tout*. By imposing such torque restrictions on the drive wheels, it is possible to suppress slippage caused by the drive wheels (in this embodiment, rear wheels 54L and 54R) spinning, and to suppress driving that alternates between slipping and gripping due to the drive wheels spinning.

Next, it is determined whether the integrated value ΣΔV of the front and rear wheel speed difference ΔV from a predetermined time ago is equal to or greater than a threshold value Vref2 (step S160). The threshold value Vref2 is a value slightly smaller than the threshold value Vref1. When it is determined that the integrated value ΣΔV is less than the threshold value Vref2, the torque limit of the drive wheels (rear wheels 54L, 54R in this embodiment) is released (step S170).

The processing of steps S140 to S170 involves imposing and releasing torque restrictions on the drive wheels, and thresholds Vref1 and Vref2 are used to provide hysteresis. That is, when the integrated value ΣΔV of the front/rear wheel speed difference ΔV from a predetermined time ago reaches or exceeds threshold Vref1, the torque restriction on the drive wheels is imposed, and then when the integrated value ΣΔV of the front/rear wheel speed difference ΔV from a predetermined time ago falls below threshold Vref2, the torque restriction on the drive wheels is released. Therefore, even if the integrated value ΣΔV of the front/rear wheel speed difference ΔV from a predetermined time ago falls below threshold Vref1 while the torque restriction is imposed, the torque restriction on the drive wheels continues as long as the integrated value ΣΔV is equal to or greater than threshold Vref2.

In the vehicle 20 of the embodiment described above, when the conditions for executing the slippage driving control are met, the front and rear wheel speed difference ΔV is calculated, and when the integrated value ΣΔV of the front and rear wheel speed difference ΔV from a predetermined time ago reaches or exceeds the threshold value Vref1, a torque limit is imposed on the drive wheels (rear wheels 54L, 54R in this embodiment). This makes it possible to suppress slippage due to the drive wheels spinning, and to suppress driving that alternates between slippage and gripping due to the drive wheels spinning. Moreover, because the smaller of the front and rear wheel speed differences ΔVL, ΔVR is obtained as the front and rear wheel speed difference ΔV, it is possible to more accurately determine whether or not slippage is occurring.

In the embodiment, the vehicle 20 is equipped with a six-speed automatic transmission 45. However, it may be equipped with a four-speed, five-speed, eight-speed, or other automatic transmission.

In the embodiment, the vehicle 20 is equipped with an engine ECU 24, a motor ECU 34, and an HVECU 70. However, at least two of these may be integrated into one unit.

In the embodiment, the vehicle 20 is configured to have front wheels 52L, 52R as driven wheels and rear wheels 54L, 54R as driven wheels connected to a powertrain consisting of the engine 22, motor 30, and automatic transmission 40. However, the vehicle may be configured to have the front wheels as driven wheels and the rear wheels as driven wheels connected to a powertrain different from the powertrain consisting of the engine 22, motor 30, and automatic transmission 40, or the front wheels as driven wheels connected to the powertrain, or the front wheels as driven wheels connected to the powertrain for the front wheels and the rear wheels as driven wheels connected to the powertrain for the rear wheels.

The following explains the relationship between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem. In the embodiment, the vehicle 20 corresponds to the "vehicle" and the HVECU 70 corresponds to the "control device."

The correspondence between the main elements of the Examples and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the Examples are examples for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be based on the description in that column, and the Examples are merely a specific example of the invention described in the Means for Solving the Problem column.

The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms without departing from the scope of the invention.

The present invention can be used in industries such as vehicle control device manufacturing.

20 vehicle, 22 engine, 23 crankshaft, 23a crank position sensor, 24 engine ECU, 25 starter motor, 26 alternator, 30 motor, 30a rotational position sensor, 31 rotating shaft, 32 inverter, 34 motor ECU, 40 automatic transmission, 41 input shaft, 41a rotation speed sensor, 42 output shaft, 42a rotation speed sensor, 43 torque converter, 44 transmission input shaft, 44a rotation speed sensor, 45 automatic transmission, 52L, 52R front wheels, 53 differential gear, 54L, 54R rear wheels, 60 high voltage battery, 61 high voltage side power line, 62 low voltage battery, 63 low voltage side power line, 64 DC/DC converter, 70 HVECU, 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 Accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 87 vehicle speed sensor, 88L, 88R, 89L, 89R wheel speed sensors.

Claims (3)

A control device for a vehicle,
the control device limits the torque of the drive wheels when an integrated value of the wheel speed difference between the front and rear wheels within a predetermined time period during running under a predetermined slip condition is equal to or greater than a threshold value.
A vehicle control device comprising: The vehicle control device according to claim 1,
the control device uses the smaller of a left wheel speed difference between a front left wheel and a rear left wheel and a right wheel speed difference between a front right wheel and a rear right wheel as the wheel speed difference between the front and rear wheels.
Vehicle control device. The vehicle control device according to claim 1 or 2,
The predetermined slippage state is defined as a state in which the shift is in second gear or lower, the vehicle is not turning, and the traction control is not operating.
Vehicle control device.

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