Vehicle control device

Abstract

To prevent the repetition of slip and grip caused by the spinning of the drive wheel during driving.SOLUTION: A vehicle controller limits the torque of drive wheels if, during travel under a predetermined slip condition, the cumulative value of the speed difference between the front and rear wheels reaches a threshold within a predetermined duration. This can prevent slipping due to the spinning of the drive wheels, thereby reducing the repetitive cycle of slip and grip during driving.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, as a control device for this type of vehicle, among the rotational speeds of each wheel detected by a wheel speed sensor, the lowest rotational speed is used as a reference rotational speed, and the slip of each wheel is determined by comparing the reference rotational speed with the rotational speed of the motor corresponding to each wheel (see, for example, Patent Document 1). In this vehicle control device, based on the result of slip determination, the required torque of the motor that drives the slip wheel is calculated so that the rotational speed of the slip wheel matches the target rotational speed, and the resulting torque reduction amount of the slip wheel is redistributed to the non-slip wheels. By such processing, it is said that the occurrence of slip of each wheel is suppressed, and the vibration of the motor and the tire is suppressed to improve drivability.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When slip and grip due to wheel spin of the drive wheels repeatedly occur, the vibration due to repetition grows and causes oscillation in the power train. This oscillation of the power train may cause a collision with the stopper of the mount and generate a knocking sound. Such knocking sounds give discomfort and a sense of incongruity to the driver and passengers.

[0005] The main object of the vehicle control device of the present invention is to suppress running in which slip and grip due to wheel spin of the drive wheels are repeated.

Means for Solving the Problems

[0006] The vehicle control device of the present invention has adopted the following means to achieve the above-mentioned main purpose.

[0007] The vehicle control device of the present invention is a vehicle control device, wherein the control device restricts the torque of the drive wheels when the integrated value of the wheel speed difference between the front and rear wheels within a predetermined time is equal to or greater than a threshold value during traveling at a predetermined slip. This is the gist of the present invention.

[0008] 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 predetermined time is equal to or greater than a threshold value during traveling at a predetermined slip, the torque of the drive wheels is restricted, thereby suppressing the slip due to the wheel spin of the drive wheels. As a result, it is possible to suppress the traveling in which the slip and grip due to the wheel spin of the drive wheels are repeated.

[0009] Here, as the "wheel speed difference between the front and rear wheels", the smaller one 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 may be used. Further, as the "traveling at a predetermined slip", the case where all of the conditions that the shift is 2nd speed or lower, the vehicle is not turning, and the traction control is not operating may be used. As the "predetermined time", 300 msec, 500 msec, 700 msec, etc. can be used.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0011] Next, embodiments for carrying out the present invention will be described using examples.

Examples

[0012] FIG. 1 is a configuration diagram showing an outline of the configuration of a vehicle 20 as an embodiment of the present invention. As shown in the figure, the vehicle 20 of 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.

[0013] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil from a fuel tank. The crankshaft 23 of this engine 22 is connected to the rotating shaft 31 (rotor) of the motor 30 via the clutch K0. The engine 22 is operationally controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24.

[0014] Although not shown, the engine ECU 24 includes a microcomputer having a CPU, a ROM, a RAM, a flash memory, input / output ports, and communication ports. Signals from various sensors necessary for operationally controlling the engine 22 are input to the engine ECU 24 via the input ports. Examples of signals input to the engine ECU 24 include the crank angle θcr from a 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 operationally controlling the engine 22 are output from the engine ECU 24 via the output ports. The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotational speed Ne of the engine 22 based on the crank angle θcr of the crankshaft 23 from the crank position sensor 23a.

[0015] A starter motor 25 for cranking the engine 22 and an alternator 26 for generating electricity using the 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 the low-voltage side power line 63 together with the low-voltage battery 62 and are controlled by the HVECU 70.

[0016] The motor 30 is configured as a synchronous generator motor and has a rotor with permanent magnets embedded in the rotor core and a stator with three-phase coils wound around the stator core. The rotating shaft 31 to which the rotor of this 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 side power line 61. The motor 30 is rotationally driven by switching control of a plurality of switching elements of the inverter 32 by a motor electronic control unit (hereinafter referred to as "motor ECU") 34.

[0017] Although not shown, the motor ECU 34 includes 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 ports. Examples of the signals input to the motor ECU 34 include the rotational position θm from a 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 current sensors that detect the phase currents of each phase of the motor 30. Control signals to the inverter 32 and the like are output from the motor ECU 34 via the output ports. The motor ECU 34 is connected to the HVECU 70 via the communication port. The motor ECU 34 calculates the rotational 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.

[0018] The clutch K0 is configured as, for example, a hydraulically driven friction clutch, is controlled by the HVECU 70, and connects and disconnects the crankshaft 23 of the engine 22 and the rotating shaft 31 of the motor 30.

[0019] The automatic transmission 40 includes a torque converter 43 and a six-speed automatic transmission 45. The torque converter 43 is configured as a general fluid transmission device, and amplifies 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, or transmits it as it is without amplifying the torque. The automatic transmission 45 includes a transmission input shaft 44, an output shaft 42 connected to the rear wheels 54L and 54R as drive wheels via a differential gear 53, a plurality of planetary gears, and a plurality of hydraulically driven friction engagement elements (clutches, brakes). The automatic transmission 45 forms forward and reverse gears from the first speed to the sixth speed by engaging and disengaging the plurality of friction engagement elements, and transmits power between the transmission input shaft 44 and the output shaft 42. The clutch K0 and the automatic transmission 45 are supplied with hydraulic pressure of hydraulic oil regulated from a mechanical oil pump or an electric oil pump by a hydraulic control device (not shown). The hydraulic control device includes a valve body in which a plurality of oil passages are formed, a plurality of regulator valves, a plurality of linear solenoid valves, and the like. This hydraulic control device is controlled by the HVECU 70.

[0020] The high-voltage battery 60 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery with a rated voltage of about several hundred volts, and is connected to the high-voltage side 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 12V or 14V, and is connected to the low-voltage side power line 63 together with the starter motor 25 and the alternator 26. The DC / DC converter 64 is connected to the high-voltage side power line 61 and the low-voltage side power line 63. This DC / DC converter 64 supplies the power of the high-voltage side power line 61 to the low-voltage side power line 63 with a voltage step-down.

[0021] The HVECU 70 includes a microcomputer (not shown) having a CPU, a ROM, a RAM, a flash memory, input / output ports, and communication ports. Signals from various sensors are input to the HVECU 70 via the input ports. Examples of the signals input to the HVECU 70 include the rotational speed Nin from a rotational speed sensor 41a attached to the input shaft 41 of the automatic transmission 40, the rotational speed Nmi from a rotational speed sensor 44a attached to the transmission input shaft 44 of the automatic transmission 40, and the rotational speed Nout from a rotational speed sensor 42a attached to the output shaft 42 of the automatic transmission 40. Also included are 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. Further examples include the ignition signal from the ignition switch 80, the shift position SP from a shift position sensor 82 that detects the operating position of the shift lever 81, the accelerator opening Acc from an accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83, and the brake pedal position BP from a brake pedal position sensor 86 that detects the depression amount of the brake pedal 85. Additionally, the vehicle speed V from the vehicle speed sensor 87 and the wheel speeds Vfl, Vfr, Vrl, and Vrr from wheel speed sensors 88L, 88R, 89L, and 89R attached to the front wheels 52L, 52R and the rear wheels 54L, 54R can be mentioned.

[0022] From the HVECU 70, various control signals are output via the output ports. Examples of the signals output from the HVECU 70 include the control signal to the starter motor 25 and the control signal to the alternator 26. Also included are the control signals to the clutch K0 and the automatic transmission 40 (hydraulic control device), and the 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 gear ratio Gt of the automatic transmission 40 by dividing the rotational speed Nin of the input shaft 41 of the automatic transmission 40 from the rotational speed sensor 41a by the rotational speed Nout of the output shaft 42 of the automatic transmission 40 from the rotational speed sensor 42a.

[0023] In the vehicle 20 of the embodiment configured in this way, the engine 22, the clutch K0, the motor 30, and the automatic transmission 40 are controlled to run in the hybrid driving mode (HV driving mode) or the electric driving mode (EV driving mode) by the cooperative control of the HVECU 70, the engine ECU 24, and the motor ECU 34. 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 disengaged and the vehicle runs without using the power of the engine 22.

[0024] In the control of the automatic transmission 40 in the HV driving mode and the EV driving mode, the HVECU 70 first sets the target gear stage M* of the automatic transmission 45 based on the accelerator opening Acc and the vehicle speed V. Then, when the gear stage M of the automatic transmission 45 matches the target gear stage M*, the automatic transmission 45 is controlled so that the gear stage M is maintained. On the other hand, when the gear stage M and the target gear stage M* are different, the automatic transmission 45 is controlled so that the gear stage M matches the target gear stage M*.

[0025] In the control of the engine 22 and the motor 30 in the HV driving mode, the HVECU 70 first sets a required torque Tout* (required for the output shaft 42 of the automatic transmission 40) required for driving based on the accelerator opening Acc and the vehicle speed V. Subsequently, a value obtained by dividing the required torque Tout* of the output shaft 42 by the gear ratio Gt of the automatic transmission 40 is set as a temporary required torque Tintmp as a temporary value of the required torque Tin* of the input shaft 41. Then, a value obtained by subjecting the temporary required torque Tintmp of the input shaft 41 to a slow change process such as rate processing or smoothing processing is set as the required torque Tin* of the input shaft 41. When the required torque Tin* of the input shaft 41 is set in this way, 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 transmitted to the engine ECU 24 and the torque command Tm* of the motor 30 is transmitted to the motor ECU 34. When receiving the target torque Te*, the engine ECU 24 performs operation control (such as intake air amount control, fuel injection control, ignition control, etc.) of the engine 22 so that the engine 22 is operated at the target torque Te*. When receiving the torque command Tm*, the motor ECU 34 performs switching control of a plurality of switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

[0026] In the control of 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 it to the motor ECU 34. The motor ECU 34 performs switching control of a plurality of switching elements of the inverter 32 so that the motor 30 is driven by the torque command Tm*.

[0027] Next, the operation of the vehicle 20 of the thus configured embodiment will be described, particularly the operation during running with slip. Here, "running with slip" is intended to mean running in which the driving wheels repeat slight slip due to wheelspin and grip. FIG. 2 is a flowchart showing an example of the running-with-slip control process executed by the HVECU 70. This process is repeatedly executed at predetermined time intervals.

[0028] When the running-with-slip control process is executed, the HVECU 70 first determines whether the conditions for executing the running-with-slip control are satisfied (step S100). The conditions for executing the running-with-slip control are running conditions in which running in which the driving wheels repeat slight slip due to wheelspin and grip is likely to occur. For example, conditions such as the shift being in the second gear or lower, the vehicle not being in a turning state, and the traction control not being activated can be cited. The determination that the conditions for executing the running-with-slip control are satisfied is made when all of the above conditions are satisfied. When it is determined that the conditions for executing the running-with-slip control are not satisfied, it is determined that the running-with-slip control is unnecessary, and the process ends.

[0029] When it is determined in step S100 that the conditions for executing the running-with-slip control are satisfied, the front-rear wheel speed differences ΔVL and ΔVR are calculated (step S110). The front-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. Also, the front-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-rear wheel speed differences ΔVL and ΔVR is obtained as the front-rear wheel speed difference ΔV (step S120), and the integrated value ΣΔV of the front-rear wheel speed difference ΔV from a predetermined time before is calculated (step S130). Here, as the predetermined time, 300 msec, 500 msec, 700 msec, etc. can be used.

[0030] Subsequently, it is determined whether or not the integrated value ΣΔV of the front and rear wheel speed differences ΔV from before a predetermined time is equal to or greater than a threshold value Vref1 (step S140). The threshold value Vref1 is a threshold value for determining whether or not slip running 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 slip running is occurring, and torque limitation is imposed on the drive wheels (rear wheels 54L and 54R in the embodiment) (step S150). As the torque limitation of the drive wheels, for example, an upper limit guard (such as 60% or 70% of the maximum output torque) is imposed on the required torque Tout* required for the output shaft 42 of the automatic transmission 40 set based on the accelerator opening Acc and the vehicle speed V, or a value obtained by multiplying the required torque Tout* by a coefficient k smaller than 1 (such as 0.6, 0.7, or 0.8) can be used as the required torque Tout*. By imposing such torque limitation on the drive wheels, it is possible to suppress slip due to the rotation of the drive wheels (rear wheels 54L and 54R in the embodiment), and it is possible to suppress running in which slip and grip due to the rotation of the drive wheels are repeated.

[0031] Next, it is determined whether or not the integrated value ΣΔV of the front and rear wheel speed differences ΔV from before a predetermined time is equal to or greater than a threshold value Vref2 (step S160). A value slightly smaller than the threshold value Vref1 is used as the threshold value Vref2. When it is determined that the integrated value ΣΔV is less than the threshold value Vref2, the torque limitation of the drive wheels (rear wheels 54L and 54R in the embodiment) is released (step S170).

[0032] The processes of steps S140 to S170 are processes for imposing and releasing torque limits on the drive wheels, and use the threshold value Vref1 and the threshold value Vref2 to provide hysteresis. That is, when the integrated value ΣΔV of the front and rear wheel speed differences ΔV from a predetermined time ago reaches the threshold value Vref1 or more, a torque limit is imposed on the drive wheels, and then, when the integrated value ΣΔV of the front and rear wheel speed differences ΔV from a predetermined time ago reaches less than the threshold value Vref2, the torque limit on the drive wheels is released. Therefore, even if the integrated value ΣΔV of the front and rear wheel speed differences ΔV from a predetermined time ago reaches less than the threshold value Vref1 while the torque limit is being imposed, the torque limit on the drive wheels continues as long as the integrated value ΣΔV is equal to or more than the threshold value Vref2.

[0033] In the vehicle 20 of the embodiment described above, when the conditions for executing the slip-time running control are satisfied, the front and rear wheel speed difference ΔV is calculated, and when the integrated value ΣΔV of the front and rear wheel speed differences ΔV from a predetermined time ago reaches the threshold value Vref1 or more, a torque limit is imposed on the drive wheels (the rear wheels 54L and 54R in the embodiment). Thereby, it is possible to suppress the slip due to the wheel spin of the drive wheels, and it is possible to suppress the running that repeatedly slips and grips due to the wheel spin of the drive wheels. Moreover, since the smaller of the front and rear wheel speed differences ΔVL and ΔVR is obtained as the front and rear wheel speed difference ΔV, it is possible to more appropriately determine whether or not the running during slip is occurring.

[0034] In the vehicle 20 of the embodiment, it is assumed that an automatic transmission 45 with six-speed shifting is provided. However, it may be provided with an automatic transmission such as a four-speed shifting, a five-speed shifting, or an eight-speed shifting.

[0035] In the vehicle 20 of the embodiment, it is assumed that the engine ECU 24, the motor ECU 34, and the HV ECU 70 are provided. However, at least two of these may be integrally configured.

[0036] In the vehicle 20 of the embodiment, it is configured to include front wheels 52L and 52R as driven wheels, an engine 22, a motor 30, an automatic transmission 40, and rear wheels 54L and 54R as drive wheels connected to a power train composed of these components. However, it may be configured to include rear wheels as drive wheels connected to a power train different from the power train composed of the front wheels as driven wheels, the engine 22, the motor 30, and the automatic transmission 40. Alternatively, it may be configured to include front wheels as drive wheels connected to the power train and rear wheels as driven wheels. Or it may be configured to include front wheels as drive wheels connected to a front-wheel power train and rear wheels as drive wheels connected to a rear-wheel power train.

[0037] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems will be described. In the embodiment, the vehicle 20 corresponds to the "vehicle", and the HVECU 70 corresponds to the "control device".

[0038] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the section of means for solving the problems is an example for specifically explaining the form for implementing the invention described in the section of means for solving the problems in the embodiment. Therefore, it does not limit the elements of the invention described in the section of means for solving the problems. That is, the interpretation of the invention described in the section of means for solving the problems should be made based on the description in that section, and the embodiment is merely a specific example of the invention described in the section of means for solving the problems.

[0039] As described above, the embodiments have been used to explain the forms for implementing the present invention. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Industrial Applicability

[0040] The present invention can be used in the manufacturing industry of control devices for vehicles and the like.

Explanation of Reference Numerals

[0041] 20 Vehicle, 22 Engine, 23 Crankshaft, 23a Crank Position Sensor, 24 Engine ECU, 25 Starter Motor, 26 Alternator, 30 Motor, 30a Rotation Position Sensor, 31 Rotation 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

1. A control device for a vehicle, wherein when the integrated value of the wheel speed difference between the front and rear wheels within a predetermined time is equal to or greater than a threshold value during traveling at a predetermined slip, the control device restricts the torque of the drive wheels. A control device for a vehicle, characterized by the above.

2. A control device for a vehicle according to Claim 1, wherein the control device uses the smaller one 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 as the wheel speed difference between the front and rear wheels. A control device for a vehicle.

3. A control device for a vehicle according to Claim 1 or 2, wherein the traveling at a predetermined slip is when all of the conditions that the shift is at the second speed or lower, the vehicle is not turning, and the traction control is not operating are satisfied. A control device for a vehicle.

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