Vehicle control device

Abstract

To provide a vehicle control device which applies brake force of an engine brake to a vehicle with improved appropriateness.SOLUTION: A vehicle control device comprises: an adjustment section which sets single upper limit request torque by adjusting upper limit torque in each upper limit request control when a request is made for at least one of a plurality of upper limit request controls, which are included in a plurality of operation support controls, to control the upper limit torque on a drive shaft; and a request torque setting section which sets the smallest torque among control request torque in the operation support control included in the plurality of operation support controls but different from the upper limit request control, basic brake torque being a basic value of brake torque when an acceleration pedal is off, and the upper limit request torque as request torque when the request is made for at least one of the upper limit request controls in a state where acceleration and brake pedals are off.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Conventionally, as this type of vehicle control device, one that is used in a vehicle equipped with multiple actuators and controls the actuators has been proposed (for example, see Patent Document 1). In this device, when execution of at least one of multiple driving assistance controls is requested, the control amount of the actuators by the multiple driving assistance controls is arbitrated, and the actuators are controlled based on the arbitration result. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-32894 A Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned documents do not disclose control of the application of a braking force by so-called engine braking to the vehicle when the accelerator and brake are off. In a device used in a vehicle equipped with a drive unit capable of outputting power to a drive shaft connected to an axle, and which controls the drive unit so that a required torque is output to the drive shaft, it is desired to apply a more appropriate braking force by engine braking to the vehicle.

[0005] The main object of the vehicle control device disclosed herein is to apply a more appropriate engine brake braking force to the vehicle. [Means for solving the problem]

[0006] The vehicle control device of the present disclosure employs the following means to achieve the above-mentioned main object. The vehicle control device of the present disclosure is used in a vehicle equipped with a drive unit capable of outputting power to a drive shaft connected to an axle, and controls the drive unit so that a required torque is output to the drive shaft, and includes an arbitration unit that arbitrates upper limit torques for each upper limit request control to set one upper limit required torque when execution of at least one of a plurality of upper limit request controls that are included in a plurality of driving assistance controls and limit an upper limit of torque of the drive shaft is requested, and a required torque setting unit that sets the required torque to the smallest torque among a control required torque in the driving assistance control that is included in the plurality of driving assistance controls and that is different from the upper limit request control, a basic braking torque as a basic value of the braking torque when the accelerator is off, and the upper limit required torque when execution of at least one of the plurality of upper limit request controls is requested in an accelerator-off and brake-off state. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle 20 equipped with a vehicle control device according to an embodiment. [Diagram 2] 11 is a flowchart showing an example of a processing routine executed by the HVECU 70. [Diagram 3] FIG. 4 is an explanatory diagram showing an example of changes over time in required torque Td2* etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Next, an embodiment of the present disclosure will be described with reference to the drawings. Next, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a hybrid vehicle 20 equipped with a vehicle control device of an embodiment. As shown in the figure, the hybrid vehicle 20 includes an engine 22, an engine electronic control unit (hereinafter referred to as "engine ECU") 28, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery (electricity storage device) 50, a transmission 60, a camera electronic control unit (hereinafter referred to as "camera ECU") 61, a brake electronic control unit (hereinafter referred to as "brake ECU") 66, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70. In the embodiment, the camera ECU 61 and the brake ECU 67 correspond to an "adjustment unit", and the HVECU 70 corresponds to a "request torque setting unit".

[0009] The engine 22 is configured as an internal combustion engine that uses fuel such as gasoline or diesel to output power. The operation of the engine 22 is controlled by an engine ECU 28. The engine ECU 28 has a microcomputer, which inputs signals from various sensors, outputs various control signals, performs various calculations, and communicates with the HVECU 70. For example, the engine ECU 28 inputs the crank angle θcr of the crankshaft 23 of the engine 22 from a crank position sensor 23a. The engine ECU 28 outputs control signals to a throttle valve, a fuel injection valve, a spark plug, etc. The engine ECU 28 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr.

[0010] The planetary gear 30 is configured as a single-pinion type planetary gear mechanism, with a rotor of a motor MG1 connected to the sun gear, a crankshaft 23 of the engine 22 connected to the carrier, and an intermediate shaft 35 connected to the ring gear. A rotor of a motor MG2 is attached to the intermediate shaft 35. The motors MG1 and MG2 are configured as, for example, synchronous generator motors, and are rotationally driven by the HVECU 70 controlling the switching of multiple switching elements of the inverters 41 and 42. The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-hydrogen secondary battery, and is connected to the power line 54 together with the inverters 41 and 42. The battery 50 is managed by the HVECU 52. The transmission 60 is configured as a stepped transmission, for example, with 4 speeds, 5 speeds, or 6 speeds. An input shaft of the transmission 60 is connected to the intermediate shaft 35, and an output shaft is connected to a drive shaft 36 which is coupled to drive wheels 39a, 39b via a differential gear 38. The transmission 60 is controlled by the HVECU 70.

[0011] The camera ECU 61 has a microcomputer, and inputs signals from various sensors, outputs various control signals, performs various calculations, and communicates with the brake ECU 67. The camera ECU 61 receives an image signal from a camera 62 installed at the front of the hybrid vehicle 20 and a vehicle speed V from a vehicle speed sensor 87. The camera ECU 61 receives on-off signals from switches for instructing the execution of a plurality of driving assistance controls, such as an ASL switch 63 for instructing the execution of an adjustable speed limit function (ASL) that adjusts the upper limit speed Vmax of the vehicle according to the speed of a road sign or the like, an ACC switch 64 for instructing the execution of an adaptive cruise control function (ACC) that adjusts the vehicle speed V to maintain a distance from a vehicle ahead, an AP switch 65 for instructing the execution of an automatic parking function (AP) that steers the vehicle to park automatically without the driver's operation and adjusts the vehicle speed V, and a PCS switch 66 for instructing the execution of a collision damage mitigation brake control (PCS) that applies the brakes to reduce collision damage. When the ASL switch 63 is on, the camera ECU 61 determines whether the vehicle speed V exceeds the upper limit speed Vmax at predetermined time intervals, and when the vehicle speed V is equal to or less than the upper limit speed Vmax, sets the upper limit torque Tmaxasl to a value that is very large with respect to the torque that can be output to the drive shaft 36. When the vehicle speed V exceeds the upper limit speed Vmax, sets the upper limit torque Tmaxasl for limiting the upper limit of the torque of the drive shaft 36 so that the vehicle speed V is equal to or less than the upper limit speed Vmax, and outputs the set upper limit torque Tmaxasl to the brake ECU 67. In other words, the ASL is an upper limit request control that limits the upper limit of the torque output to the drive shaft 36. When the ACC switch 64 is on, the camera ECU 61 calculates the lower limit torque Tminacc that limits the lower limit of the drive shaft 36 for maintaining the inter-vehicle distance between the hybrid vehicle 20 and the preceding vehicle based on the image captured by the camera 62 at predetermined time intervals, and outputs the calculated lower limit torque Tminacc to the brake ECU 67. Therefore, the ACC is a lower limit request control that limits the lower limit of the torque output to the drive shaft 36.When the AP switch 65 is on, the camera ECU 61 sets a predetermined torque as a torque for automatic parking without the driver's operation to the replacement torque Trepap, and outputs the set replacement torque Trepap to the brake ECU 67. Therefore, the AP is a replacement request control that sets the torque output to the drive shaft 36 to a predetermined torque (substitutes with the determined torque). When the PCS switch 66 is on, the camera ECU 61 sets an upper limit torque Tmaxpcs when a collision is predicted based on an image captured by the camera 62, and outputs the set upper limit torque Tmaxpcs and a brake operation command to the brake ECU 67. In other words, the PCS is an upper limit request control that limits the upper limit of the torque output to the drive shaft 36 and a control that operates the brake.

[0012] The brake ECU 67 has a microcomputer, and receives inputs such as a brake pedal position, which is the amount of depression of the brake pedal, from a brake pedal position sensor (not shown). The brake ECU 67 controls a brake actuator 68 of a hydraulic brake device so as to apply a braking force to the vehicle based on the amount of depression of the brake pedal and a brake operation command from the camera ECU 61. When the brake ECU 67 receives the upper limit torques Tmaxasl and Tmaxpcs from the camera ECU 61, the brake ECU 67 arbitrates the upper limit torques Tmaxasl and Tmaxpcs to set an upper limit required torque Tmax, and outputs the upper limit required torque Tmax to the HVECU 70. The arbitration of the upper limit torques Tmaxasl and Tmaxpcs is performed, for example, by setting the upper limit torque Tmaxpcs to the upper limit required torque Tmax when both the upper limit torques Tmaxasl and Tmaxpcs are input, and by setting the input upper limit torque to the upper limit required torque Tmax when only one of the upper limit torques Tmaxasl and Tmaxps is input. When the ASL switch 63 and the ACC switch 64 are off, the upper limit required torque Tmax is not output to the HVECU 70. The brake ECU 67 outputs the lower limit torque Tminacc from the camera ECU 61 to the HVECU 70 as the lower limit required torque Tmin. When the ACC switch 64 is off, the lower limit required torque Tmin is not output to the HVECU 70. The brake ECU 67 outputs the replacement torque Trepap to the HVECU 70 as the replacement required torque Trep. When the AP switch 65 is off, the replacement required torque Trep is not output to the HVECU 70.

[0013] The HVECU 70 has a microcomputer, which inputs signals from various sensors, outputs various control signals, performs various calculations, and communicates with the engine ECU 28 and the brake ECU 67. For example, the HVECU 70 inputs the rotational positions θm1, θm2 of the rotors of the motors MG1, MG2 from the rotational position sensors 43, 44, the voltage Vb, current Ib, and temperature T of the battery 50 from the voltage sensor 51a, current sensor 51b, and temperature sensor 51c, etc. The HVECU 70 also inputs the accelerator opening (amount of depression of the accelerator pedal) Acc from the accelerator pedal position sensor 84, the vehicle speed V from the vehicle speed sensor 87, etc. The HVECU 70 outputs control signals to the inverters 41, 42, the transmission 60, etc. The HVECU 70 calculates the rotational speeds Nm1, Nm2 of the motors MG1, MG2 based on the rotational positions θm1, θm2. The power storage rate SOC of the battery 50 is calculated based on the integrated value of the current Ib, and input / output limits (allowable input / output power) Win, Wout of the battery 50 are calculated based on the power storage rate SOC and the temperature.

[0014] In the hybrid vehicle 20, the engine 22, the motors MG1, MG2, and the transmission 60 are controlled by cooperative control between the engine ECU 28 and the HVECU 70 so that the vehicle travels in an electric drive mode (EV drive mode) in which the engine 22 stops rotating, or in a hybrid drive mode (HV drive mode) in which the engine 22 keeps rotating. The transmission 60 is controlled so that the gear Gs becomes a target gear Gs* based on the accelerator opening Acc and the vehicle speed V. The engine 22 and the motors MG1, MG2 are controlled so that a required torque Ti* of the intermediate shaft 35 is output to the intermediate shaft 35 with the engine 22 stopping or rotating. The required torque Ti* is obtained by dividing a required torque Td* of the drive shaft 36 based on the accelerator opening Acc and the vehicle speed V by a rotation speed ratio Gt corresponding to the gear Gs of the transmission 60.

[0015] In particular, when the accelerator and brake are off in the HV driving mode, the engine 22 and the motors MG1 and MG2 are controlled so that a required braking torque Ti2* (negative value) of the intermediate shaft 35 is output to the intermediate shaft 35 by a so-called engine brake torque acting on the intermediate shaft 35 due to fuel cut of the engine 22 and motoring of the engine 22 by the motor MG1 and a regenerative torque of the motor MG2. The required braking torque Ti2* is obtained by dividing the required torque (required braking torque) Td2* of the drive shaft 36 by the rotation speed ratio Gt of the transmission 60. When the above-mentioned multiple driving assistance controls are not executed, that is, when all of the ASL switch 63, the ACC switch 64, the AP switch 65, and the PCS switch 66 are off, the required torque Td2* is set to the above-mentioned required torque Td* (basic value (negative value) of the torque on the braking side, hereinafter referred to as "basic braking torque Tb") when the accelerator opening Acc is 0. The motor MG1 is controlled so that the engine 22 rotates at a target rotation speed Ne*, and the motor MG2 is controlled so that a torque that is the difference between the required braking torque Ti2* and an engine brake torque estimated based on the torque of the motor MG1, for example, is output. At this time, the battery 50 is charged and discharged based on the power of the motors MG1 and MG2. The target rotation speed Ne* is, for example, the rotation speed Ne immediately before the accelerator is released or a rotation speed higher than the rotation speed Ne immediately before the accelerator is released.

[0016] Next, the operation of the hybrid vehicle 20, in particular, the process of setting the required torque Td2* when the upper limit required torque Tmax is input from the brake ECU 67 during the accelerator and brake off in the HV driving mode, i.e., when the execution of at least one upper limit required control among the multiple driving assistance controls is requested, will be described. FIG. 2 is a flowchart showing an example of a processing routine executed by the HVECU 70. This routine is repeatedly executed during the accelerator and brake off in the HV driving mode. For the sake of convenience, it is assumed in this routine that the execution of the lower limit required control and the replacement required control is instructed, and the lower limit required torque Tmin and the replacement required torque Trep are output from the brake ECU 67.

[0017] When this routine is executed, the HVECU 70 executes a process of inputting the upper limit required torque Tmax, the lower limit required torque Tmin, the replacement required torque Trep, and the basic braking torque Tb from the brake ECU 67 (step S100). Then, it is determined whether the upper limit required torque Tmax is smaller than all three torques, the lower limit required torque Tmin, the replacement required torque Trep, and the basic braking torque Tb (step S110). When the upper limit required torque Tmax is smaller than all three torques, the lower limit required torque Tmin, the replacement required torque Trep, and the basic braking torque Tb, the upper limit required torque Tmax is set to the required torque Td2* (step S120), and this routine is terminated. When the upper limit required torque Tmax is equal to or greater than at least one of the three torques, namely, the lower limit required torque Tmin, the substitution required torque Trep, and the basic braking torque Tb, the smallest torque of the three torques, namely, the lower limit required torque Tmin, the substitution required torque Trep, and the basic braking torque Tb, is set as the required torque Td2* (step S130), and this routine is terminated.

[0018] FIG. 3 is an explanatory diagram showing an example of time change of the required torque Td2*, etc. In the figure, the thin solid line is an example of time change of the upper limit required torque Tmax. The dashed line is an example of time change of the basic braking torque Tb. The dashed line is an example of time change of the lower limit required torque Tmin or the replacement required torque Trep. The thick solid line is an example of time change of the required torque Td2*. As shown in the figure, the required torque Td2* is set to the smallest torque among the upper limit required torque Tmax, the lower limit required torque Tmin, the replacement required torque Trep, and the basic braking torque Tb. This makes it possible to avoid setting a negative torque equal to or less than the basic braking torque Tb as the required torque Td2* and setting a torque exceeding the basic braking torque Tb as the required torque Td2*.

[0019] In the above embodiment, it is assumed that the execution of the lower limit request control or the replacement request control is instructed, and the lower limit request torque Tmin and the replacement request torque Trep are output from the brake ECU 67. However, when the execution of at least one of the lower limit request control or the replacement request control is not instructed, only the torque of the lower limit request torque Tmin and the replacement request torque Trep for which execution is instructed may be input in step S100. Then, in step S110, it is determined whether the upper limit request torque Tmax is smaller than the torque of the lower limit request torque Tmin and the replacement request torque Trep input in step S100 or the basic braking torque Tb, and in step S130, the smallest torque of the torque of the lower limit request torque Tmin and the replacement request torque Trep input in step S100 or the basic braking torque Tb may be set as the request torque Td2*.

[0020] In a hybrid vehicle 20 equipped with the vehicle control device disclosed hereinabove, when execution of at least one of the upper limit request controls included in the multiple driving assistance controls is requested, the upper limit torques Tmaxasl, Tmaxpcs for each upper limit request control are arbitrated to set a single upper limit request torque Tmax, and when execution of at least one of the multiple upper limit request controls is requested with the accelerator and brakes off, the smallest torque among the control request torque (lower limit request torque Tmin or replacement request torque Trep) in a driving assistance control other than the upper limit request control included in the multiple driving assistance controls, the basic braking torque Tb, and the upper limit request torque Tmax is set as the required torque Td2*, so that a more appropriate engine brake braking force can be applied to the vehicle.

[0021] In the above-described embodiment, the hybrid vehicle 20 does not need to include the transmission 60, and may include a drive device capable of outputting power to a drive shaft connected to an axle. In addition, at least two of the camera ECU 61, the brake ECU 67, and the HVECU 70 may be integrated.

[0022] Although the above describes the form for carrying out the present invention, the present invention is not limited to such an embodiment, and it is of course possible to carry out the present invention in various forms without departing from the spirit of the present invention. [Industrial Applicability]

[0023] The present invention can be used in the vehicle control device manufacturing industry and the like. [Explanation of symbols]

[0024] 61 Camera ECU, 66 Brake ECU, 70 HVECU.

Claims

[Claim 1] A vehicle control device is used in a vehicle having a drive unit capable of outputting power to a drive shaft connected to an axle, and controls the drive unit so that a required torque is output to the drive shaft, an arbitration unit that, when execution of at least one of a plurality of upper limit request controls that are included in a plurality of driving assistance controls and limit an upper limit of torque of the drive shaft is requested, arbitrates the upper limit torques for the respective upper limit request controls to set one upper limit request torque; a required torque setting unit that, when execution of at least one of the plurality of upper limit request controls is requested in an accelerator-off and brake-off state, sets the required torque to the smallest torque among a control required torque in the driving assistance control that is included in the plurality of driving assistance controls and that is different from the upper limit request control, a basic braking torque as a basic value of the braking torque when the accelerator is off, and the upper limit request torque; A vehicle control device comprising:

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