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

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-32894 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned documents do not disclose control of the application of engine braking force to a vehicle when the accelerator and brake pedals are released. 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 controlling the drive unit so that a required torque is output to the drive shaft, it is desirable to apply a more appropriate engine braking force to the vehicle.

[0005] The vehicle control device of the present disclosure has a primary object to apply a braking force to the vehicle by a more appropriate engine brake. [Means for solving the problem]

[0006] The vehicle control device of the present disclosure employs the following means to achieve the above-described primary 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 is summarized as comprising: 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 the upper limit of torque of the drive shaft is requested, arbitrates the upper limit torques for the upper limit request controls to set a single upper limit required torque; and a required torque setting unit that, when execution of at least one of the plurality of upper limit request controls is requested with the accelerator and brakes off, sets the required torque to the smallest torque among the control required torque for 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. [Brief explanation 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. [Figure 2] 10 is a flowchart showing an example of a processing routine executed by the HVECU 70. [Figure 3] FIG. 10 is an explanatory diagram showing an example of changes over time in the required torque Td2* and the like. DETAILED DESCRIPTION OF THE INVENTION

[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 configuration diagram of a hybrid vehicle 20 equipped with a vehicle control device according to 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 (power 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 "requested torque setting unit."

[0009] The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. The operation of the engine 22 is controlled by an engine ECU 28. The engine ECU 28 has a microcomputer that receives signals from various sensors, outputs various control signals, performs various calculations, and communicates with the HVECU 70. For example, the engine ECU 28 receives 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, fuel injection valves, spark plugs, 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 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 inverters 41 and 42. The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride 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 four, five, or six speeds. The input shaft of the transmission 60 is connected to the intermediate shaft 35, and the output shaft is connected to a drive shaft 36 which is connected 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 that 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 that instruct the execution of a variety of driving assistance controls, such as an ASL switch 63 that instructs the execution of an adjustable speed limiter (ASL) function that adjusts the vehicle's upper speed limit Vmax in accordance with the speed of road signs and the like, an ACC switch 64 that instructs the execution of an adaptive cruise control (ACC) function that adjusts the vehicle speed V to maintain a safe distance from the vehicle ahead, an AP switch 65 that instructs the execution of an automatic parking function (AP) that steers the vehicle to park automatically and adjusts the vehicle speed V without driver operation, and a PCS switch 66 that instructs the execution of a collision mitigation brake control (PCS) that applies the brakes to mitigate collision damage. When the ASL switch 63 is on, the camera ECU 61 determines at predetermined time intervals whether the vehicle speed V exceeds the upper limit speed Vmax. When the vehicle speed V is equal to or less than the upper limit speed Vmax, the camera ECU 61 sets the upper limit torque Tmaxasl to a value that is very large relative to the torque that can be output to the drive shaft 36. When the vehicle speed V exceeds the upper limit speed Vmax, the camera ECU 61 sets the upper limit torque Tmaxasl to limit 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 configured as 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 a lower limit torque Tminacc based on images captured by the camera 62 at predetermined time intervals, which limits the lower limit of the drive shaft 36 to maintain the inter-vehicle distance between the hybrid vehicle 20 and the preceding vehicle, and outputs the calculated lower limit torque Tminacc to the brake ECU 67. Therefore, the ACC is configured as 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 driver operation as 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 the predetermined torque (substitutes with the predetermined 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 activation 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 activates the brakes.

[0012] The brake ECU 67 has a microcomputer and receives input of 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 between 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 only one of the upper limit torques Tmaxasl and Tmaxps to the input upper limit torque Tmax. 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 that receives 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 receives inputs such as rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from rotational position sensors 43 and 44, and voltage Vb, current Ib, and temperature T of the battery 50 from voltage sensor 51a, current sensor 51b, and temperature sensor 51c. It also receives inputs such as accelerator opening (amount of accelerator pedal depression) Acc from accelerator pedal position sensor 84 and vehicle speed V from vehicle speed sensor 87. It outputs control signals to the inverters 41 and 42, transmission 60, etc. It calculates rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotational positions θm1 and θm2. The power storage rate SOC of the battery 50 is calculated based on the integrated value of the current Ib, and the 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, motors MG1, MG2, and transmission 60 are controlled by cooperative control between the engine ECU 28 and the HVECU 70 so that the hybrid vehicle 20 travels in an electric drive mode (EV drive mode) in which the engine 22 is stopped, or in a hybrid drive mode (HV drive mode) in which the engine 22 is running. The transmission 60 is controlled so that the gear Gs becomes a target gear Gs* based on the accelerator pedal position Acc and the vehicle speed V. The engine 22 and 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 running or stopped. The required torque Ti* is obtained by dividing a required torque Td* of the drive shaft 36 based on the accelerator pedal position 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 released in the HV driving mode, the engine 22 and motors MG1, 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 the 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 the 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 assist controls are not being executed, that is, when all of the ASL switch 63, ACC switch 64, AP switch 65, and PCS switch 66 are off, the required torque Td2* is set to the required torque Td* (which is a basic value (negative value) of the braking-side torque, hereinafter referred to as "basic braking torque Tb") when the accelerator opening Acc is 0. Motor MG1 is controlled so that engine 22 rotates at target rotation speed Ne*, and motor MG2 is controlled so that torque output is the difference between required braking torque Ti2* and engine brake torque estimated, for example, based on the torque of motor MG1. At this time, battery 50 is charged and discharged based on the power of motors MG1 and MG2. Target rotation speed Ne* may be, for example, rotation speed Ne immediately before accelerator release or a rotation speed higher than rotation speed Ne immediately before accelerator release.

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

[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 determines 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). If 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 ends. If 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 replacement required torque Trep, and the basic braking torque Tb, the smallest torque of the three torques, namely, the lower limit required torque Tmin, the replacement 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 how the required torque Td2* and the like change over time. In the diagram, the thin solid line represents an example of how the upper limit required torque Tmax changes over time. The dashed line represents an example of how the basic braking torque Tb changes over time. The dot-dash line represents an example of how the lower limit required torque Tmin or the replacement required torque Trep changes over time. The thick solid line represents an example of how the required torque Td2* changes over time. As shown in the diagram, 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 allows a negative torque equal to or less than the basic braking torque Tb to be set as the required torque Td2*, and makes it possible to avoid setting a torque exceeding the basic braking torque Tb as the required torque Td2*.

[0019] In the above-described embodiment, it is assumed that execution of the lower limit request control or the substitution request control is instructed, and that the lower limit request torque Tmin and the substitution request torque Trep are output from the brake ECU 67. However, when execution of at least one of the lower limit request control or the substitution request control is not instructed, only the torques instructed to be executed, out of the lower limit request torque Tmin and the substitution request torque Trep, need to 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 or the substitution 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 or the substitution request torque Trep input in step S100 or the basic braking torque Tb is set as the requested torque Td2*.

[0020] In a hybrid vehicle 20 equipped with the vehicle control device of the present disclosure described above, 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 and 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 different from 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 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, but may include a drive unit capable of outputting power to a drive shaft connected to an axle. Also, at least two of the camera ECU 61, the brake ECU 67, and the HVECU 70 may be configured as an integrated unit.

[0022] The above describes the forms for implementing the present invention, but the present invention is not limited to these embodiments in any way, and it goes without saying that the present invention can be implemented in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0023] The present invention can be used in the manufacturing industry of vehicle control devices, etc. [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 that limit an upper limit of torque of the drive shaft is requested, arbitrates the upper limit torques for the respective upper limit request controls and sets one upper limit request torque; a required torque setting unit that, when execution of at least one of the plurality of upper limit required 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 required control, a basic braking torque as a basic value of the braking torque when the accelerator is off, and the upper limit required torque; A vehicle control device comprising:

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