Vehicle control device

Abstract

To provide a vehicle control device that is able to appropriately operate an idling stop control according to each driver.SOLUTION: A master cylinder hydraulic pressure of when a vehicle subjected to a brake operation is stopped, is stored, and a predetermined hydraulic pressure which is a threshold value for performing an idling stop control is corrected based on the stored master cylinder hydraulic pressure. This allows the idling stop control to be easily activated according to an amount of brake operation by a driver when the vehicle subjected to the brake operation is stopped. In addition, when the idling stop control is performed, a brake hydraulic pressure, which is the master cylinder hydraulic pressure, is increased by a brake actuator. This prevents the vehicle from sliding down while the engine is stopped, and from starting to move when the engine is restarted. Thereby, the idling stop control can appropriately be performed according to each driver.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that performs idling stop control. [Background technology]

[0002] A vehicle control device is well known that is mounted on a vehicle including an engine and a brake actuator that supplies brake master cylinder hydraulic pressure generated from a brake master cylinder in response to a brake operation by a driver to brake wheel cylinders provided on each wheel as brake hydraulic pressure and that supplies the brake hydraulic pressure to the brake wheel cylinders as needed regardless of the brake operation, and that performs idling stop control to temporarily stop operation of the engine when the brake operation is performed to bring the vehicle to a stop. For example, a vehicle brake system described in Patent Document 1 is such a device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-137828 Summary of the Invention [Problem to be solved by the invention]

[0004] When the idle stop control is performed, a lack of braking torque applied to the wheels may cause the vehicle to start moving when the engine is restarted or the vehicle to roll back while the engine is stopped. To prevent such phenomena, a certain level of braking torque must be applied to the wheels. A threshold value for the master cylinder hydraulic pressure when the vehicle is stopped by applying the brakes is set to enable the idle stop control. For example, the idle stop control is performed when the master cylinder hydraulic pressure when the vehicle is stopped by applying the brakes exceeds a predetermined hydraulic pressure. However, in the case of a driver who applies only a small amount of brake force, there may be situations where the idle stop control cannot be activated even if the driver intends to stop the vehicle.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can appropriately activate idling stop control in response to each driver. [Means for solving the problem]

[0006] The gist of the first invention is a vehicle control device that (a) is mounted on a vehicle having an engine and a brake actuator that supplies master cylinder hydraulic pressure generated from a brake master cylinder in response to a brake operation by a driver to brake wheel cylinders provided on each wheel as brake hydraulic pressure and supplies the brake hydraulic pressure to the brake wheel cylinders as necessary regardless of the brake operation, and that performs idling stop control to temporarily stop operation of the engine when the vehicle is stopped after the brake operation is performed, (b) performs the idling stop control when the master cylinder hydraulic pressure when the vehicle is stopped after the brake operation is performed exceeds a predetermined hydraulic pressure, and (c) stores the master cylinder hydraulic pressure when the vehicle is stopped after the brake operation is performed, corrects the predetermined hydraulic pressure based on the stored master cylinder hydraulic pressure, and when performing the idling stop control, increases the brake hydraulic pressure that is set to the master cylinder hydraulic pressure by the brake actuator. [Effects of the Invention]

[0007] According to the first aspect of the present invention, the master cylinder hydraulic pressure when the vehicle is stopped due to a brake operation is stored, and the predetermined hydraulic pressure, which is the threshold for performing the idling stop control, is corrected based on the stored master cylinder hydraulic pressure. This makes it easier to activate the idling stop control in accordance with the amount of brake operation by the driver when the vehicle is stopped due to a brake operation. In addition, when performing the idling stop control, the brake hydraulic pressure set as the master cylinder hydraulic pressure is increased by the brake actuator. This prevents the vehicle from rolling over while the engine is stopped and from starting to move when the engine is restarted. Therefore, the idling stop control can be appropriately activated according to each driver. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and control systems for various controls in the vehicle. [Figure 2] 1 is a flowchart illustrating the main control operations of the electronic control device, and is a flowchart illustrating the control operations for appropriately operating S&S control in response to each driver. [Figure 3] This is a flowchart explaining the main control operations of the electronic control device, and explains the control operations for appropriately operating S&S control in response to each driver, and is executed in parallel with the flowchart of Figure 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Example]

[0010] Fig. 1 is a diagram illustrating the general configuration of a vehicle 10 to which the present invention is applied, and also illustrates the main parts of the control functions and control systems for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is equipped with an engine 12 as a power source, wheels WH including drive wheels 14 and driven wheels 16, and a power transmission device 18 provided in a power transmission path between the engine 12 and the drive wheels 14. Note that an electric motor may be used as the power source in addition to the engine 12. Furthermore, if the vehicle 10 is an all-wheel drive vehicle, the driven wheels 16 become drive wheels.

[0011] The engine 12 is a known internal combustion engine. The engine torque Te of the engine 12 is controlled by an engine control device 40, which is provided in the vehicle 10 and includes an electronic throttle valve, a fuel injection device, an ignition device, and the like, and is controlled by an electronic control device 90, which will be described later.

[0012] The power transmission device 18 includes an automatic transmission 20, a propeller shaft 24 connected to a transmission output shaft 22, a differential gear 26 connected to the propeller shaft 24, and a pair of drive shafts 28 connected to the differential gear 26. The transmission output shaft 22 is an output rotating member of the automatic transmission 20. The power transmission device 18 also includes a connecting shaft 30 that connects the engine 12 and the automatic transmission 20. The connecting shaft 30 is an input rotating member of the automatic transmission 20.

[0013] The vehicle 10 further includes a wheel brake control device 50. The wheel brake control device 50 includes a brake pedal 52, a brake master cylinder 54, a brake actuator 56, a brake oil passage 58, and a brake device 60. The brake device 60 is provided on each wheel WH, and includes a caliper (not shown) including a brake wheel cylinder 62, brake pads (not shown), and a brake disc (not shown, also synonymous with a brake rotor).

[0014] The brake master cylinder 54 converts the force with which the driver depresses the brake pedal 52 into a master cylinder hydraulic pressure Pmc and transmits it to a brake actuator 56 via a brake oil passage 58. The master cylinder hydraulic pressure Pmc is a hydraulic pressure of a magnitude corresponding to a brake operation amount Bra, which represents the magnitude of the brake pedal 52 depression operation, i.e., the magnitude of the braking operation, corresponding to the force with which the driver depresses the brake pedal 52. The brake actuator 56 supplies a brake hydraulic pressure Pbra to a brake wheel cylinder 62 in accordance with a command from the electronic control device 90. The braking device 60 applies a wheel braking torque Tb to the wheel WH by supplying the brake hydraulic pressure Pbra to the brake wheel cylinder 62.

[0015] Under normal circumstances, the brake actuator 56 supplies the master cylinder hydraulic pressure Pmc generated from the brake master cylinder 54 in response to the driver's brake operation as the brake hydraulic pressure Pbra to the brake wheel cylinders 62. Furthermore, the brake actuator 56 supplies the brake hydraulic pressure Pbra to the brake wheel cylinders 62 as needed, regardless of the driver's brake operation. For example, when automatic brake control is activated, the brake actuator 56 supplies the brake hydraulic pressure Pbra to the brake wheel cylinders 62, the magnitude of which corresponds to the wheel braking torque Tb required for each control. The wheel cylinder hydraulic pressure, which is the hydraulic pressure of the brake wheel cylinders 62, is synonymous with the brake hydraulic pressure Pbra.

[0016] The vehicle 10 further includes an electronic control device 90 as a controller including control devices of the vehicle 10 related to the control of the engine 12, etc. The electronic control device 90 is a vehicle control device mounted on the vehicle 10. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc.

[0017] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the vehicle 10. The various sensors include, for example, an engine rotation speed sensor 70, an input rotation speed sensor 72, an output rotation speed sensor 74, an accelerator opening sensor 76, a brake sensor 78, and a master cylinder hydraulic pressure sensor 80. The various signals include, for example, an engine rotation speed Ne [rpm], an input rotation speed Ni [rpm], an output rotation speed No [rpm], an accelerator opening θacc [%], a brake-on signal Bon, a brake operation amount Bra, and a master cylinder hydraulic pressure Pmc [MPa]. The engine rotation speed Ne is the rotation speed of the engine 12. The input rotation speed Ni is the rotation speed of the connecting shaft 30. The output rotation speed No is the rotation speed of the transmission output shaft 22, which corresponds to the vehicle speed V [km / h]. The accelerator opening θacc is the accelerator operation amount indicating the magnitude of the driver's acceleration operation. The brake-on signal Bon is a signal that indicates a state in which the brake pedal 52 is being operated by the driver.

[0018] The electronic control device 90 outputs various command signals to various devices provided in the vehicle 10. The devices are, for example, the engine control device 40, the brake actuator 56, etc. The various command signals are, for example, an engine control command signal Se, a brake control command signal Sbra, etc. The engine control command signal Se is a command signal for controlling the engine 12. The brake control command signal Sbra is a command signal for controlling the brake hydraulic pressure Pbra, i.e., the wheel braking torque Tb.

[0019] The electronic control unit 90 includes an engine control unit 92 and a brake control unit 94 to realize various controls in the vehicle 10 .

[0020] The engine control unit 92 calculates the required drive torque Tddem at the drive wheels 14, for example, by applying the accelerator opening θacc and the vehicle speed V to a predetermined drive demand map. The engine control unit 92 outputs an engine control command signal Se to control the engine 12 so as to obtain the engine torque Te for realizing the required drive torque Tddem, which is calculated taking into account the gear ratio of the automatic transmission 20 and the like.

[0021] The engine control unit 92 performs idling stop control to temporarily stop operation of the engine 12 when the driver applies the brakes to stop the vehicle 10. In the idling stop control, the engine control unit 92 restarts the engine 12 when, for example, the driver releases the brakes. The idling stop control is stop-and-start control (=S&S control) that temporarily stops the engine 12 when the vehicle 10 comes to a stop, and restarts the engine 12 when the brakes are released.

[0022] For example, the engine control unit 92 performs S&S control when an S&S activation condition is satisfied. Furthermore, if the S&S activation condition is not satisfied while the S&S control is being executed, the engine control unit 92 cancels the S&S control and restarts the engine 12. The S&S activation condition is, for example, when the master cylinder hydraulic pressure Pmc, which reflects the driver's brake operation, exceeds zero [MPa], the vehicle speed V is determined to be zero [km / h] corresponding to a stop, the warm-up of the engine 12 is completed, and the battery condition is good. The battery condition is considered to be good, for example, when the battery voltage is equal to or higher than a predetermined voltage or the remaining charge of the battery is equal to or higher than a predetermined remaining amount. The S&S activation condition may be determined based on the driver's brake pedal 52 depression force or the brake operation amount Bra, instead of the master cylinder hydraulic pressure Pmc.

[0023] The brake control unit 94 controls the brake actuator 56. The brake control unit 94 outputs a brake control command signal Sbra for generating a wheel braking torque Tb corresponding to the brake operation amount Bra. When automatic brake control is activated, the brake control unit 94 outputs the brake control command signal Sbra for generating a wheel braking torque Tb required for each control.

[0024] It is desirable to prevent the vehicle 10 from rolling over while the S&S control is in operation (i.e., while the engine 12 is stopped) and the vehicle 10 from starting to move when the engine 12 is restarted. For this reason, a threshold value equal to or higher than a certain value is set for the master cylinder hydraulic pressure Pmc, which is one of the S&S activation conditions, that is, the master cylinder hydraulic pressure Pmc exceeding zero [MPa]. In other words, the brake control unit 94 performs S&S control when the master cylinder hydraulic pressure Pmc exceeds a predetermined hydraulic pressure Pmcf when the driver applies the brakes and the vehicle 10 is stopped. The predetermined hydraulic pressure Pmcf is set to, for example, a predetermined reference hydraulic pressure Pmcb to ensure a wheel braking torque Tb that does not cause the above-mentioned phenomena.

[0025] Incidentally, to activate the S&S control, the master cylinder hydraulic pressure Pmc must exceed a predetermined hydraulic pressure Pmcf, and the brakes must be applied with a certain amount of pedal force or more. Therefore, if the pedal force on the brake pedal 52 is insufficient, the S&S control cannot be activated. In this case, if the brake pedal 52 is not depressed beyond a certain level, the S&S control may not be activated even when the vehicle speed V reaches zero [km / h]. In other words, if the driver does not apply enough force to the brake pedal 52, the S&S control may not be activated even if the driver intends to stop the vehicle.

[0026] Therefore, the electronic control unit 90 further includes a learning control unit 96 that learns the master cylinder hydraulic pressure Pmc corresponding to the depression force of the brake pedal 52 by the driver when the vehicle is stopped, and corrects the predetermined hydraulic pressure Pmcf of the master cylinder hydraulic pressure Pmc, which is one of the S&S activation conditions, for each driver. Note that when the depression force of the brake pedal 52 or the like is used instead of the master cylinder hydraulic pressure Pmc as the S&S activation condition, the threshold value is learned and corrected based on the depression force of the brake pedal 52 or the like.

[0027] The learning control unit 96 stores the master cylinder hydraulic pressure Pmc when the vehicle 10 is stopped after a brake operation, and corrects the predetermined hydraulic pressure Pmcf based on the stored master cylinder hydraulic pressure Pmc. For example, the learning control unit 96 stores the master cylinder hydraulic pressure Pmc when the vehicle 10 is stopped after a brake operation in the storage device 98 of the electronic control device 90 every time the vehicle 10 stops. The learning control unit 96 calculates an average value of the master cylinder hydraulic pressures Pmc stored in the storage device 98 as a learned value Vln and stores the learned value Vln in the storage device 98. When the vehicle 10 is stopped after a brake operation, the learning control unit 96 updates the predetermined hydraulic pressure Pmcf based on the most recent learned value Vln stored up to the previous time.

[0028] An example of a method for updating the predetermined hydraulic pressure Pmcf will be described below. The predetermined hydraulic pressure Pmcf is initially set to the reference hydraulic pressure Pmcb. If the learned value Vln is the same as the current predetermined hydraulic pressure Pmcf, the current predetermined hydraulic pressure Pmcf is maintained. If the learned value Vln is smaller than the current predetermined hydraulic pressure Pmcf, the predetermined hydraulic pressure Pmcf is updated to the learned value Vln, or to a value that is smaller than the current predetermined hydraulic pressure Pmcf by a predetermined value, provided that the predetermined hydraulic pressure Pmcf does not fall below the learned value Vln. On the other hand, if the learned value Vln is greater than the current predetermined hydraulic pressure Pmcf, the predetermined hydraulic pressure Pmcf is updated to the learned value Vln, provided that the predetermined hydraulic pressure Pmcf does not exceed the reference hydraulic pressure Pmcb, or to a value that is larger than the current predetermined hydraulic pressure Pmcf by a predetermined value, provided that the predetermined hydraulic pressure Pmcf does not exceed the reference hydraulic pressure Pmcb.

[0029] If the predetermined hydraulic pressure Pmcf is set lower than the reference hydraulic pressure Pmcb, the vehicle 10 may slip down or other such phenomena described above may occur during the operation of the S&S control. Therefore, the brake control unit 94 increases the wheel cylinder hydraulic pressure, i.e., the brake hydraulic pressure Pbra, to prevent the above-mentioned phenomena during the S&S control.

[0030] When S&S control is performed, the brake control unit 94 increases the brake hydraulic pressure Pbra, which is set to the master cylinder hydraulic pressure Pmc, by the brake actuator 56. For example, when the predetermined hydraulic pressure Pmcf is set to be smaller than the reference hydraulic pressure Pmcb, the brake control unit 94 increases the brake hydraulic pressure Pbra by the hydraulic pressure that is insufficient between the master cylinder hydraulic pressure Pmc and the reference hydraulic pressure Pmcb.

[0031] 2 and 3 are flowcharts each illustrating the main parts of the control operation of the electronic control device 90, and are flowcharts illustrating the control operation for appropriately operating the S&S control in response to each driver, and are executed, for example, repeatedly.

[0032] 2, first, in step S10 (hereinafter, the term "step" will be omitted) corresponding to the function of the engine control unit 92, it is determined whether or not the S&S operation conditions (the state of the engine 12 and the battery) other than the master cylinder oil pressure Pmc and the vehicle speed V are satisfied. If the determination in S10 is negative, the routine is terminated. If the determination in S10 is positive, it is determined in S20 corresponding to the function of the engine control unit 92 whether or not the master cylinder oil pressure Pmc exceeds zero [MPa]. If the determination in S20 is negative, the routine is terminated. If the determination in S20 is positive, it is determined in S30 corresponding to the function of the engine control unit 92 whether or not the vehicle speed V is zero [km / h]. If the determination in S30 is negative, the routine is terminated. If the determination in S30 is positive, the master cylinder oil pressure Pmc is stored in S40 corresponding to the function of the learning control unit 96. Next, in S50, which corresponds to the function of the learning control unit 96, the average value of the stored master cylinder oil pressures Pmc is calculated as a learned value Vln. Next, in S60, which corresponds to the function of the learning control unit 96, the learned value Vln is stored.

[0033] The flowchart of FIG. 3 is executed in parallel with the flowchart of FIG. 2. S10-S30 in the flowchart of FIG. 3 are the same as S10-S30 in the flowchart of FIG. 2, and therefore description thereof will be omitted. In FIG. 3, if the determination in S30 is affirmative, in S110, which corresponds to the function of the learning control unit 96, the predetermined hydraulic pressure Pmcf is updated based on the previous learned value Vln. Next, in S120, which corresponds to the function of the engine control unit 92, it is determined whether the master cylinder hydraulic pressure Pmc exceeds the updated predetermined hydraulic pressure Pmcf. If the determination in S120 is negative, this routine is terminated. If the determination in S120 is affirmative, in S130, which corresponds to the function of the brake control unit 94, the wheel cylinder hydraulic pressure, i.e., the brake hydraulic pressure Pbra, is increased. Next, in S140, which corresponds to the function of the engine control unit 92, the engine 12 is stopped by S&S control.

[0034] As described above, according to this embodiment, when the brakes are applied to stop the vehicle 10, the S&S control is more likely to be activated in accordance with the brake operation amount Bra by the driver. In addition, the vehicle 10 is prevented from rolling down while the engine 12 is stopped, and from starting to move when the engine is restarted.

[0035] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0036] 10: Vehicle 12: Engine 54: Brake master cylinder 56: Brake actuator 62: Brake wheel cylinder 90: Electronic control unit (vehicle control unit) WH: Wheel

Claims

[Claim 1] A vehicle control device is mounted on a vehicle including an engine, and a brake actuator that supplies master cylinder hydraulic pressure generated from a brake master cylinder in response to a brake operation by a driver to brake wheel cylinders provided on each wheel as brake hydraulic pressure, and that supplies the brake hydraulic pressure to the brake wheel cylinders as needed regardless of the brake operation, and that performs idling stop control to temporarily stop operation of the engine when the vehicle is stopped due to the brake operation, The idling stop control is performed when the master cylinder hydraulic pressure exceeds a predetermined hydraulic pressure when the vehicle is stopped due to the brake operation, a control device for a vehicle, characterized in that the master cylinder oil pressure when the vehicle is stopped after the brake operation is performed is stored, the predetermined oil pressure is corrected based on the stored master cylinder oil pressure, and when performing the idling stop control, the brake oil pressure that is set to the master cylinder oil pressure is increased by the brake actuator.

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