JP3799934B2 - Vehicle deceleration control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle deceleration control device, and more particularly to a vehicle deceleration control device that applies deceleration when an accelerator operation amount is a predetermined amount or less.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been proposed a deceleration control device that applies a deceleration to a vehicle by operating a braking force when a driver releases the depression of an accelerator pedal. The technique disclosed in Japanese Patent Application Laid-Open No. 9-95222 is one of them. When the accelerator pedal is in the deceleration range, a braking force is applied to the main brake system via the deceleration control device. is there.
[0003]
It is described that by adding such a deceleration control device, it is not necessary to frequently operate the brake pedal when accelerating and decelerating the vehicle gently, so that deceleration response can be improved and easy driving can be realized. .
[0004]
[Problems to be solved by the invention]
However, in the above technology, when the driver performs an operation of depressing the accelerator pedal by releasing his / her foot from the brake pedal in order to accelerate from the brake operation state, the brake pedal is returned until the accelerator pedal is actually depressed by both predetermined amounts. Since the braking force is applied by the deceleration control device while the vehicle is in the deceleration range, a deceleration force unintended by the driver may act, and the operation may feel uncomfortable.
[0005]
In view of the above problems, an object of the present invention is to provide a vehicle deceleration control device that can be operated without a driver feeling uncomfortable when switching from a deceleration state to an acceleration state.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, a vehicle deceleration control device according to the present invention includes a brake operation state determination unit that determines a brake operation state of a driver, an accelerator operation state determination unit that determines a driver's accelerator operation state, and The deceleration adding means for adding deceleration to the vehicle and the determination result by the brake operation state determining means are in the non-operating state, and the accelerator operation amount determined by the accelerator operating state determining means is smaller than a predetermined value. And a control unit for controlling the deceleration adding means to add a predetermined deceleration to the vehicle, in which the control unit operates the brake operation determination result by the brake operation state determination means. after migrating from the state to the non-operation state for a predetermined period limits the predetermined deceleration added by deceleration adding means, after a predetermined period of time is with a predetermined deceleration Characterized in that it.
[0007]
According to the vehicle deceleration control device of the present invention, for example, when the driver performs an operation of returning the brake pedal from a state where the brake pedal is depressed, the accelerator operation amount is predetermined for a predetermined period after the brake pedal is returned. Even if the value is smaller than the value, the deceleration applied by the deceleration adding means is limited more than usual. Deceleration when shifting from the deceleration state to the acceleration state by setting this predetermined period slightly longer than the period required for the driver to depress the accelerator pedal after releasing the brake pedal when shifting from the deceleration state to the acceleration state It is possible to smoothly shift from the deceleration state to the acceleration state while suppressing the addition.
[0008]
Alternatively, the control unit of the vehicle deceleration control device according to the present invention, after the brake operation determination result by the brake operation state determination means shifts from the operation state to the non-operation state, the accelerator operation amount once exceeds a predetermined value. The predetermined deceleration applied by the deceleration adding means is limited until the time until the accelerator operation amount shifts again from a state where the accelerator operation amount is greater than or equal to the predetermined value to a state smaller than the predetermined value , and the deceleration is added by the deceleration adding means. When the above condition is satisfied, a predetermined deceleration is added by the deceleration adding means.
[0009]
In this case, the deceleration applied by the deceleration adding means is limited until the accelerator operation amount exceeds a predetermined value, that is, until the acceleration operation is performed once. Therefore, it is possible to suppress the addition of deceleration when shifting from the acceleration state to the acceleration state and smoothly shift from the deceleration state to the acceleration state.
[0010]
It is preferable that the vehicle further includes a downhill determination unit, and when the downhill road determination unit determines that the downhill road is a downhill road, it is preferable to perform control for suppressing the restriction of the deceleration. On a downhill road, the vehicle shifts to an acceleration state due to gravity acting on the vehicle just by releasing the brake. Therefore, if the addition of deceleration is suppressed, there is a possibility that acceleration unintended by the driver may occur. Therefore, on the downhill road, the limitation of the deceleration is suppressed, and the acceleration / deceleration as intended by the driver is enabled by adding the predetermined deceleration.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same reference numerals are given to the same components in the drawings as much as possible, and duplicate descriptions are omitted.
[0012]
FIG. 1 is a diagram showing a configuration of a vehicle deceleration control device according to the present invention, and FIG. 2 is a diagram showing a configuration of a braking system of a vehicle equipped with the control device.
[0013]
First, the configuration of the braking system of the vehicle will be described with reference to FIG. This vehicle is provided with wheel brake wheel cylinders 25 to 28 on front wheels FR and FL and rear wheels RR and RL, respectively, so that the vehicle is braked.
[0014]
A brake pedal 10 for operating this braking system is connected to the piston shaft of the master cylinder 11. A brake pressure sensor that detects an operation state of the brake pedal is connected to the brake pedal 10. A stroke simulator 15 is further connected to the master cylinder 11 on the side opposite to the brake pedal 10 to generate an appropriate repulsive force in response to the operation of the brake pedal 10.
[0015]
The two hydraulic fluid lines extending from the master cylinder 11 are connected to the wheel cylinders 25 and 26 of the right front wheel FR and the left front wheel FL via solenoid valves 12 and 13, respectively. A master pressure sensor 38 (39) is disposed on the path from the master cylinder 11 to the solenoid valve 12 (13).
[0016]
On the other hand, the hydraulic fluid line extending from the reservoir tank 16 is connected to a pump 17 driven by a motor 18, and the hydraulic fluid line extending from the pump 17 is connected to the wheel cylinders 25 to 28 of each wheel via the linear valves 21a to 24a. Connected to. A brake pressure sensor 31 and an accumulator 19 are disposed between the pump 17 and a branching portion to each of the linear valves 21a to 24a. Further, pressure reducing valves 21b to 24b are connected to the hydraulic fluid lines returning from the respective wheel cylinders 25 to 28 to the reservoir tank 16. Foil cylinder pressure sensors 32 to 35 are attached to the wheel cylinders 25 to 28, respectively.
[0017]
The deceleration control unit 100 which also serves as the control unit of the vehicle deceleration control device according to the present invention, the accelerator operation state determination unit, and the brake operation state determination unit includes an accelerator opening sensor 42, a brake stroke sensor 40, a vehicle speed sensor 44, Output signals of the engine speed sensor 46, the wheel cylinder pressure sensors 32-35, the brake pressure sensor 31, and the master pressure sensors 38, 39 are supplied.
[0018]
Further, the deceleration control unit 100 has a memory unit 120 for storing tables and constants used in deceleration control, and linear valves 21a to 24a and pressure reducing valves connected to the respective wheel cylinders 25 to 28. 21b-24b and solenoid valves 12 and 13 are controlled respectively.
[0019]
Here, a basic operation at the time of braking of the braking system will be described. When the brake pedal 10 is depressed, the piston shaft of the master cylinder 11 is pushed and a hydraulic pressure (master pressure) corresponding to the operation amount is generated. Under normal conditions, the solenoid valves 12 and 13 are in a shut-off state, and the master pressure is not directly transmitted to the wheel cylinder 25 of the right front wheel FR and the wheel cylinder 26 of the left front wheel FL. The hydraulic fluid sent from the reservoir tank 16 in accordance with the operation amount of the master cylinder 11 is boosted by a pump 17 and an accumulator 19 driven by a motor 18, and then the wheel cylinder 25 of the right front wheel FR via an FR linear valve 21a. Further, the wheel cylinder 26 of the left front wheel FL via the FL linear valve 22a, the wheel cylinder 27 of the right rear wheel RR via the RR linear valve 23a, and the wheel cylinder 28 of the left rear wheel RL via the RL linear valve 24a. Are supplied in parallel. At this time, the hydraulic pressure (wheel cylinder pressure) of each wheel cylinder 25-28 can be adjusted independently by controlling each linear valve 21a-24a by the deceleration control unit 100 independently. In this way, the braking force applied to each wheel can be controlled independently. The hydraulic fluid is returned to the reservoir tank 16 via the pressure reducing valves 21b to 24b connected to the wheel cylinders 25 to 28.
[0020]
When the braking system is abnormal, the solenoid valves 12 and 13 are turned on, and the master pressure of the master cylinder 11 is passed through the solenoid valves 12 and 13 to the wheel cylinder 25 of the right front wheel FR and the wheel cylinder 26 of the left front wheel FL, respectively. This is transmitted to brake both front wheels FR and FL.
[0021]
The deceleration control device according to the present invention further assists an engine braking effect that is often lacking in a vehicle equipped with an automatic transmission by adding a braking force to generate a deceleration force when the depressed accelerator pedal is returned. Perform deceleration control. Hereinafter, this is referred to as engine brake assist (EBA) control.
[0022]
Specifically, the deceleration control unit 100 includes an output signal of an accelerator opening sensor 42 attached to the accelerator pedal 50, a vehicle speed signal obtained from the vehicle speed sensor 44, and a brake pedal opening obtained from the brake stroke sensor 40. Each of the signals and the master pressure signals obtained from the master pressure sensors 38 and 39 are monitored. The driver sets the EBA control to an on state by a switch (not shown), the accelerator pedal opening is not more than θ ₀ (for example, 5 degrees), the vehicle speed is not less than a predetermined speed (for example, 15 km / h), and the brake When the pedal opening is 0 and the master pressure is a predetermined pressure (for example, 0.75 MPa) or less, the EBA control permission condition is satisfied and the EBA control state is set, and the EBA control signal is set to ON.
[0023]
When the accelerator pedal that has been depressed is returned, an engine control unit (not shown) reduces the supply of fuel and air to reduce the engine speed, and this resistance causes an engine braking effect in which a braking force is generated. At this time, when the above-described EBA control signal is switched from OFF to ON, the deceleration control unit 100 controls the linear valves 21a to 24a and the pressure reducing valves 21b to 24b to act on the wheel cylinders 25 to 28 of the wheels. The vehicle is decelerated by adjusting the hydraulic pressure and applying a predetermined braking force (assist braking force). Further, in the middle and high speed range, when the accelerator pedal is returned from the fuel cutoff position to the fully closed position, the engine control unit cuts off the fuel supply to the engine to obtain a larger deceleration force.
[0024]
In the conventional deceleration control device, EBA control is activated until the driver depresses the brake pedal and depresses the accelerator pedal to shift from the deceleration state to the acceleration state. Deceleration force sometimes occurred. In the present invention, in order to prevent such an unintended deceleration force from occurring, the following deceleration control is performed.
[0025]
FIG. 4 is a flowchart showing the first deceleration control mode, and FIG. 5 is a diagram showing the relationship of the time change of the brake pedal opening, the accelerator pedal opening, the EBA control signal, and the EBA control hydraulic pressure when this control is executed. It is.
[0026]
First, the basic flow of control will be described with reference to FIG. In step S1, it is determined whether or not the state of the vehicle satisfies the EBA control permission condition described above, that is, whether or not the aforementioned EBA control signal is on. If the permission condition is not satisfied, the process is terminated without performing control. When the condition is satisfied, the process proceeds to step S2, and it is determined whether or not a predetermined time (for example, 1 second) or more has elapsed after the brake pedal opening becomes zero. The time required for the time of transition from the deceleration to acceleration and release the brake pedal until depressing the accelerator pedal to the accelerator opening theta ₀ or is less than 1 second in the majority of the driver, the more periods EBA control conditions If this is the case, it can be estimated that it is not during the transition from deceleration to acceleration. Therefore, if the condition is satisfied, the process proceeds to step S3 to perform EBA control, and the assist braking force is applied to decelerate the vehicle.
[0027]
If the predetermined time has not elapsed since the release of the brake pedal, it is determined in step S4 whether the current traveling is a downhill road or a mountain road. The determination of the downhill road can be made by determination of acceleration in the vehicle longitudinal direction by the G sensor or determination based on the difference between the actual acceleration and the estimated acceleration estimated from the conditions of the engine and drive system. Whether it is a mountain road or not can be determined by determining a change in rudder angle or a change in acceleration in the lateral direction of the vehicle using a G sensor.
[0028]
If it is determined that the road is not a downhill road or a mountain road, the process ends without performing EBA control. As a result, EBA control is not performed when the pedal is switched, and assist braking force not intended by the driver is not generated.
[0029]
On the other hand, when it is determined that the road is a downhill road and a mountain road, even if a predetermined time has not elapsed since the release of the brake pedal, the process proceeds to step S3 to execute the EBA control. In the case of a downhill road and a mountain road, the vehicle is accelerated by the influence of gravity acting on the vehicle just by releasing the brake pedal. Furthermore, since frequent braking and accelerator operations are often required to safely pass the curve, it is preferable to increase the engine braking effect by EBA control.
[0030]
Next, a control example will be described with reference to FIG. As shown in FIG. 5A, it is assumed that the opening degree is set to ₀ at time t ₀ by operating the brake pedal. At this time, as shown in FIG. 5B, assuming that the accelerator pedal is not depressed until time t ₁ and further that the accelerator opening θ _{0 is} actually depressed at time t ₂ , the conventional deceleration force control is performed. In the apparatus, the EBA control signal is turned on from time t ₀ to t ₂ as shown by a broken line in FIG. 5C, and the EBA control oil pressure changes as shown in FIG. 5D. The assist braking force is generated from time t ₀ to t ₂ (actually, the time required for lowering the hydraulic pressure further later), and the deceleration force not intended by the driver is applied.
[0031]
In this control mode, even if the EBA permission condition is satisfied, the EBA control signal is not turned on between time t ₀ and time t ₃ when a predetermined time Δt has elapsed. Therefore, only when the EBA permission condition is satisfied from time t ₀ to time t ₃ , the EBA control signal is turned on at time t ₃ as indicated by a dashed line in FIG. 5C. After that, the EBA control hydraulic pressure increases, and an assist braking force is applied, and a deceleration force is applied to the vehicle. In FIG. 5B, when the accelerator pedal is depressed more than the accelerator opening θ ₀ between time t ₀ and time t ₃ , the EBA permission condition is satisfied for a predetermined time or more after the brake pedal is released. Therefore, the EBA control signal remains off. In this case, the assist braking force is not applied. Therefore, when the driver switches from the brake pedal to the accelerator pedal to shift from the deceleration state to the acceleration state, the transition from the smooth deceleration to the acceleration is performed without generating an excessive assist braking force. .
[0032]
Next, a second control mode of the deceleration control device according to the present invention will be described. FIG. 6 is a flowchart showing the second deceleration control mode, and FIG. 7 shows the time change of the brake pedal opening, the accelerator pedal opening, the θ flag, the EBA control signal, and the EBA control oil pressure when the control is executed. It is a figure which shows a relationship.
[0033]
First, the basic flow of control will be described with reference to FIG. In step S11, it is determined whether or not the vehicle state satisfies conditions other than the accelerator opening condition among the above-described EBA control permission conditions. If the condition is satisfied, the process proceeds to step S12 to determine whether the accelerator opening condition is satisfied. If this condition is also satisfied, it is further determined whether or not the variable θ flag stored in the memory unit is on. This θ flag is turned on if the accelerator pedal opening has exceeded θ ₀ while the EBA permission conditions other than the accelerator pedal opening condition are satisfied after all EBA permission conditions are satisfied. In other cases, the variable is set to off. If this variable is ON, the process proceeds to step S14 and EBA control is performed.
[0034]
If at least one EBA permission condition other than the accelerator pedal opening condition is not satisfied in step S11, the process proceeds to step S15, and after the variable θ flag is set to OFF, the process is performed without performing EBA control. finish. When the accelerator pedal opening condition is satisfied in step S12 (when all other EBA permission conditions are satisfied), the process proceeds to step S16, the variable θ flag is set to ON, and EBA control is performed. The process is terminated without performing the process. On the other hand, if the variable θ flag is off in step S13, the process proceeds to step S17, and the downhill road and mountain road determination is performed in the same manner as in step S4 of the first control mode. If it is determined, the process proceeds to step S14 to forcibly perform EBA control. In other cases, the process ends without performing EBA control.
[0035]
By controlling in this way, when the brake pedal is switched to the accelerator pedal, etc., the variable θ flag is off, so the EBA control is not performed, and the deceleration force not intended by the driver is not applied. On the other hand, since the EBA control is performed when the depressed accelerator pedal is returned or on a mountain road and a downhill road, the assist braking force can be reliably generated when the driver wants to decelerate.
[0036]
Next, a control example will be described with reference to FIG. Assume that the brake pedal and the accelerator pedal are operated as shown in FIGS. 7 (a) and 7 (b), respectively. At time t _a , the brake pedal is released and the EBA control permission condition is satisfied, but at this point in time, as shown in FIG. 7C, the θ flag is off, so as shown in FIG. 7D. In addition, the EBA control signal remains off, the EBA control hydraulic pressure does not increase as shown in FIG. 7E, and no assist braking force is applied.
[0037]
The θ flag is turned on only when the accelerator pedal is depressed from time t _b and the accelerator opening exceeds θ ₀ at time t _c . At this time, since the accelerator opening condition does not satisfy the EBA control condition, the EBA control signal remains off as shown in FIG. 7 (d), and the EBA control hydraulic pressure as shown in FIG. 7 (e). And the assist braking force is not applied. For this reason, the transition from smooth deceleration to acceleration is performed from time t _a to t _d .
[0038]
After that, the accelerator pedal is returned and the EBA control permission condition is satisfied again at time t _d when the accelerator opening again becomes θ ₀ or less, so the EBA control signal is turned on as shown in FIG. As shown in FIG. 7E, the EBA control oil pressure is increased, assist braking force is applied, and the vehicle is decelerated.
[0039]
When the brake pedal at time t _e is operated, theta flag while being set off as shown in FIG. 7 (c), it is switched off as EBA control signal is also shown in FIG. 7 (d) As a result, the EBA control hydraulic pressure is also reduced as shown in FIG. 7E, and the application of the assist braking force is stopped.
[0040]
In the above control mode, in the case of a downhill road and a mountain road, an example of executing EBA control immediately after releasing the brake pedal has been explained, but as long as the downhill road condition is satisfied, immediately after releasing the brake pedal. EBA control may be performed.
[0041]
In the above description, the embodiment in which the braking system is directly controlled to apply the deceleration force has been described. However, a configuration in which the deceleration force is applied to the drive system may be employed.
[0042]
【The invention's effect】
As described above, according to the present invention, after the brake operation shifts from the operating state to the non-operating state, the deceleration is applied for a predetermined period or until the accelerator operation amount becomes a predetermined value or more. Therefore, when the driver switches from the brake pedal to the accelerator pedal, it is possible to prevent a deceleration force not intended by the driver from being generated, and to achieve a smooth transition from deceleration to acceleration.
[0043]
Furthermore, if it is determined that the road is downhill, by suppressing this restriction, it is possible to suppress the generation of unintended acceleration force on the downhill road, and to meet the driver's intention without frequent operation of the accelerator and brake. Acceleration / deceleration is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a vehicle deceleration control apparatus according to the present invention.
FIG. 2 is a diagram showing a configuration of a braking system of a vehicle equipped with a vehicle deceleration control device according to the present invention.
FIG. 3 is a diagram for explaining an accelerator pedal opening degree;
FIG. 4 is a flowchart of a first control mode of the vehicle deceleration control device according to the present invention.
FIG. 5 is a diagram showing the relationship of changes over time in brake pedal opening, accelerator pedal opening, EBA control signal, and EBA control oil pressure during execution of the control in FIG. 4;
FIG. 6 is a flowchart of a second control mode of the vehicle deceleration control device according to the present invention.
FIG. 7 is a diagram showing the relationship of changes over time in the brake pedal opening, the accelerator pedal opening, the θ flag, the EBA control signal, and the EBA control hydraulic pressure when the control shown in FIG. 6 is executed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Brake pedal, 11 ... Master cylinder, 16 ... Reservoir tank, 17 ... Pump, 19 ... Accumulator, 21a-24a ... Linear valve, 21b-24b ... Pressure reducing valve, 25-28 ... Wheel cylinder, 31 ... Brake pressure sensor, 32-35 ... Wheel cylinder pressure sensor, 42 ... Accelerator opening sensor, 50 ... Accelerator pedal, 100 ... Deceleration force control unit, 120 ... Memory unit.

Claims (3)

Brake operation state determination means for determining the brake operation state of the driver;
An accelerator operation state determination means for determining the driver's accelerator operation state;
Deceleration adding means for adding deceleration to the vehicle;
When the determination result by the brake operation state determination unit is a non-operation state and the accelerator operation amount determined by the accelerator operation state determination unit is smaller than a predetermined value, the deceleration addition unit is controlled to control the vehicle. A vehicle deceleration control device comprising: a control unit that adds a predetermined deceleration;
The control unit, after the brake operation determination result by the brake operation state determination means shifts from the operation state to the non-operation state, at least a predetermined period expected to be required until the accelerator operation amount reaches the predetermined value , The vehicle deceleration control device for limiting the predetermined deceleration to be applied even when the condition for adding the deceleration by the deceleration adding means is satisfied, and adding the predetermined deceleration after a predetermined period has elapsed. . Brake operation state determination means for determining the brake operation state of the driver;
An accelerator operation state determination means for determining the driver's accelerator operation state;
Deceleration adding means for adding deceleration to the vehicle;
When the determination result by the brake operation state determination unit is a non-operation state and the accelerator operation amount determined by the accelerator operation state determination unit is smaller than a predetermined value, the deceleration addition unit is controlled to control the vehicle. A vehicle deceleration control device comprising: a control unit that adds a predetermined deceleration;
The control unit includes the deceleration adding unit until the accelerator operation amount once exceeds the predetermined value after the brake operation determination result by the brake operation state determination unit shifts from the operation state to the non-operation state. The above-mentioned condition for adding the deceleration by the deceleration adding means after the accelerator operation amount is changed again from the state above the predetermined value to the state smaller than the predetermined value is established. And a deceleration control device for a vehicle that adds the predetermined deceleration by the deceleration addition means.   3. The vehicle according to claim 1, further comprising a downhill road determination unit, wherein when the downhill road determination unit determines that the downhill road is a downhill road, control for suppressing the deceleration restriction is performed. Deceleration control device.

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