JPH10297461A - Skin hanging seat for tow-wheeled vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a braking distance from being increased in the situation that a vehicle should be urgently stopped by prohibiting the decrease of the braking force by a stop shock mitigating/regulating means when an obstacle is detected within the prescribed distance in the front of the vehicle. SOLUTION: The distance to an obstacle in the front of a vehicle is detected by an obstacle detecting unit 70. When an electronic control unit(ECU) 30 detects that the obstacle exists within the prescribed distance in the front of the vehicle based on the detection signal from the obstacle detecting unit 70, it turns on holding solenoids 38, 40 (to close valves) and turns on decompression solenoids 60, 62 (to open valves), it cuts off wheel cylinders 42, 44 from a master cylinder 20, and it communicates them with a reservoir 54. The brake fluid in the wheel cylinders 42, 44 flows out to the brake reservoir 54, and the wheel cylinder pressure is decreased to mitigate the braking force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a braking force control device, and more particularly to a braking force control device suitable for reducing a stop shock of a vehicle.

[0002]

2. Description of the Related Art When a vehicle stops with a brake pedal depressed, a shock (hereinafter referred to as a stop shock) acts on the vehicle due to discontinuous deceleration at the moment the vehicle stops. I do. To alleviate the stop shock, the driver needs to relax the brake operation immediately before the stop. However, performing such a brake operation imposes a burden on the driver when it is necessary to perform the brake operation frequently, such as when driving on a congested road, or when an inexperienced driver drives. become.

A configuration disclosed in, for example, Japanese Patent Application Laid-Open No. 4-151357 is known as a braking force control device capable of alleviating a stop shock without a driver relaxing brake operation. The above-described conventional braking force control device has a function of executing a stop shock mitigation control for reducing a stop shock by automatically reducing the braking force immediately before the vehicle stops. Therefore, according to the above-described conventional braking force control device, the stop shock can be reduced without imposing a burden on the driver.

[0004] When the braking force is reduced to mitigate the stopping shock, the braking distance increases. For this reason, in a situation where a sudden braking operation is being performed, priority should be given to shortening the braking distance rather than alleviating the stopping shock. Therefore, the above-described conventional braking force control device determines whether or not a sudden braking operation is being performed based on the braking operation speed. The execution of the control is prohibited.

[0005]

By the way, even if there is an obstacle in front of the vehicle and the vehicle should be stopped urgently, the obstacle may appear suddenly or the driver may not be able to stop. Due to caution, sudden braking may not be performed. However, as described above, in the conventional braking force control device, the execution of the stop shock mitigation control is prohibited based on the brake operation speed by the driver. For this reason, according to the conventional braking force control device described above, when the sudden braking operation is not performed, the stop shock mitigation control cannot be prohibited even if an obstacle exists in front of the vehicle, The braking distance increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and when an obstacle appears in front of the vehicle, regardless of whether or not a sudden braking operation is performed, the vehicle shock prevention control is performed. An object of the present invention is to provide a braking force control device capable of reliably preventing an increase in a braking distance in a situation where a vehicle is to be stopped urgently by prohibiting the execution.

[0007]

The above object is achieved by the present invention.
As described in the above, braking force generating means for generating a braking force according to the amount of brake operation, stopping shock relaxation control means for automatically reducing the braking force generated by the braking force generating means immediately before the vehicle stops, Obstacle detection means for detecting whether an obstacle is present within a predetermined distance in front of the vehicle, and prohibiting the operation of the stop shock mitigation control means when the obstacle detection means detects an obstacle. And a control prohibition unit.

In the present invention, if the braking force is reduced immediately before the vehicle stops by the stopping shock mitigation control means, the braking distance increases. The control prohibiting means prohibits the operation of the stopping shock mitigation means when the obstacle detecting means detects an obstacle within a predetermined distance in front of the vehicle. Therefore, according to the present invention, when an obstacle is present within a predetermined distance ahead of the vehicle, the braking distance is prevented from increasing.

The above object is achieved by a braking force generating means for generating a braking force according to a brake operation amount, and a braking force generated by the braking force generating means immediately before the vehicle stops. Stopping shock mitigation control means for automatically reducing the distance, obstacle detection means for detecting a distance to an obstacle in front of the vehicle, and stopping based on the distance to the obstacle detected by the obstacle detection means. The present invention is also achieved by a braking force control device including a reduction rate control means for changing a reduction rate of the braking force by the shock relaxation control means.

In the present invention, the reduction rate control means changes the reduction rate of the braking force by the stop shock mitigation control means based on the distance to the obstacle ahead of the vehicle. When the rate of decrease of the braking force changes, the braking distance and the degree of mitigation of the stop shock change. Therefore, according to the present invention, while the required braking distance according to the distance to the obstacle is realized,
The effect of alleviating the stop shock according to the reduction rate of the braking force can be obtained.

[0011]

FIG. 1 is a system configuration diagram of a braking force control device according to an embodiment of the present invention. As shown in FIG. 1, the braking force control device of the present embodiment
It has. A brake pedal 24 is connected to the master cylinder 20 via a brake booster 22.
The pedal depression force applied to the brake pedal 24 is boosted by the brake booster 22 and transmitted to the master cylinder 20. Two liquid chambers 20 provided in master cylinder 20
Liquid pressures (hereinafter, referred to as master cylinder pressures PM _{/ C} ) corresponding to the pedaling force are generated at a and 20b, respectively.

Liquid chambers 20a and 20b of master cylinder 20
Is connected to an ABS actuator 28 via hydraulic passages 26 and 27. The ABS actuator 28 is controlled by an electronic control unit 30 (hereinafter, referred to as ECU 30). The hydraulic pressure passage 27 is provided with a hydraulic pressure sensor 32 for detecting the master cylinder pressure PM _{/ C.} The output signal of the hydraulic pressure sensor 32 is supplied to the ECU 30. The ECU 30 detects the master cylinder pressure PM _{/ C} based on the output signal of the hydraulic pressure sensor 32.

The ABS actuator 28 is connected to the hydraulic passage 2.
6 are provided with main hydraulic pressure passages 34 and 36 communicating with the main hydraulic pressure passage 6. Main hydraulic passages 34 and 36 have holding solenoids 38 and
40 are provided. The holding solenoids 38 and 40 are both normally open electromagnetic open / close valves, and are closed when an ON signal is given from the ECU 30. Main hydraulic passages 34, 3
Numeral 6 communicates with wheel cylinder passages 46 and 48 leading to wheel cylinders 42 and 44 on the downstream side of the holding solenoids 38 and 40, respectively. Wheel cylinder 42,
The wheels 44 are provided corresponding to the wheels 50 and 52, respectively, and generate a braking force according to the internal fluid pressure (hereinafter, referred to as wheel cylinder pressure P _{W / C} ). The wheel cylinder passages 46, 48 are also provided with a pressure reducing passage 5 leading to a reservoir 54.
6, 58 are in communication. Pressure reducing solenoids 60 and 62 are disposed in the pressure reducing passages 56 and 58, respectively.
Each of the pressure reducing solenoids 60 and 62 is a normally closed electromagnetic opening / closing valve, and is opened when an ON signal is given from the ECU 30.

The suction port of a pump 64 communicates with the reservoir 54. The discharge port of the pump 64 communicates with the main hydraulic passages 34, 36 on the upstream side of the holding solenoids 38, 40. The pump 64 pumps the brake fluid stored in the reservoir 54 into the main hydraulic passages 34 and 36.
Wheels 50 and 52 have wheel speed sensors 66 and 6 respectively.
8 are provided. The wheel speed sensors 66 and 68 are sensors that generate a pulse wave each time the wheels 50 and 52 rotate by a predetermined angle, and output signals thereof are supplied to the ECU 30. The ECU 30 has wheel speed sensors 66 and 68
The wheel speeds of the wheels 50 and 52 are detected based on the output signals of the above.

Although FIG. 1 shows only a system of the ABS actuator 28 corresponding to the liquid chamber 20a of the master cylinder 20, the ABS actuator 28
The system corresponding to the liquid chamber 20b of the master cylinder 20 has the same configuration as the system corresponding to the liquid chamber 20a. An obstacle detection unit 70 is connected to the ECU 30. The obstacle detection unit 70 includes, for example,
Transmits light, electromagnetic waves or ultrasonic waves toward the front of the vehicle,
The distance to an obstacle ahead of the vehicle is detected based on the reflected wave. The ECU 30 detects whether or not an obstacle exists in front of the vehicle based on an output signal of the obstacle detection unit 70 and, if so, detects a distance to the obstacle. The ECU 30 is connected to a deceleration sensor 72 for detecting the deceleration of the vehicle. The ECU 30
The deceleration of the vehicle is detected based on the output signal of the deceleration sensor 72.

Next, the operation of the braking force control device shown in FIG. 1 will be described. When the holding solenoids 38 and 40 are turned off (opened) and the pressure reducing solenoids 60 and 62 are turned off (closed) (the state shown in FIG. 1), the wheel cylinder 4 is turned off.
The communication between the wheel cylinders 42 and 44 and the reservoir 54 is cut off while the communication between the master cylinder 20 and the wheel cylinders 44 is performed. Hereinafter, this state is referred to as a normal brake state.
In the normal brake state, the brake fluid having the same hydraulic pressure as the master cylinder pressure P _{M / C} is guided to the wheel cylinders 42 and 44, so that a braking force corresponding to the pedal depression force applied to the brake pedal 24 is generated.

On the other hand, when the holding solenoids 38 and 40 are turned on (closed) and the pressure reducing solenoids 60 and 62 are turned on (opened), the communication between the wheel cylinders 42 and 44 and the master cylinder 20 is cut off. At the same time, the wheel cylinders 42 and 44 communicate with the reservoir 54. This state is hereinafter referred to as a decompression mode. In decompression mode,
When the brake fluid in the wheel cylinders 42, 44 flows out to the reservoir 54, the wheel cylinders 42, 44
The wheel cylinder pressure P _{W / C} of 44 is quickly reduced.

When the holding solenoids 38 and 40 are turned on (closed valve) and the pressure reducing solenoids 60 and 62 are turned off (closed valve), the communication between the wheel cylinders 42 and 44 and the master cylinder 20 is established, and Wheel cylinder 42, 4
Any communication between the reservoir 4 and the reservoir 54 is interrupted. This state is hereinafter referred to as a holding mode. In the holding mode, the brake fluid does not flow into or out of the wheel cylinders 42 and 44, so that the wheel cylinder pressure P _{W / C} is kept constant.

Further, a foil silicide is performed by the above-described decompression mode.
Pressure P_{W / C}Brake pressure is reduced,
When expressed, the wheel cylinder pressure P_{W / C}Is the master cylinder
Pressure P _{M / C}The pressure is increased toward. Hereinafter, the state shown in FIG.
Also referred to as pressure increase mode. As described above, the braking force of the present embodiment
According to the control device, the decompression mode, the holding mode, and
By changing the pressure increase mode as needed,
Linda pressure P_{M / C}Wheel cylinder pressure P regardless of_{W / C}To
Can be changed. Therefore, for example, the ECU 30
Detects that the wheels 50 and 52 have a tendency to lock.
The pressure reduction mode, the hold mode, and the pressure increase mode.
The slip ratio of the wheels 50 and 52 does not exceed the predetermined value.
The anti-lock brake is formed by switching
Key control is realized.

When the vehicle is stopped by the driver's brake operation, and the brake pedal is still depressed, the vehicle stops with the braking force applied. Until the vehicle stops, the vehicle decelerates at a deceleration corresponding to the braking force. On the other hand, when the vehicle stops, the deceleration of the vehicle becomes zero. Therefore, when the vehicle stops in a state where the braking force is applied, a stop shock occurs due to a discontinuous change in the deceleration at the moment of the stop.

In general, in order to reduce the stop shock, it is necessary that the driver relaxes the brake operation immediately before the stop to reduce the braking force when stopping. However, performing such a brake operation imposes a heavy burden on the driver when the brake operation such as running during traffic congestion is frequently required or when an inexperienced driver drives. .

On the other hand, the braking force control apparatus according to the present embodiment automatically reduces the wheel cylinder pressure P _{W / C} immediately before the vehicle stops, thereby reducing the stop shock (hereinafter referred to as the stop shock). Mitigation control). FIG. 2 shows the wheel cylinder pressure P _{W / C} and the vehicle speed when the vehicle stop shock prevention control is executed by the braking force control device of the present embodiment under the condition that the driver does not loosen the brake operation immediately before the vehicle stops. The time change of V is illustrated. In FIG. 2, for the sake of comparison, broken lines show the wheel cylinder pressure P _{W / C} and the vehicle speed V when the vehicle stop shock prevention control is not executed under similar conditions.

If the vehicle stop shock prevention control is not executed, the wheel cylinder pressure P _{W / C} becomes the master cylinder pressure P _{W / C.
The} value is equal to _{M / C.} For this reason, as shown by the broken line in FIG. 2, even at time t ₁ when the vehicle speed V reaches zero, the wheel cylinder pressure P _{W / C} is maintained at a non-zero value P ₀ . In this case, the vehicle stops with the braking force applied, and a stop shock occurs.

On the other hand, according to the braking force control device of this embodiment,
If time t₀The vehicle speed V is the reference value V_SBelow
It is determined that the vehicle is in the state immediately before stopping and
The lock prevention control is started. Stop shock mitigation control is executed
The wheel cylinder pressure P _{W / C}Is gradually decompressed
You. Therefore, when the vehicle speed V reaches zero, the wheel
Linda pressure P_{W / C}Stop is reduced to a
The occurrence of cracks is reduced.

When the wheel cylinder pressure P _{W / C} becomes zero, the braking force acting on the vehicle also becomes zero. Therefore, until the vehicle stops, the wheel cylinder pressure P is not less than a certain value.
_{W / C} must be generated. Accordingly, in this embodiment, the wheel cylinder pressure P _{W / C} so as not to reach zero, sets the pressure gradient [Delta] P W _{/ C} of the wheel cylinder pressure P _{W / C} before the vehicle speed V reaches zero I have to do that.

The above-described stop shock mitigation control is performed by the ECU.
30 is realized by executing a predetermined stop shock mitigation control routine. As described above, the wheel cylinder pressure P _{W / C} is rapidly reduced when the pressure reducing mode is established, and the wheel cylinder pressure P _{W / C} is kept constant when the holding mode is established. Therefore, in the shock mitigation control routine, the ECU 30 alternately sets the pressure reduction mode and the holding mode to reduce the wheel cylinder pressure P _{W / C.} In this case, the wheel cylinder pressure P _{W / C} is reduced more quickly as the pressure reduction mode is formed for a longer time than the holding mode. Therefore, by appropriately setting the ratio between the duration of the pressure reduction mode and the duration of the holding mode, a desired pressure reduction gradient ΔP _{W / C} of the wheel cylinder pressure P _{W / C} can be realized.

In order to effectively reduce the stop shock, it is preferable that the wheel cylinder pressure P _{W / C} when the vehicle stops is as small as possible. Therefore, when the stop shock prevention control is started, that is, when the vehicle speed V becomes V _S
, Based on the wheel cylinder pressure P _S
Wheel cylinder pressure P _{W / C} at the same time as vehicle speed reaches zero
So they reach zero, it is also possible to set the pressure gradient [Delta] P W _{/ C} of the wheel cylinder pressure P _{W / C.}

Alternatively, during execution of the vehicle stop shock prevention control, the wheel cylinder pressure P
By varying the pressure gradient [Delta] P W _{/ C} of the _{W / C,} the value of the wheel cylinder pressure P _{W / C} of when the vehicle speed reaches zero may be controlled to be exactly zero. Incidentally, as described above, the vehicle stop shock prevention control reduces the wheel cylinder pressure P _{W / C} , that is, the braking force immediately before the vehicle stops. For this reason, when the stop shock mitigation control is executed, the braking distance increases as compared with the case where the stop shock mitigation control is not executed. Therefore, when the driver is performing a sudden braking operation, priority should be given to stopping the vehicle promptly rather than to preventing a stop shock.

Therefore, in the braking force control device according to the present embodiment, it is determined whether or not the driver is performing a sudden braking operation based on the master cylinder pressure PM _{/ C} or the deceleration of the vehicle. If it is determined that sudden braking is being performed, execution of the stop shock mitigation control is prohibited. However, even if there is an obstacle in front of the vehicle and the vehicle must be stopped urgently, due to the carelessness of the driver or because the obstacle suddenly appears in front of the vehicle, etc. However, sudden braking may not be performed. The braking force control device according to the present embodiment is characterized in that even in such a case, it is possible to prevent the braking distance from increasing by prohibiting the execution of the stop shock mitigation control.

The function of the above-mentioned braking force control device is determined by the ECU 3
0 is realized by executing a predetermined routine.
Hereinafter, with reference to FIG. 3, the contents of the routine executed by the ECU 30 in the present embodiment will be described. FIG. 3 shows the ECU
Numeral 30 is a flowchart of a routine executed to prohibit and permit the stop shock mitigation control. This routine is a regular interruption routine executed at regular time intervals. In this routine, the control prohibition flag F is set and reset in accordance with the running condition of the vehicle. When the control prohibition flag F is set, the execution of the above-described stop shock mitigation control routine is prohibited. When the control prohibition flag F is set during the execution of the stop shock mitigation control routine, the execution is stopped. Is immediately terminated.

When the routine shown in FIG. 3 is started, first, the process of step 100 is executed. Step 10
In 0, whether the vehicle speed V is equal to or smaller than the reference value V _S is determined. As a result, if V ≦ V _S is not established, it is determined that the vehicle is not immediately before stopping and that the stop shock mitigation control should not be executed.
02 is executed. In step 102, the execution of the stop shock mitigation control is prohibited by setting the control prohibition flag F. When the process of step 102 is completed, the current routine is completed. Step 1
At 00, if V ≦ V _S holds, it is determined that the vehicle is just before stopping, and the process of step 104 is executed next.

In step 104, the master cylinder pressure P
_{M / C} is smaller than the predetermined value P _1, and the master cylinder pressure P _{M / C} of the time rate of change _{ΔP M / C (= dP M} / C / dt)
Is less than zero. Here, the predetermined value P ₁ is a threshold value for determining whether or not a sudden braking operation is being performed. If the master cylinder pressure P _{M / C} is smaller than P ₁ , the sudden braking operation is performed. Is determined not to have been performed. If ΔP _{M / C} is smaller than zero, that is, if the master cylinder pressure P _{M / C} has decreased, it is determined that the brake pedal has not been increased. Therefore, in step 104, _{PM / C} <
If P ₁ and ΔP _{M / C} <0 hold, it is determined that the sudden braking operation is not currently performed and that the sudden braking operation is not to be performed anymore. Is executed. On the other hand, if P _{M / C} <P ₁ and ΔP _{M / C} <0 do not hold in step 104, a sudden braking operation is currently being performed, or
There is a possibility that a sudden braking operation will be performed from now on, so it is determined that the stop shock mitigation control should not be executed. In this case, next, at step 102, the control prohibition flag F is set, and then this routine is ended.

In step 104, the sudden braking operation is detected based on the master cylinder pressure PM _{/ C.} However, the sudden braking operation may be detected based on the deceleration of the vehicle. Alternatively, a stroke sensor or a pedaling force sensor may be provided on the brake pedal 24, and a sudden braking operation may be detected based on output signals of these sensors.

In step 106, it is determined whether an obstacle exists within a predetermined distance in front of the vehicle. Here, the predetermined distance is a threshold value used as a criterion for determining whether or not the vehicle should be stopped urgently. The determination in step 106 is made based on the output signal of the obstacle detection unit 70. In step 106, when it is determined that there is no obstacle within a predetermined distance in front of the vehicle, it is determined that there is no problem even if the braking distance is increased by executing the stop shock mitigation control. In this case, then step 10
At 8, the control prohibition flag F is reset, thereby permitting the execution of the stop shock mitigation control. When the process of step 108 is completed, the current routine is completed. On the other hand, if it is determined in step 108 that an obstacle ahead of the vehicle is present, it is determined that the vehicle should be stopped promptly.
After the control prohibition flag F is set in 02, the current routine ends.

As described above, according to the braking force control device of the present embodiment, not only when the driver performs a sudden braking operation but also when an obstacle exists in front of the vehicle,
Execution of the stop shock mitigation control can be prohibited.
Therefore, according to the present embodiment, the stop shock can be effectively mitigated in a situation where the vehicle does not need to be stopped immediately, and in a situation where the vehicle should be stopped urgently, In addition, the vehicle can be stopped at a short braking distance.

Note that, in the above embodiment,
If an obstacle is detected, the stop shock is alleviated.
Control execution is prohibited, but the present invention is not limited to this.
It is not specified, but the distance to the obstacle in front of the vehicle
Based on the wheel cylinder
Da pressure P_{W / C}Pressure gradient ΔP_{W / C}To change
Is also good. That is, in the stop shock mitigation control,
Pressure gradient ΔP_{W / C}The greater the
The braking distance is increased with relaxation, while the decompression gradient Δ
P_{W / C}Is smaller, the mitigation effect of the stop shock decreases.
And the braking distance is reduced. Therefore, the distance to the obstacle
As the separation becomes smaller, the pressure reduction gradient ΔP _{W / C}Decrease
Control the braking distance within the required range
And provide a certain stopping shock alleviation effect.
Can be.

In the above embodiment, the present invention
The case where the present invention is applied to the braking force control device that controls the braking force by the ABS actuator 28 has been described. However, the present invention is not limited to this, and is applied to any braking force control device that can automatically control the braking force. Can be applied. In the above embodiment, the ABS actuator 28 corresponds to the braking force generating means described in claims 1 and 2, and the obstacle detecting unit 70 corresponds to the obstacle detecting means described in claims 1 and 2, respectively. The ECU 30 executes a stop shock mitigation control routine, whereby the stop shock mitigation control means according to claim 1 or 2 executes the ECU 3
0 executes steps 106 and 102 of the routine shown in FIG. 3 so that the control prohibiting means according to claim 1 allows the ECU 30 to reduce the decreasing gradient Δ according to the distance to the obstacle.
The reduction rate control means according to claim 2 is realized by changing P _{W / C.}

[0038]

As described above, according to the first aspect of the present invention, when an obstacle is present ahead of the vehicle, it is possible to prohibit the reduction of the braking force by the stop shock mitigation control means. Therefore, it is possible to prevent the braking distance from increasing in a situation where the vehicle should be stopped urgently.

According to the second aspect of the present invention, the rate of reduction of the braking force by the stop shock mitigation control can be changed according to the distance to the obstacle ahead of the vehicle. Therefore, the vehicle can be stopped at a required braking distance according to the distance to the obstacle, and the stopping shock can be reduced at a degree corresponding to the reduction rate of the braking force.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a braking force control device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating changes over time in wheel cylinder pressure and vehicle speed when the stopping shock mitigation control is executed by the braking force control device of the present embodiment, in comparison with the case where the stopping shock mitigation control is not executed.

FIG. 3 is a flowchart of a control permission determination routine that is executed by the ECU to permit and prohibit stop shock mitigation control in the present embodiment.

[Explanation of symbols]

 28 ABS actuator 30 ECU 70 Obstacle detection unit

Claims (2)

[Claims] 1. A braking force generating means for generating a braking force according to a brake operation amount; a stop shock mitigation control means for automatically reducing a braking force generated by the braking force generating means immediately before a vehicle stops; Obstacle detection means for detecting whether an obstacle is present within a predetermined distance in front of the vehicle, and when an obstacle is detected by the obstacle detection means,
And a control prohibiting means for prohibiting the operation of the stop shock mitigation control means. 2. A braking force generating means for generating a braking force according to a brake operation amount; a stop shock mitigation control means for automatically reducing a braking force generated by the braking force generating means immediately before a vehicle stops; Obstacle detecting means for detecting a distance to an obstacle in front of the vehicle, and changing a reduction rate of a braking force by the stop shock mitigation control means based on the distance to the obstacle detected by the obstacle detecting means. A braking force control device comprising: a reduction rate control unit.