JPH11348767A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device for a vehicle for surely preventing the slip down of the vehicle, even at the time of the shortage of the braking force of a slope-go auxiliary device, by simple constitution and an inexpensive manufacturing cost. SOLUTION: When the movement of a vehicle is detected by a vehicle movement detecting means 31 at the time of the braking force retaining condition of a slope-go auxiliary device, an electromagnetic valve device 25 is switchedly controlled by a controlling means 30 to shift a brake chamber 24 into a braked condition. A vehicle can be surely stopped even at the time of the shortage of the braking force of the slope-go auxiliary device, by thus only providing the valve device 25 in a pressure line for an existing parking brake.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake control device provided with a slope start assist device.

[0002]

2. Description of the Related Art Conventionally, in order to eliminate the trouble of brake operation when starting on a slope, the braking state is maintained when the vehicle temporarily stops on an uphill road, and the braking is automatically released when the vehicle starts moving. Brake control devices provided with auxiliary devices are widely practiced. For example, in a brake device of this type using hydraulic pressure, the hydraulic pressure line of the brake system is shut off when the vehicle temporarily stops on an uphill road, and the hydraulic pressure increased by the brake operation even after the driver's braking operation is stopped. , The braking is continued, and when the vehicle is started thereafter, the hydraulic line is opened to release the braking. Similarly, with a brake control device (air over hydraulic brake) that uses both hydraulic pressure and pneumatic pressure, the air line between the dual air brake valve and the air over hydraulic booster that regulates the air pressure according to the brake operation is shut off. Thus, even after the braking operation is stopped, the air pressure is maintained and the braking is continued, and the air line is opened and the braking is released when the vehicle starts moving.

[0003]

As described above, the operating principle of the hill start assist device is that the hydraulic line and the air line are temporarily cut off to maintain the increased hydraulic pressure and the air pressure and to perform braking. The point is to continue. Therefore, the braking force acting to prevent the vehicle from slipping off on an uphill road is determined by the driver's brake operation force when the vehicle stops at that point, and is determined by the driver's carelessness compared to the gradient of the road surface. If the braking operation force is insufficient, or if the braking force is insufficient due to an unexpected defect in the brake pressure line, the vehicle may slip off.

[0004] Therefore, if the vehicle moves in spite of the operation of the slope start assist device, the buzzer is activated to urge the driver to re-operate the brake, and the door is opened even if the vehicle is not moving. When the vehicle is released, it is predicted that the driver will be out of the vehicle and will not be able to cope with re-operation of the brake. Therefore, measures have been taken to activate the buzzer to call attention.

[0005] However, the above countermeasures are not sure measures because they only give a warning to the driver.
More drastic measures were desired. It is conceivable to forcibly apply a brake when a slippage occurs by adding a brake system of another system, but this is not a practical measure because it involves a significant increase in cost.

SUMMARY OF THE INVENTION It is an object of the present invention to avoid a rise in manufacturing cost by a simple configuration and to reliably prevent a vehicle from slipping and falling even when the braking force of a hill start assist device is insufficient. It is an object of the present invention to provide a vehicular brake control device that can be used.

[0007]

In order to attain the above object, according to the present invention, when the vehicle movement is detected by the vehicle movement detecting means while the hill start assist device is in the braking force holding state, the electromagnetic force is controlled by the control means. The drive of the valve device is controlled to switch the brake chamber to the braking state. Therefore, even when the braking force of the hill start assist device is insufficient, the vehicle is reliably stopped, and a simple configuration in which an electromagnetic valve device is simply interposed in an existing parking brake line for a wheel park. It is feasible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle brake control device embodying the present invention will be described below.

The brake control device of this embodiment is configured as an air-over-hydraulic brake that uses both hydraulic pressure and pneumatic pressure. In addition to a normal service brake function used for decelerating and stopping the vehicle during traveling, it serves as a parking brake during parking. Wheel park function that applies braking force to the rear wheels,
And a hill start assist function for assisting the driver's brake operation at the start of the hill.

First, a configuration relating to a service brake function will be described. As shown in FIG. 1, an air compressor 2 is rotationally driven by an engine 1 mounted on a vehicle. An air tank 5 is connected to the air compressor 2 via a first air pipe 4 provided with an air dryer 3 for removing moisture, and the compressed air discharged from the air compressor 2 is introduced into the air tank 5 so as to be always at a predetermined level. It is kept at pressure. A dual brake valve 7 is connected to the air tank 5 via a second air line 6. The dual brake valve 7 has an electromagnetic forced shutoff valve 8 of a slope start assist device and a pressure switch 9 for a stop lamp. Are connected to front and rear air-over-hydraulic boosters 11 and 12 (hereinafter simply referred to as boosters) via a third air pipe 10 provided. The dual brake valve 7 is provided with a brake pedal 7a, and the opening of the dual brake valve 7 is adjusted in accordance with a stepping operation by a driver, and air pressure proportional to the opening acts on each of the boosters 11, 12.

The front booster 11 is connected to the left and right front wheel cylinders 15 via a first hydraulic line 13.
Meanwhile, the rear booster 12 is connected to the left and right rear wheel cylinders 16 via the second hydraulic line 14, and the boosters 11 and 12 respectively control the hydraulic pressure according to the air pressure from the dual brake valve 7. The hydraulic pressure is generated and the hydraulic pressure of each wheel cylinder 1 is increased via hydraulic lines 13 and 14.
Acts on 5,16. A brake fluid tank 17 is connected to the boosters 11 and 12, so that brake fluid is supplied.

Next, a structure relating to the wheel park function will be described. A quick release valve is provided in the air tank 5 via a fourth air line 21 provided with a hand control valve 20 which is opened and closed by a driver. 22
Is connected to the quick release valve 22.
Are connected to the left and right brake chambers 24 via the air pipe 23 of the first embodiment. As is well known, the brake chamber 24 is integrally formed with the rear wheel cylinder 16, and when there is no air supply, the piston of the wheel cylinder 16 is mechanically moved to the braking side by a built-in compression coil spring. It is energizing. When a wheel park is not required, such as when driving, the hand control valve 2
With the opening operation of 0, air pressure from the air tank 5 is supplied into the brake chamber 24, and the compression coil spring is compressed by the air pressure to release the braking force.

On the other hand, the fifth air line 21 is provided with an electromagnetic forcible discharge valve 25 as an electromagnetic valve device. When the forced discharge valve 25 is open, the air tank 5 and the brake chamber 24 communicate with each other as shown by an arrow a. When the forcible discharge valve 25 is closed, the air tank 5 side is shut off, and the arrow b
As shown by the arrow, the brake chamber 24 and the atmosphere side are configured to communicate with each other. At this time, the air pressure acting on the brake chamber 24 is discharged to the outside (atmosphere).

In the passenger compartment, an input / output device (not shown), storage devices (ROM, RAM, BURAM, etc.) for storing control programs and control maps, etc., and a central processing unit (C)
PU), E as control means including a timer counter, etc.
CU (brake control unit) 30 is installed,
Performs comprehensive control of the brake system. ECU 30
On the input side, a stop lamp switch signal for detecting the operation of the brake pedal, a vehicle speed sensor 31 as a vehicle movement detecting means for detecting the vehicle speed, a stroke sensor 32 for detecting the connection state of the clutch, and switching of the transmission to a neutral position , A main switch 34 of the slope start assist device, a parking brake switch 35 for detecting the operation state of the parking brake, and the like. The output of the ECU 30 is connected to the forced shutoff valve 8 and the forced discharge valve. 25 are connected.
The ECU 30 controls the valves 8 and 25 based on the detection information to execute the brake control when the vehicle starts on a slope.

Next, the operation of the vehicle brake control device configured as described above will be described.

First, the function as a service brake during normal running will be described. At this time, the hand control valve 20 is opened, and the forced discharge valve 25 is
Since the open state has been switched by the CU 30, the air pressure in the air tank 5 becomes the fourth and fifth air lines 21 and 2.
3 and acts on the brake chamber 24 to compress the compression coil spring. No braking force is generated in the rear wheel cylinder 16 by the wheel park. Further, since the forcible shutoff valve 8 has also been switched to the open state by the ECU 30, the third air line 10 is maintained in the communicating state.

When the driver performs a brake operation to decelerate and stop the vehicle, an air pressure proportional to the opening of the dual brake valve 7 flows from the air tank 5 through the second and third air lines 6 and 10 to the front. And rear booster 1
Acts on 1,12. Further, an oil pressure corresponding to the air pressure is generated in the boosters 11 and 12 and acts on the respective wheel cylinders 15 and 16 via the first and second hydraulic lines 13 and 14 to brake the respective wheels. .

Next, the function as a wheel park will be described. When parking, the driver closes the hand control valve 20 simultaneously with the parking brake operation.
As a result, the brake chamber 24 is shut off from the air tank 5 side, and the air pressure acting in the brake chamber 24 is discharged to the outside from the quick release valve 22 and the hand control valve 20, and the rear wheel is compressed by the compression coil spring. The cylinder 16 is mechanically biased to the braking side. As a result, the braking force acts on the rear wheels, and the vehicle can be more reliably stopped and held by the parking brake.

On the other hand, the function as a hill start assist device will be described.
0 indicates a condition of any one of a brake pedal operation signal based on the stop lamp switch 9, a clutch disconnection based on the detection of the stroke sensor 32, or a neutral state of the transmission based on the detection of the neutral switch 33, and a detection of the vehicle speed sensor When the conditions such as the vehicle speed 0 based on the detection and the parking brake release based on the detection of the parking brake switch 35 are satisfied, the situation is detected. E
The CU 30 closes the forced shutoff valve 8 to maintain the air pressure acting on the boosters 11 and 12 by the driver's brake operation. As a result, each wheel cylinder 15,
The hydraulic pressure acting on the wheel 16 is maintained, so that each wheel is continuously braked even if the driver stops the brake operation.

Thereafter, when conditions such as the completion of switching to any one of the gear positions based on the detection of the neutral switch 33 and the start of clutch connection based on the detection of the stroke sensor 32 are satisfied, the ECU 30 regards the driver as willing to start. Then, the forced cutoff valve 8 is opened. As a result, the hydraulic pressure acting on each of the wheel cylinders 15, 16 decreases as the air pressure acting on the boosters 11, 12 decreases,
The braking by the wheel cylinders 15 and 16 is released and the vehicle can be started. By this series of controls, the driver is released from the brake operation, and can easily start on a slope by focusing on the accelerator operation.

On the other hand, if the brake operation force is insufficient due to a defect in the brake line, carelessness of the driver, etc. at the time of starting on the slope, there is no possibility that the vehicle may fall off due to the gradient of the road surface. Can not say. EC
When U30 detects the movement of the vehicle based on the detection of the vehicle speed sensor 31 while maintaining the closed state of the forced shutoff valve 8, the U30 switches the forced discharge valve 25 to the closed state, assuming that the slippage has occurred. As a result, as shown by the arrow b, the air pressure in the brake chamber 24 is discharged to the outside from the forced discharge valve 25, and a braking force is generated in the rear wheel cylinder 16 by the compression coil spring, and the vehicle is reliably stopped. Let it. The forced discharge valve 25 switched to the closed state is opened together with the forced shutoff valve 8 when the vehicle starts moving.

In the vehicle brake control device of the present embodiment,
As described above, even if the vehicle moves due to a shortage of the braking force despite the operation of the slope start assist device, it is possible to reliably prevent the vehicle from slipping off. Moreover, the air tank 5
The components such as the brake chamber 24 and the like are the existing ones for the wheel park. As is clear from the figure, a point that a forced discharge valve 25 is provided and a program for controlling the forced discharge valve 25 are added to the ECU 30. Only points
The above-described effects can be obtained with a very simple configuration, and a rise in manufacturing cost can be avoided.

Although the description of the embodiments has been completed above, embodiments of the present invention are not limited to these embodiments. For example,
In the above embodiment, the air pressure is adjusted by the dual brake valve 7 according to the brake operation of the driver, and the hydraulic pressure corresponding to the air pressure is generated in the boosters 11 and 12 to obtain the braking force by the air-over hydraulic brake. However, the present invention is not limited to this, and may be a full-air brake device.

[0024]

As described above, according to the vehicle brake control device of the present invention, when the vehicle moves despite the operation of the slope start assist device, the electromagnetic valve device is controlled by the control means. And the brake chamber is switched to the braking state. Since the existing air park and brake chamber for the wheel park are used in this way, a simple configuration avoids a rise in manufacturing costs, and even if the braking force of the hill start assist device is insufficient, It is possible to reliably prevent the vehicle from falling off.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a vehicle brake control device according to an embodiment.

[Explanation of symbols]

 Reference Signs List 5 air tank 24 brake chamber 25 forced discharge valve (electromagnetic valve device) 30 ECU (control means) 31 vehicle speed sensor (vehicle movement detection means)

Claims (1)

[Claims] When the vehicle is stopped, a braking force generated by operating a brake pedal is retained even when the pedal is released, and when the vehicle starts, the braking force retained based on a driver's intention to start the vehicle is released. A vehicle brake control device having a hill start assist function, comprising: vehicle movement detection means for detecting that a vehicle has moved; and a brake control device interposed between an air tank and a brake chamber for a wheel park. An electromagnetic valve device capable of switching the brake chamber between a braking state and a non-braking state by controlling an operation state of air pressure to the chamber; and moving the vehicle when the hill start assist device is in a braking force holding state. Control means for controlling the operation of the electromagnetic valve device so as to bring the brake chamber into a braking state when the movement of the vehicle is detected by the detection means. A brake control device for a vehicle, characterized in that: