JP2000335392A - Control device for braking rear double-axle vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the early abrasion of a tire by eliminating the locking of a rear-rear axle wheel. SOLUTION: A braking control device comprises first and second rear wheel lines R1, R2 which are provided with an axle load moving device and feed a working fluid to a wheel cylinder 3 of one side wheel of right and left wheels and a wheel cylinder 3 of the other side wheel of the right and left wheel of right and left wheels W1l of a rear-front axle and right and left wheels W2l, W2r of a rear-rear axle, control valves 6, 7 to control the braking pressure to each wheel cylinder 3, a wheel speed sensor 22, a steering angle sensor 23, a horizontal acceleration sensor 24, and an ABS control device 8 in which the control valves 6, 7 are subjected to the select-low control of the front-rear axle wheel on each of the right and left wheels if the steering angle is at least a specified value θα, and the horizontal acceleration is at least a specified value, while the control valves 6, 7 are controlled based on the right and left wheels of the rear-front axle if the steering angle γs and the horizontal acceleration G are below the specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device capable of securing safety by eliminating wheel lock during braking of a vehicle, and more particularly to a braking control device for a rear two-axle vehicle employed in a rear two-axle vehicle. .

[0002]

2. Description of the Related Art Locking tendency of each wheel at the time of braking of a vehicle It is determined whether or not there is dense fog, and the pressure of the working fluid for braking is increased or decreased accordingly, thereby preventing wheel locking.
2. Description of the Related Art There is known an anti-lock device that secures steering stability of a vehicle during braking.

[0003] By the way, in the case of a vehicle having two rear axles, especially a vehicle having a rear front axle as a drive shaft and a rear rear axle as a driven shaft, when the vehicle is in an empty state or in a load state close thereto, the load distribution of the rear front axle is made smaller than the rear rear axle. It is desirable to increase the size to secure startability. For this reason, the vehicle is equipped with an axle load shifting device, which adjusts the load distribution of the rear front axle larger than that of the rear rear axle, ensuring the startability when the vehicle is empty and the rear front axle and rear rear axle when loading. Axial weight distribution can be accurately performed.

[0004] However, when such a conventional rear two-axle vehicle enters an unoccupied state or a loaded state close to the empty vehicle and starts turning after adjusting the load distribution of the rear front axle larger than that of the rear rear axle,
When the braking operation is performed, the rear rear axle inner wheel, which is the driven wheel, tends to lift up and is easily locked, and in this case, there occurs a problem that the wear of the tire proceeds. In order to solve such a problem, for example, a control valve is attached to each of the common braking lines of the left and right wheels of the front axle and the individual braking lines of the left and right wheels of the rear axle and the rear rear axle, It is assumed that a 6-sensor 5-channel anti-lock device in which wheel-side sensors are attached to all wheels is used. In this case, the anti-lock device performs left / right select low control for the front wheels,
The left and right wheels of the rear front axle and the rear rear axle can be independently controlled, locking of the rear rear axle can be reliably prevented, and braking efficiency is good. Furthermore, a common braking line disposed over the front left and right wheels of the vehicle, a common braking line disposed over the rear left and rear rear wheels of the vehicle, a rear front wheel of the right side of the vehicle, It is assumed that a control valve is attached to each of the common braking lines disposed over the rear and rear axle wheels, and a six-sensor three-channel anti-lock device that attaches wheel-side sensors S to all wheels is used. Also in this case, the anti-lock device performs left and right select low control for the front wheels, and can perform select low control for each of the left and right sides of the vehicle, the front, front and rear rear axles, thereby securely locking the rear rear axles. It is possible to reduce the weight of the apparatus at a relatively low cost.

[0005]

However, when an anti-lock device having 6 sensors and 5 channels is used, the locking of the rear rear wheel can be reliably prevented, but this tends to increase the cost and weight of the device. Furthermore, when an anti-lock device with 6 sensors and 3 channels is used, the rear rear axle wheels can be reliably prevented from being locked. However, the adoption of the select low increases the operation rate of the ABS and consequently reduces the braking efficiency. The problem remains. SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to eliminate locking of a rear rear axle wheel and surely prevent early wear of a tire without increasing the cost of the apparatus or lowering braking efficiency.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, the rear front shaft of the vehicle is configured as a drive shaft and the rear rear shaft is configured as a driven shaft, and the load on the driven shaft side is reduced. A braking control device for a rear two-axle vehicle provided with an axle load moving device movable to a drive shaft side, wherein the first rear wheel braking line controls the left and right rear left and right rear wheels of the vehicle. The working fluid is supplied to the braking device for one of the front and rear wheels, and the working fluid is supplied to the braking device for the other front and rear wheels of the left and right rear left and right wheels by the second rear wheel braking line. A control valve is interposed in each of the first and second rear wheel braking lines, and a braking pressure to each of the braking devices is controlled by each control valve. A steering angle sensor attached to each of the left and right shafts to detect each wheel speed Detecting a steering angle of the steering device of the vehicle, detecting a lateral acceleration applied to the vehicle by a lateral acceleration sensor, and controlling the ABS control device so that the steering angle is equal to or more than a predetermined value, and the lateral acceleration is equal to or more than a predetermined value. In this case, the control valves of the first and second rear wheel braking lines are selectively low-controlled based on the wheel speeds of the left and right opposed front and rear axle wheels, respectively, so that the steering angle and the lateral acceleration become predetermined values. Is less than the above, the control valves of the first and second rear wheel braking lines are controlled based only on the wheel speeds of the left and right wheels of the rear front shaft.

As described above, the load distribution of the rear and front shafts is made larger than that of the rear and rear shafts by the axle load moving device to secure startability, and the steering angle and the lateral acceleration are less than predetermined values.
By controlling each control valve of the first and second rear wheel braking lines based only on the wheel speeds of the rear left and right front wheels during steady driving other than turning on a dry road or during low μ road turning, A reduction in braking efficiency due to heavy use of select row control can be avoided. Further, when the steering angle and the lateral acceleration are equal to or larger than predetermined values, that is, when turning on a dry road, the control valves of the first and second rear wheel braking lines are subjected to select low control of the front and rear axle wheels on the left and right sides, respectively. In spite of the fact that the rear rear axle has a low load distribution and the rear rear axle left and right wheels are easily locked, the lock is eliminated and early wear of the tire can be reliably prevented. That is, the load distribution of the rear and front shafts is made larger than that of the rear and rear shafts by the axle load moving device to secure startability, and the reduction in braking efficiency due to heavy use of the select row control is prevented without increasing the cost of the device. By performing select-low control only when turning on a dry road, the lock of the rear rear axle wheel can be eliminated, and early wear of the tire can be reliably prevented.

[0008]

FIG. 1 shows a brake device 1 to which a braking control device for a rear two-axle vehicle according to the present invention is applied. The brake device 1 is mounted on a rear two-axle truck (not shown). This track has one front axis (not shown) and two rear tracks shown in FIG.
Axis RAf, RAr, and front left and right wheels W0
l, W0r are located on the left and right of the rear front axis RAf, and the rear front left and right wheels W1
l and W1r form double wheels, respectively, and the rear rear shaft RA
Rear left and right rear wheels W21 and W2r are double-wheeled to the left and right of r, respectively, and pivotally supported. A rear two-axis track (not shown) has a rear front axis RAf as a drive axis and a rear rear axis RAf.
r is configured as a driven shaft, and a later-described axle load moving device 30 capable of moving the load on the driven shaft side to the drive shaft side at a predetermined ratio.
Is provided. Further, a wheel cylinder 3 as a braking device is provided opposite to the front left and right wheels W01 and W0r, and a front wheel braking line R0 described later for supplying a working fluid is connected to both wheel cylinders 3. A wheel cylinder 3 as a braking device is provided opposite to the rear front axle wheel W11 and the rear rear axle wheel W21 on the left side of the vehicle, and a first rear wheel braking line R1 to be described later for supplying working fluid is connected to both wheel cylinders. Is done.
A wheel cylinder 3 serving as a braking device is provided opposite to the rear front axle wheel W1r and the rear rear axle wheel W2r on the right side of the vehicle, and a second rear wheel braking line R2 for supplying a working fluid is connected to both wheel cylinders. Is done.

The brake valve 4 receives air supply from an air tank 11 which is a high-pressure air source, and sends air having an air pressure corresponding to the operation amount of a brake pedal 12 operated by a driver through the first air pipes 13 and 14. Relay valve before and after 1
Tell 5 and 16. Front relay valve 15 is air tank 1
1 is supplied through the front second air pipe 17, and relay air pressure corresponding to the air pressure from the brake pedal 12 is transmitted to the first control valve 5. The first control valve 5 increases or decreases the relay air pressure in accordance with a previous control command from the ABS control device 8 to provide a control air pressure, which is transmitted to the previous air master 9, where the boosted hydraulic pressure is applied to the front oil pipe. The power is transmitted to the respective wheel cylinders 3 of the front left and right wheels W01 and W0r via. The first air pipe 13 and the front second air pipe 17 on the air pipe system AE side and the front oil pipe 18 on the oil pipe system OE side constitute a front wheel braking line R0.

The rear relay valve 16 is supplied with air from the air tank 11 through a rear second air pipe 19, branches the relay air pressure according to the air pressure from the brake pedal 12, and controls the second and third control valves. Inform valves 6 and 7. The second control valve 6 increases or decreases the relay air pressure in response to a left control command from the ABS control device 8 to obtain a left control air pressure, which is transmitted to the left air master 9, where the boosted braking hydraulic pressure is applied. The power is transmitted to each of the wheel cylinders 3 of the front and rear left wheels W11 and W21 via the left oil pipe 20. The third control valve 7 increases and decreases the relay air pressure in response to a right control command from the ABS control device 8 to obtain a right control air pressure, which is transmitted to the right air master 9, where the boosted brake operating oil pressure is applied. Front right and left wheels W1 via right oil pipe 21
r and W2r are transmitted to the respective wheel cylinders 3. The rear first air pipe 14, the rear second air pipe 19 on the air pipe system AE side, and the left oil pipe 20 on the oil pipe system OE side form a first rear wheel braking line R1, and the air pipe system AE side After the first air pipe 1
4 and the rear second air pipe 19 and the right oil pipe 21 on the oil pipe system OE side
Constitute the second rear wheel braking line R2.

The front left and right wheels W01, W0r, the rear front left and right wheels W11, W1r, and the rear rear left and right wheels W21, W2r are provided with wheel speed sensors 22 for detecting respective wheel speeds. The speed information is output to the ABS control device 8.

The main part of the ABS control device 8 is formed by a microcomputer, and front and right wheels W01, W0 are provided on the input side thereof.
r, rear front left and right wheels W11, W1r, and rear rear left and right wheels W
The respective wheel speeds V01, V0r, V11, V1r, V21, V21 are detected by the respective wheel speed sensors 22 attached to the wheels 21 and W2r.
2r, the steering angle θs of the track steering device (not shown) is input from the steering angle sensor 23, the lateral acceleration G applied to the not-shown track is input from the lateral acceleration sensor 24, and the transmission (not shown) is output from the forward gear switch 25. Is in the forward gear, a forward gear mf signal is input.
First, second, and third control valves 5, 6, and 7 are connected to the output side of the ABS control device 8, and front, left, and right control commands are output to these. The ABS control device 8 has a function of performing the antilock control shown in FIGS. 4 and 5 based on each of the input information described above. That is, the ABS control device 8 controls the wheel speeds V01, W01,
Based on V0r, front left / right wheel select low control is performed. Further, when the steering angle θs is equal to or larger than the predetermined value θα and the lateral acceleration G is equal to or larger than the predetermined value Gα, the ABS
And the wheel speeds V11 and V21 of the left front and rear axle wheels and the wheel speed V1 of the right front and rear axle wheels that face the respective control valves 6 and 7 of the second rear wheel braking lines R1 and R2.
r, V2r based on the front-rear axis wheel select low control, and the steering angle θs and the lateral acceleration G are set to predetermined values θα, G
If α is less than α, the control valves 6 and 7 of the first and second rear wheel braking lines R1 and R2 are controlled based on only the wheel speeds V11 and V1r of the rear left and right front wheels W11 and W1r. It has a lock control function. Here, the setting of the predetermined value θ of the steering angle and the predetermined value Gα of the lateral acceleration are performed based on the data of the steering angle θs and the lateral acceleration G at the time of turning the vehicle on a dry road in advance. An appropriate value is set as a threshold value for determining whether or not the inside wheel in the turning direction enters the tire lock area during the turning traveling.

An axle load moving device 30 for moving the load of the rear rear shaft RAr, which is a driven shaft, to the rear front shaft RAf, which is a driving shaft, at a predetermined ratio is provided on such a truck. As shown in FIG. 2, the axle load moving device 30 includes left and right air suspensions 31, 32 for suspending a rear front shaft RAf and a rear rear shaft RAr on a frame 35 on the vehicle body side, and the air suspensions 31, 32. Supply valves 33f, 33 respectively
r, drive control of the normally closed exhaust valves 34f and 34r capable of discharging air from the air suspensions 31 and 32, and the supply valves 33f and 33r and the exhaust valves 34f and 34r. And a suspension control device 38. Suspension control device 3
Reference numeral 8 denotes a vehicle height adjusting function for supplying air pressure for maintaining a predetermined vehicle height to each of the air suspensions 31 and 32 in accordance with the vehicle height signal from the height sensor 37. For example, as shown in FIG.
It has a function of moving the axle load so as to achieve a pattern of the axis shared weight of the rear front and rear axes RAf and RAr according to the load capacity. In the light load area a from the empty vehicle We to the lightly loaded state Wea, the rear front axle is provided. By increasing the load sharing of RAf, the road surface grip characteristics of the rear front left and right wheels W11 and W1r on the drive shaft side are enhanced to control the starting performance.

The operation of the brake device 1 will now be described with reference to FIGS.
A description will be given along the antilock control routine shown in FIG. Here, the air pressure equivalent to the shaft shared weight Pwn of the rear longitudinal axis RAf has been supplied to the air suspensions 31 and 32 in advance according to the current load amount Wn (see FIG. 3). It is in a situation where startability at the time was secured.

The ABS controller 8 starts driving by turning on a main switch (not shown). Step a1
In the pre-processing described above, a failure determination of each sensor, power supply system, and the like is performed. At this time, if an abnormality of each unit is detected, the following antilock control is canceled and abnormality display means (not shown) is driven. In step a2, input of a brake signal is waited. During that time, outputs to the three control valves 5, 6, 7 are switched off in step a3. When a brake signal is input, it is determined in step a4 whether the forward speed mf signal of the forward speed switch 25 is being input. If the forward speed is not the forward speed, the process returns to step a3, and in the forward speed, the process proceeds to step a5.
In steps a5 and a6, the current steering angle θs is set to a predetermined value θα.
If the current lateral acceleration G is equal to or greater than the predetermined value Gα, that is, if it can be considered that the vehicle is traveling on a dry road, step a
7; otherwise, the process proceeds to step a13.

When step a7 is reached during turning on a dry road, the wheel speeds V01, V0r of the front left and right wheels W01, W0r.
Is compared with the first determination wheel speed V0α along the predetermined deceleration mode corresponding to the vehicle speed. When the value is lower than the first determination wheel speed V0α, the first control valve 5 is depressurized in step a8. The output oil pressure of the front air master 9 is reduced, and the values of the wheel speeds V01 and V0r are increased toward the first determination wheel speed V0α. Conversely, if the lower one of the wheel speeds V01 and V0r exceeds the first determination wheel speed V0α in step a7, the pressure in the first control valve 5 is increased or held in step a8, and the output of the front air master 9 is output. The hydraulic pressure is increased stepwise to control the wheel speeds V01 and V0r to decrease toward the first determination wheel speed V0α. Such select low anti-lock control of the front left and right wheels W01 and W0r can secure the braking force and prevent the traveling direction from becoming unstable due to the wheel lock, and then proceed to step a9.

Next, when step a9 is reached, the lower one of the wheel speeds V11 and V21 of the left front and rear axle wheels W11 and W21 corresponding to the first rear wheel braking line is set to a predetermined deceleration mode corresponding to the vehicle speed. Along with the second determined wheel speed V1α, and if the second determined wheel speed V1α is less than the second determined wheel speed V1α, step a
At 10, the second control valve 6 is depressurized to reduce the output oil pressure of the left air master 9, and the wheel speeds V11, V2
The value of 1 is increased toward the second determination wheel speed V1α.
Conversely, if the lower one of the wheel speeds V11 and V21 exceeds the second determination wheel speed V1α in step a9, the pressure in the second control valve 6 is increased or held in step a10, and the output of the left air master 9 is output. The hydraulic pressure is increased stepwise, and the values of the wheel speeds V11 and V21 become the second determination wheel speed V1α.
, And after that, after step a
Proceed to 11. Such a left front and rear axle wheel select low antilock control can prevent the left front and rear axle wheels W11 and W21 from being locked, thereby preventing the traveling direction from becoming unstable. In particular, the left rear axle wheel W21 is an inner wheel and a driven wheel when turning left. In addition, since the axle load is relatively small due to the load transfer process, the axle tends to rise. However, this left and right axle wheel select low control reliably removes the lock of the left rear axle wheel W21, thereby prematurely wearing the tire. Can be prevented.

Next, when step a11 is reached, right front and rear axle wheels W1r, W2r corresponding to the second rear wheel braking line.
The lower one of the wheel speeds V1r and V2r is compared with a third determination wheel speed V2α in accordance with a predetermined deceleration mode corresponding to the vehicle speed. When the wheel speed falls below the third determination wheel speed V2α, the third control valve is turned on at step a12. 7, the output hydraulic pressure of the right air master 9 is reduced, and the wheel speeds V1r, V2
The value of r is increased toward the third determination wheel speed V2α.
Conversely, if the lower one of the wheel speeds V1r and V2r exceeds the third determination wheel speed V2α in step a11, the pressure in the third control valve 7 is increased or held in step a11, and the output of the right air master 9 is output. The oil pressure is increased stepwise, and the values of the wheel speeds V1r and V2r are changed to the second determination wheel speed V2.
is controlled so as to descend toward α, and thereafter, step a
Return to 2. Such a right front and rear axle wheel select low anti-lock control can prevent the right front and rear axle wheels W1r and W2r from becoming unstable in the running direction due to the lock. The right and left axle wheel select row control removes the lock on the right rear axle wheel W2r and reduces the early wear of the tires because the axle weight is relatively small due to the moving wheel and the axle load is relatively small due to the load transfer processing. Can be prevented. Again, from step a2 to step a
If the current steering angle θs is not equal to or greater than the predetermined value αα, or if the current lateral acceleration G is not equal to or greater than the predetermined value Gα, that is, straight traveling other than dry road turning traveling or low μ road, If the vehicle is turning, the process proceeds to step a13. In steps a13 and a14, the same control as in steps a7 and 8 is performed.

Next, at step a15, the wheel speed V11 of the rear front left shaft wheel W11 is compared with the normal determination wheel speed Vnα along a predetermined deceleration mode corresponding to the vehicle speed. At a16, the second control valve 6 is depressurized to increase the wheel speeds V11 and V21 of the left front and rear axle wheels. Conversely, at step a15
If the value of the wheel speed V11 exceeds the normal determination wheel speed Vnα in step a16, the second control valve 6 is increased or maintained in step a16 to control the wheel speeds V11 and V21 to drop, and the process proceeds to step a17. Next, when reaching step a17, the wheel speed V1 of the rear front axle right wheel W1r
r is compared with the normal determination wheel speed Vnα in accordance with the predetermined deceleration mode corresponding to the vehicle speed. When the vehicle speed falls below the normal determination wheel speed Vnα, the third control valve 7 is depressurized in step a18, and the wheel speed V1r of the rear front shaft right wheel Conversely, if the value of the wheel speed V1r exceeds the normal determination wheel speed Vnα in step a16, the pressure in the third control valve 7 is increased or held in step a18, and the wheel speeds V1r, V
Control is performed so that 2r falls, and the process returns to step a2.

As described above, when the vehicle is running straight or turning on a low μ road, the front left and right wheels W01 and W0r are independently antilock controlled, and the rear shaft antilock control is performed only by the wheel speed of the rear front left and right wheels. The first and second rear axle braking lines are controlled on the basis of the above, so that even if the wheel speed control of the rear right and left rear wheels W21 and W2r is ignored, the instability of the traveling direction during braking can be prevented, and As in the case of performing the anti-lock control of both the left and right axle wheels and the right and left axle wheels, it is possible to prevent the braking efficiency from being reduced due to the reduction of the braking range due to the frequent use of the select row, and the braking distance is relatively short. Can,
Increases safety.

[0021]

According to the first aspect of the present invention, the load distribution of the rear front shaft is made larger than that of the rear rear shaft by the axle load moving device to secure startability, and the select load can be reduced without increasing the cost of the device. It is possible to prevent the reduction of braking efficiency by reducing the frequent use of control, and to eliminate the lock of the rear rear axle wheel by the select-row control only when turning on a dry road, thereby reliably preventing early wear of the tire.

[Brief description of the drawings]

FIG. 1 is an overall functional configuration diagram of a brake device to which a braking control device for a rear two-axle vehicle as one embodiment of the present invention is applied.

FIG. 2 is a schematic configuration diagram of an axle load moving device attached to a truck including the brake device of FIG.

FIG. 3 is a shared axle load characteristic diagram of the axle load moving device of FIG. 2;

FIG. 4 is a front flowchart of an anti-skid control routine of the brake device to which the braking control device for the rear two-axle vehicle of FIG. 1 is applied;

FIG. 5 is a rear flowchart of an anti-skid control routine of the brake device to which the braking control device for the rear two-axle vehicle of FIG. 1 is applied;

[Explanation of symbols]

 Reference Signs List 1 brake device 3 wheel cylinder 5, 6, 7 control valve 8 ABS control device 22 wheel speed sensor 23 steering angle sensor 24 lateral acceleration sensor 30 axle load moving device θs steering angle θα predetermined value of steering angle G lateral acceleration Gα lateral acceleration Predetermined value RAf Rear front shaft RAr Rear rear shaft R1, R2 First and second rear wheel braking lines V11, V1r Rear front left and right wheel speeds V21, V2r Rear rear left and right wheel speeds W11, W1r Rear front shaft Left and right wheels W21, W2r Rear rear left and right wheels

Claims (1)

[Claims] 1. A braking system for a rear two-axle vehicle having a rear front shaft as a drive shaft and a rear rear shaft as a driven shaft, and an axle load moving device capable of moving a load on the driven shaft side to the drive shaft side. In the control device, a first rear wheel braking line for supplying a working fluid to a braking device for one of left and right front left and right wheels of the rear front shaft left and right wheels and the rear rear shaft left and right wheels; A second rear wheel braking line for supplying a working fluid to the other left and right front and rear wheel braking devices of the left and right shaft wheels; and a first and a second rear wheel braking line interposed in each of the braking devices. A control valve for controlling a braking pressure, a wheel speed sensor attached to each of the rear left and right front rear wheels and a rear rear left and right wheel to detect a wheel speed, and a steering angle sensor for detecting a steering angle of a steering device of the vehicle. A lateral acceleration sensor for detecting a lateral acceleration applied to the vehicle; When the steering angle is equal to or more than a predetermined value and the lateral acceleration is equal to or more than a predetermined value, the control valves of the first and second rear wheel braking lines are turned to the left and right opposed front and rear axle wheels. When the steering angle and the lateral acceleration are less than predetermined values, the control valves of the first and second rear wheel braking lines are set to the respective wheel speeds of the rear left and right front left and right wheels. And an ABS control device that performs independent control based only on the braking control.