JPH03213454A - Brake device for vehicle having swing back preventing function - Google Patents

Abstract

PURPOSE:To properly prevent and control the occurrence of swing back regardless of a sloping road by executing control such that pressure reduction control devices for front wheels and rear wheels are operated in the case of an ascent and only a pressure reducing device for front wheels is caused to control reduction of a pressure in the case of a sloping road. CONSTITUTION:A hydraulic brake A for a vehicle suppresses rotation of front wheels and rear wheels through operation of a front brake cylinder Bf and a rear brake cylinder Br. Pressure reducing devices Cf and Cr for front and rear wheels are mounted on cylinders Bf and Br, respectively. When a vehicle speed is reduced to a value lower than a reference value, the pressure reducing devices Cf and Cr are controlled by a stop control means D to reduce a pressure in each of the the cylinders Bf and Br, and the occurrence of swing back during a stop is reduced. In this case, a means (d) to control a stop during inclination of a road surface is mounted to a stop control means D, and when an ascent is detected by a detecting means E, control of reduction of a pressure is executed and meanwhile, in the case of a descending road, control of reduction of a pressure is executed only by the pressure reducing device Cf for front wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vehicle brake system having a function of preventing swaying back when stopped, and particularly relates to swaying back prevention control on a climbing road and a descending road. .

BACKGROUND ART When stopping a moving vehicle, if the brake operating member is continued to be operated until the vehicle comes to a stop, the vehicle will inevitably sway and cause discomfort to the occupants. This is because when the vehicle travel speed (hereinafter referred to as vehicle speed) reaches zero and the vehicle stops, the deceleration decreases from a constant value to zero, and the driver should avoid shaking as much as possible when stopping. It is necessary to operate the brakes with care to avoid this. However, performing such a brake operation is not only difficult for beginners, but also not easy for experienced users.

Therefore, in the vehicle brake system described in Japanese Patent Application Laid-Open No. 1-164656, the vibration back when the vehicle is stopped is automatically alleviated regardless of the driving technique of the driver. This brake device applies pressure to the front I-brake cylinder of the brake that suppresses the rotation of the front wheels and the rear brake cylinder of the brake that suppresses the rotation of the rear wheels, respectively, according to the operating amount such as the operating force and operating stroke of the brake operating member. A hydraulic brake system that suppresses the rotation of the front and rear wheels by generating a and stop control means for reducing. If the pressure in the brake cylinder is lowered, the deceleration will be reduced, and the change in deceleration at the time of stopping will be reduced, resulting in less wobbling.

In this brake device, the slope detection means detects whether the road surface is an uphill road or a downhill road, and the hydraulic pressure in the brake cylinder is reduced in a pressure reduction pattern suitable for each case. On the uphill road, gravity acts in the direction of braking the vehicle, while on the downhill road, it acts in the driving direction, so in order to stop the vehicle with less wobbling and a short braking distance, it is necessary to It is desirable to change the decompression pattern.

Furthermore, the applicant of the present application previously proposed in Japanese Patent Application No. 1-60085 to reduce the pressure in the front brake cylinder and the rear brake cylinder in different patterns. In addition to the fluid pressure brake system, this brake system is equipped with a front wheel pressure reducing device and a rear wheel pressure reducing device that can reduce the pressure in the front brake cylinder and the pressure in the rear brake cylinder, respectively. The control means controls the front wheel pressure reducing device and the rear wheel pressure reducing device. For example, after the start of braking, the vehicle speed is greatly reduced in a short period of time, and during braking, the brake cylinder pressure of the front and rear wheels is reduced, while during gentle braking, where the vehicle speed is gradually reduced, the brake cylinder pressure of the front wheels is reduced. only is depressurized. During sudden braking, the pressure in the brake cylinder is high, and if pressure is not reduced, a large swing will occur when stopping, so it is desirable to perform pressure reduction control for both the front and rear, while during gentle braking, the pressure in the brake cylinder is low, so no pressure reduction is required. However, it is advantageous to suppress the increase in braking distance by not reducing the rear wheel brake cylinder pressure, and by not reducing the rear wheel brake cylinder pressure. Further, by reducing both the front wheel brake cylinder pressure and the rear wheel brake cylinder pressure, and by making the pressure reduction patterns different from each other, fine-grained control to prevent swing back can be performed.

Problems to be Solved by the Invention However, when the pressure is reduced in both the front and rear wheels during sudden braking, and only in the front wheels during slow braking, as described in Section 2, problems occur on the descending road and on the ascending road. If sudden braking is applied on a descending road, the brake cylinder pressure for both the front and rear wheels will be reduced, but on a descending road, driving force is applied to the vehicle due to the slope of the road surface, so all brakes are If the cylinder pressure is reduced, the braking force will be insufficient and the braking distance will become longer.

In order to suppress the extension of the braking distance, it is necessary to maintain the brake cylinder pressure at an appropriate level, but it is necessary to maintain the brake cylinder pressure that can suppress the extension of the braking distance to a small level and also effectively prevent the brake from swinging back. It's not easy. on the other hand,
When braking is performed gently on a climbing road, only the brake cylinder pressure of the front wheels is reduced, but this significantly worsens the stopping feeling.

When braking, a load is transferred to the front of the vehicle, causing the front of the vehicle to sink while the rear of the vehicle lifts up.When the vehicle stops, the reaction causes the front to lift and the rear to rotate in the direction of sinking, resulting in pitching. Furthermore, during braking, the deceleration suddenly drops to zero, causing rearward wobbling, and this rearward wobbling and pitching cause the wobbling to return. Therefore, by reducing pitching, it is possible to reduce back-sway, and for this purpose, suspension links in vehicles are generally configured to be able to reduce pitching. In other words, as shown in Fig. 9, when braking, the front wheels 2
Frictional forces F, Fr are generated at the rear wheels 240 and 242, respectively, and based on this, inertial forces F, 10F,
As a result, a rotational moment 1- is generated and the front wheel 24
The load on the rear wheel 242 increases by ΔW, and the load on the rear wheel 242 decreases by ΔW. As a result, the front wheel 240 receives a resultant force Rf of Fr and ΔW.
acts on the rear wheel 242, and a resultant force R1 of Fr and -ΔW acts on the rear wheel 242, which elastically deforms the suspension spring, causing the front of the vehicle to sink and the rear of the vehicle to rise. Now, front wheel 240 and rear wheel 2
If the suspension link with 42 allows both wheels to rotate around the rotation centers Of and Or, respectively, the amount of depression of the front of the vehicle body is determined by the line of action of the resultant force R7 and the rotation center Of. The amount of lift of the rear part of the vehicle body is proportional to the product of the distance and the size of the joint JR, and the amount of lift of the rear part of the vehicle body is proportional to the product of the distance between the line of action of the resultant force Rr and the rotation center Or and the size of the resultant force Rr. Therefore, the center of rotation is 0. ．． The suspension link is constructed so that 0 is brought as close as possible to the line of action of the resultant forces Rf and Rr. However, if only the brake cylinder pressure of the front wheels is reduced, the frictional force of the front wheels disappears as shown in Fig. 10, and even though the amount of load reduction ΔW of the rear wheels based on load transfer becomes small, the Frictional force F
, does not decrease, the inclination angle θ of the resultant force R, becomes smaller, and the amount of compression of the suspension spring increases accordingly. As a result, the rear of the car sinks, and the sinking of the rear of the car due to pitching is magnified.
On the road, the rear of the car is naturally lower than the front and slants downward, so the rear of the car seems to sink particularly large, causing discomfort to the passengers.

The present invention provides a vehicle in which the anti-sway control is performed by reducing both or only one of the brake cylinder pressures of the front wheels and the rear wheels, and where the anti-sway control is appropriately performed on the uphill road and the downhill road. The objective of this project was to provide a brake device for use in motor vehicles.

Means for Solving the Problems In order to solve the above problems, the vehicle brake system of the present invention, as shown in FIG. In a vehicle brake system having a pressure reducing device for wheels and (C) a stop control means, a slope detection means is provided to detect whether the road surface is an uphill road or a downhill road. In the case of a road, both the front wheel pressure reducing device and the rear wheel pressure reducing device are made to reduce the pressure, and if the road surface is a drop-off road, the front wheel pressure reducing device is made to reduce the pressure, while the rear wheel pressure reducing device is made to reduce the pressure. The present invention is characterized in that it is provided with a stop control means when the road surface is inclined, which prevents the pressure from being reduced.

In the vehicle brake system configured as described above, when the slope detection means detects that the road surface is a hilly road, the brake cylinder pressure is applied to both the front and rear wheels regardless of whether the braking is slow or slow. The pressure is reduced. If the brake cylinder pressures of both the front and rear wheels are reduced, the rear part of the vehicle body sinks less when stopped, and the stopping feeling is improved, compared to when only the brake cylinder pressure of the front wheels is reduced. Furthermore, since the slope of the road surface applies braking force to the vehicle, the braking distance can be kept small. On the other hand, if it is detected that the road surface is a drop-off road, pressure reduction control is performed only on the front wheels, regardless of whether the braking is slow or fast, and the brake cylinder pressure of the rear wheels is not reduced, so braking force is secured. The increase in braking distance is kept small. If the pressure in the front wheel brake cylinder is reduced, the vibration in the longitudinal direction (parallel to the road surface) and the vibration caused by pitching will be reduced, but this will reduce the pressure only in the front wheel, causing the lever and the rear of the vehicle to sink as mentioned above. becomes larger. However, since the front part of the car body is originally in a low position and the rear part is high on the descent road, even if the rear part sinks significantly, the car body will only approach a horizontal position and will not cause much discomfort to the passengers.

Effects of the Invention As described above, according to the present invention, by controlling the front wheel pressure reducing device and the rear wheel pressure reducing device in accordance with the slope of the road surface, excessive braking distance can be avoided on both uphill and downhill roads. Stopping feeling can be improved without causing any elongation.

EXAMPLE Hereinafter, an example in which the present invention is applied to a two-system anti-lock type hydraulic brake system for a four-wheel vehicle will be described in detail with reference to the drawings.

In FIG. 2, 10 is a brake pedal as an operating member, and when the brake pedal 10 is depressed, a mask cylinder 12 is operated. The mask cylinder 12 is equipped with two mutually independent pressurizing chambers, and the brake pedal 1
The same level of hydraulic pressure is generated in each pressurizing chamber based on the zero depression operation. The liquid pressure generated in one pressurized chamber is
The liquid is supplied from the main liquid passage through the proportioning/bypass valve 14 to the front wheel cylinders 2022 of the brakes provided on the left and right front wheels 16 and 18, respectively. The fluid pressure generated in the other pressurizing chamber is supplied from the main fluid passage through the proportioning/bypass valve 14 to the brake cylinders 28 and 30 provided on the left and right rear wheels 24 and 26, respectively. Ru. This brake system has two systems, front and rear, with one mask cylinder and one
2 front wheel cylinder 2022, rear wheel cylinder 28, 30, etc. constitute a fluid pressure brake system. Note that the proportioning/bypass valve 14 is
When the front system is normal, it proportionally reduces the brake fluid pressure in the rear system, and when the front system fails, it plays the role of directly supplying the brake fluid pressure from the mask cylinder 12 to the Yavoir cylinder 28.30. It is something that we fulfill.

Mask cylinder 12 and front wheel cylinder 20.
There is an ionizing liquid pressure control valve 3 in the middle of the main liquid passage connecting the 22.
2.34 is provided. These electromagnetic hydraulic pressure control valves 32
．． 34 is a pressure increasing state in which the hydraulic pressure of the front wheel cylinder 20.22 is increased by supplying brake fluid from the mask cylinder 12, and a pressure increasing state of the front wheel cylinder 20.22 is increased.
It is possible to switch between a reduced pressure state in which brake fluid is discharged from the brake fluid 22 to reduce its hydraulic pressure, and a holding state in which the front wheel cylinders 20 and 22 are not communicated with either of them and the fluid pressure is maintained at a constant state. .

The second main liquid passage is divided into a mask cylinder side passage 36 and a wheel cylinder side passage 38, 40 by providing an electromagnetic hydraulic pressure control valve 32.34. .40
A return passage 42,44 is connected between the two. These return passages 42, 44 each have a wheel cylinder side passage 38, 40 and a mask cylinder side passage 36.
Check valves 46, 48 are provided to allow brake fluid to flow to the brake fluid, but to prevent flow in the opposite direction.

There is also a bypass passage 52.5 between the mask cylinder side passage 36 and the wheel cylinder side 3 passage 38.40.
4 is provided. These bypass passages 52, 54 are provided with check valves 56, 58, respectively, and are also commonly provided with a normally open electromagnetic on-off valve 60, when brake fluid is supplied to the front wheel cylinders 20, 22. The brake fluid is supplied at a sufficient flow rate through both the electromagnetic control valves 32 and 34 and the electromagnetic shut-off valve 60.

The electromagnetic hydraulic pressure control valve 32.34 has a reservoir passage 64.
66 is connected to a reservoir 68, and when the electromagnetic hydraulic pressure control valve 32.34 is switched to the reduced pressure state on the aromatic side in the figure, the brake fluid discharged from the freon 1 to the wheel cylinder 20.22 is It is designed to be stored in a reservoir 68.

The reservoir passage 64.66 is connected to the wheel cylinder 20.2.
It has a cross-sectional area through which the brake fluid discharged from No. 2 flows at a flow rate necessary for pressure reduction for anti-skid control. The brake fluid stored in this reservoir 68 is pumped up by a pump 70 equipped with a check valve and driven by a motor 69, and passed through a pump passage 72 to the mask cylinder side passage 36.
is being supplied to. In the pump passage 72,
A check valve 7 is connected to a damper 74 for reducing discharge pulsation of the pump 70 and prevents brake fluid from flowing back from the mask cylinder side passage 36 to the damper 74.
6 is provided.

Although the front system has been described above, the rear system is also similar to the front system. However, the hydraulic pressures of the rear wheel cylinders 28, 30 are commonly controlled by one electromagnetic hydraulic pressure control valve 84. Mask cylinder side passage 86. Wheel cylinder side passage 88. Return passage 90.
Check valve 92 Reservoir passage 94. Reservoir 96. pump 9
8° pump passage 100. Damper 102. A check valve 104 is provided. The electromagnetic hydraulic pressure control valve 84, like the electromagnetic hydraulic pressure control valves 32.34, is switched between a pressure increasing state, a pressure decreasing state, and a holding state, and the hydraulic pressure of the rear wheel cylinder 28.30 is controlled. In this embodiment, the electromagnetic hydraulic pressure control valves 32 and 34 constitute a pressure reducing device for the front wheels, and the electromagnetic hydraulic pressure control valve 84 constitutes a pressure reducing device for the rear wheels. In addition, from the mask cylinder side passage 86 to the wheel cylinder side passage 8
There is no normally open electromagnetic on-off valve that allows the supply of brake fluid to 8.

The rotational speeds of the left and right front wheels 16.18 and the left and right rear wheels 24.degree. 26 are detected by rotation sensors 110, 112.degree.
18. The slip ring calculating unit 118 calculates wheel rotation speed, deceleration, vehicle body speed, wheel slip rate, etc., and the anti-skid control unit 120 controls the electromagnetic hydraulic pressure control valves 32 and 34 based on the calculation results. and 84 are switched and controlled, and the wheel 16.1B.

24. Keep the slip of 26 within the proper range.

As shown in FIG. 3, the anti-skid control unit 120 includes a CPU 122. ROM124. It includes a RAM 126 and a bus 128 that connects them. Lotus 12
8 is connected to an input interface 130, and the input interface 130 is connected to the slip type cylinder calculation unit 1.
18. A brake switch 132 that detects depression of the brake pedal 10. A road surface gradient sensor 134 and a suspension control unit 136 are connected. The road surface slope sensor 134 includes a vibrator or rotor that maintains a horizontal posture even when the vehicle body is tilted due to the slope of the road surface, and a detector that tilts integrally with the vehicle body. The pitching amount is corrected based on the vehicle height, and the road surface slope θ is detected. lotus 1
An output interface 140 is further connected to 28, and a drive circuit 142 is connected to this output interface 140.
．． The electromagnetic hydraulic pressure control valves 32, 34.84 and the motor 69 are connected via 144, 146 and 148.

Further, the ROM 124 stores various routines necessary for braking, such as an anti-slip control routine and an anti-sway control routine shown in the flowchart of FIG. 7.

Vehicles equipped with this hydraulic brake system are equipped with an electronically controlled air suspension system 1 as shown in Fig. 74.
50, so that the spring constant, damping force, and vehicle height of the suspension can be automatically changed according to driving conditions. This air suspension device 150
The vehicle has a pair of front suspension units 152 and a pair of rear suspension units 153 provided between the left and right front wheels 16 and 18 and the left and right rear wheels 24 and 26, respectively, and the vehicle body. The configurations of these suspension units 152 and 153 are almost the same, and the front suspension unit 152 will be described as a representative example.

The front suspension unit 152 includes a shock absorber 154 and an air spring unit 156, as shown in FIG. As shown in FIG. 6, the shock absorber 154 has an inner cylinder 160 housed within an outer cylinder 158, and a reservoir chamber 1 between the cylinders 158 and 160.
A piston 164 is fluid-tightly and slidably fitted into an inner cylinder 160, and a cylindrical piston rod 166 has a peripheral wall thereof. An orifice is formed that penetrates in the radial direction, and damps vibrations by restricting the flow rate of oil flowing between the piston upper chamber 168 and the piston lower chamber 170.

Three sets of orifices are formed in the piston rod 166 at distances apart in the vertical direction, and the piston rod 166
Together with the orifice of the control rod 172 rotatably fitted therein, the damping force switching valve 174 is configured. The control rod 172 has a cylindrical shape and has three sets of orifices spaced apart downwardly. A pair of orifices having the same flow area are formed on the upper and lower sides, and a pair of orifices having the same flow area as the upper and lower orifices is formed in the middle.
A pair of orifices with a smaller flow path area are formed.

An actuator 176 for switching the damping force of the second solenoid is provided at the upper end of the control rod 172.
By rotating the control rod 172, a pair of upper and lower orifices formed on the control rod 172 and a pair of middle orifices with a large flow passage area are connected to three sets of orifices formed on the piston rod 166, respectively. communicated,
In a state where the amount of oil passing through is increased, communication between the upper and lower orifices of the piston rod 166 is cut off, and among the intermediate orifices, only the orifice with a small flow path area is allowed to communicate. Switching between a state in which the amount of oil passing is reduced and a state in which communication between all orifices is cut off and passage of oil is prevented,
Thereby, the damping force of the shock absorber 154 is switched to three levels: low, medium, and high.

As shown in FIG. 5, the air spring unit 156 has a cylindrical piston 180 fixed to the outer cylinder 158 of the shock absorber 154, and both ends of the air spring unit 156 are supported by the piston 180 and a screw-on rod 166 of the shock absorber 154. A variable volume chamber 184 is formed within the rolling diaphragm 182. The variable volume chamber 184 is connected to the zero resub tank 188 through a tube 186, and to a compressor 194 through a front hide control valve 190 and an air solenoid valve 192 having a dryer as shown in FIG.
The compressed air produced in The subtank 188 is provided with a spring constant switching valve 198 as shown in FIG. This valve 19
8 is provided at the connecting end of the tube 186 to the sub-tank 188, and has a cylindrical member 202 rotatably fitted within the casing 200. Two types of openings, large and small, with different areas are provided in the peripheral wall of the cylindrical member 202 at a distance in the circumferential direction.The cylindrical member 202 is rotated by a spring constant switching actuator 204, and the two types of openings are opened in the casing 200. A state in which the variable volume chamber 184 and the subtank 188 are communicated with each other at a large flow rate by being selectively aligned with an opening formed in the opening formed in the casing 200, or a state in which the variable volume chamber 184 and the subtank 188 are communicated with each other at a large flow rate;
The state is switched to a state where communication is cut off, and the spring constant is switched to three stages: low, medium, and high. When the variable volume chamber 184 and the sub-tank 188 are communicated with each other at a large flow rate, the flow resistance of the compressed air flowing from the variable volume chamber 184 to the sub-tank 188 is small, and the spring constant is low. The flow resistance increases and the spring constant becomes medium, and when the communication is cut off, there is no flow of compressed air from the variable volume chamber 184 to the sub-tank 188, and the spring constant becomes high.

Note that the vehicle height is determined by the variable volume chamber 1 of the air spring unit 156.
By supplying compressed air to 84 from a compressor 194 through the dryer and front hide control valve 190 and discharging it from an air solenoid valve 192, three stages can be achieved.

The rear suspension unit 153 has a similar structure, except that a spring constant switching actuator 210 (see FIG. 4) is provided at the upper end of the shock absorber 154 together with a damping force switching actuator 2-2 (not shown). Also, compressed air is supplied via the height control hub 212.

The damping force switching actuator 176, the front hide control sensor 190. Air solenoid valve 1
92. Spring constant switching actuators 204, 210.
The rear hide control valve 212 and the like are controlled by the suspension control unit 136. The suspension control unit 136 is CI) U, although not shown.

It is mainly composed of a ROM RAM and a microphone 220 with a hub connecting them, and a throttle position sensor 220. Front hide control sensor 222. Rear hide control sensor 224. Steering sensor 226 Neutral start switch 228° Courtesy lamp switch 23
0. A stone plunge switch 232 etc. is connected, and based on the detection signals of those sensors and the signals of the switch,
The spring constant, damping force, and vehicle height are controlled to appropriate heights depending on the vehicle speed, transmission range selection, road surface irregularities, and driving conditions such as whether or not acceleration is being performed.

Hereinafter, the wobbling return prevention control will be explained based on flowchart 1 in FIG. 7.

This anti-wobble routine is started when the brake pedal 10 is depressed. First, step Sl (hereinafter, S
It is abbreviated as l. The same goes for other steps. ), the deceleration G is read from the slip multicycle calculation unit 118, and the vehicle speed (2) is read in S2, and then it is determined in S3 whether or not to start the sway return prevention control.

This determination is made based on whether the vehicle speed (2) is less than or equal to the reference vehicle speed determined from the deceleration G based on the straight line i in FIG. When the deceleration G is large, the wheel cylinder pressure is high and the driver intends to stop the vehicle quickly.The straight line P is set so that the reference vehicle speed increases as the deceleration G increases. In contrast, when the actual vehicle speed (2) is within the range shown by diagonal lines, the sway return prevention control is performed. 2 representing this straight line ℃ is stored in the ROMI 24, and it is determined whether the vehicle speed ■ is less than the reference vehicle speed determined for the deceleration G, and if it is larger than that, S3
becomes NO, and then from 31 until S3 becomes YES.
S3 is repeatedly executed.

When the vehicle speed V becomes equal to or less than the reference vehicle speed determined for the deceleration G, the gradient θ of the road surface is read in S4, and it is determined in S5 whether the gradient θ is approximately 0, that is, whether the road surface is a horizontal surface. It will be done. Road slope sensor 13
4 is configured to emit a positive signal when the gradient θ is on the uphill road, and a negative signal when it is on the downhill road.
If the road surface is a descending road, S5 becomes NO, S6 also becomes NO, and 87 is executed, and the spring constant and damping force of the rear suspension unit 153 are set to be high. These spring constants and damping forces are normally set to intermediate magnitudes, and the suspension control i unit 136 controls the damping force switching actuator 176 and the spring constant based on the command signal issued at 37 of the anti-skid control unit 120. The switching actuator 210 is actuated and the spring constant and damping force are set high.

Also, in S8, front suspension unit 1
The spring constant and damping force of 52 are set to an intermediate value.

Next, in S9, the electromagnetic hydraulic pressure control valves 32 and 34 are switched to a reduced pressure state, and the front wheel cylinders 20.
The pressure in the rear wheel cylinder 28.30 is reduced, the vehicle is stopped with less wobbling, and the pressure in the rear wheel cylinder 28.30 is reduced.
Since the pressure is not reduced, excessive extension of the braking distance is prevented. In addition, if only the pressure in the front wheel cylinders 20 and 22 is reduced, the rear of the vehicle will sink more when stopped (although this should occur because the spring constant and damping force of the rear suspension unit 153 are set high). This suppresses the vertical movement of the rear of the vehicle, allowing the vehicle to stop without sinking.

Note that the time 6 from when a signal commanding the spring constant and damping force height is issued in S7 until the damping force switching valve 174 and the spring constant switching valve 198 switch to the state corresponding to the command is 150 m5. Although the time from when the pressure reduction command is issued in S9 until the electromagnetic hydraulic pressure control valves 32 and 34 switch to the pressure reduction state is longer than 50 m5, the spring constant and damping force are set prior to pressure reduction. Therefore, when the vehicle comes to a stop, the spring constant and damping force commanded in S7 are obtained, and the function of mitigating the vertical movement of the vehicle body when the vehicle is stopped can be achieved.

Then, SIO is repeatedly executed until the vehicle stops and the vehicle speed V becomes 0, and when the vehicle stops, in S11, the front and rear suspensions are
The spring constant and damping force of 3 are returned to steady state, and S12
At this point, the electromagnetic hydraulic pressure controls 32 and 34 are returned to the pressure increasing state, and the swing back prevention control is completed.

If the road is a boardwalk, θ is a positive value and S6 is YE.
S, the spring constant and damping force of the rear suspension unit 153 are set high in 313, and S1
After the spring constant and damping cuff of the front suspension unit 152 are set to intermediate values in S15, the electromagnetic hydraulic control valves 32, 34, 84 are switched to a reduced pressure state, and the front and rear wheel cylinders 20, 22 and 28 ．．
30 pressure is reduced. This reduces back-and-forth swing and pitching-induced swing back. Also,
Compared to the case where only the front wheel cylinders 20 and 22 are depressurized, the rear part of the vehicle body sinks less, and in addition,
Since the spring constant and damping force of the rear suspension unit 153 are set high, the sinking of the rear part of the vehicle body is thereby alleviated, and the vehicle can be stopped with little vertical movement.

If the road is level, S5 becomes YES, and it is determined in S16 whether or not sudden braking is required. This determination is made based on whether the deceleration G read in step 31 immediately before the start of the wobbling return prevention control when the determination result in S3 is YIES is greater than the set deceleration CyTH. The set deceleration GTH is set to approximately 0.4 g, and if the deceleration G is greater than the set deceleration GT, sudden braking is performed and S17 is executed, and the spring constant and damping force of the front suspension unit 152 are is set high, and the spring constant and damping force of the rear suspension unit 153 are set to an intermediate value in S18, and then the pressures in the front and rear wheel cylinders 2022 and 28.30 are reduced in S19. During sudden braking, the wheel cylinder pressure is high, and by controlling the four wheel metal parts to reduce the pressure, it is possible to stop the vehicle with less wobbling.Also, although the load is transferred to the front of the vehicle, the spring constant of the front suspension unit 152 and Since the damping force is set high, vertical movement of the front of the vehicle is alleviated, which also reduces wobbling.

Further, if braking is performed gently on a horizontal road, S16 becomes NO, and S20. In S21, the front and rear suspension units 152, 1 respectively
The spring constant and damping force at 53 are set to intermediate, and at 322 the front wheel cylinder 20.2
Pressure reduction control is performed only for No. 2. During gentle braking, the wheel sealing pressure is low, so the rear wheel cylinder is 28°30°
The spring constant of the suspension unit 152, 153 can be stopped even if the braking distance is suppressed and the braking distance is not extended, and the load shift during stopping is not so large. Even if the damping force is set to an intermediate value, the vehicle body will be stopped with less movement.

As is clear from the above explanation, in this example,
S1 to S3 of the ROM 124. SIO~S12 and S1
A portion of the CPU 122 that stores steps 6 to S22 and a portion of the CPU 122 that executes these steps constitutes a stop control means.
A portion of the OM 124 that stores S4 to S9 and 313 to S15 and a portion of the CPU 122 that executes these steps constitute a road slope stop control means.

In the above embodiment, the slope is detected by the road surface slope sensor 134, but as described in Japanese Patent Application Laid-Open No. 1-164656, when the fluid pressure of the fluid pressure brake system reaches 0. It has a fluid pressure detection means for detecting the size of the vehicle, and a deceleration detection means for detecting the deceleration of the vehicle without being affected by the longitudinal tilt of the vehicle. It is possible to adopt road surface inclination determination means that determines the road surface condition by comparing the deceleration detected by the deceleration detection means with the deceleration detected by the deceleration detection means on a horizontal road correspondingly set in advance. a first deceleration detection means that detects the deceleration of the vehicle without being affected by the longitudinal inclination of the weight; and a second deceleration detection means that detects the deceleration of the vehicle based on the chronic force generated in the weight. It is also possible to employ road surface inclination determining means that determines the road surface condition by comparing the detection results of the first and second deceleration detecting means.

In addition, in the embodiment mentioned above, all pressure reduction controls were performed in the same pressure reduction pattern, but for example,
The pressure reduction pattern may be changed depending on the situation as described in Japanese Patent Application Laid-open No. 1-164656.

Furthermore, in the above embodiment, it is determined whether or not to start the sway return prevention control based on the relationship between the deceleration G and the vehicle speed ■, but when the vehicle speed V is a constant value, for example 5 km, The depressurization may be started when the speed drops to 5 km/h or less, or it may be started after waiting for a set time after the speed drops to 5 km/h or less.

Further, in the above embodiment, the spring constant and damping force of the front and rear suspensions can be changed depending on the slope of the road surface, but this suspension control may be omitted.

In addition, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing the configuration of the present invention. FIG. 2 is a system diagram of a vehicle brake system which is an embodiment of the present invention. FIG. 3 is a block diagram showing the structure of the anti-skid control unit 1 of the vehicle brake system mentioned above. FIG. 4 is a diagram schematically showing the electronically controlled air suspension system installed in the vehicle. FIG. 5 is a front sectional view showing the front suspension unit of the air suspension device. FIG. 6 is a front sectional view showing a shock absorber constituting the front suspension unit. FIG. 7 is a flowchart showing a swing back prevention control routine stored in the ROM of the computer that constitutes the main body of the anti-skid control unit. FIG. 8 is a graph illustrating the execution timing of the wobbling return prevention control. FIGS. 9 and 10 are diagrams for explaining sinking and lifting of the vehicle body when both the front and rear wheel brakes are activated and when only the rear wheel brake is activated, respectively. 10 Brake pedal 16: Left front wheel] 8: Right front wheel 20 22: Front wheel cylinder 24; Left rear wheel
26: Right rear wheel 28 3o: Rear wheel cylinder 32, 34, 84: Electromagnetic hydraulic control valve 120: Anti-skid control unit 3 36 50 52 53: Suspension control unit: Electronically controlled air suspension device: Front suspension unit: Rear The suspension unit

Claims (1)

[Scope of Claims] Pressure is applied to the front brake cylinder of the brake that suppresses the rotation of the front wheels and the rear brake cylinder of the brake that suppresses the rotation of the rear wheels in accordance with the operation amount such as the operation force and operation stroke of the brake operation member, respectively. a front wheel pressure reducing device and a rear wheel pressure reducing device capable of reducing the pressure of the front brake cylinder and the pressure of the rear brake cylinder, respectively; Stop control that automatically reduces the pressure of the brake cylinder by controlling the front wheel pressure reducing device and the rear wheel pressure reducing device after the vehicle speed becomes equal to or less than a reference value, thereby reducing swaying back when stopped. In the vehicle brake system, the vehicle braking device includes slope detection means for detecting whether the road surface is an uphill road or a downhill road, and the stop control means includes a pressure reduction for the front wheels when the road surface is an uphill road. A road surface in which both the device and the rear wheel pressure reducing device are made to reduce the pressure, and when the road surface is a drop-off road, the front wheel pressure reducing device is made to reduce the pressure, but the rear wheel pressure reducing device is not allowed to reduce the pressure. A vehicle brake device having a sway return prevention function, characterized in that it is provided with a stop control means when tilting.