JPH0396464A - Control device for car braking - Google Patents

Abstract

PURPOSE:To prevent the lowering of the performance of ABS(antiskid braking system) control when a full rebound state is detected on any wheel, by controlling braking force for the other wheels through the antiskid braking system. CONSTITUTION:When a controller 10 for ABS(antiskid braking system) control detects that any of wheels 4L, 4R, 6L, 6R has turned into a full rebound state from signals issued by a cylinder pressure sensor 23 and a height sensor 24, rotating speed information sent from a wheel speed sensor 9 is neglected about the above wheel, and car speed is computed only from the wheel rotating speed information of the other three wheels. Brake control done through the antiskid braking system is executed only for the above three wheels on the result of the above computation. Thus the lowering of performance of the antiskid braking system can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a braking control device for a vehicle, and more specifically,
The present invention relates to a braking control device for a vehicle equipped with an anti-skid braking system that individually and variably controls the braking force of each front, rear, left, and right wheel acting on the road surface.

<Prior Art> As a brake system for a vehicle, for example, Japanese Utility Model Application No. 62-122765 discloses a system that detects the rotational speed of each front, rear, left and right wheel during braking, and also calculates a pseudo vehicle speed from the rotational speed information of these wheels. Based on the results of comparing this pseudo-vehicle speed with the rotational speed information of each wheel, braking control is performed to prevent the wheels from locking, and the slip ratio is set so that each wheel exerts the optimum braking force depending on the road surface condition. discloses an anti-skid braking system that individually controls the brake pressure applied to each wheel. This prevents the vehicle body from skidding due to the tendency of the wheels to lock, especially during braking operations on low-μ roads, and also shortens the braking distance.

Active suspension systems that control wheel suspension devices in response to changes in vehicle height while the vehicle is running are also known. For example, in Japanese Patent Publication No. 59-14365, when a change in vehicle height is detected, A vehicle height control device has been disclosed that generates an operating force based on this and applies it to a suspension device to control the vehicle height. Vehicles equipped with such active suspension systems can control the vehicle height with good responsiveness to vehicle height changes that occur during braking, acceleration, and turning, thereby improving the vehicle's running stability and dynamic characteristics. and ride comfort can be improved.

(Problem to be Solved by the Invention) By the way, in a vehicle equipped with the above-mentioned anti-skid braking system, during the operation of the system, the front, rear, left and right wheels may change due to changes in road surface conditions or vehicle running conditions. , full rebound condition on either wheel,
In other words, it is conceivable that the fluid pressure cylinder in the wheel suspension system is extended to its full stroke, and the wheel supported by it is fully extended with respect to the vehicle body. If we assume that the wheel is in such a full rebound state, there is a very high possibility that the wheel is not firmly in contact with the road surface.

Therefore, even if the rotational speed of a wheel that is likely not in contact with the ground is detected, the obtained rotational speed information is uncertain information, just like a wheel that may be in a non-contacted state, and it cannot be used as is. Even if the vehicle speed is calculated by combining it with the rotational speed information of other wheels, it will only include an error in the calculation, which will only become an obstacle to estimating the vehicle speed accurately. Even if the braking force of each wheel is controlled based on the vehicle speed, it is difficult to expect accurate operation of the anti-skid braking system, and this will only lead to a decline in the performance of the system. Therefore, the present invention aims to eliminate the rotational speed information obtained from the wheel when a full rebound state of any wheel occurs during the operation of the anti-skid braking system, and to obtain the rotational speed information obtained from the remaining wheel. An object of the present invention is to provide a braking control device for a vehicle that estimates vehicle speed from speed information and uses it to control an anti-skid braking system.

(Means for Solving the Problems) The present invention is characterized in that it is constructed as follows in order to cope with the above-mentioned problems. That is, the vehicle braking control device of the present invention has the following features: A braking control device for a vehicle equipped with an anti-skid braking system that detects rotation information of each left and right wheel and individually variably controls the braking force of these wheels, A wheel speed sensor detects the full rebound state of each wheel, a full rebound state detection sensor detects the full rebound state of each wheel, and individual braking force control is performed for each wheel based on the rotational speed information of each wheel using the detection signals of both sensors as input. and a braking force control means that performs the anti-skid braking system, and when a full rebound state is detected in any wheel, the braking force control means applies the anti-skid braking system to other wheels other than that wheel. It is characterized by being configured to perform braking force control. (Function) According to the above configuration, when the anti-skid braking system is activated, which wheel is in a full rebound state? When this is detected by the full rebound state detection sensor, the braking force control means ignores the rotational speed information of the wheel in the full rebound state even if the rotational speed information is input, and the braking force control means ignores the rotational speed information of the wheel in the full rebound state, and The vehicle speed is calculated only from the wheel rotational speed information input from the vehicle, and based on this, braking control by the anti-skid braking system is executed only for these three wheels.Therefore, the vehicle speed calculated by the braking force control means is as follows: The rotational speed information of a wheel in a full rebound state, which is highly likely not to be in contact with the ground, is no longer included. (Example) Next, an example of the present invention will be described.

Figure 1 shows the general structure of a vehicle equipped with an anti-skid braking system. In this vehicle, the output of a power plant 1 consisting of an engine and a transmission is input to a rear differential 3 via a propeller shaft 2. While preparing to drive the left and right rear wheels 4L and 4R, the rear wheels 4L
, 4R, and axles 7L, 7R of left and right front wheels 6L, 6R as driven wheels.
Disc rotors 8a...8a that rotate integrally with L, 6R, 7L, and 7R, and calibers 8b and 8a that brake the rotation of each disc rotor 8a when brake hydraulic pressure is supplied.
... 8b, etc., are respectively provided with hydraulic brake devices 8...8. And the above wheels 4L, 4R, 6L
, 6R are equipped with wheel speed sensors 9...9 for detecting the rotational speed of each wheel, and the wheel rotational speed information taken out from these wheel speed sensors 9...9 is used for anti-skid control. It is designed to be input to a controller (hereinafter referred to as an ABS control controller) 10 in the braking system. In addition to the wheel rotation speed mentioned above, the ABS controller 10 also controls G
Acceleration/deceleration signals in the longitudinal direction of the vehicle body are inputted from the sensor 11, and the ABS controller 10 receives input rotational speed information of the wheels 4L, 4R, 6L, and 6R, and acceleration/deceleration signals from the G sensor 11. The vehicle speed is calculated and estimated using
Based on the deviation from the rotational speed information of R, 6L, and 6R, the optimum braking force for each wheel is further calculated, and the calculated output is used as an output signal to be sent to each hydraulic brake device 8 through signal cables 12...12. ...8 hydraulic unit 13
...13, these hydraulic units 13...13
By varying the individual brake hydraulic pressure of the brake devices 8, 1,
8 adjusts the brake pressure applied to each wheel 4L, 4R, 6L, 6R. That is, the ABS control controller 10 determines each wheel 4L,
The hydraulic brake device 8 corresponding to each wheel calculates the slip rates of 4R, 6L, and 6R so that the slip rate of each wheel becomes a target slip rate that obtains the maximum braking force in the slip rate - braking force characteristic.・Control 8.

In FIG. 1, the ABS control controller 10 controls the brake oil pressure in the front wheel hydraulic brake devices 8, 8 independently on the left and right sides, and also controls the brake oil pressure in the rear wheel hydraulic brake devices 8, 8 independently. Controls left and right independently. FIG. 2 schematically shows the structure of an active suspension system that is installed on a vehicle together with the anti-skid braking system shown in FIG. Rear wheel 4L,
Hydraulic cylinders 15 . . . 15 as suspension devices are provided between the 4R and 4R, respectively. That is, these hydraulic cylinders 15...15 have a hydraulic chamber 15c formed in the cylinder tube 15a by a piston 15b fitted into the cylinder tube 15a.
The upper end of the piston rod 15d connected to the vehicle body 14
(The cylinder tubes 15a are connected to the respective wheels 4L, 4R, 6L, and 6R.

Further, the respective hydraulic cylinders 15 . . . 15 are communicated with and connected to corresponding gas springs 16 . These gas springs 16...
16 is internally partitioned by a diaphragm 16a into a gas chamber 16b and a hydraulic chamber 16c, of which the hydraulic chamber 16c is communicated with the hydraulic chamber 15c of the hydraulic cylinder 15 via the communication passage 17.

Furthermore, pressure oil is supplied to the hydraulic cylinders 15...15 from a hydraulic pump 18 driven by the engine power, but in that case, there is a gap between the hydraulic pump 18 and each hydraulic cylinder 15...15. Flow rate control valves 20...20 are interposed in the hydraulic pipes 19...19, respectively, and these flow rate control valves 20...20 are controlled by a controller (hereinafter referred to as ACS control controller) 21 in the active suspension system.・20 supplies and discharges pressure oil to the hydraulic chambers 15c of the corresponding hydraulic cylinders 15...15, and by supplying and discharging this pressure oil, the wheels 4L
, 4R, 6L, and 6R suspension characteristics are designed to be variable.

For such control, the ACS control controller 21 in the active suspension system includes:
Main pressure sensor 22 that detects the discharge pressure of the hydraulic pump 18
, the hydraulic pressure signal from the cylinder pressure sensor 23 that detects the hydraulic pressure in the hydraulic chamber 15c of each hydraulic cylinder 15...15, and the vehicle height of the wheels 4L, 4R, 6L, and 6R.
A vehicle height signal from a vehicle height sensor 24 that detects the cylinder stroke amount of the hydraulic cylinder 14, a vertical acceleration signal from a vertical acceleration sensor 25 that detects the vertical acceleration of the vehicle, and a vehicle speed sensor 26 that detects the vehicle speed. The vehicle speed signal is input respectively. Then, the ACS control controller 21 operates the aforementioned flow rate control valves 20 based on these input signals, and operates each hydraulic cylinder 15...
- Execute pressure oil supply and discharge control to maintain the vehicle height at the target vehicle height, control to reduce vertical vibration of the vehicle, and control for the front wheels 6L, 6R side and rear wheels 4L, 4R side. Control is performed to equalize the support load between the left and right wheels, in other words, the ground load between the left and right wheels. By the way, as shown in FIG. 3, the vehicle height sensor 24 in the above active suspension system is
For example, one end is connected to the vehicle body 14, and the other end is connected to the wheel (third
In the figure, the front wheel 4L is shown as an example.
The cylinder stroke amount accompanying the expansion and contraction of the hydraulic cylinder 14 is detected by the change in resistance value of the potentiometer. Therefore, when the detected output of the vehicle height sensor 24 is at its maximum, it can be determined that the hydraulic cylinder 15 has extended to its full stroke. In other words, the full stroke state is when the wheel is in a full rebound state, and the wheel is fully extended with respect to the vehicle body 14, so there is a high possibility that the wheel is not in contact with the road surface. Further, the cylinder pressure sensor 23 is connected to the hydraulic cylinder 15 as described above.
Since the hydraulic pressure in the hydraulic chamber 15c is detected, in this case as well, the cylinder stroke amount of the hydraulic cylinder 15 can be estimated based on the detected pressure value, and therefore, it is possible to similarly grasp the state in which the wheel is fully extended to the full rebound state. I can do it. In other words, with an active suspension system,
Hydraulic cylinder 15...1 in the direction that always keeps the wheels in contact with the ground.
5, so when the wheel reaches its full rebound state, the hydraulic chamber of the hydraulic cylinder 15 of the wheel]. Since a large hydraulic pressure is applied to the hydraulic chamber 15c, the full rebound state can be detected by detecting the hydraulic pressure in the hydraulic chamber 15c.

Taking advantage of this, the anti-skid braking system shown in FIG. 1 uses the cylinder pressure sensor 23 and vehicle height sensor 24 in the active suspension system shown in FIG.
The respective detection outputs are input to the ABS control controller 10 as shown in FIGS. 1 and 3, thereby causing a full rebound state to occur in any of the front, rear, left, and right wheels 4L, 4R, 6L, and 6R. When the anti-skid braking system is activated and a wheel full rebound condition occurs, the wheel rotation speed information input from the wheel to the ABS controller 10 is checked. , this is canceled and is not used to calculate the vehicle speed, and the vehicle speed is calculated using the wheel rotation speed information obtained from the remaining wheels that are not in a full rebound state, thereby obtaining the optimal braking force for the wheels. It is designed to control the braking force. This will be further explained with reference to the flowchart of the braking control processing operation shown in FIG. In the embodiment circuit shown in FIG. 3, both the detection output of the cylinder pressure sensor 23 and the detection output of the vehicle height sensor 24 are input to the ABS controller 10 as means for detecting the wheel full rebound state. It is also possible to use only one of the cylinder pressure sensor 23 and the vehicle height sensor 24 as the wheel full rebound state detection means. Therefore, in the flowchart of FIG. 4, the explanation of the operation will be simplified by taking as an example the case where only the vehicle height sensor 24 is used. That is, in FIG. 4, when the vehicle is running, the rotational speeds of the front, rear, left and right wheels 4L, 4R, 6L, 6R are measured by the wheel speed sensors 9... regardless of whether the anti-skid braking system is activated. 9 has been detected. In addition, the active suspension system constantly checks vehicle height displacement, and the detection signal from the vehicle height sensor 24 is input to the ACS controller 21, while the anti-skid braking system's ABSII
It is also input to the I-use controller 10 (step Sl
: The same applies hereafter). When the anti-skid braking system is activated from this state, the ABS controller 10 checks, based on input information from the vehicle height sensor 24, whether a full rebound state has occurred in any of the wheels. This check is performed by determining whether the detected cylinder stroke amount H of the hydraulic cylinder 15 obtained from the vehicle height sensor 24 is equal to or less than the maximum cylinder stroke amount H wax of the cylinder 15, and only when it is equal. It is determined that the state is full rebound (steps S2 and S3).

If a full rebound state is not detected for any wheel, braking control is performed using the normal anti-skid braking operation.

That is, the vehicle speed is calculated based on all the rotational speed information of the front, rear, left, and right wheels 4L, 4R, 6L, and 6R taken out from the respective wheel speed sensors 9...9 and the vehicle body acceleration/deceleration information from the G sensor 11. Then, by comparing the vehicle speed and the rotational speed of each wheel, it is determined whether any of the wheels is locked. If there is a wheel in a locked state, a control signal is sent to the hydraulic unit 13 of the wheel in the locked state, and the brake device 8
Adjust the brake pressure of the wheels to release the lock condition and ensure that the braking force of the wheels is applied normally to the road surface. Further, as described above, each hydraulic brake device W8...8 is controlled so that the target slip ratio for each of the wheels 4L, 4R, 6L, and 6R is achieved to obtain the maximum braking force (step S6).

However, the hydraulic cylinder 15 obtained from the vehicle height sensor 24
If there is a wheel whose stroke amount H is equal to the maximum stroke amount HoIax, and therefore the ABS controller 10 determines that the wheel is in a full rebound state, the controller 10 determines that the wheel is not in contact with the ground, and The rotation speed information of the wheels is canceled and the vehicle speed is similarly calculated using only the rotation speed information obtained from the remaining wheels, and the anti-skid braking system is applied to the remaining wheels using the vehicle speed as the calculated value. Executes braking control using In addition, regarding a wheel in a full rebound state, the brake pressure of the hydraulic brake device 8 applied to the wheel is reduced, and control is performed so that the braking force of the wheel is not applied. This is because the next time a wheel floating off the road touches the ground, if brake pressure is applied, the wheel will enter a locked state as soon as it touches the ground (step 7' S).
4S5).

When the anti-skid braking system is activated in this way, or when a wheel in a full rebound state is detected during the anti-skid braking system, the ABS control controller 10
does not use the wheel rotation speed information obtained from the wheel in question,
Since the vehicle speed is calculated using only the rotational speed information obtained from the remaining wheels, the calculated vehicle speed does not include the rotational speed information of the wheels in the full rebound state, which are most likely not in contact with the ground. The vehicle speed as a result of minute calculation becomes more accurate. Therefore, the braking control of the wheels performed using this vehicle body speed also becomes appropriate.

Note that the flowchart in FIG. 4 uses only the vehicle height sensor 24 as the full rebound state detection sensor, but when only the cylinder pressure sensor 23 is used,
Furthermore, even when both the vehicle height sensor 24 and the cylinder pressure sensor 23 are used, the function of the ABS control controller 10 is the same. <Effects of the Invention> As is clear from the above description, the present invention provides a sensor for detecting the full rebound state of each wheel in an anti-skid braking system that performs wheel braking control. Since the rebound detection signal is input to the braking force control means in the anti-skid braking system, when it is detected that a full rebound state has occurred in any wheel, the braking force control means By calculating the vehicle speed from the wheel rotational speed information, a more accurate vehicle speed can be determined. Therefore, it is possible to eliminate the performance degradation of the anti-skid braking system caused by including the rotational speed information of the wheels in the full rebound state, which are likely not in contact with the ground, into the calculation of the vehicle speed.

[Brief explanation of drawings]

The drawings show embodiments of the present invention; FIG. 1 is a schematic diagram of an anti-skid braking system, FIG. 2 is a schematic diagram of an active suspension system, and FIG. 3 is a schematic diagram of an anti-skid braking system using a part of the active suspension system. FIG. 4, which is an elliptical diagram of the main parts of the skid braking system, is a flowchart of the braking control processing operation.

Claims (1)

[Claims] (1) A braking control device for a vehicle equipped with an anti-skid braking system that detects rotation information of each front, rear, left and right wheel during a braking operation and individually variably controls the braking force of these wheels, A wheel speed sensor that detects the rotational speed of each wheel, a full rebound state detection sensor that detects the full rebound state of each wheel, and the detection signals of both sensors are used as input to determine the rotational speed information of each wheel. and a braking force control means that performs individual braking force control on the wheels, and this braking force control means includes:
A vehicle characterized in that, when a full rebound state is detected in any wheel, braking force control is performed by the anti-skid braking system on other wheels other than that wheel. Braking control device.