JPH066425B2 - Anti-skidding control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is characterized by driving control of a pump for collecting brake fluid provided in a brake fluid recovery path from a wheel cylinder to a master cylinder in a vehicle brake hydraulic system. An anti-skid control device having

[Prior Art] Generally, a friction coefficient μ between a wheel and a road surface in a vehicle becomes a maximum μ (max) at a predetermined slip ratio λo (about 15%) as shown in FIG. Maximum efficiency. Therefore, in the normal anti-skid control, when the vehicle is being braked, the braking hydraulic pressure is controlled to be increased, reduced, or maintained so that the slip ratio of the wheel is always a value near the slip ratio λo. As a result, the stopping distance during braking can be shortened and
It is possible to secure driving stability.

Conventionally, as this type of anti-skid control device, for example, there is one as shown in FIG. 6 (JP-A-58-61054, JP-A-58-56949, etc.). This is because an inflow valve 4 (hereinafter referred to as an EV valve 4) that opens and closes the hydraulic pressure transmission path from the master cylinder 2 of the braking hydraulic system to the wheel cylinder 3.
Is provided on the brake fluid recovery path from the wheel cylinder 3 to the master cylinder 2, and an outflow valve 5 (hereinafter referred to as an AV valve 5) for opening and closing the brake fluid recovery path is provided. A reservoir tank 16, a pump 6 for collecting the braking fluid, and a check valve 1 are provided downstream of the AV valve 5.
7 is provided. Then, when the vehicle is braked, the anti-skid control circuit 1 is based on the detection signal of the frequency proportional to the rotation speed of the wheel 20 output from the wheel speed sensor 1.
0 controls the drive of the EV valve 4 and the AV valve 5, and also controls the drive of the motor 13 that drives the hydraulic pressure recovery pump 6.

Here, when the control signal (hereinafter referred to as an EV signal) of the EV valve 4 from the anti-skid control circuit 10 is at the H level,
The EV valve 5 closes the hydraulic pressure transmission path, and the EV signal becomes L
While the hydraulic pressure transmission path is opened at the time of the level, the control signal of the AV valve 5 from the anti-skid control circuit 10 (hereinafter referred to as A
When the V signal) is at the H level, the braking fluid recovery path is opened, and when the AV signal is at the L level, the braking fluid recovery path is closed. That is, the hydraulic pressure (braking hydraulic pressure) of the wheel cylinder 3 is controlled by the EV signal and the AV signal as shown in the following table.

Further, the control of the motor 13 that drives the pump 6 for collecting the brake fluid provided in the brake fluid recovery path is performed according to the above table.
The V valve 4 and the AV valve 5 are subject to drive control, that is, the start of anti-skid control. For example, the motor 13 is operated from the pressure reduction control for the first time after the anti-skid control starts to the end of the anti-skid control. I'm trying to continue.

In this manner, when the pump 6 is driven by the operation of the motor 13 with the start of the anti-skid control as a starting condition, for example, when the anti-skid control is started from the first pressure reduction control until the end of the anti-skid control, the anti-skid control is performed. Even if the EV valve 4 and the AV valve 6 are controlled to be switched at high speed, the braking fluid pressure can be reliably switched to increase, decrease, or hold in accordance with the control.

[Problems to be Solved by the Invention] However, when the anti-skid control start of the motor 13 for driving the pump 6 is set as the starting condition as described above, for example, the wheel deceleration becomes the predetermined deceleration b1 during braking. As shown in FIG. 7, in the anti-skid device in which the switching control of the EV valve 4 and the AV valve 5, that is, the anti-skid control is started when it reaches, as shown in FIG. In the case where the wheel speed rapidly increases, when the wheel deceleration reaches the predetermined deceleration b1 at the time t0 when the wheel speed returns, the anti-skid control starts, and thereafter, the rotation state of the wheel (wheel acceleration / deceleration). When the speed, slip ratio, etc.) are reduced by the braking fluid pressure, the pump 6
(Motor 13) starts up. Therefore, since the unnecessary pump 6 (motor 13) is started during steady running, there is a problem such as waste of battery power or increase in vehicle interior noise during steady running. Furthermore, the pump driving motor 13 and The pump 6 itself is required to have relatively high durability.

[Means for Solving Problems] In view of the above problems, the present invention provides a brake fluid recovery pump provided in a brake fluid recovery path from a wheel cylinder to a homaster cylinder in a brake fluid pressure system only when necessary. An object of the present invention is to provide an anti-skid control device that can be activated, and in order to achieve this object, the present invention provides a hydraulic pressure transmission path from a master cylinder to a wheel cylinder in a vehicle braking hydraulic system and a wheel cylinder. An actuator for opening and closing the brake fluid recovery path to the master cylinder and a brake fluid recovery pump provided downstream of the actuator in the brake fluid recovery path are provided, and drive control of the actuator and pump is performed. In the anti-skid control device, the hydraulic pressure between the actuator and the pump in the above-mentioned braking fluid recovery path is predetermined. And a drive control means for performing drive control of the pump based on the determination output from the hydraulic pressure determination means.

[Operation] When the hydraulic pressure between the actuator and the pump in the braking fluid recovery path actually becomes equal to or higher than the predetermined hydraulic pressure due to the brake fluid pressure reduction control in the anti-skid control, the motor for driving the pump concerned Is started.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an example of the basic configuration of an anti-skid control device according to the present invention. In this example, the two front wheels and the rear wheels are independently anti-skid controlled. In the figure, for the left front wheel system, an EV valve 4a is provided in the hydraulic pressure transmission path from the master cylinder 2 linked to the brake pedal to the wheel cylinder 3a, while the EV cylinder 4a is connected to the master cylinder 2 from the wheel cylinder 3a.
An AV valve 5a, a reservoir tank 7, a pump 8 for collecting the brake fluid, and a check valve 10 are provided in the brake fluid recovery path up to. As for the right front wheel system, as in the left front wheel system, an EV valve 4b is provided in the hydraulic pressure transmission path from the master cylinder 2 to the wheel cylinder 3b, while the braking fluid from the wheel cylinder 3b to the master cylinder 2 is provided. The collection path is provided with an AV valve 5b, a reservoir tank 16 shared by the left front wheel system, a pump 8 and a check valve 10. Furthermore, for the rear wheel system, the master cylinder 2
To the wheel cylinders 3c provided corresponding to the left and right wheels,
An EV valve 4c is provided in the hydraulic pressure transmission path to 3d, while an AV valve 5c and a reservoir tank 1 are provided in the braking fluid recovery path from the wheel cylinders 3c and 3d to the master cylinder 2.
1, a pump 9 for collecting the braking fluid and a check valve 12 are provided. The pumps 8 and 9 for collecting the braking fluid are driven by the motor 13 at the same time.

Further, in FIG. 1, 14 is a pressure sensor for detecting the hydraulic pressure between the AV valves 5a, 5b and the pump 7 in the braking fluid recovery path common to the left front wheel system and the right front wheel system, and 15 is the rear wheel system. AV valve 5c and pump 9 in the braking fluid recovery path
It is a pressure sensor that detects the fluid pressure between and. Reference numeral 100 is an anti-skid control circuit. This anti-skid control circuit 100 inputs a detection signal from a wheel speed sensor 1a provided corresponding to the left front wheel via a port P1 for the left front wheel system. , This wheel speed sensor 1a
Based on the detection signals from the EVs, the EVs serving as the control signals from the ports P6 and P7 to the EV valve 4a and the AV valve 5a, respectively.
A signal and an AV signal are output, and for the right front wheel system, the detection signal from the wheel speed sensor 1b provided for the right front wheel is input through the port P2, and the wheel speed sensor 1b outputs the signal. EV valve 4 based on the detection signal
b to AV valve 5b to EV from ports P8 and P9 respectively
A signal and an AV signal are output. Further, the anti-skid control circuit 100 inputs the detection signal from the wheel speed sensor 1c provided corresponding to the rear wheel (for example, the right rear wheel) via the port P3 for the rear wheel system,
Based on the detection signal from the wheel speed sensor 1c, the ports P10 and P11 are connected to the EV valves 4c and AV valves 5c, respectively.
While outputting the V signal and the AV signal, the detection signals from the pressure sensors 14 and 15 are output to the ports P4 and P5, respectively.
The control voltage is applied to the motor 13 from the port P12 based on the detection signals from the pressure sensors 14 and 15.

Here, the specific configuration of the anti-skid control circuit 100 is as shown in FIG. 2, for example. Although FIG. 2 shows only one system of the rear wheel system with respect to the hydraulic control, the other systems have the same configuration. In the figure, 101 is a wheel speed calculation circuit that calculates the wheel speed based on the detection signal from the wheel speed sensor 1c that is input via the port P3, and 102 is a derivative of the detected wheel speed signal from the wheel speed detection circuit 101, for example. It is an acceleration / deceleration detection circuit that processes and detects the acceleration and deceleration (negative acceleration) of the wheel. Reference numeral 103 denotes a pseudo vehicle speed generation circuit that generates a pseudo vehicle speed Vi (pseudo vehicle speed) necessary for detecting the slip ratio λ, and 104 denotes that the deceleration detected by the acceleration / deceleration detection circuit 102 is a reference deceleration b1 or more. When the b1 signal from the comparison circuit 104 is input, the pseudo vehicle speed generation circuit 103 outputs, for example, from the wheel speed detection circuit 101 at that time, every time the b1 signal from the comparison circuit 104 is input. A pseudo vehicle speed Vi that is a speed straight line having a predetermined constant inclination from the detected wheel speed value that is output, or a speed straight line that connects the detected wheel speed when the b1 signal was input last time and the detected wheel speed this time. The pseudo vehicle speed Vi is output. Reference numeral 105 denotes a target wheel speed generation circuit, and the target wheel speed generation circuit 105 has a slip ratio λo λo = 1- (Vwo / Vi) at which the braking efficiency is near the maximum based on the pseudo vehicle speed Vi from the pseudo vehicle speed generation circuit 103. The target wheel speed Vwo which is the control target corresponding to is output. Specifically, since λo is about 0.15 (15%), the calculation of Vwo = Vi × 0.85 is performed and the calculated value is output. It is like this.

106 is a target wheel speed V from the target wheel speed generation circuit 105.
wo and the detected wheel speed Vw from the wheel speed detection circuit 101 are input, and when the detected wheel speed Vw is below the target wheel speed Vwo, a comparison circuit for outputting an H level signal (hereinafter referred to as a slip signal), 107 A comparison circuit 108 which outputs an H level signal (hereinafter referred to as a1 signal) when the detected acceleration from the speed detection circuit 102 becomes equal to or higher than the reference acceleration a1.
Like the comparison circuit 104, is a comparison circuit that outputs an H level signal (b1 signal) when the detected deceleration from the acceleration / deceleration detection circuit 102 becomes the reference value b1 or more. Then, the inverted signal of the a1 signal from the comparison circuit 107 and the comparison circuit 106
The AND signal (AV signal) from the AND gate 109 with the slip signal from the input signal is input from the port P11 to the AV valve 5c after passing through the driver 111b, and the comparison circuit 10
OR gate 110 of a1 signal from 7 and b1 signal from comparison circuit 108 and output signal from AND gate 109
The OR signal (EV signal) is transmitted from the port P10 to the EV valve 4c after passing through the driver 111a.

On the other hand, reference numeral 112 is a comparison circuit which outputs an H level signal when the detected value from the pressure sensor 14 input through the port P4 is equal to or higher than a predetermined reference pressure value Pth (experimentally determined), 113 Is a comparison circuit that outputs an H level signal when the detection value from the pressure sensor 15 input via the port P5 is equal to or greater than the reference value similar to the above, and the outputs of the comparison circuits 112 and 113 are the OR gates 11.
4 and a resistor R, and is connected to the base of the switching transistor Tr. The emitter of the switching transistor Tr is grounded, and its collector is connected to the circuit power supply Vcc via the relay coil 115a in the relay 115. Further, the circuit power Vcc is supplied to the power terminal of the motor 13 from the port P12 after passing through the contact 115b of the relay 115.

Next, the operation of this device will be described with reference to the timing chart shown in FIG.

First, the normal anti-skid control will be described.

When the driver depresses the brake pedal (time t0) and the braking hydraulic pressure (the hydraulic pressure in the wheel cylinders 3c, 3d) rises,
Along with this, the wheel speed decreases and the wheel deceleration (negative acceleration) increases. Here, when the wheel deceleration further increases and reaches the predetermined value b1 (time t1), the b1 signal is output from the comparison circuit 108, and the b signal via the OR gate 110 is output.
The EV signal 4c is activated by the 1 signal (EV signal), and the braking fluid pressure is maintained at that time. At this time, when the wheel deceleration reaches the predetermined value b1, the pseudo vehicle speed generation circuit 103
From the detected wheel speed at that time, the pseudo vehicle speed Vi having a predetermined inclination is output, and at the same time, the target wheel speed generation circuit 10
5 to the target wheel speed Vwo (Vi
× 0.85) are output sequentially. Then, when the wheel speed is further reduced due to the holding of the braking hydraulic pressure at a high hydraulic pressure as described above and falls below the target wheel speed Vwo (time t2), the comparison circuit 10
6, a slip signal is output, and the slip signal (AV signal) via the AND gate 109 causes the AV valve 5c.
Is activated, the operation of the EV valve 4c is held by the slip signal (EV signal) via the OR gate 110, and the braking hydraulic pressure is reduced. When the braking fluid pressure is reduced in this way, the wheel speed and the wheel acceleration are restored accordingly, and when the wheel acceleration reaches the predetermined value a1 (time t
3), the a1 signal is output from the comparison circuit 107, and the EV is generated by the a1 signal (EV signal) via the OR gate 110.
While the operation of the valve 4c is further maintained, the AND gate 109 is brought into the prohibited state by the a1 signal, the AV valve 5c is returned to the initial state, and the braking hydraulic pressure is maintained. If the braking hydraulic pressure is maintained even though the hydraulic pressure is relatively low in this way, it starts to decrease again when the wheel speed exceeds the target wheel speed (the slip signal disappears at this point) to some extent. The wheel acceleration also decreases from the above value a1 or more. Here, when the wheel acceleration falls below the predetermined value a1 (time t4), the a1 signal from the comparison circuit 107 falls, and each comparison circuit 1 at that time point.
Combined with the outputs from 06 and 108 being L level, the EV signal and the AV signal become L level, and the braking fluid pressure is increased again. Then, the wheel speed and the wheel acceleration further decrease, and thereafter, the same control of the brake hydraulic pressure as described above is sequentially repeated.

That is, the switching control of the braking hydraulic pressure during the braking is performed according to the control mode determined based on the wheel acceleration / deceleration αw and the slip ratio λ (actually Vw / Vi) as shown in FIG.

For example, at time t in the process of anti-skid control as described above.
In the brake fluid pressure reduction control starting from 2, the EV valve 4c closes the hydraulic pressure transmission path of the rear wheel system, and the AV valve 5c opens the brake fluid recovery path of the same system. The braking fluid in 3d flows out to the reservoir tank 11 side via the AV valve 5c by the action of its own hydraulic pressure. Then, the hydraulic pressure value detected by the pressure sensor 15 increases, and when the hydraulic pressure value becomes equal to or higher than the predetermined pressure value Pth, the comparison circuit 113 outputs the H level indication,
The comparison circuit 112 through the OR gate 114 and the resistor R
The switching transistor Tr is turned on by the H level signal from the power source, and the power supply Vcc is supplied to the relay coil 115a. And this relay coil 115a
The relay contact 115b is closed by the power supply to the motor 13, the power Vcc is supplied to the motor 13, and the motor 13 operates.

On the other hand, the pump 9 accompanying the operation of the motor 13 as described above
When the braking fluid in the wheel cylinders 3c, 3d is being collected by the operation of (the pump 8 is also operated), for example, if the AV valve 5c closes the braking fluid recovery path at time t3 (holding the braking fluid pressure). (Holding control), the hydraulic pressure detected by the pressure sensor 15 decreases, and when the detected pressure value falls below the predetermined pressure value Pth, the output of the comparison circuit 113 falls. The switching transistor Tr is turned off due to the fall of the output of the comparison circuit 113, the relay contact 115b is opened, and the power supply to the motor 13 is cut off. Therefore, the operation of the motor 13 is stopped, and accordingly, the operation of the pump 9 is also stopped (the pump 8
Will also stop).

Although the above operation is intended for the rear wheel system only, the same anti-skid control is actually performed for the left front wheel system and the right front wheel system, and in the process of the anti-skid control, the pressure sensor is operated. When the detected hydraulic pressure value from 15 becomes equal to or higher than the predetermined pressure value Pth, the output of the comparison circuit 112 becomes H level, and based on the output from this comparison circuit 112, the power supply control to the motor 13 similar to the above is performed. Be done. That is, the motor 13 is driven when at least one of the pressure sensors 14 and 15 detects the hydraulic pressure equal to or higher than the predetermined pressure value Pth.

As described above, according to this embodiment, the pressure sensor 14 (15) is provided between the AV valve 5a (5b, 5c) and the braking fluid recovery pump 8 (9) in the braking fluid recovery path of the braking fluid pressure system. )
Is provided and the motor 13 for driving the pump is operated when the hydraulic pressure detected by the pressure sensor 14 (15) becomes equal to or higher than the predetermined pressure Pth. Therefore, for example, as shown in FIG. Even if the anti-skid control circuit 100 becomes a condition for starting the anti-skid control during steady running and the control signals for the AV valve and the EV valve are output from the anti-skid control circuit 100 (anti-skid control start), the motor 13 for driving the pump is not operated. Absent.

In the above embodiment, the hydraulic pressure between the AV valve, which is an actuator in the braking fluid recovery path, and the pump is directly detected, and based on the detected value, it is confirmed that the hydraulic pressure at that position is equal to or higher than a certain pressure. In the present invention, the strokes of the reservoir tanks 7 and 11 in FIG. 1 are detected without being limited thereto, and the AV valve and the pump are detected based on the detected values. It may be possible to determine that the fluid pressure between them has become equal to or higher than a certain pressure.

Although the OR signal of the output signals from the comparison circuits 112 and 113 is used to control the motor 13 for driving the pump, the OR gate for outputting the OR signal is further provided for a predetermined time (normal anti-skid). It is also possible to provide a retriggerable timer in which a time longer than the pressure reduction control cycle in control is set and control the motor 13 by the output of the retriggerable timer. With this configuration, during the anti-skid control, the motor 13 continues to operate from the time of the first pressure reducing control until the end of the anti-skid control.

[Effects of the Invention] As described above, according to the present invention, when the hydraulic pressure between the actuator and the pump in the braking fluid recovery path of the braking hydraulic system becomes equal to or higher than a predetermined hydraulic pressure, Since the pump is started, the pump for collecting the braking fluid does not operate unnecessarily, and along with that, it is possible to prevent waste of battery power, increase in vehicle interior noise during steady running, etc. It is also advantageous in terms of durability of the pump driving device such as a motor and the pump itself.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of the overall configuration of an antiskid control device according to the present invention, FIG. 2 is a block diagram mainly showing the rear wheel system of the antiskid control circuit in FIG. 1, and FIG. Timing charts showing the operation of the anti-skid control device shown in FIGS. 1 and 2, FIG. 4 is an explanatory diagram showing a control mode of the brake hydraulic pressure by the anti-skid control circuit shown in FIG. 2, and FIG. 5 is a wheel. FIG. 6 is a graph showing the relationship between the friction coefficient μ between the road surface and the road surface and the slip ratio λ, FIG. 6 is a block diagram showing an example of a conventional anti-skid control device, and FIG. It is explanatory drawing which shows the example of a case. 1a, 1b, 1c ... Wheel speed sensor 2 ... Master cylinder 3a, 3b, 3c, 3d ... Wheel cylinder 4a, 4b, 4c ... Inflow valve (EV valve) 5a, 5b, 5c ... Outflow valve (AV valve) 7, 11 ... Reservoir tanks 8, 9 ... Pumps 10,12 ... Check valves 13 ... Motors 14,15 ... Pressure sensors 100 ... Anti-skid control circuits 101 ... Wheel speed detection circuits 102 ... Acceleration / deceleration detection circuits 103 ... Pseudo vehicle speed generation circuits 104, 106, 107, 108 ... Comparison circuit 105 ... Target wheel speed generation circuit 111a, 111b ... Driver 112, 113 ... Comparison circuit 114 ... OR gate 115 ... Relay 115a ... Relay coil 115b ... Relay contact Tr ... Switching transistor

Claims (1)

[Claims] 1. An actuator for opening and closing a hydraulic pressure transmission path from a master cylinder to a wheel cylinder and a braking fluid recovery path from the wheel cylinder to the master cylinder in a vehicle braking hydraulic system, and an actuator downstream of the braking fluid recovery path. An anti-skid control device having a pump for collecting braking fluid provided, and performing drive control of the actuator and pump, wherein the hydraulic pressure between the actuator and the pump in the braking fluid recovery path is It is characterized in that it is provided with a hydraulic pressure discrimination means for discriminating that the hydraulic pressure exceeds a predetermined hydraulic pressure and a drive control means for controlling the drive of the pump based on the discrimination output from the hydraulic pressure discrimination means. Anti-skid control device.