JPS62275870A - Vehicle skid control device - Google Patents

Abstract

PURPOSE:To reduce the change in yawing of a vehicle during high speed running by assuming an integral control of a right and a left wheel in such a way so to meet a wheel which is more easily locked out of a right and a left front wheel for a predetermined period of time, in stead of an independent control of the right and left front wheels. CONSTITUTION:A hydraulic pressure adjusting means B adjusting brake oil pressure from a brake oil pressure generating source A such as a master cylinder and the like to a right and a left wheel braking means, and each oil pressure adjusting means C1 and C2 which adjusts braking pressure to a right and a left front wheel braking means independently, are provided. And the oil pressure adjusting means B is controlled by an integral control means D in such a way as to meet a wheel which is more easily locked out of a right and a left rear wheel. And based on the output from a vehicle speed detecting means E and each rotational condition detecting means F1 and F2, when the vehicle speed is equal to or more than a predetermined value, the braking pressure to each braking means for front wheels is integrally controlled in such a way as to meet a wheel which is more easily locked out of a right and a left front wheel by an integral control means G for a predetermined period of time before the right and left front wheels are independently controlled.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention The present invention relates to a wheel skid control device that prevents the left and right front and rear wheels from locking during braking to improve safety during braking. be.

(Prior art) Braking of a vehicle is performed by trying to stop the rotation of the wheels using brake means such as disc brakes installed on the left and right front and rear wheels, and the force that tries to stop the wheels is The brake fluid pressure supplied to the means, that is, the brake pedal operating force by the driver increases, the greater the brake fluid pressure is increased. On the other hand, substantial braking of a vehicle depends on the frictional force between the wheels and the road surface. Therefore, if the force that attempts to stop the wheels increases unnecessarily, ignoring the frictional force of the road surface, the wheels become locked.

In this way, when the wheels become locked during braking,
This causes undesirable behavior from a safety standpoint, such as the braking distance becoming longer or the vehicle not turning in the steered direction.

For this reason, recently, a system called ABS (anti-lock brake system), which electronically optimally controls the brake fluid pressure supplied to the brake means within a range where each wheel does not lock, has become widespread. This A
In a BS, basically, the brake fluid pressure supplied to each brake means is adjusted according to the output from a rotation state detection means that independently detects the rotation state (generally, rotation speed) of each wheel. This is done by

The control for adjusting the brake fluid pressure is performed using the formula: S = ((VB-Vtl)/VB)X100%, where VW is the rotational speed of the wheels, VB is the vehicle speed, and S is the slip rate. The slip rate is calculated based on the slip rate, and ABS control is performed when the slip rate is in the range of, for example, 10 to 20%. In other areas, the brake fluid pressure generated by the driver's brake operation is directly applied to the brake system. We are trying to supply it to

Among the ABS controls mentioned above, there is a so-called 4-sensor-3-channel system in which the left and right front wheels are individually ABS controlled, while the left and right rear wheels are controlled in an integrated manner depending on which wheel is more likely to lock. There is a system (for example, see Japanese Patent Laid-Open No. 140154/1983). This system has the advantage that it can effectively prevent yaw changes of the vehicle when the ABS is activated, and that the control system is relatively simple because the left and right rear wheels are controlled in an integrated manner. In other words, for example, if the right wheel is in contact with a high-grade road surface with a high coefficient of friction, and the left wheel is in contact with a paper road surface with a low coefficient of friction, and the ABS is activated, the left and right rear wheels will Since it is integrated control, there is no difference in braking force between the left and right wheels, and yaw changes of the vehicle due to the difference in braking force between the left and right rear wheels are prevented. Furthermore, since the left and right front wheels, which have a heavy braking load, are independently controlled, it is possible to obtain the maximum braking force depending on the road surface and maintain a shortened braking distance.

(Problem to be solved by the invention) By the way, vehicles that are close to 1h1 often travel at extremely high speeds, and when traveling at these high speeds, especially when traveling at extremely high speeds as seen in some countries. However, there is a problem in that the yaw change when the ABS is activated gives the driver a feeling of great anxiety. In other words, even if only the rear wheels are integrated, the left and right front wheels are controlled independently, so when the road surface is asymmetrical, as mentioned above, there will be a difference in braking force between the left and right front wheels. The difference in braking force between the left and right front wheels appears as a change in the vehicle's yaw. This yaw change due to the difference in braking force between the left and right front wheels does not actually pose a problem when the traveling speed is low, partly because the psychological burden on the driver is small. However, when driving at high speeds, not only does the psychological burden on the driver become extremely large, but at the beginning of a yaw change, a phenomenon in which the steering wheel is turned toward the side with the greater braking force occurs in the form of a kick pack. For this reason, it tends to be difficult to appropriately deal with this yaw change in a general dry eight. In particular, when driving at high speeds, slight differences in the left and right suspension geometry, slight differences in performance between the left and right braking means, etc. tend to become noticeable as a difference in braking force between the left and right, so some kind of countermeasure is desired in this regard. It will be.

In order to solve this problem, we also changed the left and right front wheels.
It may be possible to perform integrated control in the same way as the left and right rear wheels, but in this case the braking distance would be considerably longer, making it practically difficult to adopt.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a Sugirad control system for a vehicle that can significantly reduce yaw changes of the vehicle during high-speed driving without sacrificing braking distance.

(Means and actions to solve the problem) In order to achieve the above-mentioned object, the present invention is based on the premise that the left and right rear wheels are controlled in an integrated manner, while the left and right front wheels are controlled independently. When the vehicle is running at a high speed where the vehicle speed is above a predetermined value, instead of controlling the left and right front wheels independently, the left and right front wheels are controlled in an integrated manner for a predetermined period of time in accordance with the wheel that is more likely to lock.

Specifically, as shown in Fig. 7, there is a brake fluid pressure generation source that generates brake fluid pressure for the brake means provided on each of the left and right front and rear wheels when the driver operates the brake, and a brake fluid pressure source for each of the wheels. rotational state detection means that are provided individually and independently to detect the rotational state of the corresponding wheels; and a rear wheel brake that adjusts the brake fluid pressure from the brake fluid pressure generation source to the left and right rear wheel brake means. a hydraulic pressure adjusting means; a brake hydraulic pressure adjusting means for each of the left and right front wheels that independently adjusts the brake hydraulic pressure from the brake hydraulic pressure generation source to the left and right front wheel brake means; Receiving the output from the rotational state detection means, the rear wheel brake fluid pressure adjustment means is controlled in accordance with the wheel that is more likely to lock among the left and right rear wheels, and the brake fluid pressure is adjusted to the brake means of the left and right rear wheels. In response to the output from the left and right rear wheel integrated control means that integrally controls the left and right rear wheels, and the left front wheel rotation state detection means, the left rear wheel brake fluid pressure adjustment means is controlled to control the brake fluid to the left front wheel brake means. In response to outputs from the left front wheel independent control means for independently controlling pressure and the right front wheel rotation state detection means, the right front wheel brake fluid pressure adjustment means is controlled to apply a brake to the right front wheel brake means. an independent control means for the right front wheel that independently controls hydraulic pressure; a vehicle speed detection means that detects the vehicle speed; and an output from the vehicle speed detection means and each rotation state detection means for the left and right front wheels, and when the vehicle speed is equal to or higher than a predetermined value. In this case, before performing independent control by the left and right independent control means, for a predetermined period of time, the brake fluid pressure to each brake means for the left and right front wheels is controlled in an integrated manner according to the wheel that is more likely to lock among the left and right front wheels. Integrated control means for front wheels.

This is a configuration equipped with the following.

With this configuration, when ABS is initially activated during high-speed driving, not only the left and right rear wheels but also the left and right front wheels are controlled in an integrated manner, making it possible to suppress vehicle yaw changes to a significantly small level. . This integrated control is carried out only for a predetermined period of time, after which the left and right front wheels are integrated as before, so that the braking distance is also satisfactory.

(Example) Examples of the present invention will be described below based on the attached drawings.

In Figure 1, IFL is the left front wheel, IFR is the right front wheel, and I
RL is the left rear wheel, and IRR is the right rear wheel.

For each wheel IFL, IFRlIRL, IRR, a brake means 2FL, 2FR12RL or 2FR is provided with a wheel cylinder, such as a disc brake or a drum brake, and is operated in response to brake fluid pressure.
RR is provided. For each of these wheels, a sensor 3FL, 3FR13RL, or 3RR is provided independently for detecting the rotational speed as the rotational state of the wheel.

Reference numeral 4 denotes a mask cylinder (hereinafter referred to as MC) as a brake fluid pressure generation source, and when the driver depresses the brake fluid pressure 5, this depressing force is boosted by a booster 6 and transmitted to the MC 4. As a result, brake fluid pressure corresponding to the depression force is generated within the MCA. The MC 4 is of a tandem type having two discharge ports 4a and 4b, and a pipe 11 extending from the discharge port 4a is branched into two in the middle, and one branch pipe 11a is connected to the left front wheel brake means 2FL. , the other branch pipe 11b is the brake hand j12 for the right rear wheel.
Connected to RR. In addition, the pipe 12 extending from the discharge port 4b is also branched into two in the middle, and one branch pipe 12a
is connected to the right front wheel brake means 2FH, and the other branch pipe 12b is connected to the left rear wheel brake means 2RL.

Branch pipes 11a, 1 for front wheels in the pipes 11.12
2a includes a control valve (hereinafter referred to as CV) 13FL or 1 as a brake fluid pressure adjusting means, respectively.
3FR is connected. In addition, the branch pipe 11b (12b) for the rear wheel in the pipe 11 (12) is equipped with a
R (13RL) and proportioning valve 14RR (
14RL) are connected in series. As is known, the proportioning valve 14RR114RL adjusts the ratio of the brake fluid pressure between the front wheels and the rear wheels.

Each of the CVs 13 has the same configuration, so the details thereof will be explained focusing on the left front wheel CV 13FL with reference to FIG. 2 as well.

First, the CV 13 FL is constructed by a casing 21 that combines two casing components 21A and 21B, and inside this casing 21 there is a first cylinder chamber 22 in the upper part of the figure, and a first cylinder chamber in the lower part. A two-cylinder chamber 23 is defined. A control piston 24 is slidably inserted into the first cylinder chamber 22 , and the upper part of the control piston 24 is connected to the control liquid chamber 25 .
A variable volume chamber 26 is located below. A control port 27 is opened in the control fluid chamber 25, and a brake fluid pressure outlet 28 is opened in the variable volume chamber 26, which is connected to the left front wheel brake means 2FL.

On the other hand, the second cylinder chamber 23 communicates with the variable volume chamber 26 through a communication port 29, and a cut-off valve (hereinafter referred to as COV) is installed in the second cylinder chamber 23.
30 are configured. This C0V30 has a stepped piston 31 consisting of a large diameter part, a medium diameter part, and a small diameter part, and the large diameter part of the stepped piston 31 is connected to the second cylinder chamber 22.
It is said to be able to slide freely inside. In addition, the stepped piston 31 has a small diameter portion extending into the communication port 29 in an M-fitting state, and a first liquid passage 3 connected to the communication port 29 around the medium diameter portion.
2 is formed. This first fluid passage 32 is always in communication with an inlet 33 into which brake fluid pressure from the MC 4 is introduced, and when the stepped piston 31 is in the state shown in FIG. Communication between the communication port 29, that is, the variable volume chamber 26, and the inlet port 33 via the first liquid passage 32 is blocked by the sealing material 34 as a valve body provided in the first liquid passage 32. Further, when the stepped piston 31 is lowered from the state shown in FIG. 2, the communication port 29 and the inflow port 33 are communicated with each other via the first liquid passage 32 (see FIG. 1).

On the other hand, a mechanism for bypassing the communication port 29 to connect and disconnect the variable volume chamber 26 and the inflow port 33 is provided by the stepped piston 3.
1. That is, a gT22 liquid passage 35 consisting of a large diameter portion and a small diameter portion is formed in the stepped piston 31, and this second liquid passage 35 is connected to the first liquid passage 35 through an opening 36.
The liquid passage 32 is always in communication with the inlet 33, and is opened and closed by a valve body 37 having an inverted letter shape. This valve body 37 is urged upward in FIG. 2 by a spring 38, and at the end of its upward stroke shown in FIG. (the inflow port 33 is blocked), and when it is displaced downward from this state, it becomes open. The upper ends of the valve body 37 and the stepped piston 31 project slightly into the variable volume chamber 26 when at the upper stroke end, and the valve body 37 projects further than the stepped piston 31. It is supposed to be done. Therefore, as the control piston 24 descends from the state shown in FIG. 2, the valve body 37 is first pressed downward, and then the stepped piston 31 is pressed downward. Note that the lower part of the stepped piston 31 is
As will be described later, this is a liquid chamber 39 for applying pressure to press the stepped piston 31 upward, and a boat 40 is opened in the liquid chamber 39 . Also, 41.4 in Figure 2
2 is a notch.

The CV 13FL configured as described above takes the following four operating modes depending on the mode of supply of control hydraulic pressure to the control liquid chamber 25.

■When the brake fluid pressure from the time when ABS non-BS is not activated is supplied as it is to the left front wheel brake means 2FL. At this time, as shown in FIG. 1, the control fluid pressure is supplied to the control fluid chamber 25. Been,
As shown in FIG. 1, the control piston 24 is at its downward stroke end. At this time, the inlet 33, the variable volume chamber 26, and the outlet 28 are connected to the first liquid passage 32. Communication port 29
, are communicated via the notch 42, while the first liquid passage 32,
They are also communicated through the opening 36, the second liquid passage 35, and the notch 41. Therefore, the brake fluid pressure generated by NC4 is supplied to the brake means as it is without being adjusted by CV13FL.

(During absolute ABS operation (depressurization)) As the liquid pressure in the control liquid chamber 25 is reduced, the control piston 24 is displaced upward, and as shown in FIG. In addition, the variable volume chamber 26 is expanded by 1 with the displacement of the control piston 24. Therefore, the brake fluid pressure to the brake means 2FL for the left front wheel IFL is increased by this expansion. will be depressurized.

■When ABS is activated (maintained) The depressurization of the above (Φ) is commensurate with the expansion of the volume M variable chamber 26, so the control is performed in the state shown in FIG. If the control piston 24 is stopped by stopping the adjustment of the hydraulic pressure in the hydraulic fluid chamber 25, the brake hydraulic pressure of the brake means 2FL-5 is maintained as it is.

(When carrying ABS is activated (pressure increase) From the state of (■) above, supply hydraulic pressure to the control liquid chamber 25,
Control piston 24 is lowered. As a result, the volume of the variable volume chamber 26 is reduced, and the brake fluid pressure to the brake means 13FL is increased by this reduction (the inlet 33 and the variable volume chamber 26 remain blocked).

Note that when returning to the state (2) from the above state (2), (3), or (2), the valve body 37 is first displaced downward as the control piston 24 descends, thereby connecting the inlet port 33 and the variable volume chamber 26. By communicating with each other, the subsequent downward displacement of the stepped piston 31 can be performed with a small force.

Referring again to FIG. 1, an electromagnetic switching means 51FL is provided to control the supply and discharge of hydraulic pressure to and from the control liquid chamber 24 of the CV 13FL as described above. This switching means 51FL is composed of two solenoid valves 52 and 53, one of which is a TL magnetic valve 52 serving as a discharge valve, and the other solenoid valve 53 serving as a supply valve. That is, the control liquid chamber 24 is
connected to a reservoir 54 via a discharge valve 52;
It is connected to an accumulator 55 via a supply valve 53. A predetermined hydraulic pressure is maintained in the accumulator 55 using a pump 57 driven by a motor 56. That is, the accumulator 55
The pressure (holding pressure) is detected by a pressure switch 58, and the pump 57 is driven or stopped depending on the operation of this switch 58. The pressure of the accumulator 55 is constantly supplied to the liquid chamber 39 of the CVI3FL, so that the stepped piston 31 is always activated upward in FIG. 2 as described above. Of course, this upward biasing of the stepped piston 31 +7) may be performed using a spring, but if the pressure of the accumulator 55 is used as in the embodiment, the pump 57 will not malfunction. When ABS control cannot be performed normally, the stepped piston 31 is lowered due to a drop in the fluid pressure in the fluid chamber 39, and the inflow a33 and outflow a2B are constantly communicated to ensure braking force. This is preferable from a safety standpoint. In addition, 59. in Figure 1.
60 is a check valve, and 61 is a relief valve.

Here, the four operating modes of CV13FL mentioned above ■, ■,
The relationship between (1), (2) and the operation mode of both valves 52 and 53 is summarized as follows.

■AES not activated Both valves 52 and 53 are closed.

■AES operation (depressurization) The discharge valve 52 is open and the supply valve 53 is closed.

■ABS operation (maintained) Both valves 52 and 53 are closed.

q> p, s s operation (pressure increase).

The discharge valve 52 is closed and the supply valve 53 is open (supply via check valve 53a).

The operations of the CV13FL and the switching means 51FL explained above are similar to those of the other CV13FL3RL and 13RR.
The same applies to the 51FR151R that corresponds to the 51FL, but since the brake fluid pressure for the rear wheels is always controlled integrally on the left and right sides, the two C
It can be used for both V13RL and 13RR.

In FIG. 1, 70 is a control unit configured by a microcomputer, for example, and this control unit 41 includes:
In addition to the outputs from the sensors 3FL, 3FR13RL, and 3RR, the output from a vehicle speed sensor 71 that detects vehicle speed is input. Further, the control unit 70 outputs an output to each switching means 51FL, 51FR151R.

In the control unit 70, based on the output of each sensor 3FL etc. that detects the rotational state of the wheels, when the vehicle speed is below a predetermined value (for example, 150 km/h), as in the conventional case,
The brake fluid pressure for the left and right rear wheels is integrated and controlled according to the rear wheel that is more likely to lock (slip), and the brake fluid pressure for the left and right front wheels is controlled independently.

In addition, when the vehicle speed is above a predetermined value, the brake fluid pressure for the left and right front wheels is integratedly controlled for a predetermined period of time (for example, 1 second) in accordance with the front wheel that is more likely to lock.
After this predetermined time has elapsed, the left and right rear wheels are controlled independently as in the past (the left and right rear wheels are always on the integrated side m).

The details of the control performed when the vehicle speed is above a predetermined value will be explained with reference to FIGS. 3 to 5. First, it is assumed that the right wheel of the vehicle is in contact with the road surface for use, and the left wheel is in contact with the road surface for other use, as shown in FIGS. 754 and 5. When the driver strongly depresses the brake pedal 5 in order to suddenly decelerate in this state, the brake fluid pressure (here, the pressure applied to the brake means 3FL, etc.) increases as the depressing force increases. When the left front wheel IFL on the substitute side is about to lock due to this increase in brake fluid pressure (at the time of FIG. 3 to), the brake fluid pressure is reduced for both the left and right front wheels (ABS operation). Then, when a predetermined time period has elapsed (time t1 in FIG. 3), the brake fluid pressures for the left and right front wheels are controlled independently from each other. During this independent control, it is harder to lock the right front wheel IFH than the left front wheel IFL, so after t1 in Figure 3,
The brake fluid pressure for the right front wheel is controlled to be greater than the brake fluid pressure for the left front wheel.

Here, the magnitude of the braking force of each wheel is shown as F・FL, FΦFR, F No. RL, and F@RR in FIGS. 4 and 5, respectively, and the state from to to Ll is shown as In addition, the state after t1 is shown in FIG.

In this way, since the brake fluid pressure of the left and right front wheels is also integrally controlled from to when ABS operation starts to predetermined time t1, the large braking difference between the left and right front wheels that occurs especially when ABS operation starts is eliminated, and the vehicle Yaw changes can be significantly reduced.

By the way, the conventional system in which the left and right front wheels are always controlled independently is shown by the broken line in Figure 3. In this case, the right front wheel IFH, which is difficult to lock, is affected by the ABS operation at time t2 when the ABS operation starts for the right front wheel IFH. It is understood that there will be an extremely large "difference" between the brake fluid pressure for the front left wheel and the brake fluid pressure for the left front wheel, which has already been significantly reduced due to ABS operation, and a considerable change in yaw cannot be avoided.

The flowchart shown in FIG. 6 shows the braking when the vehicle speed is above a predetermined value. In addition, in the following explanation, P
indicates a step.

First, the vehicle speed V is read at Pl, and then it is determined at P2 whether the vehicle speed V is greater than a predetermined value of 150 Km/h. In this P2 determination, ■
If it is determined that ≧150Km+/h, P3
, it is determined whether an ABS signal has been generated for either the left or right front wheels (normally ABS braking starts with pressure reduction, so for example, it is sufficient to check whether a signal for this pressure reduction has been output). be done. When an ABS signal is generated for either the left or right front wheels, an ABS signal is also generated for the other front wheel at P4.

In this P4, the integrated control of the left and right front wheels is started, but after this, in P5, it is determined whether a predetermined time has elapsed (whether or not t1 in Fig. 3 has elapsed), and it is determined that the predetermined time has elapsed. At P6, the left and right front wheels are independently controlled as in the past. Of course, in P2, ■≧15
When it is determined that the speed is not 0 km/h, left and right independent control is performed as in the conventional case.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

(2) Since various types of means for adjusting the brake fluid pressure to each wheel (brake means) constituted by CV13FL etc. have already been put into practical use, any suitable type can be adopted.

■In the example, the brake piping system was made independent for the left and right rear wheels, so the left and right CV13s were installed independently, but if this brake piping system is common for the left and right rear wheels, one CV13
It can also be used for both purposes.

(2) When the control unit 70 is configured by a computer, it may be either a digital type or an analog type.

(Effects of the Invention) As is clear from the above description, the present invention can significantly reduce the yaw change of the vehicle during high-speed driving without sacrificing the braking distance.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the control valve for adjusting the brake fluid pressure shown in FIG. 1. FIG. 3 is a graph showing the details of control according to the present invention in comparison with a conventional one. FIGS. 4 and 5 are diagrams showing the control details according to the present invention in relation to the braking force acting on each wheel. FIG. 6 is a flowchart showing a control example of the present invention. FIG. 7 is an overall configuration diagram of the present invention. IFL: Front left wheel IFR: Front right wheel LRL: Rear left wheel IRR: Rear right wheel 2FL nib brake means 2 F R: // 2 RL; // 2 RR: tt 3FL: Sensor (for rotation state detection) 3 F R : //3 RL
: //3 RR: // 4: Mask cylinder (brake phosphorus pressure generation source) 5 Brake pedal 13FL: Control valve 13 FR: // 13 RL: // 13 RR: /1 51FL: Switching means 51 FR : /1 51 R: /1 52: For discharge '11! Magnetic valve ('IJE, for pressure) 53: Supply TL magnetic valve (for pressure increase) 70: Control unit 71: Sensor (for vehicle speed detection) 3rd @ Fig. 4. Figure 5

Claims (1)

[Claims] (1) A brake fluid pressure generation source that generates brake fluid pressure for the braking means provided on each of the left and right front and rear wheels when the driver operates the brake; rotational state detection means for detecting the rotational state of the wheels; rear wheel brake fluid pressure adjustment means for adjusting the brake fluid pressure from the brake fluid pressure generation source to the left and right rear wheel brake means; and the brake fluid pressure Receiving outputs from brake fluid pressure adjustment means for each of the left and right front wheels that independently adjusts brake fluid pressure from a generation source to the brake means for the left and right front wheels, and rotation state detection means for each of the left and right rear wheels; Integrated control for the left and right rear wheels, which controls the rear wheel brake fluid pressure adjustment means in accordance with the wheel that is more likely to lock among the left and right rear wheels, and integrally controls the brake fluid pressure to the brake means of the left and right rear wheels. and a left front wheel receiving an output from the left front wheel rotation state detection means and controlling the left rear wheel brake fluid pressure adjusting means to independently control the brake fluid pressure to the left front wheel brake means. a right front wheel that receives an output from the independent control means and the right front wheel rotation state detection means and controls the right front wheel brake fluid pressure adjusting means to independently control the brake fluid pressure to the right front wheel brake means; independent control means for the left and right wheels; vehicle speed detection means for detecting vehicle speed; and upon receiving outputs from the vehicle speed detection means and the respective rotation state detection means for the left and right front wheels, when the vehicle speed is equal to or higher than a predetermined value, the left and right independent control means Integrated control means for left and right front wheels for a predetermined period of time before performing independent control, for integrated control of the brake fluid pressure to each brake means for the left and right front wheels in accordance with the wheel that is more likely to lock among the left and right front wheels. A vehicle skid control device characterized by: