JPH03287438A - Turning abnormality judging device for vehicle - Google Patents

Abstract

PURPOSE:To obviate the change of the reference value according to the friction coefficient of the road surface so as to facilitate the judgement of turning abnormality by judging the generation of turning abnormality depending on whether the increase rate of lateral momentum to the increase of at least one of the body speed and the steering angle is less than the reference value. CONSTITUTION:There is provided a lateral momentum detecting means 1 for detecting lateral momentum such as the lateral acceleration and yaw rate of a vehicle. There is also provided at least one of a body speed detecting means 2 for detecting the body speed and a steering angle detecting means 3 for detecting the steering angle of a steering gear. A turning abnormality judging means 4 is further provided to judge the generation of turning abnormality to a vehicle or the tendency of generating turning abnormality when the increase rate of lateral momentum to the increase of at least one of the body speed and the steering angle is less than the reference value. In such a turning abnormality judging device, whether the tendency of generating turning abnormality is generated or turning abnormality is actually generated can be judged always on the basis of the fixed judging reference regardless of the friction coefficient of the road surface.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to an abnormal turning state that does not correspond to the operation of a steering device due to excessive wheel side slip when a vehicle turns, or a tendency thereof. This invention relates to a turning abnormality determination device that determines.

2. Description of the Related Art Japanese Patent Application Laid-Open No. 63-203456 describes a turning control device that prevents abnormal turning of a vehicle by applying a brake. In order to prevent turning abnormalities in this way, a turning abnormality determining device is required that determines whether or not turning abnormalities have occurred, the possibility of occurrence, or whether an injection amount has been generated.

The turning control device described in the above-mentioned publication is provided with a turning abnormality determination device that determines whether or not there is a possibility that a turning abnormality will occur in the vehicle based on the vehicle body speed and steering angle. When the vehicle speed is constant, the larger the steering angle is, and when the steering angle is constant, the higher the vehicle speed is, the higher the possibility of abnormal turning occurring. When taking the angle and vehicle speed, a boundary line can be drawn between the area where abnormal turning may occur and the area where there is no possibility of abnormal turning, and the point representing the actual vehicle speed and steering angle is on this boundary line. A device is provided that determines whether or not a turning abnormality is likely to occur depending on which region the vehicle belongs to.

The position of the boundary line changes depending on the friction coefficient of the road surface, so in the above device, the driver operates a switch depending on the road surface condition to select the boundary line corresponding to the friction coefficient of each road surface. A determination is made as to whether or not there is a possibility that a turning abnormality will occur based on the boundary line.

Problems to be Solved by the Invention It is complicated to change the judgment criteria according to the coefficient of friction of the road surface, and when it is done based on the driver's switch operation, there is a possibility that the driver may forget the operation or the operation may be too quick. Therefore, there is a risk that judgments may be made based on inappropriate judgment criteria. If the turning control is performed based on the result of the erroneous determination, the objective will not be fully achieved.

The present invention provides a turning abnormality that can always determine whether a tendency for abnormal turning has occurred or whether abnormal turning has occurred, regardless of the coefficient of friction of the road surface, based on a constant determination criterion. This was done with the aim of obtaining a determination device.

Means for Solving the Problems And, the gist of the present invention is to provide a turning abnormality determination device, as shown in FIG. At least one of the vehicle body speed detecting means 2 detecting the steering angle of the steering device and the steering angle detecting means 3 detecting the steering angle of the steering device, and the rate of increase of the lateral momentum with respect to an increase in at least one of the vehicle body speed and the steering angle becomes less than the reference value. The present invention further includes a turning abnormality determination means 4 for determining that a turning abnormality has occurred or is likely to occur in the vehicle when a turning abnormality occurs in the vehicle.

The turning abnormality determination means 4 determines both the rate of increase in lateral momentum with respect to an increase in vehicle speed and the rate of increase in lateral momentum with respect to an increase in steering angle, and determines a turning abnormality in the vehicle when one of them is below a reference value. Although it is desirable to determine that the occurrence or tendency to occur has occurred, it is also possible to determine only the increase rate of one of them and determine whether there is a turning abnormality based on it. For example, in order to determine a turning abnormality when the steering device is operated while the vehicle is traveling at a substantially constant speed, it is sufficient to calculate the rate of increase in the lateral momentum with respect to the increase in the steering angle. In order to determine whether a turning abnormality occurs when the vehicle is accelerated while the steering angle is constant, it is sufficient to determine the rate of increase in lateral momentum with respect to increase in vehicle speed.

When increasing the vehicle speed while keeping the effective steering angle constant, the lateral momentum will increase approximately in proportion to the vehicle speed while the vehicle speed is low, but if the vehicle speed increases and the side slip of the wheels increases,
The rate of increase in lateral momentum with respect to increase in vehicle speed gradually decreases.

This tendency remains the same whether the coefficient of friction of the road surface is high or low.

Since the rate of increase in lateral momentum is almost constant when a vehicle tends to have a turning abnormality or when a turning abnormality actually occurs, it is possible to set these values as reference values. Depending on whether the rate of increase in momentum is below the reference value, it can be determined that a turning abnormality has occurred or that a turning abnormality' has actually occurred.

A similar tendency occurs when the steering angle is increased while keeping the vehicle speed constant, and turning abnormality can be determined in the same manner.

Effects of the Invention As described above, according to the present invention, a turning abnormality can be determined based on whether the rate of increase in lateral momentum with respect to an increase in at least one of vehicle body speed and steering angle is less than or equal to a reference value. Since this reference value can be set to a constant value regardless of the level of the friction coefficient of the road surface, there is no need to change the reference value depending on the level of the friction coefficient of the road surface, making it easy to determine abnormal turning. Further, there is no need for the driver to input information regarding the coefficient of friction of the road surface by operating a switch, etc., and it is possible to avoid a situation in which a turning abnormality is incorrectly determined due to a forgotten operation or an operational error.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 2, a brake pedal 10 is connected to a mask cylinder 14 via a booster 12. The mask cylinder 14 is a tandem cylinder with two pressurized chambers,
The hydraulic pressure generated in one pressurizing chamber is transmitted to the brake 20 of the left front wheel 18 and the brake 24 of the right front wheel 22 through the main liquid passage 16, and the hydraulic pressure generated in the other pressurizing chamber is transmitted to the main liquid passage 26.
The signal is transmitted to the brake 30 of the left rear wheel 28 and the brake 34 of the right rear wheel 32. A blow-portion valve/bypass valve 36 is provided in the middle of the main liquid passage 16.26, and when the liquid pressure in the main liquid passage 16 increases normally, the liquid pressure in the main liquid passage 26 is reduced. If the hydraulic pressure in the main liquid passage 16 does not rise normally, the hydraulic pressure in the main liquid passage 26 is not reduced.

A cylinder cut valve 38, which is an electromagnetic opening/closing valve for mask cylinder cutting, is provided in a portion of the main liquid passage 26 on the downstream side of the blow-off valve/bypass valve 36, and a cylinder cut valve 38, which is an electromagnetic on-off valve for cutting the mask cylinder, is provided in a portion of the main liquid passage 26 that is divided into two. Each hydraulic pressure control valve 4
0.41 is provided. The hydraulic control valve 40.41 is connected to the reservoir 43 by a return passage 42. The hydraulic pressure control valves 40, 41 are of the same construction, and the hydraulic pressure control valve 40 is representatively shown in FIG. A spool 46 is slidably fitted into the valve hole 45 of the housing 44 in a substantially liquid-tight manner, and is normally kept in the position shown by a spring 47 to provide an output pressure boat 4 connected to the brake 3o.
8 is connected to the high pressure boat 49 to the cylinder cut valve 38.
while being in communication with the reservoir 43, it is cut off from the low pressure bow) 50 connected to the reservoir 43. A control piston 52 is opposed to one end of the spool 46 via a ball 51, and is urged toward the spool 46 by a spring 53. The elastic force of the spring 53 is significantly smaller than the elastic force of the spring 47 and can be ignored.

The hydraulic pressure of the output pressure boat 48 is made to act on the end face of the control piston 52 and the spool 46 on the opposite side from the mutually opposing sides, and the pressure receiving area Sl of the control piston 52 is larger than the pressure receiving area S2 of the spool 46. It's been made bigger. When the excitation current T is supplied to the solenoid 54, the core 55
A control force acts between the spool 46 and the spool 46 in a direction that causes them to approach each other. The magnitude of this control force is C・■ (C is a constant)
, the elastic force of the spring 47 is F, the output pressure boat 4 is
8 (hydraulic pressure of the brake 30) is expressed as PB, the spool 46.8 always moves integrally. The balance of forces on the ball 51 and the control piston 52 is F=C-1+(S,-3z)·P.

The relationship holds true, and if we solve this for P, we get P, = -C
-1/(S, -32)+F/(S, -32), and by controlling the excitation current I of the solenoid 50, the brake fluid pressure P of the output pressure boat 48 is determined.

can be controlled. The larger the exciting current I,
The hydraulic pressure Pl of the output boat 48 becomes low. In addition,
Bypass passage 56 bypassing hydraulic control valve 40.41
．． 57 is provided with check valves 58 and 59.

Cylinder force valve 38 and hydraulic pressure control valve 40 of main liquid passage 26
．． 41, an accumulator 60 is connected through an accumulator cut valve 62. Brake fluid pumped up from the reservoir 43 by the pump 64 is stored in this accumulator 6o at high pressure, and when the accumulator cut valve 62 is opened, the hydraulic control valve 4
0.41 and is supplied to the brake 30.34. 66
is a relief valve.

These cylinder cut valves 38. Hydraulic pressure control valve 40°41,
Return passage 42. Check valve 58.59 Accumulator 6
0. Accumulator cut valve 62 Pump 64. The relief valve 66 and the like constitute an actuator 68 for performing antiskin control, and the swing control device of this embodiment utilizes this actuator 68 to control the brakes 30, 34.
is used to perform turning control.

The front wheels 18.22 are steering wheels, and the steering wheel 70. Steering gear 72. steering link 74
The direction can be changed by a steering device 76 that can be controlled from the ground.

The steering angle θ of the steering wheel 7o is detected by the steering angle sensor 8.
0, the engagement of the brake pedal 10 is detected by the brake switch 82, and each wheel 18.22.2
8.32 rotation speeds are detected by rotation sensors 84, 86,
88.90, the yaw rate and lateral acceleration (hereinafter abbreviated as lateral acceleration) of the vehicle body 92 are detected by a yaw rate sensor 94 and a lateral acceleration sensor 9 fixed to the vehicle body 92.
5 and these output signals are provided to the main controller 96.

The main control device 96 is mainly a computer, and has an input interface 100. Output interface 10
2' CPU104. ROM106 and RAM10
It is equipped with B. In the ROM 106, various tables shown in FIG. 4 are stored.

It is provided with a program memory in which control programs represented by the flowcharts of FIGS. 6, 7, 8, and 9 are stored. On the other hand, as shown in FIG. 10, the RAM 108 is provided with various memories including a current vehicle speed memory 130, a control flag F, etc. together with a working memory. input interface 100
includes the aforementioned steering angle sensor 80. Brake switch 822
Rotation sensors 84, 86, 88, 90. Yaw rate sensor 94. A lateral acceleration sensor 95 and the like are connected to the output interface 102, and the cylinder cut valve 3 is connected to the output interface 102.
8. Hydraulic pressure control valves 40, 41. Accumulator cut valve 6
2 as well as a motor 182 that drives the pump 64.

Hereinafter, the operation of this swing control device will be explained based on the flowcharts shown in FIGS. 5 to 9.

The main routine for turning control, as shown in FIG. 5, includes an initial setting step SL, a turning state determination step 32. Brake fluid pressure determination step 33. The warning starts from the left/right brake switching determination step S4 and the brake fluid pressure control step S5. The initial setting step S1 is executed at the same time as the main controller 96 is powered on, and thereafter, S2 to S5 are repeatedly executed at regular intervals.

In the initial setting step S1, each memory is cleared and the control flags F, F2, . Control switching flag X
C and the two-wheel control flag XDC are turned OFF.

In the turning state determination step S2, it is determined whether or not a turning abnormality tendency has occurred based on the rate of change of the lateral acceleration LA with respect to changes in the vehicle body speed ■ and the steering angle θ (hereinafter referred to as
(simply referred to as turning abnormality determination), and if it occurs, control flags F, , F2 . F.

is turned on, and various quantities necessary for turning control are determined. When the steering angle θ is constant, the lateral acceleration ri is the 11th
As shown in the figure, while the vehicle speed ■ is low, it increases almost in proportion to the vehicle speed ■, but when the vehicle speed ■ increases and the tire skidding becomes excessive, the rate of increase in the lateral acceleration LA increases. It becomes smaller and enters the limit region shown with diagonal lines.

Steering angle θ and lateral acceleration L when vehicle speed V is constant
A similar relationship exists between A and A as shown in FIG. If the horizontal axis is the vehicle speed {circle around (2)}, and the steering angle θ is plotted on the vertical axis, the area indicated by diagonal lines in FIG. 13 is generally the limit area, and abnormal turning tends to occur in this area. In the invention disclosed in Japanese Patent Application Laid-open No. 63-203456, the presence or absence of a possibility of occurrence of abnormal turning is determined from the relationship between the vehicle speed V and the steering angle θ by focusing on this fact. The area differs depending on the magnitude of the friction coefficient μ of the road surface. Therefore, in the above invention, the driver inputs road surface μ information by operating a switch, the boundary line of the limit area is selected accordingly, and turning control is performed based on the selected boundary line. ing. However, in this case, there is a risk that the driver may not operate the switch properly, so in this embodiment, the rate of increase of the lateral acceleration La with respect to the increase in the vehicle body speed ■ and the steering angle θ is set to the 14th, respectively. As shown in Fig. 15 and Fig. 15, focusing on the fact that the vehicle speed decreases as the vehicle speed ■ and the steering angle θ increase,
Turning abnormality is determined based on whether A/Δθ becomes smaller than reference values ΔL Al and ΔLA2, respectively.

That is, the turning determination step S2 is included in each stem shown in FIG.
It is simply represented by 311. The same applies to other steps), the vehicle speed currently stored in the vehicle speed memory 130 is transferred to the previous vehicle speed memory 132, and the new vehicle speed ■ is the output of the rotation sensors 84, 86, 88, and 90. It is calculated based on the signal and stored in the current vehicle speed memory 130. Subsequently, in 312, the steering angle θ stored in the current steering angle memory 134 is transferred to the previous steering angle memory 136, and a new steering angle θ is read from the steering angle sensor 80 and stored in the current steering angle memory 134. be done.

Similarly, in S13, the lateral acceleration LA in the current lateral acceleration memory 138 is transferred to the previous lateral acceleration memory 140, and the new lateral acceleration La is read from the lateral acceleration sensor 95 and stored in the current lateral acceleration memory 138.

Next, in 314, the differences Δ■, Δθ, ΔL between the values in the previous memory and the values in the current memory are calculated for the vehicle speed ■, steering angle θ, and lateral acceleration LA, and 315.318
The difference Δθ2ΔV is a constant value Δθ3. Δ■,
It is determined whether or not it is larger than that, and only when the determination result is YES, the determination at 316° S19 is performed. This is the difference Δ
(2) If the determination of 316.319 is made when Δθ is too small, there is a risk that an erroneous determination will occur due to the influence of detection errors in the steering angle θ, etc., so this is to avoid this. Therefore, when the steering angle θ is increasing, the determination in S16 is performed, and when the vehicle speed ■ is increasing, the determination in S19 is performed, and the steering angle θ is also determined as the vehicle speed ■.
If the value is not increasing, the determinations of 316° and 319 will not be made.

If the determination results of 316 and 319 are both NO, the control flag F is set in S17 and S20, respectively.
,, F2 is turned OFF, and it is determined in 321 whether or not the control flag F is in the ON state, but since this determination result is normally No, one turning state determination is completed. .

On the other hand, if it is determined in 316 or 319 that a turning abnormality tendency has occurred, it is determined in S22 whether or not the control flag FC is ON.

This step is provided to execute S23 and S24 only when it is first determined that a turning abnormality tendency has occurred in 316 or the like. S23
In S24, the control flags F, F, and FC are turned on, and the steering angle θ and vehicle speed ■ are determined at S24.
are stored in the reference steering angle memory 142 and the reference vehicle speed memory 144 as a reference steering angle θ5 and a reference vehicle speed ■, respectively, and brake fluid pressure control gains G, , G2 are determined in S25. Lateral acceleration L
As shown in Fig. 18, the reference steering angle θ, which is the steering angle θ when the rate of increase of A becomes less than the reference value ΔLAI for the first time, is smaller on a low μ road with a low friction coefficient μ than on a high μ road. Become. When applying the brakes to perform turning control on a low μ road, if the brake fluid pressure is raised as high as on a high μ road, the turning control will become too strong and the vehicle's directional control will become unstable. .

Therefore, in S25, the reference steering angle θ5 is determined by the steering angle-gain table 110 in which the relationship between the reference steering angle θ and the control gain G shown in FIG.
The smaller the control gain G is determined, the smaller the control gain G is determined. The determined control gain G1 is stored in the gain memory 146. Furthermore, as shown in Fig. 16, the reference vehicle speed ■s is smaller on a low μ road than on a high μ road, so
Vehicle speed-gain table 11 in which the relationship between the reference vehicle speed ■ shown in FIG. 17 and the control gain C2 is tabulated.
2, the smaller the reference vehicle speed V, the greater the control gain G.
2 is determined to be small. The determined control gain G2 is stored in the gain memory 148.

Subsequently, in S26, the transmittable longitudinal force T of the tire is determined.
, is determined, and in S27 the upper limit value P of the brake fluid pressure is determined.
, is determined. As shown in FIG. 20, the larger the friction coefficient μ of the road surface, the greater the lateral acceleration LA obtained, and a larger LA means that the friction coefficient μ of the road surface is larger. Therefore, as shown in Figures 21 and 22, the greater the lateral acceleration LA, the greater the longitudinal force T that can be transmitted by the tire, and even if the brakes are applied with a higher hydraulic pressure, the wheels will not slip. Since it is not excessive,
A longitudinal force table 114 in which the relationships shown in FIGS. 21 and 22 are tabulated. Based on the hydraulic pressure upper limit table 116, the larger the lateral acceleration LA, the larger the longitudinal force TF and the brake hydraulic pressure upper limit P are determined to be. Determined longitudinal force Ty and brake fluid pressure upper limit P. are stored in the transmissible front and rear memory 150 and brake fluid pressure upper limit value 152, respectively.

As described above, after the turning state is determined, the control flags F, , F, , FC are set, and various quantities are determined in S2, the brake fluid pressure is determined in S3. The brake fluid pressure is determined by executing each step shown in FIG. First, in 331, the control flag F
It is determined whether or not C is in the ON state, and the determination result is NO.
If so, the control flag FC is turned OFF in S32, and the brake fluid pressure memories 154 to 156 (P
.

F2 and F3) are cleared, and one execution of the brake fluid pressure determination routine is completed.

On the other hand, if the control flag Fe is ON,
At 533, it is determined whether or not the control flag F1 is ON, and if the determination result is YES, 334-3
At step 8, the brake fluid pressure P, which is related to the steering angle θ, is determined. That is, in S34, the difference D1 between the reference steering angle θ5 and the steering angle θ in the current steering angle memory 134, that is, the amount of increase in the steering angle θ from the time when it is determined that the turning abnormality tendency has occurred for the first time is calculated. , 335, it is determined whether the difference D+ is positive. If the determination result in S35 is YES, the brake fluid pressure P is calculated as the product of the difference and the predetermined control gain G in S36, and is stored in the brake fluid pressure memory 154. . The larger the amount of increase in the steering angle θ after it is determined that an abnormal turning tendency has occurred for the first time, the higher the brake fluid pressure P is determined to be.

On the other hand, if the determination result in S35 is No, it is assumed that there is no need for turning control, and the control flag F1 is turned off in 337, and the brake fluid pressure memory 154 (P,) is cleared in 338, and the steering angle θ The determination of the brake fluid pressure P based on the amount of increase in is completed.

Subsequently, in steps 339-44, the brake fluid pressure P2 is determined based on the amount of increase in the vehicle speed V.

The brake fluid pressure P2 is calculated as the product of the difference D2 between the reference vehicle speed (2) and the vehicle speed (2) at that time and the control gain G2, and is stored in the brake fluid pressure memory 155. The brake fluid pressure P2 is determined to be a higher value as the increase in the vehicle speed ■ after it is determined that an abnormal turning tendency has occurred for the first time, but the execution of these steps is the same as in steps 333 to 38 above. Therefore, detailed explanation will be omitted.

Note that if both control flags F, , F2 are turned OFF, S39. After the determination in S45, the control flag FC is turned OFF in S32, and the turning control based on the action of the brake is ended.

After the brake fluid pressures Pr and Pt are determined at 336, 338, 342, 344, etc. as described above, the brake fluid pressure P1. The final brake fluid pressure PB is calculated as the sum of P2 and is stored in brake'fluid pressure memory 1.
56, and the brake fluid pressure Pl is stored in 347.
The braking force TB is calculated as the product of the constant and the constant 8, and is stored in the braking force memory 158. Then, in step 348, the absolute value of the braking force T is subtracted from the absolute value of the transmissible longitudinal force TF of the tire, and in step S49, the difference between the two is calculated.

It is determined whether or not is positive. If it is positive, the brake fluid pressure P calculated in S46 is maintained as it is, but if not, in S50, the brake fluid pressure Ps is set to the brake fluid pressure upper limit stored in the brake fluid pressure upper limit value memory 152. It is replaced by the value Pu. That is, if the brake fluid pressure P and braking force T8 calculated in 346 exceed the transmittable longitudinal force T of the tire calculated in 326, the brake fluid pressure P
, is replaced with the upper limit value PU, and the left and right rear wheels are 28.32.
This prevents excessive slip from occurring.

After the brake fluid pressure is determined in S3 as described above, a left/right brake switching determination is performed in S4.

When the amount of lateral slip between the front wheels 18.22 and the rear wheels 28.32 is almost the same, the ratio LA/Y)I between the lateral acceleration La and the yaw rate YR is approximately constant as shown by the broken line in FIG. However, if the side slip of the front wheels 18.22 is larger, the yaw rate YR becomes smaller relative to the lateral acceleration LA, and the ratio LA/YR becomes larger. Also, the rear wheel 28
．． If the sideslip of 32 is larger, the yaw rates Y and I will be larger than the lateral acceleration LA, and the ratio LA / Y
* becomes smaller. However, even if the ratio LA/YR is close to the value indicated by the broken line, it does not necessarily mean that the wheels will not skid, and if the product of the vehicle speed ■ and the steering angle θ is large, the front wheels will be 18.22. Approximately equal sideslip occurs with the rear wheels 28.32, and the vehicle tends to understeer. In this embodiment, the brake of the wheel on the inside of the turn is applied to generate a yawing moment toward the inside of the turn, thereby reducing the tendency of the vehicle to understeer, and reducing or preventing an increase in the vehicle speed (hereinafter referred to as However, since the load on the wheel on the inner side of the turn becomes smaller due to lateral load movement, the braking effect tends to be insufficient. Therefore, in this embodiment, if a sufficient turning control effect cannot be obtained by braking the inside wheel, the outside wheel is braked, and if that is still insufficient, both the inside and outside wheels are braked. It is supposed to be added.

That is, as shown in FIG. 23, +, kz on the boundary line.

Divide the area into 5 parts by k3 and 4, and set the boundary 1ik
, brake the inside wheel between 1 and 2, and between 1 and 4 on the border! , k1, the outer wheels are braked, and in the area below the boundary line and above the boundary line 4, the left and right front and rear wheels 28.32 are braked.

The left/right brake switching determination is a routine for determining which region the ratio LA/Y* is in and setting the control switching flag XC and the two-wheel control flag XDC based on the determination result, as shown in FIG. This is done by executing each step.

First, in step 351, the yaw rate YR is read from the yaw rate sensor 94 and stored in the yaw rate memory 160, and in step S52, the lateral acceleration LA currently stored in the lateral acceleration memory 138 is divided by the yaw rate Y, and compared, / YR is calculated. And S53
In S56 to S56, it is determined in which region the point determined by the current vehicle speed ■ and the ratio LA/YR is located based on the switching determination table 118 in which the relationship shown in FIG. 23 is tabulated, and the determination result is Based on this, the control switching flag XC and the two-wheel control flag XDC are set in S57 to S359.

The switching control flag XC indicates that the wheels to be braked should be switched from the inner wheels to the outer wheels in the ON state, and the dual wheel control flag XDC indicates that the wheels to be braked should be switched from the inner wheels to the outer wheels in the ON state.
32 should be braked.

After the left and right brake switching is determined and the control flags XC and XDC are set in S4, brake fluid pressure control is performed in S5.

This brake fluid pressure control is performed by executing each step shown in FIG. First, in S61, it is determined whether or not the brake pedal 10 is depressed based on a signal from the brake switch 82. If the brake pedal 10 is depressed, the S
At 62, the control flags F, , F, are set to FF, and S
At 63, the cylinder force cut valve 38 is opened, while the accumulator cut valve 62 is closed and the pump 6 is closed.
4 is stopped. Then, the brake fluid pressure Pg is set to O in S64. When the brake pedal 10 is depressed, the turning control device does not perform turning control.

On the other hand, if the brake pedal 10 is not depressed, it is determined in S65 whether any of the control flags F, F2 is in the ON state, and both are in the ON state.
363 if not in N state. S64 is executed, and the turning control device is placed in a state in which it does not control brake fluid pressure.

If either of the control flags F, F2 is in the ON state, the cylinder cut valve 38 is closed in S66, the accumulator cut valve 62 is opened, and the pump 64 is operated, allowing brake fluid pressure control. It becomes a state.

Subsequently, in 566a, the hydraulic pressure control valve drive current is calculated;
That is, the exciting current I of the solenoid 54 of the hydraulic pressure control valve 40, 41 is set. As described above, the hydraulic pressure control valves 40 and 41 have a characteristic that the larger the excitation current I of the solenoid 54, the lower the output hydraulic pressure. There is a relationship shown in Figure 24.

Excitation current table 1 is a table of this relationship.
20, and the excitation current I is determined from the brake fluid pressure Pg set in S46 using the excitation current table 1.20. And in 566b,
It is determined whether the two-wheel control flag XDC is in the ON state, and if it is in the ON state, the drive current (excitation current I) set in 566a is output to the left and right hydraulic control valves 40, 41 in S67. , the left and right brakes 30, 34 are applied together to suppress the vehicle body speed (2), so that the vehicle can turn properly.

On the other hand, if the two-wheel control flag If the result is No, S69
It is determined whether the control switching flag xC is in the ON state.

If the result of the determination is No, the drive current of the magnitude set in 566a is output to the left hydraulic pressure control valve 40 in S71, and the hydraulic pressure of the brake 34 is output to the right hydraulic pressure control valve 41 in S71. Even if the pressure is O, a drive current of a magnitude sufficient to maintain the hydraulic pressure control valve 41 in a reduced pressure state is output. As a result, the left rear wheel 28, which is the inside wheel, is appropriately braked.
The right rear wheel 32, which is the outer wheel, is not braked, and a yawing moment that causes the vehicle body to yaw toward the inside of the turn is generated, and the vehicle speed (2) is suppressed, allowing the vehicle to turn smoothly.

On the other hand, if the control switching flag XC is in the ON state,
369 is YES, S73 and S74 are executed, and only the right rear wheel 32, which is the wheel on the outside of the turn, is braked, and only the left rear wheel 28, which is the wheel on the inside of the turn, is braked. The vehicle speed ■ is suppressed more strongly than in the above case.

Also, if the driver is turning right, the determination result of 368 is YE.
S, then S72, then S73 and S74, or 3
70 and 371 are executed.

As is clear from the above explanation, in this example,
The lateral acceleration sensor 95 constitutes the lateral momentum detection means 1 that detects lateral acceleration as the lateral momentum of the vehicle, the steering angle sensor 80 constitutes the steering angle detection means 3, and the rotation sensor 8
4, 86, 88, and 90, and a portion of the main control device 96 that executes 311 constitute the vehicle speed detection means 2.

In addition, a portion of the main controller 96 that executes 314 to 20 serves as the turning abnormality determining means 4, and the reference value ΔLAI and Δ
L^2 serves as a reference value for the rate of increase in lateral momentum with respect to increases in vehicle speed and steering angle, respectively.

In this embodiment, the rate of increase in lateral acceleration with respect to an increase in steering angle θ is calculated by ΔLA/Δ■ or base 1! When the value ΔLA or less, or when the rate of increase ΔL,/Δ■ of lateral acceleration LA with respect to the increase in vehicle speed V becomes less than the reference value ΔLA2, it is determined that a turning abnormality has occurred in the vehicle, and the left and right rear One or both of the wheels 28 and 32 are actuated to generate a yawing moment of a magnitude commensurate with the amount of increase in the steering angle θ or the vehicle speed V after the time when it is determined that an abnormal turning tendency has occurred for the first time, The vehicle speed (■) is suppressed so that the vehicle can turn appropriately.

In this way, when determining the occurrence of an abnormal turning tendency based on the fact that the rate of increase in lateral acceleration LA with respect to an increase in steering angle θ or vehicle speed V is below the reference value, it is possible to determine whether the turning abnormality tendency has occurred, regardless of the magnitude of the friction coefficient μ of the road surface. It is possible to determine whether or not there is a turning abnormality.

In addition, in this embodiment, the brake fluid pressure is adjusted based on the magnitude of the reference steering angle θ3 or the reference vehicle speed ■, which is the steering angle θ or the vehicle speed ■ when the occurrence of abnormal turning tendency is determined for the first time. Control gain G or G
2 can be changed, so when the friction coefficient μ of the road surface is low, the brake fluid pressure will be relatively low, and when the road surface friction coefficient μ is high, the brake fluid pressure will also be high. A braking force suitable for the level of the friction coefficient μ can be generated. Therefore, there is an advantage that appropriate turning control is always performed regardless of the level of the friction coefficient μ of the road surface, but even when the brake fluid pressure control gain is set to a constant value, a considerable turning control effect can be obtained.

Further, in this embodiment, the ratio LA/YFI between the lateral acceleration LA and the yaw rate YR is on the boundary line, k.

Either the left or right rear wheel is selectively braked depending on which side of k3 and 4, or both are braked, so if the friction coefficient μ of the road surface is low or the wheels skid. This has the advantage that turning control can be performed well even under unusual circumstances, such as when a sudden occurrence of a crash occurs, but it is not necessarily necessary to change the wheels to be braked depending on which region the ratio LA/YR belongs to. For example, even if the wheel on the inside of the turn is always braked, turning control can be performed fairly well.

[Brief explanation of the drawing]

FIG. 1 is a diagram conceptually showing the configuration of the present invention. FIG. 2 is a system diagram showing a swing control device including a swing abnormality determination device according to an embodiment of the present invention, and FIG. 3 is a front sectional view showing details of the hydraulic control valve in FIG. 2. Fourth
The figure is a diagram conceptually showing the configuration of the ROM in the above device. 5 to 9 are flowcharts showing control programs stored in the ROM. 10th
The figure is a diagram conceptually showing the configuration of the RAM of the above device. 11 to 24 are graphs for explaining the operation of the above device. 80: Steering angle sensor 84. 86, 88, 90: Rotation sensor 94: Yaw rate sensor 95: Lateral acceleration sensor 96: Main control device Fig. 8 Fig. 10 Fig. 11 wIi World ■ θ @13rI!J 141j!J ■ ■ [Fig. 15 Fig. 16 θ 5 5 ■ No. 23!!! Il!'' Fig. 17 Fig. 18 2011 θ Voice Figure 21 Figure 22 A A Figure 24

Claims (1)

[Scope of Claims] At least one of: lateral momentum detection means for detecting lateral momentum such as lateral acceleration and yaw rate of a vehicle; vehicle speed detection means for detecting vehicle speed; and steering angle detection means for detecting a steering angle of a steering device. and a turning abnormality determination that determines that a turning abnormality has occurred or has a tendency to occur in the vehicle when an increase rate of the lateral momentum with respect to an increase in at least one of the vehicle body speed and the steering angle becomes less than a reference value. A turning abnormality determination device for a vehicle, comprising: means.