JP2653214B2 - Vehicle turning abnormality determination device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormal turning state that does not correspond to the operation of a steering device due to excessive side slip of a wheel during turning of a vehicle, or a tendency to the tendency. The present invention relates to a turning abnormality determination device for determining the rotation angle.

2. Description of the Related Art Japanese Unexamined Patent Application Publication No. 63-203456 discloses a turning control device for preventing an abnormal turning of a vehicle by applying a brake. In order to prevent a turning abnormality in this way, a turning abnormality determination device that determines whether a turning abnormality has occurred, or whether a possibility or tendency of occurrence has occurred is required. The turning control device described in the above publication is provided with a turning abnormality determination device that determines whether or not a turning abnormality may occur in the vehicle based on the vehicle speed and the 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 turning abnormality is likely to occur. When the angle and the vehicle speed are taken, a boundary line can be drawn between a region where a turning abnormality may occur and a region where no turning abnormality occurs, and a point representing the actual vehicle speed and the steering angle is defined by the boundary line. There is provided a device that determines whether or not there is a possibility that a turning abnormality may occur depending on which side the region belongs to.

Since the position of the boundary line changes depending on the friction coefficient of the road surface, the driver operates the switch in accordance with the state of the road surface to select a boundary line corresponding to the friction coefficient of each road surface. It is determined whether or not there is a possibility that a turning abnormality may occur based on the boundary line.

Problems to be Solved by the Invention Changing the determination criterion according to the friction coefficient of the road surface as described above is troublesome, and when the determination is performed based on the driver's switch operation, the operation may be forgotten or mistakenly operated. The determination may be made based on an inappropriate determination criterion. If the turning control is performed based on the result of the erroneous determination, the purpose cannot be sufficiently achieved.

The present invention is directed to a turning abnormality determination that can determine whether a turning abnormality tends to occur, or whether a turning abnormality has occurred, based on a constant determination criterion, regardless of the friction coefficient of the road surface. It was made to obtain a device.

Means for Solving the Problems The gist of the present invention is that a turning abnormality determination device detects a turning motion state quantity representing a turning motion state of a vehicle such as a lateral acceleration and a yaw rate of the vehicle as shown in FIG. Turning motion state quantity detecting means 1, vehicle body speed detecting means 2 for detecting a vehicle speed, steering angle detecting means 3 for detecting a steering angle of a steering device, and a vehicle in which the vehicle is accelerated with a constant steering angle. A turning abnormality determining means for determining that a turning abnormality has occurred or has a tendency to occur in the vehicle when the rate of increase of the turning motion state quantity with respect to the increase in the vehicle body speed is lower than a reference value during turning; And that

In one embodiment of the present invention, the turning motion state amount detecting means is:
This is an aspect including a lateral acceleration sensor that detects a lateral acceleration of a vehicle body as a turning motion state quantity.

When increasing the vehicle speed while keeping the steering angle constant, while the vehicle speed is low, the amount of turning motion increases almost in proportion to the vehicle speed, but if the vehicle speed increases and the wheelslip increases, The rate of increase of the turning motion state quantity with respect to the increase of the vehicle body speed gradually decreases. This tendency does not change when the coefficient of friction of the road surface is high or low. Then, when the turning tendency of the vehicle tends to occur, or when the turning abnormality actually occurs, the rate of increase of the turning motion state quantity is almost constant, so that each value should be set as a reference value. Whether the turning abnormality has occurred or whether the turning abnormality has actually occurred can be determined based on whether or not the increase rate of the turning motion state quantity is equal to or less than the reference value.

As described above, according to the present invention, it is possible to determine the turning abnormality by determining whether or not the rate of increase of the turning motion state quantity with respect to the increase in the vehicle body speed is equal to or less than a reference value. Can be set to a constant value regardless of the level of the friction coefficient, so that it is not necessary to change the reference value according to the level of the friction coefficient of the road surface, and it becomes easy to determine a turning abnormality. Further, it is not necessary to input information regarding the friction coefficient of the road surface by a driver's switch operation or the like, and it is possible to avoid a situation in which an incorrect turning abnormality is determined due to forgetting to operate or an operation error.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 2, the brake pedal 10 is connected to a master cylinder 14 via a booster 12. The master cylinder 14 is a tandem type having two pressurizing chambers, and the hydraulic pressure generated in one of the pressurizing chambers is transmitted to the brake 20 of the left front wheel 18 and the brake 24 of the right front wheel 22 by the main liquid passage 16. The hydraulic pressure generated in the other pressurizing chamber is transmitted to the brake 30 of the left rear wheel 28 and the brake 34 of the right rear wheel 32 through the main liquid passage 26. A proportioning / bypass valve 36 is provided in the middle of the main fluid passages 16 and 26. When the fluid pressure in the main fluid passage 16 rises normally, the fluid pressure in the main fluid passage 26 is reduced, and 16
When the fluid pressure of the main fluid passage 26 does not rise normally, the fluid pressure of the main fluid passage 26 is not reduced.

Proportioning / bypass valve 36 for main fluid passage 26
A cylinder cut valve 38, which is an electromagnetic on-off valve for cutting the master cylinder, is provided at a further downstream side, and hydraulic pressure control valves 40, 41 are provided at the forked portions of the main liquid passage 26, respectively. The hydraulic pressure control valves 40, 41 are connected to the reservoir 43 by a return passage. The hydraulic pressure control valves 40 and 41 have the same structure, and the hydraulic pressure control valve 40 is typically shown in FIG. A spool 46 is fitted in a valve hole 45 of the housing 44 so as to be substantially liquid-tight and slidable.The spool 46 is always kept at a position shown in the drawing by a spring 47, and is connected to an output pressure port 48 connected to the brake 30. While communicating with a high pressure port 49 connected to the cylinder cut valve 38, it is shut off from a low pressure port 50 connected to the reservoir 43. A control piston 52 is opposed to one end of the spool 46 via a ball 51,
The spring 53 urges the spool 46. The elastic force of the spring 53 is significantly smaller than the elastic force of the spring 47 and can be ignored. The opposite sides of the control piston 52 and the spool 46 are as hydraulic pressure in the output pressure port 48 to the end surface opposite to act, the pressure receiving area S ₁ of the control piston 52 is pressure-receiving area S of the spool 46 _It is larger than ₂ . Excitation current I to solenoid 54
Is supplied, a control force acts between the core 55 and the spool 46 to bring them closer to each other. The magnitude of this control force is represented by C · I (C is a constant), the elastic force of the spring 47 is F, and the hydraulic pressure of the output pressure port 48 (the hydraulic pressure of the brake 30) is P _B
Spool 46 and ball 51 that always move together
And the balance of the forces in the control piston 52 is such that F = C ＝ I + (S ₁ -S ₂ ) ・ P _B holds, and if this is solved for P, P _B = −C ・ I / (S _{1 -S 2) + F / (} S 1 -S 2) next, by controlling the excitation current I of the solenoid 50, and thus capable of controlling the brake fluid pressure P _B of the output pressure port 48. As the exciting current I is increased, the fluid pressure P _B of the output pressure port 48 is the lower. Note that check valves 58 and 59 are provided in bypass passages 56 and 57 that bypass the hydraulic pressure control valves 40 and 41.

Cylinder cut valve 38 and hydraulic pressure control valves 40 and 41 of main fluid passage 26
An accumulator 60 is connected to the portion between the two through an accumulator cut valve 62. The brake fluid pumped up from the reservoir 43 by the pump 64 is stored in the accumulator 60 at a high pressure, and when the accumulator cut valve 62 is opened, the brake fluid 30 is passed through the hydraulic pressure control valves 40, 41 and the brakes 30,
Supplied to 34. 66 is a relief valve.

The cylinder cut valve 38, the fluid pressure control valves 40 and 41, the return passage 42, the check valves 58 and 59, the accumulator 60, the accumulator cut valve 62, the pump 64, the relief valve 66, and the like are actuators 68 for performing anti-skid control. The turning control device according to the present embodiment uses the actuator 68 to actuate the brakes 30 and 34 to perform turning control.

The front wheels 18, 22 are steering wheels, and the steering wheels 70,
The direction can be changed by a steering device 76 including a steering gear 72, a steering link 74, and the like.

The steering angle θ of the steering wheel 70 is
, The depression of the brake pedal 10 is detected by a brake switch 82, and the rotation speed of each wheel 18, 22, 28, 32 is detected by a rotation sensor 84, 86, 88, 90, respectively. Direction acceleration (hereinafter abbreviated as lateral acceleration) and a yaw rate sensor fixed to the vehicle body 92
These output signals are detected by the 94 and the lateral acceleration sensor 95 and supplied to the main controller 96.

Main controller 96 is mainly composed of a computer, and has input interface 100, output interface 102, CP
U104, ROM106 and RAM108 are provided. In ROM106,
The various tables shown in FIG. 4 correspond to FIGS. 5, 6, and 7.
It is provided together with a program memory in which a control program represented by the flowcharts of FIGS. 8, 8 and 9 is stored. On the other hand, as shown in FIG.
This variety of memory or control flag F ₁ or the like including the vehicle speed memory 130 is provided with a working memory. The input interface 100 includes the steering angle sensor 80 described above,
A brake switch 82, rotation sensors 84, 86, 88, 90, a yaw rate sensor 94, a lateral acceleration sensor 95, and the like are connected, and the output interface 102 is connected to the cylinder cut valve 38, the hydraulic pressure control valves 40, 41, and the accumulators. A motor 182 for driving the pump 64 is connected together with the cut valve 62.

Hereinafter, the operation of the present turning control device will be described with reference to the flowcharts of FIGS.

The main routine for turning control is as shown in FIG.
Initial setting step S1, turning state determination step S2, brake fluid pressure determination step S3, left / right brake switching determination step S4
And brake fluid pressure control step S5. The initial setting step S1 is executed at the same time when the power of the main controller 96 is turned on, and thereafter, steps S2 to S5 are repeatedly executed at regular intervals.

In the initial setting step S1, the control flag F ₁ with each memory is cleared, F _2, F _C, the control switching flag XC and wheels control flag XDC is turned OFF.

In turning state decision step S2, based on the change rate of the lateral acceleration L _A with respect to a change in vehicle speed V and the steering angle theta, determines whether a tendency of turning abnormality has occurred (hereinafter, the mere determination of the turning abnormal If it occurs, the control flags F ₁ , F ₂ , and F _C are turned ON, and various amounts required for the turning control are determined. When the steering angle θ is constant, the lateral acceleration
L _A, as shown in FIG. 11, but while the vehicle speed V is low is to increase substantially in proportion to the vehicle speed V, if the lateral slip of tire excessive and the vehicle speed V increases, the lateral acceleration L _a is increasing rate is small, and enters the critical region shown by hatching. _A similar relationship exists between the steering angle θ and the lateral acceleration LA when the vehicle speed V is constant, as shown in FIG. When the vehicle speed V is plotted on the horizontal axis and the steering angle θ is plotted on the vertical axis, generally, the hatched area in FIG. 13 is the limit area, and in this area, abnormal turning tendency occurs. In the invention of Japanese Patent Application Laid-Open No. 63-203456, attention is paid to this fact, and the presence or absence of a possibility of turning abnormality is determined from the relationship between the vehicle speed V and the steering angle θ. Varies depending on the magnitude of the friction coefficient μ of the road surface. Therefore, in the above invention, the driver inputs the information of the road surface μ by operating the switch, the boundary line of the limit area is selected accordingly, and the turning control is performed based on the selected boundary line. I have. However, since in this case there is a risk that the driver and the switch operation error occurs, in the present embodiment, the rate of increase in the lateral acceleration L _A to increasing vehicle speed V and the steering angle θ is, Figure 14, respectively and as shown in Figure 15, it focuses on the fact that decreases with increasing vehicle speed V and the steering angle theta, the lateral acceleration L increases rate of _a [Delta] L _a / [Delta] V and [Delta] L _a / [Delta] [theta], respectively reference value [Delta] L _A1, A turning abnormality is determined based on whether or not the difference is smaller than ΔL _A2 .

That is, the turning state determination step S2 includes the steps shown in FIG.
Simply represented by S11. In the other steps, the vehicle speed stored in the vehicle speed memory 130 is transferred to the previous vehicle speed memory 132, and the new vehicle speed V is output from the rotation sensors 84, 86, 88 and 90. And is stored in the vehicle speed memory 130 at this time. Subsequently, in S12, 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. Is done. Similarly, S
With the lateral acceleration L _A of the lateral acceleration memory 138 this time is transferred to the last lateral acceleration memory 140 at 13, loaded a new lateral acceleration L _A from the lateral acceleration sensor 95, it is stored in this lateral acceleration memory 138.

Next, in S14, the vehicle speed V, the steering angle θ and the lateral acceleration L _A, the difference [Delta] V, [Delta] [theta] between the value and the value of the current memory of the last memory, [Delta] L _A are calculated, respectively difference [Delta] [theta] in S15, S18, It is determined whether ΔV is greater than the fixed values Δθ _s and ΔV _s , and the determinations in S16 and S19 are performed only when the determination result is YES. This is because when the differences ΔV and Δθ are too small, S1
If the determination in S6 and S19 is performed, there is a possibility that an erroneous determination may occur due to the influence of a detection error such as the steering angle θ or the like. Therefore, while the steering angle θ is increasing, the determination in S15 is YES, the determination in S16 is performed, the steering angle θ is kept substantially constant, and the determination in S15 is NO while the vehicle body speed V is increasing. If the determination in S18 is YES, the determination in S19 is performed, and neither the determination in S16 nor S19 is performed unless both the steering angle θ and the vehicle speed V are increasing. S16, if S19 in the determination is both NO, on which the control flag F _1, F ₂ in each of S17 and S20 is is the OFF, whether or not the control flag F _C is in the ON state in S21 However, since the result of this determination is normally NO, one turn state determination is completed.

In contrast, when the tendency of turning abnormality is determined to have occurred in either S16 or S19 is whether or not the control flag F _C is ON in S22 are determined. This is S1
This is a step provided to execute S23 and S24 only when it is first determined that a tendency of turning abnormality has occurred in 6 and the like. In S23, the control flag F _1, is F ₂ and F _C is the ON, the reference steering angle as a steering angle theta and the vehicle speed V and the reference steering angle theta _s and the reference vehicle speed V _s, respectively at that time in S24 memory The control gains G ₁ and G ₂ of the brake fluid pressure are determined in S 25 while being stored in the reference body speed memory 142 and the reference vehicle speed memory 144. Reference steering angle theta _S is a steering angle theta when the increase rate of the lateral acceleration L _A becomes equal to or less than the reference value [Delta] L _A2 started, as shown in FIG. 18,
A low μ road with a low friction coefficient μ has a smaller value than a high μ road. Then, when performing turning control by applying a brake on a low μ road, if the brake fluid pressure is increased similarly to the case of a high μ road, the turning control becomes too strong and the direction control of the vehicle becomes unstable. . Therefore, in S25, the steering angle relationship between the reference steering angle theta _S shown in FIG. 19 and the control gain G ₁ is being tabulated - gain table 110
Accordingly, as the reference steering angle theta _S is small control gain G ₁ is determined small. Determined control gain G ₁ is stored in the gain memory 146. In addition, as shown in FIG.
To become smaller than the reference vehicle speed V _S is high μ road in the road, the reference vehicle speed V _S and the control gain shown in FIG. 17
Vehicle speed relationship is tabulated and G ₂ - by gain table 112, the control as the reference vehicle speed V _S is smaller gain G
₂ is determined to be small. Determined control gain G ₂ is stored in the gain memory 148.

Subsequently, in S26, the transmittable longitudinal force T _F of the tire
There are determined, the upper limit value P _U of the brake fluid pressure is determined in S27. As shown in FIG. 20, large lateral acceleration L _A is obtained as the friction coefficient of the road surface μ is large, L _A that is large means that a large μ friction coefficient of the road surface. Therefore, as shown in FIGS. 21 and 22, the lateral acceleration L _A
Is larger, the front-rear force _TF that can be transmitted by the tire is larger, and even if the brake is applied with a higher fluid pressure, the wheel slip does not become excessive. Therefore, the relationships shown in FIGS. 21 and 22 are tabulated. and longitudinal force table 114, based on the hydraulic pressure upper limit value table 116, the lateral acceleration L _a is too large longitudinal force T _F and the brake fluid pressure upper limit value P _U is determined to a large value. Longitudinal force T _F and the brake fluid pressure upper limit value P _U determined are stored respectively in the transferable longitudinal force memory 150 and the brake fluid pressure upper limit value memory 152.

As described above, the determination of the turning state in S2, after the control flag F _1, F _2, F _C configuration and various quantities of decision has been made, the determination of the brake fluid pressure in S3 is performed. The determination of the brake fluid pressure is performed by executing the steps shown in FIG. First, it is determined whether or not the control flag F _C is in the ON state in S31, if the decision result is NO, together with the control flag F _C is turned OFF at S32, the brake fluid pressure memory 154 to 156 (P ₁ , P ₂ and P _B ) are cleared,
One execution of the brake fluid pressure determination routine ends.

In contrast, if the control flag F _C is turned ON, S3
Control flag F ₁ in 3 it is determined whether a ON, if the decision result is YES, the determination of the brake fluid pressure P ₁ in relation to the steering angle θ at S34~38 is performed. That is, S3
4 increase in the steering angle theta from the time when the difference D _1, i.e. the tendency of the first time turning abnormality is determined to have occurred between the steering angle theta of the reference steering angle theta _s and the current steering angle memory 134 is calculated in , whether the difference D ₁ is positive it is determined in S35. If S35 in the determination result is YES, the brake fluid pressure P ₁ is calculated as the product of the control gain G _1, which is predetermined as the difference D ₁ in S36, is stored in the brake fluid pressure memory 154 . The greater the amount of increase in the steering angle θ since it is first determined that the turning abnormality tendency has occurred, the greater the brake fluid pressure P ₁
Is determined to be a high value.

On the other hand, O control flag F ₁ in S37 as a determination result of S35 is no longer the need for the turning control in the case of NO
Is a FF, the brake fluid pressure P ₁ based on the increase of the steering angle θ brake fluid pressure memory 154 (P ₁₎ is cleared in S38
Is determined.

Subsequently, the determination of the brake fluid pressure P ₂ based on the increase in the vehicle speed V is performed in S39～44. The brake fluid pressure P ₂ is a difference D ₂ between the reference vehicle speed V _s and the vehicle speed V at that time.
It is calculated as the product of the control gain G ₂ and the stored in the brake fluid pressure memory 155. Although the first time of turning abnormality tendency is determined as the brake fluid pressure P ₂ is a high value is greater increase in vehicle speed V from being determined to have occurred, the same execution of these steps and the S33~38 Therefore, detailed description is omitted. Note that both control flags F ₁ and F ₂ are OFF
When it becomes the, S39, the control flag F _C in S32 through determination of S45 is the OFF, turning control by the action of the brake is terminated.

S36 as described above, S38, S42, after the brake fluid pressure P _1, P ₂ is determined in S44 or the like, the brake fluid pressure P ₁ in S46, P
The final brake fluid pressure P _B is stored is calculated in the brake fluid pressure memory 156 as the sum of _2, the braking force T _B is calculated braking as product of the brake fluid pressure P _B and the constant K _B in S47 It is stored in the power memory 158. Then, the absolute value of the braking force T _B in S48 is subtracted from the absolute value of the longitudinal force T _F transmittable of the tire, whether the difference D _T therebetween is positive is determined in S49. If it is positive, the brake fluid pressure P _B calculated in S46 is maintained as it is, but if it is not positive, the brake fluid pressure P _B is stored in the brake fluid upper limit memory 152 in S50. It is changed every other to the upper limit value P _U. That is, the braking force T _B by the calculated brake fluid pressure P _B in S46, if more than longitudinal force T _F transmittable tires calculated in the S26, the brake fluid pressure P _B is the upper limit value P _U , So that excessive slip does not occur in the left and right rear wheels 28, 32.

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

When the sideslip amounts of the front wheels 18, 22 and the rear wheels 28, 32 are almost the same, the ratio L _A / Y between the lateral acceleration L _A and the yaw rate Y _R
R is is become substantially constant value indicated by a broken line in FIG. 23, the yaw rate Y _R is reduced in proportion to the lateral acceleration L _A in the case toward the side slip of the front wheels 18 and 22 is large, the ratio L _A / Y _R increases. Also, when the side slip of the rear wheels 28, 32 is larger, the yaw rate Y _R becomes larger than the lateral acceleration L _A , and the ratio L _A
/ Y _R decreases. However, just because the ratio L _A / Y _R is close to the value indicated by the dashed line does not necessarily mean that there is no side slip of the wheels, and when the product of the vehicle speed V and the steering angle θ is large, the front wheels 18, A substantially equal sideslip occurs at 22 and the rear wheels 28, 32, and the vehicle tends to understeer. In the present embodiment, the inward turning yaw moment is generated by applying the brakes of the wheels inside the turning to reduce the understeer tendency of the vehicle, and reduce the vehicle speed V or prevent the vehicle speed V from increasing. The above-mentioned understeering tendency is canceled by simply suppressing the vehicle body speed. However, since the load on the wheel inside the turn is reduced by the lateral load movement, the braking effect tends to be insufficient.
Therefore, in the present embodiment, when a sufficient turning control effect cannot be obtained by braking the inner wheel, the outer wheel is braked, and if it is still insufficient, braking is performed on both the inner and outer wheels. To be added. That is,
As shown in Figure 23, divided into five regions by a boundary line k _1, k _2, k ₃ and k _4, brake the inside wheel in between the boundary k ₁ and k _2, the boundary line k ₁ , k ₄ between and k _2, in the region and between k ₃ and brake the outer wheels, the lower and border k ₄ boundary line k ₃
On the upper side, the left and right rear wheels 28, 32 are braked.

The left / right brake switching determination determines which area the ratio L _A / Y _R is in, and based on the determination result, the control switching flag XC
And a routine for setting the two-wheel control flag XDC, which is performed by executing the steps shown in FIG.

First, read the yaw rate sensor 94 from the yaw rate Y _R in S51, is stored in the yaw rate memory 160, the ratio by dividing the lateral acceleration L _A that is currently stored on the lateral acceleration memory 138 in S52 in the yaw rate Y _R L _A
/ Y _R is calculated. Then, in S53 to S56, the second
Based on the switching determination table 118 in which the relationship shown in FIG. 3 is tabulated, it is determined in which area the point determined by the vehicle speed V and the ratio L _A / Y _R is at that time, and S57 is determined based on the determination result. In S59, the control switching flag XC and the two-wheel control flag XDC are set. Control switching flag XC
Indicates that the wheels to be braked in the ON state should be switched from the inner wheels to the outer wheels, and the two-wheel control flag XDC is ON.
In this state, both left and right rear wheels 28 and 32 are to be braked.

In S4, the left and right brake switching judgment and flag X
After the settings of C and XDC are performed, brake fluid pressure control is performed in S5.

This brake fluid pressure control is performed by executing the steps 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, and if depressed, the control flags F ₁ and F ₂ are turned off in S62, and the cylinder cut is performed in S63. The valve 38 is opened, the accumulator cut valve 62 is closed, and the pump 64 is stopped. Then, set the brake fluid pressure P _B is 0 in S64.
When the brake pedal 10 is depressed, the turning control by the turning control device is not performed.

On the other hand, when the brake pedal 10 is not depressed, _one of the control flags F ₁ and F ₂ is set in S65.
It is determined whether or not the vehicle is in the ON state. If neither is in the ON state, S63 and S64 are executed, and the turning control device is brought into a state in which the brake fluid pressure is not controlled.

If either of the control flags F ₁ and F ₂ is in the ON state, the cylinder cut valve 38 is closed in S66, the accumulator cut valve 62 is opened, the pump 64 is operated, and the brake fluid pressure control is performed. It is possible.

Subsequently, in S66a, calculation of the hydraulic control valve drive current, that is, setting of the excitation current I of the solenoid 54 of the hydraulic control valves 40 and 41 is performed. As described above, the hydraulic pressure control valves 40 and 41 have the characteristic that the output hydraulic pressure decreases as the exciting current I of the solenoid 54 increases, and the exciting current I and the brake hydraulic pressure P serving as the output hydraulic pressure.
Has the relationship shown in FIG. This relationship is tabulated in the excitation current table 120.
Than is excitation current I is determined using the excitation current table 120 from the brake fluid pressure P _B set in. Then, in S66b, it is determined whether or not the two-wheel control flag XDC is in the ON state, and if it is in the ON state, the drive current (excitation current) set in S66a is supplied to the left and right hydraulic pressure control valves 40, 41 in S67. I) is output, the left and right brakes 30, 34 are applied together, the vehicle speed V is suppressed, and the vehicle is turned properly.

On the other hand, if the two-wheel control flag XDC is not in the ON state, it is determined in S68 whether or not the vehicle is turning right based on whether or not the steering angle θ stored in the current steering angle memory 134 is positive. If the result is NO, it is determined in S69 whether the control switching flag XC is in the ON state. If the result of the determination is NO, in S70 the left hydraulic control valve 40
, A driving current having the magnitude set in S66a is output. In S71, the hydraulic pressure control valve 41 is sufficient to keep the hydraulic pressure control valve 41 in the reduced pressure state even if the hydraulic pressure of the brake 34 is 0 in the right hydraulic pressure control valve 41. A driving current of a magnitude is output. As a result, the left rear wheel 28 as an inner wheel is moderately braked, and the right rear wheel as an outer wheel is
No. 32 is not braked, so that a yawing moment for yawing the vehicle body inward is generated, the vehicle speed V is suppressed, and the vehicle is turned well.

On the other hand, if the control switching flag XC is ON, S6
The determination result of 9 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, the wheel on the inside of the turn, is braked. The vehicle speed V is more strongly suppressed than in the above case.

If the vehicle is turning right, the determination result in S68 is YES, and S73 and S74 or S70 and S71 are executed via S72.

As is clear from the above description, in the present embodiment, the lateral acceleration sensor 95 constitutes the turning motion state amount detecting means 1 for detecting the lateral acceleration as the turning motion state amount of the vehicle, and the rotation sensors 84, 86, 88 and 90 and S11 of main controller 96
And the steering angle sensor 80 constitutes the steering angle detecting means 3. Also,
The part of the main controller 96 that executes S14, S15, and S18 to S20 constitutes the turning abnormality determination means 4, and the reference value ΔL _A1 is a reference value of the rate of increase of the turning motion state quantity with respect to the increase of the vehicle body speed. .

In the present embodiment, when the increase rate [Delta] L _A / [Delta] V of the lateral acceleration L _A for increasing the vehicle speed V is smaller than the reference value [Delta] L _A1, it is determined that the turning abnormality occurs in the vehicle, the left and right rear wheels One or both of 28 and 32 are actuated, and a yawing moment having a magnitude commensurate with the increase in the vehicle speed V after the time when it is determined that the turning abnormal tendency has occurred for the first time is generated, and the vehicle speed V is suppressed. This allows the vehicle to turn properly. Thus, the vehicle speed V
When the increase rate of the lateral acceleration L _A of relative increase to determine the occurrence of the turning abnormal tendency with a be smaller than the reference value, performing the determination of the presence or absence of independently turning abnormality of the magnitude of the friction coefficient of the road surface μ Can be.

In the present embodiment, the steering angle θ or the vehicle speed V at the time when the occurrence of the turning abnormality tendency is determined for the first time is determined.
In it, based on the magnitude of the reference steering angle theta _S or the reference vehicle speed V _S, since adapted control gain G ₁ or G ₂ of the brake fluid pressure is changed, if the friction coefficient of the road surface μ is low The brake fluid pressure becomes relatively low, and when the road surface friction coefficient μ is high, the brake fluid pressure also becomes high, so that a braking force suitable for the road surface friction coefficient μ can be generated. Therefore, there is an advantage that proper turning control is always performed irrespective of the level of the friction coefficient μ of the road surface. However, even when the control gain of the brake fluid pressure is set to a constant value, a considerable turning control effect can be obtained.

In the present embodiment, the lateral acceleration L _A and yaw rate
Y ratio L _A / Y _R boundary k ₁ is, k _2, the rear wheel of the right or left depending on whether k ₃ and located on either side of the k ₄ with _R are selectively braking, or both is braked So that
If the friction coefficient μ is low and the road surface, or when the lateral slip of the wheels is abruptly generated, although there is an advantage that good turning control is carried out even under unusual circumstances, the ratio L _A / Y _R what regions It is not always necessary to change the wheel to be braked depending on whether the wheel belongs to the vehicle. For example, even if the wheel on the inside of the turn is always braked, it is possible to perform the turn control fairly well.

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing the configuration of the present invention. FIG. 2 is a system diagram showing a turning control device including a turning abnormality determination device according to one embodiment of the present invention, and FIG. 3 is a front sectional view showing details of a hydraulic control valve in FIG. FIG. 4 is a diagram conceptually showing the configuration of a ROM in the above-mentioned device. 5 to 9 are flowcharts showing a control program stored in the ROM. FIG. 10 is a diagram conceptually showing the configuration of the RAM of the above device. Fig. 11 or 2
FIG. 4 is a graph 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 controller

Claims (2)

(57) [Claims] 1. A turning motion state quantity detecting means for detecting a turning motion state quantity representing a turning motion state of a vehicle, a vehicle speed detecting means for detecting a vehicle speed, and a steering angle detecting for detecting a steering angle of a steering device. Means, at the time of vehicle turning in which the vehicle is accelerated in a state where the steering angle is constant, a turning abnormality occurs in the vehicle when an increasing rate of the turning motion state amount with respect to an increase in the vehicle body speed is equal to or less than a reference value, Or a turning abnormality determining device that determines that a tendency to occur has occurred. 2. The vehicle turning abnormality judging device according to claim 1, wherein the turning motion state amount detecting means includes a lateral acceleration sensor for detecting a lateral acceleration of the vehicle body as the turning motion state amount.