JPH04257754A - Antiskid control device - Google Patents

Abstract

PURPOSE:To give priority to ensurance of deceleration during straight running or braking approximately similar to straight running as deceleration, stability, and steering ability are held in an excellent state and to give priority to ensurance of stability during other cornering brake than the above. CONSTITUTION:A yaw rate detecting signal OMEGA is read, the value thereof is compared with first and second reference values OMEGA1 and OMEGA2 set on the low yaw rate side and the high yaw rate side, and a slip ratio reference value S0 responding to a comparing result is set. When a yaw rate ¦OMEGA¦ exceeds the second reference value OMEGA2, it is decided that a car is in a given cornering state, and the reference value S0 is set to a lower value S8. When it is below the first reference value OMEGA1, it is decided that the car is in a straight running state or in a state approximately similar to a running state, and the reference value S0 is increased to a given value S15 entering a maximum friction factor area. When it is between the first and second reference values OMEGA1 and OMEGA2, the reference value S0 is set to a value inversely proportional to the magnitude of ¦OMEGA¦. Based on the slip ratio reference value S0, antiskid control is executed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device for preventing wheel locking and locking tendency, and more particularly to a device that performs control taking into account the yaw rate when a vehicle turns.

0002

2. Description of the Related Art Conventionally, as an anti-skid control device for a vehicle, the one described in Japanese Patent Laid-Open No. 63-170156, for example, is known. This anti-skid control device is equipped with multiple acceleration sensors that detect acceleration in the longitudinal direction of the vehicle, selects the output signal of these acceleration sensors that indicates the largest vehicle body deceleration, and integrates this selected value. A pseudo vehicle speed is determined, and when the wheel speed has a predetermined slip relationship with respect to the pseudo vehicle speed, the brake fluid pressure is decreased. Here, the predetermined slip relationship is, for example, a state in which the slip rate determined from the pseudo vehicle speed and the wheel speed is smaller than a preset slip rate reference value.

0003

[Problems to be Solved by the Invention] However, in the conventional device described above, the slip rate reference value related to the predetermined slip relationship is unchanged regardless of whether the vehicle is traveling straight or turning. The value must be set at a slip ratio that is shallower (smaller) than the maximum grip force range so that appropriate deceleration, stability, and steerability can be ensured even during turning, which is the most severe driving condition. Must be. This generates sufficient cornering force even when turning the steering wheel, allowing the vehicle to come to a stable stop, but it inevitably sacrifices some deceleration performance when driving straight. As a result, braking distance becomes longer during normal driving on city roads, etc., and in car racing, for example, cornering force is high in the low yaw rate range, making it difficult to actively change the vehicle's attitude using the brakes. I was in a situation where my gender was extremely low. Therefore, it has conventionally been desired to obtain the most suitable deceleration, stability, and steering performance depending on whether the vehicle is traveling straight, a driving state similar to straight travel, or a turning state.

The present invention has been made in consideration of the situation of anti-skid control, and it is possible to maintain good deceleration, stability, and steering performance while driving in a straight-line, near-straight, or other state. The objective is to demonstrate the most accurate braking performance that takes advantage of the characteristics of each driving state, depending on the turning state of the vehicle.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the invention as set forth in claim 1, as shown in FIG. Slip condition determining means for comparing and determining the detected value of the physical quantity detecting means and a changeable slip physical quantity reference value, and braking for controlling the braking pressure of the wheel based on the rotational condition of the wheel including the determination result of the slip condition determining means. pressure control means, a yaw physical quantity detection means for detecting a yaw physical quantity related to the yaw motion of the vehicle; and a slip physical quantity for setting the slip physical quantity reference value according to a detected value of the yaw physical quantity detection means. An adjustment means is provided.

[0006] The invention according to claim 2 also includes, as shown in FIG. 1(b), slip physical quantity detection means for detecting a slip physical quantity related to wheel slip; An anti-skid control device comprising a slip condition determining means for comparing and determining a physical quantity reference value, and a braking pressure control means for controlling a wheel braking pressure based on a wheel rotation condition including a judgment result of the slip condition determining means. , a yaw physical quantity detecting means for detecting a yaw physical quantity related to the yaw motion of the vehicle, a driving state determining means for comparing and determining a detected value of the yaw physical quantity detecting means and a preset yaw physical quantity reference value, and this driving state determining means. If the running condition determines that the yaw motion is greater than or equal to the yaw physical quantity reference value, the slip physical quantity reference value is set to a predetermined value; A slip physical quantity adjusting means is provided for setting the slip physical quantity reference value to a predetermined value larger than the predetermined value when the state is determined.

[0007]

According to the first aspect of the invention, as the detected value of the yaw physical quantity detection means decreases, the slip physical quantity adjustment means gradually increases, for example, the slip physical quantity reference value from a predetermined value. Therefore, as the driving state becomes straight or near straight, the brake pressure control means performs braking pressure control based on the increased reference value, so the physical slip quantity (slip ratio, slip amount), a large grip force is obtained, and the deceleration is maximum when the vehicle is traveling straight or almost straight. At this time, although the cornering force decreases, the yaw momentum in such a driving state is small and is a value that is attributable to road surface disturbances, so the stability does not decrease.

On the other hand, when the detected value of the yaw physical quantity detection means increases, the slip physical quantity reference is returned to a predetermined value, for example, so that in a turning state with a large yaw momentum, cornering force can be obtained sufficiently and the Ensuring stability is a priority. Further, in the invention according to claim 2, when the yaw momentum of the vehicle is small and the detected value of the yaw physical quantity detecting means is almost zero or a small value, the driving state determining means determines that the yaw physical quantity detected value is smaller than the reference value. In other words, it is determined that the vehicle is traveling straight or in a state close to traveling straight. This results in
Since the slip physical quantity adjusting means increases the slip physical quantity reference value above the predetermined value, the braking pressure control means performs braking pressure control based on this increased reference value, and the actual slip physical quantity follows the reference value. Become. The physical amount of slip controlled in this way is a deeper (larger) value than when turning, and the maximum grip force is obtained, and the deceleration is maximum when the vehicle is traveling straight or in a state similar to straight travel.
Although the cornering force decreases, the yaw momentum under such driving conditions is small and is caused by road surface disturbances, so the stability does not decrease.

On the other hand, in the driving state determining means,
When it is determined that the detection value of the yaw physical quantity detection means is equal to or greater than the reference value, the slip physical quantity reference value is lowered to a predetermined value because the vehicle is in a turning state with a large yaw momentum. As a result, sufficient cornering force is obtained, and priority is given to ensuring stability during turning braking.

0010

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 to 8. This embodiment is applied to an anti-skid control device for four independent wheels, and FIG. 2 shows the device configuration for one of the four wheels. In the same figure, 1
2 indicates a wheel, 2 indicates a hydraulic brake for the wheel 1, and 3 indicates an anti-skid control device.

The brake 2 has a brake pedal 7, a master cylinder 8, and a wheel cylinder 9 for braking the wheels 1. The anti-skid control device 3 includes a wheel speed sensor 10 that detects the wheel speed of the wheel 1, a longitudinal acceleration sensor 11 that detects the longitudinal acceleration of the vehicle, a brake switch 12 that detects the operation state of the brake 2, and a vehicle a controller 15 that outputs a signal for hydraulic pressure control of the wheel cylinder 9 based on the output signals of these sensors 10 to 13; and an actuator 16 that adjusts the hydraulic pressure.

The wheel speed sensor 10 is composed of an electromagnetic pickup installed at a predetermined position facing a rotor that is interlocked with the wheel 1, and outputs an AC voltage signal vi having a frequency proportional to the rotation speed of the wheel 1. The longitudinal acceleration sensor 11 is provided at a predetermined position on the vehicle body, and detects the acceleration in the longitudinal direction of the vehicle, and generates an acceleration signal g(t) made of an analog DC voltage corresponding to the acceleration, and converts it into a positive value in the case of vehicle deceleration. Output as . The brake switch 12 outputs a brake switch signal BS that is turned on and has a logical value of "1" when the brake pedal 7 is operated, and is turned off and has a logical value of "0" when the brake pedal 7 is not operated. Further, the yaw rate sensor 13 is composed of, for example, a piezoelectric vibrating gyroscope, and outputs a signal Ω corresponding to the yaw rate (rotational angular velocity) of the yaw motion acting on the vehicle when turning or the like to the controller 15.

The controller 15 includes a wheel speed calculation circuit 18 that outputs a wheel speed signal Vwi that is a voltage signal corresponding to the wheel speed, an integrator 19 that estimates the vehicle speed, and A/D converters 20 and 21. It includes a microcomputer 22 for calculation and control, and a drive circuit 23 for the actuator 16. The wheel speed calculation circuit 18 includes the wheel speed sensor 1
It is composed of a frequency/voltage converter that performs F-V (frequency-voltage) conversion on the zero detection signal vi to calculate the wheel speed signal Vwi. The output side of this wheel speed calculation circuit 18 reaches the initial value input terminal of the integrator 19, and also connects to the A/D converter 2.
1 to a microcomputer 22. The integrator 19 calculates the output g(t) of the longitudinal acceleration sensor 11.
is used as an input signal, and the switch signal BS of the brake switch 12 is used as a control input. When the switch signal BS has a logical value "1", the wheel speed Vwi at the time t0 when the switch signal BS rises to the logical value "1" is initialized. As a value, Vr
ef (t)=Vwi(t0)−∫g(t)dt
...The circuit has a circuit configuration that performs the integral calculation in (1) to pseudo-calculate the estimated vehicle speed signal Vref that changes to the side where the vehicle speed decreases. On the other hand, when the brake switch signal BS has a logical value of "0", the integrator 19 always resets the estimated vehicle speed signal Vref to the wheel speed signal Vwi(t) at that time, and Vr
Let ef (t)=Vwi(t). The output side of this integrator 19 is connected to a microcomputer 22 via an A/D converter 20.

The microcomputer 22 includes an input interface circuit 33, an arithmetic processing unit 34, and a storage device 35.
, and an output interface circuit 36. The arithmetic processing unit 34 reads each detection signal via the input interface circuit 33, and performs arithmetic and processing according to a predetermined program stored in advance (Figs.
(see FIG. 6), and outputs a control signal to the drive circuit 23 via the output interface circuit 36. The storage device 35 stores in advance fixed data such as programs and control maps necessary for the execution of processing by the arithmetic processing unit 34, and is also capable of temporarily storing the processing results.

The drive circuit 23 includes an amplifier, and based on the control signal output from the microcomputer 22, hydraulic pressure control signals EV,
It is designed to output AV and MR respectively. On the other hand, as shown in FIG. 3, the actuator 16 is connected to the wheel cylinder 9 and an inflow valve 42 which is a normally open electromagnetic on-off valve connected between the hydraulic pressure inflow side of the master cylinder 8 and the wheel cylinder 9. Outflow valve 4 consisting of a normally closed electromagnetic on-off valve
4, an accumulator 46 for accumulating pressure and an oil pump 48 for oil recovery connected to the output side of the outflow valve 44.
and a check valve 50 installed between the oil pump 48 and the master cylinder 8.

When the braking pressure is increased, the control signal E
By turning off V and AV, the inflow valve 42 is opened and the outflow valve 44 is closed, and the brake fluid pressure from the master cylinder 8 is transferred to the wheel cylinder 9 via the inflow valve 42. As a result, the brake pedal 7
When the pedal is depressed, the cylinder pressure increases. When the braking pressure is reduced, by turning on the control signals EV and AV,
The inflow valve 42 is "closed" and the outflow valve 44 is "open", so that the oil in the wheel cylinder 9 can be recovered to the master cylinder 8 side, and as a result, the cylinder hydraulic pressure decreases. moreover,
When the braking pressure is maintained, both the inflow valve 42 and the outflow valve 44 are closed by turning on the control signal EV and turning off the control signal AV, thereby making it possible to confine the oil in the wheel cylinder 9 and maintain its pressure. The control signal MR is turned on during anti-skid control, thereby driving the pump 48.

Next, the operation of the above embodiment will be explained with reference to FIGS. 4 to 8. When the ignition switch is turned on, the power is turned on and the device starts up. The AC voltage signal vi detected by the wheel speed sensor 10 is
The wheel speed calculation circuit 18 converts the signal into a wheel speed signal Vwi. This wheel speed signal Vwi is digitized by the A/D converter 21 and supplied to the microcomputer 22 as well as to the integrator 19.

Further, vehicle deceleration caused by sudden braking is detected by the longitudinal acceleration sensor 11 as a deceleration signal g(t) corresponding to the deceleration. The integrator 19 performs an estimation calculation of the vehicle speed according to the formula (1) from the time when the brake switch 12 is turned on (BS = "1"),
The results are output to the microcomputer 22. Furthermore, during the execution of a predetermined main program, the microcomputer 22 operates for a certain period of time (
For example, the timer interrupt processing shown in FIGS. 4 to 6 is executed every 20 msec.

First, the process shown in FIG. 4 will be explained. At step 101 in the figure, the arithmetic processing unit 34 reads the detection signal Ω of the yaw rate sensor 13, stores the value, and then proceeds to step 102. In step 102, the read value in step 101 is determined with respect to the first yaw rate reference value Ω1 (see FIG. 7, for example, 5 deg/sec) on the low-range side where the yaw rate is small and can be considered to be straight or straight travel. It is determined whether Ω| satisfies |Ω|≦Ω1.

If the result of this judgment 102 is NO, that is, it is judged that the yaw rate |Ω| exceeds the first reference value Ω1, the process moves to step 103 and the second reference value Ω2 is again determined.
(See Figure 7: For example, 15deg/sec) |
Determine whether Ω|≦Ω2. The second yaw rate reference value Ω2 here is a value set to be able to discriminate whether the yaw rate is large and the turning state is greater than a predetermined yaw movement.
Ω1 < Ω2 with respect to the first reference value Ω1. If NO in this judgment 103, that is, it is judged that the yaw rate |Ω| for S0 = S8
(for example, 8%). The slip ratio reference value S8 here is set to a value that generates a cornering force that can suppress the yaw rate that occurs during turning braking of a predetermined yaw momentum or more to a predetermined value.

[0021] On the other hand, if YES at step 103,
In other words, if the yaw rate Ω is Ω1 <Ω≦Ω2, it is assumed that the vehicle is not in a turning state at the predetermined yaw rate, but it is also not in a straight-ahead or nearly straight-ahead state, and step 1 is performed.
Move to 05. In step 105, the arithmetic processing unit 34 calculates S0 =-a・|Ω|+Sb (a, Sb
is a predetermined value (see FIG. 7).

Further, if the determination in step 102 is YES, that is, Ω≦Ω1, and the yaw rate Ω is small enough to be considered to be straight travel or nearly straight travel, the process then proceeds to step 106. In this step 106, the step rate reference value S0 is set to a constant value of S0 = S15 (for example, 15%). This reference value S15 is a deep (large) value that allows the vehicle to maximize deceleration when traveling straight or nearly straight.

After steps 104-106, processing returns to the main program. Next, the process in FIG. 5 will be explained. In step 121 in the figure, the arithmetic processing unit 34
The estimated vehicle speed signal Vref from the integrator 19 is read, the value is temporarily stored as the estimated vehicle speed, and the process proceeds to step 122. In step 122, the wheel speed signal Vwi from the wheel speed calculation circuit 18 is read and the value is temporarily stored as the wheel speed. Then step 123
Then, the wheel acceleration/deceleration αwi is calculated from the difference from the wheel speed Vwi related to the previous interrupt processing, and the value is temporarily stored. Next, the process moves to step 124, and Si = {(Vref - Vwi)/Vref }
×100 ... Wheel 1 based on the formula (2)
After calculating the slip ratio Si [%] and storing this value, the program returns to the main program.

Next, the process shown in FIG. 6 will be explained for each hydraulic pressure control state. This process includes wheel acceleration/deceleration αwi and slip rate Si that have been updated and set sequentially by the process shown in FIG.
(slip physical quantity). In FIG. 6, when the previous anti-skid control ended, the control flag AS
and the decompression timer L has been cleared (step 133
, 147).

First, the rapid pressure increase state (normal brake state) will be explained. Immediately after the start of braking, when the slip ratio Si and the wheel acceleration/deceleration αwi are small, step 13 in the figure
1 slip ratio Si ≧S0 (S0: latest slip ratio reference value) is determined to be “NO”, and step 132
If the determination of whether the decompression timer L>0 is "NO",
The process moves to step 133 to determine whether the control termination conditions are satisfied. Specifically, this judgment is based on the estimated vehicle speed Vr
This is done by determining whether or not ef is less than or equal to a predetermined value Vref0 corresponding to a stopped state, so the answer is "NO". Further, in step 134, it is determined whether or not the pressure reduction timer L>0, and the result is "NO", and in step 135, the wheel acceleration/deceleration αw
If i≧α1 (α1: reference wheel acceleration/deceleration on acceleration side (positive value)) is determined as “NO”, αwi in step 136
≦α2 (α2 is the reference wheel acceleration/deceleration on the deceleration side: negative value)
The result of the determination is "NO", and the process moves to step 137. In step 137, it is determined whether the control flag AS=0 or not, but since the control flag AS has been cleared before the start of anti-skid control, the answer is "YES".
Proceeding to step 138, a sudden pressure state (normal brake state) is commanded.

That is, the processing unit 34 instructs the actuator 16 to turn off the hydraulic pressure control signals EV and AV. Therefore, the inflow valve 42 is opened and the outflow valve 44 is closed, allowing oil from the master cylinder 8 to flow into the wheel cylinder 9. Therefore, when the brake pedal 7 is operated, a braking state (see section a in FIG. 8) occurs due to a sudden increase in cylinder hydraulic pressure (sudden pressure). Note that unless the brake pedal 7 is depressed, the non-braking state remains.

When the hydraulic pressure increases rapidly in this way, the wheel speed Vwi gradually decreases, the wheel acceleration/deceleration αwi increases in the negative direction, and the slip ratio Si increases. When the wheel acceleration/deceleration αwi falls below the reference value α2 on the deceleration side, ``YES'' is determined in the aforementioned step 136, and the process proceeds to step 139, where a pressure holding state on the high pressure side is commanded. That is, the arithmetic processing unit 34 instructs the hydraulic pressure control signal EV to be turned on and the hydraulic pressure control signal AV to be turned off. As a result, as shown in section b in FIG. 8, the oil in the wheel cylinder 9 is sealed and its pressure is maintained.

Since high pressure braking is performed even while this pressure is maintained, the slip ratio Si gradually increases.
Suppose that the value reaches or exceeds the reference value S0. As a result, the determination in step 131 of FIG.
1, sets the pressure reduction timer L to a predetermined initial value L0 (positive integer), and sets the control flag AS to indicate the start of anti-skid control. Then steps 133, 134
The process then proceeds to step 142 via which a reduced pressure state is commanded.

That is, the arithmetic processing unit 34 turns on all the hydraulic pressure control signals EV, AV, and MR. As a result, the inflow valve 42 is closed, the outflow valve 44 is opened, and the oil pump 48 of the actuator 16 is driven, so that the hydraulic pressure in the wheel cylinder 9 decreases as described above (see section c in FIG. 8). Due to this pressure reduction, the wheel speed Vwi gradually recovers and approaches the vehicle body speed. Then, when the wheel acceleration/deceleration αwi reaches the reference value α1, in step 140, “YE
S'', the pressure reduction timer L is cleared in step 143, and then the process moves to step 145 via steps 133 to 135 and 144, or if the slip ratio Si <S0 in step 131, step 13
The process moves to step 145 via steps 2 to 135 and 144. In this step 145, a pressure holding state on the low pressure side is again commanded.

That is, the arithmetic processing unit 34 performs the same control as in step 139 described above. As a result, the hydraulic pressure is maintained (see section d in FIG. 8). By maintaining this hydraulic pressure, the slip ratio Si is recovered and Si
When <S0 and α2 <αwi<α1 are satisfied, the process moves to step 146 via steps 131 to 137. In step 147, a slow pressure increase state is commanded.

That is, the arithmetic processing unit 34 turns on the hydraulic control signal EV, turns off the hydraulic pressure control signal AV, and turns off the signal EV in a stepwise manner with the inflow valve 42 closed and the outflow valve 44 closed. The inflow valve 42 is opened for a short period of time, and this is repeated at predetermined time intervals. Therefore, the hydraulic pressure increases in a substantially stepwise manner as shown in section e in FIG. Thereafter, the anti-skid cycle of reducing the pressure in the wheel cylinder 9, holding the pressure, slowly increasing the pressure, and holding the pressure is repeated until the braking is completed and the above-mentioned control termination condition is satisfied. When the control termination condition is satisfied, the pressure reduction timer L and control flag AS are cleared in step 147, and the routine returns to the normal braking state in step 138.

Note that during braking on a high friction coefficient road, etc., if the slip ratio Si improves to below its reference value S0 faster than the recovery of the wheel acceleration/deceleration αwi while the pressure is being reduced, steps 131 and 132 are performed. via step 148
to move to. Then, in step 148, the pressure reduction timer L=L-1 is activated to wait. After this standby, the slow pressure increase according to step 146 is commanded before the pressure holding state according to step 145.

Although the above processing has been explained for one wheel of the vehicle, the other three wheels are also processed in the same way. In this embodiment, the yaw rate sensor 13 and the process of step 101 in FIG.
, 103 correspond to the driving state determining means, and the processes of steps 104 to 106 in FIG. 4 correspond to the slip physical quantity adjusting means. Wheel speed sensor 10, brake switch 1
2, longitudinal acceleration sensor 11, wheel speed calculation circuit 18, integrator 19, A/D converters 21, 22, and step 1 in FIG.
The processes 21, 122, and 124 constitute a slip physical quantity detection means. Further, step 131 in FIG. 6 corresponds to a slip situation determining means, and step 123 in FIG. 5, the processing in steps 132 to 148 in FIG. 6, the drive circuit 23, and the actuator 16 constitute a braking pressure control means.

Next, the overall operation will be explained using FIG. 8. In addition, since the horizontal dashed-dotted line indicating the speed in the figure is the target wheel speed corresponding to the slip ratio reference value S0, the intersection of this target wheel speed and the actual wheel speed Vwi becomes the slip ratio Si = S0. to show that The yaw rate Ω is detected based on the output signal of the yaw rate sensor 13 at regular intervals, and if the detected value |Ω| is a large value greater than a predetermined turning state, a smaller slip rate reference value S0 =
S8 is set. In this state, assume that sudden braking is started at time t0. As a result, the brake switch 12 is turned on, and the integrator 19 uses the wheel speed Vwi(t0) at time t0 as an initial value, and calculates the estimated vehicle speed Vref based on the above-mentioned equation (1) as shown in FIG.

At the beginning of this turning braking, since both the slip ratio Si and the wheel acceleration/deceleration αwi are small, a rapid pressure increase is commanded (step 138 in FIG. 6), and the cylinder hydraulic pressure rapidly increases. Along with this, the wheel speed Vwi decreases, and at time t
1, the wheel acceleration/deceleration αwi=α2, so t1
Thereafter, a pressure holding state is commanded (step 139 in the figure). This pressure holding state is at the time t when the slip ratio Si = S0.
Continued until 2.

After time t2, the slip ratio Si≧S0 and the wheel acceleration/deceleration αwi<α1 are satisfied, so that a pressure reduction state is commanded (step 142 in the figure). This pressure reduction restores the wheel acceleration/deceleration αwi, and αwi
At time t3 when =α1, a pressure holding state on the low pressure side is set (step 145 in the figure). During this pressure holding state, the wheel speed Vwi sufficiently recovers, and at time t4, when Si<S0 and α2 <α<α1, the pressure increase condition is satisfied again, and a slow pressure increase state is set (step 6 in FIG. 146). This gradual pressure increase state continues with Si < S0 until time t5 when αwi=α2, and thereafter, the pressure holding state on the high pressure side is set in the same manner as described above until time t6 when Si = S0. Thereafter, similarly, pressure reduction, holding, gradual pressure increase, etc. are repeated until the end of braking, and the slip ratio Si is adjusted with reference value S8 as the target.

[0037] As a result, it is possible to obtain an appropriate deceleration based on a friction coefficient slightly lower than the maximum friction coefficient,
In addition, since the target slip ratio is set slightly lower, the cornering force during cornering braking increases, and cornering stability can be improved. On the other hand, when the vehicle is traveling straight or can be considered to be traveling almost straight, the slip ratio reference value S0 is set to a value S15 that is higher (deeper) than that during turning braking. Therefore, by using the same braking pressure control as described above, with reference value S15 as the target value, the actual wheel slip rate becomes deeper than during turning braking, and the maximum deceleration is achieved depending on the friction coefficient in the maximum range. can get. on the other hand,
Cornering force is reduced by controlling the slip ratio more deeply. However, the cornering force to ensure the stability of the vehicle when driving straight or nearly straight is sufficient to overcome road disturbances, and originally only needed a small value, so even if the cornering force decreases, Sufficient stability is ensured.

Furthermore, the yaw rate Ω is Ω1 <|Ω|≦
When Ω2 is moderate, the running condition is assumed to be between a predetermined turning state and a state that can be considered to be traveling straight, and the slip ratio is set to a value that decreases as the yaw rate increases and approaches the slip ratio reference value S8 for the predetermined turning state. be done. As a result, the cornering force is increased as the yaw rate associated with turning increases, and swinging of the vehicle due to the increased yaw momentum is prevented, and high stability can be maintained.

By the way, the above explanation was about normal driving on city roads and expressways, but in addition, for example, in the case of car racing, the first and second yaw rate reference values Ω1,
Ω2 as appropriate (for example, Ω1 = 10deg/sec,
By setting the value to Ω2 = 25 deg/sec), a braking condition suitable for car racing can be obtained. In other words, in the low yaw rate range, the average slip ratio is greater than in the high yaw rate range, and the cornering force is reduced, allowing the occupant to control the vehicle attitude by actively using the brakes. However, even in a car race, if a certain set value Ω2 is exceeded, in order to avoid an uncontrollable state of the vehicle attitude, as in the past,
By lowering the average slip rate and increasing cornering force, it is possible to prioritize ensuring turning stability.

In addition to the slip rate, the slip amount (vehicle speed - wheel speed) may be used as the slip physical quantity in the present invention. Further, if a map or the like for calculating a slip ratio reference value as shown in FIG. 7 according to the detected value of the yaw rate sensor is provided, the driving state determining means may not be provided. In addition, although the slip physical quantity adjusting means in the present invention provides different first and second values Ω1 and Ω2 as the yaw rate reference value as in the above-mentioned embodiment, this reference value is set to one value when driving. The states may be discriminated, or, if two values are provided, a slip ratio reference value may be set that changes in a stepwise manner for driving states that fall between both reference values. .

Furthermore, the yaw physical quantity detecting means in the above embodiment detects the yaw rate, and the driving state determining means compares the yaw rate reference value (yaw physical quantity reference value) with the yaw rate, but the yaw physical quantity detecting means of the present invention As a means, the yaw angular acceleration and the yaw rate are detected, and the running state is judged by appropriately combining the comparison between the yaw angular acceleration and its reference value and the comparison between the yaw rate and its reference value in the running state judgment means. This provides high responsiveness based on determining the yaw angular acceleration and reliability based on determining the yaw rate.

Furthermore, as a yaw physical quantity detection means,
Although a piezoelectric vibrating gyro was used, the lateral acceleration,
The configuration may be such that the estimation is performed by calculation using vehicle speed or the like. Furthermore, the controller 15 in the embodiment described above may be configured entirely by a computer, while the microcomputer 22 may be configured as a counter,
It can also be configured by electronic circuits such as comparators and flip-flops. On the other hand, the brake 2 in the above embodiment
may be a drum type brake or a disc type brake. Further, the present invention can be applied not only to an anti-skid control device that controls four wheels independently, but also to an anti-skid control device that controls two rear wheels, for example.

Furthermore, in the above embodiment, the case where the pressure increase is performed again in a slow pressure increase mode has been described, but this may also be a linear pressure increase similar to that during normal braking. Further, the present invention can be similarly applied to a case where a pressure holding state on the low pressure side is not set.

[0044]

As described above, the anti-skid control device of the present invention detects a physical quantity related to yaw motion such as a yaw rate, and, for example, determines a slip physical quantity reference value according to the detected value. The detected value and the yaw physical quantity reference value are compared and judged, and if the detected value is smaller than the reference value, the slip physical quantity reference value such as the slip ratio is increased. Therefore, using the yaw physical quantity, it is possible to accurately distinguish between straight and near-straight running states and other turning states, and thereby wheel slip in the braking state during straight and near-straight running reduces deceleration. By setting a predetermined deep value to be prioritized, the maximum deceleration can be obtained and the shortest braking distance can be obtained.Although the cornering force is reduced, the cornering force when driving straight or almost straight is originally small. Therefore, stability is still maintained well, and in the case of braking during a turn, the physical amount of wheel slip returns to a predetermined shallow value, and sufficient cornering force is obtained, resulting in good stability and steering performance. is maintained. In particular, if the present invention is applied to car races, etc., it becomes possible to actively control the vehicle attitude using the brakes even when the yaw physical quantity is small.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram.

FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 3 is a block diagram showing an example of an actuator.

FIG. 4 is a flowchart illustrating an example of a process for setting a slip ratio reference value according to a yaw rate.

FIG. 5 is a flowchart illustrating an example of slip rate calculation processing.

FIG. 6 is a flowchart showing an example of a procedure for anti-skid control.

FIG. 7 is a graph showing an example of a change in slip ratio reference value with respect to yaw rate.

FIG. 8 is a timing chart showing an example of braking pressure control.

[Explanation of symbols]

1 Wheel 2 Brake 3. Anti-skid control device 10 Wheel speed sensor 11 Longitudinal acceleration sensor 12 Brake switch 13 Yaw rate sensor 15 Controller 16 Actuator 18 Wheel speed calculation circuit 19 Integrator 20 A/D converter 21 A/D converter 22 Microcomputer 23 Drive circuit

Claims (2)

[Claims] 1. Slip physical quantity detecting means for detecting a slip physical quantity related to wheel slip; slip condition determining means for comparing and determining a detection value of the slip physical quantity detecting means with a changeable slip physical quantity reference value; In an anti-skid control device, the anti-skid control device includes a brake pressure control means for controlling the braking pressure of a wheel based on a rotational condition of the wheel including a judgment result of the judgment means, and a yaw physical quantity detection means for detecting a yaw physical quantity related to a yaw motion of the vehicle. ,
An anti-skid control device comprising: slip physical quantity adjusting means for setting the slip physical quantity reference value according to the detected value of the yaw physical quantity detecting means. 2. Slip physical quantity detecting means for detecting a slip physical quantity related to wheel slip; slip condition determining means for comparing and determining a detection value of the slip physical quantity detecting means with a changeable slip physical quantity reference value; In an anti-skid control device, the anti-skid control device includes a brake pressure control means for controlling the braking pressure of a wheel based on a rotational condition of the wheel including a judgment result of the judgment means, and a yaw physical quantity detection means for detecting a yaw physical quantity related to a yaw motion of the vehicle. ,
a traveling state determining means for comparing and determining the detected value of the yaw physical quantity detecting means and a preset yaw physical quantity reference value, and when the traveling state determining means determines a traveling state of a yaw motion equal to or greater than the yaw physical quantity reference value; When the slip physical quantity reference value is set to a predetermined value and the running state determining means determines a running state with a yaw motion smaller than the yaw physical quantity reference value, the slip physical quantity reference value is set to a value larger than the predetermined value. 1. An anti-skid control device comprising: a slip physical quantity adjusting means for setting a slip physical quantity;