JPS6128540B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid control device that prevents a braking target straight line from being erroneously set during braking due to road conditions such as an uneven road surface.

Conventionally, this type of anti-skid device has controlled the wheel speed during braking to a braking target wheel speed that provides maximum braking efficiency (slip rate of around 15%). The person, etc., determines the wheel speed at which the slip rate is around 15% for each skid cycle, the set deceleration or set acceleration,
Alternatively, we have proposed a method in which the peak value of the coefficient of friction with the road surface is detected, and the braking target value for successive skid cycles is sequentially set based on the detected wheel speed (Japanese Patent Application No. 129375/1989 −53944
], 54-149451 [Unexamined Japanese Patent Publication No. 56-75242], 54
−129374 [Unexamined Japanese Patent Publication No. 56-53943]).

For example, if we take the method of setting the target wheel speed using the set deceleration as an example, as shown in Figure 1, the wheel speed when the wheel deceleration α _w reaches the set deceleration α _b in each skid cycle. v _w1 , v _w2 , v _w3 , ...... is detected, and the braking target wheel speed v is determined by the slope (deceleration) determined by each of v _w1 and v _w2 , v _w2 and v _w3 , ...
_w01 , v _w02 , v _w03 , . . . are set sequentially. Note that in the first cycle, a target wheel speed v _G with a predetermined slope is set.

By the way, in skid control on well-maintained paved roads with relatively few irregularities, the coefficient of friction with the road surface changes relatively slowly during braking, and the coefficient of friction with the road surface changes suddenly during braking. Although this is rare, if you come across an uneven road surface that has a lot of bumps while braking, the car body will bounce if the bumps are large, and this bouncing will cause the balance of the load distribution to each wheel to become unbalanced. It begins to crumble for a moment, and at this time the coefficient of friction with the road surface suddenly changes.

For example, as shown in FIG. 2, in the skid cycle after setting the braking target wheel speed _vw01 at time _t1 , during brake oil pressure reduction when the wheel speed _vw recovers toward the vehicle speed _vc , If the wheels start to float due to the bounce caused by the above irregular road surface, the coefficient of friction with the road surface will suddenly decrease and the wheel speed v _w will start to decelerate, so at time t ₂ the wheel deceleration α _w
reaches the set deceleration α _b again. When the set deceleration α _b is reached at time t ₂ , the wheel speed v _w2 at that time is detected, and the braking target wheel speed has a slope determined by the wheel speed v _w1 detected at time t ₁ . v There is a problem that _w02 may be set incorrectly.

The present invention has been made in view of the above, and in order to prevent the braking target straight line from being set incorrectly depending on road conditions in the method of sequentially setting the braking target straight line for each skid cycle, the braking target straight line is and a straight line having a value that is below this straight line by a predetermined value, and only when the wheel speed is within this range, a new braking target straight line is allowed to be set. It is.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 3 is a block diagram showing one embodiment of the present invention. First, to explain the configuration, 1 is a wheel that is skid-controlled, 2 is a wheel speed sensor that detects an AC signal (the number of pulses may be used) with a frequency proportional to the rotation of the wheel 1, and 3 is a wheel speed sensor that detects an AC signal of the wheel speed sensor 2. An f-V converter converts and outputs a voltage proportional to the frequency as the wheel speed v _w ; 4 is a deceleration detection circuit that differentiates the wheel speed v _w and detects its deceleration α _w ; 5 is a deceleration detection circuit that detects the wheel deceleration α _w ; A comparator 6 generates an e _b1 signal which becomes an H level output when a set deceleration α _b determined according to the deceleration when the slip rate is around 15% is reached, that is, when α _w > α _b . a target value generation circuit that detects the wheel speed v _w every time the set deceleration α _b is obtained and sequentially sets the braking target wheel speed v _w0 ;
8 is a reference value generation circuit that outputs a reference value v _s obtained by multiplying the generated braking target value by a predetermined coefficient or subtracting the predetermined value, and 8 is a reference value generation circuit that compares the wheel speed v _w and the reference value v _s. When v _w ≧v _s , H level output, and v _w
A comparator 9 outputs an e _b2 signal which becomes an L level output when <v _s , and an AND gate 9 provides an e _b signal which is an AND output of the e _b1 signal and e _b2 signal to the target value generation circuit 6. In addition, the reference value generation circuit 7 mentioned above
This is realized by an attenuator, a multiplier, a subtracter, or the like.

Next, the operation will be explained with reference to the time chart shown in FIG.

Assuming that braking is started at time t ₀ , the wheel speed v _w begins to decelerate while increasing the slip rate due to the increase in brake oil pressure, and the deceleration α _w reaches the set deceleration α _b at time t ₁ . . At this time, the reference value generation circuit 7 outputs a reference value v _s0 obtained by multiplying the wheel speed at time t ₀ by a predetermined coefficient, and since v _w >v _s0 , the comparator 8 outputs an H level output. The e _b1 signal of the comparator 5, which becomes an H level output at time _t1 , is sent to the target value generation circuit 6 via the AND gate 9.
command to generate the target value v _w01 . However, the target value v _w01 of the first cycle is generated with a predetermined slope. At this time, the reference value generation circuit 7 generates the target value v
A reference value v _s1 obtained by multiplying _w01 by a predetermined coefficient is generated.

Furthermore, when the wheel speed v _w continues to decelerate and falls below the reference value v _s1 at time t ₂ , the output e of the comparator 8
_b2 goes from H level to L level, and this state is changed to v
Maintain as long as _w < v _s1 . Therefore, the AND gate 9 becomes inhibited, and the e _b signal generated by the AND gate 9 returns to the L level.

Below, similarly, the time at which the set deceleration α _b is obtained
The above operation is repeated in each skid cycle of t ₄ , t ₈ , ......, and the braking target values v _w02 , v _w03 , ...
...Set one after another.

By the way, during the skid cycle from time _t4 , for example, due to the bounce of the car body, the friction coefficient μ
Suppose that suddenly decreases, the wheel speed during recovery v _w
starts to decelerate due to the decrease in μ, so that the wheel deceleration α _w reaches the set deceleration α _b at time t ₆ and the output e _b1 of the comparator 5 becomes H level. However, since the wheel speed v _w at this time is lower than the reference value v _s2 , the output e _b2 of the comparator 8 goes to L level and inhibits the AND gate 9, so the e _b signal is generated. Since the target value generation circuit 6 is not instructed to set a target value, an erroneous target value will not be generated.

Here, referring to how to determine the reference value v _s in the above embodiment, if the difference from the braking target value v _w0 is small, for example, as in the reference value v' _s shown in FIG. When the road changes, even if a predetermined wheel deceleration is detected, the wheel speed v _w falls below the reference value v _'s , so the wheel speed (v _w ) _o is not detected in order to obtain the correct braking target value. Therefore, even when the coefficient of friction with the road surface changes from the lowest μ road, e.g. deceleration 0.1G, to the highest μ road, e.g. 0.8 to 0.9G, the set deceleration α _b is obtained after the change. The ratio is determined so that the wheel speed (v _w ) _o detected at the time does not fall below the reference value v _s (for example, the reference value is determined to be v _s in FIG. 5).

The above embodiment takes as an example a method in which the braking target value is sequentially set by detecting the wheel speed when the set deceleration α _b is obtained. The same applies to the method of sequentially setting the braking target value based on the set acceleration or wheel speed obtained from the peak value of the friction coefficient, and furthermore, the system sequentially generates the target value that results in a predetermined deceleration for each skid cycle. Similarly, in the conventional method, setting of the target value can be stopped when v _w <v _s .

As explained above, according to the present invention, while the wheel speed is below a predetermined value determined based on the brake target value that is sequentially set for each skid cycle, the brake target value is Since new settings are canceled, even if the friction coefficient suddenly changes during braking due to an uneven road surface, for example, and the wheel speed changes irregularly, the system will prevent incorrect braking target values from being set due to such external disturbances. This solves the problem of storage and provides the effect that the braking target value can be reliably set even if braking conditions suddenly change.

[Brief explanation of the drawing]

FIG. 1 is a graph showing an example of the braking target value setting method proposed by the inventors, FIG. 2 is a graph showing a problem when μ suddenly changes during braking, and FIG. The figure is a block diagram showing one embodiment of the present invention, Fig. 4 is a time chart showing the operation of Fig. 3, and Fig. 5 is a method of setting the reference value _vs used in the embodiment of Fig. 3. FIG. 1...Wheel, 2...Wheel speed sensor, 3...f
-V converter, 4... Deceleration detection circuit, 5, 8...
Comparator, 6... Target value generation circuit, 7... Reference value generation circuit, 9... AND gate.

Claims (1)

[Claims] 1. In an anti-skid control device that sequentially sets a braking target wheel speed for each skid cycle, when the braking target wheel speed is set, a reference value that becomes a wheel speed that is lower than the braking target wheel speed by a predetermined value. and setting a new braking target wheel speed only when a predetermined wheel deceleration is detected and the wheel speed is equal to or higher than the reference value generated by the target value generating means. 1. An anti-skid control device, characterized in that it has a permitting means for permitting.