JP2628474B2 - Vehicle braking control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention accurately applies a failed wheel to a braking control device of a vehicle, particularly, in order to promptly deal with the failure when the failure occurs in a brake system. In addition, the present invention relates to a braking control device that can be quickly certified.

(Prior Art) In a vehicle, a hydraulic brake system having two or more independent brake systems is often adopted from a safety point of view. In such a case, is there a shortage of brake fluid as hydraulic oil? As means for checking whether or not the brake fluid is present, a reservoir for the system is usually provided with a brake fluid level sensor for detecting the brake fluid level. Then, for example, when a failure occurs in the brake system, the brake fluid level in the reservoir decreases,
Usually, it is configured to be able to know whether or not the brake has failed by looking at the signal from the level sensor.

Further, as a conventional vehicle brake control device, there is a device called an anti-lock brake system or an anti-skid brake system (ABS). this is,
A wheel speed detecting means (wheel speed sensor) for detecting a rotation speed of each wheel, that is, a wheel speed, and an electromagnetic valve provided on a hydraulic passage leading to each brake means are provided. The brake fluid pressure to each brake means is adjusted by controlling each solenoid valve based on the above, thereby preventing the wheels from being locked or skid during braking. In a vehicle employing this ABS, the presence or absence of a failure in the brake system can be determined by checking the deceleration state of the wheel during braking using the wheel speed detection means. That is, if the brake system has not failed, the wheels normally decelerate with a negative wheel speed change rate that is equal to or greater than a predetermined value corresponding to the braking force, and if the brake system has failed, braking of the normal wheels is performed. Since only a negative wheel speed change rate corresponding to the deceleration of the vehicle body caused by the vehicle speed occurs, it is determined whether the brake system has failed by determining these based on the output of the wheel speed detecting means. It is possible to detect whether or not.

(Problems to be Solved by the Invention) By the way, in a conventional braking control device for a vehicle having a plurality of brake systems as described above, when a failure occurs in any of the brake systems, the failure is There has been a problem that the generated brake system and the failed wheel cannot be accurately identified. For example, if the signal from the brake fluid level sensor indicates that the brake fluid in the reservoir is insufficient, it can be known that a failure has occurred in any of the brake systems. Or you can't tell if a wheel is missing.

In addition, when the above ABS is adopted, it is possible to detect a failure of the brake system by using the wheel speed detection means as described above, but the failure detection in this case is concrete. For example, the following problem may occur depending on how the threshold value is set because the difference between the wheel speed change rate of the non-brake wheel and the brake wheel is determined by referring to the threshold value. become. In other words, if the threshold value is set to a relatively small value, the failure can be detected earlier by that much, but on the other hand, due to the influence of disturbance such as a difference in the contact state of each wheel, At the time of gentle braking, there is a possibility that the vehicle may be erroneously determined to be in a failure state despite being in a non-failure state. Conversely, if the threshold is set relatively high, such a misperception will not occur,
It takes much time to detect the failure by that much, or the detection accuracy decreases.

The present invention addresses the above-described problems related to a vehicle brake control device, and particularly in a vehicle equipped with ABS,
It is an object of the present invention to provide a vehicle brake control device capable of quickly and accurately detecting and specifying a brake system or a wheel in a failed state when a brake system has failed.

(Means for Solving the Problems) In order to achieve the above object, the present invention is characterized in that it is configured as follows.

That is, it has brake means provided on each of the left, right, front and rear wheels, and a brake fluid pressure source for generating a brake fluid pressure for each brake means at the time of a brake operation, and the brake fluid pressure source and each brake means A plurality of brake systems are provided between the first and second brake systems, and the brake fluid pressure to each of the brake units is adjusted based on the output from the wheel speed detection unit that detects the wheel speed of each wheel during braking. In a vehicle equipped with an anti-skid brake system that prevents wheels from skidding,
A brake fluid level detecting means for detecting a brake fluid level in the reservoir; a wheel speed change rate detecting means for detecting a wheel speed change rate of each wheel based on an output of each wheel speed detecting means; and the anti-skid brake A failed wheel identifying means for identifying a failed wheel based on a wheel speed change rate of each wheel indicated by an output of each wheel speed change rate detecting means during operation of the system; Receiving each output of the wheel discriminating means, the output of the brake fluid level detecting means indicates that the brake fluid level in the reservoir is equal to or less than a predetermined value, and the output of the failed corresponding wheel identifying means indicates the value of the failed corresponding wheel. A failed wheel identifying means for identifying the failed wheel as a failed wheel when presence is indicated.

(Operation) According to the above configuration, the failed wheel identification means for identifying the failed wheel based on the wheel speed change rate of each wheel, and the brake fluid level detecting means for detecting the brake fluid level in the reservoir. Based on the outputs of both means, when the brake fluid level in the reservoir is equal to or less than a predetermined value and there is a failed wheel, the failed wheel is determined to be a failed wheel. Can be detected up to the point such as whether or not there is a failure. In addition, since the output of the brake fluid level sensor, which can detect whether or not the brake system has failed, is also considered, there is a problem that the normal state is mistakenly regarded as the failure state at the time of gentle braking. Can be prevented.

(Example) Hereinafter, an example of the present invention will be described.

FIG. 1 shows an example in which the present invention is applied to a so-called variable volume ABS having two pipes. As shown in FIG. 1, the braking control device according to this embodiment includes left and right front wheels 1, 2 and First and second brake means 1a, 2a and 3a, 4a comprising disc brakes or drum brakes respectively provided on the rear wheels 3, 4;
A tandem-type master cylinder 5 having a cylinder chamber 5a and a second cylinder chamber 5b and generating brake fluid pressure in each of the cylinder chambers 5a and 5b by depressing a brake pedal 6 is provided. The first cylinder chamber of the master cylinder 5
The hydraulic passage 7 led from 5a is branched into two branches in the middle,
One end of the first passage 7a is connected to the right front wheel brake means 2a, and the other end of the second passage 7b is connected to the left rear wheel brake means 3a. Also, the master cylinder 5
Of the hydraulic passage 8 led from the second cylinder chamber 5b
One end of the third passage 8a is connected to the left front wheel brake means 1a, and the other end of the fourth passage 8b is connected to the right rear wheel brake means 4a.

In this case, in this embodiment, the first to fourth
In the passages 7a, 7b, 8a, 8b, the variable volume modulators 9, 10,
11 and 12 are provided respectively. These modulators 9
Numerals 12 to 12 are for appropriately adjusting the brake fluid pressure supplied from the master cylinder 5 to the brake means. Since each has the same configuration, the modulator 9 provided on the first passage 7a is used here. Will be described, and description of the other modulators 10 to 12 will be omitted.

The modulator 9 has a first chamber 9b and a second chamber 9c defined by a piston 9a therein, and the second chamber 9c forms a part of the first passage 7a. A spring 9d provided on the side 9c of the second chamber urges the piston 9a toward the first chamber 9b via a ball 9e and a piston rod 9f. The first chamber 9b has one end connected to the discharge side of the hydraulic pump 13 and opened / closed by a working pressure supply solenoid valve 14, and one end connected to the suction side of the hydraulic pump 13. A discharge passage 17 which is opened and closed by a working pressure discharge electromagnetic valve 16 is connected after being joined. Then, by appropriately opening and closing the supply electromagnetic valve 14 and the discharge electromagnetic valve 16 by the controller 18,
The pressurized hydraulic oil (brake fluid) is supplied from the pump 13 to the first chamber 9b via the supply passage 15, and the piston 9a
Is moved toward the second chamber 9c against the spring 9d, or the first chamber
The hydraulic oil in the first chamber 9b is discharged to the second chamber 9b by discharging the hydraulic oil in the discharge passage 17 to the second chamber 9b.
By changing the volume of the chamber 9c, the brake fluid pressure supplied from the master cylinder 5 to the brake means 2a via the first passage 7a during braking is adjusted. Further, in the modulator 9, when the piston 9a is moved by a predetermined amount toward the first chamber 9b as described above,
The passage portion forming a part of the first passage 7a is the ball
It is to be shut off by 9a.

Similarly, the other modulators 10 to
12, a supply passage 22 to 24, which is opened and closed by each of the supply solenoid valves 19 to 21, and a discharge passage 28 to 30, which is opened and closed by each of the discharge solenoid valves 25 to 27, are connected. The opening and closing control of the electromagnetic valve by the 18 adjusts the brake fluid pressure to the brake means 1a, 3a, 4a. The hydraulic pump 13 is driven by the motor 31 to pressurize the hydraulic oil and discharge the hydraulic oil.In this case, as means for holding the hydraulic pressure of the hydraulic oil discharged from the pump 13 at a predetermined pressure, An accumulator 32 is connected to a passage portion between the pump 13 and the supply passage 15 and the like.

Further, in addition to the above configuration, this braking control device includes:
A reservoir 33 is connected to a passage from the junction of the discharge passages 17, 28 to 30 to the supply side of the hydraulic pump 13, and a brake fluid (hydraulic oil) inside the reservoir 33 is connected to the reservoir 33.
And a wheel speed sensor 1b-4b for detecting the rotational speed of each of the wheels 1-4, respectively. And
The controller 18 opens and closes the supply and discharge solenoid valves 14, 19 to 21 and 16, 25 to 27 based on the outputs of the wheel speed sensors 1b to 4b and the brake fluid level sensor 34, respectively. Control.

Next, the operation of the control 18, which is a feature of the present invention, will be described with reference to the flowchart shown in FIG.

After the controller 18 Step S ₁ as shown in FIG reads the output from the brake fluid level sensor 34 of the reservoir 33, the output whether the ON state in step S _2, i.e. the brake fluid in the reservoir 33 Then, it is determined whether or not the liquid level is below a predetermined value. If the brake fluid level has dropped to a predetermined value or less, it is determined that a failure has occurred in any of the brake systems shown in FIG.
In terms of reading the output that is the wheel speed of each wheel 1-4 from the wheel speed sensors 1b~4b following steps S _3, further executes the step S _4, S _5. Among one step S ₄ is the difference between the wheel speed change rate between predetermined wheel (the threshold position) respectively calculated using the wheel speeds of the respective wheels 1 to 4, step
In S _5, whether the wheel speed change rate exists wheels exceeds the threshold, i.e. the wheel speed change rate of the wheel is determined whether more than a threshold, if exceeded While the wheel is determined to be a non-failed wheel, if not, the wheel is determined to be a failed wheel. This determination operation means the following.

That is, when a braking operation is performed in this system, as shown in the graph of FIG. 3, the wheel speed of the normally braked wheel decreases in a pattern corresponding to the braking oil pressure, but the non-braking wheel, that is, the failed wheel Does not decrease like the above-mentioned brake wheel. Therefore, it is determined whether or not the wheel speed change rate of the wheel is within a range (threshold) from the wheel speed change rate of the non-braking wheel to the wheel speed change rate of the brake wheel. If there is, the wheel is determined to be the wheel corresponding to the fault, while if not, the wheel is determined to be the wheel corresponding to the fault.

Also, after identifying the faulty appropriate wheels in this way, by executing step S _6, but its failure relevant wheel is determined whether one wheel, perform such operations This is because the two-system piping is employed in this embodiment. That is, even if it is determined whether or not there is a wheel exceeding the threshold, for example, the right front wheel 2 and the left rear wheel 3 belonging to one brake system and the left front wheel 1 and the right This is because, for example, when the threshold value of the rear wheel 4 is equal to or more than a predetermined value, it is still unknown which of the left front wheel 1 and the right rear wheel 4 has failed. Then, it is determined in step S _6, by failure corresponding wheel executes step S ₇ if one wheel, the control for interrupting the braking circuit between the failure corresponding wheels and the master cylinder 5 This control is performed as follows, for example.

That is, assuming that the passage portion (indicated by X in FIG. 1) between the right front wheel brake means 2a and the modulator 9 has failed, the controller 18 turns on the supply electromagnetic valve 14. By outputting a signal to close the valve 14 and outputting an ON signal to the discharge solenoid valve 16 to open the valve 16, the hydraulic oil in the first chamber 9b of the modulator 9 is discharged. It is discharged to the passage 17. As a result, the modulator 9
The piston 9a and the ball 9e connected thereto move to the left in the drawing, and the ball 9e blocks the passage portion on the second chamber 9c side. As a result, the first passage 7a is shut off in the modulator 9, so that even if the brake fluid in the passage between the modulator 9 and the brake means 2a leaks from the lost portion X, The brake circuits other than the passage portion X operate normally without breaking the influence of the failure.

On the other hand, if it is determined that the failure corresponding wheels in step S ₆ there are two wheels, by executing the step S _8, first, one of the genus one of the two failure corresponding wheel Brake circuit (for example, right front wheel 2 and left rear wheel 3
On bets are in the case of failure the relevant wheel with one) of said first passage 7a and the second passage 7b blocked within the modulator 9 or 10 in the same manner as above, the following steps S ₉ Run. In step S _9, the wheel speed change rate of the failure corresponding wheel belonging to the other brake circuit which has not been cut off in step S ₈ is, as was done in step S _5, whether exceeds the threshold to determine, by if exceeds the threshold value the blocked towards relevant wheels only failure in finding that failure wheels, but maintains its interrupting operation, executes step S ₁₀ is otherwise I do. That is, in this case, certifies other failure relevant wheel and failure wheels, while blocking the brake circuit belongs failure wheels and the accreditation in the modulator, the braking circuit is interrupted in step S ₈ As for, it is considered that there is no failure, and the above-mentioned interruption operation is released.

Thus, according to the above configuration, the controller 18
Not only the output from the brake fluid level sensor 34 for detecting the brake fluid level of the reservoir 33 but also the output from each of the wheel speed sensors 1a to 4b for detecting the wheel speed of each of the wheels 1 to 4 is used to detect the failed wheel. Since the detection can be performed, it is possible to accurately detect a failed wheel that cannot be performed only from the output of the level sensor 34, and it is possible to quickly shut off the brake circuit to which the detected failed wheel belongs. Thus, safety in the event of a failure is improved.

The controller 18 may perform control as shown in the flowchart of FIG. 4 instead of the control as shown in the flowchart of FIG. In the fourth control shown in figure, first it is determined whether the brake fluid level in the reservoir from the brake fluid level sensor is output an alarm signal indicating that the predetermined value or less in step R _1, is outputted since failure in any brake system if Re has occurred, upon setting a relatively small threshold for the calculated and the wheels of each wheel speed change rate according to step R _2, the said threshold whether the wheel speed change rate of the wheel has exceeded determines in step R _3. If the wheel speed change rate of the wheel exceeds the threshold value, the wheel is determined to be a failed wheel, and if not, it is determined to be a non-failed wheel. Thereby, when the alarm signal of the level sensor is generated, that is, when the brake system fails,
The detection operation of the failed wheel is advanced earlier by the smaller the threshold value is set.

On the other hand, if the level sensor does not generate an alarm signal, after setting the threshold for the calculated and the wheels of each wheel variation rate to a relatively large value in accordance with step R _4, Step R ₅ by executing, while the wheel speed change rate of the wheel it is determined whether it exceeds the threshold value, identified as exceeding long as it similarly to the case the wheel of the step R ₃ failure wheels If not, it will be recognized as a non-falling wheel. In this case, the threshold value is set to a relatively large value, which means that a wheel exceeding the threshold value has a considerably abnormal wheel speed change rate. Therefore, if the threshold value is exceeded as described above,
The wheel can be reliably identified as a failed wheel. In other words, when the threshold value is set to a small value, there is a possibility that a failure may be recognized even though the failure is not caused at the time of gentle braking due to the influence of a disturbance such as a difference in the contact state of each wheel. Such inconveniences can be avoided beforehand by setting the threshold value to a large value as described above, and determining only those exceeding the threshold value as failed wheels.

Further, the present invention is not limited to the above-described embodiment. For example, a so-called circulating type ABS as shown in FIGS. 5 and 6, respectively.
Can also be applied. The ABS shown in Fig. 5
Is a two-system pipe. The brake fluid pressure generated in the first cylinder chamber 5a 'of the master cylinder 5' is applied to the right front wheel brake means 2a 'and the left rear wheel brake means 3a', and to the mastering 5 '. The brake fluid pressure generated in the second cylinder chamber 5b 'is supplied to the left front wheel brake means 1a' and the right rear wheel brake means 4a ', respectively. In that case, the point that the modulator as described in the first embodiment is not provided and the first and
The first to fourth parts respectively derived from the second cylinder chambers 5a 'and 5b'
The supply passages 15 ', 22', and 23 are opened and closed by brake fluid pressure supply solenoid valves 14 ', 19', 20 ', and 21', respectively, at the ends of the passages 7a ', 7b', 8a ', and 8b'. 'And 24' are different from those in the first embodiment. In this system, when the brake fluid pressure for each of the brake means 1a 'to 4a' is reduced, the discharge passages 17 ', 2
Solenoid valve 1 for brake fluid pressure provided on 8 'to 30'
6 ', 25' to 27 'are opened. The other points are the same as those of the first embodiment, and therefore, those having the same reference numerals as those of the first embodiment are denoted by dashes (') and the description thereof is omitted.

FIG. 6 shows a so-called hydraulic booster integrated type circulation system AB to which the third embodiment of the present invention is applied.
FIG. 2 is a system diagram showing S, in which a system piping system is adopted.

In the third embodiment, as shown in the figure, brake means 1a ", 2a" and 3a ", 4a provided on left and right name wheels 1", 2 "and rear wheels 3", 4 ", respectively. And a tandem-type master cylinder 5 "having a first cylinder chamber 5a" and a second cylinder chamber 5b "and generating brake fluid pressure in each of the cylinder chambers 5a" and 5b "by depressing a brake pedal 6".
And a hydraulic pump 13 "that pressurizes hydraulic oil and discharges the hydraulic oil into a hydraulic oil supply passage 35". Hydraulic oil is supplied from the pump 13 "through a hydraulic oil supply passage 35", and a brake pedal 6 " The hydraulic pressure which boosts the brake fluid pressure in each of the cylinder chambers 5a "and 5b" of the master cylinder 5 "and generates the brake fluid pressure to each of the rear wheel brake means 3a" and 4a "at the time of stepping on"" A booster 36 "is provided. The left front wheel brake means 1a" and the right front wheel brake means 2a "are connected to the first cylinder 7" of the master cylinder 5 "via the first passage 7" and the second passage 8 ", respectively. The left and right rear wheel brake means 3a ", 4a" are connected to the hydraulic booster 36 "via the third passage 9", respectively, while being connected to the cylinder chamber 5a "and the second cylinder chamber 5b", respectively. I have.

Further, in this embodiment, a main valve 37 "which is turned on when the ABS is operated is provided. The main valve 37" has a fourth passage 38 "led from the hydraulic booster 36" and one end. And a fifth passage 39 "connected to the first and second cylinder chambers 5a" and 5b "of the master cylinder 5", respectively, and one end of the hydraulic pump 1
A 3 ″ drain passage 40 ″ is connected to the suction side. When the ABS is not operated, the main valve 37 "
Is in the position shown in the figure, and the fifth passage 39 "is in the drain passage 4
However, when the ABS is activated, the solenoid is energized and the valve position is switched from the state shown in FIG.
The fourth passage 38 "communicates with the fifth passage 39".

The first to third passages 7 "to 9" are provided with brake hydraulic pressure supply solenoid valves 41 "to 43" for opening and closing the passages, respectively. 7 "~
9 "from the solenoid valves 41" to 43 "
From each of the passage portions 1a "to 4a", first to third discharge passages 44 "to 46" having one end reaching the suction side of the pump 13 "are provided.
Are respectively branched, and each of the branched discharge passages 44 ″ to 46 ″
The solenoid valve for discharging brake fluid pressure that opens and closes the passage is
7 "to 49" are provided respectively.

Further, also in this embodiment, the same reservoir 33 "and brake fluid level sensor 34" as in the first embodiment are used.
, Each wheel speed sensor 1b "to 4b", and a controller 18 ". The controller 18" receives an output from each of the sensors 34 ", 1b" to 4b "and receives the electromagnetic signals. By appropriately switching the valves 41 "to 43" and 47 "to 49", substantially the same control as that in the first embodiment is performed. The brake system to which the failed wheel belongs can be quickly shut down, for example, if the right front wheel 2 "is determined to be the failed wheel, the controller 18" can be identified.
Outputs an ON signal to the supply solenoid valve 42 "on the second passage 8" so that the valve 42 "is closed and the second discharge passage 45" is closed.
An OFF signal is output to the discharge electromagnetic valve 48 "above, and the valve 48"
Is also closed, and the brake system related to the failure is shut off in this way, so that the influence of the brake system on other brake systems is prevented.

In this embodiment, the hydraulic booster 36 ″
Performs the boosting of the brake fluid pressure to the name wheel brake means 1a "and 2a" and the supply of the brake fluid pressure to each rear wheel brake means 3a "and 4a". When a failure occurs in the brake system, for example, a passage portion (indicated by X in FIG. 6) between the solenoid valve 43 "in the third passage 9" and each of the rear wheel brake means 3a ", 4a". If left unattended, not only the brake fluid pressure will not be supplied to the brake means 3a ", 4a", but also the above-described boosting effect will not be obtained. solenoid valve
43 ", 49" because is closed and passage portion X "according to the failure is interrupted, a situation as described above will be avoided in advance. In this case, steps S ₁ ~ in Figure 2 S ₅
Until performs controller 18 "a similar operation, but after execution of step S ₅ performs step S ₆ 'as shown in FIG. 7. In other words, in this third embodiment in the first embodiment which differ are the 3 line pipe, moreover since the solenoid valve for supply and discharge to its respective line is not provided only one by one, after it is determined that failure corresponding wheel by the operation of the steps S ₅ This means that it is sufficient to shut off the brake system to which the wheel belongs, without having to determine whether the wheel corresponding to the failure is one wheel as in the first embodiment.

(Effects of the Invention) As described above, according to the present invention, the brake fluid level detecting means for detecting the brake fluid level of the reservoir, and the fault corresponding to identifying the failed wheel based on the wheel speed change rate of each wheel. Since the failure of the brake system is detected based on each output of the wheel identification means, a failed wheel can be accurately identified, and a normal state is mistaken as a failed state during slow braking. Can be avoided beforehand.

[Brief description of the drawings]

FIG. 1 is a system diagram showing the overall configuration of a braking control device according to a first embodiment of the present invention, FIG. 2 is a flowchart showing the operation of the controller in FIG. 1, and FIG. And FIG. 4 is a flowchart showing another example of the operation of the controller. 5 to 7 show another embodiment of the present invention. FIG. 5 is a system diagram showing a brake control device according to a second embodiment, and FIG. 6 is a system diagram showing a third embodiment. FIG. 7 is a system diagram showing a braking control device, and FIG. 7 is a flowchart showing a part of the operation of the controller in FIG. 1-4,1'-4 ', 1 "-4" ... wheels, 1a-4a, 1a'-4
a ', 1a "~ 4a" ... brake means, 1b ~ 4b, 1b' ~ 4b ',
1b ″ to 4b ″ ... wheel speed detecting means (wheel speed sensor), 5,
5 ', 5 ", 36" ... brake fluid pressure source (5,5', 5 "...
Master cylinder, 36 ″… hydraulic booster),
18, 18 ″: wheel speed change rate detecting means, wheel identification means for faulty wheel, wheel faulting means (controller), 33, 33 ′, 3
3 ″: reservoir, 34, 34 ′, 34 ″: brake fluid level detecting means (brake fluid level sensor).

Claims (1)

(57) [Claims] A brake means provided on each of the left, right, front and rear wheels; and a brake fluid pressure generating source for generating a brake fluid pressure for each brake means when a brake is operated.
A plurality of brake systems are provided between the brake fluid pressure source and each brake means, and each of the brakes is controlled based on an output from a wheel speed detection means for detecting a wheel speed of each wheel during braking. A brake control device for a vehicle provided with an anti-skid brake system that prevents wheels from skidding by adjusting brake fluid pressure to a means, the brake fluid level detecting a brake fluid level in a reservoir. Detecting means, wheel speed change rate detecting means for respectively detecting the wheel speed change rate of each wheel based on the output of each wheel speed detecting means, and each wheel speed change rate detecting means when the anti-skid brake system is activated. A failed wheel identifying means for identifying a failed wheel based on a wheel speed change rate of each wheel indicated by the output; the brake fluid level detecting means; Receiving each output of the wheel identification means, the output of the brake fluid level detection means indicates that the brake fluid level in the reservoir is equal to or less than a predetermined value, and the output of the failed wheel identification means indicates the failure of the wheel. A vehicle braking control device comprising: a failed wheel identifying means for identifying the wheel corresponding to the failure as a failed wheel when the presence of the vehicle is indicated.