JP4100720B2 - Brake pressure control device for vehicle - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a vehicular brake pressure control device that implements anti-skid control (hereinafter referred to as ABS control), traction control (hereinafter referred to as TRC control), and the like.
[0002]
[Prior art]
For example, in an apparatus that performs brake pressure control such as ABS control or TRC control, the control command is determined according to a brake signal indicating whether or not the driver has operated the brake. Therefore, if the brake signal is not output correctly, the control accuracy may be greatly affected, and various methods for detecting an abnormality in the brake sensor have been proposed (for example, Japanese Patent Laid-Open No. 5-149417). ).
[0003]
[Problems to be solved by the invention]
However, the conventional abnormality detection method discloses a detection method mainly during normal brake operation, such as simply detecting the presence or absence of a brake sensor signal when the vehicle is suddenly decelerated, and performs ABS control and TRC control. No specific detection method is disclosed.
[0004]
The present invention has been made paying attention to the above-mentioned problem, and the object of the present invention is to detect an abnormality of the brake sensor appropriately even when executing the brake pressure control, and to detect the abnormality of the brake sensor. It is an object of the present invention to provide a vehicle brake pressure control device that can perform appropriate brake pressure control even when the above occurs.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is a brake sensor that detects the presence or absence of a brake operation by a driver and outputs a brake signal indicating that,
In Jo Tokoro control conditions are satisfied, so that to solve the wheel lock due to braking operation by the driver, and Brakes pressure control means for controlling the at least either the vacuum state and the pressure increasing state of the brake pressure of the wheel ,
An abnormality detecting means for determining that an abnormality has occurred in the brake sensor unless a brake signal indicating the presence of the brake operation is output until the control condition of the brake pressure control means is satisfied a predetermined number of times;
Anti-skid control means having a plurality of control start criteria having different slip determination levels;
The present invention is characterized by comprising control start reference changing means for changing the control start reference so that the slip determination level is lowered when an abnormality of the brake sensor is determined by the abnormality detecting means.
[0006]
In the invention according to claim 2, in the invention according to claim 1,
When the brake sensor is normal,
When the brake signal is output, the first start reference is selected as the control start reference, and when the brake signal is not output, the slip determination level is lower than the first start reference as the control start reference. Choose a high second starting criterion,
When the brake sensor is abnormal,
The first start reference is selected as the control start reference .
[0007]
In the invention described in 請 Motomeko 3, in the invention according to claim 1-2, when an abnormality of the brake sensor is determined by the abnormality detecting means, and the abnormality information storing means for storing the abnormality information, the Informing means for informing the driver of abnormality information;
In order to notify the abnormality information stored in the abnormality information storage means when a predetermined vehicle driving condition is established, the notification means is controlled.
[0008]
According to a fourth aspect of the present invention, in the third aspect of the present invention, the vehicle operating condition of the notification control means is at least one of the vehicle speed being a predetermined speed or less or the vehicle being in a non-decelerated state. Is included.
[0009]
A fifth aspect of the present invention is the invention according to the fourth aspect , wherein the vehicle operating condition of the notification control means includes a time when the engine is started.
[0010]
According to a sixth aspect of the present invention, in the first to fifth aspects of the present invention, when an acceleration slip occurs, a traction control means for applying a brake fluid pressure to each wheel by a supply pressure of a pump, and a brake by the abnormality detection means. The gist of the invention is that it has control change means for changing brake pressure control by the traction control means when abnormality of the sensor is determined.
[0011]
[Action]
According to the invention described in 請 Motomeko 1, the brake sensor detects the presence or absence of brake operation by the driver, and outputs a brake signal indicating that effect. The brake pressure control means controls the brake pressure of the wheel to at least one of the reduced pressure state and the increased pressure state in order to release the wheel lock accompanying the brake operation by the driver when a predetermined control condition is satisfied. The abnormality detection means determines that an abnormality has occurred in the brake sensor unless a brake signal indicating the presence of a brake operation is output until the control condition of the brake pressure control means is satisfied a predetermined number of times. In other words, if the control condition of the brake pressure control means is satisfied, there is a high possibility that the driver has performed a brake operation, and abnormality of the brake sensor is easily detected from the number of times this condition is satisfied and the presence or absence of a brake signal. . Increasing the number of times the condition is satisfied can prevent erroneous detection.
[0012]
The control start reference changing means changes the control start reference of the anti-skid control means so that the slip determination level becomes low when the abnormality detection means determines that the brake sensor is abnormal . In this case, even if the brake operation is not detected when the brake sensor is abnormal, the anti-skid control is started at a lower slip determination level. Therefore, the control is started at an early timing, and the occurrence of wheel lock is suppressed with a margin.
[0013]
According to the invention of claim 2, when the brake sensor is normal,
When the brake signal is output, the first start reference is selected when the brake sensor is abnormal.
[0014]
According to the invention described in 請 Motomeko 3, abnormality information storage means, when an abnormality of the brake sensor is determined by the abnormality detecting means, and stores the abnormality information. The notification control unit controls the notification unit so as to notify the abnormality information stored in the abnormality information storage unit when a predetermined vehicle driving condition is established. The abnormality information is notified to the driver by the control of the notification means. In this case, even if a sensor abnormality is detected, the abnormality information is not notified to the driver unconditionally (immediately), but is notified after a predetermined vehicle driving condition is established. Confusion to the person is avoided.
[0015]
According to the fourth aspect of the present invention, the vehicle operating condition of the notification control means includes at least one of the vehicle speed being a predetermined speed or less or the vehicle being in a non-decelerated state.
[0016]
According to the fifth aspect of the invention, the vehicle operating condition of the notification control means includes that the engine is started. The driver's confusion due to abnormality information can be avoided also in claims 4 and 5 .
[0017]
According to the sixth aspect of the present invention, the traction control means applies the brake pressure to each wheel by the supply pressure of the pump when the acceleration slip occurs. The control changing means changes the brake pressure control by the traction control means when the abnormality of the brake sensor is determined by the abnormality detecting means. In this case, even if it is not possible to detect the presence of a brake operation when the brake sensor is abnormal, the required master cylinder pressure is transmitted to the wheel cylinder of each wheel quickly, and an appropriate brake operation is ensured.
[0018]
【Example】
(First comparative example)
Hereinafter, a first comparative example in which the present invention is embodied in a brake pressure control device for a front-wheel drive four-wheel vehicle will be described with reference to the drawings.
[0019]
FIG. 1 is a configuration diagram showing an outline of a brake pressure control device in this comparative example. As shown in FIG. 1, a vacuum booster (hereinafter referred to as V / B) 2 for boosting the depression force of the pedal 1 is connected to the brake pedal 1, and the tandem type is connected to the V / B2. A master cylinder (hereinafter referred to as M / C) 3 is connected. A brake actuator 6 is connected to the two hydraulic paths 4 and 5 provided in the M / C 3, and a hydraulic pump 7 is attached to the brake actuator 6. The brake actuator 6 is configured by a known hydraulic circuit having various electromagnetic valves that can switch at least between a pressure increasing state and a pressure reducing state. The brake actuator 6 and the hydraulic pump 7 are driven in response to a control command from an electronic control unit (hereinafter referred to as ECU) 20. The brake oil supplied by the M / C 3 or the hydraulic pump 7 passes through the brake actuator 6 and the hydraulic paths 8 and 9, and the wheel cylinders (hereinafter referred to as W / C) 10FL of the wheels FL, FR, RL, and RR. , 10FR, 10RL, 10RR.
[0020]
Each wheel FL to RR is provided with a wheel speed sensor 11FL, 11FR, 11RL, 11RR that detects the rotational speed of the wheel. As these wheel speed sensors 11FL to 11RR, electromagnetic pickup type or photoelectric conversion type sensors are used. Detection signals from the respective wheel speed sensors 11FL to 11RR are input to the ECU 20, and the ECU 20 performs ABS control (anti-skid control) for suppressing wheel lock generated during vehicle braking based on the rotational speed information of each wheel, and vehicle acceleration. TRC control (traction control) that suppresses the acceleration slip of the wheel that sometimes occurs is executed. In this ABS control, as shown in FIG. 2, the brake pressure is distributed so that the brake pressure on the front wheel side is larger than the brake pressure on the rear wheel side, so that the stability of the vehicle is ensured.
[0021]
In addition to the detection signals from the wheel speed sensors 11FL to 11RR, the ECU 20 detects a brake sensor 13 that detects whether or not the brake pedal 1 is operated, and an accelerator sensor 14 that detects an operation amount of an accelerator pedal (not shown). Operates in response to detection signals from the A warning lamp 15 for notifying the driver of abnormality information of the brake sensor 13 is provided on an instrument panel (not shown) in the vehicle compartment.
[0022]
The ECU 20 includes a microcomputer mainly composed of a CPU, a ROM, a RAM, and the like, and includes a communication device that transmits and receives detection data and control data of various sensors. In this comparative example, the ECU 20 constitutes brake pressure control means, wheel speed difference detection means, abnormality detection means, abnormality information storage means, and notification control means, and the warning lamp 15 constitutes notification means.
[0023]
Next, operations and effects peculiar to this comparative example will be described with reference to FIGS. Here, FIG. 3 is a flowchart showing a sensor abnormality detection routine executed by the ECU 20 at a predetermined cycle (for example, every 5 ms), and FIG. 6 shows an abnormality executed by the ECU 20 at a predetermined cycle (for example, every 20 ms). Warning routine. The flow shown in FIG. 3 is for detecting an OFF abnormality due to a break or the like of the brake sensor 13. In this flow, F1 = 1, F2 = 1 indicates a sensor abnormality, and F1 = 0, F2 = 0 indicates that the sensor is normal. The abnormality determination flags F1 and F2 are used. The states of the abnormality determination flags F1 and F2 are stored and held in the memory in the ECU 20 as abnormality information regardless of whether the ignition key is on or off.
[0024]
When the routine of FIG. 3 is started, the ECU 20 first determines in step 100 whether or not any of the abnormality determination flags F1 and F2 is “1”. If this determination is affirmative, this process is immediately terminated. To do. If step 100 is negatively determined, the ECU 20 proceeds to step 101.
[0025]
In step 101, the ECU 20 determines whether or not the difference between the average wheel speed VRave of the left and right rear wheels RL and RR and the average wheel speed VFave of the left and right front wheels FL and FR is larger than a predetermined determination value ε. It is determined whether or not the operation has continued for a predetermined time. Here, if the determination in step 101 is affirmative, the brake pressure on the front wheel side increases due to the execution of the ABS control, and the average wheel speed VFave on the front wheel side with respect to the average wheel speed VRave on the rear wheel side as shown in FIG. Indicates that it has decreased by more than the judgment value ε. In FIG. 4, step 101 is positively determined at time t1.
[0026]
If an affirmative determination is made in step 101, the ECU 20 proceeds to step 102 and determines whether or not a sensor abnormality detection condition is satisfied. Here, the sensor abnormality detection condition includes that the engine is not in the reduced-cylinder operation state and that the parking brake (not shown) is not operated. That is, in the front-wheel drive vehicle, when engine braking is performed by fuel cut during reduced-cylinder operation, the wheel speed of the front wheels (drive wheels) may be reduced regardless of the brake operation by the driver. In addition, if the parking brake is activated while the vehicle is running, the braking force of the parking brake acts on the front wheel side, leading to a decrease in front wheel speed. In such a case, the speed difference between the front and rear wheels is generated regardless of whether the brake sensor 13 is on or off, so that the sensor abnormality is not detected.
[0027]
If step 102 is positively determined, the ECU 20 proceeds to step 103 and determines whether or not the brake sensor 13 is turned on. In this case, if step 103 is affirmed, the ECU 20 resets the abnormality determination flag F <b> 1 to “0” in step 104, and proceeds to subsequent step 106. That is, the ECU 20 determines that the brake sensor 13 is normal. On the other hand, if a negative determination is made in step 103, the ECU 20 regards the brake sensor 13 as being abnormal OFF, and proceeds to step 105. In step 105, the ECU 20 sets the abnormality determination flag F1 to “1”, and ends this process.
[0028]
Thereafter, the ECU 20 determines in step 106 whether or not the wheel slip ratio S is greater than a predetermined ABS start reference value SS and determines whether or not the state has continued for a predetermined time or more. Here, if the determination at step 106 is affirmative, the operation of depressing the brake pedal 1 causes the rotational speed of one of the wheels to decrease with respect to the vehicle body speed as shown in FIG. It indicates that the control start reference value SS has been reached. In FIG. 5, step 106 is positively determined at time t2.
[0029]
If the determination in step 106 is affirmative, the ECU 20 determines in step 107 whether the brake sensor 13 is turned on. In this case, if an affirmative determination is made in step 107, the ECU 20 proceeds to step 108, resets the abnormality determination flag F1 to “0”, and ends the present process. If the determination at step 107 is negative, the ECU 20 proceeds to step 109, sets "1" to the abnormality determination flag F2, and ends this process.
[0030]
On the other hand, in the routine of FIG. 6, the ECU 20 determines in step 200 whether one of the abnormality determination flags F1 and F2 is “1”. In step 201, the ECU 20 detects whether or not the estimated vehicle speed VT0 is less than 30 km / h. In the subsequent step 202, the ECU 20 determines whether or not the vehicle body acceleration GT0 is greater than “0”, that is, the vehicle is in an undecelerated state. It is determined whether or not.
[0031]
If any of Steps 200 to 202 is positively determined, the ECU 20 proceeds to Step 203 and turns on the warning lamp 15 to notify the driver of sensor abnormality information.
[0032]
Thus, in the brake pressure control device of this comparative example, the abnormality of the brake sensor 13 can be easily detected by using the difference between the front and rear wheel speeds generated by the ABS control. In this case, since the abnormality detection of the brake sensor 13 is stopped at the time of the reduced-cylinder operation of the engine or the parking bouquet operation, the erroneous detection of the sensor abnormality can be prevented.
[0033]
Further, in this comparative example, when a predetermined vehicle driving condition (the vehicle is in a low speed range and in a non-decelerated state) is satisfied, the abnormality information is notified to the driver. Therefore, there is little possibility that the driver will be surprised or confused by the notification of the abnormality information, and the abnormality information can be notified to the driver at an appropriate timing.
[0034]
On the other hand, in the brake pressure control device of the first comparative example, the control method of ABS control and TRC control is changed as follows when the sensor is abnormal. That is, in this control apparatus, as shown in FIG. 7, two types of ABS control start criteria having different slip determination levels are set. That is, in FIG. 7, the first start reference K1 is the ABS control start reference when the brake signal is on, and the second start reference K2 (the wheel speed is higher than the start reference K1) having a slip determination level higher than the start reference K1. The K1 side is larger, but the slip determination level is lower on the K1 side) is the ABS control start reference when the brake signal = off.
[0035]
Then, the ECU 20 performs ABS control by selecting one of the start criteria according to the on / off state of the brake signal. When it is determined that the brake sensor 13 is abnormal, the ECU 20 always sets the ABS control start reference as the first start reference K1 regardless of whether the brake signal is on or off. In this case, the ABS control is started at a lower slip determination level even if the presence of the brake operation cannot be detected when the brake sensor 13 is abnormal. Therefore, the control is started at an early timing, and the occurrence of wheel lock is suppressed with a margin. Here, the anti-skid control means and the control start reference change means are configured by the ECU 20.
[0036]
Moreover, in this brake pressure control apparatus, when abnormality of the brake sensor 13 is determined, TRC control is prohibited after that. In this case, even if it is not possible to detect the presence of a brake operation when the brake sensor 13 is abnormal, the required master cylinder pressure is quickly transmitted to W / C 10FL to 10RR of each wheel, and an appropriate brake operation can be ensured. Here, the ECU 20 constitutes a traction control means and a control prohibition means.
[0037]
(First Embodiment)
Next, the brake pressure control apparatus in the first embodiment will be described focusing on the differences from the first comparative example. Note that this example uses the same apparatus as the first comparative example. In the first embodiment, the ECU 20 constitutes a brake pressure control means and an abnormality detection means.
[0038]
In other words, the ECU 20 controls the brake pressure of the wheel to at least one of the reduced pressure state and the increased pressure state when a predetermined ABS control condition (ABS start condition associated with a decrease in wheel speed at the time of brake operation by the driver) is established. And suppress wheel lock. Further, the ECU 20 determines that an abnormality has occurred in the brake sensor 13 unless a brake signal indicating the presence of a brake operation is output until the ABS control condition is satisfied a predetermined number of times.
[0039]
In this case, if the ABS control condition is satisfied, there is a high possibility that the driver has performed a brake operation, and an abnormality of the brake sensor 13 is determined from the number of times this condition is satisfied (for example, 1 to 10 times) and the presence or absence of a brake signal. Can be easily detected. In addition, if the number of times that the condition is satisfied is increased, erroneous detection can be prevented.
[0040]
( Second comparative example)
Next, the brake pressure control device in the second comparative example will be described. Note that this comparative example uses the same apparatus as the first comparative example. In the second comparative example, the ECU 20 constitutes a brake pressure control means, a driven wheel speed detection means, and an abnormality detection means.
[0041]
That is, the ECU 20 detects the driven wheel speed from the detection results of the wheel speed sensors 11RL and 11RR on the driven wheels RL and RR. The ECU 20 determines that an abnormality has occurred in the brake sensor 13 if the brake signal indicating that the brake operation is present is not output when the amount of decrease in the driven wheel speed during the TRC control exceeds a predetermined value. In short, the execution of the TRC control usually corresponds to the occurrence of an acceleration slip, and if the driven wheel speed decreases at this time, there is a high possibility that the driver has performed a braking operation. Therefore, the abnormality of the brake sensor 13 can be easily detected from the amount of decrease in the driven wheel speed.
[0042]
(Third comparative example)
Next, the brake pressure control device in the third comparative example will be described. The present comparative example has had use the same apparatus as in the first comparative example. In the third comparative example, the ECU 20 constitutes a measurement unit and an abnormality detection unit.
[0043]
That is, the ECU 20 measures the vehicle travel distance or the maximum vehicle speed after the ignition key of the vehicle is turned on. When the vehicle travel distance or maximum vehicle speed reaches a predetermined value, the ECU 20 determines that an abnormality has occurred in the brake sensor 13 unless a brake signal indicating the presence of a brake operation has ever been output. . In short, when the vehicle travel distance reaches a predetermined value (for example, 5 km) during actual vehicle travel, or when the maximum speed reaches a predetermined speed (for example, 60 km / h), the brake operation by the driver is performed until then. It is very unlikely that no attempt was made. Therefore, the abnormality of the brake sensor 13 can be easily detected from the above method.
[0044]
It is also possible to addition to embodied in the following aspects of the upper Symbol each example.
[0045]
(1) In the first comparative example, if the vehicle is in a low speed range and is in an acceleration state, the driver is warned of abnormal information that the vehicle driving condition is satisfied (the process of FIG. 6). Also good. For example, the vehicle operating condition may be when the engine is started, and the driver may be warned of abnormal information according to the ON operation of the ignition key at the time of starting the vehicle.
[0046]
(2) In the comparative example, the notification means is constituted by the warning lamp 15, but it may be changed to other means such as a buzzer or a message display device.
[0047]
(3) In the comparative example, it is described that the subsequent TRC control is prohibited when the sensor is abnormal. However, the TRC control pattern may be changed when the sensor is abnormal.
[0048]
That is, when the brake signal is turned on during TRC control and when a sensor abnormality is determined, excessive brake oil inflow from M / C3 to W / C10FL to 10RR of each wheel is prevented during TRC control. The TRC control pattern is changed. That is, during TRC control, a large amount of brake oil is supplied from the hydraulic pump 7 to the drive wheels FL, FR side W / Cs 10FL, 10FR via the brake actuator 6. Therefore, when a brake operation accompanying the brake operation by the driver is performed in the above state, the pedal bottoming (the brake pedal 1 of the brake pedal 1) is performed by discharging the brake oil used at the time of the TRC control and supplying the new brake oil from the M / C 3. Various problems occur.
[0049]
On the other hand, in this configuration, for example, the supply pressure of the hydraulic pump 7 is always equal to or higher than the supply pressure of M / C3 to prevent the inflow of excess brake oil from M / C3 to W / C10FL to 10RR. It has been resolved. Further, in this configuration, since the above control change is performed when a sensor abnormality is detected, the above problems can be avoided even if the presence of a brake operation cannot be detected when the brake sensor 13 is abnormal. Furthermore, the transition from TRC control to normal braking operation (including ABS control) can be appropriately performed.
[0050]
【The invention's effect】
According to the first and second aspects of the invention, it is possible to easily detect abnormality of the brake sensor from the number of times the brake pressure control condition is satisfied and the presence or absence of a brake signal . In addition , appropriate brake pressure control can be performed even when an abnormality occurs in the brake sensor.
[0051]
According to the invention described in 請 Motomeko 3, there is exhibited an excellent effect that it is possible to notify the anomaly information at the right time to the driver.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a vehicle brake control device according to a comparative example.
FIG. 2 is a diagram showing a front-rear distribution of brake pressure.
FIG. 3 is a flowchart showing a sensor abnormality detection routine.
FIG. 4 is a time chart showing changes between front wheel speed and rear wheel speed.
FIG. 5 is a time chart showing changes in vehicle body speed and wheel speed.
FIG. 6 is a flowchart showing an abnormality warning routine.
FIG. 7 is a time chart showing ABS control start criteria.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 3 ... Master cylinder (M / C), 7 ... Hydraulic pump, 10FL-10RR ... Wheel cylinder (W / C), 13 ... Brake sensor, 15 ... Warning lamp as alerting means, 20 ... Brake pressure control means, Wheel speed Electronic control device as difference detection means, abnormality detection means, driven wheel speed detection means, measurement means, anti-skid control means, control start reference change means, traction control means, control prohibition means, abnormality information storage means, notification control means ( ECU).

Claims (6)

A brake sensor that detects the presence or absence of a brake operation by the driver and outputs a brake signal indicating that,
Brake pressure control means for controlling the brake pressure of the wheel to at least one of a reduced pressure state and a boosted state in order to release the wheel lock caused by the brake operation by the driver when a predetermined control condition is established;
An abnormality detecting means for determining that an abnormality has occurred in the brake sensor unless a brake signal indicating the presence of the brake operation is output until the control condition of the brake pressure control means is satisfied a predetermined number of times;
Anti-skid control means having a plurality of control start criteria having different slip determination levels;
A vehicle brake comprising: a control start reference changing means for changing the control start reference so that the slip determination level is lowered when an abnormality of the brake sensor is determined by the abnormality detection means. Pressure control device. When the brake sensor is normal,
When the brake signal is output, the first start reference is selected as the control start reference, and when the brake signal is not output, the slip determination level is lower than the first start reference as the control start reference. Choose a high second starting criterion,
  When the brake sensor is abnormal,
  The vehicle brake pressure control apparatus according to claim 1, wherein a first start reference is selected as the control start reference. An abnormality information storage means for storing the abnormality information when the abnormality of the brake sensor is determined by the abnormality detection means;
Informing means for informing the driver of the abnormality information;
To the abnormality information storing means stored abnormality information a predetermined vehicle operating conditions are notified when satisfied, according to any one of claims 1 to 2 and a notification control means for controlling said notification means Brake pressure control device for vehicles. The vehicle brake pressure control device according to claim 3 , wherein the predetermined vehicle driving condition of the notification control means includes at least one of a vehicle speed being a predetermined speed or less or a vehicle being in a non-decelerated state. The vehicle brake pressure control device according to claim 4 , wherein the predetermined vehicle operating condition of the notification control means includes a time when the engine is started. Traction control means for applying brake fluid pressure to each wheel by pump supply pressure at the time of acceleration slip occurrence;
The abnormality if the abnormality in the brake sensor is determined by the detection means, vehicle brake pressure control apparatus according to any one of claims 1 to 5, and a control changing means for changing the brake pressure control by the traction control means.

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