JP3547088B2 - Anti-lock control device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an antilock control device for a vehicle, and more particularly to a technique for appropriately determining a brake pressure control characteristic in antilock control in relation to a road surface friction coefficient.
[0002]
[Prior art]
Generally, the anti-lock control device is configured to control a brake pressure of a wheel so that the wheel does not fall into a locked state during vehicle braking. One example is described in Japanese Patent Application Laid-Open No. 3-67757 of the present applicant.
[0003]
In the antilock control, there is a demand for appropriately determining the control characteristic of the brake pressure in relation to the friction coefficient of the road surface. For example, on a high μ road, while there is a demand to increase the brake pressure increasing tendency, and on a low μ road, to increase the brake pressure decreasing tendency, it is desired to change the control characteristics to follow a change in the road surface friction coefficient. There is.
[0004]
In order to satisfy this demand, the present applicant has developed the following antilock control device. This is due to the fact that the vehicleToFocusing on the fact that the acceleration / deceleration at the center of gravity of the vehicle reflects the level of the friction coefficient of the road surface, the antilock which acquires the acceleration / deceleration in the longitudinal direction of the vehicle and determines the control characteristics of the brake pressure in the antilock control based on it It is a control device.
[0005]
[Problems to be solved by the invention]
In a vehicle running state in which the direction of travel of the vehicle and the direction of the vehicle body substantially match each other, the longitudinal acceleration / deceleration of the vehicle substantially matches the actual acceleration / deceleration at the vehicle center of gravity, that is, the actual acceleration / deceleration. Even if the characteristics of the lock control are determined, the effect of the anti-lock control can be enjoyed as expected. However, in a vehicle running state in which the traveling direction of the vehicle and the direction of the vehicle body do not sufficiently match, such as a state in which the vehicle body is spinning, the absolute value of the longitudinal acceleration / deceleration of the vehicle is smaller than the absolute value of the actual acceleration / deceleration. If the characteristics of the antilock control are determined based only on the acceleration / deceleration, the characteristics may be on the pressure reducing side in relation to the friction coefficient of the road surface, and the effect of the antilock control may not be enjoyed as expected. There's a problem.
[0006]
The present invention has been made to solve this problem.
[0007]
[Means for Solving the Problems]
In order to solve this problem, the invention according to claim 1 of the present application,carAt the time of both braking, in the anti-lock control device that controls the brake pressure, which is the hydraulic pressure of the brake cylinder that operates the brake that suppresses the rotation of the wheels, so that the wheels do not fall into the locked state,(1) a plurality of wheel speed sensors that detect wheel speeds that are rotation speeds of a plurality of wheels of the vehicle; and (2) an estimated vehicle speed of the vehicle based on the plurality of wheel speeds detected by the wheel speed sensors. (3) means for obtaining an estimated longitudinal acceleration which is a differential value of the obtained estimated vehicle speed with respect to time, and (4)Two acceleration sensors for detecting acceleration components in two directions, each of which is inclined approximately 45 degrees with respect to the vehicle longitudinal direction when the vehicle is viewed from directly above,(5)When the absolute value of the combined acceleration of the two directions detected by the acceleration sensors is large, the brake pressure increase gradient in the antilock control is made steeper than when the absolute value is small, and the brake pressure is reduced. Control characteristic determining means for performing at least one of gradual gradients is provided.
According to a second aspect of the present invention, there is provided the antilock control device according to the first aspect, wherein (a) the brake pressure is increased in an open state, held in a closed state, and increased by controlling a time ratio between the open state and the closed state. A pressure-intensifying solenoid valve capable of controlling a pressure gradient, and (b) the brake pressure is reduced in an open state and held in a closed state, and a pressure reduction gradient can be controlled by controlling a time ratio between an open state and a closed state. A pressure reducing solenoid valve, and controlling the control characteristic determining means with respect to (i) the time of closing the pressure increasing solenoid valve to the time of opening it so as to steepen the pressure increasing gradient of the brake pressure. Means including at least one of a means for decreasing the ratio and (ii) a means for increasing the ratio of the time for closing the pressure reducing solenoid valve to the time for opening the solenoid to reduce the pressure reduction gradient of the brake pressure. It is characterized by having.
The invention according to claim 3 is the antilock control device according to claim 1 or 2.ToMeans for obtaining a combined acceleration of the detected acceleration of the remaining one acceleration sensor and the estimated longitudinal acceleration when one of the two acceleration sensors fails.ToAnd the control characteristic determining means uses a combined acceleration of the detected acceleration of the one acceleration sensor and the estimated longitudinal acceleration instead of a combined acceleration of the two detected accelerations of the two acceleration sensors. It is characterized by the following.
[0008]
[0009]
[0010]
[Action]
In the antilock control device according to the invention of claim 1 of the present application,Wheel speeds of a plurality of wheels of the vehicle are detected by the wheel speed sensors, and an estimated vehicle speed and an estimated longitudinal acceleration of the vehicle are acquired based on the detection results. Also,Control characteristic determinantStep by stepThus, the control characteristics of the brake pressure in the antilock control are determined based on the combined acceleration of the acceleration components in two directions, each of which is inclined approximately 45 degrees with respect to the vehicle longitudinal direction. When the absolute value of the resultant acceleration is large, at least one of steepening the pressure increasing gradient of the brake pressure and gradual decreasing the pressure decreasing gradient of the brake pressure in the antilock control is performed as compared with the case where the absolute value of the resultant acceleration is small. It is done.
In the antilock control device according to the second aspect of the present invention, the pressure increase gradient of the brake pressure is made steep by reducing the ratio of the time for closing the pressure increasing solenoid valve to the time for opening the pressure increasing solenoid valve, or By increasing the ratio of the time for closing the pressure reducing solenoid valve to the time for opening it, the pressure reduction gradient of the brake pressure is moderated.
In the antilock control device according to the third aspect of the present invention, when one of the two acceleration sensors fails, the combined acceleration of the detected acceleration of the remaining one acceleration sensor and the estimated longitudinal acceleration is two of the two acceleration sensors. It is used instead of the composite acceleration of the two detected accelerations.
[0011]
【The invention's effect】
As described above, according to the first aspect of the present invention, the absolute value of the true acceleration of the vehicle is accurately detected as the combined acceleration of the acceleration components in the two directions inclined at approximately 45 degrees with respect to the vehicle longitudinal direction. The control characteristics of the brake pressure in the antilock control are determined based on the detection result. When the resultant acceleration is large, it is assumed that the road surface friction coefficient is larger than when the resultant acceleration is small, and at least one of steepening the pressure increasing gradient of the brake pressure in antilock control and gradually decreasing the pressure decreasing gradient of the brake pressure. Is performed, whereby the effect that the brake pressure of the wheels can be controlled with the control characteristics well suited to the characteristics of the road surface is obtained.Further, since the estimated longitudinal acceleration is obtained based on the wheel speed detected by the wheel speed sensor, even if one of the two acceleration sensors fails, accelerations in two different directions are still obtained. Thereby, for example, as described in claim 3, the combined acceleration of the detected acceleration of the normal one acceleration sensor and the estimated longitudinal acceleration is replaced with the combined acceleration of the two detected accelerations of the two acceleration sensors. Can be used.
According to the second aspect of the present invention, it is possible to control the pressure increasing gradient and the pressure decreasing gradient during the antilock control by controlling the relatively inexpensive pressure increasing solenoid valve and the pressure decreasing solenoid valve.
According to the third aspect of the present invention, even if one of the two acceleration sensors fails, the brake pressure on the wheels can be controlled with no trouble and the control characteristics well suited to the characteristics of the road surface.
[0012]
【Example】
Hereinafter, an antilock brake system including an antilock control device according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0013]
FIG.Reference numeral 10 denotes a brake pedal, which is linked to a master cylinder 14 via a booster 12. The master cylinder 14 is of a tandem type in which two pressurizing chambers are arranged in series with each other, and generates a brake pressure of the same height in the pressurizing chambers.
[0014]
This brake system is an X-pipe type in which two independent brake systems are arranged in an X shape. In the first brake system, one pressurizing chamber of the master cylinder 14 is connected to a wheel cylinder 26 of the brake of the left rear wheel RL via a liquid passage 20, a normally open solenoid valve 22, and a liquid passage 24. The fluid passages 20 and 30 are connected to a wheel cylinder 36 of the brake of the right front wheel FR via a normally open solenoid valve 32 and a fluid passage 34. On the other hand, in the second brake system, the other pressurizing chamber is connected to a brake wheel cylinder 46 of the left front wheel FL via a liquid passage 40, a normally open solenoid valve 42 and a liquid passage 44, and the liquid passage 40 , 48, via a normally open solenoid valve 50 and a fluid passage 52 to be connected to a brake wheel cylinder 54 for the right rear wheel RR.
[0015]
In the first brake system, the liquid passage 24 is connected to a reservoir 64 via a normally closed solenoid valve 60, and the liquid passage 34 is also connected to a reservoir 64 via a normally closed solenoid valve 62. The reservoir 64 is connected to a suction port of a pump 66, and a discharge port thereof is connected to the liquid passage 20. On the other hand, in the second brake system, the liquid passage 44 is connected to a reservoir 72 via a normally closed solenoid valve 68, and the liquid passage 52 is also connected to a reservoir 72 via a normally closed solenoid valve 70. The reservoir 72 is connected to a suction port of a pump 74, and a discharge port thereof is connected to the liquid passage 40. The two pumps 66 and 74 are driven by a common motor 76.
[0016]
Therefore, for example, with respect to the brake pressure of the left rear wheel RL, a pressure increasing state is realized by setting both the solenoid valves 22 and 60 to a non-energized state, and a holding state is achieved by setting only the electromagnetic valve 22 to an energized state. The decompression state is realized by setting both the solenoid valves 22 and 60 to the energized state. The same applies to the brake pressures of the other wheels. That is, the brake pressure of each wheel is selectively realized in a pressure-increasing state, a holding state, and a pressure-reducing state by a combination of two solenoid valves. The signals supplied to the solenoid of the solenoid valve to realize the holding state and the pressure reducing state are referred to as a pressure increasing signal, a holding signal and a pressure reducing signal, respectively.
[0017]
The electromagnetic valves 22 and the like are controlled by an electronic control unit 80. This electronic control unit 80FIG.As shown in FIG. 1, the computer 82 is mainly configured and includes a CPU 84, a ROM 86, a RAM 88, a timer 90, an input interface circuit 92, and an output interface circuit 94. The motor 76 and the solenoid valve 22 are connected to the output interface circuit 94 via each driver 96. On the other hand, four wheel speed sensors 100, 102, 104, 106 and a stop lamp switch 110 (FIG.Are connected. Each of the wheel speed sensors 100 to 106 detects the rotation of a rotor that rotates together with each wheel. The stop lamp switch 110 detects the depression of the brake pedal 10 by the driver.
[0018]
Further, two acceleration sensors 120 and 122 are connected to the input interface circuit 92 via the respective signal processing circuits 112. Both of the acceleration sensors 120 and 122 are mounted at a certain position on a vertical axis passing through the center of gravity of the vehicle.FIG., The acceleration sensor 120 has a component acceleration GL in a direction extending at an angle of 45 degrees diagonally forward left from the center of gravity of the vehicle when the vehicle is viewed from directly above.₁ On the other hand, when the vehicle is viewed from directly above, the acceleration sensor 122 detects the component acceleration GL in a direction extending from the center of gravity of the vehicle at an angle of 45 degrees diagonally left backward._Two It is mounted in a state that detects In addition, the acceleration sensor 120 is designed to detect the acceleration generated during forward acceleration and left turning of the vehicle as positive, and to detect the acceleration generated during forward deceleration and right turning as negative, while the acceleration sensor 122 is The acceleration generated during forward deceleration and left turning is detected as positive, and the acceleration generated during forward acceleration and right turning is detected as negative.
[0019]
In the present embodiment, as described above, “acceleration” is broadly defined as a physical quantity that can take not only a positive value but also a negative value, but is defined in a narrow sense as a physical quantity that can take only a positive value. It is also possible. In this case, the “narrow sense of acceleration” generated on the vehicle body during vehicle acceleration is generally referred to as “acceleration”, and the “narrow sense of acceleration” generated on the vehicle body during vehicle deceleration is generally referred to as “deceleration”. .
[0020]
In ROM86FIG.As shown in (1), various programs required for the antilock control are stored in advance. Hereinafter, a typical program will be described.
[0021]
(1)  Wheel speed calculation routine
This routine is based on the output signals from the wheel speed sensors 100 to 106 of each wheel, and calculates the wheel speed V of each wheel._WAre sequentially calculated. The calculation result is stored in the RAM 88 in association with each wheel.
[0022]
(2)  Wheel acceleration calculation routine
In this routine, each wheel speed V calculated by the wheel speed calculation routine is used._WIs differentiated with respect to time, that is, specifically, the wheel speed V_WBy dividing the value obtained by subtracting the previous sampling value from the current sampling value by the sampling period, the acceleration V_W′ Are sequentially calculated. This calculation result is also stored in the RAM 88 in association with each wheel.
[0023]
(3)  Estimated vehicle speed calculation routine
This routine is based on the wheel speed V of the four wheels._WWheel speed V of the fastest wheel where_WRepresents the vehicle speed and the estimated vehicle speed V_SOIs calculated, and the wheel acceleration V of the fastest wheel is calculated._W'Exceeds the predetermined upper limit, the vehicle speed is estimated by fixing the upper limit and the estimated vehicle speed V_SOIs calculated. The calculation result is stored in the RAM 88.
[0024]
(Four)  Component acceleration calculation routine
This routine is executed sequentially and sequentially for each of the acceleration sensors 120 and 122, and based on an output signal from each of the acceleration sensors 120 and 122, each component acceleration GL is performed.₁ , GL_Two Are sequentially sampled, and further, Butterworth-type filtering is performed on them, so that the component acceleration GL of each time is obtained.₁ , GL_Two Is calculated. This calculation result is also stored in the RAM 88.
[0025]
(Five)  Synthetic acceleration calculation routine
This routine is based on the component acceleration GL calculated each time by the component acceleration calculation routine.₁ , GL_Two , The longitudinal acceleration G of the vehicle_XAnd lateral acceleration G_YIs calculated, and their composite value is calculated as a composite acceleration G_XYIs calculated. In particular,
G_X= (GL₁ -GL_Two ) / 2^1/2
Longitudinal acceleration G using the formula_X, And
G_Y= (GL₁ + GL_Two ) / 2^1/2
Using the formula_Y, And
G_XY= (GL₁ ^Two+ GL_Two ^Two)^1/2
Acceleration G using the formula_XYIs calculated.
[0026]
(6)  Antilock control routine
This routine isFIG., The outline of which is described first.
[0027]
This routine sequentially determines whether or not it is necessary to execute the antilock control for each wheel, and when it is determined that the antilock control needs to be performed, brakes each wheel so that each wheel does not fall into a locked state. This is a routine for performing antilock control for increasing and decreasing the pressure. This routine is repeatedly executed for each wheel sequentially and for a fixed short time (for example, 10 ms) while the stop lamp switch 110 detects the depression of the brake pedal 10 by the driver.
[0028]
The antilock control according to this routine controls the wheel speed V of the wheel to control the wheel brake pressure so that the tendency of the lock generated on the wheel to disappear as quickly as possible and to generate the largest possible braking force on the wheel._WAnd wheel acceleration V_W′, A control mode suitable for the state of the wheel at each time is selected from four control modes including a rapid pressure reduction mode, a pulse pressure reduction mode, a holding mode, and a pulse pressure increase mode, and the control mode is realized. Thus, the flow state of the solenoid valve is controlled.
[0029]
The selection of the control mode is performed according to the following rules. That is,FIG.As shown in the table, the wheel speed V_WIs the reference vehicle speed V_SN, V_SH(However, V_SN> V_SH) Is divided into three regions, and the wheel acceleration V_W'Is the reference acceleration G₁ , G_Two (However, G₁ Takes a negative value and G_Two Is a positive value), and is divided into three regions._WAnd wheel acceleration V_WIs divided into nine areas, and the control mode is selected in accordance with a preset relation between each of these areas and the control mode.
[0030]
However, the wheel speed V_WIs the reference vehicle speed V_SHSmaller and wheel acceleration V_W'Is the reference acceleration G_Two In the case described above, the holding mode should normally be selected for both the front wheels and the rear wheels._XYIs smaller than 0.2 G, the holding mode is selected only for the front wheels, and the pulse pressure reduction mode is selected for the rear wheels.
[0031]
The control mode selection rules described above are in principle and there are exceptions. The exception is when the pulse boost mode is run continuously for a somewhat longer time, in which case the dither boost mode is designed to be run thereafter.
[0032]
Here, each mode will be described. First, the "rapid pressure reduction mode" is a mode in which the wheel cylinder pressure is rapidly reduced by continuously supplying a pressure reduction signal to the solenoid valve and maintaining the solenoid valve in a reduced pressure state. The “pulse pressure reduction mode”FIG.In this mode, the wheel cylinder pressure is gradually reduced by alternately supplying a holding signal and a pressure reducing signal to the solenoid valve to alternately switch the solenoid valve between the holding state and the pressure reducing state. The “holding mode” is a mode in which a wheel cylinder pressure is held by continuously supplying a holding signal to the solenoid valve and keeping the solenoid valve in a holding state. In the "pulse pressure increasing mode", the wheel cylinder pressure is gradually increased by alternately supplying the holding signal and the pressure increasing signal to the solenoid valve and alternately switching the solenoid valve between the holding state and the pressure increasing state. Mode. Also, the "dither pressure increase mode"FIG.As shown in the pulse pressure increase mode, the hold signal and the pressure increase signal are alternately supplied to the solenoid valve as in the case of the pulse pressure increase mode, but the pressure increase gradient of the wheel cylinder pressure is greater than in the pulse pressure increase mode. In this mode, the duration of each signal is set so as to be steep.
[0033]
Holding time T, which is the duration of one holding signal in the pulse pressure reduction mode_D1(FIG.), And the decompression time T, which is the duration of one decompression signal._D2(See FIG. 3) are obtained as follows. That is, the holding time T_D1About the resultant acceleration G_XYThe calculated acceleration value is variable according to the_XYIs calculated to be longer as the value of is larger, that is, as the friction coefficient μ of the road surface is higher. The calculation is performed such that the higher the road surface friction coefficient μ, the gentler the pressure reduction gradient of the wheel cylinder pressure in the pulse pressure reduction mode. On the other hand, the decompression time T_D2Is assumed to be an invariant value.
[0034]
Holding time T, which is the duration of one holding signal in the dither boost mode_U1(FIG.), And the period T of one pressure-intensifying pulse defined by one continuous holding signal and one pressure-intensifying signal._U2(See FIG. 3) are obtained as follows. That is, the holding time T_U1Also period T_U2Also the synthetic acceleration G_XYIs a variable calculation value in accordance with_XYIs larger, that is, the friction coefficient μ of the road surface is higher, the holding time T_U1Is short and the period T_U2Is calculated to be longer. The calculation is performed such that the higher the road surface friction coefficient μ, the steeper the pressure increase gradient of the wheel cylinder pressure in the dither pressure increase mode.
[0035]
Next, this antilock control routineFIG.This will be described in detail based on FIG.
[0036]
In each execution of this routine, first, in step S1 (hereinafter simply referred to as S1; the same applies to other steps), the latest estimated vehicle speed V_SOIs read from the RAM 88, and then at S2, the estimated vehicle speed V_SOBased on the reference vehicle speed V related to the anti-lock control_SN, V_SHIs calculated. After that, in S3, the wheel speed V of the wheel to be executed this time (hereinafter, simply referred to as an execution target wheel) in this routine._WAnd wheel acceleration V_W'Is read from the RAM 88.
[0037]
Subsequently, in S4, the latest synthetic acceleration G_XYIs read from the RAM 88, and then at S5, the resultant acceleration G_XYAnd the holding time T as described above._D1, Decompression time T_U1And period T_U2Are respectively calculated.
[0038]
Subsequently, in S6, it is determined whether or not it is necessary to execute the antilock control. For example, the start condition of the antilock control is the wheel speed V_WIs the reference vehicle speed V_SNSmaller and wheel acceleration V_W'Is the reference acceleration G₁ It will be smaller.
[0039]
If it is assumed that the execution target wheel does not have a lock tendency this time, the determination is NO, and in S7, the brake system is brought into the normal state. The state is such that hydraulic pressure of a height corresponding to the depression of the brake pedal 10 is generated in each of the wheel cylinders 26, 36, 46, 54. Thus, one execution of this routine ends.
[0040]
Thereafter, while the execution of this routine is repeated many times, the execution target wheels tend to lock, and therefore, assuming that the start condition of the antilock control is satisfied, the determination in S6 becomes YES, and the determination in S8 is made. In, a control mode suitable to be executed for the execution target wheel is selected, and the selected control mode is executed in the following steps.
[0041]
For example, assuming that the rapid pressure reduction mode is selected in S8, if it is determined in S9 whether the current control mode is the pulse pressure increase mode, the determination is NO, and in S10, the current control mode is determined. Is determined to be in the pulse decompression mode, this determination is also NO, and the rapid decompression mode is executed in S11. Thus, one execution of this routine ends.
[0042]
Thereafter, it is assumed that the progress of the locking tendency of the execution target wheel is suppressed while the execution of S1 to S6, S8 to S10, and S11 is repeated, and as a result, the pulse pressure reduction mode is selected as the current control mode in S8. For example, the determination in S9 is NO, the determination in S10 is YES, and the pulse pressure reduction mode is executed in S12. Calculated holding time T_D1And decompression time T_D2The switching state of the solenoid valve is controlled according to the following equation. Thus, one execution of this routine ends.
[0043]
Thereafter, while the execution of S1 to S6, S8 to 10 and S12 is repeated, the locking tendency of the execution target wheel is substantially eliminated, and if it is assumed in S8 that the pulse pressure increasing mode has been selected as the current control mode, the process proceeds to S9. Is YES, and the pulse pressure increasing mode is executed in S13. Subsequently, in S14, it is determined whether or not the time of the pulse pressure increasing mode executed continuously up to this time is long, that is, for example, the number of pressure increasing pulses continuously supplied to the solenoid valve is equal to or more than a certain number. Is determined. Since this time is the beginning of the pulse pressure increasing mode, the determination is NO, and one cycle of this routine is completed.
[0044]
Thereafter, assuming that the execution target wheels again have a tendency to lock while the execution of S1 to 6, 8, 9, 13, and 14 is repeated, in S8, the rapid control mode or the pulse control mode is set as the current control mode. Is selected, and in the following steps, the selected control mode is executed. On the other hand, if the execution target wheels do not have the tendency to lock again while the execution of S1 to S6, 8, 9, 9, 13 and 14 is repeated, and the determination in S14 becomes YES, the dither increase is performed in S15. The pressure mode is executed. Calculated holding time T_U1And period T_U2The switching state of the solenoid valve is controlled according to the following equation. Thus, one execution of this routine ends.
[0045]
Therefore, in this embodiment, the longitudinal acceleration G_XNot the combined acceleration G_XYIs used to determine the wheel cylinder pressure control characteristics in the antilock control, so that the friction coefficient μ of the road surface is accurately estimated, and as a result, the antilock control is performed by the friction coefficient of the road surface. The effect that the program is executed properly in relation to μ is obtained.
[0046]
Further, in this embodiment, when the friction coefficient μ of the road surface is low, the tendency of the wheel cylinder pressure to decrease is increased, and when the friction coefficient μ is high, the characteristic of the antilock control is determined so that the tendency to increase the pressure is increased. Therefore, as in the case where the characteristics are uniformly determined irrespective of the level of the friction coefficient μ of the road surface, there is an effect that the pressure is insufficiently reduced on the low μ road, and the pressure is not excessively reduced on the high μ road.
[0047]
In this embodiment, the combined acceleration G_XYAre obtained in order to obtain the vehicle acceleration, and both of them are arranged in a state where the lateral component of the vehicle acceleration can be detected. Therefore, even if one of the acceleration sensors fails, the acceleration (GL) detected by the normal acceleration sensor remains as long as the other acceleration sensor is normal.₁ And GL_Two And the estimated vehicle speed V_SOLongitudinal acceleration obtained by differentiating the longitudinal acceleration with respect to time (the longitudinal acceleration G_X) And the above,
G_X= (GL₁ -GL_Two ) / 2^1/2
By using the relationship expressed by the following formula, the acceleration (GL) that should be detected by the failed acceleration sensor₁ And GL_Two The other) can be estimated, and from the estimated value and the acceleration detected by the normal acceleration sensor, the combined acceleration G_XYCan also be obtained.
[0048]
In the present embodiment, the acceleration sensors 120 and 122 are arranged on the vertical axis passing through the center of gravity of the vehicle, but may be arranged at any position on any horizontal plane of the vehicle.
[0049]
As is clear from the above description, in the present embodiment, the component acceleration calculation routine, the composite acceleration calculation routine,FIG.Of the present invention cooperates with the two acceleration sensors 120 and 122 in the “control characteristic determination step” of the present invention.Dan "This constitutes one embodiment.
[0050]
While the embodiment of the present invention has been described in detail with reference to the drawings, other various modifications and improvements may be made based on the knowledge of those skilled in the art without departing from the scope of the claims. The invention can be implemented.
[Brief description of the drawings]
FIG.  1 is a system diagram showing an anti-lock type brake system including an anti-lock control device according to one embodiment of the present invention.
FIG. 2  FIG.FIG. 2 is a diagram conceptually showing a configuration of an electronic control device in FIG.
FIG. 3  FIG.Acceleration GL by two acceleration sensors at₁ , GL_Two And the acceleration GL₁ , GL_Two Acceleration G_XYFIG. 4 is a diagram for explaining the principle of obtaining the.
FIG. 4  FIG.FIG. 2 is a diagram conceptually showing a configuration of a ROM in FIG.
FIG. 5  FIG.4 is a flowchart showing an antilock control routine in the first embodiment.
FIG. 6  FIG.6 is a table showing a control mode selection rule in the anti-lock control routine of FIG.
FIG. 7  FIG.5 is a time chart for explaining a signal configuration for realizing a pulse pressure reduction mode in the antilock control routine of FIG.
FIG. 8  FIG.4 is a time chart for explaining a signal configuration for realizing a dither pressure increasing mode in the antilock control routine of FIG.
[Explanation of symbols]
22, 32, 42, 50, 60, 62, 68, 70 Solenoid valve
26, 36, 46, 54 Wheel cylinder
80 Electronic control unit
100, 102, 104, 106 Wheel speed sensor
120,122 acceleration sensor

Claims (3)

An anti-lock control device that controls a brake pressure, which is a hydraulic pressure of a brake cylinder that activates a brake that suppresses rotation of a wheel during vehicle braking, so that the wheel does not fall into a locked state,
A plurality of wheel speed sensors that detect a wheel speed that is a rotation speed of each of the plurality of wheels of the vehicle,
Means for obtaining an estimated vehicle speed of the vehicle based on a plurality of wheel speeds detected by the wheel speed sensors,
Means for obtaining an estimated longitudinal acceleration that is a differential value of the obtained estimated vehicle speed with respect to time,
Two acceleration sensors for detecting acceleration components in two directions, each of which is inclined approximately 45 degrees with respect to the vehicle longitudinal direction when the vehicle is viewed from directly above,
When the absolute value of the combined acceleration of the two directions detected by the acceleration sensors is large, the brake pressure increase gradient in the antilock control is made steeper than when the absolute value is small, and the brake pressure is reduced. An anti-lock control device, comprising: control characteristic determining means for performing at least one of a gentler gradient. A pressure-intensifying solenoid valve capable of increasing the brake pressure in the open state, holding the brake pressure in the closed state, and controlling the pressure-increase gradient by controlling the time ratio between the open state and the closed state;
A pressure reducing solenoid valve that reduces the brake pressure in the open state, holds the brake pressure in the closed state, and controls the pressure reduction gradient by controlling the time ratio between the open state and the closed state; and the control characteristic determining means. Means for reducing the ratio of the time for closing the solenoid valve for pressure increase to the time for opening the solenoid valve for reducing the pressure in order to make the pressure increase gradient of the brake pressure steep; 2. The antilock control device according to claim 1, further comprising means for increasing a ratio of a time for closing the pressure reducing solenoid valve to a time for opening the pressure reducing solenoid valve. If one of the previous SL two acceleration sensor fails, comprises means to obtain a composite acceleration of one of the detected acceleration and the estimated longitudinal acceleration of the acceleration sensor remains, the control characteristic determining means, one of the acceleration that the resultant acceleration of the detected acceleration and the estimated longitudinal acceleration sensor, antilock control apparatus according to claim 1 or 2 for use in place of the resultant acceleration of the two detected acceleration of said two acceleration sensors.

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