JP2005297591A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve pressure response of a brake.
In a hydraulic system, a linear valve adjusts the amount of hydraulic fluid supplied to a wheel cylinder. The feedback control means calculates a control current to the linear valve so that the target hydraulic pressure is obtained. In the region where the hydraulic pressure gradient of the wheel cylinder is low in rigidity, the control current is increased by the fast fill control means beyond the value calculated by the feedback control means. As a result, the response of the brake is improved. Furthermore, the fast fill control means starts the fast fill control when the hydraulic pressure of the wheel cylinder reaches the threshold value, and fast fill control when the increment from the threshold exceeds a predetermined value. Works to exit. As a result, in a region where the hydraulic pressure gradient is changed from low rigidity to high rigidity, the occurrence of vibration and abnormal noise due to an excessive supply liquid amount is suppressed.
[Selection] Figure 5

Description

  The present invention relates to a vehicle brake control technique, and more particularly to a vehicle brake control device having an electromagnetic valve that adjusts a control hydraulic pressure so as to be a target hydraulic pressure.

  2. Description of the Related Art Conventionally, as a braking control device for a vehicle such as an automobile, an oil pump driven by a motor is provided in the middle of a hydraulic conduit, and hydraulic fluid on the discharge side of the oil pump is accumulated in an accumulator to keep the accumulator pressure high. Are known. This high-pressure hydraulic fluid is introduced into the wheel cylinder via the pressure-increasing valve and hydraulic fluid passage among the electromagnetic flow control valves provided on each wheel in accordance with the driver's brake pedal operation, and exhibits a desired braking force. Is done.

  In the vehicle brake control device as described above, the amount of liquid consumption increases in the low pressure region. In the area where the amount of liquid consumed is large, the pressure increase / decrease width per unit liquid volume is small, so the rise and fall of the liquid pressure becomes loose, and the time until the actual pressure reaches the target pressure becomes longer. Caused a decrease in control responsiveness.

Therefore, in Patent Document 1, in the control of the load hydraulic pressure, when there is a pressure region with a large amount of liquid consumption within the control hydraulic pressure range, the pressure range is arbitrarily set for any time with respect to the target pressure. A technique for improving pressure responsiveness by performing overshoot control for adding the pressures of the above is disclosed.
JP-A-11-154024

  However, in the above-mentioned Patent Document 1, there is a problem that the pressure suddenly increases at a portion where the liquid consumption amount is changed to a region where the liquid consumption amount is small, and abnormal noise and vibration are generated accordingly. . Especially in drum brakes, it is difficult to know the change point of the hydraulic pressure, and it is difficult to match the timing to stop overshoot control, and abnormal noise is generated when changing from a region with a large amount of liquid to a region with a small amount of liquid. And vibration is likely to occur.

  This invention is made | formed in view of such a condition, The objective is to provide the technique which improves pressure responsiveness, suppressing generation | occurrence | production of abnormal noise and a vibration.

  An aspect of the present invention includes a wheel cylinder that is supplied with hydraulic oil to drive a brake, an electromagnetic valve that adjusts the amount of liquid supplied to the wheel cylinder, and a control for the electromagnetic valve to achieve a target hydraulic pressure. A braking control device for a vehicle, comprising: a feedback control means for calculating a current; and a fast that increases the control current from a value calculated by the feedback control means in a region where the hydraulic pressure gradient of the wheel cylinder is low in rigidity. A vehicular braking control device further comprising fast fill control means for executing fill control.

  Here, the “hydraulic pressure gradient” refers to the gradient of the graph when a graph is drawn with the wheel cylinder hydraulic pressure on the horizontal axis and the amount of liquid supplied to the wheel cylinder on the vertical axis. Also, in this graph, the state in which the hydraulic pressure change of the wheel cylinder is small although the amount of liquid consumption is large is called “low rigidity”. The large state is called “high rigidity”. According to this aspect, since the amount of fluid supplied to the wheel cylinder increases by executing the fast fill control, it is possible to improve the pressure response of the brake in the low rigidity region of the fluid pressure gradient.

  The fast fill control means starts the fast fill control when the hydraulic pressure of the wheel cylinder reaches a threshold value, and when the increment from the threshold exceeds a predetermined value, Control may be terminated. According to this, stopping the fast fill control when the hydraulic pressure gradient changes from low rigidity to high rigidity reduces the amount of liquid supplied to the wheel cylinder. Both suppression of sound and vibration can be achieved.

  The hydraulic pressure generated in the wheel cylinder when the hydraulic pressure gradient of the wheel cylinder becomes lower than a predetermined value may be set as the threshold value. The fluid pressure generated in the wheel cylinder when the fluid amount determined according to the capacity of the space formed by the wheel cylinder may be set as the threshold value. According to this, it is possible to determine the end time of the fast fill control by learning the time point when the rigidity becomes low. This is because the hydraulic pressure at the start of low rigidity varies for each wheel cylinder, but the pressure that increases when shifting from low rigidity to high rigidity is small for the wheel cylinder.

  The control current is stopped when the hydraulic pressure gradient of the wheel cylinder becomes lower than a predetermined value, and the hydraulic pressure of the wheel cylinder when a predetermined time has elapsed is set as the threshold value. May be. Alternatively, after supplying a liquid amount determined according to the capacity of the space formed by the wheel cylinder, the control current is stopped, and the hydraulic pressure of the wheel cylinder when a predetermined time has elapsed is set to the threshold value. It may be set as a value. According to this, even if pulsation occurs at the initial stage of supplying the liquid amount to the wheel cylinder, the control current is turned off and the process waits until the liquid pressure becomes stable. The fluid pressure for starting the fill control can be learned.

  Instead of stopping the control current immediately, it may be stopped after being gradually reduced. Since the hydraulic pressure sensor that detects the hydraulic pressure detects the hydraulic pressure upstream of the wheel cylinder, there is a time difference until the wheel cylinder reaches that pressure. It is possible to improve the accuracy of the control by gradually decreasing.

  The solenoid valve may be a linear valve having linear operation characteristics with respect to the control current.

  According to the vehicle brake control device of the present invention, it is possible to improve the pressure responsiveness in the low-rigidity region of the hydraulic pressure gradient while suppressing the generation of abnormal noise and vibration.

  First, the overall configuration of the hydraulic system 100 and the electronic control unit 200 to which the embodiment is applied will be described, then the problems recognized by the present inventor will be described, and then the control according to the embodiment will be described. In the following description, the electronic control unit 200 alone may be regarded as a braking control device, or a combination of the hydraulic system 100 or a part thereof and the electronic control unit 200 may be regarded as a braking control device.

  FIG. 1 shows the overall configuration of the hydraulic system 100 and the electronic control unit 200. The hydraulic system 100 mainly includes an actuator 80 and a master cylinder 14 other than the actuator 80.

  The brake pedal 12 is provided with a stroke sensor 46 that detects the depression stroke. The master cylinder 14 pumps brake oil, which is hydraulic fluid, in response to the driver's depression operation of the brake pedal 12. A dry stroke simulator 13 is provided between the brake pedal 12 and the master cylinder 14.

  One end of a brake hydraulic control conduit 16 for the right front wheel and a brake hydraulic control conduit 18 for the left front wheel are connected to the master cylinder 14, and these brake hydraulic control conduits exhibit the braking force of the right front wheel and the left front wheel, respectively. It is connected to wheel cylinders 20FR and 20FL for the right front wheel and the left front wheel. A right electromagnetic on-off valve 22FR and a left electromagnetic on-off valve 22FL that are normally open (hereinafter referred to as “normally open type”) are respectively inserted in the middle of the brake hydraulic control conduits 16 and 18 for the right front wheel and the left front wheel. In addition, right master and left master pressure sensors 48FR and 48FL for measuring the master cylinder hydraulic pressure on the right front wheel side and the left front wheel side are provided. When the brake pedal 12 is depressed by the driver, the depression is detected by the stroke sensor 46, and the master cylinder hydraulic pressure is measured by the right master and left master pressure sensors 48FR and 48FL assuming that the stroke sensor 46 is broken. Also, the depression of the brake pedal 12 is detected. The master cylinder hydraulic pressure is monitored by two pressure sensors from the viewpoint of fail-safe.

  A reservoir tank 26 is connected to the master cylinder 14, a wet stroke simulator 24 is connected via an on-off valve 23, and one end of a hydraulic supply / discharge conduit 28 is connected to the reservoir tank 26. The hydraulic supply / discharge conduit 28 is provided with an oil pump 34 driven by a motor 32. The discharge side of the oil pump 34 is a high-pressure conduit 30, and an accumulator 50 and a relief valve 53 are provided. The accumulator 50 accumulates brake oil that has been brought to a high pressure in the range of 16 to 21.5 MPa (hereinafter referred to as “control range”) by the oil pump 34. The relief valve 53 opens when the accumulator pressure is abnormally high, for example, 30 MPa, and allows high-pressure brake oil to escape to the hydraulic supply / discharge conduit 28.

  The high pressure conduit 30 is provided with an accumulator pressure sensor 51 that measures the accumulator pressure. The electronic control unit 200 described later receives the accumulator pressure that is the output of the accumulator pressure sensor 51, and controls the motor 32 so that the accumulator pressure falls within the control range.

  Each of the high-pressure conduits 30 is normally in a closed state (referred to as a “normally closed type”), and is used as an electromagnetic flow rate control valve, that is, a linear valve, for boosting the wheel cylinder when necessary. , 40FL, 40RR, 40RL, right front wheel wheel cylinder 20FR, left front wheel wheel cylinder 20FL, right rear wheel wheel cylinder 20RR, left rear wheel wheel cylinder 20RL (hereinafter collectively referred to as "wheel" Cylinder 20 ”). Hereinafter, the reference numeral 40 is used to collectively refer to the pressure increasing valves 40FR, 40FL, 40RR, and 40RL.

  Drum brakes 60FR, 60FL, 60RR, 60RL are provided on the right front wheel, left front wheel, right rear wheel, and left rear wheel of a vehicle (not shown), and brake shoes are driven by wheel cylinders 20FR, 20FL, 20RR, 20RL, respectively. The brake is exerted by pressing the against the drum. The structure and operation of the drum brake 60 will be described later with reference to FIG.

  The right front wheel cylinder 20FR and the left front wheel cylinder 20FL are hydraulically supplied and discharged via electromagnetic flow control valves used for pressure reduction when necessary, that is, linearly-controlled normally closed pressure reducing valves 42FR and 42FL. Connected to conduit 28. Further, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge conduit 28 through normally open pressure reducing valves 42RR and 42RL, respectively.

  Near the right front wheel, left front wheel, right rear wheel, and left rear wheel wheel cylinders 20FR, 20FL, 20RR, and 20RL, the right front wheel, the left front wheel, the right rear wheel, Pressure sensors 44FR, 44FL, 44RR, 44RL for the left rear wheel are provided.

  The electronic control unit 200 controls the electromagnetic on-off valves 22FR and 22FL, the motor 32, the four pressure increasing valves 40FR, 40FL, 40RR, and 40RL, and the four pressure reducing valves 42FR, 42FL, 42RR, and 42RL. Note that the reference numeral 42 is used to collectively refer to the pressure reducing valves 42FR, 42FL, 42RR, and 42RL. The electronic control unit 200 includes an arithmetic unit 202 by a microcomputer, a ROM 204 for storing various control programs, and a RAM 206 used as a work area for data storage and program execution.

  Although not shown in detail, the arithmetic unit 202 includes pressure sensors 44FR, 44FL, 44RR, 44RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel, respectively, in the wheel cylinder 20FR for the right front wheel. , Pressure signal in the left front wheel wheel cylinder 20FL, pressure signal in the right rear wheel wheel cylinder 20RR, pressure signal in the left rear wheel wheel cylinder 20RL (hereinafter, generally referred to as wheel cylinder hydraulic pressure). Signal). Further, the arithmetic unit 202 has a signal indicating the depression stroke of the brake pedal 12 from the stroke sensor 46 (hereinafter referred to as a stroke signal) and a signal indicating the master cylinder hydraulic pressure from the right master and left master pressure sensors 48FR and 48FL (hereinafter referred to as a master). A cylinder hydraulic pressure signal) and a signal indicating the accumulator pressure (hereinafter referred to as an accumulator pressure signal) are input from the accumulator pressure sensor 51.

The ROM 204 of the electronic control unit 200 stores a predetermined braking control flow. The arithmetic unit 202 calculates the target deceleration of the vehicle based on the stroke signal and the master cylinder hydraulic pressure signal, and the target wheel cylinder hydraulic pressure (hereinafter also referred to as target hydraulic pressure _Pref ) of each wheel based on the calculated target deceleration. And the wheel cylinder hydraulic pressure (hereinafter also referred to as control hydraulic pressure _Pwc ) of each wheel is controlled to be the target hydraulic pressure _Pref .

FIG. 2 is a functional block diagram relating to hydraulic pressure control by the arithmetic unit 202. The arithmetic unit 202 includes a fast fill control unit 220 and a feedback control unit 222. Upon receiving the target hydraulic pressure _Pref , the arithmetic unit 202 receives the target hydraulic pressure _Pref and pressurizes the pressure increasing valve 40 and the pressure reducing valve 42 (hereinafter simply referred to as the linear valves 40 and 42). A control current I to be supplied to the control circuit is calculated. The control hydraulic pressure P _wc obtained by the operation of the linear valves 40 and 42 driven by the control current I is fed back to the arithmetic unit 202.

Fast fill control unit 220 receives the target hydraulic pressure P _ref, based on the physical properties and load model of the linear valves 40 and 42, fast fill current from such inclination or opening current of the target pressure in a known manner to calculate the I _F under a predetermined gain, and outputs. However, the fast fill control unit 220, per the calculation of fast fill current I _F, to reflect the nature against fluid pressure in the wheel cylinder system. The wheel cylinder system is a space filled with high-pressure brake oil from the pressure increasing valve 40 to the wheel cylinder in the pressure increasing mode during braking.

Specifically, 1) If the capacity of the wheel cylinder system is larger than a predetermined reference capacity, the capacity-based correction amount ΔI ₁ is added to the fast fill current, and 2) the initial stiffness against the hydraulic pressure of the wheel cylinder system is a predetermined reference When the stiffness is lower than the stiffness, the stiffness-based correction amount ΔI ₂ is added to the fast fill current. Rubber members in pipes that expand with hydraulic pressure, clearances that allow brake oil to enter inside through structural holes and gaps when hydraulic pressure is applied, and pipes and tanks that increase in diameter when hydraulic pressure is applied If there is such a member, the initial rigidity against the hydraulic pressure becomes low. The two corrections may be performed simultaneously, and the fast fill control unit 220 performs the following calculation internally.
I _F ← I _F + ΔI ₁ + ΔI ₂

Here, the “predetermined reference capacity” and the “predetermined reference rigidity” may be those determined in the past, and the correction amount may be determined by the difference from these reference values. The amount of correction may be variable depending on the magnitude of the difference. However Of course, in addition to obtaining a correction amount from the reference value may be derived the value of the optimal fast fill current I _F on the first experimental. It should be noted that a member whose rigidity is a problem is not changed in shape when a high fluid pressure is applied to some extent and is balanced by a stress or the like. Therefore, the rigidity is a problem when the fluid pressure is relatively low. For this reason, as in the present embodiment, it is useful to consider the initial rigidity of the wheel cylinder system in the fast fill control performed in the initial stage of the pressure increasing mode. Even when the capacity of the wheel cylinder system is large or the initial rigidity is low, good response to the braking request can be obtained.

The subtracting unit 234 subtracts the control hydraulic pressure P _wc from the target hydraulic pressure P _ref and outputs the hydraulic pressure difference P _error . Feedback control unit 222 receives the hydraulic pressure difference _{P error} from the subtraction unit 234, the PID control or the like, and calculates a feedback current _{I B} for approximating the pressure difference _{P error} to 0 under a predetermined gain output To do. Adding section 230 adds a fast fill current _{I F} and the feedback current _{I B,} and outputs the calculated control current I to be supplied to the linear valves 40 and 42.

  An outline of the braking control in the above configuration will be described. First, before the driver turns on the ignition switch, that is, before energization of each solenoid valve, each solenoid valve is in the state of FIG. 1 due to the biasing force of the spring incorporated therein. At this time, the brake oil at atmospheric pressure reaches from the master cylinder 14 to the right front wheel and left front wheel cylinders 20FR and 20FL via the right and left electromagnetic on-off valves 22FR and 22FL, respectively. On the other hand, the right rear wheel and the left rear wheel cylinders 20RR and 20RL are also braked at the same atmospheric pressure as the hydraulic pressure in the reservoir tank 26 via the hydraulic supply / discharge conduit 28 and the normally open pressure reducing valves 42RR and 42RL. Oil has reached. At this time, all four wheel cylinder hydraulic pressures are atmospheric pressure, and no braking force is generated. However, even before the power is applied, if the driver steps on the brake pedal 12, the braking force corresponding to the depression force directly acts on the wheel cylinders 20FR, 20FL of the right front wheel and the left front wheel, and these right front wheel and left front wheel There is a braking force.

  When the driver turns on the ignition switch, the motor 32 operates as necessary, and the accumulator pressure becomes an appropriate high pressure. Thereafter, each solenoid valve is in the state shown in FIG. Subsequently, when the driver steps on the brake pedal 12, the master cylinder 14 is first pushed in, and the communication between the master cylinder 14 and the reservoir tank 26 is shut off. Further, the right and left electromagnetic on-off valves 22FR and 22FL are closed, the on-off valve 23 is opened, and communication of brake oil at atmospheric pressure from the master cylinder 14 to the wheel cylinders 20FR and 20FL of the right front wheel and the left front wheel is cut off. . Further, the pressure reducing valves 42RR and 42RL for the right rear wheel and the left rear wheel are closed, and the four pressure increasing valves 40FR, 40FL, 40RR and 40RL are opened. The opening degree of each solenoid valve is controlled based on the target wheel cylinder hydraulic pressure of each wheel calculated through various calculations described later.

  FIG. 3 shows a schematic structure of a drum brake 60 which is a control target of the present embodiment. The drum 62 rotates together with the vehicle wheels. When brake oil is supplied from the hydraulic system 100 to the wheel cylinder 20, the piston protrudes and presses the brake shoe 66 with a friction material called a lining against the inner peripheral surface of the drum 62. This frictional effect generates a braking force. The return spring 68 urges the brake shoes 66 in a direction in which the brake shoes 66 are attracted to each other, and plays a role of pulling the brake shoes 66 away from the inner peripheral surface of the drum 62 when the pressure is released. A distance between the brake shoe 66 and the inner peripheral surface of the drum 62 at the time of pressure removal is referred to as a shoe clearance 70.

  FIG. 4 shows the relationship between the wheel cylinder hydraulic pressure and the amount of liquid consumed when the drum brake is operated. In the fluid pressure-consumed fluid amount graph of FIG. 4, a state in which the fluid pressure change of the wheel cylinder is small although the amount of fluid consumed is large is referred to as “low rigidity”. Regardless, the state where the hydraulic pressure change of the wheel cylinder is large is called “high rigidity”. In other words, as shown in the graph of FIG. 4, “high rigidity” is obtained when the inclination is small, and “low rigidity” is obtained when the inclination is large.

  In the drum brake 60, it is necessary to overcome the urging force of the return spring 68 before the brake oil is supplied to the wheel cylinder 20 and the brake shoe 66 starts moving because of the structure. Therefore, the relationship between the wheel cylinder hydraulic pressure and the amount of liquid consumption draws a graph as shown in FIG. That is, in the region “A” in the figure, until the hydraulic pressure in the wheel cylinder overcomes the set load of the return spring 68, the piston of the wheel cylinder 20 hardly moves, so the liquid amount does not increase and the graph becomes highly rigid. . In the region “B”, the hydraulic pressure in the wheel cylinder 20 overcomes the urging force of the return spring 68, and the cylinder operates to push the brake shoe 66 against the inner surface of the drum 62 until the shoe clearance 70 is clogged. Since the amount of liquid consumption increases, the graph has low rigidity. In the region “C”, when the shoe clearance 70 is clogged and the brake shoe 66 comes into contact with the inner peripheral surface of the drum 62, the piston of the wheel cylinder 20 hardly moves again, so that the amount of liquid does not increase and the graph is in a highly rigid state. Become. That is, the consumption liquid amount characteristic of the wheel cylinder 20 changes from high rigidity to low rigidity and again to high rigidity as the hydraulic pressure increases.

  Thus, if the rigidity of the hydraulic pressure gradient changes before the drum brake generates a braking force, the control cannot catch up, causing vibration and abnormal noise. In particular, in the part where the low rigidity region where the shoe clearance is filled is changed to the high rigidity region where the braking force is actually generated, the fluid pressure increases rapidly because the rigidity changes while the fluid volume is increasing. This may cause vibration and abnormal noise.

  Conventionally, in a hydraulic brake, there has been no technology that can absorb such a change in rigidity satisfactorily. That is, even if the same control current is supplied to the control valve, the brake shoe 66 comes into contact with the inner peripheral surface of the drum 62 due to variations in the spring constant of the return spring of the drum brake 60 and shoe clearance, and braking force is generated. Since the hydraulic pressure at the start of the operation varies, it has been difficult to determine the timing for stopping the fast fill control current that should flow while the braking force is not generated.

  Therefore, in this embodiment, the timing at which the fast fill current is stopped can be obtained by learning the hydraulic pressure at the timing at which the fast fill control current starts to flow. Hereinafter, a control method in the embodiment will be described.

  FIG. 5 is a flowchart showing a flow of the braking control process according to the present embodiment. This flow is continuously executed at predetermined time intervals. Prior to braking control, when the driver steps on the brake pedal 12, the right and left electromagnetic on-off valves 22FR, 22FL are first closed, the on-off valve 23 is opened, and the right front wheel and left front wheel wheel cylinder 20FR are opened from the master cylinder 14. , Communication of brake oil at atmospheric pressure to 20FL and communication between the master cylinder 14 and the reservoir tank 26 are blocked. In this state, first, the stroke signal is read (S10), the master cylinder hydraulic pressure signal is read (S12), and the target deceleration is calculated by the calculation unit 202 from these signals by a known method (S14).

Subsequently, the calculation unit 202 calculates the target hydraulic pressure P _ref of each wheel with respect to the target deceleration (S16), and calculates the hydraulic pressure P _wc in the wheel cylinders 20FR, 20FL, 20RR, 20RL of each wheel as pressure sensors 44FR, 44FL. , 44RR, 44RL (S18). The feedback control unit 222 calculates the feedback current I _B from the difference between the target hydraulic pressure P _ref and the control hydraulic pressure P _wc that is the actual wheel cylinder hydraulic pressure (S20).

Next, it is determined whether or not the fast fill control unit 220 has already learned the shoe clearance hydraulic pressure P _s , in other words, whether or not the learned flag set in S28 is “1” (S22). . Here, the “shoe clearance hydraulic pressure” is the wheel cylinder hydraulic pressure at the point where the balance with the urging force of the return spring 68 is reached. If the flag is not learned "0" and is fast fill control unit 220 is still the shoe clearance pressure P _s (NO in S22), the amount of brake fluid that will substantially balance the biasing force of the return spring 68 It flows through the wheel cylinder 20 (S24). This amount of liquid is determined according to the capacity of the space formed by the wheel cylinder, and if the drum brake is of the same type, the flow rate is almost constant and can be obtained by experiments or the like. The fast fill control unit 220 acquires the pressure of the wheel cylinder 20 when a current of this liquid amount as shoe clearance pressure P _s (S26). Even liquid volume is the same, because of the variations in the spring constant of the return spring 68, the shoe clearance fluid pressure P _s takes a different value for each wheel cylinder. For example, when the spring constant of the return spring 68 is large, a larger wheel cylinder hydraulic pressure is shown even if the liquid amount is the same. Therefore, if the drum brakes provided in the four-wheel vehicle, the fast fill control unit 220 acquires the shoe clearance fluid pressure P _s for each wheel. Incidentally, fast fill control unit 220, the shoe clearance fluid pressure P _s may be acquired hydraulic pressure generated in the wheel cylinder 20 when the hydraulic pressure gradient becomes lower rigidity than a predetermined value.

Then, "1" is set to the learned flag indicating that it is already learned the shoe clearance fluid pressure P _s (S28). Since it is sufficient to use the already learned shoe clearance hydraulic pressure P _s in the subsequent calculations, the determination in S22 is YES, and the processing from S24 to S28 is skipped.

Fast fill control unit 220, based on the target hydraulic pressure P _ref obtained in S16, by the above-described method, calculates the fast fill current I _F which reflects the initial rigidity of the wheel cylinder system (S30). The control current I fast fill current _{I F} and the feedback current _{I B} is added is supplied to the linear valves 40, 42 (S32).

The arithmetic unit 202 determines only whether the wheel cylinder pressure is increased pressure P _th predetermined from the shoe clearance fluid pressure P _s obtained in S26 (S34). Since the pressure _Pth does not vary much, the same value can be used for the same type of drum brake, and this value can be obtained by experiments or the like. If the pressure does not increase by the pressure _Pth (NO in S34), control of the linear valves 40 and 42 is continued (S32). When the pressure increases by the pressure _Pth (YES in S34), the wheel cylinder hydraulic pressure changes from a low rigidity to a high rigidity, that is, a point of transition from “B” to “C” in the graph of FIG. so fast fill control unit 220 stops the fast fill current _{I F} (S36). That is, this point on, only the feedback current I _B flows.

As described above, at the point where the wheel cylinder hydraulic pressure changes from low rigidity to high rigidity, the fast fill current _IF is stopped to eliminate unnecessary current and reduce the brake oil flow rate. No sudden rise occurs, and abnormal sounds and vibrations accompanying this can be suppressed.

  FIG. 6 is a diagram illustrating an example of a time change of the wheel cylinder hydraulic pressure and the control current when the control is performed according to the flowchart of FIG. 5.

First, in the region “A”, a predetermined liquid amount is supplied from time t _1, and the wheel cylinder hydraulic pressure at time t _{2 when} the liquid amount has been supplied is acquired as the shoe clearance hydraulic pressure P _s . As described above, this state is whether or not the brake shoe 66 starts to move.

Next, in the region "B", flow and the feedback current I _B corresponding to the brake stroke, the control current I obtained by adding the amount of fast fill current I _F to pack shoe clearance. This fast fill current needs to be stopped at an appropriate time. Fast fill control unit 220 turns off the fast fill current _{I F} when the pressure _{P th} minute increment (time _{t 3).} Shoe Clearance solution time t ₃ after the pressure P _s was acquired, as shown in a region "C", flow only normal feedback current I _B.

  As described above, according to the present embodiment, in the vehicle braking control device having the electromagnetic valve that controls the hydraulic pressure in response to the braking request, the fast fill control is performed in the region where the amount of consumed liquid is large, and the control is started. As a point, the hydraulic pressure when the hydraulic pressure gradient in the relationship between the hydraulic pressure and the consumed liquid amount becomes low rigidity is learned, and the control stop point is determined when the hydraulic pressure change from the learned value exceeds a predetermined amount. Set. As a result, the fast fill current can be appropriately flowed, and both of ensuring responsiveness and suppressing noise and vibration can be achieved.

  The present invention has been described above based on the embodiment. It is to be understood by those skilled in the art that these embodiments are exemplifications, and various modifications can be made to the combination of each component, and such modifications are also within the scope of the present invention. Hereinafter, such modifications will be described.

When the control current for supplying the oil amount to the wheel cylinder is large in the low pressure region, hydraulic pressure pulsation may occur. When in such a pulsating, there is a possibility that the time to stop the fast fill current when learning the shoe clearance pressure P _s is shifted. Therefore, after passing a predetermined amount of liquid to wheel cylinders to stop a predetermined between control current, fluid pressure may be learned shoe clearance pressure P _s at stable.

This is shown in FIG. First, in a region “A”, after a predetermined amount of liquid is supplied from time t ₁ to time t ₂ , the control current I is once set to zero. That is, S24 of the flowchart of FIG. 5 is executed, and the control current is turned off after a lapse of a predetermined time (see the region indicated by “OFF” in the lower diagram of FIG. 7). The predetermined time varies depending on the brake type and the characteristics of the brake oil passage, and can be obtained in advance by experiments or the like. During this time, (see time t ₃₎ as shown in the upper diagram of FIG. 7, the wheel cylinder pressure pulsates, by waiting a predetermined time, the wheel cylinder hydraulic pressure which becomes substantially shows a constant value. The fast fill control unit 220 obtains the wheel cylinder pressure at the time t ₃ as the shoe clearance pressure P _s. The shoe clearance pressure P _s, as described above, is where the boundary of whether the brake shoe 66 begins to move.

Next, in the region "B", flow and the feedback current I _B corresponding to the brake pedal force, the control current I obtained by adding the fast fill current I _F to pack shoe clearance. This fast fill current needs to be turned off at an appropriate time. In order to determine this, the fast fill control unit 220 turns off the fast fill current _{I F} when the pressure _{P th} minute increment (time _{t 4).} After the time t ₄ when acquiring the shoe clearance hydraulic pressure, as shown in a region "C", flow only normal feedback current I _B.

  In the embodiment, the fast fill current is suddenly turned off, but may be gradually decreased. Even if the fast fill current gradually decreases linearly, the rate of gradual decrease may be increased.

  Although the embodiment has been described using a leading / trailing type drum brake, the same applies to other types of drum brakes such as a two-leading type. The present invention can also be applied to a floating type disc brake in which a caliper is operated by a cylinder to pinch the disc rotor to generate a braking force. For example, this is effective when the sliding resistance of the caliper is large and a certain amount of liquid is required until the braking force is generated. For example, when the wheel cylinder system has a large volume such as an opposed caliper, the improvement effect by applying the present invention is great.

1 is an overall configuration diagram of a vehicle brake control device according to an embodiment. It is an internal block diagram of the arithmetic unit of FIG. It is a figure which shows schematic structure of a drum brake. It is a graph which shows the relationship between a wheel cylinder hydraulic pressure and the amount of liquid consumption. It is a flowchart which implements the brake control which concerns on embodiment. It is a graph which shows the relationship between control current and wheel cylinder hydraulic pressure. It is a graph explaining the modification which turns off control current temporarily.

Explanation of symbols

  12 brake pedal, 14 master cylinder, 20FR, 20FL, 20RR, 20RL wheel cylinder, 22FR right solenoid on-off valve, 22FL left solenoid on-off valve, 26 reservoir tank, 32 motor, 34 oil pump, 40FR, 40FL, 40RR, 40RL booster valve , 42FR, 42FL, 42RR, 42RL Pressure reducing valve, 44FR, 44FL, 44RR, 44RL Pressure sensor for each wheel, 48FR Right master pressure sensor, 48FL Left master pressure sensor, 50 Accumulator, 51 Accumulator pressure sensor, 60 Drum brake, 62 drum , 66 brake shoe, 68 return spring, 70 shoe clearance, 80 actuator, 100 hydraulic system, 200 electronic control unit, 202 arithmetic unit, 204 ROM, 206 RAM, 220 fast fill control unit, 222 feedback control unit.

Claims (7)

A wheel cylinder that is supplied with hydraulic oil and drives a brake;
A solenoid valve for adjusting the amount of liquid supplied to the wheel cylinder;
Feedback control means for calculating a control current to the solenoid valve so as to achieve a target hydraulic pressure;
In a vehicle brake control device comprising:
The vehicle further comprising: a fast fill control unit that performs a fast fill control for increasing a control current in a region where the hydraulic pressure gradient of the wheel cylinder is low-rigidity than a value calculated by the feedback control unit. Braking control device.   The fast fill control means starts the fast fill control when the hydraulic pressure of the wheel cylinder reaches a threshold value, and when the increment from the threshold exceeds a predetermined value, The vehicle braking control device according to claim 1, wherein the fill control is terminated.   3. The vehicle brake according to claim 2, wherein the hydraulic pressure generated in the wheel cylinder when the hydraulic pressure gradient of the wheel cylinder becomes lower than a predetermined value is set as the threshold value. Control device.   3. The vehicle according to claim 2, wherein a hydraulic pressure generated in the wheel cylinder when a liquid amount determined according to a capacity of a space formed by the wheel cylinder is supplied is set as the threshold value. Braking control device.   The control current is stopped when the hydraulic pressure gradient of the wheel cylinder becomes lower than a predetermined value, and the hydraulic pressure of the wheel cylinder when a predetermined time has elapsed is set as the threshold value. The vehicle brake control device according to claim 2, wherein   After supplying the liquid amount determined according to the capacity of the space formed by the wheel cylinder, the control current is stopped, and the hydraulic pressure of the wheel cylinder when a predetermined time has elapsed is used as the threshold value. The vehicle braking control device according to claim 2, wherein the vehicle braking control device is set. The vehicular braking control apparatus according to claim 5 or 6, wherein the control current is gradually reduced and then stopped.

Images