JP2008260417A - Brake boost control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake boost control device for accurately detecting a pressure generated by a driver's brake pedal operating force and generating a wheel cylinder pressure corresponding to the brake pedal operating force with high accuracy.
A current value for energizing a coil of a gate-out valve is given based on a difference between a braking intention and a target braking force, and a hydraulic pressure higher than the target braking force can be generated between the wheel cylinder and the gate-out valve. Equipped with an appropriate hydraulic pressure source.
[Selection] Figure 2

Description

  The present invention relates to a technical field of a brake boost control device that boosts a driver's brake pedal operating force to generate a large wheel cylinder pressure.

Conventionally, a negative pressure booster that uses engine negative pressure and a hydraulic pressure booster that uses an accumulator are often used as a brake system that boosts the driver's brake pedal operating force to generate a large wheel cylinder pressure. Has been. However, since these boosters are large-sized, for example, the technique described in Patent Document 1 is known. This publication discloses that when a driver's brake pedal operation is detected, a hydraulic pump built in the anti-lock brake system is operated to generate a wheel cylinder pressure larger than the pressure generated by the brake pedal operating force. Has been.
JP 11-227590 A

  In the brake booster control device described in Patent Document 1 described above, a pedal sensor that detects the brake pedal operation amount is provided between the brake pedal and the master cylinder. Since the pedal sensor does not directly detect the pressure, there is a problem that an accurate pressure cannot be detected due to the influence of the friction of the input rod and the friction of the piston in the master cylinder.

  The present invention has been made paying attention to the above-mentioned problems, and the problem is that the pressure generated by the driver's brake pedal operating force is detected with high accuracy, and the wheel cylinder pressure corresponding to the brake pedal operating force is detected with high accuracy. An object of the present invention is to provide a brake booster control device that generates the brake booster.

  In order to achieve the above object, according to the present invention, a master cylinder that generates pressure according to a driver's braking operation, a wheel cylinder that is provided in each wheel and generates a braking force on the wheel, the master cylinder, and the wheel An electromagnetic valve disposed between the cylinder and the opening degree of which is determined based on a balance between the electromagnetic attraction force of the coil, the force according to the master cylinder pressure, and the force according to the wheel cylinder pressure, and braking of the driver A braking intention detecting means for detecting an intention; a target braking force calculating means for calculating a target braking force based on the braking intention; and a current value for energizing the coil based on a difference between the braking intention and the target braking force. And a hydraulic pressure source capable of generating a hydraulic pressure equal to or higher than the target braking force between the wheel cylinder and the electromagnetic valve.

  Therefore, the control amount based on the difference between the braking intention and the target braking force is simply fed forward as the current value of the solenoid valve, and the difference between the master cylinder and the wheel cylinder is automatically made without finely controlling the hydraulic pressure source. The pressure can be controlled. That is, since the valve opening degree of the electromagnetic valve can be controlled by the current, the wheel cylinder pressure can be controlled to a hydraulic pressure corresponding to a desired target braking force.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.

  The brake booster control apparatus according to the first embodiment includes a motor, a pump, a solenoid valve, a sensor, and the like, a hydraulic unit 31 interposed between a master cylinder M / C and a wheel cylinder W / C, This is an electromechanically integrated brake booster that is integrally formed with the hydraulic unit 31 and includes a control unit CU that controls each element. Note that the configuration is not limited to a mechanical / electrical integrated configuration, and the hydraulic unit 31 and the control unit CU may be configured separately and are not particularly limited.

[Configuration of brake piping]
FIG. 1 is a hydraulic circuit diagram of a brake system to which a brake booster control device of the present invention is applied. This brake system has a piping structure called X piping, which consists of two systems, a P system and an S system.

  The P system is connected to the wheel cylinder W / C (FL) for the left front wheel and the wheel cylinder W / C (RR) for the right rear wheel. The wheel cylinder W / C (FR) for the right front wheel is connected to the S system. The wheel cylinder W / C (RL) on the left rear wheel is connected. Each of the P system and the S system is provided with a pump PP and a pump PS, and the pump PP and the pump PS are driven by one motor M. In addition, you may comprise from one motor and one pump, a plunger pump and a gear pump may be mounted, and it does not specifically limit.

  The brake pedal BP is provided with a brake switch BS that detects the operation state of the brake pedal BP. The brake pedal BP is connected to the master cylinder M / C via the input rod 1.

  Master cylinder M / C and the suction side of pumps PP and PS (hereinafter referred to as pump P) are connected by pipes 11P and 11S (hereinafter referred to as pipe 11 (corresponding to the third brake circuit)). Has been. On each pipeline 11, gate-in valves 2P and 2S, which are normally closed electromagnetic valves, are provided. A pressure sensor PMC that detects the pressure of the master cylinder M / C is provided between the master cylinder M / C and the gate-in valve 2P.

  Further, on the pipeline 11, between the gate-in valves 2P and 2S (hereinafter referred to as gate-in valve 2) and the pump P, check valves 6P and 6S (hereinafter referred to as check valve 6) are provided. The check valves 6 allow the brake fluid to flow in the direction from the gate-in valve 2 to the pump P, and prohibit the flow in the opposite direction.

  The discharge side of each pump P and each wheel cylinder W / C are connected by pipelines 12P and 12S (hereinafter referred to as pipeline 12 (corresponding to the second brake circuit)). On each pipeline 12, solenoid-in valves 4FL, 4RR, 4FR, 4RL (hereinafter referred to as solenoid-in valves 4), which are normally open solenoid valves corresponding to the respective wheel cylinders W / C, are provided.

  Further, check valves 7P and 7S (hereinafter referred to as check valves 7) are provided on the pipes 12 and between the solenoid-in valves 4 and the pumps P. The brake fluid flow in the direction from the pump P toward the solenoid-in valve 4 is allowed, and the flow in the opposite direction is prohibited.

  Furthermore, each pipeline 12 is provided with pipelines 17FL, 17RR, 17FR, and 17RL (hereinafter referred to as pipeline 17) that bypass each solenoid-in valve 4, and the pipeline 17 includes a check valve 10FL. , 10RR, 10FR, 10RL (hereinafter referred to as check valve 10). Each check valve 10 allows the flow of brake fluid in the direction from the wheel cylinder W / C toward the pump P, and prohibits the flow in the opposite direction.

  Master cylinder M / C and pipe 12 are connected by pipes 13P and 13S (hereinafter referred to as pipe 13 (corresponding to the first brake circuit)), and pipe 12 and pipe 13 are connected to pump P. It merges with the solenoid-in valve 4. On each pipe line 13, gate-out valves 3 </ b> P and 3 </ b> S (hereinafter referred to as gate-out valve 3 (corresponding to a mechanical feedback mechanism)) which are normally open electromagnetic valves are provided. Here, in the pipeline 13, the pipeline on the master cylinder side from the gate-out valve 3 is referred to as a master side pipeline 13a, and the pipeline on the wheel cylinder side is referred to as a foil side pipeline 13b.

  Each pipeline 13 is provided with pipelines 18P and 18S (hereinafter referred to as pipelines 18) that bypass each gate-out valve 3, and the pipeline 18 includes check valves 9P and 9S (hereinafter referred to as pipelines 18). A check valve 9). Each check valve 9 permits the flow of brake fluid in the direction from the master cylinder M / C side toward the wheel cylinder W / C, and prohibits the flow in the opposite direction.

  On the suction side of the pump P, reservoirs 16P and 16S (hereinafter referred to as the reservoir 16) are provided, and the reservoir 16 and the pump P are connected by pipe lines 15P and 15S (hereinafter referred to as the pipe line 15). ing. Check valves 8P and 8S (hereinafter referred to as check valve 8) are provided between the reservoir 16 and the pump P, and each check valve 8 has a flow of brake fluid in the direction from the reservoir 16 toward the pump P. Is allowed and flow in the opposite direction is prohibited.

  The wheel cylinder W / C and the pipeline 15 are connected by pipelines 14P and 14S (hereinafter referred to as pipeline 14 (corresponding to the fourth brake circuit)), and the pipeline 14 and pipeline 15 are connected to the check valve 8. And the reservoir 16 merge. Each pipe line 14 is provided with solenoid-out valves 5FL, 5RR, 5FR, 5RL, which are normally closed solenoid valves.

  FIG. 2 is a block diagram illustrating a control configuration in the control unit CU of the brake booster control apparatus according to the first embodiment. This control unit CU describes only the part that receives the pressure command PMC as an input and outputs the drive command values to the motor M and the gate-out valve 3. As for drive command values to other various solenoid valve controls (solenoid in valve 4, solenoid out valve 5, gate in valve 2), drive command values are appropriately output from other control logic.

  The target hydraulic pressure calculation unit 101 calculates a target hydraulic pressure P * of the wheel cylinder W / C based on a signal of the master cylinder pressure Pmc detected by the pressure sensor PMC, and a differential pressure calculation unit 102 and a target hydraulic amount described later Output to the calculation unit 105. Here, the brake booster control device of the first embodiment includes a mechanical booster (for example, a type using engine negative pressure) between the master cylinder M / C and the hydraulic unit 31. Absent. Therefore, the value detected by the pressure sensor PMC detects the master cylinder pressure Pmc corresponding to the pedaling force of the driver.

  In general vehicles, a booster is arranged between the brake pedal and the master cylinder, and is configured to boost the driver's brake pedal depression force and press the input rod to generate a high master cylinder pressure Pmc. Yes. On the other hand, the first embodiment is different in that a master cylinder pressure Pmc corresponding to the pedaling force of the driver is generated. Further, the target hydraulic pressure P * is set to a hydraulic pressure that is considered to be generated in the master cylinder pressure Pmc when the booster is mounted, but can be set as appropriate and is not particularly limited.

[Gateout valve control]
The differential pressure calculation unit 102 calculates a target differential pressure ΔP between the detected master cylinder pressure Pmc and the target hydraulic pressure P *, and outputs it to a gate-out valve target current calculation unit 103 described later.

  The gate-out valve target current calculation unit 103 calculates the target current value I * of the gate-out valve 3 based on the input differential pressure ΔP as shown in the gate-out valve current-differential pressure characteristic map shown in FIG. To do. For example, in order to secure the target differential pressure ΔP of 3.0 Mpa, 0.5 A is set as the target current value I *. This characteristic is a value determined by the design value of the solenoid valve.

  The gate-out valve drive command unit 104 drives the switching circuit (not shown) by PWM so that the target current value I * is obtained, and outputs a desired current value to the gate-out valve 3.

  Here, the differential pressure control in the gate-out valve 3 will be described. FIG. 4 is a schematic diagram showing the configuration of the gate-out valve 3. The gate-out valve 3 includes a coil 3a that generates an electromagnetic attractive force, a mover 3b that operates according to the electromagnetic attractive force, and a valve body 3c that is connected to the conduit 13a and the conduit 13b.

  When the mover 3b moves downward in FIG. 4, the pipeline 13a and the pipeline 13b are closed, while when the mover 3b moves upward in FIG. 4, the pipeline 13a and the pipeline 13b open. It becomes a valve state. That is, the communication state (differential pressure) between the pipe line 13a and the pipe line 13b is determined according to the vertical position of the mover 3b.

  The mover 3b includes a force Fwc that is to be pushed upward in FIG. 4 according to the pressure Pwc on the wheel cylinder side, a force Fmc that is to be pushed downward in FIG. 4 according to the master cylinder pressure Pmc, and electromagnetic suction. According to the force, a force Fb that attempts to push down in FIG. 4 acts. In addition, since it is a normally open valve, a force in the valve opening direction is actually applied by the spring, but it is ignored here (in consideration, an offset value or the like may be given).

  The position of the mover 3b stops at a position where these forces are balanced. In other words, when Fmc + Fb−Fwc = 0, the mover 3b stops. When Fmc + Fb−Fwc> 0, the mover 3b moves downward. When Fmc + Fb−Fwc <0, the mover 3b Move upward. Since Fmc is a value correlated with the master cylinder pressure Pmc, and Fwc is a value correlated with the wheel cylinder pressure, it can be said that the target differential pressure ΔP is correlated with (Fmc−Fwc). When the above relational expression is modified, the position of the mover 3b is determined by the magnitude relationship between (Fmc−Fwc) and Fb. Therefore, if the same electromagnetic attraction force Fb as the target differential pressure ΔP is set, the target differential pressure ΔP Is automatically determined.

  Considering the proposal of a booster control device, it is assumed that a higher pressure is generated using a pump or the like on the wheel cylinder side than the gate-out valve 3 and the wheel cylinder pressure Pwc is higher than the master cylinder pressure Pmc. It will be. At this time, if the electromagnetic attractive force Fb is set to a value corresponding to the desired differential pressure ΔP, the position of the mover 3b is automatically changed according to the pressure increasing action performed on the wheel cylinder side, A target wheel cylinder pressure can be obtained. For example, when the discharge pressure of a pump or the like is high, the wheel cylinder pressure is discharged to the master cylinder side until the mover 3b moves upward and automatically reaches the target differential pressure ΔP, and acts in the pressure reducing direction.

  This eliminates the need for complicated feedback control and allows the motor control error to be absorbed by the gate-out valve 3. In other words, after giving the target current value I * corresponding to the target differential pressure ΔP in a feed-forward manner based on the driver's brake pedal depression force, the gate-out valve 3 functions as the target differential pressure ΔP. It is synonymous with a mechanical feedback mechanism that achieves the above, and does not require a sensor or the like for detecting the state of a controlled object as compared with an electronic feedback control mechanism, and can be said to have very high control stability.

[About motor drive control]
The target fluid amount calculation unit 105 converts the target fluid pressure P * into the target fluid amount Q *. The target fluid amount Q * is based on the relationship that the fluid pressure P is generated when this fluid amount Q is placed in the wheel cylinder W / C, and is determined by the design value of the wheel cylinder. .

  The liquid amount deviation calculating unit 106 calculates a liquid amount deviation ΔQ between the target liquid amount Q * and the actual liquid amount Q inputted from the liquid amount converting unit 110 described later, and the motor target rotation number calculating unit 107 described later is calculated. Output.

  The motor target rotational speed calculation unit 107 divides the input fluid amount deviation ΔQ by the control period (corresponding to differentiation) to convert it into a flow rate, and calculates the target rotational speed N * of the motor M based on this flow rate. . That is, since the motor rotation speed has a correlation with the flow rate per unit time discharged from the pump P, the motor target rotation speed N * required to fill the necessary liquid amount deviation based on the differential value of the liquid amount. Is calculated.

  The motor drive command unit 108 calculates a motor drive command value that achieves the motor target rotational speed N * and outputs a drive command value to the motor M. Here, in the first embodiment, the motor M is not particularly limited. For example, when a brush motor is employed, a counter electromotive voltage when the brush motor is controlled on and off is detected, and the counter electromotive voltage and the motor are detected. Since there is a proportional relationship with the rotational speed, the motor rotational speed is estimated, and control is performed so that the estimated rotational speed matches the motor target rotational speed N *. Further, when a brushless motor is employed, since a rotation angle sensor is provided, control may be performed so as to match the motor target rotation speed N * based on the value of the rotation angle sensor.

The wheel cylinder pressure estimation unit 109 estimates the wheel cylinder pressure based on the master cylinder pressure Pmc, the gate-out valve drive command value, and the motor drive command value. Specifically, it is estimated by the following procedure.
(i) The pump discharge amount [m ³ / s] is calculated from the motor speed. Then, the pump discharge liquid amount [m ³ ] is calculated by multiplying the time of the control cycle by the pump discharge amount.
(ii) There is a relationship between the wheel cylinder pressure and the wheel cylinder fluid amount beforehand, and from this relationship, the wheel cylinder fluid amount is converted from the wheel cylinder pressure estimated in the previous control cycle, and in the above (i) Add the calculated pump discharge fluid amount. Convert it to wheel cylinder pressure again.
(iii) The upper limit value of the wheel cylinder pressure is determined from the master cylinder pressure Pmc and the target differential pressure determined by the gate-out valve drive command. Estimated foil cylinder pressure.

  The liquid amount conversion unit 110 converts the estimated wheel cylinder pressure into the liquid amount Q actually supplied to the wheel cylinder W / C, and outputs it to the liquid amount deviation calculation unit 106. That is, in the motor drive control, feedback control is electronically performed based on the target fluid amount Q * and the actual fluid amount Q in order to avoid unnecessary motor drive and to ensure brake pedal feeling.

FIG. 5 is a flowchart for realizing boost control.
In step S1, the initial value of each variable is set. Here, each variable represents various flags used for control, a timer value, a calculation coefficient, and the like.
In step S2, detection values of various sensors are read.
In step S3, the presence or absence of a driver's brake pedal operation is detected from the signal of the brake switch BP.

In step S4, it is determined from the relationship between the detected master cylinder pressure Pmc and the estimated wheel cylinder pressure which control to increase / hold / depressurize. When the pressure is increased, the motor drive control is performed, and otherwise, the motor drive control is stopped or prohibited (corresponding to the hydraulic pressure source control means and the holding means).
In step S5, the target motor speed N * is determined and an operation command is output.
In step S6, an opening command for the gate-in valve 2 is determined and an operation command is output.
In step S7, the target current I * is determined from the target differential pressure of the gate-out valve 3, and a drive command is output.

In step S8, the wheel cylinder pressure is estimated from the operation commands of the motor M and the valve.
In step S9, the end of boost control is determined.

  Next, the operation of the boost control based on the control flow will be described. FIG. 5 is a control determination map for performing the control determination shown in step S4. On the coordinate plane formed by the master cylinder pressure Pmc and the wheel cylinder pressure, one of pressure increase, hold, and pressure reduction is selected from the master cylinder pressure Pmc and the wheel cylinder pressure.

  For example, when the master cylinder pressure Pmc is P1 and the wheel cylinder pressure is P2, the point A shown on the coordinate plane of the control determination map belongs to the pressure increase, so the pressure increase control is selected. For example, when the hydraulic pump is a plunger pump, the holding region is set wider than the amount of decrease in the master cylinder pressure Pmc at the pump discharge position. In the map shown in FIG. 6, a first predetermined value for switching between increasing pressure and holding is linearly set according to the master cylinder pressure Pmc, and a second predetermined value for switching between holding and depressurization is the first predetermined value. Is set to a smaller value.

  FIG. 7 is a time chart when the boost control is performed, and FIG. 8 is a description of the transition of the master cylinder pressure Pmc and the wheel cylinder pressure shown in the time chart of FIG. 7 on the control determination map.

  When the driver operates the brake pedal at time t11, it is determined that the brake switch is turned on by the brake operation state determination shown in step S3, and the boost control is started. At this time, in step S4, pressure increase control is selected from the relationship between the master cylinder pressure Pmc and the wheel cylinder pressure.

  When the pressure increase control is selected, in step S5, the target motor rotational speed N * is determined from the master cylinder pressure Pmc and the target hydraulic pressure P * that is the target wheel cylinder pressure, and a motor operation command is output. Next, in step S6, the gate-in valve 2 is opened. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, when increasing the pressure, the wheel cylinder pressure is estimated from the master cylinder pressure Pmc, the motor rotation speed N, and the gate-out valve current I *. Since brake fluid is supplied from the hydraulic pump to the wheel cylinder W / C, the wheel cylinder pressure increases.

  When the master cylinder pressure Pmc decreases at time t12, holding control is selected from the relationship between the master cylinder pressure Pmc and the wheel cylinder pressure in step S4. When the holding control is selected, the motor M is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, since the amount of wheel cylinder fluid does not change during holding, the previous wheel cylinder pressure is continuously set. Since the control is such that the hydraulic pressure in the wheel cylinder W / C does not change during holding, the gate-out valve current I * is set to a higher fixed value so that the gate-out valve 3 is securely closed. You may control.

  When the master cylinder pressure Pmc increases at time t13, the pressure increase control is selected again in step S4. The processing from step 5 to S8 is the same as that from time t11 to t12, and will not be described.

  When the master cylinder pressure Pmc decreases at time t14, the holding control is selected in step S4. The processing from step S5 to S8 is the same as that from time t12 to t13, and will be omitted.

  When the master cylinder pressure Pmc further decreases at time t15, pressure reduction control is selected from the relationship between the master cylinder pressure Pmc and the wheel cylinder pressure in step S4. When the pressure reduction control is selected, the motor M is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, at the time of pressure reduction, the wheel cylinder pressure is estimated from the master cylinder pressure Pmc and the gate-out valve current. Since the brake fluid of the wheel cylinder W / C is discharged to the master cylinder side, the wheel cylinder pressure decreases.

  As described above, in the brake booster control apparatus according to the first embodiment, the wheel cylinder pressure is increased when the master cylinder pressure Pmc is increased, and the wheel cylinder pressure is decreased when the master cylinder pressure Pmc is decreased. When the amount of decrease in the master cylinder pressure Pmc is small, the boost control is executed by maintaining the wheel cylinder pressure.

  As described above, in the brake booster control apparatus according to the first embodiment, the following effects can be obtained.

  (1) The master cylinder M / C, the wheel cylinder W / C, and the electromagnetic attraction force based on the current value that is the control amount that is placed between the master cylinder M / C and the wheel cylinder W / C. A gate-out valve 3 that operates so that the differential pressure ΔP between the master cylinder M / C and the wheel cylinder W / C matches, a pressure sensor that detects the master cylinder pressure Pmc that the driver intends to brake, A target hydraulic pressure calculation unit 101 that calculates a target hydraulic pressure P * of the wheel cylinder W / C that is a target braking force based on the master cylinder pressure Pmc, and a gate that calculates a target current value I * based on the differential pressure ΔP An out-valve target current calculation unit 103 and a pump P that is a hydraulic pressure source capable of generating a hydraulic pressure equal to or higher than the target hydraulic pressure P * between the wheel cylinder W / C and the gate-out valve 3 are provided.

  Therefore, it is possible to automatically control the differential pressure between the master cylinder and the wheel cylinder only by giving a control amount based on the differential pressure ΔP in a feedforward manner without finely controlling the hydraulic pressure source. Accordingly, the wheel cylinder pressure can be controlled to a desired target hydraulic pressure even though the master cylinder and the wheel cylinder are not shut off. For example, even if a low-priced pump that is not very accurate or a low-priced motor that drives this pump is used, it can automatically absorb pump pulsation, motor over-rotation, etc. A stable boosting action can be obtained.

  (2) The gate-out valve 3, which is a mechanical feedback mechanism, has an opening based on a balance between the electromagnetic attraction force of the coil 3a, the force Fmc corresponding to the master cylinder pressure Pmc, and the force Fwc corresponding to the wheel cylinder pressure. It is a solenoid valve to be determined, and the value of the current supplied to the coil 3a is controlled.

  Therefore, a mechanical feedback mechanism can be easily achieved using an existing solenoid valve.

  (3) Control was performed using a pressure sensor PMC that detects the hydraulic pressure of the master cylinder M / C. That is, in controlling the differential pressure ΔP of the gate-out valve 3, it is possible to detect the hydraulic pressure closest to the control target, and loss due to friction, etc., compared to detecting a value near the brake pedal BP. Control accuracy can be improved without erroneous detection. In addition, the pressure generated in the master cylinder is lower than that of a brake system using a conventional negative pressure booster or hydraulic pressure booster, so it is possible to use a small pressure sensor with a small pressure detection range. Thus, the brake booster control device can be reduced in size, and the resolution at the time of inputting the pressure sensor signal to the control unit CU can be made finer, so that the pressure detection accuracy can be improved.

  (4) The hydraulic pressure source is a pump that sucks the brake fluid of the master cylinder M / C and discharges it to the wheel cylinder side. Therefore, the brake pedal stroke of the driver can be ensured without providing a stroke simulator or the like.

  (5) An electronic feedback control for estimating the hydraulic pressure of the wheel cylinder and controlling the drive amount of the pump P so that the target hydraulic pressure P * and the estimated foil cylinder hydraulic pressure coincide with each other is provided. Therefore, useless pump driving can be suppressed, and brake fluid discharged to the master cylinder side can be suppressed, so that the brake pedal feeling can be improved.

  (6) Braking force detection means for detecting or estimating the braking force of the vehicle and a hydraulic pressure source only when the detected braking intention is equal to or greater than a first predetermined value set according to the detected or estimated braking force And a hydraulic pressure source control means for supplying hydraulic pressure from. Specifically, the pump P is driven only when it is determined that the pressure is increased in the map shown in FIG. 6, and the driving of the pump P is prohibited otherwise. Therefore, it becomes possible to drive the pump P only in a scene that requires a boosting action, and energy loss can be suppressed.

  (7) When the detected braking intention is smaller than the first predetermined value and larger than the second predetermined value set as a value smaller than the first predetermined value, the holding means for holding the pressure of the wheel cylinder Was established. Specifically, the gate-out valve 3 is operated so as to maintain the pressure of the wheel cylinder when it is determined to be retained in the map shown in FIG.

  Therefore, even if the brake pedal is increased, the wheel cylinder pressure is reduced even if the master cylinder pressure Pmc is reduced by operating the hydraulic pump to suck the brake fluid from the master cylinder M / C. It is possible to maintain the braking force without reducing the.

  (8) The braking intention detection means is means for detecting the hydraulic pressure of the master cylinder, and the braking force detection means is means for detecting or estimating the hydraulic pressure of the wheel cylinder.

  In other words, it is possible to accurately detect the pressure generated by the driver's brake pedal operation without being affected by the friction of the input rod or master cylinder, and by operating the hydraulic pump and the pressure control valve based on the detected pressure, the wheel The cylinder pressure, that is, the braking force can be generated with high accuracy.

  (9) The pump P, which is a hydraulic pressure source, the pipeline 13 (first brake circuit) connecting the master cylinder M / C and the wheel cylinder W / C, and the pipeline 13 and the discharge side of the pump P are pipelines. A pipe line 12 (second brake circuit) connected via a check valve that allows only the flow to the side 13, and a normal cylinder provided on the pipe 13 and closer to the master cylinder than the connection position of the pipe line 12. An open gate-out valve 3, a pipeline 11 (third brake circuit) on the pipeline 13 that connects the position on the master cylinder side of the gate-out valve 3 and the suction side of the pump P, and a pipeline 13 The normally open solenoid-in valve 4 provided on the wheel cylinder side above the connection position of the pipe line 12 and the position of the pump P on the pipe line 13 and on the wheel cylinder side from the solenoid-in valve 4 Pipe line 14 (fourth brake) connecting the suction side With the road), and the solenoid-out valve 5 normally closed provided on the pipe 14, a reservoir 16 provided on the suction side of the pump P than the solenoid-out valve 5 a on line 14.

  That is, the circuit configuration is the same as that of a brake unit that can achieve existing vehicle behavior control and anti-skid control. In this existing configuration, it is possible to propose a brake booster control device only by controlling the differential pressure of the gate-out valve 3, and cost reduction and vehicle mountability can be improved by eliminating the negative pressure booster and the like. In addition, vehicle behavior control can be proposed.

  Here, the vehicle behavior control means that the actual yaw rate of the vehicle is detected by a yaw rate sensor or the like, the target yaw rate is obtained by using a steering angle sensor or the like, and a specific wheel is set so that the target yaw rate and the actual yaw rate coincide This is a known technique for applying a braking force only to the. Anti-skid control calculates a slip ratio or the like from the relationship between the pseudo vehicle speed and the wheel speed, and uses the solenoid-in valve 4 or the solenoid-out valve 5 so that the slip ratio becomes a desired value. This is a known technique for controlling pressure increase / decrease.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. FIG. 9 is a characteristic diagram showing the relationship between the master cylinder pressure Pmc and the brake pedal depression force. Solid line MC1 is a characteristic of a brake system with a small invalid pedaling force, and solid line MC2 is a characteristic of a brake system with a large invalid pedaling force. This characteristic is determined by design values such as the pedal ratio of the brake pedal and the piston diameter of the master cylinder.

  FIG. 10 is a control determination map for performing the control determination shown in step S4. As shown in FIG. 9, after replacing the master cylinder pressure Pmc with the brake pedal depression force, the pressure is increased and maintained from the brake pedal depression force and the wheel cylinder pressure in the coordinate plane formed by the brake pedal depression force and the wheel cylinder pressure. Select one of the reduced pressures. For example, when the brake pedal depression force F1 and the wheel cylinder pressure P2 are set, the point B shown on the coordinate plane of the control determination map belongs to the holding, so the holding control is selected.

  FIG. 11 is a time chart of the boost control in the second embodiment. FIG. 12 shows the transition of the brake pedal depression force and the wheel cylinder pressure shown in the time chart of FIG. 11 on the control determination map. FIG. 13 is a diagram showing the relationship of the wheel cylinder pressure to the brake pedal depression force, which is the result of performing the boost control.

  When the driver operates the brake pedal at time t21, it is determined that the brake switch is turned on by the brake operation state determination shown in step S3, and the boost control is started. At this time, in step S4, the brake pedal depression force is calculated from the master cylinder pressure Pmc, and the pressure increase control is selected from the relationship between the brake pedal depression force and the wheel cylinder pressure.

  When the pressure increase control is selected, in step S5, the wheel cylinder pressure, which is the target hydraulic pressure, and the target motor rotation speed are determined from the brake pedal depression force, and a motor operation command is output. Next, in step S6, the gate-in valve 2 is opened. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, at step S8, when the pressure is increased, the wheel cylinder pressure Pwc is estimated from the master cylinder pressure Pmc, the motor rotation speed N, and the gate-out valve current I. Since brake fluid is supplied from the hydraulic pump to the wheel cylinder, the wheel cylinder pressure increases.

  When the master cylinder pressure Pmc decreases at time t22, the brake pedal depression force is calculated from the master cylinder pressure Pmc in step S4, and the holding control is selected from the relationship between the brake pedal depression force and the wheel cylinder pressure.

  When the holding control is selected, the motor is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output. Next, in step S8, since the amount of wheel cylinder fluid does not change during holding, the previous wheel cylinder pressure is continuously set.

  When the master cylinder pressure Pmc increases at time t23, the pressure increase control is selected again in step S4. The processing from step 5 to S8 is the same as that from time t21 to t22, and will be omitted.

  When the master cylinder pressure Pmc decreases at time t24, the holding control is selected in step S4. The processing from step S5 to S8 is the same as that from time t22 to t23, and is therefore omitted.

  When the master cylinder pressure Pmc further decreases at time t25, the brake pedal depression force is calculated from the master cylinder pressure Pmc in step S4, and the pressure reduction control is selected from the relationship between the brake pedal depression force and the wheel cylinder pressure.

  When the pressure reduction control is selected, the motor M is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, the wheel cylinder pressure is estimated from the master cylinder pressure Pmc and the gate-out valve current I during pressure reduction. Since the brake fluid of the wheel cylinder is discharged to the master cylinder side, the wheel cylinder pressure decreases.

  As described above, in the brake booster control apparatus according to the second embodiment, the brake pedal depression force is calculated from the detected master cylinder pressure Pmc, and the relationship between the brake pedal depression force and the wheel cylinder pressure is managed. Execute control.

  As a result, the brake force required by the driver can be generated by managing the relationship between the brake pedal depression force and the wheel cylinder pressure, so that the feeling is good.

  FIG. 14 is a characteristic diagram showing the relationship between the wheel cylinder pressure and the pedal stroke in the brake booster control apparatus according to the third embodiment. The solid line WC1 is a wheel cylinder that generates a large pressure with a small amount of liquid, and the solid line WC2 is a wheel cylinder that requires a large amount of liquid to generate the same pressure as the solid line WC1. This characteristic is determined by the fluid amount-pressure characteristic of the wheel cylinder and the piston diameter of the master cylinder.

  FIG. 15 is a control determination map for performing the control determination shown in step S4. On the coordinate plane formed by the brake pedal depression force and the pedal stroke, one of pressure increase, holding, and pressure reduction is selected from the brake pedal depression force and the pedal stroke. For example, when it is the brake pedal depression force F1 and the pedal stroke L2, the point C shown on the coordinate plane of the control determination map belongs to the pressure reduction, so the pressure reduction control is selected.

  FIG. 16 is a time chart of the boost control of the third embodiment. FIG. 17 describes the brake pedal depression force and pedal stroke transition shown in the time chart of FIG. 16 on the control determination map. FIG. 18 shows the result of boost control of a wheel cylinder having the characteristics shown in FIG. 14 according to the time chart of FIG.

  When the driver operates the brake pedal at time t31, it is determined that the brake switch is turned on by the brake operation state determination shown in step S3, and the boost control is started.

  At this time, in step S4, the brake pedal depression force is calculated from the master cylinder pressure Pmc, the pedal stroke is calculated from the estimated wheel cylinder pressure, and the pressure increase control is selected from the relationship between the brake pedal depression force and the pedal stroke.

  When the pressure increase control is selected, in step S5, the target motor rotation speed N * is determined from the brake pedal depression force and the wheel cylinder pressure, and a motor operation command is output. Next, in step S6, the gate-in valve 2 is opened. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, when the pressure is increased, the wheel cylinder pressure is estimated from the master cylinder pressure Pmc, the motor rotation speed N, and the gate-out valve current I. Since brake fluid is supplied from the hydraulic pump to the wheel cylinder W / C, the wheel cylinder pressure increases.

  When the master cylinder pressure Pmc decreases at time t32, the holding control is selected from the relationship between the brake pedal depression force and the pedal stroke in step S4.

  When the holding control is selected, the motor M is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output. Next, in step S8, since the amount of wheel cylinder fluid does not change during holding, the previous wheel cylinder pressure is continuously set.

  When the master cylinder pressure Pmc increases at time t33, the pressure increase control is selected again in step S4. The processing from step 5 to S8 is the same as that from time t31 to t32, and is therefore omitted.

  When the master cylinder pressure Pmc decreases at time t34, the holding control is selected in step S4. The processing from step S5 to S8 is the same as that from time t32 to t33, and is therefore omitted.

  When the master cylinder pressure Pmc further decreases at time t35, the brake pedal depression force is calculated from the master cylinder pressure Pmc in step S4, the pedal stroke is calculated from the estimated wheel cylinder pressure, and the pressure is reduced from the relationship between the brake pedal depression force and the pedal stroke. Select control.

  When the pressure reduction control is selected, the motor M is stopped in step S5. Next, in step S6, the gate-in valve 2 is closed. Next, in step S7, the gate-out valve current I * is calculated from the target hydraulic pressure P * and the master cylinder pressure Pmc, and the duty ratio is output.

  Next, in step S8, the wheel cylinder pressure is estimated from the master cylinder pressure Pmc and the gate-out valve current I during pressure reduction. Since the brake fluid of the wheel cylinder W / C is discharged to the master cylinder side, the wheel cylinder pressure decreases.

  As described above, in the brake booster control apparatus according to the third embodiment, the brake pedal depression force is calculated from the detected master cylinder pressure Pmc and the pedal stroke is calculated from the estimated wheel cylinder pressure. The boost control is executed by managing the relationship with the pedal stroke.

  Thereby, by managing the relationship between the brake pedal depression force and the pedal stroke, the stroke amount of the pedal relative to the brake pedal depression force can be made variable, and without changing the design of the brake feeling member etc. It can be realized only by changing the software.

  The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  For example, instead of estimating the wheel cylinder pressure, a pressure sensor may be provided and directly detected. At this time, the processing in step S8 is not necessary, and an accurate pressure can be detected, so that the braking force according to the driver's operation of the brake pedal can be realized more accurately.

1 is a hydraulic circuit diagram of a brake system to which a brake boost control device of Embodiment 1 is applied. It is a block diagram showing the control structure in the controller of the brake booster control apparatus of Example 1. 2 is a gate-out valve current-differential pressure characteristic map in Example 1. FIG. 1 is a schematic diagram illustrating a configuration of a gate-out valve according to Embodiment 1. FIG. 3 is a flowchart for realizing boost control according to the first embodiment. 3 is a control determination map for determining pressure increase, holding, and pressure reduction from a master cylinder pressure and a wheel cylinder pressure according to the first embodiment. 3 is a time chart for performing a boost control to a wheel cylinder pressure corresponding to the master cylinder pressure of the first embodiment. It is a figure showing the transition of the control judgment map when performing boost control to the wheel cylinder pressure corresponding to the master cylinder pressure of Example 1. It is a characteristic view showing the relationship between the master cylinder pressure of Example 1 and a brake pedal depression force. 7 is a control determination map for determining pressure increase, holding, and pressure reduction from the brake pedal depression force and wheel cylinder pressure according to the second embodiment. It is a time chart which carries out boost control to the wheel cylinder pressure corresponding to the brake pedal depression force of Example 2. FIG. It is a figure showing the transition of the control judgment map when performing boost control to the wheel cylinder pressure corresponding to the brake pedal depression force of Example 2. It is a figure showing the result of carrying out boost control to the wheel cylinder pressure corresponding to the brake pedal depression force of Example 2. FIG. It is a characteristic view showing the relationship between wheel cylinder pressure and pedal stroke in Example 3. 10 is a control determination map for determining pressure increase, hold, and pressure decrease from the brake pedal depression force and pedal stroke in the third embodiment. It is a time chart which manages and boost-controls so that it may become a pedal stroke corresponding to the brake pedal depression force in Example 3. FIG. It is a figure showing the transition of a control judgment map when managing and boosting control so that it may become a pedal stroke corresponding to the brake pedal depression force in Example 3. FIG. It is a figure showing the result of managing and boosting control so that it may become a pedal stroke corresponding to the brake pedal depression force in Example 3. FIG.

Explanation of symbols

1 Input Rod 2 Gate In Valve 3 Gate Out Valve 3a Coil 3b Movable Element 3c Valve Body 4 Solenoid In Valve 5 Solenoid Out Valve 6-10 Check Valve
M motor
BP brake pedal
BS brake switch
CU control unit
M / C Master cylinder P Pump
PMC pressure sensor
W / C wheel cylinder

Claims (10)

A master cylinder that generates pressure in response to the driver's brake operation;
A wheel cylinder provided on each wheel for generating braking force on the wheel;
An electromagnetic valve disposed between the master cylinder and the wheel cylinder, the opening degree of which is determined based on a balance between the electromagnetic attraction force of the coil, the force corresponding to the master cylinder pressure, and the force corresponding to the wheel cylinder pressure When,
Braking intention detection means for detecting the driver's braking intention;
Target braking force calculating means for calculating a target braking force based on the braking intention;
Control amount calculating means for calculating a current value for energizing the coil based on a difference between the braking intention and the target braking force;
A hydraulic pressure source capable of generating a hydraulic pressure greater than the target braking force between the wheel cylinder and the solenoid valve;
A brake booster control device comprising: In the brake booster control device according to claim 1,
The brake boosting control device, wherein the braking intention detection means is a pressure sensor that detects a hydraulic pressure of the master cylinder. In the brake booster control device according to claim 1 or 2,
The brake booster control device according to claim 1, wherein the hydraulic pressure source is a pump that sucks brake fluid from the master cylinder and discharges the brake fluid to the wheel cylinder side. In the brake booster control device according to claim 3,
Hydraulic pressure estimating means for detecting or estimating the hydraulic pressure of the wheel cylinder;
Electronic feedback control means for controlling the drive amount of the pump so that the target braking force and the detected or estimated hydraulic pressure coincide with each other;
A brake booster control device comprising: In the brake booster control device according to any one of claims 1 to 4,
Braking force detection means for detecting or estimating the braking force of the vehicle;
Hydraulic pressure source control means for supplying hydraulic pressure from the hydraulic pressure source only when the detected braking intention is not less than a first predetermined value set according to the detected or estimated braking force;
A brake booster control device comprising: In the brake booster control device according to claim 5,
When the detected braking intention is smaller than the first predetermined value and larger than a second predetermined value set as a value smaller than the first predetermined value, the pressure of the wheel cylinder is maintained. A brake booster control device comprising holding means for operating the electromagnetic valve. In the brake booster control device according to claim 5 or 6,
The brake boosting control device according to claim 1, wherein the braking intention detecting means is means for detecting a hydraulic pressure of the master cylinder, and the braking force detecting means is means for detecting or estimating the hydraulic pressure of the wheel cylinder. In the brake booster control device according to claim 5 or 6,
The brake boost control device according to claim 1, wherein the braking intention detection means is means for detecting a driver's brake pedal depression force, and the braking force detection means is a means for detecting or estimating a hydraulic pressure of a wheel cylinder. In the brake booster control device according to claim 5 or 6,
The brake boost control device according to claim 1, wherein the braking intention detecting means is means for detecting a driver's brake pedal depression force, and the braking force detection means is a means for detecting a brake pedal stroke. In the brake booster control device according to any one of claims 1 to 9,
A pump that is the hydraulic pressure source;
A first brake circuit connecting the master cylinder and the wheel cylinder;
A second brake circuit that connects the first brake circuit and the discharge side of the pump via a check valve that only allows flow to the first brake circuit side;
A gate-out valve on the first brake circuit and provided on the master cylinder side of the connection position of the second brake circuit and functioning as the solenoid valve;
A third brake circuit on the first brake circuit for connecting a position closer to the master cylinder than the gate-out valve and a suction side of the pump;
A solenoid-in valve provided on the wheel cylinder side above the connection position of the second brake circuit on the first brake circuit;
A fourth brake circuit on the first brake circuit for connecting a position closer to the wheel cylinder than the solenoid-in valve and a suction side of the pump;
A solenoid out valve provided on the fourth brake circuit;
A reservoir provided on the suction side of the pump above the solenoid out valve on the fourth brake circuit;
A brake booster control device comprising:

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