JP2009292209A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device that achieves a size-reduction without imparting a sense of incongruity to an operator. <P>SOLUTION: When a high-pressure request is made, a correlation is changed such that vehicle deceleration becomes large in a correlation between brake pedal stepping force and the vehicle deceleration among correlations as references. A hydraulic pump and a pressure control valve are controlled so as to keep the correlation as a reference in the correlation between a brake pedal stroke amount and the vehicle deceleration. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to the technical field of brake control devices.

Conventionally, for example, a technique described in Patent Document 1 is known as a technique for changing a relationship (hereinafter referred to as brake pedal characteristics) among a preset brake pedal depression force, a brake pedal stroke amount, and vehicle deceleration. In Patent Document 1, when the vehicle deceleration with respect to the brake stroke amount is greatly changed, the reaction force applying device controls the reaction force with respect to the brake stroke amount, thereby maintaining the relationship between the brake stroke amount and the brake pedal depression force. .
JP 2004-50905 A

  In the brake control device described in Patent Document 1 described above, it is necessary to separately provide a reaction force applying device, and there is a problem that the size of the brake control device increases.

  The present invention has been made paying attention to the above problems, and it is an object of the present invention to provide a brake control device that can be downsized without giving the driver a sense of incongruity.

  In order to achieve the above object, in the first invention, when a high pressure request is made, the correlation is changed to a correlation that increases the vehicle deceleration in the correlation between the brake pedal depression force and the vehicle deceleration, among the reference correlations, and Therefore, the hydraulic pump and the pressure control valve are controlled so as to maintain a reference correlation between the brake pedal stroke amount and the vehicle deceleration.

  In the second invention, when a high pressure request is made, the correlation between the brake pedal depression force and the vehicle deceleration is changed to a correlation that increases the vehicle deceleration, and the brake pedal depression force The hydraulic pump and the pressure control valve are controlled so as to maintain a reference correlation with the brake pedal stroke amount, and the pressure increasing valve and the pressure reducing valve are controlled so as to suppress the brake fluid flowing into the rear wheel side wheel cylinder. It was decided to.

  Therefore, the uncomfortable feeling accompanying the change in the brake pedal characteristics can be suppressed while securing the vehicle deceleration.

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

  FIG. 1 is a system diagram illustrating the entire system of the brake control device according to the first embodiment. The brake control apparatus according to the first embodiment includes a hydraulic unit 31 that is mounted with a motor, a pump, a solenoid valve, a sensor, and the like, interposed between a master cylinder M / C and a wheel cylinder W / C, and the hydraulic unit. 31 is an electromechanically integrated brake device that is integrally formed with a control unit CU that is attached to 31 and 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.

  The control unit CU is a signal from the pressure sensor PMC that detects the master cylinder pressure, a signal from the longitudinal acceleration sensor GS that detects the longitudinal acceleration of the vehicle, a signal from the wheel speed sensor VS that detects the wheel speed of each wheel, and an obstacle ahead of the vehicle. The signal of the laser radar device LR that detects an object or the like is input. The hydraulic unit 31 is controlled based on these various sensor signals.

[Configuration of brake piping]
FIG. 2 is a hydraulic circuit diagram of a brake system to which the brake 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. The input rod 1 is provided with a stroke sensor SS that detects a brake pedal stroke amount.

  Master cylinder M / C and the suction side of pumps PP and PS (hereinafter referred to as pump P) are connected by conduits 11P and 11S (hereinafter referred to as conduit 11). 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 pipe lines 12P and 12S (hereinafter referred to as pipe line 12). 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 pipeline 13, gate-out valves 3 </ b> P and 3 </ b> S (hereinafter referred to as gate-out valves 3) that are normally open solenoid 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), and the pipeline 14 and pipeline 15 merge between the check valve 8 and the reservoir 16. To do. Each pipe line 14 is provided with solenoid-out valves 5FL, 5RR, 5FR, 5RL, which are normally closed solenoid valves.

FIG. 3 is a flowchart showing a control process for changing the brake pedal characteristics.
In step S1, detection values of various sensors are read.
In step S2, a brake pedal depression force (hereinafter referred to as pedal depression force) Fpedal is calculated from the master cylinder pressure PMC detected in step S1 (hereinafter referred to as master pressure PMC) based on the following equation (1).
Formula (1)
Fpedal = k × A × PMC

  Here, k is the pedal ratio of the brake pedal, and A is the piston cross-sectional area of the master cylinder M / C. The pedal ratio is a ratio between the distance between the fulcrum and the action point and the distance between the fulcrum and the force point. The fulcrum is the position where the brake pedal BP is pivotally attached to the vehicle body side, the power point is the pedal part where the driver actually depresses the brake pedal, and the action point is the part connecting the brake pedal BP and the input rod 1 It is.

  In step S3, the reference deceleration Gbase is calculated from the pedal depression force Fpedal calculated in step S2. Here, the reference deceleration Gbase is determined by design values such as the wheel cylinder W / C, the brake rotor effective diameter, and the vehicle weight.

  In step S4, the deceleration requested by the driver is determined from the master pressure PMC and the master pressure change rate ΔPMC detected in step S1, and the first requested deceleration is calculated based on the first requested deceleration calculation map shown in FIG. Greq1 is determined. Note that the pedal pressure is not limited to the master pressure PMC detected in step S1, but may be the pedal depression force Fpedal calculated in step S2, or the pedal depression force detected by attaching a depression force sensor to the brake pedal.

  In step S5, the risk of collision is determined from the inter-vehicle distance, relative speed, and relative acceleration detected by the laser radar device LR in step S1, and the second required deceleration Greq2 corresponding to the risk of collision is determined. decide. The detection is not limited to the laser radar device, but may be detected by attaching a millimeter wave radar or a stereo camera.

  In step S6, brake characteristics are determined based on Gbase, Greq1, and Greq2. Details will be described in the brake characteristic determination flow shown in FIG.

  In step S7, a target brake pedal stroke amount (hereinafter referred to as a target stroke amount) Sreq that realizes the brake characteristics determined in step S6 is calculated. Details will be described in the target stroke calculation flow shown in FIG.

In step S8, the brake pedal stroke amount S (hereinafter referred to as stroke amount S) is calculated from the pressure PWC of the wheel cylinder (hereinafter referred to as wheel pressure PWC) based on the equation (2).
Formula (2)
S = k × {f _f (PWC _FL ) + f _f (PWC _FR ) + f _r (PWC _RL ) + f _r (PWC _RR )} / A

Here, f _f and f _r is a function for calculating the amount of the brake fluid, respectively the wheel cylinder from the wheel pressure PWC of the front wheels and the rear wheels are determined by the design value of the wheel cylinder.

  The wheel pressure PWC may be a sensor value detected by attaching a pressure sensor to the wheel cylinder of each wheel, or may be an estimated value calculated from drive signals of the motor M and various valves. The stroke may be directly detected by attaching a stroke sensor to the brake pedal BP, and is not particularly limited.

In step S9, based on the deceleration GS detected by the longitudinal acceleration sensor GS in step S1, the second required deceleration Greq2 calculated in step S5, the target stroke amount Sreq calculated in step S7, and the stroke amount S calculated in step S8. Drive the motor and valve. Details will be described in the motor / valve drive flow shown in FIG.
In step S10, the end of the brake characteristic change control is determined. When continuing, the process is repeated again from step S1, and when it is finished, this control flow is ended.

  FIG. 4 is a map for calculating the first required deceleration Greq1 from the master pressure PMC and the master pressure change rate ΔPMC. When the master pressure change rate ΔPMC is small, Greq1 = Gbase, and the first required deceleration rate Greq1 larger than Gbase is calculated as the master pressure change rate ΔPMC increases. Thereby, even if the force which depresses a brake pedal is weak, since the deceleration according to the depressing speed can be generated, the effect of a brake assist can be acquired.

  In other words, when there is a reference correlation between the brake pedal depression force, the brake pedal stroke amount, and the vehicle deceleration set in advance, the correlation in which the vehicle deceleration G increases in the correlation between the brake pedal depression force F and the vehicle deceleration G. Will be changed. This is simultaneously synonymous with changing the correlation between the brake pedal stroke amount S and the brake pedal depression force F so that the brake pedal depression force F becomes smaller.

  FIG. 5 is a flowchart for determining the brake characteristic mode MODE based on Gbase, Greq1, and Greq2.

  In step S601, it is determined whether the first required deceleration Greq1 and the second required deceleration Greq2 are large or small. When it is determined that Greq1 ≧ Greq2, the process proceeds to step S602. Otherwise, the process proceeds to step S603.

  In step S602, it is determined whether the first required deceleration Greq1 and the reference deceleration Gbase are large or small. When it is determined that Greq1> Gbase, the process proceeds to step S604 and MODE = 1 is set. Otherwise, the process proceeds to step S605 and MODE = 0 is set.

  In step S603, it is determined whether the second required deceleration Greq2 and the reference deceleration Gbase are large or small. When it is determined that Greq2> Gbase, the process proceeds to step S606, and MODE = 2 is set. Otherwise, the process proceeds to step S607 and MODE = 0 is set.

  FIG. 6 is a table showing the relationship between the brake characteristic mode MODE and the brake characteristic. When the brake pedal depression force is F, the brake pedal stroke amount is S, and the vehicle deceleration is G, the reference correlation between the brake pedal depression force, the brake pedal stroke amount, and the vehicle deceleration is described as F-S-G characteristics. When MODE = 0, the F-S-G characteristics are not changed. When MODE = 1, the FG characteristic (FS characteristic) is changed while maintaining the S-G characteristic. In MODE = 2, the F-G characteristics (S-G characteristics) are changed while maintaining the F-S characteristics. Details will be described later.

FIG. 7 is a flowchart showing the target stroke amount calculation processing.
In step S701, a brake characteristic mode is determined. When it is determined that MODE = 1, the process proceeds to step S702, and the target stroke amount Sreq is calculated from the first required deceleration Greq1 based on the SG characteristics preset by the vehicle. Otherwise, the process proceeds to step S703, and the target stroke amount Sreq is calculated from the pedal depression force Fpedal based on the FS characteristic preset by the vehicle.

FIG. 8 is a flowchart showing the motor / valve driving process.
In step S901, it is determined whether or not the brake characteristic mode is MODE = 1. If MODE = 1 is determined, the process proceeds to step S903. Otherwise, the process proceeds to step S902.

  In step S902, it is determined whether or not the brake characteristic mode is MODE = 2. If MODE = 2 is determined, the process proceeds to step S908. Otherwise, the process proceeds to step S913.

In step S903, motor control is performed. Specifically, the rotational speed of the motor M is controlled by feeding back the deviation between the target stroke amount Sreq and the stroke amount S. When Sreq> S, the motor speed is increased, and when Sreq <S, the motor speed is decreased.
In step S904, the gate-in valve 2 is controlled to be opened.
In step S905, the valve opening degree of the gate-out valve 3 is controlled by feeding back the deviation between the target stroke amount Sreq and the stroke amount S. When Sreq> S, the gate-out valve 3 is controlled in the valve closing direction, and when Sreq <S, the gate-out valve 3 is controlled in the valve opening direction.
In step S906, the rear wheel solenoid in valves 4RL and 4RR are not driven (opened), and the process proceeds to step S907.
In step S907, the rear wheel solenoid out valves 5RL and 5RR are not driven (closed).

In step S908, motor control is performed. Specifically, the rotational speed of the motor M is controlled by feeding back the deviation between the target stroke amount Sreq and the stroke amount S.
In step S909, the gate-in valve 2 is controlled to be opened.
In step S910, the valve opening degree of the gate-out valve 3 is controlled by feeding back the deviation between the target stroke amount Sreq and the stroke amount S.
In step S911, the deviation between the second required deceleration Greq2 and the longitudinal acceleration GS is fed back to control the valve opening of the rear wheel solenoid in valves 4RL and 4RR. When Greq2> GS, the rear wheel solenoid in valves 4RL and 4RR are controlled in the valve closing direction, and when Gerq2 <GS, the rear wheel solenoid in valves 4RL and 4RR are controlled in the valve opening direction to return to the rear wheel wheel cylinder. Increase inflow of brake fluid.
In step S912, the deviation between the second required deceleration Greq2 and the longitudinal acceleration GS is fed back to control the valve opening time of the rear wheel solenoid out valves 5RL and 5RR. When Greq2> GS, the rear wheel solenoid out valves 5RL and 5RR are closed.

In step S913, the motor is not driven.
In step S914, the gate-in valve 2 is not driven (closed state).
In step S915, the gate-out valve 3 is not driven (opened).
In step S916, the rear wheel solenoid valves 4RL and 4RR are not driven (opened).
In step S917, the rear wheel solenoid out valves 5RL and 5RR are not driven (closed state).

In step S918, the front wheel solenoid in valves 4FL and 4FR are not driven (opened).
In step S919, the front wheel solenoid out valves 5FL and 5FR are not driven (closed state).

  During the brake characteristic change control, the gate-in valve 2 and the gate-out valve 3 are not repeatedly opened and closed, the gate-in valve 2 is opened, the brake fluid is discharged by the pump P, and the opening of the gate-out valve 3 Is used to control the excess amount to return to the master cylinder. Thereby, since pressure pulsation generated by opening and closing of the valve can be reduced, the pedal feel can be improved. Furthermore, since the feedback system can be configured to control the motor rotation speed and the gate-out valve opening, the target stroke amount Sreq can be realized with high accuracy.

  FIG. 9 is a time chart when the relationship between the stroke amount and the pedal effort is smoothly changed while maintaining the relationship between the stroke amount and the deceleration in accordance with the brake pedal operation speed of the driver in the brake control device. 10 is a diagram showing a transition on the FS characteristic diagram, and FIG. 11 is a diagram showing a transition on the SG characteristic diagram.

  When the driver operates the brake pedal BP at time t11, a master pressure PMC corresponding to the pedal depression force Fpedal is generated, and the pressure is transmitted to the wheel cylinder. Since the pedal depression speed is low, there is no need to change the pedal characteristics, and the motor M and the valve are in a non-driven state.

  When the driver's brake pedal operation speed increases at time t12, a first required deceleration Greq1 larger than the reference deceleration Gbase is calculated in step S4. In step S6, MODE = 1 is set as the brake characteristic mode. That is, the process proceeds from S601 to S602 to S604.

  Next, in step S7, a target stroke amount Serq for realizing the first required deceleration Greq1 is calculated based on the relationship between the stroke amount and the deceleration set in advance by the vehicle. That is, the process proceeds from S701 to S702. Next, in step S8, the stroke amount S is calculated from the wheel pressure PWC of each wheel, the pedal ratio k, and the master cylinder piston cross-sectional area A according to equation (2). Next, in step S9, the gate-in valve 2 is controlled to be in an open state, and the deviation between the target stroke amount Sreq and the stroke amount S is fed back to control the motor rotation speed and the gate-out valve opening. That is, the process proceeds from S901 → S903 → S904 → S905 → S906 → S907 → S918 → S919.

  The target stroke amount Sreq is realized by opening the gate-in valve 2 and sucking brake fluid from the master cylinder with the pump P, controlling the opening degree of the gate-out valve 3 and circulating the surplus to the master cylinder side. .

  When the driver weakens the operation force of the brake pedal BP at time t13, the first required deceleration Greq1 and the reference deceleration Gbase become equal in step S4, and MODE = 0 is selected as the brake operation mode in step S6. In step S9, the motor and valve are not driven, and the brake characteristic change control is terminated.

  That is, by reducing the pedal depression force with respect to the stroke amount, even a driver with weak force can depress the brake pedal, and a large deceleration can be obtained. Furthermore, since the relationship between the stroke amount and the deceleration is maintained, the uncomfortable feeling due to the change in the brake characteristics can be eliminated.

  FIG. 12 shows the degree of collision risk based on the distance between the preceding vehicle detected by the laser radar device LR, the relative speed, and the relative acceleration, and the relationship between the pedal pressing force and the stroke amount, while maintaining the relationship between the pedal pressing force and the stroke amount. It is a time chart in the case of changing a relationship smoothly. FIG. 13 is a diagram showing a transition on the FS characteristic diagram, and FIG. 14 is a diagram showing a transition on the S-G characteristic diagram.

  When the driver operates the brake pedal BP at time t21, a master pressure corresponding to the pedal depression force is generated, and the pressure is transmitted to the wheel cylinder. Since there is no risk of collision with the preceding vehicle, there is no need to change the pedal characteristics, and the motor and valve are in a non-driven state.

  If it is determined at time t22 that there is a risk of collision with the preceding vehicle, a second required deceleration Greq2 larger than the reference deceleration Gbase is calculated in step S5. At this time, in step S6, MODE = 2 is selected as the brake characteristic. That is, the process proceeds from step S601 to S603 to S606. In step S7, the target stroke amount Sreq corresponding to the pedal depression force Fpedal is calculated based on the FS characteristic predetermined by the vehicle. That is, the process proceeds from step S701 to S703. Further, in step S8, the stroke amount S is calculated from the wheel pressure PWC of each wheel, the pedal ratio k, and the master cylinder piston cross-sectional area A by the equation (2).

  Next, in step S9, the gate-in valve 2 is controlled to be in an open state, and the deviation between the target stroke amount Sreq and the stroke amount S is fed back to control the motor rotation speed and the gate-out valve opening. When the motor speed increases, the amount of brake that moves from the master cylinder side to the wheel cylinder side increases, and the stroke amount S increases. Further, when the gate-out valve 3 is controlled in the valve opening direction, the brake amount that moves from the master cylinder side to the wheel cylinder side increases, and the stroke amount decreases.

  Furthermore, the deviation between the second required deceleration Greq2 and the longitudinal acceleration sensor GS is fed back to control the opening degree of the rear wheel solenoid in valves 4RL and 4RR, and the opening time of the rear wheel solenoid out valves 5RL and 5RR is controlled.

  When the rear wheel solenoid out valves 5RL and 5RR are opened, the brake fluid in the rear wheel wheel cylinder flows into the reservoir 16 and the rear wheel wheel pressure is reduced. Since the brake fluid in the reservoir 16 that has flowed out is pumped to the front wheel cylinder side by the pump P, the front wheel foil pressure increases. In the first embodiment, the front wheel can generate a larger braking force than the rear wheel, so even if the amount of fluid is the same, supplying a large amount to the front wheel can increase the deceleration as a result. Can do. In general, the front wheel has a larger contact area between the brake pad and the brake rotor than the rear wheel, so that a large braking force can be generated even with the same amount of fluid.

  If it is determined that the risk of collision with the preceding vehicle has disappeared at time t23, the second required deceleration Greq2 and the reference deceleration Gbase become equal in step S5, and the brake operation mode MODE = 0 is set in step S6. In step S9, the motor and valve are not driven, and the brake characteristic change control is terminated.

  As described above, when MODE = 2 is selected, the vehicle deceleration G is increased with respect to the brake pedal depression force F. Therefore, even when the brake pedal BP is operated with a constant depression force, the vehicle deceleration is performed. G can be increased to guide the vehicle in a safer direction. Furthermore, in order to maintain the relationship between the brake pedal depression force F and the brake pedal stroke amount S, the stroke amount does not change even if the vehicle deceleration G is increased. Therefore, the uncomfortable feeling due to the change in the brake pedal characteristics can be suppressed.

  In addition, when the FG characteristic is set to increase the vehicle deceleration G in the FG characteristic, if the FS characteristic is to be maintained, the vehicle deceleration G is reduced while the amount of brake fluid supplied from the master cylinder side to the wheel cylinder side is the same. A means to raise is needed. At this time, the total braking force of the four wheels can be increased by moving the brake fluid in the rear wheel side wheel cylinder into the front wheel side wheel cylinder.

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

    (1) A brake pedal BP that operates in response to a driver's brake operation, a master cylinder M / C that generates a master pressure PMC by the operation of the brake pedal BP, and a wheel that is controlled by wheel pressure. The wheel cylinder W / C that generates power, the first required deceleration calculation map that is a high pressure request means that requires higher pressure than the wheel pressure generated only by the driver's brake operation, and the brake from the master cylinder M / C A pump P that sucks liquid and discharges it to the wheel cylinder side, a gate-out valve 3 that is provided between the master cylinder M / C and the discharge part of the pump P and controls the wheel pressure, and a preset brake pedal A brake pedal characteristic change control process that changes a correlation that serves as a reference for the pedal force, the brake pedal stroke amount, and the vehicle deceleration. When the request is made, the correlation between the brake pedal depression force F and the vehicle deceleration G is changed to a correlation in which the vehicle deceleration G becomes larger in the reference correlation, and the brake pedal stroke amount S and the vehicle deceleration G are changed. The pump P and the gate-out valve 3 are controlled so as to maintain a reference correlation.

  Therefore, increasing the vehicle deceleration G with respect to the brake pedal depression force F is synonymous with decreasing the brake pedal depression force F with respect to the brake pedal stroke amount S. Therefore, even a driver with weak power can depress the brake pedal BP, and a large vehicle deceleration can be obtained. Furthermore, since the relationship between the brake pedal stroke amount S and the vehicle deceleration G is maintained, the uncomfortable feeling due to the change in the brake characteristics can be suppressed.

  (2) A brake pedal BP that operates according to the driver's brake operation, a master cylinder M / C that generates a master pressure by the operation of the brake pedal BP, and a front wheel that generates a first braking force for a predetermined amount of fluid Side wheel cylinder W / C (FR, FL), rear wheel cylinder W / C (RR, RL) that generates a braking force smaller than the first braking force for a given amount of fluid, and driver's brake Second required deceleration calculation process (step S5), which is a high pressure request means that requires a pressure higher than the wheel cylinder pressure generated only by operation, and brake fluid is drawn from the master cylinder M / C and discharged to the wheel cylinder side A gate-out valve 3 for controlling the wheel pressure, a gate-out valve 3 and a rear wheel side wheel cylinder W / C (RR, RL) to control the foil pressure Solenoid in valves 4RR, RL to be operated, and solenoid out valves 5RR, 5RL, which are provided between the rear wheel side wheel cylinder W / C (RR, RL) and the suction part of the pump P and control the wheel pressure, are preset. A brake pedal characteristic change control process for changing a reference correlation between the brake pedal depression force F, the brake pedal stroke amount S, and the vehicle deceleration G, and the brake pedal characteristic change control process has a high pressure request. When the correlation between the brake pedal depression force F and the vehicle deceleration G is changed to a correlation in which the vehicle deceleration G becomes larger in the correlation between the reference and the correlation between the brake pedal depression force F and the brake pedal stroke amount S The pump P and the gate-out valve 3 are controlled so as to maintain a reference correlation, and the brake fluid flowing into the rear wheel side wheel cylinder W / C (RR, RL) is suppressed. The renoid in valves 4RR and RL and the solenoid out valves 5RR and 5RL were controlled.

  Therefore, since the vehicle deceleration G is increased with respect to the brake pedal depression force F, the vehicle deceleration can be increased even when the brake pedal is operated with a constant depression force, and the vehicle can be guided in a safer direction. Furthermore, in order to maintain the relationship between the brake pedal depression force F and the brake pedal stroke amount S, the brake fluid in the rear wheel cylinder is moved into the front wheel cylinder, thereby increasing the total braking force of the four wheels. Can be made. By utilizing this characteristic, even if the vehicle deceleration G is increased, the brake pedal stroke amount S does not change. Therefore, the uncomfortable feeling due to the change in the brake pedal characteristics can be suppressed.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes within the scope of the present invention are included in the present invention. It is.

  In the first embodiment, the vehicle deceleration G is increased by changing the brake pedal characteristics based on the relative distance, relative speed, and relative acceleration with respect to the preceding vehicle or obstacle. Alternatively, the risk of the vehicle may be determined from vehicle-to-vehicle communication, position information by GPS, or the like. Safety can be improved because danger can be detected in advance.

  Further, in the time chart shown in FIG. 12, the relationship between the brake pedal depression force and the vehicle deceleration is smoothly changed while maintaining the relationship between the brake pedal depression force and the brake stroke amount according to the risk of collision. However, a slight vibration may be generated in the brake pedal BP by driving the motor / valve so as to quickly change the brake pedal characteristics. Since the driver can be made aware of the danger of collision via the brake pedal BP, safety can be improved.

1 is a system diagram of a brake control device of Embodiment 1. FIG. 1 is a hydraulic circuit diagram of a brake system to which a brake control device of Example 1 is applied. 3 is a flowchart illustrating a control process for changing the brake pedal characteristics according to the first embodiment. 3 is a first required deceleration calculation map according to the first embodiment. 4 is a flowchart for determining a brake characteristic mode MODE based on Gbase, Greq1, and Greq2 of the first embodiment. It is a table | surface which shows the relationship between the brake characteristic mode of Example 1, and a brake characteristic. 3 is a flowchart illustrating target stroke amount calculation processing according to the first embodiment. 3 is a flowchart illustrating a motor / valve driving process according to the first embodiment. 3 is a time chart illustrating a brake pedal characteristic change control process according to the first embodiment. FIG. 6 is a diagram illustrating transitions on the FS characteristic diagram of Example 1. It is a figure showing the transition on the S-G characteristic figure of Example 1. FIG. 3 is a time chart illustrating a brake pedal characteristic change control process according to the first embodiment. FIG. 6 is a diagram illustrating transitions on the FS characteristic diagram of Example 1. FIG. 6 is a diagram illustrating a transition on an S-G characteristic diagram of Example 1.

Explanation of symbols

1 Input Rod 2 Gate In Valve 3 Gate Out Valve 4 Solenoid In Valve 5 Solenoid Out Valve
M motor
BP brake pedal
CU control unit
M / C Master cylinder P Pump
PMC pressure sensor
W / C wheel cylinder

Claims (2)

A brake pedal that operates according to the driver's brake operation;
A master cylinder that generates a master cylinder pressure by operating the brake pedal;
A wheel cylinder provided on each wheel and generating a braking force on the wheel by the wheel cylinder pressure;
High pressure request means for requesting a pressure higher than the wheel cylinder pressure generated only by the driver's brake operation;
A hydraulic pump that draws in brake fluid from the master cylinder and discharges it to the wheel cylinder;
A pressure control valve that is provided between the master cylinder and the discharge part of the hydraulic pump and controls a wheel cylinder pressure;
Brake pedal characteristic changing means for changing a correlation that is a reference of a preset brake pedal depression force, a brake pedal stroke amount, and vehicle deceleration;
With
The brake pedal characteristic changing means, when the high pressure request is made, changes to a correlation in which the vehicle deceleration becomes larger in the correlation between the brake pedal depression force and the vehicle deceleration among the reference correlations, and The brake control device, wherein the hydraulic pump and the pressure control valve are controlled so as to maintain the reference correlation in the correlation between the brake pedal stroke amount and the vehicle deceleration. A brake pedal that operates according to the driver's brake operation;
A master cylinder that generates a master cylinder pressure by operating the brake pedal;
A front wheel cylinder that generates a first braking force for a predetermined amount of fluid;
A rear wheel cylinder that generates a braking force smaller than the first braking force for a predetermined amount of fluid;
High pressure request means for requesting a pressure higher than the wheel cylinder pressure generated only by the driver's brake operation;
A hydraulic pump that draws in brake fluid from the master cylinder and discharges it to the wheel cylinder;
A pressure control valve that is provided between the master cylinder and the discharge part of the hydraulic pump and controls a wheel cylinder pressure;
A pressure increasing valve provided between the pressure control valve and the rear wheel side wheel cylinder, for controlling a wheel cylinder pressure;
A pressure reducing valve, which is provided between the rear wheel side wheel cylinder and the suction part of the hydraulic pump, and controls the wheel cylinder pressure;
Brake pedal characteristic changing means for changing a correlation that is a reference of a preset brake pedal depression force, a brake pedal stroke amount, and vehicle deceleration;
With
The brake pedal characteristic changing means, when the high pressure request is made, changes to a correlation in which the vehicle deceleration becomes larger in the correlation between the brake pedal depression force and the vehicle deceleration among the reference correlations, and The hydraulic pump and the pressure control valve are controlled so as to maintain the reference correlation in the correlation between the brake pedal depression force and the brake pedal stroke amount, and the brake fluid flowing into the rear wheel side cylinder is suppressed. A brake control device that controls the pressure increasing valve and the pressure reducing valve.

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